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FOUNDATIONS     OF     PSYCHOLOGY 


WILEY  PUBLICATIONS  IN  PSYCHOLOGY 

FOUNDATIONS  OF  PSYCHOLOGY' 

By  Edwin  G.  Boring,  Herbert  S.  Langfeld,  and  Harry  P.  Weld 
INTRODUCTION  TO  PSYCHOLOGY 

By  Edwin  G.  Boring,  Herbert  S.  Langfeld,  and  Hakky  P.  Weld 
SOCIAL  PSYCHOLOGY 

By  Daniel  Katz  and  Richard  L.  Schanck 
HEARING— ITS  PSYCHOLOGY  AND  PHY'SIOLOGY 

By  S.  Smith  Stevens  and  Hallowell  Davis 
MANUAL  OF  PSYCHIATRY  AND  MENTAL  HYGIENE.    Seveidh  Edition 

By  Aaron  J.  Rosanoff 
STATISTICAL   METHODS   IN   BIOLOGY',   MEDICINE,  AND   PSYCHOL- 
OGY.    Fourth  Edition 

By  C.  B.  Davenport  and  Merle  P.  Ekas 
MOTIVATION  OF  BEHAVIOR 

By  P.  T.  Young 
PSY'CHOLOGY— A  FACTUAL  TEXTBOOK 

By  Edwin  G.  Boring,  Herbert  S.  Langfeld,  and  Hakry  P.  Weld 
PSYCHOLOGY  IN  BUSINESS  AND  INDUSTRY 

By  John  G.  Jenkins 


HERBERT  S.  LANGFELD 
Advisory  Editor 

APPLIED  EXPERIMENTAL  PSYCHOLOGY 

By  Alphonse  Chapanis,  W.  R.  Garner,  and  C.  T.  Morgan 
THEORY'  OF  HEARING 

By  Ernest  Glen  Wever 
PSY'CHOLOGICAL  STATISTICS 

By  QuiNN  McNemar 
METHODS  OF  PSYCHOLOGY 

T.  G.  Andrews,  Editor 
THE  PSYCHOLOGY  OF  EGO-INVOLVEMENTS 

By  MuzAFER  Sherif  and  Hadley  Cantril 
MANUAL  OF  CHILD  PSYCHOLOGY 

Leonard  Carmichael,  Editor 
EMOTION  IN  MAN  AND  ANIMAL 

By  P.  T.  Y'oung 

UNCONSCIOUSNESS 

By  James  Grier  Miller 
THE  PSYCHOLOGY  OF  PERSONAL  ADJUSTMENT.     Second  Edition 

By  Fred  McKinney 
THE  PSYCHOLOGY  OF  SOCIAL  MOVEMENTS 

By  Hadley  Cantril 


FOUNDATIONS     OF 


PSYCHOLOGY 


EDITED   BY 

Edwin  Garrigues  Boring 


HARVARD  UNIVERSITY 


Herbert  Sidney  Langfeld 

PRINCETON  UNIVERSITY 

Harry  Porter  Weld 


CORNELL  UNIVERSITY 


1948 

JOHN     WILEY     AND     SONS,     INC.,     NEW     YORK 
CHAPMAN      AND      HALL,      LIMITED,      LONDON 


Copyright,  1948 

BY 

John  Wiley  &  Sons,  Inc. 


All  Rights  Reserved 

i?his  book  or  any  part  thereof  must  noi 
be  reproduced  in  any  Jorm  wiil.oui 
'he.  vtrilten  permission  of  the  publisher. 


FIl-TII    PIUNTINC,    M.W,    1951 


PRINTED    IN    THE    UNITED    STATES    OF    AMERICA 


CONTRIBUTORS 


ANNE  ANASTASI 


Fordham  University 


CARL  I.  HOVLAND 


Yale  University 


M.  E.  BITTERMAN 


EDWIN  G.  BORING 


HADLEY  CANTRIL 


Cornell   University 


Harvard   University 


Princeton   University 

LEONARD  CARMICHAEL 


LEO  P.  CRESPI 


Tufts  College 


Princeton  University 


FORREST  L.  DIMMICK 
U.  S.  Naval  Medical   Research  Laboratory 
at  New  London 

FRANK  A.  GELDARD 

University  of  Virginia 


DONALD  R.  GRIFFIN 


Cornell  University 


WILLIAM  A.  HUNT 

Northwestern   University 

DONALD  W.  MacKINNON 

University  of  California 

CLIFFORD  T.  MORGAN 

The  Johns  Hopkins  University 


EDWIN  B.  NEWMAN 


CARL  PFAFFMANN 


T.  A.  RYAN 


Harvard   University 


Brown   University 


Cornell  University 


LAURANCE  F.  SHAFFER 

Teachers  College,  Columbia   University 

CARROLL  L.  SHARTLE 

Ohio  State  University 


S.  SMITH  STEVENS 

Harvard  University 


THE  strongest  evidence  of  the  rapid  advance  of  psychology  is  the  need  of 
frequent  revisions  of  textbooks.  It  is  nine  years  since  our  last  book,  Intro- 
duction to  Psychology,  was  published.  In  the  meantime  we  have  had  a  long  war 
and  a  victory  which  psychological  research  helped  attain.  In  this  wartime  re- 
search much  new  and  valuable  knowledge  came  into  being.  In  addition  there 
has  been  the  more  normal  acquisition  of  facts  as  well  as  a  clearly  distinguishable 
change  in  point  of  view.  This  advance  in  our  science  had  to  be  covered  in  a 
revision,  but  we  soon  found  that  instead  of  a  revision  we  were  going  to  have  a 
book  so  nearly  new  that  it  needed  a  new  title.  And  so  we  present  here  the  third 
book  that  has  appeared  under  our  combined  editorship. 

To  describe  in  detail  the  changes  in  this  book  over  the  last  would  be  to  tie- 
scribe  a  large  part  of  its  contents.  We  must  confine  ourselves  to  indicating  a 
few  of  the  more  significant  differences.  It  is  about  twice  as  large  as  the 
Introduction  of  1939.  Approximately  80  per  cent  of  the  material  is  either  new 
or  freshly  described.  What  has  been  taken  from  the  previous  book  has  been 
re-edited.  There  are  eighteen  contributors,  of  whom  fifteen  are  new.  A  num- 
ber of  new  chapters  have  been  added,  two  of  which  introduce  the  student  to 
problems  of  personal  adjustment.  Some  of  the  material  of  the  old  chapters  has 
been  differently  distributed  among  the  chapters  of  this  book.  Some  of  the 
topics  have  been  given  more  detailed  treatment;  no  material  of  importance 
has  been  omitted.  There  are  also  a  large  number  of  new  illustrations,  and 
many  of  the  old  ones  have  been  redrawn.  In  selecting  the  illustrations  we 
have  intended  to  include  only  those  which  we  feel  would  help  the  student 
to  understand  the  text. 

The  order  of  the  chapters  is  completely  changed.  In  our  first  book  ^ve  hcUl 
to  the  conventional  arrangement  of  sensation  at  the  beginning  and  thought  ami 
personality  at  the  end.  In  the  second  book  \\'e  reversed  this  order.  \\'e  had  a 
principle  in  mind  with  each  book:  synthesis  in  the  first  order,  analysis  in  the 
second;  but  we  must  confess  to  a  certain  dependence  on  trial  and  error.  Now. 
with  the  trials  and,  we  hope,  the  errors  past,  and  giving  attention  to  the  opnuons 
expressed  by  some  teachers  of  introductory  courses,  we  present  Avhat  is  partly  a 
compromise   between   the   two   orders   and   partly   a   reflection   of  psychology's 


Preface 

changed  orientation.  In  1948  the  important  thing  about  the  organism  is  not 
that  it  is  conscious,  btit  that  it  reacts  to  stimuhition.  So  .we  are  having  the  book 
start  with  response— its  nature,  its  mechanics,  its  maturation,  its  dependence  on 
moti\e.  After  that  the  student  is  prepared  to  study  learning  as  change  in  the 
organism's  response  repertoire,  and  then  perception  as  a  form  of  the  organism's 
adjustment  to  its  physical  environment.  Such  an  approach  leads  on  naturally 
to  the  study  of  the  facts  of  individual  difference,  to  the  problems  of  human 
efficiency  and  personal  adjustment,  and  finally  to  the  understanding  of  attitudes 
and  social  relations. 

The  amount  of  necessary  editing  has  varied  considerably.  Some  chapters 
remain  very  much  as  they  were  presented  by  the  collaborator.  Some  had  to  be 
rewritten.  In  several  instances  we  transferred  material  from  one  chapter  to 
another.  Some  material  was  deleted,  some  new  material  added.  For  the  sake 
of  unity  and  style  all  chapters  had  to  undergo  at  least  some  changes  by  the 
editorial  pen. 

From  this  explanation  the  reader  will  see  the  reason  for  the  wording  of  our 
acknowledgment  of  the  authorship  of  each  of  the  chapters.  We  as  editors  must 
assume  responsibility  for  any  errors  that  may  have  occurred  in  the  text.  We  wish, 
on  the  other  hand,  to  give  full  credit  to  the  collaborators  for  their  contributions 
to  this  book  and  to  thank  them  for  their  generous  cooperation,  which  we  realize 
was  motivated  by  their  loyalty  to  their  science. 

We  are  also  grateful  to  our  former  collaborators,  all  of  whom  helped  to  make 
this  book  possible.  They  are  C.  W.  Bray,  J.  G.  Beebe-Center,  "Warner  Brown, 
D.  W.  Chapman,  K.  M.  Dallenbach,  H.  B.  DeSilva,  S.  Feldman,  Norman  Fred- 
eriksen,  George  Humphrey,  Daniel  Katz,  Carney  Landis,  R.  B.  MacLeod,  J.  A. 
McGeoch,  C.  C.  Miles,  D.  McL.  Purdy,  M.  A.  Tinker,  E.  G.  Wever  and  M.  J. 
Zigler.     We  note  a  special  debt  to  Dr.  Wever  for  his  continued  advice. 

We  acknowledge  an  especial  debt  of  gratitude  to  the  secretarial  staff  of  the 
Harvard  Psychological  Laboratories,  who  retyped  entirely  the  much-edited  manu- 
script; to  Elizabeth  MacLeod,  who  administered  the  retyping  and  its  proofing; 
to  Robert  S.  Harper  of  Harvard  University,  who,  with  some  assistance  from 
Mabel  Mills,  prepared  the  figures  for  our  publisher's  artist;  and  to  Helen  Orr 
of  Princeton  University,  who  lent  us  her  very  considerable  editorial  experience 
in  reading  both  manuscript  and  proofs. 

E.  G.  B. 
H.  S.  L. 
H.  P.  W. 

January  11,  19-lS 


N  T  E  N 


1.  The  Nature  of  Psychology  1 

Behavior  and  Consciousness:  Behavior;  Consciousness.  Origins  of 
Scientific  Psychology.  Schools  of  Psychology:  Introspective  Psy- 
chology; Functional  Psychology;  Behaviorism;  Gestalt  Psychology; 
Modern  Psychology.  Fields  of  Psychology.  Scientific  Method:  Ex- 
periment; Control;  Hypothesis.     Definitions.     References. 

2.  The  Response  Mechanism  19 

Differentiation  of  the  Response  Mechanism:  The  Stimulus;  Evolu- 
tion of  the  Response  Mechanism;  The  Effectors;  Endocrine  Ef- 
fectors; The  Receptors;  The  Adjusters.  Structure  and  Function 
of  Neurons:  Stimulation;  Mechanisms  of  Intensity;  Synaptic  Con- 
nections. Structure  of  the  Nervous  System:  The  Efferent  Peripheral 
Nervous  System;  The  Autonomic  Nervous  System.  Functions  of 
the  Brain:  Localization  in  the  Brain.    References. 

3.  Response  ^^ 

Varieties  of  Behavior:  Locomotion  and  Manipulation;  Tropisms 
and  Reflexes;  Conditioned  Response;  The  Reflex  Circle;  Condi- 
tioned Voluntary  Responses.  Motivated  Behavior:  Instinct;  Needs 
and  Activity;  Problem-Solving  Behavior;  Covert  Behavior;  Set  and 
Readiness.  Voluntary  and  Automatic  Behavior:  The  Will;  Volun- 
tary Control  of  Movement;  Reflexes,  Conditioned  Responses  and 
Voluntary  Acts;  Voluntary  Acts  and  Learning.  Acts  and  Ideas: 
Ideomotor  Action;  Empathy;  Suggestion;  Hypnotism.  Reaction: 
Reaction  Time;  Simple  Reactions;  Sensory  and  Motor  Reactions; 
Discrimination  and  Choice  Reactions;  Word  Reactions;  Practical 
Use  of  Reaction  Experiments.    References. 

4.  Growth  and  Development  64 

Growth,  Development  and  Maturation:  Conditions  of  Growth; 
Integration  and  Maturation;  The  Nervous  System  as  Integrator. 
Growth  and  Development  before  Birth:  The  Beginning  of  Human 
Growth;  Rates  of  Prenatal  Growth.  Growth  after  Birth:  Types  of 
Growth;  Maturity.  Maturation  at  Birth:  The  Neonate  in  a  New 
Environment;  Reflexes  in  the  Neonate;  Maturation  of  the  Recep- 
tors; Maturation  of  Emotion.    Maturation  after  Birth:  The  Matura- 


Contents 

tion  of  Adaptive  Behavior;  Norms  of  Early  Development;  Matura- 
tion of  Ability  to  Learn;  Maturation  of  Speech  and  Language. 
Adolescence,  Adulthood  and  Old  Age:  Puberty  and  Adolescence; 
Adulthood;  Old  Age;  The  Trajectory  of  Life.     References. 

5.  Feeling  and  Emotion  90 

Pleasantness  and  Unpleasantness:  Affective  Value  of  Stimuli;  The 
Relativity  of  Hedonic  Tone;  Dependence  of  Learning  upon  He- 
donic  Tone;  Hedonism.  Emotion:  Visceral  Reactions  and  the 
Autonomic  Nervous  System;  Direct  Action  of  the  Nervous  System; 
Peripheral  Response  and  Expressive  Behavior;  Facial  Expression  in 
Emotion;  The  Startle  Pattern;  The  Emotional  Consciousness;  Emo- 
tion and  Learning;  The  Genetic  Development  of  Emotion.  Specific 
Emotions:  Smiling,  Laughing  and  Crying;  Fear;  Anger.  The  Meas- 
urement of  Emotion:  The  Galvanic  Skin  Response;  Blood  Pressure 
Changes;  Rating  Scales;  Observational  and  Psychoanalytic  Tech- 
niques; Questionnaire  Methods.  Disorders  of  Emotion:  Patho- 
logical Conditions;  Functional  Disorders;  Psychosomatic  Medicine. 
Hygiene  of  Emotion.    References. 

6.  Motivation  112 

Needs:  Distinction  among  Needs;  Needs,  Structure  and  Environ- 
ment. The  Physiological  Basis  of  Behavior:  Hunger  Drive;  Sex 
Drive;  Other  Drives;  Behavior  and  Structure;  Needs  for  Particular 
Foods;  Derived  Needs.  Behavior  as  Dependent  on  the  Environ- 
ment: Relation  of  Environment  to  Needs;  Incentives;  Cultural 
Determination  of  Needs.  Definition  of  Need.  Measurement  of 
Needs:  Obstruction  Method;  Learning  Method.  Some  Effects  of 
Need:  Effect  on  Perception  and  Imagination;  Effect  on  Sensitivity; 
Effect  on  Persistence;  Frustration  Tolerance.  Individual  Differ- 
ences in  Respect  of  Needs.     References. 

7.  Learning  138 

Associative  Learning:  Conditioning;  Factors  Affecting  Condition- 
ing; Conditioned  Emotional  Responses;  Anticipatory  Function 
of  Conditioned  Responses;  The  Law  of  Contiguity.  Trial-and- 
Error  Learning:  The  Law  of  Effect.  The  Role  of  Motivation  in 
Learning.  The  Effect  of  Practice:  Plateaus;  Insight;  Physiological 
Limits;  The  Law  of  Frequency.  Other  Factors  Affecting  the  Effi- 
ciency of  Learning:  The  Learner;  Kind  of  Material;  Distribution 
of  Practice;  Whole  or  Part  Learning;  Verbalization;  Active  Partici- 
pation; Recitation.  Acquisition  of  Skills:  Basic  Principles  in  the 
Acquisition  of  Skills.     References. 


Contenfs 

8.  Retention  and  Transfer  of  Learning  167 

Retention  and  Forgetting:  How  Retention  Is  Measured;  Individual 
Dirtercnces  in  Retention;  The  Exceptional  Memori/xr;  Retention  of 
Different  i  ypes  of  Material;  Retention  as  Affected  fjy  Original 
Learning;  Reminiscence.  Cause  of  Forgetting:  Retroactive  Inhi- 
bition; Alteration  of  Stimulating  Conditions;  Change  of  Set.  Un- 
learning: Overcoming  Fears;  Breaking  Habits.  Transfer  of  Learn- 
ing: Formal  Discipline;  A  Transfer  Experiment;  Transfer  within 
the  Same  Class;  Bilateral  Transfer;  Fransier  from  One  Class  to 
Another;  Positive  versus  Negative  Fransier.  Efficient  Study:  Moti- 
vation; Planning;  Reading  Habits;  Meaningfulness;  Active  Par- 
ticipation.   References. 

9.  Recollecting,  Imagining  and  Thinking  185 

Recollecting:  Eidetic  Images;  Recollection  and  Perception.  Re- 
liability of  Recollection:  Reliability  of  Testimony;  Changes  in 
Recollection  with  Lapse  of  Time;  Nature  of  Errors  in  Recollec- 
tion; Failures  of  Recollection.  Types  of  Recollection.  Imagining: 
Imagination  and  Perception.  Thinking:  Important  Tools  of 
Thinking;  Language;  Reading;  The  Problem  and  the  Set;  Trial- 
and-Error  and  Insight.  Incorrect  Thinking:  Fallacies;  Wishful 
Thinking;  Hunches;  Word  Fallacies;  Motivation;  Tacit  Assump- 
tions; Atmosphere  Effect;  Habitual  Methods  of  Attack;  Faulty 
Transfer  of  Method;  Individual  Differences.  How  to  Think.  Ref- 
erences. 

10.  Perception  215 

The  Definition  of  Perception.  Change  Is  the  Basis  of  Perception. 
Perception  Is  Selective.  Perceiving  Is  Organized.  What  Is  It  That 
We  Perceive?  The  Simplest  Perception— Figure  on  a  Ground.  Ob- 
jects Are  Our  Commonest  Perceptions.  The  Constancy  of  Objects: 
Size  Constancy;  Whiteness  Constancy;  General  Explanation  of  Con- 
stancy. The  Framework  of  Perception— Space.  The  Framework  of 
Perception— Time.  Temporal  Patterns:  Short  Intervals;  Rhythm. 
Orientation  in  Time.     References. 

11.  Sensation  and  Psychological  Measurement  250 

Sensation  Is  the  Core  of  Perception.  Stimulus  and  Attributes: 
Stimulus;  Attributes  of  Sensation;  Quality;  Intensity.  Psycho- 
physics:  Psychophysical  Problems  and  Methods.  Scales  of  Meas- 
urement. Statistics  and  Measurement:  Central  Tendency:  \'aria- 
bility.     Thresholds.     The  Weber  Fraction.     References. 


xii  Contents 

12.  Color 

Characteristics  of  Colors:  Color  Names;  Unique  Colors;  The  Color 
Equation;  The  Color  Pyramid;  Chromatic  and  Achromatic  Colors. 
The  Stimulus  to  Color:  Nature  of  the  Stimulus;  Dependence  of 
Color  on  Its  Stimulus;  Purity  and  Saturation;  Sensation  versus 
Stimulus.  Color  Mixture:  Laws  of  Mixture;  Methods  of  Mixture; 
Colorimetry.  Color  Phenomena:  Adaptation;  Afterimages;  Con- 
trast; Indirect  Vision;  Color  Blindness;  Night  Vision.  Physiology 
of  Color  Vision:  Duplexity  of  Retinal  Function.     References. 


269 


13.  Visual  Space  Perception 

Visual  Perception  of  the  Third  Dimension:  Implicit  Clues;  Motor 
Context;  Retinal  Disparity;  Stereoscopy.  Visual  Perception  of  Size: 
Perceived  Size  and  Perceived  Distance;  Perceived  Size  and  Sur- 
rounding Objects;  Visual  Acuity.  Visual  Perception  of  Movement: 
General  Conditions  for  Perceived  Movement;  Afterimages  of  Move- 
ment; Perceived  Movement  with  a  Moving  Stimulus;  Perceived 
Movement  with  Stationary  Stimuli.     References. 


297 


14.  Hearing 

Stimulus  for  Hearing:  Sound  Waves;  Simple  Waves  and  Complex 
Waves;  Fourier  Analysis;  Analysis  by  Resonance;  Sine  Waves;  Har- 
monics. Sounds— What  We  Hear.  Pitch:  Pitch  and  the  Sound 
Wave;  Pitch  Thresholds;  The  Scale  of  Pitch.  Loudness:  Loudness 
Thresholds;  The  Scale  of  Loudness.  Interaction  of  Stimuli:  Beats 
and  Combination  Tones;  Masking.  How  the  Ear  Works:  The 
Outer  Ear;  The  Middle  Ear;  The  Inner  Ear;  How  the  Cochlea 
Works.  Localization  of  Sounds:  Binaural  Clues;  Secondary  Clues. 
Deafness.  Music.  Communication:  Speech  Sounds;  Sound  Pattern 
in  Speech;  Perception  and  Speech.     References. 


313 


15.  Taste  and  Smell 

Taste,  Smell  and  the  Common  Chemical  Sense.  Taste:  Primary 
Tastes;  Sensitivity;  Adaptation;  Physiological  Effects.  Smell:  Pri- 
mary Odors;  Sensitivity;  Adaptation;  Physiological  Effects;  Odor 
Mixtures  and  Blends.     References. 


351 


16.  Somesthesis 

Cutaneous  Sensibilities:  The  Skin  and  Its  Receptors;  Exploration 
of  the  Skin  Surface.  Pressure  Sensitivity:  Perception  of  Vibration; 
Pressure  Adaptation;  Localization  of  Pressures;  Receptors  for  Pres- 


360 


Contents  xiii 

sure.  Pain  Sensitivity:  Pain  Adaptation;  Pathways  for  Pain;  Pain 
Receptors.  Temperature  Sensitivity:  Skin  Temperature:  Physio- 
logical Zero  and  Adaptation;  Paradoxical  Cold  and  'Heat';  Recep- 
tors for  Temperature.  Kinesthesis:  Kinesthetic  Receptors.  Organic 
Sensibility:  Hunger  and  Appetite;  Thirst.  Ecjuilibrium:  The  Semi- 
circular Canals;  Receptors  in  the  Sacs;  Adaptation  and  Habituation. 
References. 


17.  Topographical  Orientation  380 

The  Topographical  Schema:  Components  of  the  Schema;  Graphic 
Representation  of  the  Schema;  Extension  of  the  Schema  to  New 
Territory;  Nonvisual  Clues.  Sensory  Basis  of  Orientation:  Orienta- 
tion by  the  Blind;  Auditory  Perception  of  Obstacles;  Auditory 
Orientation  by  Bats;  Echolocation;  Other  Problems  of  Animal 
Orientation.  Migration  and  Homing:  The  Sensory  Basis  of  Mi- 
gration.    References. 

18.  Individual  Differences  393 

Measurement  of  Individual  Differences:  Characteristics  of  a  Psycho- 
logical Test;  Standardization;  Norms;  Reliability;  Validity;  The 
Correlation  Coefficient.  Intelligence  Testing:  The  Binet  Tests; 
Group  Testing;  Performance  and  Nonlanguage  Tests;  Testing  In- 
fants and  Preschool  Children;  Evaluation  of  Intelligence  Tests. 
Measurement  of  Special  Aptitudes:  Trait  Variability;  Factor  Analy- 
sis; Dynamic  Organization  of  Mental  Traits.  Measurement  of 
Personality  Characteristics:  What  Are  Personality  Tests?;  Construc- 
tion of  Personality  Tests;  Evaluation  of  Personality  Tests.  Distribu- 
tion of  Individual  Differences:  Frequency  Distributions;  Types; 
Constitutional  Types;  The  Subnormal  Person;  The  Genius.  Group 
Differences:  Sampling;  Psychological  Sex  Differences;  Are  There 
Racial  Differences?     References. 

19.  Heredity  and  Environment  436 

Fundamental  Concepts:  What  Is  Heredity?;  Popular  Misconcep- 
tions Regarding  Heredity;  Environment;  Structure  and  Function. 
The  Study  of  Hereditary  and  Environmental  Influences:  Selective 
Breeding;  Family  Resemblances;  Foster  Family  Relationships:  Evi- 
dence from  Maturation;  Effect  of  an  Unusual  Environment;  Effect 
of  Parents'  Socio-economic  and  Occupational  Status;  Urban,  Rural 
and  Regional  Influences;  Cross-comparisons  of  Cultural  and  Bio- 
logical Groups.  The  Heredity-Environment  Question— Present 
Status.     References. 


xiv  Contents 

20.  Efficiency  459 

Measurement  ol  Human  Efficiency:  Output— Evaluation  of  Per- 
formance; Input— Expenditure  of  Bodily  Resources;  Physiological 
Indicators  of  Effort  and  Fatigue;  Measuring  Efficiency  and  Fatigue 
by  Performance;  Laboratory  Tests  of  Efficiency;  Work  Decrement; 
Summary.  Methods  of  Working:  The  'Natural'  Way  versus  the 
'One  Best'  Way;  Motion  Study;  Time  Study;  Evaluation  of  Motion 
and  Time  Study.  The  Working  Environment:  Atmospheric  Condi- 
tions: Respiration;  Temperature  Regulation;  Illumination;  Noise. 
Rest  and  Sleep:  Hours  of  Work;  Rest  Periods;  Sleep.  Effects  of 
Common  Drugs:  Alcohol;  Tobacco;  Caffeine.  Job  Satisfaction. 
Accident  Control:  General  Causes  of  Accidents;  Accident  Prone- 
ness.     References. 

21.  Personality  487 

Psychological  Concepts  of  Personality:  Definitions  of  Personality; 
Personality  Types;  Personality  Traits.  Measurement  of  Person- 
ality: Informal  Diagnosis;  Rating  Methods;  Questionnaires;  Per- 
formance Tests;  Projective  Methods.  The  Origins  of  Personality. 
Biological  Factors  in  Personality:  Body  Chemistry  and  the  Endo- 
crine Glands;  Physique  and  Physical  Health;  The  Nervous  System. 
Influence  of  Culture  on  Personality.  Development  of  Personality: 
Infancy;  Childhood;  Adolescence;  Personality  in  Maturity.  Ref- 
erences. 

22.  Personal  Adjustment  51 1 

The  Adjustment  Process:  Motives  in  Adjustment;  Thwarting;  Ad- 
justment by  Trial  and  Error;  Adjustive  Solutions.  Responses  to 
Thwarting:  Constructive  Adjustments;  Substitute  Adjustments; 
Consciousness  in  Adjustment.  Typical  Adjustment  Mechanisms: 
Compensation;  Rationalization;  Identification;  Seclusiveness;  Fan- 
tasy; Repression;  Projection;  Regression;  Sublimation.  Conflict: 
An  Analysis  of  Conflicts;  Approach-Approach  Conflicts;  Avoidance- 
Avoidance  Conflicts;  Approach-Avoidance  Conflicts.  Experiments 
on  Conflict:  Conflicts  in  Cats;  Experimental  Neurosis;  Effects  of 
Conflict.  Common  Sources  of  Conflict:  Family  Conflicts;  Sex  Con- 
flicts; Other  Cultural  Conflicts.  Psychoneuroses:  Anxiety;  Phobias; 
Compulsions  and  Obsessions;  Ailment  Adjustments.  Psychoses: 
Organic  Psychoses;  Functional  Psychoses;  The  Treatment  of  the 
Psychoses.  Techniques  for  Readjustment:  Counseling  and  Psycho- 
therapy; Interpretation  of  Psychotherapy.  Mental  Hygiene:  Mental 
Hygiene  in  Childhood;  Mental  Hygiene  for  Adults.     References. 


Contents  xv 

23.  Vocational  Selection  546 

Criteria:  Criteria  of  Vocational  Success;  Choice  of  Criterion.  Job 
Analysis.  Nature  of  Occupations:  Dictionary  of  Occupations; 
Census  Classification;  Characteristics  of  Occupations.  Trade 
Knowledge  and  Performance:  Oral  Trade  Tests;  Performance 
Tests.  Vocational  Potentiality:  Intelligence;  Interests;  Other 
Measures.      Basic    Factors   in    Occupational   Skills.      References. 

24.  Attitudes  and  Opinions  560 

Social  Norms.  The  Process  of  Socialization:  Acceptance  of  Social 
Norms;  Suggestion;  Formation  of  Attitudes;  Emotional  Origin  of 
Attitudes.  Effects  of  Attitudes.  Development  of  the  Ego:  Effects  of 
Ego  Involvement;  The  Ego  and  Group  Loyalty.  Attitudes  and 
Social  Change:  The  Effects  of  Technology  on  Thought  and  Be- 
havior; Propaganda;  Techniques  of  Propaganda;  Receptivity  to 
Propaganda;  Social  Bias  of  Propaganda.  Measurement  of  Atti- 
tudes and  Opinions:  Sampling;  Accuracy;  Setting  the  Problems 
and  Questions;  Analysis  of  Results;  How  to  Poll.     References. 

25.  Social  Relations  of  the  Individual  589 

Primary  Social  Relations:  General  Functions  of  the  Family;  The 
Family  in  Relation  to  Social  Control;  Imitation;  Suggestion;  Iden- 
tification; Language;  Semantics.  The  Individual  in  Relation  to 
the  Assembled  Group:  Social  Facilitation  and  Social  Inhibition; 
Crowds  and  Mobs.  The  Individual  in  Relation  to  the  Dispersed 
Group:  Group  Attachment;  Group  Conception.  Leadership.  Re- 
lations between  Groups:  Socio-economic  Interest  Groups;  Social 
Participation  Groups.  Social  Prejudice:  Nature  of  Prejudice; 
Origin  of  Prejudice;  Motivations  for  Prejudice;  Rationalizations 
about  Prejudice;  Individual  Differences  in  Prejudice;  Elimination 
of  Prejudice.    References. 

Index  615 


^.k' 


CHAPTER 


1 


The  Nature  of  Psychology 


PSYCHOLOGY  is  the  study  of  human 
nature.  It  is  the  study  of  man,  man  as  a 
living  being,  acting  in  an  ever-changing 
world,  responding  to  things  and  events  and 
other  people.  If  you  know  what  man  is,  if 
you  know  the  full  answer  to  the  question 
about  the  nature  of  man,  then  you  know 
what  himian  nature  is  and  what  psychology 
comprises. 

The  single  person  is  the  psychological 
unit.  He  acts  more  or  less  consistently 
with  himself,  although  often  differently 
from  other  persons.  There  is,  moreover, 
a  great  deal  of  interaction  among  persons. 
They  act  together  in  groups:  families,  so- 
cieties, parties,  nations.  They  communi- 
cate with  one  another  by  language.  They 
talk  as  man  to  man,  and  also  as  author  to 
his  readers  or  statesman  to  his  radio  audi- 
ence. With  language  they  incite  each 
other  to  action.  The  mother  incites  her 
son  to  be  good.  The  propagandist  incites 
a  nation  to  accept  or  reject  a  government. 
There  is  always  a  good  deal  of  conflict 
between  persons  and  between  groups,  for 
the  same  people  get  incited  in  different 
directions  simultaneously.  Sometimes  they 
actually  get  pushed  around  or  made  to  go 
where  they  do  not  want  to  go,  but  mostly 
the  forces  of  social  interaction  are  ex- 
pressed by  words.  The  first  thing  we  note 
abotit  a  man  is  that  he  is  a  unit  in  a  com- 

This  chapter  was  prepared  by  Edwin 

1 


plex  field  of  social  relations.  It  is  the 
psychology  of  these  social  functions  that 
supplies  the  details  as  to  just  how  man 
fits  into  the  social  structure  and  how  he 
adjusts  to  it  or  resists  it. 

The  ftmdamental  nature  of  man  does 
not  appear,  however,  merely  in  his  rela- 
tion to  his  fellows.  We  have  also  to  con- 
sider him  as  a  single  individual.  \Vhile 
chemically  he  seems  to  be  only  an  active 
mass  of  protoplasm,  he  turns  out  to  have 
many  consistencies  of  behavior  Avhich  make 
up  what  is  called  his  personality.  His  par- 
ticular pattern  of  behavior  may,  ho^\e\er, 
vary  greatly  from  the  patterns  of  other 
men.  He  may  be  introverted  or  extraverted 
in  his  relation  to  his  ^vorld,  ascendant  or 
submissive  in  his  relation  to  his  felloA\-s. 
persistent  or  volatile  in  his  activities,  a 
radical  or  a  conservative  in  his  thought. 
He  may  have  a  high  or  low  level  of  aspira- 
tion in  his  motivation.  The  ntimber  of 
traits  and  attitudes  which  would  describe 
these  consistencies  of  mind  and  conduct  is 
enormous.  If  we  ask  why  men  differ  in  these 
various  respects,  we  learn  that  it  is  because 
of  their  differences  in  inheritance,  in  edu- 
cation, in  physiological  constitution,  in 
past  emotional  experience,  in  the  secre- 
tions of  their  endocrine  glands  and  in  a 
myriad  of  other   properties   of  this   acti\e 

G.  Borine  of  Hai-vard  University. 


The  Nature  of  Psychology 


mass  of  protoplasm,  which  is  a  man,  and 
^vhich  psychologists  call  the  organism. 

To  understand  why  man  acts  as  he  does 
in  different  circumstances,  psychology  has 
to  study  all  the  properties  of  this  organism. 
Just  what,  we  may  ask,  is  an  organism?  An 
organism  is  a  mass  of  protoplasm  that  re- 
sponds to  excitation.  It  has  certain  neces- 
sities for  response,  and  they  are  called  its 
needs.  Man  has  a  need  for  food,  and,  if 
we  keep  a  man  from  food,  he  will  be 
driven  to  seek  it  until  he  gets  it.  In  this 
way  a  need  unsupplied  creates  a  drive. 
Every  need  leads  to  a  drive  which  is  ter- 
minated by  the  satisfaction  of  the  need. 
Man  has  a  great  capacity  for  needs.  His 
primary  needs  become  differentiated,  and 
in  that  way  he  acquires  many  new  needs.  A 
child  may  need  not  only  food,  but  candy; 
a  youth  not  only  love,  but  good  clothes. 
Around  man's  needs  and  drives  centers  the 
psychology  of  his  motixmtion. 

Man's  emotions  are  closely  related  to  his 
needs.  In  his  need  for  self-preservation 
may  arise  his  emotion  of  fear.  In  his  sex- 
ual need  may  arise  his  emotion  of  love. 
Like  his  needs,  his  emotions  become  dif- 
ferentiated and  specific.  The  fear  of  in- 
sult and  the  love  of  music  are  important, 
useful,  acquired  emotions,  whereas  the  fear 
of  mice  and  the  love  of  liquor  are  acquired 
but  less  useful. 

Since  man  is  a  doer,  he  satisfies  his  needs 
by  doing  something  about  them.  He  acts. 
His  action  is,  however,  never  fortuitous  or 
spontaneous,  for  it  occurs  always  as  a  re- 
sponse to  excitation.  Why?  Because  of 
the  nenious  system.  To  understand  man, 
the  doer,  we  must  understand  his  nervous 
system,  which  activates  his  muscles  and  his 
glands. 

The  nervous  system  connects  stimulus 
with  response,  making  excitation  effective. 
It  has  simple  levels  for  reflex  action,  levels 


that  may  not  even  involve  the  brain.  It 
has  complex,  levels,  where  action  depends 
on  elaborate  connections  in  the  brain.  Be- 
cause no  animal  that  does  not  respond  to 
stimulation  can  be  said  to  have  a  mind, 
the  nervous  system  is  often  said  to  be  the 
organ  of  man's  mind. 

Responses  develop  as  the  individual 
grows  up.  The  embryo  can  squirm  as  a 
whole.  The  infant  can  clench  his  fist. 
The  adult  can  trill  a  note  or  say  a  tongue- 
twister.  Some  responses  are  primitive  and 
automatic,  like  winking,  whereas  others 
are  complex  and  voluntary  in  the  sense 
that  they  are  excited  by  ideas,  like  going 
shopping.  Still  others  are  complex  and 
learned,  like  walking.  The  essential  cause 
of  a  response  may  be  social  pressure,  emo- 
tion, need,  thought,  learning,  idea  or  sim- 
ple stimulation.  To  understand  thor- 
oughly the  causes  of  the  organism's  re- 
sponses would  be  to  understand  man  him- 
self. 

Next  in  importance  to  the  fact  that  man 
can  respond  with  movement  to  excitation 
is  his  characteristic  of  being  able  to  alter 
his  modes  of  response.  He  can  learn. 
Learning  is  the  establishment  of  new  rela- 
tions between  stimulus  and  response.  Food 
in  a  man's  mouth  makes  his  saliva  flow; 
that  is  an  inherited  relationship.  Man  can. 
however,  learn  what  food  looks  like  so 
that  his  saliva  flows  at  the  mere -sight  of 
food.  His  mouth  may  even  learn  to  water 
at  the  soimd  of  a  dinner  bell. 

It  often  happens  that  a  complex  response 
seems  entirely  new  because  it  is  a  brand 
new  combination  of  old  response  elements, 
as  in  the  learning  of  a  poem  or  of  a  stroke 
at  tennis.  Man  makes  these  new  integra- 
tions of  responses  under  the  pressure  of 
some  need,  primitive  or  sophisticated.  He 
learns  to  recognize  food,  because  he  needs 
to  eat  to  live;  and  he  learns  to  recognize 


The  Subject  Maffer  of  Psychology 


musical  intervals  because  he  needs  to  play 
the  violin  in  order  to  enjoy  the  life  in 
which  he  lives.  Sometimes  he  perceives  a 
new  relationship  suddenly,  and  ever  after- 
ward acts  differently  about  what  he  has 
perceived.  That  is  insight.  More  often 
he  learns  slowly,  with  many  repetitions,  a 
little  at  a  time.  Learning  accounts  for 
most  of  the  differences  between  the 
adult  and  the  infant.  It  is  so  important 
that  some  animal  psychologists  have  said 
that  without  learning  there  can  be  no 
mind,  although  it  is  probably  more  accu- 
rate to  say  that  mind  exists  wherever  re- 
sponse exists. 

It  turns  out  that  learning  is  not  perma- 
nent in  man.  He  forgets.  In  general  his 
forgetting  goes  on  continually.  His  recent 
memories  are  more  numerous  than  his  old 
ones.  One  cause  of  his  forgetting  is  his 
limited  capacity  for  the  acquisition  of  re- 
sponse relationships.  He  cannot  learn 
more  than  so  much  at  a  time  and  thus  gen- 
erally for  complete  learning  he  requires 
many  repetitions.  What  he  succeeds  in 
learning,  however,  interferes  with  what  he 
has  already  learned,  so  that  the  new  ac- 
quisitions cancel  out  some  of  the  old.  Per- 
haps if  a  man  could  sleep  without  thinking 
or  learning  at  all  for  a  hundred  years,  he 
would,  like  the  sleeping  beauty,  wake  up 
with  no  forgetfulness  and  go  on  just  where 
he  had  left  off. 

Next  in  importance  to  learning  is  man's 
capacity  for  representation.  He  can  re- 
spond to  an  absent  object  because  he  can 
learn  to  let  a  present  object  represent  it, 
or  because  he  creates  within  himself  a  rep- 
resentative. These  internal  representatives 
have  been  called  images.  Out  of  sight  is 
not  out  of  mind  for  man.  In  terms  of  his 
imagery  he  can  recollect  and  he  can  think; 
he  can  imagine  and  dream  the  bizarre 
dreams  of  sleep  or  the  wise  dreams  of  crea- 


tive genius,  liy  images  he  can  solve  prob- 
lems in  thought.  Similarly  he  ran  um; 
words,  either  imaged  or  spoken,  to  repre- 
sent absent  objects  or  abstract  generaliza- 
tions. With  them  he  can  think,  and  create, 
and  solve  jjroblems.  This  great  capacity 
to  utilize  the  symbolic  power  of  words  and 
images  is  the  chief  distinction  between  man 
and  the  animals. 

Inhere  is  also  the  question  as  to  how  man 
learns  about  the  world  in  which  he  lives, 
how  he  finds  out  what  is  there.  That  is 
the  problem  of  perception.  Man  does  not 
perceive  his  environment  exactly  as  it  is, 
but  alters  what  he  perceives  in  accordance 
with  his  needs,  for  the  outside  world  is  too 
complicated  and  variable  for  him  to  be 
able  to  perceive  it  in  all  its  chaotic  change- 
fulness.  Needing  to  simplify  his  environ- 
ment for  his  own  purposes,  the  first  thing 
man  does  is  to  divide  it  up  into  objects. 
Objects  are  thus  man-made.  Perception 
pulls  many  items  of  experience  together 
into  an  object  and  puts  other  items  off  on 
the  outside,  so  that  man,  when  he  sees  the 
world  as  a  collection  of  objects,  has  done 
something  to  the  world  in  perceiving  it. 
An  object  must  have  a  certain  amount  of 
stability  in  order  that  it  may  always  seem 
to  be  itself  and  not  to  be  forever  becom- 
ing something  else.  Thus  we  find  man 
equipped  with  a  set  of  laws  of  perceptual 
constancy:  seen  objects  tend  to  stay  the 
same  size,  even  when  thev  vary  in  distance: 
they  tend  to  stay  the  same  shape.  e\en 
when  viewed  at  different  angles;  they  tend 
to  stay  the  saqie  color,  even  Avhen  tlie  in- 
tensity and  hue  of  the  illumination  cliange. 
Since  man  needs  to  kno^v  where  he  is  and 
where  other  things  are,  Ase  find  that  he  can 
perceive  the  locations  and  distances  of 
many  objects,  as  well  as  tlieir  shapes  and 
sizes.    From  various  clues  tliat  come  to  him 


The  Nature  of  Psychology 


he  correctly  reconstructs  some  of  the  data 
of  his  environment— or  rather  his  nervous 
system  is  such  that  it  makes  these  'infer- 
ences' about  the  outer  world  for  him  and 
presents  them  to  him  as  his  perceptions. 
Man  is  so  built  that  he  gets  in  this  way  the 
picture  of  the  world  that  he  needs. 

It  is  via  the  five  senses  that  the  nervous 
system  gets  the  data  which  it  works  over 
into  perceptions  of  objects.  Psychology 
had  a  great  deal  to  say  about  the  senses 
because  they  constitute  its  oldest  field  of 
research,  and  much  is  now  known  about  it. 
It  is  an  historical  accident  that  we  know 
more  about  tones  than  about  needs,  more 
about  colors  than  about  prejudices,  but 
there  will  not  always  be  this  discrepancy. 
Eventually,  as  research  continues,  the  laws 
of  thinking  and  wishing  will  become  fully 
as  explicit  as  the  laws  of  seeing  and  hear- 
ing are  now. 

So  this  is  what  psychology  is  about— man, 
the  organism:  man's  capacity  (1)  for  per- 
ceiving, (2)  for  response,  (3)  for  learning 
and  (4)  for  symbolization.  The  organ- 
ism has  these  various  properties,  man  has 
these  various  capacities,  and  man  uses  them 
all  in  a  world  filled  with  things,  which 
have  been  created  by  his  own  perceiving, 
and  with  other  people,  who  themselves 
have  comparable  capacities  and  whose  re- 
lations and  responses  to  one  another  are 
of  the  utmost  importance  to  all. 

BEHAVIOR    AND 
CONSCIO  USNESS 

Psychology  deals  with  both  the  beliavior 
of  man  as  it  appears  in  his  responses  and 
with  consciousness  as  he  finds  it  in  his  im- 
mediate experience.  "We  need  now  to  con- 
sider a  few  matters  about  each  of  these  two 
kinds  of  data. 


Behavior 

If  beha\ior  is  just  movement  of  the  or- 
ganism, why  does  it  come  into  psychology? 
Is  not  physiolog)'  the  field  where  bodily 
moxement  is  studied?  People  are  always 
asking  that  question,  asking  where  the  line 
between  physiology  and  psychology  comes, 
where  one  science  leaves  off  and  the  other 
begins;  but  there  is  no  line.  Sciences  never 
have  sharp  boundaries. 

Think,  for  instance,  about  the  behavior 
of  the  stomach.  You  put  food  into  it  and 
then  study  how  it  contracts  while  the  gas- 
tric juice  flows  in  rapidly.  In  doing  that 
you  are  being  a  physiologist,  studying  di- 
gestion. But  suppose  you  keep  food  out 
of  the  stomach  and  then  see  how,  after  sev- 
eral hours,  it  starts  its  long  slow  contrac- 
tions that  make  men  restless  and  make 
them  say,  "Oh,  how  hungry  I  am!"  Then 
you  are  being  a  psychologist,  studying 
hunger  as  motivation.  Or  you  start  find- 
ing out  how  continued  worry  makes  the 
stomach  keep  contracting  too  much  and 
the  gastric  juice  flow  too  much,  forming 
presently  a  stomach  ulcer,  and  then  you 
are— what?  A  psychologist.  A  physiolo- 
gist. A  physiological  psychologist.  A  sci- 
entist interested  in  what  is  now  called  psy- 
chosomatic medicine.  The  terms  do  not 
really  matter. 

Actually  a  psychologist  ought  to  know, 
besides  psychology,  a  great  deal  of  physi- 
ology, physics  and  sociology,  and  have  some 
acquaintance  with  the  history  of  science 
and  enough  knowledge  of  philosophy  to 
prevent  him  from  trying  to  make  too  rig- 
orous a  definition  of  psychology  for  stu- 
dents to  learn.  Actually  he  has  to  be  con- 
tent with  less. 

Consciousness 

Psychology  studies  consciousness  as  well 
as   behavior.      Only   a   hundred   years   ago 


Consciousness 


you  would  have  been  told  that  jjsyrhoirjgy 
is  the  study  of  consciousness,  that  men  have 
minds  and  bodies,  and  that  psychology 
studies  the  minds  and  physiology  the  bod- 
ies. That  is  really  how  this  distinction  be- 
tween physiology  and  psychology  devel- 
oped, the  one  group  of  men  studying  the 
workings  of  the  body  and  the  other  con- 
sciousness—sensations, perceptions,  feelings, 
emotions,  imaginations,  memories,  thoughts 
and  volitions.  The  two  sciences  would 
never  have  overlapped  had  it  not  been 
for  the  fact  that  consciousness  depends  on 
the  body  and  its  nervous  system.  No  scien- 
tist has  ever  been  able  to  observe  a  dis- 
embodied consciousness.  There  is  always 
a  body  around,  and  the  body  is  behaving— 
talking  or  acting  in  some  way.  So,  al- 
though it  is  true  that  psychology  studies 
both  consciousness  and  behavior,  you  never 
find  consciousness  in  anyone  but  yourself 
except  by  observing  his  behavior.  The 
basic  rule  is:  no  behavior,  no  conscious- 
ness. It  is  for  this  reason  that  the  psy- 
chologists, who  began  with  the  study  of 
consciousness,  got  to  studying  behavior,  so 
that  after  a  time  the  sharp  line  between 
physiology  and  psychology  disappeared. 

The  fact  that  consciousness  can  be  known 
only  through  behavior  reduces  to  the 
simple  statement  that  there  are  three  kinds 
of     behavior    which     psychologists     study. 

(1)  First,  there  is  the  behavior  which  gives 
information  about  consciousness:,  like 
laughing  or  crying  or  saying  the  words, 
"It's    pink,"    or    telling    abovit    a    dream. 

(2)  Then  there  is  the  behavior  which  gives 
information  about  unconscioiisness~ior 
psychologists  believe  in  the  paradox  of  an 
unconscious  kind  of  consciousness.  This 
is  the  behavior  that  implies  that  you  are 
acting  on  wishes  which  you  do  not  know 
about  and  would,  perhaps,  deny  having, 
like  wishful   forgetting  when  you  remain 


li;ipjjily  uruoriscious  of  something  you 
ought  to  remember  and  do  not  want  lo 
remember.  Rebuking  a  person  you  know 
well  and  do  not  like  by  forgetting  his  name 
is  a  good  instance.  (.S)  And  then  there  is 
just  plain  behavior,  like  putting  the  .5014th 
candy  neatly  in  a  box  in  a  candy  factory 
because  you  have  learned  to  do  it  and  it 
is  now  a  habit  which  you  carry  on,  hour 
after  hour,  while  you  occupy  your  con- 
sciousness with  memories  of  last  night's 
date.  It  all  gels  back  to  behavior  in  this 
way,  even  if  you  start  with  consciousness. 

On  the  other  hand,  even  though  you 
have  to  study  the  behavior  of  other  people 
to  know  about  their  consciousnesses,  your 
own  consciousness  always  seems  to  be 
known  to  you  yourself  immediately.  You 
do  not  need  a  mirror  to  find  out  that  vou 
are  angry.  A  science  of  psychology  cannot, 
of  course,  be  built  up  on  any  one  man's 
experience,  so  most  of  consciousness  for 
every  psychologist  is  the  experience  of 
others.  Nevertheless  it  is  interesting  to 
pause  to  consider  just  what  sort  of  stuff 
your  own  experience  is  and  how  it  differs 
from  what  you  know  exists  in  the  world 
about  you. 

Begin  with  an  experiment.  Look  at  Fig. 
1.  See  the  spirals.  Find  the  letter  A  at  the 
top  of  the  figure  on  one  of  the  spirals. 
Follow  that  spiral  with  your  eyes  or  your 
pencil  around  the  figure  until  you  come 
back  to  the  top  again.  There  you  are,  back 
at  the  letter  A.  W^hat  vou  ^vere  folloAving 
was  not  a  spiral  after  all,  but  a  circle— in 
fact  a  perfect  circle,  as  you  could  discover 
if  you  had  a  compass.  Nevertheless  \\hat 
you  see  is  a  spiral,  even  though  Avhat  you 
follow  is  a  circle.  Therein  lies  die  distinc- 
tion which  we  are  considering.  The  spiral 
is  your  consciousness.  The  circle,  A\hich  is 
there  and  which  you  cannot  see.  is  the 
physical   stimulus   for  your   perception   of 


The  Nature  of  Psychology 


FIGURE    1.      STIMULUS  VS.   CONSCIOUSNESS:    THE  TWISTED   CORD   ILLUSION 

The  conscious  data  are  the  spirals,  which  are  seen  immediately  and  persist  in  spite  of  sophistication. 
The  stimuli  for  the  spirals  are  perfect  circles.  Start  at  A  at  the  top  and  follow  all  the  way  around;  you 
come  back  to  A  again.    [Adapted  from  J.  Fraser,  Brit.  J.  Psychol.,  1908,  2,  307,  Fig.  3.] 


the  spiral.  This  is  an  illusion,  a  percep- 
tion in  which  consciousness  and  its  stimu- 
lus coexist  in  a  lawful,  scientifically  under- 
stood disagreement. 

In   others  words,    consciousness   is   what 
you  experience  immediately.     Physical  ob- 


jects, unless  you  have  already  learned  about 
them,  have  to  be  figured  out.  It  takes  a 
compass  to  discover  the  circularity  of  the 
spiral's  stimulus.  One  of  the  commonest 
illusions  is  seeing  a  single  object  as  single 
Avith  two  eyes.    You  can  find  out  that  that 


Origins  of  Scientific  Psychology 


sort  of  stimulation  is  double  only  by  fiisi 
shutting  one  eye,  then  opening  it  and  shut- 
ting the  other.  Consciousness,  on  the 
other  hand,  is  the  sort  ot  experience  which 
you  can  describe  immediately  without  hesi- 
tation or  reasoning. 

Unconsciousness  has  to  be  figured  out— 
by  yourseir,  your  friends,  your  psychiatrist 
or  someone  else.  Maybe  /  am  wise  enough 
to  know  more  about  your  motives  than 
you  yourself  when  you  address  the  letter 
meant  for  Boston  to  Baltimore  where  lives 
the  girl  you  met  last  night.  Motives  are 
very  likely  not  to  be  directly  conscious. 

ORIGINS    OF    SCIENTIFIC 
PSYCHOLOGY 

Psychology  has  had  a  long  history,  and 
we  had  better  have  some  words  about  how 
it  came  to  be  the  way  it  is. 

The  first  name  to  mention  is  that  of  the 
philosopher-physiologist  Descartes  (1596- 
1650),  whose  effect  upon  psychological 
thinking  is  still  felt.  Descartes  made  these 
two  important  contributions.  (1)  He  ar- 
gued that  animals  are  automata,  that  they 
act  like  machines,  and  that  men  do  too  in 
their  irrational  conduct.  Based  on  this 
view  is  the  modern  notion  that,  if  you 
knew  enough  about  the  nervous  system, 
you  could  make  a  mechanical  or  electronic 
robot  who  could  act  and  think  like  a  man. 
(2)  Descartes  also  argued  that  soul  and 
body,  consciousness  and  nervous  system  are 
quite  separate,  forming  different  worlds, 
which  nevertheless  interact,  each  affecting 
the  other,  at  a  specific  point  in  the  brain. 
Consciousness  is  in  the  body  but  it  occu- 
pies no  space  within  it— is,  as  Descartes  put 
it,  "unextended  substance."  This  view  of 
quite  different  body  substance  and  mind 
stuff  is  called  dualism.  It  is  responsible  for 
the  modern  common-sense  notion  that  the 


mind  is  soiixtliiiig  within  the  head,  taking 
up  no  separate  space  oi  its  own,  yet  work- 
ing there  to  perceive  the  oiitsifle  world,  lo 
do  its  own  thinking  and  to  (ontrol  the 
actions  of  the  body— a  little  extra  person 
immured  in  the  skull,  perpetually  busy,  as 
news  comes  in  along  one  set  of  nerves, 
sending  out  orders  along  another  set. 

Next  we  must  jnit  in  our  record  the  long 
tradition  of  liritish  psychology  thai  began 
in  1690  with  the  philosopher  John  Locke 
(1632-1704)  and  continued  up  into  mod- 
ern psychology  two  centuries  later.  'I "his 
school  is  sometimes  called  British  cinpirt- 
cisrn  and  sometimes  British  associationisrn. 
It  was  empiricism  first  when  Locke  argued 
—he  was  trying  to  refute  Descartes  in  this 
matter— that  all  content  of  the  mind  conies 
from  experience.  The  infant's  mind,  he 
said,  is  just  a  piece  of  white  paper  on  which 
experience  Avrites.  Actually  he  had  hold 
of  half  the  truth,  for  there  is  nothing  in  a 
man's  consciousness  or  behavior  that  is  not 
partly  learned,  although  heredity  also  plays 
its  role.  Having  made  learning  so  im- 
portant, Locke  then  had  to  say  how  learn- 
ing works.  He  suggested  that  association 
is  the  principle.  Ideas  that  belong  to- 
gether tend  to  stay  together  in  the  mind: 
that  is  what  association  is.  Locke's  view 
led  eventually  to  a  kind  of  mental  chem- 
istry, in  which  perceptions  and  ideas  were 
thought  of  as  complex  molecules  made  up 
of  atoms  of  sensations  and  images  held  to- 
gether by  association. 

Dualism  remained  the  rule  in  psychology 
pretty  much  up  to  the  end  of  the  nine- 
teenth century.  You  had  mind  and  you 
had  body.  There  were  many  guesses  as  to 
how  the  two  were  related,  but,  in  the 
middle  of  the  nineteenth  century,  the  gen- 
eral acceptance  of  the  notion  of  the  con- 
servation of  energy  led  psychologists  to 
accept,  for  the  most  part,  the  conception 


8 


The  Nature  of  Psychology 


of  parallelism.  That  view  is  that  man  is 
a  machine  in  which  all  conduct  is  to  be 
explained  by  the  action  of  the  sensory 
nerves,  the  spinal  cord,  the  brain  and  the 
motor  nerves,  and  that  certain  of  these 
events— some  of  those  that  occur  in  the 
brain— are  paralleled  by  the  occurrences  in 
consciousness. 

Against  this  parallclistic-dualistic  view 
of  the  relation  of  the  mind  to  the  body 
were  put  forward  various  kinds  of  monism, 
the  A'icw  that  mind  and  body  are  the  same 
kind  of  stuff  or  at  most  different  aspects 
of  the  same  basic  e^'ents.  These  views  of 
the  relation  of  mind  to  body  matter  to  us 
only  in  respect  of  what  they  led  to.  Paral- 
lelistic  dualism  led  to  introspectionism. 
Monism  has  realized  itself  in  modern  times 
in  behaviorism.  These  two  schools  of  psy- 
chology we  shall  consider  presently,  but 
first  we  must  get- back  to  the  nineteenth 
century. 

When  physiology'  -vvas  growing  into  a 
science,  some  of  the  physiologists  became 
interested  in  what  are  really  psychological 
problems.  There  was,  for  instance,  Jo- 
hannes Miiller  (1801-1858),  called  the 
father  of  experimental  physiology,  who  in 
1826  laid  down  the  theory  that  the  nature 
of  sensory  quality  depends  on  which  par- 
ticular nerve  is  excited.  Press  on  your  eye- 
ball, and  you  see  colors;  get  your  ears 
boxed,  and  they  will  ring.  Miiller  was  a 
dualist.  He  was  supposing  that  the  mind, 
within  the  brain,  would  be  noting:  "This 
is  something  that  can  be  seen,  a  sight  not 
a  sound,  because  it  is  the  optic  nerve  that 
is  being  stimulated."  There  was  also  E.  H. 
Weber  (1795-1878),  who  gave  us  AVeber's 
law  in  1834,  the  law  which  asserts  that  the 
just  perceivable  difference  between  two 
stimuli  gets  larger  as  the  stimuli  get  larger. 
Two  men  shoiuing  make  more  noise  than 


one  man,  but,  if  you  add  only  one  extra 
shouter  to  fifty  shouters,  you  will  never 
hear  the  difference.  In  such  ways  it  was 
getting  quite  clear  toward  the  middle  of 
the  nineteenth  century  that  you  could  ex- 
periment with  the  mind— at  least  with  sen- 
sations—as well  as  with  the  brain. 

At  that  point  experimental  psychology 
began.  Three  men  contributed  to  its 
founding.  There  was  Hermann  von  Helm- 
holtz  (1821-1894),  perhaps  the  ablest  scien- 
tist who  has  as  yet  touched  psychology,  the 
man  who  set  the  physiologists  by  the  ears 
in  1850  by  measuring  the  velocity  of  the 
nerve  impulse  and  who  wrote  and  pub- 
lished what  are  still  the  gieat  classical  vol- 
umes on  visual  and  auditory  sensation  in 
the  decade  following  1856.  There  was  also 
G.  T.  Fechner  (1801-1887),  who  worked 
out  the  methods  for  measuring  sensation 
and  published  them  in  1860.  And  then 
there  was  AVilhelm  AVundt  (1832-1920), 
■who  coined  the  phrase  physiological  psy- 
chology to  stand  for  the  kind  of  work 
Miiller  and  Weber  and  Helmholtz  and 
Fechner  had  been  doing.  He  wrote  in  1874 
the  first  systematic  handbook  of  physiologi- 
cal or  experimental  psychology  (the  classic 
up  to  its  sixth  edition  in  1911),  he  founded 
the  first  important  laboratory  of  experi- 
mental psychology  at  Leipzig  in  1879 
(William  James  had  a  little  laboratory  at 
Harvard  a  few  years  earlier)  and  he  really 
got  the  new  experimental  psychology  im- 
der  way  as  a  separate  social  institution. 
■Wundt  was  a  dualist  and  parallelist  in  his 
theory  of  mind  and  body.  Fie  took  over 
the  notion  of  association  from  British  em- 
piricism. He  was  a  mental  chemist,  and 
he  believed  that  we  can,  by  introspection, 
analyze  consciousness  into  the  mental  ele- 
ments of  which  it  is  composed.  Introspec- 
tion  is   the   ha\  ing  of  experience   and  de- 


Schools  of  Psychology 


scribinj^  il.  VVlicii  wc  note  iIkil  tlic  cuivcs 
in  Fig.  1  are  spirals,  we  arc  introspecting. 
Introspcrlion  is  llie  way  to  gel  at  conscious- 
ness. 

As  late  as  1910  most  psychologists  re- 
garded introspection  as  the  basic  method 
or  psychology,  that  is  to  say,  most  psycholo- 
gists were  dualists:  they  believed  that  phys- 
iology studied  the  body,  that  psychology 
studied    consciousness    and    that   introspec- 


cliological  expeiimcnls  on  animal  intelli- 
gence. He  studied  how  cats  can  learn  to 
get  out  of  puz/le  boxes. 

From  this  point  it  will  be  easy  for  us  to 
follow  the  main  developments  in  the  hiv 
tory  of  scientific  psychology  by  noting  how 
the  four  most  important  schools  of  mod 
ern  psychology  waxed  and  waned  from  the 
end  of  the  nineteenth  century  until  the 
present.     We  turn  to  them  now. 


FIGURE    2.      SCHOOLS   OF   PSYCHOLOGY 

Diatjram  shows  the  relationship  of  four  schools  of  psychology  to  each  other  and  to  the  theory  of  eyolii- 
tion.  Modern  psychology  tends  to  ignore  schools  but  to  deal  with  both  consciousness  and  behayior  in  in- 
teurated  wholes. 


tion  was  the  direct  way  of  getting  at  con- 
sciousness. 

Meanwhile,  in  1859,  Darwin  had  con- 
tributed the  theory  of  evolution  to  science. 
It  created  a  revolution  in  scientific  think- 
ing and  cast  some  doubt  upon  dualism. 
Before  that  time  consciousness  liad  been 
thought  of  as  practically  the  same  stuff  as 
the  soul.  Now  Darwin  suggested  that  men- 
tal characteristics— especially  emotional  be- 
havior—might be  inherited  by  man  from 
his  animal  ancestors.  Consciousness  was 
thus  being  biologized.  Darwin's  famous 
cousin,  Francis  Galton  (1822-1911),  pub- 
lished in  1869  a  study  of  British  genius,  in 
which  he  sought  to  show  that  genius  is 
inherited.  Several  investigators  in  England 
and  America  became  interested  in  mental 
evolution  and  so  in  animal  psychology,  and 
in  1898  Thorndike  in  America  published 
what  were  almost  the  first  systematic  psy- 


SCHOOLS    OF    PSYCHOLOGY 

There  have,  then,  been  these  four  schools 
of  psychology.  They  are  of  different  ages, 
but  the  last  two  were  contemporaneous. 
See  Fig.  2  for  a  diagram  of  their  relation- 
ships. 

(1)  Introspective  Psychology 

That  is  the  school  which  regards  con- 
sciousness as  the  important  object  of  study. 
It  was  the  school  of  Wundt  and  for  the 
most  part  it  used  some  kind  of  introspec- 
tive analysis  of  consciousness,  a  kind  of 
mental  chemistry.  In  America  it  was  most 
strongly  defended  by  Titchener  (1867-1927) 
at  Cornell.  The  school  was  at  its  gieatest 
power  about  1910.  No  one  noAvadays  calls 
himself  an  introspectionist.  but  everyone 
has  to  know  about  this  oldest  of  the  schools 
in  order  to  understand  the  others. 


10 


The  Nature  of  Psychology 


(2)  Functional  Psychology 

The  theory  of  evohition  was  marvelovisly 
well  fitted  to  thrive  in  the  American  atmos- 
phere, where  competition  and  the  struggle 
tor  success  resembled  Darwin's  principle  of 
the  survival  of  the  fittest.  It  was  natural 
for  American  psychology  to  be  functional, 
to  consider  mind  in  terms  of  its  uses  to 
tiie  organism  in  its  effort  to  succeed. 
William  James  (1842-1910)  at  Harvard  was 
the  first  American  to  react  against  intro- 
spectionism,  and  most  of  the  other  Ameri- 
can psychologists  in  the  period  1890-1910 
believed  that  psychology  should  deal  pri- 
marily with  human  abilities  and  capacities. 
The  school  that  was  called  the  functional 
school  was  established  by  John  Dewey 
(1859-  )  at  the  University  of  Chicago 
about  1896  and  was  carried  on  there  later 
by  James  R.  Angell  (1869-  ).  This 
school  was  dualistic,  interpreting  conscious- 
ness in  terms  of  its  use,  and.  because  it  was 
(oncerned  primarily  with  himian  abilities, 
it  provided  a  friendly  background  for  both 
(he  mental  tests  and  animal  psychology, 
neither  of  which  is  primarily  concerned 
about  consciousness.  The  school  of  func- 
tional psychology  may  be  said  to  have 
evaporated  when  behaviorism  became  well 
established,  but  the  spirit  of  the  school  is 
still  the  dominating  force  in  American 
psychology.  Mental  testing  and  applied 
psychology  have  thrived  in  America  be- 
cause they  are  useful  psychologies  and  ac- 
cord well  with  tlie  spirit  of  competition 
liiat  marks  the  American  culture. 

(3)  Behaviorism 

The  next  step  in  functionalistic  progress 
in  America  was  the  founding  of  behavior- 
ism about  1913  by  John  B.  Watson  (1878- 
).  Watson  had  been  working  with  rats 
at  Chicago  under  Angell.  His  early  inter- 
ests  were   in   animal   psychology,   and    the 


conventions  of  his  day  held  that  animals, 
in  learning,  to  solve  puzzles,  to  find  food 
in  mazes  and  to  discriminate  the  correct 
food  box,  were  displaying  consciousness 
and  that  the  psychologist  ought,  therefore, 
to  assess  their  consciousnesses.  Watson  ar- 
gued that  you  never  know  much  about  the 
consciousness  of  a  rat,  although  you  can 
study  his  abilities  and  capacities,  and  that 
such  study  is  properly  to  be  regarded  as 
psychology.  He  laid  down  the  law  that 
psychology  should  deal  only  with  behavior. 
Introspection  he  ruled  out,  and  conscious- 
ness he  ignored.  His  behaviorism  proved 
practicable  for  the  very  reason  that  you 
never  learn  about  the  consciousness  of  any 
organism,  human  or  animal,  unless  the  or- 
ganism behaves  somehow  in  its  introspec- 
tion. Thus  Watson  could  really  keep  in- 
trospection in  behaviorism  by  calling  intro- 
spection "verbal  behavior."  Nevertheless, 
interest  in  consciousness  was  diminishing 
and  interest  in  behavior  increasing.  Be- 
haviorism was  consistent  with  mental  test- 
ing and  animal  psychology.  The  study  of 
consciousness  was  still  fmther  depreciated 
about  the  turn  of  the  century  when  the 
psychoanalytic  doctrine  of  Sigmund  Freud 
(1856-1939)  began  to  direct  the  thinking 
of  the  psychologists  toward  imconscious- 
ness.  Partly  on  this  accoiuit  and  partly 
because  of  the  outcome  of  experiments  on 
thought  and  action,  they  came  to  realize 
that  a  great  deal  of  motivation  is  luicon- 
scious  and  quite  tmavailable  to  introspec- 
tion. By  1930  introspection  had  become 
only  a  secondary  method  of  psychology,  ex- 
cept as  it  was  used  in  simple  sensory  dis- 
criminations or  employed  loosely  in  social 
psychology  and  psychotherapy. 

(4)  Gestalt  Psychology 

1  he   success   of   behaviorism   was   some- 
what diminished  by  the  appearance  of  Ges- 


Schools  of  Psychology 


n 


tak  psychology  in  (iermany  about  1912. 
The  new  movement  had  caught  American 
interest  by  the  1920's,  and  then  in  the 
I930's  its  leaders  migrated  to  America  when 
the  Nazi  power  destroyed  German  treedom. 
(ieslall  means  form,  and  the  name  was  de- 
rived from  rcr(ain  studies  of  visual  percep- 
tion of  spatial  form,  it  is  better  trans- 
lated, however,  as  structure,  for  the  thesis 
of  the  school,  which  was  founded  by  Max 
Wertheimer  (1880-1943),  is  that  psycholo- 
gists nnist  deal  with  total  structures  and  the 
system  of  their  internal  forces,  eschewing 
the  mental  chemistry  and  the  analysis  that 
both  introspectionism  and  behaviorism 
favored.  The  Gestalt  psychologists  say 
that,  in  looking  at  a  square,  it  is  the  total 
figure  that  makes  the  square  look  square, 
not  the  parts.  A  square  is  more  than  four 
black  lines.  It  is  four  black  lines  in  a  par- 
ticular relation  to  one  another,  and  square- 
ness really  depends  on  the  relation  and  not 
the  lines.  Four  dots  will  also  make  a 
square,  as  will  four  red  lines.  The  mental 
chemists  were  always  talking  about  the 
sensations,  the  parts  that  made  up  the 
s(|uare,  as  if  the  squareness  of  a  red  square 
were  different  from  the  squareness  of  a  blue 
square.  By  the  late  1930's  this  school  had 
accomplished  its  main  purpose  of  getting 
the  attention  of  psychologists  directed  to 
larger  systems  of  interrelated  facts.  The 
movement  did  not  revive  American  inter- 
est in  consciousness,  though  for  a  while  it 
delayed  the  general  shift  of  the  Americans 
toward  behaviorism.  Meanwhile  the  Nazi 
power  had  destroyed  German  psychology, 
and   America    took    the   lead   in    the    new 


(5)  Modern  Psychology 

During  the  1930's  the  isms  pretty  well 
dropped  out  of  psychology.  The  func- 
tionalists first  gave  place  to  the  behavior- 


ists,  but  nowadays  yon  never  hear  a  jnaii 
call  himself  a  behaviorisi,  although  you 
may  still  hear  about  behaviorism.  It  has 
fjeen  even  longer  since  anyone  liked  to 
label  himself  an  inlrospectionist.  There 
are,  jjerhaps,  still  a  few  Creslallisls,  but 
that  is  only  because  Germans  like  istns 
ijetter  than  Americans  do. 

What  has  actually  happenerl  is  iliat  con- 
sciousness, inherited  from  inlrospec  tionism, 
is  used  in  psychophysics  (for  example,  in 
discrimination  of  colors,  tones,  visual  div 
tances  and  all  the  other  sensory  capacities 
for  which  perceptual  accuracy  must  be  de- 
termined) and,  at  the  other  extreme,  in 
psychotherapy  where  experiences  from 
waking  life  or  dreams  need  to  be  recorded 
and  studied.  The  spirit  of  functional 
psychology  pervades  the  modern  American 
scene  which  studies  mind  in  use  for  the 
organism  as  a  matter  of  course.  Behavior- 
ism has  contributed  behavior  and  the  mod- 
ern stimidus-response  psychology.  This 
kind  of  psychology  also  claims  to  be  study- 
ing consciousness,  because  consciousness  is 
revealed  to  scientific  observation  only 
through  behavior  of  some  kind.  Gestalt 
psychology  disappeared  as  an  ism  because, 
after  a  battle,  nearly  everyone  had  accepted 
its  basic  tenet  that  too  much  analysis  gives 
false  residts,  that  wholes  are  safer  objects 
of  study  than  their  parts,  that  you  must 
always  take  into  consideration  enough  of 
the  interrelated  forces  to  make  you  fairh 
safe  about  not  having  omitted  any  essential. 

From  here  we  can  go  on  to  the  fields  of 
modern  psychology.  The  only  reason  for 
mentioning  these  four  schools  in  this  book 
is  that  the  student  hears  about  behaviorism 
and  Gestalt  psychology  and  has  a  right  to 
be  told  what  they  are  and  that  they  are  no 
longer  important  as  scliools.  AN'hat  was 
good  in  all  the  schools  is  now  simph  pare 
of  psychology. 


12 


The  Nature  of  Psychology 


Fl  ELDS    OF    PSYCHOLOGY 

The  way  in  which  modern  psychology 
has  become  further  complicated  appears  if 
we  pick  out  and  define  eleven  of  its  more 
important  fields.    Let  us  do  it. 

(1)  General  psychology  includes  the  fun- 
damental principles  of  all  psychology.  It 
also  deals  particularly  with  the  normal 
human  adult,  leaving  other  matters  to  spe- 
cial fields.  It  is  sometimes  divided  into  the 
smaller  fields  of  (a)  sensation  and  perce|> 
lion,  (b)  feeling  and  emotion,  (r)  learning 
and  motivation  and  (d)  the  higher  proc- 
esses, including  thought. 

(2)  Physiological  psychology  studies  the 
functions  of  the  nervous  system  which  con- 
trol behavior  and  consciousness  and  of 
other  similar  mechanisms  like  the  endo- 
crine glands.  It  often  uses  operative  tech- 
niques, investigating  the  functions  of  ani- 
mal brains,  for  instance,  by  removing  por- 
tions of  the  brain  tissue  and  noting  the 
effect  upon  behavior.  This  kind  of  experi- 
ment is  older  than  experimental  psychol- 
ogy, going  back  to  the  early  nineteenth 
century. 

(3)  Comparative  psychology  is  the  name 
given  to  the  study  of  the  comparison  of 
the  behaviors  of  different  animal  species. 
It  is  the  natural  history  of  animal  conduct. 
Most  of  the  psychological  work  with  ani- 
mals is  now  in  the  hands  of  physiological 
psychologists,  but  there  are  still  some  com- 
parative psychologists  left. 

(4)  Psychology  of  individual  differences 
is  the  name  given  to  the  measurement  and 
assessment  of  human  abilities,  largely  by 
the  employment  of  mental  tests.  The  use 
of  mental  tests  for  this  purpose  goes  back 
to  Francis  Galton  in  England  in  1883,  but 
the  development  of  the  tests  has  been  great- 
est in  America  in  the  last  forty  years.  Both 
the  World  Wars  greatly  stimulated  research 


in  these  modes  of  the  appraisal  of  human 
abilities. 

(5)  Industrial  psychology  includes  all  the 
means  of  personnel  selection  by  the  use  of 
tests,  inter\iews  and  other  devices,  and  all 
the  means  of  training  on  the  job  and  of 
measuring  efficiency  of  work.  It  is  not 
new,  but  it  has  been  accelerated  by  the  suc- 
cess of  these  procedures  in  the  Second 
^^'orld  ^Var. 

(6)  Child  psycliology  studies  the  develop- 
ment of  the  child,  assesses  his  abilities  by 
the  use  of  tests,  seeks  evidence  on  the  prob- 
lem of  the  relative  effects  of  heredity  and 
environment  upon  ability,  and  also  con- 
siders the  adjustment  of  the  child,  a  form 
of  clinical  psychology  (vide  infra). 

(7)  Educational  psychology  examines  the 
educational  process  in  terms  of  child  psy- 
chology, clinical  psychology'  and  the  dy- 
namic psychology  of  learning  and  moti^'a- 
tion  (vide  infra). 

(8)  Abnormal  psychology  has  to  do  with 
the  deviation  of  the  human  adult  from  the 
normal.  It  is  allied  to  psychiatry,  the 
medical  field  for  the  treatment  of  psycho- 
logical disorders  and  maladjustments. 
Since  about  1930  this  field  has  been  greatly 
influenced  by  psychoanalysis,  and  the  psy- 
choanalytic conceptions  of  unconsciotis  mo- 
ti\ation  are  now  used  by  all. 

(9)  Dynamic  psychology  is  the  result  of 
this  interpenetration  of  abnormal  psychol- 
ogy by  psychoanalysis  and  of  other  re- 
searches tliat  have  indicated  how  often 
motivation  is  unconscious.  Dynamic  psy- 
chology can  be  defined,  therefore,  as  the 
psychology  of  normal  moli\ation.  While 
its  origins  can  be  traced  far  back  into  the 
French  abnormal  psycholog)'  of  the  nine- 
teenth century,  its  important  development 
lies  entirely  in  the  present  century. 

(10)  Clinical  psychology  is  the  practical 
application  of  dynamic  and  abnormal  psy- 


Scientific  Method 


13 


(liology  to  ihc  problems  of  fiuinan  adjiist- 
incnl.  It  has  been  stimulalcd  by  the  de- 
mand for  psychological  assistance  for  the 
many  veterans  of  the  Second  World  War 
who  suffer  from  psychoneurosis. 

(11)  Social  psycholoiry  is  the  study  of  the 
individual  in  the  group  and  the  relations 
of  groups  to  one  another.  Thus  social  psy- 
chology considers  the  psychological  inter- 
relations of  people  forming  families, 
crowds,  societies  and  mobs,  and  of  the 
leader  with  his  followers.  It  includes  the 
study  of  the  formation  of  group  attitudes 
and  opinions  and  of  the  assessment  of  so- 
cial attitudes  and  public  opinions.  It  is 
thus  forced  into  a  consideration  of  social 
and  national  conflict,  of  race  prejudice  and 
similar  manifestations  of  the  interrelations 
of  the  conflicting  needs  of  many  individ- 
uals. Social  psychology  is  as  old  as  sociol- 
ogy and  cultural  anthropology,  but  its 
specific  development  along  psychological 
lines  is  visually  traced  from  the  writing  of 
William  McDougall  in  1908. 

The  present  book  has  something  to  say 
about  these  kinds  of  psychology:  general, 
physiological,  individual  differences,  indus- 
trial, dynamic  and  social.  The  other  five 
fields  enter  only  incidentally,  often  by  way 
of  illustration.  In  general  this  book  limits 
itself  to  the  scientific  core  of  psychology. 
The  other  fields  are  more  specialized  or  are 
fields  of  application. 

SCIENTIFIC    METHOD 

We  ought  now  to  say  something  about 
how  the  scientist  works.  He  does  not  fol- 
low rigid  rules.  Usually  he  has  a  hunch 
that  something  might  be  true  and  tries  it 
out  in  an  experiment.  If  his  hunch  proves 
wrong,  he  does  not,  as  a  rule,  publish  that 
fact;  so  perhaps  someone  else  will  make  the 
same  guess  and  try  it  out  again,  and  find 


again  iliat  the  guess  is  wrong.  The  scien- 
tist is  sometimes  motivated  by  intellectual 
curiosity,  .sometimes  by  that  esthetic  feeling 
which  makes  a  man  want  to  make  concrete 
a  good  idea  and  sometimes  by  the  desire 
to  advance  civilization  or  to  solve  a  par- 
ticularly pressing  practical  problem;  but  all 
the  other  human  competitive  motives  work 
too— the  need  for  money,  the  need  for  pres- 
tige, the  need  to  prove  yourself  right  and 
the  other  man  wrong.  The  rules  for  re- 
search have  been  worked  out,  not  to  con- 
strict scientific  imagination  and  constrain 
drive,  but  to  stimulate  men  into  what  are 
usually  the  more  profitable  avenues  of 
work. 

Experiment 

The  basic  scientific  method  is  experi- 
ment. Experiment  is  the  observation  of 
concomitant  variation  and  the  interpreta- 
tion of  the  concomitances  as  causes  and 
effects.  You  change  x,  and  )'  happens.  So 
y  is  observed  as  a  function  of  x.  You  prick 
a  man's  finger  with  a  pin,  and  he  quicklv 
withdraws  his  finger.  The  prick  is  .v,  the 
independent  variable,  which  the  experi- 
menter controls.  The  withdrawal,  )',  is 
the  dependent  variable,  which  the  experi- 
menter observes  as  a  result  of  x,  the  prick. 

Sometimes  you  have  to  wait  for  nature 
to  do  the  independent  ^arying  for  you. 
The  astronomer  does.  His  independent 
observation  is  often  a  date  and  a  moment 
at  which  he  makes  the  observations  whicli 
his  hypothesis  (or  hunch)  requires.  It  is 
also  impossible  for  the  psychologist  to  cre- 
ate individual  differences  in  intelligence, 
but  he  can  choose  persons  who  ha^e  differ- 
ent scores  on  an  intelligence  test  (inde- 
pendent variable)  and  then  see  whether 
they  do  differentlv  as  clerks  or  salesmen 
(dependent  variable). 

It  is   fair   to   define   the  scientist   as   the 


14 


The  Nature  of  Psychology 


man  who  is  always  after  generalizations, 
and  the  engineer  or  applied  scientist  as  the 
man  who  is  solving  particular  problems.  A 
generalization  would  be  the  statement:  All 
dreams  arc  pariially  concealed  expressions 
of  unconscious  wishes.  A  particular  prob- 
lem of  psychiatric  'human  engineering' 
would  be  tlie  use  of  John's  dreams  to  show 
why  he  had  had  a  nervous  breakdown. 
John  is  an  immediate  problem  for  'human 
engineering,'  but  he  is  interesting  to  sci- 
ence only  if  he  serves  to  represent  some 
larger  class  of  objects— like  all  men,  or  all 
the  dreamers  with  psychoneuroses.  Usu- 
ally 'pure'  and  applied  science  go  ahead 
together.  Work  in  the  one  contributes  to 
the  advance  of  the  other,  but  it  is  impor- 
tant to  remember  about  generalization. 
The  whole  value  of  science  is  that  it  re- 
duces the  complexities  of  the  world  to  gen- 
eral rules,  which,  once  established,  enable 
you  to  explain  or  predict  many,  many  in- 
dividual cases. 

You  cannot  generalize  without  repeti- 
tion. If  y  changes  when  .v  is  changed,  that 
may  be  chance.  Try  it  again.  If  it  hap- 
pens ten  times,  perhaps  it  is  'right,'  that  is 
to  say,  perhaps  the  general  rule  can  be  ac- 
cepted. More  cases  make  you  more  sure. 
Yet  you  are  never  entirely  certain;  the  fu- 
ture may  still  reveal  some  discrepancy. 

Control 

You  also  need  control  if  you  are  to  gen- 
eralize. That  means  ordinarily  that  you 
must  keep  all  the  conditions  constant  when 
you  repeat  or  you  may  not  get  the  same 
result.  If  conditions  are  going  to  be  al- 
lowed to  change,  you  had  better  change 
them  at  will  and  then  you  may  learn  some- 
thing extra.  If  you  withdraw  your  finger 
when  it  is  pricked  and  you  are  awake,  what 
will  you  do  when  you  are  asleep?  But  the 
experimenter  must  not  let  you  sleep  and 


wake  at  random.  He  must  control  yoiu 
sleeping,  keeping  it  constant  or  varying  it 
at  his  will. 

On  the  other  hand,  hunch  comes  into 
this  business  too.  No  one  can  keep  all  the 
conditions  constant,  and  the  experimenter 
has  to  guess  which  conditions  are  the  most 
important.  Suppose  you  discovered  on  a 
Tuesday  that  a  certain  percentage  of  auto- 
mobile drivers  cannot  tell  a  red  traffic  light 
from  a  green,  except  by  knowing  that  the 
red  is  on  top.  (You  could  do  it  by  inter- 
changing the  red  and  green  in  one  signal, 
provided  you  prevented  accidents  in  some 
other  way.)  Well,  that  was  Tuesday. 
Would  you  have  to  repeat  the  experiment 
on  Wednesday  and  all  the  other  days?  No, 
you  assiune  that  the  day  of  the  week  makes 
no  difference,  that  eyes  see  the  same  on 
Tuesdays  and  on  Wednesdays.  Nor  does 
the  phase  of  the  moon  matter,  nor  the 
last  name  of  the  driver.  It  is  by  hunch  that 
)ou  leave  these  matters  out  of  control. 
You  hope  they  make  no  difference.  Some- 
times, when  a  long-accepted  generalization 
turns  out  later  to  be  wrong,  it  is  because 
some  such  essential  condition  was  not  con- 
trolled when  the  original  generalization 
was  formed.  For  instance,  most  people 
w^ould  expect  sex  to  make  no  difference  in 
observing  traffic  lights,  biu  it  does.  Very 
few  women  are  color-blind. 

In  reading  about  experiments  you  often 
see  the  phrase  control  series  or  control 
group  or  you  meet  the  criticism  that  an 
experiment  was  uncontrolled.  What  do 
those  statements  mean?  This.  The  ex- 
periment consists  of  seeing  whether  y  varies 
when  .V  varies.  The  control  consists  in 
seeing  whether  y  does  not  vary  when  x  does 
not  vary.  You  want  to  see  whether  men 
can  do  better  on  an  intelligence  test  when 
you  give  them  some  of  the  drug  benzedrine 
sulphate.    So  you  divide  the  men  into  two 


Scientific  Methods 


15 


groups.  To  ihe  experimental  group  you 
give  the  benzedrine  in  capsules  without 
telling  them  what  it  is.  I'o  the  control 
group  you  give  sugar  in  capsules  without 
telling  them  what  it  is.  If  the  experimen- 
tal group  does  better  or  worse  than  the 
control  group,  maybe  benzedrine  has  some 
effect.  If  both  groups  do  as  much  better 
with  the  capsules  as  without,  perhaps  the 
improvement  is  due  merely  to  the  confi- 
dence of  the  men  that  a  psychologist's  cap- 
side  will  make  them  more  efficient.  If  you 
do  not  have  two  groups,  but  only  one,  you 
must  have  control  series  with  the  sugar,  and 
experimental  series  with  the  benzedrine, 
both  for  the  same  people. 

There  is  a  great  deal  of  pseudoscience 
which  fails  to  get  reliable  results  just  be- 
cause it  has  no  controls.  Colleges,  for  in- 
stance, keep  changing  their  course  require- 
ments in  order  to  manufacture  better  A.B.'s. 
How  do  they  know  when  the  A.B.'s  arc 
better  unless  they  keep  half  the  students  as 
a  control  on  the  old  plan  and  put  the 
other  half  on  the  new  plan  and  also  know 
how  to  compare  the  two  finished  products 
after  Commencement? 

Hypothesis 

Now  one  word  about  the  use  of  hypoth- 
eses in  science.  If  a  psychologist  gets  a 
hunch  that  blond  women  are  more  placid 
than  brimettes,  he  is  privileged  to  try  to 
pro\'e  his  hypothesis  by  experiment  if  he 
has  the  time  and  facilities  for  such  research. 
The  safe  rule  for  research,  however,  is  to 
use  it  to  test  plausible  hypotheses  which 
grow  out  of  other  research.  That  is,  by 
and  large,  the  way  science  has  progressed. 
Here,  then,  is  the  best  way,  which  has  been 
burdened  with  the  name  hypothetico- 
deductixie  method. 

(I)  On  the  basis  of  general  knowledge, 
previous  research  and  insight  into  the  re- 


lationships of  the  available  facts,  you  form 
an  hypothesis.  It  had  fjctter  be  a  sensible 
one,  but  you  arc  the  judge  of  its  plausibil- 
ity. If  you  are  trying  to  serve  science,  you 
choose  an  hypothesis  the  proof  or  disprrxjf 
of  which  would  advance  scientific  knowl- 
edge. 

(2)  The  hypothesis  is  a  generality,  the 
sort  of  proposition  that  makes  a  law  when 
it  is  proved.  So  you  deduce  from  it  some 
jjarticular  consequence  that  ought  to  fol- 
low, one  that  can  be  subjected  to  experi- 
mental lest. 

(3)  Then  you  set  up  the  test  experirnenl 
and  see  whether  the  deductive  prediction  is 
verified  or  not. 

(4)  If  the  prediction  is  verified,  you  may 
assume  tentatively  that  the  hypothesis  is 
strengthened.  You  may  even  decide  to 
accept  it,  always  subject,  of  course,  to  the 
possibility  that  it  may  be  overthrown  later. 

(5)  If  the  experiment  gives  negative  re- 
sults, does  not  justify  the  hypothesis,  then, 
if  you  arc  very  anxious  to  understand  the 
phenomena  being  investigated,  you  Avill 
have  to  use  your  wits  to  find  another  plaus- 
ible hypothesis  to  test  out. 

(6)  When  an  hypotliesis  is  verified,  you 
are  very  likely  to  find  that  it  sets  you  ne^v 
problems.  So  now  you  think  up  new  finer 
hypotheses  to  direct  you  toward  finding  out 
?('/?}'  the  hypothesis  just  verified  is  true,  and 
that  process  of  refinement  can  go  on  prac- 
tically forever. 

The  study  of  the  moon  illusion  shows 
this  process  operating.  It  was  early  ob- 
served that  the  full  moon  looks  larger  on 
the  horizon  than  up  in  the  heavens.  Many 
hypotheses  were  advanced— that  the  differ- 
ence is  due  to  refraction  at  the  horizon,  or 
due  to  the  atmospheric  haze  at  the  horizon, 
or  due  to  the  fact  that  the  moon  looks 
farther  a\va\  at  the  hori/on  and  tlius  would 


16 


The  Nature  of  Psychology 


have  to  be  big  in  order  to  give  the  normal- 
sized  image  on  the  retina.  The  first  tAvo 
hypotheses  fail  when  tested  by  the  camera. 
A  photograph  of  the  horizon  moon  is  as 
small  as  the  photograph  of  the  moon  in 
elevation.  The  third  hypothesis  fails  be- 
cause the  horizon  moon  no  longer  looks 
large  when  you  bend  over  and  \ie\v  it  be- 
tween your  legs.  The  next  hypothesis  is 
that  the  illusion  depends  on  looking  up, 
and  that  hypothesis  has  been  proved.  It 
holds  even  for  experimental  moons  only 
thirty  meters  away.  So  now  you  know;  the 
phenomenon  is  an  illusion  and  not  an 
astronomical  change,  and  it  depends  on 
looking  up.  But  why,  you  ask  at  once. 
That  needs  another  hypothesis.  Perhaps 
what  shrinks  the  moon  is  raising  the  eyes, 
or  perhaps  it  is  bending  the  neck.  That 
question  has  been  answered.  The  raised- 
eyes  hypothesis  is  right,  the  bent-neck  hy- 
pothesis is  wrong.  So,  by  forming  and 
testing  new  hypotheses,  you  have  refined 
your  knowledge.  Now  you  want  to  know 
why  raising  the  eyes  shrinks  the  moon,  but 
no  one  has  yet  been  clever  enough  to  for- 
mulate for  test  the  crucial  hypothesis  that 
will  answer  that  question.  Sometime  it 
will  be  done. 

DEFINITIONS 

Nearlv  all  the  definitions  of  terms  come 
up  in  their  proper  places  in  this  book.  'We 
may,  however,  examine  here  a  very  few 
special  words  that  we  need  to  use  at  the 
outset. 

Stimulus.  A  stimulus  is  any  change  in 
external  energy  that  gives  rise  to  such  an 
excitation  of  the  nervous  system  as  arouses 
a  response.  (See  pp.  20,  217,  251.)  A 
stimulus  cannot  exist  without  a  response 
because    it    is   defined    as    producing   a    re- 


sponse, but  in  this  sense  a  conscious  event 
must  be  regarded  as  a  response. 

Stimulus  object.  An  object,  like  a  col- 
ored paper  that  is  seen  or  a  sweet  substance 
that  is  tasted,  is  often  called  a  stimulus,  but 
it  is  more  correct  to  call  it  a  stimulus  object, 
since  it  determines  a  change  of  energy  but 
is  not  the  change. 

Situatio77.  "When  a  stimulus  object  is  ex- 
tremely complex  or  has  special  meaning  to 
the  obser\'er,  it  is  often  loosely  called  a 
situation.  A  red  light  may  be  a  stimulus, 
but  an  enemy  is  a  situation. 

Proximal  stimulus.  Since  energv  changes 
progress  serially  from  a  stimulus  object  to 
the  organism,  it  is  plain  that  stimuli  can 
be  more  or  less  proximal  (near  the  nervous 
system).  "When  the  pistol  shot  makes  you 
jump,  the  pistol  is  the  stimulus  object,  the 
sound  in  the  air  is  a  stimulus,  the  motion 
of  your  eardrmn  is  a  more  proximal  stim- 
ulus, and  motion  of  the  hair  cells  where 
the  sensory  nerve  fibers  are  in  your  inner 
ear  is  a  still  more  proximal  stimulus.  The 
stimulus  does  not  exist,  for  there  is  always 
a  series  of  more  and  more  proximal  energy 
changes  when  stimulation  occurs. 

Response.  A  response  is  the  second  and 
later  event  in  a  stimulus-response  pair.  In 
man  it  is  usually  a  muscular  movement  or 
the  secretion  of  a  gland.  AVhen  a  psychol- 
ogist is  dealing  with  consciousness,  he 
thinks  of  a  sensation  as  a  response.  Re- 
sponse exists  only  in  relation  to  a  stimidus, 
and  in  man  it  is  always  an  end  result  of 
the  action  of  the  nervous  system.  Re- 
sponses, like  stimuli,  can  be  more  or  less 
proximal.  The  contraction  of  a  muscle  is 
more  proximal  than  the  finger  movement 
which  the  muscle's  contraction  causes. 

Behavior.  "When  the  responses  are  Aery 
complicated,  it  is  better  to  call  them  bc- 
hax'ior.  Behavior  has  the  same  relation  to 
a  situation  that  a  response  has  to  a  stimulus. 


Definitions 


17 


Suhjrci  and  ohserxx^r.  7'hc  psychologist 
docs  Ills  research  with  the  stimulated  re- 
sponses of  men  and  lower  animals.  These 
organisms  on  which  he  works  are  his  sub- 
jects—\\\c  subjects  of  his  experiment.  The 
psychologist  performing  an  experiment  is 
the  experimenter.  Sometimes,  when  a  hu- 
man subject  is  asked  to  observe  his  own 
consciousness,  he  is  called  an  obserxier. 
That  means  that  the  human  subject  has 
been  able  to  take  over  a  part  of  the  experi- 
menter's responsibility  for  the  accuracy  of 
observation.  In  an  experiment  with  ani- 
mal subjects,  it  is  always  the  experimenter 
who  is  the  observer,  for  animals  cannot  be 
trusted  with  responsibility  for  scientific 
esults. 

With  all  these  matters  out  of  the  way,  we 
can  now  turn  to  the  real  business  of  this 
book,  and  we  shall  begin  with  the  mecha- 
nism of  response,  which  is,  in  man,  the 
nervous  system. 

REFERENCES 

1.  Boring,  E.   G.     A   history   of  experimental  psy- 
chology.    New   York:    Appleton-Century,    1929. 
A  thorough-going  history,  from  1690  to  about 
1920,  of  psychologists  and  their  schools  within 
the  scientific  tradition  in  psychology. 

J.  Boring,  E.  G.  Setisatio?i  and  perception  in  the 
history  of  experimental  psychology.  New 
York:   Appleton-Century,   1942. 

The  history  of  research  and  ideas  in  the  field 
of  sensation  and  perception  from  the  seven- 
teenth century  down  to  about   1930. 

3.  Cohen,  M.  R.,  and  Nagel,  E.  An  introduction 
to  logic  and  scientific  method.  New  York:  Har- 
court.  Brace,  1936.  Chaps.  10-16.  Or  abridged 
ed.     London:  Rutledge,  1939.     Chaps.  5-10. 

Discussion  of  experimental  method,  classifica- 
tion, use  of  hypotheses,  probability,  induction, 
measurement  and  statistical  method  by  two 
logicians. 

4.  Dennis,  "\V.,   ct  al.     Current   trends  in  psrcliol- 


ogy.     i'iilsljuigl),   I'a.:    University  of   l'illf>l>ur^!i 
Press,  1917. 

Eight  lectures  by  eight  disiiriguishcd  fMvchol- 
ogists  showing  hoiv  the  .Sccontl  World  War  al- 
tered the  scientific  picture  in  eight  of  the  m'»M 
important  fields  of  scientific  and  applied  psy- 
chology. 

5.  F.llis,  W.  I).  A  source  book  of  Cje\lall  psy- 
chology. London:  K.  Paul,  Trench,  Trubiier, 
r938. 

Thirty-lour  silcdious  from  (he  writings  of 
seventeen  Gesialt  psuliologisis  translated  into 
English. 

6.  I'ciiriiig,  r.  Urftf'x  action:  a  sluity  in  the  his- 
tory of  physioloniial  psychology.  Baltimore: 
'Williams  and  Wilkins,  1930. 

A  good  and  quite  detailed  survey  of  the 
history  of  physiological  psychology  from 
Descartes  to  about   1930. 

7.  Flugel,  J.  C.  A  hundred  \ears  of  psychology. 
New  York:  Macmillan,  1933. 

A  picture  of  modern  psycholog\-  from  1K33 
to  1933  with  especial  emphasis  upon  the  psy- 
chology of  Great  Britain  and  psvchoanalvsis. 

8.  Guilford,  J.  P.  (Ed.)  Fields  of  psychology. 
New  York:  Van  Nostrand,  1940. 

Twenty-t^vo  chapters  by  thirteen  authors  on 
the  content  of  ph)sioIogical,  animal,  differen- 
tial, child,  educational,  industrial,  abnormal, 
clinical  and  social  psychology. 

9.  Hartmann,  G.  W.  Gestalt  psychology.  Xew 
York:    Ronald    Press,    1935. 

A  good  interpretation  and  summarv  of  the 
theories  and  researches  that  belong  to  the 
school  of  Gestalt  psychology  and  other  closeh 
allied  schools. 

10.  Heidbreder,  E.  Seven  psxcliologies.  Xew  York: 
Appleton-Century.    1933. 

A  clear  summarv  of  the  psvchologv  of  the 
schools  of  introspective,  functional,  behavioris- 
tic,  d)namic  and  Gestalt  psvcholog\. 

11.  Keller,  F.  S.  The  definition  of  psychology. 
New   York:    Appleton-Century,    1937. 

Brief  discussions  of  the  principles  involved  in 
introspective,  functional,  behavioristic  and  Ge- 
stalt psychologies. 

12.  Kohler,  "W.  Gestalt  psychology.  (2nd  ed.) 
New  York:   Liveria;ht,  1947. 


18 


The  Nafure  of  Psychology 


A  clear,  readable  exposition  of  Gestalt  psy- 
cliology  by  one  of  its  leading  exponents,  some- 
what  revised  since   the    1929  edition. 

13.  Moore,  J.  S.,  and  Gurnee,  H.  The  foiinda- 
lions  of  psychology.  (2nd  ed.)  Piinceion: 
Princeton  University  Press,  1933. 

A  good.  aUhough  not  recent,  discussion  of 
tlie  fimdamental  concepts  and  principles  of 
psNchology. 

11.  Minphv,  G.  Ati  historical  inlroduction  to 
modem  psychology.  New  York:  Harcourt, 
Brace,  1929. 

An  excellent  detailed  and  accurate  history  of 
modern  psychology,  not  limited  to  the  experi- 
mental  tradition. 

15.  Petermann,  B.  The  Gestalt  theory  and  the 
problem  of  configuration.  New  York:  Har- 
court, Brace,  1932. 


A  straightforward  exposition  and  evaluation 
of  the  Gestalt  psychology  of  the  three  leading 
exponents,  of  the  school. 

16.  \Vatson,  J.   B.     Behaviorism.      (2nd   ed.)      New 
York:  Norton.  1930. 

.\  readalile  and  elementary  presentation  of 
tliis  school  of  psychological  thought,  by  the 
founder  of  the  school  long  after  the  founding. 

17.  Woodworth,    R.    S.      Contemporary    schools    of 
psychology.     New  York:  Ronald  Press,  1931. 

Clear  chapters  on  introspective,  behavioristic, 
Gestalt,  dynamic  and  purposive  psychologies. 

18.  Zilboorg,  G.,  and  Henry,  G.  ^V.     A   hisloy  of 
medical  psychology.     New  York:   Norton,   1941. 

.\  vividly  written  history  of  psychopathologv 
from  the  Greeks  to  the  present  with  especial 
emphasis  on  the  psychoneuroses  and  t!  eir  ante- 
cedents. 


CHAPTER 


The  Response  Mechanism 


Now  that  we  have  seen  what  psychol- 
ogy in  its  essentials  is,  and  how  it 
came  to  be  what  it  is,  we  are  prepared  to 
go  ahead  with  the  study  of  psychology's 
actual  facts.  We  start  with  the  topic  of  the 
nervous  system.  Psychology  is  not  physiol- 
ogy, but  it  has  constantly  to  consider  that 
part  of  physiology  which  explains  the 
mechanisms  of  human  action.  Psychology 
studies  man,  the  doer.  Man's  doings  are 
res23onses— responses  to  stimulations,  to  sit- 
uations, to  his  own  needs  and  ideas.  The 
nervous  system,  considered  together  with 
the  system  of  endocrine  glands,  is  the  prin- 
cipal response  mechanism.  These  two  sys- 
tems are  basic  to  all  human  behavior. 

This  chapter  sketches  the  machinery  of 
the  body  which  enables  man  to  perceive 
and  to  respond  to  his  environment  in  intel- 
ligent fashion. 

As  a  matter  of  fact,  nearly  every  part  of 
the  human  body  is  involved  either  directly 
or  indirectly  in  behavior,  for  each  part 
plays  some  role  in  the  smooth  functioning 
of  the  whole  body.  The  digestive  tract  is 
the  portal  of  entry  for  food  and  water 
without  which  other  tissues  of  the  body 
cannot  survive  or  carry  on  their  functions 
normally.  The  liver  stores  food  materials 
which  the  brain  uses.  The  heart  pumps 
blood  which  carries  these  materials  to  the 
sense   organs,    the  brain   and   the   muscles. 


The  lungs  provide  oxygen  for  the  use  ol 
the  food  materials  in  tissues  of  the  body, 
and  they  carry  away  carbon  dioxide  result- 
ing from  such  use.  The  kidneys,  similarly, 
rid  the  body  of  the  poisonous  products 
which  are  generated  in  the  activities  of 
the  body's  tissues.  These  are  but  a  few  of 
the  interrelations  of  organs  of  the  body;  the 
list  could  be  greatly  enlarged. 

The  response  mechanism  in  man  and  in 
the  higher  animals  includes  (1)  the  sense 
organs  or  receptors,  which  react  to  stimula- 
tion and  set  in  operation  the  processes  of 
excitation  in  the  living  individual,  (2)  the 
nervous  system,  which  transmits  and  con- 
ducts excitation,  and  (3)  the  muscles  and 
glands,  or  effectors,  which  make  actual  re- 
sponse possible.  Combined  in  a  highly 
complex  mechanism,  these  three  principal 
parts  give  the  living  organism  means  of 
responding  in  an  organized  fashion  to  the^ 
physical  energies  of  the  environment  -^vhich 
stimidate  him.  The  immediate  analog)-  is 
a  system  of  push-buttons  and  buzzers.  Eacii 
button  (receptor)  is  connected  (ner\ous 
system)  to  its  own  buzzer  (effector).  A  pai- 
ticular  buzz  is  a  response.  Actually  this 
analogy  is  much  too  simple.  Different  pat- 
terns of  pushes  should  produce  different 
patterns  of  buzzes,  and  the  system  of  con- 
nections should  change  from  time  to  time 


This  chapter  was  prepared  by  Clifford  T.   Morgan  of  The  Johns  Hopkins  University. 

19 


20 


The  Response  Mechanism 


as  situations  change.     We  must,   howe\er, 
understand  the  simplest  things  first. 

DIFFERENTIATION    OF    THE 
RESPONSE    MECHANISM 

All  around  tis,  all  the  time,  energy 
changes  are  going  on.  Light  is  emitted  by 
tlie  sun,  stars,  fires  and  man-made  light 
bidbs;  it  is  reflected  by  the  moon,  the  walls 
ot  our  rooms,  the  plants,  our  clothes  and 
the  earth.  Heat  is  given  off  in  the  absorp- 
tion of  light,  in  chemical  process  in  our 
bodies,  from  machinery  and  from  hot  ob- 
jects; it  is  absorbed  by  the  cold  objects  in 
our  environment.  Electromagnetic  waves 
are  sent  out  by  our  radio  and  radar  trans- 
mitters and  picked  up  by  sensitive  receivers. 
Sounds  are  made  by  the  whirling  of  the 
wind,  the  boiling  of  the  water  or,  generally, 
whenever  one  object  strikes  or  rubs  against 
another.  Changes  in  chemical  energy  oc- 
cur in  food  as  it  is  being  cooked,  in  the 
barnyard,  in  the  brewery,  in  the  plants 
around  us  and  in  the  tissues  of  our  bodies. 

The  Stimulus 

Many,  but  not  all,  of  these  energ)'  changes 
afl^ect  living  tissues.  Radio  and  magnetic 
waves  do  not,  some  frequencies  of  light  and 
sound  do  not  and  some  chemical  substances 
are  relatively  inactive.  On  the  other  hand. 
X-rays  can  destroy  living  tissue,  infrared 
rays  heat  it  up,  ultraviolet  rays  assist  in 
the  synthesis  of  vitamin  B  in  the  body. 
Heat  causes  changes  in  chemical  reactions 
in  our  tissues  and,  if  extreme  enough,  can 
destroy  them.  Sounds  set  tissues  into  vibra- 
tion, causing  mechanical  changes  in  them 
and,  at  certain  frequencies  and  intensities, 
destroying  them.  Chemical  reactions  are 
necessary  for  the  growth  and  maintenance 
of  living  cells  but,  if  of  the  wrong  kind,  can 
kill  them. 


Ot  those  energy  changes  which  affect 
living  tissues,  some  produce  responses  in 
the  organism,  others  simply  affect  the  tis- 
sues directly.  Those  energy  changes  which 
produce  responses  are  defined,  for  the  pur- 
poses of  scientific  psychology,  as  stimuli. 
Thus,  in  man,  who  is  equipped  with  recep- 
tors and  effectors  for  responding,  the  word 
stimulus  is  used  to  describe  any  change  in 
the  energies  outside  a  receptor  which  is 
responsible  for  altering  the  physical-chemi- 


FIGURE  3.      RESPONSE  OF  AMOEBA  TO  STIMULATION 

(a)  Just  stimulated  by  glass  rod,  S;  (b)  change  of 
flow  of  protoplasm  and  response  of  amoeba  to  such 
stimulation. 


cal  state  of  the  receptor  in  such  a  way  that 
excitation  is  initiated.  The  essential  char- 
acteristics of  a  stimidus,  we  may  note,  are 
described  in  the  same  quantitative  units  as 
are  employed  in  the  sciences  of  physics  and 
chemistry. 

Man's  response  mechanism  is  very  com- 
plex. We  may,  however,  more  easily  un- 
derstand it  by  seeing  how  it  got  to  be  the 
way  it  is,  how  the  response  mechanism 
evolved  from  the  simple  to  the  complex. 

Look  at  a  simple  unicellular  animal,  the 
amoeba.  It  has  no  specialized  receptors, 
no  organs  for  the  reception  of  stimuli,  for 
the  transmission  of  excitation  or  for  the 
effecting  of  response.  Yet  the  amoeba  is  a 
self-contained,  living  system,  which  may  be 
acted  upon  and  changed  by  many  of  the 
same  physical  stimuli  which  are  significant 
in  complex  animal  behavior  and,  indeed, 
in  the  whole  psychological  life  of  man. 
Radiant  energ)',  \ibrations  in  its  surround- 
ing medium,  chemical  and  other  energies 


Differentiation  of  the  Response  Mechanism 


21 


;h  t  upon  (lie  ;iitio('h;i  ;<ik1  initiate  processes 
in  the  single  cell.  If  strong  light  or  heat, 
for  example,  is  projected  upon  one  side  of 
an  amoeba,  the  creature  contracts  its  body 
on  the  stimulated  side  in  such  a  way  as  to 
effect  its  withdrawal  from  the  stimulus.  As 
the  result  of  processes  so  initiated  the 
orientation  of  the  organism  in  relation  to 
its  environment  may  be  changed.  The 
amoeba,  like  man,  responds  to  the  stimuli 
in  its  environment. 

Evolution  of  the  Response  Mechanism 

Between  the  amoeba  and  man,  there  is 
obviously  a  vast  difference,  not  only  in  the 
complexity  of  the  organism  as  a  whole,  but 
also  in  the  response  mechanism.  It  is  a 
difference  in  the  number  of  cells  involved 
and  in  the  specialization  of  their  functions. 
Above  the  amoeba  in  the  evolutionary 
scale  are  the  simple  multicellular  organisms 
like  the  sponge  and  the  jellyfish.  In  them 
we  see  the  first  steps  in  the  differentiation 
which  finally  residts  in  the  complex  re- 
sponse mechanism  of  man.  The  very  first 
step,  the  most  primitive  differentiation, 
consists  in  the  appearance  of  the  independ- 
ent muscle-effector  cell,  as  seen  in  the 
sponge.  These  independent  effectors  of 
the  sponge  are  more  sensitive  to  external 
physical  stimuli  than  primitive  undifferen- 
tiated cells  like  amoebae.  Tliey  contract 
more  readily  and  vigorously  than  primitive 
cells,  thus  featuring  response  to  external 
stimulation. 

After  the  specialization  of  cells  for  re- 
sponse had  begun  in  the  evolutionary  de- 
velopment, there  came  the  differentiation 
of  special  cells  for  excitation  by  stimuli,  the 
receptor  cells.  In  such  primitive  animals 
as  the  sea  anemone,  these  receptor  cells 
took  the  form  of  diffuse  nerve  nets  which 
are  excited  by  external  stimuli  and  dis- 
tribute the  excitation  to  effector  cells.     It 


was   in    this  way   that   the:  rereptor-efjff lor 
mechanism  first  appeared  (¥i^.  4,  /I). 

Finally,  in  somewhat  higher  animaS 
forms,  specialized  nerve  or  ganglion  cells 
(adjustors)  came  to  he  interposed  between 
the  receptors  and  effectors  to  make  up  a 
true  nervous  system  for  conducting  excita- 
tion from  receptors  to  effectors  (Fig.  4,  B). 
Such  a  ganglionic  nervous  system,  or  recep- 
lor-adjustor-elfector  mechanism,  is  seen   in 


FIGURE   4.      PRIMITIVE   RESPONSE    MECH.\MSMS 

(A)  A  simple  receptor-effector  mechanism;  <B)  a 
receptor-adjustor-effector  mechanism.  [From  G.  H. 
Parker,  The  elementary  nervous  system,  Lippincott, 
1919,  pp.  201  f.] 

worms.  Thereafter,  this  mechanism  in- 
creases in  complexity  and  also  in  effective- 
ness in  the  series  of  vertebrate  and  mam- 
malian animals  to  reach  its  highest  devel- 
opment in  man. 

The  Effectors 

To  the  muscle  cells,  which  were  the  first 
effectors  to  appear  in  evolution,  ^vas  later 
added  another  class  of  effectors,  the  glands, 
so  that,  in  man,  we  must  distinguish  two 
main  classes  of  effectors,  the  muscles  and 
glands.  The  glands  secrete  chemical  sub- 
stances, needed  in  the  bodv"s  functions,  and 
deliver  them  into  the  blood  stream  for 
general  circulation  or  into  special  cavities 
of  the  body  like  the  moudi  or  stomach. 


22 


The  Response  Mechanism 


The  muscles  are  of  three  kinds,  varying 
according  to  the  amount  and  kind  of  dif- 
ferentiation which  they  have  undergone 
(Fig.  5).  (1)  Most  primitive,  or  least  differ- 
entiated, of  the  muscle  effectors  is  the  un- 
striped.  or  smooth,  muscle  cell  (D).     It  is 


\l\|i|l!j||Pi(^ 


'!)m^ri<<>£^'' 


FIGURE  5.      TYPES  OF  MUSCLE  FIBERS 

(A,  B)  Striped  muscle  fibers:  (C)  heart  muscle 
fibers;  and  (£))  smooth  muscle  fibers.  [From  M.  F. 
Guyer,  Animal  biology  (3rd  ed.),  Harper,  1941,  p. 
405.] 

foiuid,  for  example,  in  the  walls  of  the 
intestine.  Typically  a  spindle-shaped  cell, 
it  contains  within  it  a  special  substance,  the 
fibrillae,  upon  which  its  contractual  prop- 
erties depend.  (2)  More  elaborate  in  form, 
however,  is  a  second  class  of  muscle  cells, 
the  striped  muscle  cells  {A,  B),  which  are 
typical  of  arm  and  leg  muscles.  They  are 
much  more  elongated  than  smooth  muscle 
cells  and  are  enclosed  in  a  special  elastic 
membrane,  the  sarcolemma.  In  them  the 
contractile  fibrillae  are  differentiated  into 
two  substances,  one  darker  than  the  other, 
the  regular  alternation  of  which  through- 
out the  length  of  the  fiber  gives  the  muscle 
cell  its  striped  appearance.  (3)  A  third  type 
of  muscle,  the  cardiac  muscle  of  the  heart 
(C),  is  actually  a  special  kind  of  striped 
muscle.  Its  chief  distinction  is  that  its 
fibers  are  not  arranged  parallel  or  enclosed 
in  a  membrane  as  are  the  striped  muscle 
cells,  but  branch  and  unite  with  each  other 
in  a  network. 


All  muscle— be  it  smooth,  striped  or  car- 
diac—is specialized  for  but  one  function, 
contraction.  The  excitation  transmitted 
through  the  adjustors  of  the  nervous  system 
initiates  the  essential  physical  and  chemi- 
cal events  in  the  muscle,  events  which  lead 
to  the  release  of  the  muscle's  stored  energy 
in  the  form  of  a  contraction.  Contraction 
is  the  final  step  which  determines  the  be- 
havior of  the  stimulated  organism. 

Because  glandular  cells,  in  most  instances 
at  least,  are  connected  with  the  cells  of  the 
nervous  system  and  respond,  like  muscle 
cells,  to  excitation  transmitted  by  the  ad- 
justors, they  too  are  called  effector  cells. 
The  differentiation  by  which  glands  have 
developed   their  secretory   function   is   not 


(a)  (b) 

FIGURE   6.      DIAGRAMS   OF  ENDOCRINE  GLANDS 

(a)  Glatid  composed  of  irregular  sacs  (heavy  bhisk 
lines)  surrounded  by  tissue  and  blood  vessels  (e.g., 
thyroid  and  ovary);  (b)  gland  simply  consisting  of 
epithelium  (black)  penetrated  by  networks  of  blood 
\essels  (white).  Most  endocrine  glands  belong  to 
this  type  (adrenals,  pancreas,  parathyroids,  hypoph- 
ysis). [From  A.  A.  Maximow  and  W.  Bloom, 
A  textbook  of  histology  (4th  ed.),  Saunders,  1941, 
p.  291.] 

particularly  prominent  in  their  structure, 
for  they  look  very  much  like  simple  cells 
of  the  skin.  They  differ,  however,  in  their 
chemical  function  and  in  the  way  in  which 
they  deliver  their  secretions  into  the  body. 
In  fact,  glands  may  be  classified  into  two 


Endocrine  Effectors 


23 


principal  groups:  (1)  duel  or  exocrine 
glands,  like  the  salivary  and  the  tear 
glands,  which  pour  the  product  of  secretion 
through  a  tube  into  a  cavity  o£  the  body  or 
out  upon  the  body  surface,  and  (2)  endo- 
crine glands,  as  shown  in  Fig.  6,  of  which 
the  thyroid  and  the  adrenal  glands  are 
typical,  and  which  have  no  ducts  but  pour 
their  secretions  directly  into  the  blood 
stream.  Such  endocrine  secretions,  called 
hortnones,  must  be  taken  into  consideration 
for  a  complete  imderstanding  of  the  re- 
sponse mechanism.  We,  therefore,  must 
consider  them  in  more  detail. 

Endocrine  Effectors 

The  adrenal  glands,  for  exampfe,  are 
known  to  be  directly  involved  in  the  physi- 
ological expression  of  emotion.  Two  forms 
of  secretion,  both  of  which  are  circulated 
in  the  blood  stream,  are  produced  by  these 
glands:  the  hormone  from  the  medulla  of 
the  gland,  which  is  called  adrenalin  (some- 
times epinephrine),  and  the  hormone  of 
die  cortex  of  the  gland,  which  is  called 
cortin.  Cortin  is  made  up  of  several  chemi- 
cally distinct  hormones,  active  in  several 
bodily  functions.  Thus  cortin  has  a  slight 
effect  on  the  sugar  content  of  the  blood  and 
tissues,  but  more  significant  is  its  role  in 
controlling  sodium  and  water  content.  If 
cortin  is  withdrawn  by  removal  of  the 
adrenal  cortex,  sodium  is  excreted  through 
the  kidneys,  and  the  sodium  level  falls  in 
the  blood  stream  and  tissues  of  the  body. 
Sodium,  in  turn,  is  necessary  for  the  reten- 
tion of  water  in  the  body,  and  lack  of  cortin 
therefore  causes  dehydration.  Sodium  is 
also  necessary  for  nervous  excitability,  and 
without  it  animal  organisms  become  in- 
active and  may  eventually  go  into  a  coma 
and  die.  This  condition  occurs  with  a 
severe  deficiency  of  cortin,  but  it  may  be 
partially      remedied      by      feeding      large 


amounts  of  sodium  chloride  (common  salt; 
to  make  up  for  the  large  amounts  lost  from 
the  body. 

liesides  cortin,  the  adrenal  cortex  secretes 
in  small  amounts  some  of  the  so-called 
androgenic  hormones,  hormones  having  the 
same  physiological  effects  as  the  hormones 
secreted  by  the  glands  of  sex  (see  below;. 


Parathyroids 
Thyroid 
Thymus 


FIGURE    7.       SILHOUETTE    OF    THE    HUMAN     FIGURE 
SHOWING    LOCATION    OF    ENDOCRINE    GLANDS 

[From  R.  G.  Hoskins.  Tides  of  life.  Norton.  1933. 
p.  19.] 

Cortin  is  itself  closeh'  related  chemically 
to  these  hormones  and  is  derived  from  the 
same  tissues  in  embryological  dexelopment. 
In  many  of  the  commonlv  observed  fea- 
tures of  emotion  we  can  see  the  physiologi- 
cal effects  of  the  hormone  adrenalin  which 
is  poured  into  the  blood  stream  in  times  of 
emotional  reaction.  An  increase  in  the 
amount  of  adrenalin  in  the  blood  has  the 
following  effects  upon  physiological  activ- 
ity: (1)  it  increases  the  tremor  in  striped 
(voluntary)  muscles;  (2)  it  causes  relaxation 
of  smooth  (involuntary)  muscle;  (3)  it 
counteracts  fatigue  in  striped  muscle.  b\ 
facilitating   the    transmission   between    the 


24 


The  Response  Mechanism 


adjustor  and  the  muscle  effector;  (4)  it 
alters  distribution  of  the  blood  in  the  body, 
sending  more  blood  to  the  Aoluntary  mus- 
cles, less  to  the  digestive  tract;  (5)  it  in- 
creases blood  pressure;  (6)  it  hastens  clot- 
ting of  blood;  (7)  it  relaxes  the  bronchioles 
in  the  hmgs:  (8)  it  causes  the  liver  to  re- 
lease sugar  into  the  blood  stream;  and  (9) 
it  causes  the  spleen  to  secrete  or  release  red 
corpuscles  into  the  blood  stream.  All  these 
physiological  changes  brought  about  by 
adrenalin  may  be  considered  emergency 
reactions  which  prepare  an  organism  to 
meet  situations  calling  for  quick  and  prob- 
ably prolonged  discharge  of  energ)'.  (See 
pp.  95  f.) 

The  thyroid  gland  is  directly  related  to 
the  metabolism  of  the  body,  that  is  to  say, 
to  the  destructive  and  constructive  changes 
in  the  body  tissues.  Its  hormone,  thyroxin, 
acts  as  an  agent  which  facilitates  the  break- 
ing do^vn  of  waste  products  so  that  they  can 
be  readily  eliminated  from  the  body.  If 
the  thyroid  gland  is  underactive,  partially 
decomposed  proteins  are  retained  in  the 
tissues,  oxidation  is  lessened,  blood  pres- 
sure falls  and  metabolic  processes  are  gen- 
erally slo^ved  up.  If  the  thyroid  gland  is 
overactive,  on  the  other  hand,  metabolism 
is  increased  and  body  tissues  are  overstimu- 
lated. 

Situated  just  behind  the  stomach,  the 
pancreatic  gland  is  attached  to  the  intes- 
tinal tract  by  a  duct.  Through  this  duct, 
the  pancreas  deli\ers  secretion  to  the  di- 
gestive tract,  thereby  aiding  digestion;  in 
addition,  it  manufactures  a  hormone,  in- 
sulin, which  it  pours  directly  into  the 
blood.  This  hormone  is  concerned  pri- 
marily in  the  utilization  of  sugar  by  the 
tissues  of  the  body.  AVhen  insulin  concen- 
tration is  low,  as  in  diabetes,  blood  sugar 
does  not  get  into  the  tissues  to  be  used  but 


remains  in  the  blood  at  abnormally  high 
levels.  "When  insulin  concentration  is  ex- 
cessively high,  the  opposite  process  occurs, 
and  sugar  leaves  the  blood  to  be  deposited 
in  the  liver,  the  muscles  and  the  brain. 
Sugar  in  the  blood  is  utilized  as  fuel  by  the 
brain  and  muscles.  It  is  especially  impor- 
tant for  the  brain,  which  uses  sugar  almost 
exclusively. 

The  gonadal  glands  are  important  in  the 
development  of  secondary  sex  characteris- 
tics and  also,  to  a  considerable  extent,  in 
sexual  motivation.  (See  pp.  1 16-1 18.)  The 
adult's  secondary  sex  characteristics,  which 
are  determined  in  great  part  by  the  gonadal 
hormones,  include  height,  weight,  the  dis- 
tribution of  hair  over  the  body,  subcu- 
taneous fat  and  the  development  of  the 
mammary  glands,  all  of  which  are  features 
distinguishing  the  two  sexes.  In  animals. 
moreo\'er,  these  hormones  are  important  as 
determiners  of  sexual  beha\'ior,  and  they 
are  undoubtedly  of  significance  too  in  the 
sexual  behavior  of  man,  although  it  has 
been  shown  that  man's  sexual  conduct  is 
also  influenced  greatly  bv  his  ctistoms  and 
moral  codes. 

The  pituitary  gland,  sometimes  called 
the  master  gland  and  located  deep  within 
the  skull  at  the  base  of  the  brain,  manu- 
factures many  different  hormones.  Among 
them  are  many  whose  principal  function  is 
to  stimulate  or  regidate  other  glands  of  the 
body.  There  is  also  the  growth  hormone 
which  comes  from  the  pituitary  gland  and 
is  important  in  regulating  body  growth. 
Deficiency  of  the  growth  hormone  in  child- 
hood creates  a  dwarf;  excess  may  produce 
a  giant,  a  very  tall  person  with  a  long 
spindly  frame.  In  general,  impairment  of 
pituitary  function  in  childhood  results  in 
a  deficient  body  structin^e,  weakened  striped 
muscles  and  tniderde\eloped  sex  organs. 


The  Receptors 


25 


The  Receptors 

Receptor  cells  are  cells  upon  which  the 
physical  stimuli  ol'  the.  environment  act 
and  which  start  in  motion  tlie  processes  by 
which  the  organism  makes  adjustment  to 
stimulation.  It  is  instructive  to  observe 
how  receptors  have  been  differentiated  in 
evolution,  changing  their  structures,  their 
positions  in  the  body  and  their  chemical 
make-up  so  as  to  respond  to  different  types 
of  physical  energy.  The  first  primitive 
step  (noted  above)  in  the  differentiation  of 
receptors  is  the  relative  increase  in  excita- 
bility of  receptor  cells  as  compared  with 
other  tissues.  Further  evolution  has  car- 
ried this  trend  forward  by  specializing  cer- 
tain receptors  to  respond  to  one  kind  of 
stimulation  and  other  receptors  to  be  ex- 
cited by  other  kinds.     (See  Fig.  8.) 

As  a  result  of  this  differentiation,  in  man, 
receptors  may  be  divided  into  four  classes: 
thermal  (warmth  and  cold),  mechanical, 
chemical  and  light  receptors.  The  fourth 
class,  the  light  receptors,  differs  from  the 
others,  in  that  it  has  arisen  through  the 
differentiation  of  special  chemical  mate- 
rials in  the  cell  which  are  responsive  to 
light.  In  none  of  these  specializations, 
however,  does  a  receptor  completely  lose 
sensitivity  to  other  kinds  of  energy  change; 
its  development  results  only  in  a  special  in- 
crease in  one  type  of  sensitivity.  Thus  the 
thermal  receptors  are  more  sensitiAC  to 
changes  in  temperature  than  other  recep- 
tors, but  they  can  be  chemically  stimu- 
lated. For  the  mechanical  receptors  a  me- 
chanical stimulus  is  more  effective  than 
other  kinds  of  stimuli,  yet  thermal  stimu- 
lation may  affect  them. 

The  kind  of  stimulus  to  which  a  receptor 
is  most  sensitive  because  of  its  specializa- 
tion is  known  as  the  adequate  stitymliis; 
other  kinds  of  energy  changes  which  will 


excite  the  receptor  if  presented  in  unusual 
amounts  are  sometimes  called  inadequate 
stimuli,  being  inappropriate  and  therefore 
less  adequate.  As  a  result  of  this  differen- 
tiation with  respect  to  stimuli,  we  have  the 
following  specific  types  of  receptors  in  man: 
photic  receptors— the  eyes;  mechanical  re- 
ceptors—the ears  and  the  pressure  receptors 
in  the  skin;  chemical  receptors— taste,  smell, 
and  the  common  cheinical  receptors  in  the 


Specialized  nerve  cell 


^ 


W 


Unspecialized  receptor        Q 


Specialized   epithelial  cell     y 


4 


FIGURE    8.       TYPES    OF    SPECIALIZATION    OF    RECEP- 
TORS   AND    EPITHELIAL    CELLS 

[After  G.  H.  Parker:  from  C.  T.  Morgan,  Phyfio- 

loglcal  psychology,  McGraw-Hill,   1943,  p.  25.] 

mouth  and  nose;  and  thermal  receptors— 
the  receptors  in  the  skin  responsi\'e  to 
changes  in  temj^erature  and  giving  rise  to 
the  sensations  of  warmth  and  of  cold. 

Along  with  this  functional  differentia- 
tion of  the  receptors  ha\e  gone  changes  in 
their  structure— from  simple  to  complex. 
Those  chemical  receptors,  which  are  acti- 
vated only  by  high  concentrations  of  cliem- 
ical  substances,  are  very  simple  in  structure 
and  not  highly  differentiated  in  function. 
Tlie  receptors  for  taste  are  chemical  organs 
which  have  become  much  more  complex  in 
structure  and  precise  in  disaimination. 
The  receptors  for  smell  are  die  most  highlv 
developed  of  the  chemical  receptors.  They 
are  nerve  ceils  with  different  chemical  com- 
positions. The  same  differences  occur  for 
mechanical  stimulation.    The  receptors  for 


26 


The  Response  Mechanism 


touch  are  relatively  simple,  for  hearing  (a 
mechanical  sense)  extremely  complex. 

We  may  note  also  how  receptors  have 
taken  different  positions  in  the  body  in 
order  to  be  available  for  the  different  kinds 


Sensory 
peripheral 
neurons 


Proprioceptor 


FIGURE    9.       RELATIONSHIP    BETWEEN    THE    VARIOUS 

CLASSES   OF   RECEPTORS,   THE   NERVOUS   SYSTEM   AND 

THE    EFFECTORS 

A  diagram  to  show  the  relationship  of  exterocep- 
tors,  proprioceptors  and  interoceptors  to  the  periph- 
eral, central  and  autonomic  nervous  systems,  and 
to  the  muscular  and  glandular  effectors  of  the  body. 
[Adapted  from  various  sources.] 

of  Stimulation  which  come  to  act  at  the  dif- 
ferent positions.  Some  of  the  receptors  are 
at  the  surface  of  the  body,  so  located  that 
they  may  easily  be  affected  by  external  en- 
vironmental forces.  These,  called  extero- 
ceptors,  are  exemplified  by  the  receptor 
cells  of  the  eye.  Some  receptors,  on  the 
other  hand,  are  embedded  in   the  bodily 


substance  itself.  Typical  of  such  receptor 
cells  are  the  sensory  cells  of  the  muscles, 
which  are  stimulated  by  the  movement  of 
the  muscle  substance.  Such  receptors  are 
called  proprioceptors.  Proprio  means  self, 
and  these  receptors  inform  the  organism 
about  itself.  There  are  also  receptors  asso- 
ciated with  the  lining  of  the  digestive  tract, 
sometimes  called  interoceptors.  (See  Fig. 
9.) 

The  Adjusters 

The  central  nervous  system— the  adjustor 
mechanism— makes  possible  the  different 
connections  between  receptors  and  effectors 
and  consequently  between  the  impulses 
coming  in  from  receptors  and  going  out 
to  effectors.  The  possibility  of  this  switch- 
board-like action  is  due  in  part  to  the  fact 
that  the  continuity  of  the  nervous  system, 
as  it  was  seen  in  the  old  nerve-net  stage, 
has  given  place  in  the  receptor-adjustor- 
effector  system  to  relatively  independent 
nerve  cells  or  neurons.  In  understanding 
the  function  of  the  human  nervous  system, 
a  clear  knowledge  of  the  structure,  function 
and  interdependence  of  neurons  is  impor- 
tant.    (See  Fig.  10.) 

STRUCTURE    AND    FUNCTION 
OF    NEURONS 

First  we  need  to  establish  the  meanings 
of  a  few  terms.  The  central  nervous  system 
consists  of  the  brain  and  the  spinal  cord. 
In  it  lie  all  the  adjustor  mechanisms.  The 
peripheral  nei-uous  system  is  the  totality  of 
the  nerves  which  connect  the  central  nerv- 
ous system  with  the  receptors  and  effectors. 
The  afferent  nervous  system  is  the  totality 
of  nerve  fibers  which  connect  receptors  with 
the  spinal  cord  and  the  brain.  It  is  the  in- 
put or  sensory  half  of  the  peripheral  nerv 
ous  system.     The   efferent   nervous  system 


Neurons 


27 


FIGURE  10.      STRUCTURE  OF  SOME  TYPICAL  NEURONS 

(A)  A  typical  efferent  (motor)  neuron.  (B)  A  typ- 
ical afferent  (sensory)  neuron  (in  less  detail  than  A). 
(C)  Typical  central  (connector)  neurons  (in  less  detail 
than  A).  Abbreviations:  D  =  dendrites,  N  =  nu- 
cleus, CB  =  cell  body,  CO  =  collateral,  A  =  axon, 
NE  =  neurilemma  sheath,  M  =  myelin  (medullary 
sheath),  MU  =  muscle,  EN  =  motor  end  plate, 
TE  =  terminal  arborization  or  end  brush. 

is  the  totality  of  nerve  fibers  whicfi  lead 
from  the  spinal  cord  and  brain  to  the  effec- 
tors. It  is  the  output  or  motor  half  of  the 
peripheral  nervous  system. 

The  basic  unit  of  the  nervous  system  is 
the  neuron,  which  is  a  nerve  cell  having  a 
cell  body  and  nerve  fibers  leading  to  it  and 
away  from  it.  Impulses  are  ordinarily  ad- 
mitted to  a  neuron  by  fibers  called 
dendrites  and  are  passed  on  to  the  next  neu- 
rons by  the  fibers  called  axons.  Within  the 
single  neuron,  therefore,  impulses  are  nor- 
mally transmitted  from  dendrite  to  axon. 


In  the  simplest  cases  in  the  liuman  body, 
a  receptor  is  merely  a  free  ending  of  an  af- 
ferent neuron  of  the  peripheral  nervous 
system.  More  often,  however,  as  we  have 
just  seen,  a  receptor  is  a  specialized  cell 
associated  with  such  a  neuron.  The  af- 
ferent peripheral  neuron  itself  is  typically 
a  continuous  thread  of  protoplasm  connect- 
ing a  receptor  with  the  neurons  of  the  cen- 
tral nervous  system.  The  peripheral  fiber 
of  a  single  neuron  may  thus  be  several  feet 
long,  for  it  is  unbroken  from  receptor  to 
central  nervous  system,  although  it  is  micro- 
scopic in  diameter.  In  most  cases  each  neu- 
ron fiber  is  insulated  by  special  sheaths.  A 
great  many  insulated  fibers  are  ordinarily 
held  together  by  other  tissue  to  form  a 
cable  called  a  peripheral  nerve.  Such 
nerves  usually  contain,  at  least  for  certain 
distances,  many  independent  fibers  of 
which  some  may  be  efferent  and  others  af- 
ferent. 

Stimulation 

The  energy  changes  which  make  up  the 
world's  stimuli  act  upon  receptors  or  af- 
ferent neurons  to  cause  physical  and  chem- 
ical changes  in  the  fibers  of  the  neurons. 
These  disturbances  travel— propagate  them- 
selves—along the  fibers  and  cause  similar 
disturbances,  in  turn,  in  neurons  of  the  cen- 
tral nervous  system,  and  eventually  in  the 
effectors.  Stimulation  in  an  animal  thus 
initiates  processes  which  usually  lead  in  the 
course  of  time  to  effector  response  and  a 
change  of  the  individual  in  relation  to  its 
environment. 

Stimulation  is  in  some  respects  analo- 
gous to  the  finger  pressure  on  the  trigger 
which  initiates  the  release  of  energy  in  the 
gunpowder  of  a  cartridge,  and  thus  leads  to 
the  expulsion  of  a  bullet  from  a  gun.  Ob- 
viously, in  the  cartridge,  the  explosion  of 
the  stored  energy,  not  the  mo\ement  of  the 


28 


The  Response  Mechanism 


finger,  is  what  drives  the  bullet.  In  the 
same  way,  the  release  by  stimvilation  of 
energy  stored  in  the  receptor  or  neuron  is 
what  starts  the  nervous  impulse  off.  Un- 
like the  bullet,  however,  the  impulse  is  not 
a  thing  which  moves  along  a  fiber.  It  is 
merely  a  progressive  release  of  energy;  that 
is  to  say,  the  physical  energy  of  the  stimulus 
does  not  itself  go  through  the  receptor  but 
releases   certain   energies   of   the   organism 


Direction  of  impulse 


Positive  ions 
Membrane  -[-      -|-      .f 


FIGURE    11.       SCHEMATIC    DIAGRAM    OF    EXCITATION 
AND    CONDUCTION    IN    THE    NERVE    MEMBRANE 

The  semipermeable  membrane  is  shown  in  black 
with  the  positive  ions  on  the  outside  and  the  nega- 
tive ions  on  the  inside.  A  local  current  flows  when 
the  polarization  of  the  membrane  breaks  down. 
That  part  of  the  membrane  which  is  being  restored 
after  the  passage  of  the  impulse  is  shaded.  Thus 
the  diagram  also  shows  the  refractory  periods. 
[Adapted  from  E.  G.  Boring.] 

located  in  the  receptor,  whereupon  other 
progressive  releases  of  energy  follow  all  the 
way  along  the  excited  fiber.  Movement  is 
analogous  to  the  movement  of  fire  along  a 
train  of  gunpowder  in  which  each  bit  of 
powder  is  ignited  by  a  preceding  bit  and  in 
turn  ignites  still  another  bit. 

Recent  research  has  shown  that  there  are 
complex  chemical  and  electrical  events  oc- 
cuning  in  a  receptor,  neuron  or  effector 
when  it  is  excited  by  a  stimulus.  The  place 
of  these  events,  it  is  now  known,  is  in  the 
membranes,  not  in  the  interior,  of  the 
microscopic  neuron  fiber.    Across  this  mem- 


brane, in  the  normal  resting  neuron,  there 
is  always  a  difference  of  electrical  potential, 
represented  in  Fig.  11,  created  between  the 
positive  ions  accumulated  on  the  outside 
and  the  negative  ions  accumulated  on  the 
inside  of  the  membrane.  This  electrical 
difference,  because  of  the  arrangement  of 
chemical  ions  on  the  two  sides  of  the  mem- 
brane, is  known  as  polarization  of  the  inem- 
brane. 

The  effect  of  the  trigger-like  action  of  a 
stimulus  applied  to  the  membrane  is  to  set 
off  a  series  of  chemical  reactions  in  the 
membrane.  The  most  important  result  of 
these  reactions  is  a  release  of  energy  conse- 
quent upon  a  sudden  depolarization  of  the 
membrane  and  a  rapid  change  in  the  rest- 
ing potential  across  the  membrane.  This 
sudden  and  progressive  electrical  change  is 
the  nervous  impulse. 

If  a  single  neuron  is  excited  by  a  stimu- 
lus which  sets  up  a  nervous  impulse,  the 
neuron  is  always  excited  to  its  maximum 
extent.  This  principle  is  known  as  the 
all-or-none  laxu.  The  law  may  be  stated 
formally  as  follows:  The  magnitude  of  the 
activity  in  any  single  neural  functional 
unit  is  as  great  as  it  can  be  in  that  unit  at 
that  time  and  is  independent  of  the  magni- 
tude of  the  energy  exciting  it,  provided 
only  that  the  stimulating  energy  is  suffi- 
ciently strong  to  excite  the  neuron  at  all. 
This  law  follows  from  the  more  general 
principle  that  the  characteristics  of  the  im- 
pulse at  any  point  depend  upon  the  state 
and  properties  of  the  fiber  at  that  point  and 
not  upon  the  nature  of  preceding  events. 

The  nervous  impulse  arises  at  any  point 
on  the  neuron  at  which  the  stimulus  is  ap- 
plied. Once  initiated,  it  in  turn  becomes  a 
stimulus  to  adjacent  points  on  the  mem- 
brane and  thus  the  impulse  propagates  it- 
self along  the  neuron  fiber,  like  a  burning 
train   of  gunpowder  or   a   burning  string. 


Stimulation 


29 


except  for  the  lact  that  burning  is  chemical, 
whereas  the  neural  impulse  is  an  electrical 
depolarization  which  is  set  off  by  an  im- 
mediately preceding  depolarization.  It  is 
important  to  remember  that  the  energy  of 
the  nervous  impulse  depends  upon  the 
energy  released  in  the  neuron,  not  upon 
the  energy  of  the  original  stimulus. 

The  progress  of  a  nervous  impulse  along 
a  fiber  may  be  recorded  on  a  galvanometer 
(as  represented  in  Fig.  12).  On  this  instru- 
ment, the  active  region  of  the  neuron  fiber 
is  seen  to  be  electrically  negative  in  relation 
to  the  unexcited  portion  of  the  same  fiber, 
because,  in  nervous  excitation,  the  normal 
polarization  of  the  membrane  with  positive 
ions  on  the  outside  is  destroyed  and  the  re- 
gion of  depolarization  (the  region  of  the 
impulse)  is  therefore  less  positive  and  thus 
more  negative  than  it  was  before  the  im- 
pulse arrived.  This  region  of  negativity, 
which  is  the  measure  of  the  impulse,  travels 
on  down  the  neuron.  Though  the  impulse 
travels  in  mammalian  neurons  at  varying 
speeds,  a  speed  of  approximately  one  hun- 
dred meters  a  second,  or  two  hundred  miles 
an  hour,  may  be  taken  as  typical.  Such  a 
speed,  though  relatively  fast,  is,  of  course, 
in  no  way  comparable  to  the  speed  of  light 
or  the  speed  of  an  electrical  impulse  in  a 
wire.  It  is  only  about  a  quarter  as  fast  as 
the  speed  of  sound. 

Returning  for  a  moment  to  the  analogue 
of  the  burning  trail  of  gunpowder,  Ave  may 
note  that,  once  a  gunpowder  trail  has  been 
burned,  it  cannot  be  ignited  again  until 
new  energy  in  the  form  of  a  new  trail  of 
powder  has  once  more  been  laid  down.  In 
the  nerve,  there  is  a  similar  effect.  Im- 
mediately following  the  peak  of  the  nerv- 
ous impulse,  there  is  a  period  during  which 
the  nerve  fiber  cannot  be  activated  again, 
no  matter  how  strong  the  stimulus.  The 
potential  difference  has  been  used  up.    This 


time  inicrval  is  known  technically  as  the 
absolute  refractory  period.  Then,  follow- 
ing this  period,  there  is  an  interval  of  con- 
tinuous recovery  during  which  the  neuron 
may  lie  stimulated  again,  provided  the 
stimulus  is  stronger  than  the  minimal  stim- 
ulus   which    ordinarily    is   effective.      This 


_Kr__  ^1^ 


■<I>- 


1. 


•0- 


_j: 


<!>■ 


1.. 


■I 


...x 


•0- 


FIGURE    12.      PROPAGATION   OF  AN   ELECTRICAL  DIS- 
TURBANCE   ALONG    A    NEURON    FIBER 

I,  II,  III,  IV  show  successive  time  intenals  as 
the  impulse  passes  from  left  to  right.  The  gal- 
vanometer deflection  is  indicated  in  each  case.  It 
will  be  noticed  that  the  impulse  is  marked  by  a 
negative  deflection.  Abbreviations:  S  =  stimulus, 
NI  =  nerve  impulse,   G  =  galvanometer. 

second  interval  is  called  the  relative  re- 
fractory period.  At  the  end  of  the  relati\e 
refractory  period,  the  excitability  of  the 
neuron  has  completely  reco\ered  and  die 
neuron  is  again  ready  for  activation  by  a 
stimulus  of  normal  degree.  In  certain  neu- 
rons, especially  in  the  larger  sensory  neu- 
rons and  Avhen  the  neurons  are  not  greatly 
fatigued,  it  has  been  demonsu-ated  diat 
there  may  be  a  brief  period,  immediately 
following    the    relative    refractory    period, 


30 


The  Response  Mechanism 


during  which  a  stimulus  of  an  intensity  less 
than  that  normally  required  to  excite  the 
resting  nerve  may  be  effective.  The  time 
during  which  this  phenomenon  is  possible 
has  been  called  the  supernormal  period.  A 
diagram  of  the  relation  of  these  various 
periods  is  given  in  Fig.  1 3. 


Time  in  thousandths  of  seconds 

FIGURE    13.      NERVE    EXCITATION 

Graph  shows  schematically  the  absolute  and  rela- 
tive refractory  periods  and  the  supernormal  period. 

Mechanisms  of  Intensity 

Because  animals  and  human  beings  are 
quite  capable  of  appreciating  differences  in 
the  intensity  of  various  stimuli,  it  is  inter- 
esting to  see  how  nervous  impulses  may  rep- 
resent these  differences  in  the  intensity  of 
stimulation.  Increasing  the  intensity  of 
stimulation  may  affect  nervous  impulses  in 
two  ways:  (1)  it  may  increase  the  frequency 
of  successive  nerve  impulses  in  a  particular 
neuron  fiber  and  (2)  it  may  increase  the 
number  of  fibers  in  which  there  are  nervous 
impulses. 

Laboratory  experiments  show  how  in- 
creasing the  intensity  of  the  stimulus  may 
increase  the  number  of  nerve  impulses  in  a 


single  neuron  fiber.  If  a  stimulus  is  ap 
plied  continuously  to  a  fiber,  a  strong  stimu- 
lus will  reexcite  the  fiber  at  an  earlier  stage 
of  the  refractory  period  than  a  weak  one. 
Consequently,  an  intense  continued  stimu- 
lus produces  a  relatively  rapid  series  of  suc- 
cessive impulses,  whereas  a  weak  stimulus 
may  produce  a  less  rapid  series.  The  rate 
of  discharge  in  a  peripheral  nerve  fiber  thus 
tends  to  become  greater  the  more  intense 
the  physical  energy  of  the  stimulus  applied 
to  it.  The  total  limits  of  this  frequency 
are,  as  can  be  seen  (Fig.  13),  always  deter- 
mined by  the  time  limits  of  the  relative 
and  absolute  refractory  periods  of  the  neti- 
rons  in  question. 

The  second  neural  mechanism  of  in- 
tensity is  an  increase  in  the  number  of 
neurons  being  excited.  To  understand  this 
mechanism,  it  should  not  be  forgotten  that, 
in  many  of  the  sense  organs,  as  well  as  in 
centers  of  the  nervous  system,  there  are 
many  receptors  or  neurons  exposed  at  the 
same  time  to  every  strong  stimulus.  The 
neurons  and  receptors  differ  among  them- 
selves with  respect  to  their  excitabilities, 
so  that  a  stimulus  of  a  particular  physical 
intensity  may  call  into  action  some,  but  not 
all,  of  the  neurons  being  stimulated. 

From  this  description  it  can  be  seen  that, 
when  the  intensity  of  the  stimulus  applied 
to  a  group  of  neurons  increases,  an  increas- 
ing number  of  individual  neurons  is  acti- 
vated as  each  neuron  reacts  in  an  all-or- 
none  manner.  It  thus  appears  that  an  in- 
crease in  the  intensity  of  a  stimulus  may  be 
associated  in  the  peripheral  nervous  system 
with  an  increase  in  number  of  units  af- 
fected as  well  as  with  an  increase  in  the 
number  of  impulses  per  second  in  each 
fiber  involved.  These  two  factors  jointh 
determine  the  intensity  of  sensation. 


Synapfic  Connections 


31 


Synaptic  Connections 

In  order  to  come  to  an  understanding  of 
the  response  mechanism,  we  have  dealt 
with  tlie  structure  and  properties  of  indi- 
vidual neurons.  Not  single  neurons,  how- 
ever, but  myriads  of  them,  connected  with 
each  other  in  many  diverse  ways,  make  up 
the  central  nervous  system.  Someone  has 
calculated  that  there  are  approximately 
twelve  billion  neurons  in  the  central  nerv- 
ous system.  At  first,  this  inconceivable 
complexity  might  seem  to  balk  any  hope  of 
understanding  the  mechanisms  of  the  nerv- 
ous system.  It  is  well  to  remember,  how- 
ever, that,  no  matter  what  the  complica- 
tions of  this  system  may  be,  it  is  possible 
to  look  at  it  as  basically  organized  for  the 
purpose  of  making  connections  between  in- 
coming and  outgoing  nerve  impulses. 

Neurons,  according  to  most  observers, 
are  not  actually  connected  one  with  an- 
other, for  each  is  an  individual  cell  with  its 
own  membrane.  Nevertheless,  the  fibers  of 
the  neurons  interlace  to  form  functionally 
effective  junctures,  which  are  known  as 
synapses.  Nowadays  a  general  understand- 
ing of  the  nervous  system  requires  a  knowl- 
edge not  only  of  the  properties  of  the  indi- 
vidual neurons  but  also  of  the  special  ana- 
tomical and  functional  characteristics  of 
synapses. 

Three  of  these  synaptic  characteristics 
are  worthy  of  special  attention.  (1)  In  the 
synapse,  fibers  tend  to  divide  many  times 
into  small  terminals  which  come  in  contact 
with  the  terminals  of  other  neurons  or,  in 
some  cases,  with  the  body  of  another  neu- 
ron. (2)  By  virtue  of  the  fact  that  each 
neuron  has,  usually,  several  collaterals  or 
branches  of  its  fibers,  one  neuron  usually 
makes  connections  with  many  other  neu- 
rons, both  afferent  and  efferent.  Thus, 
synapses  may  be  regarded  as  'choice  points' 


from  which  nervous  activity  may  be  trans- 
mitted along  different  neurons.  (3)  The 
synapse  acts  as  a  valve,  permitting  passage 
of  the  impulse  only  from  axon  to  dendrite. 
It  is  the  synapses  that  liriu't  the  nerve  fibers 
to  one-way  traffic. 

For  many  years  psychologists  have 
thought  of  the  synapses  as  having  resist- 
ance, just  as  water  in  a  large  main  meets 
resistance  when  it  comes  to  a  small  outlet, 
or  as  an  electrical  current  is  resisted  when 
it  is  conducted  through  a  very  small  wire. 
The  notion  of  synaptic  resistance  should 
be  regarded  only  as  an  analogy,  but  there 
are  conditions  at  the  synapse  which  give  it 
resistive  characteristics.  For  one  thing,  we 
know  from  the  all-or-none  law  that  the  size 
of  the  nervous  impulse  is  reduced  when  it 
comes  to  the  very  small  terminals  which  are 
common  at  the  synapses.  For  another 
thing  conduction  across  a  synapse'  means, 
of  course,  that  the  nei-ve  impulse  at  the 
terminals  of  the  fibers  of  one  neuron  must 
initiate  an  impulse  in  a  second  neuron,  in 
spite  of  the  discontinuity  of  the  mem- 
branes. For  this  reason  one  would  expect 
transmission  of  the  nerve  impulse  to  be 
more  easily  blocked  at  a  synapse  than  along 
a  neuron  fiber. 

Out  of  these  anatomical  and  functional 
characteristics  of  the  synapses  arise  some 
properties  of  the  central  nervous  system 
which  are  not  ordinarily  seen  in  peripheral 
nerves.  One  of  these  properties  is  spatial 
surnmation.  In  many  cases  an  impulse 
coming  along  a  fiber  to  a  synapse  is  not  suf- 
ficiently strong  to  excite,  by  itself,  the  ner^■e 
fiber  on  the  other  side  of  the  synapse.  In- 
stead, it  is  necessary  that  two,  three  or  even 
more  impulses  arrive  along  different  fibers 
and  stimidate  the  same  region  aaoss  the 
synapse  simultaneously.  In  this  Asay  the 
effect  of  impulses  arriving  at  the  cenual 
nervous    system    over    afferent    neurons    is 


32 


The  Response  Mechanism 


summative.  Such  spatial  summation  is  en- 
countered in  sensory  phenomena  and  re- 
flex behavior.  For  instance,  a  tiny  spot 
of  hght,  too  faint  to  be  perceived,  may  be- 
come visible  if  its  size  is  doubled,  simply 
because  more  adjacent  fibers  are  activated 
simultaneously  and  their  impulses  are  sum- 
mated  at  some  synaptic  point. 

Another  important  characteristic  of  activ- 
ity in  the  central  nervous  system  is  reverter- 


if^ 


u 

1^ 


V 


"X" 


FIGURE    14.       RECURRENT    (REVERBERATORY)    NERVE 
CIRCUITS 

The  circles  represent  cell  bodies;  the  lines  repre- 
sent the  axons  and  dendrites.  Direction  o£  the 
nerve  impulse  is  indicated  by  the  arrows.  [From 
C.  T.  Morgan,  Physiological  psychology,  McGraw- 
Hill,  1943,  p.  64.] 

ation.  By  tracing,  with  electrical  record- 
ing, the  impulses  in  groups  of  neurons  in 
certain  centers  of  the  nervous  system,  it  has 
been  possible  to  demonstrate  that  neurons 
are  frequently  arranged  in  circuits  in  which 
the  fiber  of  one  neuron  comes  back  and 
ends  on  the  neuron  whose  fiber  stimulated 
the  first  neuron.  A  typical  arrangement  of 
neurons  in  such  a  recurrent  nervous  circuit 
is  shown  diagrammatically  in  Fig.  14. 
Such  an  arrangement  of  neurons  means 
that  in  the  central  nervous  system  activity 
may  be  set  up  by  a  stimulus  and,  unlike 
the  situation  in  peripheral  neurons,  may 
continue  for  some  time  after  the  stimulus 
has  disappeared.  This  principle  of  rever- 
beration has  many  important  applications 
in  understanding  the  response  mechanism 


and  human  psychological  capacities.  It  ac- 
counts in  some  instances  for  the  persistence 
of  sensory  motivation.  A  pang  of  hunger 
or  surge  of  fear,  for  example,  may  start 
activity.  Often  the  activity  persists,  even 
though  the  hunger  or  fear  subsides.  The 
nervous  system  seems  often  to  hang  on  to 
such  motives,  and  reverberation  may  well 
be  the  mechanism. 

A  third  characteristic  of  central  nervous 
function  is  recruitment.  This  term  refers 
to  a  progiessive  increase  in  the  number  of 
nerve  fibers  giving  nervous  impulses  as  the 
exciting  impulse  is  repeated.  The  phe- 
nomenon of  recruitment  is  based  on  the 
fact  that  the  excitability  of  a  neuron  varies 
from  time  to  time  and  that,  on  repeated 
stimulation,  the  fiber  that  fails  to  respond 
on  the  first  or  second  try  may  be  activated 
on  the  third  or  fourth  because  by  that  time 
it  has,  in  the  random  variation  of  its  sensi- 
tivity, become  more  excitable.  Once  ex- 
cited, there  is  a  tendency  for  a  nerve  fiber 
to  continue  giving  nervous  impulses  be- 
cause of  the  chance  of  stimulation  during 
the  supernormal  phase. 

Recruitment  has  also  been  demonstrated 
in  peripheral  nerves,  but  it  is  a  more  im- 
jjortant  phenomenon  in  the  central  nerv- 
ous system.  Recruitment,  especially  when 
taken  in  connection  with  reverberation,  ex- 
plains many  cases  in  which  persistent  activ- 
ity becomes  more  vigorous  as  it  persists. 
Reverberation  and  recruitment  are  sta- 
bilizing factors  in  the  lives  of  the  higher 
vertebrates.  They  keep  the  organism  from 
mirroring  in  its  behavior  every  casual 
change  in  its  stimulating  environment. 

STRUCTURE    OF    THE    NERVOUS 
SYSTEM 

It  is  now  time,  after  being  introduced  tc 
neurons  and  synaptic  functions,  to  take  up 


Sirucfure  of  the  Nervous  Sysfem 


33 


the  nervous  syslcin  as  a  whole  and  lo  con- 
sider its  general  structure  and  functions. 
This  system,  in  man,  is  made  up  of  the 
brain,  the  spinal  cord,  the  autonomic  nerv- 
ous system,  the  afferent  peripheral  nervous 
system,  the  receptors,  the  efferent  periph- 
eral nervous  system  and  the  effectors  (Fig. 
15). 

The  spinal  cord  is  the  part  of  the  nerv- 
ous system  that  is  enclosed  in  the  jointed 
iDony  case  of  the  vertebral  column.  It  is 
connected  with  receptors  and  effectors  by 
more  than  thirty  pairs  of  spinal  peripheral 
nerves.  The  spinal  cord  is  primarily  to  be 
thought  of  as  a  cable  of  insulated  fibers, 
by  means  of  which  impulses  initiated  at 
the  receptors  may  be  transmitted  to  and 
from  the  higher  centers  of  the  brain.  Yet 
the  cord  is  also  in  its  own  right  a  center 
for  the  connection  of  afferent  and  efferent 
neurons  taking  part  in  the  action  of  rela- 
tively simple  reflexes. 

Continuous  with  the  spinal  cord  and 
protected  by  the  bony  case  of  the  skull  is 
a  very  complex  system  of  nerve  centers  and 
communication  tracks  known  as  the  brain. 
Immediately  above  the  cord  and  in  con- 
tinuity with  it  is  located  the  medulla 
oblongata.  Like  the  cord,  the  medulla  is 
an  important  adjustment  center  in  its  own 
right,  but  it  is  primarily— again  like  the 
cord— to  be  regarded  as  a  great  cable  of 
fibers  connecting  the  spinal  system  below 
with  the  higher  brain  centers  above.  In 
addition,  however,  it  plays  a  vital  role  in 
the  control  of  certain  bodily  functions, 
such  as  breathing,  heart  rate  and  circula- 
tion of  the  blood. 

Situated  above  the  medulla,  and,  as  it 
were,  off  the  main  track  of  the  central 
nervous  system,  are  the  two  hemispheres  of 
the  cerebellum,  which  functions  in  the  co- 
ordination of  bodily  movements.  In  front 
of  the  cerebellum,  there  is  a  large  structure. 


the  pons,  made  up  (jI  fiber  tracks  and  sjjc- 
cialized  adjustment  centers.  Above  the 
cerebellum  and  pons  is  an  elaborate  scries 
of  special  connecting  centers,  all  of  which 
f)iay  an  important  part  in  the  adjustment 


Base  of  frontal  lobe  _ 
of  cerebral  hemisphere 


Base  of  temporal  lobe      fX 
of  cerebral  hemisphere 


Cerebellum ^. 

Base  of  occipital  lobe^--^ 
of  cerebral  hemisphere 


Chain  of  ganglia  of 
autonomic  nervous  system 


Longitudinal  fissure 

( between  cerebral 

hemispheres) 

Olfactory  bulb 

Cut  end  o( 
one  optjc  nerve 

Optic  chiasma 

Pons 

Cut  ends  of  other 
typical  cranial  nerves 

I  Cervical  spinal  nerve 


I  Thoracic  spinal  nerve 


ts"  Lumbar  spinal  nerve 


Sacral  spinal  nerve 


FIGURE    15.      BASE  OF   BRAIN   AND  SPINAL  CORD 

Heavy  black  structure  at  left  of  cord  indicates 
part  of  autonomic  nervous  svstera.  [Adapted  from 
C.  J.  Herrick,  An  introduction  to  neurology,  1931: 
by  permission  of  the  W.  B.  Saimders  Co.] 

of  imptilses  and  in  the  adaptation  of  the 
organism  to  its  environment.  Much  is 
known  concerning  these  centers,  and  much 
is  still  to  be  discovered.  It  is  impossible 
to  review  here  their  anatomical  relation- 
ships. It  is  important  to  note,  nevertheless, 
that,  before  we  reach  the  cerebral  cortex, 
the  upper  le\el  of  the  central  nervous  svs- 
tem,  ^ve  pass  through  a  complex  group  of 


34 


The  Response  Mechanism 


amplifying  and  contributing  centers  known 
as  the  thalamus,  or  thalamic  region.  The 
thalamus  proper  is  concerned  mainly  with 
rela)ing  afferent  impulses  on  their  way 
from  the  sense  organs  to  the  cerebral  cor- 
tex, but  the  parts  known  as  the  subthala- 


Receptor  Effector 

FIGURE    16.       LEVELS    OF    THE    CENTRAL    NERVOUS 
SYSTEM 

Schematic  diagram  showing  alternative  loops  at 
various  levels  of  the  central  nervous  system.  Many 
other  schemes  of  levels  in  the  nervous  system  have 
been  proposed.  The  diagram  given  here  does  not 
represent  an  accepted  view  of  the  hierarchy  of  gov- 
erning centers  but  is  given  to  emphasize  the  fact 
that  there  are  levels  in  the  brain  and  that  they  in- 
fluence each  other.  [Adapted  from  W.  M.  Bayliss, 
Principles  of  general  physiology,  1927;  by  permis- 
sion of  Longmans,  Green.] 

mus  and  hypothalamus  are  concerned  with 
the  control  and  coordination  of  bodily 
functions  involved  in  metabolism,  and  the 
hypothalamus  has  also  a  special  role  in 
the  expression  of  emotion.  More  will  be 
said  elsewhere  (see  p.  100)  concerning  this 
function  of  the  hypothalamic  region. 

In  man,  by  far   the  largest  part  of  the 
brain  is  the  great  cerebrum,  which  is  di- 


vided into  two  cerebral  hemispheres. 
Large,  closely  organized  masses  of  neurons, 
these  structures  almost  fit  the  skull.  The 
surface  of  the  hemispheres  is  the  cerebral 
cortex.  It  is  convoluted  and  deeply  fis- 
sured, and  in  it  lie  the  cell  bodies  of  the 
cerebral  neurons,  the  gray  matter  of  the 
brain.  The  cerebruin  is  constructed  both 
to  receive  impulses  from  and  to  send  im- 
pulses back  to  the  lower  levels  of  the  cen- 
tral nervous  system.  It  thus  forms  an  ad- 
justment center  for  recircuiting  and  pat- 
terning impulses,  a  center  superimposed,  as 
it  were,  upon  the  lower,  more  immediate, 
connecting  centers  of  the  central  nervous 
system.  Sometimes  the  activities  of  the 
cerebral  hemispheres  facilitate  processes  al- 
ready in  progress  in  lower  centers;  some- 
times, on  the  contrary,  they  inhibit  such 
processes. 

The  Efferent  Peripheral 
Nervous  System 

We  have  seen  how  sensory  activity  tends 
to  spread  out  over  many  paths,  ultimately 
involving  many  regions  of  the  central  nerv- 
ous system.  Often  it  is  this  total  complex 
of  excitation  that  determines  just  which  ef- 
fectors shall  be  activated  and  how.  Dis- 
tributed excitation  must  be  brought  to- 
gether to  act  along  particular  efferent  paths 
upon  specific  effectors  if  response  is  to  be 
adequate  to  the  needs  of  the  organism.  We 
may  think  then  of  the  efferent  system  as  the 
place  where  excitation  converges  upon  final 
common  neural  paths  to  produce  response. 

The  final  common  path  is  the  name  ap- 
plied to  the  avenue  along  which  all  im- 
pulses, no  matter  whence  they  come,  must 
travel,  if  they  are  to  act  on  particular  mus- 
cle fibers  or  glands  and  bring  about  the 
corresponding  response.  Thus  activities  in 
various  parts  of  the  brain  and  spinal  cord, 
which  have  resulted,  it  may  be,  from  ex- 


The  Autonomic  Nervous  System  and  the  Bram 


35 


leroceptive  stimulation,  can  be  brought 
into  relation  with  impulses  from  other 
parts  of  the  central  nervous  system  which 
have  themselves  originated,  for  example,  in 
the  proprioceptors  of  certain  muscles. 
Some  of  these  impulses  may  mutually 
strengthen  or  facilitate  one  another;  some 
may  act  in  such  a  way  as  to  lead  to  mutual 
extinction  or  inhibition.  In  the  normal 
individual  the  oiucome  of  such  complex 
adjustment  is  the  finely  graded  and  pre- 
cisely timed  effector  response.  In  this  way 
activities  occur  which  make  up  adaptive, 
intelligent  behavior. 

The  Autonomic  Nervous  System 

In  a  complete  consideration  of  the  motor 
aspects  of  the  response  mechanism,  it  is 
necessary  to  deal  with  the  so-called  auto- 
nomic nervous  system,  a  motor  nervous  sys- 
tem which  enjoys  a  measure  of  independ- 
ence from  the  great  peripheral  and  central 
systems  already  considered.  This  system, 
together  with  the  secretions  of  the  endo- 
crine glands,  constitutes  a  neurohumoral 
system  which,  to  a  large  degree,  controls 
the  organic  functions  of  the  body— the  di- 
gestive functions,  the  circulatory  functions 
and  others  that  are  connected  with  efficient 
action. 

The  autonomic  nervous  system  is  essen- 
tially a  nerve  net  of  interconnections. 
Anatomically,  it  is  divided  into  the  sympa- 
thetic and  parasympathetic  divisions.  The 
parasympathetic  division  is  composed  of 
the  cranial  and  sacral  sections.  Figure  17 
is  a  schematic  diagram  of  the  interrelations 
of  these  divisions  and  their  relationship  to 
the  various  bodily  organs. 

Generally  speaking,  the  activity  of  the 
sympathetic  division  is  antagonistic  to  that 
of  the  parasympathetic;  for  example,  the 
heart  rate  is  inhibited  by  nervous  excita- 
tion reaching  it  over  the  parasympathetic. 


while  it  is  actelerated  by  excitation  from 
the  sympathetic.  On  the  whole,  the  action 
of  the  autonomic  nervous  system,  which 
serves  involuntary  muscles  and  glands,  is 
diffuse  and  relatively  slow  in  effect  com- 
pared with  that  of  the  central  nervous  sys- 


FiGURE     17.       AUTONOMIC    NERVOUS    SYSTEM- 
SCHEMATIC    DIAGR.-\M 

[Reprinted  from  Bodily  Changes  in  Pain.  Hun- 
ger, Fear  and  Rage  by  ^Valter  B.  Cannon,  bv  per- 
mission of  W.  ^V.  Norton  &  Company,  Inc.  Copv- 
right  1915,  1920  bv  D.  Appleton-Centurv  Co..  copy- 
right 1929  b)   \Valter  B.  Cannon.] 

tem.    (See  the  further  discussion  of  the  uses 
of  this  system  in  emotion,  pp.  94  i.) 

FUNCTIONS    OF    THE    BRAIN 

There  are  certain  general  problems  of 
the  central  nervous  system  in  ^vhich  the 
student  of  mental  phenomena  is  keenlv  in- 
terested. 

One  of  these,  abotit  v.'hich  there  has  been 
much  speculation,  is  the  relationship  be- 
tween brain  ^veight  and  intellectual  abilitv. 
\Vhen  a  formula  is  used  Avhicli  makes  pos- 


36 


The  Response  Mechanism 


sible  the  comparison  between  the  ratios  of 
brain  weight  to  body  weight,  it  is  found 
that  there  is  some  positive  relationship  be- 
tween the  relative  brain  weight  and  adapt- 
ability, as  far  as  the  various  species  of  ani- 
mals in  the  evolutionary  series  are  con- 
cerned. Animals  with  brains  that  are  large 
in  proportion  to  the  size  of  their  bodies 
tend  to  be  more  adaptable,  more  clever. 
It  has  not  been  demonstrated,  however, 
that  this  relationship  also  holds  true  statis- 
tically in  comparing  human  beings  of  dif- 
ferent intellectual  abilities. 

Localization  in  the  Brain 

Another  problem  of  interest  in  the  fimc- 
tioning  of  the  central  nervous  system  is  the 


r   Frontal 
association 
area 

■^y^^                Body 
/  ^             association 

v" 

Speec 
area 

^ Auditory 

/^             association 

iX 

if    \ 

^/ 

Auditory 
area 

^   1  Visual 
^  /    area  i 

f/  7 

V 

s^                jC^^\     Cerebellum   / 

FIGURE    l8.       HUMAN    CEREBRAL    CORTEX    SHOWING 
LOCALIZATION    OF    MENTAL    FUNCTIONS 

Diagram  oE  side-view  of  cortex.  [From  C.  T.  Mor- 
gan, Physiological  psychology,  McGraw-Hill,  1943, 
p.  16.]    ■ 

localization  of  various  psychological  func- 
tions in  the  brain.  This  problem  has  been 
extensively  investigated  in  recent  years  by  a 
variety  of  techniques:  by  observing  the  ef- 
fects of  accidental  destruction  of  brain  tis- 
sue in  human  individuals,  by  experimental 
removal  of  parts  of  the  brain  in  animals 
preceded  and  followed  by  tests  of  behavior 


of  various  sorts,  by  directly  stimulating 
with  electrical  stimuli  centers  of  the  brain 
in  animals  and  in  human  beings  to  get  ob- 
servations or  verbal  reports  of  the  effects 
and  by  using  various  methods  of  the  elec- 
trical recording  of  activity  in  the  nervous 
system. 

We  know  now  that  there  is  a  consider- 
able amount  of  localization  of  psycholog- 
ical functions  in  the  brain;  on  the  other 
hand,  there  is  also  a  considerable  independ- 
ence of  the  various  parts  of  the  brain,  such 
that  many  mental  functions  depend  on  sev- 
eral different  areas  of  the  brain  or  even,  in 
some  cases,  it  would  seem,  on  the  brain  as 
a  whole. 

The  simplest  aspects  of  perceiving  and 
acting  are  well  localized.  In  rats  and  other 
aniinals  below  man  these  functions  are  lo- 
calized in  part  at  subcortical  levels;  but  in 
man,  though  the  subcortical  centers  still 
exist,  they  are  concerned  mainly  with  sim- 
ple reflex  reactions  to  stimuli,  and  the  pri- 
mary centers  for  perceiving  and  acting  are 
cortical. 

In  the  occipital  region  at  the  extreme 
back  of  the  head  is  the  area  for  seeing.  De- 
struction of  this  area  causes  almost  com- 
plete blindness  in  man,  leaving  him  with 
only  the  crudest  appreciation  of  light  and 
dark  but  depriving  him  of  ability  to  see  ob- 
jects and  to  perceive  color.  In  the  tem- 
poral lobes  at  the  side  of  the  head  are  the 
primary  cortical  areas  for  hearing.  We 
know  less  about  them  than  the  visual  areas, 
but  their  loss,  by  destruction  or  operation, 
causes  'cortical  deafness'  which  is  consider- 
able, if  not  complete.  Along  and  behind 
the  central  fissure  in  the  cerebrum,  a  fissure 
which  lies  under  the  skull  on  a  line  run- 
ning roughly  from  the  center  and  top  of 
the  head  toward  the  ear,  is  the  area  repre- 
senting the  sensations  of  the  body— pres- 
sure, pain  and  temperature  as  well  as  pro- 


Localization  in  the  Brain 


37 


prioceptive  sensations  Ironi  liic  imisclcs.  It 
is  interesting  to  note  that  when  this  area  is 
exposed  under  local  anesthesia  and  stimu- 
lated by  electricity,  it  is  possible  to  obtain 
reports  from  the  patient  of  the  occurrence 
of  the  proper  sensory  experiences. 

Just  in  front  of,  but  also  running  along, 
the  central  fissure  is  the  motor  area  of  the 
brain.  It  is  not  so  well  defined  in  lower 
animals,  but  in  monkeys  and  in  man  it  is 
the  area  through  which  'voluntary'  acts  of 
behavior  are  controlled.  By  direct  electri- 
cal stimulation  of  different  parts  of  the  mo- 
tor area  one  may  produce  movement  of  the 
fingers,  the  legs  or  the  moiuh,  depending 
upon  just  which  spot  is  stimulated.  By  ex- 
citing the  right  spot  it  is  possible  to  get 
'forced'  vocalization,  voiced  sounds  from 
the  larynx.  Extirpation  or  destruction  of 
this  area  causes  paralysis  of  muscles  in  vol- 
untary acts.  This  is  what  we  see  in  a  per- 
son who  has  suffered  a  'stroke'  or  apoplectic 
attack. 

Both  the  motor  area  and  the  bodily  sen- 
sation area  lying  near  it  are  laid  out  like  a 
map  of  the  body,  with  those  spots  near  the 
top  of  the  head  representing  the  feet  and 
legs,  those  along  the  sides  the  hands  and 
arms,  and  those  farther  to  the  sides  the  face 
and  movith. 

Although  simple  perceiving  and  acting 
depend  on  specific  areas,  more  complex  per- 
ception, learning  and  memory  are  not  so 
well  localized.  There  is,  however,  good 
reason  to  believe  that  there  are  sensory  as- 
sociation areas,  situated  immediately  ad- 
jacent to  the  primary  areas  for  sensation 
and  concerned  in  the  more  complex  per- 
ceptions of  the  respective  senses.  Thus  the 
visual  association  area  seems  to  be  neces- 
sary for  coordinated  responses  to  seen  ob- 
jects and  may  well  play  a  role  in  visual  re- 
membering. The  auditory  association  area 
is  needed  in  auditory  space  perception,  the 


otientiiig  of  ilic  body  in  iclaiion  to  the  di- 
rection of  the  source  of  sound.  It  is 
thought  also  to  be  essential  to  auditory  re- 
call. These  functions,  however,  are  not 
fully  established,  and  much  more  research 
is  needed  before  this  chapter  of  brain  psy- 
chology can  be  written. 

For  the  majority  of  complex  memories 
and  intellectual  activities  in  man  there  is 
only  a  rough  localization  of  functions.  It 
is  possible  to  distinguish  between  receptive 
memory  functions,  involving  the  recogni- 
tion and  naming  of  objects  and  the  mean- 
ing of  experiences,  and  expressive  func- 
tions, consisting  of  memories  for  skills  and 
ways  of  doing  things.  In  general,  recep- 
tive types  of  memories,  as  in  simple  percep- 
tion, reside  in  the  back  portion  of  the  cere- 
bral cortex,  particularly  in  the  areas  not 
directly  concerned  with  sensation,  whereas 
expressive  types  of  memory  are  dependent 
on  the  frontal  areas  of  the  cortex  lying 
ahead  of  the  motor  area. 

Worthy  of  particular  mention  is  recent 
research  concerning  the  function  of  the  ex- 
treme frontal  association  areas.  Although 
the  whole  cerebral  cortex  seems  to  be  con- 
cerned in  reasoning  and  thinking,  a  man's 
ability  to  order  his  behavior  and  direct  it 
toward  a  goal  depends  especially  on  tiiese 
areas.  In  certain  standard  tests  with  mon- 
keys, for  example,  in  which  it  is  necessary 
to  use  tools  or  rakes  in  a  certain  order— first 
a  short  rake  is  used  to  obtain  a  longer  rake, 
and  then  that  rake  in  turn  is  used  to  obtain 
a  longer  rake,  in  order  eventually  to  obtain 
food— in  these  tests  monkeys  deprived  of 
their  frontal  association  areas  are  unable 
to  solve  the  problem.  In  man,  similarly, 
destruction  of  the  frontal  areas  interferes 
with  ability  to  svnthesize  acts  into  a  com- 
plete pattern  and,  in  particular-,  to  plan 
and  administer  daily  activities. 

This  function  of  the  frontal  areas  of  the 


38 


The  Response  Mechanism 


cortex  has  been  recognized  in  the  surgical 
treatment  of  mental  disorders.  Certain 
types  of  patients,  who  suffer  from  such  an 
excess  of  anxiety  and  planning  of  their 
lives  that  they  are  depressed  or  are  ob- 
sessed with  complex,  compulsive  rituals  of 
behavior,  have  been  treated  by  partial  re- 
moval of  the  frontal  areas  (prefrontal  lo- 
bectomy) or  by  interrupting  the  fibers 
which  go  to  and  from  these  areas  (pre- 
frontal lobotomy).  This  treatment  has  had 
some  success  in  relieving  patients.  Along 
with  the  good  results  there  has  been  some 
loss  in  their  ability  to  plan  their  behavior; 
yet,  all  in  all,  the  results  have  been  good. 

REFERENCES 

1.  Adrian,  E.  D.  The  mechanism  of  nervous  ac- 
tion: electrical  studies  of  the  neuron.  Phila- 
delphia: University  of  Pennsylvania  Press,  1932. 

A  short  seiies  of  lectures  outlining  the  meth- 
ods of  electro-physiology  and  the  nature  of  ac- 
tion potentials  in  various  types  of  nerves. 

2.  Boring,  E.  G.  Sensation  and  perception  iri  the 
history  of  experimental  psychology.  New  York: 
D.  Appleton-Century,  1942.     Chap.  2. 

Chapter  2  gives  a  brief  history  of  experiments 
in  nerve  conduction. 

3.  Cannon,  W.  B.,  and  Rosenblueth,  A.  Auto- 
nomic neuro-effector  systems.  New  York:  Mac- 
millan,   1937. 

A  monograph  summarizing  a  great  deal  of 
research  on  the  functions  of  the  autonomic 
nervous  system  and  particularly  on  the  role  of 
chemical   messengers   in   synaptic  conduction. 

4.  Creed,  R.  S.,  Denny-Brown,  D.,  Eccles,  J.  C, 
Liddell,  E.  G.  T.,  and  Sherrington,  C.  S. 
Reflex  activity  of  the  spinal  cord.  Oxford: 
Clarendon  Press,   1932. 

A  summary  of  experiments  on  reflex  action 
and  synaptic  functions  in   the  nervous  system. 

5.  Erlanger,  J.,  and  Gasser,  H.  S.  Electrical  signs 
of  nervous  activity.  Philadelphia:  University  of 
Pennsylvania   Press,   1937. 

A  monograph  covering  experiments  on  ac- 
tion-potentials. It  illustrates  especially  well  the 


methods  by  which  one  can  determine  the  func- 
tions of  different  groups  of  fibers  in  different 
nerves. 

6.  Forbes,  A.  The  mechanism  of  reaction.  In  C. 
Murchison  (Ed.),  A  handbook  of  general  ex- 
perimental psychology.  Worcester,  Mass.:  Clark 
University  Press,  1934.     Chap.  3. 

A  comprehensive  review  of  the  functions  of 
the  nervous  system  forming  the  background  of 
behavior.     It  is  now  a  little  out  of  date. 

7.  Freeman,  W.  J.,  and  Watts,  J.  W.  Psycho- 
surgery.    Springfield,  111.:   C.  C.  Thomas,   1942. 

An  account  of  use  of  brain  operations  in  hu- 
man patients  performed  to  alleviate  or  cure 
certain  types  of  mental  disorder. 

8.  Fulton,  J.  F.  Selected  readings  in  the  history 
of  physiology.  Springfield,  111.:  C.  C.  Thomas. 
1930.     Chaps.  6  and  7. 

Excerpts  from  the  classical  writings  on  the 
action  of  the  nervous  system  and  of  muscles  by 
thirty-two  physiologists  from  the  second  century 
down  to  1926.  A  third  of  the  excerpts  belong 
to  the  twentieth  century. 

9.  Fulton,  J.  F.     Physiology  of  the  nervous -system. 

(Rev.  ed.)  New  York:  Oxford  University 
Press,   1943. 

A  comprehensive,  up-to-date  textbook  on  the 
functions  of  the  nervous  system. 

10.  Gardner,  E.  Fundamentals  of  neurology. 
Philadelphia:   Saunders,   1947. 

Contains  excellent  illustrations  of  the  nervous 
system. 

11.  Herrick,  C.  J.  Brains  of  rats  and  men.  Chi- 
cago:   University  of  Chicago  Press,   1926. 

An  elementary  description  of  brain  anatomy 
and  functions. 

12.  Hill,  A.  V.  Muscular  actixnty.  Baltimore:  Wil- 
liams and   Wilkins,   1926. 

A  summary  of  classical  researches  on  muscle 
contraction,  the  nervous  excitation  of  muscles 
and  muscular  work. 

13.  Lillie,  R.  S.  Protoplasmic  action  and  nervous 
action.  (2nd  ed.)  Chicago:  University  of  Chi- 
cago Press,  1932. 

A  discussion  and  summary  of  biochemical 
problems  of  propagation  and  integration  of 
nervous  impulses. 


References 


39 


14.  Marquis,  D.  G.  The  neurology  of  IcarniiiK.  In 
F.  A.  Moss  (F,(l.),  Coniparalive  psychology. 
New   York:    Prentice-Hall,    1912.     Chap.   7. 

An  excellent  summary,-  not  too  technical,  of 
what  is  known  of  brain  functions  in  learning 
and  memory. 

15.  Papez,  J.  W.  Comparative  neiirnln^y.  New 
York:  Thomas  Y.  Crowell,  1929. 

An  olf!  hut  iiscfnl  introduclioii  lo  neurology 
in   animals  and   man. 


10.  I'arkfi,  (i.  II.     '/'he  clcmenlary  nervou.%  system. 
Philadelphia:   J.  B.  Lippintott,  1919. 

A  classical  description  of  the  evojuiion  ol 
the  nervous  system  in  simple  invcnchraic  ani- 
mals. 

17.  Weisenburg,    'I.,    aiirl    McIJride,    K.      Aphasia. 
New   York:   The  C>)inmonwealth  Fund,   I9.?.5. 

An  advanced  but  readable  treatment  of  the 
localizal  ion  of  psychologiral  rnnctions,  jiarticn 
larl)    langinigc   liint.lioiis,   in    llic   human   f^rain 


CHAPTER 


Response 


MAN  is  seldom,  if  ever,  quiet  in  his  wak- 
ing moments,  nor  is  he  very  tranquil 
in  sleep.  In  response  to  stimulation  he  is 
constantly  making  movements,  though 
often  they  are  hardly  noticeable.  There  are 
the  incipient  niovements  of  his  vocal  organs 
and  other  muscles  while  he  is  thinking,  the 
ever-recurring  eyewink,  the  shifting  of  his 
limbs,  the  restless  movement  of  his  body, 
the  frequent  turning  of  his  head,  as  well  as 
the  more  coordinated  activities  like  walk- 
ing, talking,  piano  playing  and  tennis.  All 
such  behavior  is  directed  primarily  toward 
a  manipulation  and  understanding  of 
things  of  the  external  world.  It  is  this  be- 
havior with  which  the  psychologist  is  chiefly 
concerned.  Such  movements  are  depend- 
ent, for  the  most  part,  on  the  striped  mus- 
cles. There  are,  in  addition,  the  actions  of 
the  smooth  muscles,  like  those  connected 
with  the  functions  of  nutrition  and  of  re- 
production, but  these  movements  are 
mainly  of  interest  to  the  physiologist. 

The  importance  of  the  behavior  which 
the  psychologist  studies  need  hardly  be  em- 
phasized. If  we  may  judge  from  the  lower 
forms  of  life,  such  as  the  sponge  whose 
muscles  are  stimulated  by  direct  contact 
only,  behavior  was  present  in  the  evolution 
of  life  even  before  the  development  of  a 
nervous  system.     It  is  the  means  by  which 


the  organism,  in  order  to  survive,  becomes 
adapted  to  the  ever-changing  external  situa- 
tion. We  have  seen  in  the  previous  chapter 
what  are  the  physiological  mechanisms 
which  affect  the  behavior  of  the  organism. 
Our  present  task  is  to  survey  the  kinds  and 
characteristics  of  the  various  responses 
which  make  up  this  behavior. 

VARIETI  ES    OF    BEHAVIOR 

There  are  many  ways  to  classify  human 
and  animal  behavior.  We  may  inquire 
whether  an  act  has  been  learned  through 
experience  or  whether  it  is  an  innate  char- 
acteristic of  the  organism,  whether  it  is 
evoked  by  external  stimuli  or  whether  it 
arises  from  a  need  within  the  organism, 
whether  it  is  automatic  or  conscious  and 
voluntary,  and  whether  it  is  a  movement  of 
the  body  as  a  whole  or  of  a  part  or  limb 
in  particular.  All  these  distinctions  have 
their  place  in  helping  us  to  understand 
man's  behavior,  and  we  shall  employ  them 
in  a  description  of  the  varieties  of  behavior. 

Locomotion  and  Manipulation 

Since  the  maintenance  of  life  is  depend- 
ent upon  the  physical  environment— the 
supply  of  food,  water,  oxygen  and  sunshine, 
and  protection  from  extremes  of  tempera- 


This  chapter  was  prepared  by  Clifford 


T.   Morgan  of  The  Johns  Hopkins  University. 
40 


Tropisms  and  Ref}exes 


41 


Lure— living  things  cillicr  iiiiist  use  vvIkii  is 
available  as  plants  do,  or  ilicy  iriiist  try  to 
change  their  environment  as  animals  do. 
Most  behavior  may  be  tlassihetl  in  terms  of 
whether  the  individual  changes  its  environ- 
ment by  moving  about,  or  by  manipulating 
or  altering  it  to  suit  his  needs.  For  ex- 
ample, in  the  auttunn  many  ol:  the  birds  mi- 
grate from  north  to  south  to  obtain  a 
warmer  climate  and  a  more  abundant  food 
supply.  Man,  on  the  other  hand,  can  build 
and  heat  a  shelter,  and  can  grow,  preserve 
and  store  food  for  the  winter  months.  The 
former  action  we  call  locomotor  behavior, 
the  latter  manipulatory  behavior. 

Locomotor  behavior  is  the  more  primi- 
tive. It  is  interesting  to  note  that  in  lower 
invertebrate  forms,  such  as  the  worm,  and 
also  in  the  lower  vertebrates,  such  as  fishes, 
organisms  must  adjust  to  their  environment 
merely  by  swallowing  some  of  it  or  by  mov- 
ing to  and  fro  within  it.  The  higher  in- 
vertebrate and  vertebrate  forms,  however— 
insects,  most  of  the  mammals,  monkeys  and 
man— have  evolved  appendages  with  which 
they  can  manipulate  objects  in  their  en- 
vironment, and  in  this  way  they  adjust 
themselves  to  it  or  adjust  it  to  themselves. 
Thus  the  worm  or  the  fish  can  avoid  light 
only  by  moving  away  from  it,  but  man  can 
turn  the  light  out.  The  fish  procures  its 
food  by  swimming  to  it  and  grabbing  it  in 
its  mouth,  but  the  monkey  can  use  its  hands 
to  pick  bananas  from  the  tree,  and  man 
can  eat  by  manipvdating  a  fork  and  a  spoon. 
A  worm  gets  a  home  by  burrowing  in  the 
ground,  but  man,  by  handling  a  hannner 
and  saw,  builds  himself  a  house. 

As  we  look  at  evolutionary  history,  we  see 
that  the  development  of  appendages,  an 
important  aid  to  locomotion,  accompanied 
change  of  the  animal's  habitat  from  the 
water  to  the  land.  An  earlier  step  was 
taken,  however,  when  animals  began  to  use 


their  iiK>utiis  ir<  i/iaiiipulate  the  enviion- 
ment.  This  is  the  only  way  in  which  man\ 
animals  can  alter  their  environments.  The 
insects,  for  example,  carry  food  to  their 
nests  by  clasping  it  in  their  rnanfliblcs. 
Birds  construct  nests  with  their  beaks.  Tlic 
dog  retrieves  a  stick  by  carrying  it  in  his 
mouth. 

It  was  late  in  evolution  that  animals  be- 
gan to  use  their  limbs  for  manipulation. 
A  rat  can,  under  appropriate  circumstances, 
learn  to  pull  a  string  with  its  foreleet  in 
order  to  obtain  food.  Monkeys  are  skillful 
with  their  hands,  and  chimpanzees  can 
handle  tools  to  solve  many  problems.  Man, 
however,  represents  a  tremendous  refine- 
ment in  manipulative  ability:  in  the  precise 
movements  of  his  hands  and  fingers  and  in 
the  extremely  delicate  coordination  of  his 
vocal  apparatus  and  of  his  eyes.  It  is  his 
use  of  a  very  small  part  of  himself  to  alter 
his  environment  that  has  made  man  capable 
of  his  mechanical  and  engineering  achie\e- 
ments. 

Tropisms  and  Reflexes 

The  distinction  between  the  use  of  the 
whole  body  or  some  part  of  it  in  an  act  of 
behavior  is  also  useful  in  understanding 
two  other  varieties  of  behavior,  the  tropism 
and  the  reflex.  Both  types  of  behavior, 
unlike  any  others,  are  relatively  stereo- 
typed immediate  reactions  to  stimuli.  The 
tropism,  however,  is  an  orientation  or 
movement  of  the  ^vhole  body  ^vith  respect 
to  a  stimulus,  whereas  the  reflex  is  the 
movement  of  a  specific  part,  such  as  a  leg 
or  an  e\'elid,  in  response  to  a  stimulus. 

AVe  get  the  concept  of  the  tropism  from 
observation  of  the  behavior  of  plants,  such 
as  the  sunflo^ver's  turning  its  face  to^vard 
the  sun  in  die  daytime  and  drooping  it  to- 
ward the  ground  in  the  night.  Orientatior 
toward  the  siui  is  a  lieliotropism,  and  orien- 


42 


Response 


lation  toward  light  in  general  is  a  photo- 
tropism.  Many  of  the  lower  animals,  espe- 
cially the  insects,  also  show  phototropic  be- 
havior. Some,  like  the  night  bugs  which 
seek  the  light  on  a  summer  evening,  are 
positively  j^hototropic;  others,  like  the  cock- 
roach which  scurries  out  of  the  light  into 
the  dark  corner,  are  negatively  phototropic. 
There  are  many  other  kinds  of  tropism. 
The   larval   salamander,   for   example,   dis- 


FIOtlRE    U). 


NKGATI\E    PHOTOTROPIC    BEHAVIOR    IN 
IHE    '.SOWBUCi' 


(A)  Wlieii  light  from  abo%e  illuminales  dittusely 
the  suiiate.  llie  bug  wanders  around  randomly  until 
it  accidenially  finds  the  dark  corner  (D).  (B)  When 
light  is  directed  from  one  side,  the  bug  mo\es  di- 
rectly away  from  it  to  the  dark  corner.  [From 
N.  R.  I".  Maier  and  T.  C.  Schneirla,  Principles  of 
animal  psVcholog)',  McGraw-Hill,  1935,  p.  131.] 

plays  a  galvanolropism  to  electrical  stimu- 
lation. It  lowers  its  head  and  tail,  arching 
the  body  concavely,  when  the  positive  elec- 
trode is  near  the  head  and  the  negative  one 
near  the  tail;  it  raises  its  head  and  tail, 
arching  its  body  convexly,  when  the  di- 
rection of  electrical  stimulation  is  reversed. 
Many  animals  which  live  in  the  water  show 
a  rheolropism,  an  orientation  and  a  swim- 
ming movement  opposite  to  the  current. 
^Ve  may  see  such  a  rheotropism  in  fish 
swimming  upstream  or  attempting  to  jump 
a  falls.  There  is  also  geolropism,  a  re- 
sponse elicited  by  the  force  of  gravity  (the 
(at  lands  on  its  feet),  and  stereolropism, 
elicited  by  the  stirfaces  with  which  the  body 
makes  contact  (the  mouse  hugs  the  wall  as 


it  runs).  These  are  but  a  few  of  the  tropis- 
tic  responses.  All  of  them  have  the  charac- 
teristics that  (1)  they  are  not  learned,  (2) 
they  are  controlled  by  external  stiinuli 
rather  than  by  volition,  (3)  they  are  orient- 
ing responses  involving  approach  to  stimu- 
lation or  withdrawal  from  it,  and  (4)  they 
invohe  the  entire  organism  rather  than 
some  part  of  it. 

We  see  little  that  can  be  called  tropistic 
behavior  in  man  and  the  higher  animals. 
Just  as  specific  manipulative  responses  have 
in  large  part  displaced  locomotion  as  a 
means  of  adjusting  to  the  environment,  so 
reflex  responses  of  parts  of  the  organism 
have,  in  man  and  the  higher  animals,  taken 
the  place  of  the  gross  orienting  movements 
in  the  tropistic  behavior  of  the  lower  ani- 
mals. 

The  reflexes  may  be  defined  as  iinolun- 
tary  and  prompt  responses  of  the  striped 
or  the  smooth  muscles  of  the  body.  In  the 
human  repertoire  of  beha\ior  there  is  a 
great  \'ariety  of  such  reflex  acts.  If  licjuid 
gets  into  the  throat  of  an  infant,  its  mus- 
cles immediately  respond  and  the  liquid  is 
swallowed;  if  there  is  too  much  liquid,  the 
infant  chokes.  It  begins  breathing  at  birth 
as  a  reflex  response  to  lack  of  oxygen  and 
accumulation  of  carbon  dioxide  in  its 
blood.  Its  eyelids  close  automatically  at  a 
lotid  noise  or  wheii  something  moves  rap- 
idly toward  its  eyes.  These  are  a  few  early 
examples  of  man's  many  reflexes. 

It  will  aid  our  understanding  of  the  re- 
flex to  consider  briefly  its  physiological 
mechanism.  The  simplest  form  of  reflex 
would  require  a  receptor,  a  sensory  neuron, 
a  motor  neuron  and  an  effector.  Such  a 
simple  reflex  arc,  however,  is  not  found  iso- 
lated functionally  from  all  other  parts  of 
the  nervous  system  in  a  mature  human  or- 
ganism. Take,  for  example,  the  following 
illustration  of  a  spinal  reflex.     If  we  jjinch 


Conditioned  Response 


43 


ihe  paw  oi  a  clog  whose  spinal  coid  has  been 
cut  just  below  the  brain,  we  can  still  ob- 
tain a  withdrawal  or  flexion  oi  the  one  paw 
accompanied  by  a  forward  thrust  of  the 
other  paw.  A  relatixely  simple  neural  arc 
is  involved  in  the  flexion  of  the  paw,  but 
even  here  more  than  one  motoi  neuron  is 
necessary  lo  bend  the  leg:  and,  besides, 
there  must  be  a  (onnection  in  the  spinal 
(oixl  between  the  sensory  neuron  and  the 
motor  neuron  going  to  the  opposite  leg  to 
produce  the  thrust  of  that  leg.  There  are 
also  connections  between  these  arcs  and 
many  more  remote  reflexes,  which,  if  stim- 
ulated at  the  same  time,  may  exert  either 
an  inhibitory  or  facilitating  effect  upon  the 
first  reflex.  Furthermore,  when  the  central 
nervous  system  is  intact,  the  legs  may  be 
moved  voluntarily— a  fact  which  means  that 
there  are  connections  between  the  spinal 
reflex  arc  and  the  cerebrum.  This  brief 
sketch  of  the  physiology  of  the  reflex  arc  is 
given  to  emphasize  once  more  the  fact  that 
even  the  simplest  form  of  response  involves 
a  complicated  neural  and  muscular  pattern. 
By  obser^  ing  reflex  acts  in  young  infants, 
or  e\'en  in  human  and  animal  fetuses  before 
birth,  one  can  see  that  the  maturing  of  cer- 
tain parts  of  the  response  mechanism  is  nec- 
essary for  the  appearance  of  reflexes. 
There  may  be,  in  addition,  some  stimula- 
tion necessary  for  their  appearance  (see 
below),  but  in  the  broad  sense  of  the  term 
reflexes  are  unlearned  acts.  Once  firmly 
established,  they  remain  stable  and  predict- 
able, many  of  them  being  common  to  all 
organisms  of  the  same  species. 

Conditioned  Response 

Pavlov,  a  famous  Russian  physiologist, 
was  the  first  to  demonstrate  experimentally 
that  there  are  learned  reflexes,  and  that 
they  appear  through  the  conditioning  of 
unlearned    reflexes.      Pavlov    stimulated    a 


dog  with  the  sound  of  a  bell  lor  a  brief 
period,  then  gave  it  food  and  measured  the 
resulting  flow  of  .saliva.  After  a  consider- 
able number  of  such  pairings  of  fjeil  with 


Light 

«UncR 

A 

A 

Eyelid 

A'- 

Air  puff^^    j      \^ 

t                                  1 

yu--                                   1 

Light 

/NUncR 

C 

CR^\ 

Eyelid 

_^Rl. 

^       \ 

Air  pun                             1 

FIGURE     20.       RECORDS    OF    CONDITIONING    OF    THE 
RIGHT    EYELID    TO    LIGHT 

(A)  Reaction  of  the  eyelid  (Unc  R)  lo  a  putt  of 
air  before  conditioning.  (B.  C)  The  beginnings  of 
conditioning  (CR),  in  which  the  closure  of  tlie  eve- 
lid  anticipates  somewhat  the  puff  of  air.  (D)  Full 
conditioned  response  to  light.  Rj^  is  the  light  re- 
flex. [From  E.  R.  Hilgard  and  D.  G.  .Ntarquis. 
Conditioning  and  learning,  Appleton-Century,  1940, 
p.  38.] 

food,  the  sound  of  the  bell  alone  ^vould 
call  forth  the  saliva  in  somewhat  the  same 
manner  as  had  the  food,  diat  is  to  say.  the 
bell  had  taken  the  place  of  the  food  as  a 
stimulus  to  saliAation.  Pavlov  called  diis 
fact  a  conditioned  reflex. 


44 


Response 


Later  work,  however,  has  shown  that 
many  responses  other  than  simple  reflexes 
can  be  conditioned.  For  instance,  a  man 
places  his  hand  on  a  grid  of  electric  wires, 
a  bell  is  rung,  and  then,  a  second  later,  the 
man  recei\es  a  shock  in  his  hand.  Quickly 
he  withdraws  his  hand.  After  this  sequence 
of  events  has  happened  often  enough,  the 
man  begins  to  withdraw  his  hand  at  the 
sound  of  the  bell,  thus  escaping  the  shock. 
Since  the  conditioned  withdrawal  was  a 
learned  response  and  not  a  simple  reflex,  it 
seems  better  in  general  for  us  not  to  speak 
at  all  of  a  conditioned  reflex,  but  to  call  it  a 
conditioried  response.  (For  a  further  de- 
scription of  conditioned  responses,  see  pp. 
139-144.) 

The  Reflex  Circle 

There  are  several  situations  in  human 
behavior,  particularly  at  the  early  stages  of 
infancy  and  childhood,  when  a  reflex  pat- 
tern of  behavior  may  be  strengthened  or 
perpetuated  through  conditioning.  Con- 
sider, for  example,  the  grasping  reflex.  If 
a  stick  is  placed  on  the  palm  of  an  infant's 
hand,  its  fingers  will  curl  about  the  stick 
and  hold  on  with  considerable  strength. 
Indeed,  shortly  after  birth  an  infant  can  be 
raised  from  the  ground  by  its  hold  on  the 
stick.  Although  this  reflex  is  present  at 
birth,  it  is  probable  that  the  grasping  re- 
sponse is  not  due  entirely  to  inherited  fac- 
tors, but  involves  the  formation  of  a  reflex 
circle  through  conditioning.  It  is  easy  to 
see  that,  in  this  case  of  grasping,  when  a 
movement  occurs,  the  resulting  stimulation 
of  the  proprioceptors— the  receptors  in  mus- 
cles, tendons  and  joints— produces  a  sensory 
impulse  which  goes  into  the  central  nerv- 
ous system  and  that  this  impulse  may  then 
become  connected  by  conditioning  to  the 
motor  response  of  the  original  movement, 
so    that   it   acts    to   continue    the   original 


movement.  The  gi-asping  is  strengthened 
because  it  becomes  conditioned  upon  itself 
by  way  of  proprioception.  This  type  of 
reflex  circle  which  involves  proprioceptors 
is  called  a  circular  response. 

It  is  through  the  mechanism  of  a  reflex 
circle  that  various  other  responses  are  sus- 
tained and  perpetuated,  often  by  means  of 
exteroceptors.  For  example,  if  an  infant 
utters  the  sound  ah,  this  sound  stimulus  af- 
fects its  ear,  and  impulses  travel  along  the 
auditory  nerve  to  the  brain.  Since  the 
muscles  of  the  vocal  organs  are  the  ones 
that  have  just  moved,  this  motor  path  tends 
to  be  reactivated  by  the  impulses  from  the 
auditory  nerve,  and  the  infant  says  ah 
again.  It  is  clear  that  until  there  is  a  break 
in  this  circle,  the  infant  would  continue  to 
say  ah,  but  the  reiteration  always  gets  termi- 
nated presently  by  some  other  stronger 
stimulation  from  outside  the  circle. 

Even  in  older  children  this  circular  phe- 
nomenon is  frequently  observed.  They  de- 
light in  repeating  sounds— to  the  annoyance 
of  their  parents,  who  may  think  the  chil- 
dren do  it  purposely  to  irritate  them.  One 
boy  of  eight  would  bleat  like  a  sheep  and 
keep  on  until,  only  with  difficulty,  he  was 
made  to  stop.  There  was  a  mental  de- 
fective who  sat  in  a  corner,  day  in  and  day 
out,  hitting  his  two  index  fingers  together 
and  murmuring  "Beelzebub."  The  normal 
adult  also  has  many  such  continuous  cir- 
cular responses— like  chewing  gum,  twisting 
a  lock  of  hair,  turning  a  coat  button  while 
thinking. 

Conditioned  Voluntary  Responses 

Other  complex  aspects  ol  liimian  behav- 
ior may  be  understood,  at  least  in  part,  in 
terms  of  the  method  and  phenomenon  of 
conditioning.  It  is  even  possible  to  obtain 
voluntary  control  of  what  is  for  most  per- 
sons an  involuntary  reflex. 


Condition  and  Moiivafed  Behavior 


45 


In  one  experiment  of  tliis  nature,  liic 
pupil  of  a  man's  eye  was  trained  to  contract 
at  command.  In  the  first  stage  of  training, 
a  bell  was  rung  immediately  before  a  light 
was  shone  in  his  eyes.  After  some  trials, 
ihe  sound  of  the  bell  alone  would  cause  his 
pupil  to  contract.  Then  the  man  was  in- 
structed to  close  and  open  the  circuit  for 
both  bell  and  light  by  closing  and  opening 
his  hand  at  the  verbal  command  of  the  ex- 
perimenter. In  this  way  verbal  commantl 
became  connected  through  the  iiand  move- 
ment and  the  sound  of  the  bell  to  the 
pupilary  reflex.  The  next  step  in  the  ex- 
periment was  to  eliminate  both  the  hand 
movement  and  the  bell.  This  left  only  the 
vocal  instruction  of  the  experimenter  as  the 
conditioned  stimidus,  and  the  man's  pupil 
now  contracted  to  it  alone.  The  last  stage 
of  the  experiment  consisted  in  having  the 
subject  himself  repeat  the  verbal  instruc- 
tions, first  aloud,  then  in  a  whisper  and 
finally  subvocally.  Each  of  these  forms  of 
stimulation,  it  was  found,  could  become  the 
condition  for  the  contraction  of  the  pupil. 
So  the  man  could,  at  the  end  of  the  experi- 
ment, effectively  command  his  own  pu- 
pilary reflex,  and  this  ability  was  still  pres- 
ent fifteen  days  later,  without  practice  in 
the  meantime. 

MOTIVATED    BEHAVIOR 

Thus  far  we  have  been  dealing  with  the 
kinds  of  behavior  which  are  directly  and 
immediately  controlled  by  stimulation. 
Tropisms  are  orientations  of  the  whole  or- 
ganism with  respect  to  external  stimuli. 
Reflexes  are  responses  of  specific  parts  of 
the  organism  to  stimuli.  Conditioned  re- 
sponses are  reflexes,  which,  through  learn- 
ing, have  come  under  the  control  of  new 
stimidi.  In  addition  to  these  stimidus-con- 
trolled  responses,  however,  there  are  many 


varieties  ol  behavior  which  arise  from  needs 
located  within  the  organism.  .Such  behav- 
ior, although  it  may  use  various  stimuli  as 
cues  or  signals,  depends  in  its  character  and 
manifestation  primarily  on  the  motive  of 
the  organism.  Now  we  shall  consider  such 
behavior. 

Instinct 

It  is  common  among  laymen  to  call  reflex 
action  instinctive,  because  both  reflexive 
and  instinctive  behavior  are,  in  the  first 
instance,  unlearned  responses  which  de- 
jaend  upon  innate  connections  in  the  nerv- 
ous system.  In  the  vocabulary  of  the  psy- 
chologist, however,  the  instinct  differs  from 
the  reflex  because  it  is  in  part  activated  bv 
internal  needs  of  the  organism.  Responses 
are  called  instinctive  when  they  involve  not 
only  innate  reflexes  in  their  response  pat- 
terns, but  also  organic  needs  or  drives  as 
their  immediate  causes.  Complicated  re- 
sponses, however,  often  owe  their  develop- 
ment to  experience  as  well  as  to  innate  con- 
nections, and  it  is  to  the  interest  of  the  psy- 
chologist to  determine  by  observation  and 
experimentation  how  much  may  rightly  be 
classed  as  instinctive  or  innate  and  how 
much  is  acquired. 

An  interesting  form  of  beha\ior,  which  is 
in  part  instinctive,  is  the  pecking  response 
of  chicks.  Shortly  before  the  chick  is 
hatched,  its  ^vhole  body  moves  violently  in 
the  shell.  The  movements  of  its  head  take 
on  the  form  essential  to  pecking,  and  its 
legs  dirust  upward  against  die  shell.  It  is 
during  one  of  diese  agitated  movements 
that  the  shell  cracks  open  and  the  chick 
emerges.  The  chick's  action  in  breaking 
out  of  the  shell  is  instincti\e  in  die  sense 
that  it  is  caused  by  the  internal  develop- 
ment of  the  organism.  It  is  not  instinctive 
in  the  popular  but  incorrect  sense  that  the 


46 


Response 


idea  of  getting  out  of  the  shell  at  the  right 
time  was  inherited  by  the  chick. 

After  the  chick  is  thus  released,  it  uses  its 
pecking  response  for  eating,  but  it  has  to 
learn  to  peck  effectively.  At  first  the  chick 
often  misses  the  grain  of  corn  that  it  strikes 
at.  It  may  strike  the  com  but  not  seize  it, 
or  it  may  seize  the  giain  but  not  swallow  it. 
Only  after  some  days  does  the  chick  peck 
accurately  and  eat  with  the  proficiency  of 
the  adult  hen.  If  some  of  the  chicks  are 
fed  artificially  for  several  days  and  not  al- 
lowed to  peck  during  that  time,  they  will 
nevertheless  very  soon  learn  to  peck  as  ac- 
curately as  the  chicks  who  had  been  'prac- 
ticing' earlier.  Thus  we  see,  even  in  this 
relatively  simple  response  of  pecking,  that 
both  instinctive  response  and  learning  play 
a  part. 

Many  animals  build  nests  according  to  a 
pattern  which  varies  little  within  the  spe- 
cies. In  some  instances,  the  offspring  have 
had  no  opportunity  to  learn  from  their  pro- 
genitors. There  must,  therefore,  be  at  least 
some  innate  tendency  controlling  the  activ- 
ity. That  such  behavior,  however,  cannot 
possibly  be  an  instinct  in  the  sense  in  which 
an  instinct  is  sometimes  defined  (that  is  to 
say,  a  series  of  chain  reflexes  whose  con- 
nections are  innate  and  fixed)  is  evident 
from  the  fact  that  the  animal  must  change 
the  nature  and  sequence  of  its  responses  in 
order  to  fit  its  behavior  to  the  particular 
siuToundings  in  which  it  finds  itself  and  to 
the  kind  of  material  immediately  available 
for  the  purpose. 

In  other  cases,  so-called  instincts,  both  in 
animals  and  in  man,  are  learned  behavior. 
Naturalists  frequently  have  reported,  for 
example,  that  some  wild  animals  they  have 
encountered  were  not  'instinctively'  either 
afraid  of  man  or  inclined  to  attack  him 
imtil  they  had  had  unpleasant  experiences 
with   him.      Hunters    in    Africa    have    fre- 


quently been  able  to  approach  by  automo- 
bile within  a  few  yards  of  a  lion  without 
the  lion's  paying  particular  attention  to 
them.  There  are  many  other  confusions  of 
instincts  with  learned  behavior,  and  it  is  a 
wise  and  prudent  principle,  when  explain- 
ing a  particular  response,  to  endeavor  first 
to  determine  all  the  factors  of  experience 
that  could  possibly  have  been  operative  in 
the  development  of  the  behavior  in  ques- 
tion before  concluding  that  it  is  instinctive. 
It  may  safely  be  stated,  however,  that 
there  are  many  aspects  of  behavior  which 
are  primarily  instinctive.  Many  fishes 
carry  out  long  and  comjalex  cycles  of  mi- 
gration and  spawning.  The  salmon,  for 
example,  spawns  in  fresh  water  streams, 
and  the  young  swim  downstream  to  the  sea. 
Later  and  at  the  proper  time  in  their  ma- 
turity, they  swim  back  up  the  rivers  and 
tributaries  from  which  they  came,  there  to 
spawn  again.  Some  species  of  birds  mi- 
grate back  and  forth  between  particular 
areas  in  the  north  in  the  summertime  and 
in  the  south  in  the  wintertime.  (See  Fig. 
195.)  Birds  too  not  only  build  complex 
nests  characteristic  of  their  species  but  also 
display  well-patterned  activity  in  procuring 
food  and  feeding  their  young.  The  ma- 
ternal behavior  of  many  animals  is  largely 
instinctive;  they  deliver  their  young,  clean 
them,  construct  nesting  places,  retrieve  the 
young  when  they  venture  from  the  nest  anil 
suckle  them.  The  complex  sequences  of 
sexual  behavior— courting  and  strutting, 
billing  and  cooing,  the  male's  pursuit  of  the 
female  and  finally  the  complex  responses  in 
copulation— are  all  largely  innate  and  in- 
stinctive. Vestiges  of  these  instinctive  ac- 
tivities may  often  be  seen  in  man's  behax- 
ior,  but  learning,  habit,  intelligence  and 
culture  have  so  overridden  them  that  it  is 
seldom  proper  to  speak  of  instinctive  be- 
havior in  man. 


Needs  and  Problem  Solving 


47 


Needs  and  Activity 

Tropisms,  reflexes  and  inslinctivc  acts  are 
all  relatively  definite,  invariable  and  stereo- 
typed kinds  of  behavior.  li'  we  knov^'  the 
stimulus  conditions  in  the  environment  and, 
in  the  case  of  instinctive  acts,  the  needs  ol 
the  organism,  we  can  predict  with  relative 
accuracy  the  kinds  of  acts  which  will  Occur. 
There  is,  however,  much  behavior  in  man 
and  animals  that  is  not  so  predictable;  it  is 
simply  a  pacing  to  and  fro,  or  running 
through  the  wilds  or  exploring  hither  and 
yon.  Such  behavior  may  appear  to  be  ran- 
dom, because  we  cannot  see  a  stimulus  or 
any  other  immediate  cause  for  it,  nor  can 
we  see  any  definite,  repeated  pattern  in  it. 

We  therefore  often  call  such  behavior 
general  activity  or  general  exploratory  be- 
liaxnor.  This  kind  of  activity  is  important 
to  the  psychologist,  for  it  is  from  general, 
exploratory  and  apparently  aimless  move- 
ment that  patterns  of  learned  behavior,  and 
eventually  of  thinking,  arise.  Upon  close 
observation,  it  is  possible  to  conclude  that 
most  general  exploratory  behavior  is  the 
result  of  primitive  needs  or  tensions  within 
the  organism.  (See  p.  114.)  The  organism 
is  cold  or  hot,  it  is  hungry,  it  is  in  need  of 
water,  or  it  is  suffering  sexual  deprivation. 
Many  experiments  in  which  general  activ- 
ity has  been  measured  in  various  animals 
show  that  large  increases  in  activity  and 
exploration  occur  when  one  or  another  of 
these  needs  is  present. 

Problem-Solving  Behavior 

It  is  no  accident  that  general  exploratory 
behavior  accompanies  the  presence  of  needs 
in  the  organism.  In  the  evolution  of  the 
response  mechanism  and  in  the  adjustment 
of  the  organism  to  its  environment,  general 
activity  becomes  the  first  step  in  insuring 
that   the  organism  has  an  opportunity   to 


obtain  the  satisfaction  of  its  needs.  By  for- 
aging around  the  wild  animal  ha.s  a  good 
chance  to  come  upon  food;  by  exploring  a 
maze  a  rat  finally,  if  .somewhat  randomly, 
finds  the  food  at  the  end  of  it;  and,  sinn- 
larly,  the  thirsty  deer  by  roaming  about 
comes  to  a  stream  and  finds  water.      I  lius 


- 

- 

_ 

, 

— 

' 

1 

Exit 

' Entrance 

FIGURE   21.      MULTIPLE-T    MA^E   FOR   STUDYING 
PROBLEM-SOLVING    BEHAVIOR    IN    RATS 

[After  C.  p.  Stone;  from  F.  A.  Moss  (Ed.).  Com- 
parative psychology  (2nd  ed.).  Prentice-Hall.  1942, 
p.  221.] 

general  activity  has  use.    It  is  instrumental 
in  satisfying  needs. 

Although,  in  a  new  and  unfamiliar  situ- 
ation, general  exploration  is  the  onlv  avail- 
able means  for  finding  the  satisfaction  of  a 
need,  when  the  need  arises  again  and  again 
in  the  same  situation,  learning  has  an  op- 
portunity to  take  place.  Activity  tlien  be- 
comes less  random  and  more  stereotyped, 
and  specific  learned  patterns  of  beha\ior 
emerge.  Thus,  the  first  time  a  hungry  rat 
is  placed  in  a  maze,  it  wanders  randomly 
in  and  out  of  tnany  of  the  blind  alleys,  but 
after  it  has  been  placed  in  the  maze  manv 
times,  each  time  finding  food  at  the  end,  it 


48 


Response 


gradually  eliminates  its  random  behavior 
and,  instead,  runs  rapidly  through  the  maze 
along  the  shortest  true  path.  Such  learn- 
ing behavior  is  called  problem-solving  be- 
liavior. 

Problem-solving  behavior  as  thus  de- 
scribed involves  a  need  which  at  first  gives 
rise  to  general  activity.  It  also  may  involve 
conditioning.  Just  as,  in  conditioning,  the 
bell  comes  to  elicit  the  salivary  response 
originally  evoked  only  by  the  sight  of  food, 
so,  in  establishing  habits  for  problem-solv- 
ing, stimuli  like  odors,  shadows,  cracks  and 
soimds  come  to  serve  as  signals  for  the  cor- 
rect responses  which  were  originally  only  a 
part  of  general  random  activity.  In  this 
way  conditioning  establishes  behavior  pat- 
terns for  solving  problems.  (Figure  21  shows 
a   maze   used   in   problem-solving   studies.) 

Covert  Behavior 

In  animals  and  in  children  we  can  usu- 
ally see  many  random  movements  in  the 
cotu'se  of  their  solving  of  a  problem,  but 
adult  human  individuals  do  not  display  so 
many  random  movements.  In  solving  a 
puzzle,  for  example,  an  adult  is  likely  to 
study  the  parts,  not  making  any  trial  solu- 
tions, but  putting  two  pieces  together  only 
when  he  has  'decided'  that  they  will  fit.  He 
seems  to  think  the  solution  out  rather  than 
to  attain  it  by  trial-and-error.  Many  ex- 
periments indicate,  however,  that  the  prob- 
lem-solving behavior  is  there,  even  though 
it  is  not  seen,  that  it  is  simply  reduced  in 
magnitude  to  very  small  muscular  contrac- 
tions. Even  in  the  problem  solving  of  ani- 
mals, it  may  be  shown  that,  when  random 
responses  seem  to  drop  out,  actually  they 
ai-e  simply  reduced  in  magnitude  to  the 
point  where  the  eye  cannot  see  them. 

Such  covert  behavior,  sometimes  called 
implicit  behavior,  has  been  measured  by 
mechanical   and   electrical   methods   of   re- 


cording activity  in  muscles.  In  some  ex- 
periments, for  example,  an  apparatus  was 
constructed  for  showing  slight  movements 
of  the  tongue.  Subjects  were  then  in- 
structed to  think  of  certain  words,  and, 
while  they  were  thinking,  the  movements 
of  their  tongues  were  recorded.  The  think- 
ing was  found  to  be  accompanied  by  defi- 
nite movements  of  the  tongue.  In  other 
cases,  electrical  voltages  arising  in  various 
muscles  were  recorded  while  subjects  ^vere 
engaged  in  'mental'  problem  sohing,  for 
example,  the  solution  of  arithmetical  prob- 
lems. In  such  subjects,  muscle  contractions 
almost  always  appeared  in  the  course  of 
problem  solving,  even  though  they  coidd 
not  be  seen  by  the  eye,  and  the  electrical 
records  showed  that  these  contractions  were 
similar  in  pattern  to  the  responses  obtained 
Avhen  the  subjects  were  solving  the  prob- 
lem 'out  loud'  or  with  observable  move- 
ments. Thus  it  is  important  to  realize  that 
covert  movements  may  be  going  on,  and,  in 
fact,  that  a  person  may  be  behaving  all  the 
time,  even  when  no  behavior  is  observable 
by  the  casual  observer. 

In  the  following  experiment  covert  be- 
havior is  clearly  demonstrated.  If  a  record- 
ing instrument  is  placed  on  a  person's  head 
so  that  a  graphic  record  of  his  head  move- 
ments can  be  obtained,  it  is  found  that 
when,  with  his  eyes  closed,  he  merely  thinks 
of  his  head's  moving  to  the  right,  the  rec- 
ords show  that  his  head  actually  makes  a 
slight  movement  to  the  right.  AVhen  he 
thinks  of  moving  his  head  to  the  left,  the 
record  indicates  that  such  a  movement  to 
the  left  is  made.  Yet  the  person  himself  is 
unlikely  at  any  time  during  the  experi- 
ment to  realize  that  he  has  made  an  actual 
movement. 

The  feat  of  muscle  reading,  a  form  of 
'mind  reading,'  is  based  on  this  fact  of  cov- 


Set  and  Readiness 


49 


ert  behavior.  II  (lie  iiulividual,  wliosc 
hand  is  held  by  the  perlonner,  (liiiiks  ol 
going  toward  the  window,  his  hand  will 
make  a  slight  movement  "in  that  direction, 
which  the  performer,  who  is  especially  sen- 
sitive to  such  weak  muscular  responses, 
will  immediately  i'ecl  and  use  as  a  clue. 
Animals  are  particularly  acute  in  noticing 
such  involuntary  movement.  A  trained 
dog  may  be  able  to  pick  out  the  correct 
one  of  a  series  of  playing  cards  spread  on 
the  floor  if  persons  who  know  the  correct 
card  are  near  by.  In  thinking  of  the  card, 
these  onlookers  are  likely  to  turn  their 
heads  involuntarily  for  a  fraction  of  a  sec- 
ond toward  the  card  in  question,  a  hint 
which  is  not  lost  on  the  dog. 

Set  and  Readiness 

There  is  another  aspect  to  the  behavior 
of  problem  solving  and  conditioning,  which 
is  known  as  set  or  readiness  to  respond.  An 
odor  at  a  particular  point  in  the  pathway 
of  a  maze  may  be  a  signal  to  a  rat  to  turn 
right,  but  it  may  be  more  than  that.  It 
may  not  only  tell  him  to  turn  right  but  may 
also  prepare  him  for  making  a  second  right 
turn  after  that.  A  pianist  in  learning  to 
play  the  piano  must  learn  not  only  to  play 
one  note  at  a  time  from  the  score  but  also 
to  read  ahead  and  to  be  ready  to  strike 
other  notes  at  the  appropriate  time.  He 
must  let  himself  be  'set'  for  the  particular 
key  in  which  the  piece  is  written  and  must 
not  have  to  be  constantly  reminding  him- 
self about  the  sharps  or  the  flats. 

A  more  detailed  example  of  set  may  be 
taken  from  laboratory  experiments  in 
which  a  subject  is  asked  to  push  a  key  with 
his  right  hand  when  a  red  light  appears 
and  to  jDUsh  another  key  with  his  left  hand 
when  a  green  light  appears.  In  this  situa- 
tion the  subject  of  the  experiment  may  at 


(iisl  icjjcai  I  lie  instriiriions  to  liirfiscll.  He 
may  also  consciously  associate  his  right 
hand  with  the  red  light  and  his  left  hand 
with  the  green  light.  He  will  probably,  in 
addition,  feel  some  tension  in  his  arms.  In 
such  terms  as  these  the  task  or  problem  is 
represented  in  the  subject's  mind  before  a 
reaction  takes  place.  This  attitude  of  the 
subje<:t  is  called  the  set  toward  the  task. 
The  set  will,  however,  become  increasingly 
less  conscious,  so  that  eventually  the 
movement  will  occur  immediately  and  au- 
tomatically upon  the  appearance  of  the 
stimulus  without  any  intervening  mental 
state  at  all.  Such  a  set  may  be  either  posi- 
tive or  negative.  In  the  experiment  with 
the  red  and  green  lights,  the  set  for  the 
right  hand  is  positive  for  the  red  light  and 
negative  or  inhibitory  for  the  green  light. 
The  subject  is  set  not  to  move  his  right 
hand  for  the  green  light.  It  Avoidd  be 
much  harder  to  reverse  the  meanings  for 
red  and  green  now  for  the  t^vo  hands  than 
to  set  up  new  sets  for  yellow  and  blue. 

An  experiment  can  be  arranged  to  in\cs- 
tigate  a  motor  set  by  jjlacing  a  rubber  ball 
on  the  reaction  key  in  order  to  measure  the 
amount  of  pressure  of  the  finger.  By  such 
means  it  has  been  found  that  the  finger  fre- 
quently makes  an  actual  anticipatory  move- 
ment of  downward  pressure  on  the  key  be- 
fore the  real  movement  is  carried  out.  An- 
other good  example  of  motor  set  is  that  of 
the  football  player  who  has  in  mind  ju^t 
what  to  do  in  answer  to  the  play  of  his 
opponent.  As  soon  as  he  sees  the  i^lay.  his 
intended  response  follo\\s  immediately 
without  further  diought.  Off-side  play  is 
frequently  due  to  an  overintensified  set. 
The  player  is  so  ready  to  act,  that  he  re- 
sponds to  the  A\-rong  stimulus  or  even  to  an 
imaginary  stimidus.  (For  the  relation  of 
set  to  )ieed  and  attitude,  see  p.  126.) 


50 


Response 


VOLUNTARY    AND    AUTOMATIC 
BEHAVIOR 

AVe  arc  now  ready  to  consider  briefl) 
more  complex  forms  of  behavior,  including 
voluntary  behavior.  A  person  decides  to 
go  to  town.  He  walks  down  the  stairs,  puts 
on  his  coat  and  hat,  opens  the  door,  gets 
into  his  car  and  starts  the  engine.  Com- 
mon sense  says  that  he  has  willed  to  do 
lliese  various  acts.  Or  again  someone  is 
trying  to  read  a  difficult  passage  in  a  text- 
ijook.  His  mind  continues  to  wander  from 
the  book  to  irrelevant  matters,  until  finally 
with  great  effort  he  succeeds  in  concen- 
trating on  the  work  at  hand.  It  is  usual 
to  say  that  he  has  had  to  use  his  will  power. 
No  fault  can  be  found  with  such  an  ex- 
pression in  ordinary  speech,  but  the  psy- 
chologist desires  to  know  what  is  the  gen- 
eral process  that  one  calls  'will.' 

The  Will 

In  a  voluntary  act  there  is  no  special 
force  that  can  be  called  the  'will.'  Most 
important  is  the  preliminary  set  or  attitude 
already  described.  In  addition,  what  is  felt 
in  an  experience  of  'will  power'  is  the  mus- 
cular tension  involved— tension  in  the  arms, 
for  instance,  in  acts  where  arm  movement 
is  involved,  or  tension  in  the  muscles  of  the 
forehead  when  the  brow  is  wrinkled  in  an 
effort  to  concentrate  on  a  mental  task.  It 
has  been  argued  that,  since  a  person  para- 
lyzed in  one  leg  experiences  an  effort  of  will 
when  he  tries  to  move  the  inert  limb  and 
yet  does  not  move  it,  the  will  experienced 
obviously  cannot  come  from  these  muscles. 
What  actually  happens  is  that,  unknow- 
ingly, he  moves  some  other  member.  It  is 
these  other  muscular  sensations,  imagined 
bv  their  owner  as  coming  from  the  missing 
ineinbcr,  that  give  him  the  impression  of 
will  power. 


The  will,  then,  so  far  as  experience  is 
concerned,  turns  out  to  be  tlie  preliminary 
set  ph/s  the  experience  of  movement  plus 
the  knowledge  that  the  movement  follows 
directly  on  the  set  and  has  not  been  caused 
by  any  external  force.  We  know  that  we 
have  made  the  movement.  It  is  unfortu- 
nate that  xi'ill  is  a  noim,  as  if  it  were  an 
agent,  a  faculty  or  a  special  kind  of  energy. 
There  is  'willing'  but  not  a  'will.'  Willing 
is  a  process  which  one  calls  a  vohinlary  act. 

Voluntary  Control  of  Movement 

What  do  we  have  to  do  in  order  to  gain 
voluntary  control  of  a  response?  It  was  at 
one  time  supposed  that,  if  we  could  call  to 
mind  how  the  muscles  would  feel  when 
moved  in  a  certain  way— in  other  words,  if 
we  had  a  clear  memory  of  the  propriocep- 
tive sensations  produced  by  the  movement 
—we  could  then  move  those  muscles  appro- 
priately. It  was  even  sometimes  supposed 
that  such  a  memory  of  a  movement  must 
necessarily  precede  the  movement  which  we 
desire  to  make.  That  this  assumption  is 
not  true  was  demonstrated  in  the  experi- 
ment already  described,  the  one  showing 
that  voluntary  control  of  a  reflex  can  be 
obtained  by  the  method  of  conditioning 
(pp.  44f.). 

Not  only,  however,  is  this  anticipatory 
proprioception  not  necessary,  but  research 
has  also  shown  that  proprioception  alone— 
or  even  when  combined  with  a  visual  image 
of  what  the  movement  should  be— is  not  a 
sufficient  preliminary  process  to  produce  'at 
will'  a  movement  never  before  voluntarily 
initiated. 

In  certain  experiments,  persons  who 
could  not  move  their  ears  voluntarily  had 
their  ear  muscles  stimulated  electrically  so 
as  to  produce  the  mo\ement.  These  per- 
sons felt  the  movement  and  saw  it  in  a 
mirror.     Still   they  could  not   move   their 


Voluntary  and  Auiomafic  Behavior 


51 


ears  voliiiilarily.  In  allciiij^tiiig  lo  iikjvc 
them,  they  had  the  same  sense  o£  helpless- 
ness which  they  had  experienced  before  the 
electrical  stimulation.  In  their  attempts, 
however,  they  moved  the  volimtarily  con- 
trolled muscles  of  the  brow,  jaw  and  cheek, 
in  such  a  way  that  the  nuiscles  of  the  ear 
were  accidentally  moved  with  them.  Thus 
the  ear  muscles  were  brought  into  the  re- 
action pattern,  with  the  result  that  there 
occurred  both  afferent  impidses  lo  liie  mus- 
cles and  proprioception  irom  their  contrac- 
tion. It  was  only  then  that  the  proprio- 
ception, by  becoming  a  link  in  a  reHex  cir- 
cle, helped  to  develop  fidl  voluntary  con- 
trol of  the  ears. 

These  facts  give  us  a  picture  of  the  ori- 
gin and  development  of  voluntary  move- 
ment. It  is  clear  from  them  that  the  first 
movement  of  our  muscle  groups  are  un- 
conscious and  involuntary,  and  that  they 
come  under  conscious  voluntary  control 
only  later,  after  the  muscles  have  been  'ac- 
cidentally' innervated. 

Reflexes,  Conditioned  Responses 
and  Voluntary  Acts 

In  many  instances  of  human  behavior 
there  is  no  difficulty  in  distinguishing  a 
simple  reflex  from  the  more  complicated 
conditioned  response  or  from  a  voluntary 
response.  Simply  by  observing  the  ante- 
cedents to  the  movement,  we  can  tell,  for 
example,  whether  an  eyewink  has  occurred 
voluntarily  or  has  been  caused  by  some 
stimulus.  In  the  case  of  the  conditioned 
knee  jerk,  however,  an  investigator  may  not 
always  be  able  to  tell  whether  the  move- 
ment of  the  leg  in  response  to  a  bell  as  a 
conditioning  stimulus  is  an  involuntary 
conditioned  response  or  whether  the  sub- 
ject is  'faking'  results  by  voluntarily  mov- 
ing his  leg  when  he  hears  the  bell. 

Numerous    experiments    have    been    de- 


vised (o  oblaiii  some,  oljjctlive  crilcrion  for 
llie  dillereiitiatirjii  ol  these  three  forms  of 
response.  It  has  been  found  that  the  reflex 
is,  on  the  average,  more  rapid  than  either 
the  conditioned  response  or  the  voluntary 
response.  Experiments  in  which  the  pupi- 
lary light  reflex  was  conditioned  showed 
that  the  average  latency  (the  time  jet  ween 
the  presentation  of  the  stimulus  and  the 
onset  of  the  response)  of  the  conditioned 
dilation  of  the  pupil  was  1.56  seconds  and 
of  the  conditioned  (onlraction  2.29  seconds, 
whereas  the  simple  reflex  to  light  is  gen- 
erally 0.2  lo  0.5  second.  The  average 
duration  of  the  conditioned  dilation  re- 
sponse was  8.24  seconds  and  of  the  condi- 
tioned contraction  response  10.93  seconds, 
whereas  the  duration  of  the  simple  reflex 
to  light  is  usually  1  to  4  seconds. 

There  may  be  overlapping,  however,  in 
the  speed  of  these  different  forms  of  re- 
sponse. In  the  case  of  the  eyelid  response, 
it  was  found  that,  through  practice  in  open- 
ing the  eyes  as  quickly  as  possible  immedi- 
ately after  the  eyes  had  closed,  the  speed  of 
such  voluntary  opening  increased  above  the 
speed  of  the  reflex.  Yet  this  result  does  not 
mean  that  the  voluntary  response  has  de- 
veloped into  a  reflex. 

The  conditioneci  response,  moreo\er,  usu- 
ally differs  qualitatively  from  the  uncondi- 
tioned. The  conditioned  knee  jerk  is  not 
quite  the  same  as  the  reflex  knee  jerk,  nor 
is  the  conditioned  wink  response  identical 
with  the  reflex  eyewink.  Under  most  ex- 
perimental conditions  the  conditioned  re- 
sponse is  seldom  as  great  in  magnitude  as 
the  unconditioned. 

Another  objective  difference  bet^veen  tlie 
reflex  and  the  voluntary  response  appears 
in  an  analysis  of  the  total  time  of  the  wink. 
If  this  time  is  analyzed  into  the  time  of 
opening  and  the  time  of  closing  the  eye,  it 
is  found  for  the  reflex  that,  as  the  time  of 


52 


Response 


dosing  decreases,  the  time  of  opening  also 
decreases.  In  voluntary  response  this  rela- 
tionship is  changed. 

A  further  difference  is  that  voluntary  re- 
sponse is  more  readily  modified  by  instruc- 
tion than  the  reflex.  At  times  the  change 
of  tlie  reflex  is  found  to  be  opposite  in  di- 
rection from  the  change  in  voluntary  re- 
sponse. For  example,  subjects  were  told 
to  relax  as  much  as  possible  during  both 
voluntary  and  reflex  action.  When  the 
records  of  the  eyelid  movements  were  ana- 
lyzed, it  was  found  that  the  latency  of  re- 
sponse was  generally  slightly  decreased  for 
the  reflex,  whereas  the  latency  of  the  volun- 
tary response  increased  under  relaxation. 
These  last  results  are  readily  understood. 
The  football  player  has  to  be  'keyed  up' 
to  start  immediately  upon  the  snapping  of 
the  ball.  If  he  relaxes  for  a  moment,  he 
may  be  caught  off  his  guard.  The  reflex, 
on  the  other  hand,  seems  to  work  best  when 
we  are  caught  off  guard.  If  our  attention 
is  concentrated  on  the  appearance  of  the 
stimulus  for,  let  us  say,  the  knee  jerk,  there 
is  likely  to  be  a  slight  inhibitory  effect  on 
the  reflex. 

Experiments  have  also  been  made  to  de- 
termine whether  any  differences  between 
reflex  and  voluntary  activity  can  be  discov- 
ered in  the  electrical  potentials  as  the  im- 
pulses pass  along  the  nerves  involved.  The 
results  indicate  that  the  pattern  of  these 
potentials  is  more  stereotyped  in  the  reflex, 
a  discovery  which  is  in  accord  with  the  con- 
ception of  a  reflex  as  a  fixed  form  of  re- 
sponse as  compared  with  the  variability  of 
voluntary  response. 

Voluntary  Acts  and  Learning 

The  fact  that  voluntary  acts  have  been 
so  highly  developed  in  man  gives  him  a 
considerable  advantage  in  learning  various 


sorts  of  behavior,  for  he  employs  volun- 
tary acts  in  his  initial  solutions.  When, 
for  example,  a  man  starts  to  learn  some 
difficult  movement,  like  a  new  kind  of  dive, 
he  has  an  idea  of  the  form  of  movements 
that  he  wishes  to  make  and  then  vohmtarily 
attempts  to  carry  out  the  movements.  Dur- 
ing the  dive  he  will  be  aware  to  a  certain 
extent  of  the  position  of  his  limbs,  and 
after  the  completion  of  the  dive  he  will 
have  a  memory  of  what  he  has  done.  On 
the  next  occasion,  he  may  make  use  of  this 
experience  by  voluntarily  attempting  to 
alter  the  form  of  his  dive.  By  successively 
and  voluntarily  altering  his  behavior  on 
subsequent  occasions,  he  is  able  to  learn 
much  more  rapidly  and  to  achieve  a  higher 
degree  of  proficiency  than  if  learning  had 
to  take  place  through  random  trials  or  con- 
ditioning. 

After  a  great  deal  of  practice,  acts  which 
were  originally  voluntary  become  more  and 
more  involuntary  and  finally  result  in  auto- 
matic acts  or  habits.  Thus,  in  learning  to 
operate  a  typewriter,  each  pressing  of  a  key 
is  at  first  a  voluntary  act,  but,  after  a  rea- 
sonable degree  of  proficiency  has  been  at- 
tained, the  typist  thinks  no  more  of  indi- 
vidual finger  movements  and  may  type  au- 
tomatically, while  thinking  about  some- 
thing else.  By  practice,  the  component  vol- 
untary acts  become  integrated  into  a 
smooth  sequence  of  movements  which  do 
not,  for  the  most  part,  enter  consciousness. 
In  fact,  if  the  person  becomes  aware  of  the 
acts  and  attempts  voluntarily  to  carry  them 
out,  his  performance  is  usually  impaired. 
Let  a  person  suddenly  become  fidly  con- 
scious of  what  he  is  doing,  while  he  is  per- 
forming some  well-coordinated  response, 
and  there  is  likely  to  be  an  interference  in 
the  smoothness  of  the  response.  When  he 
is  very  eager  not  to  make  a  mistake  in  the 


Voluntary  Acts  and  Learning 


53 


letter  he  is  typing,  lie  is  almost  suie  to  do 
something  wrong.  If  he  thinks  of  volun- 
tarily moving  his  legs  when  going  rapidly 
upstairs,  he  is  likely  to  trip.  This  change 
from  an  automatic  response  to  a  voluntary 
act  throws  the  individual  back  to  tlie  initial 
stages  in  the  development  of  his  habit. 

There  arc  many  examples  in  everyday 
life  of  the  way  in  which  acts  which  were 
originally  voluntary  become  automatic.  A 
pitcher,  when  he  throws  a  ball,  docs  not 
have  to  think  of  the  movement  he  is  going 
to  make.  The  act  is  voluntary  in  the  sense 
that  he  intends  to  pitch  the  ball,  but,  as  he 
starts  the  swing  of  his  arm,  he  is  likely  to  be 
looking  at  the  plate,  his  mind  occupied 
with  little  else  than  the  corner  of  the  plate 
he  wishes  to  'cut.'  Seldom  are  you  con- 
scious of  the  movements  of  your  vocal  or- 
gans while  you  are  talking,  nor  are  you 
often  conscious  of  how  you  are  going  to 
move  them  before  you  start.  For  the  most 
part,  you  are  occupied  with  the  direction 
of  your  thought  and  the  effect  you  are 
achieving.  You  hear  your  own  voice 
vaguely.  If  you  want  to  know  what  words 
you  are  actually  using  to  express  your  ideas, 
you  have  got  to  listen  to  yourself  talking. 
In  rapid  conversation  there  is  no  feasible 
way  of  being  aware  of  your  own  words  be- 
fore they  are  uttered.  Conversation  is  only 
one  example  of  habituated  automatic  ac- 
tion. A  day  is  replete  with  such  semivol- 
untary  acts,  acts  that  hardly  touch  the  con- 
scious level  at  all. 

There  are  examples  of  voluntary  acts 
which  have  become  even  more  automatic. 
We  curl  a  strand  of  hair,  bite  our  pencil 
tip,  tap  on  the  floor,  lattle  our  keys,  en- 
tirely unaware  that  we  are  doing  anything. 
While  walking  with  a  friend,  we  engage  in 
animated  conversation,  completely  uncon- 
scious of  the  action  of  our  legs.    Such  auto- 


matic acts  can  be  as  complex  and  can  in- 
volve as  highly  an  iruegrated  set  of  reac- 
tions as  any  fully  voluntary  response.  This 
fact  is  well  demonstrated  by  instances  of 
automatic  writing,  where  a  person  writes 
the  answers  to  (juestions  put  to  him  with- 
out the  least  ability  to  say  what  it  is  he 
has  written.  Since  it  seems  evident  in  such 
cases  that  ilie  hand  has  been  guided  by  'un- 
conscious' processes,  the  method  is  often 
used  to  discover  what  lies  below  the  level 
of  conciously  controlled  behavior. 

The  examples  which  we  have  examined 
in  these  last  paragraphs  illustrate  the  vari- 
ous forms  of  action,  from  wholly  voluntary 
to  unconscious  automatic  acts.  Such  a 
classification,  however,  is  by  no  means  clear- 
cut.  We  can  have  acts  that  are  entirely 
automatic  and  unconscious,  and  acts  that 
are  entirely  voluntary,  but  almost  all  volun- 
tary acts  contain  some  automatic  process. 
In  fact,  such  acts  as  piano  playing,  when 
performed  by  a  proficient  player,  contain 
so  much  automatic  response  that  it  is  cus- 
tomary to  use  the  word  automatic  rather 
than  voluntary  in  regard  to  them.  Here 
action  has  become  so  well  established  a 
habit  that  correct  response  follows  immedi- 
ately upon  stimulus,  whether  the  musician 
is  using  the  score  or  playing  from  memorv, 
that  is  to  say,  whether  the  stimuli  are  the 
printed  musical  notations  and  the  preced- 
ing finger  movements  or  the  latter  alone. 
It  is,  indeed,  frequently  difficult  to  say 
whether  an  action  is  entirely  automatic  or 
not,  as  when  the  musician  plays  softlv  over 
the  keys  while  conversing  with  a  friend,  or 
when  a  telegraph  operator  taps  SOS  on 
the  desk  with  his  finger  while  he  is  reading 
an  engrossing  detective  stor).  The  impor- 
tant point  is  that  most  of  om^  responses  ai-e 
a  mixture  of  the  t^\o  types,  being  both 
automatic  and  voluntary. 


54 


Response 


ACTS    AND    IDEAS 

Closely  related  to  the  complex  \oluntary 
and  automatic  acts  which  we  considered  in 
the  last  section  are  the  forms  of  behavior 
which  are  controlled  by  ideas  rather  than 
by  external  stimuli,  needs  or  volition.  Al- 
though some  animals  can  solve  elementary 
problems  involving  reasoning  and  ideas, 
only  man's  behavior  can  be  controlled  in 
any  considerable  way  by  ideas.  The  fact 
that  ideas  may  cause  acts  of  behavior  is 
called  suggestion.  Sometimes  such  sugges- 
tion comes  from  within  the  individual, 
sometimes  from  external  events  which  he  is 
observing  and  sometimes  from  the  actions 
or  words  of  other  individuals.  We  shall 
now  consider  these  forms  in  turn. 

Ideomotor  Action 

If  the  idea  of  an  act  impels  a  person  to 
carry  out  the  act,  we  speak  of  ideomotor  ac- 
tion. This  form  of  action  may  be  illus- 
trated by  the  dislike  of  some  persons  for 
high  places.  The  idea  of  jumping  comes 
so  strongly  to  them  that  they  fear  it  will 
break  over  into  action.  Nearly  everyone 
has  had  at  some  time  so  vivid  an  idea  of  the 
act  of  jumping  out  of  the  window  at  which 
he  was  standing  that  he  has  wished  to  with- 
draw from  the  spot  in  order  to  avoid  the 
danger.  Another  example  is  the  desire  to 
knock  off  the  top  hat  of  a  fellow  traveler, 
an  idea  which,  once  brought  to  mind,  may 
prove  almost  irresistible.  Advertising  has 
made  good  use  of  the  principle  of  ideo- 
motor action.  The  tired  tennis  player  is 
portrayed  in  the  act  of  smoking  a  certain 
brand  of  cigarette,  so  that  the  reader  may 
be  induced  by  the  idea  to  do  likewise.  In- 
numerable examples  of  a  similar  natuie 
could  be  taken  from  daily  life,  for  ideo- 
motor action  is  a  very  common  experience. 


Empathy 

Still  more  frequent,  however,  are  the  in- 
cipient movements,  sometimes  too  slight  to 
be  readily  detected,  at  other  times  quite 
noticeable,  which  are  aroused  in  us  by 
movements  in  our  environment.  An  ob- 
vious example  may  be  observed  at  a  foot- 
ball game  where  the  home  team,  let  us  say, 
is  holding  on  the  one-yard  line.  An  en- 
thusiastic and  partisan  spectator  may  push 
actively  and  urgently  with  the  players,  until 
suddenly  he  realizes  that  he  is  actually  push- 
ing his  neighbor.  Or  again,  when  spec- 
tators watch  an  acrobat  climb  to  the  top 
of  a  pole  balanced  on  the  head  of  a  col- 
league and  swing  back  and  forth  with  the 
tottering  pole,  the  whole  crowd  sways  in 
unison. 

In  looking  at  statues  and  buildings  and 
pictures,  or  in  listening  to  music,  this  sort 
of  movement  likewise  occurs.  We  may  feel 
the  thrust  of  the  foot  or  the  tension  of  the 
outstretched  hand  of  a  statue,  the  weight 
of  the  arch  on  its  columns  or  the  rise  of  the 
cohmins  themselves,  and  the  direction  of 
the  lines  and  weight  of  the  represented 
mass  in  the  picture.  Listening  to  music, 
we  often  find  ourselves  following  the  rhythm 
with  some  part  of  our  bodies.  Even  the 
rhythmical  click  of  the  car  wheel  over  the 
lail  may  arouse  a  motor  response.  Since  wc 
are  occupied  with  the  perception  of  the  ob- 
ject, we  are  for  the  most  part  not  conscious 
of  these  movements  in  ourselves.  Neverthe- 
less our  responses,  though  unconscious  as 
such,  give  dynamic  quality  to  these  percep- 
tions. The  lines  of  the  picture  become 
lines  of  force,  the  represented  mass  has 
weight,  the  rhythm  of  the  music  seems  to 
flow  smoothly,  the  curves  of  the  architec- 
ture appear  to  have  the  grace  of  a  moving 
object.  It  is  as  if  we  had  projected  our 
own  unconscious  movements  into  the  ob- 


Acts  and  Ideas 


55 


ject  ot  our  perception.  Because  ol  iliis 
'projection'  the  experience  has  been  termed 
empathy,  a  feeling  of  oneself  into  the  ob- 
ject of  regard. 

An  example  of  empathy  is  presented  in 
Fig.  22.  It  is  assumed  that  the  trainer  is 
unconscious  of  the  movement  of  his  leg;  he 


(IrawaJ  of  the  hand.  The  sight  ol  a  half- 
read  book  suggests  continuing  the  story; 
without  any  intervening  thought  the  stu- 
dent picks  it  up,  when  he  had  fully  in- 
tended to  settle  down  to  study.  The 
sleight-of-hand  performer,  by  a  movement 
of  the  other  hand,  suggests  a  shift  of  the 


■ 

np 

I^H 

^^^■^ 

BF^^^I 

1 

•31 

FIGURE    22.    EMPATHY 


Blind  Bill  Kelley  clearing  the  pole,  with  his  trainer,  Peter  Bennett,  watching.    Notice  the  cmpatliic  re- 
sponse ot  the  trainer.     [By  permission  of  Pictures,  Inc.] 


is  only  aware,  through  projection  of  his 
own  movements,  of  the  effort  being  made 
by  the  jumper,  that  is  to  say,  of  the  dynamic 
quality  of  the  perception.  Without  this 
assumption  of  projection  the  illustration 
would  be  merely  an  example  of  imitation 
and  not  of  empathy. 

Suggestion 

In  the  broad  sense  of  the  term,  sugges- 
tion plays  a  large  role  in  our  lives  of  ac- 
tion. The  immediate  perception  of  an  ob- 
ject most  frequently  leads  to  some  response 
which  depends  upoii  previous  experience 
with  the  object.     The  flame  suggests  with- 


attention  of  the  audience  away  from  the 
hand  that  is  doing  the  trick.  In  the  em- 
pathic  perception  of  lines  and  mass  there 
is  the  direct  suggestion  of  some  motor  re- 
sponse. The  individuals  of  a  mob  are  ex- 
tremely suggestible  to  the  action  of  one  or 
more  of  their  companions.  Although  the 
term  suggestion  is  used  legitimately  in  all 
these  instances,  it  is  usually  restricted  to 
that  action  which  is  brought  about  by  a 
verbal  instruction.  \Ve  act  through  sug- 
gestion when  we  respond  to  the  written  or 
spoken  word  uncritically.  In  most  in- 
stances such  a  response  is  immediate,  but  it 
may  on  occasions  be  delayed. 


56 


Response 


Children,  being  obviously  less  critical 
than  adults,  are  more  suggestible.  As  a 
consequence  their  testimony  is  particularly 
imtrustworthy.  This  trait  may  be  easily 
demonstrated.  The  child  is  asked  to  place 
his  hand  on  an  electric  heater  and  told  to 
say  when  he  feels  the  warmth.  After  the 
experimenter  has  made  the  motion  of  turn- 
ing on  the  current  (^vithout  actually  throw- 
ing the  switch),  the  child  will  soon  report 
that  he  feels  the  heat. 

On  occasion,  however,  adults  can  be  just 
as  suggestible  as  children.  Given  the 
proper  emotional  setting,  they  will  imagine 
the  impossible.  An  excellent  example  is 
what  occurred  in  the  autumn  of  1938  when 
the  story  of  the  Martians  came  over  the 
radio.  Many  persons  'actually'  smelt  the 
poisoned  fumes  which  the  men  from  Mars 
were  supposed  to  have  spread  on  Earth. 

A  person  is  said  to  be  highly  suggestible 
when  he  lacks  firm  convictions  of  his  own. 
Though  most  of  us  can  act  through  sug- 
gestion a  thousand  times  a  day  without 
losing  individuality,  there  are  the  extreme 
cases  where  a  person  has  so  few  firm  con- 
victions of  his  own  that  no  counter  argu- 
ment enters  his  mind  when  he  is  presented 
with  an  important  course  of  action.  Con- 
versely, there  is  the  negatively  suggestible 
person.  He  almost  invariably  has  some 
reason  for  not  doing  what  is  desired  of  him. 
The  first  type  cuts  out  the  coupon  of  the 
advertisement  at  once  and  mails  it.  The 
second  type  immediately  throws  the  adver- 
tisement in  the  wastebasket.  It  is  thus  that 
attitudes  toward  suggestion  determine  ac- 
tion in  the  large  as  well  as  the  small  affairs 
of  life.  Degree  of  suggestibility  is  an  essen- 
tial feature  of  personality. 

Hypnotism 

The  hypnotic  trance  and  its  manifesta- 
tions are  the  result  of  an  extreme  state  of 


suggestibility.  It  is  a  state  which  may  be 
induced  in  varying  degrees  in  most  normal 
persons  who  are  willing  to  cooperate  with 
the  hypnotist.  Except  that  he  can  respond 
adequately  to  external  stimulation  when 
the  hypnotist  suggests  it,  the  person  who 
has  been  hypnotized  is  in  a  condition  re- 
sembling sleep.  If  the  subject's  mind  is 
free  from  the  ordinary  inhibitions  and  re- 
sistance, he  readily  carries  out  the  instruc- 
tions given  him  by  the  hypnotist,  provided 
that  the  task  does  not  conflict  with  his  most 
fundamental  convictions.  He  will  commit 
an  artificially  arranged  crime  but,  contrary 
to  popular  belief,  he  cannot  easily  be  in- 
duced to  commit  an  offense  if  it  really  con- 
travenes strong  tendencies  of  ethical  con- 
duct, as  we  shall  see  presently. 

It  has  been  supposed  that  under  hyp- 
nosis a  person's  senses  are  keener  and  his 
strength  greater  than  normal.  Experi- 
ments, however,  have  shown  that  this  is  not 
the  case.  There  is  little  if  any  difference 
in  his  sensitivity,  and  the  feats  of  strength 
he  performs  under  hypnosis  he  can  also  do 
in  his  normal  state  if  he  is  willing  to  make 
great  effort.  It  has  also  been  found  experi- 
mentally that  persons  who  acted  through 
hypnotic  suggestion  as  if  they  could  not  see, 
actually  had  normal  vision. 

The  state  of  hypnosis  is  characterized  by 
its  contradictory  phenomena.  The  hypno- 
tized person  behaves  as  if  he  were  enthusi- 
astically acting  out  a  big  lie  in  order  to 
please  the  hypnotist,  acting  it  out  and  be- 
lieving it  as  he  acts.  Sometimes  he  has  to 
perceive  something  in  order  to  know  that 
it  is  something  he  is  supposed  not  to  per- 
ceive. For  instance,  the  subject  may  be 
told  that  he  is  now  blind  in  his  left  eye,  can 
see  only  with  his  right.  Immediately  he  be- 
gins to  act  consistently  as  if  he  were  blind 
in  his  left  eye.  The  hypnotist  then  shows 
him   a  little  box  into  which   he  can  look 


Hypnosis  and  Reaction 


57 


with  both  eyes.  First  the  hypnotist  lets  the 
subject  see  that  a  red  disk  is  inserted  at 
the  back  o£  the  box  at  the  left  and  a  green 
disk  at  the  back  at  the  right.  Then  he  tells 
the  subject  to  look  into  the  box  with  both 
eyes  and  asks  him  what  he  sees.  The  sub- 
ject reports  that  he  sees  a  green  disk,  be- 
cause the  red  disk  is  at  the  left  and  he  is 
simulating  blindness  with  his  left  eye.  Ac- 
tually the  box,  by  the  use  of  prisms,  reverses 
the  images  of  the  disks  left  for  right,  so  that 
the  reported  green  disk  is  really  seen  with 
the  left  eye.  Thus  it  appears  that  the  sub- 
ject really  can  see  with  his  left  eye  when  it 
helps  him  to  play  the  game  of  being  blind 
in  his  left  eye. 

Experiments  of  this  sort  make  hypnosis 
resemble  faking,  but  it  is  a  very  insistent 
and  enthusiastic  kind  of  faking.  For  in- 
stance, it  is  easy  to  suggest  successfully  to 
a  subject  that  he  is  insensitive  to  pain  in 
some  part  of  his  body  and  then  to  burn  or 
cut  him  in  that  region  while  he  carries  on  a 
gay  conversation  with  the  hypnotist.  In 
fact,  hypnosis  was  used  successfully  in  many 
cases  for  surgical  anesthesia  just  before  the 
discovery  of  ether  in  1846.  It  certainly 
takes  a  good  deal  of  enthusiastic  coopera- 
tion to  fail  to  notice  the  pain  when  your 
leg  is  being  amputated,  with  no  anesthesia 
but  with  the  hypnotic  suggestion  that  you 
are  not  to  feel  anything  in  the  leg. 

This  desire  to  please  the  hypnotist  has 
to  take  its  chances  along  with  all  the  other 
desires  that  fight  for  dominance.  Will  a 
subject  under  hypnosis  stab  a  man  with  a 
dagger?  He  will  stab  a  friend  with  a  card- 
board dagger  if  he  knows  the  dagger  is 
cardboard.  An  habitual  stabber  might  be 
persuaded  to  stab  an  enemy  with  a  real 
dagger.  A  college  student  was  once  in- 
dviced  under  hypnosis  to  throw  what  he 
knew  certainly  to  be  strong  nitric  acid  at 
the  face  of  a  very  good  friend.     The  acid 


never  reached  its  goal  because  invisible 
glass  was  interposed,  but  the  student  did 
not  know  about  the  glass.  Still  he  did 
know  that  he  was  in  a  psychological  labora- 
tory wiiere  strange  things  may  happen  with- 
out permanent  liarm  to  any  one,  and  he 
may  have  been  trusting  the  hypnotist  to 
jjrotect  him  from  the  apparent  consequences 
of  his  act.  Hypnotic  suggestion  is  only 
one  among  many  motives  that  act  upon  the 
hypnotized  subject. 

Suggestion  may  also  operate  after  a  sui)- 
ject  has  been  awakened  from  the  hypnotic 
state.  That  phenomenon  is  called  posl- 
hypnotic  suggestion.  For  instance,  the  sub- 
ject may  be  told:  "After  you  awaken  and 
before  you  leave  the  room,  you  will  take 
that  chair  and  stand  it  on  the  table."  Then 
the  subject  awakens,  looks  at  the  chair,  and 
puts  it  on  the  table.  He  gives  all  sorts  of 
excuses.  It  is  in  the  way  on  the  floor.  It 
looks  better  on  the  table.  He  was  thinkini; 
he  would  like  to  sit  way  up  there  on  the 
top  of  the  table.  One  such  subject  looked 
at  the  chair  and  exclaimed:  "I  want  to  put 
that  chair  on  the  table.  I  bet  it  is  because 
you  told  me  to  in  hypnosis.  I  am  not  going 
to  do  it!"  He  left  the  room,  banging  the 
door.  In  five  hours  he  was  back,  a  little 
sheepish.  He  looked  at  the  chair  and  the 
table.  "Well,"  he  said,  "I  may  as  well  get 
it  over  w^ith!"  And  he  lifted  the  chair  and 
put  it  on  the  table.  Then  he  heaved  a 
sigh  of  relief  for  a  dut)'  at  last  accomplished. 

REACTION 

The  preceding  sections  ha\  e  dealt  princi- 
pally with  the  qualitative  aspects  of  voli- 
tional acts. 

Reaction  Time 

We  turn  no^v•  to  the  speed  of  response  ami 
the  conditions  ^vhich  determine  the  speed. 


58 


Response 


The  problem  o£  the  reaction  time  arose  in 
1796,  when  a  certain  astronomer  at  the 
Greenwich  Obser\atory  in  England  dis- 
missed his  assistant  because  the  latter's  ob- 
servations of  the  time  at  which  stars  cross 
a  cross-hair  in  the  field  of  the  telescope  were 
almost  a  second  later  than  his  own. 
Twenty   vears   later   it   was   disco\ered    bv 


One  of  the  most  accurate  arrangement- 
for  the  measurement  of  human  response  is 
illustrated  in  Fig.  23.  Its  main  feature  is 
a  chronoscope  or  timing  device,  consisting 
of  a  synchronous  motor  and  a  dial  whose 
hand  is  attached  to  a  magnetic  clutch.  Two 
telegraph  keys  are  wired  to  the  instrument 
in  such  a  ^\ay  that  ^vhen  one  key  is  pressed 


FIGURE   23.      INSTRUMENT  FOR  TIMING  REACTIONS 

(A)  Bulb  for  response  kev;  {IS)  voice  keys;  (C)  light  stimulus;  (D)  relay  for  touch  stimulus;  (E)  chron- 
oscope; (F)  relay  for  sound  stimulus;  (G)  tuning  fork  for  time  control;  (H)  stimulus  keys.  [Courtesy  of 
the  C.  H.  Stoelting  Company  of  Chicago.] 


checking  the  observations  of  different 
astronomers  that  the  discrepancies  were  due 
to  more  fundamental  differences  in  the 
manner  of  reaction  than  would  be  produced 
by  mere  carelessness.  The  conclusion  was 
reached  that  these  measurements,  which  de- 
pend upon  the  speed  of  reaction  of  the  ob- 
server, were  affected  by  what  was  then 
called  Ure  personal  equation,  that  is  to  say, 
constant  individual  differences  in  reaction 
time.  When  the  first  psychological  labora- 
tory was  established  in  Leipzig  in  1879,  ex- 
periments on  reaction  times  were  under- 
taken. Ever  since,  the  determination  of 
reaction  times  has  represented  an  impor- 
tant technique  in  experimental  psycholog)'. 


the  clutch  engages  with  the  motor  and 
when  the  other  key  is  pressed  the  motor  is 
released.  In  the  simplest  experiment  the 
subject  is  seated  at  one  key  and  the  experi- 
menter at  the  other,  and  the  motor  is 
started.  The  experimenter  presses  his  key, 
ivhich  gi\es  the  desired  stimulus  to  the  sub- 
ject and  engages  the  cltuch  so  that  the  hand 
on  the  dial  revolves.  As  quickly  as  possible 
upon  perceiving  the  appropriate  signal,  the 
subject  presses  his  key,  thereby  releasing  the 
clutch,  so  that  the  hand  on  the  dial  stops. 
The  revolutions  of  the  hand  are  recorded 
on  the  dial.  As  the  speed  of  revolution  is 
already  known,  the  time  that  elapsed  be- 
tween   the    pressing    of    the    two    keys— in 


Simple  Reactions 


59 


short,  between  stimulus  and  response— may 
be  read  from  the  dial  in  milliseconds. 

Various  stimuli  and  types  of  response 
may  be  used.  For  example,  the  experi- 
menter may  signal  by  means  of  a  clicking 
sound  produced  by  a  relay,  or  he  may  give 
a  tactual  stimulus  by  means  of  a  magnetic 
contrivance  that  presses  on  the  subject's 
hand.  He  may  flash  an  electric  lamp  as  a 
visual  stimulus;  or,  if  a  discrimination  re- 
action is  desired,  he  may  illuminate  in  hap- 
hazard order  a  green  and  a  red  lamp,  re- 
quiring the  subject  to  react  to  one  color 
and  avoid  reaction  to  the  other.  For  word 
reactions  he  uses  a  voice  key  containing  a 
thin  diaphragm  which  vibrates  when 
spoken  against,  thus  temporarily  breaking 
the  electric  circuit.  The  experimenter  may 
speak  into  one  voice  key,  starting  the  clock, 
and  the  subject  may  speak  into  the  other 
key,  stopping  it.  There  are  other  possible 
arrangements  and  other  forms  of  electric 
clocks,  but  in  each  of  them  the  clock  is 
started  and  stopped  automatically  and  re- 
action times  are  obtained  which  are  accu- 
rate within  a  few  milliseconds. 

Simple  Reactions 

In  the  siinple  reaction  experiment,  the 
subject  is  generally  instructed  to  respond 
by  pressing  a  telegraph  key  as  quickly  as 
possible  after  the  signal  is  given  by  the  ex- 
perimenter. Not  only  do  individuals  vary 
among  themselves  in  speed  of  reaction,  but 
also  the  reaction  time  of  the  same  individ- 
ual varies  according  to  the  sense  organ 
stimulated.  The  following  table  will  give 
an  idea  of  the  approximate  range  of  the  re- 
action times  in  seconds  for  the  different 
senses. 

The  reaction  times  to  painful  stimuli  are 
especially  long,  owing  in  part  to  the  fact 
that  there  is  a  considerable  lag  between  the 
application  of  a  stimulus  and  the  conscious- 


Reaction  Times 

Kind  of  Stimulation 

{Seconds) 

Visual 

0.150  to  0.225 

Auditory 

0.120  to  0.185 

Tactual 

0.115  to  0.190 

Olfactory 

0.200  to  0.800 

Gustatory 

0.305  to  1.080 

Pain 

0.400  to  1.000 

Cold 

0.150 

Warm 

0.180 

ness  of  pain.  The  reaction  times  for 
warmth  and  cold  vary  according  to  the 
manner  of  application  of  the  stimuli.  Tiie 
reaction  to  taste  varies  with  the  pan  of  the 
tongue  stimulated  and  the  kind  of  stimu- 
lus; the  time  is  shortest  for  salt  and  longest 
for  bitter.  The  time  for  touch  varies  ac- 
cording to  the  part  of  body  stimulated  and 
to  the  limb  making  the  response.  The  re- 
action time  for  a  stimulus  applied  to  the 
forehead  is  longer  than  for  one  applied  to 
the  hand,  although  the  forehead  is  nearer 
the  brain.  The  reaction  of  one  hand  to  a 
tactual  stimulus  applied  to  the  same  hand 
is  quicker  than  to  a  stimulus  applied  to  the 
opposite  hand.  The  reaction  to  light  is 
faster  when  the  light  falls  on  the  fovea  (tlie 
area  of  clearest  vision  near  the  center  of  the 
retina  of  the  eye)  than  when  it  falls  on  an 
eccentric  part  of  the  retina,  the  time  in- 
creasing continuously  with  the  distance  ol 
stimulation  from  the  fovea.  Reaction  is 
more  rapid  to  binocular  than  to  monocidar 
stimulation. 

In  most  experiments  upon  reaction  time. 
a  preparatory  signal  is  given  before  the 
presentation  of  the  stimulus.  It  is  found 
that  the  reaction  time  varies  Avith  the 
length  of  the  intewal  between  the  prepara- 
tory signal  and  reaction  signal.  Constant 
intervals  between  2  and  4  seconds  give  the 
shortest  times.  If  the  preparatory^  signal  is 
varied  wathin  a  series,  so  that  the  subject 
never  knows  exactly  how  long  he  will  have 
to  wait  for  the  reaction  signal,  the  optimal 


60 


Response 


interval  ranges  between  12  and  16  seconds. 
The  act  of  preparation  seems  to  be  the 
chief  factor  involved  in  these  results.  If 
the  interval  is  too  short,  the  subject  has 
not  sufficient  time  to  'get  set'  and  the  stimu- 
lus may  come  before  he  is  quite  ready.  If 
he  has  to  wait  more  than  4  seconds,  the  in- 
terval becomes  too  monotonous  for  him  to 
hold  his  attention  entirely  on  the  task.  If 
the  interval  is  varied,  he  is  unable  to  as- 
sume a  constant  attitude  of  expectation  and 
therefore  requires  a  longer  interval  for  his 
quickest  reaction  than  when  the  interval  is 
constant. 

Distraction  usually  lengthens  reaction 
time,  but  sometimes  the  supposedly  dis- 
tracting stimulus  acts  as  a  spur  and  de- 
creases the  time.  This  paradoxical  effect, 
which  has  been  found  in  other  experiments 
where  concentration  is  necessary,  is  ex- 
plained by  the  fact  that  some  persons  use 
more  effort  to  concentrate  when  there  is  an 
obstacle  to  o\ercome.  City  dwellers  be- 
come so  accustomed  to  concentration  'in 
spite  of  the  noise  of  the  street  that  they 
often  have  difficulty  at  first  in  working  ef- 
ficiently when  they  go  into  the  country. 
Students,  studying  with  the  radio  turned 
on,  may  be  more  alert  to  their  work  because 
they  are  fighting  the  radio  as  a  potential 
distractor— more  alert  than  they  would  have 
been  in  the  quiet  without  the  radio's  chal- 
lenge. (For  fiuther  description  of  the  ef- 
fects of  distraction,  see  pp.  477  f.) 

Reaction  times  to  all  kinds  of  stimuli  de- 
crease with  an  increase  in  the  intensity  of 
the  stimulus.  This  decrease  in  time  is  most 
marked  in  the  range  of  weak  intensities. 

Although  an  individual's  reaction  time 
varies  according  to  the  nature  of  the  stimu- 
lus, the  question  arises  whether,  if  he  is 
quicker  than  his  fellows  in  his  response  to 
visual  stimuli,  he  will  also  respond  more 
quickly  to  auditory  and  tactual  stimuli.     In 


other  words,  is  there  a  speed  characteristic 
of  response  that  runs  through  all  a  person's 
motor  reactions?  In  a  series  of  experiments 
it  was  found  that  the  correlation  of  simple 
visual,  auditory  and  tactual  reaction  times 
is  really  quite  high.  Thus  if  a  person  ex- 
cels in  speed  of  reaction  to  one  kind  of 
stimulus,  there  is  a  good  chance  that  he  will 
also  be  quick  in  his  reactions  to  other  kincis. 

Sensory  and  Motor  Reactions 

If  a  runner  starts  sooner  than  his  rival  at 
the  crack  of  the  pistol,  it  is  owing  in  part  to 
the  difference  in  set  of  the  contestants.  It 
has  been  shown  in  the  laboratory  that  there 
are  two  types  of  reaction,  sensory  and 
motor.  In  the  sensory  type,  the  subject's 
attention  is  directed  by  die  initial  set  to  the 
stimulus,  and  in  the  motor  type  to  the  re- 
sponse which  he  is  to  make.  In  the  ex- 
treme form  of  sensory  reaction,  the  expecta- 
tion of  the  subject  is  directed  almost  ex- 
clusively to  the  coming  stimulus,  often 
with  a  steady  fixation  in  the  direction  of  its 
appearance.  In  the  extreme  motor  reac- 
tion the  idea  of  the  mo^•ement  to  be  per- 
formed in  terms  of  proprioception  is  domi- 
nant. If  the  subject  is  allowed  to  react 
'naturally,'  there  is  usually  an  attitude  mid- 
way between  these  two  forms,  or  an  alterna- 
tion of  the  two. 

These  differences  in  set  cause  differences 
in  reaction  time.  "When  the  reaction  tends 
toward  the  sensory  type,  the  time  is  longer 
than  when  it  tends  toward  the  motor  type. 
In  the  table  on  reaction  times  (p.  59)  vis- 
ual reactions  range  from  0.150  second  to 
0.225  second.  It  is  probable  that  the  time 
0.150  second  was  obtained  under  a  motor 
set  and  the  0.225  second  under  a  sensory 
set.  With  practice  one  tends  to  become  in- 
creasingly motor  until  the  reaction  becomes 
practically  automatic;  then  the  finger  move- 
ments occur  with  little  conscious  intention 


Simple  and  Complex  Reactions 


61 


as  soon  ;is  a  signal  is  given.  With  this  ex 
treme  niolor  set,  however,  premature  re- 
actions are  not  infrequent,  as  we  find  not 
only  in  the  laboratory  but  also  in  such  sit- 
uations as  racing.  A  runner  who  is  of  the 
extreme  motor  type  often  makes  a  false 
start.  Some  runners,  however,  prefer  to  be 
sure  of  the  signal,  even  though  they  are  a 
little  late.  These  different  types  are  found 
among  people  in  general;  there  are  those 
who  are  slow,  safe  and  sure,  and  those  who 
go  off  'half-cocked.' 

Discrimination  and  Choice  Reactions 

Most  of  oiu-  reactions  in  life  are  not  like 
the  simple  reaction  experiments.  It  is  sel- 
dom in  everyday  life  that  we  can  be  so  sure 
of  what  is  going  to  happen  as  to  set  our- 
selves to  react  automatically  at  maximum 
speed.  The  runner  who  is  not  alert  may, 
for  example,  start  at  the  soimd  of  an  auto- 
mobile backfiring  instead  of  at  the  pistol 
shot.  Consequently  some  discrimination  is 
generally  necessary  for  a  correct  response. 

In  the  laboratory  this  more  complicated 
situation  is  produced  by  varying  the  stim- 
uli. The  stibject  may  be  instructed  to  re- 
act only  to  a  red  light,  when  both  red  and 
green  signals  are  used  in  haphazard  order. 
This  is  a  discrimination  reaction.  It  is  ob- 
vious that  this  problem  is  similar  to  that 
confronting  the  locomotive  engineer  and 
the  automobile  driver.  The  necessity  of 
recognizing  the  correct  signal  increases  the 
average  reaction  time  above  the  time  of  the 
simple  reaction;  and,  the  more  motor  the 
set  of  the  subject  is,  the  more  likely  he  is 
to  react  to  the  wrong  light.  The  discrimi- 
nation situation  may  be  further  compli- 
cated by  requiring  a  choice  between  two  or 
more  reactions  as  well  as  a  discrimination 
between  stimuli.  The  subject  may,  for  ex- 
ample, be  instructed  to  respond  with  die 
right  hand  if  the  light  is  red  and  witli  the 


left  hand  it  the  light  is  green,  or  with  the 
right  hand  if  the  red  light  appears  on  the 
right  of  the  green  and  with  the  left  hand  if 
the  stimuli  are  reversed.  The  greater  the 
complications  in  such  choice  reactions,  the 
longer  the  reaction  time. 

In  the  discrimination  reaction  it  is  found 
that  the  more  the  stimuli  resemble  each 
other,  the  longer  are  the  reaction  times.  If 
black  and  white  are  used  as  stimuli,  the 
reactions  are  quickest.  Red  and  green 
come  next,  then  red  and  blue,  followed  bv 
red  and  yellow,  and  finally  red  and  orange. 
If  tones  are  used,  the  reaction  to  tones  dif- 
fering by  16  cycles  per  second  is  quicker 
than  to  tones  differing  by  12  cycles,  and 
much  quicker  than  to  tones  only  4  cycles 
apart.  When  lines  differing  in  length  are 
the  stimuli,  the  less  the  difference  between 
the  lines,  the  longer  are  the  reactions.  The 
reaction  time  is,  for  example,  shorter  for 
discrimination  between  lines  of  10  and  13 
millimeters  than  for  10  and  12  millimeters. 

Word  Reactions 

The  commonest  reactions  in  life  are 
verbal.  To  determine  the  nature  and  speed 
of  such  responses  numerous  experiments 
have  been  devised.  The  usual  method  is 
to  present  a  word  visually  or  vocally,  the 
subject  being  told  to  respond  as  quicklv  as 
possible  with  the  word  that  is  suggested  by 
the  stimtdus  word.  The  time,  -which  may 
be  taken  by  a  stop  watch  or  by  means  of 
voice  keys  and  a  chronoscope,  indicates  the 
speed  of  the  association  of  ideas  for  the 
person  tested. 

If  the  subject  is  told  to  respond  ^\•idl  die 
first  Avord  that  occurs  to  him,  the  associa- 
tion is  termed  'free.'  Frequently,  however, 
the  instructions  are  more  limited.  For  ex- 
ample, a  general  term  indicating  a  class, 
such  as  animal,  is  given  and  the  subject  is 
requiied  to  repl)  widi  tlie  name  of  a  mem- 


62 


Response 


ber  of  this  class,  such  as  bear;  or  he  is  in- 
structed to  respond  with  a  word  opposite 
in  meaning  to  the  stimulus  word.  Many 
other  varia'^ions  in  instruction  may  be 
given.  These  associations,  being  partially 
determined  from  the  start,  are  called  con 
trolled  associations.  Experiments  of  this 
nature  have  been  extensively  employed  in 
investigations  of  the  nature  of  the  thought 
process. 

Practical  Use  of  Reaction  Experiments 

An  individual's  ability  in  practical  affairs 
depends  in  part  upon  his  speed  of  reaction. 
It  is,  therefore,  frequently  of  value  to  know 
both  his  speed  of  reaction  in  a  given  situa- 
tion and  how  he  compares  with  other  indi- 
\iduals  under  similar  circumstances.  It  is 
also  of  interest  to  know  how  much  he  may 
improve  his  speed  and  accuracy  by  practice 
as  well  as  under  the  incentive  of  increased 
interest  in  the  task. 

Reaction  time  is  an  important  factor 
both  in  vocational  selection  and  in  deter- 
mining the  individual's  aptitudes  as  a  basis 
for  vocational  advice.  For  example,  in  the 
selection  of  telephone  switchboard  oper- 
ators, speed  of  response  and  relative  free- 
dom from  errors  are  essential  requirements. 
A  consideration  of  the  same  characteristics 
is  necessary  in  the  selection  of  chauffeurs 
and  machine  operators.  According  to  the 
results  of  tests  of  taxicab  drivers,  those  men 
with  the  greatest  number  of  accidents  have 
the  slowest  reaction  times.  Those  who 
have  the  fastest  reaction  times  have  also 
many  accidents,  perhaps  because  they  are 
overconfident  and  take  chances.  It  is 
therefore  desirable  to  select  drivers  whose 
reaction  times  are  neither  very  fast  nor  very 
slow. 

The  association-reaction  experiinents 
have  been  used  with  some  success  to  deter- 
mine guilt.    Words  which  are  related  to  the 


crime  are  interspersed  with  'neutral'  words. 
The  words  of  this  combined  list  are  read 
to  the  subject,  who  must  answer  as  rapidly 
as  possible  to  each  one  with  any  word  he 
can  think  of.  Anyone  knows  from  his  own 
experience  that  when  he  is  faced  with  an 
embarrassing  situation— one  that  is  emo- 
tionally toned— he  is  likely  to  hesitate  and 
often  to  reply  foolishly  or  irrelevantly.  In 
the  'crime'  experiment  there  is  exactly 
such  an  embarrassing  situation  for  the 
guilty  person.  Therefore  the  tendency  is 
for  the  reaction  time  to  the  relevant  words 
to  be  unusually  long,  or  at  least  to  vary 
more  than  the  reaction  times  to  the  neutral 
words.  In  addition,  the  meaningful  refer- 
ence of  the  words  is  often  different  in  the 
cases  of  guilt  and  of  innocence. 

This  same  method  is  used  to  discover  sup- 
pressed complexes— the  memory  of  painful 
experiences  which,  held  in  an  unconscious 
state,  often  give  rise  to  abnormal  mental 
conditions.  Because  such  complexes  are, 
like  the  concealed  knowledge  of  the  guilty 
subject,  highly  emotional  in  nature,  the  two 
test  situations  are  very  similar. 

REFERENCES 

1.  Crafts.  L.  W.,  Schneirla,  T.  C,  Robinson,  E.  E., 
and  Gilbert,  R.  S.  Recent  experiments  in  psy- 
chology. New  York:  McGraw-Hill,  1938. 
Chaps.  I  to  3. 

These  chapters  deal  with  'instincts'  (cats 
and  mice,  migration  of  birds  and  salmon)  and 
with  the  behavior  of  newborn  babies. 

2.  Estabrooks,  G.  H.  Hypnotism.  New  York: 
Dutton,  1943. 

An  up-to-date  survey  of  hypnosis  and  sugges- 
tion in   man. 

3.  Hilgard,  E.  R.,  and  Marquis,  D.  G.  Condition- 
ing and  learning.  New  York:  Appleton-Cen- 
tury,  1940.     Chaps.  2  and  13. 

A  text  and  reference  book  which  surveys  con- 
ditioning  and    learning   in    both    animals    and 


References 


63 


man.      Chapter     13     deals     vviili     physiological 
mechanisms   in   conditioning. 

4.  Hull,  C.  L.  Hypnosis  and  suggestibility.  New 
York:   Appleton-Century,  "1933. 

An  old  but  useful  summary  of  experiments 
and  unsolved  problems  in  the  understanding 
of  hypnosis  and  suggestion. 

5.  Morgan,  C.  T.  Physiological  psychology.  New 
York:  McGraw-Hill,  1913.  Chaps.  1.5,  18,  19, 
l-'O,   21. 

An  up-to-date  textbook  in  physiological  psy- 
chology. These  chapters  deal  with  reflexes, 
sleep  and  activity,  instinctive  behavior,  mating 
behavior   and   bodily    needs. 

6.  Shaffer,  L.  F.  The  psychology  of  adjustment. 
Boston:  Houghton  Mifflin,  1936.  Chaps.  2,  3,  4. 
An  elementary  text  on  mechanisms  of  human 
adjustment  approached  from  a  biological  point 
of  view.  These  chapters  consider  the  origin 
and  modification  of  behavior  and  the  role  of 
motivation. 


7.  Tomkins,  S.  S.  CKd.)  Contemporary  psycho- 
pathology.  Cambridge:  Harvard  University 
Press,   1943.     Chaps.  34,  36. 

Selected  readings  from  experiments  and  dis- 
cussions dealing  with  abnormal  behavior. 
Chapter  34,  by  H.  .S.  Liddell,  treats  of  the 
modification  of  instinct  by  conditioning.  Chap- 
ter 35,  by  R.  W.  White,  considers  the  nature  of 
hypnosis. 

8.  Woodworlh,  R.  S.  Experimental  psychology. 
New  York:  Holt,  193H.    Chaps.  5,  13.  II. 

A  comprehensive  textbook  of  experimcMtal 
psychology.  These  chapters  deal  with  ihe 
conditioned  response,  the  galvanic  skin  response 
and   reaction    time. 

9.  Young,  P.  T.  Motivation  of  behai'ior.  New 
York:  Wiley,  1936.     Chap.  5. 

The  only  text  and  reference  book  dealing 
entirely  with  motivation  in  relation  to  response 
Chapter  5  deals  specifically   with   set. 


CHAPTER 


Growth  and  Development 


MAN  is  an  organism,  as  the  preceding 
chapters  have  shown,  a  mass  of  proto- 
jjlasm  moving  about  on  the  lace  of  the 
earth.  His  movements  are  lawful.  They 
depend  on  his  properties  as  an  organism,  on 
his  bodily  structure  and  on  his  capacities 
for  response  to  stimulation  which  in  turn 
depend  upon  inherited  and  acquired  char- 
acteristics of  his  nervous  system. 

This  organism  that  is  man  has  a  life  to 
U\e.  It  begins  at  the  moment  of  concep- 
tion when  two  parent  cells  unite  to  form  a 
new  individual.  Then  at  once  the  new 
organism  begins  to  grow  and  develop,  at 
first  as  an  embryo,  then  into  a  fetus,  and 
then,  being  born,  into  an  infant,  a  child,  a 
youth,  an  adult  and  finally,  if  he  lives, 
into  an  old  person.  Since  growth  and  de- 
velopment are  such  important  characteris- 
tics of  man,  it  is  proper  that  we  should 
begin  our  detailed  study  of  man's  proper- 
ties by  seeing  what  happens  to  an  individ- 
ual organism  as  it  grows  and  develops  from 
conception  to  extreme  old  age. 

GROWTH,    DEVELOPMENT    AND 
MATURATION 

It  will  simplify  our  account  of  the  proc- 
esses of  growth  and  development  if,  at  the 
outset,  we  carefully  distinguish  between 
them.     We  shall  use  the  term  growth,  as 


the  biologists  do,  to  mean  merely  increase 
in  size,  and  it  will  apply  not  only  to  the 
overall  dimensions  of  the  body  in  terms  of 
height  (or  length)  and  weight,  but  also  to 
the  parts  of  the  body  as,  for  example,  the 
head,  arms  and  trunk— the  heart,  brain, 
skeleton,  muscles,  etc.  By  the  term  devel- 
opment we  shall  mean  the  changes  in  the 
shape  of  the  parts  of  the  body  and  the  inte- 
gration of  the  various  parts  into  functional 
units  as  growth  goes  on.  Growth  can  be 
measured.  Development  can  be  observed 
by  noting  changes  in  shape  as  they  occiu^ 
and  in  modes  of  behavior  as  their  matura- 
tion is  completed. 

We  shall  use  the  term  maturation  to 
mean  the  growth  and  development  that  is 
necessary  either  before  any  unlearned  be- 
havior can  occur,  or  before  the  learning  of 
any  particular  behavior  can  take  place.  For 
example,  one  of  the  first  coordinated  move- 
ments that  any  baby  makes,  is  to  raise  its 
head,  and  to  hold  its  head  upright  without 
support  while  sitting.  The  child  could  not 
perform  this  act  earlier  because  its  matura- 
tion was  not  complete,  that  is  to  say,  the 
muscles  at  the  back  of  its  head  and  neck 
had  not  gi-own  sufficiently,  and  the  con- 
nections of  nerve  fibers  and  synapses  lead- 
ing from  the  muscles  to  the  cerebral  cortex 
and  back  again  had  not  developed  enough 
to  activate  the  muscles.     The  maturation 


This  chapter  was  prepared  by  Leonard  Carmichael  of  Tufts  College. 

64 


Conditions  of  Growth 


65 


ol'  this  bit  ol  bcliavior  is,  llicicloie,  (oin- 
jDlcte  as  soon  as  the  f^rowth  and  integration 
of  the  parts  have  progressed  sufficiently. 
The  child  does  not  learn  "to  raise  its  head; 
maturation  is  all  that  is  needed.  But,  laicr 
in  life,  it  does  learn  to  raise  its  head  in 
order  to  see  something,  for  that  behavior 
means  attaching  the  newly  available  move- 
ment to  some  stimulus.  Similarly  the  child 
cannot  learn  to  write  until  the  growth  of 
the  small  muscles  in  the  fingers  and  their 
neural  connections  have  developed  suffi- 
ciently. It  can  learn  to  write  only  after  it 
has  developed  the  brain  capacity  for  learn- 
ing and  the  mviscular  capacity  for  fine 
movement. 

Conditions  of  Growth 

The  first  essential  condition  for  growth 
is  food.  For  a  few  days  the  newly  fertilized 
cell  finds  its  food  in  the  cell  itself.  Then, 
as  embryo  and  fetus,  it  derives  its  food 
from  the  mother  and  will  continue  to  get  it 
in  this  way  throughout  the  prenatal  period. 
If  growing  is  to  be  normal,  the  mother  must 
supply  her  child  with  a  well-balanced  diet, 
for  the  growing  cells  require  proteins,  car- 
bohydrates, fats,  vitamins  and  a  variety  of 
mineral  salts.  After  birth  the  neonate,  as 
the  newborn  infant  is  called,  gets  its  food 
by  mouth  and  must  digest  it  himself.  If 
he  cannot  digest  his  food  properly,  or  if 
his  mother's  milk  lacks  needed  elements 
for  his  diet,  his  growth  will  suffer. 

A  second  important  condition  for  human 
growth  is  the  supply  of  the  secretions  called 
hormones  from  some  of  the  endocrine 
glands.  (See  pp.  23  f.)  Chief  of  these 
are  hormones  from  various  lobes  of  the 
pituitary  body,  a  small  gland  situated  at 
the  base  of  the  brain.  One  hormone  af- 
fects the  growth  of  the  body  as  a  whole— 
particularly  the  skeleton.  If  the  amount  of 
the  secretion  is  too  great,  growth  is  abnor- 


mal and  rcsidls  in  gigantism;  if  not  eiiougii, 
it  results  in  dwarfism.  Anotlier  hormone, 
called  thyroxin  and  produced  by  the 
thyroid  gland,  influences  the  consumption 
of  oxygen  in  the  tissues  and  thereby  in- 
fluences metabolism  and  growth.  An  ab- 
sence of  this  hormone  in  early  childhood 
stops  the  growth  of  the  brain,  inhibits 
growth  in  stature— particularly  of  the  arms 
and  legs— and  results  in  producing  the  kind 
of  dwarf  known  as  a  cretin.  1  he  intersti- 
tial cells  of  the  sex  glands  furnish  a  hor- 
mone that  stimulates  the  growth  of  the 
secondary  sex  characters— the  rapid  growth 
and  changes  in  figure,  hair  and  voice  that 
occur  in  early  adolescence.  A  less  dramatic 
but  equally  important  part  is  played  by 
hormones  from  still  other  glands  in  the  as- 
similation of  food  and  the  removal  of 
waste  products  which  are  necessary  for 
growth. 

A  third  condition  of  growth  is  heredity, 
which,  of  course,  also  determines  the  two 
2:)revious  conditions— food  assimilation  and 
the  hormones.  However,  heredity  also  de- 
termines whether  the  fertilized  cell,  when 
gi'own  and  developed,  will  be  a  human  be- 
ing or  some  other  animal  and,  if  human, 
to  what  race  it  will  belong;  ^vhether  it  will 
be  a  boy  or  a  girl;  Avhether,  other  tilings 
being  equal,  it  will  eventually  be  large, 
medium  or  small  in  size;  whether  the  shape 
and  size  of  many  of  its  features  (for  ex- 
ample, eyes,  nose,  mouth,  lo'^ver  ja^v,  hands 
and  fingers)  will  be  like  those  of  its  father 
or  mother  or  one  of  its  grandparents  or  a 
more  remote  ancestor. 

A  detailed  account  of  the  la^\'s  of  hered- 
ity would  take  us  too  far  afield.  "We  may 
say,  however,  that  the  basic  factors  for  die 
transmission  of  characters  from  one  gener- 
ation to  others  are  called  genes.  No  two 
germinal  cells  have  tlie  same  genes.  Be- 
fore fertilization  there  is  usually  onlv  one 


66 


Growth  and  Development 


ovum  (female  cell)  but  there  are  millions 
of  sperms  (male  cells),  only  one  of  which 
joins  the  ovum.  The  newly  fertilized  cell 
has,  therefore,  an  almost  certainly  unique 
combination  of  genes.  If  some  other  sperm 
had  fertilized  the  ovum,  the  combination 
would  have  been  different.  If  conception 
should  take  place  a  month  later,  the  ovum 
woidcl  have  a  different  set  of  genes  and  the 
fertilized  cell  would  have  quite  another 
combination.  These  facts  help  us  to  un- 
derstand why,  for  example,  in  a  family  con- 
sisting of  a  large  number  of  children  of  the 
same  parents,  no  two  children  (identical 
twins  excepted)  are  of  the  same  size  and 
bodily  contour.  You  can  always  tell  one 
child  from  another  (except,  of  course,  with 
the  identical  twins). 

Finally,  a  fourth  condition  of  growth  is 
use  or  exercise.  General  exercise,  such  as 
walking,  gymnastics  and  sports,  increases 
heart  rate  and  blood  pressure  and  the  rate 
and  depth  of  respiration.  As  a  result,  the 
blood,  carrying  an  increased  supply  of  oxy- 
gen and  food,  passes  with  new  force  into 
the  smallest  of  the  capillaries  and  thus 
reaches  all  the  cells  of  the  body.  During 
the  growing  years  the  development  of  all 
parts  of  the  body  is  thus  quickened.  In 
continuous  and  violent  exercise  the  muscles 
particularly  involved  grow  larger.  The 
sprinter  develops  his  leg  muscles,  the  oars- 
man his  arm,  trunk  and  leg  muscles,  and, 
since  the  heart  has  an  additional  burden 
laid  upon  it,  it  is  frequently  permanently 
enlarged. 

Integration  and  Maturation 

Thus  far  we  have  regarded  growth  as  if 
it  were  an  end  in  itself,  as  if,  for  example, 
all  that  the  brain  does  is  to  grow  until  it 
stops  at  maturity.  Growth,  however,  is  only 
one  aspect— though  a  very  important  one— 
of  a  larger  process  of  development.     The 


end  of  development  is  the  production  of  a 
living  organism  prepared  to  do  all  the 
things  that  man  does.  Development,  there- 
fore, requires  not  only  the  growth  and  for- 
mation of  the  structural  parts  but  also,  as 
we  have  seen,  their  integration  into  a  func- 
tioning whole. 

We  may  illustrate  this  process  by  a  crude 
analogy.  The  structural  parts  of  a  gas  en- 
gine—the cylinders  and  pistons,  the  battery, 
wire^  and  timer,  the  carbureter  and  spark 
plugs— must  be  assembled,  fastened  into 
place,  carefully  adjusted  and  provided  with 
fuel  before  the  engine  as  an  integrated 
whole  is  ready  to  run.  The  integration 
both  of  the  engine  and  of  the  developing 
organism  consists  in  uniting  and  coordi- 
nating the  parts. 

There  are,  however,  two  important  dif- 
ferences between  man  and  a  gas  engine. 
First,  in  man,  under  the  guidance  of  the 
genes  inherited  from  his  ancestors,  develop- 
ment takes  place  automatically.  Second, 
when  the  gas  engine  leaves  the  assembly 
line  its  development  ends.  It  can  then  do 
all  the  things  it  can  ever  do;  it  can  start 
and  stop,  run  at  various  speeds,  and  pro- 
duce various  amounts  of  horsepower.  Ex- 
cept for  limbering  up  and  the  effects  of 
subsequent  wear,  its  basic  behaviors  are  all 
matured  at  once.  In  man,  on  the  other 
hand,  maturation  of  various  forms  of  be- 
havior goes  on  for  a  long  time.  Although 
at  birth  maturation  of  the  functions  neces- 
sary for  the  maintenance  of  life  has  been 
reached,  it  will  be  many  months  before  the 
child  has  complete  control  of  its  muscles 
and  years  before  it  can  reproduce  its  kind. 

The  Nervous  System  as  Integrator 

The  great  integrator  and  coordinator  of 
the  organism  is  the  functioning  nervous 
system.     Its  fibers  pass  into  almost  every 


The  Nervous  System  as  Integrator 


67 


structure  of  the  body,  few  of  which  can 
function  without  nerve  direction. 

The  rate  of  development  of  the  nervous 
system  is  not,  however,  uniform  through- 
out. The  spinal  cord  is  formed  and  devel- 
oping throughout  its  entire  length  by  the 
middle  of  the  second  month  of  the  pre- 
natal period.  The  lower  parts  of  the  brain 
—the  medulla,  midbrain  and  other  parts 
necessary  for  automatic  control— also  de- 
velop early.    Last  of  all  the  cortex  develops. 

We  may  illustrate  the  course  of  develop- 
ment in  the  lower  centers  by  experiments 
that  have  been  made  with  the  larva  of  the 
salamander,  Amblystoma.  This  salaman- 
der develops  quickly  under  water  from  a 
fertilized  egg  which  has  its  own  rich  supply 
of  yolk.  It  becomes  a  free-swimming  ani- 
mal before  it  must  seek  for  food.  Thus  it 
is  an  ideal  animal  in  which  to  study  the 
maturation  of  nerve  and  muscle  coordina- 
tion at  the  automatic  level.  The  develop- 
ment which  leads  up  to  swimming  behav- 
ior in  this  embryo  (see  Fig.  24)  may  be  de- 
scribed in  five  typical  stages,  as  follows:  (1) 
a  nonmotile  stage,  in  which  the  direct  mus- 
cle stimulation  by  electrical  or  mechanical 
means  leads  to  muscular  contractions  which 
occur  without  bodily  movement;  (2)  an  early 
C-flexure  stage,  in  which  a  light  touch  on 
the  skin  of  any  portion  of  the  body  leads 
to  a  bending  of  the  head  to  one  side;  (3)  a 
tight-coil  stage,  in  which  the  contractions 
noted  in  stage  (2)  extend  toward  the  tail 
to  make  a  coil;  (4)  the  S-reaction,  which  is 
characterized  by  a  reversal  of  flexure  before 
the  previous  C-flexure  has  been  completely 
executed,  thus  leading  to  the  sinuous  be- 
havior of  the  organism;  and  (5)  the  speed- 
ing up  of  this  S-reaction  so  as  to  produce 
the  typical  swimming  movement  of  the  am- 
phibian larva. 

Studies  were  also  made  of  the  neural  or- 
ganization of  the  central  nervous  system  at 


every  one  of  these  stages.  It  was  found  that 
development  in  specific  chains  of  neurons 
in  the  central  nervous  system  arc  necessary 
before  the  alterations  of  behavior  from 
stage  to  stage  can  take  place.  These  studies 
showed  clearly  that  a  particular  set  of  con- 
nections must  be  produced  by  growth  be- 
fore particular   responses   occur.      In   gen- 


FIGURE    24.       DEVELOPMENT    OF    SWIMMING    IN    THE 
YOUNG   SALAMANDER 

(A)  Stage  before  neuromuscular  activity  has  be- 
gun. In  this  stage  muscles  may  be  directly  stimu- 
lated. (5)  Beginning  of  C  or  reverse-C  movement. 
(C)  S-shaped  swimming  movement.  The  first  re- 
verse-C-flexure  progresses  toward  the  tail  while  an- 
other C-flexure  begins  at  the  head.  Muscle  con- 
tractions shown  black  at  flexures.  [After  G.  E. 
Coghill,  Anatomy  and  the  problem  of  behavior, 
Cambridge  University  Press,  1929,  pp.  7  f.] 

eral,  it  is  found  that  the  earliest  movement 
is  the  bending  of  the  head  to  one  side.  A 
little  later  the  bending  progresses  down- 
ward toward  the  tail.  The  development  of 
the  swimming  behavior  is,  therefore,  in  a 
head  to  tail,  or  cephalocaudal  direction. 
This  is  a  pattern  of  an  orderly  develop- 
ment of  neuromuscular  function  which  is 
also  found  in  the  maturation  of  bodily 
movements  in  die  child. 

The  development  in  the  central  ner\ous 


68 


Growth  and  Developmenf 


system  begins  with  the  spinal  cord  and 
continues  to  higher  and  higher  centers  of 
the  brain.  As  higher  centers  become  ef- 
fective, the  lower  centers,  without  ceasing 
to  act,  begin  to  be  influenced  by  the  higher 
in  new  ways.  This  development  from 
lower  to  higher  centers  is  spoken  of  as  the 
encephalization  of  junction.  The  word 
rncephalon  means  brain,  and  encephaliza- 
tion occurs  when  the  control  of  functions 
migi^ates  in  the  developing  child  or  in  the 
evolution  of  animal  species  from  the  spinal 
cord  to  the  brain.  After  encephalization 
has  taken  place,  the  same,  process  of  devel- 
opment is  continued  as  corticalizalion  of 
function,  the  migration  in  individual  or 
evolutionary  development  of  functional 
control  from  the  lower  centers  of  the  brain 
to  the  cerebral  cortex,  where  the  highest 
centers  lie.  Thus,  as  development  of  the 
individual  continues,  the  higher  centers 
come  to  play  a  more  and  more  important 
role  in  what  the  organism  does.  In  man 
all  volimtary  movement  and  all  learning 
are  largely  dependent  upon  the  develop- 
ment of  these  higher  centers. 

GROWTH    AND    DEVELOPMENT 
BEFORE    BIRTH 

We  turn  now  to  follow  the  course  of 
growth  and  development  of  a  human  being 
from  a  fertilized  cell  to  his  birth. 

The  Beginning  of  Human  Growth 

The  growth  of  a  human  being  starts  first 
^\'ith  the  enlargement  of  the  fertilized  cell. 
Then,  when  the  cell  has  reached  a  certain 
size,  it  divides  into  two  smaller  cells,  each 
with  a  nucleus  and  surrounding  proto- 
plasm. These  cells  grow  and  again  divide. 
The  process  continues,  the  number  of  cells 
increasing  in  geometrical  proportion. 
Meanwhile  the  tiny  individual  is  migrating 


from  the  o\iduct,  where  fertilization  took 
place,  to  the  wall  of  the  uterus,  where  it 
soon  becomes  attached.  Here  growth  con- 
tinues more  rapidly  until,  two  weeks  after 
fertilization,  the  first  period,  called  the 
germinal  period,  comes  to  an  end.  (See 
Fig.  25.) 

The  next  fi\'e  weeks  of  the  life  of  the 
prenate   (as   tlie  organism  is  called  before 


Uterine  blood  vessel 


Maternal 
blood - 
space 


Fetal  villi 


FIGURE   25.      UTERUS,    MEMBRANES  AND   EMBRYO    IN 
EARLY    PREGNANCY 

[After  L.  Carmichael,  A  handbook  of  child  psy- 
chology  (2nd  ed.),  Clark  University  Press,  1933,  p. 

50.] 

birth)  constitute  the  embryonic  period. 
Growth  goes  on  as  before  by  cell  enlarge- 
ment and  division,  but  differentiation  also 
begins.  These  changes  are  tlie  start  of  a 
long  process,  and  some  of  the  new  struc- 
tures do  not  become  recognizable  for  sev- 
eral weeks.  Others  develop  rapidly.  By 
the  end  of  the  first  week  of  the  period 
(three  weeks  after  fertilization)  there  occurs 
the  first  independent  activity  of  the  grow- 
ing human  embr)o,  namely,  the  beating  of 
the  cells  which  later  de\elop  into  the  adult 
human  heart. 

It  may  be  remarked  that  at  all  times  in 
the  uterine  life  of  the  prenate,  the  circula- 
tory system  is  completely  separated  from 
the  maternal  blood  s)stem  by  cell  walls.  A 
highly      complex      structure      called      the 


rfie  Beginning  of  Human  Growth 


69 


placenta  develops  to  provide  a  iiuaiis 
whereby  the  independent  blood  systems  o£ 
the  mother  and  child  can  communicate. 
(See  Fig.  26.)  Through  the  walls  of  this 
structure  oxygen  and  food  substances  pass 
from  the  mother's  blood  to  the  independ- 
ent blood  stream  of  the  embryo  and  fetus. 
Carbon  dioxide  and  the  other  waste  prod- 
ucts from  cell  activity  pass  back  into  the 
maternal  blood  through  the  placenta.  Fur- 
thermore, there  is  no  neural  connection  at 
any  time  between  the  mother  and  the 
growing  fetus.  Contrary  to  superstitious 
belief,  no  transfer  of  ideas  can  take  place 
between  the  mother  and  the  fetus.  Some 
drugs  taken  by  the  mother  may,  it  is  true, 
affect  the  fetus.  It  may  be  also  that  some 
strong  emotions  of  the  mother,  which  are 
related  to  changes  in  the  chemical  make-up 
of  her  blood,  have  some  effect  on  the  tni- 
born  child.  If,  however,  the  future  mother 
wants  a  certain  big  strawberry  and  does  not 
get  it,  this  act  does  not  produce  a  'straw- 
berry mark'  on  the  unborn  child  which  she 
is  carrying,  no  matter  what  superstition 
may  say. 

By  the  end  of  the  second  month,  the 
embryo  begins  to  look  like  a  human  being, 
and  thereafter  until  birth  seven  months 
later  it  is  called  a  fetus.  The  fetal  period, 
regarded  as  a  whole,  is  first  merely  a  con- 
tinuation of  the  growth  and  development 
already  begun.  The  external  parts  of  the 
body— the  features  of  the  face,  the  arms  and 
fingers,  the  legs  and  toes— become  more 
clearly  defined.  There  is  also  at  this  time 
a  rapid  increase  in  size.  Beginning  with 
the  fourth  month  the  cerebral  cortex  de- 
\elops  rapidly.  Development  of  functional 
connections  in  the  nervous  system  thus  far 
has  been  restricted  for  the  most  part  to  the 
spinal  cord  and  the  lo^\'er  parts  of  the  brain 
—those  parts  which  have  the  involuntary 
controls  of  the  organs  and  muscles  of  the 


body.  Now  the  cortex,  man's  most  distin- 
guishing feature,  starts  its  rapid  functional 
development.  Presently,  the  fetus  begins 
a  wide  variety  of  movements  which,  as  its 
development  proceeds,  become  more  and 
more  individualized.  The  first  recorded 
movement,   as   the   result  of  experimental 


Intervillous         Amnion 
space 


Chorion 


■J  r:^'^/^}     1^,  - 


■Villus 


sUterine 
vein  artery 

FIGURE  26.    FETAL  AND  MATERNAL  BLOOD  STRE.\^rS 

In  the  placenta  the  fetal  blood  stream  (umbilical 
artery  and  vein)  and  the  maternal  blood  stream 
(uterine  artery  and  vein)  do  not  join.  [From 
Human  Physiology  by  Winton  and  Bayliss,  by  per- 
mission of  J.  &  A.   Churchill,  Ltd.,   London.] 

stimulation  of  fetuses  that  were  born  pre- 
maturely or  removed  from  the  mother  by 
surgical  means,  occtured  Avhen  die  fetus 
was  about  eight  and  one-half  weeks  old. 
(See  Fig.  27.)  The  stimulus  Avas  a  light 
touch  on  the  cheek  near  die  moudi  and  it 
induced  a  contraction  of  die  long  muscles 
of  the  body  and  neck  whicli  resulted  in  a 
flexion  of  the  body  and  accompanying 
movements  of  the  arms.     A  week  later  a 


70 


Growth  and  Development 


FIGURE   27.      HUMAN  FETUS  WHEN  ACTIVIIV  BEGINS 

Photographs  of  response  of  fetus  to  touch  stimulation  at  about  eight  weeks  of  age.     [After  D.  Hooker 
A   preliminary  Alias  of  early  humafi  fetal  activity,   1939,  p.   15.] 


Rates  of  Prenatal  Growth 


71 


similar  stimulation  produced  a  rotation  of 
the  pelvis  in  addition  to  a  flexion  of  the 
body.  By  the  twelfth  week  local  move- 
ments resulted  from  stimulation  of  the 
arms  and  legs  of  the  fetus.  About  the 
same  time  stimulation  of  the  palm  resulted 
in  a  partial  closure  of  the  fingers;  this  is 
the  response  which  will  later  develop  into 
the  grasping  reflex.  These  instances  are 
perhaps  enough  to  indicate  the  course  of 
development  of  motor  responses. 


sponse  does  not  succeed  in  removing  the 
stimulus,  the  guinea  pig  rotates  its  whole 
trunk  in  such  a  way  as  to  favor  removal 
of  the  touched  spot  from  the  noxious  stim- 
ulus. If  the  stimulus  still  continues  to  be 
effective,  it  may  be  that  the  guinea  pig's 
limbs  begin  to  beat  out  a  rhythmic  swim- 
ming pattern  which  effectively  moves  the 
whole  organism  away  from  the  stimulus 
save  in  so  far  as  it  is  held  fast  by  the  um- 
bilical cord.     No  one  can  watch  such  be- 


FIGURE  28.      ADAPTIVE  FETAL   BEHAVIOR 

Tracings  of  outline  posture  of  the  localizing  paw  movement  of  a  guinea  pig  fetus  a  few  days  before  the 
period  of  natural  birth.  Note  the  accuracy  of  this  unlearned  behavior.  [After  L.  Carmichael  and  M.  F. 
Smith,  /.  genet.  Psychol.,  1939,  54,  432.] 


The  responses  of  the  prenate  become 
more  and  more  versatile  and  more  and 
more  effective  as  growth  continues.  In 
some  mammals,  such  as  the  guinea  pig,  in 
which  the  development  of  behavior  before 
birth  has  been  studied  in  great  detail,  this 
sequence  can  be  seen  clearly.  It  is  possible 
in  the  few  weeks  of  prenatal  development 
to  observe  how  a  first  slight  twitch  of  the 
forelimb  develops  into  behavior  which  in- 
volves the  effective  use  of  almost  every 
group  of  body  muscles.  Some  of  these  late 
fetal  sequences  of  response  are  marvelously 
well  adjusted.  In  experimental  work  on 
still  unborn  guinea  pigs  it  has  been  shown, 
for  example,  that  the  animals  can  localize 
and  brush  away  with  an  appropriate  paw  a 
stimulus  applied  to  almost  any  area  of  the 
skin.     (See  Fig.  28.)     If  this  brushing  re- 


havior  in  a  fetus  that  has  been  prepared  for 
experimental  observation  without  recog- 
nizing the  subtle  perfection  of  the  develop- 
ment for  future  activity  that  is  begun  be- 
fore birth. 

Rates  of  Prenatal  Growth 

Growth  before  birth  is  exceedingly  rapid. 
The  fertilized  cell  has  a  diameter  of  0.013 
millimeter  or  ^2000  inch.  By  the  end  of 
the  two  weeks  of  the  germinal  period  the 
prenate  has  a  length  of  6.0  millimeters  or 
y^  inch,  an  increase  5  hundredfold  in 
length  (more  than  100  millionfold  in  vol- 
ume). During  die  eighth  week  die  fetus  is 
about  an  inch  long  and  has  increased  its 
length  2  thousandfold  since  tlie  beginning. 
At  birth  an  average  neonate  has  a  length  of 
20   inches.      That   makes    it   about   40,000 


72 


Growth  and  Developmeni 


times  longer  than  the  ovmn  from  which  it 
sprang,  several  thousand  million  times  its 
original  volume.  The  average  rate  per 
week  for  the  40  weeks  of  the  uterine  period 
is  one-half  inch.  The  growth  per  week  at 
first  increases  rapidly  and  then  after  birth 
slows  down.  If  the  rate  at  birth  were 
maintained  until  maturity,  a  grown  man 
would  be  45  feet  tall. 


the    prenatal   period,    however,    the   brain 
reaches  about  two-thirds  of  its  adult  size. 

Before  birth  growth  of  the  brain  by  the 
cell  division  of  its  neurons  comes  to  an 
end.  There  are  approximately  twelve 
thousand  million  neurons  in  a  normal 
brain  at  birth  and  there  is  no  increase  in 
this  number  dining  any  part  of  postnatal 
life. 


£  mo.  (fetal)     5  mo.      Ncvx/bom 


FIGURE   2g.      BODY   PROPORTIONS  DURING   GRO^VTH 

Changes  in  relative  form  and  proportion  of  human  bodv  in  fetal  life,  childhood,  \oiith  and  adult  life. 
[After  C.  M.  Jackson;  in  W.  J.  Robbins,  S.  Brody,  A.  G.  Hogan,  C.  M.  Jackson  and  C.  ^V.  Green,  Growth, 
Yale  University  Press,   1928,  p.  118.] 


The  structures  within  the  body  also  grow 
rapidly  during  the  entire  prenatal  period. 
From  about  the  third  month  until  birth 
the  weight  of  most  of  these  structures  in- 
creases at  about  the  same  rate;  the  small 
structures  groAv,  in  a  gi\en  period,  as  much 
as  the  larger  ones. 

In  the  early  days  of  the  embryonic 
period,  however,  the  heart  and  brain  grow 
much  more  rapidh  than  other  parts  of  the 
body.  At  about  the  fourth  week,  because 
of  the  large  brain,  the  head  constitutes 
nearly  half  the  length  of  the  embryo.  Even 
at  birth  the  size  of  the  head  is  much  larger 
in  proportion  to  its  body  length  than  it 
will  be  at  maturity.     (See  Fig.  29.)    During 


GROWTH    AFTER    BIRTH 

Although,  as  we  have  seen,  during  most 
of  the  fetal  period  the  structures  of  the 
body  gi'ow  at  about  the  same  relative  rate, 
after  birth  their  rates  and  increments  vary 
widely.  Despite  this  variability,  it  has  been 
found  that  the  rates  of  many  structures  fall 
into  groups  for  each  of  which  the  incre- 
ments of  gi'owth  through  a  number  of  years 
are  so  similar  as  to  suggest  types  of  growth. 

Types  of  Growth 

Four  of  these  types  widi  their  typical 
growth  curves  are  shown  in  Fig.  30.  They 
represent  only  the  growth  that  occurs  be- 


Types  of  Growth 


73 


twecn  birth  and  Llic  iwentieth  year.  Ihc 
increments  shown  in  the  figure  are  percent- 
ages of  the  total  growth  chiring  that  period. 
The  topmost  curve  is  of  the  Lymphoid 
Type.     It  represents  tlie  growth  of  the  ihy- 


200 


years,   and    (inalJy   it   neaily   slops   lor   the 
remainder  of  the  period. 

Below  this  in  the  figure  is  the  curve  of 
the  General  Type.  It  represents  the  growth 
of  the  body  as  a  whole  (excepting  ihe  head, 


Lymphoid  Type 

Thymus,  lymph  nodes, 
intestinal  lymphoid  masses. 


Neural  Type 

Brain  and  its  parts,  dura 
spinal  cord,  optic  apparatus, 
many  head  dimensions. 


General  Type 

Body  as  a  whole,  external  dimensions 
(with  exception  of  head  and  neck), 
respiratory  and  digestive  organs, 
kidneys,  aorta  and  pulmonary  trunks, 
spleen,  musculature  as  a  whole, 
skeleton  as  a  whole,  blood  volume. 

Genital  Type 

Testis,  ovary,  epididymis, 

uterine  tube,  prostate,  prostatic  urethra, 

seminal  vesicles. 


FIGURE  30.   MAJOR  TYPES  OF  POSTNATAL  GROWTH  OF  THE  VARIOUS  PARTS  AND  ORGANS  OF  THE  BODY 

The  several  curves  are  drawn  to  a  common  scale  by  computing  their  values  at  successi\e  ages  in  terms 
ot  their  total  postnatal  increments  (to  twenty  years).  [From  J.  A.  Harris,  C.  M.  Jackson.  D.  G.  Paterson 
and  R.  E.  Scammon,  The  measuremetit  of  man,  University   of  Minnesota   Press,   1930.   p.   193.1 


inus  gland  and  a  few  lymphoid  tissues.  The 
curve  rises  sharply  for  eleven  years  and 
then  falls  until  the  end  of  the  period  of 
twenty  years  is  reached. 

The  next  curve  is  of  the  Neural  Type. 
It  includes  the  brain,  the  spinal  cord  and 
the  eye.  The  ciuve  of  the  pineal  gland  is 
similar  but  does  not  rise  quite  so  rapidly. 
In  this  type,  growth  is  rapid  for  the  first 
six  years,    then   slower   for    the   next    two 


neck  and  chest)  in  its  external  dimensions, 
the  respiratory  and  digestive  organs,  the 
kidneys,  the  spleen,  the  muscles,  the  skele- 
ton and  blood  volume.  The  cur\e  rises 
rapidly  until  about  the  fourth  year,  much 
more  slowly  until  about  the  twelfth  year, 
rapidly  again  until  the  eighteenth  year  and 
slowly  again  until  the  end  of  tlie  period. 

The  last  curve  is  of  the  Genital  Type. 
It  shows  the  trend  of  groAvth  for  tlie  testes. 


74 


Growth  and  Development 


ovaries,  uterine  lube,  prostate  gland  and 
the  seminal  vesicles.  There  is  first  a  slight 
growth  for  four  years,  then  no  growth  at 
all  until  the  twelfth  year,  after  which  there 
is  a  rapid  growth  until  the  end  of  adoles- 
cence. 

Two  things  should  be  said  abovu  these 
typical  curves.  One  is  that  they  do  not  in- 
clude all  curves  of  growth.  There  are  a  few 
—those,  for  instance,  of  head,  neck  and 
chest  circumference,  of  the  weight  of  the 
suprarenal  glands,  the  human  uterus  and 
the  thyroid  gland— that  do  not  fit  into  any 
type.  Second,  it  should  be  emphasized  that 
the  typical  curves  are  merely  graphic  repre- 
sentations of  trends  of  growth.  As  such 
they  are  exceedingly  useful  in  aiding  the 
luiderstanding  of  the  growth  and  develop- 
ment of  the  individual. 

Maturity 

Maturity  means  cessation  of  growth.  A 
time  is  ultimately  reached  beyond  which, 
normally,  there  is  no  further  increase  in 
size.  Structures  belonging  to  the  neural 
type  reach  that  stage,  as  we  have  seen,  at 
about  ten  years  after  birth;  those  of  the 
lymphoid  type  at  twelve  years;  those  of  the 
general  and  genital  types  may  continue  to 
grow  until  at  least  the  twenty-fifth  year. 

Increase  in  weight  of  the  body  may,  of 
course,  occur  as  a  result  of  deposits  of  fat. 
When  growth  ceases,  its  curve  either  be- 
comes a  straight  horizontal  line  and  may 
so  continue  for  thirty-five  or  forty  years  or 
even  until  death  in  extreme  old  age,  or  the 
curve  turns  downward  representing  a  de- 
crease in  size,  the  regression  of  senescence. 

MATURATION    AT    BIRTH 

The  newborn  infant  is  called  a  neonate. 
We  turn  now  to  the  appraisal  of  its  mat- 
uration. 


The  Neonate  in  a  New  Environment 

Development  after  birth  is  a  continua- 
tion of  prenatal  development.  At  the  mo- 
ment of  birth  the  neonate  comes  into  a 
different  world.  For  months  he  has  been 
living  as  a  prenate  in  a  fluid  medium  of  a 
constant  temperature;  he  has  been  shielded 
by  his  liquid  environment  from  all  external 
stimuli  and  has  derived  his  oxygen  and 
food  from  his  mother  without  breathing 
and  without  digestion.  In  a  short  interval 
he  becomes  an  air-dwelling  animal  living 
in  a  variable  temperature.  He  is  now  sub- 
ject to  a  wide  variety  of  external  stimula- 
tion and  must  obtain  his  oxygen  by  his 
own  breathing  and  his  food  by  his  own 
digestion.  These  new  needs  require  that 
the  great  physiological  functions— circula- 
tion, respiration  and  digestion— be  matu- 
rated if  the  infant  is  to  survive.  Prema- 
ture births  show  that  the  maturation  of 
these  functions  is  fairly  well  established  as 
early  as  220  days  after  fertilization,  60  days 
before  normal  birth.  A  baby  born  180  days 
after  fertilization  rarely  survives,  princi- 
pally because  its  digestive  system  is  not  at 
that  time  sufficiently  developed. 

We  shall  subsequently  see  that  a  num- 
ber of  other  forms  of  behavior  reach  matu- 
ration at  birth.  The  muscles  of  the  trunk, 
legs  and  arms,  however,  have  not  yet 
reached  sufficient  development  for  their 
proper  effective  functioning  in  air.  The 
liquid  prenatal  environment,  because  it  is 
so  nearly  of  the  same  specific  gravity  as 
the  fetus,  allows  a  complexity  and  preci- 
sion of  prenatal  muscular  response  that  the 
neonate  cannot  again  achieve  until  some 
time  after  its  birth.  At  birth  the  cortex  of 
the  brain,  despite  the  fact  that  it  has  been 
developing  since  the  latter  half  of  the  fetal 
period,  is  still  immature. 


Maturation  at  Birth 


75 


Reflexes  in  the  Neonate 

During  the  firsi  lew  days  the  (:om{)lc;x 
feeding  reactions,  involving  head  orienta- 
t'on,  lip  reflexes,  sucking  and  swallowing, 
mature.  Soon  after  birth  many  infants  can 
also  grasp  a  rod  and  support  their  own 
weight  if  the  rod  is  lifted.  This  involun- 
lory  grasping  reflex  ordinarily  disappears 
during  the  first  half  year  of  life.  Another 
reflex  which  soon  disappears  is  the  Babinski 
reflex  m  which  the  infant  extends  its  toes 
when  the  bottom  of  the  foot  is  tickled. 
(See  Fig.  31.)    This  reflex  is  later  replaced 


!>y  tlie  plantar  reflex  which  consists  of  a 
( urling  up  of  the  toes  when  the  sole  of  the 
loot  is  stimulated.  The  plantar  reflex  de- 
pends ujjon  certain  motor  tracts  that  lead 
from  the  brain  to  the  spinal  cord  and  ap- 
pears when  these  fibers  mature  after  birth. 
An  infant  a  few  hours  old,  when  held 
vertically  in  such  a  way  as  to  support  his 
head  and  trunk,  and  with  the  soles  of  his 
feet  touching  the  floor,  often  makes  pranc- 
ing movements.  These  movements  con- 
sist in  alternately  raising  the  legs  and  flex- 
ing them  at  the  knee— behavior  which    is 


■[ 

^n 

■ 

^^^^ 

I^^^^N*       l^^^l 

F 

[^^i 

2exj|P 

||Sv 

^^/!i-~ """ JH 

^A 

cz 

~      ^ty^g^--^ 

®"^^ 

- — '_        .••,„™. 

""^5^^., 

^^ — 

-    -^ 

FIGURE    31.       INFANTILE    REFLEXES 

{A)  Defensive  reflex  with  left  foot  to  slight  pinch  on  inner  surface  of  right  knee.  [B)  Stimulation  for 
Babinski  reflex.  The  blunt  end  of  a  match  is  rubbed  across  the  sole  of  the  foot.  The  result  is  shown  in 
(C).  The  great  toe  shows  extension,  whereas  the  small  toes  shown  "fanning'  or  flexion.  This  is  a  variable 
reflex  as  far  as  the  pattern  is  concerned.  (D)  The  grasping  reflex  (infant  12  days  old).  [After  J.  B.  AVat- 
son.  Psychology  from,  the  statidpoint  of  a  behaviorist,  Lippincott,  1919.  p.  239.] 


76 


Growth  and  Development 


part  o£  tlie  leg  movement  in  walking.     (See 
Fig.  32.) 

There  are  many  other  specific  reflexes 
\\hich  develop  in  normal  human  individ- 
uals at  various  periods. 


FIGURE    32.       EARLY    STEPPING    MOVEMENTS 

Infants  a  few  hours  old  sometimes  show  prancing 
steps  when  they  are  supported  under  the  arms,  as 
shown  in  diagram.  The  patterns  basic  to  this  be- 
havior are  probably  related  to  walking  responses 
which  will  appear  much  later.  [Sketch  of  photo- 
graph from  M.  B.  McGraw,  Child  dex'elopment, 
1932.  3,  295;  by  permission  of  Williams  and  Wilkins 
Company.] 

Maturation  of  the  Receptors 

The  skin  sense  for  pressure  develops 
first.  We  have  already  seen  that  a  human 
fetus  eight  and  a  half  weeks  old  responded 
to  pressure  stimulation  near  the  mouth. 
The  mouth  is  the  first  area  that  can  be 
activated  by  pressure  stimuli.  Later,  ef- 
fective areas  for  pressure  stimulation  spread 
over  the  entire  skin  surface.  Such  sensory 
development,  like  the  development  of  move- 
ment, proceeds  in  a  general  cephalocaudal 
direction. 


Responses  to  the  stimulation  of  tem- 
perature and  pain  receptors  can  also  be 
elicited  during  fetal  life.  The  pain  sense 
is,  howe\er,  not  well  developed  in  the 
prenate.  A  needle  prick  or  even  a  lacera- 
tion of  deep  tissues  in  a  fetus  may  not  cause 
any  more  vigorous  response  than  would  a 
light  touch  with  a  soft  hair.  This  late  de- 
velopment of  pain  may  have  important 
value,  for  it  may  minimize  the  shock  of  the 
mechanical  pulling  and  squeezing  that  arc 
incident  to  birth. 

It  has  long  been  known  that  at  birth  the 
receptors  for  smell,  taste,  vision  and  hear- 
ing (as  soon  as  the  liquid  has  drained  from 
the  middle  ear)  respond  to  their  appropri- 
ate stimuli.  The  responses  are  movements 
usually  of  some  part  of  the  face  like  blink- 
ing, frowning  or  opening  the  eyes  wide. 
The  neonate  does  not  distinguish  objects 
until  the  higher  levels  of  the  brain  have 
developed.  Recently  systematic  obsen'a- 
tions  have  been  made  of  a  number  of  in- 
fants, some  of  whom  were  prematurely 
born  babies  that  are  called  fetal  infants 
because,  except  for  the  accident  of  birth, 
they  would  still  be  fetuses.  They  ranged 
in  age  from  twenty-eight  to  forty  weeks. 
It  was  found  that  they  not  only  respond  to 
both  auditory  and  visual  stimuli  during  the 
seventh  month,  but  also  that  their  re- 
sponses inay  change  in  kind  at  a  later 
time.  For  example,  the  first  response  of 
fetal  infants  to  a  bell  may  be  a  slight  frown 
with  a  blink  of  the  eyes,  but  during  the 
ninth  month  its  response  changes  to  an 
opening  of  the  eyes.  Furthermore,  the 
earliest  movements  are  feeble  and  spas- 
modic, and,  as  a  general  rule,  they  cease 
entirely  if  the  stimultis  is  frequently  re- 
peated. Later,  they  become  stronger  and 
more  continuous.  These  facts  mean  that, 
■with  the  earliest  responses,  de\elopment 
is  not  quite  complete;   a  little  more   tinre 


Maturation  at  Birth 


77 


or,  it  may  be,  some  practice  is  necessary 
before  it  is  complete. 

Eye  movements,  which  are  later  so  im- 
portant for  visual  perception,  may  also  be 
observed  in  course  of  development  in  the 
fetal  infant.  During  the  seventh  month 
the  two  eyes  may  move  together  in  both 
horizontal  and  vertical  directions,  even  be- 
fore there  is  any  definite  response  to  a 
visual  stimulus.  During  the  eighth  month 
the  eyes  may  follow,  with  brief  movements 
Ijut  without  fixation,  any  object  that  moves 
slowly  across  the  visual  field.  During  the 
next  month  the  eyes  may  definitely  follow 
a  moving  object  through  an  arc  of  forty- 
five  degrees.  All  these  eye  movements  ma- 
ture quickly  shortly  after  the  time  of  nor- 
mal birth. 

There  are  located  in  each  inner  ear  of  a 
mammal,  not  only  the  complex  sense  or- 
gans which  make  hearing  possible,  but  also 
stabilizing  mechanisms,  the  static  or  vestib- 
ular receptors,  which  assist  the  organism 
in  maintaining  body  balance.  (See  pp.  374- 
378.)  There  is  good  reason  to  believe  that 
these  inner-ear  receptors  are  effective  in 
fetal  life.  Before  the  eyes  of  the  fetus  have 
moved  in  response  to  stimulation  by  light, 
they  can  be  made  to  move  by  changing  the 
position  of  the  fetus  with  respect  to  grav- 
ity in  such  a  way  as  to  stimulate  the  re- 
ceptors in  the  inner  ear.  The  maturation 
of  such  adjustments  makes  it  possible  for 
an  infant,  as  he  later  develops,  not  only  to 
maintain  his  posture  but  also  to  keep  his 
eyes  focused  upon  objects  even  when  his 
own  head  and  bodv  move. 


tion  which  results  from  certain  sf>-called 
emotion-arousing  situations  such  as  undue 
restraint,  sudden  noises  or  being  dropjxrd 
onto  a  pillow.  It  is  almost  certain  that 
the  component  movements  of  the  behavior 
patterns  of  emotions  are  a  result  of  matu- 
ration in  the  part  of  the  brain  called  the 
hypothalamus. 

The  hypothalamus  thus  tends  to  induce 
certain  emotional  patterns,  and  tiie  cerebral 
cortex  tends  to  inhibit  or  limit  this  action 
of  the  hypothalamus.  (See  p.  100.)  For 
instance,  rage  is  natural  to  cats  and  dogs 
—the  snarling,  hissing  attack  of  the  cat,  the 
growling,  snapping  attack  of  the  dog. 
These  behavior  patterns  are  activated  bv 
the  hypothalamus,  but  inhibited  by  the 
action  of  the  cortex.  The  surgical  removal 
of  the  cortex  releases  the  thalamic  action, 
and  these  animals,  when  disturbed,  snarl 
and  snap  quickly  and  automatically  in  a 
manner  so  closely  resembling  a  reflex  that 
their  behavior  is  called  sJiam  rage. 

Thus  it  comes  about  that  the  develop- 
ment of  the  cortex  makes  possible  the  de- 
velopment of  emotional  restraint  in  man, 
as  well  as  in  the  cat  and  dog.  A  child, 
using  his  cortex,  gradually  learns  what 
emotional  expressions  are  approved  by  the 
social  groups  to  which  he  belongs,  modify- 
ing his  inborn  behavior  patterns  accord- 
ingly. It  follows  that  emotional  maturity, 
the  control  of  emotion,  depends  on  the 
maturation  of  the  cortex  and  learning— 
when  the  individual  has  a  cortex  with 
which  to  learn. 


Maturation  of  Emotion 

It  is  doubtful  that  the  prenate  and  the 
neonate  show  clearly  differentiated  emo- 
tional responses,  such  as  fear,  joy  and  rage. 
Rather  it  appears  that  very  young  infants 


MATURATION    AFTER    BIRTH 

Between  the  neonatal  and  adolescent 
levels  of  development  comes  cliildhood.  In 
it  adapti^•e  behavior  appears,  the  ability  to 


experience  onlv  a  state  of  general  excita-      learn  develops  and  language  is  acquired. 


78 


Growth  and  Development 


The  Maturation  of  Adaptive  Behavior 

As  the  child  develops  he  progressively 
makes  a  large  number  of  movements  com- 
mon to  all  human  beings,  which  are  un- 
learned and  have  only  awaited  maturation 
to  be  performed.  These  movements  require 
the  action  of  the  higher  brain  centers  and 
so  are  instances  of  the  encephalization  or 
corticalization  of  function.  They  are,  in  a 
sense,  controlled  movements  and  may  be 
classified  as  \oluntary.  Examples  of  these 
forms  of  behavior  are  grasping,  creeping, 
standing  erect,  walking,  running.  ^Ve  may 
take  the  maturation  of  the  act  of  walking 
as  an  illustration  of  their  development. 

The  alternate  innervation  of  the  two 
legs  in  the  prancing  movement  already  de- 
scribed shows  that  a  highly  complex  neuro- 
muscular organization  is  well  along  at 
birth.  Before  the  child  can  walk,  how- 
ever, he  must  first  be  able  to  hold  up  his 
head,  then  to  hold  his  trunk  erect  with- 
out support  while  sitting.  The  matura- 
tion of  erect  sitting  must  await  the  stiffen- 
ing of  the  spine.  Next  he  must  be  able 
to  stand  erect,  an  act  which  he  cannot  do 
until  the  bones  and  muscles  of  his  legs 
are  strong  enough  to  bear  his  weight.  The 
order  of  these  maturations,  it  will  be  no- 
ticed, follow  the  cephalocaudal  rule.  The 
child  still  cannot  maintain  his  equilibrium 
until  maturation  effects  the  coordination 
of  the  sensory  nerves  from  his  muscles,  the 
sensory  nerves  from  his  semicircidar  canals 
(see  p.  378)  and  the  motor  tracts  leading 
to  his  muscles.  Only  then  can  he  trans- 
form the  prancing  into  a  walking  move- 
ment by  thrusting  his  flexed  leg  forward 
imtil  it  rests  on  the  floor,  at  the  same  time 
letting  his  center  of  gravity  also  go  for- 
ward. He  must  then  maintain  his  balance 
on  the  one  foot  until  the  other  is  brought 
up  and  thrust  forward.    The  repetition  of 


this  sequence  is  walking.  Walking  is  the 
end  product  of  a  series  of  maturations 
which  it  takes  the  prancing  infant  about 
twelve  to  fourteen  months  to  complete. 

Norms  of  Early  Development 

There  are  tables  and  charts  showing  the 
general  sequences  of  behavior  which  may 
be  expected  to  take  place  during  the  first 


Sociality.  Kindergarten 

^   Concepts:  Number,  form 

Speech:  Sentences    ■ 
^^  _^  Sptiincters:  Bladder  and  bowel  control 
_^   Larynx:  Words,  ptirases.  Walks 
-^  Legs,  feet:  Stands,  cruises 
_»  Trunk,  fingers:  Sits,  creeps,  pokes 
.  Hands:  Grasp  and  manipulate 
Head:  Balance 


Autonomic  system:  Physicochemical  control 

, ' ,  / ^  Tonic -neck -reflex:  Quickening 

,'///_^  Hand  closure  and  grip 
"./_^  Prerespiratory  movements 
^  Swallow,  sneer,  Babinski 
„  Trunk  extension 

.  Fetal  stage  (trunk  flexion,  oral  sensitivity) 
/_^  Embryonic  stage  (preneural  organization) 
.  Conception  (germinal  organization) 

FIGURE    33.       HUMAN    BEHAVIOR    GROWTH 

Diagram  to  sho\\'  gradual  development  of  behav 
ior  in  early  life.  [After  A.  Gesell  and  C.  S.  .Ama- 
truda,  Dex'elopmental  diagnosis:  normal  and  abnor- 
mal child  development,  Hoeber,  1941,  p.  9.] 

five  years.  (See  Fig.  33.)  In  the  first  year, 
the  child  gains  control  of  his  basic  muscles 
so  as  to  be  able  to  grasp  objects  and  stand 
erect  and  to  do  many  other  acts  in  his  new 
nonaquatic  environment.  In  his  second 
year,  typically^  he  walks  and  runs  and 
articulates  words  and  phrases.  At  this 
time  he  may  acquire  bladder  and  bowel 
control.  In  his  third  year,  he  speaks  sen- 
tences and  begins  to  comply  with  the  de- 
mands of  his  home.  In  his  fourth  year, 
he  asks  many  questions  and  becomes  self- 


Maturafion  Afier  Birth 


79 


dependent  in  the  routines  of  the  house. 
At  five  he  hops  and  skips,  can  tell  a  long 
story  and  is  "a  self-assured  conforming  citi- 
zen of  his  small  world." 

There  are,  nevertheless,  great  differences 
in  the  sequence  of  development  in  differ- 
ent children.  No  doubt  some  of  these  dif- 
ferences are  due  to  differences  in  inherited 
rates  of  maturation.  Some  differences  are 
also  due  to  differences  in  environmental 
opportunity,  as  the  studies  of  twins  sug- 
gest. (See  pp.  448  f.)  It  is  also  likely  that 
there  is  a  basis  in  maturation  for  the  ap- 
pearance of  certain  aptitudes,  like  musical 
ability. 

Maturation  of  Ability  to  Learn 

Thus  far  our  discussion  has  been  limited 
almost  entirely  to  development  in  general 
and  the  maturation  of  unlearned  behavior 
in  particular.  We  can  now  turn  to  some 
of  the  relations  between  maturation  and 
learning.  It  is,  of  course,  impossible  to  say 
just  when  maturation  ceases  and  learning 
begins.  It  may  be  that  the  fetal  infant, 
by  exercise  or  practice,  'learns'  something 
from  the  feeble,  spasmodic  and  discontinu- 
ous movements  that  he  makes  before  the 
maturation  of  his  eye  movements  is  com- 
plete. It  may  be  that  the  child  can  be  said 
to  learn  from  his  successes  and  failures 
when  he— as  some  of  them  do  while  taking 
their  first  steps— totters,  staggers,  falls  down, 
gets  up  and  tries  again.  The  question  of 
the  effectiveness  of  such  learning— assuming 
that  it  takes  place— has  been  the  subject  of 
a  number  of  investigations. 

Experiments  have  been  carried  out  on 
animals,  birds  and  mammals  to  determine 
the  effect  of  withholding  exercise  from 
certain  young  of  a  brood  or  litter,  while 
allowing  the  others  to  exercise  as  they 
de\'eloped.  Chicks,  for  instance,  have  been 
hooded  or  otherwise  kept  from  visual  ex- 


perience after  they  hatch,  to  keep  them 
from  using  the  seeing-pecking  behavior  for 
food.  Birds  have  also  been  prevented  from 
flying  until  other  birds  of  the  same  age 
were  flying  well.  Figure  M  shows  the  re- 
sult of  some  experiments  in  this  field. 


T  5 


E 
t;  3 


1 — r 


Group  A 


\>— Group  B 


\    y- Group  C 

\    \ 
\   ^     y-'Group  D 
\^\    \      ^Group£_ 

J \ I    ^^^^^ 


0         12         3         4         5         6         7 

Daily  test  series 

FIGURE    34.       chick's    PECKING    SKILL    AND 
MATURATION 

Errors  of  chicks  given  opportunity  to  peck  foi 
first  time  when  1  day  old  (Group  A)  up  to  when  5 
days  old  (Group  E).  Curves  show  greater  initial  ac- 
curacy in  older  chicks,  but  learning  is  alwavs  needed 
to  supplement  maturation.  Note  speed  of  learning 
in  4-day  groups.  [From  W.  W.  Cruze.  J.  cnnip. 
Psychol,  1935,  19,  391,  Williams  and  Wilkins  Co.] 

In  experiments  with  amphibians  it  has 
proved  possible  to  raise  experimental 
groups  of  larval  Amblystoma  (salamanders) 
in  water  containing  a  drug  ^\hidi  kept 
the  larvae  from  making  any  mo%ements. 
At  a  later  time,  when  a  control  group  de- 
veloped from  eggs  of  the  same  age  and 
raised  in  undrugged  water  were  freely 
swimming,  the  experimental  animals  were 
placed  in  fresh  water.  In  a  few  minutes 
the  preA'iously  anesthetized  animals  swam 
in  a  way  hardly  to  be  distinguished  from 


80 


Growth  and  Development 


that  of  the  animals   that  had  been  freely 
'practicing'  for  some  days. 

All  these  experiments  seem  to  show  that 
the  animal  who  was  backward  for  want  of 
exercise  may  overtake  the  animal  who  has 
had  exercise  all  alon^  after  thev  have  been 


given  equal  opportunity.  Does  this  result 
hold  also  for  the  human  organism?  This 
question  too  has  been  put  to  experiment. 
A  detailed  study  has  been  inade  of  a  pair 
of  twin  boys  from  the  age  of  twent)-onc 
days    to    the    age    of    twenty-two    months. 


Johnny 


Jimmy 


FIGURE  35.      DEVELOPMENT  OF  TWINS'   BEHAVIOR  WITH  PRACTICE 

Johnny  (left),  who  had  been  given  a  great  deal  of  active  exercise,  tackles  the  problem  of  getting  him- 
self down  from  the  pedestal  with  ease,  whereas  Jimmy  (ri_^ht),  who  had  been  given  a  minimum  of  active 
play,  sits  perched  on  top,  unable  to  solve  his  problem,  [.\ftcr  M.  B.  McGraw,  Growlh:  a  sliidy  of  Johnny 
and  /jHiwi)',  .Appleton-Century,  1935,  pp.  156-157.] 


Maturation  of  Ability  to  Learn 


81 


Johnny,  one  of  the  twins,  was  regularly 
exercised  in  motor  abilities,  while  his  twin, 
Jimmy,  was  kept  in  a  crib  in  the  laboratory 
during  the  day.  The  two  were  compared 
with  each  other  and  with  sixty-eight  other 
children.  This  study  showed  that  the  be- 
havior which  every  child  must  ac(|uire  in 
order  to  act  as  a  biologically  normal  hu- 
man being  is  not  markedly  modified  by  op- 
portunity for  practice.  Maturation  alone 
seems  to  take  care  of  such  responses.  Spe- 
cialized skills,  on  the  other  hand,  are  de- 
pendent on  practice.  Actually,  Johnny, 
the  exercised  twin,  continued  all  the  way 
up  to  ten  years  of  age  to  show  greater  mus- 
cular skill  than  his  brother  who  received 
relatively  little  practice  during  the  first  two 
years  of  life.  (See  Fig.  35.)  Human  skills, 
unlike  swimming  of  salamander  larvae, 
depend  on  much  more  than  inheritance. 
A  good  coach  is  an  important  factor  in  the 
success  of  a  team. 

This  experiment,  taken  with  the  others, 
seems  to  show  that  the  exercise  of  a  be- 
havior before  its  maturation  is  finished 
does  no  more  than  hasten  the  maturation. 
It  can  act  in  one  or  both  of  two  ways. 
Exercise  increases  the  growth  and  thus  the 
strength  of  the  muscles  involved.  That  is 
one  way  in  which  exercise  could  hurry 
maturation.  It  is  also  conceivable  that 
exercise  hastens  the  integration  of  a  neuro- 
muscular pattern.  In  either  case  exercise 
woidd  be  doing  little  more  than  time  alone 
would  accomplish  in  completing  the  nia- 
turation.  Furthermore  it  seems  clear  that, 
if  there  is  any  learning  as  a  result  of  exer- 
cise, it  affords  little  profit  in  so  far  as  man's 
basic  and  fundamental  acts  of  behavior  are 
concerned.  In  the  acquisition  of  special- 
ized skills,  on  the  other  hand,  learning  is 
necessary,  and  what  Johnny,  the  exercised 
twin,  had  learned,  together  with  his  greater 


strength,  txjjjains  his  superiority  over  his 
brother. 

Since  learning  itself  dejjeiids  upon  matu- 
ration, individual  differences  in  the  rate 
of  maturation  create  individual  difierences 
in  the  capacity  to  learn.  Children  who 
matuie  earlier  (an  learn  specific  skills 
earlier.  Some  infrahuman  animals  of  a 
given    age    can    learn    more    cjuickjy    than 


I  IGURE   36.      CHIMPANZEE  AND   HUMAN   INFANT   OF 
ABOUT  THE    SAME   AGE 

For  two  and  a  half  years  this  chimpanzee  lived  in 
a  human  family  with  two  children,  one  of  them 
about  its  own  age.  (See  also  Fig.  216,  p.  451.) 
[From  R.  M.  Yerkes,  Chimpanzees:  a  laboratory 
colony,  Yale  University  Press,  1943,  p.  191.1 

human  children  of  the  same  age  those 
forms  of  behavior  that  are  common  to  both, 
simply  because  the  child  matures  more 
slowly. 

There  is  an  interesting  example  of  this 
difference.  A  human  infant  and  a  cliim- 
panzee  infant  of  about  the  same  age  were 
brought  together  in  the  human  child's 
home.  (See  Fig.  36.)  Both  ^vere  treated 
exactly  alike.  Each  was  fondled,  kissed  as 
he  went  to  sleep  and  pimished  in  the  same 
way.  Because  tlie  chimpanzee  matured 
more  rapidly,  he  outdistanced  his  human 
companion     in     many    ways.      At     Iwehc 


82 


Growth  and  Devehpmenf 


months  the  chimpanzee  could  respond  to 
twenty  verbal  commands  such  as  "Open  the 
door"  and  "Shake  hands,"  but  the  human 
child  could  respond  to  only  three.  In  con- 
trol of  bowels  and  bladder  and  in  other 
skills  the  chimpanzee  was  superior  to  the 
child.  The  chimpanzee  learned  better  to 
use  a  spoon  and  to  drink  from  a  glass.  In 
general,  at  one  year  of  age  the  chimpanzee 
could  do  better  with  a  problem  of  learn- 
ing than  the  child.  This  finding  means 
simply  that  the  physiological  basis  for 
learning  had  matured  earlier  in  the  ape 
than  in  the  child.  No  ape,  however,  reared 
in  human  or  other  environment,  has  ever 
acquired  the  advanced  use  of  language  or 
of  the  other  symbols  that  are  basic  to  man's 
mental  life.  When  the  centers  of  the  hu- 
man brain,  which  are  essential  in  the  use 
of  language  and  other  symbolic  processes, 
finally  mature,  a  new  kind  of  learning,  not 
possessed  by  any  organism  other  than  man, 
becomes  available.  At  this  stage  of  matura- 
tion the  human  child  soon  outdistances 
all  his  animal  competitors.  (For  other  de- 
tails of  this  experiment,  see  p.  451.) 

Maturation  of  Speech  and  Language 

Speech  implies  both  vocalization  and 
symbolization— the  production  of  sounds 
and  their  use  as  symbols.  Both  functions 
depend  on  learning,  and  both  recjuirc  the 
development  of  the  higher  brain  centers 
before  progress  with  respect  to  them  can 
be  made. 

Vocalization  consists  in  the  coordination 
of  the  nerves  and  muscles  which  control 
movements  of  the  throat,  palate,  tongue, 
lips  and  the  lower  jaw.  Separately,  as  re- 
flexes, all  these  movements  are  present  at 
birth,  and  all  are  at  least  partially  coordi- 
nated in  the  infant's  first  cry.  The  birth 
cry  of  the  human  infant  has  siipcrstitiously 
been  regarded  from  early  times  as  having 


symbolic  significance.  It  is,  however,  only 
a  reflex  which  results  from  a  stimulation 
of  receptors  and  a  coordination  of  groups 
of  motor  nerves  in  the  medulla  of  the 
brain.  For  example,  when  the  contraction 
of  the  walls  of  the  empty  stomach  stimu- 
lates the  receptors  there,  the  baby  cries. 
The  cry  has  no  symbolic  significance  what- 
ever to  the  baby  although  to  its  nurse  it 
means  "the  baby  is  hungry."  Crying  is 
not  necessarily  speech. 

The  coordination  of  the  motor  nerves 
necessary  for  speech  occurs  in  the  cortex  of 
the  brain  in  an  area  that  is  called  the 
speech  center.  This  coordination,  the  in- 
tegration of  the  nerves  to  the  various  mus- 
cles of  the  throat  and  mouth,  is  sufficiently 
matured  by  the  sixth  or  seventh  month 
after  birth  to  make  possible  the  beginning 
of  learning  to  talk.  At  this  time  the  child 
begins  to  babble.  Babbling  consists  in  the 
automatic  production  of  meaningless  syl- 
lables; they  are  variable  in  sound,  but 
generally  the  same  syllable  is  repeated  a 
number  of  times.  The  child  hears,  of 
course,  the  sounds  of  its  own  voice  and 
apparently  finds  the  experience  pleasur- 
able. Babbling  is  a  period  of  practice  in 
enunciation,  particularly  in  the  use  of  the 
tongue  and  lips.  It  has  been  said  that 
before  the  period  ends  all  the  sounds  are 
produced  which  occur  in  any  language. 
This  statement  docs  not  mean  that  the 
child  can  at  will  enunciate  any  speech  sound 
that  he  hears  and  wislies  to  imitate.  He 
needs  much  practice  before  he  can  com- 
mand the  sounds  of  his  mother  tongue. 

When  vocalization  has  become  possible, 
then  symbolization  can  follow.  The 
sounds  can  acquire  meanings.  Symboliza- 
tion is  created  by  learning  and  the  build- 
ing up  of  conditioned  responses.  Since  this 
process  is  discussed  in  a  later  cliaplcr  (pp. 
51H  f.),  we  need  not  consider  it  here. 


Adolescence,  Adulthood  and  Old  Age 


83 


When  a  vocalized  sound  has  acquired  a 
meaning,  it  has  become  a  word.  A  reper- 
toire of  words  is  a  -(incnbulary.  At  first  the 
child  accjuires  a  vocabulary  but  slowly. 
When  twelve  months  old  he  can  usually 
respond  to  his  own  name  and  to  two  or 
three  other  words.  At  fifteen  months  he 
may  know  half  a  dozen  more  words;  at 
eighteen  months,  twenty  to  (ilty  words. 
When  he  discovers  that  all  objects  have 
names,  an  event  which  occurs  during  his 
second  year,  his  progress  becomes  much 
more  rapid.  By  the  beginning  of  his  third 
year  he  will  have  learned  some  three  hun- 
dred words.  There  can  be  no  doubt  that 
every  one  of  these  advances  in  his  learn- 
ing is  preceded  by  a  new  stage  of  matura- 
tion, some  new  coordination  or  integration 
that  occurs  in  the  cerebral  cortex. 

ADOLESCENCE,    ADULTHOOD 
AND    OLD    AGE 

The  period  from  adolescence  to  old  age 
may  be  four  times  as  long  as  the  period 
from  conception  to  adolescence,  but  it  does 
not  include  nearly  so  much  change.  The 
adult  reaches  the  height  of  his  powers  I)ut 
slowly,  and  thereafter  declines  but  slowly. 

Puberty  and  Adolescence 

Adolescence  is  the  period  of  some  eight 
or  ten  years  dining  which  the  human  in- 
dividual develops  from  childhood  to  adult- 
hood. The  period  is  characterized  by  pu- 
bescence, the  beginning  of  the  procreative 
functions.  It  is  the  maturation  of  a  com- 
plex mechanism  which  includes  the  sex 
glands,  the  external  sexual  organs  and  parts 
of  the  nervous  system.  The  chronological 
age  at  which  puberty  begins  is  variable;  it 
may,  however,  be  expected  dining  the  thir- 
teenth year  in  girls,  and  the  following  year 
in  boys,  and  is  generally  regarded  as  estab- 


lished at  the  first  menstruation  in  girls  and 
at  the  appearance  of  pubic  hair  in  fwys. 
The  common  belief  that  puberty  is  reached 
early  in  tropical  countries  is  not  borne  out 
by  careful  study.  Ciirls  in  the  United 
States  reach  sexual  maturity  on  the  aver- 
age as  early  as  any  group  that  has  ijcen 
scientifically   studied. 

A  second  characteristic  of  adolescence  is 
the  rapid  increase  in  the  growth  and  de- 
velopment of  the  individual.  As  we  have 
seen  in  the  curve  of  the  general  type  of 
growth  in  Fig.  30  (p.  73),  the  period  be- 
gins during  the  eleventh  year  and  the  curve 
begins  to  flatten  out  about  the  sixteenth 
year,  although  it  will  continue  to  rise  bv 
smaller  increments  beyond  the  twentieth 
year.  The  change  thus  begins  before  pu- 
berty, and  it  commences  earlier  in  girls 
than  in  boys,  with  the  result  that,  although 
tliroughout  childhood  the  boy  has  on  the 
average  been  taller  and  heavier  than  the 
girl  of  the  same  age,  from  the  eleven tli 
to  the  fourteenth  year  this  relation  is  re- 
versed. Thereafter  the  boy  will  resume 
his  superiority  in  this  respect.  We  have 
also  seen  that  the  sex  glands  and  all  the 
internal  and  external  sexual  organs  begin 
a  period  of  rapid  growth  at  about  the 
twelfth  year,  starting  at  least  a  year  earlier 
in  girls  than  in  boys. 

This  growth  results  not  only  in  an  in- 
crease in  height,  weight  and  the  maturation 
of  the  sexual  organs,  but  also  in  changes 
in  the  relative  proportions  of  the  head,  the 
legs  and  arms,  the  trunk  and  the  features 
of  the  face.  Other  changes  are  the  second- 
ary sexual  characters  noted  previously.  In 
a  boy  these  changes  are  the  starting  of  the 
beard  and  hair  on  odier  parts  of  the  bodv 
and  a  lowering  of  the  pitch  of  the  voice, 
which  sometimes  amounts  to  as  much  as  an 
octave.  In  a  girl,  the  voice  drops  onlv 
slightly   in   pitch   and  she   develops   pubic 


84 


Growth  and  Development 


hair  and  the  soft  downy  hair  on  her  face. 
There  is  also  a  widening  of  the  pelvis  and 
a  consequent  broadening  of  the  hips  and 
the  development  of  the  breasts. 

A  third  characteristic  of  adolescence  is 
the  appearance  of  an  increased  emphasis 
upon  certain  previously  existing  interests 
and  attitudes.  The  adolescent  begins  to 
be  concerned  about  the  other  sex,  and  in 
romance  and  sexual  matters.  He  feels  a 
heightened  self-consciousness,  realizes  more 
fully  his  position  in  the  social  group  in 
which  he  moves.  He  gains  a  greater  de- 
sire for  independence  and  a  tendency  to 
resist  parental  direction.  The  girl,  in  par- 
ticular, may  become  critical  of  her  mother's 
dress  and  the  way  she  does  her  hair.  Both 
boys  and  girls  acquire  new  attitudes  toward 
social,  economic  and  religious  ideas  which 
they  formerly  accepted  without  thought, 
but  which  now  they  question,  at  times 
with  intolerance.  Because  he  is  still  in- 
experienced the  adolescent  often  says  and 
does  many  things  that  he  will  later  regard 
as  radical  or  ill  advised. 

For  many  individuals  this  period  is  diffi- 
cult. The  adolescent  has  so  many  new 
adjustments  to  make.  He  yearns  for  action, 
but  his  goals  are  not  yet  clear.  Nor  does 
he  yet  know  that  his  problems  are  char- 
acteristic of  the  period  through  which  he  is 
passing  and  that  time  alone  will  bring 
their  solution. 

Adulthood 

There  are  wide  individual  differences  in 
the  chronological  age  at  which  the  adoles- 
cent period  ends.  It  ends  earlier  in  women 
than  in  men,  and  within  a  sex  it  happens 
earlier  in  some  persons  than  in  others.  It 
may  be  said  to  be  all  over  by  the  age  of 
twenty-five.  By  that  time,  as  we  have  seen, 
the  organism  has  practically  completed  its 
growth— only   the  skin,   the  nails  and   the 


hair  continue  to  grow.  Repair,  however, 
will  still  go  on. 

When  all  matmation  has  come  to  an  end, 
the  normal  individual  does  everything  that 
all  normal  members  of  the  human  race  do. 
His  neuromuscidar  growth  and  develop- 
ment, however,  are  now  such  that  he  may 
learn  to  do  many  other  things.  His  rate 
of  metabolism  is  high;  he  has  great  stores 
of  energy;  he  fatigues  slowly  and  recuper- 
ates quickly.  For  this  reason  he  is  able 
to  do  more  and  harder  work  with  fewer 
ill  effects  than  at  any  other  time  in  his 
life.  He  has  presumably  decided  on  his 
life's  work— his  trade,  business  or  profes- 
sion. His  formal  education  is  finished,  and 
his  apprenticeship  or  professional  training 
is  nearly  completed.  The  end  of  matura- 
tion is,  therefore,  the  beginning  of  another 
period,  the  period  of  adulthood,  which 
may  last  for  thirty-five  or  forty  years,  while 
the  individual  rears  a  family,  masters  a 
trade  or  profession  and  otherwise  plays 
the  part  of  a  mature  person  in  the  culture 
to  which  he  belongs. 

The  first  twenty  years  of  adulthood  are, 
however,  the  most  productive.  A  study 
of  the  recorded  achievements  of  one  thou- 
sand historically  eminent  persons  showed 
that  about  a  third  of  their  best  work  was 
done  between  the  ages  of  thirty  and  forty, 
and  seventy  per  cent  of  it  before  the  forty- 
fifth  year.  The  causes  for  this  difference 
must  be  very  complex.  The  younger  adult 
has  more  endiuance;  he  can  work  harder 
and  longer.  He  has  higher  motivation  tc 
work,  not  only  because  of  his  need  to  make 
a  living  for  himself  and  his  family,  but  also 
because  he  feels  competition  with  his  fel- 
lows more  keenly  when  he  is  at  the  thresh- 
old of  his  career.  It  is  not  clear  whether 
besides  endurance  and  motivation  there 
is  something  else  that  makes  young  animals 
and  young  people  and  younger  adults  more 


Adulthood 


85 


active,  more  aggressive,  iriore  ciithusiasiic, 
more  'energetic'  than  they  will  be  later  in 
life.  It  is  certainly  true  that  younger  ani- 
mals and  persons  expend  effort  more  read- 
ily than  older  ones.  What  happens  seems 
to  be  that  this  'energy'  diminishes  with  age 
while  wisdom  and  skill  increase,  with  the 
result    that    maximal    effectiveness    occurs 


I    I    I    I   '    I    I    I    '    I   I    I    I 
-Pursuit  reaction 


eg       CO       ^       in       i£> 

Age  in  semidecades 

FIGURE    37.       SPEED    OF    RESPONSE    TO    STIMULI    AT 
VARIOUS    AGES 

Many  other  human  functions  follow  similar 
curves.  See  also  Fig.  30.  [After  W.  R.  Miles,  Proc. 
Nat.  Acad.  Sci.,  1931,  17,  631.] 

for  human  beings  in  an  intermediate  dec- 
ade around  forty.  There  is  possibly  also  a 
third  effective  factor:  creative  work  in 
older  adults  becomes  more  difficult  because 
society  makes  more  demands  upon  older 
responsible  people  and  seeks  oftener  to  de- 
termine their  activities.  For  instance,  great- 
ness, once  achieved,  may  bring  about  its 
own  limitation,  for  it  takes  time  and  is 
fatiguing  to  play  the  role  of  a  famous 
person. 

The  high  tide  of  muscular  strength,  en- 
durance and  speed  of  action  at  first  re- 
cedes slowly  and  then,  as  the  years  go  on, 
more  rapidly.  The  professional  baseball 
player,  particularly  the  in-fielder,  is  fre- 
quently said  to  be  an  old  man  at  thirty  to 


tliirty-seven  years  of  age.  He  no  longer 
lias  the  blinding  speed  necessary  to  play 
his  position  with  his  former  skill.  Experi- 
ments also  show  that  the  speed  ol  various 
movements  of  the  hand,  fingers  and  fool 
reaches  its  peak  just  before  or  soon  after 
the  twentieth  year,  and  within  the  next 
decade  begins  a  decline  which  continues  for 
the  remainder  of  life.  The  curves  of  some 
of  these  results  are  shown  in  Figs.  37  and 
38. 

After  the  forty-fifth  year  other  decre- 
ments which  at  first  were  so  small  as  to  be 
unnoticed  begin  to  be  bothersome.  The 
individual  finds  that  his  hearing  is  not  so 
good  as  it  was;  he  can  no  longer  hear  very 
high  tones  like  the  chirp  of  the  cricket,  and 
he  frequently  misses  a  word  in  a  conversa- 
tion.    He  discovers  also  that,  although  he 


Digital  extension -flexion  speed 


in      vD 
Age  in  semidecades 

FIGURE    38.       MOTILITY    AT    \ARIOLS    AGES 

See  also  Fig.  37.     [.After  AV.  R.  Miles.  Pioc.  Xiit. 
Acad.  Sci.,  1931,  17,  629.] 

can  still  see  distant  objects,  he  cannot  fo- 
cus his  eyes  to  near  objects  as  \\ell  as  for- 
merly. His  memory  too  is  often  bother- 
some. At  times  he  cannot  recall  proper  and 
place  names  that  are  perfectly  familiar.  His 
immediate  memory  is  bad.  For  example,  lie 
may  look  up  a  telephone  niunber  and  dien 
forget  it  before  he  puts  in  his  call.     He 


86 


Growth  and  Development 


has  trouble  also  in  renicinbering  tacts  that 
belong  to  a  field  which  is  unfamiliar.  On 
the  other  hand,  he  may  recall  with  fidelity 
the  details  of  events  that  happened  many 
years  earlier,  as  well  as  new  facts  in  a 
familiar  field. 

As  a  man  grows  older  there  is  a  decided 
shift  in  his  interests  and  attitudes.  He 
cares  less  for  physical  activity,  and  he  gradu- 
ally gives  up  those  forms  of  sport  that  rc- 
(juire  strength,  speed  and  endurance.  If 
he  continues  to  play  tennis,  he  no  longer 
tries  to  cover  the  coiut;  instead  he  tries 
to  win  by  strategy  and  gieater  accuracy. 
If  he  plays  golf,  he  is  satisfied  with  nine  or 
l^erhaps  six  holes;  and,  if  he  defeats  his 
younger  opponent,  it  is  through  accuracy 
rather  than  distance.  As  observer,  how- 
ever, his  interest  in  sports  increases.  He 
does  not  care  so  much  for  dancing  or  the 
cinema  as  younger  persons  do.  The  statis- 
tical studies  show  also  that  he  has  an  in- 
creased interest  in  his  home,  in  art  gal- 
leries, in  his  chinch  and  in  his  clubs. 

The  least  diminution  with  advancing 
years  occurs  in  those  human  activities  that 
depend  less  upon  muscle  and  more  upon 
brain.  For  example,  tests  of  the  kind  of 
imagination  which  sees  objects  in  the 
clouds  or  in  ink  blots  show  that  there  is 
little  decline  with  age.  Moreover,  tests  of 
comparison  and  judgment  in  which  speed, 
inmiediate  memory  or  recall  of  unfamiliar 
material  are  not  involved,  reveal  that  the 
older  person  does  just  about  as  well  as  the 
yoimger.  On  the  whole,  skill  in  verbal 
association,  interpretation  of  meaning, 
generalization  and  the  finding  of  relations 
resists  the  influence  of  age.  Thus  it  comes 
about  that  the  older  man,  provided  he  has 
escaped  the  hardening  efi^ect  of  habit,  be- 
comes a  valued  counselor;  his  long  and 
varied  experience  renders  his  judgments 
more  objective  and  impartial  and  gives  his 


opinions  greater  breadth  and  perspective. 
Thus  he  finds  compensation  for  the  physi- 
cal disabilities  that  overtake  him. 

Old  Age 

The  period  of  old  age  is  called  senes- 
cence. There  is  no  particidar  time  at 
which  senescence  can  be  said  to  begin. 
Ihe  process  of  aging,  like  the  process  of 
maturing,  is  continuous  and  the  two  kinds 
of  change  are  often  just  the  obverse  and 
re\'erse  of  the  same  process.  Actually  aging 
begins  as  soon  as  the  ovimi  is  fertilized. 
When  the  prenate,  two  weeks  after  devel- 
opment has  started,  passes  from  the  germi- 
nal period  to  the  embryonic  period,  its 
cells  undergo  a  change.  At  first  they  are 
what  is  called  iotipolent:  any  cell  could 
develop  into  a  whole  individual  or  into 
any  of  the  kinds  of  tissue  of  which  the  in- 
dividual is  composed.  Then  the  cells 
change,  acquiring  special  fimctions,  and  it 
is  no  longer  possible,  for  example,  to  get  a 
nerve  cell  from  a  cell  destined  to  be  mus- 
cle. This  specialization  is  a  stage  of  ma- 
turation, but  it  is  also  a  stage  of  prenatal 
aging.  For  the  gain  in  special  potency 
there  had  to  be  a  loss  in  general  potency. 
Senescence  can  be  regarded  simply  as  the 
ultimate  maturity  when  the  losses  have  be- 
come more  noticeable  than  the  gains. 

Man  does  not  grow  old  at  the  same  rate 
all  over.  His  vital  organs,  his  glands,  his 
bones  and  muscles,  his  senses  and  his  psy- 
chological abilities  age  at  different  rates. 
It  is  only  after  a  long  time,  somewhere  be- 
tween the  ages  of  fifty  and  seventy-five,  that 
all  these  symptoms  combine  to  make  up  the 
picture  of  true  old  age.  It  may  be  even 
later  before  we  find  the  extreme  picture  of 
age— the  tottering  step,  the  trembling 
hands,  the  filmed  and  watery  eyes,  the  flut- 
tering heart,  the  wrinkled  skin,  the  extreme 
forgetfulness.     Even  then  the  old  man  has 


The  Trajectory  of  Life 


87 


not  lost  his  usefulness  to  society  if  liis  diIikI 
remains  clear.  He  needs  to  resist  the  tend- 
ency to  withdraw  into  himself,  to  nurse  his 
growing  infirmities,  and  thus  lo  becoinc 
solitary. 

Postmortem  studies  show  tliat  all  the 
structuies  of  the  body  have  degenerated  in 
old  age.  Nearly  all  (he  inlernal  organs 
and  glands  are  alropliicd  and  decreased  in 
si/e.     The  niusdcs  are  slioi    ilirougii   wiili 


itstif,  and  whidi,  il  ii  progresses  far  enough, 
may  result  in  senile  dementia,  a  form  of 
irunlal  disorder  which  sometimes  occurs  in 
the  very  old.  Personality  changes  at  vari- 
ous ages  of  the  individual  are  discussed  in  a 
later  chapter  (pp.   505-509). 

The  Trajectory  of  Life 

The    course    of   Inirn.iii    life    througlioul 
lis  ages  has  been  likened   lo  the  trajectorv 


FICURK    39.       BRAINS   OF   OLD   PF.OPI.E 

(n)  Small  segment  of  the  cerehial  cortex  Avith  co\eiiug  membranes  removed.  The  deep  wide  fissures 
result  from  atrophy  of  the  brain,  common  in  senility.  This  brain  weighed  only  1000  grams,  whereas 
the  average  normal  braiir  weighs  al)out  1300  grams,  (h)  Cross-section  of  one  hemisphere  of  brain,  show- 
ing in  the  center  a  large  hemorrhage,  such  as  often  occurs  in  older  people  as  a  result  of  arteriosclerosis. 


fibrous  tissue  losing  their  elasticity  and 
contractility.  The  cartilages  are  stiffened 
with  deposits  of  lime.  The  arteries  are 
hard  and  inelastic,  a  condition  (arterio- 
sclerosis) which  results  from  a  cellular 
change  in  the  walls  of  the  arteries,  mak- 
ing it  more  difficult  for  the  heart  to  force 
idood  into  the  small  capillaries  of  the  brain, 
and  thus  depriving  the  brain  of  the  needed 
food  and  oxygen.  (See  Fig.  39.)  Some- 
times, under  high  blood  pressure,  the  blood 
vessels  in  some  region  of  the  brain  burst, 
resulting  in  a  'stroke'  (apoplexy),  a  partial 
paralysis.  There  is  another  kind  of  sclero- 
sis which  is  a  degeneration  within  the  brain 


of  a  bullet  fired  from  a  gun.  The  bullet 
first  shoots  upward  and  forward  after  leav- 
ing the  gun,  then  le\els  off  and  eventually 
drops  again  to  the  earth.  It  is  eas)  to  see 
the  analogy.  From  the  moment  of  the 
fertilization  of  the  egg  until  the  end  of 
adolescence  there  is  an  increase  in  size,  in 
jDhysical  strength  and  encUirance,  in  motor 
responses,  in  sensory  capacity,  in  'intelli- 
gence.' Ultimately  a  peak  is  reached  at 
which  the  individual  is  at  his  best  average 
in  these  respects.  Then  decline  begins, 
at  first  very  slowly  and  then  more  rapidly 
until  death  is  reached  in  extreme  old  age. 
This   picture   of    the    course   of   human 


88 


Growth  and  Development 


life  is  useful  because  it  brings  into  bold 
relief  an  important  triuh.  Notwithstand- 
ing the  complexity  of  the  comse  of  growth 
and  development  Avhich  has  been  re- 
counted in  this  chapter— the  fact  that  every 
structure  of  the  body  has  its  own  rate  of 
growth  and  dexelopment,  the  fact  that  the 
maturation  of  the  various  structures  and 
forms  of  behavior  occurs  at  different  times 
and  yet  all  are  about  at  their  best  when 
life  is  at  its  peak,  the  fact  that  the  decline 
of  the  various  psychological  abilities  is  not 
imiform— notwithstanding  these  complexi- 
ties, the  course  of  life,  regarded  as  a  whole, 
is  first  an  evolution,  then  a  continuation 
and  then  an  involution  This  is  the  basic 
life  pattern  of  other  living  things,  and, 
since  man  also  conforms  to  it,  the  plan  of 
his  life  course  must  surely  have  been  laid 
down  in  heredity  and  directed  by  his  genes. 
The  wide  individual  variation  in  the  chron- 
ological ages  at  which  the  several  life  pe- 
riods are  reached  is  not  surprising.  The 
mar\elous  timing  of  the  genes  is  not  done 
with  respect  to  any  astronomical  calendar. 
The  calendar  of  the  genes  is  physiological, 
and  some  racial  strains  are  longer  lived 
than  others. 

Finally,  it  may  be  said  that  the  task  of 
heredity  is  finished  only  when  it  brings  the 
organism  to  the  peak  of  its  powers  and  has 
enabled  it  to  reproduce  and  rear  its  kind. 
What,  in  addition,  man  makes  of  his  life, 
he  does  on  his  own  initiative  in  relation 
to  the  social  and  other  environmental 
forces  which  bear  in  upon  him.  What  his 
resources  are  and  what  means  he  employs 
are  set  forth  in  subsequent  chapters  of  this 
book. 

REFERENCES 

1.  Brooks,  F.  D..  and  Shaffer,  L.  F.  Child  psy- 
chology. Boston:  Hoiighloh  Mifflin,  1937. 
Ctiap.  7. 


A  student  tcxtlioolc  whicli  reviews  and  in- 
terprets tlic  scientific  literattne  in  its  field. 

2.  Cannicliaei.  L.  (Ed.)  Manual  of  child  ps\- 
choloffy.     New  York:   Wiley,   1946. 

An  ad\anced-level  book  on  developmental 
psycliologv'  by  nineteen  experts.  Excellent  bib- 
liographies. 

3.  Cowdry,  E.  V.  (Ed.)  Problems  of  ageing.  (2nd 
ed.)  Baltimore:  Williams  and  ^Vilkins,  1942. 
Especially   Chap.   28. 

A  general  book  in  a  new  field,  including  an 
excellent  chapter  on  psychological  aspects  by 
Walter  R.  MHes. 

4.  Dewey,  E.  Behavior  development  in  infants:  a 
survey  of  the  literature  on  prenatal  and  post- 
natal activity,  1920-1934.  New  York:  Columbia 
University  Press,  1935. 

A  source  book  which  gives  a  summarv  of 
scientific  literature,  some  of  which  was  previ- 
ously available  only  in  obscure  journals. 

5.  Gerard,  R.  W.  The  body  functions:  physi- 
ology.    New  York:  Wiley,  1941.    Chap.  11. 

An  excellent  general  summary  which  in- 
cludes consideration  of  the  phvsiology  of  de- 
velopment. 

6.  Gesell,  A.,  and  Amatruda,  C.  S.  Developmen- 
tal diagnosis:  normal  and  abnormal  child  de- 
velopment.    New  York:  Hoeber,  1941. 

A  basic  description,  trait  by  trait,  of  typical 
and  atypical  early  human  development. 

7.  Gesell,  A.,  and  Amatruda,  C.  S.  The  embry- 
ology of  behavior.     New  York:  Harper,  1945. 

A  general  consideration  of  the  growth  of  be- 
havior discussed  as  the  anatomist  considers  the 
growth  of  structure. 

8.  Gilbert,  M.  S.  Biography  of  the  unborn. 
Baltimore:   Williams  and  Wilkins,  1939. 

A  somewhat  popular  description  of  some  as- 
pects of  prenatal  life. 

9.  Hollingworth,  L.  S.  The  psychology  of  the 
adolescent.    New  York:  Appleton-Century,  1928. 

A  wise  treatment  of  a  difficult  period  of 
human  development  bv  a  scientifically  minded 
woman  psychologist. 
10.  Kellogg,  W.  N.,  and  Kellogg,  L.  A.  The  ape 
and  the  child:  a  study  of  environmental  in- 
fluence upon  early  behavior.  New  ^'ork:  Mc- 
Graw-Hill,  1933. 


References 


89 


A  detailed  study  of  a  cliimpanzce  :ind  a  liu- 
man  infant  reared  together  in  a  liiiiiiaii  home. 

11.  McGraw,  M.  B.  Growth:  a  sludy  of  Johnny 
and  Jimmy.  New  York:  A|j|jlcloii-Ceiitury, 
1935. 

An  elaborate  experiment  on  twins,  one  of 
whom  was  given  much  exercise  while  the  other 
was  kept  relatively  quiet. 

12.  Miles,  W.  R.  Age  and  human  society.  In  C. 
Murchison  (Ed.) ,  A  handbook  of  social  psy- 
chology. Worcester,  Mass.:  Clark  University 
Press,  1935.     Chap.  15. 

An  excellent  summary  of  the  psychological 
factors  that  are  important  in  human  aging. 

13.  Munn,  N.  L.  Psychological  development:  an 
introduction  to  genetic  psychology.  Boston: 
Houghton  Mifflin,   1938. 

A    sinnmary    of    the    psychology    of    develop- 


jr)(iii    uiih  due  reference  to  relevant  liiolo^ical 
facts. 

H.  Scammon,  R.  E.  The  measurement  of  the  IxmK 
in  childhood.  The  measurement  of  man.  .Min- 
neapolis: University  of  .Minnesota  I'rc-ss,  1930. 
Chap.  4. 

Facts  and  generalizations  concerning  the 
measurement  of  human  growth  in  childhof>d. 

15.  Warthin,  A.  S.  Old  age:  the  major  involution. 
New  York:    I'aul  B.  Hoeher,  1929. 

A  general  book  wiili  special  reference  to 
medical  problems. 

16.  Windle,  W.  !•'.  Physiology  of  the  fetus:  origin 
and  extent  of  function  iii  prenatal  life.  Phila- 
delphia: Saunders,  1940. 

An  excellent  summary  of  the  physiological 
functions  of  the  mammalian  and  human  fetuses 
before  birth. 


CHAPTER 


Feeling  and  Emotion 


FEW  areas  of  human  experience  and  be- 
havior are  as  vital  and  interesting  to  the 
individual  as  his  feelings  and  emotions. 
They  occur  in  situations  of  special  impor- 
tance to  him,  when  his  interest  is  aroused, 
his  attention  held,  and  his  energy  increased 
and  directed  toward  a  definite  goal.  They 
range  from  the  milder  feelings  which  we 
call  pleasantness  and  unpleasantness  to 
stronger  emotions  like  fear  and  anger.  We 
do  not  know  what  the  exact  relationship 
may  be  between  the  affective  states,  as 
pleasantness  and  unpleasantness  are  called, 
and  the  stronger  emotions,  but  this  we  do 
know:  they  both  involve  general  reaction 
attittides  of  the  organism  toward  something 
in  its  environment. 

PLEASANTNESS    AND 
UNPLEASANTNESS 

Pleasantness  and  unpleasantness,  referred 
to  either  as  afjeclive  stales  or  as  Jiedonic 
tone,  correspond  to  broad  attitudes  of  ac- 
ceptance or  rejection  that  the  organism 
assumes  toward  various  aspects  of  its  en- 
vironment. Pleasant  things  are  the  things 
that  we  like,  that  we  desire  and  seek  to  ob- 
tain. Pleasant  situations  are  ones  that  we 
attempt  to  maintain  and  prolong.  Un- 
pleasant things  arc  not  liked.     We  strive 


to  avoid  them.     Unpleasantness  is  a  condi 
tion  which  we  try  to  terminate. 

In  one  sense,  pleasantness  and  unpleas- 
antness may  be  said  to  be  indicators  of  the 
organism's  normal  reaction  tendencies  to- 
ward stimulus  objects.  This  interpretation 
is  supported  by  laboratory  experiments 
which  show  that  under  conditions  where 
movement  by  the  subject  is  not  possible, 
pleasant  stimuli  lead  to  muscidar  relaxa- 
tion, and  unpleasant  ones  to  musciUar  ten- 
sion. Where  movement  by  the  stibject  is 
possible,  where  he  sits  unrestrained  and  the 
stimulus  moves  past  him,  pleasant  stimuli 
prodtice  movements  of  his  approach  to  the 
stimulus,  and  unpleasant  ones  movements 
of  his  withdrawal.  The  actual  behaviors 
involved  in  such  acceptance  or  rejection 
vary  from  situation  to  situation,  and  from 
individual  to  individual,  and  resemble  one 
another  only  in  this  one  common  charac- 
teristic, that  they  are  designed  to  continue 
or  to  remove  the  source  of  stimulation. 

Affective  Value  of  Stimuli 

Because  pleasantness  and  unpleasantness 
serve  as  indicators  of  the  direction  an  in- 
dividual's behavior  will  take,  it  is  impor- 
tant to  know  which  stimuli  are  normally 
pleasant  and  which  unpleasant.  This 
knowledge  should  help  us  in  predicting 
and  controlling  liuman  behavior. 


lliis  tliaplcr  was  jncparcd  by  William  A.  Hunt  of  Nortliwcstcni  Uni\ersity. 

90 


Pleasantness  and  Unpleasantness 


91 


There  is  some  indication  that  pleasant 
stimuli  tend  to  be  those  which  are  of  posi- 
tive biological  value  to  the  individual,  and 
that  unpleasant  stimuli  are  in  general  bio- 
logically harmful.  Thus  the  alkalies,  which 
are  often  poisonous,  are  bitter  and  usually 
unpleasant;  whereas  the  sugars,  which  have 
food  value,  are  sweet  and  nearly  always 
pleasant.  Pain,  which  accompanies  tissue 
damage  or  physiological  disorganization,  is 
notoriously  unpleasant.  The  relationship 
is  not  exact,  for  many  harmful  stimuli  are 
pleasant  and  many  beneficial  ones  unpleas- 
ant. Few  people  relish  the  flavor  of  cod 
liver  oil  although  its  biological  effect  may 
be  desirable;  and  diabetics  continue  to 
crave  the  sugar  which  has  become  bad  for 
them. 

This  biological  interpretation  is  sup- 
ported by  the  relationship  which  exists 
between  affectivity  and  the  intensity  of  the 
stimulus.  In  general,  pleasantness  and  un- 
pleasantness vary  in  direct  relation  to  the 
intensity  of  the  stimulus,  both  the  pleas- 
antness and  unpleasantness  becoming 
greater  as  the  intensity  of  the  appropriate 
stimulus  increases.  In  most  cases,  however, 
there  comes  a  point  beyond  which  an  in- 
crease in  intensity  causes  the  pleasant 
stimulus  to  become  unpleasant.  Thus,  as 
the  concentration  of  salt  in  a  solution  is 
increased,  the  solution  is  at  first  indiffer- 
ent, then  it  becomes  pleasant  as  more  salt 
is  added,  and  finally,  when  the  concentra- 
tion is  increased  beyond  a  certain  point,  the 
solution  becomes  definitely  distasteful  and 
unpleasant.  (See  p.  356.)  The  biological 
importance  of  this  general  rule  of  intensity 
seems  obvious— intense  stimuli  tend  to  be 
dangerous,  and  unpleasantness  acts  as  a 
warning. 

Whatever  the  biological  significance  of 
the  affective  states,  it  is  possible  to  plot 
certain  general  relationships  between  pleas- 


antness and  unpleasantness,  on  the  one 
hand,  and  their  specific  stimulus  condi- 
tions, on  the  other.  Human  beings  show 
broad  resemblances  in  their  preferences. 
For  instance,  they  tend  to  prefer  saturated 
colors  to  unsaturated.  Primitive  peoples 
and  young  children  seem  to  prefer  the 
'warmer'  colors  like  red,  whereas  our  adult 
culture  prefers  the  'cooler'  colors  like  blue. 
Certain  combinations  of  tones  have  differ- 
ent hedonic  value.  The  musical  interval 
of  the  major  third  is  usually  considered 
most  pleasant  and  the  minor  second  least 
pleasant  by  musically  sophisticated  persons. 
Sweet  is  usually  pleasant,  and  fjitter  im- 
pleasant. 

Although  there  is  no  doubt  that  these 
general  tendencies  exist,  we  must  remem- 
ber that  they  are  only  tendencies,  broad 
generalizations  concealing  a  great  amount 
of  individual  variation  among  the  members 
of  the  groups  studied.  Not  only  do  pleas- 
antness and  unpleasantness  change  with 
learning,  but  they  also  depend  on  manv 
other  conditions.  The  breakfast  food  that 
is  so  pleasant  today,  through  monotony 
may  become  vmpleasant  a  few  months  from 
now.  The  favorite  dress  of  ten  years  ago, 
discovered  and  put  on  today,  niav  now 
look  ridiculous. 

The  Relativity  of  Hedonic  Tone 

Not  only  are  pleasantness  and  unpleas- 
antness dependent  on  individual  stimuli, 
but  they  also  are  affected  by  the  relation- 
ships within  a  group  of  stimuli.  If  a  less 
pleasant  stimulus  is  presented  as  one  of  a 
group  of  more  pleasant  stimuli,  its  affec- 
tive value  may  be  enhanced  by  its  inclu- 
sion, as  belonging,  within  tlie  group  of 
more  pleasant  stimuli.  This  change  is 
called  assimilation.  AVhen  vou  really  like 
a  person,  you  may  find  yourself  liking  even 
his  (or  her)  faults.     On  the  other  hand,  if 


92 


Feeling  and  Emotion 


the  less  pleasant  stimulus  is  not  assimilated 
into  the  group,  it  may  seem  even  less  pleas- 
ant or  definitely  unpleasant  by  contrast 
with  the  more  pleasant  stimuli  present. 
This  is  called  afjeciive  contrast.  How 
much  worse  it  is  to  spend  an  hour  with 
the  chap  you  do  not  like  right  after  you 
have  spent  an  hour  with  the  chap  you  do 
like  very  much. 

The  affective  value  of  a  stimulus  also  is 
conditioned  by  the  range  of  stimulus  values 
presented  to  an  individual.  If  we  give  a 
subject  a  series  of  odors  which  covers  a  wide 
range  of  hedonic  tones,  we  can  establish 
which  odors  are  pleasant,  indifferent  or 
unpleasant  to  him.  If  we  now  remove  the 
unpleasant  odors,  and  continue  to  present 
to  him  over  and  over  again  the  indifferent 
and  the  pleasant  ones,  some  of  the  indif- 
ferent ones  gradually  become  unpleasant 
and  some  of  those  previously  less  pleasant 
are  presently  judged  to  be  indifferent.  In 
other  words,  the  subject  rearranges  his  re- 
sponses, spreading  them  over  the  present 
range  of  his  olfactory  experience.  This 
phenomenon,  known  as  affective  equilib- 
rium, is  an  example  of  the  general  prin- 
ciple of  relativity  of  judgment  with  which 
we  are  all  familiar. 

Suppose,  for  example,  a  man  found  the 
food  at  a  given  restaurant  so  extremely  un- 
pleasant that  he  declared  it  the  worst  food 
he  had  ever  eaten.  Subsequently,  if  he  has 
changed  to  a  cheap  boarding  house  where 
the  food  is  even  worse,  it  now  seems  to 
him  that  his  present  fare  is  really  the  worst 
food  he  has  ever  eaten.  Should  he  then 
return  to  the  original  restaurant,  the  food 
there  would  seem  much  better,  just  as  long 
as  he  keeps  remembering  about  the  food 
at  the  boarding  house.  If,  however,  he 
forgets  all  about  the  boarding  house,  the 
food  at  the  restaurant  is  going  to  become 
worse  aa;ain.    To  the  Children  of  Israel  in 


the  wilderness  the  taste  of  the  flesh  pots  of 
Egypt  would  .have  been  very  pleasant. 

The  same  relationships  work  out  at  the 
other  end  of  the  scale.  Our  present  pleas- 
ures fade  before  still  greater  ones;  nor  do 
the  still  greater  ones  long  remain  'still 
greater.'  This  ride  provides  one  of  the 
reasons  why  wealth  does  not  assure  happi- 
ness. There  seem,  nevertheless,  to  be  limits 
to  such  relativity.  Some  stimuli  show 
great  constancy  in  pleasantness  or  unpleas- 
antness. Within  a  wide  range,  however, 
human  beings  do  adjust  their  affective 
values  to  fit  the  experiences  available  to 
them,  and  this  relativity  has  important 
consequences  for  man's  contentment  im- 
der  varied  environmental  circumstances. 

Dependence  of  Learning 
upon  Hedonic  Tone 

Hedonic  tone  depends  upon  learning 
and,  conversely,  learning  in  part  upon 
hedonic  tone.  This  relationship  between 
the  two  has  received  much  attention  in 
educational  psychology.  A  child  who  likes 
candy  learns  to  like  the  aimt  who  gives 
him  candy;  hedonic  tone  depends  upon 
learning.  Similarly,  the  child  learns  the 
multiplication  table  because  the  aunt, 
whom  he  now  likes,  teaches  it  to  him  and 
gives  him  the  pleasiu'e  of  her  approval  as 
a  reward;  learning  depends  upon  hedonic 
tone.  By  such  transfers  of  hedonic  value, 
it  might  be  possible  to  make  a  lover  of 
candy  into  a  mathematician,  provided  cer- 
tain other  capacities  were  available. 

Pleasantness  reinforces  learning,  and  im- 
pleasantness  hinders  it.  For  this  reason 
either  reward  or  punishment  may  be  used 
to  establish  a  learned  response.  Experi- 
ments with  animals  show  that  the  task 
which  is  followed  by  the  greater  reward  or 
by  lesser  punishment  is  the  task  that  is 
learned  most  rapidly  and  effectively.     Fur- 


Emotion 


93 


thcniiore,    reward   or   |nniislinicnl    is    more 
effective  the  more  immediate  it  is. 

Hedonism 

Because  of  the  apparent  importance  of 
affectivity,  or  hedonic  tone,  in  human  mo- 
tivation and  behavior,  it  has  frequently  oc- 
cupied a  prominent  part  in  some  philo- 
sophical systems.  These  theories  have  as- 
sumed that  hedonic  tone  determines  ac- 
tion, a  doctrine  which  is  called  hedonism. 
In  its  various  forms  hedonism  reduces  hu- 
man motivation  to  a  desire  to  seek  pleasure 
and  to  avoid  unpleasantness.  Some  of  the 
theories  base  all  present  action  on  the  part 
played  by  hedonic  tone  in  the  past  when 
the  action  was  learned;  others  hold  that 
action  is  in  direct  accordance  with  present 
hedonic  tone;  still  others  maintain  that 
action  is  determined  by  the  anticipated 
pleasantness  of  the  future. 

These  theories  are  too  naive  to  explain 
adequately  the  complicated  facts  of  human 
behavior.  Hedonic  tone  is  really  not  so 
much  a  determiner  of  human  behavior  as 
it  is  an  accompaniment  and  indicator. 
Pleasantness  indicates  the  existence  of  an 
attitude  of  acceptance  and  unpleasantness 
of  an  attitude  of  rejection. 

Objection  is  often  made  to  this  state- 
ment because  it  implies  that  all  positive 
action  is  pleasant,  whereas  it  is  obvious  that 
man  often  'chooses'  unpleasant  action  or 
action  with  unpleasant  consequences.  Mo- 
rality seems  to  depend  on  his  capacity  so 
to  choose.  Does  the  martyr  like  his  mar- 
tyrdom? Is  it  jaleasant?  That  is  the  he- 
donic paradox. 

This  paradox  arises  because  we  tend  to 
think  of  conflict  situations  in  simple  terms 
as  if  they  were  completely  pleasant  or  com- 
pletely unpleasant.  If  the  martyr  experi- 
ences no  conflict,  perhaps  he  can  march 
to  the  lions  with  joy  at  this  opportunity  to 


glorily  his  laiili,  and  soitiicrs  similarly 
have  been  known  to  go  into  almost  certain 
death  with  enthusiasm  and  without  hesi- 
tation. Such  instances  are,  however,  rare. 
Expectation  of  death  or  pain  normally 
leads  to  unpleasantness  and  the  attitude  of 
rejection,  or,  if  opposed  by  some  other  mo- 
tive, to  a  conflict  and  vacillation  of  accept- 
ance and  rejection.  The  stronger  motive- 
courage  or  fear— is  what  wins  out,  but 
meanwhile  there  has  almost  always  been  a 
fluctuation  of  pleasantness  and  unpleasant- 
ness. 

This  matter,  however,  requires  two  fur- 
ther qualifications.  (1)  Often  the  only 
choice  lies  between  two  unequally  unpleas- 
ant alternatives,  courage  with  danger  versus 
cowardice  with  shame.  The  hero  may  then 
choose  unpleasant  courage  because  it  is  less 
unpleasant  than  very  unpleasant  shame, 
may  choose  it  without  affective'  equilib- 
rium's getting  a  chance  to  turn  the  less 
unpleasant  courage  into  positive  pleasant- 
ness. (2)  Habit,  moreover,  enters  into  these 
equations.  For  instance,  the  purpose  of 
military  discipline  is,  in  part,  to  substitute 
habit  for  choice  when  simple  hedonistic 
preference  would  lead  to  the  wrong  action. 
Undoubtedly  habituated  action  patterns 
have  also  lent  support  to  martyrs. 

EMOTION 

Classed  with  pleasantness  and  unpleas- 
antness under  the  general  heading  of 
feelings  are  such  emotions  as  fear,  anger, 
sorrow,  love,  joy,  laughter.  The  emotions 
resemble  the  affective  responses  in  diat 
both  represent  general  reaction  attitudes  of 
the  organism  and  seem  to  have  special  bio- 
logical significance  for  the  organism.  It  is, 
moreover,  an  affective  state  that  usually 
ushers  in  an  emotion.  As  a  rule  you  feel 
unpleasantness    as    a    prelude    to    feai-    or 


94 


Feeling  and  Emotion 


anger,  pleasantness  as  a  prelude  to  joy  or 
elation.  In  fact,  all  the  emotions  them- 
selves may  be  roughly  classified  as  either 
pleasant  or  unpleasant  experiences.  A£- 
fectivity  is  thus  intimately  connected  with 
emotion. 

The  differences  between  the  emotions 
and  the  affective  responses  are  also  marked, 
in  some  respects  more  marked  than  the  re- 
semblances. The  reaction  attitudes  are 
more  specific  in  the  emotions  than  in  the 
affective  states.  The  general  rejection  that 
belongs  to  unpleasantness  may  be  differen- 
tiated into  actual  flight  in  fear  or  actual 
attack  in  anger.  The  emotional  behaviors 
themselves  are  more  forceful,  more  ex- 
treme; they  involve  more  of  the  body  and 
involve  it  in  a  greater  intensity  of  response. 
Attended  by  great  feelings  of  excitement, 
they  disorganize  and  disrupt  other  behav- 
ior patterns  of  the  moment.  We  speak  of 
being  'engulfed,'  'overwhelmed'  or  'swept 
away'  by  emotion.  We  have  only  to  re- 
member the  difference  between  disliking  a 
person  and  being  angry  at  him  for  the  dis- 
tinction between  feeling  and  emotion  to  be 
clear. 

The  biological  significance  of  emotional 
stimuli  lies  back  of  this  intensitive  differ- 
ence. Emotions  arise  in  situations  which 
the  individual  feels  are  emergencies.  We 
dislike  things  that  are  bad  for  us,  but  it  is 
not  until  they  become  actually  threatening, 
until  an  emergency  arises,  that  we  become 
emotional  and  respond  with  fear  or  with 
the  aggressive  attack  that  is  typical  of 
anger.  We  like  pleasant  things,  strive  to 
attain  them  and  to  keep  them,  but  it  is 
only  the  particularly  desirable  object  or 
goal,  the  much-wanted  or  much-desired, 
whose  attainment  produces  the  excited  re- 
sponse of  elation  or  joy.  Emotion  accom- 
panies an  emergency,  be  it  real  or  fancied. 
Emotion  is  typical  of  crisis. 


Visceral  Reactions  and  the 
Autonomic  Nervous  System 

Emotions  involve  generalized  reaction  at- 
titudes of  the  organism.  Thus  anger  is  al- 
ways marked  by  some  aggressive  response, 
some  kind  of  attack  on  the  object  that 
makes  us  angry;  yet  the  specific  behavior  of 
attack  varies  from  person  to  person  and 
from  situation  to  situation.  We  may  at- 
tempt to  dispose  of  an  enemy  by  blacken- 
ing his  eye  with  a  blow,  by  woiniding  his 
self-esteem  with  an  epithet  or  by  imdcr- 
mining  his  social  reputation  through  derog- 
atory remarks  about  his  character.  All 
strong  emotion,  however,  does  involve  one 
common  behavioral  element:  it  is  accom- 
panied by  increased  visceral  action,  height- 
ened response  in  the  vital  organs. 

The  importance  of  visceral  response  in 
emotion  has  been  recognized  since  the  ear- 
liest times.  We  speak  of  love  as  an  affair 
of  the  heart,  compassion  as  residing  in  the 
bowels  and  fear  as  striking  in  the  pit  of  the 
stomach.  Modern  physiology  has  con- 
firmed the  general  correctness  of  this  liter- 
ary usage.  We  know  that  the  viscera  are 
controlled  by  a  special  section  of  the  nerv- 
ous system,  the  autonomic  nertio^is  system, 
which  is  intimately  involved  in  emotion. 

The  autonomic  nervous  system  is  a  group 
of  nerve  centers  or  ganglia  lying  just  out- 
side the  spinal  cord.  It  controls  those  in- 
ternal vital  processes  which  have  to  do 
with  metabolism  and  the  vasomotor  and 
glandular  responses.  Heart  rate,  blood 
pressure,  salivation,  digestion,  elimination 
are  a  few  of  these  involuntary  functions 
that  operate  under  the  control  of  the  auto- 
nomic nervous  system. 

This  nervous  system  is  divided  into  two 
parts  (see  Fig.  17,  p.  35):  the  parasympa- 
thetic (craniosacral)  and  the  sympathetic 
(thoracico-lumbar).     The  actions  of  these 


Visceral  Reactions  and  the  Autonomic  Nervous  System 


95 


two  branches  are  opposed;  sympallictic 
stimulation,  for  example,  increases  the  pulse 
rate,  parasympathetic  stimulation  decreases 
it.    These  functions  may  be  seen  in  Table  I. 


TABLE  I 

Functions 

OF  THF.  Autonomic 

Nf.rvous  Systkm 

Sympathelic 

Parasympathetic 

Organ 

Function 

Function 

Heart 

speeded  up 

slowed  down 

Surface  arteries 

dilated;  more  blood 

constricted;  less  blood 

Visceral  arteries 

constricted;  less  blood 

dilated;  more  blood 

Pupil  of  eye 

dilated;  more  light 

contracted;  less  light 

Sweat  glands 

sweat  secreted 

Hair  on  skin 

hairs  erected 

Adrenal  glands 

adrenalin  secreted 

Liver 

sugar  liberated  into 

insulin  liberated;  blood 

blood 

sugar  reduced 

Salivary  glands 

salivation  stopped 

salivation  increased 

Stomach 

contraction    and    secre- 

contraction and  secre- 

tion stopped 

tion  increased 

Intestines 

contraction    and    secre- 

contraction and  secre- 

tion stopped 

tion  Increased 

Rectum 

defecation  inhibited 

feces  expelled 

Uladder 

urination  inhibited 

urine  expelled 

(Jenilal  organs 

seminal  vesicles  con- 
tracted 

erection  induced 

The  parasympathetic  system  governs 
those  vegetative  functions  which  are  con- 
cerned with  the  normal  metabolic  activities 
of  the  organism,  the  functions  which  main- 
tain the  organism  in  everyday  living; 
whereas  the  sympathetic  system  has  an 
emergency  function.  It  comes  into  action  at 
times  of  crisis  when  normal  metabolic  func- 
tion must  be  suspended  and  energy  must  be 
marshaled  to  counteract  some  threat. 

In  contrast  to  the  parasympathetic  sys- 
tem, the  parts  of  which  may  act  separately 
in  activating  specific  individual  organs,  the 
sympathetic  system  tends  to  discharge  it- 
self as  a  whole,  furnishing  a  general  dif- 
fused excitation  to  all  the  organs  under  its 
control.  It  is  this  diffuse  sympathetic  ac- 
tion which  provides  the  visceral  response 
typical  of  all  strong  emotion.  When  you 
are  angry  or  afraid  and  you  feel  as  though 
the  bottom  of  your  stomach  had  'dropped 
out,'  feel  yourself  shaking  and  trembling. 


feel  your  heart  rating  and  your  blood 
pounding  in  your  throat,  it  is  a  sign  that 
your  sympathetic  nervous  system  has  gone 
into  action. 

The  parasymjjathctic  system  is  also  active 
in  emotion,  and  its  differential  activation 
of  various  organs  may  account  for  some  of 
the  difference  between  such  unpleasant 
emotional  states  as  anger  and  fear;  but  this 
parasympathetic  adion  usually  is  masked 
by  the  violent,  generalized  response  of  the 
sympathetic  system.  It  is  the  sympathetic 
system  that  is  primarily  responsible  for  the 
bodily  state  of  excitement  common  to  all 
strong  emotion. 

Walter  B.  Cannon,  in  his  emergency 
theory  of  emotion,  has  made  the  point  that 
sympathetic  action  not  only  occurs  com- 
monly in  all  the  emergencies  which  tall 
forth  emotion,  but  that  tiie  bodily  results 
of  such  action  place  the  individual  in  a 
state  of  physiological  preparedness  or  effi- 
ciency to  meet  the  threat  of  such  emergen- 
cies. Sympathetic  action  occurs  because  it 
is  useful  in  an  emergency.  Digesti\e  func- 
tions are  stopped,  and  the  blood  supply  of 
the  body  is  directed  to  the  voluntary  mus- 
cles—the attack  muscles,  the  flight  muscles. 
The  heart  beats  more  rapidly  supplying 
more  blood  to  these  muscles.  At  the  same 
time,  blood  sugar  is  liberated  from  the 
liver  to  furnish  extra  fuel  for  heavy  muscu- 
lar activity.  The  bronchioles  to  the  lungs 
dilate,  making  it  easier  to  breathe  and  in- 
suring a  greater  supply  of  oxvgen.  The 
sympathetic  innervation  of  the  adrenal 
glands  results  in  the  secretion  into  the 
blood  stream  of  a  hormone,  adrenalin, 
which  acts  directly  upon  the  viscera  in  the 
same  manner  as  direct  sympathetic  stimu- 
lation. Adrenalin  thus  becomes  a  sustain- 
ing or  reinforcing  agent,  building  up  the 
sympathetic  response.  Because  of  this  ac- 
tion it  is  called  a  sympathomimetic  chem- 


96 


Feeling  and  Emotion 


ical  agent,  for  it  duplicates  the  effects  of  the 
sympathetic  system. 

Adrenalin  also  has  some  particular  prop- 
erties of  its  own  which  it  contributes  to  the 
general  bodily  picture  of  efficiency  for  ac- 
tion during  an  emergency.  It  hastens  the 
coagulation  time  of  the  blood,  helping  to 
counteract  hemorrhage  in  a  surface  wound; 
and  it  is  thought  also  to  have  some  direct 
action  in  counteracting  the  effects  of  fa- 
tigue. 

The  actual  efficiency  of  such  an  emer- 
gency response  in  the  complicated  condi- 
tions of  present-day  civilized  living  is  du- 
bious. We  no  longer  fight  wild  beasts  in 
hand-to-hand  combat,  but  there  are  many 
social  relations,  ranging  from  an  argument 
between  two  persons  to  war  between  na- 
tions, where  perceived  aggression  begets  ag- 
gression in  the  perceiver  by  way  of  these 
automatic  reaction  mechanisms  of  the  sym- 
pathetic nervous  system.  Usually  civilized 
man  avoids  fight  with  his  muscles,  using 
words  or  the  police  as  his  agents.  Yet  the 
visceral  response  of  emotion  is  still  present, 
and  the  effort  to  suppress  emotion  in  civili- 
zation is  often  costly  to  him  who  is  moved. 
Later  we  shall  return  to  a  consideration  of 
this  matter,  when  we  come  to  the  discussion 
of  the  measurement  of  emotion,  and  also 
when  we  deal  with  some  of  the  harmful  ef- 
fects of  emotion  upon  the  body,  a  subject 
of  great  importance  today  in  the  medical 
specialty  called  psychosomatic  medicine. 

Direct  Action  of  the  Nervous  System 

The  pattern  of  sympathetic  excitation 
just  described  results  in  energizing  the  or- 
ganism. The  person  experiencing  emotion 
is  ready  for  action;  he  is  'rarin'  to  go.'  This 
fact  has  been  shown  in  experiments  where 
the  visceral  pattern  of  emotion  has  been 
artificially  produced  by  the  injection  of 
adrenalin,   whose   action,   as  we   have  just 


learned,  duplicates  that  of  sympathetic 
stimulation.  .  Few  subjects  report  feeling  a 
genuine  emotion  imdcr  these  circum- 
stances, but  most  of  them  report  feeling 
tense,  excited  and  moved  to  action.  This 
state  has  sometimes  been  called  a  'cold 
emotion.'  Subjects  say:  "I  want  to  have 
an  emotion  and  get  it  over  with"  and  "I 
feel  all  wrought  up  and  want  to  get  it  off 
my  chest." 

When  the  emotional  stimulation  is  par- 
ticularly strong  or  when  the  usual  channels 
of  emotional  expression  are  blocked,  the 
excitation  initiated  may  overflow  into 
other  nervous  pathways  to  result  in  confus- 
ing, extraneous  responses  which  are  not 
part  of  the  usual  pattern.  Thus  an  impa- 
tient man  may  relieve  his  tension  by  tap- 
ping his  foot;  an  angry  man  attempting  to 
control  his  rage  may  giind  his  teeth.  In 
one  experiment  of  infants'  reactions  to  a 
sudden  loud  noise  (revolver  shot),  it  was 
found  that  many  of  the  male  infants,  in 
addition  to  being  startled,  crying,  etc.,  also 
showed  a  sexual  response  with  genital 
tumescence.  In  1872  Charles  Darwin  de- 
scribed the  behavioral  overflow  of  emotion 
in  his  classic  work  on  the  expression  of 
emotion.  The  phenomenon  illustrates  the 
dynamic,  energizing  nature  of  emotion. 

Peripheral  Response  and 
Expressive  Behavior 

Emotion  is  not  limited  to  visceral  reac- 
tions, but  also  involves  the  peripheral  mus- 
culature under  the  control  of  the  central 
nervous  system.  It  is  these  easily  observed 
peripheral  responses  which,  as  indicating 
certain  internal  or  central  events,  are  usu- 
ally spoken  of  as  expressive  behavior  in 
emotion.  The  attempt  to  find  specific  and 
predictable  patterns  of  expressive  behavior 
has  attracted  the  research  efforts  of  many 
psychologists. 


Expression  in  Emotion 


77 


Unfortunately,  the  results  of  liieir  inv<-s- 
cigations  have  been  bf)(ii  eoiif using  and 
controversial.  No  clear  .and  univotal  ex- 
pressive patterns  have  been  found  for  the 
different  emotions.  Anger,  it  is  true,  seems 
to  involve  a  general  attitude  of  aggressive 
attack  by  the  organism,  but  the  specific  be- 
haviors by  which  such  an  attack  is  carried 
out  are  infinitely  varied  and  change  from 
situation  to  situation. 

fn  part  this  variability  arises  from  the 
fact  that  the  peripheral  musculature,  un- 
like the  visceral,  is  subject  to  voluntary 
control  involving  fewer  reflexes.  Thus  a 
man  can  often  inhibit  and  suppress  his 
expressive  behavior  during  emotion,  and  in 
different  civilizations  sang  froid  is  culti- 
vated in  different  degrees.  When  you  are 
angry  you  cannot  control  your  rapid  pulse, 
nor  your  rising  blood  pressure;  but  you  can 
repress  hostile  movement  and  you  may 
even  force  a  pleasant,  disarming  smile. 
The  expressive  peripheral  behavior  in  emo- 
tion thus  is  not  an  immediate,  involuntary, 
primitive  reaction  like  the  visceral  re- 
sponse. It  is  complicated  by  voluntary  con- 
trol, the  acquisition  of  learned  modifica- 
tions and  the  effects  of  social  and  cultural 
standards.  No  wonder  that  few  clear, 
identifiable  patterns  of  emotional  expres- 
sion have  been  discovered.  Even  those 
which  are  almost  universal  in  meaning,  like 
the  smile,  can,  being  voluntary,  be  used 
to  deceive. 

Facial  Expression  in  Emotion 

The  difficulties  of  investigation  and  the 
conflicting  findings  of  such  research  are 
seen  most  typically  in  the  studies  of  facial 
expression.  Most  of  the  early  work  was 
undertaken  under  the  assumption  that  spe- 
cific facial  expressions  exist  for  the  various 
emotions.  Actors  or  other  persons  trained 
in  mimicry  were  asked  to  pose,  assuming 


the  expressions  representative  of  such  emo- 
tions as  anger,  fear,  surprise  and  disgust. 
Their  faces  were  then  photographed  or 
drawn  by  an  artist,  and  the  pictures  were 
presented  to  subjects  who  were  asked  to 
name  the  emotion  portrayed. 

That  roughly  typical  facial  expressions 
for  certain  emotions  exist  is  demonstrated 
by  the  fact  that  subjects  can  identify  these 
expressions  when  they  are  posed.  The 
older  and  less  subtle  emotions  are  most 
consistently  interpreted,  whereas  in  other 
posed  expressions  there  is  a  wide  range  of 
diverse  interpretations.  The  ability  of  per- 
sons to  interpret  these  expressions  correctly 
improves  with  training,  with  increasing  age 
and  with  increasing  intelligence.  \\'hat 
have  we  got  in  these  uniformities:  behavior 
that  is  instinctive  and  biologically  deter- 
mined, or  behavior  that  is  learned  and  ad- 
justed to  certain  cultural  conventions? 

Since  the  pictures  used  in  these  experi- 
ments were  deliberately  posed  and  did  not 
represent  the  features  of  an  individual  ac- 
tually experiencing  an  emotion,  they  can 
only  demonstrate  the  existence  of  stereo- 
typed, socially  accepted  patterns  of  facial 
expression  which  can  be  assumed  volun- 
tarily by  a  man  when  he  wishes  to  com- 
municate his  feelings  to  others  about  him. 
The  behavior  need  not  be  instinctive  but 
merely  a  culturally  acquired  means  of  so- 
cial communication.  Thus  'looking  sur- 
prised' is  not  an  immediate,  necessary  mus- 
cular response  to  certain  stimulus  situa- 
tions, but  rather  a  learned  means  of  telling 
people  how  you  feel  under  certain  condi- 
tions. Facial  expression  substitutes  for 
verbal  expression  in  the  communication  of 
feeling.  There  are  manv  anthropological 
findings  on  the  differences  of  expressive 
movement  in  different  cultures.  For  in- 
stance,   in   our   culture   round,   wide-open 


98 


Feeling  and  Emotion 


eyes  suggest  surprise,  but  to  the  Chinese 
they  mean  anger. 

One  experimenter  substituted  for  posed 
expressions  photographs  of  the  faces  of 
people  who  ^vere  having  actual  laboratory- 
induced  emotions.  When  the  stimuli  were 
weak,  the  classical  expressions  appeared  as 
expected,  but  when  strong  stimuli  were 
used  to  arouse  strong  emotions,  the  con- 
ventional facial  patterns  did  not  appear. 
The  emotional  situations  were  genuinely 
upsetting  and  included  plunging  the  hand 
into  a  bucket  of  live  frogs,  decapitating  a 
rat,  looking  at  pornographic  pictures  and 
being  suddenly  given  ammonia  while  smell- 
ing a  pleasant  perfume. 

Instead  of  the  conventional  patterns 
there  appeared  a  diverse  mass  of  nuiscidar 
response  whicii  varied  from  person  to  per- 
son. Each  subject  seemed  to  have  his  own 
characteristic  pattern  and  there  was  little 
agreement  among  them.  Nevertheless  the 
amount  of  facial  response  varied  signifi- 
cantly. Pain  showed  the  most  movement, 
anger  less,  disgust  still  less  and  revolting 
experiences  very  little. 

This  finding  confirms  the  view  that  typ- 
ical facial  expressions  exist  as  a  tradition 
in  our  culture,  and  that  people  learn  to 
use  them  as  a  means  of  social  communica- 
tion. In  mild  emotional  situations  where 
the  reaction  is  largely  intellectual,  these 
cultural  patterns  predominate,  biu  in 
strong  emotion  the  social  language  is  for- 
gotten and  varied  expressions  appear  that 
have  little  relation  to  the  classical  pat- 
terns. 

This  interpretation  is  still  further  ad- 
vanced by  experiments  which  show  that, 
in  judging  the  feelings  of  people  in  actual 
emotional  situations,  observers  rely  more 
upon  their  knowledge  of  the  stimulus  con- 
ditions than  upon  the  subjects'  facial  ex- 
pression.     A    group    of    medical    students 


were  shown  moA'ing  pictures  of  the  re 
spouses  of  infants  who  were  hungry,  were 
dropped,  were  restrained  by  having  their 
heads  held  and  were  stuck  with  a  pin. 
AV^ith  no  knowledge  of  the  stimulus  condi- 
tions, the  students  had  little  success  in 
identifying  the  emotions.  With  knowledge 
of  the  stimuli,  the  students  could  spec- 
ify the  proper  emotions.  But  when  the 
stimidi  were  associated  with  the  wrong  pic- 
tures of  expressive  behavior,  the  students 
became  at  once  confused  about  the  signifi- 
cance of  the  behavior. 

The  Startle  Pattern 

The  one  consistent  exception  to  the  gen- 
eral statement  that  there  has  been  found 
no  fixed,  innate  pattern  of  facial  or  bodily 
emotional  reaction  is  sudden  surprise  or 
the  startle  pattern.  If  a  per^on  is  suddenly 
stimulated  by  a  loud  soiuid  or  a  flash  of 
light,  a  very  rapid  response  pattern  occurs 
in  him. 

By  means  of  high-speed  motion-picture 
photography,  the  response  to  the  sound  of 
a  pistol  shot  has  been  studied.  Cameras 
rimning  as  fast  as  three  thousand  exposures 
per  second  have  permitted  the  very  exact 
analysis  of  this  pattern.  Figures  40  and  41 
are  schematic  drawings  showing  the  ele- 
ments of  this  pattern  in  both  the  infant 
and  the  adidt.  The  startle  response  con- 
sists of  a  sudden  movement  of  the  head, 
blinking  of  the  eyes,  a  characteristic  facial 
expression,  raising  and  drawing  forward  of 
the  shoidders,  turning  inward  of  the  upper 
arms,  bending  of  the  elbows,  turning  down- 
ward of  the  forearms,  flexion  of  the  fingers, 
forward  movement  of  the  trunk,  contrac- 
tion of  the  abdomen  and  bending  of  the 
knees.  Not  all  these  elements  occur  in 
every  person  every  time  he  is  stimulated. 
Elements  in  the  response  which  are  op- 
posed to  any  of  these  reactions,  however, 


The  Startle  Pattern  and  the  James-Lar^ge  Theory 


99 


rarely  if  ever  occur.    Present  cvidentc  leads  I'he  startle  pattern  is  usually  tornpkted 

us  to  believe  that,  witiiin  limits,  complete-      in  less  than  half  a  second.     Hence  it  tan- 
ness  of  appearance  of  the  pattern  is  closely      not  be  adcfpiatcly  oljserved  except  by  the 


related    to   the    intensity   of  the   stimulus; 

mild   simuli   may   give   only  the   eyeblink, 

but  intense  stimuli  give  the  complete  pat- 
tern. 


FIGURE    40.       SCHEMATIC    REPRESENTATION    OF    THE 
BODILY  PATTERN  IN  STARTLE 

[From  C.  Landis  and  W.  A.  Hunt,  The  startle 
pattern.  Farrar  and  Rinehart,  1939.  p.  22.] 

It  has  also  been  shown  that  with  repeti- 
tion certain  parts  of  the  startle  response 
die  out— rapidly  in  some  individuals  and 
slowly  in  others.  After  a  long  series  of 
stimuli,  the  eyeblink  and  certain  elements 
of  the  facial  contortion  persist  in  practi- 
cally everyone,  although  most  other  ele- 
ments of  the  pattern  will  have  dropped 
out.  After  a  sufficient  period  of  time,  how- 
ever, the  appropriate  stimulus  will  again 
elicit  the  total  pattern. 

The  pattern,  which  can  be  evolved  in 
very  early  infancy,  does  not  change  in  its 
form  throughout  life.  It  appears  in  all  the 
higher  animals.  In  certain  diseases  it  is 
exaggerated,  whereas  in  epilepsy  it  is  totally 
absent  in  about  one-fifth  of  the  patients. 


temporal  magnification  of  ultra-rapid  pho- 
tography. Few  people  are  even  aware  that 
it  has  occurred  in  them. 

The  Emotional  Consciousness 

"I'he  c|uestifjn  of  whether  or  not  the  vari- 
ous emotions  are  accompanied  by  some 
.sort  of  imique  and  specific  conscious  crjn- 
tent  has  long  bothered  psychologists. 
While  we  would  presume  that  the  logical 
answer  to  this  question  would  be  found  in 
a  direct  appeal  to  introspection  (asking  sub- 
jects   undergoing    emotion    to    report    di- 


FIGURE    41.       SCHEMATIC    REPRESENTATIO.V    OF    THE 
STARTLE    PATTERN    IN    INFANTS 

{A)  resting  posture.  (B)  startle  pattern.  [From 
C.  Landis  and  W.  A.  Himt,  The  startle  patient, 
Farrar  and  Rinehart,  1939.  p.  61.] 

rectly  on  how  they  feel),  this  method  has 
not  been  used  to  any  gieat  extent.  Most 
of  the  classical  studies  have  assumed  the 
existence  of  such  distinguishing  feelings 
and  then  proceeded  to  make  hypotheses 
concerning  their  origin. 

In   1884  William  James,   the  American 


TOO 


Feeling  and  Emotion 


psychologist,  and  in  1885  C.  G.  Lange,  the 
Danish  physiologist,  proposed  independ- 
ently what  came  presently  to  be  called  the 
James-Lange  theory  of  emotion.  This  the- 
ory states  that  the  conscious  emotion  consists 
of  a  man's  awareness  of  his  bodily  changes 
as  they  occur  in  his  emotion.  There  is  a 
stimulus  to  emotion,  the  organism  responds 


FIGURE    42.       JAMES-LANGE    AND    CANNON-BARD 
THEORIES   OF   EMOTION 

The  James-Lange  theory  states  that  emotional  ex- 
perience in  the  cortex  arises  from  autonomic  re- 
actions to  the  emotional  stimulus.  The  impulses 
from  the  receptors  go  through  the  thalamus  to  the 
effectors  and  travel  back  through  the  thalamus  to 
the  cortex,  giving  rise  to  the  consciousness  of  the 
emotion.  The  Cannon-Bard  theory  holds  that  both 
emotional  experience  and  autonomic  effects  arise 
from  the  stimulus.  The  impulses  from  the  recep- 
tors go  to  the  thalamus  and  then  both  to  the  cortex 
and  to  the  effectors.  The  responses  of  the  effectors 
are  an  accompaniment  of  the  emotional  experience. 
[From  C.  T.  Morgan.  Physiological  psychology, 
McGraw-Hill,  1943,  p.  3,'i6.] 

reflcxly,  and  then  the  conscious  awareness 
of  these  reflex  changes  gives  the  man  his 
feeling  of  emotion.  James  said  "the  bodily 
changes  follow  directly  the  perception  of 
the  exciting  fact,  and  .  .  .  our  feeling  of 
the  same  changes  as  they  occur  is  the  emo- 
tion." We  do  not  cry  because  we  feel 
sorry,  but  feel  sorry  because  we  cry. 

In  some  neurological  disorders  when  the 
patient  cannot  feel  these  bodily  changes, 
he  may,  nevertheless,  report  feeling  an  emo- 


tion. In  other  disorders,  like  pathological 
laughing  or  weeping,  bodily  responses  typ- 
ical of  einotions  take  place  and  yet  the  pa- 
tient may  be  without  any  experience  that 
he  would  call  an  emotion.  These  facts 
and  others  have  cast  doubt  upon  any  literal 
acceptance  of  the  James-Lange  theory. 

The  fact  that  the  hypothalamus,  a  lower 
brain  center,  acts  in  mediating  the  reflex 
responses  typical  of  emotion  has  led  Can- 
non and  Bard  to  posit  this  part  of  the 
brain  as  the  seat  of  emotional  conscious- 
ness. According  to  this  theory,  the  action 
of  this  center  adds  the  quale  or  distin- 
guishing element  of  consciousness  which 
gives  emotion  its  typical  characteristic  feel. 
(See  Fig.  42.) 

All  these  interpretations,  however,  seem 
to  rest  upon  an  oversimplification  of  emo- 
tional behavior.  There  is  little  evidence 
that  a  peculiar,  unique  type  of  conscious- 
ness accompanies  and  identifies  the  differ- 
ent emotions.  Different  persons  describe 
their  emotional  feelings  in  different  ways. 
To  one  man  conscious  emotion  may  be  his 
awareness  of  the  bodily  responses  taking 
place;  he  may  report  that  fear  is  typified 
by  "an  awful  feeling  in  my  stomach,  and 
cold,  clammy  hands."  Another  man,  how- 
ever, may  concentrate  upon  the  cognitive, 
relational  aspects  of  experience.  He  feels 
fear  as  the  awareness  of  a  threatening  situa- 
tion. "Something  is  present  which  I  would 
like  to  avoid."  We  can  only  conclude  that 
the  conscious  experiences  in  emotion  arc  as 
complex  and  multiform  as  the  behavioral 
items  and  that  the  existence  of  specific, 
unique,  distinguishing  conscious  content  in 
the  various  emotions  has  not  been  dem- 
onstrated. 

Emotion  and  Learning 

Emotional  behavior,  like  much  other  be- 
havior,   is    subject    to    learning.      New   re- 


The  Development  of  Emofion 


101 


sponses  may  be  attached  Lo  old  stimuli,  ;ni(l 
new  stimuli  may  be  attached  to  old  re- 
sponses. Such  learning^  resuks  in  a  rapid 
comph'cation  ol  wliatevcr  slimuhis-responsc 
patterns  may  be  present  innately  in  the 
human  infant.  Any  universal  patterns  that 
may  exist  then  are  rapidly  altered  by  learn- 
ing in  accordance  with  the  unique  life  ex- 
periences of  each  individual. 

A  classic,  early  experiment  in  this  field 
was  performed  in  1920  by  John  B.  Watson. 
A  nine  months'  infant  showed  no  fear  of 
a  white  rat,  but  showed  evidence  of  fear 
when  a  loud  sound  was  made  by  striking  an 
iron  bar.  Striking  the  bar  when  the  infant 
was  reaching  for  the  white  rat  resulted  in 
fear  behavior  which  later  appeared  when 
the  rat  was  presented  alone  without  the 
loud  sound.  The  infant  had  now  learned 
to  be  afraid  of  the  white  rat  because  of  its 
association  with  the  fearsome  noise. 

An  important  result  of  this  experiment 
was  the  demonstration  that  the  fear  be- 
havior not  only  became  attached  to  the 
white  rat  as  a  new  stimulus,  but  also  spon- 
taneously became  attached  to  other  stimuli 
resembling  the  rat,  although  these  had  not 
been  present  in  the  original  learning  situa- 
tion. The  infant  now  feared  other  furry 
animals,  as  well  as  fur  coats  and  a  teddy 
bear,  which  had  never  been  associated  with 
the  loud  noise.  This  generalization  of 
learning  shows  how  complicated  our  emo- 
tional behavior  may  become  on  the  basis 
of  a  single  emotional  experience. 

Such  learning  may  explain  the  genesis 
of  abnormally  strong  fears  which  become 
attached  to  specific  stimuli  or  situations. 
During  the  war,  an  examination  of  Naval 
recruits  who  could  not  swim  showed  that 
many  of  them  were  nonswimmers  because 
of  a  fear  of  water  attributable  to  some  emo- 
tional shock  experienced  during  boyhood. 
One  recruit  had  dived   into   a  swimming 


hole  shortly  alu-r  a  boy  had  been  drowned 
there,  lie  hit  the  corpse  on  ilje  bottom 
and  came  up  with  it  entangled  in  his  arms. 
Since  that  one  gruesome  experience,  he  has 
been  unable  to  force  himself  to  enter  the 
water. 

Not  only  can  emotions  be  altered  by 
learning,  but  emotion  itself  may  inter- 
fere with  learning.  Subjects  attempting 
to  solve  prcjblems  under  emotional  stress 
do  not  do  well.  Their  reasoning  is  in- 
ferior, and  they  tend  to  forget  more  re- 
cently learned  responses  and  to  fall  back 
upon  older  habits  which  may  no  longer 
be  applicable.  Whether  the  emotional  be- 
havior directly  affects  the  learning  process 
or  merely  acts  as  a  distraction  to  the  indi- 
vidual attempting  to  learn  is  not  clear,  but 
the  interference  of  emotion  during  learn- 
ing has  been  demonstrated  amply.  It  is 
hard  to  study  when  you  are  excited.  It  is 
also  hard  to  think  clearly  when  you  are 
excited.  The  emergency  aspect  of  emotion 
is  right  for  running  away  or  fighting  or 
even  for  primitive  love  making,  but  civili- 
zation brings  emotions  and  emergencies 
which  need  more  brain  than  brawn.  Man's 
emotions  are  still  useful  to  him,  but  he  is 
nowadays  well  advised  to  keep  a  cool  head 
when  emergencies  arise. 

The  Genetic  Development  of  Emotion 

The  preceding  discussion  has  sho^vn  that, 
apart  from  the  common  element  of  visceral 
excitement  attributable  to  the  excitation 
of  the  sympathetic  branch  of  the  auto- 
nomic nervous  system,  there  is  very  little 
vniiformity  and  agreement  in  the  specific 
behavior  of  different  individuals  during 
emotion  with  the  exception  of  die  startle 
response.  To  some  scientists  this  finding 
means  that  no  inherent  emotional  re- 
sponses are  provided  for  in  the  nervous 
system  of  the  human  being.    Others  believe 


102 


Feeling  and  Emotion 


that  instinctive  emotional  patterns  exist  but 
that  learning  enters  at  so  early  an  age  as 
to  confuse  and  complicate  the  original  pic- 
ture. 

The  appeal,  to  studies  of  infant  behavior 
has  not  clarified  the  problem.  Smiling, 
laughing  and  crying,  as  we  shall  see  later, 
seem  to  be  fairly  uni\ersal  and  predictable 
in  infants,  but  even  these  behaviors  are 
rapidly  altered  by  learning  and  social  pres- 
sme.  Recent  studies  of  these  patterns  show 
their  occurrence  in  blind  children  in  the 
same  manner  and  under  the  same  circum- 
stances as  in  seeing  children.  In  the  seeing 
children,  however,  mimicry  and  social  pres- 
sure produce  beha\ioral  changes  which  in- 
crease with  age. 

Watson,  in  an  early  study  of  the  emo- 
tional behavior  of  infants,  claimed  to  have 
loimd  three  basic  patterns  of  response— 
fear,  anger  and  lox'e.  The  stimuli  for  fear 
were  sudden  loud  sounds  and  the  sudden 
loss  of  support  (dropping  the  child  and 
catching  it);  for  anger,  restraint  of  move- 
ment; and  for  love,  cuddling  and  the  stimvi- 
lation  of  the  erogenous  zones.  On  this  sim- 
ple basis,  through  the  various  combinations 
obtainable  by  learning,  he  proposed  to  ex- 
plain the  entire  complicated  picture  ol 
adult  emotion.  Thus  a  student  who  fears 
loss  of  social  prestige  by  dismissal  from  the 
football  squad  is  afraid  because,  through 
learning  and  generalization,  he  has  associ- 
ated loss  of  social  prestige  with  the  loss  of 
physical  support  which  was  the  original 
fear  stimulus  in  his  infant  environment. 
Fear  of  the  dark,  Watson  thought,  may 
also  spring  from  a  fear  of  loss  of  support, 
since  in  the  darkness  all  the  familiar  orient- 
ing visual  clues  by  whicli  we  habitually 
guide  and  steady  ourselves  in  space  are 
missing. 

Later  work  has  demonstrated  that  Wat- 
son's findings  do  not  present  the  complete 


picture  of  infant  emotion.  Loud  sounds, 
loss  of  support  and  restraint  of  movement 
are  common  and  potent,  but  not  universal, 
determiners  of  emotion.  Not  all  infants 
cry  when  they  are  startled  by  a  revolver 
shot.  If  they  are  already  crying  when  the 
gun  is  fired,  some  ma)  stop  crying  instead  of 
crying  harder.  The  triuh  is  not  so  simple 
as  \Vatson  had  believed. 

The  emotional  response  of  the  infant  at 
birth,  like  all  his  other  behavior,  is  limited 
by  the  relatively  primitive  state  of  his  nerv- 
ous system.  As  his  nervous  system  de\'el- 
ops,  more  complicated  behavior  becomes 
possible  for  him.  Whether  these  changes 
are  learned  or  not,  it  is  hard  to  say.  For 
instance,  it  was  found  that  children  under 
two  had  no  fear  of  snakes.  After  two,  cau- 
tion in  approach  to  snakes  became  e\ident 
in  the  children's  behavior.  Definite  fear  of 
snakes  did  not  appear  with  any  frequency 
until  the  age  of  four.  Is  this  progressive 
development  of  the  fear  of  snakes  related 
to  some  innate  reaction  pattern  which  be- 
comes operative  as  the  nervous  system  ma- 
tures, or  is  it  a  learned  response  acquired 
as  the  child  becomes  socialized?  The  com- 
plex nature  of  any  emotional  behavior 
shows  that  it  must  derive  from  both  sources. 

The  emotional  development  of  the  child 
is  characterized  by  a  decreasing  frequency 
of  intense  emotional  response,  by  a  pro- 
gressive transfer  of  emotion  to  socially  ap- 
proved and  experientially  determined  situ- 
ations and  by  a  change  in  the  patterns  of 
emotional  behavior  to  accord  with  cultural 
pressin-es. 

SPECIFIC    EMOTI  ONS 

Most  of  our  consideration  of  emotion  so 
far  has  been  about  the  general  characteris- 
tics common  to  all  emotions.  Now  it  is 
time  to  be  more  specific,  to  deal  with  indi 


Smiling,  Laughing  and  Crying 


103 


vidual    chanittciistics    associated    with    the 
different  emotions. 

Smiling,  Laughing  and  Crying 

Well-defined  examjjies  ol  emotional  ex- 
jiression  are  smiling,  laughing  and  crying. 
We  habitually  accept  the  occurrence  of  this 
sort  of  behavior  as  indicative  of  emotional 
experience.  Although  it  is  true  that  these 
behaviors  may  occur  without  attendant 
emotional  experience,  yet  in  the  ordinary 
conduct  of  everyday  life  smiling,  laughing 
and  crying  are  by  common  consent  re- 
garded as  truly  emotional  expressions. 

The  development  of  these  patterns  of 
response  in  the  infant  has  long  been  a 
matter  of  interest  to  child  psychologists. 
Smiling  is  exhibited  at  a  very  early  age  by 
most  children.  In  the  very  yoimg  infant  it 
is  almost  invariably  brought  about  by  spe- 
cific stimulation,  the  response  usually  being 
evoked  by  other  people,  or  at  least  exhib- 
ited only  in  their  presence.  Study  of  the 
development  of  smiling  and  laughing 
shows  that  originally  several  varieties  of 
respiratory  reactions  or  compensatory  mo- 
tor mechanisms  are  elicited  by  certain  situ- 
ations whicfi  the  child  lias  not  met  before 
and  for  which,  consequently,  he  has  ready 
no  immediate  appropriate  pattern  of  re- 
sponse. On  such  occasions  a  response  in- 
volving smiling  or  laughing  is  appro\ed 
by  the  infant's  mother  or  nurse,  whereas 
other  respiratory  mechanisms  may  be  dis- 
approved. Smiling  and  laughing  are  thus 
quickly  foiuid  to  be  socially  acceptable  and 
to  lead  to  reward  or  comfort.  They  be- 
come learned  reactions,  selected  as  socially 
appropriate.  Once  incorporated  in  the  re- 
action repertoire  of  the  child,  this  original 
usage  becomes  widely  generalized,  blending 
into  all  the  patterns  of  response  which  din- 
ing most  of  our  lives  we  call  amusement. 
Already  by  the  end  of  the  first  )'ear  of  life, 


smiling  has  become  a  learned  response  to 
such  an  extent  that  the  smile  must  be  re- 
garded as  a  communicative,  adaptive,  social 
reaction  rather  than  a  modified  respiratory 
response. 

Laughing  appears  much  later  in  die 
child's  life  than  smiling,  usually  not  until 
after  the  twentieth  week.  During  the  first 
year  of  life  it  remains  a  stereotyped  form  of 
behavior.  More  differences  between  chil- 
dren occur  in  the  frec|uency  of  smiling  or 
laughing  than  in  the  actual  form  of  these 
two  behaviors. 

Laughter  presents  us  with  more  than  one 
problem.  We  have  laughter  of  joy,  laugh- 
ter of  comedy,  laughter  as  a  form  of  social 
response,  laughter  as  a  release  from  tension 
and  laughter  under  pathological,  organic 
or  mental  conditions.  All  these  laughters 
involve  different  psychological  elements. 
The  joyfid  laugh,  a  bubbling  over  of  good 
humor,  occurs  in  children  or  adults  in  a 
state  of  well-being.  The  comic  laugh  is  di- 
rected at  some  joke  or  ludicrous  situation. 
Laughter  as  a  social  response  invoh  es  many 
principles  of  social  psychology.  AVe  laugh 
more  easily  in  a  group  tlian  alone,  for 
laughter  is  a  \ariety  of  gesture  language. 
The  act  of  laughing  may  be  used  at  times 
for  a  commimication  of  good  will  and  a 
spirit  of  fun,  at  others  of  pme  jov  and,  at 
still  other  times,  of  embarrassment. 

The  laughter  which  is  associated  with  a 
relief  of  tension  has  been  explained  on  an 
evolutionary  basis.  Since  the  facial  nius- 
cidature  is  not  primarilv  necessary  to  the 
active  energetic  preservation  of  life,  it  has 
been  suggested  that  the  excess  energy,  set 
up  by  emotional  stimulation,  is  drained  off 
by  the  activity  of  the  facial  and  respiratory 
muscles  in  a  way  which  does  not  interfere 
with  any  activity  of  the  body  essential  to 
the  emergency  which  induces  the  emotion. 
Ihis  drainage   theory  must  not   be   taken 


104 


Feeling  and  Emotion 


loo  literally.  The  nervous  system  does  not 
accumulate  energy  which  has  to  be  released 
by  one  channel,  if  not  by  another.  Never- 
theless, it  is  true  that  individuals  often  find 
themselves  in  slates  of  emotional  tension 
which  can  be  relieved  only  by  action— al- 
most any  relevant  action.  It  is  a  problem 
of  motivation,  however,  not  of  physics. 

The  behavior  of  infants  during  crying 
has  been  observed  experimentally  in  a  se- 
ries of  standard  situations.  Crying  induced 
by  the  perception  of  strangers  increases  in 
frequency  up  to  about  ten  months  of  age. 
Crying  caused  by  fear  or  strange  situations 
can,  however,  be  distinguished  from  other 
types  of  the  response.  In  the  adult,  crying, 
like  laughing  and  smiling,  is  so  bound  up 
with  the  social  reactions  of  the  individual 
that  it  is  impossible  to  be  certain  in  a  ma- 
jority of  cases  whether  the  response  is  truly 
emotional,  only  partly  so  or  an  habituated 
response,  devoid  of  emotion. 

The  observation  of  adults  in  situations 
which  produce  tears  (funerals,  for  example) 
shows  that  tears  are  usually  indicative  of  a 
mixed  emotional  state.  Sorrow,  dejection, 
joy  and  elation,  when  occurring  alone,  have 
but  little  effect  in  producing  tears.  Adult 
crying  occurs  in  the  main  only  when  an 
otherwise  depressing  or  unpleasant  situa- 
tion is  partially  redeemed  by  some  pleasant 
or  alleviating  stimulation,  or  when  there  is 
a  conflict  in  extreme  frustration. 

Fear 

The  most  jDrominent  feelings  associated 
with  fear  are  the  bodily  sensations  at- 
tributable to  the  activation  of  the  auto- 
nomic nervous  system.  Pounding  of  the 
blood,  a  sinking  feeling  in  the  stomach, 
trembling  and  shaking,  weakness,  faintness 
and  tension  all  are  common  and  promi- 
nent. 

Present  witJi  these  ieelint!,s  is  an  insistent 


desire  to  get  away  from  some  threatening 
situation  with  which  the  individual  does 
not  feel  able  to  deal  adequately.  Some 
form  of  withdrawal  behavior  usually  re- 
sults. Once  the  threatening  stimulus  has 
been  removed  or  the  threatening  situation 
has  been  controlled,  and  the  real  or  imag- 
ined danger  has  passed,  fear  disappears.  If 
the  danger  increases  rapidly,  or  if  the  fear 
strikes  suddenly  and  severely,  terror  may 
result  with  a  complete  disintegration  of 
the  individual's  behavior.  Typical  of  ter- 
ror are  both  the  blind  flight  of  panic  and 
the  occasional  complete  inhibition  of  activ- 
ity with  its  attendant  immobility  and  paral- 
ysis of  volition.  When  fear  is  anticipatory, 
when  it  is  aroused  by  something  foreseen 
in  the  future  rather  than  existing  in  the 
present,  we  may  call  it  anxiety  or  appre- 
hension. 

The  stimuli  for  fear  are  many  and  varied 
but  they  all  involve  some  sudden  change  in 
the  environment,  some  change  which  the 
individual  regards  as  threatening  and  to 
which  he  is  either  unprepared  or  unable  to 
respond.  This  fact  has  led  one  psycholo- 
gist to  speak  of  such  situations  as  cata- 
strophic, and  fear  behavior  as  catastrophic 
behavior.  Once  an  adequate  course  of  ac- 
tion develops,  once  the  individual  feels  he 
is  in  control  of  the  situation  and  doing 
something  about  it,  fear  disappears. 

It  is  not  the  man  who  is  successfidly  run- 
ning away  from  a  bear  who  is  afraid.  Fear 
comes  when  he  realizes  that  the  gap  be- 
tween him  and  the  bear  is  decreasing  in- 
stead of  growing  larger,  or  when  he  realizes 
that  he  is  becoming  exhausted  and  cannot 
run  much  farther.  It  is  the  soldier  about 
to  go  into  combat  who  most  often  experi- 
ences fear,  rather  than  the  one  who  is  ac- 
tually in  combat,  fighting  desperately  for 
his  life. 

Ade(iuaic  action  seems  to  be  llic  antidote 


Fear  and  Anger 


105 


for  fear.  Such  action  is  more  possible  when 
the  individual  has  full  knowicdf^e  of  the 
threatening  situation.  Ihe  existence  of 
well-established  habit  patlerns  also  helps. 
It  is  not  the  experienced  big-game  hunter 
who  feels  fear  when  faced  by  a  lion.  He 
has  met  the  situation  before,  knows  what  to 
do  and  acts  habitually  and  smoothly.  It  is 
the  neophyte,  hunting  for  the  first  time, 
who  becomes  frightened. 

Knowing  what  to  do  and  doing  it  is  the 
best  way  to  handle  fear.  As  we  have  seen, 
it  is  possible  that  all  the  complicated  re- 
sponse of  the  autonomic  nervous  system  in 
emotion  may  be  the  body's  way  of  organ- 
izing its  reserves  for  action.  To  fight  fear, 
use  what  the  autonomic  system  has  pro- 
vided, the  capacity  for  effective  action. 

Our  understanding  of  fear  has  been  con- 
firmed by  exhaustive  questioning  of  men 
who  have  returned  from  battle.  One  study 
of  4504  flyers  who  had  returned  to  this 
country  after  extensive  tours  of  combat  is 
particularly  enlightening.  These  flyers  re- 
ported the  usual  signs  of  fear  when  flying  a 
combat  mission.  They  experienced  a  rapid 
pulse  rate,  muscle  tension,  irritability,  dry- 
ness of  the  mouth,  sweating,  stomach  sensa- 
tions and  a  feeling  of  unreality.  Delayed 
symptoms  which  appeared  later  included 
fatigue,  restlessness,  depression,  over-reac- 
tion to  stimuli,  loss  of  appetite,  loss  of  zeal 
and  even  obsessive  thoughts. 

Their  fear  was  greatest  in  danger  when 
they  were  idle  or  unable  to  take  counter- 
action. Fear  was  reduced  by  confidence  in 
equipment  and  leadership,  goal-directed  ac- 
tivity and  social  stimulation.  Organiza- 
tional morale,  sense  of  duty,  hope  of  sur- 
vival and  personal  pride  were  motivating 
factors  which  were  much  more  successful  in 
reducing  fear  than  citations  for  bravery, 
pay,  self-advancement  and  hatred  of  the 
enemy. 


Anger 

Anger  is  the  normal  response  to  frustra- 
lion.  When  some  situation  or  another  per- 
son unduly  limits  the  freedom  of  action  of 
an  individual,  the  restrained  individual  is 
likely  to  become  angry.  He  may  then  at- 
tack the  obstacle  which  is  inhibiting  his 
freedom. 

I'hus,  the  condition  which  arouses  anger 
in  young  children  is  a  situation  which,  in- 
stead of  being  a  sudden  call  for  action,  is 
often  a  more  or  less  sudden  stoppage  or 
interference  with  action.  Interference  with 
activity,  especially  activity  motivated  by 
the  common  urges  or  drives,  is  an  essen- 
tial characteristic  of  the  anger-producing 
situation. 

The  anger  responses  in  the  child  are  out- 
bursts of  impulsive  activity— kicking,  stamp- 
ing, slashing  about  with  the  arms  and  often 
a  prolonged  holding  of  the  breath.  With 
increasing  age,  the  anger  becomes  more 
overtly  focused  upon  a  given  end.  Along 
with  a  decrease  in  the  proportion  of  out- 
bursts consisting  of  mere  displays  of  undi- 
rected energy  comes  an  increase  in  the  fre- 
quency of  retaliative  behavior.  The  per- 
centage of  observable  after-reactions,  such 
as  resentfulness  and  sulkiness,  increases 
steadily  with  advancing  age,  perhaps  in 
part  because  retaliation  is  not  always  prac- 
ticable or  carries  with  it  its  own  penalties. 

Mild  anger,  directed  toward  the  legiti- 
mate removal  of  some  barrier  obstructing 
individual  action,  may  well  become  an  im- 
portant moti\ator  of  beha^  ior.  Anger, 
however,  is  difficult  to  control  and  easily 
develops  into  disorganized  rage.  It  may, 
moreover,  call  forth  the  same  type  of  re- 
sponse from  tlie  object  against  which  it  is 
directed.  In  human  affairs  aggression 
tends  to  be  met  by  aggression,  and  the  re- 
sults are  disastrous  for  social  intercourse. 


106 


Feeling  and  Emotion 


Anger,  like  fear,  is  a  primitive  emergency 
response  which  energizes  the  individual. 
We  may  seriously  question  the  general 
serviceability  of  such  primitive  responses 
in  tlie  complex  social  organization  of  con- 
temporary life,  in  spite  of  the  occasional 
good  uses  for  righteous  anger  and  moral 
indignation. 

Anger  can  be  misdirected.  If  the  aggres- 
sion aroused  by  frustration  cannot  be  di- 
rected against  the  frustrating  situation  it- 
self, it  may  be  displaced  and  vented  upon 
a  substitute.  If  you  are  publicly  embar- 
rassed by  some  incident  about  which  you 
can  do  nothing,  you  may  suddenly  become 
angry  with  an  innocent  witness  of  the  af- 
fair. Majority  groups  may  thus  take  out 
their  aggressions  against  a  minority  group, 
and  within  the  minority  group  aggression 
in  turn  may  be  directed  against  some  poor 
individual  selected  as  a  scapegoat.  Beyond 
the  fact  that  such  substitute  reactions  may 
offer  emotional  relief  to  the  individual 
aroused,  misdirected  anger,  being  false, 
cannot  be  said  to  have  any  social  value. 

THE    MEASUREMENT    OF 
EMOTION 

The  importance  of  emotion,  both  as  be- 
havior itself  and  secondarily  as  an  indi- 
cator of  the  conscious  and  unconscious 
vital  concerns  of  the  individual,  has  led  to 
gieat  interest  in  its  measurement.  The 
participation  of  the  autonomic  nervous 
system,  with  its  attendant  changes  in  pulse 
rate,  blood  pressure,  breathing,  etc.,  has 
held  out  to  psychologists  the  hope  that 
measures  of  such  bodily  changes  might 
give  a  clear  measure  of  emotion.  Such 
hopes  have  not  been  fully  realized.  The 
autonomic  nervous  system  is  not  exclusively 
concerned  with  emotion,  and  its  complex 
organization  adds  further  to  the  difficulty; 


still,  measures  of  bodily  processes  are  our 
best  indicators  of  emotion. 

The  Galvanic  Skin  Response 

In  1888  the  French  scientists,  Vigouroux 
and  Fere,  called  attention  to  the  fact  that, 
when  electrodes  are  placed  on  the  skin  and 
attached  to  the  proper  electrical  measuring 
instruments,  variations  in  the  electrical 
properties  of  the  skin  appear  from  time  to 
time.  During  emotional  excitement,  they 
found,  there  is  an  increase  in  these  electii- 
tal  variations.  The  occiurence  of  these 
changes  has  been  named  the  galiianic  skin 
response  or  the  psychogalvanic  reflex,  a  phe- 
nomenon which  has  been  extensively  stud- 
ied by  many  investigators.  The  response 
was  first  called  prominently  to  the  attention 
of  psvchoiogists  by  the  work  of  C.  G.  fimg 
and  his  pupils,  who  came  to  tiie  general  con- 
clusion that  the  galvanic  skin  response  is  as- 
sociated with  repressed  emotional  com- 
plexes. \Vhether  this  electrical  response  is 
associated  with  physiological  and  psycholog- 
ical occurrences  other  than  emotion,  they 
did  not  particularly  consider.  Their  claim 
to  have  a  measure  of  emotion  was  accepted 
more  or  less  uncritically  by  many  psychol- 
ogists. More  recent  investigations  show, 
however,  that  these  electrical  responses 
occur  not  only  during  emotional  experience 
btit  also  to  some  extent  with  practically 
every  other  variety  of  psychological  experi- 
ence. Furthermore,  it  appears  that  the  de- 
gree of  electrical  change  does  not  measure 
accurately  the  amount  of  emotion  experi- 
enced by  the  individual. 

Blood  Pressure  Changes 

The  amount  of  inciease,  decrease  or 
variability  in  blood  pressure  has  been  used 
as  a  measure  of  emotionality.  Perhaps  the 
most  extensive  use  of  this  type  of  measure- 
ment has  been  in   the  detection  of  false- 


Measurement  of  Emotion 


107 


hood,  the  so-called  lie  deleclor  being  an  in- 
sirunient  lo  record  changes  in  blood  pres- 
sure. (Some  lie  detectors  record  the  gal- 
vanic skin  response  and  changes  in  lespira- 
tion  as  well.)  Under  certain  conditions  it 
seems  possible  on  the  basis  o£  the  changes 
in  the  record  of  blood  pressure  to  deter- 
mine whether  or  not  a  person  has  told  the 
truth  or  has  lied,  provided  always  that  he 
is  more  moved  when  lying  than  when  tell- 
ing the  truth.  It  has  not  been  jxjssible  lo 
standardize  this  procedure,  since  it  depends 
upon  so  many  variables  and  there  are  so 
many  different  factors  which  must  be  con- 
sidered in  the  interpretation  of  the  record. 
For  instance,  an  habitual  liar  may  be  cjuite 
unmoved  about  his  lies.  There  are,  more- 
over, people  who  can  convince  themselves 
by  their  own  lies  to  become  sincere  liars. 

In  a  study  of  blood  pressure,  made  on 
persons  who  had  suffered  severe  injmy  in 
automobile  accidents  and  upon  friends  and 
relatives  who  were  called  to  the  hospital  to 
see  them,  interesting  results  were  obtained. 
It  was  found  that  the  injined  individuals 
themselves,  who  had  undoubtedly  gone 
through  profoimd  physical  and  emotional 
shock,  did  not  show  very  much  alteration 
in  blood  pressure.  Their  friends  or  rela- 
tives, on  the  other  hand,  waiting  to  find 
out  how  severely  the  patients  had  been  in- 
jured, showed  a  tremendous  variability. 
Evidently,  then,  the  rise  in  blood  pressure 
frequently  accompanies  the  apprehensive 
state  preceding  some   possible   emergency. 

Rating  Scales 

The  failure  to  establish  good  physiolog- 
ical measures  of  emotion  has  led  to  the 
development  of  new  techniques.  A  com- 
mon one  is  the  rating  scale.  In  this  pro- 
cedure, we  ask  the  friends  and  acquaint- 
ances of  some  person  to  rate  his  emotion- 
ality or  emotional  expressiveness.     By  sta- 


tistical manipulation  of  tlic  data  it  is  j>ov 
sible  (o  obtain  some  idea  ol  the  probable 
emotional  reactivity  of  an  individual  in 
comparison  with  that  of  his  friends  and 
associates. 

Observational  and 
Psychoanalytic  Techniques 

Several  investigations  ol  emotional  re- 
actions, jjarticularly  with  children,  have 
been  made  by  the  observational  method. 
One  observer  watched  a  large  group  (j| 
children  on  the  playground,  following  their 
behavior  over  a  period  of  several  months. 
All  instances  of  anger,  fighting,  fear  or 
other  emotional  reactions  were  noted.  On 
the  basis  of  such  observational  studies,  we 
can  obtain  very  good  descriptions  of  ac- 
tual emotional  behavior,  the  stimuli  or 
situations  which  produced  the  behavior 
and  the  results  of  the  reactions.  Although 
it  has  been  foimd  possible  in  this  way  to 
predict  rather  acciu-ately  the  sort  of  situa- 
tion which  will  evoke  an  emotional  reac- 
tion in  a  particular  individual,  the  e\i- 
dence  shows  that  the  same  situation  is  not 
luiiformly  effective  in  producing  the  same 
reaction  in  all  indi\iduals  or  even  in  the 
same  individual  every  time. 

Psychoanalysis  provides  a  special  situa- 
tion under  which  emotion  can  often  be  ob- 
served in  adults.  In  such  an  analysis, 
which  consists  essentially  of  talking  in  a 
free  and  uninhibited  fashion  about  any- 
thing that  comes  into  the  mind,  \ery 
marked  emotional  reactions  sometimes  take 
place.  The  subject  may  respond  in  an  in- 
tense emotional  fashion  to  his  OA\n  descrip- 
tions of  events  long  past  and  previously  be- 
lieved forgotten.  By  such  methods  we  can 
acquire  much  knowledge  concerning  the 
emotional  history  of  the  person  being  ana- 
lyzed. 


108 


Feeling  and  Emotion 


Questionnaire  Methods 

An  entirely  different  method  of  meas- 
urement and  test  makes  use  of  tlie  ques- 
tionnaire, as,  for  example,  the  Pressey  X-O 
test.  Form  B.  This  test  consists  of  three 
lists  of  words.  In  the  first,  the  individual 
is  told  to  cross  out  everything  he  thinks  is 
Avrong;  in  the  second  list,  everything  about 
Avhich  he  has  ever  worried;  and  in  the 
third,  everything  he  likes  or  is  interested 
in.  He  is  also  told  to  encircle  the  crossed- 
out  word  in  each  line  which  he  considers, 
respectively,  to  be  the  worst,  the  most  wor- 
risome or  the  most  interesting.  The  total 
niunber  of  words  crossed  out  is  called  the 
score  of  emotionality,  since,  theoretically, 
the  more  things  a  person  dislikes,  worries 
about  or  likes,  the  more  generally  emo- 
tional he  is.  The  encircled  words  having 
been  compared  with  a  standard  list  that 
giAes  the  most  frequently  encircled  word 
for  each  line,  the  number  of  encircled 
words  which  deviate  from  this  standard  list 
is  the  score  of  idiosyncrasy.  Various  inves- 
tigators have  reported  that  students  who 
obtain  high  scores  of  emotionality  and 
idiosyncrasy  tend  to  have  more  than  the 
usual  nuinber  of  emotional  conflicts  in 
school. 

DISORDERS    OF    EMOTION 

Like  the  other  bodily  processes  the  emo- 
tional mechanisms  sometimes  fail  to  func- 
tion correctly.  The  trouble  may  be  some 
physiological  or  organic  disorder,  such  as 
a  wrong  functioning  of  a  gland  or  a  dis- 
order of  the  nervous  system.  Such  disturb- 
ances can  be  classified  as  the  pathology  of 
emotion.  On  the  other  hand,  if  the  cause 
is  not  organic  but  arises  from  faulty  learn- 
ing or  poor  habits  of  adjustment,  we  call 
the      disturbances     functional      disorders. 


Often  both  functional  and  organic  dis- 
abilities occur  together  in  relation  to  each 
other,  as  in  the  problems  of  psychosomatic 
medic  itJe. 

Pathological  Conditions 

Since  emotional  behavior  is  mediated  by 
the  nervous  system,  it  can  be  ujjset  by  any 
injury  or  disease  which  affects  the  pertinent 
parts  of  the  nervous  system.  Tumorous 
growths  in  the  thalamic  or  hypothalamic 
regions  of  the  brain  may  produce  uncon- 
trollable weeping  or  laughing.  The  re- 
moval of  large  areas  of  cortical  brain  tissue 
has  been  known  to  result  in  an  apparent 
lessening  of  social  inhibitions  with  result- 
ing inappropriate  and  embarrassing  emo- 
tional behavior  of  a  sort  previously  inhib- 
ited by  the  individual.  Glandular  dis- 
functions may  also  unbalance  the  emo- 
tional behavior.  Feelings  of  anxiety, 
which  may  be  accompanied  by  terror  night- 
mares, are  often  found  in  advanced  cases 
of  hyperthyroidism. 

Extreme  emotional  states  are  also  promi- 
nent in  the  symptoms  of  the  major  mental 
disorders.  Extreme  euphoria,  an  abnor- 
mally strong  sense  of  well-being,  happiness, 
and  exaggerated  self-confidence,  is  found  in 
the  manic  patient,  and  sometimes  in  gen- 
eral paresis.  Both  the  depressive  phases  of 
manic-depressive  psychosis  and  of  involti- 
tional  melancholia  include  persistent  deep 
depressions  which  are  accompanied  by  tn> 
happiness,  anxiety,  apprehension  and  oc- 
casional thoughts  of  self-destruction. 

In  schizophrenia,  or  dementia  praecox, 
we  may  find  apathy,  a  relative  dulling  of 
emotional  response.  The  patient  does  not 
show  a  normal  emotional  interest  in  and 
response  to  his  environment.  Such  a  pa- 
tient  might  commit  a  crime,  even  murder, 
%v'ithout  the  emotional  conflict  ^s'hich  stich 
beha\'ior  would  cause  in  the  normal  indi- 


Disorders  of  Emotion 


109 


vidua].     Wc  describe  such  emotional   apa- 
tliy  as  a  blunting  of  affect. 

Functional  Disorders 

Some  emotional  disorders  are  not  due 
to  physiological  disorder  but  must  be  con- 
sidered as  inappropriate  behavior  produced 
by  unusual  experiences  in  the  individual's 
past.  Phobias,  or  unusually  strong,  per- 
sistent fear  reactions,  are  an  example.  As 
we  have  already  noted,  the  examination  of 
Naval  recruits  who  were  nonswimmers 
showed  that  many  of  them  had  developed 
a  phobia  for  water  because  of  soine  trau- 
niatic  experience  with  swimming  or  water 
in  the  past. 

Phobias  may  appear  to  occur  without 
reason  and  remain  inexplicable  to  the  in- 
dividual suffering  from  them.  They  handi- 
cap his  adjustment  and  limit  his  activities. 
They  are  often  found  in  exaggerated  form 
in  the  psychoneuroses. 

Anxiety,  which,  as  we  have  already  noted, 
normally  functions  as  a  forerunner  of  some 
anticipated  dangerous  situation,  may  also 
get  out  of  hand  and  may  so  dorninate  the 
individual's  behavior  that  he  is  vmable  to 
take  any  logical  action  concerning  the  situ- 
ation which  produces  the  anxiety.  Thus 
the  student  who  is  anxious  and  worried 
about  an  examination  may  become  so  up- 
set as  to  be  unable  to  study.  His  inability 
to  study  increases  his  feeling  of  unpre- 
paredness  which  in  turn  increases  his  anx- 
iety, and  he  is  caught  in  a  viciotis  circle. 
Next  time  he  had  better  schedule  his  work 
so  that  he  does  not  get  caught  so  unpre- 
pared or  he  might  make  some  other  intelli- 
gent administrative  changes  in  his  life  of 
study.  In  general,  the  best  way  to  handle 
anxiety  is  by  a  frontal  attack  upon  the 
problem  causing  it. 

In  many  maladjusted  individuals,  how- 
ever, the  basic  reasons  for  the  anxiety  may 


be  repressed  and  unconscious.  The  pers<^jn 
is  then  faced  with  a  persistent  worry  or 
apprehension  which  colors  all  his  emo- 
tional life  and  about  which  he  is  unable  to 
do  anything  since  he  cannot  unflerstand  its 
origin.  In  such  cases,  psychiatric  counsel- 
ing may  be  necessary  to  uncover  the  source 
of  the  basic  insecurity  or  inferiority  caus- 
ing the  anxiety. 

Anxiety  very  frecjuently  has  a  profound 
effect  ujjon  the  physiological  functions  of 
the  individual.  Persistent  respiratory,  cir- 
culatory, digestive  or  muscular  disturb- 
ances may  occur.  Chronic  fatigue  accom- 
panied by  insomnia  is  also  common. 

The  effect  of  anxiety  on  psychological 
functions  is  to  lower  the  general  acuity  and 
completeness  of  response.  Although  the 
individual  still  reacts,  he  does  so  either  in  a 
preoccupied  fashion,  paying  attention  to 
only  part  of  what  is  going  on  around  him, 
or  inadequately,  as  though  he  were  fa- 
tigued or  had  instifficient  energy  to  meet 
the  demands  of  the  situation.  Since  anxiety 
is  a  rather  common  human  experience,  a 
great  deal  of  medical  work  has  been  done 
in  the  attempt  to  control  or  alleviate  it. 
Generally  speaking,  if  in  one  way  or  an- 
other the  anxious  person  can  be  made  to 
discover  the  original  connection  between 
his  anxiety  and  its  primary  or  original 
cause,  he  will  be  able  either  to  free  him- 
self of  the  anxiety  or  to  control  it  in  a 
satisfactory  fashion.  (For  more  on  phobias 
and  anxieties,  see  pp.  531-534.) 

Psychosomatic  Medicine 

We  have  already  seen  that  emotion  in- 
volves activity  of  the  autonomic  ner^•ous 
system  and  hence  a  profound  change  in 
the  activity  of  the  vital  organs.  Inaeased 
pulse  rate,  increased  blood  pressure,  irregu- 
larities in  respiration  and  interference  witli 
dia;estion  may  all  result.     Wliere  the  emo- 


no 


Feeling  and  Emotion 


tion  perse\'eres  o\er  a  period  of  time,  as 
it  does  in  chronic  worry  or  anxiety,  it  may 
result  in  a  persistent  disturbance  of  vital 
function.  Modern  medicine  has  finally 
realized  that  many  disorders  of  digestion, 
respiration  and  heart  function  are  at- 
tributable, not  to  organic  difficulties,  but 
to  emotional  disorders.  They  must  be 
treated  by  treating  the  individual's  prob- 
lems of  psychological  adjustment  which 
are  causing  the  emotional  disturbance  re- 
sponsible for  the  physical  symptoms.  Thus 
a  wliole  new  branch  of  medicine,  psychu- 
somntic  medicine,  has  arisen  to  handle 
these  problems. 

It  must  be  remembered,  however,  that  if 
such  finictional  disorders  continue  they  may 
in  time  result  in  organic  damage  to  the 
ijodily  system  involved.  A  chronic  fear 
may  produce  the  persistent  diarrhea  known 
as  colitis,  and,  if  such  diarrhea  persists, 
ulceration  of  the  colon  may  residt.  After 
the  ulcer  has  formed,  psychological  treat- 
ment alone  has  become  insufficient. 

HYGIENE    OF    EMOTION 

In  the  preceding  pages  emotion  has  been 
pictured  both  as  a  helpful  reinforcing  agent 
which  energizes  and  motivates  man  when 
he  is  faced  with  some  threatening  emer- 
gency and  as  a  disrupting  force  which  dis- 
organizes his  behavior  and  confuses  his 
thinking  at  a  moment  of  crisis.  Actually 
it  is  both.  The  answer  to  whether  emo- 
tion is  helpful  or  harmful  depends  on 
whether  the  emotion  is  appropriate  to  the 
situation  in  which  the  individual  finds 
himself. 

The  question  of  the  appropriateness  or 
inappropriateness  of  a  specific  emotional 
response  must  be  settled  by  the  individual 
himself  after  a  consideration  of  all  the 
important  circumstances  entering  into  the 


specific  stimidus  situation  of  the  moment. 
Psychology  can  only  offer  us  broad  truths, 
but  every  man  must  apply  them  to  his  own 
particular  needs  at  any  specific  time.  The 
description  of  emotion  which  this  chapter 
contains  has  in  it  much  of  value  to  govern 
us  in  imderstanding  and  controlling  our 
emotions.  We  want  to  be  able  to  have 
appropriate  emotions,  to  dispense  with  the 
inappropriate  ones.  How  can  we  tell  the 
two  apart;  decide  about  appropriateness? 
Here  are  three  principles  which  may  help. 

(1)  Emotion  is  inappropriate  if  it  is 
harmful  to  the  biology  of  the  indixndual. 
No  intelligent  person  should  allow  himself 
the  luxiuy  of  flying  into  a  severe  rage  im- 
mediately after  eating  a  full  meal.  Nor 
can  fear  or  anxiety  be  considered  desirable 
in  an  individual  who  is  suffering  from 
stomach  ulcers,  high  blood  pressine  or  a 
colitis  of  functional  origin. 

(2)  Emotion  is  inappropriate  if  it  arouses 
conflicting  motivations  within  the  individ- 
ual. If  we  allow  ourselves  to  become  angry 
with  those  we  love,  we  are  plunged  into  a 
bitter  and  disrupting  conflict  within  our- 
selves. The  soldier  who  is  possessed  of  an 
overwhelming  fear  of  death  while  being 
driven  at  the  same  time  by  an  equally 
strong  desire  not  to  let  his  comrades  down 
may  succumb  to  a  mental  breakdown  din- 
ing combat. 

(3)  Emotion  is  inappropriate  if  it  brings 
the  individual  in  conflict  ivith  society. 
There  are  innmnerable  social  codes  that 
control  emotional  behavior  and  they  must 
be  respected  if  the  individual  is  to  live  in 
harmony  with  his  neighbors.  A  frank  ex- 
pression of  fear  at  an  inappropriate  time 
may  result  in  a  man's  being  branded  a 
coward  and  subjected  to  the  ridicule  of  his 
comrades.  However  strong  the  provoca- 
tion, the  enlisted  man  who  strikes  an  offi- 
cer must  face  severe  disciplinary  measures. 


Hygiene  of  Emotion 


111 


The  overt  dcnionstralioii  ol  allcction   may 
not  be  considered  proper  in   public. 

Unfortunately,  these  principles  do  not 
always  coincide.  Anger  in  response  to  an 
insult  may  be  considered  socially  accejH- 
able,  and  the  failure  to  exhibit  it  may  re- 
sult in  the  person's  feeling  he  has  lost  caste 
and  in  being  plunged  into  an  unhappy 
personal  conflict  within  himself.  Never- 
theless, such  justifiable  anger  may  be  lethal 
to  an  individual  afflicted  with  a  severe  heart 
disorder.  The  answer  to  such  dilemmas  is 
not  an  easy  one,  but  on  it  rests  the  deci- 
sion as  to  whether  our  emotions  are  bene- 
ficial or  liarmful,  and  on  it  rests  in  large 
part  our  cliances  for  happiness. 

REFERENCES 

1.  Bard,  P.  liniolion:  I.  The  ncino-luimoral  Iiasis 
of  emotional  reactions.  In  C.  Mmxhison  (Ed.), 
A  handbook  of  general  cxpcriinenlal  psy- 
chology. Worcester,  Mass.:  Clark  University 
Press,  1934.     Chap.  6. 

In  need  of  revision  but  still  a  standard  icih 
nical  reference  on  the  ncuro-lunnoral  basis  of 
emotion. 

2.  Beebe-Centev,  J.  G.  The  psychology  of  pleas- 
antness and  unpleasantness.  New  York:  D.  Van 
Nostrand,   1932. 


I  he  only  adc(jiialc  vjukc  \><x>i  for  the  cx- 
|)(  riiri<nl;il   lilciiil  iiic  in  rhis  field. 

3.  (Gannon,  W.  15.  liodily  chiuiges  in  pain,  hun- 
ger, fear  anil  rage.  (2nd  cd.;  .New  Vork: 
Applcton,   1929. 

An  historical  classic  still  very  iriiicli  woith 
reading  as  the  basis  of  the  emergency  theory 
ol   emotion. 

I.  jersild,  A.  T.  Kmotional  development.  Jn  L. 
Carniichael  (Ed.),  Manual  of  'child  psycholo^-. 
New  \ork:  Wiley,  1946. 

An  excellent  survey  of  the  lileialiirc  on  the 
development  of  emotion   in  the  child. 

5.  Landis,  C.  Emotion:  If.  The  expressions  of 
emotion,  fn  C.  iVfurchison  (Ed.)  ,  A  handbook 
of  general  experimental  psychology.  Worcester, 
Mass.:  Clark  University  Press,  1931.  Chap.  7. 
An  excellent  survey  of  the  experimental  find- 
ings on  cmolion   up  to   1931. 

G.  Landis,  C,  and   Hunt,  W.  A.     The  startle  pat- 
tern.     New    'iork:    I'arrar    and    Hi'iehart,    1939. 
An   intensive  study   of   the   reflex  response  in 
startle  based  upon   the  use  of  ultra-rapid  pho- 
tography. 

7.  Ruckmick,  C.  .\.  The  psychology  of  feeling 
and  emotion.     New  York:    McGraw-Hill,    1936. 

Somewhat  outmoded  as  a  survey  of  emotion, 
but  valuable  for  its  historical  material. 

8.  Yoting,  P.  T.  Emotion  in  man  and  animal. 
New  York:   Wiley,   1943. 

A  treatment  of  emotion  with  particidar  stres: 
on  its  relations  to  drive  and  motivation. 


CHAPTER 


Motivation 


THIS  chapter  is  concerned  with  what  the 
layman  usually  considers  the  most  impor- 
tant problem  of  psychology.  The  question 
which,  above  all  others,  he  wants  psychol- 
ogy to  answer  for  him  is,  "Why  do  people 
act  as  they  do?"  Not  satisfied  with  a  mere 
description  of  man's  behavior,  he  wants  to 
know  the  motives  back  of  it.  The  problem 
of  motivation,  narrowly  conceived,  is  the 
problem  of  discovering  the  motives  of  hu- 
man beings;  but,  broadly  viewed,  it  is  the 
problem  of  determining  the  forces  which 
impel  or  incite  all  living  organisms  to 
action. 

NEEDS 

We  cannot  long  study  the  behavior  of 
living  organisms  without  observing  that 
they  need  things;  and  it  is  their  wants, 
lacks  or  needs  which  have  to  be  investi- 
gated if  the  reasons  for  their  behavior  are 
to  be  discovered.  The  things  which  they 
need,  however,  vary  greatly,  not  only  from 
species  to  species,  but  also  from  individual 
to  individual  within  the  same  species. 
Oysters  do  not  need  automobiles  and  men 
do  not  need  shells;  but,  if  they  are  to  con- 
tinue to  live,  oysters  and  men,  like  all  other 
living  organisms,  need  to  get  from  their 
environments  a  continuous  supply  of 
energy  and  materials.  The  needs  of  the 
amoeba  arc  limited  to  these  vital  ones, 
'lliis  cliiiplcr  \\:is  |)r(']);ii((l   h\  Donald  \V. 


The  needs  of  man,  on  the  other  hand,  are 
ever  so  much  more  numerous.  He,  too,  has 
vital  needs.  He  needs  to  breathe  oxygen, 
to  eat  food,  to  drink  water,  to  eliminate 
wastes  from  his  body,  to  maintain  a  rela- 
tively constant  body  temperature.  But,  in 
addition  to  these,  he  has  other  needs  which 
cannot  be  considered  so  vital  or  so  uni- 
versal. He  may  need  to  have  more  money 
than  anyone  else  in  his  town,  he  may  need 
to  be  loved  by  a  particular  person,  he  may 
need  to  be  constantly  praised  and  ap- 
plauded. 

Distinction  among  Needs 

There  are  important  respects  in  which 
xiital  and  nonvital  needs  are  different, 
though  in  other  respects  they  have  much 
in  common. 

The  vital  needs  are  primary  and  innate 
in  the  sense  that  they  are  the  first  needs 
of  the  organism.  If  they  remain  unsatis- 
fied, the  organism  does  not  live  to  develop 
nonvital  needs  as  a  result  of  experience. 
In  this  sense,  nonvital  needs  are  secondary 
and  acquired.  This  distinction  does  not 
mean,  however,  that  secondary  needs  are 
necessarily  weaker  or  less  important  than 
primary  ones.  The  terms  primary  and  sec- 
ondary apply  only  to  the  origins  of  needs 
and  imply  nothing  about  their  relative 
strengths.    The  need  to  possess  great  wealth 

MacKinnon   of   llic   University  ol  California. 
12 


Needs 


113 


may  be  so  iiuidi  slroiif^cr  in  a  man  than 
his  needs  lor  lood  and  rest  and  exercise 
that,  even  though  he  succeeds  in  amassing 
great  wealth,  he  may  so  break  his  health  as 
to  die.  In  such  a  case  the  secondary  need 
lor  possessions  is  obviously  stronger  than 
the  primary  vital  needs  which  are  frus- 
trated. Furthermore,  the  distinction  be- 
tween primary  and  secondary  needs  does 
not  imply  that  the  latter  are  always  in  the 
service  of  the  former.  The  example  just 
cited  shows  that  such  is  not  the  case.  The 
amassing  of  great  wealth  (a  secondary  need) 
may  be  an  end  in  itself  and  not  necessarily 
a  means  to  the  certain  and  more  adecjuate 
satisfaction  of  the  need  for  food  or  of  any 
other  primary  need. 

lliere  is  a  sense,  then,  in  which  a  sec- 
ondary need  may  be  more  vital  for  the 
continued  existence  of  an  individual  than 
a  primary  need.  It  is,  for  example,  not 
uncommon  for  a  man  to  commit  suicide 
because  he  has  lost  his  fortune  in  a  crash 
of  the  stock  market  or  because  he  has  lost 
his  honor  through  becoming  involved  in  a 
public  scandal.  For  such  persons  life  with- 
out money  or  life  without  honor  is  impos- 
sible. In  a  A'ery  real  sense  their  secondary 
needs  have  become  vital  ones. 

The  primary  needs  are  sometimes  called 
physiological  needs  and  the  secondary  ones, 
psychological  needs.  This  does  not  mean 
that  the  secondary  psychological  needs  lack 
the  physiological  basis  in  the  body  which 
the  primary  physiological  needs  have,  but 
merely  that,  in  general,  we  know  more 
about  the  specific  physiological  basis  of  pri- 
mary than  of  secondary  needs.  We  know, 
for  example,  that  the  physiological  basis 
of  the  need  for  food  is  a  matter,  in  part,  of 
a  reduction  of  the  sugar  concentration  of 
the  blood  and  consequent  contractions  of 
the  smooth  muscle  of  the  stomach:  and  we 
know  at  least  something  about  the  physio- 


logical basis  (A  ilic  oilier  so-called  physio- 
logical needs,  liut  what  the  physiological 
basis  of  a  man's  need  for  superiority  may 
be,  or  of  any  other  of  his  socalled  psycho- 
logical needs,  we  do  not  know.  We  as- 
sume, however,  that  they  have  a  physio- 
logical basis  even  though  we  cannot  demon- 
strate it. 

On  the  other  hand,  the  distinction  be- 
tween physiological  and  psychological  needs 
does  not  mean  that  the  psychological  needs 
have  a  representation  in  consciousness 
which  is  absent  in  physiological  needs.  We 
may  be  just  as  much  aware  of  our  need  for 
food  as  we  are  aware  of  our  need  to  pass 
a  crucial  examination;  and  we  may,  at  an- 
other time,  be  just  as  unaware  of  our  need 
to  get  even  with  a  person  for  a  slight  which 
he  has  given  us  as  we  are  una\\are  of  our 
need  for  vitamin  B.  Physiological  and 
psychological  needs  are  alike  in  that  both 
may  be  at  certain  times  known  but  at  other 
times  unrecognized. 

The  primary  needs  are  sometimes  re- 
ferred to  as  biological  needs  because  they 
have  biological  origins.  The  secondary 
needs  are  sometimes  called,  in  contrast, 
social  needs  because  they  are  the  products 
of  social  life.  Though  this  is  a  valid  dis- 
tinction among  needs,  we  must  not  over- 
look the  fact  that  social  needs  are  also  bio- 
logical in  the  sense  that  they  are  needs  of 
biological  organisms  and  that  biological 
needs  are  also  social  in  that  the  expres- 
sions of  these  needs  are  to  a  large  extent 
socially  determined.  All  men  need  food, 
but  the  particular  objects  Avhich  -svill  satisfy 
this  need  vary  widely  from  one  society  or 
culture  to  another.  Religious  taboos  and 
cultural  prohibitions  limit  greatly  tJie  num- 
ber of  objects  whicli  will  satisfv  an  indi- 
vidual's need  for  food. 

W^e  have  seen  that  needs  are  of  twc 
kinds:  first,  needs  which  are  primary,  vital 


114 


Mofivation 


physiological  and  biological  and,  second, 
needs  which  arc  secondary,  nonvital,  psy- 
chological and  social.  But  we  have  seen 
also  that,  valid  as  these  distinctions  be- 
tween the  two  classes  of  needs  are,  they  are 
not  rigid.  All  needs  have  much  in  com- 
mon. It  is  this  fact  which  makes  it  pos- 
sible for  psychologists  to  seek  the  general 
laws  of  need  regardless  of  the  particidar 
need  studied. 

Needs,  Structure  and  Environment 

All  organisms  have  the  primary  need  for 
oxygen,  but,  although  they  have  this  need 
in  common,  they  satisfy  it  in  different  ways. 
The  hsh  supplied  with  gills  and  living  in 
water  gets  oxygen  in  one  way;  man  sup- 
plied with  lungs  and  living  on  land  gets 
his  in  a  different  manner.  The  ways  in 
which  an  organism's  needs  may  be  satis- 
fied are  determined  by  its  structure  as  well 
as  by  the  nature  of  its  environment.  This 
relationship  is  no  less  valid  for  secondary 
needs.  A  common  need  in  a  highly  com- 
petitive society  is  the  need  to  be  or  to  feel 
superior  to  others,  but  it  may  be  satisfied 
in  very  different  ways.  A  person  skillful  in 
athletics  may  gain  his  superiority  by  ex- 
celling in  sports;  a  man  of  puny  body  but 
keen  intellect  may  gain  his  feeling  of  supe- 
riority by  scholastic  excellence. 

Behavior  which  is  motivated  by  need  de- 
pends then  upon  the  following  three  fac- 
tors. 

(1)  The  need  itself,  conceived  of  as  a 
want  or  lack  in  the  organism,  involving 
always  a  physiological  disequilibrium  or  a 
tension  which  tends  to  discharge  in  beha- 
vior in  such  a  way  as  to  bring  about  a 
restoration  of  the  equilibrium  which  was 
disturbed  by  the  need.  (See  pp.  511-514 
on  tension  reduction.)  Su(h  physiological 
disc(juili!)ria     are     to     be     (onsidered     llic 


sources  of  the  stinudation  which  drive  the 
organism  to  action. 

(2)  The  structure  of  the  organism,  which 
determines  to  an  important  degree  not  only 
the  needs  of  the  organism  but  also  the  man- 
ner in  which  they  will  be  satisfied.  Here 
are  to  be  considered  certain  mechanisms- 
gills  as  against  hmgs,  the  claw  of  the  lobster 
as  against  the  hand  of  a  man— as  well  as 
the  sensory  organs  and  nervous  system 
which  mediate  the  perception  of  needed 
objects  and  the  muscles  and  glands  which 
are  organized  into  systems  of  response. 

(3)  The  enviromneni  of  the  organism 
and  the  objects,  present  in  the  environment 
or  absent  from  it,  which  are  retjuired  for 
the  satisfaction  of  any  need.  Here  both  the 
social  and  the  physical  environment  have 
to  be  considered. 

Any  concrete  case  of  behavior  is  deter- 
mined by  the  interrelated  fimctioning  of 
all  three  of  these  factors;  it  is  only  by 
adopting  an  analytical  attitude  that  they 
can  be  discussed  separately.  Later  we  shall 
consider  them  in  their  interrelation. 

THE    PHYSIOLOGICAL    BASIS 
OF    BEHAVIOR 

The  psychologist  has  long  considered 
that  one  of  his  problems  is  the  determina- 
tion of  the  conditions  in  bodily  tissues 
which  release  energy  so  as  to  stimulate  the 
organism  to  overt  activity.  He  has  sotight 
to  determine  the  precise  correlation  be- 
tween these  known  conditions  and  activity, 
both  general  and  specific,  and  having  found 
such  correlations  he  has  developed  the  con- 
cept of  drive,  which  he  defines  as  an  intra- 
organic activity  or  condition  of  tissue  sup- 
plying sliiuulation  for  a  particular  type  o' 
behavior. 


Hunger  Drive 


115 


Hunger  Drive 

riic  lollowing  Ijicts  arc  known  iiIkhH  ilic 
pliysiology  ol  the  Imnger  dritic.  When 
the  sugar  (onccnlration  ol  the  blood  is  re- 
duced below  a  (crtaui  level,  vigorous  con- 
tractions ot  the  stomach  ensue.  These  con- 
tractions of  the  smooth  muscles  ot  the 
stomach  wall  are  the  physiological  con- 
comitants of  tlie  conscious  pangs  of  hunger. 
This  latter  fact  has  been  demonstrated  by 
having  subjects  swallow  a  tube  to  the  end 
of  which  a  rubber  balloon  is  attached. 
Wlien  the  balloon  is  in  the  stomach,  it  is 
inflated  and  the  tube  connected  to  a  record- 
ing apparatus  so  as  to  give  a  graphic  record 
of  the  stomacli  contractions,  f  f  under  these 
conditions  subjects  are  instructed  to  press 
a  signal  key  whenever  a  pang  of  hunger 
is  experienced,  it  is  found  that  their  stom- 
ach contractions  and  liunger  pangs  coin- 
cide. These  experiments  have  been  car- 
ried further  to  determine  the  relation  be- 
tween stomacli  contractions  and  general 
bodily  activity.  Subjects  were  asked  to  re- 
cline on  a  bed  so  constructed  as  to  yield  a 
graphic  record  of  their  movements— even 
so  slight  a  movement  as  that  of  a  single 
finger.  By  taking  simultaneous  records  of 
bodily  activity  and  stomach  contractions 
both  when  ttie  subjects  were  asleep  and 
when  quietly  reading,  a  very  close  correla- 
tion between  the  rhythmic  contractions  of 
the  smooth  muscle  of  the  stomach  and  bod- 
ily activity  was  demonstrated. 

Just  as  the  altered  chemical  state  of  the 
blood  consequent  upon  the  reduction  of  its 
sugar  concentration  affects  the  stomach, 
setting  up  the  vigorous  contractions  of  the 
smooth  muscle,  so  these  contractions  in 
turn  set  up  nervous  impulses  which  make 
for  an  increase  of  bodily  activity.  Hungry 
persons  are  restless. 


I'.odily  (ondiiions  such  as  those  just  de- 
scribed are  correlated,  however,  not  only 
with  ;in  in(reasc  in  general  bodily  activity 
but  ;dso  uiih  specific  activity  directed  to- 
ward the  satisfaction  of  the  momentary 
need.  J  he  hungry  jjerson  seeks  food  and 
eats  it  when  he  finds  it.  The  thirsty  one 
seeks  water  and  drinks  it  if  he  gets  it. 

Although  this  activity,  both  general  and 
specific,  has  been  found  to  be  associated 
with  sudi  specific:  internal  conditicjns  as 
stcjmach  contracticjns,  there  are  a  number 
of  experiments  which  have  demonstrated 
that  the  activity  may  likewise  occur  in  the 
absence  of  the  usually  associated  physio- 
logical state.  Rats  in  which  practically  all 
the  contractile  tissue  of  the  stomach  has 
been  removed  or  in  which  the  nerves  be- 
tween the  stomach  and  the  brain  have  been 
severed  are  still  motivated,  when  deprived 
of  food,  to  seek  food  and  ingest  it.  A 
hungry  hen  placed  before  a  heap  of  giain 
will  eat  a  certain  amount  and  stop,  though 
there  is  still  more  food  before  her.  Never- 
theless, the  hen  can  be  motivated  to  eat 
again— this  time  in  the  absence  of  anv 
stomach  contractions— if  the  remaining  food 
is  removed  and  immediately  replaced. 
With  some  hens  this  process  can  be  i^epeated 
as  many  as  eight  times.  In  the  light  of 
such- evidence  we  cannot  assume  that  stom- 
ach contractions  are  always  and  necessarih 
the  source  of  stimulation  which  motivates 
the  hen  to  eat.  In  this  case  the  percep 
tion  of  the  food  presented  is  alone  sufficient 
to  stimulate  eating. 

In  another  experiment  the  amoimt  of 
grain  that  a  hen  will  eat  spontaneoush 
after  a  twenty-four-hour  fast  Avas  deter- 
mined. The  hen  was  then  presented  after 
a  similar  fast  with  a  heap  of  grain  larger 
than  before.  If  ordinarily  the  hen  eats 
fifty  gi-ains   from   a   heap  of  one  hundred 


116 


Motivation 


grains  of  wheat,  from  a  larger  heap  she  -will 
eat  thirty-five  to  fifty  grains  more.  Since 
presumably  the  chemical  state  of  the  blood 
and  the  condition  of  the  tissues  of  the 
stomach  are  about  the  same  under  both 
conditions,  the  increase  in  eating  must  be 
determined  by  neither  of  these  factors  but 
by  the  increase  in  the  size  of  the  heap  and 
by  whatever  physiological  changes  result 
from  the  perception  of  this  fact. 

Or  again,  if  a  hen  eats  until  satisfied  and 
remains  motionless  in  front  of  a  pile  of 
grain,  she  will  begin  to  eat  once  more  if  a 
hungry  hen  introduced  into  the  situation 
starts  to  eat.  And  like  hens  we,  too,  will 
start  to  eat  again  if,  having  eaten  our  fill, 
we  are  joined  by  hungry  friends. 

Such  observations  as  these  indicate  how 
necessary  it  is  to  consider,  in  addition  to 
the  internal  sources  of  stimulation  in  the 
stomach  wall,  the  environmental  factors 
which  may  also  stimulate  the  organism  to 
eat.  Objects  which  in  the  past  have  been 
present  when  physiological  hunger  has 
driven  the  organism  to  eat,  or  situations  in 
which  eating  has  occurred,  may,  because  of 
their  connection  with  previous  eating,  be- 
come adequate  in  their  own  right  to  stimu- 
late the  same  behavior  on  later  occasions. 
Thus,  we  eat  when  we  see  others  eating; 
we  eat  more  when  more  food  is  presented 
to  us;  and  we  eat,  in  everyday  life,  long  be- 
fore we  are  driven  to  do  so  by  the  goading 
pangs  of  hunger.  Once  we  develop  habits 
of  eating  certain  things  at  certain  times  and 
in  certain  places,  the  appearance  of  these 
things,  at  these  times  and  in  these  places, 
alone  suffices  to  make  us  eat. 

Sex  Drive 

Sexual  desire  waxes  and  wanes  in  cycles. 
There  are  life  cycles:  the  specific  desire  for 
the  sexual  act  does  not  characteristically 
arise  until   the  animal   is  sexually  mature 


or  in  man  imtil  puberty,  and  in  old  age  the 
desire  weakens.  There  are  seasonal  cycles 
for  many  animals:  some  mate  only  in  the 
spring,  others  in  the  spring  and  fall.  And 
there  is  also  the  estrus  cycle  in  female  mam- 
mals, the  period  of  recmrent  'heat'  when 
females  are  receptive  to  the  advances  of 
males.  This  sexual  receptivity  occurs  at 
the  time  when  the  o\a  or  female  germ  cells 
become  matiue  and  seems,  indeed,  to  be 
dependent  upon  the  process  of  their  growth 
and  development.  The  period  of  heat  is 
also  a  period  of  increased  activity.  Female 
rats  have  been  placed  in  cages  with  'activity 
wheels,'  like  those  provided  for  the  exer- 
cise of  squirrels,  and  the  activity  of  the 
animals  has  been  measm-ed  by  the  num- 
ber of  revolutions  of  the  wheels  per  unit 
of  time.  Mechanical  counters  keep  the 
record.  Although  a  female  rat  ordinarily 
rims  about  a  mile  a  day,  it  is  not  imusual 
for  her,  every  fourth  or  fifth  day  at  the 
peak  of  the  estrus  cycle,  to  run  as  much  as 
fifteen  miles  in  a  day.  Sexual  drive,  like 
the  hunger  drive,  gives  rise  to  general  acti^•- 
ity  as  well  as  specific. 

In  the  absence  of  certain  hormones- 
hormones  secreted  by  the  gonads  or  sex 
glands  and  by  the  pituitary  gland— there 
is  little  sexual  drive  in  the  higher  animals. 
The  testes  of  the  male,  in  addition  to  form- 
ing the  male  germ  cells,  the  sperms,  secrete 
hormones  called  androgens,  and  the  ovaries 
of  the  female,  besides  producing  the  fe- 
male germ  cells  or  ova,  secrete  hormones 
that  are  known  as  estrogens.  These  hor- 
mones are  most  immediately  responsible  for 
sexual  desire,  but  hormones  secreted  by  the 
pituitary  gland  located  at  the  base  of  the 
brain  also  determine  the  strength  of  the 
sex  drive,  since  they  in  turn  stimidate  the 
secretion  of  the  androgens  and  estrogens. 
In  fact,  the  pituitary  gland  and  the  gonads 
act  reciprocally.     Pituitiiry  secretion  stimu- 


Sex  Drive 


117 


lilies  f^(jii;i(l;il  secretion,  which  in  luin  acis 
lo  (h'lninish  pituitary  secretion,  a  process 
(ailed  honicuslasis,  by  which  the  proper 
i)alance  of  the  sex  hormones  is  maintained 
in  the  body. 

The  role  of  the  pituitary  gland  and  the 
gonads  in  the  sexual  need  and  behavior  of 
higher  animals  can  be  demonstrated  in  a 
lumiber  of  ways.  In  female  rats,  for  ex- 
ample, the  increased  activity  at  the  time 
of  the  estrus  cycle  appears  at  puberty  and 
disappears  at  menopause.  Removal  of  the 
ovaries  reduces  general  activity  and  abol- 
ishes the  activity  cycle.  Injection  of  estro- 
gens will,  on  the  other  hand,  restore  the 
cyclical  behavior  as  will  also  replacement 
of  the  ovaries  by  grafting.  Similarly,  the 
removal  from  an  animal  of  that  part  of  the 
pituitary  gland  which  secretes  the  gonad- 
stimulating  hormones  results  in  a  loss  of 
sexual  drive  unless  gonadal  hormones  are 
artificially  introduced  into  the  animal's 
blood  by  injection.  When  the  testes  are 
removed  from  male  rats  and  ovaries  sub- 
stitiUed  for  them,  typically  female  cycles 
and  le\'els  of  activity  appear  in  the  male. 

The  sex  drive  of  the  male  rat,  as  well  as 
that  of  other  male  mammals,  does  not  ap- 
pear vmtil  puberty.  Castration  after  pu- 
berty reduces  sexual  desire  as  well  as  gen- 
eral activity  and,  although  sexual  behavior 
may  not  immediately  cease,  it  is  presently 
^\'eakened  and  in  most  cases  eventually 
disappears  entirely.  Injection  of  andro- 
gens into  the  blood  stream  of  castrated  rats 
not  only  revives  their  specifically  sexual 
behavior  but  increases  as  well  the  amount 
of  their  general  activity. 

There  is,  then,  no  doubt  that  the  sex 
drive  of  higher  animals  is  in  large  measure 
dependent  upon  the  presence  of  hormones 
in  their  blood.  The  hormonal  origin  of 
the  sexual  need  of  man  is  also  clear. 
Though  an  infant  or  child  may   seek   to 


gain  lliroiigli  stimulation  ol  certain  eroge- 
nous /ones  of  the  body  (for  example,  by 
masturbation  of  the  genitals)  a  kind  of 
pleasure  which  later  would  normally  be 
gained  in  the  act  of  sexual  intercourse,  a 
specific  and  strong  sex  drive  is  not  observed 
in  children  prior  to  puberty.  In  fact,  if 
ovaries  are  removed  from  a  female  child 
or  fail  to  develop,  she  will  never  become 
pubescent;  adult  female  characteristics  will 
not  appear  and  there  will  be  a  complete 
absence  of  sex  drive.  Similarly,  early  cas- 
tration of  a  male  child  results  in  a  person 
of  neutral  sex,  lacking  both  sex  drive  and 
the  male  secondary  sexual   characteristics. 

The  mere  fact  that  a  person  has  reached 
or  passed  bc)ond  the  stage  of  puberty  does 
not  necessarily  mean,  however,  that  his 
sexual  drive  will  find  a  normal  and  healthy 
outlet.  Sexual  maturation  gives  no  guar- 
antee of  adequate  psychosexual  develop- 
ment. Unfortunate  early  experiences  may 
so  warp  a  man's  attitudes  toward  sex  that, 
although  he  may  have  a  fully  de\eloped 
sexual  mechanism  and  an  adequate  secre- 
tion of  hormones  in  his  blood,  he  may, 
nevertheless,  find  himself  imable  to  per- 
form the  sexual  act  (impotency).  A 
woman  who  has  been  made  to  fear  her 
sexual  impulses  or  has  been  led  to  think  of 
sex  as  something  dirty  or  sinful  may  find 
herself  unable  to  experience  any  pleasure 
in  the  sexual  act  (frigidity).  e\en  though 
she  is  fiUly  equipped  physiologically  and 
anatomically  for  such  experience. 

The  hormonal  basis  of  the  sex  drive  can 
vary  tremendously,  but  sexual  need  and 
behavior  are  not  related  in  any  simple 
manner  to  the  amount  of  this  variation. 
Just  as  frigidity  is  not  alwa\s  caused  by  a 
deficiency  of. hormones,  so  an  abnormally 
strong  sexual  desire  in  ■women  (nympho- 
mania) is  not  always  the  result  of  an  ex- 
cessive   secretion    of    hormones.      In    fact. 


118 


Moiivation 


nymphomania  is  o[ten  an  attempt  of  a 
woman  to  compensate  for  a  real  or  an  im- 
agined sexual  inadequacy.  Impotence  in 
males,  and  its  opposite,  satyriasis,  though 
sometimes  correlated  respectively  -vvith  low 
and  high  Levels  of  hormonal  secretion,  are 
in  other  cases  entirely  unrelated  to  physi- 
cal and  structural  factors. 

Man's  sexual  need  and  behavior  arc, 
ihen,  no  more  completely  determined  by 
the  level  of  hormones  in  his  blood  than  is 
his  eating  determined  solely  by  his  stom- 
ach's hunger  contractions.  Both  appetite 
and  sexual  desire  also  depend  upon  habits 
and  attitudes  that  are  learned  and  become, 
as  derived  needs,  part  of  the  personal  ad- 
justment of  the  individual.  Herein  lies 
the  reason  why  love  in  man,  with  a  better 
cerebral  cortex  than  any  other  animal,  can 
persist  and  even  arise  in  the  absence  of  ade- 
quate hormonal  secretions. 

The  menstrual  cycle  in  women  is  an 
estrus  cycle,  biu  a  woman's  sexual  desire  is 
not  completely  determined  by  the  cycle. 
The  peak  of  her  desire  has  no  fixed  relation 
to  the  time  of  ovulation;  it  is  usually  re- 
jiorted  to  be  gieatest  just  before  and  jtist 
after  menstruation,  but  it  is  often  reached 
at  other  times.  The  fact  that  women  do 
not  lose  their  sextial  desire  or  their  ability 
to  enjoN  the  sexual  act  after  menopause  is 
further  evidence  that  sexual  need  and  be- 
havior are  not  entirely  determined  by  hor- 
monal secretions,  once  women  have  learned 
to  enjoy  sexual  relations. 

Androgens  in  men  constitute  an  impor- 
tant basis  for  their  sex  drive,  but  the  andro- 
gens do  not  alone  explain  the  drive.  Re- 
moval of  the  male  gonads  in  mature  indi- 
viduals may  have  little  effect  upon  sexual 
behavior,  and  old  men  who  are  impotent 
may  still  experience  desire.  This  is  not 
to  say  that  androgens  have  no  effect;  they 


are  important  in  the  first  stirring  of  de- 
sire, and  beyond  this  they  contribute  to  a 
man's  energy  and  general  efficiency.  There 
is  no  doubt  that  castration  impairs  bodily 
vigor,  and  probably  also  intellectual  verve 
and  the  power  of  creati\e  thinking,  but 
it  does  not  necessarily  destroy  sexual  desire 
or  eliminate  sexual  behavior. 

Jt  can,  then,  be  said  of  sex,  as  of  hunger, 
that  objects  and  situations  associated  with 
the  arousal  of  the  sex  drive  may,  because 
of  this  association,  become  in  themselves 
adequate  to  stimulate  sexual  behavior. 
Once  an  individual  has  developed  habits 
of  sexual  behavior  with  a  certain  person  or 
kind  of  person  or  at  certain  times  and  in 
certain  places,  the  appearance  of  these 
established  'stimidi'  alone  may  suffice  to 
e\oke  again  sexual  need  and  beha\ior. 

Other  Drives 

Many  experiments  have  confirmed  the 
drive  character  of  other  endocrine  or  duct- 
less gland  secretions.  The  remo\al  of  the 
jjituitary,  adrenal  or  thyroid  glands  in  rats, 
as  well  as  in  other  animals  including  men, 
has  been  shown  to  be  followed  by  a  reduc- 
tion in  general  activity. 

Other  bodily  conditions  ser\'ing  as  dri\es 
to  action  are  dryness  of  the  mucous  lining 
of  the  throat  in  thirst,  distention  of  the 
bladder  or  large  intestine,  injury  to  the 
skin.  Such  examjales  could  be  many  times 
multiplied,  but  these  will  suffice. 

It  is  important  to  point  out  again,  hoAV- 
evev,  that  while  such  physiological  condi- 
tions as  have  just  been  described  may  be  the 
primary  drives  to  action,  nevertheless,  the 
environmental  situation  in  which  such  ac- 
tion occurs  may  in  itself  become  the  effec- 
tive stimulus  for  a  similar  form  of  be- 
havior thereafter  when  the  primary  stimu- 
lus is  lackins;. 


Needs  for  Particular  Foods 


119 


Behavior  and  Structure 

As  wc  liave  already  seen,  the  way  in  whidi 
organisms  satisfy  their  needs  depends  in 
part  upon  their  striittures.  We  cannot 
understand  how  an  engine  runs  if  we  know 
only  that  there  is  steam  in  the  boiler;  we 
must  also  know  the  structure  of  the  whole 
and  the  relationships  among  its  parts.  We 
have  to  know  as  much  about  living  or- 
ganisms if  we  are  to  understand  their  l)e- 
havior.  Needs  and  structures  are  related. 
Tiie  needs  of  a  blind  man  are  not  the  same 
as  those  of  a  man  who  sees,  or  those  of  a 
Ijed-ridden  cripple  the  same  as  those  of  an 
athlete.  Such  individuals  may  and  do 
have  some  needs  in  common,  but  they  will 
iiave,  in  addition,  unic]ue  needs. 

One  important  respect  in  which  organ- 
isms difler  is  in  ihe  extent  to  wliich  they  are 
able  at  birth  to  satisfy  their  needs.  "Hie 
luniian  infant  is  absolutely  dependent  upon 
others  for  the  gratification  of  many  of  his 
needs;  not  until  years  have  passed  is  he 
able  to  care  for  himself  alone.  He  must 
first  learn  how  to  get  most  of  the  things 
he  recjuires.  Many  animals,  such  as  spiders 
and  the  lower  insects,  on  the  other  hand, 
are  from  the  very  first  as  capable  of  satis- 
fying their  needs  as  the  adults  of  the  same 
species.  They  do  not  have  to  learn  how 
to  take  care  of  themselves,  for  they  are  born 
with  mature  structures  organized  for  pat- 
terns of  action  adequate  to  meet  all  their 
needs.  Such  inborn  patterns  of  response 
have  been  called  instincts,  and  the  be- 
liavior  resulting  from  the  activation  of  such 
patterns,  instinctive.  A  fuller  account  of 
instinctive  beha\'ior  has  already  been  gi\en 
(pp.  45-47).  Here  it  is  important  only 
to  note  that,  whereas  man  has  to  learn 
through  years  of  exj^erience  how  he  may 
satisfy  his  needs,  other  animals  start  with 


beliavior  all  ready  to  take  care  of  most  ol 
their  tjasic  needs. 

Needs  for  Particular  Foods 

Most  animals  are  superior  to  man  in  the 
degree  to  which  patterns  of  response  acti- 
vated by  bodily  needs  operate  unconsciously 
in  the  satisfaction  of  these  needs.  In  one 
experiment  hens  were  fed  a  diet  almost  en- 
tirely deficieni  in  calcium  carbonate.  The 
omission  oi  this  imp(jrlant  material  from 
the  diet  soon  residted  in  a  marked  thinning 
of  the  shells  of  their  eggs  and,  after  lour 
days,  in  a  complete  cessation  of  laying. 
After  nine  days  of  this  diet  deficient  in 
calcium,  the  investigator  divided  the  hens 
into  two  groups.  To  one  group  on  one 
occasion  he  gave  short  pieces  of  macarf)ni 
within  which  shell  had  been  jjlacetl.  with 
the  ends  of  the  macaroni  so  closed  that  the 
shell  could  neither  Ije  seen  nor  tasted. 
These  hens  ate  at  that  time  an  average  of 
seventeen  grains  of  shell.  AVhen  he  pre- 
sented them  plain  shell  a  few  hours  later, 
each  of  these  hens  ate  an  average  of  only 
five  grains  more,  making  twent)-two  grains 
of  shell  eaten  in  all.  The  other  gioup  he 
first  gave  plain  macaroni,  but.  when  later 
lie  presented  them  with  plain  shell,  thev 
ate  on  the  average  nineteen  grains  of  shell. 
On  the  two  occasions  taken  together  the 
hens  of  the  two  sets  ate  approximately  the 
same  amount  of  shell,  but  that  was  because 
the  hens  who  needed  the  calciimi  more  on 
the  second  occasion  ate  more  shell  then. 
They  were  guided,  it  would  seem,  b\  phvsio- 
chemical  processes  within  their  bodit-s.  Be- 
ing calcium  hungrv  thev  kept  on  t-ating 
calcium  when  they  got  it. 

In  a  similar  experiment  hens  ^vere  of- 
fered a  choice  between  three  kinds  of  but- 
ter, one  high  in  \  itamins  A  and  D,  a  sec- 
ond high  in  A  but  low  in  D,  the  third  \o\v 
in  both  A  and  D.     They  ate  more  of  the 


120 


Motivation 


first  butter,  the  one  most  adequate  for  the 
satisfaction  of  niitrilional  needs,  than  of 
the  others. 

Rats  have  been  shown  to  have  the  same 
ability  to  choose  between  suitable  and  un- 
suitable diets  when  presented  with  a  variety 
of  foods  in  so-called  'rat  cafeterias.'  Pre- 
sented with  two  kinds  of  food,  one  con- 
taining sufficient  and  the  other  insufficient 
protein  for  normal  growth,  the  rats  ate 
both  foods,  but  enough  more  of  the  former 
to  maintain  normal  growtli.  Given  foods 
varying  in  vitamin  B  content,  they  chose 
the  foods  with  the  richer  vitamin  content. 
The  same  resiUts  have  been  obtained  with 
pigs  and  cows;  these  animals  have  demon- 
strated under  controlled  conditions  their 
ability  to  select  a  diet  adequate  to  their 
bodily  needs. 

These  experiments  have  also  demon- 
strated that  hunger  is  not  just  an  indis- 
criminate demand  for  any  kind  of  food, 
but  a  complex  of  specific  himgers  or  appe- 
tites, each  for  a  particular  nutritive  sub- 
stance, like  protein,  fat,  carbohydrate, 
water,  sodium,  phosphorus,  or  calcium. 
(The  desire  for  salt  due  to  the  removal  or 
a  disease  of  the  adrenal  glands  is  discussed 
on  pp.  355  f.) 

This  discovery  does  not  mean,  however, 
that  animals  limit  their  eating  to  food- 
stuffs that  satisfy  specific  nutritive  needs. 
Like  human  beings,  they  may  be  tempted 
to  eat  whatever  is  appetizing  to  them  rather 
than  what  is  needed  by  their  bodies. 

In  one  experiment  rats  were  allowed  to 
choose  between  two  different  foods,  a  pro- 
tein (casein)  and  a  carbohydrate  (sucrose), 
but  they  were  required  to  make  the  choice 
in  two  different  ways.  In  the  first  kind  of 
choice,  the  protein  and  the  carbohydrate 
had  no  fixed  positions,  but  were  shifted 
at  random  between  the  left  and  the  right. 
The  rats  could  see,  smell  and  taste  both 


these  foods  and  made  their  choices  on  this 
immediate  sensory  basis.  In  the  othei 
kind  of  choice,  the  positions  of  the  pro- 
tein and  carbohydrate  were  fixed,  and  the 
rat  was  required  to  make  his  choice  in  ad- 
vance, after  he  had  had  enough  experi- 
ence to  remember  which  food  was  where. 
When  the  rats  had  been  deprived  of  pro- 
tein for  thirty  days,  they  were  allowed  to 
select  food  under  these  two  conditions. 
Their  bodies  then  needed  protein  much 
more  than  carbohydrate.  Were  they  wise? 
They  were  wise  in  advance,  that  is  to  say, 
when  they  had  only  the  memories  of  the 
foods  and  their  awareness  of  their  own 
bodies  in  mind,  they  chose  protein;  but 
when  they  were  close  to  the  foods  so  that 
they  could  see,  smell  and  taste  them,  they 
tended  to  take  the  carbohydrate,  even 
though  it  was  not  so  good  for  them. 

This  experiment  was  repeated  with  dis- 
tilled water  and  powdered  dog  chow  as 
the  substances  between  which  choice  had  to 
be  made.  The  rats  were  deprived  of  both 
chow  and  water.  When  they  had  to  choose 
in  advance  they  all  chose  water,  but,  faced 
immediately  with  tasteless,  odorless  water 
versus  smelly,  tasty  chow,  they  chose  the 
chow. 

The  himian  analogy  is  apt.  Motivation 
in  rat  or  man  is  altered  by  immediate 
perception  The  lure  of  the  senses  is 
strongest  when  sensation  is  actual  and  not 
merely  remembered.  In  the  days  of  the 
saloon  and  the  drunkard,  it  was  always  a 
(question  as  to  whether  the  drunkard  coidd 
get  home  with  his  pay  without  squander- 
ing it  on  drink.  Starting  home  with  high 
resolve,  he  could  succeed  if  he  did  not  pass 
the  saloon,  if  he  avoided  the  visual-olfac- 
tory perception  that  could  so  easily  shift 
his  motivation.  The  dinner  table  is  replete 
with  similar  dilemmas.  Do  you  eat  what 
is  good  for  you  or  what  tastes  good  to  you? 


Derived  Needs 


121 


Since  lumiaii  ;i(liills  so  ric(|ii(iuly  cal  an 
improper  diet,  it  is  interesting  to  note  that 
newly  weaned  infants,  ii  presented  with  a 
variety  of  simply  prepared,  natural  foods 
(includino  all  kinds  necessary  to  pTodnce  a 
good  state  of  nutrition,  but  excluding  all 
food  mixtures,  refined  cereals  and  sugar) 
and  if  then  allowed  complete  freedom  of 
choice,  select  their  food  so  that  they  have 
an  adetjuate  and  balanced  diet  in  terms  of 
protein,  carbohydrate,  fat,  calories,  acidity 
and  alkalinity.  They  gain  in  weight  more 
than  the  average  for  this  growth  period. 
Jn  view  of  the  above  limitations  these  find- 
ings evidently  do  not  imply  that  free  choice 
at  the  family  table  would  produce  the 
same  satisfactory  results. 

Experiments  of  this  sort,  however, 
hardly  justify  the  conclusion  that  infants 
and  children  should  be  allowed  complete 
freedom  in  the  choice  of  their  food  in  the 
situations  of  everyday  life.  If  a  complete 
and  adequate  range  of  foods  were  always 
available  to  children— something  which 
would  be  most  uneconomical— and  if  the 
feeding  habits  of  adults  were  unknown  to 
them,  and  if,  in  addition,  they  were  left 
absolutely  free  to  choose,  perhaps  they 
would  do  as  well.  In  the  absence  of  such 
conditions,  however,  they  seem  to  develop 
specific  food  preferences  and  habits  of  eat- 
ing which  make  it  difl&cult,  if  not  impos- 
sible, for  the  infant  to  get  along  if  such 
unconscious  regulation  of  diet  continues 
indefinitely. 

Derived  Needs 

The  greater  plasticity  of  man  means  that 
he,  more  than  any  other  animal,  has  to 
learn  hoiv  to  satisfy  his  needs.  It  also 
means  that  he  learns  to  need  more  things 
than  any  other  animal. 

Learned  skills   and   abilities   and  habits 


arc  imjjortant  in  the  study  ol  motivation 
not  only  because  they  enable  the  individ- 
ual to  satisfy  his  needs,  but  also  because 
they  may  themselves  become  drives  to  ac- 
tion, constituting  needs  in  their  own  right. 
The  boy  who  learns  boxing  in  sclf-delense 
may  find  that  he  wants  to  box,  no  longer 
in  self-defense,  but  just  for  the  fun  of  box- 
ing; or  the  girl  who  learns  to  sew  in  order 
that  she  may  have  clothes  as  attractive  as 
her  friends  may  discover  that  she  wants 
to  sew,  even  though  she  needs  no  more 
clothes  for  her  few  social  engagements.  It 
might  be  argued  that  the  boy  who  con- 
tinues to  box  does  so  in  order  to  feel  supe- 
rior instead  of  merely  to  protect  himself, 
and  that  the  girl  who  continues  to  sew  does 
so  in  order  to  feel  superior  in  the  exercise 
of  her  skill  rather  than  merely  to  be  attrac- 
tive. But  even  so  it  is  in  such  ways  that 
the  number  of  our  specific  needs  is  multi- 
plied niany  times  over  in  the  course  of  oiu" 
lives.  In  general,  the  greater  the  pattern- 
ing of  the  nervous  processes  underlying  our 
actions,  the  greater  will  be  the  number  of 
needs  which  we  shall  experience. 

Such  needs,  resulting  from  mechanisms 
and  Iiabits  which  have  become  drives  in 
their  own  right,  are  called  derived  needs. 
They  are  the  clearest  examples  of  what  at 
the  beginning  of  this  chapter  we  called  sec- 
ondary needs.  Their  importance  for  every- 
day life  lies  in  the  fact  that,  through  their 
development,  objects  and  activities  which 
earlier  were  means  to  an  end  now  become 
ends  in  themselves.  Their  importance  for 
any  theory  of  motivation  lies  in  the  fact 
that  they  indicate  the  complexity  of  the 
physiological  basis  of  the  behavior  which 
results  from  need  and  they  re\"eal  die  in- 
adequacy of  conceiving  of  drive  as  simply 
a  matter  of  a  specific  condition  of  the  tis- 
sue in  an  organ  or  other  restricted  part  of 
the  bod\-. 


122 


Motivation 


Because  these  secondary  needs  result 
from  the  patterning  of  the  response  mecha- 
nism, it  follows  that  their  physiological 
basis  must  be  in  large  measure  these  neural 
patterns.  Since  even  primary  needs  are 
satisfied  only  when  the  appropriate  pat- 
terns of  response  are  activated,  and  since, 
as  we  ha\e  seen,  these  primary  needs  may 
be  aroused  in  the  absence  of  the  usually 
associated  organic  condition,  it  would  seem 
no  less  true  that  their  physiological  basis 
is  also  in  large  part  a  matter  of  patterns  in 
the  nervous  system.  In  other  words,  we  arc 
forced  to  conceive  of  the  physiological  basis 
of  all  needs,  both  primary  and  secondary, 
as  being  a  matter  both  of  certain  organic 
stimulating  conditions  (for  example,  stom- 
ach contractions)  and  of  certain  neural 
states  (for  example,  neinal  patterns). 

BEHAVIOR    AS    DEPENDENT    ON 
THE    ENVIRONMENT 

So  important  is  the  role  of  the  environ- 
ment in  eliciting  and  determining  behav- 
ior that  it  has  been  impossible  not  to  men- 
tion it  in  connection  with  the  other  factors 
already  discussed. 

A  rat  confined  in  an  activity  cage  shows 
an  increase  of  activity  as  the  time  for  feed- 
ing approaches.  In  that  environment  it  is 
all  he  can  do  when  driven  by  himger.  But 
if  we  take  him  from  his  cage  and  put  food 
before  him,  he  will  no  longer  rvui;  he  will 
eat.  If,  on  the  other  hand,  we  place  him 
in  a  maze  which  he  has  learned,  he  will 
run  directly  to  the  food  box  and  eat.  We 
may  assume  in  all  three  cases  the  existence 
of  the  same  internal  state  of  physiological 
disequilibriimi  or  drive,  so  that  the  differ- 
ences in  behavior  appear  to  be  determined 
i)y  differences  in  the  rat's  environment  in 
the  three  situations. 

Let  lus  observe  the  same  rat   iusi  nfter  hr 


has  eaten  to  satiety.  A  satiated  rat  re- 
mains relatively  quiet  in  his  activity  cage. 
If  there  is  food  before  him,  he  ignores  it. 
If  placed  in  a  maze,  provided  it  is  not  a 
strange  one,  he  shows  no  active  seeking 
after  food.  Here,  in  the  same  three  situa- 
tions as  described  above  and  all  quite  dif- 
ferent from  each  other,  the  behavior  of  the 
rat  is  practically  identical— a  quiet  indif- 
ference to  his  environment.  Are  we,  then, 
to  draw  from  observation  of  a  satiated  rat 
a  different  conclusion  from  that  we  reached 
by  observation  of  a  hungry  rat,  namely, 
that  the  similarity  of  behavior  in  different 
environments  is  determined  by  the  similar 
internal  state  of  the  rat  in  all  three  situa- 
tions? 

Relation  of  Environment  to  Needs 

Neither  conclusion  is  wholly  right  nor 
^\■holly  wrong,  and  the  conflict  between 
them  can  be  resolved  if,  instead  of  consider- 
ing the  internal  and  external  factors  sep- 
arately, we  see  them  in  relation  to  each 
other.  The  point  is  that  any  situation  as 
it  exists  psychologically  for  the  organism— 
that  is  to  say,  as  it  is  perceived  and  reacted 
to— is  in  large  measure  dependent  upon  the 
needs  of  the  organism;  and,  since  the  needs 
of  any  organism  are  constantly  changing, 
this  fact  means  that  the  same  physical  en- 
vironment and  objects  in  it  ha\e  at  differ- 
ent times  quite  different  meanings.  When 
a  child  is  hungry,  an  apple  is  something 
to  eat;  but  when  he  is  angry,  it  is  some- 
thing to  throw  at  the  provoking  person. 
Similarly,  a  hungry  rat  is  an  alert  rat, 
actively  seeking  in  its  environment  any- 
thing that  may  serve  as  a  means  to  the 
satisfaction  of  its  need;  but  a  satiated  rat 
is  a  sleepy  rat,  indifferent  to  many  aspects 
of  its  environment.  Whether  food  is  pres- 
ent or  absent  is  a  matter  of  no  conse- 
(juence  to  it.     Environments  physically  im- 


Environmenfal  Determinafion  of  Needs 


123 


like  may  all  be  the  same  psychologically, 
in  that  they  are  reacted  to  as  though  they 
were  alike. 

It  is  helpful  in  distinguishing  the  physi- 
cal and  psychological  environment  to  call 
the  former  the  silualion  and  the  latter  the 
field.  The  physical  situation  is  the  en- 
vironment considered  as  having  independ- 
ent real  existence,  whereas  the  psycholog- 
ical field  is  the  situation  as  it  exists  psycho- 
logically for  the  individual.  The  psycho- 
logical field  is  not  to  be  equated  merely  to 
what  is  consciously  perceived  or  known  but 
rather  to  everything  that  at  the  moment 
determines  the  behavior  of  an  individual. 

Food  in  the  situation  may  or  may  not  be 
food  in  the  field.  If  there  is  a  need  for  it, 
food  in  the  situation  is  likely  to  be  per- 
ceived and  reacted  to.  It  then  exists  as 
food  in  the  field  and  has  a  positive,  at- 
tractive value,  exciting  the  hungry  person 
to  eat.  But  the  need  for  nourishment  hav- 
ing been  satisfied,  the  same  food  may  be 
ignored.  Although  it  may  be  perceived,  it 
will  not  excite  the  individual  to  activity, 
for  it  now  has  a  neutral  quality,  neither  at- 
tracting nor  repelling  him.  The  presence 
of  others  who  are  hungry  and  eating  may 
make  the  food  seem  slightly  attractive  so 
that  it  is  nibbled  at.  An  unpleasant  story 
told  at  the  table  may  make  the  food  seem 
unpleasant  so  that  it  is  pushed  away.  If, 
however,  for  any  reason  food  has  been 
eaten  to  the  point  of  satiation,  especially  if 
this  overeating  has  resulted  in  any  degree 
of  discomfort,  the  sight  and  smell  of  food 
cease  to  be  neutral  and  acquire  a  negative 
character.  The  individual  experiences  a 
need  to  push  the  food  out  of  sight  or  to 
remove  himself  from  it. 

Incentives 

The  existence  of  objects  or  activities  in 
a  person's  field  is  thus  seen  to  depend  to 


an  iiriportanl  dcgicc  upon  his  needs.  Jt  is 
for  this  reason  that  objects  and  artivities 
in  the  field  so  often  have  to  be  described 
psychologically  as  having  an  attracting,  re- 
pelling, exhorting,  summoning,  inviting  or 
demanding  character.  Things  f>ossessing 
such  characteristics  are  called  incentives. 
An  incentixie  may  be  defined  as  an  object, 
a  situation  or  an  actit)ity  which  excites, 
maintains  and  directs  behavior.  It  must  be 
clear,  however,  that  a  thing  which  is  an 
incentive  at  one  moment  may  not  be  an 
incentive  at  tlie  next  moment,  or  that  a 
thing  which  is  at  one  time  a  positive  in- 
centive attracting  a  person  may  subse- 
quently be  a  negative  incentive  repelling 
the  same  individual. 

Objects  or  activities  offered  to  an  indi- 
vidual may  act  as  incentives  to  arouse  his 
needs  and  stir  him  to  action,  ^\'hen  a 
need  is  very  strong,  he  will  actively  seek 
objects  to  satisfy  it  if  they  are  not  present 
in  his  environment.  But,  under  condi- 
tions of  a  lesser  need,  an  individual  mav 
be  relatively  quiet  and  contented  until 
something  brought  into  his  environment 
acts  as  an  incentive  to  arouse  that  need 
more  actively.  A  person  may  not  be  con- 
sciously hungry  until  he  smells  the  pleas- 
ant aroma  of  food,  or  he  may  be  little  in- 
terested in  stamp  collecting  until  he  hears 
a  lecture  on  the  fascinations  of  philately. 
As  the  advertiser  knows,  it  is  possible, 
within  limits,  to  motivate  people  to  action 
through  a  manipulation  of  their  environ- 
ments; but,  if  this  activation  is  to  be 
wholly  successful,  it  is  necessary  to  know 
something  about  the  latent  needs  of  those 
whom  one  seeks  to  influence.  Otherwise 
what  may  seem  the  most  attractive  of  in- 
centives to  the  one  ^vho  offers  them  may 
turn  out  to  be  no  incentives  at  all  for  those 
to  whom  thev  are  offered. 

The  social  environment,  no  less  than  the 


124 


Motivation 


physical,  influences  the  activities  of  indi- 
\'iduals,  causing  things  to  lose  or  to  acquire 
incentive  value  for  them.  It  has  already 
been  pointed  out  that  a  hen  which  has 
eaten  to  satiation  will  begin  to  eat  again 
if  a  hungry  second  hen  is  introduced  into 
the  situation;  and  she  will  eat  more  if  two 
hungry  hens,  and  still  more  if  three,  are 
brought  in.  This  result  occurs,  however, 
only  when  the  hungry  hens  have  been  ac- 
customed to  tyrannize  over  the  satiated 
hen  in  other  situations.  If,  instead,  the 
satiated  hen  has  habitually  tyrannized  over 
the  hungry  hens,  she  will  attempt  to  keep 
them  from  eating  by  pecking  at  them  or 
chasing  them  away.  The  converse  experi- 
ment has  likewise  been  performed,  in 
which  three  hens  eat  to  satiation  and  then 
are  joined  by  a  single  hungry  hen.  Under 
these  conditions  the  hungry  hen  begins  to 
peck  the  grain,  but  her  behavior  has  no 
effect  upon  the  group  of  three,  who  re- 
main passive  or  peck  only  a  little.  Evi- 
dently the  satiated  hens  support  one  an- 
other in  their  indifference. 

Other  experiments  have  demonstrated 
comparable  effects  of  social  situations  on 
eating  in  fishes,  rats  and  monkeys,  and  the 
same  effect  is  noticeable  among  persons. 
The  child  who  does  not  want  his  oatmeal 
may  nevertheless  eat  it  eagerly  ^vhen  he 
sees  his  brother  eating  his  with  relish,  just 
as,  in  the  same  way,  the  eating  to  excess  at 
an  old-fashioned  Thanksgiving  dinner  is  a 
function  not  only  of  the  increased  quantity 
of  food  (tlie  same  effect  as  seen  in  hens) 
but  also  of  the  social  facilitation  supplied 
b)  the  sight  of  others  eating.  The  presence 
of  others  may,  of  course,  just  as  well  cause 
objects  or  activities  to  become  negative  in- 
centives as  positive,  as  when,  for  example, 
the  work  we  are  doing  ceases  to  be  inter- 
esting because  others  gather  lor  an  evening 
of  fun.     (See  also  pp.  596  f.) 


Cultural  Determination  of  Needs 

The  importance  of  the  environment  in 
the  behavior  that  is  dependent  on  needs  is, 
however,  most  clearly  seen  in  the  cultural 
determination  of  needs.  The  infant  is 
born  into  a  society  in  which  there  are  cer- 
tain social  norms  of  behavior,  certain  cus- 
toms which  determine  to  a  large  extent  not 
only  the  needs  which  the  members  of  that 
society  experience  but  also  the  particular 
means  by  which  these  needs  may  be  satis- 
fied. What  the  norms  of  his  society  are  is 
one  of  the  things  the  infant  has  to  learn. 
The  process  of  socialization  in  the  devel- 
oping child  is  in  large  measure  the  incor- 
poration of  these  norms  within  himself  in 
order  that  his  general  patterns  of  behavior 
may  coincide  wuth  those  of  his  gioup.  In 
short,  he  learns  that  certain  ends  may  be 
sought,  but  not  others. 

The  specific  nature  of  the  means  of  sat- 
isfying primary  needs  no  less  than  sec- 
ondary ones  is  determined  by  social  norms. 
The  kind  of  food  eaten  by  people  of  differ- 
ent cultures  varies  greatly.  In  many  so- 
cieties individuals  are  not  permitted  to  eat 
the  flesh  of  certain  animals  which  are  be- 
lieved to  be  related  to  them,  a  relationship 
which  thus  renders  the  idea  of  eating  such 
flesh  abhorrent.  In  other  societies  fruits 
or  plants  are  prohibited.  There  is  no  so- 
ciety in  which  the  entire  range  of  edible 
objects  is  included  in  the  diet.  Having 
learned  to  eat  certain  things  and  not  cith- 
ers, and  having  learned  to  eat  them  only 
when  prepared  in  certain  ways,  we  find  it 
difficult,  if  not  impossible,  to  change  our 
eatmg  habits.  It  is  known,  for  instance, 
that  immigrants  frequently  find  it  easier  to 
learn  a  new  language  than  to  learn  to  like 
the  dishes  of  their  new  counti-y.  ^\n  Amer- 
ican may  demand  a  soft  mattress  and  pil- 


Cultural  Determination  of  Needs 


125 


low  ii  his  need  lor  rest  is  to  be  satisdcd,  ;i 
Japanese  may  demand  a  hard  mat  and  jjil- 
low  of  wood  and  the  African  native  may 
be  able  to  rest  only  if  he  tan  lie  upon  the 
ground.  Such  differences  as  these  are  not 
racially  determined  but  are  rather  the  ef- 
fect of  social  pressure  on  the  needs  of  in- 
dividuals in  different  cultures. 

The  young  of  the  human  species  must 
be  cared  for  if  the  species  is  to  survive. 
This  fact  has  led  many  persons  to  assume 
the  existence  in  every  mother  of  a  need  to 
care  for  her  offspring,  a  need  so  fixed  in  its 
expression  as  to  constitute  a  malernal  in- 
stinct. Yet,  actually,  there  is  to  be  found 
among  different  peoples  a  wide  range  of 
norms  of  behavior  in  regard  to  the  care  and 
protection  of  infants.  Among  the  Arapesh 
of  the  South  Seas  an  infant  is  the  object 
of  great  warmth  and  affection.  Suckled 
whenever  it  cries,  sleeping  in  close  contact 
with  its  mother  and  carried  by  her  wher- 
ever she  goes,  the  Arapesh  infant  is  almost 
continuously  fondled  and  caressed.  In 
contrast  to  the  Arapesh,  the  Mundugumor 
treat  their  children  with  little  love.  The 
infant  is  kept  in  a  hard  uncomfortable 
basket,  is  not  suckled  unless  clearly  in  need 
of  milk,  is  not  fondled  or  caressed,  is  made 
early  to  fend  for  itself  and  in  general  is 
so  harshly  treated  that  only  the  strongest 
survive.  Among  the  Andaman  Islanders 
adoption  of  children  is  so  customary  that 
it  is  rare  to  find  a  child  of  more  than  six  or 
seven  years  of  age  living  with  its  parents, 
for  to  adopt  the  child  of  a  friend  is  an 
accepted  form  of  expressing  friendship  and 
regard.  On  the  Island  of  Mota,  on  the 
other  hand,  an  infant  may  be  sold  at  birth 
to  the  man  who  pays  the  midwife.  Al- 
though this  person  is  usually  the  father,  it 
sometimes  happens  that,  in  the  absence  of 
the  father  or  in  the  event  that  he  lacks  the 


ii((cssai)  lunds,  another  man  bu)s  the 
(hild  and  Ijccomes  its  'lather.'  In  otiicr 
societies  infanticide,  at  least  under  certain 
conditions,  is  an  accepted  practice;  and  th," 
Aztecs  sold  their  children  into  slavery. 

y\nother  form  of  human  behavior  which 
has  sometimes  been  regarded  as  instinctive 
is  the  aggressiiie  reaction  to  frustration. 
Nevertheless  conflict  between  individuals 
does  not  invariably  or  universally  result 
in  the  same  behavior.  Instead  of  fighting 
with  his  fists,  the  Kwakiutl  Indian  fights 
with  property  in  the  institution  of  the 
"potlatch,"  in  which  the  more  property  he 
can  give  away  or  destroy,  the  more  superior 
he  is  to  his  opponent.  Eskimos  settle  their 
conflicts  in  a  public  contest  in  which  each 
sings  abusive  songs  about  the  other.  ^Vhen 
two  Indians  of  Santa  Marta  quanel,  in- 
stead of  striking  each  other,  they  strike  a 
tree  or  a  rock  with  sticks,  and  the  one  first 
breaking  his  stick  is  considered  the  braver 
and  hence  the  victor.  In  other  societies 
aggression  is  expressed  in  still  other  Avays; 
even  within  the  same  society  there  may  be  a 
wide  range  of  different  socially  approved 
expressions  of  aggression. 

It  is  noiv  possible  to  demonstrate  a  wide 
range  of  behavior  for  any  need.  In  the  ab- 
sence of  crucial  anthropological  kno^vl- 
edge,  it  was  formerly  assumed  diat  the 
needs  were  in  all  societies  the  same  as  in 
ours,  and  therefore  instinctive.  The  fixed- 
ness and  universality  of  forms  of  human 
beha\ior,  ho^vever,  turn  out  to  be  a  myth. 
Instead,  we  find  that  the  needs  of  die  indi- 
vidual, as  well  as  the  ways  in  A\hich  he  is 
jjermitted  to  satisfy  them,  are  determined 
to  a  large  extent  by  the  social  and  cultural 
environment  into  which  he  is  born  and  in 
■which  he  is  reared,  (^\'e  shall  learn  more 
about  social  norms  on  pp.  560-562.) 


126 


Motivation 


DEFINITION    OF    NEED 

The  iacts  reviewed  in  the  preceding  sec- 
tions of  this  chapter  suggest  the  following 
definition  of  need.  A  need  is  a  tension 
within  an  organism  which  tends  to  orgaji- 
ize  the  field  of  the  organism  with  respect 
to  certain  incentives  or  goals  and  to  incite 
actixnty  directed  toivard  their  attainment. 
For  each  need  there  are  certain  objects  or 
activities— terminal  situations— which,  if 
they  are  obtained,  satisfy  the  need,  thus  re- 
leasing the  tension.  It  is  for  this  reason 
that  the  fullest  meaning  of  any  behavior  is 
described  only  when  the  final  situation  to- 
ward which  it  is  leading  is  discovered. 

At  this  point  we  must  pause  to  note  that 
a  7ieed,  a  set  and  an  attitude  are  psycho- 
logically the  same  thing.  The  terms  are 
merely  being  used  in  different  contexts. 
When  a  subject  is  given  pairs  of  digits  and 
told  to  write  down  their  sums,  he  is  put  in 
the  adding  attitude  and  is  operating  under 
a  set  for  addition.  Actually  it  would  be 
just  as  reasonable  to  say  that  he  has  tempo- 
rarily acquired  a  need  for  sums,  a  need 
which  is  derived  from  his  need  to  do  what 
the  experimenter  asks  him  to  do  and  to  do 
it  well,  which  in  turn  is  a  phase  of  his  need 
for  approbation,  which,  of  course,  be- 
longs properly  to  all  gregarious  animals 
like  man.  Need,  set,  attitude— these  are 
all  dynamic  psychological  concepts  which 
express  the  fact  that  the  organism  can  be 
set  to  pursue  a  given  end  or  purpose  con- 
sistently and  without  being  put  off  the 
main  track  by  every  casual  stimulation  that 
comes  along. 

Needs  have  a  qualitative  aspect  which 
makes  it  possible  for  us  to  distinguish  such 
primary  needs  as  those  for  food,  sex,  ther- 
mal constancy  and  elimination,  and  such 
secondary  needs  as  those  for  superiority, 
submission,  affiliation,  freedom  and  invio- 


lacy.  Such  terms  as  these  are,  of  course, 
generalizations  from  the  specific  situations 
in  which  the  concrete  activities  of  needs 
end.  We  do  not  have  a  general  need  to 
be  superior,  but  rather  a  need  to  be  su- 
perior in  a  particular  way  in  a  specific  sit- 
uation, for  example,  to  win  this  race,  to  get 
the  highest  mark  on  this  examination,  to 
know  more  about  a  certain  field  of  study 
than  any  other  person.  Yet  it  is  often  help- 
ful in  the  study  of  certain  problems  of  per- 
sonality and  in  the  comparison  of  individ- 
uals to  conceptualize  general  needs  of 
which  any  given  behavior  or  trait  is  but  a 
specific  and  concrete  expression. 

MEASUREMENT    OF    NEEDS 

Needs  also  have  a  quantitative  aspect 
which  makes  it  possible  by  the  use  of  cer- 
tain techniques  to  measure  their  strength. 
Although,  of  course,  a  need  cannot  be 
measured  directly,  an  indirect  estimate  can 
be  obtained  by  measuring  its  effect  upon 
consciousness  and  behavior.  Thus,  by  de- 
termining the  work  which  the  need  will 
do,  we  get  an  indication  of  its  intensity. 

Obstruction  Method 

One  technique  for  the  measurement  of 
needs  is  the  obstruction  method,  by  which 
the  strength  of  a  need  is  measured  in  terms 
of  the  magnitude  of  an  obstacle  or  the 
number  of  times  an  obstacle  of  a  given 
magnitude  will  be  overcome  in  order  to 
obtain  a  needed  object.  The  obstruction 
method  has  been  employed  most  often  in 
the  measurement  of  animal  drive,  rats  hav- 
ing been  the  subjects  most  frequently  stud- 
ied. 

A  diagram  of  an  obstruction  box  used  in 
such  investigations  is  shown  in  Fig.  43.  To 
measure  the  sex  need  a  female  rat  is  placed 


Measurement  of  Needs 


127 


in  compartment  A,  a  male  rat  (the  in- 
centive) in  compartment  1).  In  order  to 
reach  the  incentive,  the  female  rat  must 
pass  through  the  alley  B.  The  floor  of 
this  section  is  covered  with  an  electric  grid 
which  enables  the  experimenter  to  give  the 
animal  a  shock.  If  she  crosses  the  grid,  she 
steps  on  E  which  releases  door  ^21  liber- 
ating the  male  from  D.  It  has  been  found 
that    when    a    female    rat    is    in    heat    she 


order  to  get  the  food;  and,  presumably,  the 
stronger  the  first  need,  the  more  often  will 
the  grid  be  crossed  in  a  given  period  of 
time.  Since  every  need  is  unstable,  the 
measurement  of  one  against  another  can- 
not be  exact.  In  evaluating  these  results 
we  must  remember  that  the  animal  tends  to 
become  accustomed  to  the  electric  shock, 
so  that  the  negative  incentive  of  the  physi- 
cally constant  shock  decreases  in  time. 


A 

1 

1 



1 a  — 

E 

C 

i 

FIGURE   43.      FLOOR   PLAN    OF    OBSTRUCTION    BOX 

(A)  Entrance  compartment;  (B)  obstruction  compartment  (electric  grid):  (C,  D)  divided  inceiiiive  com- 
partment; (£)  release  plate;  (d^)  manually  operated  door  between  entrance  compartment  .-/  and  grid  li: 
((I2)  automatic  door  operated  by  animal's  stepping  on  release  plate  E.  [From  T.  N.  Jenkins,  L.  H.  Warner 
and  C.  J.  Warden,  /.  conip.  Psychol.,  1926,  6,  366;  reprinted  by  permission  of  the  Williams  and  ^VilkiIls 
Company.] 


crosses  the  charged  grid  frequently  and 
with  little  hesitation,  though  at  other 
times  she  scarcely  ever  crosses  it. 

Similar  investigations  of  hunger,  thirst 
and  inaternal  need  have  demonstrated  that 
a  rat  does  not  repeatedly  cross  the  grid  and 
take  a  shock  in  the  absence  either  of  a 
motivating  need  or  of  the  appropriate  in- 
centive. 

In  the  obstruction  inethod  not  one  need 
is  measured,  but  two  which  are  in  conflict. 
There  is  the  need  for  food,  or  water,  or 
whatever  other  need  is  being  investigated, 
but  there  is  also  the  need  for  avoidance  of 
pain,  so  that  what  is  actually  being  meas- 
ured is  the  relative  strength  of  the  two 
needs.  If,  for  example,  the  need  for  food 
is  stronger  than  the  need  for  avoidance  of 
pain,   the   animal  will   take   the   shock   in 


With  the  use  of  this  method  of  obstruc- 
tion attempts  have  been  made  to  determine 
the  relative  strengths  of  various  animal 
needs.  In  the  most  extensive  investiga- 
tions so  far  recorded,  the  maternal  need 
has  been  found  to  be  the  strongest.  The 
others  in  rank  order  of  strength  are  thirst, 
hunger,  sex  and  the  exploratory  need. 
This  order  depends,  howe\'er,  upon  the  de- 
gree of  deprivation  of  the  animal  and  upon 
the  particular  apparatus  used  as  well  as 
upon  the  comparison  of  one  need  at  a  time 
with  the  need  for  avoidance  of  pain. 

Needs,  hoAvever,  are  all  interrelated.  It 
has  been  shown  that  prolonged  hunger 
both  in  man  and  in  animals  is  accompa- 
nied by  a  lessening  of  sexual  diive;  that 
prolonged  deprivation  of  water  reduces  ma- 
terially the  intake  of  food  in  rats;  that  the 


128 


Motivation 


brooding  of  a  hen  reduces  greatly  the 
amount  of  food  she  eats:  that  an  increase 
in  the  hunger  of  rats  is  accompanied  by  an 
increase  in  their  need  for  exploration;  and 
that,  when  sex  need  is  strongest  (at  the  time 
of  estrus  in  the  female  rat),  the  need  for 
food  as  measured  by  its  intake  is  greatly 
reduced.  A  similar  interrelation  can  be 
observed  in  persons.  The  need  to  get  good 
grades  may  become  much  less  when  the 
student  falls  in  love,  the  need  for  food  may 
become  secondary  to  the  desire  to  have  a 
slim  figure,  and  the  need  of  the  mother  to 
dress  attractively  may  become  negligible 
when  the  need  to  care  for  her  child  is 
great. 

Learning  Method 

A  second  technique  for  the  measurement 
of  needs  is  the  learning  method,  by  which 
the  strength  of  need  is  measured  in  terms 
of  the  readiness  with  which  a  task  is  learned 
under  different  conditions  of  motivation. 
It  has  long  been  known  that  for  an  organ- 
ism to  learn  it  must  be  motivated.  This 
fact  makes  it  possible  to  vary  the  factor  of 
motivation  and  to  measure  its  effect  upon 
the  rate  of  learning.  Here  again,  because 
animal  experimentation  is  simpler  than  hu- 
man, most  of  the  studies  have  been  made 
with  animals,  but  an  analogue  of  the  ex- 
perimental findings  can  usually  be  found 
in  the  realm  of  human  behavior. 

It  has  been  shown  that,  within  limits, 
the  stronger  the  motivation  the  faster  the 
learning.  In  one  experiment  which  dem- 
onstrated this  relation,  the  rate  of  maze 
learning  by  three  groups  of  rats  differing 
only  in  their  motivation  was  investigated. 
The  first  group  was  very  hungry  and  very 
thirsty,  the  second  was  very  hungry  but 
only  slightly  thirsty  and  the  third  was  very 
thirsty  but  only  slightly  hungry.  During 
the  first  nine  days  of  the  experiment  the 


rats  were  rewarded  with  bran  mash;  during 
the  last  nine  days  they  were  rewarded  with 
water.  In  the  first  half  of  the  experiment 
the  rats  motivated  both  by  hunger  and 
thirst  learned  slightly  faster  than  the  ani- 
mals of  the  other  two  groups,  a  fact  which 
indicates  the  superiority  of  two  needs  over 
one  in  motivating  learning.  In  the  second 
half  of  the  experiment,  with  the  shift  to 
water  as  the  reward,  the  very  hungry  and 
thirsty  animals  were  temporarily  disturbed 
by  the  change.  They  showed  at  first  an  in- 
crease in  the  number  of  their  errors,  but  at 
the  end  of  the  experiment  they  were  again 
superior  to  the  other  two  groups.  The  ef- 
fect of  the  shift  in  reward  upon  the  other 
two  groups,  which  had  learned  at  the  same 
rate  during  the  first  nine  days,  was  striking. 
Now  rewarded  with  Avater,  the  very  thirsty 
animals  speeded  up  their  learning,  whereas 
the  very  hungry  rats  showed  very  little  im- 
provement with  the  inappropriate  reward. 
The  second  half  of  the  experiment  not 
only  confirmed  the  finding  of  the  first  in 
demonstrating  that  two  needs  constitute  a 
more  effective  condition  for  learning  than 
one,  but  it  also  showed  that  learning  is 
faster  when  the  need  serving  as  motive  is 
appropriately  rewarded. 

The  needs  motivating  children  for  their 
school  work  are  numerous  and  varied. 
The  arousing  of  more  needs  by  presenting 
additional  incentives  has  been  shown  to  in- 
crease their  accomplishment.  In  one  in- 
vestigation, the  offer  of  a  reward  of  a  choco- 
late bar  raised  the  performance  fifty-two 
per  cent  above  the  usual  level,  whereas  the 
introduction  of  a  number  of  incentives, 
like  candy,  a  definite  goal,  rivalry  and 
praise,  increased  the  performance  sixty-five 
per  cent.  In  human  motivation,  then,  as 
in  animal,  it  is  easy  to  demonstrate  that  an 
increase  in  motivation  leads  to  an  increase 
of  performance. 


Effecfs  of  Need 


129 


1 1  has  also  been  shown  that  the  amount 
ol  reward  offered  inHuences  the  rate  of 
learning.  For  instance,  chicks  who  find  six 
grains  of  boiled  rice  in  the  reward  box  at 
the  end  of  a  simple  maze  learn  the  maze 
more  effectively  than  chicks  who  are  re- 
warded with  only  one  grain.  That  the 
amount  of  reward  offered  human  beings  is 
not  without  its  effect  upon  performance  is 
also  clear.  We  work  harder  and  better  for 
more  rather  than  for  less  pay.  The  stu- 
dent works  harder  for  a  large  scholarship 
than  for  a  small  one. 

Not  only  is  the  amount  of  reward  impor- 
tant in  determining  the  rate  of  learning 
but  also  the  kind  of  reward.  It  has  been 
shown,  for  example,  that  of  two  groups  of 
rats  learning  a  maze,  the  group  rewarded 
with  bran  mash  will  learn  the  maze  more 
rapidly  than  the  group  rewarded  with  less- 
preferred  sunflower  seeds.  This  finding 
also  has  its  analogue  in  human  behavior. 

SOME    EFFECTS    OF    NEED 

Sensitivity,  perception,  imagination, 
thought,  activity  and  persistence  all  depend 
on  need  and  are  affected  by  needs.  Frus- 
tration often  arises  from  a  conflict  of  needs. 
To  these  effects  we  now  turn. 

Effect  on  Perception  and  Imagination 

The  investigations  just  reviewed  have 
demonstrated  the  role  of  need  in  learning. 
They  have  also  shown  the  effect  of  need  on 
perception,  for  all  learning  involves  a  re- 
organization of  a  field.  The  maze  which  a 
rat  has  learned  is  psychologically  quite  dif- 
ferent from  what  it  was  when  first  encoun- 
tered. The  keyboard  of  a  typewriter  is  for 
the  skilled  typist  quite  a  different  field 
from  what  it  is  for  the  novice. 

A  simple  example  will  illustrate  that 
learning    involves    a    reorganization    of    a 


field  as  a  result  of  need.  Let  us  lake  the 
case  of  a  young  child  separated  from  an 
apple  by  a  lerKC,  as  indicated  in  Fig.  44(a). 
If  the  child  is  not  hungry,  and  is  content- 
edly playing  wiiii  some  toys  in  the  blind 
alley,  he  may  not  even  sec  the  apple;  or, 
if  lie  does,  he  will  not  be  interested  in  it. 
If,  on. the  other  hand,  he  is  restless,  either 
because  he  is  hungry  or  because  he  is  tired 
of  playing  with  his  toys,  the  likelihood  is 
greatly  increased  that  he  will  see  the  apple. 


+ 

+ 

+  -K^ 

o 

o 

o 

t 

\ 

(fc)  (c) 

FIGURE  44.      STEPS  IN  SOLUTION  OF  SIMPLE  DETOUR 
PROBLEM 

-|-  =  apple.     O  =  child.     -^  =  path  taken  bv  child. 

Under  two  different  conditions  of  need  the 
field  of  the  child  is  differently  organized. 
Thus,  whether  the  apple  will  become  a 
positive  incentive  depends  upon  whether  it 
can  serve  in  any  way  to  satisfy  a  need. 

If  it  does  become  a  positive  incentive, 
the  very  young  child  will  try  to  get  it  in 
the  simplest  and  most  direct  manner,  as 
indicated  in  Fig.  44(6).  Since  he  cannot 
reach  it,  or  crawl  through  the  fence  to  it, 
his  need  is  blocked  and  his  field  reorgan- 
ized until  ^vhat  was  previously  for  him  a 
fence  or  a  row  of  sticks  no^v  looms  as  a 
barrier.  He  may  push  against  this  barrier, 
try  to  crawl  under  or  over  it  or  reach 
through  it  as  far  as  he  can,  all  because  the 
way  to  the  apple  is  a  straight  line  towaid 
it.  Then,  blocked  and  frustrated,  he  may 
look  around,  see  the  opening  and  suddenly 
run  to  tlie  apple  in  the  roundabout  direc- 
tion indicated  in  Fig.  44(c).  Again  his 
field  has  been  reorganized.  \\'hat  was  pre- 
viously either  nonexistent  as  a  way  to  the 


130 


Motivation 


goal,  or  else  a  path  away  from  the  goal, 
now  becomes  the  first  phase  of  the  path  to 
the  goal.  If  the  child  is  again  put  back 
into  the  blind  alley,  he  will  at  once  take 
the  roundabout  way  to  obtain  the  apple. 
He  has,  in  other  words,  learned  the  solu- 
tion of  what  is  called  a  detour  problem. 
In  this  case  it  is  clear  that  learning  is  the 
result  of  a  need  which  reorganizes  a  field. 
When  there  is  no  possible  solution  of  a 
problem,  the  role  of  need  in  reorganizing 
the  field  may  be  even  more  marked.  In 
an  investigation  of  anger,  subjects  were 
given  a  task  for  which  three  different  solu- 
tions were  demanded,  although  there  were 
only  two  possible  ones.  The  subject  was 
asked  to  step  within  a  square  outlined  by 
long  sticks  laid  upon  the  floor  and,  with- 
out leaving  this  area,  to  obtain  a  flower 
which  was  placed  upon  a  sawhorse  four 
feet  outside  the  square.  The  two  possible 
soltitions  were:  (1)  to  place  a  chair  which 
stood  within  the  square  between  the  square 
and  the  horse  and,  leaning  with  one  hand 
on  the  chair,  reach  the  flower  with  the 
other  hand;  and  (2)  to  kneel  down  (keep- 
ing the  feet  within  the  square)  and  reach 
the  flower.  Both  these  solutions  were  pos- 
sible only  if  the  subject  had  perceived  the 
field  reorganized  in  these  two  ways.  After 
the  subjects  had  arrived  at  these  two  solu- 
tions, they  were  asked  to  demonstrate  a 
third.  Since  there  was  no  third  solution 
and  since  the  subjects  were  kept  for  hours 
at  the  task,  the  mounting  tension  result- 
ing from  the  blocking  of  their  need  was 
expressed  not  only  in  anger  but  also  in 
many  new  perceptual  organizations  of  the 
field.  As  the  experiment  continued,  all  ob- 
jects came  to  be  seen  in  relation  to  the  goal 
—as  baniers,  disturbances,  tools,  etc.  The 
greater  the  tension,  the  more  did  objects 
offer  themselves  as  possible  means  to  the 
solution.      Some    rings    which    had    been 


placed  along  the  side  of  the  square  were 
seen  again  and  again  as  having  something 
to  do  with  getting  die  flower.  Although 
they  were  of  no  use,  they  were  picked  up 
repeatedly  and  juggled  about  in  a  vain  at- 
tempt at  use.  Then  they  became  disturb- 
ing factors  which  the  subjects  wanted  to 
forget  but  could  not.  The  subjects  were 
also  disturbed  by  the  fact  that  the  back  of 
the  square  was  made  of  two  sticks  rather 
than  one,  as  though  this,  too,  had  some- 
thing to  do  with  the  solution. 

Such  behavior  clearly  indicates  that 
while  a  certain  degree  of  need  is  necessary 
for  that  reorganization  of  a  field  which  con- 
stitutes insight  and  learning,  a  need  in  ex- 
cess of  such  an  optimum  may  come  so  to 
distort  the  field  that  it  no  longer  bears  any 
resemblance  to  the  situation.  In  this  ex- 
periment, some  of  the  subjects  after  long 
periods  of  frustration  revealed  momentary 
fantastic  distortions  of  the  field.  One  per- 
son began  to  act  as  though  she  had  hyp- 
notic power  to  draw  the  flower  to  her, 
while  another,  yielding  to  fantasy,  saw  the 
room  filled  with  water  and  the  horse  and 
flower  floating  in  her  direction.  Both  sub- 
jects in  their  momentary  fantasies  forgot 
the  harsh  realities  of  their  situation.  Such 
a  denial  of  the  frustrating  realities  of  a 
situation  is,  of  course,  characteristic  of  all 
fantasy  and  wishful  thinking. 

The  behavior  of  these  subjects  was  simi- 
lar to  that  of  a  student  who,  having  en- 
dured one  frustration  after  another  in  his 
boyhood,  was  still  in  college  being  frus- 
trated both  in  his  scholastic  work  and  in 
his  social  relations.  Yet,  if  in  reality  his 
needs  were  frustrated,  in  fantasy  his  wishes 
were  fulfilled.  He  confided  that  when  he 
sat  in  a  classroom  he  paid  little  attention  to 
the  lecture,  for  he  found  it  easier  and  pleas- 
anter  to  indulge  in  the  fantasy  that  he  was 
the  head  of  a  large  office  and  that  all  the 


Effect  on  Perception  and  Imagination 


131 


other  members  of  the  class  (so  industri- 
ously taking  notes)  were  his  secretaries  and 
stenographers  busily  working  for  him. 
When  he  walked  from  one  building  to  an- 
other on  the  campus,  he  thought  of  each 
as  a  separate  city  or  town.  To  his  mind 
he  was  not  merely  passing  buildings  on  a 
campus;  he  was  speeding  over  the  highways 
from  one  city  to  another  in  a  high-powered 
car.  And  when,  one  night,  he  was,  in 
reality,  walking  along  a  country  road  with 
two  of  his  friends,  it  seemed  to  him  in  his 
fantasy  that  they  were  a  couple  of  the 
enemy  whom  he  had  captured  in  a  lone 
raid  into  no  man's  land  and  whom  he  now 
was  escorting  back  to  his  own  lines— for 
which  brave  action  he  was  soon  to  be  deco- 
rated. 

The  fields  of  this  student  deviated  far 
from  the  objective  realities  of  his  everyday 
situations.  Since  he  found  in  them  a 
pleasant,  vicarious  satisfaction  of  the  needs 
which  were  in  reality  frustrated,  his  fan- 
tasies constituted  escapes  from  this  reality. 
We  all  indulge  in  such  flights  from  reality 
from  time  to  time,  when  our  needs  are  ex- 
cessively frustrated.  We  return  from  them 
frequently  with  renewed  vigor  and  strength 
to  force  the  satisfaction  of  our  needs  on 
the  level  of  reality.  As  a  matter  of  fact, 
the  very  distortion  that  our  fields  undergo 
at  such  times  may  suggest  to  us  the  way 
in  which  we  can  in  reality  satisfy  our  needs. 
There  is  always  the  danger,  however,  that 
such  flights  from  reality  will  cease  to  be 
momentary  or  of  relatively  short  duration 
and  will  become  instead  permanent.  It  is 
in  this  sense  that  the  delusions  characteris- 
tic of  certain  mental  disorders  are  merely 
extreme  and  lasting  distortions  of  the  pa- 
tients' fields  by  their  needs.  The  poor  man 
whose  need  for  material  things  has  been 
enduringly  frustrated  may  end  by  living  in 
a  fantastically  distorted  field  in  which  he  is 


fabulously  wealthy,  although  in  leality  he 
is  an  inmate  of  a  mental  hospital. 

Less  marked  and  less  pathological  exam- 
ples of  the  organization  of  a  field  by  a  need 
can  be  seen  in  everyday  life.  When  two 
persons  behave  differently  in  the  same  ob- 
jective situation,  they  do  so  because  the  sit- 
uation is  for  each  a  different  field. 
Whereas  one  individual's  need  for  atten- 
tion may  make  him  see  a  group  of  indif- 
ferent strangers  as  an  appreciative  audi- 
ence before  whom  he  must  show  off,  an- 
other's need  for  inviolacy  may  cause  him 
to  perceive  the  members  of  the  same  group 
as  hostile  critics  from  whom  he  must  shrink 
and  withdraw.  That  Napoleon's  need  for 
superiority  often  determined  the  structure 
of  his  fields  is  revealed  in  his  remark  to  an 
attendant  prior  to  the  meeting  of  an  Aus- 
trian conference.  "Carry  that  chair  away 
before  we  begin.  I  have  never  been  able 
to  see  a  raised  chair  without  wanting  to 
sit  in  it." 

Explorers  who  have  been  forced  to  live 
on  short  rations  or  whose  food  supplies 
have  become  exhausted  have  often  reported 
their  preoccupations  at  such  times  with 
thoughts  of  food.  During  the  day  their 
conversations  have  been  mostly  about  the 
preparation  of  food;  at  night  their  dreams 
have  been  of  sumptuous  feasts. 

In  one  investigation  of  the  effects  of  ab- 
stinence from  food  upon  imaginal  proc- 
esses, subjects  were  given,  at  various  inter- 
vals after  eating,  a  series  of  tests  in  which 
ambiguous  or  incomplete  material  had  to 
be  interpreted  or  completed.  \Vith  all  the 
tests  it  was  found  that,  as  the  incenal  of 
time  since  the  last  meal  ina'eased,  the  num- 
ber of  interpretations  or  completions  which 
referred  to  food  also  increased.  ^Vhen,  for 
example,  the  subjects  ^vei'e  given  a  word- 
association  test  in  which  they  had  to  re- 
spond to  a  given  word  ^vitli  die  first  ^vord 


132 


Motivation 


Avhich  came  to  mind,  hungry  subjects,  more 
often  than  others,  thought  of  such  words 
as  spoon,  fork,  eat  and  food.  In  another 
test  the  subjects  were  asked  to  tell  what 
was  going  on  in  a  series  of  pictures,  parts 
of  which  had  been  cut  away.  In  the  case 
of  one  picture  of  a  child  pointing,  subjects 
who  were  not  hungry  were  likely  to  inter- 
pret this  as  a  child  about  to  strike  a  key 
of  a  typewriter  or  about  to  pick  up  a  toy, 
whereas  hungry  subjects  were  inclined  to 
see  it  as  a  child  about  to  stick  his  finger 
in  a  pie  or  in  some  other  way  reacting  to 
a  food  situation. 

Tests  comparable  to  those  just  described 
for  hunger  have  been  used  to  determine, 
by  an  analysis  of  subjects'  responses,  the 
relative  strengths  of  other  needs.  Addi- 
tional tests  which  have  been  used  for  the 
same  purpose  are  a  musical  reverie  test,  in 
which,  while  a  number  of  phonograph  rec- 
ords are  played,  a  subject  allows  a  fantasy 
to  develop  which  he  later  reports  to  the 
experimenter;  an  odor  imagination  test  in 
which,  as  each  of  a  number  of  odors  is  pre- 
sented, a  subject  invents  some  episode  or 
story  from  the  first  idea  or  image  which 
comes  to  mind  upon  smelling  the  odor;  and 
a  thematic  apperception  test  in  which  the 
subject  is  presented  with  a  number  of  pic- 
tures and  asked  to  make  up  a  plot  or  story 
for  which  the  picture  might  serve  as  an  il- 
lustration. Such  tests  have  been  used  for 
the  measurement  of  needs  on  the  assump- 
tion that  the  stronger  a  need  the  greater 
will  be  its  effect  in  organizing  the  field. 
This  means  that  in  these  tests  the  stronger 
needs  of  the  individual  determine  the  con- 
tent of  the  fantasies  which  are  evoked  and 
the  nature  of  the  interpretations  and  com- 
pletions of  the  material  which  are  made. 

Since,  in  thus  reorganizing  the  percep- 
tual field  in  accordance  with  his  own  needs, 
the  subject  is  projecting  his  own  needs  into 


the  situation  which  he  faces,  these  means 
of  assessing  needs  have  been  called  pro- 
jective techniques,  procedures  which  have 
become  important  tools  in  the  assessment 
of  personality.     (See  pp.  495-497.) 

Effect  on  Sensitivity 

There  is  evidence  that  need  may  deter- 
mine an  increase  in  sensitivity.  Fasting 
persons  have  frequently  reported  that  they 
are  more  sensitive  to  odors  and  sounds  dur- 
ing fasting  than  at  other  times,  and  for 
such  statements  there  is  some  experimental 
confirmation  in  other  sensory  fields.  In 
one  case  it  was  found  that,  as  the  fast  was 
prolonged  (it  lasted  altogether  thirty-one 
days),  the  abilities  to  discriminate  tactually 
between  two  adjacent  points  on  the  skin 
and  visually  two  points  on  the  retina  were 
increased.  Studies  of  animals  and  infants, 
in  which  the  ease  of  evoking  a  response  is 
taken  as  a  measure  of  sensitivity,  also  indi- 
cate an  increase  of  sensitivity  to  various 
kinds  of  stimulation  under  conditions  of 
hunger. 

In  one  investigation  rats  were  allowed 
to  choose  between  distilled  water  and  weak 
solutions  of  salt.  With  concentrations  of 
salt  below  the  threshold  of  perception  nor- 
mal rats  showed  no  preference,  although, 
when  the  concentration  of  salt  was  in- 
creased to  0.055  per  cent  (about  one  part 
of  salt  to  2000  parts  of  water),  they  con- 
sistently preferred  the  salt  solution.  On 
the  other  hand,  rats,  whose  need  for  salt 
had  been  increased  by  the  removal  of  their 
adrenal  glands,  could  distinguish  much 
weaker  solutions,  for  they  chose,  in  prefer- 
ence to  distilled  water,  concentrations  of 
salt  as  low,  on  the  average,  as  0.003  per 
cent  (about  one  part  of  salt  to  33,000  parts 
of  water).  It  seems  clear  that  increased 
need  increases  sensitivity,  although  it  is 
not  so  clear  what  the  mechanism  is.     It  is 


Effect  on  Sensitivity  and  Persistence 


133 


more  likely  that  need  heiglileiis  attention 
in  these  rats  than  that  it  sensitizes  liicii 
taste  receptors. 

Eflfect  on  Persistence 

It  the  activity  of  an  indivichial  is  inter- 
rupted, we  should  expect,  from  the  defini- 
tion of  need,  that  the  residual  tension  re- 
maining after  the  interruption  would  cause 
the  individual  to  return  to  the  interrupted 
activity  and  to  attempt  again  to  reach  the 
original  goal.  A  number  of  experiments 
have  demonstrated  precisely  this  effect. 

In  one  experiment  subjects,  given  a  se- 
ries of  simple  tasks  to  perform,  were  al- 
lowed to  complete  some  of  them  but  were 
interrupted  before  finishing  the  others. 
When,  with  both  completed  and  inter- 
rupted tasks  within  reach,  the  subjects  were 
left  free  to  do  whatever  they  desired,  it  was 
found  that,  whereas  they  almost  never  took 
up  the  completed  tasks  again,  presumably 
because  their  corresponding  tensions  had 
been  discharged,  they  resumed  the  inter- 
rupted tasks  in  about  eighty  per  cent  of  the 
cases. 

In  another  investigation  subjects  were 
asked  to  help  the  experimenter  in  thinking 
of  words  beginning  with  a  certain  letter. 
After  writing  down  as  many  words  as  they 
could  think  of  within  the  allotted  time, 
some  of  the  subjects  were  told  that  they 
had  done  unusually  well,  whereas  others 
were  told  that  they  had  done  very  poorly. 
The  intention  of  the  experiment  was  to 
create  for  some  subjects  an  experience  of 
success  and  for  others  an  experience  of 
failure.  When,  two  weeks  later,  the  sub- 
jects were  questioned  as  to  whether  they 
had  thought  in  the  interim  of  words  begin- 
ning with  the  assigned  letter,  there  was  con- 
siderable evidence  that  they  had  had  diffi- 
culty in  keeping  their  minds  off  the  origi- 


nal   task.      One   siibject,    wiio   had   experi- 
enced failure,  reported: 

"As  soon  as  the  experiment  was  over  C- 
words  came  flooding  into  my  mind.  On 
my  way  home  1  felt  that  I  should  go  insane 
if  I  contiiuied  to  think  of  them,  so  I  de- 
termined to  banish  them  by  thinking  of 
other  things.  At  intervals  thereafter  C- 
words  would  slip  into  my  thoughts  when  I 
was  not  expecting  them,  but  they  gradually 
ceased  coming." 

In  general  the  persistence  of  the  activity 
was  greater  for  those  who  had  felt  frus- 
trated in  the  original  experiment,  presum- 
ably because  of  the  greater  unresolved  ten- 
sion which  tended  to  continue  the  original 
activity  until  it  was  terminated  by  the  ful- 
filment of  the  original  purpose.  We  often 
experience  in  everyday  life  the  persistence 
of  activities  which  have  failed  to  reach  their 
goals.  Having  done  poorly  in  an  examina- 
tion, we  continue  to  think  of  all  the  things 
we  should  have  written  but  did  not. 
Worsted  in  an  argument,  we  can  think  of 
nothing  but  the  brilliant  things  we  failed 
to  say. 

Experiments  such  as  these,  as  well  as  the 
observation  of  persisting  activities  in  every- 
day life,  demonstrates  that  tasks  which  have 
been  undertaken,  like  any  purpose  or  in- 
tention, set  up  tendencies  within  the  indi- 
vidual which  keep  him  at  work  until  the 
goals  thus  set  are  attained.  It  must  be 
noted,  however,  that  in  the  experiments 
reported  above  no  conflicting  purposes  or 
intentions  were  aroused,  as  there  might 
well  have  been  and  as  there  often  are  in 
everyday  life.  These  experiments,  there- 
fore, offer  no  guarantee  tliat  all  human  be- 
ings will  always  complete  their  incompleted 
tasks  if  given  an  opportunity.  In  some  in- 
dividuals tlie  need  for  initiating  new  ac- 
tion may  be  stronger  than  the  need  for  fin- 
ishing work  already  begun. 


134 


Motivation 


Since  the  residual  tensions  of  incom- 
pleted tasks  may  cause  preoccupation  with 
these  activities,  we  should  expect  to  find 
that  incompleted  tasks  tend  to  be  better 
remembered  than  finished  ones.  This  ex- 
pectation is  verified.  If  subjects  are  given 
a  series  of  simple  tasks  to  perform,  are  al- 
lowed to  finish  one  half  of  them  but  are 
interrupted  before  they  have  completed  the 
other  half,  and  then  are  asked  immediately 
after  the  experiment  to  recall  all  the  tasks 
which  they  have  attempted,  they  can  recall 
incompleted  tasks  almost  twice  as  often  as 
finished  ones. 

Frustration  Tolerance 

The  effects  of  need  upon  the  behavior 
and  consciousness  of  the  individual  depend 
to  a  large  extent  upon  the  degree  of  ten- 
sion in  the  given  case.  Some  degree  of 
need  is  necessary  for  psychobiological  adap- 
tation, for  otherwise  the  organism  is  inert. 
In  order  that  learning  may  occur,  there 
must  be  some  degree  of  tension  to  reorgan- 
ize a  field,  but  we  have  already  seen  that 
an  excess  of  tension  resulting  from  a  pro- 
longed blocking  of  a  strong  need  may  cause 
a  field  to  be  so  grossly  distorted,  as  in  the 
delusions  of  mental  disorders,  that  it  no 
longer  bears  any  resemblance  to  the  situa- 
tion. Tension  increased  beyond  a  critical 
point  results  in  a  failure  of  adjustment  of 
the  organism  to  the  requirements  of  the  sit- 
uation. These  facts  have  suggested  the  fruit- 
fulness  of  a  concept  of  frustration  tolerance, 
which  has  been  defined  as  the  amount  of 
frustration  xuhich  can  be  borne  without  a 
resultant  failure  in  psychobiological  ad- 
justment. The  frustration  tolerance  of  an 
individual  is,  then,  his  capacity  to  stand 
frustration  without  distorting  his  field  so 
that  it  no  longer  bears  a  valid  resemblance 
to  the  real  situation. 

The  frustration  tolerance  of  an  individ- 


ual is  exceeded  in  all  cases  in  which  the 
increased  tension  resulting  from  frustration 
causes  the  individual  to  react  inadequately 
to  the  situation.  If,  instead  of  modifying 
his  behavior  in  such  a  way  as  to  effect  a 
satisfaction  of  his  frustrated  needs,  he  re- 
acts with  crying,  temper  tantrums,  regres- 
sion to  more  primitive  behavior  or  a  break- 
down of  the  personality  in  any  of  the  vari- 
ous forms  of  mental  disorder,  the  individ- 
ual's tolerance  for  frustration  has  clearly 
been  exceeded. 

Just  as  there  is  a  point  beyond  which  the 
primary  needs— for  example,  the  need  for 
oxygen— cannot  be  denied  satisfaction  with- 
out a  collapse  of  the  organism,  so  there  is 
also  a  point  beyond  which  the  secondary 
needs— for  example,  the  need  for  freedom— 
cannot  be  frustrated  without  a  breakdown 
of  the  individual.  One  of  the  important 
problems  of  psychology  is  to  discover  the 
conditions  which  determine  not  only  the 
general  frustration  tolerance  of  the  individ- 
ual but  also  his  specific  tolerance  for  the 
frustration  of  different  needs. 

INDIVIDUAL    DIFFERENCES    IN 
RESPECT    OF    NEEDS 

The  terms  with  which  we  characterize 
persons  are  often  merely  short  statements 
about  the  need  or  needs  which  most  often, 
or  at  least  most  obviously,  motivate  them. 
When  we  say  of  a  man,  "He  is  a  show-off," 
we  are,  in  eff^ect,  saying  that  he  has  a  strong 
need  for  attention;  and,  when  we  say  of 
another,  "He's  a  go-getter,"  we  are  recog- 
nizing in  him  a  strong  need  for  superiority. 
Such  characterizations  point  to  the  fact, 
which  we  have  already  noted,  that  not  all 
the  needs  of  an  individual  are  equally 
strong,  and  that  the  differences  among  per- 
sons are  at  least  in  part  determined  by  dif 


Individual  Differences  in  Needs 


135 


I'erences  in   the  relative  strengths  of   iheir 
needs.' 

Other  differences  in  personality  are  de- 
termined by  differences  in  the  relationships 
ol  needs.  It  is  important  to  know  wiiich 
ol'  an  individual's  needs  are  regularly  acti- 
vated in  the  service  of  other  more  impor- 
tant needs.  An  individual  may  be  mo- 
tivated to  collect  rare  antiques  in  order 
that  he  may  show  them  off  to  his  friends 
and  thus  gain  a  satisfaction  of  his  needs 
lor  attention  and  superiority.  If,  however, 
he  does  not  have  the  money  with  which  to 
buy  expensive  antiques,  he  may  be  mo- 
tivated to  gain  his  goals  of  attention  and 
superiority  in  some  other  way,  perhaps  by 
developing  and  exhibiting  athletic  skill. 
We  may  find  at  different  times  different 
particular  needs  serving  the  dominant  need 
of  a  given  individual.  We  know,  however, 
a  great  deal  about  a  person  if  we  know, 
over  a  period  of  time,  which  needs  pri- 
marily determine  his  behavior  and  which 
needs  are  more  or  less  consistently  subsid- 
iary to  these  dominant  needs.  An  impor- 
tant difference  among  persons  occurs  in  re- 
spect of  the  subsidiary  relationships  which 
exist  among  their  needs.  One  man  may 
gain  his  superiority  by  cruelty  to  his  sub- 
ordinates; another  man  may  gain  his  su- 
periority by  generosity  to  his  subordinates 
Both  may  get  what  they  want— importance, 
recognition,  prestige. 

There  are  varying  degrees  with  which 
one  may  be  consciously  aware  of  his  own 
needs.  At  one  extreme,  a  man  may  have 
no  awareness  at  all  of  what  he  wants.  He 
may  not  even  be  aware  of  any  tension  or 
uneasiness.  At  the  other  extreme,  a  man 
may  know  precisely  what  it  is  he  is  after. 
An  intermediate  degree  of  awareness  is  the 
case  where  a  person  recognizes  that  some- 
thing is  lacking,  that  he  is  uneasy  and  dis- 
satisfied,   and    yet   he    cannot    say    exactly 


what  it  is  he  wants.  No  one  is  aware  of 
all  his  needs  at  all  times,  but  some  persons 
have  much  more  insight  than  others  into 
their  basic  motivations. 

A  need  may  fail  to  be  recognized  berausc 
it  is  relatively  weak  in  comparison  with 
other  needs,  which  for  the  moment  domi- 
nate the  consciousness  and  behavior  of  the 
individual.  More  important  in  its  conse- 
quences for  the  personality,  however,  is  the 
failure  of  a  person  to  recogni/e  a  need  be- 
cause it  is  in  conflict  with  his  consciously 
recognized  and  accepted  needs. 

The  consciously  recognized  and  accepted 
needs  of  the  person  are  often  called  his 
ego  needs,  since  the  ego  is  defined  as  that 
part  of  the  person  which  is  consciously 
knowing,  desiring  and  willing.  Needs 
which  are  recognized  as  one's  own  and  for 
the  satisfaction  of  which  one  takes  respon- 
sibility are  ego  needs.  Ideals  which  a  man 
consciously  sets  for  himself  and  for  which 
he  strives  are  ego  ideals.  The  ego  is  an  im- 
portant factor  in  motivation.  The  need  or 
needs  which  are  most  important  to  the  ego 
are  those  which  most  clearly  distinguish 
one  person  from  another.  They  are  the 
more  enduring  needs  of  the  ego;  yet  needs, 
which  at  one  time  are  central  to  the  ego, 
absorbing  all  its  energies,  may  at  other 
times  become  quite  unimportant. 

In  general,  needs  -ivhich  are  smoothly 
and  silently  satisfied  do  not  in\ol\e  the 
ego.  Though  die  need  for  oxygen  is  one 
of  man's  most  vital  needs,  the  satisfaction 
of  it  does  not  involve  his  ego,  since  air  is 
free  and  he  ordinarily  gets  all  he  wants  of 
it  unconsciously  and  automatically.  But, 
if  air  were  not  free,  if  getting  it  depended 
upon  the  cooperation  of  others  or  if  one 
had  to  compete  for  it,  the  need  for  oxygen 
would  become  an  ego  need  as  the  needs  for 
sex,  affection,  recognition,  superiority  so 
often  are. 


136 


Motivation 


Many  of  the  effects  o£  residual  need  ten- 
sion described  earlier  in  this  chapter  are 
more  pronounced  when  they  derive  from 
ego  needs,  and,  in  tlie  absence  of  ego  in- 
volvement, they  may  not  be  observed  at  all. 
Interrupted  tasks,  for  example,  are  more 
often  resumed  and  better  remembered  than 
completed  ones  only  if  the  tasks  which 
have  been  undertaken  have  really  involved 
the  ego. 

The  typical  shifts  in  a  person's  level  of 
aspiration  in  attempting  to  solve  tasks  of 
\arying  degrees  of  difficulty,  the  raising  of 
the  level  of  his  aspiration  after  success  and 
the  lowering  of  it  after  failure,  occur  most 
strikingly  for  those  tasks  in  which  a  person 
is  deeply  egoistically  involved.  If  the  same 
set  of  tasks  is  given  twice  to  the  same  per- 
sons, once  as  'practice'  and  once  as  'a 
test,'  the  shifting  of  the  level  of  aspiration 
—up  after  success  and  down  after  failure- 
is  greater  when  the  tasks  are  understood  to 
be  a  test  measuring  the  ability  of  the  indi- 
vidual and  not  merely  practice.  In  other 
words,  if,  when  setting  our  level  of  aspira- 
tion, there  is  something  at  stake  for  our 
ego,  we  behave  more  cautiously. 

Other  experiments  as  well  as  observa- 
tions of  everyday  behavior  suggest  that  ego 
motivation  tends  to  be  strong  motivation. 
Ego  needs  are  frequently  selfish  needs,  but 
not  always.  "Whether  they  are  or  not  de- 
pends upon  the  person,  for  in  so  far  as  a 
person  identifies  himself  with  others  and 
experiences  their  needs  as  his  own,  his  mo- 
tivation ceases  to  be  narrowly  egocentric, 
becoming  instead  sociocentric.  Such  com- 
mon sociocentric  motivation  characterizes 
all  successfully  integrated  groups  which  are 
held  together  by  mutual  loyalty— from  the 
wedded  pair  up  through  many  kinds  of  so- 
cial groups  to  the  nation  itself.  Those  per- 
sons who  liopc  for  the  democratization  of 


the  world  ancl  the  achie\cmcnL  of  interna- 
tional peace  base  their  aspiration  on  this 
possibility  of  combatting  egocentric  aggres- 
sion with  this  sociocentric  identification. 
(For  more  on  the  ego,  see  pp.  567-570.) 

REFERENCES 

1.  Katz,  D.  Anunals  and  men.  New  Voik:  Long- 
mans, Green,  1937. 

A  provocative  discussion  of  problems  of  com- 
parative psychology  based  upon  the  author's  in- 
genious observations  and  experiments. 

2.  Kinsey,  A.  C,  Pomeroy,  W.  B.,  Martin,  C.  E. 
Sexual  behavior  in  Ihc  liunian  male.  Phila- 
delphia: Saunders,  1948. 

A  scientific  account  of  sexual  behavior  writ- 
ten by  leading  authorities  on  the  subject,  from 
the  point  of  vie^^'  of  biology,  psychology  and 
sociology. 

3.  Klineberg.  O.  Race  differences.  New  'S'ork: 
Harper,  1935. 

A  clear  and  simple  survey  of  the  findings  of 
the  biological,  psychological  and  cultural  ap- 
proaches to  the  problem  of  race  differences. 

4.  Kohler,  W.  The  mentality  of  apes.  New  York: 
Harcourt,  Brace,  1925. 

A  Gestalt  psychologist's  report  on  the  behav- 
ior of  chimpanzees  and  the  role  of  insight  and 
intelligence  in  their  solution  of  detour  prob- 
lems. 

5.  Lewin,  K.  A  dynamic  theory  of  personality. 
New  York:  McGraw-Hill,  1935. 

The  beginnings  of  this  author's  dynamic  psy- 
chology as  illustrated  in  his  early  theoretical 
discussions  and  experimental  findings. 

6.  Mead,  M.  Sex  and  temperament  in  three  prim- 
itive societies.  New  York:  William  Morrow, 
1935. 

An  anthropologist's  report  of  differences  in 
culture  and  personality  in  three  geographically 
closely  situated  primitive  societies. 

7.  Muenzinger,  K.  V.  Psychology:  the  science  of 
behavior.     New  York:   Harper,  1942. 

A  systematic  introductory  text  in  psychology 
which  gives  a  central  position  to  the  concept  of 
motivation. 


References 


137 


8.  Murray,  H.  A.,  «/  «i.  Explorations  in  per- 
sonality. New  York:  Oxfoid  University  Press, 
1938. 

'Die  fiii(lin)>s  ol  ;i  (liiiic;il  ;iii(l  ex|jci  inienliil 
study  of  fifty  men  ol  rolle^c  a^e  |)reseiilecl  in 
conjmiclion  with  a  dynamic  Ihcory  o(  per- 
sonality. 

9.  Sharif,  M.  Tlie  psychulo<^\  of  social  norms. 
New  Yorlc:   Harper,   1936. 

A  clear  and  simple  discussion  of  the  ways 
in  which  individual  frames  of  reference  of  ex- 
perience and  social  norms  of  behavior  become 
established. 


10.  VVarflcn,  C.   J.:  Animal  motivation.     Sew  V'ork: 
Columbia  I'niversity  Press,  IO.?l. 

Siiidies  of  various  drives  in  the  uhirc  rat  by 
nif.ins  of  llic  obsiruflion    mcltiod. 

11.  ^oMrjj;,     I',      1.       'Ilir     iii'itiralion    of    hehai'ior. 
New   Vork:    Wiley,   1936. 

A  comprehensive  review,  presented  in  text- 
book form,  of  experimental  investigations  of 
the  motivational  ijases  of  behavior. 

12.  Young,    P.    T.      Emotion    in    man    and    animal. 
New  York:   Wiley,   1943. 

A  comprehensive  review  of  experimental 
studies  of  emotion  which  stresses  the  role  of 
emotions  as  motivatiiif'  factors  in   behavior. 


CHAPTER 


7 


Learning 


OUR  ability  to  profit  from  past  experi- 
ence is  one  of  our  most  valuable  as- 
sets. Learning— the  process  by  which  we  do 
this— is  the  subject  of  this  chapter.  In  it  we 
shall  analyze  the  conditions  under  which 
learning  takes  place.  We  shall  discover 
that  the  same  principles  which  account  for 
our  learning  of  desirable  and  appropriate 
reactions  also  explain  our  acquiring  of  un- 
ilesirable  bad  habits. 

We  can  best  appreciate  the  important 
role  which  learning  plays  in  our  lives  if  we 
recall  what  a  limited  repertoire  of  re- 
sponses a  human  infant  possesses  at  birth. 
As  we  have  seen,  all  learning  depends  upon 
maturation,  which  fits  the  organism  for 
learning.  On  the  other  hand,  all  the  in- 
crease in  capacity  and  complexity  which 
cliaracterizes  mature  adult  behavior  must 
be  attributed  to  learning.  We  learn,  for 
instance,  to  eat  the  things  we  eat  in  the 
way  we  eat  them,  to  respond  as  we  do  to 
other  people  and— the  crowning  achieve- 
ment of  the  human  being— to  use  language. 
We  learn  not  only  to  use  language  for  com- 
munication but  to  use  it  also  to  satisfy  our 
needs  and  to  control  the  behavior  of  other 
people.  Nor  is  learning  only  intellectual. 
Likes  and  dislikes,  emotional  responses, 
most  of  the  complex  pattern  of  reactions 
which  we  call  personality,  all  are  learned. 
Most  of  this  learning  occurs  informally  in 


the  give  and  take  of  daily  life,  for  learning 
is  by  no  means  always  intentional  or 
formal. 

The  very  fact  that  learning  is  so  per\'asive 
and  bound  into  the  warp  and  woof  of  our 
daily  lives  results  in  the  process  going  al- 
most unremarked.  When  we  notice  it  at 
all,  Ave  think  of  it  in  rough,  unanalytic 
terms;  but,  if  we  seek  to  understand  it  and 
its  principles,  detailed  analysis  is  essential. 
As  a  consequence,  much  of  our  understand- 
ing of  learning  behavior  is  derived  from 
controlled  laboratory  experiments.  The 
careful  laboratory  analysis  of  learning  re- 
quires the  use  of  materials,  methods  and 
concepts  which  at  first  appear  to  be  strange 
and  divorced  from  the  learning  of  every- 
day life.  Nevertheless,  learning  in  the  lab- 
oratory is  really  the  same  in  kind  as  the 
learning  which  pervades  evei^day  life. 
What  the  laboratory  does  is  simply  to  pro- 
vide a  better  situation  for  analyzing  the 
learning  process. 

ASSOCIATIVE    LEARNING 

Learning  varies  greatly  in  complexity. 
We  shall  begin  oiu-  analysis  with  a  very 
simple  type,  associative  learning,  which 
consists  of  the  formation  of  associations  be- 
tween responses  and  the  stimuli  which  are 
present    when    those    responses    are    made. 


This  chapter  was  prepared  by  Carl  I.  Hovland  of  Yale  University. 


138 


Conditioning 


139 


Assoriatiun  is  a  toinmoii  phenomenon,  ex- 
emplified by  our  'being  reminded  ol'  an  ex- 
jjeriente  by  stimuli  wlii<li  were  present 
durinf^  the  experienee.  Tlie  odor  of  a  burn- 
ing wood  fire  may  lecall  a  Cinistmas  vaca- 
tion in  the  north  woods,  or  magnolia  blos- 
soms may  remind  us  of  a  (hildhood  trip 
to  the  Soutli.  Often,  l)ut  l)y  no  means  al- 
ways, wc  have  been  aware  of  lliese  stinudi 
in  the  oiiginal  situation  of  which  we  are 
now  reminded. 

Ihis  phenomenon  has,  oE  course,  been 
known  lor  a  long  time,  and  philosophers 
lor  two  centuries  have  called  attention  to 
the  "association  of  ideas."  Careful  study 
of  the  conditions  under  which  stimuli  and 
responses  are  associated  is,  however,  much 
more  recent.  It  really  begins  about  1903 
with  the  work  of  Pavlov,  which  we  have  al- 
ready noted  in  a  previous  chapter.  Pavlov, 
while  studying  problems  in  the  physiology 
of  digestion,  made  the  observation  that  ani- 
mals salivate  not  only  to  food  but  also  in 
response  to  the  various  stimuli  which  in 
their  experience  invariably  precede  the  in- 
troduction of  food,  like  the  clicking  of  a 
food  release  mechanism.  Salivation  to 
stimidi  of  this  type,  which  were  not  orig- 
inally effective,  he  called  "psychic  secre- 
tion." 

Conditioning 

I'his  phenomenon  fascinated  Pavlov, 
and  as  a  consequence  he  devised  a  series 
of  experiments  to  determine  the  conditions 
inider  which  it  occurred.  Mostly  he  used 
dogs  as  the  experimental  animals.  He 
chose  the  salivary  response  for  study  be- 
cause it  provided  a  sensitive  measure  of 
the  magnitude  of  response.  (See  Fig.  45.) 
He  performed  a  simple  surgical  operation 
by  which  the  flow  of  sali\'a  from  the  dog's 
jowl  is  transmitted  through  a  glass  tubing 
to  a  measuring  instrument. 


To  establish  a  connection  between  a  re- 
sponse, like  salivation,  and  an  initially  in- 
effective stimulus,  like  the  sounding  of  a 
buzzer,  Pavlov  found  that  it  was  essential 
to  pair  the  presentation  of  the  new  stimu- 
lus with  the  one  which  was  originally  ef- 
fective. I'or  example,  he  would  sound  the 
buzzer  at  the  time  he  presented  the  food  to 


FIGURK  45.      PAVLOV  S  ^fETHOD  OF  ESTABLISHING   A 
CONDITIONED    SALIVARY    REFLEX 

The  unconditioned  stimulus  (food)  is  presented 
automatically  in  the  small  dish  through  the  win- 
dow. At  the  same  time,  or  earlier,  the  conditioned 
stimulus  (the  ringing  of  a  hell)  is  given.  The  saliva 
which  flows  through  a  tuhe  from  the  dog's  jowl  is 
collected  in  the  graduated  class  receptacle.  As  the 
saHva  flows  into  the  receptacle,  it  strikes  a  small 
disk  which  depresses  the  lever  just  in  fiont  of  the 
animal.  This  downward  movement  is  transmitted 
to  the  lever  behind  the  screen,  and  an  automatic 
tracing  is  thus  secured  upon  a  smoked  drum  or 
kymograph.  The  kvmographic  record  tells  the  ex- 
perimenter how  many  drops  of  saliva  have  been 
secreted  and  how  regular  the  flow  has  been.  [From 
R.  M.  Yerkes  and  S.  Morgulis,  The  method  of  Pav- 
lov in  animal  psvchologv,  Psychol.  Bull.,  1909.  6, 
264.] 

the  dog.  or  just  before.  The  response 
which  ^vas  thus  learned  he  called  a  condi- 
tioned response  because  it  was  dependent 
upon  conditions.  The  process  is  still  re- 
ferred to  as  conditioning.  The  stimulus 
which  originally  produced  die  response  A\as 
called  the  unconditioned  stimulus,  and  tlie 
new  one  -with  which  the  response  was  be- 
ing connected  bv  conditioning  was  called 


140 


Learning 


the  conditioned  sdiniilus.  In  Pavlo\ 's  lab- 
oratory food  Avas  customarily  the  original 
stimulus,  and  the  sound  of  a  bell  or  buzzer, 
the  conditioned  stimulus.  After  a  nimiber 
of  trials  the  sound  of  the  buzzer  alone  elic- 
ited some  secretion  of  saliva.  \Vith  more 
trials  the  amoimt  of  saliva  secreted  for  the 
buzzer  alone  would  increase  until  it  finally 
became  nearly  as  great  as  to  the  sight  of 
food  itself. 

We     can     diagram     this     process     c^uite 
simply. 

Before  Conditioning 

Response 
Conditioned  Stimulus 

Buzzer >  Listening,  etc 

Unconditioned  Stimulus 
Sight  of  Food    — ♦    Salivation 


After  Conditioning 

Response 
Conditioned  Stimulus 

Buzzer , 

Unconditioned  Stimulus       i 


At  an  earlier  period  of  time,  when  the 
dog  was  a  tiny  puppy,  the  response  of  sali- 
vating to  the  sight  of  food  was  established 
through  conditioning.  Food  in  the  mouth 
was  at  that  time  the  unconditioned  stimu- 
lus. This  initial  conditioning  would  be 
diagiammed  as  follows. 


Before  Conditioning 

Responsi: 
Conditioned  Stimulus 

Sight  of  Food *  Looking  at 

it,  etc. 

Unconditioned  Stimulus 
Food  in  Mouth   — ♦   Salivation 


After  Conditioning 

Response 
Conditioned  Stimulus 
Sight  of  Food 


Uncondition-ed  Stimulus 

Food  in  Mouth   — >  Salivation 


Factors  AfFecting  Conditioning 

Pavlov  and  his  students  kept  careful  rec- 
ords of  some  of  the  factors  influencing  the 
association  formed  between  the  condi- 
tioned and  unconditioned  response.  These 
relationships  have  been  further  studied  in 
American  laboratories  so  that  today  we 
know  a  great  deal  about  the  phenomena  of 
conditioning.  Some  of  the  more  impor- 
tant conclusions  follow. 


(1)  Acquisition.  Repetition  of  the  pair- 
ing of  the  conditioned  and  unconditioned 
stimuli  increases  the  strength  of  the  con- 
nection until  a  point  is  reached  where  no 
further  observable  gain  is  obtained.  A 
sample  acquisition  curve  is  shown  in  Fig. 
46.  These  results  correspond  to  our  every- 
day experience  that  learning  is  favored  by 
repetition. 


250 


Sight  of  Food    — ►    Salivation         ~ 


6  8         10         12        14        16 

Units  of  training 

FIGURE    46.       ACQUISITION    OF    A    SALIVARY    CONDI- 
TIONED   RESPONSE 

Composite  curve  of  the  data  from  four  clop;s.  [As 
given  by  N.  Kleitman  and  G.  Crisler.  and  plotted 
by  C.  L.  Hull  in  Handbook  of  general  experimental 
psychology,  1934,  p.  425;  by  permission  of  the  Clark 
University  Press.] 

(2)  Time  faclors.  There  is  an  optimal 
time  between  the  presentation  of  the  con- 
ditioned and  unconditioned  stimuli,  and 
time  intervals  more  remote  from  the  latter 
are  progressively  less  effective.  The  graph 
(Fig.  47)  shows  the  percentage  of  condition- 
ing at  each  of  several  different  time  inter- 
vals between  the  conditioned  and  uncon- 
ditioned stimuli.  The  unconditioned  stim- 
ulus in  this  experiment  was  an  electric 
shock  which  produced  finger  withdrawal, 
and  the  conditioned  stimulus  was  a  sound 
signal  which  initially  produced  no  finger 
response.  In  this  case  the  optimal  time 
interval  was  that  in  which  the  conditioned 


Conditioning 


141 


stimiiliis  was  presented  about  a  half -second 
before  the  unconditioned  stinndus.  I'lie 
situation  in  wiiich  the  conditioned  stinndus 
comes    after    the    unconditioned    stimulus 


witJi  a  pitch  corresponding^  to  1000  cycles 
per  second,  the  j^reatest  response  will  \}e 
made  to  this  Irefjuency,  a  smaller  response 
to   a   frefjuency  ol   800   cycles,   and  a  still 


(called    backward    rnndilioninii)    produced      smaller  response  to  600  cycles.     Fif^ure  48 

presents   an   experimentally   derived   curve 
of  generalization. 

(4)  Differentiation.  As  learning  pro 
ceeds,  the  range  of  stimidi  which  touch  oil 
ihe  ccjnditioned  response  becomes  jjrcjgres- 
sively  reduced.  This  process  is  called 
differentiation.      Thus    after    a    while    the 


O  ^  -H  ^ 


Number  of  seconds  by  which 
conditioned  stimulus  preceded 

FIGURE    47.       STRENGTH    OF    CONDITIONING    AS    DE- 
PENDENT    ON     TIME     RELATIONS     BETWEEN     CONDI- 
TIONED   AND    UNCONDITIONED    STIMULUS 

Graph  shows  greatest  efficiency  when  conditioned 
stimulus  precedes  unconditioned  stimulus  by  halt 
a  second.  Negative  times  means  that  the  uncondi- 
tioned stimulus  precedes  the  conditioned  stimulus. 
[After  H.  M.  Wolfle,  from  C.  L.  Hull  in  Handbooli 
of  general  experimental  psy etiology,  1934,  p.  420; 
by  permission  of  the  Clark  University  Press.] 

soine  learning,  but  it  was  not  nearly  so 
effective  as  the  situation  where  the  condi- 
tioned stimtdus  was  presented  before  the 
unconditioned  stimulus. 

(3)  Stimulus  generalization.  In  the  ini- 
tial  phases   of  learning,    the   organism   re- 


Stimuli 

FIGURE  48.      SENSORY  GENERALIZATION:    COMPOSITE 
CURVE 

Shows  amount  of  galvanic  skin  response,  after 
conditioning  to  various  standard  tonal  stimuli  (0  in 
the  graph),  that  is  given  for  other  tones  removed 
from    these   standards   by   25,  50   and   75  just   dis- 


sponds   not  only   to   the   exact   conditioned  criminable  differences  (represented  by  1.2  and  3  in 

stimulus  used  in  the  original  learning  but  S'^'P^^-    [J"™'"  C.  I.  Ho^land,  /.  geu.  Ps,c},ot.,  1937, 

r      .,...,         *     ,  17,  136.] 
also  to  a  variety  of  stimuli  similar  to  the 

one  used.    The  response  is  generally  great-  animal  conditioned  to  a  tone  of  1000  cycles 

est  to  tlie  conditioned  stimulus  and  pro-  „o  longer  responds  to  tones  of  600  or  800 

gressively  less  to  stimuli  more  and   more  cycles,  but  onh-  to  those  nearer  1000  cvcles. 

dissimilar  to  the  one  originally  used.    If,  for  By    giving   food    simultaneously   with    the 

example,  the  conditioned  stimulus  is  a  tone  conditioned  stimulus  and  not  giving  food 


142 


Learning 


with  any  other  stimukis,  you  can  finally 
produce  very  fine  discrimination  so  that, 
for  example,  an  animal  will  salivate  to  a 
tone  of  1000  cycles  but  not  to  one  of  1002 
cycles.  If  you  press  discrimination  too  far, 
however,  differentiation  is  broken  down 
and  disruption  of  behavior  occurs,  produc- 
ing sometimes  a  pattern  of  nervous  irrita- 


Extinction  trials 

FIGURE    49.    EXTINCTION    CURVE 

Diminution  of  response  in  successive  trials  with- 
out reinforcement.  Response  is  plotted  as  per  cent 
of  the  response  in  the  first  trial.  [From  C.  I.  Hov- 
l:nid,  Proc.  Nat.  Acad.  Sci.,  1936,  22,  431.] 

bility  which  has  been  called  'experimental 
neurosis.'     (See  pp.  526  f.) 

(.5)  External  inhibition.  When  stimuli 
other  than  those  used  in  the  conditioning 
are  presented  simidtaneously  with  or  just 
before  the  conditioned  stimulus,  they  fre- 
quently serve  to  reduce  the  size  of  the  re- 
sponse to  the  conditioned  stimulus.  Pav- 
lov's students  often  found  that,  having  set 
up  a  conditioned  response  in  a  dog,  they 
could  not  exhibit  it  to  Pavlov  becatise  his 
presence  in  the  room  inhibited  it.  This 
phenomenon  is  called  external  inhibition. 
We  notice  an  analogous  phenomenon  in 
more  complex  types  of  behavior.  For  ex- 
ample, recently  acquired  acts  of  skill  may 


be  disintegrated  by  a  distraction.  When 
one  has  jtist  mastered  a  difficult  passage  on 
the  piano,  the  appearance  of  a  stranger 
may  prevent  its  execution. 

(6)  Extinction.  Just  as  repetition  of  the 
pairing  of  the  conditioned  stimulus  and 
the  unconditioned  stimulus  strengthens  the 
connection,  presentation  of  the  conditioned 
stimulus  without  its  being  followed  by  the 
tuiconditioned  stimulus  resiUts  in  a  pro- 
gressive diminution  of  the  response.  The 
dog  no  longer  salivates  at  the  sound  of  the 
bell  after  the  bell  has  been  rung  a  certain 
number  of  times  without  food  following  it. 
The  size  of  response  on  successive  trials  of 
this  type  is  shown  in  Fig.  49.  These  lab- 
oratory extinctions  of  conditioned  re- 
sponses are,  however,  not  necessarily  per- 
manent. A  response  that  has  been  'extin- 
guished' may  recur  later,  a  phenomenon 
called  spontaneous  recovery. 

(7)  Higlier  order  co)iditioning.  We  have 
seen  how  Pavlov  chose  as  his  unconditioned 
response  the  production  of  salivation  in  a 
dog  by  the  dog's  sight  of  food.  We  have 
remarked  how  this  'unconditioned  re- 
sponse' is  itself  a  conditioned  response,  for 
it  had  to  be  learned  by  the  dog  when  a 
puppy.  The  original  tuiconditioned  re- 
sponse was  the  production  of  salivation  by 
the  feel  and  taste  of  food  in  the  dog's 
motith.  That  response  was  inherited  and 
developed  early  in  the  course  of  mattira- 
tion.  Then,  by  conditioning,  the  sight  of 
food  was  substituted  for  the  feel  and  taste 
of  food.  Pavlov's  substituting  the  sound 
of  the  buzzer  for  the  sight  of  the  food 
was  conditioning  at  a  second  level.  When 
conditioning  is  established  to  a  new  stimu- 
lus on  the  basis  of  a  previously  conditioned 
stimulus,  we  have  what  is  called  higlier  or- 
der conditioning.  It  is  an  extremely  im- 
portant aspect  of  conditioning  in  human 
beings  because  it  permits  learning  by  asso- 


Conditioning 


143 


(iation  to  stimuli  more  and  more  remote 
Irom  the  one  that  was  biologically  ade(|uate 
initially.  Pavlov  did  find,  however,  that 
the  farther  this  process  is  carried  the  more 
difficult  the  process  of  conditioning  be- 
'  comes. 

Other  investigators  have  studied  a  wide 
variety  of  stimuli  and  responses  but  have 
in  the  main  supported  Pavlov's  original 
findings.  Bechterev,  a  Russian  neurologist 
who  was  a  contemporary  of  Pavlov,  de- 
voted most  of  his  studies  to  a  type  of  con- 
ditioning called  conditioned  withdraival  in 
which  a  noxious  stimulus  producing  with- 
drawal is  used  as  the  unconditioned  stimu- 
lus. 


Before  Conditioning 

Response 
Cnndilioned  Stimulus 

Buzzer '  Listening,  etc. 

Unconditioned  Stimulus 
Shock  to 

Forepaw  — +  Withdrawal  of 
Limb 


After  CoNDiTioNiNt; 

Responsr. 
Conditioned  Stimulus 

Buzzer . 

Unconditioned  Stimulus 
Shocli  to  I 

Forepaw  — *  Withdrawal  of 
Limb 


In  other  respects  his  experimental  tech- 
nicjue  was  essentially  the  same  as  Pavlov's, 
and  it  has  been  the  method  most  widely 
used  in  America. 

Conditioned  Emotional  Responses 

The  simple  conditioned  responses  have 
been  studied  with  care  in  the  laboratory, 
but  they  are  by  no  means  just  a  laboratory 
phenomenon.  They  are  a  type  of  learn- 
ing that  we  see  all  around  us.  Language 
is  acquired  to  a  large  extent  through  this 
means.  The  infant  has  in  his  repertoire  of 
responses  a  large  number  of  random  sounds. 
The  selection  of  the  appropriate  sounds  to 
signify  objects  and  events  is  largely  deter- 
mined by  adult  behavior.  When  the  child 
utters  a  meaningless  sound,  no  consistent 
reaction  on  the  parents'  part  is  likely  to 
ensue,  and  Ikih  c  no  learning  occurs.     Hut 


when  a  meaningful  or  near-meaningful 
sound  is  made,  the  adult  repeats  the  sound 
after  the  (hild  and  may  give  the  child  tlic 
objed  named.  In  that  way  conditions  arc 
established  for  the  child's  learning  the 
word.  Vou  have  perhaps  observed  the  Ih:- 
havior  of  a  fond  father  when  his  child 
liajipens  to  say  a  word  like  "ted-di."  The 
father  repeats  the  sound  after  the  child 
and  hands  him  the  teddy-bear.  After  a  lew 
trials  the  child  will  say  "ted-di"  when  he 
wants  it  given  to  him.  (F'or  a  fuller  ac- 
count of  the  acquisition  of  language,  see 
pp.  594  1.) 

We  know  from  a  previous  discussion 
(pp.  101  f.)  how  experiments  by  Watson 
on  infants  showed  that  fears  can  be  estab- 
lished by  conditioning.  It  is  well  to  re- 
peat in  more  detail  the  observations  of 
his  experiments.  He  found,  first  of  all, 
that  a  neutral  object  could  be  made  fright- 
ening by  the  conditioning  technicjue.  The 
striking  of  a  steel  bar  near  the  baby's  ear 
originally  elicited  a  strong  fear  response. 
He  used  this  noise  as  the  unconditioned 
stimulus.  For  a  conditioned  stimulus  he 
used  a  white  rat  of  which  the  child  was 
initially  not  at  all  afraid.  Then  the  white 
rat  was  shown  to  the  child,  and  just  as 
he  reached  for  it  the  bar  was  struck.  The 
child  responded  with  symptoms  of  fear. 
This  procedure  was  repeated  several  times. 
Presently  the  child  showed  fear  of  the  pre- 
viously neutral  white  rat.  It  was  also  afraid 
of  a  rabbit,  a  fur  coat  and  even  of  cotton 
wool  (generalization),  but  it  did  not  fear 
building  blocks  (differentiation).  Repeated 
exposure  to  the  rat  giadually  reduced  the 
fear  when  it  was  not  followed  by  the  sound 
of  the  struck  steel  bai-  (extinction). 

A  vast  amount  of  clinical  material  indi- 
cates that  many  of  the  adult  intense  feai-s 
of  objects  and  places  {pliobias)  arc  trace- 
alilc  to  an  unfortunate  pairing  of  a  stiinu- 


144 


Learning 


lus  with  an  unpleasant  experience.  Often 
the  person  is  unable  to  recall  the  specific 
conditioning  experience  which  is,  never- 
theless, affecting  him.  Characteristically, 
such  a  fear  response  is  generalized  to  in- 
clude similar  stimuli  so  that  the  affected 
person  comes  to  fear  a  whole  class  of  ob- 
jects. Sometimes,  but  not  often,  such  a 
phobia  can  be  removed  by  extinction,  once 
the  relevant  stimulus  is  discovered  and  iso- 
lated. 

Anticipatory  Function  of 
Conditioned  Responses 

Although  it  is  typical  of  conditioning 
that  a  new  stimulus,  becoming  attached 
to  a  given  response,  has  the  power  to  call 
it  forth,  there  is  more  to  conditioning  than 
this  new  stimulus-response  connection.  As 
the  connection  becomes  established,  the  re- 
sponse to  the  conditioned  stimulus  occurs 
before  the  unconditioned  stimulus.  Sali- 
vation takes  place  before  the  food  is  eaten, 
the  knee  jerks  before  the  hammer  falls 
against  the  patellar  tendon,  the  eyewink 
occurs  before  the  puff  of  air  strikes  the  eye- 
ball, the  finger  is  removed  from  the  elec- 
trode before  the  shock  is  received.  It  will 
be  recognized  that  here  the  conditioned 
response  anticipates  the  unconditioned 
stimulus  and  in  many  cases  prevents  its 
occurrence. 

This  anticipatory  character  of  the  condi- 
tioned response  pervades  all  learning.  We 
are  able,  because  of  having  learned,  to  re- 
spond in  a  way  which  looks  to  the  future. 
We  can  learn  to  a\oid  harmfid  stimidi  be- 
fore they  strike  the  sense  organs.  The 
child,  once  burned,  avoids  the  stove.  The 
cow,  having  been  strongly  shocked  at  the 
electric  fence,  never  goes  near  it  again.  The 
results  of  such  learning  pyramid  greatly. 
The  word  danger  may  be  enough  to  warn 
us  from  a  region  where  noxious  stimidi  arc 


probable.  Words  of  all  kinds  accjuire  the 
power  to  guide  behavior  anticipatorily. 
From  the  simplest  forms  of  learning  to  the 
most  complex,  this  anticipatory  fimction, 
whereby  we  prepare  for  the  future,  is  con- 
tinuous. 

The  Law  of  Contiguity 

From  the  studies  of  conditioning,  certain 
authors  have  formidated  what  they  believe 
to  be  a  basic  law  of  learning,  the  law  of 
contiguity,  which  states  that,  when  tu'o 
psycliological  processes  occur  together  in 
time  or  in  immediate  succession,  the  prob- 
ability increases  that  an  associative  con- 
nection between  them  will  dex'elop.  It 
seems  clear  that  no  learning  takes  place 
without  fairly  close  psychological  contigu- 
ity between  the  terms  related  in  the  learn- 
ing. The  extent  to  which  this  principle 
must  be  supplemented  by  others,  especially 
by  motivation,  is  a  matter  to  wliich  we 
shall  come  presently. 

TRI  AL-AN  D-ERROR    LEARNING 

Not  all  learning,  however,  is  as  simple 
as  the  conditioned  response.  More  fre- 
quently our  task  is  to  learn  complex  se- 
quences of  responses  or  to  select  the  correct 
response  from  a  whole  category  of  possible 
responses. 

A  good  example  of  this  type  of  learning  is 
illustrated  by  an  experiment  of  Thorn- 
dike's.  A  hungry  cat  is  placed  in  a  cage, 
called  a  problem  box,  with  a  small  piece 
of  fish  lying  just  outside  (Fig.  50).  The 
box  is  designed  in  such  a  way  that  the  door 
of  the  cage  can  be  released  by  some  simple 
act  like  depressing  a  lever  inside  the  cage. 
At  first  we  see  a  great  deal  of  varied  activity 
on  the  part  of  the  cat:  clawing  at  the  wire, 
trying  to  squeeze  between  the  bars,  pawing 
and   shaking  movable   parts   of   the   appa- 


Trial-and-Error  Learning 


145 


ratiis.  Such  activity  is  ollcn  described  as 
random  or  trial-and-error.  Alter  a  time 
tlie  animal  succeeds  in  operating  the  lever 
i)y  accident,  and  gets  out.  It  is  tlien  al- 
lowed to  cat  a  bit  ol  the  fish  and  is  imme- 
diately returned  to  the  box  for  another 
Irial.  The  second  trial  may  not  differ 
much  from  the  hrst  with  useless  activity 
persisting  until  the  cat  happens  again  to 
operate  the  lever;  but  usually  the  time  on 
the  second  trial  is  shorter  than  on  the  first, 
and  on  successive  trials  both  the  time  and 
useless  movements  decrease  until  after 
enough  practice  the  cat  goes  immediately 
to  the  lever  and  lets  itself  out.  The  course 
of  its  learning  is  not,  of  course,  smooth  and 
regular.  On  a  trial  after  one  in  which  it 
has  performed  the  correct  response  quickly, 
it  may  go  through  so  much  trial-and-error 
activity  that  it  would  appear  that  it  had 
not  made  any  progress  at  all.  With  exten- 
sive practice,  however,  the  cat  makes  the 
correct  response  directly  with  a  minimum 
of  activity  iiTelevant  to  the  business  of 
escaping  from  the  box.  It  is  interesting, 
nevertheless,  to  note  instances  in  which 
escape  is  achieved  by  some  clumsy  maneuver 
which  actually  does  release  the  animal. 
Often  such  clumsy  behavior,  having  been 
successful,  is  continued,  despite  its  ineffi- 
ciency. On  the  other  hand,  if  it  is  fati- 
guing or  inconvenient,  it  may  later  be  re- 
placed by  some  more  appropriate  act. 

It  is  not  correct  to  say  that  the  cat  'un- 
derstands' wliy  pressing  the  bar  releases 
him.  Thorndike  found  that  causally  ir- 
relevant acts  can  be  taught  as  the  means 
of  securing  escape  from  the  box,  as  when  he 
taught  cats  to  get  out  of  the  box  by  scratch- 
ing themselves.  Thorndike  released  the 
door  as  soon  as  the  cat  scratched  himself, 
and  befoie  long  the  cat  had  learned  to 
scratch  itself  immediately  to  escape  from 
the  box. 


The  animal's  behavior  sequence  in  the 
problem  box  situation  may  be  analyzed 
into  four  basic  elements:  response,  stimu- 
lus,  motive  and  reward. 

(I)  Response.  This  is  the  center  of  ref- 
erence in  learning  since  the  biological  use 
of  all  learning  is  the  making  of  new  re- 
sponses in  new  situations.     The  response 


FIGURE    50.       PUZZLE    BOX    USED    BY    THORNDIKE    IN 
LEARNING    EXPERIMENTS    WITH    CATS 

[From  H.  E.  Ganett,  deal  experiments  in  piy- 
chology,  Appleton-Century,  1930,  p.  107.] 

may  be  simple  or  it  may  be  a  complex 
sequence.  It  must  be  one  which  the  learner 
is  able  to  perform.  In  Thorndike's  experi- 
inent  pushing  the  lever  was  a  response  the 
cat  could  make.  If  Thorndike  had  required 
the  animal  to  insert  a  key  in  a  lock  to  get 
out,  the  learning  would  not  haAC  occurred 
since  cats  cannot  turn  keys  in  locks. 

(2)  Stimulus.  This  is  the  causal  factor 
which  becomes  associated  with  the  response 
during  learning  and  so  becomes  capable 
of  evoking  the  response.  There  is  initially 
a  multiplicity  of  stimuli  to  whicli  the 
learner  is  responsive,  but  die  range  becomes 
narrowed  with  learning.  In  Thorndike's 
experiment  the  cat  originally  looked  about, 
sniffed    and    explored    a    host    of    stimuli. 


146 


Learning 


With  a  high  degree  of  learning,  however, 
the  cat  singled  out  the  essential  stimulus 
of  the  lever  and  reacted  to  it  alone. 

(3)  Motive.  Although  some  learning  oc- 
curs without  obvious  desire  or  intent  to 
learn,  it  is  true  nevertheless  that  all  learn- 
ing depends  on  the  individual's  motives. 
They  may  be  simple,  like  a  need  for  food 
or  a  need  to  avoid  the  light,  or  they  may 
be  more  complex,  like  a  need  to  gain  self- 
approval,  the  approval  of  others  or  to  avoid 
criticism.  Thorndike  always  used  hungry 
cats.  If  animals  are  satiated  (and  hence 
without  motive),  learning  does  not  occur. 

(4)  Reumvd.  One  generally  learns  those 
responses  which  are  rewarded,  the  responses 
which  lead  to  the  satisfaction  of  motives. 
Often  the  rewards  are  not  obvious,  since 
they  may  consist  of  such  things  as  self- 
approval,  or  the  relief  from  anxiety  or 
worry  associated  with  fear  of  criticism  or 
jnmishment.  If  Thorndike  had  not  al- 
lowed his  cats  to  get  out  of  the  box  and 
cat  the  food  after  making  the  correct  re- 
sponses, if  he  had  not  rewarded  tliem,  they 
never  would  have  learned  how  to  get  out. 

Using  these  terms,  we  can  describe  trial- 
and-error  behavior  in  simplest  form  as  fol- 
lows. 

(1)  The  learner  has  a  inotive  (in  the 
case  of  the  cat,  to  get  out  of  the  box  and 
obtain  food). 

(2)  The  motive  leads  to  varied  types  of 
activity  in  which  the  learner  tries  succes- 
sively various  responses  in  its  behavior 
repertoire,  beginning  with  the  one  which 
is  most  strongly  established  and  then,  suc- 
cessively, responses  which  are  less  and  less 
well  established. 

(3)  Some  of  these  responses  ultimately 
lead  to  a  reivard  which  satisfies  the  motive. 

(4)  The  responses  which  lead  to  the  re- 
ward become  more  strongly  established 
(l)ettcr  learned)  as  a  result  of  tlic  satisfac- 


tion of  the  motive,  being  made  more  and 
more  certainly  on  subsequent  trials  when 
the  same  stimulus  situation  is  present. 

(5)  Responses  not  leading  to  -the  satis- 
faction of  the  motive  tend  to  be  eliminated 
after  repeated  trials. 

Thus  we  see  that  trial-and-error  behavior 
is  regular  and  predictable  in  that  it  de- 
pends upon  the  motives  of  the  leainer  and 
the  responses  in  his  repertory  of  behaviors. 
Such  learning  is  random  only  in  the  sense 
that  the  learner  has  a  problem  to  solve  and 
cannot  solve  it  by  insight  or  foresight.  He 
has  to  test  out  possible  actions  by  random 
behavior  until  he  hits  upon  the  one  that 
brings  success.  Then  success  succeeds.  It 
would  really  be  better  to  speak  of  this  kind 
of  learning  as  Irial-and-surcess,  for  the  er- 
rors retard  learning,  whereas  success  is 
what  establishes  it  finally. 

In  Irinl-nnd-error  learning  we  (ind  again 
all  tlie  characteristics  which  belong  to  as- 
sociative learning.  When  a  subject  has 
learned  by  trial  and  error  a  response  which 
leads  to  a  reward,  the  omission  of  the  re- 
ward results  in  the  gradual  disappearance 
of  the  Yt^pon?,e— extinction.  An  extin- 
guished habit  may,  however,  reappear  after 
the  passage  of  Um&— spontaneous  recovery. 
Situations  similar  to  the  one  in  which  the 
original  learning  took  place  will  also  elicit 
the  newly  learned  behavior  and,  the  more 
similar  the  situation  to  the  original,  the 
greater  the  transfer  of  learning  to  it.  That 
is  generalization.  If,  however,  reward  is 
not  forthcoming  in  the  new  situation,  the 
generalized  response  will  presently  be  ex- 
tinguished, while  the  primary  rewarded 
response  continues.  That  is  differentiation. 
Last,  time  relations  are  as  critical  for  trial- 
and-error  learning  as  for  associative  learn- 
ing. The  shorter  the  interval  between  the 
response  and  the  reward,  tlic  greater  the 
strengtliening  of  llic  responsf. 


The  Law  of  Effect 


147 


The  Law  of  Effect 

The  inijiortanL  principle  whirh  emerges 
Irom  our  discussion  ol  irial-ancl-error  learn- 
ing is  the  importance  of  reward  in  fixating 
learning.  This  result  is  so  universally  ob- 
tained that  it  has  become  a  law  of  learn- 
ing, the  laxv  of  efject.  The  name  stresses 
the  importance  of  the  effect  or  consequence 
of  an  act  on  its  acquisition.  This  law  was 
first  formulated  by  Thorndike  in  terms  of 
the  satisfaction  or  dissatisfaction  which  hal- 
lows ihe  making  of  a  given  response.  He 
said:  "When  a  modifiable  connection  be- 
tween a  situation  and  response  is  made  and 
is  accompanied  or  followed  by  a  satisfy- 
ing state  of  affairs,  that  connection's 
strength  is  increased.  When  made  and  ac- 
companied or  followed  by  an  annoying 
state  of  affairs,  its  strength  is  decreased." 

The  terms  satisfying  state  and  annoying 
slate  were  defined  by  him  as  follows:  "By 
a  satisfying  state  of  affairs  is  meant  one 
Avhich  the  animal  does  nothing  to  avoid, 
often  doing  things  which  maintain  or  re- 
new it.  By  an  annoying  state  of  affairs  is 
meant  one  which  the  animal  does  nothing 
to  preserve,  often  doing  things  which  put 
an  end  to  it." 

Learning  and  'satisfaction'  are  so  closely 
related  that  it  is  difficult  to  measure  satis- 
faction independently  of  learning;  but  that 
difficulty  can  be  avoided  if  we  discover  what 
is  satisfying  or  rewarding  in  one  situation 
and  then  apply  this  knowledge  in  predict- 
ing the  strengthening  of  other  stimulus- 
response  connections.  If  a  certain  kind  of 
food  is  an  efl^ective  reward  for  learning  one 
task,  it  can  be  used  to  induce  the  learning 
of  other  tasks. 

Experiments  have  established  the  gener- 
alization that  the  greater  the  reward,  the 
more  it  facilitates  learning.  This  rule  is 
closely  related  to  what  has  been  called  by 


'WunwiWkv  ihe  law  of  intensity.  Ail  evi- 
dence points  to  the  fact  that  the  greater 
tlie  si/c  of  the  reward,  the  stronger  the  mo- 
tivation; and  the  stronger  the  inotivation, 
tfie  faster  and  surer  the  Icarrn'ng.  (See 
p.  129.) 

As  we  have  already  seen,  the  time  inter- 
\al  between  the  response  and  the  reward 


I   I   I   I   I   M    I    M    I   I   I   I   I   I 


I   I   i   I   I   I   I    I   I   I   I   I   I   I   I   I   I 


20     18     16     14      12     10      8       6       4 
Minutes  of  delay  in  reinforcement 


FIGURE     K 1 


DELAY-OF-REINFORCEMENT    GRADIENT 


The  circles  siiow  the  amount  of  learning  for  con- 
stant numbers  of  reinforcements  plotted  as  a  func- 
tion of  the  delay  in  the  occurrence  of  the  reinforce- 
ment. [From  data  published  by  J.  B.  \VoIfe,  and 
plotted  by  C.  L.  Hidl,  Principles  of  behavior, 
Appleton-Century,  1943,  p.  137.] 

is  an  important  factor  to  consider  in  pic- 
dicting  the  effect  of  reward.  The  strength 
of  learning  is  greater,  the  shorter  the  time 
between  the  response  and  the  reward. 
Thorndike  said:  "The  closeness  of  connec- 
tion between  the  satisfying  state  of  affairs 
and  the  bond  it  affects  may  be  due  to  close 
temporal  sequence.  Other  things  being 
equal,  the  same  degiee  of  satisfvingness  will 
act  more  strongly  on  a  bond  made  two  sec- 
onds previously  than  on  one  made  tv.o 
minutes  previously."  Verification  of  Thorn- 
dike's  principle  is  shown  in  Fig.  51.  Eight 
groups  of  white  rats  learned  to  find  food 
in  a  simple  maze  ^vith  varving  delavs  be- 
tween the  correct  choice  and  the  food.     A 


148 


Learning 


clear  tendency  is  seen  lor  learning  to  be 
most  efficient  when  a  short  time  elapses 
between  the  response  and  the  reward. 

These  results  have  considerable  impor- 
tance in  practical  learning  situations,  par- 
ticularly in  child  training.  Very  often 
too  long  a  period  is  allowed  to  elapse  be- 
tween the  act  which  a  parent  is  attempting 
to  strengthen  or  weaken  and  the  reward 
or  punishment.  If  the  time  is  much  too 
long,  the  reward  or  punishment  may  even 
get  attached  to  the  incorrect  act  merely 
because  it  has  immediately  preceded  the 
reward  or  punishment. 

THE    ROLE    OF    MOTIVATION 
IN    LEARNING 

Now  that  it  is  clear  that  the  concepts  of 
learning  and  motivation   cannot  be  disso- 


I    I    I    I    I    I    M    I    I    I    M    I    I    M 
""  ^^i^ Less  hungry  rewarded 
~  v^-^  >rLess  hungry  nonrewarded- 


I     I     I     I     I     I     I     I     I     II 


0       2        4        6        8        10       12       14       16       18 
Days 

FIGURE    52.       EFFECT    OF    FOOD    REWARD    ON    MAZE 
LEARNING  IN  RATS 

[From  E.  C.  Tolman  and  E.  H.  Honzik,  University 
of  California  Publications  in  Psychology,  1930,  4, 
246.] 

ciated,  let  us  examine  their  relationship  in 
greater  detail. 

As  we  have  seen  in  the  preceding  chapter, 
motives  are  forces  which  impel  to  action, 
and  the  simplest  are  physiological,  like 
thirst,  hunger  and  pain.    They  are  the  mo- 


tives most  frequently  used  in  laboratory 
experiments  on  animal  learning  because 
they  are  most  universal  and  easy  to  con- 
trol. In  human  learning,  however,  much 
more  complex  motives  are  usually  in- 
volved, motives  which  are  derived  from 
the  simple  ones.  Desire  for  prestige,  money, 
approval,  all  such  motives  are  built  upon 
earlier  simpler  ones. 

Rewards  may  be  thought  of  as  e\'euls 
which  satisfy  motives.  Thus  in  Thorn- 
dike's  problem-box  experiment  the  reward 
was  food  which  reduced  the  cat's  hunger 
drive.  When  an  experimenter  controls 
strength  of  motive  by  controlling  amount 
of  reward,  it  is  not  necessary  for  us  to  dis- 
tinguish between  motive  and  reward.  On 
the  other  hand,  motive  and  reward  can  vary 
separately.  The  following  experiment 
shows  the  relationship  between  the  two. 

Rats  were  taught  to  follow  a  complex 
pattern  of  runs  and  turns  through  a  maze 
to  reach  food.  One  group  of  rats  was  not 
hungry  and  was  not  given  any  food  at  the 
end  of  a  trial;  a  second  group  was  hungry 
but  was  not  given  food;  the  third  was 
hungry  and  given  food  at  the  end  of  a  trial. 
The  results  are  shown  in  Fig.  52.  Only 
the  group  that  was  hungry  (had  a  motive) 
and  was  given  food  (was  rewarded)  learned 
appreciably.  To  be  motivated  and  unre- 
warded is  to  have  before  you  nothing 
worth  learning.  Nor  is  it  worth  while  to 
work  for  a  prize  you  do  not  want.  It  is 
the  motive  that  gives  the  reward  its  value, 
and  the  satisfaction  of  reward  that  fixes 
the  learning  of  which  it  is  the  effect. 

Motivation  is  equally  important  in  hu- 
man learning,  but  here  the  motives  are  not 
usually  the  simple  physiological  needs. 
There  is  no  doubt  that  human  beings  learn 
effectively  when  motivated  by  primary 
drives  like  hunger,  thirst  or  pain,  but  these 
drives  are  rarely  intense  in  present-day  life. 


The  Effect  of  Motivation  and  Practice 


149 


The  motives  which  ;ire  involved  are  what 
ai'c  called  learned  or  deriwid  motives.  'I  hat 
is  to  say,  they  liave  been  associated  with 
the  biological  needs  and  now  operate  in 
che  same  way  as  the  original  needs  (pp. 
121  I.).  An  anxious  parent  praises  a 
stubborn  child  every  time  it  takes  a  spoon- 
lul  oi  Icjod.  Eventually  the  child,  even 
though  not  feeling  hungry,  will  eat  merely 
(o  obtain  the  reward  of  its  ])arent's  praise 
or  approval. 

The  way  these  learned  motives  operate 
may  be  illustrated  by  several  experiments. 
In  one,  students  were  instructed  to  add  col- 
umns as  rapidly  and  accurately  as  possible. 
One  group  worked  without  any  particular 
incentive.  In  the  second  group  the  chil- 
dren were  praised  in  front  of  the  class 
for  their  performance,  while  the  members 
of  the  third  group  were  reproved  for  their 
careless  and  inferior  work.  The  perform- 
ance on  successive  days  for  the  three  groups 
is  shown  in  Table  II.     The  control  group 

TABLE  II 

Effect  of  Praise  and  Reproof  on  Learning  Scores 
[Data  from  E.  B.  Hurlock,  /.  ednc.  Psychol.,  1925,  16, 
149.] 

Average  Scores  in  Addition 
Day  1     Day  2     Day  3     Day  4     Day  5 
"Praised"  11.81     16.59     18.85     18.81     20.22 

"Reproved"  11.85     16.59     14.30     13.26     14.19 

"Ignored"  11.84     14.19     13.30     12.92     12.38 

Control  11.81     12.34     11.65     10.50     11.35 

shows  no  consistent  gain  from  practice. 
The  reproved  group  shows  an  initial  im- 
provement, but  the  improvement  is  not 
maintained.  The  most  effective  incentive 
is  shown  here  to  be  praise,  which  results 
in  consistent  improvement. 

Rivalry  or  competition  is  another  motive 
which  has  long  been  effectively  used  in 
learning,  particularly  in  school  situations. 
The  competition  can  be  either  between 
individuals  or  between  groups.    A  study  in 


which  these  two  types  of  competition  were 
compatc.-d    is   pres(-ntcd    in     i  able    III.      In 

TABLE  ill 

PREFECT    OF    Individual    and    Groi.p    Rivai.rv    o.s 

Variou.s  Ta.sk.s 
[After  V.  M.  Sims,  /.  educ.  Psychol.,  1928, 19,  481,  483.) 

Per  Cent 

Gain  in  Per  Cent 

Substitution  dain  in 

Task  Reading 

Group  rivalry                    109.9  14.5 

Individual  rivalry            157.7  34.7 

Control:  No  rivalry         102.2  8.7 

the  first  experiment  one  group  competed 
against  another  in  a  substitution  test;  in 
the  second  matched  pairs  of  children  com- 
peted with  each  other  in  reading.  The 
latter  condition  was  found  to  be  the  more 
effective. 


THE    EFFECT    OF    PRACTI CE 

In  learning  anything  of  e\en  moderate 
complexity,  several  repetitions  are  re- 
quired. It  is  impossible  to  master  a  com- 
plex or  elaborate  task  in  a  single  try,  no 
matter  what  the  degi^ee  of  motivation  or 
what  the  value  of  the  reward.  You  could 
not  learn  the  Constitution  of  the  United 
States  in  one  reading,  even  though  your 
life  depended  on  it,  e\en  though  the  prize 
were  a  million  dollars.  A  great  deal  of  re- 
search has,  therefore,  been  done  on  the 
effect  of  repetition  on  learning,  that  is  to 
say,  on  practice. 

The  clearest  way  to  bring  out  the  effect 
of  practice  is  to  graph  leaining  on  succes- 
sive trials.  Learning  may  be  measured  in 
a  number  of  Avays.  One  A\ay  Avith  A\hich 
w'e  are  all  familiar  is  in  terms  of  tlie  speed 
Avith  which  we  can  do  a  task.  In  learning 
to  type,  for  example,  at  first  we  can  do  only 
a  few  words  per  minute  but  witli  practice 


150 


Learning 


greater  and  greater  speed  is  attained.  Speed 
may  be  measured  in  terms  of  how  much 
work  is  done  in  a  given  time  or  how  rap- 
idly a  single  task  is  performed.  A  second 
way  in  which  improxement  is  shown  is  in 
accuracy.  In  the  typing  there  is  a  reduc- 
tion in  the  number  of  errors  as  practice 
continues.  More  difficuk  to  measure  but 
very  important  is  reduction  in  cffoit,  the 


1    2    3    4    5    6    7    8    9   10  11  12 
Presentations  of  list 

FIGURE    53.       MEMORIZATION     CURVE    FOR    LIST    OF 
NONSENSE   SYLLABLES 

I. earning  is  shown  by  the  increase  in  the  number 
of  syllables  that  are  anticipated  in  the  tests  for  re- 
cill.      This  cmve  is  for  one  subject. 

energy  cost  in  performing  a  task.  .\t  first, 
a  task  is  difficuk  and  fatiguing,  but  with 
further  practice  it  becomes  smoother  and 
requires  less  effort. 

A  typical  record  showing  improvement 
with  practice  is  given  in  Fig.  .53.  Here 
is  shown  the  number  of  syllables  in  a  list 
of  ten  which  a  subject  was  able  to  recite 
correctly  after  twelve  successive  repetitions. 
The  curve  shows  an  upward  course  of  im- 
provement, but  with  marked  up-and-down 
fluctuations.  Such  yariations  are  charac- 
teristic of  all  individual  learning  curves 
and  are  the  result  of  chance  conditions 
which  the  experimenter  has  not  controlled, 
such  factors  as  distraction  and  fluctuation 
of  motivation. 


W^hen  the  curves  of  a  number  of  indi- 
\iduals  who  learned  the  same  material  are 
averaged,  we  can  see  the  course  of  impro\e- 
ment  more  clearly.  We  find,  however, 
that  there  is  no  single  type  of  learning 
curve  biu  that  the  type  depends  upon  the 
nature  of  the  task  and  the  conditions  lui- 
der  which  the  learning  is  done.  The  three 
most  common  types  are  shown  in  Fig.  .54. 
The  first  type  (A)  is  the  one  in  which  ini- 
])rovement  is  rapid  at  first  biu  then  pro- 
gressively slower  toward  the  end.  It  is 
called  a  negatively  accelerated  learning 
curve.  It  is  the  type  most  often  obtained 
when  motivation  is  high  at  first  but  de- 
creases as  practice  continues,  or  when  the 
subject  has  had  previous  practice  on  a  simi- 
lar task  so  that  the  learning  is  not  really 
'from  scratch.' 

The  second  type  (B)  is  called  a  positively 
accelerated  curve.  Here  the  increments 
are  relatively  sinall  during  the  early  part  of 
practice   but    increase   in    magnitude   with 


FIGURE    54.       REPRESENTAT1\E    LEARNING    CURVES 

[Cur\es  A  and  li  are  from  H.  A.  Carr,  Psychology: 
a  sliidy  of  mental  actii'itv.  1925.  p.  21S;  rejjrinted 
by  permission  of  Longmans,  Green.] 

continued  practice.  Curves  cannot,  of 
course,  be  positively  accelerated  through- 
out, since,  at  the  end,  as  perfect  learning 
is  approached,  they  necessarily  level  off. 

In  the  third  type  of  curve  there  is  an  ini- 
tial period  of  positive  acceleration  followed 
by  negative  acceleration.  In  this  case,  the 
total  curve  is  S-shaped  (type  C).  All  ini- 
tially positively  accelerated  learning  curves, 
if  canied  through  to  the  leveling-off  stage, 
become  S-shajjed. 


Practice 


151 


Curves  of  types  B  and  C  arc  most  often 
obtained  when  the  subject  has  had  very 
little  prior  practice,  particuhirly  when  the 
acts  learned  are  relatively  difficult  for  the 
learner.  The  manner  in  which  the  diffi- 
culty of  the   material   affects   the   type   of 


FIGURK  55.       MEMORIZAllON    CURVKS   !•  OR  KASV   ANIl 
HARD  ITEMS 

[From  J.  A.  McGeoch,  The  psychology  of  liiunan 
learning,  Longmans,  Green,  1942,  p.  56.1 

learning  curve  obtained  is  shown  in  Fig. 
55.  With  the  easy  material  a  negatively 
accelerated  learning  curve  is  obtained;  with 
hard  items  a  positively  accelerated  learning 
curve  is  found. 

Wherever  the  entire  learning  of  a  task 
from  zero  performance  to  mastery  is  stud- 
ied, the  third  type  of  curve  (S-shaped)  is 
most  likely  to  be  obtained.  With  difficult 
material  we  are  more  likely  to  be  starting- 
near  'scratch'  with  initial  positive  accelera- 
tion, whereas  with  easy  material  we  are 
more  likely  to  be  beginning  further  along 


toward  mastery,  where  negative  accelera- 
tion is  obtained.  As  learning  progresses, 
what  began  as  hard  is  becoming  easier,  and 
acceleration  may  therefore  change  from 
positive  to  negative— the  S-curve. 

Plateaus 

Sometimes  there  occurs  in  learning  a 
long  period  of  practice  in  which  no  im- 
jjrovement  is  apparent,  where  the  trend  for 
a  period  of  time  is  toward  a  relatively  con- 
stant level  of  performance.  Periods  of  this 
sort  in  which  no  improvement  takes  place 
are  called  plateaus.  This  phenomenon  was 
first  noticed  in  certain  experiments  on  the 
learning  of  telegraphy  (Fig.  56).  In  the 
the  curve  for  receiving  telegraphic  signals 
there  is  a  period  of  arrested  progiess  in  tlu- 
iiiidposition  of  the  graph.     The  hypothesis 


0      4       8      12     16     20     24     28     32     36     40 
Weeks  of  practice 

FIGURE  56.      PLATEAU    IN   A  LEARNING   CURVE 

Curve  for  one  subject's  learning  to  receive  in  the 
telegraphic  language.  "This  is  a  curve  of  sample 
performance.  I'he  region  of  very  little  or  no  prog- 
ress toward  the  middle  of  the  curve  is  a  plateau." 
[From  W.  L.  Bryan  and  N.  Harter,  Psychol.  Re-,:. 
1897,  4,  49.] 

formulated  by  the  experimenters  for  this 
result  was  that  plateaus  occur  in  the  re- 
gion of  transition  from  one  tvpe  of  habit 
to  another.  In  the  early  stages,  diev 
thought,  learning  is  by  letters.  Later  it 
would   proceed    by   words,    and    then    still 


152 


Learning 


later  by  phrases,  and  thus  on  to  the  largest 
units  which  a  skilled  telegrapher  can  re- 
ceive as  a  whole.  They  thought  that  the 
change-over  from  one  type  of  learning  to 
the  next  introduced  a  plateau,  and  indeed 
that  may  sometimes  be  true  when  plateaus 
occur.  Learning  telegraphy  does  not,  how- 
ever, usually  go  by  jumps,  nor  do  its  learn- 
ing curves  always  show  plateaus.  Cer- 
tainly other  factors  enter  into  the  produc- 
tion of  plateaus.  Any  long-drawn-out  S- 
curve  would  be  said  to  have  a  plateau  in 
the  middle  of  it.  Sometimes  plateaus  are 
caused  by  loss  of  interest  and  motivation, 
by  discouragement  with  the  slow  progress 
which  the  difficult  nature  of  the  task  makes 
necessaiy.  The  important  thing  for  a 
learner  to  remember  is  that  plateaus  are 
natural  phenomena  in  learning,  can  be 
overcome  and  do  not  last  forever.  If  the 
learner  allows  a  plateau  to  discourage  him, 
the  plateau  by  reducing  his  motivation  will 
prolong  itself. 

Insight 

A  curve  strikingly  different  from  the 
ones  we  have  been  considering  is  sometimes 
found  when  the  fully  learned  response 
makes  its  appearance  suddenly,  as  is  the 
case  when  a  problem  is  solved  by  the  grasp 
of  a  single  general  principle  or  method. 
This  type  of  learning  is  called  learning  by 
i}jsight.  In  a  famous  experiment  with 
chimpanzees  one  of  the  animals,  which  had 
already  learned  to  pull  a  banana  through 
a  fence  by  using  a  stick,  was  given  two 
sticks,  each  one  alone  too  short  to  reach 
the  banana.  The  two  sticks,  however,  were 
constructed  in  such  a  way  that  the  end  of 
one  would  fit  into  the  other.  Playing  with 
the  two  sticks  in  another  part  of  his  cage, 
the  chimpanzee  casually  fitted  the  two  to- 
gether and  then,  suddenly  realizing  that 
he  had  now  a  long  stick,  rushed  to  the  other 


side  of  the  cage  and  raked  in  the  banana. 
This  'seeing'  that  the  two  together  made 
a  stick  long  enough  to  get  the  banana  is  an 
instance  of  insight.  The  learning,  more- 
over, stuck.  Thereafter  the  chimpanzee 
always  knew  how  to  use  the  two  sticks  to- 
gether.    (See  Fig.  73,  p.' 203.) 

Physiological  Limits 

A  consideration  of  learning  cmves  leads 
directly  to  the  question  whether— or  how 
rapidly— learners  reach  a  physiological 
limit,  the  level  of  performance  beyond 
which,  by  reason  of  the  physical  limita- 
tions of  their  organisms,  they  cannot  go. 
Since  under  ordinary  laboratory  conditions 
subjects  seldom  approach  such  an  extreme 
limit  of  performance,  one  must  rely  for  an 
answer  to  this  question  upon  fragmentary 
evidence. 

It  has  been  found  that  years  of  practice 
at  such  skills  as  telegraphy  or  typesetting 
do  not  commonly  bring  a  man  to  his  maxi- 
mal performance.  Even  among  workers 
with  many  years  of  experience,  the  intro- 
duction of  special  incentives  may  greatly 
improve  performance.  In  a  printing  house, 
for  example,  where  hand  compositors  had 
been  working  at  their  trade  for  an  a^■erage 
of  about  ten  years,  performance  rose  stead- 
ily for  at  least  twenty  weeks  when  a  special 
bonus  was  introduced  for  output  beyond  a 
certain  level.  The  increased  output  re- 
sidted  from  elimination  of  stabilized  inef- 
fecti\e  habits  of  work  and  the  acquisition 
of  better  ones.  Analogous  results  have 
been  obtained  with  other  kinds  of  work. 

The  fact  that  in  athletics  and  in  other 
skills  records  are  repeatedly  broken  under 
standard  conditions  is  best  interpreted  as 
an  indication  of  the  practical  remoteness 
of  a  physiological  limit.  It  has,  likewise, 
been  found  repeatedly  in  the  laboratory 
that,    after   a   subject   has   reached    a   rela- 


Insight  and  Frequency 


153 


lively  high  level  of  performance,  increased 
motivation  or  better  methods  will  produce 
further  substantial  increments.  It  thus  ap- 
pears that  a  physiological  limit  is  not 
reached  in  normal  persons  by  ordinary 
amounts  of  practice  and,  indeed,  may  not 
be  reached  even  by  prolonged  practice  un- 
der favorable  conditions.  On  the  other 
hand,  there  are  physiological  limits  to  the 
speed  of  human  reaction  which  no  degree 
of  practice,  insight  or  motivation  will  en- 
able the  learner  to  transcend. 

The  Law  of  Frequency 

The  results  which  have  been  presented 
above  clearly  indicate  that  repetition  is 
usually  required  for  mastery  in  learning. 
This  fact  has  led  to  the  belief  that  fre- 
quency is  the  basic  determiner  of  learning, 
a  generalization  often  called  the  laiu  of  fre- 
quency. The  law  of  frequency  (or  law  of 
exercise)  states  that  the  connection  between 
a  stimulus  and  a  response  is  strengthened 
by  its  recurrence,  its  exercise,  its  use. 

Experiments  have  conclusively  demon- 
strated that  mere  repetition  is  itself  not  a 
sufficient  condition  for  learning.  If  we  set 
a  man  the  task  of  hitting  the  bull's-eye 
with  a  rifle  but  do  not  tell  him  how  close 
to  the  bull's-eye  he  comes,  no  amount  of 
repetition  results  in  his  learning  to  shoot 
straight.  Similarly,  if  a  learner  is  not  try- 
ing to  learn,  repetition  becomes  ineffective. 
This  fact  has  been  demonstrated  in  one 
study  by  presenting  students  with  a  series 
of  cards,  each  bearing  a  printed  word,  a 
number  and  a  strip  of  colored  paper.  The 
subjects  were  instructed  to  learn  the  word- 
number  pairs,  so  that,  when  the  word  was 
given,  the  accompanying  number  could  be 
recited.  No  mention  was  made  of  the  colors 
accompanying  the  words.  After  several 
presentations  the  subjects  were  asked  to 
name  the  color  that  went  with  the  given 


word.  Few  of  them  had  learned  any  of  the 
colors.  They  knew  the  numbers,  but  not 
the  colors,  although  they  had  seen  the 
colors  with  the  words  as  often  as  the  num- 
bers. In  the  same  way  a  man  can  be  driven 
frec]ucntly  over  a  route  without  learning 
how  to  go.  The  best  way  for  him  to  learn 
is  to  drive  the  car  himself;  then  he  will 
remember. 

The  motive  to  learn  is  tied  up  with  good 
attention.  People  can  remember  events 
when  they  have  paid  good  attention  to 
them  without  intending  to  learn  them  or 
expecting  to  have  to  report  on  them.  The 
witness  of  an  accident  will  recall  certain 
details.  Such  learning  is  called  incidental 
learning  and  is  not  very  reliable.  Although 
the  man  who  stumbles  in  the  dark  over 
what  turns  out  to  be  a  corpse  will  not  at 
once  forget  what  it  was  he  found  so  unex- 
pectedly, it  is  difficult  on  the  witness  stand 
to  get  an  accurate  report  of  the  details  of 
such  an  important,  exciting  event.  If  you 
witness  an  accident  or  a  crime,  you  had 
better  invoke  the  intent  to  learn  at  once. 
Commit  to  memory  what  seem  to  be  the 
important  factual  items  Avhich  you  ob- 
sei-ved,  and  then  write  them  down  later 
so  that  you  can  go  to  court  and  be  a  good 
witness. 

There  are  certain  schools  of  psycholog^ 
today  which  believe  that  all  learning  is 
basically  instantaneous,  like  the  flash  of 
insight  which  gives  the  solution  to  the  prob- 
lem and  once  seen  is  not  forgotten,  or  like 
the  emotional  experience  (the  corpse  in  the 
dark)  which  leads  to  instant  pennanent 
learning  of  a  simple  interesting  fact.  These 
psychologists  argue  that  repetition  is  neces- 
sary only  because  tasks  are  too  large  to 
come  all  at  once  widiin  reach  of  the  con- 
ditions for  learning.  You  learn  most  on  the 
first  experience.  If  you  learn  a  third  of 
the    material    the    first    time,    perhaps   -vou 


154 


Learning 


can  learn  a  third  of  the  remaining  two- 
thirds  the  second  time,  and  so  on.  Fre- 
tjuency  is  necessary,  they  argue,  merely  in 
order  that  all  portions  of  the  learning 
should  eventually  get  their  full  oppor- 
tunity to  be  realized. 

Certainly  the  repetition  of  practice  is 
necessary  to  most  learning,  even  though 
there  is  this  doubt  that  the  same  associa- 
tive connections  need  repeated  reinforce- 
ment before  they  become  fixed  for  the  use 
of  the  learned  man. 

OTHER    FACTORS    AFFECTING 

THE    EFFICIENCY    OF 

LEARNING 

We  have  seen  how  learning  is  affected 
by  practice  and  by  motivation.  In  this 
section  we  shall  discuss  some  of  the  more 
specific  factors  affecting  the  speed  and  effi- 
ciency with  which  learning  takes  place,  con- 
sidering successively  the  importance  of  (1) 
the  learner,  (2)  the  material  learned  and 
(,S)  the  methods  of  learning  used. 

The  Learner 

Great  individual  differences  between 
people  learning  the  same  task  are  invari- 
ably found.     The  influence  of  such  factors 


0        10       20       30       40       50       60       70       80 


FIGURE  57.      DEPENDENCE  OF  LEARNING  ABILITY  ON 
AGE 

The  trend  of  mean  performance  in  digit-symbol 
suljstitution  with  age.  (See  Figs.  37  and  38,  p.  85.) 
[From  R.  R.  Willoughby,  /.  educ.  Psychol.,  1929. 
20,  678;  rcprinle<l  by  periiiission  f)f  ^Var^^■ick  and 
\r,rk.] 


as  age,  intelligence  and  previous  training 
have  been  studied,  but  even  when  all  are 
controlled  pronounced  variation  still  ex- 
ists. In  one  study  made  with  subjects  of 
the  same  age,  sex,  year  in  college  and 
equivalent  previous  practice  at  the  activity 
being  learned,  the  fastest  learners  required 
8  trials  to  learn,  perfectly  and  in  the  same 
order,  a  list  of  8  nonsense  syllables,  whereas 
the  slowest  learners  required  37  trials, 
more  than  four  times  as  many.  Simi- 
larly, the  fastest  learner  mastered  a  maze  of 
considerable  difficulty  in  19  trials,  whereas 
the  slowest  took  78.  When  the  records  of 
a  large  group  of  subjects  are  examined, 
they  are  found  to  be  distributed  after  the 
fashion  of  many  large  populations,  with 
medium  speed  most  frequent  and  the  fre- 
quency of  instances  diminishing  for  slower 
and  faster  learning. 

Differences  between  the  sexes  in  speed  of 
learning  are  only  rarely  found,  and  then 
they  are  due  to  sex  differences  in  interest 
and  motivation  with  respect  to  the  mate- 
rial being  learned. 

A  variable  affecting  learning,  one  which 
has  great  practical  importance,  is  age.  The 
curve  of  learning  improves  as  one  grows 
older,  at  least  until  the  late  teens.  After 
the  early  twenties  a  gradual  decline  with 
increasing  age  is  found.  A  sample  of  per- 
formance in  a  simple  learning  task  at  vari- 
ous ages  is  shown  in  Fig.  57. 

An  interesting  experiment  on  the  effect 
of  age  on  learning  is  the  following.  Three 
groups  were  studied.  The  young  group  was 
12  to  17  years  of  age;  the  middle  group 
34  to  59;  the  oldest  group  60  to  82  years. 
The  three  groups  were  comparable  in  so- 
cial background,  native  ability  and  will- 
ingness to  cooperate  in  the  experiment. 
The  five  different  tasks  learned  by  the  sub- 
jects were  chosen  to  represent  different  de- 
grees of  dependence  ujwn  previous  habits. 


Intelligence,  Sex,  Age  and  Material 


155 


The  investigator  found  only  moderate  de- 
cline with  age  in  the  tasks  which  involved 
the  perfecting  of  previously  learned  habits, 
but  extremely  marked  decline  with  age 
when  the  new  learning  was  in  conliict  with 
previously  learned  coordinations,  as  in  a 
task  like  learning  false  multiplication 
tables,  2X4  =  9,  5x4=14. 

These  results  suggest  a  reason  for  the 
greater  conservatism  of  older  individuals. 
Being  less  able  to  learn  new  materials, 
particularly  of  the  type  involving  tearing 
down  old  habits  of  response,  they  are  lim- 
ited in  their  thinking  to  experiences  ac- 
quired in  the  past.  The  further  a  proposed 
change  deviates  from  their  past  experience, 
the  liarder  it  is  for  them  to  learn  the  new 
relationships  and  implications  which  they 
must  substitute  for  old  knowledge  if  they 
are  to  appreciate  the  need  for  change. 

Kind  of  Material 

We  are  all  aware  that  some  kinds  of  ma- 
terial are  much  easier  to  learn  than  others. 
What  accounts  for  the  difference  in  ease  of 
learning? 

Probably  the  most  important  factor  is 
the  7neaningf Illness  of  the  material  to  be 
learned.  It  is  possible  to  rank  a  large  num- 
ber of  verbal  materials  from  low  to  high 
with  respect  to  their  meaningfulness.  On 
such  a  scale,  nonsense  syllables  (artificial 
syllables  like  ROP,  BAV,  GEX;  see  p.  161) 
are  placed  well  toward  the  lower  end,  single 
wortfs  are  higher,  poetry  and  prose  are  still 
higher.  An  almost  perfect  relationship  is 
found  between  meaningfulness  and  ease  of 
learning,  so  that  it  may  be  said  that,  over 
a  wide  range  of  materials,  rate  of  learning 
is  a  direct  function  of  the  meaningfulness 
of  the  material,  provided  everything  else 
remains  constant.  The  results  of  an  illus- 
trative research  on  this  point  are  given  in 
Table  IV. 


TABLK  IV 

ErrECT   OF   Meaningfulness   in   Learning    Equal 
Number  of  Units  of  Different  .Materials 
[After  Lyon,  /.  educ.  Psycho/.,  1914,  5,  85-91.) 

Minulei  Required Jr/r 
Material  Learning  200  Units 

Nonsense  syllables  93 

Digits  85 

Words  (prose)  24 

Words  (poetry)  10 

A  closely  related  factor  is  the  one  which 
Thorndike  has  called  belongingness.  He 
demonstrated  this  principle  in  an  experi- 
ment in  which  he  read  a  series  of  twenty- 
four  unrelated  sentences  several  times  to  a 
group  of  students.  The  students  were  then 
asked  to  name  the  word  that  had  followed 
the  word  now  read  by  the  experimenter. 
In  42  per  cent  of  the  cases  the  students 
were  able  to  give  the  second  word  of  a  sen- 
tence when  the  first  was  read,  but  in  less 
than  1  per  cent  were  they  able  to  give  the 
first  word  of  the  following  sentence  when 
the  last  word  of  the  preceding  sentence  Iiad 
been  read.  The  difference  was  attributed 
to  the  fact  that  words  in  a  sentence  'belong' 
together  in  a  way  that  the  words  in  dif- 
ferent sentences  do  not. 

Another  way  in  which  the  importance 
of  relationship  as  belongingness  can  be 
demonstrated  is  in  the  learning  of  pairs  of 
words.  If  we  make  up  pairs  like  table- 
chair,  green-grass,  they  \vill  be  learned  much 
more  rapidly  than  combinations  like  book- 
dog,  candle-rose.  In  the  first  type  of  pair 
the  relationship  is  familiar  and  meaning- 
ful with  a  high  degree  of  belongingness.  In 
the  latter  type  of  pair  die  words  are  unre- 
lated and  more  difficult  to  associate. 

It  seems  probable  tliat  both  meaningful- 
ness and  belongingness  help  leai-ning  be- 
cause they  indicate  pre^ious  familiarit\ 
with  the  terms  or   their  relations  or  both 


156 


Learning 


and  are  seen  thus  to  depend  on  the  fact 
that  a  certain  amount  of  learning  has  al- 
ready taken  place. 

Closely  related  to  the  factor  of  meaning- 
fulness  is  the  type  of  learning  activity  re- 
quired for  mastery.  It  is  well  known  that 
it  is  a  great  deal  easier  to  learn  the  ideas 
in  a  passage  than  the  exact  phrasing  used. 
The  former  is  often  called  logical  learning 
and  the  latter  verbatim.  In  a  recent  ex- 
periment it  was  shown  that  logical  learning 
can  be  three  times  as  rapid  as  verbatim 
learning.  It  is  further  significant  that  tell- 
ing the  subject  to  try  to  find  meaningful 
relations  in  the  material  speeds  up  his 
learning.  And  there  are  also  the  ingenious 
learners  who  perpetually  see  meaning  in 
nonsense,  who  perceive  at  once  a  belong- 
ingness  between  WED  and  NAG  in  a  list 
of  words  to  be  learned,  who  remember  the 
sequence  BOS-BEN  because  of  Boston 
(baked)  beans  and  who,  because  of  their 
skill  at  punning  meaningful  insights,  al- 
ways rank  high  in  learning  nonsensical 
stuff. 

Distribution  of  Practice 

Given  a  particular  material  how  is  it 
most  efficient  for  an  individual  to  proceed 
in  learning  it?  Should  he  try  to  learn  the 
material  in  a  single  sitting  or  distribute 
his  practice  over  a  period  of  time,  learn  it 
in  large  units  or  small?  Research  has  given 
the  answers  to  many  of  these  questions. 

When  a  period  of  time  separates  each 
trial  in  learning,  the  method  is  called 
distributed  practice.  When  trials  are  given 
without  a  break,  the  method  is  called 
massed  practice.  Results  indicate  that  for 
almost  all  situations  some  form  of  distrib- 
uted practice  is  more  effective  than  massed. 
A  sample  study  is  shown  in  Fig.  58,  where 
rate  of  learning  nonsense  syllables  contin- 
uously without  a  break  is  compared  with 
the  rate  when  a  short  rest  interval  of  two 


minutes  was  introduced  between  successive 
trials.  We  see  a  marked  difference  favor- 
ing distributed  practice.  This  statement 
refers,  of  course,  to  comparisons  of  amounts 
of  time  actually  spent  in  practice.  Total 
elapsed  time  will  almost  always  be  greater 
under  distribution  because  the  time  for  the 
rest  periods  has  to  be  added.     As  a  conse- 


4         6         8         10        12       14 
Number  of  trials  required 

FIGURE  58.      MASSED  VS.  DISTRIBUTED  PRACTICE 

Cur\es  show  a\erage  number  of  trials  to  reach 
successive  levels  of  performance  by  massed  and  dis- 
tributed practice.  For  example,  it  takes  only  about 
11  trials  to  get  all  12  syllables  correct  by  distributed 
practice,  but  nearly  15  by  massed  practice.  [From 
C.  I.  Hovland,  /.  exper.  psychol.,  1938,  23,  176.] 

quence  it  is  sometimes  necessary  to  use 
massed  practice  under  high  presstire  for  time 
despite  its  relative  inefficiency. 

The  length  of  the  time  interval  between 
trials  is  a  critical  factor  in  the  relative 
effectiveness  of  massed  and  distributed 
practice.  If  the  time  is  very  short  or  of 
zero  duration,  leaining  is  likely  to  suffer 
because  of  reduced  motivation,  interference 
and  fatigue.  If,  on  the  other  hand,  the 
interval  is  too  long,  considerable  forgetting 
will  occur  between  trials,  and  hence  the 
efficiency  of  learning  will  be  reduced.  In 
practice,  however,  because  we  are  more 
likely  to  err  in  the  direction  of  too  much 
massing   than   in    too   wide   separation   of 


Distribufed  Practice:  Wholes  versus  Parts 


157 


trials,  the  admonition  to  distribute  learn- 
ing trials  is  usually  correct. 

For  many  activities  a  variation  in  the 
length  of  the  interval  between  trials  as 
learning  progresses  is  beneficial.  For  cer- 
tain activities  massing  in  the.  early  stages 
of  learning,  with  distribtited  practice  later, 
is  best.  For  others  the  pattern  of  distrib- 
uted practice  at  first,  followed  by  shorter 
and  shorter  intervals  between  trials,  is 
optimal. 

The  advantages  of  distribution  of  prac- 
tice are  greater  when  the  learning  is  less 
meaningful  and  rote  in  character.  Mate- 
rial high  in  meaningfulness  benefits  less 
from  spaced  practice.  This  difference  is 
probably  at  least  partly  due  to  the  greater 
ease  in  maintaining  a  high  degree  of  inter- 
est in  material  that  is  meaningful  or  in 
which  the  learner  sees  significance. 

A  number  of  studies  have  indicated  that 
the  longer  and  more  difficult  the  task,  the 
more  effective  is  distributed  practice.  In 
Fig.  59  results  are  reported  showing  that 
the  longer  the  list  of  syllables  learned,  the 
greater  the  advantage  brought  about  by 
distribution  of  practice. 

Several  factors  appear  to  be  involved  in 
the  explanation  of  the  superiority  of  dis- 
tributed over  massed  practice.  An  im- 
portant one  is  fatigue.  In  certain  learn- 
ing tasks  continuous  practice  produces 
fatigue;  then  rest  periods  between  trials 
benefit  the  learning.  But  in  many  situa- 
tions we  obtain  the  favorable  results  of  dis- 
tribution without  fatigue's  being  a  likely 
factor.  In  these  cases  we  often  find  evi- 
dence of  the  formation  of  conflicting  con- 
nections which  adversely  affect  further 
learning.  These  conflicts  appear  to  sub- 
side quite  rapidly  during  a  rest  period,  so 
that  the  positive  effects  of  repetition  can 
presently  become  more  apparent.  Moti- 
vation is  also  an  important  factor  to  con- 
sider in  the  effectiveness  of  spaced  practice. 


Prolonged  practice  often  results  in  reduced 
interest  in  the  task,  so  that  the  learner  does 
not  work  so  eflectively.  Following  a  rest 
pause  the  learner  may  return  to  his  task 
with  increased  vigor  and  interest. 


1216     24      32  48 

Number  of  syllables  In  list 

FIGURE   59.       MASSED   VS.    DISTRIBUTED   PR.\CTICE    IN 
RELATION   TO    LENGTH   OF    LIST   LEARNED 

Mean  number  of  minutes  required  for  learning 
by  massed  and  distributed  practice  with  varving 
lengths  of  lists  of  nonsense  syllables.  It  is  especially 
important  to  distribute  practice  with  long  lists. 
[Data  from  D.  L.  Lyon,  The  relation  of  length  of 
material  to  time  taken  for  learning,  and  the  opti- 
mum distribution  of  time.  /.  ediic.  psycho!.,  1914, 
V,  1-9;  85-91;  155-163,  published  by  Wandck  S: 
York,  Inc.  Summarized  by  C.  L.  Hull,  Massed  vs. 
distributed  practice,  from  Mathematico-deductive 
theory  of  rote  learning,  Yale  University  Press,  1940, 
p.  131.] 

Whole  or  Part  Learning 

In  attacking  a  learning  problem  is  it 
better  to  try  to  learn  it  by  going  all  the 
way  through  it  on  each  trial  or  by  breaking 
it  into  small  portions  and  learning  each 
in  turn?  The  former  is  usually  called  the 
xvhole  metJiod  and  die  latter  the  part 
method. 

The  majority  of  sttidies  have  found  it  to 
be  more  efficient  to  learn  by  tlie  whole 
method  than  by  the  part,  but,  as  in  tlie  case 


158 


Learning 


of  distributed  practice,  the  relative  effi- 
ciency is  to  a  large  extent  a  function  of  the 
special  conditions  of  learning.  Some  of  the 
factors  affecting  the  relative  effectiveness 
of  the  two  procedmes  are  these. 

(1)  The  age  of  tlie  subjects.  Children 
tend  to  learn  faster  with  the  part  method, 
adults  with  the  whole  method. 

(2)  The  ability  of  the  learner.  Brighter 
children  tend  to  learn  better  with  the  whole 
method,  less  bright  ones  with  the  part 
method. 

(3)  The  stage  of  practice.  At  first  bet- 
ter results  are  obtained  with  the  part 
method,  but  later  on,  after  practice,  the 
Avhole  method  usually  proves  to  be  more 
effective. 

(4)  The  length  of  the  material  to  be 
learned.  If  the  assignment  is  of  moderate 
size  the  whole  method  has  been  foimd  supe- 
rior, but  if  it  is  lengthy  the  part  method  is 
superior. 

These  apparently  conflicting  results  can 
perhaps  all  be  placed  under  one  generaliza- 
tion: Learn  imits  as  large  in  size  as  can  be 
grasped  at  one  time.  If  material  is  diffi- 
cult in  relation  to  the  learner's  ability, 
smaller  units  will  have  to  be  employed,  but 
they  should  still  be  as  large  wholes  as  the 
learner  can  manage  efficiently. 

Verbalization 

Often  in  the  acquisition  of  a  complex 
motor  task  learning  is  facilitated  by  re- 
ducing it  to  a  verbal  formula.  It  has  been 
observed,  for  example,  that  this  is  what 
many  adults  do  in  learning  the  route 
through  a  maze.  They  repeat  to  them- 
selves: "One  to  the  right,  then  two  to  the 
left,  and  then  one  right  again,"  and  so  on. 

The  importance  of  verbalization  in  the 
learning  of  skills  is  supported  by  a  recent 
experiment  in  the  learning  of  mechanical 
puzzles.     The  task  was  the  assembly  of  a 


mechanical  puzzle.  With  one  group  of 
children  the  teacher  demonstrated  the 
puzzle  silently,  but  the  child  was  required  to 
engage  in  counting,  an  activity  calculated 
to  interfere  with  the  child's  inner  verbali- 
zation of  the  steps  in  solving  the  puzzle. 
In  a  second  group  the  teacher  assembled 
the  puzzle  silently  while  the  child  was  in- 
structed to  describe  the  procedure  used  by 
the  teacher.  In  two  other  groups  the 
teacher  described  the  procedure  of  assem- 
bly while  the  child  watched  silently.  In 
still  another  gioup  the  teacher  coiTected 
the  child's  verbal  formulation  of  the  pro- 
cedure, and  in  the  final  group  the  same  pro- 
cedure was  followed  except  that  the  process 
of  describing  the  assembly  was  facilitated 
by  having  numbers  pasted  on  the  parts  in 
the  order  of  assembly.  The  six  groups  can 
be  seen  thus  to  differ  in  the  degree  to  which 
the  child  was  aided  in  verbalizing  the  pro- 
cedure for  assembly.  It  was  found  that  the 
greater  the  verbalization,  the  more  rapid 
the  learning.  The  results  are  shown  in 
Table  V. 

Data  from  another  study  of  this  type  are 
given  in  Table  VI.  Subjects  who  had 
learned  the  correct  path  through  a  maze 
were  asked  to  describe  their  modes  of  at- 
tack and  the  subjective  means  which  they 
used  in  learning.  The  means  reported  fall 
into  three  categories.  (1)  In  verbal  meth- 
ods the  turns  and  other  moves  are  remem- 
bered in  words,  so  that  the  subject  guides 
himself  through  the  maze  by  saying,  "First 
turn  to  the  right,  then  straight  ahead,"  etc. 
(2)  In  motor  methods  the  sensory  cues 
employed  are  predominantly  the  feelings 
of  movement;  the  subject  'follows  the 
lead  of  his  hand'  without  consciously  or- 
ganizing his  movements.  (3)  In  visual 
methods  attempts  are  made  to  construct 
visual  images  of  the  maze  pattern.  The 
frequencies  with  which  the  three  methods 


Verbalization  and  Active  Participation 


159 


TABLE  V 

Effect  of  Verbalization  on  Learning 

Number  of  trials  rcquirc-d  for  children  to  learn  to 
assemble  a  mechanical  puzzle.  The  amount  of  the 
child's  verbalization  increases  from  item  1  to  item  6. 
[From  Louise  Thompson,  The  role  of  verbalization  in 
learning  from  demonstration,  unpublished  dissertation, 
Yale  University,  1944.] 

A  vera^e 
Number       Number 
Subjects        Trials 
Group  Procedure  Learning    Required 

1  Silent  demonstration.    Child  required 

to  count  so  as  to  prevent  verbaliza- 
tion. 3  25  + 

2  Silent  demonstration.    Child  describes 

proceedings  orally.  22  22.00 

3  Demonstrator  describes  partly.    Child 

watches  and  may  verbalize  silently  25  16. 16 

4  Demonstrator  describes  fully.     Child 

watches  and  may  verbalize  silently.  25  14.12 

5  Teacher  watches  but  makes  correc- 

tions when  child's  description  is  in 

error.  25  12.44 

6  Same  as  5,  except  that  blocks  are  num- 

bered in  the  order  in  which  they  are 

to  be  assembled.  25  9.52 

are  used  decrease  in  the  order  just  given, 
with  the  visual  methods  appearing  but  in- 
frequently. The  learning  curves  of  sub- 
jects using  the  different  methods  show  the 
clear  superiority  for  the  verbal  method 
over  the  other  two  and,  usually,  a  superior- 
ity of  visual  over  motor  cues.     Table  VI 

TABLE  VI 

Performance    Scores    Made    by    Subjects    Using 

Different  Modes  of  Attack 

[Data  from  R.  W.  Husband,  /.  genet.  Psychol.,  1931, 

39,261,269.] 


Average 

Mode  of 

Number 

Score 

Time 

Attack 

Trials 

{Errors) 

{Seconds) 

Verbal  method 

10.1 

20 

358 

Visual  method 

15.0 

29 

505 

Motor  method 

25.8 

23 

802 

gives  a  sample  set  of  results  for  one  section 
of  a  high-relief  finger  maze  on  which  the 
subject,  without  the  use  of  vision,  learns 
to  trace  a  raised  line  with  one  finger.    Simi- 


lar results  liave  been  found  with  stilus 
mazes  (the  maze  is  made  of  grooves  and  the 
path  is  traced  with  a  stylus  while  vision  is 
excluded)  where  the  more  intelligent  sub- 
jects are  likely  to  adopt  the  verbal  method. 
Tlie  pronounced  superiority  of  the 
verbal  method  over  the  motor  in  the  learn- 
ing of  a  motor  problem  is  significant.  It 
shows  that  tlie  motor  skill  as  actually  ac- 
quired by  most  subjects  is  learned  as  a  pat- 
tern with  both  verbal  and  motor  constit- 
uents. The  so-called  motor  learning  is  not 
limited  to  the  learner's  perception  of  his 
own  movements,  for  the  trials,  errors  and 
successes  are  often  ideationally  controlled. 
Learning,  furthermore,  proceeds  much 
more  rapidly  when  the  ideational  factors 
are  employed.  These  facts  also  show  that 
there  is  no  clean-cut  division  between  dif- 
ferent kinds  of  materials  with  respect  to 
the  activities  they  require. 

Active  Participation 

The  more  the  learner  enters  into  his 
task,  the  more  effective  is  his  learning. 
Many  times  active  participation  is  insured 
by  the  nature  of  the  task,  as  in  learning  to 
pilot  a  plane.  On  the  other  hand,  in  a 
great  deal  of  instruction  in  school  and  col- 
lege, material  is  presented  to  the  learner, 
as  in  lectures,  while  the  learner  fails  to 
participate  in  the  learning  process,  merel\ 
sitting  back  and  reacting  passively.  In 
these  cases  the  teacher  can  improve  in- 
struction significantly  by  demising  means  of 
instiring  acti\e  jjarticipation  bv  the  learner. 

An  experiment  from  tlie  uaining  of  sol- 
diers in  the  Army  illustrates  the  difference 
between  active  and  passive  learning.  The 
objective  was  to  teach  the  soldiers  the  pho- 
netic alphabet,  in  which  word  equivalents 
are  learned  for  letters,  like  Able  for  A. 
Baker  for  B,  Charlie  for  C.  etc.  This  svs- 
tem  increases   the   claritv  and  accuracv  of 


160 


Learning 


material  transmitted  o^■er  telephone  com- 
munication systems. 

The  standard  method  of  instruction  was 
to  employ  a  film  in  which  the  letter,  pre- 
sented on  the  screen,  was  followed  by  the 
equivalent  word.  After  a  number  of  indi- 
vidual letters  had  been  presented,  a  portion 
of  the   list  was  repeated   by   the   narrator. 


Participation  method 


0    12     3    4     5  10  15 

Time  following  presentation  of  letter  in  seconds 

FIGURE   6o.      ACTIVE   PARTICIPATION    AS   AN    AID   TO 
LEARNING 

The  subjects  learned  phonetic  names  for  letters, 
like  Able  for  A,  (a)  by  a  passive  method  (listening 
to  the  narrator  repeat  the  letter-word  combina- 
tions) and  (b)  by  a  participation  method  (reciting 
aloud  the  combinations).  The  graphs  show  the 
number  of  items  recalled  in  different  periods  of 
time  after  the  presentation  of  the  letter.  The  active 
participation  method  is  more  efficient.  [.Adapted 
from  the  forthcoming  Experimental  studies  of 
Army  educational  films.] 

In  the  participation  method  the  same  film 
was  used,  but,  instead  of  the  narrator's  re- 
peating the  words  in  groups,  the  trainees 
were  instructed  to  recite  aloud  the  word 
equivalent  when  each  letter  was  presented, 
thus  insuring  active  rehearsal.  The  ef- 
fectiveness of  this  procedure  is  shown  in 
Fig.  60. 

Since  learning  depends  on  motivation, 
active  participation  is  basic  to  learning. 
Teaching  does  not  compel  learning,  for  the 
learner  must  himself  participate.    The  best 


that  teaching  can  do  for  learning  is  to  pro- 
vide optimal  conditions  for  its  achieve- 
ment. The  teacher  makes  the  materials 
to  be  learned  available  to  the  student,  he 
gives  instruction  as  to  the  best  methods  of 
learning  and  in  some  cases  requires  by 
periodic  examinations  a  favorable  distribu- 
tion of  practice,  and  then  he  resorts  to  all 
the  conventional  devices  and  the  other 
means  that  his  own  ingenuity  supplies  to 
induce  the  students— to  'motivate'  them— to 
participate  actively  in  the  learning  process. 
The  ultimate  responsibility,  however,  is 
the  learner's.  It  is  he  who  must  accept 
participation  if  he  is  to  learn. 

Recitation 

One  way  actively  to  participate  in  learn- 
ing is  to  begin  using  the  material  learned 
before  the  learning  is  complete.  A  man 
learning  a  maze  may  rehearse  verbally  to 
himself  the  turns  which  he  has  just  made, 
Avhile  at  the  same  time  he  is  going  forward 
through  other  sections.  W^en  he  has  to 
memorize  a  list  of  words  he  may  try  to  re- 
peat the  list  without  the  copy  before  he  has 
fully  learned  it.  In  one  experiment,  the 
learning  of  lists  of  nonsense  syllables  and 
of  short  biographies  was  practiced,  some- 
times by  repeated  readings  until  they  were 
learned,  and  at  other  times  by  reading  fol- 
lowed by  recitations  with  prompting  given 
whenever  necessary.  The  relati\e  effective- 
ness of  recitation  in  varying  proportions  is 
shown  in  Table  VII,  where  the  percentages 
of  material  recalled  immediately  at  the 
close  of  the  learning  period  are  presented. 

These  results  show  that  direct  repetition- 
plus-recitation  yields  larger  increments  of 
learning  than  time  spent  only  in  direct 
repetition,  and  that  the  increments  in- 
crease when  the  proportion  of  the  total 
learning  time  spent  in  recitation  increases. 
The  advantage  of  recitation  is  greater  with 


Acquisition  of  Skills 


161 


TABLE  VII 

Infi.uf.nck  of  Different  A-mounts  of  Rkcitaiion 

UPON    I-EARNlNt; 

The  figures  are  for  subjects  in  Cirade  VIII  and  have 
been  obtained  by  computing  the  percentage  which  the 
amount  learned  by  each  method  is  of  the  average  of 
all  methods.  [From  A.  I.  Gates,  /ink.  Psycho/.,  1917, 
6,  36,  41.] 


Per  Cent 

of  Total 

Time 

Spent 

In 

In  Reci- 

Materials Learned 

Reading 

tation 

Syllables 

Biographies 

100 

0 

65.4 

87.8 

80 

20 

92.2 

94.6 

60 

40 

99.7 

105.0 

40 

60 

105.5 

105.5 

20 

80 

137.3 

106.8 

the  nonsense  syllables  than  with  the  biogra- 
phies, probably  because  the  biogiaphies  in- 
vite more  active  organization  of  the  ma- 
terial during  its  repetition  than  the  non- 
sense syllables.  Other  investigators  have 
found  that  more  favorable  results  are  ob- 
tained when  readings  and  recitations  are 
interspersed  than  when  they  are  grouped 
together. 

The  superiority  of  reading-plus-recita- 
tion over  reading  alone  results  from  sev- 
eral independent  conditions.  (1)  The  reci- 
tation arouses  more  active  participation  by 
the  subject.  (2)  During  recitation  the  sub- 
ject is  practicing  the  recall  of  the  material 
in  the  way  he  is  to  use  it  later  when  tested. 
(3)  The  recitation  yields  progressive  infor- 
mation about  errors  and  right  responses, 
thereby  permitting  the  correction  of  errors 
through  prompting  from  the  copy  and  pro- 
viding increased  motivation  for  improve- 
ment. 

ACQUISITION    OF    SKI  LLS 

When  we  acquire  through  learning  a  co- 
ordinated   series    of    responses    which    are 


p(ii(jt  MK-d  wiili  jjroficiency,  we  speak  of  llic 
acfoniplisfiriKrit  as  skill.  Playing  the 
piano,  piloting  a  plane  and  reciting  a  poem 
are  all  skills.  (Jiaractcristif ally,  they  in- 
volve a  serial  organization  of  responsts. 
The  name  serial  learning  is  applied  to  the 
process  of  learning  such  a  sequence  of  re- 
sponses. 

One  of  the  commonest  types  of  serial 
learning  is  the  learning  of  verbal  material, 
like  a  poem,  so  that  we  can  recite  it  all  the 
way  through.  'Ihe  process  of  learning 
poems  has  been  analyzed,  but  for  the  care- 
ful study  the  use  of  poetry  presents  certain 
difficulties.  For  one  thing  some  poems  are 
easy  and  others  hard,  and  it  is  difficult  to 
know  how  much  previous  experience  the 
subject  has  had  with  the  particular  poems. 
Even  the  separate  words  will  not  be  uni- 
form in  their  associations  from  person  to 
person.  To  overcome  these  difficulties 
many  studies  have  used  materials  de\oid 
of  much  meaning  so  that  all  learners  can 
start  learning  with  an  equal  degree  of  un- 
familiarity  with  the  material.  The  method 
of  achieving  this  end  w^e  owe  to  the  Gei- 
man  psychologist,  Ebbinghaus,  who  de\el- 
oped  the  system  of  nonsense  syllables  for 
use  in  memory  experiments.  They  are  usu- 
ally three-letter  units  of  two  consonants 
with  a  vowel  between  them.  Lists  of  these 
syllables  of  equivalent  difficulty  can  be 
readily  prepared.  In  the  laboratory  the 
syllables  are  usually  presented  by  an  aiuo- 
matic  machine,  and  the  experimenter  re- 
cords the  subject's  progress  in  learning  the 
list. 

Often  a  motor  skill  also  involves  learn- 
ing in  serial  order.  A  device  frequently 
used  for  studying  diis  type  of  learning  in 
its  simplest  form  is  a  ?naze.  The  maze,  a 
sample  of  ^vhich  is  shown  in  Fig.  61,  can  be 
used  to  study  both  animal  and  human 
learning.      In    animal    studies    white    rats 


162 


Learning 


have  been  used  most  frequently  with  mazes 
similar  to  the  one  illustrated  and  with 
more  complicated  ones.  A  hungry  rat  is 
put  at  one  end  and  required  to  learn  the 
path  to  the  food  box,  where  it  is  fed.     It 


I'lGURE   61. 


11  pic:al  stylus-maze  pattern 


The  subject  learns  to  trace  with  a  stylus  the  cor- 
rect path  from  the  start  (S)  to  the  goal  (G).  He  is 
hlindlolded  or  else  prevented  from  seeing  the  maze 
and  his  own  hand  by  a  screen.  [From  C.  J.  War- 
den, /.  exper.  Psychol.,  1924,  7,  101.] 

will  be  observed  that  this  learning  is  simi- 
lar to  that  stvidied  by  Thorndike  with  his 
cats,  except  that  it  involves  a  sequence  of 
acts,  rather  than  a  single  one,  to  achieve 
tlie  goal. 

Mazes  have  also  been  used  with  human 
subjects.  .Sometimes  a  large  maze  is  con- 
structed through  which  the  subject  must 
learn  to  walk  to  find  the  goal.  More  fre- 
quently, however,  the  same  task  can  be  ar- 
ranged by  using  a  stylus  maze  in  which  the 
maze  pattern  is  cut  into  the  surface  and  the 
subject  traces  the  path  (constantly  blind- 
folded, of  course)  with  a  stylus  (Fig.  61). 


In  the  learning  of  many  acts  of  skill  the 
task  continually  changes  as  greater  skill  is 
achieved.  This  type  of  learning  has  been 
studied  most  extensively  in  telegraph  send- 
ing and  receiving,  but  an  identical  prob- 
lem is  involved  in  learning  to  type.  At 
low  speeds  we  learn  to  inake  an  appropri- 
ate movement  for  each  letter  reqtiired,  for 
example,  to  press  the  a,  then  the  71  and 
finally  the  d  in  and.  As  greater  skill  is 
achieved  we  respond  with  an  integrated  act 
of  successively  pressing  the  three  keys  to 
the    total    word    and.      With    still    greater 


10  - 


_2   6 

E 


1 

1    1    1    1    1    1    1    1    1    1 

- 

Massed-,^/        S.                   _ 

_ 

/  ^^"x\  - 

/      ''              V     \ 

~ 

/  ^           ^>-  X  "^ 

/  ''                  "^'vX 

— 

/     /'<=- Distributed                  "A 

- 

//                                             A 

/  /                                                    > 

~ 

/  (f                                                     ~ 

^^ 

1      1      1      1       1       1       1      1       1      1 

4  - 


2  - 


2  4  6  8  10 

Position  of  syllables  in  series 


12 


FIGURE    62.       EFFECT    OF    SERIAL    POSITION    ON 
LEARNING 

Composite  curves  showing  mean  number  of  fail- 
ines  in  recall  at  various  syllable  positions  involved 
in  the  series  when  the  subject  learns  the  lists  to 
complete  mastery  by  massed  and  by  distributed 
practice  with  a  2-second  rate  of  presentation.  The 
beginning  is  learned  best,  the  middle  least.  Dis- 
tributed practice  is  better  than  massed.  [From  C.  I. 
Hovland,  J.  exper.  Psychol,  1938,  23,  178.] 

practice,   phrases   and   even   complete   sen- 
tences are  learned  as  units. 

From  studies  of  serial  learning  we  find 
that  the  various  portions  of  a  sequence 
are  not  equally  difficult  to  learn.    The  first 


Acquisition  of  Skills 


163 


responses  and  the  last  responses  are  easiest, 
and  the  middle  ones  the  most  difficull.  A 
typical  curve  of  difficulty  is  presented  in 
Fig.  62.  These  results  have  sometimes  been 
explained  by  the  principles  of  pritiiary  and 
recency.  The  first  principle  states  that, 
other  things  being  equal,  the  first  experi- 
ence is  most  readily  learned.  The  prin- 
ciple of  recency  is  that  recent  experiences 
are  remembered  more  vividly  than  earlier 
ones.  Current  studies  indicate  that  the 
first  and  last  responses  are  usually  easiest 
to  learn  because  of  a  minimum  of  inter- 
ference. Maximum  interference  is  in  the 
central  portion  of  a  series. 

When  a  rat  learns  a  maze,  the  law  of  ef- 
fect enters  into  serial  learning.  The  rat 
learns  first  the  goal  end  of  the  maze  where 
the  food  lies.  As  learning  progresses  his 
skill  extends  farther  and  farther  backward 
from  the  goal,  being  least  at  the  very  start 
of  the  maze  which,  of  course,  lies  farthest 
away  from  the  satisfying  goal.  This  in- 
creasing familiarity  with  the  maze  as  the 
goal  is  approached  is  called  the  goal 
gradient,  which  thus  constitutes  a  striking 
example  of  the  operation  of  the  law  of 
effect. 

It  is  clear  that  serial  learning  involves 
many  different  factors.  A  rat  learning  to 
run  a  maze  is  not  like  a  person  learning  a 
poem.  The  person  remembers  the  poem 
by  its  first  line  and  can  find  it  again 
through  an  index  of  first  lines,  but  the  rat 
must  remember  the  maze  by  its  last  line, 
as  it  were,  by  the  food  to  which  it  led. 

Basic  Principles  in  the 
Acquisition  of  Skills 

All  the  principles  of  learning  bear  on  the 
problem  of  obtaining  efficiency  in  the  ac- 
quisition of  skills,  but  there  are  certain 
practical  rules,  based  upon  these  principles, 
which  may  be  set  do^vn.     Here  they  are. 


(I)  SlreA.s  the  (orred  prnfonnuncf;  from 
I  he  slarl.  In  other  words,  do  not  let  wrong 
habits  get  established.  This  rule  may  seem 
obvious  enough,  stated  in  this  general  way, 
yet  you  often  try  to  learn  skills  in  the  hofx; 
that  you  can  discover  the  correct  way  by 
trial  and  error.  Then  it  is  that  pradice 
may  not  make  perfect.  Practice  makes  per- 
fect only  when  jjracticc  is  restricted  to  tlu- 
conect  performance.  Use  trial-and-error  il 
you  must,  but  not  when  available  informa 
tion  will  enable  you  to  avoid  error.  Never 
practice  errors  when  truth  can  be  had  for 
the  asking. 

In  skills,  like  golf  or  typing,  you,  as  the 
learner,  often  keep  practicing  without  im- 
provement. Guidance  may  be  necessary  to 
bring  about  improvement.  A  skilled 
teacher  or  coach  can  often  demonstrate  the 
exact  form  of  the  correct  response,  thus  en- 
abling you  to  discriminate  between  corret  t 
and  incorrect  procedures.  For  example, 
one  of  the  reasons  it  is  so  difficult  to  stojj 
slicing  in  golf  is  that  the  difference  be- 
tween the  correct  drive  and  the  slice  is  not 
sufficiently  obvious  to  you.  If  you  felt  a 
jab  in  the  back  when  you  took  up  the  posi- 
tion which  results  in  slicing,  onlv  a  few 
trials  would  suffice  to  abolish  your  incor- 
rect movements.  Since  there  is  no  such 
dramatic  differentiation,  you  may  ne\er  b\ 
yourself  develop  the  proper  drive.  ^V'hat 
the  'pro'  does  is  to  show  vou  the  specifi( 
respects  in  which  the  right  and  the  Anong 
methods  differ,  and  he  shows  vou  just  Avhen 
you  are  about  to  make  the  response. 

(2)  Concentrate  on  the  actual  task  to  be 
learned.  This  principle  is  closely  related 
to  the  first.  To  be  most  effecti^e.  learning 
should  be  directed  to  the  actual  operations 
you  want  to  perform.  Training  bv  trans- 
fer from  a  similar  skill  ahvays  gives  per- 
formance inferior  to  direct  practice.  This 
rule  means  that  you  should  practice  on  a 


164 


Learning 


full-sized  standard  tyjjewritei.  a  full-sized 
piano  keyboard,  with  real  golf  clubs.  Do 
not  attempt  to  practice  tennis  by  playing 
squash.  Anyone  who  has  learned  to  type 
by  the  touch  system  after  having  originally 
learned  by  the  'hunt-and-peck'  system  can 
attest  to  the  fact  that  just  having  had  ex- 
perience in  operating  a  typewriter  is  not 
enough;  )ou  have  to  practice  the  identical 
motions  involved  in  tlie  finished  perform- 
ance, for  otherwise  old  habits  are  always 
interfering  with  the  new.  (That  is,  nega- 
tive transfer;  see  p.  180.) 

(3)  Learn  in  natural  units,  not  piece- 
meal. You  have  seen  that  learning  in  large 
units  is  ordinarily  more  efficient  than  piece- 
meal learning.  Too  often  practice  is  di- 
rected to  small  details  instead  of  to  the  en- 
tire performance.  This  neglect  of  the 
larger  units  results  in  the  learner's  being 
able  to  perform  the  detailed  acts,  while  re- 
maining unable  to  coordinate  them  in  a 
finished  performance.  The  natural  rhythm 
of  the  entire  operation  is  broken  by  the 
concentration  on  minute  details.  You 
sometimes  see  people  learning  to  play  golf 
by  learning  first  the  up  stroke  and  then 
the  down  stroke;  they  should  learn  the 
total  pattern  into  which  both  these  two 
parts  must  fit  smoohly. 

This  rule  does  not  mean  that  learning 
should  not  sometimes  be  broken  down  into 
convenient  imits,  but  merely  that  the  imits 
must  be  natural  rather  than  artificial.  The 
unit  of  practice  must  involve  the  entire  se- 
quence or  pattern  which  is  essential  for 
correct  performance.  Thus,  in  learning  to 
drive  a  car,  practice  may  be  profitably 
broken  up,  with  separate  practice  on  start- 
ing a  car  from  rest,  but  the  principle  would 
be  violated  if  the  learner  were  to  concen- 
trate first  on  operating  the  clutch,  then  on 
the  gearshift,  then  on  the  accelerator,  since 
the  finished  pattern  for  this  operation  al- 


ways involves  simidtancous  movements  of 
the  accelerator,  clutch  and  gearshift,  and 
practice  on  the  separate  movements  will 
not  bring  about  a  smooth  integration  of 
motions. 

Learning  to  type  is  gieatly  accelerated  by 
applying  this  principle.  In  typing,  the 
natural  unit  is  the  word;  yet  for  years 
students  were  taught  to  practice  the  indi- 
vidual letters  first  (the  well-known  r-t-y-u 
method),  coming  to  words  later.  Learning 
the  general  layout  of  the  keyboard  and 
then  beginning  at  once  to  practice  whole 
words  instead  of  letters  have  reduced  the 
number  of  trials  required  for  learning  by 
more  than  half. 

(4)  Space  learjiing  trials.  The  experi- 
ment cited  earlier  concerning  the  advan- 
tages of  distributed  over  massed  practice  is 
relevant  to  the  acquisition  of  skills.  Two 
rounds  of  golf  on  one  day  are  likely  to  be 
less  effective  training  than  one  round  on 
each  of  two  days.  Materials  learned  by 
speed-up  processes  are  also  likely  to  be 
more  rapidly  forgotten,  as  you  will  recall  if 
you  have  ever  tried  'cramming.'  Deter- 
mine for  the  skill  you  are  learning  the 
period  which  is  short  enough  to  avoid  fa- 
tigue, boredom  and  interfeience  effects,  but 
long  enough  to  avoid  wasting  time  in 
getting  warmed-up  for  the  task. 

(5)  Overlearn;  do  not  count  on  barely 
learnijig  the  task.  For  a  performance  to  be 
skilled  it  must  be  a  smooth  flawless  coor- 
dination of  responses.  To  achieve  such  in- 
tegration, it  is  not  nearly  enough  that 
learning  should  continue  until  a  single 
correct  performance  is  reached.  Any  such 
minimally  learned  performance  will  be 
quickly  forgotten  and  easily  disrupted  by 
even  slight  distraction.  The  armed  forces 
in  the  late  war  were  well  aware  of  the  im- 
portance of  this  principle  in  teaching  com- 
plex military  skills.     Men  were  given  prac- 


Rules  for  Learning 


165 


tice  long  after  Lhcy  ihoiiglu  tlicy  'knew  ;ill 
about  it.'  This  overiearning  was  designed 
to  take  care  of  tfie  needed  peiiorniante  of 
these  skills  under  battle  tondilions  where 
fatigue,  fear  and  confusion  would  have  a 
disrupting  influence  on  any  but  the  best- 
learned  habits.  You  will  find  that  any 
skill  you  wish  to  perform  in  public  must 
be  similarly  overlearned  to  prevent  its  be- 
ing broken  up  by  stage  fright  or  distraction. 
(6)  Speed  or  accuracy?  From  these  spe- 
cific principles  and  the  earlier  analysis  of 
learning  in  this  chapter  you  should  your- 
self be  able  to  deduce  the  answers  to  many 
specific  problems  that  arise  in  acquiring 
skills.  Should  you,  for  example,  stress  ac- 
curacy or  speed  first  in  learning  manual 
skills?  You  know  that  the  correct  pattern 
must  be  practiced  from  the  very  start,  if 
that  is  at  all  possible.  You  must,  there- 
fore, analyze  the  operations  to  determine 
whether  the  performance  at  a  slow  speed 
is  the  same  as  that  at  a  high  speed.  If  it 
is,  you  should  start  your  learning  with  em- 
phasis upon  accuracy,  so  that  the  exactly 
correct  performance  is  carried  out  from  the 
very  beginning.  This  relationship  certainly 
holds  in  learning  typing.  No  fvnidamental 
change  in  the  nature  of  the  moveinent  oc- 
curs as  greater  speed  is  achieved.  If,  on  the 
other  hand,  the  operation  changes  signifi- 
cantly between  low  and  high  speeds,  you 
should  strive  toward  the  form  of  the  finally 
correct  performance  even  if  some  accuracy 
must  be  sacrificed.  This  type  of  learning 
exists  in  bricklaying.  An  entirely  different 
method  is  involved  when  the  job  is  done 
slowly,  one  which  hardly  resembles  the 
form  used  when  the  work  is  performed  rap- 
idly. Speed  would,  therefore,  have  to  be 
stressed  from  the  start,  even  if  the  learner's 
work  would  have  later  to  be  redone  by 
an  experienced  bricklayer.  Thus  the  para- 
dox as   to  whether  to  stress  speed  or  ac- 


(  uracy  first  (an  be  best  resolved  in  the  par- 
ticular situation. 

(7)  /low  much  guidance?  1  his  is  another 
pLi/zling  problem.  How  much  help  or 
guidance  should  you  have  at  the  beginning 
of  learning?  Analysis  of  this  problem  in- 
dicates that  some  guidance  is  usually 
needed  at  the  start  to  help  establish  the 
correct  pattern  and  avoid  practicing  errors. 
But  it  is  also  ti  ue  that  tfie  learner  must 
learn  the  task  in  the  manner  in  which  it 
will  have  to  be  performed  later.  He  will 
not,  then,  want  to  become  dependent  upon 
someone  else  for  help  and  guidance,  not  for 
very  long.  An  intermediate  procedure 
works  best.  Let  the  learner  get  help  when 
he  thinks  he  needs  it  but  cultivate  self- 
reliance  in  his  learning. 

(8)  Motivation.  Attention  to  these  prac- 
tical rules  must  not  lead  you  to  forget  the 
great  importance  of  motivation  in  the 
learning  of  skills  and  all  other  tasks. 
Knowledge  of  results,  competition  with 
yourself  and  other  persons  are  useful  mo- 
tivating devices.  Enthusiasm  and  real  de- 
sire to  progiess  are  factors  which  distin- 
guish the  mediocre  from  the  exceptional 
learner  of  skills.  The  man  who  can  bring 
zest  to  his  learning  has  a  great  advantage, 
but  the  zest  must  be  controlled  by  wisdom. 
Errors  too  can  be  quickly  learned  zestfullv. 

REFERENCES 

1.  Bird,  C,  and  Bird,  D.  M.  Learning  more  by 
effective  study.  New  York:  Appleton-Centur\ . 
1945. 

An  analysis  of  factors  affecting  efficieno  in 
study  and  a  description  of  the  effects  of  pro- 
grams designed  to  improve  efficiency. 

2.  Garrett,  H.  E.  Great  experiments  in  psy- 
etiology.  (Rev.  ed.)  Xew  York:  Appleton-Cen- 
tiiry,   1941.     Chaps.   3  to   7. 

Interesting  accounts  of  the  experimental  con- 
tributions to  the  study  of  learning  by  Ebbing- 


166 


Learning 


haus,  Pavlov,  Thorndike,  Woodwoitli  and  Wal- 
son. 
3.  Guthrie,    E.    R.      The    /wvf/(o/ogv    of    Iraniiiig. 
New  York:   Harper,   1935. 

A  provocative  attempt  to  cover  all  tlie  major 
aspects  of  learning  in  terms  of  the  principle  of 
association.     Quite  readable. 

t.  Hilgard,  E.  R.,  and  Marquis,  D.  G.  Condition 
ivg  and  learning.  New  York:  Appleton -Cen- 
tury, 1940. 

A  systematic  coverage  of  the  empirical  stud- 
ies of  conditioned  response  learning  and  the 
implication  of  these  studies  for  the  general 
analvsis  of  all  types  of  learning. 

r>.  Hull,  C.  L.  Learning:  the  factor  of  the  con- 
ditioned reflex.  In  C.  Murchison  (Ed.)  ,  A 
handbook  of  general  experimental  psychology. 
Worcester,  Mass.:  Clark  University  Press, 
1934. 

A  comprehensive  review  of  the  most  signifi- 
cant experimental  studies  of  the  phenomena  of 
conditioning  published  from  1902  to  1934. 

5.  Hull,  C.  L.  Principles  of  bcltavior.  New 
York:   Appleton-Centiiry,   1943. 

An  analysis  of  the  fundamental  principles  of 


behavior    derived    from    numerous    conditioned 
response  experiments.    Not  easy  reading. 

7.  Hunter,  W.  S.  Learning:  experimental  studies 
of  learning.  In  C.  Murchison  (Ed.),  A  hand- 
book of  general  experimental  psychology. 
Worcester,  Mass.:   Clark  University  Press,   1934. 

A  good  summary  of  experimental  studies  of 
the  acquisition  and  retention  of  learning  up  to 
1934. 

8.  Kingsley,  H.  L.  The  i\ature  and  conditions  of 
learning.    New  York:  Prentice-Hall,  1946. 

The  most  recent  coverage  of  the  facts  of 
learning  with  a  good  discussion  of  the  rele- 
vance of  these  facts  to  the  educative  process. 

9.  McGeoch,  J.  A.  TIte  psychology  of  human 
learning.     New  York:    Longmans,  Green,    1942. 

The  most  authoritative  and  comprehensive 
summary  of  present  evidence  concerning  fac- 
tors affecting  human  learning. 

10.  Miller,  N.  E.,  and  Bollard,  J.  Social  learning 
and  iinitalinn.  New  Haven:  Yale  l'ni\ersity 
Press,    1941. 

In  these  chapters  there  is  a  clear  and  inter- 
esting analysis  of  learning  from  the  point  of 
view  of  stimulus  and  response,  applied  later  tc 
problems  in   social  psychology. 


CHAPTER 


8 


Retention  and  Transfer  of  Learning 


IN  the  preceding  chapter  we  studied  learn- 
ing, the  way  learning  is  accomplished, 
the  fundamental  conditions  which  favor 
and  hinder  learning.  Now  wc  must  con- 
sider, first,  retention  of  learning,  and  its 
opposite,  which  is  forgetting.  When  do  we 
remember  and  when  forget?  How  fast 
does  forgetting  go  on?  And  what  makes 
us  forget? 

In  answering  these  questions  we  shall 
find  ourselves  studying  the  interactions  be- 
tween different  learnings.  Sometimes 
learning  one  thing  means  unlearning  an- 
other. Sometimes  learning  one  thing 
makes  it  easier  to  learn  another.  There  is 
a  transfer  effect  from  the  learning  of  one 
thing  to  the  learning  of  another,  a  transfer 
which  may  in  some  cases  help  and  in  other 
cases  hinder  the  new  learning. 

With  these  complex  principles  and  their 
use  in  the  formation  of  efficient  habits  of 
study,  the  present  chapter  is  concerned. 

RETENTION    AND    FORGETTING 

One  phenomenon  with  which  we  are  all 
familiar,  often  to  our  regret,  is  forgetting. 
We  can  learn  the  meanings  of  a  thousand 
French  words,  but,  unless  we  use  them,  the 
new  knowledge  gradually  disappears  until 
only  a  few  meanings  can  be  correctly  gi\en. 


The  earliest  systematic  study  of  forget- 
ting was  made  by  Ebbinghaus.  He  himsell 
learned  lists  of  nonsense  syllables  until  he 
could  recite  a  list  of  them  without  er)or. 
Then  he  tried  to  repeat  the  recitation  after 


2  3         4 

Time  interval  in  days 

FIGURE  63.      ebbinghaus'   CURVE  OF  RETENTION    AS 
MEASURED    BY    THE    METHOD    OF    SAVINGS 

Shows  decrease  in  savings  when  original  material 
is  lelearned  after  different  periods  of  elapsed  time 
lip  to  6  days.  [Data  from  H.  Ebbinghaus.  Memory. 
I'eacbers  College,  Colmnbia  I'niversity,  trans.  191.^. 

p.    76.] 

allowing  various  periods  of  time  to  elapse. 
Figure  63  is  his  curve  that  shows  the  de- 
crease in  retention  with  time— tire  forget- 
ting curve.  The  figure  indicates  that  he 
found  a  continuous  loss  in  retention  Avith 
increases  in  the  length  of  time  during  the 
first   six   davs   after   the   oria:inal   learnina;. 


This  thaptor  A\as  prepared  by  Carl  I.  Hovhiiul  of  ^  ale  lTni\ersity. 

167 


168 


Retention  and  Transfer  of  Learning 


The  rate  ot  loss  was  rapid  at  first  and  then 
much  less  rapid  as  time  went  on. 

How  Retention  Is  Measured 

The  simplest  way  to  measure  retention 
is  to  determine  the  amount  we  can  recall  of 
the  material  originally  learned.  This  is 
usually  called  the  method  of  recall,  or 
sometimes  the  method  of  reproduction. 
Recall  scores  are  usually  given  as  the  per- 
centage of  the  original  material  that  can 
be  recalled  at  a  later  time.  If,  for  exam- 
ple, we  learn  the  meaning  of  twenty  French 
words  today  but  can  recall  only  thirteen 
tomorrow  our  recall  score  would  be  i%o 
or  65  per  cent. 

Sometimes,  after  several  years  have 
elapsed,  we  cannot  recall  a  single  line  of  a 
poem  we  had  learned  earlier;  yet,  if  we 
attempt  to  memorize  it  again,  we  find  it 
comes  back  rapidly  as  compared  with  the 
original  learning  of  the  same  poem.  This 
fact  suggests  another  way  of  measuring  how 
much  we  retain  of  what  we  have  learned, 
the  method  of  relearning  or  saving  which 
was  first  employed  by  Ebbinghaus  and  has 
been  widely  used  since.  The  subject  is 
asked  to  relearn  the  material  after  a  time 
interval,  and  his  performance  is  compared 
wath  the  amount  of  time,  number  of  trials 
or  number  of  eiTors  required  to  learn  it  in 
the  first  place.  If,  for  example,  it  took 
Ebbinghaus  33  trials  to  learn  a  list  of  15 
nonsense  syllables  to  the  point  where  he 
could  repeat  them  once  without  error,  and 
after  six  days  it  took  him  only  II  trials  to 
relearn  them  to  the  same  standard  of  per- 
formance, we  would  say  he  had  made  a  sav- 
ing of  22  trials  (33  minus  11.)  These  re- 
sults are  often  expressed  as  a  savings  score 
in  which  the  numerator  is  the  number  of 
trials  saved  and  the  denominator  the  orig- 
inal number  of  trials.  In  the  present  ex- 
ample Ebbinghaus  woidd  have  had  a  sav- 


ings score  of  -%->,  or  67  per  cent.  The 
curve  of  Fig.  63  was  determined  by  the 
method  of  savings. 

A  third  method  is  the  method  of  recog- 
nition. Here  the  subject  is  shown  the  ma- 
terial which  he  formerly  learned  together 
with  other  items  which  had  not  been 
shown  him  initially,  and  he  is  asked  to 
identify  the  items  which  were  in  the  orig- 


OlLU 

off   ^4  t 
P-l  hr 


2  days 


hr  1  day 

-20  min  Time  interval 

FIGURE   64.      RETENTION    CURVES   OBTAINED   BY    DIF- 
FERENT   METHODS   OF    MEASUREMENT 

[From   C.    W.   Luh,   Psychol.   Monogr.,    1922,   31, 
No.  142,  22.] 

inal  material.  In  one  memory  test,  pic- 
tures of  a  number  of  persons  are  studied 
by  the  subject,  and  he  is  asked  later  to  say 
which  ones  he  has  seen  before.  This  pro- 
cedure is,  of  course,  the  well-known  method 
used  by  the  police  for  identifying  suspects. 
When  material  has  been  learned  in  serial 
order,  a  fourth  procedure  is  often  used  in 
which  the  learner  is  given  the  original 
items  all  mixed  up  and  is  then  required  to 
arrange  them  in  the  original  order.  This 
is  called  the  method  of  reconstruction. 
The  learner  recalls  the  relationships  but 
not  the  terms  related.  As  a  matter  of  fact 
a  subject  who  can  reconstruct  a  series  can 
nearly  always  also  identify  the  terms.  The 
method  is  useful  for  studying  the  learning 


Refention  and  Forgetf'ing 


169 


of    series    of    iinrejjrodutiljle    icniis,    like 
odors  or  photof^r.iphs. 

The  type  of  forf^cttiiig  curve  obtained  is 
to  some  extent  a  function  of  the  type  of 
measurement  used  to  determine  it.  As  you 
might  expect,  forgetting  is  greatest  when 
the  learner  must  reproduce  material  ver- 
batim. The  ability  merely  to  recognize 
what  was  and  what  was  not  originally  stud- 
ied (method  of  recognition)  is  retained 
longest  after  learning.  The  methods  of 
saving  and  reconstruction  show  intermedi- 
ate amounts  of  retention.  Retention  meas- 
ured in  these  four  ways  is  shown  in  Fig.  64. 

Individual  Differences  in  Retention 

As  we  should  expect  from  the  close  rela- 
tionship between  learning  and  retention, 
wide  individual  differences  exist  in  the 
amount  of  material  retained  over  an  in- 
terval. Retention  plotted  against  age  gives 
a  curve  closely  similar  to  that  presented  in 
the  last  chapter  for  the  learning  ability  of 
various  age  groups  (Fig.  57,  p.  154).  By 
and  large,  we  find  that  more  intelligent 
persons  retain  more  than  those  less  intelli- 
gent. Closely  related  is  the  general  finding 
that  the  rapid  learner  is  more  likely  to  be 
the  good  retainer  than  the  slow  learner. 
The  slow  learner  gains  no  advantages  in  re- 
tention from  his  slowness,  and  the  fast 
learner  suffers  no  disadvantage  from  his 
fastness.  There  is  here  between  individ- 
uals no  benign  law  of  compensation,  as 
there  is  between  speed  and  accuracy  for 
the  single  individual. 

The  Exceptional  Memorizer 

Occasionally,  because  of  remarkable  per- 
formance in  memorizing  and  retaining,  a 
person  attracts  popular  attention  and  some- 
times even  scientific  study.  Persons  w4io 
can  learn  a  list  of  two  hundred  digits  in 
nine  minutes  and  retain  it  for  some  time  or 


who  can  repeat  the  numbers  of  every  car 
in  a  long  freight  train  to  a  total  wliirh  fills 
several  pages  in  the  (onduclor's  nrHcbook 
are  cases  in  point.  The  fpicstion  at  ontc 
arises  whether  such  performances  are  a  re- 
sult of  some  special  native  ability  or  of 
intensive  practice.  Certainly  these  f»er- 
formances  do  not  require  high  intelligence. 
One  man,  for  example,  who  could  give  the 
populations  of  any  of  our  laiger  cities,  had 
an  IQ  of  only  74.  The  conclusion  wiiich 
emerges  from  the  available  data  on  these 
exceptional  memorizers  is  that  their  per- 
formances are  a  result  of  special  practice. 
Their  abilities  are  usually  limited  to  nar- 
row classes  of  materials,  such  as  dates,  num- 
bers and  similar  disparate  items. 

The  exceptional  memorizer  is  highly  mo- 
tivated to  put  into  relation  and  recall  the 
materials  with  which  he  works.  He  groups 
the  items,  uses  them  whenever  possible  and 
utilizes  many  of  the  basic  methods  of  learn- 
ing and  recalling.  With  sufficient  motiva- 
tion almost  anyone  could  do  as  well.  In 
one  experiment  the  feat  of  a  memory  ex- 
pert was  duplicated  with  relatively  little 
practice  by  a  group  of  college  students. 
This  expert  could  recall  the  order  of  a  52- 
card  deck  of  shuffled  cards  after  twenty 
minutes  of  study.  The  college  students 
were  able  to  duplicate  this  performance 
after  an  average  of  5.25  practice  periods  of 
twenty  minutes  each.  Two  students  did  it 
at  the  first  sitting  and  twelve  at  the  third. 

Retention  of  DifFerent 
Types  of  Material 

A  number  of  generalizations  can  be 
made  about  die  effect  of  die  t\pe  of  ma- 
terial learned  upon  retention. 

(1)  Meaningful  materials  are  better  re- 
tained than  meaningless.  A  comparison  of 
Figs.   6S  and  65   illustrates   this   fact.     ^\'e 


170 


Retention  and  Transfer  of  Learning 


retain  better  the  material   that  we  under- 
stand than  the  material  that  we  do  not. 

(2)  The  more  extensive  the  amount  of 
material  learned,  the  better  the  retention. 
When  materials  of  varying  length  are 
learned  to  the  same  level  of  performance, 
the  longer  series  are  better  retained.  The 
greater  effort  expended  in  learning  the 
longer  lists  is,  therefore,  rewarded  with  a 


0        30       60       90      120 
Time  interval  in  days 

FIGURE    65.       RETENTION    CURVE    FOR    MEANINGFUL 
MATERIAL    (OBJECTS    OBSERVED    BRIEFLY) 

[From  J.  A.  McGeoch  and  P.  L.  VVhiiely,  /.  eiluc. 
Psvchol.,  1926,  17,  422;  reprinted  by  permission  of 
Warwick  and  York.] 

higher  degree  of  retention.  Results  on  this 
problem  are  shown  in  Table  VIII. 

(3)  Materials  which  have  pleasant  emo- 
tional tone  tend  to  be  better  recalled  than 
those  which  are  unpleasant.  Most  of  us 
can  find  in  our  own  experience  how  much 
easier  it  is  to  remember  a  pleasant  engage- 
ment than  one  which  we  expect  to  be  un- 
pleasant. And  how  much  oftener  we  recall 
our  greatest  triumph  than  our  most  embar- 
rassing moment. 

In  one  experimental  study  the  investi- 
gator asked  his  students  on  the  first  day 
after  Christmas  vacation  to  write  out  the 
experiences  which  they  had  during  the  va- 
cation period,  and  then  to  indicate  which 
of  the  items  were  pleasant  and  which  were 


TABLE  VIII 

Retention  for  Lists  Differing  in  Length 

Method  of  recall  and  method  of  savings.  The 
longer  lists,  which  require  more  work  in  learning,  are 
retained  better.  [From  E.  S.  Robinson  and  W.  T. 
Heron,  /.  exper.  Psychol.,  1922,  5,  443,  and  E.  S. 
Robinson  and  C.  W.  Darrow,  Amer.  ].  Psychol.,  1924, 
35,  241.] 

Number  of  Items         Nonsense  Syllables 

in  List  '  0  Recalled  %  Saved 

6  71.3  68.7 

9  78.3  78.8 

12  78.7  78.1 

15  77.0  80.7 

18  81.7  86.3 

Number  0/ Items  Three-Place  Numbers 

in  List  %  Recalled       %  Saved 

4  60.0                25.0 

6  66.5                72.5 

8  66.6                69.4 

10  70.8                78.9 

unpleasant.  Six  weeks  later,  without  any- 
thing having  been  said  about  the  experi- 
ment, the  students  were  again  asked  to  de- 
.scribe  their  vacation  experiences.  Of  the 
experiences  which  they  had  initially  de- 
scribed as  pleasant  they  recalled  after  six 
weeks  fifty-three  per  cent,  whereas  less  than 
forty  per  cent  of  those  initially  described  as 
unpleasant  were  recalled  on  the  second  oc- 
casion. 

Freud  and  the  other  psychoanalysts  have 
explained  such  results  in  terms  of  the  con- 
cept of  lepressioti.  They  believe  that  mem- 
ories which  are  painful  tend  to  be  ejected 
from  con.sciousness  although  still  present  in 
the  'unconscious.' 

It  is  likely  that  some  of  the  factors  ac- 
counting for  the  differential  recall  of  pleas- 
ant and  unpleasant  material  can  be  ana- 
lyzed without  recourse  to  the  concept  of 
the  unconscious.  One  important  factor  is 
the  greater  tendency  to  rehearse  our  pleas- 
urable experiences,  a  repetition  which, 
under  the  law  of  frequency,  results  in  their 


Retention  as  Affected  by  Types  of  Material  and  Original  Learning  171 


better  recall  on  later  occasions.  11,  more- 
over, we  analyze  llie  initial  un]jlcasant  ex- 
perience, we  shall  usually  notice  that  pain, 
shame  or  guilt  are  associated  with  some 
aspects  of  the  unpleasant  situation.  Not 
remembering  in  these  instances  is  a  case 
of  avoidance  conditioning.  Just  as  a  man 
learirs  to  avoid  people  who  are  lui pleasant, 
so  he  learns  to  avoid  activity  (in  this  case 
remembering)  which  is  unpleasant.  It  is 
also  true  that  we  learn  to  make  other  re- 
sponses to  the  clues  which  originally 
aroused  the  feelings  of  shame  or  guilt. 
These  responses  serve  as  distractions  and 
help  us  to  inhibit  the  recall  of  unpleasant 
events. 

Retention  as  Affected 
by  Original  Learning 

The  amount  of  material  retained  is  in- 
fluenced to  a  considerable  extent  by  the 
method  used  in  learning  it  initially. 

(1)  The  set  with  which  a  material  is  stud- 
ied affects  the  degree  to  which  it  is  reniem- 


Time  interval  in  days 

FIGURE    66.       RETENTION    CURVES    FOR    DISTRIBUTED 
AND    MASSED   PRACTICE 

Shows  mean  recall  scores  at  intervals  of  1,  3  and 
7  days  following  the  memorization  of  12  nonsense 
syllables  by  distributed  and  massed  practice.  [From 
J.  A.  McGeoch,  The  psycJiology  of  human  learning, 
Longmans,  Green,  1942,  p.  130.] 


685 

1         1         1 

1           i          / 

573 

- 

/ 

■o 
o 

/ 

=  407 

. 

/                             _ 

00 

c 

/ 

<^295 

/ 

— 

192 

/ 

- 

103 

/    1          II 

1           1 

0       8        16      24      32  42         53  64 

Number  of  repetitions  of  original  learning 

FIGURE  67.      RKTENI  ION   AS  A   FUNCTION   OF  DEGREE 
OF    ORIGINAL    LEAR.NING 

The  graph  shows  the  savings  after  24  hours  for 
different  numbers  of  repetitions  in  the  original 
learning.  [From  J.  A.  McGeoch,  The  psyrholo^-  ul 
human   learning,  Longmans,   Green,   1942.   p.   377.] 

bered.  Retention  is  gieater  when  the  ma- 
terial to  be  learned  is  studied  with  the  in- 
tent to  reinember  it  over  a  long  periotl 
than  when  it  is  studied  with  the  set  to  learn 
it  only  for  immediate  recall. 

(2)  Recitation  of  material  during  learn- 
ing increases  the  amount  -which  •will  be  re- 
tained. 

(3)  Material  learned  by  distributed  prac- 
tice is  better  retained  than  material  learned 
l)\  massed  practice,  when  both  are  learned 
to  the  same  level  initially.  Retention 
cur\es  obtained  under  these  \.\\o  condi- 
tions are  shown  in  Fig.  66.  » 

(4)  The  greater  the  degree  of  original 
learning,  the  greater  the  retention.  This 
relationship  is  illusU'ated  in  Fig.  67. 

(5)  DegTee  of  retention  depends  upon 
whether  the  original  learning  task  is  com- 
pleted or  whether  it  is  discontinued  be 
fore  completion.    (See  pp.  133  f.) 


172 


Retention  and  Transfer  of  Learning 


Reminiscence 

Although  rajjid  initial  foigeliing  is  the 
rule,  there  are  some  interesting  exceptions. 
Sometimes  we  find  that,  when  we  have  been 
studying  material  for  a  while,  we  do  better 
if  we  lay  it  aside  and  come  back  again  to 
it  later.  The  psychologist,  William  James, 
called  attention  to  this  phenomenon  in 
striking   fashion   when   he    said    that    "we 


IJ.U 

10.5 

1      1            1 

- 

ralO.O 

f^^^ 

- 

c   9.5 

N. 

- 

1   ^-^ 

\^ 

- 

S.  8.5 

—                          ^ 

•««.,„„^_^^                   — 

y 

^*''^~».^,^_^ 

1   8.0 

- 

-~~,..^ 

7.5 

- 

- 

7.0 

1     1         1 

HoH  2 


5  10 

Length  of  interval  in  minutes 


REMINISCENCE 


The  graph  shows  retention  (correct  anticipations 
in  recall)  as  a  fimction  of  elapsed  time  up  lo  20 
minutes  after  learning.  Lists  of  nonsense  syllables 
were  the  material.  Retention  is  greater  at  30  sec- 
onds and  at  2  nrinutes  than  it  was  at  6  seconds  or 
than  it  will  be  at  5  minutes  or  thereafter.  Remi- 
niscence is  this  increase  shortly  after  learning. 
[From  L.  B.  Ward,  Reminiscence  and  rote  learning, 
Psychol.  Monogr.,   1937,  49,   No.  220,   17.] 

learn  to  skate  in  the  summer  and  learn  to 
swim  in  the  winter."  This  phenomenon  of 
improvement  in  performance  without  in- 
tervening practice  is  called  reminiscence. 
A  retention  curve  showing  reminiscence  is 
shown  in  Fig.  68. 

The  conditions  under  which  reminis- 
cence rather  than  forgetting  is  obtained  are 
not  completely  known.  It  appears  at  pres- 
ent that  reminiscence  indicates  that  there 
is  some  interference  which  operates  at  the 
end  of  practice  and  which  disappears  with 
the  passage  of  time.     If  this  explanation  is 


valid  it  would  be  reasonable  to  expect  that, 
if  we  gave  short  rest  intervals  after  each 
practice  trial,  the  interferences  would  not 
accumulate  and  reminiscence  would,  there- 
fore, not  occur.  This  result  has  indeed 
been   found   and   is   shown   in   Table    IX. 

TABLE  IX 

Reminiscrnce  after  Massed  and  after  Distributed 

Practice 
[From  C.  I.  Hovland,  /.  exper.  Psychol.,  1938,  22,  212.] 

AJter  After 

Massed     Distributed 
Practice       Practice 
(a)  Number   of   syllables   recalled   on    trial 
immediately  after  learning  has  reached 
the  level  of  7  correct  syllables  out  of  12        6.96  8.00 

(J)  Number  of  syllables  recalled  on  trial  2 
minutes  after  learning  has  reached  the 
level  of  7  correct  syllables  out  of  12  7.49  8.04 

Reminiscence  =  (i)  —  (a)  0.53  0.04 

The  general  conclusion  is  that  both  remi- 
niscence and  distributed  practice  gain  their 
advantage  for  recall  by  the  removal  or 
avoidance  of  some  inhibiting  factor  rather 
than  by  the  introduction  of  a  special  rein- 
forcing agent. 

CAUSE    OF    FORGETTING 

It  was  once  thought  that  forgetting  is 
due  merely  to  the  lapse  of  time,  that  an 
impression  made  on  nervous  tissue  would 
naturally  fade  out.  There  is  now  consider- 
able evidence  to  show  that  this  simple  ex- 
planation is  inadequate.  Both  laboratory 
experiments  and  common  sense  support 
the  view  that  the  rate  of  forgetting  during 
a  time  interval  must  be  dependent  upon 
w^hat  is  going  on  during  that  time  rather 
than  upon  time  itself. 

This  conclusion  receives  supjjort  from 
the  fact  that  retention  during  active  wak- 
ing hours  is  poorer  than  retention  during 
sleep.  Ordinarily,  on  waking  up  we  can 
recall  what  we  did   before  retiring  better 


Forgefting  and  Reiroactive  Inhibition 


173 


than  wc  can  recall  in  the  cvciiin;^  what  wc 
did  that  morning. 

The  results  of  an  interesting  laboratory 
exjaeriment  on  this  topic  are  shown  in  Fig. 
69.  Two  subjects  were  tested  after  varying 
amounts  of  sleep,  and  again  after  varying 


10 


7 
6 

m 

■a 
s  5 

>, 

CO 

4 
3 
2 
1 
0 


V 

\ 

.^'' 

leep 

\ 



— --- 

f- 



-zzi 

\ 

\  \ 

k^ 

' 

""x^ 

7^ 

^^ 

'-Wak 

ng-^ 

^^ 

::;; 

'-— 

^ 

4 
Hours 


this  study  concluded  that  "forgetting  is 
not  so  much  a  matter  of  the  decay  of  old 
impressions  and  associations  as  it  is  a  mat- 
ter of  interference  or  obliteration  of  the 
old  by  the  new."  The  old  impressions  fade 
because  they  are  blotted  out  by  the  new- 
impressions  of  an  active  waking  life. 

Retroactive   Inhibition 

Considerable  research  has  been  devou-d 
to  finding  out  more  about  this  problem  ol 
how  intervening  activities  affect  retention. 
Usually  it  is  found  that  learning  another 
sample  of  the  same  material  during  the  in- 
terval between  the  end  of  practice  and  the 
measurement  of  retention  produces  a  decre- 
ment in  retention.  Such  interference  is 
called  reiroactive  inhibition. 

The  experimental  procedure  employed 
in  studying  retroactive  inhibition  is  of  the 
general  form  shown  in  Table  X,  where  the 

TABLE  X 

Experimental    Procedure    for    SruD-iTNG    Retro- 
active Inhibition 


FIGURE    69.       FORGETTING    AS    A    FUNCTION    OF 
RETROACTIVE    INHIBITION 

Two  subjects  learned  10  nonsense  syllables.  The 
graphs  show  tor  each  subject  the  number  of  syl- 
lables recalled  after  1,  2,  4  and  8  hours  when  the 
subjects  remained  awake,  and  when  they  went  to 
sleep.  Forgetting  is  less  during  sleep  and  almost 
nonexistent  when  sleep  has  become  sound  2  hours 
after  learning.  [Adapted  from  J.  G.  Jenkins  and 
K.  M.  Dallenbach,  Amer.  J.  Psychol.,  1924,  35,  610.] 

amounts  of  interpolated  work.    The  curves 


Condi - 

Original 

Interpolated 

lion 

Aclivily 

Activity 

Final  Test 

(1)  Rest 

Learn  (.4 ) 

Rest 

Measure  retention  of  (.-I) 

(2)  Work 

Learn  (.-1) 

Learn  (B) 

Measure  retention  of  (.4 ) 

letters  A  and  B  stand  for  two  different 
learning  materials.  The  difference  between 
retention  under  these  two  conditions— 
(1)  rest  and  (2)  work— is  the  gross  amount 
of  inhibition. 

If  a  subject  recalls  ten  words  of  list  A 
after  rest  and  onlv  six  words  of  A  after  the 
work  of  learning  B,  he  shows  a  gross  inter- 
ference effect  of  four  words  and  a  relati\e 
for  the  subjects  when  they  remained  awake  interference  of  forty  per  cent  owing  to  the 
fall  with  negative  acceleration  in  a  manner  interpolated  acti^itv  B.  The  two  condi- 
not  unlike  the  forgetting  curve  obtained  by  jions  must  be  arranged  so  that  they  differ 
Ebbinghaus  (Fig.  63).  The  curves  for  the  importantly  only  with  respect  to  the  inter- 
subjects  tested  after  various  amounts  of  polated  activity  (rest  or  learning)  between 
sleep  fall  less  rapidly  during  the  first  two  the  original  learning  and  the  measurement 
hours,  and  then  not  at  all.    The  authors  of      of  its  retention. 


174 


Retention  and  Transfer  of  Learning 


The  experimentally  obtained  decrements 
from  interpolated  learning  vary  in  amount 
from  nearly  zero  to  almost  one  hundred  per 
cent.  The  amoimts  which  appear  are  a 
function  of  several  conditions.  (1)  Over  a 
considerable  range  of  similarity,  degree  of 
inhibition  varies  directly  with  the  degree 
of  similarity  between  the  orginal  and  the 
interpolated  activities.  "When,  for  example, 
the  original  material  consists  of  lists  of  ad- 
jectives and  the  interpolated  material  of 
lists  of  synonyms  of  these  adjectives,  the 
amount  of  inhibition  is  maximal  and  de- 
creases when  antonyms,  unrelated  ad- 
jectives, nonsense  syllables  and  three-place 
numbers  are  interpolated.  (2)  Meaningful 
material  is  less  susceptible  to  retroactive 
inhibition  than  unrelated  disconnected  ma- 
terial. (3)  The  longer  the  material  and  the 
more  difficult  to  learn,  the  less  susceptible 
it  is  to  inhibition.  (4)  The  amount  of  prac- 
tice with  the  original  and  interpolated  ma- 
terials affects  the  amount  of  inhibition.  If 
the  learning  of  the  interpolated  activity  is 
held  constant,  inhibition  decreases  with  in- 
creased learning  of  the  original  activity. 
When,  on  the  other  hand,  the  degree  of 
original  learning  is  kept  constant,  inhibi- 
tion increases  at  first  with  degree  of  inter- 
polated learning.  As  complete  mastery  is 
approached,  however,  additional  incre- 
ments of  interpolated  learning  cease  to  in- 
crease the  amount  of  inhibition  and  may 
finally  even  decrease  it. 

Alteration  of  Stimulating  Conditions 

Retroactive  inhibition  brought  about  by 
the  interpolation  of  new  learning  accounts 
for  a  large  share  of  forgetting,  but  another 
important  factor  is  the  alteration  of  the 
stimulating  conditions  between  the  time  of 
learning  and  the  time  of  the  measurement 
of  retention.  Forgetting  will  occur  be- 
cause some  of  the  stimuli  present  during 


the  original  learning  arc  missing  during 
recall,  or  it  will  occur  when  ne^v  stimuli 
are  present  which  evoke  competing  re- 
sponses sufficiently  strong  to  block  the  orig- 
inally learned  ones.  These  stimuli  arc  both 
external  (like  the  furniture  in  the  room, 
the  ap23aratus,  the  experimenter)  and  in- 
ternal (like  sensations  resulting  from  pos- 
ture, responses  made  during  learning).  Re- 
call may  be  reduced  merely  because  the 
learning  has  taken  place  in  one  classroom, 
whereas  the  testing  of  retention  is  con- 
ducted in  a  different  room. 

Similarly,  when  words  are  learned  with 
one  color  of  backgiound,  recall  is  reduced 
when  the  color  is  changed.  A  language 
learned  in  one  setting  may  be  poorly  re- 
tained in  a  different  setting.  One  person, 
for  example,  lived  for  several  years  in 
China  and  acquired  considerable  fluency  in 
Chinese.  Upon  his  return  to  the  United 
States  for  a  couple  of  years'  vacation,  he 
fotmd  that  by  the  end  of  the  time  his  abil- 
ity to  speak  and  understand  Chinese  had 
practically  disappeared.  Upon  his  return 
to  China,  however,  he  was  astonished  to 
discover  that  he  was  again  able  to  speak  the 
language  fluently.  This  is  a  dramatic  ex- 
ample of  the  familiar  phenomenon  of  be- 
ing unable  to  recall  material  in  a  changed 
context,  as  when  we  are  not  able  to  remem- 
ber the  name  of  a  person  who  is  met  in  a 
new  environment,  although  his  name 
comes  readilv  enough  in  the  usual  environ- 
ment. 

Change  of  Set 

It  is  probable,  although  the  experimen- 
tal evidence  in  support  of  it  is  not  yet 
conclusive,  that  forgetting  also  depends 
upon  our  set.  That  interest  or  set  in  a 
given  direction  has  a  selective  influence 
on  recall  is  well  known;  if  the  set  is  in 
an    incorrect    direction,    recall    may    fail. 


Forgetting  and  Unlearning 


175 


even  though  with  a  correct  set  it  may  occur. 
Thus,  it  in  seeking  to  recall  a  name  we  in- 
sist incorrectly  that  tJie  name  is  Scotch,  the 
search  may  be  confined  to  Scotch  names  lo 
the  neglect  of  others,  and  it  will  seem  that 
the  name  has  been  forgotten.  When  the 
correct  set  is  established,  the  name  may  be 
(jiiickly  recalled. 

There  is  no  lack  of  evidence  that  set 
helps  recall.  In  the  reaction  exjxriment 
we  rcmemlier  lo  press  the  key  when  we  sec 
the  gieen  light,  provided  we  are  set  to  make 
this  reaction.  We  start  to  the  theater  at 
eight  o'clock  because  we  perceive  the  lime 
and  a  set— a  special  set  lor  this  particular 
evening— operates.  Posthypnotic  sugges- 
tion also  shows  how  set  affects  recall.  But, 
if  set  can  make  us  remember  something,  il 
can  also  make  tis  forget  something  else,  be- 
cause the  range  of  human  attention  is  lim- 
ited; and  remembering  one  thing  is  neces- 
sarily, at  least  at  the  moment,  a  forgetting 
of  everything  else. 

The  psychoanalysts  argue  that  forgetting 
may  be  wishful,  that  we  forget  what  we 
piefer  not  to  remember.  Jones  is  talking 
to  a  girl  whom  he  is  courting.  Smith  ap- 
pears. Jones  dislikes  Smith  and  is  jealous 
of  him.  Jones  knows  Smith  vei"y  well,  in- 
deed had  called  him  by  name  only  that 
same  morning.  But  now,  strangely.  Jones 
is  at  a  loss  to  recall  Smith's  name.  Try  as 
he  will  the  name  will  not  come.  He  is  em- 
barrassed and  blushes,  mufFs  the  proper  in- 
troduction to  the  girl.  Was  not  Jones'  ab- 
normal forgetting  an  intentional  one?  Did 
he  not  want  to  forget  Smith's  name,  and 
succeed?  It  is  very  hard  to  arrange  a  test 
case  to  prove  or  disprove  this  kind  of  un- 
conscious intentional  forgetting,  for  there 
are  always  other  possible  ways  in  which  the 
forgetting  might  have  occiured.  It  is. 
moreover,  possible  that  Jones  actually  did 
remember  Smith's  name  momentarily,  put 


it  out  of  his  mind  and  then  forgot  that  he 
remembered.  Nevertheless  such  deter- 
mined forgetting  is  consistent  with  many 
other  phenomena— with  the  facts  of  hvj>- 
nosis  and  with  the  adjustive  mechanisms  of 
the  jjcrsonaliiy  (pjj.  520  f.). 

UNLEARNING 

Forgetting  is  (he  natural  dropping  out  ol 
one  habit  owing  to  interference  by  Jiew 
learning.  On  some  occasions,  how'ever,  we 
wish  to  reduce  the  strength  of  a  habit  de- 
liberately, to  forget  by  design.  This  proc- 
ess of  'unlearning'  assumes  particular  im- 
])ortance  when  bad  habits  need  breaking. 

Overcoming  Fears 

One  of  the  earliest  studies  of  unlearning 
was  an  attempt  to  teach  childien  to  get 
o\er  their  fears  of  being  alone  or  in  a  dark 
room  and  their  fears  of  snakes,  rabbits  and 
other  animals. 

It  is  often  suggested  that  fears  will  dis- 
appear spontaneously  if  no  further  contact 
with  the  feared  object  occurs.  In  this  ex- 
periment no  diminution  in  the  strength  of 
fear  occurred  by  simply  not  exercising  the 
fear.  A'erbal  appeal,  in  which  the  experi- 
menter talked  about  the  feared  object,  con- 
necting it  with  pleasant  experiences,  was 
likewise  quite  ineffective. 

The  method  of  'negative  adaptation'  was 
also  tried,  a  method  in  which  the  child  was 
exposed  to  the  feared  object  repetiti\ely. 
In  one  case  this  procedure  led  to  consider- 
able improvement,  but  in  other  cases  the 
children  actually  became  more  frightened. 
Ridicule  of  tlie  fear  caused  the  childien  to 
hide  or  repress  their  fear  without  actuallv 
feeling  less  afraid. 

Under  certain  conditions  distraction  was 
effective.  When  tovs  and  plavthings  which 
the    tliild    wanted    ^\cre    placed    near    ihc 


176 


Retention  and  Transfer  of  Learning 


frightful  animal  the  child  was,  in  some 
cases,  so  eager  to  get  the  toys  that  he  would 
ignore  the  animal.  But  this  method  re- 
quires the  constant  presence  of  an  adult  to 
arrange  the  distractions,  and  the  effects 
seemed  temporary. 

The  two  ways  which  -were  found  most 
effective  in  overcoming  the  children's  fears 
were  (1)  reconditioning  and  (2)  social  imi- 
tation. 

In  the  first  method,  direct  conditioning 
was  used  to  associate  the  feared  object  with 
a  stimulus  capable  of  arousing  positive  re- 
actions of  acceptance  and  pleasantness. 
For  example,  when  hungry,  a  child  was 
placed  in  a  high  chair  and  given  something 
to  eat.  Then  the  feared  object  was  brought 
in  and  placed  some  distance  away.  Grad- 
ually the  object  was  moved  closer  and 
closer  to  the  child  as  he  ate.  In  this  man- 
ner tolerance  would  be  giadually  built  up 
until  the  child  became  indifferent  to  the 
feared  object  and  in  some  cases  finally  re- 
sponded positively  to  the  object  with  ac- 
ceptance and  interest.  That  is  recoJidi- 
tioning.  This  method  must,  however,  be 
very  carefully  applied.  If  the  child  fears 
the  object  intensely  and  the  object  is  intro- 
duced too  rapidly,  the  treatment  may 
'boomerang,'  so  that  the  child  learns  to  be 
afraid  of  eating  instead  of  learning  to  like 
tlie  rabbit  or  snake  or  whatever  the  feared 
object  is. 

The  method  of  reconditioning  was  used 
by  the  British  during  the  Second  World 
War  as  their  'battle  conditioning.'  The 
training  was  directed  at  reducing  soldiers' 
initial  fear  of  artillery.  The  British  used 
the  method  of  gradual  increase  in  exposure, 
starting  with  the  discharge  of  a  gun  at  a 
great  distance  from  the  training  ground, 
and  then  each  day  bringing  discharges  of 


ammunition  closer  and  closer,  luitil  the 
soldiers  could  at  least  tolerate  quite  intense 
artillery  fire  without  signs  of  fear. 

The  method  of  social  imilation  is  to 
allow  the  children  to  participate  in  the 
activity  of  other  children  who  react  to  the 
critical  object  without  fear.  When  the  so- 
cial group  in  which  the  child  is  placed  has 
great  prestige  for  the  child,  he  behaves  the 
way  the  group  bcha\es.  When  the  other 
children  approach  the  object  without  fear, 
the  child  who  was  afraid  accepts  the  sug- 
gestion from  the  others  and  loses  his  fear. 

Breaking  Habits 

A  novel  method  of  breaking  habits  has 
been  described  by  Knight  Dunlap.  In  his 
procedure  the  individual  is  taught  to  prac- 
tice the  very  error  he  wishes  to  eliminate. 
For  example,  Dunlap  had  the  'bad'  habit 
of  typing  "h  t  e"  for  "t  h  e."  By  deliber- 
ately practicing  the  writing  of  "h  t  e"  he 
became  more  fully  aware  of  his  move- 
ments, brought  the  misspelling  under  con- 
trol and  thus  broke  the  habit.  If  we  are 
not  fully  aware  of  the  undesirable  move- 
ments we  are  making  it  is  hard  to  stop 
making  them.  Stuttering,  nail  biting  and 
other  undesirable  habits  have  sometimes 
been  curbed  by  practicing  them  with  the 
set  to  break  them.  This  method  may  at 
first  glance  appear  contradictory  to  the 
principle  learned  earlier  that  practice  fix- 
ates a  habit  (law  of  frequency,  p.  153).  We 
shall  realize,  however,  that  deliberately 
practicing  a  habit  we  know  to  be  bad  is 
punishing  rather  than  rewarding,  and 
lience  would  be  expected  to  result  in  ex- 
tinction of  the  habit  (law  of  effect,  p.  147). 
The  important  factor  in  Dunlap's  method 
is,  however,  the  having  of  insight  into  the 
nature  of  the  habit. 

Another  effective  procediue  is  to  recon- 


Unlearning  and  Transfer  of  Learning 


]77 


dition  the  subject  by  attaching  new  but  in- 
compatible responses  to  the  old  stimulus 
which  originally  produced  the  undesired 
response.  We  are  told  to  "Reach  for  a 
Lucky  instead  of  a  sweet."  We  can  break 
the  habit  of  eating  too  much  candy  if  we 
can  substitute  for  candy  eating  the  incom- 
patible response  of  cigarette  smoking  when- 
ever we  have  a  craving  for  candy.  After 
that  we  can  break  the  smoking  habit  with 
chewing  gum. 

Punishment  is  sometimes  useful  in  break- 
ing up  habits,  but  it  must  be  carefully 
timed.  If  applied  too  long  after  the  act 
which  is  to  be  corrected,  the  unpleasant- 
ness is  likely  to  be  associated  with  the 
events  just  preceding  the  punishment 
rather  than  with  the  act  to  be  extinguished. 
(See  p.  148.)  Furthermore,  punishment  is 
unreliable  in  its  effects,  and  particularly  so 
with  children.  It  is  likely  either  not  to  be 
severe  enough  or  distracting  enough  really 
to  break  up  the  habit.  Instead  it  may  re- 
inforce the  habit  by  making  its  perform- 
ance exciting.  Excitement  usually  facili- 
tates the  learning  of  habits.  In  this  way 
the  'naughty'  behavior  of  children  may  be 
encouraged  by  mild  punishment  or  by 
moderate  parental  opposition.  Once  again 
we  may  note  that  reward  is  better  than 
punishment,  praise  is  better  than  reproof, 
for  the  facilitation  of  training. 

TRANSFER    OF    LEARNING 

It  is  seldom  that  the  situation  in  which 
we  learn  is  identical  with  the  situation  in 
which  we  use  the  learning.  For  example, 
we  learn  arithmetic  at  school  and  use  it  in 
the  grocery  store.  To  what  extent  does 
learning  transfer  from  one  situation  to  an- 
other? In  a  common-sense  way  we  know 
that  old   learninsf  is   useful   in   new  situa- 


tions. A  man  who  has  learned  to  drive  one 
car  can  drive  a  similar  car  almost  a.s  well 
without  additional  practice.  That  we  call 
positive  transfer.  On  the  cHher  hand,  pre- 
vicHis  learning  often  interferes  with  new 
learning.  If,  for  example,  a  man  learns  to 
type  with  a  special  kind  of  keybcjard,  he 
has  a  much  more  difficult  time  learning  to 
use  a  standard  keyboard  than  if  he  had 
started  with  the  standard  one  in  the  first 
place.  It  is  for  this  same  reason  that  ini- 
tial learning  with  the  'hunt-and-peck' 
method  of  typing  may  make  it  actually 
harder  to  learn  with  the  touch  system. 
When  learning  one  task  makes  learning  a 
second  task  harder,  we  speak  of  negatiiH' 
transfer.  Would  you  expect  that  it  would 
be  more  difficult,  less  difficult  or  about 
equally  difficult  to  teach  golf  to  a  person 
who  was  expert  at  tennis  than  to  teach 
golf  to  an  equally  competent  person  who 
had  not  learned  tennis?  That  is  the  kind 
of  problem  with  which  we  are  concerned 
in  studies  on  the  transfer  of  training. 

Formal  Discipline 

Not  so  long  ago  educators  had  a  clear-cut 
answer  to  these  problems.  They  believed 
that  the  mind  was  composed  of  a  number  of 
faculties  which  could  be  improved  through 
exercise,  just  as  a  muscle  is  strengthened 
by  use.  Consecjuently  thev  believed  that 
certain  subjects  should  be  taught  in  school 
primarily  for  their  disciplinary  value,  espe- 
cially Latin,  Greek  and  mathematics.  This 
theory  is  now  called  the  doctrine  of  formal 
discipline,  the  theory  that  what  is  hard  is 
good  for  us  because  it  makes  us  suong. 
Such  a  statement  carries  ■with  it  a  specious 
tone  of  morality  of  which  we  must  beware. 
Learning  higher  mathematics  A\ould  bene- 
fit an  astronomer  but  would  scarcely  im- 
prove the  art  of  a  glamour  girl.     Transfer 


178 


Retention  and  Transfer  of  Learning 


niav  be  positive  or  missing  or  even  nega- 
tive. Learning  is  not  good  just  because  it 
is  hard. 

The  first  experimental  attack  on  this 
problem  was  made  by  the  American  psy- 
chologist, William  James.  He  determined 
to  find  out  whether  practicing  the  memori- 
zation of  poetry  really  improved  memoriz- 
ing ability.  First  he  learned  158  lines  of 
\'ictor  Hugo's  Satyr  and  recorded  his  time. 
Then  he  spent  more  than  a  month  commit- 
ting to  memory  Milton's  Paradise  Lost. 
When  he  had  finished  with  it  he  returned 
to  the  Satyr  and  memorized  another  158 
lines.  He  found  that  these  158  lines  actu- 
ally took  longer  than  the  first  158,  and  he 
concluded  that  all  the  work  on  Paradise 
Lost  had  not  improved  his  ability  in  memo- 
1  izing. 

James'  study  was  not  ideally  set  up  as  an 
experiment  and  was  therefore  not  conclu- 
sive, although  it  did  set  other  investigators 
to  studying  the  problem.  We  question 
whether  James'  learning  was  representa- 
tive of  all  learning.  We  do  not  know 
that  the  first  158  lines  were  equal  in  diffi- 
culty to  the  second.  We  wonder  whether 
James'  physical  condition  was  the  same  at 
the  two  times.  (He  himself  says  he  was 
fagged  out  by  other  work  at  the  time  of 
the  second  learning.)  We  note  that  the 
effect  of  practice  itself  was  not  separated 
from  transfer  of  training  proper. 

A  Transfer  Experiment 

Later  experiments  have  corrected  these 
procedural  defects.  A  large  number  of 
subjects  has  been  used.  To  rule  out  prac- 
tice effects,  two  equivalent  groups  have 
been  employed,  of  which  one  was  given  the 
practice  and  the  other  (the  control  group) 
was  not  given  any  practice.  This  gives  the 
following  experimental  design. 


Experimental  Group 

(1)  Given  test  on  activity  {A) 

(2)  Then  given  training  on  activity  (fl) 
{Tj  Then  retested  on  activity  {A) 

Control  Group 

(1)  Given  test  on  activity  {A) 

(2)  Then  given  no  further  training 

(3)  Then  retested  on  activity  {A) 

The  amoimt  of  transfer— the  effect  of 
learning  [B)  on  skill  in  {A)—h  measured  by 
the  amount  of  improvement— (3)  minus  (I) 
—made  by  the  experimental  group  as  com- 
pared with  the  improvement  made  by  the 
control  group  which  did  not  get  any  prac- 
tice.    (See  Table  X,  p.  173.) 

These  later  experiments  have  greatly 
extended  our  knowledge  of  the  conditions 
imder  which  transfer  of  training  occurs. 
Several  types  of  transfer  can  be  distin- 
guished. 

Transfer  within 
the  Same  Class 

Practice  upon  one  sample  of  a  given  kind 
of  material— mazes,  word  lists,  poetry,  etc.— 
usually  affects  favorably  the  learning  of 
other  samples  of  the  same  kind  of  material. 

TABLE  XI 

Positive  Transfer 

Effect   of   Learning    Maze   A    upon    Si'bseqtient 
Learning  of  Maze  B. 

The  number  of  trials,  the  number  of  errors  and  the 
time  are  all  averaged.  The  time  is  in  seconds.  [From 
L.  W.  Webb,  Psychol.  Monogr.,  1917,  24,  No.  104,  18.) 

Measure  of  Performance  in  Maze  B 

Trials  Errors  Time 

Mean  A.D.*  Mean     A.D.      Mean       A.D. 

(1)  Maze  B  (con- 

trol) 33.6     14.3     285.2     205.4     1166.0     514.2 

(2)  Maze  B  preceded 

by  Maze  A 

(experimental)     10.8      5.9      32.4       13.7       149.4       54.7 
Number  of  units 
saved: 
(1)  minus  (2)       22.8  252.8  1016.6 


*  Average  deviation  from  ihc  mean 


Transfer  of  Learn'mg 


A  sample  of  such  positive  liaiislt  r  is  shown 
in  Table  XI,  where  the  learning  ol  one 
maze  is  seen  to  reduce  the  time  required  to 
learn  a  second  maze.  Under  certain  condi- 
tions, however,  negative  instead  ot  positive 
transfer  may  be  found. 

Bilateral  Transfer 

liilateral  tiansfcr,  or  cross-education,  an- 
oilier  form  of  the  positive  transfer  of  learn- 
ing, is  the  facilitation  of  the  learning  of  re- 
sponses on  one  side  of  the  body  by  the  pre- 
vious learning  of  responses  made  on  the 
other  side.  When  we  practice  a  task  with 
the  left  hand  for  a  number  of  trials,  we  usu- 
ally find  that  we  can  learn  to  do  the  same 
task  with  the  right  hand  in  many  fewer 
trials  than  if  we  had  not  initially  practiced 
with  the  left  hand. 

Bilateral  transfer  has  been  found  in  a 
large  number  of  acts,  among  them  mirror 
drawing  (tracing  a  diagram  when  we  can 
see  only  it  and  our  pencil  reflected  in  a 
mirror),  rapid  tapping  on  a  tapping  board, 
tossing  a  ball  at  a  target,  finding  and  learn- 
ing the  correct  path  through  a  maze.  The 
amount  of  transfer  varies  from  a  small 
amount  to  as  much  as  fifty  per  cent.  Tact- 
ual discrimination  of  the  Braille  alphabet 
for  the  blind  by  subjects  with  normal  vision 
has  been  found  to  transfer  completely  from 
one  hand  to  the  other.  That  is  a  positive 
transfer  of  one  hundred  per  cent.  Con- 
ditioned responses  established  on  one  side 
of  the  body  have  been  found  to  appear  on 
the  other  side  with  a  consistency  almost 
equal  to  that  shown  on  the  side  used  in 
training. 

Bilateral  transfer  is  common  enough 
when  great  motor  precision  is  not  required, 
as  in  learning  to  shift  automobile  gears, 
to  manipulate  the  knobs  on  a  radio,  to 
handle  a  telephone  transfer  readily  from 
one  hand   to   the  other.     Such   transfer   is 


seldom  ((jiiipletc  at  the  bcgiruii 

learning  on   the  new  side  is  so 

it  very  (juickly  reaches  the  level 

an(e  which   the   first-trained   siuc  i^v,_. 

long  practice  to  attain. 

Transfer  from  One 
Class  to  Another 

The  next  qucsiion,  the  one  which  is  Ijasic 
in  the  problem  (jf  jonnal  disiipUne,  is 
whether  practice  upon  one  or  more  samples 
of  one  class  will  facilitate  the  learning  of 
samples  of  a  different  class.  Will  practice 
at  maze  learning  facilitate  card  sorting? 
Will  practice  at  learning  nonsense  syllables 
transfer  to  learning  poetry?  Will  studying 
Latin  help  in  writing  better  English?  AVill 
it  help  in  learning  calculus?  AVill  it  help  in 
learning  golf?  Would  the  formal  discipline 
in  learning  to  make  discriminations  help  a 
rat  to  find  the  goals  in  mazes? 

One  of  the  most  important  studies  of 
transfer  of  academic  training  was  made 
by  Thorndike.  He  studied  the  eftect  of  a 
year's  work  in  such  high  school  studies  as 
Latin,  mathematics  and  history.  All  stu- 
dents used  in  his  study  were  first  given  a 
test  of  "selective  and  relational  thinking." 
An  equivalent  form  of  the  same  test  was 
given  again  at  the  end  of  the  vear.  During 
the  year  some  of  these  students  took  a  pro- 
gram which  included  Latin,  mathematics, 
history  and  other  subjects,  while  others 
instead  took  subjects  like  shop  work  and 
bookkeeping.  Thorndike  then  compared 
the  relative  effects  of  different  school  sub- 
jects on  performance  in  the  test.  The  ef- 
fects were  so  small  that  Thorndike  con- 
cluded that  there  is  no  marked  balance  in 
favor  of  one  rather  than  another  school  sub- 
ject in  its  effect  on  "selective  and  relational 
thinking." 

Numerous  otlier  experiments  ha\  e  tended 
to   confirm   these   findings.      The   evidence 


180 


Reiention  and  Transfer  of  Learning 


indicates  that  the  most  effective  way  to 
achieve  a  desired  educational  objective  is 
to  train  directly  for  it  rather  than  to  hope 
to  attain  it  as  a  by-product  of  training  in 
other  subjects  which  have  been  taught  for 
their  disciplinary  value.  These  results  sup- 
port the  trend  in  modern  education  to 
teach  things  for  their  own  values— social, 
esthetic,  recreational  or  utilitarian,  as  the 
case  mav  be— rather  than  for  a  general 
training  of  the  mind,  a  kind  of  training 
which  is  not  known  to  be  possible. 

On  the  other  hand,  there  are  all  sorts  of 
wavs  in  whicJi  having  learned  one  thing  may 
help  a  student  to  learn  another.  Learn- 
ing Latin  may  help  the  formation  of  the 
habit  of  sitting  still  and  paying  attention 
to  the  contents  of  books,  so  that  the  Latin 
does  make  the  learning  of  mathematics 
easier.  If  a  student  ^vith  a  poor  scholastic 
record  should  do  brilliantly  in  Latin,  be- 
cause it  is  easy  for  him,  his  pride  in  his 
success  might  motivate  him  to  work  harder 
with  his  algebra,  which  is  hard  for  him, 
and  thus  unexpectedly  to  do  well  in  al- 
gebra. For  studying  one  thing  he  may  have 
to  hunt  up  a  quiet  place  so  that  he  can 
concentrate  on  his  work.  Then  that  place 
Avill  remain  available  for  studying  other 
things.  So  situations  transfer,  fundamental 
habits  of  study  transfer,  motivation  and 
pride  transfer  from  one  study  to  another. 
Formal  discipline  often,  not  always,  has 
positive  transfer  effects  of  these  kinds.  Yet 
even   then   formal   discipline   is   inefficient. 

Positive  versus  Negative  Transfer 

\\t  have  seen  that  while  positive  trans- 
fer is  ^ery  common,  negative  transfer  also 
occurs.  AVhat  determines  whether  the 
transfer  is  positive  or  negative?  Research 
indicates  that  the  most  important  fac- 
tor is  whether  the  new  learning  involves 
making  an  old  response  to  a  new  stimulus 


or  making  a  new  response  to  an  old  stimu- 
lus. In  the  former  case,  where  we  are  learn- 
ing to  make  an  old  response  to  a  new  stimu- 
lus, positive  transfer  is  the  rule.  We  shall 
see  that  this  phenomenon  is  similar  to  that 
of  generalization  in  conditioning  (p.  141). 
The  general  principle  is  that  each  new 
stimulus  siluation  tends  to  elicit  the  re- 
sponse which  has  been  connected  u'itli 
similar  stimulus  conditions  in  the  past. 

On  the  other  hand,  when  a  new  response 
must  be  made  to  an  old  stimulus,  transfer 
is  usually  negative.  This  result  has  been 
generalized  as  the  law  of  associative  inhibi- 
tion, which  states  that  luhen  any  tivo  items, 
like  a  stimulus  A  and  a  response  B,  have 
been  associated,  it  is  more  difficult  to  form 
an  association  betu'een  the  initial  item,  A, 
and  a  third  item,  K.  If,  for  example,  you 
are  accustomed  to  carry  your  cigarettes  in 
your  right  pocket  but  shift  them  over  to  the 
left,  you  will  observe  numerous  errors  and 
false  movements  in  learning  to  reach  auto- 
matically to  the  new  location.  The  stimu- 
lus, desire  for  a  smoke,  which  has  been 
connected  with  the  response  reach-to-the- 
right-pocket,  must  now  become  connected 
with  the  response  reach-to-the-left-pocket. 
The  formation  of  this  new  association  is 
interfered  with  in  its  early  stages  by  the 
appearance  of  the  old  response,  now  wrong, 
or  by  delay  and  fumbling. 

In  general,  it  is  clear  why  this  difference 
between  positive  and  negative  transfer  oc- 
ciu's  in  these  cases.  If  we  have  learned 
the  sequence  stimulus-/l-to-response-fi,  and 
want  then  to  learn  the  sequence  stimulus- 
/-to-response-B,  we  have  positive  transfer. 
AVhen  /  occurs,  A  is  not  there  to  interfere, 
and  B  is  attached  to  /  easily  because  we  got 
familiar  with  B  and  made  it  more  meaning- 
ful when  we  were  learning  A-to-B.  On  the 
other  hand,  when  we  wish  to  substitute  for 
A-lo-B  the  new  association  ,^-to-A',  we  find 


Efficient  Study 


181 


Ji  iiKikinsj;  I  rouble  lor  A'.  VVIuri  //  (nciirs, 
B  is  likely  to  appear  and  prevent  or  dehiy 
the  appearance  ol  A's  new  partner,  A'.  It 
is  this  conflict  that  makes  (he  transler  nega- 
tive. 

EFFICIENT    STUDY 

All  the  general  principles  that  apply  to 
learning  and  retention  are  applicable  to 
the  student's  daily  work  and  study  habits. 
We  shall,  therefore,  consider  here  use  of 
these  basic  principles  in  laying  down  rules 
lor  the  improvement  of  efficiency  in  study- 
ing. 

Motivation 

One  well-known  textbook  advises  stu- 
dents: "Be  motivated!"  Although  we  can- 
not, of  course,  turn  motivation  on  and  off 
on  demand  as  this  advice  implies,  the  im- 
portance of  motivation  in  learning  cannot 
be  overemphasized.  The  best  motive  for 
learning  is  a  strong  desire  to  achieve  cer- 
tain results  by  learning.  When  you  want 
to  drive  the  family  car,  you  don't  have  to 
be  bribed  to  take  driving  lessons.  Are  you 
equally  interested  in  the  outcome  of  your 
school  learning?  It  is  worth  while  to  re- 
view every  now  and  then  your  ultimate 
goals  to  remind  yourself  of  why  you  are 
studying  at  all.  But  ultimate  goals  are 
often  too  remote  to  provide  effective  moti- 
vation. We  saw  in  the  preceding  chapter 
(p.  147)  that  the  more  immediate  the  re- 
ward, the  greater  the  learning.  One  way 
of  taking  advantage  of  this  fact  is  to  set 
for  yourself  intermediate  goals  short  of  the 
final  one. 

These  subgoals  enable  you  to  see  how 
you  are  doing  and  thus  to  guide  your  fu- 
ture improvement.  Try  to  make  the  goals 
as  concrete  as  possible  and  keep  accurate 
tab  of  your  progress  in  achieving  them. 
Some  students  find  it  helpful  to  make  up  a 


(liart  in  wliifli  I  hey  record  iluir  j>rogrcss 
(such  as  liow  many  foreign  words  they  arc- 
able  to  translate,  or  the  number  of  errors 
I  hey  make  on  successive  examinations). 
J  he  United  States  Army  found  this  tech- 
nique extremely  helpful  in  improving  per- 
formance. In  some  cases  men  had  been 
instructed  in  learning  to  operate  complex 
weapons  merely  by  being  told  to  "practice 
for  a  while."  When  a  system  of  informing 
them  exactly  how  well  they  did  on  each 
trial  was  introduced,  their  performance 
improved  rapidly.  Plotting  your  own  per- 
formance as  you  go  along  is  a  way  of  com- 
peting with  yourself.  Another  good  mo- 
tivation booster  is  to  compete  with  others 
in  your  class  or  with  your  roommate's  per- 
formance. 

Although  it  is  helpful  to  maintain  a  high 
level  of  motivation,  you  should  not  attempt 
tasks  beyond  your  ability.  You  must  set 
your  level  of  aspiration  at  a  level  commen- 
surate with  your  ability.  Otherwise  you 
will  experience  constant  frustration,  and 
the  consequent  absence  of  reward  will  re- 
duce the  efficiency  of  your  learning. 

Planning 

Even  with  the  best  of  motivation,  studv 
cannot  be  efficient  unless  it  is  carefulh 
planned.  Most  students  find  it  helpful  to 
draw  up  a  schedule  in  which  are  listed  all 
their  daily  activities  with  a  specific  time 
reserved  for  each  type  of  activity.  Such  a 
schedule,  to  be  realistic,  must  include  time 
for  recreation  and  even  for  '^vasting.' 
Scheduling  helps  to  separate  work  sharply 
from  play,  inaeasing  the  efficiency  of  each. 
A  loose  mixture  of  'fiddling  around'  and 
work  is  likely  to  be  inefficient  for  work  and 
not  much  fun  as  play.  To  have  dutv 
watching  while  you  play  cuts  down  the  joy 
of  playing. 

In  planning  a  work  schedule  of  diis  sort. 


182 


Retention  and  Transfer  of  Learning 


it  is  well  to  bear  in  mind  the  facts  about 
distribution  of  practice  (pp.  156  f.).  You 
should  determine  for  each  topic  the  opti- 
mum length  for  your  uninterrupted  study. 
You  have  to  hit  near  the  happy  medium 
between  bareh  getting  warmed  up  before 
you  shift  to  the  next  topic  and  keeping  on 
with  interference,  boredom  and  fatigue 
working  against  you. 

In  arranging  a  program,  a\oid  'cram- 
ming' just  before  examinations.  Hurriedly 
learned  is  hurriedly  forgotten.  Careful  ini- 
tial learning  with  periodic  review  insures 
the  best  retention. 

In  laving  out  your  plans  it  is  well  for 
you  to  provide  for  a  constant  place  in 
which  to  study.  Such  a  place  will  come  to 
provide  cues  for  study  and  will  lack  the 
distraction  which  a  changing  environment 
is  likely  to  have  upon  performance.  Even 
if  the  place  is  noisy,  it  is  better  to  have  a 
constant  noise  than  a  variable,  unpredict- 
able, imperfect  quiet.  You  can  get  accus- 
tomed to  the  same  old  noise,  and  then  it 
will  not  distract  you,  may,  in  fact,  even 
spur  you  on  to  work  a  little  harder,  in  the 
way  that  the  continuous  jumble  of  a  radio 
can  help  some  students  to  study  better. 

Reading  Habits 

Since  learning  in  college  deals  so  largely 
with  verbal  material,  it  is  extremely  im- 
portant that  the  individual  be  able  to  read 
efficiently.  For  efficiency,  it  is  of  first  im- 
portance that  your  reading  instruments, 
your  eyes,  should  be  up  to  their  peak  per- 
formance. A  check-up  on  your  eyes  by  a 
competent  eye  doctor  wall  guard  you  against 
defects  which  can  be  corrected  by  exercise 
of  the  eyes  or  suitable  glasses.  Headaches 
and  tension  aroimd  the  eyes  are  often  at- 
tributable to  poor  vision.  Also  important 
for  maximal  visual  efficiency  is  adequate 
illumination.    Arrange  for  enough  light  to 


fall  directly  on  the  material  you  are  read- 
ing. (For  the  specification  of  the  best  in- 
tensity and  distribution  of  illinnination, 
see  pages  475-477.) 

Efficient  readers  differ  markedly  from  in- 
efficient in  the  way  they  read.  Study  of 
eve  movements  may  help  you  to  improve 
your  efficiency  in  reading  and  learning.  If 
you  will  take  a  page  of  reading  material 
and  cut  a  small  hole  in  it,  about  the  si/e 
of  a  dime,  and  will  ask  a  friend  of  yours 
to  read  the  page  while  you  watch  his  eyes 
through  the  opening,  you  will  be  able  to 
make  some  interesting  observations.  You 
will  see  that  his  eyes  do  not  move  continu- 
ously along  the  lines  as  he  reads  but  jimip 
a  few  words,  then  pause,  then  jump  again. 
Between  the  end  of  the  last  pause  on  one 
line  and  the  first  on  the  next  there  is  a  long 
sweeping  movement.  During  this  time 
the  eyes  are  not  able  to  see.  At  each  pause, 
or  fixation,  the  reader  takes  in  several 
words.  The  more  words  w^hich  he  can  take 
in  per  fixation,  the  fewer  fixations  he  needs 
and  hence  the  more  rapid  his  reading.  Slow 
readers  not  only  take  in  very  small  nimi- 
bers  of  words  at  a  time  but  often  will  be 
observed  to  go  back  and  reread,  a  shift 
called  regression  in  reading.  Regression, 
of  course,  greatly  reduces  reading  speed. 

Considerable  increase  in  reading  speed 
can  be  achieved  through  practice.  In  one 
experiment  a  poor  reader  was  able  to  re- 
duce his  pauses  from  15.5  to  6.1  by  prac- 
ticing only  twenty  minutes  a  day  for  twenty 
days.  He  Avas  able  to  comprehend  just  as 
much  at  the  increased  speed.  Practice 
should  consist  primarily  of  forcing  yourself 
to  read  as  rapidly  as  you  can  without  sacri- 
ficing the  meaning  of  what  is  being  read. 
All  of  us  can  benefit  by  this  practice,  since 
nearly  everyone  reads  less  rapidly  than  his 
capacity  permits. 

Slow  readers   also   tend   to  vocalize   the 


Efficient  Study 


183 


words  as  ihey  read  them,  often  using  actual 
tongue  and  lip  movements.  This  unneces- 
sary extra  work  lurtlicr  slows  down  read- 
ing s|xc'd.  Silent  reading  increases  read- 
ing speed,  and  with  practice  you  can  learn 
to  read  swiftly  and  silently  without  loss  of 
the  significance  and  meaning  of  the  text. 
One  of  the  most  common  reasons  for  slow 
reading  and  eye  movement  regression  is 
lack  of  adequate  vocabulary.  A  shortage 
of  familiar  words  can  be  readily  overcome 
by  a  systematic  use  of  the  dictionary.  Mak- 
ing a  habit  of  looking  up  in  the  dictionary 
every  word  which  is  unfamiliar  to  you  will 
save  you  time  later,  and,  as  your  vocabulary 
increases,  yoin-  reading  rate  will  also  im- 
prove. 

Meaningfulness 

Learning  the  definition  of  all  imfamiliar 
words  will  also  help  learning  by  increas- 
ing its  meaningfulness.  Another  way  in 
which  we  can  take  advantage  of  this  im- 
portant factor  is  by  getting  a  bird's-eye 
view  of  the  entire  material  to  be  learned 
befoie  concentrating  on  the  individual 
parts  to  be  learned.  Such  a  perspective  in- 
creases interest  in  the  details  and  makes  the 
entire   task   more  significant. 

In  learning  new  material  always  try  to 
relate  it  to  material  you  already  know.  It 
is  much  easier  to  add  a  new  fact  when  you 
already  have  a  background  for  it  than  to 
learn  a  new  isolated  fact  related  to  noth- 
ing else  in  your  repertoire.  Translating  a 
material  into  your  own  words  is  also  help- 
ful in  guaranteeing  that  material  will  be 
meaningful,  as  well  as  in  adding  the  favor- 
able circumstance  of  more  active  participa- 
tion to  the  learning.  When  you  do  not 
jjaraphrase  a  material  as  you  learn  it,  you 
may  find  that  you  have  it  in  fairly  good 
shape  for  verbatim  reproduction  but  that 
you  can  recall  the  words  better  than   the 


sense.  Usually  what  you  want  to  rernembei 
is  the  sense.  C)ne  good  way  to  get  more 
sense  than  words  is  to  study  mateiial  from 
more  than  one  source.  Reading  the  same 
topic  in  several  different  textbooks  will 
give  you  a  better  knowledge  of  the  topic 
than  a  single  coverage,  even  if  the  same 
points  are  covered.  Approaching  the  same 
material  from  different  points  of  view  also 
aids  in  retention.  It  may  seem  confusing 
to  read  two  books  that  appear  to  contradict 
each  other,  but  if  you  put  into  your  learn- 
ing the  activity  necessary  to  resolve  the  con- 
fusion and  make  the  sense  consistent,  vou 
will  know  more  than  you  would  if  you  had 
had  only  a  single  clear  consistent  but  un- 
challenging  book  to  read. 

Active  Participation 

There  are  many  ways  in  which  learning 
can  be  favored  by  making  participaticjii 
more  active.  When  material  is  studieil 
with  the  intent  to  remember,  it  is  better 
retained  than  when  read  without  intent  to 
remember.  Just  studying  with  the  book 
in  front  of  you  never  insures  learning. 
You  have  actively  to  practice  what  you  are 
trying  to  learn.  You  can,  for  instance,  at- 
tempt to  recite  the  material  in  ^\•hate\er 
way  you  wish  to  learn  it,  Avords  or  sense. 
Close  your  book  and  see  how  much  of  the 
material  you  can  recall.  If  aou  are  studv- 
ing  for  quizzes,  think  up  questions  for  voin- 
self  and  undertake  to  answer  them.  Keep 
putting  your  book  down  to  see  how  much 
of  the  material  you  can  recite  after  \ou 
have  read  it. 

Active  participation  in  leaining  also  im- 
plies paying  close  attention  to  the  material 
you  wish  to  acquire.  \'arious  niemoi-y 
systems  attempt  to  guarantee  this  close  at- 
tention by  elaborate  ile\ices.  memory 
'crutches.'  If  you  will  spend  the  same  time 
and  effort  directlv  on  the  material  that  ii 


184 


Retention  and  Transfer  of  Learning 


required  to  learn  the  system,  nou  will  usu- 
ally be  ahead  of  the  game. 

And  do  not  forget  the  importance  of 
overlearning,  if  you  want  the  material  to 
stick.  Never  be  satisfied  with  bare  mastery. 
Alwavs  learn  your  material  well  enough  so 


that  distractions   and   excitement   will   not 
interfere  with  your  recall. 

REFERENCES 

See  the  references  cited  for  learning  at  the  end 
of  Chapter  7,  pp.  165  f. 


CHAPTER 


Recollecting,  Imagining  and  Thinking 


ALL  the  topics  to  be  dealt  with  in  this 
^  chapter  are  frequently  referred  to  by 
the  layman  as  thinking.  When  he  says,  "I 
am  thinking  about  the  time  my  car  skidded 
into  the  ditch,"  he  probably  means  that  he 
is  going  once  more  through  the  experiences 
of  that  accident,  recalling  the  visual  scene 
of  the  road,  the  snow  and  ice,  reproducing 
the  'feel'  of  the  car  as  it  went  out  of  con- 
trol and  re-experiencing  the  fear  which  ac- 
companied the  event.  This  kind  of  'think- 
ing-about'  in  which  we  bring  back  the  past 
and  recognize  it  as  belonging  to  the  past  we 
shall  call  recollecting. 

When  a  person  says  that  he  is  'thinking 
about'  a  plan  for  remodeling  his  house, 
his  activity  is  probably  what  we  shall  call 
imagining.  He  is  creating  new  pictures  or 
scenes  which  are  neither  present  nor  past. 
Sometimes  these  imagined  events  are  re- 
garded as  future,  as  things  which  the  in- 
dividual expects  to  occur.  At  other  times, 
imagining  has  no  definite  reference  to  time 
at  all.  The  imagined  scenes  are  not  past, 
or  present,  or  future;  they  are  simply  un- 
real. 

The  term  thinking  usually  includes  more, 
however,  than  the  'thinking-about'  which 
is  labeled  recollecting  or  imagining.  It  is  a 
complicated  process  and  requires  more  of 
an  introduction  than  recollecting  or  imag- 
ining.    The  kind  of  thinking:  which  leads 


to  the  solution  of  important  problems  ol 
personal  decision,  of  political  theory  or  ol 
science  is  more  than  a  creation  of  pictures 
or  images.  For  the  sake  of  clarity  we  had 
better  use  the  term  thinking  only  when  we 
refer  to  this  more  complicated  activity  with 
recollecting  and  imagining  recognized  as 
important  tools  for  this  kind  of  thinking. 
It  is  easier,  as  a  matter  of  fact,  to  state 
what  is  not  thinking  than  it  is  to  give  a 
clear  and  useful  definition  of  the  term. 
For  the  time  being  we  can  be  content  with 
a  rough  characterization  and  a  few  ex- 
amples. Later  in  the  chapter  we  shall  give 
a  fuller  description. 

Thinking  is  directed  toward  the  solution 
of  a  problem.  It  is  not  automatic.  It  re- 
quires effort.  It  frequently  uses  symbolic 
short  cuts  and  signs.  And  it  takes  us  be- 
\'ond  the  immediate  concrete  situation  by 
the  use  of  concepts.  A  man  regards  his 
thinking  as  successful  when  it  provides 
him  with  ne^\•  knowledge,  with  better  un- 
derstanding of  a  situation,  with  a  decision 
which  he  believes  to  be  correct,  or  ^\hen 
it  leads  to  an  action  which  is  successful 
in  overcoming  the  obstacles  in  his  patli. 

Suppose,  for  example,  that  you  are  told 
that  the  sum  of  the  first  A'  integers  is  equal 
to  A  (A"  +  1)  2  and  that  you  are  unable  to 
understand  why  this  is  true.     Your  search 


for  an  understanding  is  an  example  of  what 

This  chapter  was  prepared  by  T.  A.  Ryan  of  Cornell  University. 

185 


186 


Recollecting,  Imagining  and  Thinking 


we  mean  by  thinking.  It  is  not  thinking 
if  you  are  satisfied  with  the  recollection  that 
vou  once  learned  this  formula  in  an  alge- 
bra class  in  high  school.  It  is  not  thinking 
if  you  have  already  worked  out  an  under- 
standing of  the  relationships  involved,  so 
that  you  simply  recall  the  results  of  your 
earlier  thinking. 

When  you  accept  this  problem  and  there 
is  no  ready-made  answer  available,  you 
start  on  a  course  of  thinking.  The  problem 
engages  your  attention.  You  'work  hard' 
(effort)  trying  to  find  the  point  of  view 
which  will  make  the  relationships  clear. 
\ou  consider  the  various  meanings  which 
may  be  attached  to  numbers  (signs,  sym- 
bols and  concepts).  Your  thinking  ceases 
^vhen  you  believe  that  you  at  last  under- 
stand luhy  the  formula  works  or  when  you 
are  interrupted  by  other  affairs.  It  is  not 
necessary  that  you  arrive  at  a  solution  (to 
say  nothing  of  finding  a  correct  solution) 
in  order  to  call  the  process  thinking,  for  the 
|jrocess  has  its  characteristic  features 
whether  it  is  successful  or  unsuccessful. 
The  applied  psychology  of  thinking  is,  of 
course,  interested  in  the  correctness  of  the 
lesult;  but,  before  we  can  control  thinking 
and  direct  it  toward  correct  solutions,  it  is 
necessary  to  understand  thinking  in  gen- 
cial,  both  correct  and  incorrect. 

.\lthough  all  the  above  characteristics 
appear  typically  in  thinking,  they  also  ap- 
pear separately  in  many  other  kinds  of  ac- 
tivity as  well.  Suppose  we  ask  someone 
to  tell  us  which  of  two  weights  is  heavier. 
We  have  given  him  a  problem,  but  we 
would  not  say  that  his  solution  ordinarily 
requires  thinking.  Similarly  when  we  read 
a  description  of  a  landscape  we  are  dealing 
with  symbols,  but  it  does  not  require  think- 
ing to  understand  the  description  and  to 
translate  it  into  an  imagined  scene. 


RECOLLECTING 

Recollection  is  a  process  by  which  events 
and  situations  from  the  past  are  recreated 
by  the  individual  and  recognized  bv  fiim 
as  comiiig  from  his  past.  It  is  in  the  em- 
phasis on  recognition  that  recollection  dif- 
fers from  recall  as  that  term  is  used  in  the 
more  general  study  of  learning.  The  test 
for  recall  in  an  experiment  upon  memo- 
rizing is  whether  the  individual  is  able  to 
reproduce  the  words  in  the  memorized  list. 
It  is  immaterial  whether  he  remembers  hav- 
ing seen  the  words  before.  In  learning  a 
motor  skill,  recall  is  also  measured  by  the 
accuracy  of  performance.  Recall  may  or 
may  not  involve  recollection.  For  example, 
when  you  multiply  you  are  demonstrating 
recall  of  the  multiplication  table,  but  sel- 
dom do  you  recollect  the  occasion  of  your 
original  learning  of  the  tables. 

In  other  situations,  however,  recall  may 
depend  upon  recollection.  To  describe  the 
details  of  a  picture  seen  in  the  past,  we 
usually  re-view  the  picture,  reading  (recall- 
ing) the  details  from  the  visualized  (recol- 
lected) picture. 

As  a  part  of  his  act,  one  vaudeville 
prodigy  used  to  learn  a  10-by-lO  square  of 
numbers— 100  digits  in  all.  The  numbers 
were  called  out  at  random  by  the  audience 
at  the  beginning  of  the  act.  After  writing 
the  ninnbers  down,  the  prodigy  tinned  the 
blackboard  over  and  performed  other  nu- 
merical tricks.  Half  an  hour  later  he  would 
repeat  the  whole  set  of  digits,  writing  them 
down  in  an  order  different  from  that  in 
which  they  had  been  originally  placed  upon 
the  board.  The  stunt  might  have  been 
managed  by  tricks  of  memorizing,  but  in 
this  case  it  was  foimd  to  depend  upon  a 
detailed  visual  recollection.  In  general,  a 
subject's   ability   to  reproduce   in   different 


Recollecting 


187 


order   Llic  items  of  a   material  is  evidence 
of  visual  recollection. 

Recollection,  of  course,  is  by  no  means 
limited  to  visual  scenes.  Any  of  the  sense 
departments  may  be  involved,  singly  or  in 
combination,  with  each  showing  special 
development  in  certain  individuals.     The 


in  young  (lii!di(ii  than  in  adults.  I  hcv 
can  be  defuiiteiy  localized  and  'projcded' 
upon  a  screen. 

Figure  70  is  a  picture  that  was  shown  to 
English  school  children  in  an  investigation 
of  eidetic  imagery.  Some  of  the  children 
could  recollect  the  picture  in  such  detail 


FIGURE    70.      EIDETIC   IMAGERY 


This  picture  was  shown  to  a  number  of  English  school  children  for  35  seconds.  From  an  image  of  the 
picture  the  children  were  later  able  to  describe  accurately  a  very  great  many  details,  including,  in  some 
cases,  the  long  German  word  over  the  entrance  of  the  building.  [Used  by  G.  ^V.  Allport,  Brit.  J.  Psychol., 
1924,  15,  99-120.] 


prodigious  feats  of  musical  memorization 
exhibited  by  some  musicans  would  be 
likely  to  be  instances  of  unusually  accurate 
auditory  recollection. 

Eidetic  Images 

At  times  recollected  and  imagined  ob- 
jects can  appear  in  extremely  complex  and 
clear  detail,  resembling  ordinai7  percep- 
tions. Such  images  are  known  as  eidetic 
images.     They  are  more  frequently  found 


that  they  were  able  to  spell  the  strange  Ger- 
man word  on  the  house  at  the  left.  Three 
out  of  thirty  children  could  spell  the  word 
correctly  forward  or  back^vard,  Avhereas 
seven  could  spell  it  either  way  with  only 
two  mistakes— the  same  mistakes  in  either 
direction. 

This  is  an  example  of  an  eidetic  recol- 
lection, but  similar-  clear  images  can  also 
occur  ■\\ithout  reference  to  the  past.  An 
eidetic  image  is  an  experience  which   lies 


188 


Recollecting,  Imagining  and  Thinking 


on    the    borderline   between    a   perception 
and  an  image. 

Although  adults  do  not  often  report 
having  eidetic  images,  they  may  experience 
them  under  special  circumstances.  After 
a  long  and  concentrated  day  of  visual  study 
of  some  particular  material,  like  micro- 
scopic slides  or  blueprint  drawings,  images 
of  ilie  material  may  insist  on  floating  in 
iront  of  the  eyes  later  when  the  tired  ob- 
server is  falling  asleep.  A  haunting  tune 
may  be  made  of  auditory  eidetic  imagery. 

Recollection  and  Perception 

Recollected  events  are  describable  in 
terms  of  color,  shape,  sound,  warmth,  feel- 
ings of  movements  and  the  like.  We  de- 
scribe them  in  the  same  terms  we  tise  for 
perceived  objects  and  events  themselves. 
A  question  arises,  therefore,  as  to  how 
recollected  objects  difi^er  from  perceived 
objects,  a  question  which  has  troubled  a 
great  many  psychologists  in  the  past.  Al- 
most any  criterion  of  differentiation  upon  a 
descriptive  basis  is  faulty  because  of  the 
exceptions  which  occur.  Recollections  are 
usually  less  clear,  less  definite  and  less  de- 
tailed than  perceptions,  but  that  is  not  al- 
ways the  case.  Some  recollections,  espe- 
cially the  recollections  of  certain  gifted 
individuals  (like  the  'prodigy'  mentioned 
above)  and  eidetic  recollections,  are  ex- 
tremely clear  and  detailed,  whereas  an  ob- 
ject seen  briefly  out  of  the  corner  of  the  eye 
or  in  a  mist  is  anything  but  clear,  definite 
and  detailed. 

The  question  is;  How  do  we  tell  the 
difference  between  a  bit  of  melody  which 
has  come  back  from  the  past  and  the  snatch 
of  melody  heard  as  being  played  right  now 
on  the  neighbor's  piano?  How  can  we 
distinguish,  when  either  or  both  may  be 
clear  or  unclear,  loud  or  soft,  have  the 
same  pitches  and  so  on?     The  fact  is  that 


we  do  usually  distinguish  perceived  objects 
from  recollected  objects,  even  when  the 
recollected  objects  are  clear  and  detailed. 
The  difference  lies  in  the  meaning  of  the 
experience,  rather  than  in  the  pattern  of 
colors,  sounds,  shapes  or  movements.  We 
can  say  that  we  'just  know'  fact  from  mem- 
ory, perception  from  recollection. 

What  really  happens  is  that  there  are 
two  worlds— the  world  of  perception  and 
the  world  of  imagery.  To  the  experienced 
adult  the  world  of  perception  is  a  complex 
but  unitary  whole.  A  thing  is  'there,'  is 
'real'  and  not  imaginary,  if  you  can  see  it, 
touch  it,  handle  it,  find  it  there  whenever 
you  turn  to  it,  discover  that  what  you  per- 
ceive of  it  depends  on  what  you  do  to  put 
your  sense  organs  in  relation  to  it.  The 
hard  yellow  floor  of  your  room,  the  blue 
walls,  the  uncomfortable  chair  with  the  too 
soft  cushion,  the  brown  radio  with  the  swing 
music  coming  out  of  it,  the  smell  of  fresh 
paint  from  the  next  room  mixed  with  the 
smell  of  magnolias  through  the  open  win- 
dow, all  these  items  of  experience  together 
with  hundreds  of  others  make  up  a  con- 
sistent systematic  whole  which  we  think 
of  as  reality.  Other  items  that  fit  into  the 
system  are  necessarily  'real,'  have  the  mean- 
ing of  reality  given  them. 

All  is,  however,  not  so  simple.  A  woman 
enters  your  room  and  takes  a  chair.  Thus 
she  fits  into  the  system,  is  presimiably 
'real.'  But  she  might  be  a  delusion.  So 
might  the  magnolias,  the  music  and  the 
whole  room.  The  only  proof  of  reality 
you  have  is  that  the  items  of  it  all  fit  to- 
gether and  are  consistent  with  the  host  of 
your  recollections  about  them  and  about 
the  relations  of  things  in  general.  If  the 
woman  is  transparent,  if  she  walked  in 
through  the  door  without  opening  it,  per- 
haps she  is  not  'real,'  for  she  does  not  fit 
past    experience    with    'real,    live'    women. 


Reliabilify  of  Recollection 


189 


You  have  only  to  feel  that  the  c;onsistenty 
ol  the  system  is  destroyed  to  doubt  the 
•  reahty  of  perception.  Starting  off  to  work 
in  the  morning  when  there  is  really  no 
work  because  it  is  a  holiday  soon  shows  you 
how  the  system  fits  together.  The  streets 
are  half  empty,  the  other  people  are  not 
hurrying  to  work,  and  you  get  first  a  feel- 
ing of  unreality,  imtil  you  find  out  what 
is  wrong.  You  had  forgotten  about  Wash- 
ington's birthday. 

Recollection  and  imagination  make  up 
the  experience  that  comes  into  your  life 
without  fitting  the  basic  perceptual  pattern 
as  do  perceptions.  You  are  recollecting 
when  what  you  experience  fits  into  a  past 
perceptual  system,  is  dated  and  placed  in 
)-elation  to  past  places  and  events.  If  there 
is  no  such  specification  upon  the  experi- 
ence, presumably  it  is  an  imagination,  a 
vision,  an  inspiration. 

RELI  ABI  LITY    OF 
RECOLLECTION 

There  are  ways  of  measuring  the  relia- 
bility of  recollection  and  of  studying  how  a 
recollection  changes  with  the  lapse  of  time. 

Reliability  of  Testimony 

If  you  follow  the  accounts  of  a  criminal 
trial  in  a  newspaper  or  if  you  read  detec- 
tive stories,  you  may  have  been  impressed 
by  the  amount  and  accuracy  of  detail  which 
the  witnesses  to  the  crime  are  asked  to 
recollect.  Actual  testimony  is,  liowever, 
frequently  conflicting  and  is  often  changed 
under  cross-examination. 

Prompted  by  the  practical  problems  of 
the  law,  psychologists  have  performed  a 
number  of  experiments  to  determine  the 
accuracy  of  testimony  and  the  conditions 
imder  which  recollection  is  accurate.  Their 
method  is  to  stage  a  scene  or  event  for  a 


'witness'  oi  to  sliow  him  a  moving  picture. 
Sometimes  the  witness  knows  in  advan(c 
that  he  will  be  required  to  recall  the  details 
later.  In  other  experiments  the  crucial 
event  is  introduced  casually  and  appar- 
ently accidentally,  so  that  the  witness  is 
not  prepared  for  his  later  examination. 
'I'he  examination  of  the  witness  takes  place 
later  after  various  periods  of  time  have 
been  allowed  to  elapse. 

Even  when  subjects  have  no  'axe  to 
giind'  and  are  merely  collaborating  in  an 
experiment,  their  errors  of  recollection  are 
many.  Errors  occur  even  though  the  sub- 
ject is  instructed  in  advance  to  be  ready 
for  a  later  test  of  his  accuracy.  They  in- 
crease markedly  when  the  original  event  oc- 
curred 'accidentally'  and  without  the  suIj- 
ject's  expecting  it.  Thus  perception  with 
the  intention  to  recall  the  event  later  is  an 
important  factor  in  the  accuracy  of  recol- 
lection, a  factor  seldom  operative  in  court- 
room testimony. 

Another  factor  that  can  affect  the  accu- 
racy of  recollection  is  questioning  or  cross- 
examination  at  the  time  of  recall.  If  a 
witness  is  allowed  to  report  what  he  can, 
without  questioning,  his  reports  may  be 
fairly  accurate,  although  still  not  perfect. 
Cross-examination  may.  however,  double 
or  triple  the  proportion  of  incorrect  infor- 
mation which  is  given  by  witnesses.  The 
leading  question  is  very  effective  in  induc- 
ing witnesses  to  recall  something  that  did 
not  appear  in  the  original  event  at  all.  The 
leading  question  in  the  form,  "^Vasn■t 
there  a  horse  in  the  street?"  •will  often 
receive  the  reply  "yes"  if  it  is  at  all  reason- 
able to  suppose  that  a  horse  could  have 
been  there.  Once  such  a  false  recollec- 
tion has  been  reported  under  cross-exami- 
nation, it  tends  to  become  fixed  and  to 
reappear   later,   e\en   spontaneously.      Per- 


190 


Recollecting,  Imagining  and  Thinking 


haps  the  witness  did  not  really  recollect 
the  horse  when  the  question  was  asked,  but 
later,  under  pressure  to  be  consistent,  he 
becomes  convinced  that  he  is  actually  recol- 
lecting something  he  truly  saw. 

These  experiments  differ  from  the  real- 
life  situation  involved  in  testimony  in  three 
ways.  First,  the  laboratory  or  classroom 
situation  is  relatively  calm  and  unemo- 
tional. Emotion  is  likely  to  decrease  ac- 
curacy of  perception  and  recollection.  Sec- 
ond, the  experimental  situation  is  not  so 
intensely  interesting  as  a  real  accident, 
robbery  or  similar  dramatic  event.  Inter- 
est favors  accuracy  but  is  likely  to  be 
(oiipled  with  emotion,  which  favors  inac- 
curacy. Often  psychologists  have  intro- 
duced both  interest  and  emotion  into  their 
experiments  by  staging  dramatic  episodes 
in  I  he  classroom  with  some  success  in  con- 
\incing  the  students  of  their  authenticity. 
In  one  case,  for  example,  the  instructor  had 
an  argument  with  a  man  who  interrupted 
his  class.  The  event  was  carefully  re- 
hearsed and  staged  so  that  the  accuracy  of 
testimony  could  be  checked.  The  amount 
of  error  was  found  to  be  extremely  high. 
Descriptions  of  the  man  ranged  from  tall 
to  short,  dark  to  blond,  fat  to  thin  and 
so  on. 

A  third  difference  between  the  experi- 
ment and  the  courtroom  lies  in  the  fact 
that  errors  of  recollection  become  much 
more  important  in  the  courtroom.  In  the 
experiment  the  subject  may  be  willing  to 
report  something  of  which  he  is  not  cer- 
tain, largely  because  error  will  not  matter 
much.  Often  the  subjects  are  asked  to  dis- 
tinguish between  those  things  which  they 
are  willing  to  swear  to  and  the  things  of 
which  they  are  only  moderately  sure.  See 
Table  XII  for  the  results  of  one  experi- 
ment.    Although  the  accuracy  was  higher 


TABLE  XII 

Errors  of  Rfxollection 

Showing  the  errors  in  an  experiment  upon  testimony. 
Subjects  were  shown  a  picture,  then  answered  a  ques- 
tionnaire about  the  contents  of  the  picture  at  each  of 
the  time  intervals  listed.  Each  answer  was  labeled 
according  to  the  degree  of  certainty  of  the  subject. 
"Report"  refers  to  an  answer  which  was  "just  a  little 
better  than  a  mere  guess."  "Fairly  certain"  is  the 
description  given  to  the  next  degree  of  certainty. 
The  last  column  shows  percentage  of  errors  in  answers 
where  the  subject  was  "willing  to  give  his  sworn 
oath."  [From  K.  M.  Dallenbach.  Psychol.  Rev.,  1913, 
20,  323.] 

Percentage  Error 

Time  of  Recall  Report  Fairly  Certain  Sworn  to 
Immediate  48.2  28.3  6.7 

5  days  66.6  30.7  10.0 

15  days  64.5  25.3  15.4 

45  days  55.0  31.4  19.5 


Average  of  errors        58 . 6 


28.9 


12.9 


for  those  reports  of  which  the  subjects  were 
very  sure,  the  percentage  of  error  was  still 
substantial. 

Changes  in  Recollection 
with  Lapse  of  Time 

In  addition  to  these  practical  experiments 
upon  the  reliability  of  testimony,  the  way 
the  recollection  of  an  object  changes  with 
lapse  of  time  has  been  investigated.  We 
need  to  know  what  happens  to  the  mem- 
ory of  an  object  or  event  as  time  passes 
and  whether  the  memory  of  an  object 
simply  fades  out,  gradually  becoming  more 
and  more  fuzzy  and  indefinite,  or  whether 
it  undergoes  other  changes. 

The  experimental  procedure  is  as  fol- 
lows. An  observer  is  shown  an  object,  a 
series  of  objects  or  a  story.  Later  he  is 
asked  to  redraw  the  object  or  retell  the 
story  as  he  recalls  it.  (See  Fig.  71.)  In 
some  of  the  experiments  the  observers  re- 
produce each   object  just  once,   with   the 


Changes  in  Recollection  with  Lapse  of  Time 


191 


time  intervals  between  initial  observation 
and  reproduction  varying.  In  other  experi- 
ments the  observers  are  asked  to  repro- 
duce the  same  material  over  and  over  again, 
thus  getting  at  the  effects  of  repeated  recol- 
lection. 

Both  these  experimental  conditions  have 
their  counterparts  in  everyday  lite.  Some- 
times your  first  recollection  of  an  event 
occurs  only  after  a  considerable  lapse  of 
time.     You  have  not  thought  of  the  event 


ToR  T^Al)-  J)'Hofif|^ 


FIGURE  71.      PERCEPTION  AND  IMAGE 

The  drawing  at  the  left  was  observed  by  a  person 
and  reproduced  by  him  15  to  30  minutes  later  as 
on  the  right.  Thus  the  figure  at  the  left  represents 
the  stimulus,  and  the  figure  on  the  right  the  recol- 
lection of  it.  [From  F.  C.  Bartlett,  Remembering, 
Cambridge  University  Press,  1932,  p.  178.] 

or  reviewed  it  between  the  original  per- 
ception and  the  recall  much  later.  More 
frequently,  however,  a  striking  event  in 
your  life  is  recollected  over  and  over  again 
at  intervals  for  many  years.  When  you 
recall  an  important  event  of  your  child- 
hood, you  have  probably  recollected  it 
many  times  before.  Your  present  recollec- 
tion is,  therefore,  a  result  of  many  previous 
rehearsals.  In  part  this  recall  is  a  recol- 
lection of  a  recollection  of  a  recollection, 
but  it  also  may  refer  to  the  original 
observations.  It  is,  moreover,  impossible 
to  be  sure  that  the  period  of  time  between 
the  original  perception  and  the  recollection 
is  ever  entirely  free  of  spontaneous  re- 
hearsals by  the  subject,  and  it  is  certainly 


not  improbable  that  we  never  recall  an 
event  after  a  long  time  span  without  there- 
having  been  intervening  rehearsals. 

When  the  experimenter  has  collected  a 
great  many  reproductions— drawings  or  re- 
ports—he is  likely  to  be  impressed  by  the 
great  variety  of  things  which  can  happen 
to  a  recollection.  To  describe  the  mem- 
ory merely  as  indefinite  and  unclear  does 
not,  however,  do  justice  to  the  findings. 
Some  aspects  of  a  design  or  a  story  may 
become  7nore  clear  as  time  passes.  To  be 
sure,  these  clear  aspects  are  not  necessarily 
correct,  even  though  the  observer  believes 
that  they  are. 

Some  of  the  changes  which  frequently  oc- 
cur are  these: 

(1)  Details  are  omitted;  only  the  general 
pattern  is  reproduced. 

(2)  New  details  are  added;  for  example, 
eyebrows  were  added  to  a  drawing  (A 
a  face  which  originally  had  none. 

(3)  Certain  peculiarities  of  the  original 
figure  may  become  exaggerated  in  the 
reproduction;  for  example,  slanting 
eyes  become  more  slanted  in  recollec- 
tion. 

(4)  The  resemblance  between  the  figure 
and  some  familiar  object  is  increased; 
for  example,  a  conventional  drawing 
of  a  cat  becomes  more  catlike. 

(5)  Different  figures  in  the  same  experi- 
ment come  to  resemble  one  another 
more  than  they  did  originally. 

(6)  Under  repeated  recollection,  errors 
and  changes  may  finally  become 
stabilized. 

(7)  Stories,  and  sometimes  figures,  may 
be  made  more  'logical'  or  made  to 
fit  a  more  familiar  pattern.  (See 
Fig.  71.) 


192 


Recollecting,  Imagining  and  Thinking 


Nature  of  Errors  in  Recollection 

The    factors    which    bring    about    these 
changes  in  recollection  operate  both  during 


Stimulus 


Reproductions 


0 

0'-i8"8"8" 

/\ 

'i"'!iil 

0 

@ 

0 

R    1             2 

^ 

46 

FIGURE    72.       DEPENDENC:E    ok    RKCOl.l.ECriON    ON 
MEANING 

Tlie  fi_mircs  in  llie  sLiimilus  column  were  shown, 
among  a  niniiber  of  others,  to  a  group  of  subjects 
for  a  short  time.  Their  reproductions  of  these 
stimuli,  made  from  memory,  varied  according  to  the 
meaning  suggested  by  the  figmes.  Thus  stimulus  1 
suggested  (1)  a  woman's  torso;  (2)  a  "footprint  on 
the  sands  of  time";  (3)  a  dumb-bell;  (4)  a  violin: 
(5)  a  dumb-bell.  Stimulus  2  received  the  names  (1) 
pillars  with  curve;  (2)  pillars  with  curve;  (3)  mega- 
phone in  a  bowl.  Stimulus  3  was  named  (1)  one 
circle  inside  another.  The  experimenter  gave  dif- 
ferent names  to  stimulus  4  as  he  showed  it  to  dif- 
ferent individuals.  Their  reproductions  varied  ac- 
cording to  the  name:  (1)  bottle;  (2)  stirrup.  Stim- 
ulus 5  was  treated  like  stimulus  4.  The  names 
were  (1)  pine  tree;  (2)  trowel.  [After  J.  J.  Gibson, 
/.  exper.  Psychol.,  1929,  12,  15  and  19;  and  L.  Car- 
michael,  H.  P.  Hogan  and  A.  A.  Walter,  /.  exper. 
PsyclioL.  1932,  15,  75  and  SO.] 

the  original  perception  and  afterward.  If 
the  original  object  is  seen  as  resembling 
sotnething  familiar,  if  it  is  given  a  name  or 
if  certain  special  features  of  it  are  noticed, 
these  characteristics  tend  to  become  more 


marked  in  the  reproduction.  Figure  72 
shows  some  examples  of  this  effect  of  the 
original  mode  of  perception.  Such  char- 
acteristics are  hkely  to  appear  in  the  very 
first  reproduction,  immediately  after  the 
perception.  As  time  goes  on,  the  effect 
may  become  more  exaggerated.  Sometimes 
it  appears  that  the  observer  recalls  only 
the  verbal  identification  or  the  general  re- 
semblance to  a  familiar  object,  and  recon- 
structs his  recollection  from  it. 

We  have  noted  that  forms  as  well  as 
stories  may  becoine  more  'logical'  or  sen- 
sible in  recollection.  That  happens  most 
often  when  the  original  material  is  frag- 
mentary or  perceived  as  fragmentary,  as  it 
may  be  if  perceived  hurriedly  or  under  dis- 
traction. Then  recollection  goes  to  work 
to  make  a  whole  out  of  the  parts,  to  com- 
plete and  unify  the  event  or  form  or  what- 
ever it  is  that  is  being  recalled.  It  is  not 
easy  to  describe  disconnected  scraps.  Recol- 
lection needs  to  have  a  total  structure  if  it 
is  to  represent  adequately  the  original  per- 
ception. The  same  thing  happens  in  recol- 
lecting dreams.  There  we  piece  the  seem- 
ingly silly  fragments  together  into  a  sen- 
sible story. 

These  laboratory  experiments  on  recol- 
lection are  concerned  with  impersonal  ma- 
terial. They  differ  from  the  recall  of  events 
in  our  own  past  lives,  events  involving 
emotional  relationships  to  other  persons, 
success  and  failure  in  work  or  sport.  The 
emotional  context  of  most  of  our  oiclinary 
recollections  is  another  factor  which  modi- 
fies our  recollections  and  frequently  falsi- 
fies them. 

The  psychoanalysts  have  collected  ex- 
amples from  clinical  practice  showing  the 
falsification  of  memories  of  emotional  situ- 
ations and  conflicts.  (See  pp.  175  and  520  f.) 
The  experimental  results  we  have  described 
represent  changes  in  recollection  which  are 


Errors  and  Failures  of  Recollecfior) 


193 


but  mild  and  sliglit  coinpaicd  to  tlu: 
changes  which  occur  in  normal  personal 
recollections.  Autobiographies  and  mem- 
oirs, iMiless  they  are  carefully  authenticated, 
must  be  full  of  these  personalized  distor- 
tions. 

Some  investigators  have  sotight  to  study 
recollection  of  events  into  which  an  emo- 
tional flavor  has  been  injected.  In  one 
experiment  a  subject  was  given  various 
problems  to  solve.  He  succeeded  in  solv- 
ing some  of  them.  Others,  however,  were 
too  difficult  for  him  and  he  was  disturbed 
at  failing.  Later  he  was  asked  to  recall 
the  problems  upon  which  he  had  worked, 
and  the  experimenter  compared  his  accu- 
racy in  recall  of  those  problems  in  which 
he  experienced  failure  with  those  which  he 
solved.  It  was  found  that  as  a  rule  he  re- 
called with  greater  accuracy  the  problems 
he  solved  than  those  in  which  he  failed. 

Another  way  of  showing  how  personal 
factors  influence  recollection  is  to  use  for 
perception  and  recall  material  which  either 
accords  with  the  attitudes  and  opinions  of 
the  subject  or  contradicts  them.  Here  fol- 
lows the  account  of  such  an  experiment. 

Two  groups  of  students— one  group 
strongly  pro-Communist,  the  other  strongly 
anti-Commimist— were  chosen  as  the  sub- 
jects. Each  subject  was  asked  to  study  two 
brief  excerpts  from  books.  One  of  these 
passages  was  a  strong  anti-Soviet  argu- 
ment; the  other  was  moderately  pro-Soviet. 
The  materials  were  studied  repeatedly; 
hence  there  was  more  learning  than  recol- 
lecting going  on.  Nevertheless,  the  biases 
entered  in.  The  anti-Communist  subjects 
recalled  the  points  of  the  anti-Soviet  argu- 
ment better  than  the  pro-Communist  sub- 
jects did.  The  converse  held  for  the  pro- 
Communist  passage.  These  differences  ap- 
peared after  each  of  the  repeated  periods 
of  studv  of  the  materials.     After  foin-  such 


periods  of  study,  the  tests  were  continued 
lor  five  weeks  without  further  opportunity 
to  review  the  printed  materials,  and  the 
two  biases  became  more  and  more  effective 
during  the  serifs  of  repeated  recollections. 

Failures  of  Recollection 

Often  recollection  fails.  The  conditions 
seem  to  be  right  for  its  occurrence,  yet  it 
is  blocked,  temporarily  or  even  perma- 
nently. Emotional  factors  are  often  to 
blame,  for  they  may  lead  to  a  forgetting 
which  is  called  repression,  a  blocking  of 
recollection  which  can  be  overcome  only 
by  treatment,  such  as  psychoanalysis.  (See 
p.   541.) 

When  forgetting  is  complete  and  per- 
sistent it  is  called  amnesia.  Amnesia  mav 
occur  after  a  bad  shock  like  an  accident  or 
after  an  intensely  emotional  experience. 
The  person  affected  may  lose  his  memory 
for  a  period  either  before  or  after  the  event. 
In  extreme  cases,  he  may  lose  his  memor\ 
for  his  whole  past  life,  including  his  knowl- 
edge of  his  identity,  of  where  he  lives  and 
so  on. 

Amnesia  illustrates  clearly  the  distinc- 
tion between  learning  and  recollection.  It 
is  a  characteristic  of  amnesia  that  the  indi- 
vidual loses  recollection  alone.  He  does 
not  forget  how  to  walk,  how  to  speak  his 
native  language  or  even  other  skills  ac- 
quired later  in  life  such  as  typing,  or  his 
other  occupational  skills.  Recollection  is 
the  recall  of  experiences  in  the  personal 
past,  and  it  is  these  experiences  whicli  are 
lost  in  amnesia. 

There  is,  however,  a  certain  selectivity 
in  recollection  which  does  not  seem  to  fol- 
low  strictly  from  the  la^\s  of  learning. 
Only  a  few  past  events  come  back  out  of 
the  many  which  association  might  bring. 
The  selection  is  doubtless  due  to  the  sets 
and  motives  that  are  operating. 


194 


Recollecting,  Imagining  and  Thinking 


A  more  complete  analysis  of  the  prob- 
lem of  amnesia  requires  an  understanding 
of  the  general  problems  of  abnormal  psy- 
chology.    (See  pp.  531-535.) 

TYPES    OF    RECOLLECTION 

Accurate  recollection  of  the  same  object 
or  event  does  not  necessarily  always  take 
the  same  form.  There  are  different  kinds 
of  recollection.  One  man  may  differ  from 
another  in  the  kind  of  recollection  he  uses 
most  of  the  time.  One  task  may  differ  from 
another  in  the  type  of  recollection  that  is 
best  suited  to  it.  These  differences  are 
found  between  persons  and  also  between 
recollections  by  the  same  person. 

One  of  the  t-\vo  most  important  distinc- 
tions of  this  sort  is  the  difference  that  oc- 
curs according  to  the  sense  departments 
used.  "We  can  recall  events  in  visual 
imagery,  or  auditory  imagery,  or  in  motor 
processes.  The  other  important  distinction 
lies  in  the  difference  between  verbal  recol- 
lection and  recollection  in  terms  of  concrete 
imagery.  Take  the  recollection  of  a  par- 
ticular hammer.  A  man  may  recall  in 
imagery  (1)  the  look  of  the  hammer,  (2)  the 
feeling  of  swinging  the  hammer  in  his 
hand,  (3)  the  sound  of  the  blows  of  the 
hammer,  (4)  the  look  of  the  word  hammer, 
(5)  the  sound  of  the  word  hammer,  (6) 
the  voice-feeling  of  what  saying  the  word 
hammer  is  like.  The  first  three  recollec- 
tions are  made  of  concrete  imagery,  visual, 
kinesthetic  and  auditory.  (Kinesthetic 
means  pertaining  to  the  feeling  of  the  move- 
ment of  your  own  body  and  its  parts.) 
The  last  three  are  verbal  imagery,  visual, 
auditory  and  kinesthetic.  There  are  differ- 
ent combinations  of  these  types  of  verbal 
imagery.  For  instance,  auditory-kinesthetic- 
verbal  imagery  is  much  more  common  than 
pure  auditory-verbal  imagery.     If  you  hear 


the  sound  of  a  word  in  imagery,  you  are 
likely  also  to  feel  how  it  is  to  pronounce  it. 

Are  there  differences  among  persons  in 
respect  of  these  imagery  types?  Do  some 
people  prefer  visual  imagery,  others  kines- 
thetic, others  auditory-kinesthetic?  Yes, 
there  are  such  persons  but  they  are  excep- 
tional. Occasionally  you  find  a  person 
who  seems  never  to  have  visual  imagery, 
who  recollects  entirely  in  terms  of  kines- 
thetic and  auditory-kinesthetic  imagery, 
both  verbal  and  concrete.  He  will  tell  you 
what  the  colors  of  the  rocks  in  the  Grand 
Canyon  of  the  Colorado  look  like,  but  he 
will  be  recollecting  words,  not  actual  col- 
ors. Occasionally  you  find  a  person  who 
does  nearly  all  his  thinking  in  visual  terms, 
even  in  his  verbal  thinking.  Most  persons, 
however,  use  all  the  types  on  different  oc- 
casions.    Versatility  is  the  rule. 

Versatility  is  also  more  efficient.  As  we 
have  already  seen  in  the  discussion  of 
eidetic  imagery,  recollection  of  great  detail 
of  an  object  is  easiest  if  it  occurs  in  visual 
terms.  If  you  can  see  the  Mona  Lisa  in 
your  'mind's  eye,'  you  can  do  a  good  job 
at  recollecting  it.  If  you  have  to  depend 
on  kinesthesis,  you  will  be  likely  to  get 
only  the  words  with  which  you  originally 
described  it.  On  the  other  hand,  if  you 
are  remembering  the  Ninth  Symphony, 
auditory  imagery  is  more  fun,  even  though 
visual  recollection  of  the  looks  of  the  score 
may  be  quite  accurate.  Kinesthesis,  of 
course,  fails,  since  you  cannot  sing  or  play 
a  symphony  by  yourself.  The  best  you 
could  do  with  kinesthesis  would  be  to  re- 
member descriptive  words.  The  stroke  in 
golf  which  you  have  at  last  mastered;  how 
do  you  recollect  that?  Kinesthesis  is  best 
there,  though  you  might  have  a  visual 
image  of  ho^v  the  'pro'  swings  his  club. 
Sometimes  imagery  type  is  thus  related  to 
efficiency  in  recollecting. 


Types  of  Recollection 


195 


On  the  other  hand,  it  is  surjjrising  how 
often  type  does  not  matter.  Verbal  recol- 
lection fits  into  any  ol  the  common  types, 
and  most  recollection  can  be  made  verbal. 
Musicians  do  not  necessarily  recall  music 
in  auditory  terms.  Geometricians  do  not 
necessarily  use  visual  terms.  Persons  who 
have  been  blind  and  deaf  from  birth  and 
have  no  visual  and  auditory  imagery  are 
capable  of  learning  language  and  of  doing 
any  of  the  abstract  thinking  which  is  nor- 
mal to  a  person  without  sensory  defect. 
They  are  shut  off  from  certain  perceptions 
and  from  such  direct  recollections,  but  they 
are  able  to  substitute  kinesthetic  imagery. 
Blind  persons  learn  to  perceive  in  auditory 
and  kinesthetic  terms  with  remarkable  ac- 
curacy, and  their  recollections  take  place  in 
similar  terms. 

One  reason  why  type  of  imagery  makes 
so  little  difference  in  human  life  is  to  be 
found  in  the  fact  that  the  most  important 
recollections  for  civilized  adults  are  gen- 
eral and  abstract,  not  concrete  and  ob- 
jective. Most  recollecting  of  this  sort,  and 
indeed  most  thinking,  can  be  done  in 
words,  and  any  of  the  three  main  kinds  of 
imagery  will  work  with  words. 

Verbal  recollection  is  commoner  than 
concrete  recollection,  less  accurate  as  a 
rule,  but  more  efficient  in  the  sense  that 
the  telescoping  of  a  complex  object  or 
event  into  a  verbal  formula  is  so  compact 
that  it  gets  out  of  the  way  of  other  recol- 
lections. Any  important  business  of  living 
is  likely  to  include  the  making  of  judg- 
ments. You  can  recollect  the  judgment 
you  previously  made  of  an  observation  in 
words  and  do  it  fairly  easily.  More  diffi- 
cult and  less  common  is  it  to  recollect  the 
observation  itself,  as  you  might  be  able  to 
do  quite  accurately  in  eidetic  imagery,  and 
then  to  make  your  judgment  of  the  recol- 
lection.    The  witness  on  the  stand  is  asked 


to  recollect  the  event  and  to  let  the  court 
or  jury  pass  judgment.  More  often  he 
recollects  his  past  judgment  of  the  event 
and  reports  it  or  tries  to  reconstruct  the 
fading  event  from  it.  It  is  easier  for  a  wit- 
ness to  remember  that  he  thought  the 
driver  who  hit  the  pedestrian  was  at  fault 
than  it  is  for  him  to  recollect  just  what  it 
was  that  made  him  blame  the  driver.  Ac- 
curacy and  scope  are  here  inversely  related. 
You  can  remember  best  if  you  remember 
details  of  an  event;  but  you  can  remember 
more  events  if  you  condense  each  into  your 
assessment  of  it  and  remember  merely  the 
assessment.  How  often  a  man  says:  "I 
know  that's  a  fallacy,  but  I  can't  remember 
why." 

iMAGI  Nl  NG 

Like  recollection,  imagining  creates  ob- 
jects without  benefit  of  the  sense  organs. 
A  person  who  is  blinded  during  his  child- 
hood can  continue  to  imagine  colors  and 
shapes.  A  person  who  becomes  deaf  can 
still  imagine  sounds  and  melodies.  Beetho- 
ven composed  and  conducted  great  music 
after  he  was  stone  deaf. 

There  is  no  essential  difference  bet^veen 
the  kinds  of  experience— colors,  shapes, 
sounds— that  make  up  perceptions,  recollec- 
tions and  imaginations.  As  we  have  already 
seen,  these  experiences  differ  only  in  their 
meaning.  The  perceived  object  is  there- 
now-in-front-of-me,  belonging  to  the  svstem 
of  present  reality.  The  recollected  object 
is  something-I-once-saw,  belonging  to  some 
system  of  past  reality.  The  imagined  ob- 
ject is  the  thing  which  is  about-to-happen 
or  which  might  happen,  and  it  is  either  iso- 
lated without  fitting  any  established  system 
or  else  it  fits  temporarily  and  insecurelv 
into  a  reality  system,  as  is  the  case  Ashen  I 
look  at  my  empty  garage  and  imagine  a 
splendid  car  in  it. 


196 


Recollecting,  Imagining  and  Thinking 


Imagination  and  Perception 

Since  imagination  is  free  and  not  tied  to 
reality,  there  is  no  problem  of  the  reliabil- 
ity of  imagination.  There  are,  however, 
the  cases  in  which  imagination  occurs  to- 
gether with  a  perception,  the  cases  in  which 
imagination  gets  confused  with  perception, 
the  cases  in  which  the  imagination  is  mis- 
taken for  a  perception  and  the  contrary 
cases  in  which  a  perception  seems  strange 
and  is  taken  for  an  imagination. 

Synesthesia.  There  are  a  few  persons  (per- 
haps five  per  cent  of  the  population)  who 
report  that  they  experience  colors  when- 
ever they  hear  sounds;  that  is  to  say,  there 
is  a  definite  color  or  color  pattern  which 
regularly  appears  when  a  certain  soimd  is 
heard.  This  phenomenon  is  known  as 
chromesthesia  or  colored  hearing.  Synes- 
thesia is  the  general  term  for  relations  of 
this  kind  between  sense  qualities.  Thus 
we  may  have  colored  odors  or  tastes  as  well 
as  colored  hearing. 

Colored  hearing  can  be  very  stable  and 
dependable.     Table  XIII  is  a  record  of  the 

TABLE  XIII 

A   Case   of   Chromesthesia   Investigated  in    1905 
AND  Again  in  1912 

The  notes  of  the  musical  scale  are  associated  with 
images  of  very  constant  colors.  [From  H.  S.  Langfeld, 
Psychol.  Bull.,  1914,  11,  113.) 


J90S 

J9/2 

c 

Red 

Red 

d'9 

Purple 

Lavender 

d 

Violet 

Violet 

el> 

Soft  blue 

Thick  blue 

e 

Golden  yellow 

Sunlight 

f 

Pink 

Pink,  apple  blossoms 

fS 

Green  blue 

Blue  green 

gb 

Greener  blue 

Greener  blue 

g 

Clear  blue 

Clear  sky  blue 

a 

Cold  yellow 

Clear  yellow,  hard, 
not  warm 

bb 

Orange 

Verges  on  orange 

Very  brilliant  coppery         Very  brilliant  coppery 


colors  associated  with  notes  of  the  musical 
scale  for  one  person  with  colored  hearing. 
The  two  records,  taken  seven  years  apart, 
show  remarkable  consistency. 

Synesthesia  is  a  special  form  of  imagin- 
ing—apparently not  imagining  of  objects 
but  of  abstract  sensory  qualities.  It  dif- 
fers from  other  forms  of  imagining  in  be- 
ing so  closely  tied  to  the  perceptive  situ- 
ation. 

How  synesthesia  develops  is  not  certain, 
but  it  is  probably  learned  early  in  child- 
hood. When  colored  patterns  are  perceived 
in  colored  hearing  they  are  likely  to  be 
familiar  kinds  of  designs,  like  wallpaper 
patterns.  Closely  resembling  synesthesia 
are  number  forms,  in  which  the  person  sees 
any  number  fitted  into  a  geometrical 
schema,  and  date  forms,  which  are  similar. 
A  number  form  is  likely  to  have  corners  in 
it  at  'imjaortant'  numbers,  like  5,  10,  12, 
25,  50,  100,  1000,  and  10,000.  A  common 
academic  date  form  for  the  year  is  a  closed 
ellipse,  with  the  spaces  for  June,  July  and 
August  much  longer  than  the  spaces  for 
any  other  month.  Such  forms  must  cer- 
tainly be  learned  and  cannot  be  innate. 

Dreams  are  the  most  familiar  events  in 
^vhich  imagination  plays  the  role  of  pei"- 
ception.  Since  dreams  are  bizarre  and  frag- 
mentary and  do  not  fit  in  well  with  any 
total  reality  system,  why  do  they  seem  real? 
The  answer  to  that  question  is  that  dreams 
do  not,  as  a  rule,  seem  real.  They  do  not 
seem  unreal;  that  is  all.  Dreams  occiu' 
under  some  strong  tension  or  set— some- 
times in  partial  fulfillment  of  a  suppressed 
wish,  the  psychoanalysts  think.  They  are 
vivid  and  usually  emotionally  toned,  but 
limited  in  scope  and  not  fitted  into  any 
reality  system  at  all. 

The  hallucinations  of  persons  with  men- 
tal disease  are  like  dreams.  The  schizo- 
phrenic who   tells   us   what  his  voices   are 


Imagination,  Perception  and  Thinking 


197 


saying  to  him,  the  mean,  ugly,  abusive 
things  they  say,  is  accepting  uncritically 
imagery  which  does  not  fit  in  with  reality; 
but  then  that  is  what  schizophrenia  is,  the 
splitting  up  o£  the  integrated  personality 
and  its  reality  systems. 

These  instances  show  that  the  kinds  of 
stuff  of  which  perception  and  imagination 
are  made  are  so  much  alike  that  without  a 
label  imagination  may  be  identified  as  per- 
ception or  at  least  not  distinguished  from 
it. 

False  imaginalion.  There  is  also  the  con- 
verse case  in  which  perception  is  thought 
to  be  imagination.  That  is  what  happened 
in  a  well-known  experiment  in  which  the 
observers  were  instructed  to  look  at  a 
screen,  fitted  into  a  window  in  a  wall,  and 
to  imagine  a  specified  object  projected 
upon  the  screen.  Unknown  to  the  observ- 
ers, a  projector  behind  this  translucent 
screen  projected  upon  the  screen  a  very 
dim  image  of  the  object  called  for.  The 
observers  were  quite  pleased  that  they  were 
able  to  get  their  images  of  imagination  so 
clearly.  They  did  not  guess  that  they 
were  actually  being  provided  with  a  visual 
stimulus.  Even  when  the  projected  image 
failed  to  correspond  exactly  with  the  char- 
acter of  the  thing  they  were  trying  to  imag- 
ine, they  still  regarded  the  object  as 
'imagined.'  "I  can  see  that  knife  standing 
up  on  end,"  one  observer  said.  "I  should 
have  thought  I  would  have  imagined  it  as 
lying  down."  It  is  important  to  note  that 
the  image  remained  even  after  the  pro- 
jector was  turned  off.  The  imagination, 
which  the  stimulus  helped  to  start,  contin- 
ued independently  afterward. 

Creative  imagination  also  sometimes 
works  in  a  similar  way.  An  author,  artist 
or  musician  creates  his  work  of  art— his 
story,  his  poem,  his  melody.  His  pride  in 
it  tells  him  that  his  work  is  new,  his  own 


creation;  and  then  iomeone  comes  who 
tells  him  that  what  he  has  done  is  a  close 
copy  of  what  someone  else  has  done.  Sure 
enough,  he  really  did  know  the  work  which 
he  copied  unconsciously,  but  his  recollec- 
tion was  separated  from  its  proper  past 
reality  system  and  the  composer— doubtless 
reinforced  f)y  his  own  wishes— mistook  his 
old  memory  for  new  imagination.  Many 
cases  of  plagiarism  are  uniruentional  and 
to  be  accounted  for  in  this  sini[jle  manner. 

THINKING 

The  psychology  of  thinking  is  not,  of 
course,  the  same  thing  as  logic.  Logic  ana- 
lyzes the  correctness  and  incorrectness  of 
thinking  or,  more  generally,  the  drawing 
of  conclusions  from  premises.  Thinking, 
however,  may  be  quite  illogical,  even  when 
it  gets  to  the  right  conclusion.  Often  im- 
portant creative  thinking  goes  on  by  trial- 
and-error.  You  form  an  hypothesis  as  a 
hunch.  You  test  it  out  in  thought,  and 
find  it  wrong.  You  make  up  another  h\- 
pothesis.  Finally  you  get  one  that  seems  to 
work  where  you  need  it  and  you  accept  it. 
It  may  be  an  hypothesis  in  such  form  that 
you  can  test  it  by  logic,  but  the  trial-test- 
error-trial-test-success  method  is  not  the 
procedure  of  logic. 

We  have  already  noted  that  the  term 
thinking  is  often  apphed  indiscriminatelv 
to  a  great  many  different  kinds  of  psvcho- 
logical  activity— recollecting  the  past,  imag- 
ining the  future  or  even  deciding  what  to 
do  now.  The  kind  of  thinking  which  re- 
quires special  and  sepai-ate  treatment  is  a 
more  complex  kind  of  performance.  It 
starts  with  a  problem  which  cannot  be 
solved  by  methods  ^\hich  come  readilv  to 
hand.  We  have  to  in\ent  ne^v  methods  for 
it  or  grasp  new  relationships;  at  least  thev 
are   new   to   the   thinker.      Sometimes   this 


198 


Recollecting,  Imagining  and  Thinking 


kind  of  thinking  is  called  elaborative 
thinking  to  distinguish  it  from  recollective 
and  imaginative  processes. 

Starting  with  the  acceptance  of  the  prob- 
lem, elaborati\'e  thinking  progresses 
through  a  series  of  phases,  reversing  direc- 
tion, discovering  new  problems,  dealing 
with  concepts  and  symbols,  recollecting, 
imagining,  applying  memorized  formulas 
and  so  on.  In  other  words,  the  progress  of 
thinking  consists  of  a  series  of  manipula- 
tions of  objects  and  of  other  tools  of 
thinking.  These  tools  exist  in  great  va- 
riety. Before  we  can  understand  the  total 
process  of  thinking,  we  must  examine  them 
and  try  to  describe  them  accurately. 

Important  Tools  of  Thinking 

Here  we  may  list  and  discuss  the  more 
important  tools  of  thinking— objects,  con- 
cepts and  symbols. 

(1)  Perceived,  recollected  and  imagined 
objects. 

(a)  Concrete  or  specific  objects.  You 
understand  the  word  'ancestor'  by  imag- 
ining your  own  grandfather.  In  testing 
the  truth  of  a  general  statement,  you 
look  for  concrete  exceptions.  In  under- 
standing the  word  'friction,'  you  imagine 
rubbing  your  hands  together. 

(b)  Objects  as  examples;  generalized 
objects.  In  solving  a  geometrical  prob- 
lem you  imagine  a  triangle  but  do  not 
consider  it  as  this  particular  imagined 
triangle;  that  is  to  say,  in  the  geometric 
operation  you  do  not  consider  it  as  ob- 
tuse, acute  or  as  any  other  particular 
kind  of  triangle.  It  is  just  an  object  of 
'that  general  kind.'  Geometry  always 
discusses  the  general  but  illustrates  with 
the  particular. 

(c)  Objects  with  dynamic  properties. 
In  solving  many  concrete  problems,  ob- 


jects are  seen  as  tools  for  doing  certain 
things.  A  stone  is  seen  only  as  some- 
thing heavy,  something  you  can  pound 
Avith.  An  object  may  be  seen  as  about- 
to-fall,  as  instable  on  its  base,  as  easily 
broken.  Through  past  experience  the 
object  takes  on  a  significance  beyond 
that  immediately  given  in  the  stimulus 
pattern.  You  see  that  ice  is  cold  and 
heavy. 

(2)  Concepts.  A  very  important  tool  for 
thinking  is  the  concept.  A  concept  is  a 
'general  idea,'  an  item  in  thinking  that 
stands  for  a  general  class.  As  an  experi- 
ence the  concept  may  seem  to  be  nothing 
more  than  an  ordinary  image,  but  as  a 
concept  it  has  acquired,  through  learning, 
various  potentialities  which  give  it  much 
more  general  meaning.  In  other  words  the 
concept  implies  the  state  in  which  there 
is  a  broadly  generalized  response. 

Consider  the  word  dog,  and  also  the 
concept  dog  which  may  enter  into  thought. 
If  you  read  in  a  story  the  sentence,  "He 
called  his  dog,"  you  miy  have  a  visual 
image  of  a  particular  dog,  you  get  the 
meaning  of  the  sentence,  but  you  are  not 
then  using  a  concept.  If,  on  the  other 
hand,  you  read  the  title  of  an  article  in  a 
journal,  "Conditioned  Responses  in  the 
Dog,"  this  dog  is  the  concept  dog,  for  it 
means  any  dog  and  every  dog,  the  class  of 
dogs.  How  do  these  two  experienced  dogs, 
the  particular  and  the  general,  differ  psy- 
chologically? In  both  cases  you  may  have 
the  same  visual  image,  an  image  of  a  dog, 
and  every  image  is  in  itself  particular.  In 
the  case  of  the  concept,  however,  the  par- 
ticular image  is  associatively  connected 
through  learning  with  all  sorts  of  other 
images,  which  have  in  common  whatever 
learning  has  taught  you  to  believe  are  the 
essential  characteristics  of  dogginess.   Given 


Important  Tools  of  Thinking 


199 


a  chance,  a  ]jau.sc  in  the  thinking  process, 
a  challenge  as  to  whether  you  understand 
the  concept,  and  many  of  these  alternative 
images  will  actually  arise,  attesting  the  con- 
ceptual nature  of  the  item  of  thinking 
which  is  represented  consciously  at  the  mo- 
ment only  by  the  particular  image  of  the 
dog. 

The  main  thing  to  remember  in  this 
context  is  that  thinking  needs  to  use  gen- 
eralized concepts,  that  the  concept  is  neces- 
sarily represented  in  conscious  thinking  by 
some  particular  item,  like  an  image,  but 
that  the  concept  is  nevertheless  more  than 
a  particular  image  because  in  thinking  this 
image  plays  the  role  of  a  generalized  ab- 
straction. Thinking,  as  we  shall  see,  could 
not  go  on  without  the  great  economy  which 
generalization  makes  possible. 

(3)  Symbols  and  signs.  Thinking  also 
gains  economy  by  making  use  of  both  sym- 
bols and  signs.  Since  every  symbol  is  poten- 
tially a  sign,  and  every  sign  potentially  a 
symbol,  the  two  conceptions  must  be  con- 
sidered together. 
^A^s^yrnboljsja.  concrete  particular  item  in 
thinking  that  stands  for  something  more 
general.  A  particular  dog— seen,  imaged 
or  pictured— can  be  the  symbol  for  the  gen- 
eral concept  dog.  Concepts  are  usually  rep- 
resented in  thinking  by  symbols.  The 
word  tioo  is  a  symbol  for  the  concept  of 
duality,  and  2  is  another  symbol  for  the 
same  concept.  A  traffic  light,  perceived  or 
imagined,  may  be  a  symbol  of  police  power. 
The  symbol  is  simpler  and  more  easily  used 
than  the  generality  for  which  it  stands,  and 
the  employment  of  symbols  for  thinking 
also  contributes  enormously  to  the  econ- 
omy of  thinking. 

Symbols  tend  to  becomejS/g?7,y.  They  act 
as  signals  for  thinking  or  action,  as  stimuli 
for  conscious  or  motor  response.  The  traf- 
fic light  is  a  sign;   it  tells  us  what  to  do. 


The  symbol  for  multiplication  is  a  sign;  it 
also  tells  us  what  to  do.  Thinking  pro- 
gresses because  symbols  act  as  signs  and 
carry  the  thinking  pioccss  along. 

Symbols  and  signs  are  thus  seen  to  be 
the  pawns  and  pieces  with  which  the  great 
game  of  thinking  is  played.  It  could  not 
be  such  a  remarkable  and  successful  game 
without  them.  As  it  is,  by  letting  a  little 
symbol  act  for  a  large,  complex  and  clumsy 
concept,  we  can  think  quickly  and  effi- 
ciently. We  can  also  avoid  starting  our 
thinking  from  scratch.  The  original  un- 
derstanding of  a  concept  and  the  attach- 
ment of  a  symbol  to  represent  it  is  in  it- 
self often  an  elaborate  job  of  thinking,  but 
once  done  and  the  symbol  given  its  proper 
powers  as  a  sign,  the  thinking  does  not 
have  to  be  done  again.  We  use  the  symbol 
without  stopping  to  recollect  for  what  it 
stands,  and  we  use  it  as  a  sign  to  indicate 
the  processes  which  we  have  learned  belong 
to  it. 

Take  the  algebraic  symbol  of  involution. 
X",  the  raising  of  x  to  the  nth  power.  The 
exponent,  n,  written  as  a  superscript,  is  the 
symbol.  It  stands  for  a  generalization.  We 
learn  the  processes  of  squaring  and  cubing 
and  then  of  raising  numbers  to  other  pow- 
ers. Thus  we  get  the  meaning  of  involution 
attached  to  the  symbol.  We  must  grant  the 
symbol  the  greatest  generality.  It  means 
that  .V  could  be  raised  to  the  power  of  2.  3. 
510,  %,  ly,,  V2  or  ,r.  After 3:e  under- 
stand the  symbol,  we  no  longer  need  to  re- 
call the  vartous  processes  by  -ts-TiTch  it  ac- 
quired its  meaning.  Instead  we  need  to 
recognize  it  as  a  sign,  knowing  -ivhat  opera- 
tions it  indica.t£s_jn  tlie  process  of  think- 
ing. Mathematics  constantly  Builds  up 
symbols  for  the  relations  of  s\Tnbols,  cre- 
ating new  signs  and  proceeding  ever  at  a 
level  more  and  more  remote  from  the  par- 


200 


Recollecting,  Imagining  and  Thinking 


ticular   objects   whose   relationships   it   in- 
vestigates. 

Mathematics  is,  of  course,  a  highly  sym- 
bolic form  of  language,  but  in  principle  it 
does  not  differ  from  any  other  form  of  lan- 
guage. 

Language 

Language,  because  it  uses  symbols,  is  the 
best  medium  for  thinking.  Ordinarily  the 
symbols  are  words,  which,  of  course,  have 
meaning  and  readily  act  as  signs.  The 
words  can  be  spoken,  written  or  printed, 
or  fingered  in  the  manual  alphabet  that 
the  stone  deaf  use.  There  are  languages 
in  which  the  symbols  are  gestures,  the  ges- 
ture languages  of  the  Neapolitans  and  of 
the  North  American  Indians.  It  is  not  true 
that  man  alone  among  the  animals  has  lan- 
guage. Every  animal  with  a  conditioned 
response  is  reacting  to  a  symbol,  for  the 
conditioned  stimulus  is  a  symbol  of  the  un- 
conditioned stimulus.  The  dog  who  sali- 
vates when  he  hears  the  dinner  bell  under- 
stands the  meaning  of  the  bell,  which  has 
become  for  him  a  symbol  for  food.  When 
that  little  bit  of  language  has  been  built 
up  between  a  scientist  and  a  dog,  it  be- 
comes possible  for  the  dog  to  tell  the  scien- 
tist whether  long-continued  loud  noise  deaf- 
ens the  dog,  for  the  dog  can  say  "I  hear  the 
bell"  simply  by  salivating,  or  "I  do  not  hear 
any  bell"  by  not  salivating.  Human  lan- 
guage is  nothing  else  than  a  high  develop- 
ment of  such  symbolic  responses. 

Human  language  has  four  chief  func- 
tions. (1)  It  serves  to  communicate  ideas 
from  one  person  to  another.  That  is  its 
chief  social  function.  It  is  not,  however, 
its  only  function.  (2)  It  serves  to  persuade 
or  to  incite  others  to  action.  That  is  an- 
other social  function.  Persuasion  per  se  is 
not  communication.  Yelling  "Fire!"  when 
there  is  no  fire  may  incite  a  stampede  with- 


out directly  communicating  thought.  (3) 
Language  serves  also  to  relieve  tension  in 
the  speaker.  That  is  its  cathartic  finic  lion. 
Exclamations  and  profanity  may  ha\e  this 
purpose,  but  so  also  does  a  gieat  deal  .of 
unilateral  talk.  The  hypochondriac  who 
wants  to  tell  everyone  his  symptoms  is  try- 
ing less  to  get  understanding  or  action  in 
his  vis-a-vis  than  he  is  to  relieve  his  own 
frustration.  An  exclamation  can  be  used 
to  communicate,  to  let  others  know  how 
you  feel.  However,  Robinson  Crusoe 
doubtless  used  expletives  before  he  had  his 
man  Friday  to  talk  to,  because  the  condi- 
tioned response  of  talking  does  not  become 
easily  extinguished,  and  some  action  is 
needed  in  emotional  situations. 

Those  are  three  functions  of  language 
most  usually  cited,  two  of  them  social  and 
one  of  them  individual.  There  is,  how 
ever,  a  fourth  and  more  basic  function 
(4)  Language  is  used  as  a  tool  in  thinking. 
It  is  the  system  of  symbols  which  makes 
thinking  efficient.  Men  think  to  them- 
selves in  words.  An  argument,  a  discus- 
sion, an  exposition  is  developed  verbally, 
whether  an  audience  is  present  or  not. 
The  words  and  phrases  are  symbols,  and 
as  such  they  carry  with  them  meanings 
which  have  become  implicit  and  do  not 
have  to  be  expressed.  They  are  also  signs, 
and  as  such  they  indicate,  because  of  much 
past  conditioning,  the  proper  course  of 
thought.  Often  a  verbal  argument,  written 
or  spoken,  seems  to  develop  of  itself.  Even 
its  author  does  not  know  how  it  is  coming 
out.  He  lets  his  mouth  talk  while  he  lis- 
tens, or  he  lets  his  fingers  work  his  type- 
writer while  he  perceives  the  sentences  as 
they  form.  The  final  result  is  a  conclusion, 
one  that  is  quite  satisfactory  to  the  author, 
and  valid  as  far  as  he  can  see.  That  auto- 
matic factor  in  language  is  possible  because 
so  nuich  learning  precedes  its  acquisition. 


Language  and  Reading 


201 


IL  is  a  lad  llial  tliiiikiiij4  is,  lor  liic  mkjsI, 
part,  unconscious.  J  "lie  symbols,  actinf^  as 
signs,  carry  on  irom  symbol  to  symbol  with- 
out the  things  to  which  the  symbols  refer 
getting  themselves  represented  in  imagery. 
We  can  see  how  abbreviated  the  conscious 
processes  of  language  are  if  we  consider 
the  nature  of  reading. 

Reading 

The  child  at  first  reads  slowly  and  la- 
boriously. He  does  not,  if  he  is  well 
taught,  read  letter  by  letter;  he  reads  word 
by  word  or  phrase  by  phrase.  That  is 
what  you  too  do  in  learning  German  or 
French.  At  first  the  word  cat  will  evoke  its 
referent,  that  is  to  say,  the  child  will  per- 
ceive the  word  and  then  see  the  visual 
image  of  a  cat.  Soon,  however,  as  learning 
progresses,  the  symbol  comes  to  work  alone. 
There  is  not  time  in  reading  for  imagery 
of  the  referent  to  arise.  The  word  cat  acts 
properly  as  a  sign  without  arousing  any 
conscious  associates  at  all.  And  the  word 
Katz,  which  at  first  you  translated  into  the 
English  word  cat,  comes,  as  your  German 
improves,  similarly  to  act  alone  without 
this  extra  addition  of  translation. 

In  short,  you  know  much  more  than  you 
are  conscious  of.  You  can  read  a  simple 
clear  prose  passage  of  five  liundred  words 
tfirough  quickly  and  understand  it  per- 
fectly. Perhaps  the  preposition  by  oc- 
curred in  the  first  sentence,  and  the  passage 
would  have  been  altered  throughout  in  its 
meanings  if  the  word  had  been  to  instead 
of  by.  If  quizzed,  you  have  the  meanings 
correct.  So  you  must  have  perceived  by. 
Yet  you  do  not  remember  the  word,  you 
did  not  pause  to  pronounce  it  or  to  let  any 
imagery  arise  to  indicate  its  meaning.  You 
just  went  on  and  let  your  brain  take  care 
of  the  sense  for  you.  If  you  had  allowed  as 
little  as  a  second  to  become  conscious  of  the 


incaiiiiig  ol  cadi  ol  those  five  hundred 
words,  you  would  have  had  to  spend  about 
eight  more  minutes  on  the  passage,  and 
that  is  exactly  what  does  not  happen.  You 
can  read  without  pausing  because  the  syn> 
bols  arc  safe  substitutes  for  their  referents 

Since  children  learn  to  read  aloud,  pro 
nouncing  the  seen  word  when  reading  be- 
comes for  them  a  much  overlcarned  condi 
tioned  response.  Many  adults  who  can  get 
rid  of  all  other  associations  for  read  words, 
still  pronounce  them  or  at  least  form  the 
words  with  their  vocimotor  organs  as  they 
read.  After  much  reading  their  tongues 
get  tired!  This  translation  of  sight  into 
movement  and  kinesthesis  is  just  as  unnec- 
essary for  effective  understanding  as  is  the 
translation  of  every  German  word  into 
English  for  the  understanding  of  German. 
Skill  in  language  means  that  both  kinds 
of  translation  are  dispensed  with.  An 
adult  with  a  tired  i-eading  tongue  can  learn 
visual  reading  and  gain  enormously  in  effi- 
ciency. He  may  prefer  to  read  more  slowh 
and  pronounce  the  words  when  he  wishes 
to  appreciate  the  esthetic  beauty  of  prose 
or  poetry;  yet  for  the  tough  practical  busi- 
ness of  getting  as  much  sense  as  possible  as 
quickly  and  accurately  as  possible,  visual 
reading  is  the  correct  method. 

This  same  principle  applies,  of  course,  to 
the  use  of  arithmetic.  How  many  people 
can  set  themselves  to  add,  and  then,  seeing 
a  4  below  an  8,  can  at  once  image  a  12. 
without  wasting  time  to  say  "four  and 
eight  are  twelve"?  Yet  that  %vay  of  adding 
is  extremely  inefficient.  A  good  adder,  an 
expert  accountant,  can  perceive  an  8.  per- 
ceive a  4,  image  a  12,  perceive  a  9,  image 
a  21  and  so  run  his  eve  do^vn  the  column 
with  partial  sums  popping  out  in  imagerv 
as  he  goes  along,  and  he  could  even  learn 
to  whistle  while  he  adds. 

A  visual  reader  ought  not  to  be  able  to 


202 


Recollecting,  Imagining  and  Thinking 


see  sense  in  the  sentence:  "Two  beer  knot 
tube  bee  thought  is  thick  west  shun."  The 
slow-pronouncing  reader  will,  however,  de- 
tect a  familiarity  in  the  sound  as  he  forms 
it,  and,  if  he  repeats  the  sound,  with  his 
eyes  shut  or  his  attention  off  the  looks  of 
the  words,  he  will  discover  the  sense.  So 
too  with  "Pas  de  la  Rhone  que  nous." 

The  first  step  in  the  development  of  the 
understanding  in  reading  is  the  stripping 
off  of  these  conscious  contexts  from  words. 
The  second  is  for  the  words  themselves  to 
become  obscure,  and  the  imagery  for  which 
they  are  signs  to  occupy  attention.  Not 
only  can  you  understand  a  text  when  the 
meanings  of  the  words  do  not  arise  in  con- 
sciousness, but  you  also  can  understand  it 
when  the  words  do  not  have  time  to  be- 
come clear  in  detail.  What  happens  is 
that  symbolization  goes  farther.  A  part  of 
a  word  becomes  an  adequate  symbol  for 
the  whole  word.  That  is  why  errors  in 
printed  matter  are  so  hard  to  catch.  We  do 
not  always  see  the  whole  word.  Psycology 
seems  to  be  what  this  book  is  about. 

The  Problem  and  the  Set 

The  problem  determines  the  course  of 
thinking.  Thinking  is  aimed  at  a  goal,  a 
solution,  a  conclusion.  It  gets  somewhere 
or  attempts  to.  We  have  said  that  it  is  the 
symbols-become-signs  which  determine  the 
course  of  thinking,  but  there  is  no  incon- 
sistency here,  because  the  problem  is  the 
overlord  which  chooses  the  signs  that  oper- 
ate. The  problem  has  this  effect  because  it 
is  represented  by  a  set  or  attitude  that  it 
induces  in  the  thinker. 

This  matter  becomes  clearer  if  we  go 
back  to  the  experiments  on  set  and  attitude 
which  were  described  in  connection  with 
reaction  (pp.  60-62).  Reaction  closely  re- 
sembles thought  and  often  cannot  be  dis- 
tinguished from  it.    If  you  are  set  the  prob- 


lem to  press  a  key  when  you  see  a  green 
light  and  not  when  you  see  a  red  light,  and 
you  press  for  the  green  light,  you  are 
reacting  in  accordance  with  the  set  that  you 
have  taken  on  from  our  instruction.  If 
you  are  set  the  problem  to  decide  whether 
a  statement  is  true  or  false  and  are  given 
the  statement,  "To  give  every  man  his  due 
were  to  will  justice  and  achieve  chaos,"  and 
you  decide  that  the  statement  is  true  (or 
false),  you  have  done  some  thinking  in  ac- 
cordance with  the  set  which  you  have  ac- 
cepted from  our  instruction.  But  if  some- 
one flashes  this  statement  at  you  on  a  card 
in  a  stimulus-exposure  apparatus,  and  you 
call  out  True  or  False  as  your  decision  is, 
and  he  measures  the  reaction  time,  why 
then  surely  your  thinking  is  reacting. 

A  famous  experiment  on  set  was  per- 
formed by  Ach  in  1905.  He  showed  his 
subjects  pairs  of  digits,  one  below  the  other. 
Sometimes  he  asked  them  to  tell  him  the 
sinns  of  each  pair,  sometimes  the  differ- 
ences and  sometimes  the  products.  Those 
operations  depend  on  three  different  sets 
or  attitudes  which  his  subjects  could  take 
on  at  his  behest.  It  was  not  for  them  a 
matter  of  learning.  They  already  knew  all 
the  sums,  differences  and  products  perfectly. 
The  discovery  in  Ach's  experiment  was  that 
any  one  of  the  three  kinds  of  answer  could 
be  obtained  from  an  unconscious  set. 
Asked  for  stuns,  the  subjects  gave  sums 
without  even  remembering  consciously  that 
it  was  sums  they  were  to  think  of  and  not 
differences  or  products.  Set  for  sums,  they 
got  no  differences  or  products.  Then,  with 
the  very  same  pairs  of  digits,  the  subject 
at  a  word  could  be  reset  for  differences,  or 
for  products,  and  get  only  what  the  set 
called  for.  As  a  matter  of  fact  Ach  held 
that  his  experiments  were  actually  an  in- 
vestigation of  thought,  and  these  arithmet- 
ical reactions  are  indeed  simple  thinkings. 


Trial-and-Error  and  Insight 


203 


Ach  called  the  set  a  detennining  tend- 
ency and  he  said  (hat  progress  ol  thought 
is  set  by  a  determining  tendcnc  y  toward  the 
ideated  goal.  Since  set,  attitude,  need  and 
determining  tendency  are  similar  concepts, 
this  book  gets  along  by  using  the  first  three 
terms  but  omitting  Ach's. 

The  notion  ol'  set  as  dcternu'ning  ac  lion 
and  thought  is  further  ilhistrated  l)y  exam- 
ples. In  the  morning  you  decide  that  you 
need  a  certain  book  from  the  library  and 
that  you  will  stop  for  it  on  the  way  down- 
town. Then  you  forget  all  about  this  de- 
cision. Yet  as  you  pass  the  library  you  find 
yourself  turning  in,  and  you  wonder  for 
a  moment  why  you  are  entering  the  library. 
Presently  you  recollect  your  original  deci- 
sion. In  thinking  the  same  soit  of  phe- 
nomenon occurs  continually.  Many  scien- 
tists and  inventors  have  described  this  phe- 
nomenon of  'incubation'  in  thinking.  The 
solution  of  a  baffling  problem  suddenly  oc- 
curs to  the  thinker  when  he  is  thinking 
about  something  else. 

Trial-and-Error  and  Insight 

We  have  ahead)  seen  how  animals  sohe 
problems  by  trial-and-error  and  by  insight. 
Thorndike's  cat  in  the  puzzle  box  (p.  145) 
escaped  to  get  food  by  trying  this  and  trying 
that,  and  finally  hitting  upon  the  right 
movement.  A  rat  in  an  alley  maze  cannot 
possibly  get  to  his  food  by  insight.  He  does 
not  know  where  the  food  is  and  he  has  to 
try  and  try  again  until  he  finds  it.  On  the 
other  hand,  a  rat  that  can  see  before  him 
the  paths  of  an  elevated  maze  may  solve 
his  problem  by  insight  and  without  trials 
that  end  in  errors.  He  examines  the  situa- 
tion and  picks  the  correct  path  to  the  food, 
provided  the  maze  is  very  simple.  The 
chimpanzee  that  tries  to  get  the  banana 
from  beyond  the   fence   (p.    152)  tries  and 


errs,  tries  and  errs,  and  then,  when  he  real- 
izes that  the  two  sticks  will  fit  together 
to  make  a  long  one,  a  flash  of  insight  gi\cs 
liim  ific  solutif>n.     (See  Fig.  7.^.) 


■ 

>     1 

1            ir'*^**^ -*i»* 

<%- 

FIGURE    73.       insight:     CHIMPANZEE    PUTTING    TO- 
GETHER   A    DOUBLE    STICK 

Having  discovered  that  the  two  sticks  would  go 
together  to  make  one  long  stick,  the  ape  took  the 
long  stick  at  once  to  the  other  side  of  his  cage  and 
secured  a  banana  outside  the  bars  and  too  far  awav 
to  be  got  bv  either  short  stick  alone.  [Comtesy  of 
^V.  Kohler.] 

Human  thinking  is  not  different.  The 
thinker,  faced  with  a  problem,  tries  for  a 
solution.  He  keeps  on  until  a  trial  is  suc- 
cessful. Many  of  his  errors  are  errors  of 
insight,  false  insights  that  come  as  inspira- 
tions and  do  not  sohe  the  problem.  His 
final  success  may  be  an  act  of  true  insight, 
or  it  may  be  a  blind  success,  as  Avhen  tlie 
puzzle  finally  comes  apart   in  your  hands 


204 


Recollecting,  Imagining  and  Thinking 


and  you  ha\c  no  idea  wliat  it  was  you  did 
to  get  it  apart. 

If  tlie  problem  is  simple  and  the  solution 
has  already  been  learned,  then  there  need 
be  no  errors  and  no  insight.  You  want  to 
know  the  sum  of  4  and  8;  you  appeal  under 
the  set  for  addition  to  past  learning;  and 
the  answer  is  before  you,  12. 

You  want  to  decide  whether  a  novel 
proposition  is  true  or  false.  Past  learning 
is  not  going  to  be  enough  to  decide  the 
issue  for  you  without  insight.  This  is  a 
brand  new  proposition  and  you  need  a  little 
time,  perhaps  several  seconds,  to  think. 
Images  come  up,  and  then  presently  some 
insight  into  the  relations  of  the  concepts 
decides  you,  and  you  make  your  judgment. 

You  have  a  puzzle  to  solve.  The  block  at 
the  upper  right  corner  must  be  moved  to 
the  lower  left  corner.  You  can  work 
blindlv  with  trial-and-error,  and  you  may 
indeed  solve  the  problem  thus,  though  you 
will  not  have  learned  it  and  cannot  do  it 
again.  Or  you  may  study  the  situation, 
form  an  hypothesis,  try  it  out,  find  that 
it  does  not  work,  try  out  another  hypothe- 
sis and  continue  in  this  fashion  until  one 
hypothesis  or  a  series  of  partial  hypotheses 
give  the  required  solution.  This  is  trial- 
and-error  thinking,  but  it  is  also  insightful 
thinking  because  the  hypotheses  are  formed 
by  insight  and  abandoned  when  found  in- 
adequate. 

Here  is  a  simple  example  that  shows  how 
problems  get  solved.  Suppose  that  your 
alarm  clock  has  stopped.  You  may  first  use 
blind  trial-and-error.  You  shake  it,  ti7  to 
wind  it  some  more,  shake  it  again,  turn  it 
upside  clown,  change  the  setting  and  so  on. 
So  far  you  have  used  methods  which  some- 
times work,  but  you  have  shown  little  in- 
sight into  the  problem.  Finally,  having  ex- 
hausted these  possibilities,  you  open  the 
case.     You  notice  that  the  hair  spring  has 


been  tangled,  apparently  because  the  clock 
lias  been  dropped.  At  that  point,  believ- 
ing that  you  have  the  solution  of  the  dif- 
ficulty, you  untangle  the  hair  spring,  and 
the  clock  begins  to  run.  You  piu  it  back 
together  again,  and  the  clock  stops  again. 
Your  first  insight  may  have  been  correct, 
but  it  was  inadequate.  You  need  to  know 
something  more.  So  you  reopen  the  clock, 
find  that  the  shaft  of  the  balance  wheel  is 
out  of  place  and  replace  it— another  insight- 
ful trial.  You  put  the  clock  together,  and 
it  runs.  Success  stops  your  thinking,  just 
as  satisfaction  stops  a  need. 

Trial-and-error  without  insight  would  be 
the  case  if  your  clock  stops,  you  take  it 
apart,  see  nothing  the  matter  with  it,  put 
it  together  again  and  find  that  it  runs. 

There  are  problems  in  which  trial-and- 
eiTor  does  not  help  and  in  which  one  cor- 
rect act  of  insight  is  enough.  For  instance, 
there  is  a  ring  problem,  with  two  rings, 
each  on  a  loop  of  cord.  The  ends  of  the 
cord  are  fastened  permanently  to  a  stick, 
and  the  cord  is  also  looped  about  the  stick 
through  a  hole  in  a  special  manner.  The 
problem  is  to  get  the  two  rings  on  the 
same  loop.  Blind  trial-and-error  seldom 
helps.  It  gets  the  puzzle  tangled  up  and 
makes  solution  difficult  or  impossible.  In- 
spection of  the  situation  shows  that  you 
must  pass  the  ring  along  the  cord,  through 
a  hole  in  the  stick,  aroimd  a  loop  of  the 
cord  and  then  back  through  the  same  hole; 
but  the  hole  is  smaller  than  the  ring,  and 
the  ring  cannot  go  through  it.  Able  scien- 
tists have  worked  for  hours  on  this  prob- 
lem, but  the  solution  comes  in  a  single 
flash  of  insight.  You  cannot  put  the  ring 
through  the  hole  to  pass  it  around  the  loop, 
but  you  can  pull  the  loop  through  the 
hole  to  the  ring,  pass  the  ring  around  it 
and  then  push  the  loop  back.  The  neces- 
sary insight  is  as  simple  as  that;  if  you  can- 


Trial-and-Error  and  Insight 


205 


not  gel  llic  ling  lo  tlie  loop,  yon  innst  bi  ing 
the  loop  to  the  ring. 

Insight  is  not  always  either  false  or  ade- 
quate. Sometimes  it  is  imperfectly  ade- 
quate. The  chimpanzees  of  Kig.  74  were 
solving  the  problem  of  getting  the  banana, 
suspended  near  the  top  of  their  cage,  by 
piling  boxes  on  top  of  one  another  and 
climbing  up  on  the  pile.  As  the  figure 
shows,  they  could  solve  the  problem  when 
three  boxes  were  necessary  in  the  pile,  but 
they  never  learned  the  mechanics  of  ecpii- 
librium.  Their  rickety  piles  often  fell  over, 
or  else  tlie  apes  balanced  j^erilonsly  on 
them  as  they  tottered. 

When  a  rat  begins  to  know  the  correct 
pa  til  through  a  maze,  he  may  come  to  a 
place  where  he  must  choose,  look  down  the 
wrong  alley  and  then  abandon  it  for  the 
correct  path.  This  behavior,  since  it  is  not 
actually  an  error,  has  been  called  vicarious 
trial-and-error.  Human  thinking  makes 
liberal  use  of  vicarious  trial-and-error. 
You  form  your  hypothesis,  examine  it  and 
then  abandon  it  as  inadequate,  without  try- 
ing it  out  on  the  actual  problem. 

Sometimes  it  has  been  said  that  solving  a 
problem  by  trial-and-error  and  by  insight 
are  different  and  opposed  methods  of  think- 
ing. Such  a  statement  is  obviously  false. 
Trial-and-error  is  what  happens  in  certain 
kinds  of  learning  and  certain  kinds  of 
thinking;  but  we  learn  by  trial  and  success, 
and  we  solve  problems  by  trial  and  insight. 

What  is  the  way  to  solve  a  problem?  (a) 
Inspect  the  situation,  study  it  carefully,  ex- 
amine it.  [b)  If  you  find  you  know  the 
answer,  the  problem  is  solved,  (c)  If  you 
do  not  know  the  solution,  you  continue 
your  examination,  hoping  for  an  adequate 
insight,  {d)  If  the  insight  comes  and  is 
adequate,  the  problem  is  solved.  If  it  is 
inadequate,  you  continue  hoping.  (e) 
AVhen   it  becomes  apparent   that   the  data 


necessary  for  insight  are  not  available  to 
your  inspection,  you  begin  with  trials,  ran- 
dom trials  if  you  have  nf>  insight  at  all  to 


FIGURE  74.    problem-solving:  chimpanzee  stacks 

BOXES    to    reach    THE    B.-VNANA    SUSPENDED    .ALOIT 

The  ape  solves  this  problem  but  does  not  le.Tin 
to  pile  the  boxes  securely  on  top  of  one  anoiher. 
The  other  ape,  watching,  makes  a  sympathetic  ges- 
ture with  his  left  hand.  [From  \V.  Kohler.  Men- 
tality of  apes,  Harcourt,  Brace.  1927,  Plate  I\'.] 

guide  you,  like  a  cat  in  a  box  ■with  escape 
dependent  on  her  toudiing  an  object  which 
the  experimenter  has  selected.  The  cat 
does  not  kno^v  the  experimenter's  sea"et. 
whicli  is  arbitrar\  and  not  open  to  insight. 


206 


Recollecting,  Imagining  and  Thinking 


Blind  tiial  is  the  only  possible  method.  (/) 
As  trials  alter  the  situation,  insight  may 
become  possible,  and  the  problem,  partly 
solved,  may  then  be  attacked  at  stage  (r) 
or  even  stage  (a). 

Blind  trying  is  inferior  to  insight,  but  it 
is  better  than  nothing;  and  insight  is  not 
always  possible.  Most  complex  thinking 
makes  use  of  actual  trials,  vicarious  trials, 
insights,  successes  and  partial  solutions,  as 
thinking  continues  to  the  final  solution. 

INCORRECT    THINKING 

Thinking  may  completely  fail  to  solve 
its  problem.  That  is  the  safe  kind  of  fail- 
ure, because,  since  it  does  not  give  satis- 
faction, the  frustrated  thinker  continues  to 
address  himself  to  the  task  of  finding  a  so- 
lution or  else  abandons  the  problem  with 
no  false  belief  tliat  he  has  solved  it. 

Thinking  may,  however,  fail  by  being  in- 
correct, and  the  thinker  may  accept  a  false 
conclusion  as  true,  experiencing  the  relief 
of  resolved  frustration.  That  is  a  danger- 
ous event  in  thinking,  for  it  lulls  the  thinker 
into  a  false  sense  of  security. 

In  this  section  we  consider  some  of  the 
ways  in  which  incorrect  thinking  takes 
place  and  some  of  the  reasons  why  it  occvns. 

Fallacies 

Textbooks  of  logic  expoimd  the  nature 
of  fallacies.  Although  logic  is  not  psychol- 
ogy, correct  thinking  must  not  contravene 
the  logical  canons.  Everyone  ought  to 
know  the  nature  of  the  common  fallacies  of 
thinking,  but  this  book  is  not  the  place  to 
set  them  forth.  We  must  content  ourselves 
with  a  single  example  from  science,  the 
failure  to  'control'  conclusions. 

A  personnel  expert  in  a  factory  writes: 
"We  have  been  trying  out  a  new  means 
for  reducing  absenteeism  in  the  plant.     It 


has  turned  out  to  be  very  good.  Absentee- 
ism has  dropped  twenty  per  cent  during 
the  six  weeks  the  new  method  has  been  in 
use."  That  sounds  right,  doesn't  it?  You 
vary  x  (the  method)  and  you  get  a  con- 
comitant change  in  y  (absenteeism),  so  y  is 
a  function  of  x.  Perhaps.  Life  in  a  fac- 
tory is,  however,  a  very  complex  affair,  and 
a  personnel  expert,  if  he  is  an  expeit, 
woidd  want  better  evidence  before  he 
reached  that  conclusion.  Absenteeism  var- 
ies for  many  different  reasons.  How  does 
this  expert  know  that  it  is  the  new  method 
which  is  reducing  absenteeism?  Some 
other  factor  might  be  at  work— the  weather, 
the  season,  the  fading  out  of  an  epidemic, 
a  factor  that  arises  from  within  the  factory 
itself.  He  should  have  had  a  control  (p. 
14).  Perhaps  he  could  have  divided  his 
workers  into  two  groups,  using  the  new 
method  for  tlie  test  group  and  the  old 
method  (or  lack  of  method)  for  the  control 
group.  If  the  test  group  and  the  control 
group  showed  the  same  decrease  in  ab- 
senteeism, he  would  know  that  the  new 
method  was  not  working,  or  conversely. 

The  fallacious  thinking  that  arises  from 
lack  of  control  is  similar  to  what  is  called 
the  fallacy  of  tlie  single  instayice.  Think- 
ers not  trained  in  scientific  research,  often 
men  in  public  affairs,  accept  this  fallacy 
easily.  You  can  never  safely  draw  a  gen- 
eral conclusion  from  a  single  instance. 
Any  obsei'ved  concomitance  of  events  could 
happen  for  many  different  reasons  or  by 
chance.  You  must  repeat  the  concurrence 
again  and  again,  keeping  what  you  think  is 
important  the  same  and  letting  everything 
else  vary.  Only  in  that  way  do  you  at  last 
become  secure  in  concluding  that  a  gener- 
alization holds.  If  rats  always  have  been 
found  to  speed  up  toward  the  end  of  a 
maze,  you  can  begin  to  talk  about  a  goal 
gradient.    A  great  economic  depression  fol 


Incorrect  Thinking 


207 


lowed  the  election  of  Hoover  as  Presideiii 
of  the  United  States.  That  is  a  single  in- 
stance. Did  Hoover  cause  the  depression? 
It  is  (|uite  iiiij)ossible  to  say  until  you  have 
tried  electing  Hoover  under  a  number  of 
different  economic  (ondiiions. 

Wishful  Thinking 

Opinions  and  attitudes  are  affected  liy 
wishes  and  prejudices  and  tend  to  accord 
with  what  the  thinker  desires.  The  course 
of  thinking  is  biased  by  desire  and  need. 
(This  matter  is  discussed  more  fully  on 
pp.  603-613.) 

You  find  wishful  thinking  in  politics,  in 
courts  of  law,  in  science,  in  everyday  social 
relations.  Wherever  controversy  exists, 
there  men  try  to  prove  themselves  right,  in- 
stead of  trying  to  find  out  the  truth.  Wish- 
ful thinking  is  so  insistent  when  important 
human  needs  are  involved  that  the  law 
makes  a  virtue  of  necessity  and  lets  the  op- 
posing lawyers  show  how  good  their  contra- 
dictory biases  can  make  their  cases,  while 
the  judge  tries  to  transcend  bias  and  re- 
main impartial.  Scientists  try  to  be  im- 
partial judges,  but  scientific  controversy, 
the  unwillingness  to  accept  the  possibility 
of  their  own  past  mistakes,  shows  that  ego- 
tism may  control  the  scientists  too.  We 
take  pride  so  much  for  gianted  that  we 
hardly  expect  a  man  to  think  correctly  if 
the  right  conclusion  to  his  thought  would 
be  humiliating  to  him. 

Hunches 

A  hunch  is  an  imperfect  insight.  Your 
guess  that  a  relationship  might  be  true 
seems  right  to  you,  and  yet  you  lack  the 
evidence  to  validate  your  guess.  That  is  a 
hunch.  The  hypotheses  and  insights  of 
trial-and-error  thinking  are  often  such 
hunches.  A  hunch  should  always  be  used 
as  a  tentative  conclusion  to  be  tested  out. 


It  becomes  a  lorm  of  intorrect  thinking 
only  when  it  is  accejjled  wiifiout  subsc- 
<|uent  validation. 

On  the  other  hand,  it  may  be  said  that 
human  action  is  based  on  a  very  large  nuni- 
Inr  of  incorrect  conclusirjns,  ccjnclusicjns 
tliat  may  never,  during  the  lifetime  of  the 
person  who  uses  them,  be  recogni/ed  as  in- 
correct. The  history  of  thought  abcjut  dis- 
eases and  their  cures  is  full  cjf  such  incc)r- 
rect  beliefs.  Every  day  every  man  makes 
hundreds  of  decisions  that  are  based  upon 
inadecjuately  validated  opinions  which  he 
holds  to  be  facts.  When  a  hunch  is  held 
to  firmly  and  we  are  sure  that  it  is  incor- 
rect, we  name  it  a  siiperstilion.  People 
who  bet  on  horse  races  have  to  use  hunches 
(or  superstitions)  because  they  have  not 
enough  else  to  use;  they  are  taking  action 
in  the  absence  of  adequate  information. 

Word  Fallacies 

The  commonest  trouble  into  which  lan- 
guage can  get  your  thinking  arises  from 
the  same  word's  having  several  difl:ereni 
meanings.  The  meaning  shifts  as  thought 
progresses  from  one  sense  in  the  premise 
to  another  in  the  conclusion.  Said  one 
newly  naturalized  immigrant:  "Of  course 
I'll  vote  Democratic.  This  country's  a  de- 
mocracy, isn't  it?  They  told  me  so  when  I 
was  studying  to  be  a  citi/en."  And  then 
there  is  the  old  joke  from  the  Victorian 
era:  "A  piece  of  bread  is  better  than  noth- 
ing; nothing  is  better  than  Heaven:  there- 
fore a  piece  of  bread  is  better  than 
Heaven." 

These  are  crude  examples.  The  modern 
science  of  semantics  studies  the  meanings 
of  words,  showing  how  often  thought  is 
falsified  because  the  meaning  of  a  word 
shifts  without  the  thinker's  knowing  that 
it  has.  \Vc  arc  advised  ahva^s  to  be  aware 
of  the  referents  ^^•hich  a  ^vord  has  as  de- 


208 


Recollecting,  Imagining  and  Thinking 


fining  its  meaning,  but  that  advice  must 
not,  of  course,  be  taken  too  literally.  Lan- 
guage gets  its  efficiency  from  the  fact  that  it 
uses  words  without  their  meanings  having 
to  become  explicit.  We  have  to  trust  lan- 
guage, in  spite  of  the  ways  in  which  it  be- 
trays us,  becoming  critical  only  when  we 
find  that  our  thinking  is  not  working  ac- 
cinately. 

There  is  also  luord  magic,  the  belief  that 
when  an  unknown  thing  or  event  is  named 
it  is  understood.  Labeling  tends  to  allay 
thinking.  The  lazy  thinker  is  content  with 
a  name  or  with  a  classification  which  nam- 
ing establishes.  Such  naming  is  useful  and 
safe  when  the  object  named  is  understood. 
"That  noise  is  a  burglar."  There  is  a 
classification  of  a  noise  that  could  properly 
incite  to  action.  But  naming,  when  it  adds 
no  new  information  except  the  name,  is  a 
delusion  if  it  is  mistaken  for  thinking. 
"Why,"  says  someone,  "do  you  notice  de- 
tails so  much  better  than  I?  I  suppose 
your  perceptive  faculty  must  be  better." 
Noticing  detail  is  perceiving  better.  Yet 
many  a  would-be  thinker  gets  satisfaction 
from  such  redundant  thinking. 

Motivation 

One  of  the  most  potent  causes  of  failure 
and  error  in  thinking  is  so  obvious  that  it 
is  usually  overlooked.  Thinking  takes 
time,  and  it  requires  effort;  the  thinker  has 
to  be  strongly  moti\ated.  Errors  occur  be- 
cause he  does  not  have  time  or  inclination 
for  complete  and  careful  analysis  of  the 
problem.  He  takes  short-cuts  and  jumps 
to  conclusions.  He  gives  up  as  soon  as  he 
comes  to  a  point  of  serious  difficulty. 

This  state  of  affairs  is  especially  marked 
in  our  thinking  upon  political  and  social 
affairs.  Careful  assessment  of  the  relative 
merits  of  political  parties  requires  an  anal- 
ysis of  a  mass  of  information  which  must 


be  sought  out  from  books,  periodicals  and 
newspapers.  Some  of  the  essential  infor- 
mation may  not  even  exist.  Political  prop- 
aganda, moreover,  is  so  phrased  that  it 
never  suggests  the  possibility  of  thinking 
out  political  problems.  No  wonder  think- 
ing upon  these  topics  is  so  rare. 

Tacit  Assumptions 

The  set  or  attitude  under  which  a 
thinker  undertakes  to  solve  a  problem  may 
involve  certain  tacit  assumptions  of  which 
the  thinker  is  wholly  unaware.  Very  often 
these  assumptions  prevent  him  from  solv- 
ing the  problem,  because  they  exclude  from 
his  consideration  the  hypothesis  which  is 
necessary  for  his  success. 

For  example,  consider  this  laboratory 
study  of  thinking.  The  experimenter  gave 
the  subjects  a  string  of  beads,  on  which  two 
small  white  beads  were  alternated  with  one 
large  yellow  one.  In  the  middle  portion, 
however,  there  were  five  white  beads  sep- 
arating two  yellow  ones.  The  instructions 
were:  "Make  a  single  regularly  repeated 
pattern  without  either  unstringing  or  re- 
stringing  the  beads,  and  without  knotting 
or  breaking  the  thread."  On  the  table 
were  many  assorted  objects,  including  a 
bottle  of  glue,  a  saw,  pliers,  and  needles. 
Most  of  the  subjects  took  some  time  to 
reach  a  solution  of  the  problem,  and  some 
failed  altogether  to  solve  it.  The  only  pos- 
sible solution  available  was  to  break  the 
extra  beads  with  the  pliers.  It  did  not  oc- 
cur to  the  subjects  who  failed  that  the 
beads  might  be  destroyed,  even  though  the 
instructions  did  not  explicitly  forbid  it. 

Figure  75  is  the  horse-and-rider  puzzle. 
The  thinker  is  given  two  pieces  of  paper  or 
cardboard,  one  square  with  the  two  horses 
printed  on  it,  the  other  a  strip  with  the 
two  riders  printed  on  it.  He  is  told  to  put 
the  riders  on  the  horses  without  injuring 


Incorrect  Thinking 


209 


the  two  pieces  in  any  way.  At  fust  solution 
seems  impossible.  The  riders  would  be  up- 
side down  on  the  horses  and  not  adjusted 
to  the  horses'  bodies.  Solution  is,  however, 
possible,  and  it  may  come  by  blind  trial, 
error  and  success  or  by  insight.     In  Fig.  76 


^w^i.-p'i 


FIGURE    75.       HORSE-AND-RIDER    PUZZLE 

The  Strip  with  the  two  riders  on  it,  B,  must  be 
superposed  on  the  square  with  the  two  horses  on  it, 
A,  so  that  the  riders  will  appear  in  proper  positions, 
each  astride  a  horse.  (Do  not  break,  bend  or  tear 
the  two  pieces.)  [From  Amer.  J.  Psychol.,  1941,  54, 
437  f,  by  M.  Scheerer,  K.  Goldstein  and  E.  G. 
Boring.] 

the  two  pieces  are  shown  together,  with  the 
strip,  B,  superposed  upon  the  square,  A. 
How  is  that  possible?  You  turn  the  square 
through  90  degrees,  so  that  one  rider  rides 
the  head  and  forelegs  of  one  horse  and  the 
tail  and  hind  legs  of  the  other.  That  is  an 
utterly  unexpected  kind  of  a  solution.  All 
your  tacit  assumptions  are  against  it. 

Some  of  these  results  may  be  a  function 
of  the  experimental  setting.  If  the  prob- 
lem had  arisen  in  the  course  of  everyday 
events,  the  tacit  assumption  might  never 
have  arisen.  Nevertheless,  these  examples 
are  important  because  similar  unrecognized 
assumptions  occur  constantly  in  the  every- 
day course  of  thinking.  In  industrial  pro- 
duction, for  example,  there  are  numerous 


situations  in  which  tacit  assumptions  pre- 
vent the  development  of  better  rncthod.s  of 
doing  a  job.  Operation  A  has  always  pre- 
ceded operation  li,  so  everyone  assumes 
that  the  order  cannot  be  changed.  The 
workers  make  this  a.ssumption  without  ever 
considering  the  need  for  it.  To  combat 
such  mistaken  assumptions  it  has  been 
necessary  to  develop  special  techniques  like 
time  and  motion  studies,  which  locate  the 
accepted  but  inefficient  prrjcedures.  (See 
pp.  470-472.) 


FIGURE  76.      HORSE-AND-RIDER  PUZZLE:    SOLUTION 

This  figure  was  made  by  photographing  the  strip, 
B,  of  Fig.  75  lying  on  top  of  the  square.  A,  of  Fig. 
75.     Can  you  see  how  it  was  done? 

Atmosphere  Effect 

Sometimes  mistakes  in  thinking  occur 
because  unrecognized  and  unconscious  fac- 
tors attach  the  sense  of  conviction  to  a  false 
conclusion  which  convinces  the  thinker 
that  his  problem  is  solved— when  it  is  not 
In  the  case  of  the  problem  of  absenteeism 
mentioned  above,  the  personnel  expert 
could  have  said  correctly  (and  it  was  prob- 
ably unconsciously  in  his  mind):  "If  tlie 
new  method  is  a  good  one,  its  use  will  be 
followed  by  a  reduction  in  absenteeism." 
WlvAt  he   did   sa^    is   the   converse   of   this 


210 


Recollecting,  Imagining  and  Thinking 


statement,  a  converse  that  is  not  necessarily 
true:  "If  the  new  method  is  followed  by  a 
reduction  in  absenteeism,  it  is  a  good  one." 
The  one  statement  creates  an  atmosphere 
in  which  the  second  statement  appears  to 
be  equivalent  and,  therefore,  as  true  as  the 
first. 

The  atmosphere  effect  is  sometimes  pres- 
ent in  syllogistic  reasoning.  When  you 
reason  from  a  major  and  minor  premise  to 
a  conclusion,  a  conclusion  containing  the 
Avord  all  tends  to  be  accepted  as  correct 
when  both  premises  also  contain  all.  Thus: 
"All  X's  are  Y's.  All  X's  are  Z's.  There- 
fore all  Y's  are  Z's."  The  conclusion  is 
a  non  sequitur,  but  it  will  be  accepted  by 
many.  It  is  easy  to  see  the  fallacy  when 
it  asserts  a  conclusion  that  we  know  to  be 
wrong.  Thus:  "All  dogs  are  mammals. 
All  dogs  have  four  legs.  Therefore  all 
mammals  have  four  legs:  [or]  all  four- 
legged  animals  are  mammals."  Atmos- 
phere does  not  stifle  knowledge,  but  it  does 
seduce  ignorance. 

Atmosphere  also  affects  opinions  and  at- 
titudes. That  fact  becomes  clear  in  the 
questionnaire  studies  of  the  values  which 
people  hold.  The  effects  are  very  subtle. 
The  way  a  question  is  worded  may  change 
utterly  the  frequencies  of  the  different  an- 
swers to  it  in  a  public  opinion  poll.  (See 
pp.  580-584.) 

Habitual  Methods  of  Attack 

Correct  thinking  is  limited  by  the  habit- 
ual methods  of  attack  that  the  thinker  em- 
ploys. That  these  methods  are  arbitrary 
and  may  not  be  the  only  possible  methods, 
the  thinker  is  usually  not  aware.  Like 
tacit  assumptions  and  atmosphere  they  con- 
stitute for  his  thinking  a  limitation  of 
which  he  is  usually  unconscious  and  which 
he  is  therefore  not  likely  easily  to  change. 

One  kind  of  a  problem  will  be  translated 


almost  at  once  by  one  person  into  an  alge- 
braic equation.  Another  person  will  try 
to  solve  the  same  problem  by  a  diagram. 
Problems  in  plane  geometry  call  for  dia- 
grams and  construction  figures,  but  multi- 
dimensional geometries  seem  to  require 
algebraic  expressions.  A  detective  problem 
can  be  solved  by  systematic  logic  or  by  in- 
sight. Some  psychologists  like  to  put  psy- 
chological problems  into  terms  of  stimulus 
and  response  and  always  to  envision  hiunan 
phenomena  as  they  would  exist  in  animals 
or  even  in  robots.  Others  like  to  stick  to 
the  terms  of  experience  and  the  data  of 
consciousness.  Methods  of  attack  differ  for 
different  individuals. 

If  the  thinker  is  accustomed  to  use  one 
method,  it  is  not  likely  to  occur  to  him 
that  the  method  may  be  inefficient  in  a 
given  case  or  even  inapplicable.  He  will 
go  ahead  with  the  old  familiar  method  in- 
stead of  looking  for  a  new  one.  The  most 
successful  problem  solvers  are  those  per- 
sons who  are  constantly  on  the  lookout  for 
new  methods  and  on  guard  against  the  in- 
efficient use  of  habitual  action  in  novel 
situations. 

A  famous  psychologist  who  investigated 
the  nature  of  thinking— his  name  was  Max 
Wertheimer— once  posed  this  problem.  ^Ve 
have  a  simple  organism— an  amoeba— which 
multiplies  by  division  into  two  once  every 
three  minutes.  Every  new  organism  re- 
divides  every  three  miniUes.  We  place  a 
single  amoeba  in  a  jar  and  we  find  that  the 
jar  is  filled  with  amoebae  in  one  hoin\ 
How  long  will  it  take  to  fill  the  jar  if  we 
start  with  two  amoebae  instead  of  one? 
Wertheimer  found  that  his  friends  who 
were  accustomed  to  the  use  of  mathemati- 
cal procedures  would  start  in  at  once  to 
work  oiU  geometrical  progressions  in  un- 
dertaking to  answer  this  question.  Il  rc- 
(juircs   a   great    deal   of  ^vork    to   reach    llie 


Incorrect  and  Correct  Tbink'mg 


211 


answer  in  this  way,  but  not  much  work  or 
time  by  a  simple  insight.  The  student 
with  this  admonition  and  a  little  thought, 
with  no  fornuilas  and  no  paper  and  pen- 
til,  should  be  able  to  give  the  answer  with 
assurance,  provided  only  he  can  subtract 
and  knows  how  many  minutes  there  are  in 
an  hour. 

Faulty  Transfer  of  Method 

A  frequent  source  of  error  or  failure  in 
thinking  is  the  use  of  a  method  which  is 
not  adapted  to  the  problem  at  hand.  There 
is  also  the  tendency  to  take  over  for  a  new 
problem  some  superficial  aspect  of  a  meth- 
od successful  in  a  different  problem,  while 
overlooking  its  fundamentally  important 
feature.  Another  example  of  Wertheimer's 
will  make  this  matter  clear. 

In  one  case  children  had  been  previously 
taught  to  prove  a  theorem  about  the  area 
of  a  rectangle  by  dividing  the  rectangle 
into  unit  squares.  By  this  process  they 
found,  of  course,  that  the  area  was  the 
product  of  the  two  sides.  Then  the  chil- 
dren were  given  the  problem  of  finding 
the  area  of  a  parallelogram.  Some  of  them 
applied  the  method  used  before  in  a  com- 
pletely blind  manner.  They  divided  the 
parallelogram  up  into  smaller  parallelo- 
grams—which did  not  help  them  at  all. 
They  had  transferred  to  a  new  problem  a 
feature  of  the  old  method,  but  it  was  only 
a  superficial  aspect.  They  had  failed  to 
grasp  the  important  part  of  the  original 
method  for  finding  the  area  of  a  rectangle, 
having  learned  to  use  the  method  mechani- 
cally without  really  understanding  it. 

Wertheimer  blames  conventional  and  un- 
imaginative teaching  for  the  fact  that  many 
children  rely  on  this  blind  and  superficial 
transfer.  He  complains  that  the  schools 
stress  drill  too  much  and  insight  not 
enough.    The  child,  after  being  shown  how 


to  do  one  kind  of  problem,  practices  by 
using  the  method  upon  essentially  the 
same  problem.  Little  is  changed  but  the 
numbers  and  arithmetic  involved.  This 
kind  of  drill  may  blind  the  pupil  to  the 
essential  principles  involved  in  the  proce- 
dure. y\t  any  rate  drill  is  not  the  way  to 
learn  to  be  alert  for  novel  relationships. 
Too  drilled  a  child  may  lose  the  fun  of 
learning  to  think. 

Individual  Differences 

Certainly  some  persons  are  better  thinkers 
than  others.  They  are  more  alert  to  the 
perception  of  novel  relations,  to  getting  in- 
sight. They  follow  habitual  procedures 
less  inflexibly  when  insight— or  a  hunch- 
shows  an  alternative,  possibly  better  way. 
They  like  problems,  accepting  the  unsolved 
as  a  challenge.  Their  motivation  to  earn 
on  to  a  solution  is  high;  an  unresolved 
dilemma  keeps  coming  back  into  their  field 
of  attention,  compelling  them  to  work  at 
it.  Some  men  of  genius  fit  these  specifica- 
tions, but  not  all  who  are  proclaimed 
geniuses  by  the  world. 

Some  people  think  that  the  intelligence 
tests  could  be  used  to  measure  thinking 
ability,  but  it  is  doubtful  if  such  tests  are 
good  indicators  of  a  person's  insight. 

HOW    TO    THINK 

Thinking  is  not  easy,  and  there  is  no 
easy  substitute  for  thinking  other  than  ac- 
cepting your  solutions  and  beliefs  read\- 
made  from  others  without  troubling  to 
check  their  adequacy  for  \ourself.  You 
can,  however,  reduce  the  effort  of  thinking 
by  eliminating  false  starts,  by  avoiding  un- 
necessary errors  and  stumbling  blocks  or 
by  taking  pains  not  to  repeat  the  same 
error.  There  remains,  ho^vever,  a  process 
which  takes  time  and  ^vhich  those  persons 


212 


Recollecting,  Imagining  and  Thinking 


who  ha\e  not  learned  to  enjoy  it  regard  as 
'work.' 

The  fundamental  problem  of  the  applied 
psychology  of  thinking  is  the  improvement 
of  the  adequacy  of  thinking.  For  the  in- 
dividual thinker  this  means  improving  his 
'batting  average'  in  the  solution  of  the 
problems  which  he  meets  from  day  to  day. 
For  society  at  large  it  means  reducing  the 
gullibility  of  the  voter,  the  radio  listener 
and  the  reader.  Thought  in  oiu"  cidture 
will  be  improved  if  we  better  the  quality  of 
thinking  which  is  broadcast,  printed  and 
spoken  by  writers,  editors,  speakers,  com- 
mentators and  men  of  public  affairs. 

The  partners  in  that  undertaking  are 
logic,  education,  psychology  and  all  the 
sciences,  social  and  natural.  Logic  pro- 
vides tests  of  the  validity  of  thinking.  Psy- 
chology fin^nishes  knowledge  about  the 
actual  thinking  process  and  the  causes  of 
bad  thinking.  Education  and  the  sciences 
provide  the  factual  backgioimd  which  the 
individual  needs  in  his  thinking,  and  also 
training  and  practice  in  this  difficult  art. 

It  is  not  possible  to  print  a  dozen  or  a 
hundred  practical  rules  guaranteed  to  make 
anyone  an  effective  thinker.  Good  think- 
ing depends  upon  (1)  strong  motivation  for 
the  particular  problem  in  hand,  (2)  con- 
stant general  interest  in  problem  solving, 
(3)  the  alertness  and  flexibility  that  favor 
insight  over  the  continued  use  of  stereo- 
typed procedures  and  (4)  the  wide  range 
of  wisdom  that  gives  insight— the  percep- 
tion of  novel  relationships— something  to 
work  on. 

In  addition  to  these  general  dimensions 
of  good  thinking,  not  all  of  which  lie  under 
voluntary  control  and  many  of  which  it  is 
too  late  for  the  mature  adult  to  acquire,  this 
chapter  suggests  many  rides  that  can  be 
applied  in  favor  of  correctness  and  effi- 
ciency.   Here  are  a  few  of  them. 


(1)  Because  thinking  takes  time,  best 
results  cannot  be  obtained  with  rigid  time 
limits.  When  a  problem  is  intrinsically 
and  strongly  interesting  there  is  no  need  for 
a  time  pressure.  If  the  problem  is  less  in- 
teresting, a  time  limit  may  serve  as  a  con- 
venient device  for  maintaining  motivation. 
Too  short  and  too  rigid  a  time  limit  is 
likely  to  reduce  the  quality  of  thinking. 

(2)  Although  the  phenomenon  is  not 
well  imderstood,  incubation  can  be  put  to 
practical  use.  When  thinking  appears  to 
be  'getting  nowhere'  and  failure  after  fail- 
ure occurs,  put  the  problem  aside  for  a 
time.  When  you  return  to  it  fresh,  it  will 
often  progress  well.  You  may  even  experi- 
ence the  sudden  insight  which  comes  im- 
expectedly  'out  of  the  blue.' 

Incubation  is  not  effective  if  you  have 
not  really  tried  to  solve  the  problem  be- 
fore resting.  The  success  of  incubation 
depends  upon  the  previous  labor  you  have 
devoted  to  the  problem  and  the  level  of 
your  motivation.  Incubation  cannot  be 
used  to  avoid  work  upon  the  problem,  and 
it  is  not  a  substitute  for  factual  informa- 
tion. You  will  hatch  nothing  if  there  is  not 
something  already  there  to  incubate. 

(3)  Tacit  assumptions  and  unrecognized 
sets  are  such  frequent  causes  of  failure  that 
we  must  continually  watch  for  them.  Per- 
haps one  reason  for  the  incubation  effect 
is  that  the  intei-val  permits  us  to  lose  some 
of  these  wrong  sets.  At  any  rate,  when  you 
are  'stuck,'  start  looking  over  your  assump- 
tions and  the  conditions  of  the  problem. 
It  may  be  helpful  to  write  down  all  the 
conditions  of  the  problem  and  those  as- 
sumptions which  are  necessary.  Then  ex- 
amine your  procedure  to  see  if  you  have 
missed  some  possibilities  which  are  not 
explicitly  forbidden  by  the  nature  of  the 
problem. 


How  fo  Think 


213 


(4)  Check  the  logical  pattern  of  your  rea- 
soning. U  you  have  had  no  training  in 
logic,  try  to  obtain  it.  In  any  case,  make 
sure  all  the  steps  of  your  reasoning  are  ex- 
plicitly stated.  Frequently  you  will  have 
taken  for  granted  one  or  more  important 
steps.  If  all  the  steps  were  explicitly 
stated,  you  might  not  accept  them  as  readily 
as  you  do  in  their  vague  unformulated 
state. 

As  a  check  upon  the  validity  of  reason- 
ing it  is  frequently  useful  to  follow  through 
a  parallel  argument  in  another  field  where 
the  correct  solution  is  known.  For  ex- 
ample, in  discussing  the  syllogism  (p.  210), 
we  used  first  an  example  of  a  formal  argu- 
ment with  X's  and  Y's,  and  then  we  took 
a  look  at  the  same  form  of  argument  with 
animals  instead  of  the  letters.  In  the  sec- 
ond case  we  found  that  the  conclusion  was 
contrary  to  known  facts.  This  kind  of 
parallel  check  with  familiar  materials  does 
not  prove  that  the  original  logic  was  sound. 
The  parallel  might  be  right  by  accident. 
But  when  the  parallel  is  patently  wrong, 
the  original  logic  does,  indeed,  need  care- 
fid  scrutiny. 

Always  suspect  yourself  when  you  are 
inclined  to  accept  a  conclusion  while  the 
details  of  the  argument  remain  unclear. 
Let  your  knowledge  of  atmosphere  effect 
warn  you  that  conviction  of  correctness  is 
not  necessarily  valid.  Intuition  and  hunch 
are  extremely  valuable  in  thinking,  but 
they  are  means  for  getting  to  a  sound  con- 
clusion and  they  are  not  necessarily  self- 
validating.  Sometimes  an  insight  is  as 
self-validating  as  a  geometrical  axiom,  but 
there  is  still  the  danger  that  habit  or  at- 
mosphere or  wishful  thinking  may  have 
deceived  you. 

(5)  A  final  word  has  to  do  with  motiva- 
tion in  thinking.  Thinking  itself,  regard- 
less of  its  practical  outcome,  does  not  have 


to  be  'work';  it  can  be  intrinsically  inter- 
esting. The  modern  occidental  culture  is 
an  aggressive  culture.  We  like  competi- 
tion. A  fight  is  alway.s  news.  In  America 
competitive  sports  interest  almost  everyone, 
at  least  as  onlookers,  most  of  whom  like  the 
indoor  contests  that  are  waged  with  cards 
or  comparable  weapons.  Thinking  is  just 
such  a  game.  Mostly  it  is  solitaire,  but  in 
it  you  compete,  not  against  chance,  but 
against  nature  which  yields  up  its  truth 
only  to  those  who  are  deft,  wise,  alert  and 
eager  to  be  right. 

REFERENCES 

1.  Allport,  G.  ^V.,  and  Postman,  L.  J.  The  psy- 
chology of  rumor.     New  York:  Holt,  1947. 

The  how  and  why  of  the  spread  of  rumor  in 
relation  to  the  psychology'  of  perceiving,  re- 
membering and  reporting  with  the  results  of 
experiments. 

2.  Bartlett,  F.  C.  Remembering.  Cambridge, 
England:  University  Press,  1932. 

Descriptions  of  the  author's  own  researches 
upon  recollection  of  form,  using  both  pictures 
and  stories  as  materials. 

3.  Bentley,  M.  The  new  field  of  psxchologw  New 
York:  D.  Appleton-Century,  193-t.  Chaps.  14 
and  15. 

A  careful  survey  of  all  the  psychological 
processes.  The  chapters  on  recollecting,  com- 
prehending and  thinking  stress  primarilv  the 
descripti\e   approach. 

4.  Duncker.  K.  On  problem-solving.  Psxchol. 
Monogr.,   No.   270,    1945. 

Descriptive  experiments  upon  problem  solv- 
ing, interpreted  from  the  point  of  view  of  Ge- 
stalt  psychology. 

5.  Hayakawa,  S.  I.  Laytguage  in  action.  New 
York:   Harcomt.  Brace.  1946. 

As  the  subtitle  states,  the  book  is  "a  guide 
to  accmate  thinking,  reading  and  writing.'" 

6.  Kasner.  E..  and  Newman.  J.  Malhemalics  and 
the  imagination.  New  York:  Simon  and  Schus- 
ter, 1940. 


214 


Recollecting,  Imagining  and  Thinking 


An  entertaining  account  ol  some  ol'  the  im- 
portant concepts  used  in  mathematical  think- 
ing: mathematical  ratlier  than  psychological  in 
its  orientation,  hut  holding  many  implications 
for   the   psychologist. 

7.  Kohler,  W.  The  mentalily  of  afjes.  New 
York:    Harcourt,  Brace,   1925. 

.'Vn  interesting  and  detailed  report  of  Kohler's 
experiments  upon  insightful  hehavior  in  chim- 
panzees, and  their  use  of  sim|jle  tools  and  con- 
structions  in   solving  problems. 

S.  Stern,  W.  General  psychology.  New  York: 
Macmillan.  trans.  1938.  Part  4.  Chaps.  In  to 
19. 

Good  chapters  on  recollecting,  imagining  and 
thinking,  in  a  descriptive  survey  of  psychology 
from  the  pcrsonalistic  point  of  view. 


9.  Thouless.  R..H.     How  lo  think  siraighl.     New 
York:  Simon  and  Schuster,  1939. 

The  technique  of  using  logic  instead  of  emo- 
tion in  thinking. 

10.  Wertheimer,    M.      Pioduclive    Ihinking.      New 
York:  Harper,  1945. 

The  approach  of  Gestalt  psychology  to 
thinking  is  simimarized  and  illustrated  by  the 
author's  own  experiments  with  children  and 
adults,  as  well  as  by  certain  instances  of 
.scientific  thinking    (for  example,  Einstein's). 

11.  Woodworth,    R.    S.      Experimental    psychology. 
New  York:  Holt.  1938.    Chaps.  25,  29  and  30. 

Excellent  chapters  on  memory  for  form, 
problem  solving  and  thinking  in  an  advanced 
but  clearly  written  survey  of  experimental  psy- 
chology. 


CHAPTER 


10 


Perception 


IN  the  first  chapters  of  this  book  we  have 
studied  men  doing,  acting  and  learning; 
but  before  men  act  they  usually  perceive, 
they  sense,  they  note  what  things  and  events 
are  about  them.  Perception  is  the  first 
event  in  the  chain  which  leads  from  the 
stimulus  to  action.  To  understand  per- 
ception we  must  find  out  just  what  it  is 
in  the  world  that  we  respond  to.  What 
things  are  important  for  us,  and  why? 

In  the  simplest  sense,  a  stimulus  is  any 
sort  of  energy  change,  that  is  to  say  event, 
which  can  set  ofT  a  response.  Heat  or  pres- 
sure on  the  skin,  light  falling  into  the  eye, 
chemical  particles  carried  into  the  nose, 
these  are  all  stimuli  in  this  simple  sense. 
For  many  of  the  simplest  organisms  they 
are  all  that  matter.  The  immediate  physi- 
cal agent  is  all  important.  It  is  the  water, 
as  hot  or  cold,  acid  or  neutral,  which  makes 
the  amoeba  swim  forward  or  back.  In  the 
same  way,  the  initial  response  of  our  sense 
organs  depends  upon  these  proximal 
stimuli. 

As  organisms  become  more  complex,  they 
no  longer  react  just  to  the  stimulus  which 
touches  the  skin.  They  acquire  also  an 
ability  to  know  something  about  what  lies 
at  a  distance.  The  'eyes'  of  starfish  and 
the    octopus    can    tell    the    direction    from 


which  light  conies.  The  'ears'  of  insects 
permit  them  to  hear  sounds  made  by  their 
distant  mates. 

The  receiving  equipment  of  mammals 
and  of  men  is  made  far  more  complex  by 
the  addition  of  a  nervous  system.  The 
physical  and  chemical  stimuli,  of  course, 
still  pass  through  the  skin,  but  man's  reac- 
tions are  gauged  to  objects  and  events 
often  quite  far  away.  It  is  the  steak  si//ling 
in  the  pan,  the  friend  walking  by  his  side, 
the  ball  flying  through  the  air  which  directs 
what  he  does.  For  the  simple  animal  it  is 
only  the  proximal  events  in  his  physical 
environment,  the  events  that  come  into 
actual  contact  with  him,  which  set  the  pat- 
tern of  his  action;  for  higher  animals  the 
more  distant  occurrences  are  of  great  im- 
portance. To  describe  these  remote  stimuli 
a  more  complete  inventory  of  the  human 
environment  is  necessary.  We  have  to  go 
farther  afield  to  find  just  what  it  is  that, 
corresponding  with  our  experience,  is  rep- 
resented by  that  experience.  Just  what  are. 
we  ask,  the  more  distant  things  in  the  workl 
around  man  to  which  he  responds. 

It  is  not  easy  to  understand  fully  the 
problem  of  perception.  Reality,  tlie  ob- 
jects and  events  around  us.  seems  so  tan- 
gible, so  concrete  that  we  believe  the  world 
exists  just  as  we  perceive  it.     Our  experi- 


This  chapter  was  prepared  by  Edwin  B.  Newman  of  Harvard  University. 

215 


216 


Perception 


ence  mirrors  what  is  out  there.  Or,  at  its 
worst,  experience  is  but  a  slightly  tarnished 
copy  of  the  world.  More  thoughtful  peo- 
j)le  realize  that  this  view  is  too  simple. 
The  physicist  tells  us,  for  instance,  that  this 
hard,  smooth,  solid  object  which  I  hold  in 
my  hand  is  actually  not  solid  at  all.  In 
his  view  it  is  many  tiny  bits  of  matter 
spinning  in  orbits  like  the  moon's  about 
the  earth  with  relatively  large  spaces  be- 
tween the  particles.  He  may  call  attention 
to  other  'errors'  in  our  perceptions.  White 
to  the  eye  is  a  simple  color;  to  the  physicist 
it  is  a  most  complicated  mixture  of  many 
kinds  of  light.  Consider  musical  tones. 
In  our  experience  they  are  smooth  and  con- 
tinuous. Physically  they  consist  of  a  rap- 
idly alternating  series  of  sound  waves  strik- 
ing our  ears.  Clearly  then,  the  object  out 
there,  as  a  physical  object,  and  our  experi- 
ence of  it  are  two  quite  different  things. 

There  are  philosophers  who  are  so  im- 
pressed by  the  difficulty  of  relating  our 
experience  on  the  one  hand  to  the  physical 
world  on  the  other,  that  they  give  up  the 
problem  altogether.  Experience,  they  say, 
is  the  only  thing  which  we  can  know  with 
assurance.  There  is  no  proof  of  the  exist- 
ence of  the  physical  world;  hence  it  is  only 
an  illusion.  These  philosophers  are  the 
idealists. 

Today  most  people  reject  philosophical 
idealism.  We  believe  there  is  a  real  world 
apart  from  our  experience  of  it.  We  ac- 
cejjt  both  the  fact  that  there  is  a  world  out 
there  and  that  we  as  organisms  respond 
to  it.  The  way  in  which  an  organism  re- 
sponds to  the  world  is  a  problem  which 
is  on  a  par  with  any  other  scientific  prob- 
lem. What  happens  when  we  perceive,  and 
what  is  it  that  makes  it  happen?  That  is 
the  problem  of  perception. 


THE    DEFINITION    OF 
PERCEPTION 

It  will  perhaps  be  well  to  set  out  clearly 
the  meaning  of  a  few  of  the  words  which 
we  are  going  to  use.  Perception  is  the 
experience  of  objects  and  events  which  are 
here  now.  It  excludes  those  things  which 
are  somewhere  else,  things  about  which  we 
may  think  clearly  but  do  not  sense  di- 
rectly. Furthermore,  it  is  convenient  to  use 
the  term  perception  for  the  more  general 
aspects  of  this  activity,  reserving  the  term 
sensation  for  those  facts  in  our  experience 
which  depend  upon  how  the  sense  organ 
acts. 

Some  perceptions  seem  to  us  to  be  in 
error.  If  one  perception  does  not  agree 
with  another,  we  call  the  unusual  one  an 
illusion.  Everyone  knows,  for  instance, 
that  the  movement  seen  in  the  movies  is  an 
illusion.  A  series  of  still  pictures  is  shown 
in  rapid  succession.  Each  picture,  pro- 
jected alone,  is  quite  stationary,  but  when 
the  series  is  shown  at  a  proper  rate  we  see 
movement.  It  is  not  true  in  an  illusion 
that  one  perception  is  'wrong'  while  the 
other  is  'right.'  Actually  each  is  just  as 
normal  as  the  other.  It  is  no  easier  to  ex- 
plain why  slow  projection  is  seen  as  a  series 
of  objects  displaced  discontinuously  than 
it  is  to  explain  why  faster  projection  shows 
the  same  objects  moving  continuously. 
Both  kinds  of  seeing  are  complicated  and 
need  a  great  deal  of  explaining.  The  word 
illusion  is  a  convenient  handle  for  desig- 
nating these  luiusual  perceptions,  but  we 
must  remember  that  naming  a  phenome- 
non does  not  explain  it. 

Hallucinations  are  clearly  abnormal. 
They  are  perceptions  which  are  unique  for 
one  person  alone.  If  nine  people  in  a  room 
see  nothing  while   the  tenth  sees  a  black 


change  is  the  Basis  of  Perception 


217 


cit,  the  tcnlh  is  jjiob.ihly  li;illiic:inatcd. 
Hallircinations  occur  occasionally  tor  every- 
one. When  frequent  and  persistent,  they 
are  almost  always  in  our  society  regarded 
as  a  symptom  of  mental  disorder.  We 
send  the  person  who  has  them  to  an  insti- 
tution for  special  care. 

CHANGE    IS    THE    BASIS    OF 
PERCEPTION 

Many  of  the  facts  about  perception  are 
so  simple  that  they  almost  escape  notice. 
Let  us  start  out,  however,  with  some  of 
these  simple  facts  because  they  are  very 
general  and  apply  to  almost  all  cases  of 
perception.  One  such  fact  is  that  percep- 
tion is  always  a  response  to  some  change  or 
difference  in  the  environtnent.  If  the  world 
were  perfectly  homogeneous  and  we  were 
in  equilibrium  with  it,  we  should  experi- 
ence nothing.  Let  some  condition  change 
suddenly,  or  one  receptor  be  stimulated 
and  another  not,  and  we  sense  the  fact 
at  once. 

Take  as  an  example  our  experience  of 
pressure.  At  the  surface  of  the  earth  there 
is  a  presisure  of  15  pounds  on  each  square 
inch  of  the  surface  of  our  bodies.  Yet  we 
feel  nothing.  Let  15  pounds  more  press  on 
a  single  square  inch,  and  we  feel  it  very 
clearly.  Proof  that  we  do  not  feel  a  uni- 
form pressure  comes  from  aviators  who  go 
up  to  an  altitude  of  35,000  or  40,000  feet 
in  the  air.  At  this  altitude  the  pressure 
on  the  surface  of  the  body  is  but  3  pounds 
per  square  inch.  Still  they  do  not  feel  any 
pressure.  The  same  is  true  of  the  diver 
or  the  sand  hog  who  works  in  a  caisson 
under  the  river.  These  men  may  be  sub- 
jected to  pressures  as  great  as  50  or  60 
pounds  per  square  inch.  Of  the  pressure 
itself,  they  feel  nothing. 


Rapid  change  of  pressure  is  a  different 
story.  Sound  which  stimulates  our  ears  is 
just  sucli  a  rapid  change.  Tactual  stimu- 
lation is  a  difference  in  pressure  between 
one  part  of  the  fiody  and  another.  A  nice 
demonstration  of  these  facts  may  be  made 
by  a  very  simple  experiment.     Plare  your 


FIGURE  77.      CHANGE  IN   PRESSURE  DETERMINES 
PERCEPTION 

When  the  hand  is  held  under  water,  only  the 
ring  around  the  wrist  is  felt.  Neither  the  uniform 
pressure  of  the  air  nor  of  the  water  is  sensed  bv 
the  subject. 

hand  in  a  deep  basin  of  lukewarm  water. 
So  long  as  you  hold  your  hand  still,  you 
feel  pressure  neither  from  the  "water  nor 
from  the  air.  All  that  you  feel  is  the  ring 
wliere  the  water  joins  tfie  air,  wliere  there 
is  a  sharp  change  of  pressure  due  to  the 
surface  tension.    (See  Fig.  77.) 

Temperature  is  another  familiar  illus- 
tration of  this  same  fact.  "What  we  per- 
ceive as  hot  or  cold  depends  largelv  upon 
what  has  just  gone  before.  If  tlie  tempera- 
ture is  lowered  w-e  perceive  cold;  if  it  is 
raised  we   perceive   warm.     This   is   prob- 


218 


Perception 


ably  all  that  counts.  It  has  been  said 
that  a  frog,  a  cold-blooded  animal,  may  be 
heated  up  gradually  while  sitting  in  a  pan 
of  water  until  killed  by  the  heat  without 
feeling  anything,  at  least  without  jumping 
out.  The  problem  is  somewhat  more  com- 
plex in  man  who  possesses  a  special  tem- 
perature-regulating mechanism  and  the 
means  for  getting  ill  with  fever  when  the 
blood  gets  too  warm. 

The  visual  perceptions,  white  and  black, 
are  notoriously  dependent  upon  differences. 
The  intensity  of  light  given  off  by  the 
darkest  black  object  in  sunlight  may  be 
greater  than  the  intensity  of  the  brightest 
white  object  in  a  dim  light.  And  yet  the 
white  object  looks  white  and  the  black 
object  black,  even  though  the  white  object 
reflects  less  light  than  the  black.  What  is 
most  important  is  the  relative  amount  of 
light  from  each  part  of  the  visual  field, 
from  the  object  and  from  its  surroundings. 
Black  is  not  just  the  absence  of  any  visual 
experience.  It  is  a  definite  something 
which  is  not-white.  The  person  born 
blind,  whose  optic  nerve  is  destroyed,  sees 
neither  white  nor  black;  he  sees  nothing. 

PERCEPTION    IS    SELECTIVE 

A  second  general  characteristic  of  per- 
ceiving is  that  it  is  selective.  At  any  given 
moment  himdreds  of  stimuli  are  reaching 
our  sense  organs.  Out  of  this  welter  of 
forces  acting  from  outside,  the  organism 
has  to  select  the  particular  one  to  which 
it  will  attend,  the  one  to  which  it  will  re- 
spond in  some  unified,  coherent  way. 
Simplicity,  or  singleness  of  response,  is  part 
of  the  basic  biological  nature  of  living  mat- 
ter. 

This  selectivity  of  perception  amounts 
to  giving  one  sense  impression  a  clear  track. 
The  one  impression  captures  or  preempts 


the  reacting  machine,  momentarily  shut- 
ting out  all  other  sense  impressions.  For 
the  moment  the  favored  sense  impression 
holds  sway.  Later,  of  course,  some  other 
sense  impression  will  take  over. 

In  our  experience  we  speak  of  these  facts 
by  saying  that  we  attend  to  something. 
Only  a  small  number  of  items  can  fall 
within  the  span  of  attention.  Our  experi- 
ence is  said  to  have  a  focus  and  a  margin. 
Those  items  which  are  clearest  in  experi- 
ence lie  within  the  focus  of  attention. 
Mixed  in  with  them  or  off  to  one  side  arc 
many  less  clear  items  which  make  up  the 
margin.  Still  other  things,  which  we 
might  be  experiencing  and  are  not,  lie  en- 
tirely outside  the  field  of  attention. 

Yotir  experience  at  this  moment  will  make 
this  matter  quite  clear.  The  focus  of  your 
attention  is  occupied  by  the  words  you  are 
reading  on  this  page.  The  margin  of  your 
experience  is  filled  with  such  things  as  the 
table  on  which  this  book  is  lying,  the  sound 
of  people  moving  near  by,  perhaps  a  pres- 
sure from  your  stomach  which  reminds  you 
of  lunch  or  a  slight  pain  in  your  foot  from 
an  ill-fitting  shoe.  You  have  been  quite 
unaware  as  you  read  this  of  the, touch  of 
your  clothes,  of  slight  strains  in  your  eyes 
as  they  move  back  and  forth  over  the  lines 
of  print,  of  the  soimds  of  your  own  breath- 
ing, of  the  color  of  the  paper  on  which  this 
is  printed.  You  luere  unaware  of  them, 
that  is,  until  reading  the  preceding  sen- 
tence made  you  attend  to  them! 

Attention  may  indeed  be  selective,  but  it 
seems  to  be  fickle  in  its  choices.  The  stream 
of  consciousness  is  rarely  smooth  and  placid. 
It  seems  rather  to  dart  here  and  there, 
never  continuing  for  long  in  a  single  direc- 
tion. Some  modern  writers,  such  as  James 
Joyce  and  Eugene  O'Neill,  have  made  much 
of  this  jumpiness  of  experience.  They  try 
to   portray   the   kaleidoscopic   character   of 


Perception  Is  Selecfive 


219 


experience  in  actual  words  and  thoughts. 
Carefully  studied,  however,  the  kaleido- 
scope turns  out  to  be  an  orderly  machine. 
Our  attention  may  fluctuate  from  one  thing 
to  another  but  it  is  not  really  capricious. 
There  arc  rules  which  help  to  predict  what 
will  gain  attention  and  what  will  hold  it. 
Here  are  six  of  the  rules. 

(1)  The  intensity  of  the  stimulus  is  obvi- 
ously the  most  important  single  factor  in 
determining  response.  A  loud  sound,  a 
bright  light,  a  hard  slap,  an  intense  pain, 
each  of  these  demand  action,  and  they 
usually  get  it.  Of  course  the  basic  rule 
that  change  is  the  stimulus  for  perception 
still  holds.  It  is  the  sudden  loud  sound, 
the  flash  of  bright  light  that  gets  attention 
and  action.  When  it  persists  an  intense 
stimulus  can  usually  be  neglected.  We 
work  under  bright  lights,  or  ride  on  the 
subway  train  without  serious  results.  Se- 
vere pain  may  even  go  unnoticed.  On  the 
other  hand,  a  sudden  decrease  in  intensity 
may  also  get  attention.  When  suddenly  the 
din  of  a  steel  mill  stops,  the  silence 
seems  almost  to  shout  at  you.  Alone  in  a 
quiet  room  with  a  ticking  clock,  you  do  not 
hear  the  clock  vmtil  it  stops.  Then  again 
the  silence  is  noticeable.  Nevertheless  a 
racket  is  more  compelling  than  a  silence. 
If  a  whisper  does  not  get  a  reply,  a  shout 
nearly  always  will. 

(2)  Novelty  is  a  factor  scarcely  less  im- 
portant than  intensity.  Any  mode  of  per- 
ception loses  its  effectiveness  as  it  grows 
older.  The  new  sight,  the  new  sound  gains 
relatively  in  strength  because  it  is  differ- 
ent from  the  old  ones,  contrasts  with  them. 
When  we  want  something  to  be  noticed, 
we  give  it  a  new  color,  a  new  shape,  per- 
haps a  new  odor  or  taste,  and  see  to  it  that 
it  contrasts  with  what  precedes  it  and  ac- 
companies it.  Just  as  perceiving  cannot 
take  place  at  all  without  there  being  dif- 


ference or  change,  so  there  must  be  differ- 
ence or  change  in  the  factor  novelty.  A 
strange  object  grouped  with  ninety-nine 
other  strange  objects  does  not  get  attention, 
because  there  is  no  reason  for  the  choice  of 
one  object  more  than  another.  On  the 
other  hand,  one  familiar  object  placed 
among  ninety-nine  novel  objects  does  stand 
out  and  catch  the  eye.  Paradoxical  as  the 
statement  is,  here  familiarity  is  novel,  or  at 
least  rare,  and  strange  objects  are  too  com- 
mon to  seem  novel. 

(3)  The  repetition  of  a  stimulus  helps  in 
several  ways  to  evoke  action.  First  of  all, 
a  repeated  stimulus  is  in  some  senses  a  more 
intense  stimulus.  Two  shots  in  succession 
are  more  likely  to  attract  our  attention 
than  one;  three  are  perhaps  more  effective 
than  two.  Sometimes  regular  repetition 
helps  attract  attention  because  the  first  few 
instances  sensitize  us  to  the  later  ones. 
How  often  do  we  start  to  count  the  strokes 
of  a  clock  after  two  or  three  have  gone  by. 
We  hear  a  new  song  tw^o  or  three  times 
over  before  we  really  seem  to  hear  it. 
Finally,  the  regular  repetition  of  a  stimulus 
often  produces  a  set  or  expectation  so  strong 
that  later  members  of  the  series  are  per- 
ceived the  same  way  even  when  they  have 
in  fact  been  changed.  An  example  is  the 
'proofreader's  illusion,'  the  failure  to  see  a 
misspelled  word  because  of  expectation  of 
the  correct  form  (see  p.  202).  The  movies 
trade  on  this  factor  when  they  use  'doubles' 
and  'stand-ins'  which  the  uncritical  person 
readily  accepts  as  if  the  principal  actor  were 
continuously  present.  Repetition  also  mul- 
tiplies the  chances  of  a  stimulus'  getting 
attention:  if  it  misses  on  the  first  two  tries, 
it  may  succeed  on  the  third.  Nevertheless, 
the  effect  of  repetition  is  not  primaiilv 
due  to  the  operation  of  chance.  Thert 
can  be  no  doubt  that  the  marginal  occur- 


220 


Percept/on 


rence   of   stimulation   helps   eventually    to 
bring  it  into  the  focus  of  attention. 

(4)  hitention— the  effect  of  set  or  atti- 
tude—is a  very  important  factor  in  deter- 
mining what  experience  is  selected  for  at- 
tention. When  we  intend  to  speak  to  a 
particular    person,    he    stands    out    quite 


FIGURE   78.      THE    WIFE— AND    THE    MOTHER-IN-LAW 

There  are  two  equally  'good'  faces  shown  in  this 
picture.  You  can  see  one.  Can  you  see  the  other? 
[.Adapted  from  W.  E.  Hill.] 

clearly  as  we  meet  him  in  a  crowd.  When 
we  decide  to  get  the  hammer  from  the 
shop,  we  see  it  at  once  even  though  it  is 
out  of  place  on  the  bench.  The  bird  lover 
at  once  hears  the  thrush's  song,  while  the 
business  inan  remains  unperturbed,  exain- 
ining  the  woods  as  possible  pulp  for  mak- 
ing paper.  Intention  is  in  a  way  a  rehearsal 
of  an  expected  experience.  'When  the  ex- 
perience comes,  it  is  like  meeting  an  old 
friend. 

(5)  All  those  forces  within  the  individual 
which  are  lumped  together  as  motivation 
act   as   a   powerful   selective   agent   in   per- 


ception. The  familiar  example  is  the 
pretty  girl  of  any  advertisement.  Sense- 
less though  it  seems,  'leg  art'  and  'cheese 
cake'  are  basic  principles  of  advertising. 
Sex  appeal  gets  attention  more  quickly 
than  any  other  factor.  For  a  half-starved 
man  the  values  are  quite  different.  The 
odor  of  food  is  far  sweeter  to  his  nostrils 
than  the  finest  perfume.  Sex,  food,  water, 
need  for  shelter,  parental  love,  operate  both 
in  animals  and  men  to  determine  jjercep- 
tion.  Other  needs,  for  social  approval  and 
security,  for  play  and  activity  and  order, 
may  have  less  evident  although  perhaps 
no  less  real  effects. 

(6)  Finally,  selection  is  determined  by 
the  part  luhich  the  particular  stimulus 
plays  in  the  luhole  pattern  of  perception. 
Each  part  by  itself,  in  a  figure  such  as  Fig. 
78,  stands  little  chance  of  being  selected. 
But  when  it  is  given  an  important  role  in 
the  scheme  of  things,  it  suddenly  stands  out. 
Note  how  this  happens  as  you  discover  the 
mother-in-law.  An  unimportant  shadow 
becomes  her  eye,  and  an  inconspicuous 
band  her  mouth.  At  the  same  time  the 
pert  nose  of  the  wife  becomes  only  a  slip 
of  the  artist's  pen. 

The  parts  of  the  hidden  figure  were  there 
all  the  time  waiting  for  you  to  discover  the 
object  or  to  have  it  pointed  out  to  you. 
Once  the  object  is  seen  it  directs  atten- 
tion to  its  own  parts,  makes  them  signifi- 
cant and  important.  At  the  same  time,  of 
course,  it  makes  other  details  unimportant, 
makes  them  just  members  of  the  crowd  as 
background  for  the  star  actor. 

PERCEIVING    IS    ORGANIZED 

The  task  of  selecting  among  the  many 
stimuli  presented  to  our  senses  would  be 
almost  impossible  were  it  not  for  teamwork 
among  the  individual  sense  organs.     Each 


Perceiving  Is  Organized 


221 


element  of  the  eye  docs  not  report  to  the 
brain  upon  what  happens  to  it  alone; 
rather,  a  group  of  receptors  sees  a  square 
or  circle,  a  moving  figure  or  patterns  with 
more  complex  structure.  The  eyes  and  the 
brain  are  able  to  group  or  to  organize  a 
number  of  stimuli  into  a  larger  unit  to 
^vhich  the  organism  now  may  respond  in  a 
simple  fashion.  This  unifying  activity  of 
perception  makes  it  possible  for  a  person 
to  respond  to  a  far  more  complicated  en- 
vironment than  he  could  without  it. 

The  way  grouping  works  can  best  be 
illustrated  by  a  number  of  simple  examples 
chosen  to  illustrate  the  more  important 
principles. 

(1)  If  there  are  various  objects  in  a  field, 
those  things  will  be  grouped  which  are 
similar.  Look,  for  instance,  at  Fig.  79. 
In  the  left-hand  part  of  this  figure,  which 
are  the  obvious  series  of  objects?  In  what 
direction  do  the  sets  run?  Up  and  down? 
right  and  left?  diagonally?  What  do  you 
see  in  the  right-hand  part  of  the  figure? 

In  both  parts  it  is  the  similar  figures 
which  appear  linked  together.  In  the  left 
part  of  the  figure  they  mark  out  five  hori- 
zontal lines,  three  longer  and  two  shorter. 
In  the  right-hand  part  the  three  cubes 
stand  out  while  the  small  figures  form  a 
closely  knit  background  for  the  cubes.  It 
would  indeed  be  unusual  if  you  saw  one 
of  the  tiny  figures,  such  as  the  A^  forming 
a  pair  with  one  of  the  cubes,  while  the 
other  cubes  formed  some  other  figure  with 
other  parts  of  the  background.  (Can  you 
find  the  A  among  the  other  small  figures?) 
Similarity  may  be  similarity  of  shape,  simi- 
larity of  size,  similarity  of  color  or,  for  that 
matter,  similarity  in  any  property  of  an  ob- 
ject which  can  readily  be  distinguished. 

(2)  The  second  principle  of  grouping  is 
nearness   or  proximity.      How   would   you 


describe  the  lines  at  tlic  left  in  Mg.  80? 
Everyone  would  say  of  the  figures  at  the 
right  that  there  were  two  people  followed 
l^y  a  single  person.  The  relative  nearness 
of  the  two  lines  or  of  the  two  people  makes 
them  seem  obviously  a  pair.  Proximity  is  a 
relative  matter,  to  be  sure.  Two  objects 
might  be  separated  by  quite  a  distance  and 
still  form  a  pair  if  no  other  object  of  the 
same  kind  were  in  the  vicinity. 


FIGURE    79.       SINULARITY    FAVORS    GROUPING 

In  the  left-hand  figure  one  sees  five  horizontal 
lines.  The  circles,  or  the  crosses,  are  grouped  to- 
gether. Three  figures  stand  out  easily  on  the 
right.  The  small  similar  figures  of  the  background 
form  such  a  firm  pattern  that  the  letter  ,\  among 
them  can  be  found  only  with  difficulty. 

(3)  The  factor  of  proximity  may  be  modi- 
fied to  some  extent  by  the  symmetry  of  the 
entire  figure.  Compare  the  two  sets  of 
lines  in  Fig.  81.  In  the  upper  set.  A,  prox- 
imity operates  so  that  you  see  three  pairs  of 
parallel  lines.  In  the  lower  set,  B,  a  per- 
son usually  sees  two  sets  of  parallel  lines 
with  a  single  line  on  each  end  which  forms 
a  disturbing  remainder.  Set  B  mav,  how- 
ever, be  seen  almost  as  well  as  three  sets  of 
broadly  spaced  parallel  lines.  Thus  the 
pairing  favored  by  proximity  may  be  broken 
down  in  favor  of  a  pairing  which  uses  up 
the  entire  set  of  six  lines.  It  is  much  more 
difficult  to  see  this  pairing  across  the  broad 
space  in  the  set  A  because  this  would  in 
turn  leave  a  remainder  on  either  end.  It 
is  as  if  the  organism  abhorred  something 
left  over. 


222 


Percepfion 


FIGURE  80.      NEARER  OBJECTS  FORM  A   PAIR 

To  the  left,  one  sees  two  lines,  plus  one.     How  would  you  describe  the  gioiiping  of  the  three  men   to 
the  right? 


(4)  The  principles  of  grouping  deter- 
mine not  only  the  way  separate  items  are 
linked  together  but  also  how  a  number  of 
parts  fit  together  to  form  a  figure.  The 
choice  of  parts  to  be  grouped  would  seem 
to   be   especially   difficult   if   one    figure   is 


FIGURE    81.        PAIRS     LEAVE     NO     REMAINDER     WHEN 
POSSIBLE 

In  A,  the  pairs  favored  by  proximity  take  in  all 
the  lines.  In  B,  the  end  lines  work  to  favor  a  pair- 
ing across  the  longer  distance. 

drawn  over  the  other  one  as,  for  instance, 
in  Fig.  82.  Here  there  appear  to  be  two 
lines.  One  is  a  wavy  line,  the  other  is  like 
the  edge  of  a  wall  with  its  square  corners. 
In  terms  of  the  detail,  a  belongs  with  c  and 
b  with  d.  But  proximity  would  favor  the 
linking  of  a  and  d  or  c  and  d.  In  this  fig- 
ure, however,  the  good  continuation  is  the 
straight  or  continuous  line,  and  such  a 
grouping  is  favored  over  other  possible 
groupings. 

(5)  The  forces  which  gioup  visual  ele- 
ments into   a  stationary   figure   are   multi- 


plied in  a  sense  many  times  over  when 
that  figure  moves.  The  significant  links 
among  the  parts  of  the  figure  itself  remain 
constant  while  the  relations  between  parts 
of  the  figure  and  parts  of  the  background 
are  constantly  changing,  and  getting  lost 
in  the  process.  A  familiar  example  is 
looking  through  a  dirty  or  spotted  win- 
dow. If  the  person  looking  holds  his  head 
quite  still,  it  is  not  easy  for  him  to  know 
whether  the  spots  are  on  the  window  or  on 
the  object  seen  through  the  window.  If, 
now,  he  moves  his  head  ever  so  slightly, 
all  the  spots  on  the  window  move  in  one 
direction  while  the  object  seen  through  the 
window  moves  in  the  other.  What  was  un- 
clear a  moment  before  is  now  neatly  divided 
between  window  and  object.  Elements  are 
linked  which  have  a  common  movement. 
The  same  things  occurs  to  spoil  camou- 
flage. The  grouse  or  partridge  with  its 
protective  coloration  will  remain  invisible 
so  long  as  he  remains  still.  Just  as  soon 
as  all  the  spots  of  his  checkered  plumage 
move  together,  they  are  grouped  in  per- 
ception, and  the  bird  is  seen  to  be  a  single 
object. 

(6)  Moving  figures  illustrate  still  another 
principle  of  considerable  importance.  This 
principle  is  that  when  a  figure  moves,  the 
parts  of  the  figure  will  hold  constant  their 
relation  to  one  another.     The  parts  of  the 


Perceiving  Is  Organized 


223 


FIGURE  82.      LINES  ARE  GROUPED    INTO   CONTINUOUS   FIGURES 

A  wavy  line  is  drawn  over  the  square-coineicd,  straight  line.     In  terms  of  the  detail  to  the  right,  a  is 
paired  with  c  and  b  is  paired  with  d.     [After  Wertheimer  (1923).] 


(igtire  keep  in  formation  as  they  match 
along,  and  the  role  which  each  plays  will 
determine  what  points  are  linked  from  one 
moment  to  the  next.  A  single  example 
will  show  what  is  meant.  Imagine  that 
you  have  put  before  you  nine  white  spots 
arranged  in  a  diamond-shaped  pattern  as 
shown  by  the  circles  of  Fig.  83.  Let  these 
spots  disappear  and  a  moment  later  let 
nine  similar  spots  appear  in  the  places 
marked  by  the  crosses  in  this  figure.  No- 
tice that  four  of  the  spots  are  exactly  the 
same  when  they  are  shown  the  first  time 
and  the  second  time.  If  these  four  spots 
were  shown  alone  each  time,  they  would 
of  course  not  move  at  all.  We  might  sup- 
pose that  the  four  spots  would  do  the  same 
when  all  nine  were  present,  and  the  other 
five  would  have  to  move  around  them  from 
left  to  right.  What  happens  is  quite  dif- 
ferent. Everyone  sees  a  diamond-shaped 
pattern  which  moves  as  a  whole  over  to  the 
right.  The  spot  which  was  the  right-hand 
corner  in  the  first  presentation  is  linked 
or  grouped  with  the  spot  which  is  the  right- 
hand  corner  in  the  second  showing.  'Right- 
hand-corneredness'  has  more  to  do  with 
what  is  linked  together  than  the  actual 
stimulation  of  the  identical  spot  in  the  eye 
in  the  first  and  second  showing. 

All  the  examples  which  we  have  chosen 
have  been  visual  figures,  largely  because 
vision  is  our  most  complex  and  highly  de- 
veloped   sense.      Grouping   occurs    in    the 


other  sense  departments  as  well.  In  hear- 
ing, for  instance,  the  appreciation  of  a 
rhythm  depends  upon  the  linking  together 
of  the  proper  notes  or  beats  in  a  series. 
It  turns  out  in  this  case  that  the  principle 


o 


o 


o 


o 


0 


(8) 


0 


X 


® 


O  X  ' 

FIGURE    83.       PARTS     OF     A    FIGURE     RETAIN     THEIR 
RELATIVE  IDENTITY  WHEN   THE  FIGURE  MOVES 

The  circles  indicate  the  initial  position  of  nine 
points  of  light.  These  disappear  and  are  followed 
by  nine  lights  in  the  positions  marked  by  X's.  All 
nine  lights  move  equally  to  the  right,  even  though 
the  four  center  lights  are  identical  in  the  first  and 
second  exposures,     [.\fter  J.  Ternus  (1926).] 

of  proximity,  expressed  in  time,  is  very 
compulsory.  Pairs  of  beats,  dit-dit,  dit-dit, 
dit-dit,  are  invariably  grouped  into  pairs 
that  follow  closely  on  one  another.  Re- 
gi^ouping  across  a  longer  inter^•al,  such  as 
we  had  in  Fig.  81,  does  not  occur  in  hearing 
An  interesting  instance  of  giouping  oc- 
curs in  the  skin  in  what  has  been  called 
the  tau  effect.    Try  this  one  on  a  friend,  as 


224 


Perception 


it  is  very  easy  to  demonstrate.  Mark  out 
three  equidistant  points  on  his  forearm  or 
the  back  of  his  hand.  They  should  be  suffi- 
ciently separated  to  give  a  clear  impression 
of  distance.  When  his  eyes  are  closed, 
touch  the  three  points  in  succession  but 
with  your  timing  unequal.  For  instance, 
try  l-2-pause-3,  or  the  reverse,  l-pause-2-3. 
Ask  him  which  distance  is  the  longer.  It 
will  be  evident  at  once  that  the  distances 
which  are  felt  on  the  skin  depend  very 
much  upon  the  grouping  of  the  successive 
stimuli  in  time. 


WHAT    IS    IT    THAT 
PERCEIVE? 


WE 


At  the  beginning  of  this  chapter  we 
noted  that  to  understand  perception  we 
must  find  out  just  what  it  is  in  the  world 
around  us  to  which  we  respond.  Before 
trying  to  answer  that  question,  we  took 
time  to  describe  three  important  character- 
istics of  the  act  of  perceiving  itself.  It  was 
found  first  that,  in  perceiving,  the  organ- 
ism always  responds  to  some  change  or  dif- 
ference in  the  environment.  Second,  the 
organism  selects  the  particular  stimulus  or 
group  of  stimuli  to  which  it  will  respond. 
Third,  the  organism  links  together  a  num- 
ber of  stimuli  into  a  group  so  that  a  single 
simple  response  may  be  made  to  a  complex 
pattern. 

It  is  time  now  to  return  to  the  original 
question.  Let  us  examine  some  of  our  sim- 
ple perceptions  to  see  if  they  help  to  tell 
us  what  aspects  of  the  world  are  important 
as  the  stimuli  for  these  perceptions. 

THE    SIMPLEST    PERCEPTION: 
FIGURE    ON    A    GROUND 

The  simplest  perception  is  a  single  fig- 
ure which  appears  against  a  uniform  back- 


ground. Imagine,  for  instance,  that  the 
cross  of  Fig.  84  is  a  white  figure  on  a  per- 
fectly uniform  gray  backgi^ound  which  ex- 
tends out  beyond  the  limits  of  vision.  The 
experience  of  such  a  figure  represents  very 
nearly  the  absolute  minimum  of  complex- 
ity tliat  can  be  obtained.    Nevertheless,  sev- 


lU.l  HI.    f'].       s'Ml'l  I.    1  K.im      ON     LMIokM     1SA(.K- 
GROUND 

Imagine  that  the  cross  is  a  white  figure  on  a  uni- 
form dark  gray  background  that  extends  out  be- 
yond the  limits  of  the  visual  field. 

eral    things    can   be    stated    about    such    a 
figure. 

First  of  all,  the  figure  is  seen  as  a  single 
unitary  thing.  It  has  some  sort  of  shape, 
it  is  spread  out  in  space,  and  it  is  bounded 
by  edges  or  contours.  Characteristically, 
the  figure  seems  to  stand  out  slightly  in 
front  of  its  backgiound.  It  has  a  color,  and 
this  color  is  usually  seen  as  a  surface;  it  is 
dense  and  opaque,  seen  on  the  face  of  the 
figure,  spread  out  and  at  a  definite  distance 
away.  In  contrast,  the  ground  is  less  well 
localized  and  has  neither  a  well-defined  sur 
face  nor  bounding  edges. 


The  Simplest  Perception:  Figure  on  a  Ground 


225 


A  simple  perception  such  as  this  lies 
within  the  scope  of  animals  which  have  a 
nervous  system  like  man's.  They  respond 
as  if  they  'see'  a  figure  on  a  ground.  Such 
animals  include  birds  and  certainly  all 
mammals.  If  you  wish  to  train  a  cat  or 
dog  or  monkey  to  respond  to  some  stimu- 
lus, it  is  necessary  that  the  stimulus  be  set 
off  from  its  surroundings  so  that  it  is  a  clear 
signal. 

An  experiment  will  help  make  this  mat- 
ter clear.  Figure  85  shows  a  pattern  which 
was  used  in  testing  a  raven.  The  bird  was 
first  taught  to  look  for  food  under  an  in- 
verted flower  pot.  After  he  had  learned  to 
find  food  under  a  pot,  he  watched  while 
one  of  these  thirteen  pots  was  baited.  If 
the  food  was  placed  under  the  pot  A,  the 
bird  flew  to  this  outstanding  object  at  once 
and  found  the  morsel  left  for  him.  If,  how- 
ever, the  food  was  placed  under  the  pot  B 
or  any  of  the  eleven  other  pots  in  the 
circle,  the  bird  was  uncertain  and  confused 
and  made  many  errors  before  finding  the 
right  pot. 

Human  memory  also  depends  upon 
man's  perception  of  a  figure.  In  a  way, 
this  is  a  matter  of  common  observation. 
What  is  not  seen  as  a  figure  cannot  be  re- 
called later.  In  one  famous  experiment  a 
series  of  odd-shaped  patterns  were  shown, 
each  of  which  could  be  seen  in  two  differ- 
ent ways,  having  a  duplicity  like  that  of 
Fig.  88.  Later  on,  the  subjects  were  tested 
to  see  if  they  recognized  the  patterns  as  be- 
ing the  same  ones  they  had  seen  before. 
If  they  succeeded,  it  was  always  because 
they  saw  the  same  figure  in  the  test  that 
they  had  seen  originally  in  the  stimulus. 
But  if  the  alternative  figure  was  perceived 
on  the  second  showing  of  the  stimulus,  the 
pattern  seemed  strange  and  unfamiliar. 
It  is  the  figure,  not  the  stimulus,  we  recog- 
nize. 


Actually,  very  few  figures  are  as  simple 
as  the  cross  or  the  flower-pot  pattern.  Most 
figures  are  more  comjjlex  and  exhibit  quite 
a  number  of  properties,  some  of  which  we 
shall  study  in  more  detail  when  we  come  to 
the  subject  of  vision.  A  few  of  the  more 
important  properties  of  figures  should, 
however,  be  mentioned  here. 


O 


o- 


o  ^  o 


o 
o 
o 


o 
o 


OqO 


FIGURE  85.      FIGURE-GROUND  PATTERN  USED  TO  TEST 
BIRDS 

A  raven  could  be  taught  to  find  food  under  the 
isolated  flowerpot  A.  It  was  unable  to  distinguish 
B,  or  any  other  pot  in  the  circle.     [After  M.  Hertz 

(1929).] 

(1)  All  figures  have  some  kind  of  shape. 
If  nothing  else,  they  are  vaguely  round  or 
extended.  Usually  they  have  a  veiy  defi- 
nite form  set  by  a  sharp  outline.  But  it  is 
not  enough  simply  to  name  and  to  de- 
scribe the  shape.  Shapes  can  be  smooth  or 
rough,  flowing,  angular,  compact,  regulai^lv 
stepped,  etc.  These  properties  represent 
something  w-hich  the  organism  is  doing 
about  shape,  something  which  goes  beyond 
the  simple  geometry  of  the  stimulus.  EiTist 
Mach,  a  famous  physicist,  made  this  clear 
by  a  simple  example  which  is  shown  in 
Fig.  86.  He  dre^^•  the  four-sided  figure  in 
the  two  positions  shown.  Looking  at  the 
two  figures,  we  call  the  one  a  diamond,  the 
other   a   square.      The   diamond    and    the 


226 


Perception 


square  have  quite  different  'dynamics,'  if 
we  may  use  the  word  to  describe  some- 
thing of  the  feehng  we  have  in  looking  at 
them.  The  important  difference  lies  in 
what  is  regarded  as  the  axis  of  symmetry 
of  each  figure.  In  the  square  the  axis  runs 
parallel  with  the  sides;  the  top  is  opposite 
to  the  bottom,  and  the  left  side  is  paired 
with  the  right  side.  In  the  diamond,  on 
the  other  hand,  the  axis  runs  from  one  cor- 


FIGURE   86.      A   DIAMOND   AND   A   SQUARE 

The  two  figures  are  identical  geometrically,  but 
they  are  perceived  as  two  quite  different  shapes. 
[After  E.  Mach  (1886).] 

ner  to  the  opposite  one,  and  the  sides  which 
are  paired  are  always  the  ones  next  to  each 
other. 

Shape  makes  a  difference  in  other  ways. 
Some  shapes  seem  to  be  preferred  over 
others  and  may  be  more  readily  or  more 
frequently  perceived.  If  a  simple  closed 
figure  like  a  square  or  a  circle  is  broken 
or  blurred,  it  tends  nevertheless  to  be  seen 
perfect  and  completed.  A  very  small 
brightness  difference  on  a  screen  will  be 
much  easier  to  see  if  a  thin  line  sets  off  a 
figure  at  the  point  where  the  difference  is 
supposed  to  appear.  A  very  faint  figure 
will  be  seen  more  readily  if  it  is  anchored 
in  our  field  of  view  by  an  index  or  by  ref- 
erence marks. 

(2)  Simple  figures  appear  to  have  a  sur- 
face which  is  only  just  evident.  Objects 
in  perception,  on  the  other  hand,  seem  to 
possess  a  surface  which   is  very   hard   and 


close  and  definite.  The  difference  between 
the  two  lies  principally  in  a  special  sort  of 
detail  which  is  present  in  complex  figures 
and  which  is  called  microstructure  or  tex- 
ture. Microstructure  is  present  when  there 
is  a  very  fine  detail  which  is  repeated  con- 
tinuously from  one  boundary  of  a  figure  to 
the  other.  There  are  certainly  other  things 
which  contribute  to  our  appreciation  of  a 
siuface,  but  microstructure  is  probably  the 
most  important. 

(3)  Just  as  surface  is  enhanced  in  com- 
plex figures,  so  may  the  impressions  of 
depth  and  solidity  be  somewhat  greater 
than  they  are  in  the  simplest  figure.  The 
impression  of  depth  increases  from  the 
simplest  to  the  most  complex  figures  as 
more  lines,  more  surfaces  and  planes  and 
more  figures  are  added.  Figure  87  helps 
to  make  this  clear.     These  outline  shapes 


FIGURE    87.       CUBES    AND    BARS 

Line  drawings  frequently  appear  to  be  solid, 
three-dimensional  objects.  How  many  bars  are 
there?     How  many  might   there  be? 

no  longer  appear  flat  and  thin,  as  indeed 
they  really  are  when  printed  on  this  page. 
They  appear  to  extend  back  into  space  and 
to  be  thick  and  solid.  In  the  case  of  the 
cubes  we  can  readily  imagine  that  there  is 
a  fourth  cube  behind  and  beneath  the  oth- 
ers filling  out  the  unseen  comer.  In  the 
other  case,  we  see  just  two  bars,  one  in 
front  and  one  behind.  The  one  behind  ap 
pears,  of  course,  to  be  continuous. 


The  Simplesf  Perception:  Figure  on  a  Ground 


227 


The  perception  of  depth  is  the  result  of 
the  common  action  of  many  factors.  Some 
contribute  largely  to  the  appreciation  of 
distance;  they  tell  us  how  far  away  things 
arc.  Others  have  more  to  say  about  the 
thickness  and  solidity  of  objects.     The  fac- 


THE    PETER-PAUL    GOBLET 


What  do  you  see,  the  goblet  or  the  famous  twins? 
Whichever  you  see,  try  to  find  the  other.  Then, 
when  you  have  found  the  other,  try  to  turn  the 
perception  back  to  what  it  was  at  first.  [After  E. 
Rubin  (1915).] 

tors  governing  depth  perception  will  be 
taken  up  in  detail  later  (pp.  298-304). 
What  is  important  here  is  to  point  out 
that  all  perceptions  of  objects  involve 
depth  in  some  small  degree  and  that  a 
strong  impression  of  depth  or  solidity  can 
be  created  with  patterns  whose  stimuli  are 
actually  flat  and  two-dimensional. 

(4)  Often  lines  are  arranged  so  that  not 
one  but  two  or  three  or  several  figures  can 
be  picked  out.  Everyone  at  some  time  or 
other  has  puzzled  over  the  mosaic  of  lines 


in  a  tile  floor  or  in  a  wallpaper  design. 
He  combines  first  one  .set  of  lines  and  tht-n 
another  to  form  constantly  changing  fig- 
ures. Such  patterns,  when  reduced  to  a 
simple  form,  bring  out  a  quite  basic  princi- 
ple in  the  perception  of  figures.  For  this 
purpose  the  psychologist  (onmionly  uses  a 
reversible  figure,  that  is  to  say,  one  in 
whi(h  there  are  two  equally  good  ways  o[ 
seeing  a  figure,  so  that  a  person  looking  at 
it  sees  first  one  and  then  the  other.  Figure 
88  and  Fig.  89  illustrate  two  common  in- 
stances. Figure  78  (p.  220)  is  another  in- 
stance. Figure  88  is  the  picture  of  a  fa- 
mous goblet  which  outlines  two  human 
profiles.  Can  you  find  the  two  faces? 
When  you  have  found  them,  what  has  hap- 


FIGURE   eg.      A   REVERSIBLE   CROSS 

Keep  vour  eves  fixed  near  the  center  of  the  fig- 
ine.  and  note  whether  you  see  an  x  or  a  +.  Main- 
tain your  fixation  and  see  how  long  the  cross  at 
which  you  are  looking  lasts. 

pened  to  the  goblet?  Or  examine  Fig.  89. 
Keep  your  gaze  as  steadily  in  the  center  of 
the  figure  as  possible.  Do  you  see  an  X  or 
a  +  as  the  figure?  If  you  think  you  can 
change  die  figure  at  will,  just  see  how  long 
you  can  continue  to  see  the  X  or  tlie  -f . 


228 


Perception 


Once  it  has  started  to  reverse,  nothing  can 
keep  it  fixed  for  long. 

The  principle  underlying  these  fluctua- 
tions can  be  understood  from  an  easy  ex- 
periment. Gaze  steadily  at  one  of  the  fig- 
ures in  Fig.  90  while  you  count  slowly  to 
25.  Then  turn  quickly  back  to  page  227 
and  glance  at  the  center  of  Fig.  89.    Which 


first  one  recovers.     Finally,   flip,   and  the 
first  one  is  back  again. 

This  process  of  satiation  affects  many 
characteristics  of  a  figure.  Size,  shape, 
depth,  perspective,  direction  and  mode  of 
movement  all  become  weakened  or  altered 
through  continued  observation.  Under 
proper  conditions,  the  changes  can  be  meas- 


FIGURE  90.      ADAPTATION  STIMULI  FOR  FIG.   89 

Keep  \oiii  e\es  fixed  near  the  center  of  either  figure  for  about  25  seconds.  Tlien  glance  quickly  at  the 
reversihle  figure  in  Fig.  89.  Is  the  cross  you  see  the  same  one  as  you  have  just  been  fixating?  Repeat  the 
experiment  with  the  other  cross. 


do  you  now  see,  the  X  or  the  +?  Repeat 
the  test  using  the  other  part  of  Fig.  90. 
W^hat  do  you  see  now?  Try  the  experi- 
ment  before   reading  further. 

What  has  happened  in  this  experiment 
is  exactly  what  happens  all  the  time  in  a 
reversible  figure.  Any  figure  process  grad- 
ually weakens  itself  as  it  continues.  We 
say  that  it  becomes  satiated.  In  Fig.  90 
you  do  not  notice  this  satiation  because  it 
is  possible  to  see  only  one  figure.  In  Fig. 
88,  however,  you  see  one  figure  which  giad- 
ually  weakens  itself  until  suddenly,  flip, 
the  other  figure  is  there.  Then  the  second 
figure  gradually  weakens   itself  while   the 


ured  directly,  but  that  is  rather  hard  as  it 
requires  very  close  observation.  More  fre- 
quently, the  satiation  is  noted  only  as  it 
leads  to  reversals  when,  as  we  saw  above, 
the  stimulus  can  be  made  ambiguous. 

OBJECTS    ARE    OUR 
COMMONEST    PERCEPTIONS 

In  reading  the  past  few  pages  you  may 
have  liad  the  thought,  "All  this  discussion 
of  simple  figures  is  well  enough  in  a  text- 
book and  in  the  laboratory,  but  it  has  noth- 
ing to  do  with  my  everyday  experience." 
You  may  say   that  your  world  is   full   of 


Objects  Are  Our  Commonest  Perceptions 


229 


people  and  chairs  and  tables,  shoes  and 
books  and  automobiles.  The  psychologist 
can  explain  trick  figures  and  odd  happen- 
ings, but  does  psychology  deal  with  the 
flesh  and  blood  of  what  we  see  and  hear 
and  feel? 

Science,  of  course,  always  deals  with  ab- 
stractions, and  the  abstractions  are,  indeed, 
less  'real,'  less  palpable,  than  the  actual 
observed  things  and  events  from  which  the 
abstractions  were  derived  and  which  they 
are  now  prepared  to  predict.  Nevertheless 
people,  chairs,  tables,  shoes,  books  and  au- 
tomobiles are  objects,  and  psychology  has  a 
great  deal  to  say  about  objects.  Just  what 
does  it  say? 

(1)  First  of  all,  objects  are  figures,  figures 
in  the  jaarticular  sense  we  have  been  using 
the  term.  An  object  is  something  which 
fills  a  certain  part  of  my  visual  field  and  is 
set  off  sharply  from  the  background,  and 
from  other  objects,  by  a  well-defined  con- 
tour. Within  the  contour,  the  object,  like 
a  good  figure,  is  coherent  and  continuous. 
What  happens  to  one  bit  of  an  object  also 
happens  to  the  neighboring  bit.  A  per- 
ceived object  acts  as  a  unit.  It  is  usually 
so  constructed  that  the  forces  underlying 
grouping  can  have  their  strongest  effect. 
When  a  drawing  or  a  picture  is  designed  so 
that  it  is  strongly  organized,  it  usually 
turns  out  to  be  such  a  good  figure  that  it 
looks  as  if  it  ought  to  be  an  object! 

(2)  In  the  second  place,  objects  usually 
present  the  eye  with  a  stimulus  pattern 
which  produces  good  surfaces  and  depth 
and  solidity.  Under  conditions  which  are 
suitable  for  their  perception,  the  surfaces 
of  objects  almost  always  possess  micro- 
structure.  The  lines  and  planes  of  an 
object  give  rise  to  light  and  shade  and  per- 
spective, which  are  powerful  determinants 
of  the  perception  of  depth.  Objects  are 
commonly  separated  from  one  another  in 


tfiree-dimensional  space.  All  these  factors 
contribute  to  the  impression  of  an  object 
as  a  separate,  space-filling  thing, 

(3)  In  the  third  place,  objects  almost  al- 
ways involve  cooperation  among  the  senses. 
Rarely  do  we  receive  information  about  an 
object  from  one  sense  alfjne.  There  is  a 
rustle  beside  us,  we  look  down,  and  there  is 
the  cat.  You  are  looking  at  the  pages  of 
this  book;  in  a  moment  you  will  reach  out 
and  turn  the  page,  touching  and  pushing  it 
in  the  act.  A  good  deal  of  the  mutual  aid 
which  one  sense  gives  to  another  depends 
on  timing.  Sight  and  sound  happen  at  the 
same  moment.  Sometimes  this  results  from 
what  the  objects  themselves  do.  The  cat 
moves,  your  friend  speaks;  such  events 
themselves  provide  you  with  multiple 
clues.  In  other  cases  the  perceiving  organ- 
ism itself  provides  half  the  information. 
If  you  move  your  head  or  eyes  a  bit  to  one 
side,  muscles  and  joints  tell  you  about  the 
movement.  At  the  same  time  there  are 
changes  in  what  you  see.  "Whenever  what 
happens  to  an  object  is  sensed  in  more  than 
one  way,  the  resulting  perception  is  likely 
to  be  more  complete  and  more  sharply  set 
off. 

The  contribution  of  the  senses  other 
than  vision  and  hearing  is  often  so  subtle 
that  it  goes  unnoticed.  There  is  a  tend- 
ency for  the  more  highly  developed  senses 
of  vision  and  hearing  to  'see'  or  'hear' 
everything,  even  though  some  of  the  infor- 
mation may  have  come  from  a  simpler 
sense.  Try  this  experiment.  Turn  the 
stem  of  your  watch  back'^vard  -with  your 
hands  behind  your  back.  Notice  how 
clearly  you  can  fee!  the  clicks  of  die  ratchet. 
Now  hold  the  watch  near  vour  ear  and 
turn  the  stem  again.  ^Vhat  does  the  sound 
of  the  click  do  to  the  feeling  in  your 
fina:ers? 


230 


Perception 


(4)  The  fourth  important  characteristic 
of  objects  is  that  they  have  meaning.  Every 
(onimon  object  in  your  view  is  thoroughly 
familiar  to  you.  You  not  only  see  it  but 
you  also  recognize  it  as  being  such  and 
such  an  object.  Your  pencil,  the  crumpled 
sheets  of  paper,  the  door,  the  books  you 
wish  you  were  reading,  none  of  these  is 
just  an  indifferent  object.  Even  something 
quite  new  and  unfamiliar  has  a  little  mean- 
ing. It  is  made  of  a  familiar  material.  It 
can  be  used  for  some  purpose.  It  does  or 
does  not  belong  here.  Later  it  may  have 
a  different  or  richer  meaning,  but  it  is  at 
least  not  a  complete  unknown.  Ebbing- 
haus'  nonsense  syllables  had  this  kind  of 
meaning.  They  were  not  meaningless. 
They  had  some  meaning,  and  their  great 
advantage  was  that  this  slight  meaning  was 
about  the  same  for  different  syllables. 

Meaning  in  this  sense,  it  should  be 
pointed  out,  is  not  the  same  as  a  dictionary 
definition,  although  the  two  are  not  unre- 
lated. Psychological  meaning  includes 
much  more.  Much  of  it  is  personal  and 
individual.  What  some  picture  means  to 
you  can  be  quite  different  from  what  it 
means  to  me.  Furthermore,  psychological 
meaning  includes  shades  and  nuances 
which  are  expressed  with  difficulty  in 
words. 

Specifically,  u'hat  an  object  means  to  us 
is  first  of  all  what  we  do  about  it.  This 
object  is  something  to  drink  from.  That 
object  we  use  to  make  marks  on  paper. 
Almost  every  object  is  dealt  with  in  some 
way.  One  of  the  commonest  things  we  do 
about  an  object  is  to  give  it  a  name.  A 
child  picks  up  something  and  quickly 
learns  to  say  "book"  or  "shoe"  or  "doll." 
Many  objects  have  meanings  not  so  much 
because  of  what  is  done  with  them  now  but 
because  of  something  which  happened   in 


the  past.  So  fundamental  is  this  depend- 
ence of  meaning  on  doing  that  it  has  be- 
come an  important  principle  of  education. 

Objects  also  have  meanings  because  they 
are  related  to  other  objects.  That  is  the 
rug  which  lies  by  the  door.  A  chair  is 
something  which  stands  at  a  table.  Horses 
pull  wagons.  Frequently  the  relations 
among  objects  are  not  just  indifferent  links 
but  are  directed  in  some  way.  This  handle 
is  a  part  of  a  machine.  This  spoon  belongs 
to  a  set  of  silver.  That  is  a  leaf  from  the 
tree  in  the  yard.  Part  of,  belonging  to, 
necessary  for,  these  are  samples  of  the  many 
kinds  of  relations  which  objects  may  have 
to  one  another. 

Meaning  is,  of  course,  a  much  larger 
subject  than  has  been  outlined  in  the  last 
few  paragraphs.  A  full  discussion  takes 
us  into  the  problems  of  language,  thinking 
and  concept  formation.  The  point  to  be 
established  here  is  simply  that  what  we  see 
and  what  we  hear  depend  in  some  measure 
on  what  the  things  we  see  or  hear  mean  to 
us.  Especially  is  meaning  a  help  when  we 
are  faced  with  something  that  is  confused 
or  overcomplicated.  A  student's  first  view 
through  a  microscope  is  usually  confused 
and  unclear;  to  the  skilled  biologist  each 
small  detail  fits  into  place.  In  contrast, 
meaning  contributes  very  little  at  the  sim- 
plest level;  complication  provides  an  op- 
portunity for  its  development. 

We  have  been  discussing  how  objects  are 
perceived.  The  question  might,  however, 
be  asked  with  propriety:  Why  do  we  need 
all  this  explanation  of  how  an  object  is 
perceived?  Is  it  not  obvious  that  there 
are  all  kinds  of  things  in  the  world,  and 
we  simply  perceive  what  is  there?  The 
answer  is  no;  it  is  not  obvious.  In  fact,  it 
is  not  true.    Here  are  the  reasons. 


7o  see  an  object  is  lo  have  something 
happen  within  you.  I'he  object  is  some- 
thing that  you  do,  an  event  in  your  brain, 
it  is  the  result  of  a  long  series  of  jjhysio- 
logical  events,  in  your  eye,  in  your  nerves, 
in  your  brain.  These  internal  events  have, 
in  turn,  been  set  off  by  proximal  physical 
events,  complex  patterns  of  light  waves  and 
movements  and  pressures. 

The  near-by  physical  event  usually,  but 
not  always,  starts  from  some  single  region 
out  in  space,  from  the  'physical  object'  that 
you  see,  and  hear  and  feel.  That  thing 
out  there  is  a  red  book  with  color  and 
solidity  and  weight,  or  at  least  it  seems  to 
be.  Actually  that  is  not  true.  The  red 
l:)ook,  the  puffing  engine,  the  crying  baby, 
they  are  events  within  you  which  are  about 
to  cause  you  to  read,  to  step  back,  to  pick 
up  the  child.  The  'object  out  there'  is  a 
physical  and  chemical  process.  You  know 
it  only  indirectly.  It  is  but  one  of  the 
causes,  several  times  removed,  of  the  event 
in  your  brain. 

That  the  object  exists  out  there  is  some- 
thing that  you  take  for  granted.  That  is 
proper,  since  many  of  the  formal  properties 
of  the  objects  are  mirrored  in  your  experi- 
ence of  them.  Man's  adjustment  to  the 
world  is  aided  by  the  fact  that  his  brain 
creates  an  acceptable  copy  of  what  goes  on 
outside  himself.  He  sees  squares  as  square. 
He  perceives  the  longer  of  two  times  as 
the  longer.  There  is  a  reasonable  corre- 
spondence between  stimuli  and  perceptions, 
but  it  is,  nevertheless,  contradicted  by  many 
exceptions.  In  perception,  for  example, 
white  is  simple.  In  light,  the  stimulus, 
white  is  a  mixture  of  colors,  that  is  to  say, 
a  mixture  of  many  wave  lengths.  But  seen 
white  is  known  directly  in  experience. 
The  wave  lengths  you  get  at  only  by  scien- 
tific inference. 


The  Consiancy  of  Objects  231 

THE    CONSTANCY    OF    OBJECTS 


It  would  l;(;  ever  so  much  f-asici  il  (>\> 
jects  we  once  perceived  stayed  fixed  and 
constant  in  relation  to  us.  They  do  not, 
of  course,  and  man  is  faced  with  the  neces- 
sity of  adjusting  his  behavior  to  the  chang- 
ing aspects  of  objects  around  him.  One  of 
the  major  difficulties  is  that,  having  seen 
an  object,  we  move  about,  towards  it,  away 
from  it,  to  the  one  side  or  the  other.  As 
we  move,  the  proximal  stimulus  (the  light 
entering  the  eye)  changes.  The  image  on 
the  retina  grows  smaller  or  larger  or 
changes  in  shape.  There  is  the  .same  trou- 
ble when  the  object  itself  moves.  Or  again, 
the  colors  and  brightnesses  of  objects  change 
as  the  Sim  rises  or  sets,  as  we  pass  from 
the  sunlight  into  the  shadow,  or  as  we  add 
man-made  light  to  that  provided  by  nature. 

To  the  simplest  organism  all  changes 
must  appear  alike,  whatever  may  have  been 
the  cause.  One  thing,  the  immediate  stini- 
idus,  is  altered  and  for  all  it  knows  the 
world  itself  around  it  is  changing  in  its 
very  nature.  To  man,  to  us,  the  world  is 
quite  different.  We  move  around  among 
fixed  and  constant  objects.  Our  point  of 
view  may  change  but  the  things  at  which 
we  are  looking  do  not.  This  important 
aspect  of  perceiving  is  called  object  con- 
stancy. 

It  is  convenient  to  divide  the  total  prob- 
lem of  object  constancy  into  constancies  of 
the  various  aspects  of  the  object  itself. 
Thus  we  speak  of  size  constancy,  shape  con- 
stancy, whiteness  (brightness)  constancy, 
color  constancy,  velocity  constancy,  etc. 

Size  Constancy 

Constancy  of  size  is  both  one  of  the  most 
perfect  constancies  and  one  of  the  easiest  to 
understand.     Let  us  take  it  as  an  example 


232 


Perception 


But  first  of  all  let  us  review  some  simple 
geometry. 

Everyone  knows  that  the  eye  acts  like  a 
simple  camera.  The  lens  in  the  front  of 
the  eye  throws  a  picture  of  what  is  outside 
on  the  sensitive  retina  which  lines  the  back 
of  the  eyeball.  The  si/e  of  the  image  on 
the  retina  may  be  determined  by  drawing  a 


change  in  size  of  the  retinal  image  might 
equally  well  be  produced  by  a  change  in 
the  size  of  the  object  itself  or  by  a  change 
in  the  distance  away  of  a  constant  object. 

It  is  clear  that  a  physical  object  of  fixed 
size  produces  in  the  eye  a  series  of  con- 
stantly changing  images  as  the  object  comes 
closer  or  goes  farther  away.     What  about 


Near 

FIGURE   91.      GEOMETRY    OF    THE   EYE 

The  diagram  shows  how  an  object,  represented  by  an  arrow,  throws  an  image  on  the  sensitive  retina 
in  the  back  of  the  eye.  Note  particularly  that  the  smaller  image  F-F  may  be  produced  either  by  the 
short  arrow  at   the  near  distance  or  the  large  arrow   at    the   far   distance. 


Straight  line  from  any  point  on  the  object 
out  in  space  through  a  crossing  point  just 
behind  the  lens  and  extending  it  until  it 
meets  the  retina.  Such  lines  are  shown  in 
Fig.  91.  Notice  that  the  near  arrow  throws 
a  large  image  on  the  retina,  indicated  by 
the  letters  N-N.  If  the  same  arrow  were 
twice  as  far  away,  it  would  produce  the 
smaller  image  F-F.  .Actually,  the  change  in 
the  linear  size  of  the  retinal  image  is  ex- 
actly proportional  to  the  change  in  the 
distance.  Only,  of  course,  the  changes  are 
reversed.  The  farther  the  object  is  from 
the  eye,  the  smaller  will  be  the  image.  If 
the  distance  is  doubled,  the  size  of  the 
image  is  halved.  But  it  is  more  important 
for  our  present  purpose  to  notice  that  the 
smaller  image  might  just  as  well  have  been 
formed  bv  a  smaller  object  such  as  the 
;iiiow  marked  S-S.     In  other  words,  a  given 


our  experience  under  these  conditions? 
Does  the  size  of  a  person's  head  grow  larger 
as  he  comes  toward  us?  Of  course  not. 
Only  if  he  is  very  far  ofE  and  we  are  not 
clearly  aware  of  the  distance,  as  happens 
when  we  look  down  from  a  tall  building, 
does  he  seem  to  become  abnormally  small. 
Try  the  experiment  of  setting  up  a  scries 
of  cards  of  graded  size  across  the  room  as 
shown  in  Fig.  92.  Hold  another  card  in 
your  hand  and  see  if  you  can  pick  out  the 
card  in  the  series  having  the  same  size. 
Usually  we  find  that  the  judgment  is  al- 
most perfect— perfect  on  the  assumption 
that  there  is  a  constancy!  If  the  card  in 
the  hand  is  four  inches  wide  and  the  dis- 
tance of  the  observer  from  the  table  is 
twelve  feet,  the  observer  is  matching  the 
image  of  the  card  in  hand  to  the  image  of 
the  card  in  the  series,  when  one  image  is 


Size  Constancy 


233 


actually    lliirty-six    times    as    wide    as    the 
other. 

riic  secret  ol  these  amazing  judgments 
lies  largely  in  our  ability  to  judge  distance 
correctly.  We  know  that  the  card  across 
the  room  which  throws  a  small  image  on 
our  retina  is  at  a   much  greater  distance 


shows  this  same  carry-over  of  size  constancy 
into  their  representation  of  landscapes.  In 
old  Chinese  and  Japanese  paintings  in  par- 
ticular, objects  supposed  to  be  at  different 
distances  from  the  obseiver  still  liave  the 
same  size  in  the  drawing.  An  example  of 
this,  in  exaggerated  form,  is  shown  in  Fig. 


FIGURE  92.      TEST  OF  SIZE  CONSTANCY 

The  problem  is  to  designate  the  card  on  the  table  which  is  the  same  size  as  the  one  held  in  the  hand. 
The  task  is  accomplished  easily  and  correctly,  although  the  retinal  image  of  the  one  in  the  hand  is  at  least 
36  times  as  large  as  the  retinal  image  of  its  match  on  the  table. 


than  the  one  we  hold  in  our  hand.  Size  is 
always  judged  as  a  function  of  distance. 

So  conipulsory  is  constancy  in  the  percep- 
tion of  size  that  even  an  artist  cannot  al- 
ways overcome  it.  The  drawings  of  chil- 
dren illustrate  the  problem  in  the  extreme. 
A  child  is  likely  to  draw  a  man  the  same 
size  wherever  he  inay  be.  It  is  not  clear 
to  the  child  that  the  drawing  of  a  man  is 
something  which  should  change  constantly 
in  actual  size.  The  child  does  not  care  too 
much,  for  his  drawings  are  really  a  way  of 
telling  us  about  something,  a  kind  of  sign 
language,  rather  than  a  picture  of  the 
world. 

The  formal  art  of  some  Eastern  peoples 


93.  Note  how  the  men  drawn  in  the  back- 
ground to  the  left  are  as  large,  or  actuallv 
a  little  larger,  than  those  in  the  foreground. 
It  is  wrong  to  suppose  that  the  Japanese 
artist  did  not  know^  better.  This  same 
artist,  using  a  different  stvle,  might  have 
pictured  the  sizes  of  objects  correctly,  but 
he  was  bound  by  a  tradition  whicli  made  it 
improper  for  him  to  draw  figures  ^vith  pho- 
tographic precision.  It  is  only  that  his  ua- 
dition  is  different  from  ours.  Even  we  of 
the  Occident  did  not  fullv  develop  the  use 
of  perspective  in  art  until  tfie  fifteenth  cen- 
tury, although  the  general  principles  were 
understood,  though  not  ah\a\s  used,  by  the 
ancient  Greeks  and  Romans. 


234 


Perception 


■dM^^ 


I'IGURE    9;j.       JAPANESE    HISIORICAI,    SCENE    OF    1  HE    FlllEENTH    CENTURY 

A  drawing  by  Sesshii  in  Avhich  the  artist  followed  a  style  which  did  not  allow  for  size  constancy.  Note 
ilie  distorted  linear  perspective  and  the  large  size  of  the  more  remote  figures.  [From  J.  C.  Conell,  Uiuler 
tlie  seal  of  Si'ssliii,  De  Pamphilis,   1941.] 


(Further  information  abotit  si/e  constancy 
appears  in  the  chapter  on  visual  space  per- 
ception, pp.  304  f.) 

Whiteness  Constancy 

Tlie  instance  of  constancy  which  has 
been  most  widely  investigated  is  whiteness 
constancy.  This  visual  characteristic  has 
been  in  many  ways  more  interesting  than 
size  because,  since  we  commonly  experience 
something  less  than  perfect  whiteness  con- 
stancy, it  has  been  possible  to  discover 
more  readily  which  factors  help  the  effect 
and  whicli  hinder  it  and  also  to  meastue 
the  relative  importance  of  these  factors. 


Whiteness  constancy  is  familiar  to  every- 
one. Our  scale  of  blacks  and  whites  re- 
mains quite  stable  even  though  the  level 
of  ilhmiination  changes  a  great  deal.  The 
most  common  change  in  illumination  is 
the  result  of  shadows.  There  is  less  light 
in  a  shadow,  and  a  piece  of  white  paper, 
for  instance,  will  reflect  much  less  light 
when  it  is  in  shadow  than  when  it  is  in  full 
illuinination.  It  seems,  nevertheless,  al- 
most as  white  in  shadow  as  in  bright  light, 
provided  we  know  that  the  object  we  are 
looking  at  really  is  a  piece  of  white  paper. 

To  measure  the  effect  of  shadows  on 
whiteness  constancy  an  expeiiment  can  be 


Whiteness  Constancy 


235 


set  up  as  shown  in  the  plans  ol  Fig.  94. 
Two  spinning  cardboard  disks,  A  and  B, 
are  set  up  in  one  end  ol  a  room.  Ihe  light 
comes  in  from  the  window  W  at  one  side. 
The  light  falls  directly  on  disk.  B,  while  a 
screen  S  cuts  off  the  light  from  disk  A  and 
iasts  a  shadow  over  it.  A  person,  who  is 
standing  at  O,  compares  the  two  disks, 
judging  their  relative  whitenesses. 


T 


X 


w 


I. 


% 


sl^/    ^ 


R 


o 


IIGURE    94.       PLAN    OF    EXPKRIMKNT   TO    MEASURE 
WHITENESS   CONSTANCY 

I'laii  I  shows  the  arrangement  for  measuring  con- 
stancy. Plan  II  shows  the  arrangement  for  the 
'reduction'  equation.  A  and  B  are  the  disks  to  be 
matched.  W  is  a  window,  the  source  of  light.  S 
is  a  screen  casting  a  shadow  on  disk  A.  O  is  the 
oljserver  Avho  makes  the  judgments,  ii  is  a  reduc- 
tion screen  cutting  off  all  the  field  except  small 
patches  of  A  and  B. 

Each  disk  consists  of  a  black  and  a  white 
sector  which  fuse,  when  the  disks  are  spun 
rapidly  by  motor,  to  give  a  uniform  gray. 
Let  us  assume  that  disk  A  which  is  in  the 
shadow  is  made  up  of  320  degrees  of  white 
and  40  degrees  of  black.  The  experi- 
menter now  adjusts  the  proportions  of 
white  and  black  in  disk  B  until  the  ob- 
server says  the  two  disks  are  equal  in  white- 
ness. 

What  proportions  of  white  and  black 
might  we  expect  to  find  in  disk  B}  Table 
XIV  makes  clear  the  various  possibilities.  If 


TABLE  XIV 

Rksiji.ts  or  Whitrness-Constancv  Kxprriment 


Perfect  constancy 
Actual  constancy 
No  constancy 

(reduction  equation) 


Disk  A  nUk  P  PerrftUacc 

(in  skadirw}  (in  li(lili  ConiUinry 

320°  white  320°  while  lOfJ 

320°  while  152°  while  40 

320°  white  40°  white  0 


there  were  perfect  constancy,  that  is  to  say, 
if  the  observer  could  discount  completely 
the  darkening  produced  by  the  shadow, 
disk  B  would  also  have  320  degrees  of 
white. 

The  other  end  of  the  scale,  an  equation 
which  would  reveal  no  constancy,  requires 
that  we  make  a  special  measurement  as  in 
plan  II  of  Fig.  94.  Here  a  second  screen  R 
with  two  holes  in  it,  a  reduction  screen, 
has  been  placed  in  front  of  the  observer 
so  that  all  he  can  see  is  a  small  section  of 
each  disk.  No  longer  can  he  see  that 
[here  is  a  shadow  and  he  has  to  judge  the 
brightness  of  each  disk  reduced  to  the 
common  conditions  of  proximal  stimula- 
tion by  the  reduction  screen.  Under  a 
given  set  of  conditions,  conditions  which 
vary  widely  from  one  experimental  setup 
to  another,  he  might  find  that  only  40  de- 
grees of  white  in  disk  B  would  be  required 
in  the  second  equation. 

Now  if  the  reduction  screen  is  removed 
and  an  equation  is  made  with  the  arrange- 
ment shown  by  plan  I  of  Fig.  94,  we  shall 
be  measuring  the  actual  amount  of  'con- 
stancy' achieved.  Such  a  measurement  will 
tell  us  how  well  the  shadow  has  been  dis- 
counted. A  typical  result  is  sho^vn  by  the 
second  line  of  Table  XIV.  Disk  B  \\i\\  be 
152  degrees  white,  a  value  whicla  lies 
ii%,yQ  of  the  way  from  no  constancy  to 
perfect  constancy. 

From  the  result  of  experiments  which 
have  followed  this  general  plan  it  is  pos- 
sible to  formulate  the  follo-\ving  rules. 


236 


Perception 


(1)  The  most  important  single  condition 
of  whiteness  constancy  is  the  backgiound 
against  which  the  disks  are  seen.  In  fact, 
it  has  recently  been  shown  that  almost  per- 
fect constancy  can  be  achieved  if  each  disk 
is  close  to  its  background,  and  the  two 
sets  of  disk-phis-background  are  well  sep- 
arated. In  other  instances  the  background 
is  effective  only  as  fixing  a  general  level  in 
terms  of  which  each  item  in  a  given  part 
of  the  field  is  evaluated. 

(2)  Second  in  importance,  particularly  if 
the  backgiound  is  placed  so  far  away 
from  the  disk  that  it  can  no  longer  play  an 
important  part,  is  the  clear  perception  of 
the  shadow.  That  there  is  a  shadow  may 
be  seen  from  several  details.  For  instance, 
the  edge  of  the  shadow  may  fall  across  the 
top  of  the  table  on  which  the  screen  and 
the  disks  are  sitting.  Or  the  screen  may 
cast  a  shadow  on  some  more  remote  object 
in  the  background.  One  way  of  showing 
how  strong  is  the  effect  of  the  shadow  is  to 
mo\e  the  screen  so  that  the  edge  of  the 
shadow  falls  across  disk  A.  Almost  perfect 
constancy  will  be  the  result.  Shadows  are 
recognized  as  such  because  they  usually 
have  a  penumbra,  which  is  the  fuzzy  edge 
that  most  shadows  have. 

(3)  If  there  is  light  from  some  special 
source  or  if  neither  the  background  nor 
the  edge  of  the  shadow  gives  sufficient  clues, 
constancy  ma\'  be  improved  by  putting  anv 
small  object  in  the  field  of  view  around 
disk  A.  These  small  objects  serve  as  tiny 
guideposts  to  give  the  observer  information 
about  the  amount  of  light  on  disk  A. 

(4)  Objects  in  their  natural  surroundings 
are  helped  out  considerably  by  the  percep- 
tion of  the  whole  pattern  of  illiunination 
in  a  room.  There  will  be  giadual  falling 
off  of  brightness  as  one  goes  away  from  the 
window  or  other  source  of  illumination. 
Furthermore,    there    will    be    the    lines    of 


shadows  all  pointing  away  from  the  place 
from  which  the  light  is  coming.  Often  this 
sort  of  general  information  about  the  light- 
ing of  the  room  helps  out  constancy  a  great 
deal. 

General  Explanation  of  Constancy 

The  general  problem  of  constancy  may 
be  formulated  without  difficulty  from  these 
two  examples.  Let  us  say  that  each  case 
of  constancy  represents  a  problem  of  tivo 
syste??is.  The  organism  is  trying  to  handle 
a  situation  in  which  the  stimulus  is  con- 
stantly changing.  For  practical  reasons  we 
prefer  to  operate  in  a  world  in  which 
objects  appear  to  be  constant.  It  would 
be  most  inconvenient  if  objects  were  con- 
stantly shrinking  and  expanding,  changing 
their  shapes  and  color  and  brightness. 
What  the  organism  does  is  to  split  its  in- 
formation about  the  world  into  two  sys- 
tems, one  of  which  it  can  maintain  steady 
and  constant. 

In  Table  XV  we  can  see  just  what  pairs 
of  systems  are  operating  in  the  more  fa- 
miliar constancies.     The  first  two  columns 

TABLE  XV 

The  Perceptual  Constancies 


Proximal  Stimulus: 

Variable 
Size  of  image  in  eye 
Shape  of  image  in  eye 

Intensity  of  light  in 

eye 
Spectral  composition 

of  light 
Intensity  of  sound  at 

ears 


Situation  of 

Stimulus  Object: 

Variable 


Property  of 

Perceived  Object: 

Constant 


Distance  of  seen  object  Size  of  seen  object 

Angle  of  object  to  the  Shape  of  seen  ob- 

line  of  regard  ject 

Illumination  on  sur-  Whiteness  of  sur- 
face face 

Color  of  illuminant  Color  of  surface 

Distance  of  sound  from  Loudness  of  sound 

listener  at  its  source 


Proximal  Stimulus 
Variable 


Condition  oj 

Obsercation: 

Variable 


Properly  of 

Perceived  Object: 

Constant 


Displacement  of  im-  Turning  of  head  or  Location  of  seen 
age  in  eye                      ■  eyes  object  in  space 

Binaural  difference  in  Turning  of  head  or  Location  of  sound 
time  or  intensity            body  in  space 


Space  Perception 


237 


show  the  two  variables  which  the  organism 
integrates  to  achieve  the  constancy  which 
is  noted  in  the  third  column.  In  size  con- 
stancy, for  example,  the  proximal  stimulus 
(changing  size  of  the  image  on  the  retina) 
works  concurrently  with  the  situation  of 
the  stimulus  object  (changing  distance  of 
the  seen  object)  to  effect  size  constancy  of 
the  perceived  object.  Thus  perceived  ob- 
ject size  becomes  the  system  in  which  things 
remain  constant,  whereas  distance  is  the 
system  in  which  they  vary.  In  whiteness 
constancy,  the  two  systems  are  whiteness 
and  illumination.  The  former  is  constant, 
the  latter  varied. 

The  great  utility  of  this  arrangement  to 
the  organism  is  evident.  By  and  large, 
physical  objects  in  the  world  are  constant, 
whereas  conditions  of  observation  are  vari- 
able. The  mechanism  of  object  constancy 
goes  a  long  way  towards  enabling  the  or- 
ganism to  deal  with  the  physical  world  in 
a  manner  suited  to  the  world's  actual  con- 
struction. 

THE    FRAMEWORK    OF 
PERCEPTION:    SPACE 

Up  to  this  time  we  have  centered  our  at- 
tention on  objects  and  have  said  little 
about  the  space  they  occupy.  The  objects 
themselves  may  be  short,  long,  wide  or 
thin,  but  in  addition  they  may  be  located 
to  the  right,  left,  behind,  above,  around 
other  objects  in  the  field.  Distance  between 
two  objects  is  just  as  real  as  the  distance 
on  the  surface  of  one  object.  Space  is  a 
dimension  of  experience,  a  characteristic 
about  which  we  have  to  ask  the  questions 
how  far?  what  direction?  where  does  it  start 
and  stop? 

Space  does  not  belong  to  one  sense  alone. 
It  is  common  to  several  senses.  Distance  felt 
on    the    skin    is    related    to    the    distance 


through  which  you  feel  your  finger  moving, 
and  the  size  of  an  object  held  in  your  hand 
is  like  the  size  you  .see  with  your  eyes.  The 
space  perceived  is  the  joint  creation  of 
several  senses  and  is  richer  for  the  contribu- 
tion of  each. 

riie  dimensions  of  perceived  space  must 
be  chosen  with  reference  to  the  problems 
to  be  studied.  The  real  world  of  objects 
is  fitted  into  three  dimensions— uj>-do\vn, 
north-south,  east-west  or  else  some  other 
system  of  three  coordinates.  The  world  of 
visual  perception  similarly  has  three  di- 
mensions—up-down, right-left,  near-far. 
Perceived  up-down  may  approximate  the 
geographical  vertical  or  it  may  differ  from 
it.  Near-far  is  not  perceived  so  precisely 
as  up-down  and  right-left;  its  mechanism 
is  more  complex,  its  correspondence  with 
reality  not  so  sure.  In  the  field  of  auditory 
space  perception  the  primary  dimension  is 
right-left,  determined  by  the  spatial  rela- 
tion of  the  two  ears.  Direction  up-and- 
down  is  less  accurately  perceived,  and 
near-far  is  so  uncertain  in  heard  space 
as  sometimes  not  to  figure  at  all  in  the 
localization  of  sound  (see  p.  337).  Kines- 
thetic space— for  instance,  the  space  that 
an  animal  experiences  in  a  maze  or  an 
automobilist  in  old  Boston— is  something 
else  again.  It  is  a  space  of  connections  and 
may  have  nothing  at  all  to  do  with  the 
points  of  the  compass  (see  pp.  380-384). 

Because  there  is  a  fair  degree  of  coiTe- 
spondence  between  the  geometry  of  ph\s- 
ical  space  and  the  dimensions  of  \isuallv 
perceived  space,  it  is  tempting  to  believe 
that  there  is  some  necessary  relationship 
between  them.  It  is  so  easv  to  think  that 
we  see  this  object  near  by  and  that  object 
far  off  simply  "because  that  is  the  way  thev 
are."  Yet  most  people  can  realize  that  this 
statement  is  not  true.  'When  vou  look  at 
die  stars,    for   instance,   vou   see    them   all 


238 


Percepfion 


roughly  the  same  distance  away.  Actually, 
one  star  may  be  thousands  of  times  as  far 
away  as  another  which  looks  to  you  equally 
distant.  On  the  other  hand,  you  may  per- 
ceive depth  where  there  is  none.  Two  flat 
photographs  when  viewed  properly  in  a 
stereoscope  produce  an  impression  of  depth 
^vhich  cannot  be  o\ercome.  There  is  no 
escape  from  the  conclusion  that  percei^•ed 
space,  like  other  perceived  qualities,  is 
something  which  exists  within  each  of  us. 
How  then  shall  we  account  for  perceived 
space?  What  takes  place  in  the  eye,  in  the 
brain,  in  order  that  the  perceiving  organ- 
ism can  usually  respond  so  neatly  to  actual 
places  and  things?  Let  us  consider  first  a 
few  general  points  that  answer  these  ques- 
tions, filling  in  some  of  the  details  later. 

(1)  First  of  all  the  organism  must  have 
sense  organs  which  are  able  to  respond  to 
the  appropriate  physical  stimulus  that  is  re- 
cei\ed  from  the  object.  The  eye  must  be 
sensitive  to  light,  the  skin  to  contact,  the 
ear  to  sound.  Furthermore,  each  of  these 
sense  organs  must  be  able  to  give  a  differ- 
ent response  when  a  different  space  is  oc- 
cupied by  the  stimulus  object.  Thus  the 
eye  must  respond  differently  to  a  large  ob- 
ject than  it  does  to  a  small  one;  the  ears 
must  act  differently  when  a  sound  comes 
from  the  right  or  from  the  left.  Patterns  of 
stimulation  are  set  up  in  the  sense  organs 
which  correspond  in  some  degree  with  the 
properties  of  the  world  we  are  perceiving. 

(2)  The  brain  and  the  nerve  pathways 
leading  from  the  sense  organs  to  the  brain 
must  be  constructed  so  that  the  informa- 
tion from  the  sense  organs  is  properly  trans- 
mitted and  registered  in  the  brain.  It  was 
once  supposed  that  this  effect  was  managed 
by  means  of  a  set  of  fixed  connections, 
single  nerse  fibers  running  from  a  recep 
tor  to  a  fixed  point  in  the  brain.  The 
brain  was  thought  to  be  like  a  large  electric 


sign  with  thousands  of  lights,  each  light 
connected  by  a  single  wire  to  a  single 
switch  or  photocell  so  that  a  pattern  of 
light  and  dark  falling  on  the  bank  of  photo- 
cells is  reproduced  point  by  point  on  the 
electric  sign. 

Modern  physiology  has  made  it  quite 
clear  that  this  picture  of  the  nervous  sys- 
tem is  in  error.  True,  there  must  be  avail- 
able a  number  of  nerve  fibers  and  nerve 
cells  sufficiently  large  to  copy  the  pattern 
of  stimulation.  But  order  is  maintained 
among  the  many  impulses  passing  to  the 
brain  only  by  functional  relations  among 
the  messages  in  the  nerves  and  centers 
along  the  line. 

As  an  analogy  we  may  think  of  the  nerv- 
ous system  as  a  football  team  making  a  par- 
ticular play.  Where  the  play  goes,  the  pat- 
tern of  the  moving  men,  depends  neither 
upon  exact  distance  nor  upon  particular 
men.  Off -tackle  means  inside  the  end  man 
and  outside  the  rest  of  the  line.  Perhaps  a 
better  example  would  be  a  well-trained 
army  as  it  moves  forward.  Each  man  in 
the  skirmish  and  supporting  line  must 
guide  his  movements  in  terms  of  the  men 
on  either  side  of  him.  Once  given  a  pat- 
tern or  order  of  attack,  that  order  is  main- 
tained as  the  entire  group  moves  forward. 
Pattern  is  transmitted  to  the  brain  by  such 
team  play.  The  physiological  mechanisms 
by  which  one  fiber  works  with  its  neighbor 
include  simimation,  inhibition,  thresholds 
and  proper  timing.  Order  may  also  be 
maintained  by  electrical  or  chemical  factors 
which  sene  to  unify  the  actions  of  many 
individual  nerve  cells. 

(3)  Once  the  information  recei\ed  by  the 
sense  organs  has  been  relayed  to  the  brain, 
the  brain  takes  charge  of  the  job  of  inter- 
preting this  material.  Each  item  must  be 
located  with  reference  to  other  items  being 
perceived  at  that  moment  or  to  points  sup- 


Space  Perception 


239 


plied  by  memory.  Each  item  will  be  lo- 
cated or  anchored  with  respect  to  a  total 
fratne  of  reference. 

If  a  person  looks  at  a  single  small  spot 
of  light  in  the  dark,  its  location  is  a  very 
imstable  affair.  The  spot  wanders  first  in 
one  direction  and  then  in  another;  it 
pauses  and  speeds  up,  stops  and  reverses, 
but  the  extent  of  the  movement  is  seldom 
seen  to  be  more  than  40  degrees.  Such  seen 
luovement  is  called  autokinetic. 

If  a  second  spot  of  light  is  now  intro- 
duced at  a  fixed  distance  from  the  first, 
two  things  happen.  First  of  all  the  two 
spots  together  will  undergo  aiUokinetic 
movement,  but  the  speed  and  extent  of  this 
two-spot  movement  will  be  less  than  it  was 
with  one  spot  alone.  Second,  the  distance 
and  direction  of  the  spots  from  each  other 
will  imdergo  some  change.  It  is  as  if  each 
of  the  dots  were  trying  to  move  as  it  would 
were  it  alone;  yet  each  is  constrained  by  the 
presence  of  the  other  spot  in  the  field. 

The  introduction  of  a  third  spot,  or  a 
fourth  or  fifth,  increases  the  effects  noted 
when  the  second  spot  was  added.  With 
each  further  spot  the  movement  of  the  total 
pattern  is  gradually  reduced,  and  the  rela- 
tions of  the  spots  to  one  another  become 
more  and  more  stable.  From  these  experi- 
ments it  appears  that  the  position  of  a  fig- 
ure in  the  visual  field  depends  in  some 
measure  on  its  anchorage  to  the  other  fig- 
ures in  the  field.  For  any  given  item,  the 
rest  of  the  items  in  the  field  constitiUe  its 
frame  of  reference.  Autokinetic  movement 
does  not  occur  if  there  is  a  fixed  frame  of 
reference. 

Let  us  look  briefly  at  another  experiment 
which  extends  this  conclusion.  Suppose 
that  we  are  looking  at  two  spots  of  light 
in  a  completely  darkened  room.  One  of 
the  spots  is  much  larger  than  the  other,  or, 
better,  the  larger  is  an  outline  of  a  square 


or  circle.  Let  one  of  the  stimuli  actually 
move  back  and  forth.  We  shall  fliscovcr 
at  once  that  it  makes  no  difference  which 
stimulus  actually  moves,  for  the  small  fig- 
ure will  always  be  .seen  to  move  %v'hile  the 
large  one  remains  at  rest.  Particularly  is 
this  true  when  the  large  outlined  figure 
moves  back  and  forth  with  the  small  figure 
located    within    it,    as    shown    in    Fig.    '.)r>. 


FIGURE    95. 


XPERIMENT    TO    SHOW 
MOVEMENT 


An  observer,  sitting  in  the  dark,  sees  iwo  dimly 
lighted  squares.  The  large  square  is  moved  to  and 
fro.  The  small  square  remains  stationary.  The 
observer,  however,  sees  the  small  stationary  square 
moving,  not  the  large  square  which  actually  is 
moving.    [After  K.  Duncker  (1929).] 

Then  the  small  enclosed  figure  will  appear 
to  do  all  the  moving.  We  call  this  phe- 
nomenon induced  movement.  Do  you  re- 
member marveling  as  a  child  upon  the  fact 
that  the  moon  seemed  to  race  across  the  sky 
when  it  was  the  clotids  which  were  drift- 
ing over  it?  Induced  movement  shows  us 
that  a  larger,  enclosing  figure  forms  a  more 
stable  frame  of  reference  than  a  small  iso- 
lated figure. 

Even  the  rate  of  any  movement  is  judged 
in  terais  of  its  particular  frame  of  refer- 
ence. A  set  of  dots  is  arranged  to  move 
behind  each  of  two  windows,  as  sho^^"n  in 
Fig.  96.  The  dots  will  have  to  be  moved 
fii'icr  as   fast   plixsicallv   in   the  larger  win- 


240 


Perception 


clow  as  they  are  moving  in  the  smaller  in 
order  to  appear  to  have  the  same  velocity. 
The  frame  of  reference  in  which  places 
and  positions  are  anchored  is  not  a  matter 
of  the  present  alone.  Our  memory  of  what 
has  been  seen  in  the  past  can  serve  us  just 
as  well.  A  carpenter,  for  instance,  knows 
the  size  of  each  nail  at  a  glance.  The 
plumber  picks  out  the  right  size  of  pipe 


throw  a  ball,  or  that  when  you  thread  your 
way  through  a  crowd,  it  is  the  eye  which 
helps  you  to  pick  out  the  correct  move- 
ments. On  the  other  hand,  what  your  eye 
sees  would  have  no  meaning  were  it  not 
for  your  hand.  If  you  were  to  be  para- 
lyzed all  your  life,  and  what  happened 
around  you  rolled  off  like  a  movie  on  a 
screen,  what  you  would  sec  woidd  have  a 


FIGURE    q6.       FRAME    OK    REFERENCE   DETERMINES    RATE    OF    MOVEMENT 

The  large  dots  moving  behind  the  large  opening  must  have  twice  the  physical  velocity  of  the  small 
(lots  behind  the  small  opening  if  the  two  sets  are  to  appear  to  move  at  the  same  speed.  [After  J.  F. 
Brown  (1931).] 


or  fitting  unerringly.  The  skilled  sales- 
man picks  the  right  shoe  from  the  shelf  or 
coat  from  the  rack  without  measuring  the 
customer.  Such  standards  or  anchors  may 
be  accumulated  over  a  long  period  of  time 
and  carried  imconsciously.  Since  there  is 
no  easy  way  to  wipe  them  out,  it  is  hard 
to  estimate  how  much  effect  they  have 
upon  present  perception. 

(4)  Perceived  space  depends  on  the  joint 
contribution  of  several  senses  to  a  much 
greater  degree  than  we  ordinarily  realize. 
A  good  many  of  the  things  which  seem 
to  be  so  natural  and  fundamental  about 
space  actually  take  form  only  when  what 
we  see  is  brought  into  line  with  what  we 
hear,  and  with  our  feelings  of  movement. 
It  is  quite  correct  to  say,  for  instance,  that 
the  hand  is  guided  by  the  eye  when  you 


dreamlike  quality  indeed.  The  real,  sub- 
stantial quality  of  space  comes  from  your 
walking  and  moving  in  it,  your  doing  some- 
thing with  it.  Several  well-known  facts 
help  to  make  this  fact  clear. 

Suppose  that  you  are  looking  at  a  movie 
on  a  screen  directly  before  you.  Let  the 
picture  jump  quickly  and  violently  to  one 
side  or  up  and  down,  and  the  experience  is 
most  unpleasant.  Nothing  is  so  disturb- 
ing as  to  watch  amateur  movies  made  by  a 
cameraman  with  an  unsteady  hand.  Now 
consider  that  the  eye  is  far  more  unsteady 
than  the  worst  of  such  movies.  You  glance 
about  the  room  and  the  images  projected 
on  your  retina  will  shift  in  bewildering 
succession.  Yet  in  this  case  you  see  the 
world  standing  still!  The  difference  lies 
in  the  fact  that  when  )our  eyes  move  you 


Space  Perception 


241 


have  iul!  and  precise  information  about 
their  movements;  when  the  camera  moves 
you  do  not.  The  brain  is  able,  by  a  process 
which  seems  ahiiost  miraculous,  to  put  to- 
gether these  two  sets  of  facts,  the  moving 
visual  pictures,  on  the  one  hand,  and  the 
knowledge  of  eye  movements,  on  the  other, 
and  to  come  out  with  a  stable  stationary 
view  of  the  world. 

The  adjustments  of  this  mechanism  are 
not  always  quite  perfect.  When  you  are 
dizzy  you  are  no  longer  able  to  discount  the 
movements  which  your  eyes  make,  and  in 
consequence  the  world  'out  there'  seems  to 
move.  Ear  infections  and  diseases  of  the 
nervous  system  can  produce  unwanted 
movements  of  the  eyes  with  the  same  result. 
Another  familiar  experience  is  that  of  a 
person  who  puts  on  strong  glasses  for  the 
first  time.  His  eyes  make  the  accustomed 
movements  to  bring  a  new  object  into 
focus,  but  the  field  of  view  shifts  too  far 
or  too  little  because  of  the  strong  lens. 
Consequently  he  sees  everything  jump  each 
time  his  eyes  move.  Fortunately  experi- 
ence and  practice  gradually  correct  this 
state  of  affairs,  and  things  eventually  stay 
put  the  way  they  normally  do. 

This  same  kind  of  coordination  is  pres- 
ent when  you  hear  a  sound  coming  from  a 
particular  direction.  Hearing  the  sound, 
you  expect  to  be  able  to  look  for  it  'there' 
or  to  put  out  your  hand  and  touch  it  if 
it  is  near  by.  A  psychologist  once  upset 
this  relation  by  wearing  a  device  he  called 
a  pseudophone.  The  pseudophone  is  con- 
structed as  shown  in  Fig.  97.  It  has  one 
horn  and  a  tube  to  lead  to  the  right  ear 
the  sound  which  is  ordinarily  heard  by  the 
left,  and  another  horn  and  tube  to  lead  to 
the  left  ear  the  sound  ordinarily  heard  by 
the  right. 

Wearing  the  pseudophone  was  at  first  a 
most  upsetting  experience.     There  was  al- 


most con)plcte  reversal  of  sounds,  right  and 
left.  When  the  device  was  worn  out  on  the 
street  the  wearer  bumped  into  people  be- 
cause he  would  move  in  the  wrong  direc- 
tion when  he  heard  them  approaching. 
Automobiles  at  a  busy  intersection  created 
a  real  hazard.  If,  while  he  was  eating,  a 
waiter    addressed    him    on    his    right,    he 


FIGURE    97.      THE    PSEUDOPHO.N'E 

Sound  from  the  left  is  picked  up  by  the  horn  and 
led  through  the  tube  to  the  right  ear.  Sound  from 
the  right  goes  to  the  left  ear.  The  subject  therefore 
looks  for  the  source  of  the  sound  on  the  wrong  side 
until  he  has  adjusted  himself  to  this  novel  artificial 
situation.    [.A.fter  P.  T.  Voung  (1928).] 

would  turn  to  the  left  in  answering  him. 
If,  however,  he  saw  the  lips  of  the  person 
who  was  speaking  to  him  move,  he  located 
the  sound  correctly.  But  more  interesting 
was  the  fact  that,  after  some  time,  the 
^vearer  began  to  get  used  to  the  new  loca- 
tions which  sound  had.  Unfortunately  a 
long  experiment  was  not  possible.  If  the 
experiment  could  be  continued  long 
enough,  a  new  set  of  coordinations  between 
sound  and  sight,  and  between  sound  and 
movement,  would  probably  be  developed. 
Two  related  experiments  have  been  done 
in  vision.  In  one,  a  set  of  glasses  was  in- 
vented which  tipped  everything  over  at  an 
angle.  Naturally,  a  good  deal  of  difficulty 
was   encountered   when    these   glasses  were 


242 


Perception 


(irst  worn,  but  very  soon  everything  began 
to  straighten  up.  What  had  seemed  tipped 
when  the  glasses  were  first  put  on  now  be- 
(anie  vertical.  The  person  wearing  the 
glasses  could  walk  about  without  tending 
to  fall  over.  This  experiment  seemed  to 
show  that,  when  vision  is  distorted  in  this 
simple  way,  we  can  gradually  readjust  the 
relation  between  what  is  seen  and  our 
movement. 

The  other  visual  experiment  went  even 
farther.  The  glasses  were  constructed  so 
that  everything  in  the  visual  field  was 
turned  upside  down.  The  subject  had  a 
great  deal  of  difficulty  when  the  glasses 
were  first  worn.  After  several  days  of 
continuous  wear,  adjustments  were  grad- 
ually made  to  the  new  appearance  of  the 
visual  environment.  And  as  the  subject 
learned  to  carry  out  the  necessary  move- 
ments in  this  new  world,  the  visual  scene 
lost  its  character  of  being  upside  down. 
As  a  matter  of  fact,  right  side  up  and  up- 
side down  probably  have  little  meaning 
except  in  terms  of  what  we  do  about  them. 
Doxvn  is  a  direction  we  move  our  heads 
when  we  bend  over;  up  is  a  direction  we 
mo\e  our  feet  when  we  lift  them  from  the 
floor. 

THE    FRAMEWORK    OF 
PERCEPTION:    TIME 

Time,  as  we  experience  it,  is  a  good  deal 
like  space;  it  is  something  that  most  people 
just  take  for  granted.  We  are  usually  so 
occupied  with  what  is  happening  that  we 
pay  no  heed  to  the  temporal  frame  in 
which  our  experiences  are  set.  Only  oc- 
casionally does  time  become  the  specific 
object  of  our  attention,  while  we  are  wait- 
ing for  a  friend  to  keep  an  appointment, 
when  we  suddenly  realize  that  the  hour  has 
grown    late,   in    the   few   minutes   we   have 


left  for  last-minute  preparations.  Thus,  al- 
though all  our  experiences  are,  of  course, 
stretched  out  in  time,  it  is  only  when  some 
importance  attaches  to  time  that  Ave  par- 
ticularly notice  it. 

Perceived  time  is  also  like  pciceived 
space  in  that  it  is  easy  to  confuse  physical 
time  and  psychological  time.  AV'hat  we 
try  so  hard  to  judge  correctly  and  what 
counts  when  we  are  making  a  train  is 
clock  time.  Sometimes  we  succeed  quite 
well  in  getting  our  personal  internal  clocks 
regulated  so  that  they  agree  with  physical 
clocks.  But  any  person  who  has  to  'kill' 
time  is  convinced  that  the  physical  clock 
runs  much  too  slowly.  Clearly,  our  per- 
sonal clocks  do  not  always  keep  the  best 
of  time.  The  kind  of  time  they  do  keep  is 
a  matter  of  perception  and  must  be  ex- 
plained by  the  psychologists. 

A  couple  of  distinctions  are  in  order  be- 
fore we  begin  our  more  detailed  inquiry. 
First  of  all  we  must  distinguish  between 
time  which  we  can  know  directly  and  time 
about  which  we  have  knowledge.  Knoivl- 
edge  about  time  is  greatly  aided  by  hav- 
ing elaborate  means  of  keeping  time.  We 
are  beset  on  every  side  by  clocks  and  calen- 
dars. Our  getting  up  in  the  morning,  oin- 
going  to  class,  our  meals,  our  entertain- 
ment, all  these  events  are  regulated  by 
clocks  with  elaborate  means  to  insure  their 
synchronization.  Furthermore  our  lives 
for  weeks  and  months  and  years  ahead  will 
be  regulated  by  calendars.  In  the  absence 
of  such  formal  things  as  hours  and  dates, 
men  have  controlled  their  lives  by  the 
rhythms  of  natural  events,  the  rising  and 
setting  of  the  sun,  the  phases  of  the  moon, 
the  seasons  of  the  year.  So  elaborate  are 
the  schemes  of  marking  off  time  that  we 
make  use  of  long  periods  extending  fre- 
quently beyond  the  life  time  of  any  one 
person.     In   this  Avay  wc  know  collectively 


The  Framework  of  Perception:  Time 


243 


a  great  deal  about  spans  of  time  which  no 
one  can  ever  apprehend  directly.  This 
kind  of  time  is  important  for  the  sociolo- 
gists or  anthropologists,  but  it  is  not  part 
of  our  present  problem. 

Within  the  range  of  time  which  we  ap- 
prehend directly  a  second  distinction  is 
important.  In  this  case  we  distinguish  be- 
tween short  intervals  of  time  which  we 
perceive  directly  as  they  pass,  belonging  in 
a  way  to  the  'present,'  and  longer  inter- 
vals of  time  where  we  judge  that  so  much 
time  has  elapsed  since  something  hap- 
pened. You  may  be  able  to  judge  how 
long  it  has  been  since  you  began  to  read 
this  section,  or  how  long  ago  it  was  that 
you  came  into  the  room,  without  your 
having  been  aware  continuously  in  either 
case  that  time  was  passing.  To  make  a 
judgment  of  elapsed  time,  you  have  to  re- 
call specific  memories. 

Let  us  consider  the  simplest  case.  How 
do  we  know  that  time  passes  at  all?  What 
is  there  about  our  present  experience 
which  makes  it  part  of  the  stream  of  con- 
sciousness, anchored  on  the  one  side  in  the 
past  and  on  the  other  side  in  the  future? 
Do  we  have  some  kind  of  a  time  sense 
which,  acting  by  itself,  tells  us  of  the  pas- 
sage of  time?  Psychologists  agree  that  the 
answer  to  this  last  question  is  pretty  ob- 
viously no.  Time  cannot  be  appreciated 
directly,  nakedly,  as  such;  it  can  only  be 
known  through  some  process  which  goes  on 
in  time.  For  the  physicist  such  a  process 
may  be  the  motion  of  a  pendulum  or  the 
rotation  of  the  earth.  For  the  psychologist 
the  processes  whicli  give  us  our  impression 
of  time  are  those  which  underlie  the  per- 
ception of  what  William  James  called  "the 
specious  present."  We  seem  to  sit  perched 
on  a  sort  of  saddleback  of  time  with  a  cer- 
tain length  of  its  own.  The  present,  as 
we   experience   it,   is   a   very  small   bit   of 


duiation  bciuccrj  llu;  past  and  tlie  future, 
the  bit  whidi  can  be  spanned  in  any  one 
instant.  A  phrase  of  a  melody  is  somehow 
a  unitary  thing,  spread  out  in  time  and  yet 
sensed  in  one  instant.  By  trying  to  hold 
the  notes  of  the  melody  or  the  ticks  of  a 
watch  clearly  in  mind,  it  is  possible  to  ev 
timate  how  long  is  this  directly  perceived 
duration.  Normally  it  is  not  more  than 
(me  or  two  seconds.  Certain  observers  have 
claimed  that  it  may  stretch  out  to  eight  ot 
even  twelve  seconds.  On  what  does  this 
durable  present  depend? 

(1)  First,  we  should  note  that  each  ex- 
perience we  have  persists  for  a  very  brief 
time.  Cut  off  an  experience  suddenly  bv 
removing  its  stimulus  and  it  seems  to  glow 
for  a  moment  like  the  tail  of  a  comet.  It 
is  as  if  the  processes  underlying  conscious- 
ness have  a  certain  inertia  which  they  have 
to  expend  before  they  can  return  to  quies- 
cence. Our  consciousness  is  somehow  like 
the  scene  from  the  back  of  a  moving  train. 
Objects  flash  into  view  and  then  gradually 
fade  into  the  distance.  Sometimes  this 
persistence  is  called  memory  or,  more  par- 
ticularly, the  primary  memory  image,  but 
in  general  it  seems  better  to  speak  simplv 
of  the  persistence  of  consciousness. 

(2)  The  flow  of  experience  must  be 
marked  off  by  distinct  events.  Somediing 
must  flash  by.  If  what  we  experienced 
in  one  moment  were  just  exactly  like  A\hat 
we  experienced  the  moment  before,  we 
should  not  be  able  to  distinguish  them,  to 
know  that  the  one  was  ne%\'.  the  other  hang- 
ing on  from  the  moment  before.  It  would 
be  as  if  our  train  were  moving  in  a  dense 
fog,  or  even  in  inky  blackness.  There 
would  be  nothing  to  tell  us  that  we  were 
moving,  that  time  was  passing.  An  event 
which  marks  off  time  is  necessarih'  a  change. 
Something  is  present  now  ^vhich  a  moment 
before  was  not  there,  or  something  is  gone 


244 


herception 


now  and  our  experience  of  it  is  fading 
away. 

Once  more  we  see  how  important  change 
is  to  perception.  As  a  matter  of  fact,  the 
perception  of  time  depends  so  fundamen- 
tally upon  the  perception  of  change  that 
in  many  specific  cases  they  amount  to  the 
same  thing. 

(3)  Many  of  the  changes  which  are  fun- 
tlamental  to  the  perception  of  time  are  in- 
ternal. The  important  background  of 
events  which  furnishes  the  framework  of 
time  consists  of  subtle  experiences  from  the 
body,  the  rhythms  of  pulse  and  breathing, 
occasionally  the  peristaltic  movement  of 
digestion,  the  flow  of  memories  and  images 
before  the  mind's  eye.  Insomnia  would  be 
no  trial  at  all  were  it  not  for  the  insistent 
flow  of  these  internal  experiences  which 
assail  us  when  sleep  will  not  come.  They 
form  the  ground  against  which  the  events 
of  the  external  world  appear  as  clear  figures. 

Experience  is  a  continuing,  unbroken 
process.  The  experience  of  each  moment 
belongs  with  that  of  the  moment  before. 
One  flows  smoothly  and  without  interrup- 
tion into  the  next.  At  the  same  time  ex- 
perience is  constantly  changing.  Against 
a  uniform  background  of  internal  pulsa- 
tions and  muscular  strain,  constant  light  or 
steady  noise,  one  change  after  another 
erupts  into  our  field  of  attention.  Each 
momentary  event  appears,  persists  for  a 
moment  and  then  fades  away.  Fitted  be- 
tween other  events  fore  and  aft,  it  belongs 
to  the  present;  it  is  neither  imagined  nor 
recalled. 

The  present  includes  everything  of  which 
we  are  aware  just  now.  Some  of  these  ex- 
periences, which  have  persisted,  really  repre- 
sent the  recent  past.  And  yet  they  do  not 
seem  old,  for  they  have  not  yet  passed  the 
threshold  into  the  past.  We  experience 
them  as  being  here  noic  because  we  cannot 


clearly  label  them  as  belonging  either  to 
the  future  or  to  the  past.  To  sense  time 
fully,  therefore,  requires  that  we  be  able 
to  discriminate  between  experiences  that 
belong  to  the  present  and  those  that  be- 
long to  the  past. 

It  would  be  a  mistake  to  think  of  the 
durable  present  as  a  problem  peculiar  to 
man's  conscious  experience.  There  are 
aspects  of  the  behavior  of  animals  which 
raise  much  the  same  problem.  We  shall 
have  more  to  say  later  about  certain  time- 
telling  rhythms  which  occur  in  animal  ac- 
tivities. In  addition  to  these  rhythms,  the 
simplest,  free-swimming  organisms  possess 
a  very  elementary  kind  of  memory,  a  mem- 
ory in  the  sense  that  the  animal  'keeps  in 
mind'  what  happens  from  one  moment  to 
the  next.  The  best  example  is  the  collec- 
tion of  bacteria  in  a  ring  about  an  oxygen 
bubble.  They  are  exhibiting  what  Jen- 
nings called  trial  behavior.  Imagine  a  bac- 
terium swimming  about  in  a  body  of  water 
which  is  short  of  oxygen.  It  comes  to  the 
favored  zone  near  the  oxygen  and  passes 
readily  from  the  poorer  area  into  the  better 
one.  Later  it  starts  to  cross  tlie  boundary 
in  the  opposite  direction.  Once  it  touches 
the  unfavored  area,  its  forward  motion 
stops  and  it  turns  back  into  the  better 
area.  The  bacterium  has  made,  in  its 
simplest  form,  a  kind  of  successive  com- 
parison. It  is  just  this  kind  of  reaction 
to  change  which  is  the  essential  first  step 
in  the  perception  of  the  passing  of  time. 

This  is  the  place  to  interrupt  the  argu- 
ment with  a  brief  remark.  It  must  now  be 
clear  that  the  psychological  problem  of 
the  present  is  very  different  from  the 
philosophical  one.  Psychologically,  the 
present  is  a  part  of  a  substantial  con- 
tinuing process,  whether  it  is  regarded  as 
our  experience  or  as  some  activity  in  our 
brain.      The    psychological    present   is    the 


Temporal  Patterns 


245 


segment  ol  this  process  which,  at  any  mo- 
ment, can  influence  what  we  do.  It  is  a 
good  solid  chunk  of  time  even  it  it  lasts 
only  a  second  or  two.  Philosophically,  on 
the  other  hand,  the  jjresent  is  but  an  in- 
finitely small  particle  of  time  which  has  no 
duration.  It  is  only  the  boundary  between 
the  future  and  the  past,  like  the  edge  of  a 
sharp  shadow  through  which  events  pass. 
There  is  no  movement,  no  flow,  no  exist- 
ence. 

TEMPORAL    PATTERNS 

Time  not  only  passes;  it  is  also  patterned 
or  structured.  It  is  divided  and  subdivided 
by  a  sequence  of  events  which  follow  in 
varied  order.  Let  us  see  what  happens  as 
the  rate  of  these  events  changes.  Imagine 
that  you  are  listening  to  a  series  of  short 
sounds  or  watching  a  flashing  light.  At  a 
high  rate  of  speed  the  sounds  or  flashes 
merge  into  each  other  so  that  the  sensa- 
tion which  results  is  smooth  and  continu- 
ous. Slow  down  the  rate  of  interruption 
and  a  point  is  reached  at  which  the  tone 
begins  to  waver  or  roughen,  the  light  to 
flicker.  This  critical  rate  may  be  called  the 
threshold  of  discontinuity  (or  the  threshold 
of  continuity,  depending  upon  whether 
you  are  speeding  up  or  slowing  down). 
The  threshold  will  be  somewhat  different 
for  light  and  for  sound  or  for  widely  dif- 
ferent conditions  of  stimulation.  As  a 
rough  estimate,  however,  it  can  be  said 
that  sounds  must  be  separated  by  at  least 
one-twentieth  of  a  second  if  they  are  to  be 
heard  as  two,  or  that  a  light  must  flash  less 
than  twenty  times  per  second  if  it  is  to 
appear  to  flicker. 

A  series  of  clicks  or  flashes  at  a  rate 
slower  than  the  threshold  of  discontinuity 
will  seem  nevertheless  to  fill  up  the  time 
as  it  passes.     We  see  simply  a   flickering 


liglit,  hear  a  'beating'  tone  or  a  rough 
noise.  There  is  no  perceptible  pause  \x:- 
tween  the  ticks  of  a  watch  or  the  explf>- 
sions  of  an  idling  auioinobile  engine.  The 
sounds  or  flashes  are  bound  together  into  a 
firm  series. 

Let  the  time  between  sounds  become 
long  enough,  however,  and  we  begin  to 
hear  pauses.  When  more  than  one-hall 
second  comes  between  two  clicks,  we  hear 
a  click-pause-click,  in  which  the  pause  has 
a  sensible  duration.  Longer  and  longer 
intervals  will  seem  to  last  quite  a  while 
up  to  the  point  where  the  beginning  of  the 
interval  has  slipped  out  of  mind  and  can 
be  recalled  only  from  memory.  At  this 
point,  judgment  of  duration  depends  no 
longer  on  a  perception  but  rather  on  all 
the  memories  which  fill  up  the  gap  be- 
tween the  starting  point  and  the  end. 

Short  Intervals 

The  accuracy  with  which  short  intervals 
of  time  can  be  estimated  has  been  the  sub- 
ject of  a  great  many  experiments.  It  has 
been  found  that  intervals  of  less  than  a 
second  are  commonly  overestimated,  and 
intervals  of  more  than  a  second  tend  to  be 
underestimated.  Between  the  two  lies  an 
indifference  point,  an  interval  which  is 
judged  correctly  since  it  is  neither  over- 
nor  underestimated. 

Our  estimates  of  time  are  much  affected 
by  the  way  the  interval  is  filled.  If  two 
clicks  mark  off  the  period  of  silence,  the 
interval  is  called  unfilled.  On  the  other 
hand,  a  series  of  five  or  ten  clicks  might 
be  presented  in  which  the  first  and  last 
clicks  would  define  the  inter\al  to  be 
judged.  This  would  be  a  filled  intenal. 
Filled  intervals  are  perceived  as  longer  tlian 
unfilled  inter\als  of  the  same  objective 
length. 

More  disturbing  to  the  judgment  of  time 


246 


Perception 


than  the  number  of  events  filling  an  inter- 
\al  is  the  meaning  of  the  material  for  the 
listener.  The  duration  of  a  word,  for  in- 
stance, is  judged  to  be  shorter  than  a  noise 
Avhich  actually  lasts  the  same  time,  and 
meaningful  sentences  seem  to  be  shorter 
than  an  equivalent  series  of  nonsense  syl- 
lables. Other  factors  which  increase  the 
interest  of  the  listener  in  what  is  going  on 
have  much  the  same  effect.  On  the  other 
hand,  an  interval  with  a  striking  beginning 
and  end  will  be  perceived  as  longer  than 
one  with  indifferent  boundaries.  Either 
the  sharp  intense  stimuli  call  particular  at- 
tention to  the  passing  of  time,  or  they  add 
a  short  bit  of  duration  on  either  end  of  the 
interval. 

Rhythm 

Rhythms  are  patterns  in  time  which  are 
marked  off  by  regular  beats  with  varying 
emphasis.  Simple  rhythms  have  every  sec- 
ond, third  or  fourth  beat  accented.  But 
the  accent  alone  is  only  part  of  the  pattern. 
Subjectively  the  important  thing  is  the  way 
the  beats  are  grouped.  Thus,  the  count  of 
one,  two,  three  is  different  in  grouping 
from  a  coimt  of  one,  two,  three,  or  one, 
Ixuo,  three;  and  in  poetry  iambic  meter 
differs  from  trochaic  meter,  depending  upon 
the  place  of  the  stress  in  the  foot.  Rhythm 
depends,  then,  on  two  basic  factors,  group- 
ing of  beats  into  measures  or  feet  and  the 
accenting  of  one  or  more  of  the  beats  in 
each  measure.  Rhythms  become  more 
complicated  when  (1)  the  time  intervals 
between  beats  are  no  longer  equal  and 
regular  and  (2)  when  more  than  one  level 
of  accentuation  is  introduced,  giving  rise 
to  subgroups  within  the  measure. 

In  the  absence  of  any  accentuation  in 
the  objective  rhythms,  the  person  listening 
will  nearly  always  supply  his  own.  Try  to 
listen    to    a    series    of   absolutely    uniform 


clicks  and  you  will  find  yourself  involuntar- 
ily grouping  them  into  twos,  threes,  fours, 
or  even  groups  of  six  or  eight  beats.  The 
commonest  subjective  groupings  are  of  two 
or  four  beats;  if  a  larger  group  of  six  or 
eight  beats  is  heard,  it  is  almost  sure  to  be 
subdivided  into  two  sets  of  three  or  two  sets 
of  four. 

For  the  perception  of  rhythm  the  rate  at 
which  the  beats  follow  each  other  must 
be  neither  too  slow  nor  too  fast.  The 
possible  range  is  from  about  two-thirds 
beats  per  second  up  to  8  beats  per  second. 
The  most  pleasing  rates  usually  fall  be- 
tween 70  and  90  beats  per  minute  or 
roughly  1.2  to  1.5  beats  per  second. 

Rhythm  plays  a  great  part,  of  course,  in 
artistic  expression.  All  the  basic  forms  of 
music,  dancing  and  poetry  are  rhythmic. 
Curiously  enough,  a  comparable  form  of 
art  which  makes  important  use  of  visual 
rhythms  has  never  developed.  Perhaps 
this  is  a  result  of  technical  difficulties  in 
producing  rhythmic  visual  patterns;  more 
probably  it  reflects  rather  a  fundamental 
difference  between  the  sense  modalities. 
Rhythm  appeals  to  the  ear  and  to  the  sense 
of  bodily  movement,  the  kinesthetic  sense. 
These  are  the  senses  which  offer  us  sharply 
defined  events  against  a  continuing  back- 
ground. Visual  events  are  not  nearly  so 
abrupt  and  discrete  as  those  of  hearing; 
visual  objects  are,  after  all,  substantial  and 
do  not  suddenly  appear  and  disappear. 
Sounds,  on  the  other  hand,  start  and  stop 
imder  circumstances  where  the  seen  ob- 
ject remains  steadily  in  view.  Furthermore, 
sound,  or  silence,  furnishes  us  with  a  con- 
tinuous background  whether  we  care  to 
listen  or  not.  Vision  can  be  shut  off  by 
our  own  fiat;  we  shut  our  eyes  or  turn  our 
heads  away.  Kinesthesis  resembles  hear- 
ing in  these  particulars.     Perhaps  it  is  not 


Orientation  in  Time 


247 


so  strange  that  rhythm  belongs  pcciiliaily 
to  sounds  and  to  bodily  movement. 

ORI  ENTATION    IN    TIME 

Our  ability  to  tell  time,  to  wake  at  a 
particular  hour,  to  judge  periods  several 
hours  in  length  without  recourse  to  a  time- 
piece, presents  quite  a  different  problem 
from  the  one  we  have  just  been  discussing. 
This  ability  has  been  tested  in  an  experi- 
ment in  which  a  subject  spent  nearly  tour 
days  in  complete  isolation  in  a  soundproof 
room.  The  subject  was  provided  with  a 
bed,  supplies  of  food  and  water,  paper, 
pencil  and  a  telephone  with  which  he 
could  conmiunicate  with  the  experimenter 
at  will.  At  irregular  intervals  the  subject 
reported  what  time  he  thought  it  was  then. 
Between  reports  he  ate  meals,  made  notes, 
slept  and  amused  himself  as  well  as  he 
could  under  such  restricted  conditions. 
Within  the  first  day  the  subject's  personal 
'clock'  had  gained  more  than  four  hours. 
Then  it  began  to  lose  and  at  the  end  of  the 
experiment  his  guess  about  the  time  was 
less  than  forty  minutes  in  error,  closer  to 
the  correct  time  than  it  had  been  since  the 
start  of  the  experiment. 

How  this  man  was  able  to  maintain  his 
orientation  in  time  will  be  better  under- 
stood if  we  digress  for  a  moment  to  see 
what  is  known  of  some  of  the  important 
time-telling  rhythms  in  animal  behavior. 
The  longest,  and  yet  highly  precise,  rhythms 
are  those  connected  with  the  migration  of 
birds  and  fishes.  Year  after  year  we  see 
the  ducks  and  geese  flying  north  in  the 
spring  and  south  again  in  the  autumn. 
Each  flock  sets  off  on  its  flight  at  almost 
precisely  the  same  date  each  year.  Bird 
lovers  are  accustomed  to  finding  individual 
species  of  warblers  arriving  each  spring 
within   a    few   days   of  a   customary   date. 


How  are  these  migrations  controlled;'  Our 
best  guess  at  the  present  time  is  that  the 
length  of  the  day  is  the  principal  factor. 
'I'emperature  and  food  supply  appear  to 
be  secondary  factors.  Changes  in  the  total 
light  are  known  to  produce  fivefold  to  ten- 
fold changes  in  the  size  of  the  pituitary 
gland,  which  in  turn  secretes  more  or  less 
of  several  hormones.  These  control  many 
other  organs  of  the  body.  Nature  appar- 
ently uses  this  mechanism  to  start  many 
species  of  birds  north  to  their  breeding 
grounds  in  the  spring. 

Many  other  long-term  rhythms  are  known 
in  other  animals.  Arctic  animals  such  as 
the  weasel,  hare  and  fox  change  the  color 
of  their  coats  with  the  season.  Certain 
marine  worms  swarm  with  the  full  moon. 
Army  ants  alternate  between  a  nomadic 
and  sedentary  life.  In  all  these  cases  we 
find  evidence  of  the  same  thing,  emiron- 
mental  control  of  a  particular  physiological 
mechanism.  The  animal  is  sensitized  so 
that  he  can  tell  time  from  nature's  clock. 

By  far  the  most  general  rhythm  in  ani- 
mal behavior  is  the  diurnal  one,  the  daily 
pattern  of  sleep  and  activity.  Animals 
vary,  of  course,  as  their  peak  activity  comes 
during  the  day  or  night.  But  their  hunt- 
ing and  eating,  their  hiding  and  sleep,  even 
their  sex  life  follow  a  daily  cycle  that  is 
governed  by  the  sun.  Offhand  it  would 
look  as  if  this  diurnal  rhythm,  like  the 
longer  ones,  is  controlled  by  light,  tempera- 
ture, sound  or  some  other  environmental 
stimulus.  In  some  measure  this  is  true. 
Female  rats,  for  instance,  always  come  into 
heat  at  night.  If  the  lighting  cycle  is 
changed  so  that  it  is  dark  during  the  dav 
and  light  at  night,  the  rat's  estrus  peak 
comes  in  the  dark  during  the  day.  Its  oc- 
currence is  obviouslv  controlled  bv  the 
cycle  of  light  ancf  dark.  But  there  is  this 
very  important  difference.     A  blind  rat.  or 


248 


Perception 


one  kept  continuously  in  the  light,  shows 
little  or  no  disturbance  of  the  normal  four- 
day  estrus  c)cle.  In  other  words,  the  light 
acts  only  to  s\  nchronize  the  already  rigidly 
established  rhythm  within  the  animal  with 
the  changes  in  the  environment. 

There  is  evidence  to  indicate  that  the 
diunial  rhythm  generally  is  something  of 
this  kind.  Normally  sleep  and  activity  are 
synchronized  with  the  environment,  but  in 
the  absence  of  environmental  changes  the 
rhythm  will  maintain  itself  with  consider- 
able precision.  A  group  of  rats  were  placed 
in  a  room  with  a  28-hour  'day';  lighting, 
watering  and  feeding  were  all  geared  to  the 
longer  day.  It  might  have  been  thought 
that  they  would  adapt  to  this  new  day,  but 
apparently  they  did  not,  for  in  each  28-hour 
cycle  they  showed  a  peak  of  acti^'ity  just 
24  hours  after  the  time  they  had  been  pre- 
viously fed.  In  these  diurnal  and  estrus 
rhythms,  then,  we  are  dealing  with  a  self- 
maintaining  physiological  rhythm. 

The  behavior  of  men  does  not  show^  such 
neat  control  as  the  behavior  of  rats.  Rem- 
nants of  both  the  types  of  mechanisms 
which  we  have  discussed  above  probably 
exist.  It  is  not  hard  to  believe  that  the 
restlessness  of  spring  fever  has  its  roots  in 
surplus  hormones  brought  forth  at  that 
season  of  the  year.  Physiologically 
rhythms  such  as  estrus  are  quite  clear-cut. 
Diurnal  rhythms  are  harder  to  discover 
because  they  are  so  strongly  reinforced  by 
social  conventions  as  to  cast  doubt  on  their 
underlying  physiological  nature.  Trav- 
elers report,  for  instance,  that  Eskimo  life 
north  of  the  Arctic  Circle  continues  around 
the  clock  during  the  month-long  summer 
day.  Nevertheless,  we  do  get  clues  from 
our  bodies  when  we  make  temporal  judg- 
ments. Four  psychologists  had  their  alarm 
clocks  set  at  odd  hours  between  12:15  and 


4:45  A.M.  When  awakened,  they  guessed 
the  hour.  They  discovered  that  depth  of 
sleep  was  one  of  their  most  obvious  clues, 
followed  closely  by  the  dark  brown  taste 
of  indigestion  and  the  necessity  to  urinate. 
These  clues  do  not  belong  to  the  basic 
diurnal  rhythm,  and  a  more  clever  experi- 
ment will  be  required  to  settle  whether  our 
sleeping  once  a  day  is  a  social  convention 
or  sound  physiology. 

Two  other  important  mechanisms  can 
be  recognized  in  our  time  telling.  The  first 
of  them  is  the  conditioning,  often  uncon- 
scious, of  particular  behavior  to  some  clue 
in  the  environment.  Some  of  the  best  ex- 
amples can  be  found  in  individuals  who 
wake  up  in  the  morning  "like  clockwork." 
A  careful  examination  nearly  always  shows 
that  there  is  some  particular  happening  to 
which  each  of  these  people  responds.  For 
some  people  the  clue  is  the  sunlight,  for 
others  it  is  the  sounds  of  traffic  or  the  ar- 
rival of  the  milkman  or  the  early  departiue 
of  a  neighbor  for  work.  Similar  condition- 
ing establishes  our  hunger  at  mealtimes 
or  our  drowsiness  in  the  late  evening. 
Daily  habits  of  long  standing  apparently 
can  go  quite  far  in  regulating  our  basic 
bodily  mechanisms.  These  habits  repre- 
sent a  sort  of  involuntary  keeping  of  time. 
Intentional  estimates  of  time  would  be  Avell 
anchored  by  this  habitual  framework. 

In  addition  to  this  subtle  sort  of  con- 
ditioning, it  is  possible  for  us  to  make  quite 
explicit  use  of  memories  in  gauging  the 
amount  of  time  which  has  passed.  If  you 
think  of  how  long  it  has  been  since  you 
arrived  home,  you  are  able  to  recall  that 
you  went  to  your  room  and  washed  up  for 
supper,  that  you  talked  briefly  to  your 
roommate,  that  you  read  a  letter  waiting 
for  you  when  you  arrived,  that  you  have 
now   danced   over  certain   features   of   the 


Orientation  in  Time 


249 


evening  paper.  Some  memories  may  af- 
ford you  quite  exact  estimates,  such  as  the 
known  time  of  your  accustomed  walk  from 
school  to  home.  In  other  memories  the 
clue  may  be  the  sheer  number  and  clarity 
of  them  which  crowd  into  your  mind.  A 
morning  in  a  new  and  strange  place  seems 
very  long  in  retrospect  because  of  the  many 
novel  experiences  it  contained,  or,  again, 
your  estimate  may  be  influenced  by  the 
restlessness  and  boredom  which  you  recall 
or  by  the  absence  of  memories  of  moments 
when  time  was  heavy  on  your  hands.  What- 
ever may  be  the  whole  pattern  of  these 
explicit  memories,  it  is  evident  that  they 
form  a  most  substantial  clue  against  which 
we  all  can  check  our  personal  clocks. 

To  sum  up,  we  can  say  that  orientation 
in  time  depends  on  four  factors:  (1)  exter- 
nally controlled  physiological  rhythms,  (2) 
self-controlled  physiological  rhythms,  (3) 
habitual  acts  conditioned  to  environmental 
cues,  and  (4)  the  pattern  of  memories  which 
belong  to  the  interval  being  judged.  From 
all  these  factors  we  build  up  a  framework 
of  time  in  which  our  present  actions  are 
set.  External  events  and  our  own  actions 
have  special  meanings  for  us  as  they  fit 
into  this  framework.  Thus  we  come  finally 
to  have  a  kind  of  'time  perspective'  pointed 
both  toward  the  past  and  toward  the  future. 

REFERENCES 

1.  Boring,  E.  G.  The  physical  dimensions  of 
consciousness.  New  York:  Appleton-Century, 
1933.     Chap.  5. 


A  fairly  modern  view  of  mind-and-fxxly. 
This    chapter    deals    with     the    perception    o\ 

time. 

2.  Boring,  E.  G.  Sensation  and  perception  in  the 
history  of  experimental  psychology.  .New  York: 
Appleton-Century,  1942. 

Descrihcs  the  historical  setting  of  the  inoie 
important  current  problems  in  perception,  anrl 
in  vision  and  hearing  as  well. 

3.  Carr,  H.  A.  An  introduction  to  space  percep- 
tion.    New  York:  Longmans,  Green,  193.5. 

A  simple,  and  not  too  complete,  summary  of 
the  conventional  material  on  space  perception. 

4.  Harrower,  M.  The  psychologist  at  work.  New 
York:  Harper,  1937.     Chaps.  2  and  3. 

A  popular  account  of  how  a  Gestalt  (isychol- 
ogist  deals  with  a  few  of  the  facts  of  experi- 
ence and  their  relation  to  behavior. 

5.  James,  W.  Psychology:  briefer  course.  New 
York:  Holt,  1892.     Chaps.  17,  20  and  21. 

James'  discussion  of  space  and  time  and  of 
the  stream  of  consciousness;  it  has  been  modi- 
fied by  many  new  facts,  but  the  breadth  of  his 
account  is  still  without  peer. 

6.  Kohler,  AV.  Gestalt  psychology.  (2nd  ed.) 
New  York:  Liveright,  1947.     Chaps.  4.  5  and  6. 

Three  chapters  on  Gestalt  principles  applied 
to  some  problems  of  perception.  Still  the  best 
introduction   to   this  school. 

7.  Koffka,  K.  The  principles  of  Gestalt  psychol- 
ogy. New  Y'ork:  Harcourt,  Brace,  1935.  Chaps. 
3,  4,  5  and  6. 

Contains  a  comprehensive  account  of  percep- 
tion written  from  the  Gestalt  point  of  view. 
Difficult  and  erudite. 

8.  Woodworth,  R.  S.  Experimental  psychology. 
New  York:  Holt,  1938.     Chaps.  24  and  25. 

Chapters  on  form,  color,  space  and  attention. 
Factual  and  readable,  the  best  single  advanced 
text  on  experimental  psychology. 


CHAPTER 


n 


Sensation  and  Psychological 
Measurement 


THE  chief  business  of  the  living  organism 
is  adaptation  to  its  ever-changing  envi- 
ronment. The  protozoan,  swimming  along 
near  the  muddy  floor  of  a  pond,  turns  aside 
from  the  sharp  cold  of  a  fresh  current  and 
moves  toward  a  safer  region.  Man's  prob- 
lems and  man's  responses  may  be  more  com- 
plicated than  the  protozoan's,  yet  man, 
crossing  the  street  in  traffic,  dodging  taxi- 
cabs  in  the  five-o'clock  rush  hour,  solves  sim- 
ilar problems  of  avoidance  in  similar  ways. 
Both  cases  involve  perception:  the  proto- 
zoan perceives  cold  and  the  man  perceives 
the  oncoming  rush  of  steel  and  glass  which 
is  the  taxicab.  All  organisms,  from  proto- 
zoan to  man,  preserve  themselves  in  a  care- 
less universe  by  a  knowledge  of  the  external 
world  which  comes  to  them  through  their 
sensory  mechanisms. 

The  preceding  chapter  has  dealt  with 
problems  of  perception.  In  perception  the 
organism  does  all  it  can  to  get  the  best  pos- 
sible information  about  the  external  world. 
A  piece  of  coal  in  the  sunshine  may  reflect 
more  light  than  a  piece  of  notepaper  in  the 
shade:  yet  we  see  the  coal  as  black  and  the 
paper  as  white.  The  constancy  phenome- 
non has  come  into  play  here;  it  helps  us 
to  recognize  these  and  other  objects  in  a 

This  rhapter  was  prepared  by  S. 


way  which  has  most  meaning  for  us.  Sc 
too  the  organism  gets  the  third  visual  di- 
mension of  space;  it  sees  that  a  mountain 
oi-  a  trolley  car  has  not  only  height  and 
width  but  also  solidity.  As  it  'interprets' 
the  data  from  its  two  eyes,  so  also  the  or- 
ganism 'interprets'  the  data  from  its  two 
ears,  not  merely  hearing  a  sound— the  horn 
of  the  taxicab— but  knowing  also  the  direc- 
tion from  which  it  came.  In  short,  in  one 
way  or  another  the  organism  musters  all  its 
resources  to  the  end  that  it  may  get  the 
most  valuable  information  about  its  en- 
vironment; and  this  process  we  call  per- 
ception. 

Sensation  Is  the  Core  of  Perception 

The  way  from  the  external  world  to  the 
brain  is  via  the  sense  organs,  and  these  re- 
markable organs,  responding  to  light, 
sound,  heat,  cold,  pressure,  touch,  etc.,  are 
the  windows  through  which  we  look  out  at 
the  world  about  us.  The  sense  organs 
start  the  messages  along  the  nerves,  the 
high^vays  to  the  brain.  "W^hen  these  mes- 
sages merge  at  the  higher  centers  of  the 
nervous  system,  when  they  organize  them- 
selves and  modify  one  another  through  in- 
teractions and  associations,  we  call  the  re 

Smith  Stevens  of  Harvard  University. 
250 


Stimulus  and  Atiribufes 


251 


suit  perception,  iiut  the  bare  messages 
themselves,  isolated  and  apart  from  their 
mutual  influences,  we  call  sensations. 

We  get  at  sensations  by  analysis,  by  pay- 
ing attention  to  certain  aspects  of  our  per- 
ceptions. It  is  much  like  the  artist  paint- 
ing his  landscape.  Where  the  casual  ob- 
server sees  a  valley  partly  shadowed  by  a 
rocky  hill,  the  artist  sees  a  patch  of  purple 
jutting  into  a  field  of  green  and  speckled 
by  reddish  brown  dots.  By  selective  at- 
tention he  analyzes  the  organized  scene 
into  patches  of  color  and  he  translates  these 
sensations  into  pigments  on  canvas. 

The  student  of  sensation  goes  farther. 
He  learns  to  attend  not  only  to  color  as 
such  but  also  to  its  several  modes  of  varia- 
tion, to  its  redness  and  whiteness  and  gray- 
ness.  And  the  object  of  his  analysis  is  an 
understanding  of  the  behavior  of  sensory 
processes:  How  do  sensations  arise?  what 
causes  them  to  change?  how  many  aspects 
of  them  can  be  separately  distinguished  and 
how  can  the  aspects  be  measured?  what 
takes  place  in  the  sense  organ  and  in  the 
sensory  nerves?  and  how  do  these  events 
depend  upon  the  physical,  chemical  or  me- 
chanical happenings  in  the  world  outside? 
The  answers  to  these  questions  are  the  laws 
of  sensation,  laws  that  are  based  upon  care- 
ful experimental  measurements. 

STIMULUS    AND    ATTRIBUTES 

In  order  to  understand  the  laws  of  sen- 
sation we  must  first  know  what  is  meant  by 
a  stimulus  and  by  attributes  of  sensation 
such  as  quality  and  intensity. 

Stimulus 

A  stimulus  is  any  change  in  external 
energy  that  activates  a  sense  organ  and  its 
receptors.  It  is  a  stimulus  only  when  it 
stimulates.     Light  is  not  a  stimulus   to  a 


totally  blind  person.  1  he  radio  waves  tliai 
fill  the  air  are  not  a  direct  stimulus  to  any 
organism  that  we  know  of.  Many  phe- 
nomena of  nature  affect  no  sense  organs, 
and  these  phenomena  come  to  our  atten- 
tion only  indirectly  by  way  of  their  effects 
or  by  way  of  the  elaborate  inferences  of 
science.  The  important  phenomena  that 
can  be  classed  as  stimuli  are  mechanical, 
thermal,  acoustic,  chemical  and  photic. 

Man  himself  reacts  to  many  kinds  of 
mechanical  stimulation.  He  has  the  tac- 
tual sense  of  his  skin,  by  which  he  appre- 
ciates the  presence,  size  and  shape  of  the 
objects  with  which  he  comes  in  contact. 
He  can  feel  pain,  which  warns  him  of  vio- 
lent or  dangerous  contact.  He  perceives 
his  own  posture  by  means  of  the  proprio- 
ceptive organs  that  lie  in  his  muscles  and 
joints.  By  their  use  and  by  vision  he  main- 
tains his  erect  position.  He  perceives  cer- 
tain contractions  of  his  stomach  and  calK 
them  hunger.  He  perceives  dryness  in  his 
mouth  and  throat  and  calls  it  thirst.  These 
instances  are  samples  of  the  wide  variety 
of  mechanical  events  which  can  act  as 
stimuli  in  man. 

Therynal  stimulation  is  also  effective  for 
man.  He  must  keep  the  temperature  of  his 
body  constant.  If  it  varies  a  little  he  mav 
be  ill;  if  it  varies  much  he  may  die.  Al- 
though his  body  is  equipped  with  a  re- 
markable system  for  automatic  thermostatic 
control,  he  needs  also  to  help  out  by  con- 
scious adaptive  behavior.  The  thermal 
sense  tells  him  when  to  put  on  heavier  or 
lighter  clothes,  when  to  start  the  electric 
fan,  when  to  turn  on  the  radiator. 

Acoustic  stimulation  affects  most  animals 
that  live  in  the  air  and  some  that  live  in 
water.  Hearing,  which  shares  with  vision 
the  important  function  of  giving  informa- 
tion about  distant  stimuli,  is  a  verv  impor- 
tant and  highly  developed  sense.     Persons 


252 


Sensation  and  Psychological  Measurement 


suddenly  made  deaf,  and  depri\ed  of  speech 
and  music,  seem  to  suffer  even  more  from 
their  deficiency  than  the  blind.  These  peo- 
ple say  that  they  live  in  a  "dead  world." 
Sound,  more  than  anything  else,  signifies 
that  the  world  is  alive  and  moving. 

Taste  and  smell  are  chemical  senses,  the 
direct  descendants  of  the  chemical  sense 
of  fishes.  Taste  is  a  liquid  sense;  it  is 
stimulated  only  by  substances  in  solution. 
Smell  is  an  air  sense;  it  is  activated  by  small 
particles  of  substance  diffused  in  the  air. 
Although  a  highly  developed  sense,  smell 
is  little  used  by  man,  who,  with  his  erect 
posture,  keeps  his  nose  away  from  the 
ground  where  most  of  the  smells  lie.  The 
dog,  nose  to  ground,  finds  how  extremely 
informative  olfactory  stimuli  can  be. 

Vision  is  the  photic  sense,  and  light  is 
man's  most  important  stimulus,  even 
though  the  other  senses  may,  in  the  blind, 
become  remarkably  effective  substitutes  for 
vision.  ^V^hereas  the  lower  animals  sense 
only  the  intensity  of  light,  man  and  some 
of  the  higher  vertebrates  can  discriminate 
its  wave  length  as  well;  that  is  to  say,  they 
can  see  hues  as  well  as  blacks,  grays  and 
whites.  Probably  this  sensitivity  to  differ- 
ence in  the  wave  length  of  light  is  one  of 
man's  most  recent  sensory  acquisitions,  for 
the  development  of  color  vision  is  still  in- 
complete in  that  an  appreciable  portion  of 
the  population  is  color  blind.  Most  ani- 
mals are  also  color  blind,  responding  to 
differences  in  the  energy,  but  not  differences 
in  the  wave  length,  of  light. 

Attributes  of  Sensation 

Since  there  are  many  ways  in  which  a 
sensation  can  change,  an  observer,  experi- 
encing a  sensation,  describes  it  completely 
only  when  he  has  specified  its  value  with 
respect    to    every    possible    dimension    of 


change.  These  possible  dimensions  consti- 
tute the  attributes  of  sensation. 

Suppose  a  congenitally  blind  man  were 
suddenly  given  perfect  vision  and  shown  a 
red  square.  This  single  experience  would 
not  teach  him  anything  about  the  attributes 
of  visual  sensation,  but  we  could  soon  show 
him  what  some  of  them  are.  First,  we  could 
change  the  square  in  quality  by  altering 
its  hue  toward  orange  or  purple  or  gray, 
telling  the  man  that  this  sort  of  change 
is  a  change  in  the  qualitative  attribute  of 
color.  Then  we  could  change  the  square 
in  size  to  teach  him  about  the  attribute  of 
extension.  To  change  the  time  of  its  ex- 
posure would  be  to  exhibit  duration  to 
him.  Some  psychologists  think  that  hues 
also  have  an  attribute  of  intensity,  which 
they  call  brightness.  A  difficulty  arises 
here,  however,  because  brightness  is  white- 
ness, and  white  is  a  color  quality.  At  any 
rate  all  the  other  sensations  have  an  in- 
tensitive  attribute.  Tones  can  be  loud, 
smells  and  tastes  strong,  pressures  and  pains 
intense. 

It  is  conventional  to  classify  the  sensory 
attributes  under  four  main  heads:  quality, 
intensity,  extension  and  duration.  There 
can  be,  however,  many  more  than  four 
sensory  attributes,  for  there  are  just  as 
many  attributes  as  there  are  possible  modes 
of  variation  of  sensation.  In  his  course  in 
psychology  the  college  student  often  dis- 
covers attributes  that  are  new  to  him,  for 
most  people  do  not  know,  until  they  are 
taught,  that  colors  vary  in  three  dimensions 
in  a  system  that  is  represented  by  a  solid 
figure  and  that  tones  change  in  volume 
and  density  as  well  as  in  pitch  and  loud- 
ness. Perhaps  there  are  some  sensory  at- 
tributes which  the  psychologist  himself  has 
not  yet  discovered. 

The  problem  of  attributes  comes  up  for 
animals  as  well  as  persons.     For  instance. 


Attribufes  of  Sensaiion 


253 


size  is  ail  attribute  ol  visual  experiences. 
Can  a  rat  perceive  sizei'  Yes,  because  lie 
can  learn  to  choose,  for  a  reward,  the  larger 
of  two  circles.  Can  a  rat  perceive  shape 
as  such,  independently  of  all  the  other 
spatial  properties  of  visual  stimuli?  Prob- 
ably not.  Figure  98  shows  the  stimuli  of  an 
experiment  which  was  arranged  to  test 
the  capacity  of  human  and  animal  subjects 
to  perceive  triangularity  as  such.  The 
subject  was  first  trained  to  choose  the  tri- 
angle and  avoid  the  square  in  the  standard 
pair  of  stimuli,  S.  He  was  then  tested  to 
see  whether  he  would  choose  the  triangle 
instead  of  the  other  figure  in  each  of  the 
other  seven  pairs  of  stimuli,  A  to  G.  If  he 
chose  the  triangle  in  preference  to  the 
square  in  5  because  it  was  a  triangle,  he 
should  choose  the  triangle  instead  of  the 
circle  in  A  and  the  inverted  triangle  in  B; 
he  should  choose  the  triangle  instead  of  the 
rotated  square,  without  regard  to  the  ro- 
tation of  the  triangle,  in  C  to  F;  and  he 
should  prefer  the  dark  triangle  to  the  dark 
square  in  G.  Since  each  pair  of  figures  is 
equated  in  total  area  and  thus  in  total 
brightness,  and  since  the  triangle  was  shown 
as  often  on  the  right  as  on  the  left,  it  can 
be  argued  that  shape— not  brightness,  an- 
gular position  or  size— must  have  been  the 
basis  for  the  original  discrimination  in  S. 
The  general  problem  has  proved,  however, 
too  hard  for  the  rat.  A  chimpanzee  almost 
succeeded  in  it,  and  a  child  did  succeed. 
Thus  it  is  apparent  that  a  human  being  is 
able  to  analyze  a  perception  more  specifi- 
cally into  its  attributes  than  a  rat  or  even 
a  chimpanzee. 

It  is  important  to  realize  that  a  per- 
son has  to  learn  about  particular  attributes 
before  he  can  describe  experience  in  terms 
of  them.  People  learn  readily  enough  to 
distinguish    between    size    and    brightness, 


but  most  animals  do  not.  Color-blind  per- 
sons do  not  easily  discover  the  defects  in 
their  color  sense  because  they  are  not  espe- 
cially trained  to  analyze  their  color  experi- 
ences.    Instead  they  are  told  that  the  grass 


Iab 
|a« 

|A4 

H^ 

°AH 

FIGURE    gh.       DISCRIMIN.\TIO.N    OF    SHAPE 

The  subject  was  trained  to  choose  the  triangle  in 
pair  S.  Then  the  experiment  was  arranged  to  dis- 
cover whether  he  would  choose,  without  further 
training,  the  triangle  in  each  of  the  pairs  A  to  G. 
The  stimuli  were  large,  and  were  presented  with 
the  triangle  as  often  at  the  right  as  at  the  left.  A 
child  learned  to  discriminate  'pure  triangularity'  in 
this  way:  a  chimpanzee  almost,  hut  not  quite,  suc- 
ceeded; a  rat  failed.  [From  L.  W.  C.ellerman. 
/.  genet.  Psychol.,  1933,  42,   14.] 

is  gieen  and  tliat  the  rose  is  red,  although 
these  two  objects  may  be  to  them  the  same 
color.  And  faced  ^vith  die  task  of  making 
an  impossible  color  analysis,  thev  avoid 
giving  attention  to  color  attributes,  and 
rely,  when  they  can.  upon  their  knowledge 
of  the  nature  of  objects.     Xo  roses,   thev 


254 


Sensation  and  Psychological  Measurement 


remind  themselves,  are  green,  and  grass  is 
never  red. 

Quality 

All  the  senses  but  hearing  seem  to  be 
based  upon  a  few  unique  qualities,  which 
may  unite  in  fusions  to  give  other  secondary 
qualities. 

In  vision  the  seven  iniique  qualities  are 
red,  yellow,  green,  blue,  white,  gray  and 
black.  All  other  colors  occur  as  blends  of 
these  unique  colors.  (See  pp.  270-274.) 
In  smell  the  unique  qualities  are  fragrant, 
ethereal,  spicy,  resinous,  burned  and  putrid, 
and  a  huge  number  of  intermediates  that  fit 
in  among  these  six.  (See  p.  356.)  In  taste 
the  tmique  qualities  are  sweet,  saline,  sour 
and  bitter,  and  for  these,  too,  there  are  in- 
termediates. (See  p.  353.)  In  somesthesis, 
the  body  sense,  the  unique  qualities  are 
pressure,  pain,  warmth  and  cold.  There 
are  also  a  great  many  complex  patterns  of 
these  four  qualities,  like  hunger,  dizziness 
and  itch.  (See  p.  360.)  Hearing  is  the 
one  sense  that  cannot  be  reduced  to  a  few 
unique  qualities.  The  tones  form  a  con- 
tinuous series  of  qualities  from  the  lowest 
pitch  to  the  highest.  Instead  of  a  mere 
four  or  seven  unique  qualities  we  have  in 
hearing  all  the  separate  pitches  the  ear  can 
hear,  a  thousand  or  more. 

Why  do  we  experience  different  quali- 
ties? Why  is  a  sight  so  different  in  quality 
from  a  sound?  How  can  the  brain  tell  a 
smell  from  a  pat  on  the  hand?  Actually, 
there  is  almost  no  satisfactory  physiological 
theory  of  sensory  quality.  All  we  know 
about  quality  is  that  the  fibers  for  each  of 
the  five  senses  lead  to  a  particular  part  of 
the  cerebral  cortex.  It  seems  probable  that 
of  the  four  unique  qualities  of  the  sense 
of  touch  each  has  its  special  nerve  fibers; 
that,  in  hearing,  although  a  given  tone 
excites  many  fibers,  its  quality  may  be  de- 


pendent upon  the  excitation  of  one  par- 
ticular fiber  more  than  the  others.  In 
vision  it  seems  likely  that  there  are  only 
three  kinds  of  nerve  fibers  in  the  optic 
nerve,  and  that  the  six  or  seven  tinique 
colors  are  not  differentiated  physiologically 
from  the  others  until  the  excitation  has 
reached  the  brain.  There  the  mystery  is 
complete.  All  we  can  say  is  that,  when  an 
organism  is  making  a  qualitative  discrimi- 
nation, it  is  distinguishing  between  the  ex- 
citation of  different  systems  of  nerve  fibers. 
Quality  indicates  what  neural  system  is 
functioning,  which  fibers  are  excited.  In- 
tensity, extension  and  duration  merely  tell 
how  the  system  is  functioning.  That  is 
why  quality  seems  to  be  more  fundamental 
than  the  other  attributes,  why  we  talk 
about  the  loudness  of  a  pitch  but  not  the 
pitch  of  a  loudness,  about  the  duration 
of  a  red  but  not  the  redness  of  a  duration. 

Intensity 

Usually  the  intensity  of  a  sensation  in- 
creases when  the  energy  of  its  stimulus  is 
increased.  A  paperweight  makes  more 
noise  if  it  drops  from  the  desk  to  the  floor 
than  if  it  drops  only  a  few  inches.  On  the 
other  hand,  intensity  of  sensation  also 
varies  with  the  sensitivity  of  the  sense 
organ.  In  hearing,  for  instance,  sensitivity 
is  greatest  in  the  middle  of  the  musical 
scale.  A  tone  in  this  region,  therefore,  re- 
quires less  energy  than  a  low  tone  in  order 
to  sound  equally  loud. 

Both  vision  and  hearing  are  senses  tuned 
to  respond  to  certain  limited  ranges  of  a 
continuous  stimulus.  The  electromagnetic 
waves,  some  of  which  we  call  light,  extend 
through  a  long  range  (see  Fig.  114,  p. 
275);  yet  the  retina  responds  to  only 
a  limited  range  of  these  wave  lengths.  The 
long  infrared  waves  and  the  short  ultra- 
violet waves  are  invisible  under  most  cir 


Psycbopbysics 


255 


cumstances.  For  visible  light  the  retina  is 
least  sensitive  at  the  two  extremes  of  the 
spectrum  and  most  sensitive  in  the  middle. 
(See  Fig.  120,  p.  291.)  Similarly  the  ear  re- 
sponds to  only  a  limited  range  of  tonal  fre- 
quencies, being  completely  deaf  to  very 
low  and  very  high  frequencies  and  most 
sensitive  to  the  middle  frequencies  of  the 
musical  range.  (See  Fig.  154,  p.  324.)  Thus 
it  is  plain  that,  if  we  wish  to  predict  the 
intensity  of  a  sensation,  we  must  know 
about  the  stimulus,  its  frequency  and  its 
energy,  and  we  must  know  about  sensi- 
tivity as  well.  The  sensitivity  of  the  or- 
ganism to  a  given  stimulus  is  just  as  im- 
portant as  the  energy  of  the  stimulus. 

PSYCHOPHYSICS 

The  obvious  fact  about  sensation  is  that 
it  arises  from  an  interaction.  Some  form 
of  energy  impinges  upon  a  sensitive  re- 
ceptor in  a  living  organism,  and  the  or- 
ganism reacts.  The  organism  sees,  hears, 
smells,  tastes,  feels.  These  reactions  are 
psychological  processes,  set  in  motion  by 
physical  events.  When  we  study  sensation, 
therefore,  what  we  discover  is  the  relation 
between  those  two  aspects  of  the  universe 
commonly  called  the  mental  and  the  physi- 
cal. We  learn  how  experience  depends 
upon  stimulation.  We  learn  what  it  takes 
by  way  of  a  cause  to  set  off  a  response  in  a 
perceiving  organism. 

Psychophysics  was  christened  by  G.  T. 
Fechner,  a  physicist  and  philosopher,  who 
in  1860  gave  us  a  treatise  on  a  new  science 
of  the  "relation  between  mind  and  mat- 
ter"—meaning  the  relation  between  sensa- 
tion and  the  stimulus  that  causes  it. 
Fechner's  basic  notion  was  simple.  He  be- 
lieved that,  if  he  could  measure  both  the 
strength  of  a  stimulus  and  the  magnitude 


of  the  sensation  it  arouses,  he  would  have  a 
formula  relating  physics  and  psychology. 
He  asked,  for  example,  how  great  is  the 
loudness  we  experience  when  we  listen  to  a 
sound  wave  of  a  given  energy.  Or  how 
bright,  subjectively,  is  a  light  of  so  manv 
candle-power? 

These  are  complicated  questions,  as  later 
chapters  will  show.  We  no  longer  give 
them  the  same  answers  that  Fechner  gave, 
for  psychophysics  has  moved  ahead,  and 
new  methods  of  psychophysical  investiga- 
tion have  been  evolved.  These  methods 
are  used  nowadays  to  answer  practical, 
everyday  questions  as  well  as  to  settle 
theoretical  problems.  They  are  essential 
to  engineers  and  designers  as  well  as  to 
psychologists.  All  attempts  to  adapt  ma- 
chines and  gadgets  to  the  sensory  capacities 
of  human  beings  raise  problems  in  psycho- 
physics which  can  be  solved  by  its  methods. 

The  story  of  the  telephone  is  a  case  in 
point.  The  earliest  instruments  were  unre- 
liable devices.  You  spoke  your  message 
and  the  listener  asked,  "What  did  you 
say?"  You  shouted  into  the  mouthpiece 
and  he  still  did  not  understand.  Trial- 
and-error  on  the  part  of  in\entors  brought 
improved  clarity,  but  the  last  word  in  high- 
fidelity  transmission  was  impossible  until 
the  psychophysics  of  hearing  had  been  ex- 
plored. In  one  of  the  world's  largest  re- 
search laboratories  careful  studies  were 
made  of  the  behavior  of  the  ear:  its  sensi- 
tivity to  different  frequencies,  its  response 
to  sounds  of  varying  intensity,  its  ability 
to  hear  tones  masked  by  noise.  These  re- 
searches established  the  performance  re- 
quirements of  the  telephone:  how  it  should 
transmit  the  sounds  of  speech  in  order  for 
them  to  be  correctly  percei^"ed.  Kno^\ing 
what  they  ivere  aiming  at,  tlie  designers 
could  then  proceed. 


256 


Sensation  and  Psychological  Measurement 


Psychophysical  Problems  and  Methods 

The  procedures  used  in  psychophysical 
studies  are  as  varied  as  ingenious  re- 
searchers confronted  by  complex  problems 
can  make  them.  There  are  two  useful 
ways,  however,  of  classifying  them:  (1)  by 
the  type  of  judgment  or  reaction  made  by 
the  subject  in  the  experiment;  (2)  by  the 
method  of  presenting,  controlling  and 
measuring  the  stimulus.  Thus  the  prob- 
lem has  two  facets:  the  psychological  and 
the  physical.  There  are  several  ways  of 
getting  at  the  psychological  experience  of 
the  subject— ways  of  having  him  respond— 
and  there  are  many  procedures  for  manipu- 
lating the  physical  energies  and  forces  to 
which  he  is  exposed.  In  general,  our  choice 
of  procedures  is  guided  by  the  nature  of 
the  problem  we  set  ourselves,  but  we  often 
find  it  impossible  to  follow  what  might  be 
the  ideal  method.  We  cannot,  for  example, 
change  the  intensity  of  a  smell  by  known 
physical  amounts  in  the  way  we  can  alter 
the  intensity  of  a  light.  Many  problems 
in  psychophysics  must  wait  on  further  de- 
velopments in  the  other  sciences. 

It  is  the  business  of  psychophysics  to  ask 
questions  about  the  behavior  of  man  and 
animals.  And  since  the  character  of  a  sci- 
ence is  revealed  by  the  kind  of  questions 
it  poses— and  by  the  way  it  tracks  down  the 
answers— we  do  well  to  list  the  types  of 
questions  asked  and  answered  by  psycho- 
physical procedures.  Of  course  these  are 
technical,  scientific  questions,  designed  to 
reveal  the  laws  and  principles  of  behavior. 
They  are  the  kinds  of  questions  that  in- 
volve measurement  and  experimentation 
guarded  by  careful  controls.  Broken  down 
into  their  principal  categories,  we  find  that 
these  questions  raise  seven  kinds  of  psycho- 
phvsical  problems. 


(1)  Absolute  thresholds.  What  is  the 
smallest  stimulus  that  will  set  off  a  response 
on  the  part  of  an  organism? 

Example.  How  faint  is  the  faintest 
light  a  man  can  see?  (Answer.  Five  to 
seven  quanta  of  light  energy'  falling  on 
the  retina  may  produce  a  visual  response. 
A  quantum  is  the  smallest  package  of 
light  energy  possible  in  nature.) 

(2)  Differential  thresholds.  What  is  the 
smallest  change  in  a  stimulus  that  can  be 
detected? 

Example.  How  many  ounces  must  be 
added  to  a  pound  in  order  to  make  it 
feel  heavier?  (Answer.  .About  half  an 
ounce.) 

(3)  Equality.  "What  values  must  two 
stimuli  have  in  order  to  produce  equality 
in  a  given  attribute? 

Example.  What  intensity  of  red  light 
appears  as  bright  as  a  given  intensity  of 
green  light?  (Ansicer.  The  red  light 
must  have  about  eight  times  the  physical 
intensity  of  the  green  light.) 

(4)  Order.  Given  a  set  of  stimuli,  what 
is  their  order  of  progression  from  least  to 
greatest  with  respect  to  some  attribute  or 
quality? 

Example.  What  is  the  relative  merit 
of  the  music  of  these  composers:  Bach, 
Beethoven,  Chopin,  Grieg,  Tschaikovsky, 
Wagner?  (Answer.  By  308  members  of 
four  leading  symphony  orchestras  the 
music  of  these  comjjosers  was  preferred 
in  the  order:  Beethoven,  AVagner,  Bach. 
Tschaikovsky,   Chopin  and  Grieg.) 

(5)  Equality  of  inten>als.  When  is  the 
apparent  difference  between  two  experi- 
ences the  same  as  the  difference  between 
two  other  experiences?     Or.   as   a   special 


Psychophysics  and  Measurement 


257 


case,  vvlu'ii  docs  one  scnsalioii  Mpixat  to 
he  ((iiiidisl.int  hclwccn  two  oilier  sciisa- 
I  ions? 

Exdiii jilc.  V\'li;ii  note  on  ilir  piano 
has  a  ])it(li  that  sonnds  ('(|uidistan(  Ix- 
Iwcfii  middle  (;  and  the  (  fonr  octaves 
above  it?  [Answer.  N'ot  the  c  at  the 
second  octave  aho\c  noddle  (J,  as  you 
might  sn|)|)osc,  Ixit  the  note  j^  above 
this  c.) 

(fi)  E<iuaHty  of  ralio.s.  When  is  the  ap- 
j)aitnt  ratio  between  two  experiences  the 
same  as  the  apparent  ratio  between  two 
otiui  experiences?  Or  what  stimuli  pro- 
duce sensations  having  a  given  latio  with 
respect  to  eac  h  other? 

Exdinplr.  How  many  ounces  fcrl  half 
as  heavy  as  a  pound?  (Ansxi'er.  About 
eleven  oinices.  Eight  ounces  feel  much 
less  than  half  as  heavv   as  a  pound.) 

(7)  Stimulus  ratiui^.  How  accurately  can 
a  person  name  the  correct  physical  value 
of  a  stimidus  which  he  can  sense  but  caiuiot 
nieasine  directly? 

Examples.  Several  of  (hem,  mostlv  un- 
answered c]uestions:  How  accurately  can 
aviators  estimate  their  height  in  feet 
above  the  ground?  How  well  can  police- 
men estimate  the  speed  of  passing  cars? 
How  precisely  can  a  farmer  estimate  the 
area  of  a  field?  In  trying  to  answer  these 
cjuestions  the  experimenter  would  usu- 
ally be  interested,  not  onlv  in  the  ac- 
curacy of  the  estimate  itself  but  also  in 
the  factors  which  tend  to  increase  or 
decrease  the  acciuacy.  Some  of  these 
factors  woidd  come  under  the  heading 
of  what   we  commonh    call   illusions. 

To  each  of  the  types  of  problems  listed 
above  we  can  applv  a  ^arietv  of  psycho- 
physical  procedures.      In   other   words,   we 


can  present  the  stimuli  in  a  variety  of  wrayt 
and  wc  can  ask  the  subject  to  iniliraie  hu 
response  in  several  inanners.  These  meth- 
ods and  their  many  variants  have  im{Xir- 
lant  uses  in  psychcilcigy  in  all  its  brandies. 
.Some  of  them  {x:rinil  the  detailed  M.TUtiny 
of  the  function  of  the  sense  organs  them- 
selves. .Scjnic  of  them  enable  us  to  measure 
sensation  and  tell  how  cjne  sensory  ex[x.Ti- 
ence  compares  with  ancjther.  Others  have 
nicjie  practical  uses.  They  make  it  pos- 
sible to  grade  conunodities  like  leather  and 
perfumes  and  wines  in  terms  of  psycholog- 
ical scales  set  up  by  experienced  judges. 
They  even  provide  the  basis  of  techniques 
that  are  used  in  the  |>olling  of  public  opin- 
ion and  in  the  assessment  of  consumer 
attitudes. 

SCALES    OF    MEASUREMENT 

Measurement  is  the  backbone  of  the 
scientific  method.  Primitive  peoples  usu- 
ally speak  of  "a  lot  of"  this  or  "a  little  of* 
that.  Scientists,  trving  to  get  away  from 
being  primitive,  like  to  pin  numbers  on 
things.  They  are  not  content  \siih  the 
mere  statement  that  something  is  hot  or 
cold.  Instead,  they  ask  what  its  tenifjera- 
ture  is  in  terms  of  degrees  on  a  scale.  Not 
many  centuries  ago  there  were  no  scales  of 
temperature  and  no  way  of  making  hot 
and  cold  a  quantitative  matter.  Methcxb 
of  measining  temperatme  had  to  be  de- 
vised. Someone  in  the  middle  of  the  sev- 
enteenth centurv  had  to  invent  a  ther- 
mometer. 

Psychology  uses  many  of  the  scales  cm- 
ployed  in  the  other  sciences,  and  it  also 
invents  scales  of  its  own  with  which  to 
measine  in  psychological  dimensions.  We 
have  scales  for  measuring  attitudes,  intelli- 
gence, learning,  sensation,  etc.  Some  of 
the   scales    are    rather   crude    affairs:    some 


258 


Sensation  and  Psychological  Measurement 


show  considerable  refinement.  The  ac- 
curacy and  usefulness  of  any  scale  depend, 
of  course,  upon  the  care  and  ingenuity  of 
its  creator,  but  they  also  depend  upon  other 
things,  particularly  upon  -which  of  the  four 
basic  kinds  of  scale  is  being  used.  These 
four  categories  of  scales  are  called  by  the 
names  (1)  nominal  scale,  (2)  ordinal  scale, 
(3)  intenial  scale  and  (4)  ratio  scale. 

(1)  The  nominal  scale  is  the  most  primi- 
tive of  the  four.  In  fact  it  is  not,  in  the 
ordinary  sense,  a  scale  of  measurement  at 
all.  But  for  the  sake  of  completeness  we 
must  include  it  here,  because  it  is  what  we 
achieve  when  we  pin  numbers  on  objects 
or  on  classes  of  objects  in  order  to  keep 
track  of  them.  For  example,  a  coach  num- 
bers the  football  players  on  his  team,  or  a 
manufacturer  uses  a  model  number  to 
stand  for  a  class  of  automobiles.  There 
is  actually  more  to  this  simple-minded  pro- 
cedure than  meets  the  eye,  for  if  the  coach 
could  not  tell  his  players  apart  in  the  first 
place,  he  could  not  give  each  player  a  dif- 
ferent number.  And  it  is  only  because  the 
automobile  maker  thinks  all  of  a  certain 
group  of  cars  are  equal  in  some  respect 
that  he  gives  them  all  the  same  model 
number. 

We  see,  therefore,  that  the  nominal  scale 
is  not  entirely  trivial.  It  has  great  practi- 
cal importance,  and,  what  is  of  more  in- 
terest to  us,  its  creation  really  depends 
upon  our  ability  to  determine  (a)  that 
something  is  present  (so  that  we  can  give 
it  a  number)  and  {h)  what  other  things  are 
equal  to  it  (so  that  we  can  give  them  the 
same  number).  In  other  words,  we  have 
to  be  able  to  answer  the  psychophysical 
problem  of  equality— problem  3  in  our  list 
above. 

(2)  The  ordinal  scale  is  more  interesting. 
It  is  the  kind  of  scale  we  can  set  up  when- 
ever we  can  determine  the  rank  order  of  a 


set  of  items.  Thus  the  composers  listed  on 
page  256  are  arranged  on  an  ordinal  scale 
of  merit,  from  greatest  to  least,  in  the  opin- 
ion of  other  musicians.  A  scale  of  rank 
order  cannot  be  set  up  unless  we  can  solve 
problem  4  above:  the  determination  of  the 
direction  of  a  difference. 

On  the  ordinal  scale  of  musical  merit  we 
find  that  Beethoven  is  better  than  Wagner, 
who  is  better  than  Bach.  But  this  scale 
does  not  tell  us  how  much  better  Beethoven 
is  than  Wagner,  nor  whether  the  difference 
between  these  two  is  the  same  as  the  differ- 
ence between  Wagner  and  Bach.  In  other 
words,  the  ordinal  scale  is  not  a  quantita- 
tive scale  in  the  layman's  sense  of  the  term 
quantitative.  It  is  nevertheless  a  very  use- 
ful device,  as  is  shown  by  the  fact  that 
many  such  scales  are  in  daily  use.  They 
are  used  to  rate  applicants  for  jobs,  to 
scale  personality  traits,  to  measure  intelli- 
gence and  to  grade  examination  papers. 
(See  Fig.  99  for  ordinal  scales.) 

When  the  instructor  gives  you  A,  B,  C 
or  D  on  a  term  paper  he  is  using  an  ordi- 
nal scale.  Of  course  he  may  give  a  nu- 
merical instead  of  a  letter  grade,  but  that 
does  not  change  the  situation.  When  you 
get  90  and  your  friend  gets  70,  it  means 
that  your  paper  is  somewhat  better  than  his 
(from  the  instructor's  point  of  view),  but 
you  cannot  say  how  much  better  it  is.  This 
is  true  simply  because  there  is  no  way  of 
knowing  whether  the  units  on  the  in- 
structor's grading  scale  are  equal  from  unit 
to  unit.  Is  the  difference  between  70  and 
80  the  same  as  the  difference  between  80 
and  90?  Since  neither  you  nor  the  in- 
structor can  answer  that  question,  we  are 
forced  to  conclude  that  he  grades  on  an  or- 
dinal scale. 

Actually,  if  you  were  to  count  up  all  the 
scales  described  in  books  on  psychology, 
you  would  find  that  most  of  them  are  or- 


Scales  of  Measurement 


259 


Violet 


pleasant 

■  Sweet  /Red 

'Cloves 
-S§/white  rose ,\V  Sour 

/^  '^/  C5> 

Cananga        /Bitter  /    Bluish  green 

Thyme  /  /Yellow 

'Geranium        /Salt  ,.        .  .       ,, 

^  /Greenish  yellow 

Least     pleasant 

FIGURE    gg.      SOME   ORDINAL   SCALES    OF    PLEASANT- 
NESS-UNPLEASANTNESS 

Odors:  samples  from  a  list  of  14  olfactory  stimuli 
ranked  by  8  observers  using  the  method  of  paired 
comparisons  (each  stimulus  compared  with  each 
other  stimulus) . 

Tastes:  average  rank  order  obtained  from  7  to 
10  observers  who  rated  each  taste  on  a  three-point 
scale.  The  concentrations  used  were  20  times  the 
threshold  concentration  (the  least  concentration  de- 
tectable as  different  from  plain  water).  At  other 
concentrations  the  rank  order  may  be  different. 
For  example,  at  10  times  the  threshold  concentra- 
tion salt  is  preferred  to  bitter. 

Colors:  18  squares  of  colored  paper  were  ranked 
by  1279  college  students  using  the  method  of  paired 
comparisons.  Many  factors  and  causes  may  alter  a 
person's  preference  for  colors. 

[Data  from  J.  G.  Beebe-Center,  Pleasantness  and 
unpleasantness.  Van  Nostrand,  1932.] 

dinal  scales.  It  is  far  easier  to  arrange 
things  in  rank  order  than  it  is  to  devise 
scales  for  measuring  them  in  terms  of  equal 
units.  But  rank  ordering  is  not  always 
easy.  How,  for  example,  would  you  scale 
the  following  traits  in  order  of  their  im- 
portance for  success  in  business:  perse- 
verence,  courage,  honesty,  initiative,  op- 
timism, friendliness,  intelligence,  loyalty? 
(3)  The  intewal  scale  is  one  on  which 
the  units  are  equal  but  on  which  the  zero 
point  is  arbitrarily  chosen.  The  ordinary 
Fahrenheit  temperature  scale  is  a  good  ex- 
ample. The  units  (degrees)  are  equal,  but 
the  zero  point  is  just  an  arbitrary  tempera- 
ture chosen  by  the  German  physicist, 
Fahrenheit,  that  of  a  freezing  mixture  of 


ice  and  salt.  The  centigrade  scale  is  an- 
other example  of  an  interval  scale,  and  it 
has  a  different  zero  point,  the  temperature 
of  ice  water  without  salt  (Fig.  100).  On 
both  these  scales  we  know  that  the  units 
are  equal  because  we  set  up  the  units  by 
marking  off  equal  distances  on  a  column 
of  mercury  or  alcohol,  which  expands  with 
increasing  temperature.  Then  each  rise  of 
one  degree  in   temperature   lengthens   the 


Boiling       — 100  ■ 


200 


150 


—  100 


50 


50  — 


Freezing 


0  — 


# 


Fahrenheit 


Centigrade 


FIGURE    100.    INTERV.AL    SC.\LES 

On  each  scale  the  units  are  of  equal  size,  but  the 
Fahrenheit  units  are  five-ninths  as  large  as  the  cen- 
tigrade units.  Each  scale  has  a  different  zero  point, 
and  neither  zero  point  on  the  scale  represents  a 
'true'  or  'absolute'  zero  in  temperature. 


260 


Sensation  and  Psychological  Measurement 


column  by  the  same  amount.  By  this  pro- 
cedure we  solve  for  temperature  scales  the 
problem  of  equality  of  intervals,  the  same 
kind  of  problem  we  listed  on  page  256  as 
psychophysical  problem  5. 

When  equal  intervals  can  be  determined 
for  sensation,  intelligence  or  some  other 
psychological  variable,  scales  having  equal 
units  can  be  established.  The  intelligence 
tester  makes  the  units  on  his  scale  as  equal 
as  possible  by  adjusting  (a)  the  difficulty  of 
the  items  on  his  test  and  (b)  the  numerical 
credit  given  the  testee  for  passing  a  given 
item.  He  then  concludes  that  the  units 
are  equal  if  a  large  group  of  children, 
chosen  at  random,  make  scores  that  distrib- 
ute themselves  according  to  the  normal 
curve  (p.  262).  His  conclusion  is  correct, 
of  course,  only  provided  the  intelligence 
of  the  children  is  really  normally  dis- 
tributed—something the  psychologist  can 
assume  but  not  prove  in  advance.  Never- 
theless, by  proceeding  on  this  assumption 
of  a  normal  distribution,  we  get  highly  use- 
fid  scales  for  measuring  human  traits  and 
abilities,  scales  having  reasonably  equal 
imits  but  whose  zero  points  are  generally 
arbitrary.  An  uncritical  critic  might  make 
the  rash  claim  that  his  competitor  has  no 
intelligence  whatever,  but  he  would  speak 
loosely,  for  no  one  knows  what  zero  intelli- 
gence is. 

(4)  True  zero  points  are  possible  only  on 
ratio  scales.  And  in  order  to  set  up  a  ratio 
scale  we  must  be  able  to  determine  not 
only  equal  intervals  but  equal  ratios  as 
well.  Scales  of  length,  weight  and  electri- 
cal resistance  are  examples  of  ratio  scales. 
In  fact  so  are  most  of  the  other  scales  used 
in  physics.  We  can  demonstrate  that  two 
inches  is  half  of  four  inches  and  that  four 
inches  is  half  of  eight  inches.  If  we  knew 
nothing  about  these  ratios  we  should  not 


know  where  to  put  the  zero  point  on  the 
scale,  and  vice  versa. 

The  stimuli  used  in  psychophysical  ex- 
periments are  nearly  always  measured  on 
ratio  scales.  The  sensations  produced  by 
these  stimidi  can  also  be  measured  on  ratio 
scales  whenever  we  can  solve  the  psycho- 
physical problem  of  sensed  ratios  (problem 
6,  p.  257).  For  example,  if  we  can  find  out 
what  weights  feel  half  as  heavy  as  what 
other  weights,  we  can  set  up  a  ratio  scale  of 
perceived  weight,  as  distinct  from  the  phys- 
ical weight  which  we  measure  in  pounds 
and  ounces.  With  the  aid  of  the  psycholog- 
ical scale  of  weight,  we  might  then  be  able 
to  tell  the  grocer  how  to  package  his  dried 
beans  so  that  a  package  of  one  size  will  feel 
fifty  per  cent  heavier,  say,  than  the  next 
smaller  size. 

Figure  101  shows  a  ratio  scale  of  per- 
ceived weight.  This  scale  was  obtained  by 
the  simple  procedure  of  having  a  group  of 
subjects  select  from  among  a  graded  series 
of  weights  the  one  that  felt  half  as  heavy 
as  a  given  standard.  Standards  weighing 
different  amounts  were  used,  of  course,  and 
the  complete  data  were  employed  to  con- 
struct the  curve  in  Fig.  101.  The  dotted 
lines  illustrate  the  basis  on  which  the  curve 
was  drawn;  a  weight  of  100  grams  gives  a 
psychological  impression  which  we  say  ar- 
bitrarily corresponds  to  one  psychological 
unit  or,  to  name  the  unit,  one  veg  (from 
an  old  Anglo  Saxon  word  meaning  "to 
lift").  Then  0.5  psychological  imit  must 
correspond  to  the  physical  weight  that  feels 
half  as  heavy,  since  0.5  is  half  of  1.0.  But 
our  experiment  tells  us  that  72  gi-ams  feel 
half  as  heavy  as  100  grams.  Therefore  our 
graph  must  pass  through  the  cross  and  also 
through  the  circled  point  on  the  plot— 
the  point  indicated  by  the  dotted  lines  con- 
necting the  value  of  0.5  veg  on  the  vertical 
scale  with  72  grams  on  the  horizontal  scale 


Stafistics  and  Measurement 


261 


50  100  150  200 

Physical  weight  in  grams 

FIGURE    101.       PSYCHOLOGICAL   RATIO    SCALE 

Relates  perceived  weight  in  vegs  to  physical 
weight  in  grams.  A  veg  is  defined  arbitrarily  as  the 
value  of  the  subjective  impression  obtained  by  lift- 
ing a  weight  of  100  grams.  By  experiment  it  is  de- 
termined that  72  grams  feel  half  as  heavy  as  100 
grams.  Therefore  half  a  veg  corresponds  to  72 
grams.  The  curve  shows  that  perceived  weight  in- 
creases much  more  rapidly  than  physical  weight. 
[Data  from  R.  S.  Harper  and  S.  S.  Stevens,  Anier.  J. 
Psychol,  1948,  61.] 

By  extending  this  logic  we  obtain  other 
points  on  the  curve,  and  eventually  we  map 
out  the  entire  graph  relating  perceived 
weight  and  physical  weight. 

STATISTICS    AND 
MEASUREMENT 

None  of  the  seven  basic  problems  of  psy- 
chophysics  can  be  solved  without  the  use 
of  statistics.  The  reason  for  this  is  ob- 
vious. The  behavior  of  living  organisms 
is  variable.  Seldom  does  their  behavior  re- 
peat itself  exactly  from  moment  to  mo- 
ment. Nor  does  the  behavior  of  one  in- 
dividual always  duplicate  that  of  another. 
For  this  reason  the  answers  to  psycholog- 


ical questions  are  nearly  always  statistical 
answers.  They  are  usually  given  in  terms 
of  averages  and  variabilities— the  elemen- 
tary but  important  concepts  in  what  has 
lately  become  a  higlily  developed  branch 
of  mathematics.  --^      / 


Central  Tendency  // 

The  common  cv^-ryday  notion  of  an  aver- 
age—so familiar  to  baseball  fans— is  usually 
one  of  three  measures  of  central  tendency. 
The  statistician's  name  for  the  average  is 
the  mean.  And  two  other  measures  of  cen- 
tral tendency  are  the  median  and  the 
mode.  We  shall  define  these  measures  with 
the  aid  of  an  illustration. 

Suppose  we  show  a  group  of  ten  subjects 
a  horizontal  line  twenty-four  inches  long 
and  ask  them  to  estimate  its  length.  The 
ten  estimates  might  give  us  the  following 
distribution  of  guesses:  17,  18,  20,  20,  20, 
22,  22.  24,  27,  30.  What,  then,  is  the  mean 
or  average  estimate?  In  order  to  obtain 
the  mean  we  add  up  all  the  individual 
estimates  (scores)  and  divide  by  the  num- 
ber of  scores.  This  gives  twenty-two  inches 
as  the  mean  estimate  of  the  group  of  ten 
subjects.  We  conclude  that  on  the  average 
they  underestimated  the  length  of  the  line. 

We  might  also  ask  another  question 
about  these  estimates:  ^Vhat  ^■alue  divides 
the  scores  into  two  groups  such  that  the 
estimates  of  half  the  subjects  are  equal  to 
or  lower  than  this  value  and  half  are  equal 
to  or  higher  than  this  value?  The  answer 
gives  us  the  median  of  the  disuibution.  In 
our  example  the  median  would  be  the 
value  midway  between  the  scores  for  the 
fifth  subject,  who  guessed  20,  and  the  sixth 
subject,  who  guessed  22.  The  median  then 
is  21  inches.  Fifty  per  cent"  of  the  guesses 
lie  above  this  point  and  50  per  cent  lie 
below. 

The  mode  is  simpiv  the  value  in  tlie  dis- 


262 


Sensation  and  Psychological  Measuremenf 


tribution  that  occurs  with  greatest  fre- 
quency. Since  20  inches  was  guessed  more 
often  than  any  other  value,  we  see  at  once 
that  the  mode  is  20  inches. 

Which  of  these  three  measures  of  central 
tendency  should  we  use?  The  answer  de- 
pends upon  what  we  want  to  know,  the 
kind  of  question  we  ask.  Generally  speak- 
ing, the  mean  is  the  mosj  useful  measure  in 


that  the  line  tends  to  be  underestimated, 
but  they  also  show  that  the  judgments 
above  the  mean  are  spread  out  further 
than  those  below.  In  other  words,  the 
distribution  tails  off  more  gradually  at  the 
right  than  at  the  left.  If  we  observed  1000 
cases  instead  of  10,  we  should  get  rid  of 
all  the  small  irregularities  in  the  curve, 
but  these  other  two  features  might  remain 


10  12  14  16  18  20  22  24 

Estimated  length  in  inches 

FIGURE    102.      DISTRIBUTIONS  OF  DATA 

The  heights  of  the  vertical  bars  show  how  many  times  each  value  on  the  horizontal  scale  was  given  as 
the  estimated  length  of  a  line.  The  dotted  curve  shows  the  shape  of  a  normal  distribution  (see  text). 
The  distance  indicated  by  c  is  the  standard  deviation  of  the  distribution. 


the  sense  that  it  is  the  most  stable.  If  we 
were  to  enlist  another  10  subjects  for  our 
experiment  and  get  10  more  guesses,  the 
mean  of  the  second  group  would  probably 
not  be  very  different  from  that  of  the  first— 
not  so  different,  at  any  rate,  as  the  median 
of  the  second  group  compared  with  the 
median  of  the  first.  And  the  mode  would 
be  the  least  stable  of  all.  This  fickleness 
on  the  part  of  the  mode  is  unfortunate,  be- 
cause the  mode  is  extremely  simple  to  de- 
termine. Apparently  what  comes  easiest  in 
statistics  is  often  not  worth  very  much. 

The  data  for  10  subjects,  plotted  as  ver- 
tical bars  in  Fig.  102,  show  a  roughly  bell- 
shaped  distribution:  the  judgments  tend 
to  cluster  near  the  mean.     They  indicate 


as  the  facts  of  the  case,  provided  we  still 
use  this  scale  of  inches  for  measuring  them. 
More  often  than  not  we  get  underestima- 
tions,  yet  the  overestimations,  when  they  do 
occur,  show  larger  departures  from  the 
average  of  the  group. 

The  dotted  curve  of  Fig.  102  is  the  so- 
called  curve  of  normal  distribution.  Ob- 
served data  very  often  approximate  it  when 
the  deviations  from  the  mean  are  due  to  a 
multitude  of  chance  factors  and  when  the 
total  number  of  cases  is  large.  When  the 
data  do  not  approximate  the  normal  curve, 
the  scientist  often  changes  the  scale  of  his 
distribution,  stretching  it  at  one  end  and 
pushing  it  together  at  the  other,  so  as  to 
force  the  curve  to  be  more  nearly  normal. 


r 


Cenfrai  Tendency  and  Variabilify 


263 


He  does  that  because  he  wishes  to  treat  his 
data  under  the  conventional  rules  of  statis- 
tics, many  of  which  have  been  worked  out 
in  their  simplest  forms  only  for  the  normal 
curve. 

It  is  clear  that  when  data  can  be  prop- 
erly represented  by  the  normal  curve,  their 
mean,  median  and  mode  all  have  the  same 
value,  for  the  normal  distribution  is  sym- 
metrical about  its  single  mode.  (On  nor- 
mal distribution,  see  also  pp.  418  f.) 

Variability 

Measures  of  variability  tell  us  how  widely 
the  data  scatter  about  their  mean.  The 
important  measures  of  variability  are  the 
range,  the  standard  deviation  and  the  prob- 
able error. 

The  range  is  simply  the  difference  be- 
tween the  highest  and  the  lowest  score. 
As  with  the  mode,  we  come  by  it  easily  but 
it  tells  us  relatively  little.  The  range  of 
guesses  for  the  length  of  the  line  in  our 
experiment  is  30—17  =  13  inches.  Com- 
mon sense  tells  us  that  another  group  of 
ten  subjects  would  probably  not  scatter  its 
guesses  over  precisely  this  same  range.  So 
what  is  needed  is  a  more  stable  measure  of 
variability. 

The  standard  deviation  gives  us  this 
greater  stability  and  is  the  most  important 
measure  of  variability  in  the  whole  field 
of  statistics.  In  technical  language  the 
standard  deviation,  designated  by  the 
Greek  letter  sigma  (a),  is  defined  as  the 
square  root  of  the  mean  of  the  sum  of  the 
squares  of  the  deviations  from  the  mean. 
What  this  boils  down  to  is  simply  that,  in 
order  to  compute  o-,  we  first  find  the  mean, 
then  we  subtract  the  value  of  the  mean 
from  each  score  in  turn.  We  then  square 
each  of  the  results,  add  them  all  up,  di- 
vide by  the  number  of  scores  and  finally 
,    take  the  square  root. 


Apply  this  formula  to  the  ten  estimates 
of  the  length  of  the  line,  and  you  will  find 
that  the  standard  deviation  of  the  distribu- 
tion equals  3.8  inches.  In  Fig.  102  the 
upper  and  lower  standard  deviations  on 
either  side  of  the  mean  are  indicated  by 
vertical  dotted  lines. 

It  is  interesting  to  note  that  the  area  ly- 
ing under  the  normal  curve  and  between 
the  upper  and  lower  standard  deviations  is 
equal  to  about  two-thirds  of  the  total  area. 
If  we  were  to  draw  verticals  to  points  on 
either  side  of  the  mean  so  that  just  half  the 
area  lay  between  them,  we  should  have 
to  pick  points  nearer  the  mean.  Those 
points,  with  half  the  area  below  the  curve 
lying  between  them,  are  the  values  de- 
fining the  probable  error  (P.E.).  In  nu- 
merical terms  it  turns  out  that  the  prob- 
able error  is  equal  to  0.6745(7.  The  prob- 
able error  gets  its  name  from  this  fact:  If 
the  scores  that  scatter  about  the  mean  are 
regarded  as  errors,  the  probability  is  50-50 
that  a  particular  error  will  lie  inside  the 
limits  set  by  the  probable  error. 

THRESHOLDS 

All  living  organisms  exhibit  the  phe- 
nomena known  as  thresholds.  Some  stim- 
uli affect  them;  others  do  not.  Some  lights 
are  too  faint  to  be  seen,  some  sounds  too 
faint  to  be  heard.  But,  as  the  intensity  of 
a  light  or  a  sound  is  increased,  there  comes 
a  point  at  which  it  is  seen  or  heard.  At 
any  instant,  it  appears,  this  point  at  which 
a  stimulus  just  crosses  the  tlireshold  must 
be  fixed,  definite  and  precise.  But,  un- 
fortunately, at  two  different  instants  the 
threshold  point  is  not  the  same.  The  or- 
ganism's properties  do  not  stay  put.  In- 
stead, its  sensitivity  bobs  up  and  doAvn 
from  moment  to  moment.  Consequently, 
when  we  want  to  determine  the  threshold 


264 


Sensation  and  Psychological  Measurement 


we  have  to  make  repeated  measurements 
and  we  have  to  apply  statistical  procedures 
to  the  resulting  data.  For  this  reason  it  is 
commonly  said  that  the  threshold  is  a  sta- 
tistical concept. 

When  we  examined  the  seven  basic  prob- 
lems of  psychophysics,  we  saw  that  there 
are  two  kinds  of  threshold,  absolute  thresh- 
olds and  relative  or  differential  thresholds. 
The  absolute  threshold  is  the  value  of  a 
stimulus  which  is  (on  the  average)  just 
noticeable  or  just  detectable.  The  differ- 
ential threshold  is  that  difference  between 
two  stimuli  which  is  (on  the  average)  just 
noticeable.  The  measurement  of  both 
types  of  threshold  has  long  been  an  im- 
portant problem  in  psychology,  and  for 
their  measurement  elaborate  procedures 
and  precise  statistical  treatments  have  been 
devised.  All  these  methods  have  one  aim 
in  common:  They  try  to  draw  stable  con- 
clusions from  measurements  on  variable 
organisms.  These  conclusions  are  impor- 
tant to  science,  and  they  are  often  of  great 
practical  importance  as  well.  Some  people 
earn  their  living  measuring  other  people's 
thresholds. 

Suppose,  for  example,  a  man  is  applying 
for  a  job  as  a  radio  operator.  Obviously 
he  must  have  normal  hearing.  That  means 
that  his  absolute  threshold  for  sound  must 
not  be  significantly  above  normal.  Since 
speech  is  the  most  important  kind  of  sound 
he  must  hear,  we  might  say  that  he  must 
have  a  normal  absolute  threshold  for 
speech. 

Standardized  threshold  tests  for  speech 
were  developed  during  the  recent  war  as 
an  aid  in  the  rehabilitation  of  aural  casual- 
ties. Carefully  chosen  words  were  recorded 
on  phonogiaph  records,  and  by  means  of 
special  electrical  circuits  these  words  could 
be  reproduced  at  the  listener's  ear  in  graded 
steps  of  intensity.     The   problem   then   is 


(1)  to  determine  the  faintest  intensity  at 
which  the  listener  can  hear  the  speech  and 

(2)  to  compare  this  intensity  with  that  at 
which  a  normal  listener  hears  the  words. 
How  this  is  done  can  be  illustrated  with 
the  aid  of  Fig.  103.  We  shall  assume  that 
our  listener  has  a  fairly  large  hearing  loss, 
sufficient  to  cause  his  friends  to  raise  their 
voices. 

First  let  us  consider  the  threshold  of  the 
normal  listener.  We  find,  of  course,  that 
at  a  given  faint  intensity  he  hears  some  of 
the  words  and  not  others,  because  his  sensi- 
tivity varies.  If  we  raise  the  intensity 
slightly,  he  hears  a  larger  percentage  of  the 
words.  Finally,  if  we  make  the  speech  loud 
enough,  he  hears  all  the  words.  If,  there- 
fore, we  plot  the  percentage  of  the  words 
he  hears  at  each  level  of  intensity,  we  ob- 
tain the  curve  in  Fig.  103.  This  is  usually 
a  long  S-shaped  curve.  It  approximates,  in 
fact,  the  ogive  form  of  the  normal  distribu- 
tion curve,  the  form  which  shows  us,  not 
the  number  of  cases  for  each  value  of  the 
stimulus,  but  the  number  of  cases  up  to 
and  including  each  value  of  the  stimulus. 
It  is  a  cumulative  curve.  It  starts  at  zero 
per  cent  for  the  stimulus  that  is  always  in- 
effective and  reaches  100  per  cent  at  the 
stimulus  that  is  always  effective. 

Having  plotted  the  percentage  of  words 
which  the  listener  hears  at  successive  in- 
tensity levels,  we  are  ready  to  decide  what 
value  we  shall  call  the  threshold  for  speech. 
Both  common  sense  and  convention  tell  us 
that  the  threshold  ought  to  be  defined  as 
the  intensity  corresponding  to  the  50  per 
cent  point  on  the  curve.  This  is  the  speech 
intensity  that  will  be  heard  correctly  half 
the  time.  If  we  regard  the  listener's  re- 
sponses to  the  words  as  comprising  a  fre- 
quency distribution,  this  50  per  cent  point 
is  the  median  of  the  distribution. 

For  the  hard-of-hearing  listener  we  carry 


Thresholds  and  Psychometric  Functions 


265 


out  precisely  the  same  procedure.  We  plot 
a  curve  showinff  how  his  correct  responses 
depend  upon  intensity  and  we  pay  atten- 
tion to  the  50  per  cent  point.  Then,  since 
we  measure  hearing  loss  relative  to  the 
normal     threshold,     we    simply     take     the 


measure  absolute  thresholds,  but  similar 
(unctions  are  obtained  when  we  measure 
relative  thresholds  by  the  same  method. 

Thus  we  can  present  pairs  of  stinmli 
graded  as  to  the  difjerenre  between  them 
and  ask   the  subject  to  respond   by  saying 


100 
90 


t  70 
o 

•D 

sz 

P  50 

o 
5 

°  40  - 

<u 

oo 

I  30 
"^20^ 
10 
0 


- 

1 

1 

^^ 

' 

/ 

^ 

- 

~ 

/Normal 

ear 

/ 

/hard 

of- hearing  ear 

- 

J. 

/ 

- 

10 

i                   1 
20                 30 

40 

T 

50 

1 

60                  70 

/  ° 

Scale  of  hearing  loss 

/ 

4 

/  ^ 

/ 

/ 

^  ° 
o  ^ 

/      ^ 

/ 

-o£ 

y 

'                o 

1             ' 

1 

1 

^X 

113 

X 

1 

1 

1 

- 

10 


20 


30  40  50  60 

Relative  intensity  of  speech  in  decibels 


70 


80 


90 


FIGURE    103.       PSYCHOAfETRIC    FUNCTIONS    FOR    ABSOLUTE    THRESHOLDS 

The  two  curves  (psychometric  functions)  show  how  tlie  percentage  of  words  heard  correctly  increases  as 
the  intensity  level  of  the  speech  (in  decibels)  is  raised.  The  intensity  at  which  half  the  words  are  heard  cor- 
rectly is  defined  as  the  absolute  threshold.  Amount  of  hearing  loss  is  the  difference  between  the  threshold 
of  the  patient  and  the  threshold  of  a  normal  ear. 


spread  between  the  two  50  per  cent  points 
as  the  quantitative  measure  of  hearing 
loss.  In  the  example  before  us  this  loss  is 
45  decibels,  a  large  enough  loss  to  call  for 
a  hearing  aid.  (For  a  fuller  account  of  the 
intelligibility  of  speech,  see  pp.  345-349.) 
The  S-shaped  curves  in  Fig.  103  are 
known  as  psychometric  junctions.  Curves 
of  this  sort  are  obtained  whenever  we  pre- 
sent carefully  graded  stimuli  and  record 
the  frequencies  with  which  a  subject  re- 
sponds to  them.     The  curves  in  Fig.   103 


whether  the  second  stimulus  in  each  pair  is 
greater  or  less  than  the  first.  A\'e  should 
then  obtain  two  psychometric  functions 
(one  for  judgments  greater,  one  for  judg- 
ments less).  The  two  functions  would  cross 
each  other  at  their  50  per  cent  points. 
This  aossing  would  usually  fall  near-  die 
value  corresponding  to  no  physical  differ- 
ence between  the  stimuli.  On  diese  two 
functions  we  should  then  have  to  decide 
die  value  of  the  differential  direshold.  ob- 
viouslv  not  the  50  per  cent  point.     Here 


266 


Sensation  and  Psychological  Measurement 


convention  tells  us  we  should  choose  the 
value  of  the  physical  difference  which  gives 
judgments  of  greater  (or  of  less)  75  per  cent 
of  the  time.  This  is  reasonable  enough  if 
you  think  about  it.    The  75  per  cent  point 


pair  is  higher  or  lower  than  the  first  tone. 
The  percentages  of  correct  judgments  may 
then  be  tabulated  and  plotted  as  in  Fig. 
104.  There  we  see  plots  for  the  average 
of  the  group  of  95  students  and  plots  for 


-15 


-10  -5  0  +5  +10 

Difference  in  cycles  per  second  between  first  and  second  tone 


+  15 


FIGURE    104.      PSYCHOMETRIC   FUNCTIONS    FOR   DIFFERENTIAL   THRESHOLDS 

Psychometric  functions  show  how  the  correctness  of  pitch  judgments  depends  upon  the  size  of  the  stim- 
ulus difference.  The  dotted  curves  represent  the  composite  scores  made  by  95  high  school  students  who 
took  the  Seashore  Test  for  Musical  Talent.  The  solid  curves  are  for  the  group  of  11  students  who  scored 
highest  on  the  test.  The  curves  for  the  judgments  higher  and  lower  cross  at  the  50  per  cent  point,  which 
coincides  with  zero  difference  between  the  two  tones  presented  as  stimuli.  Thus,  when  there  was  no  dif- 
ference to  be  heard,  the  judgments  followed  the  chance  expectancy  of  50-50. 


is  the  midpoint  of  the  distribution  of  judg- 
ments falling  on  one  side  of  equality. 

Figure  104  shows  how  all  this  works  out 
in  a  practical  situation.  A  group  of  95 
high  school  students  was  given  one  of  the 
Seashore  Tests  designed  to  gauge  musical 
ability.  This  test  calls  for  the  discrimina- 
tion of  small  differences  in  pitch.  Pairs 
of  tones  are  sounded,  and  the  listener  tries 
to  tell   whether   the   second   tone  of  each 


the  average  of  the  1 1  best  students.  These 
1 1  listeners  are  clearly  better  at  discrimi- 
nating differences  in  pitch  than  the  group 
as  a  whole.  If  we  measure  pitch  discrimi- 
nation as  the  difference  in  frequency  (cycles 
of  the  tonal  stimulus  per  second)  correctly 
noticed  75  per  cent  of  the  time,  we  find 
that  the  group  as  a  whole  has  an  average 
differential  threshold  equal  to  7  cycles  per 
second.     For  the  1 1  best  listeners  the  aver 


Psychometric  Functions  and  Weber  Fractions 


267 


age  is  only  2  cycles  per  second.  On  the 
average  these  1 1  people  could  tell  the  dif- 
ference between  a  tone  of  1000  cycles  and 
a  tone  of  1002  cycles— which  is  very  good 
discrimination  indeed. 

Pitch  discrimination  as  good  as  this  is  a 
necessary  asset  to  a  musician.  But  a  word 
of  caution  is  in  order  here.  Although  good 
pitch  discrimination  is  necessary,  the  fact 
of  having  it  does  not  make  a  person  a  musi- 
cian. Other  important  talents  are  called 
for  in  addition.  Pitch  discrimination  is  to 
the  musician  what  visual  acuity  is  to  the 
artist.  It  is  what  is  called  a  necessary  but 
not  a  sufficient  condition  for  success. 

THE    WEBER    FRACTION 

There  is  another  important  aspect  of  the 
problem  of  differential  thresholds  that  we 
must  consider.  It  is  important  because  it 
is  a  law  of  relativity  in  psychology.  This 
law  says  that  in  order  for  it  to  be  perceived 
the  increase  that  must  be  made  in  a  stim- 
ulus depends  upon  the  amount  that  is  al- 
ready there.  If  to  two  lighted  candles  in  a 
room  a  third  is  added,  there  is  a  greater 
increase  in  the  sensed  illumination  than 
there  would  be  if  a  twenty-first  candle  were 
added  to  twenty.  The  additional  light  has 
more  effect  when  added  to  a  lesser  illumi- 
nation. A  cough  counts  for  more  in 
church  than  in  the  subway.  In  other 
words,  the  differential  threshold  for  in- 
tensity gets  larger  as  the  intensity  gets 
greater. 

It  is  usual  to  measure  relative  sensitivity 
by  taking  the  ratio  of  the  differential 
threshold,  which  we  may  call  A/,  to  the 
total  intensity  at  which  the  threshold  was 
obtained,  which  we  may  call  /.  This  ratio 
A///  is  called  the  Weber  ratio  or  the  Weber 
fraction,  because  a  century  ago  the  physiol- 
ogist,   E.    H.    Weber,    thought    that    it   re- 


mained constant  at  different  inten.sities. 
Modern  research  has  corrected  his  view. 
Figure  105  shows  the  typical  form  of  the 
Weber  function,  that  is,  the  way  A/// 
changes  with  /.  Although  Weber  held  that 
such  a  function  would  be  a  horizontal 
straight  line,  actually  the  Weber  fiinciioii 


2  3         4  5         6         7  8 

/  in  logarithmic  units 

FIGURE    105.      TYPICAL   WEBER  FUNCTIONS   FOR 
VISION   AND   HEARING 

The  curves  show  the  relation  between  the  \\'el)er 
fraction  A///,  and  the  intensity  of  the  stimulus,  /. 
Log  7  =  0  =  absolute  threshold.  On  the  intensity 
scale  each  unit  represents  a  tenfold  increase  in 
energy.  White  noise  is  a  purely  random  mixture 
of  all  frequencies.  It  sounds  like  a  sustained  Sh-h-h. 
It  is  called  white  because,  like  white  light,  it  is 
composed  of  all  the  perceptible  frequencies  acting 
simultaneously.  [Data  from  G.  A.  Miller,  /.  acousl. 
Soc.  Amer.,  1947,  19,  609-619.]  The  measurement"; 
for  white  light  were  made  with  a  small  patch  of 
light  (visual  angle  =  28  minutes  of  arc)  falling  on 
the  retinal  fovea. 

is,  as  the  figure  shows,  a  curve.  The  \alue 
of  the  Weber  fraction  first  decreases  rapidly 
as  the  intensity  increases  and  then  more 
slowly  until  it  reaches  a  minimal  value. 
Thereafter,  it  may  remain  constant,  or  oc- 
casionally it  may  again  increase  slightly. 

In  terms  of  the  Weber  fractions,  it  is  pos- 
sible to  compare  one  sense  with  another 
with  respect  to  differential  sensitivity. 
Since  the  fraction  vaiies  within  a  single 
sense,  we  must  choose  for  each  sense  some 


268 


Sensation  and  Psychological  Measurement 


one  representative  value,  and  it  is  obvious 
that  the  minimal  fractions  best  lend  them- 
selves to  comparison,  since  each  minimal 
fraction  shows  the  maximal  sensitivity  of 
which  that  sense  is  capable.    In  Table  XVI 

TABLE  XVI 

Minimal  Weber  Fractions 

For  all  cases  below,  except  tones  and  smells,  the 
Weber  fraction  has  a  minimal  value  in  the  middle 
range  of  intensities.  The  minimal  values  for  tone 
and  smell  are  for  the  maximal  intensities  after  the 
Weber  function  has  leveled  off.  Although  each  of  the 
different  values  would  be  somewhat  altered  by  a 
different  choice  of  experimental  conditions,  the  differ- 
ence between  Ijj  and  \i  is  so  very  great  that  there 
can  be  no  doubt  about  the  general  fact  that  different 
sensory  mechanisms  differ  significantly  in  sensitivity. 

Weber  Weber 

Ratio  Fraction 
Deep   pressure,    from    skin    and   subcutaneous 

tissue,  at  about  400  grams  0.013  1^7 

Visual  brightness,  at  about  1000  photons  0.016  Hs 

Lifted  weights,  at  about  300  grams  0.019  }i3 
Tone,  for  1000  cycles  per  second,  at  about  100 

db  above  the  absolute  threshold  0.088  Hi 

Smell,  for  rubber,  at  about  200  olfacties  0. 104  Mo 
Cutaneous   pressure,    on   an    isolated   spot,   at 

about  5  grams  per  mm  0. 136  H 
Taste,  for  saline  solution,  at  about  3  moles  per 

liter  concentration  0.200  '/i 

these  minimal  values  are  listed  for  seven 
well-established  cases.  It  is  true  that  these 
figures  apply  only  to  particular  experimen- 
tal conditions;  nevertheless,  the  general  re- 
lation of  the  senses  is  clear.  Tonal  sensi- 
tivity is  less  than  visual.  The  skin  is  not 
so  sensitive  to  a  difference  in  pressure  as 
the  muscles  to  a  difference  of  lifted  weight. 
Despite  the  fact  that  for  a  given  sense 
the  Weber  fraction  is  only  approximately 
constant,  we  must  not  lose  sight  of  the 
fact  that  the  Weber  function  is  a  general 
statement  that  relativity  is  approximated 
in  the  world  of  sensory  intensities.  The 
principle  of  relativity  signifies  that  a  little 
thing  means  more   to  another  little   thing 


than  it  does  to  a  big  thing.  A  dollar  mean;; 
more  in  poverty  than  it  does  in  wealth, 
whereas  an  error  of  an  inch  in  the  length 
of  the  equator  matters  less  than  an  error 
of  an  inch  in  the  fit  of  a  shoe.  Just  so  the 
Weber  function  means  that  differences  that 
seem  large  at  small  intensities  become  quite 
unnoticeable  at  large  intensities. 

REFERENCES 

1.  liarlley,  S.  H.  ]'ision.  New  York:  Van  Nos- 
trand,  1941.     Chap.  2. 

A  discussion  of  the  principal  facts  of  bright- 
ness discrimination  with  emphasis  on  the  un- 
derlying  physiological   processes. 

2.  Boring,  E.  G.  The  physical  dimensions  of  con- 
sciousness. New  York:  Appleton-Century,  193.S. 
Chaps.  2,  3  and  6. 

A  systematic  discussion  of  the  sensory  at- 
tributes of  intensity  and  quality  in  terms  of 
a  physical  theory  of  mind. 

3.  Boring,  E.  G.  Sensation  and  perception  in  the 
history  of  experimental  psychology.  New  York: 
Appleton-Century,  1942.     Chap.  1. 

Chapter  1  summarizes  the  work  and  thought 
on  sensation  and  perception  during  the  last 
three  centtiries. 

4.  Guilford,  J.  P.  Psychometric  methods.  New 
York:   McGraw-Hill,  1936.     Chaps.  2  to  6. 

A  comprehensive  treatment  of  the  classical 
psychophysical  methods  and  their  statistical 
bases. 

5.  Stevens,  S.  S.,  and  Davis,  H.  Hearing:  its  psy- 
chology and  physiology.  New  York:  Wiley, 
1938.     Chaps.  2  to  5. 

A  systematic  analysis  of  the  facts  of  auditory 
sensation  with  respect  to  pitch,  loudness  anti 
the  other  tonal  attributes. 

6.  Troland,  L.  T.  The  principles  of  psycho- 
physiology.  New  York:  Van  Nostrand,  1930. 
Vol.  2,  especially  sections  53,  54  and  61. 

A  systematic  account  of  the  psychophysical 
facts  of  all  the  senses  with  especial  emphasis  on 


CHAPTER 


12 


Color 


WHAT  the  eye  sees  is  color— greens, 
oranges,  pinks,  grays,  whites.  The 
location  ot  the  seen  colors  in  space  and  the 
patterns  that  make  up  the  perceived  visual 
field  are  problems  of  visual  space  percep- 
tion with  which  the  next  chapter  deals— 
the  how  and  why  of  shape  and  size,  of  flat 
and  solid,  of  near  and  far.  This  chapter  is 
about  the  visual  qualities,  the  relationships 
and  laws  of  colors. 

CHARACT.ERISTICS     OF     COLORS 

We  begin  with  the  appearance  of  col- 
ors, what  can  be  said  about  color  without 
reference  to  its  stimuli  or  to  the  conditions 
of  its  arousal. 

Color  Names 

An  attempt  to  catalogue  all  the  various 
color  qualities  at  first  appears  impossible. 
When  we  think  of  the  many  lavenders, 
pinks,  purples,  reds,  oranges,  yellows, 
browns,  tans,  greens,  blues,  grays,  blacks 
and  whites  of  our  everyday  experience,  the 
accepted  estimates  of  100,000  to  300,000 
discriminatively  different  colors  does  not 
seem  too  high.    Colors  were  first  named  by 


reference  to  paiticular  objects,  and  many 
such  terms  are  still  retained  in  our  every- 
day speech,  for  instance,  orange,  violet, 
olive,  straw.  Others  have  lost  their  object 
reference  and  now  are  simply  color  names, 
as  purple,  scarlet,  sepia,  maroon,  crimson, 
azure,  taupe.  In  addition,  it  has  been  the 
custom  for  a  long  time  to  invent  color 
names,  particularly  for  clothing,  and  such 
names  have  changed  with  the  styles  of  the 
time.  In  the  sixteenth  century,  for  in- 
stance, French  women  wore  colors  called 
rat  color,  widow's  joy,  envenomed  monkey 
and  chimney  sweep.  The  eighteenth  cen- 
tury produced  rcish  tears,  Paris  mud,  stifled 
sigh  in  France  and  red-hot  bullets  and 
smoke  of  the  Camp  of  St.  Roche  in  Eng- 
land. Only  yesterday  (1930)  they  could  be 
matched  with  folly,  lucky  stone,  elephant's 
breath  and  in  1946  with  sun  love,  town 
blond  and  cocoblush  or  J'irginia  turf, 
radar  blue  and  avenue  gray.  Obviouslv. 
such  fantastic  names  have  no  ^alue  for 
scientific  purposes,  though  the  textile  in- 
dustry has  systematized  them  for  sales  pro- 
motion. 

The   most   comprehensive   dictionary   of 
color  gives  over  seven  thousand  samples  of 


This  chapter  was  prepared  by  Forrest  L.  Dimmick  of  the  U.  S.  Naval  Medical  Research 
Laboratory  at  New  London. 

The  opinions  or  assertions  contained  in  this  chapter  are  the  private  ones  of  the  collabo- 
rator and  the  editors  and  are  not  to  be  construed  as  official  or  reflecting  the  views  of  the 
Navy  Department  or  the  Naval  Service  at  large. 

269 


270 


Co/or 


colors  but  finds  only  about  half  that  many 
color  names,  some  of  them  repetitions  and 
others  obsolete.  An  attempt  has  been 
made  by  the  National  Bureau  of  Standards 
and  the  Inter-Society  Color  Council  to 
standardize  and  simplify  color  names. 
They  have  found  that  the  long  list  of  color 
names  commonly  used  can  be  reduced  to 
twelve  applied  singly  (blue)  or  in  combina- 
tion (bluish  green)  with  certain  modifiers 
(light  blue-green).     (See  Table  XVII.) 

TABLE  XVII 

Color  Names 

The  diagram  shows  how  a  tew  color  names  and 
modifiers  can  be  combined  to  represent  a  large  range 
of  colors  in  the  Inter-Society  Color  Council  and  the 
National  Bureau  of  Standards  system  of  color  names. 
The  five  rows  give  alternative  names  for  five  different 
greens. 

Green 


Greenish 
White 

Very 
Pale 
Green 

Very 
Light 
Green 

Very 

Brilliant 

Green 

Light 

Greenish 

Gray 

Pale 
Green 

Light 
Green 

Brilliant 
Green 

Medium 
Greenish 
Gray 

Weak 
Green 

Moderate 
Green 

Strong 
Green 

Vivid 
Green 

Dark 

Greenish 

Gray 

Dusky 
Green 

Dark 
Green 

Deep 
Green 

Greenish 
Black 

Very 

Dusky 

Green 

Very 
Dark 
Green 

Very 
Deep 
Green 

Unique  Colors 

It  is  not  necessary  to  have  a  separate 
name  for  every  color,  because  colors  can  be 
grouped  according  to  their  resemblances  to 
a    few   outstanding   or   unique    colors.      A 


unique  color  is  a  color  that  is  describablc 
in  terms  of  itself  alone,  that  is  to  say,  it 
must  be  displayed  or  demonstrated.  There 
are  seven  such  unique  colors,  namely.  Red, 
Yellow,  Green,  Blue,  White,  Gray  and  Black. 
No  one  of  the  unique  colors  looks  like  or 
implies  the  existence  of  any  other  unique- 
color,  but  all  non-unique  colors  can  be  re- 
ferred to  two  or  more  of  the  unique  colors 
because  they  resemble  the  unique  colors. 
Thus  non-unique  colors  fall  into  series  of 
gradations  from  one  unique  color  to  an- 
other. For  example,  purple  refers  to  a 
group  of  colors  that  look  both  reddish  and 
bluish.  There  are  bluish  reds  (purples), 
blue-reds  and  reddish  blues  (violets).  Some 
investigators  use  the  terms  purplish  red, 
reddish  purple,  purple  and  bluish  purple, 
as  well  as  red-violet,  violet  and  blue-violet. 
Any  color  in  the  group  can  be  described 
by  giving  its  relative  redness  and  blueness. 
Careful  experimental  observations  have  es- 
tablished the  fact  that  the  seveyi  unique 
qualities  mentioned  above  are  necessmy 
and  sufficient  for  precise  description  of  all 
visible  colors. 

The  Color  Equation 

The  fact  that  every  color  can  be  de- 
scribed precisely  by  stating  its  likenesses  to 
the  several  unique  colors  can  be  expressed 
in  the  equation: 

Color  =  (Red  or  Green)  +  (Yellow  or 
Blue)  +  (White  or  Black)  -f  Gray 

or,  more  simply, 

C  =  {R,  G)  +  (7,  B)  +  {Wh,  Bk)  +  Gy 

The  equation  pairs  six  unique  colors,  ex- 
pressing the  fact  that  there  are  no  red- 
green,  no  blue-yellow  and,  as  a  matter  ol 
fact,  no  black-white  colors.  (The  interme 
diate  colors,  from  black  to  white,  are  mix 


The  Color  Equation 


271 


lures  of  black  or  white  with  the  gray  color 
in  various  proportions,)  This  fact  is  the 
basis  of  the  complementarisrn  of  colors,  a 
relationship  which,  as  we  shall  see,  appears 
in  several  other  ways.  There  are  no  colors 
which  look  reddish  green  or  bluish  yellow, 
although  there  are  reddish  yellows,  bluish 
greens  and  reddish  blues  (Fig.  106).  That 
is  why  the  equation  for  color  reduces  to 
lour  terms  instead  of  seven. 


Unique  colors.  There  are  seven  of 
them,  R  (red),  Y  (yellow;,  G  Cgrcen), 
B  (blue),  Wh  (white),  Bk  (black)  and 
(jy  (gray).  They  are  unique  because 
they  are  the  points  of  orientation  for  all 
the  other  colors  and  no  one  resembles 
any  other  one.     They  are  also  simplex. 

Duplex  colors.  They  lie  on  the  color 
series  connecting  any  two  unique  colors. 
There  are  eighteen  such  series: 


Red 


Carmine 


Purple 


Violet 


Indigo 


FIGURE    106.      DUPLEX   SERIES   OF   COLORS 


Blue 


RED 



" 

■■ 

BLUE                       'M 

The  second  point  about  the  color  equa- 
tion is  that  it  shows  how  many  different 
ways  colors  can  vary  in  their  relations  to 
one  another.  The  unique  colors  are  sim- 
ple and  points  of  reference,  for  all  the 
other  colors  are  designated  by  reference  to 
them.  Then  there  are  duplex  colors,  like 
the  carmines,  purples,  violets  and  indigos 
of  Fig.  106,  which  form  a  series  between 
unique  red  and  unique  blue.  Unique  red 
is  an  end  point  of  five  such  duplex  series, 
red-blue,  red-yellow,  red-white,  red-gray 
and  red-black.  For  duplex  colors  two  of  the 
four  terms  in  the  color  formula  are'  equal 
to  zero  and  disappear,  and  the  other  two 
terms  characterize  the  color.  When  there 
are  three  terms  used  in  the  color  equation 
the  color  is  triplex,  like  a  light  purple 
(red  -f  blue  -f  white)  or  a  grayish  orange 
(red  -f  yellow  -f  gray).  The  great  majority 
of  colors  are,  however,  quadruplex,  like  a 
light  pastel  jade  (green  -f  blue  +  white  + 
gray). 

We  shall  do  well  to  sunimari/e  these  rela- 
tionships. 


1. 

RY 

7. 

G-VVh 

13. 

R-Gy 

2. 

Y-G 

8. 

B-Wh 

14. 

Y-Gy 

3. 

G-B 

9. 

R-Bk 

15. 

G-Gy 

4. 

BR 

10. 

Y-Bk 

16. 

B-Gy 

5. 

R-Wh 

11. 

G-Bk 

17. 

Wh-Gy 

6. 

Y-Wh 

12. 

B-Bk 

18. 

Bk-Gy 

In  these  groups  what  are  sometimes 
called  'good  hues'  appear  in  series  1-4. 
The  bright  colors  are  in  series  5-8,  the 
dark  colors  in  series  9-12,  the  poorly  sat- 
urated or  grayish  colors  in  series  13-16 
and  the  achromatic  colors  (the  whites, 
grays  and  blacks)  in  series  17  and  18. 
These  series  are  the  lines  in  Figs.  107, 
108,  109  and  110. 

Triplex  colors.  A  great  manv  colors 
have  only  one  term  in  the  color  equa- 
tion missing,  being  related  to  the  other 
three  unique  colors.  Such  colors  lie  in 
the  triangular  spaces  of  Figs.  107,  108, 
109  and  110.  There  are  twenty  such 
triangles: 

1.  R-Y-Wh  4.  Y-G-Wh  7.  G-B-Wh 

2.  R-Y-Bk  5.   Y-G-Bk  8.   G-B-Bk 

3.  R-Y-Gy  6.   Y-G-Gx  9.   G-BG^ 


272 


Color 


]().  B-R-Wh  14.   Y-Gy-]V,  18.   Y-Gy-Bk 

11.  B-R-Bk  15.   G-Gy-Wli  19.   G-Gy-Bk 

12.  B-R-Gy  16.  5-G>i-Tl7i  20.  B-Gy-Bk 

13.  i?-G)'-Ty/z  17.  R-Gy-Bk 

See  the  triplex  series  from  orange  to 
white  in  Fig.  111. 

Quadruplex  colors.  They  represent 
the  great  majority  of  colors  which  have 
to  have  positive  specification  in  respect 
of  all  four  terms  of  the  color  formula. 
There  are  eight  such  combinations: 


WHITE 


Straw 


YELLOW 


1.  R-Y-Wh-Gy 

2.  R-Y-Bk-Gy 

3.  Y-G-Wh-Gy 

4.  Y-G-Bk-Gy 


5.  G-B-Wh-Gy 

6.  G-B-Bk-Gy 

7.  B-R-Wh-Gy 

8.  B-R-Bk-Gy 


The  Color  Pyramid 

The  facts  expressed  in  the  color  formula 
can  be  represented  in  a  spatial  schema.  If 
we  put  the  unique  colors  at  points  and  the 
various  qualitative  series  on  straight  lines, 
the  framework  of  our  structure  builds  it- 
self. For  a  start  let  us  take  the  four  points 
and  four  series  representing  red,  yellow, 
green  and  blue.  The  resulting  shape  is  a 
square  with  each  one  of  the  four  colors  at  a 


RED 


Orange 


YELLOW 


Chartreuse 


Emerald 


BLUE  Turquoise  GREEN 

FIGURE    107.       UNIQUE    AND    COMPLEX    COLORS 

Schematic  arrangement  of  the  five  unique  colors, 
red,  yellow,  green,  blue  and  gray,  showing  examples 
of  duplex  colors  lying  along  the  straight  lines  con- 
necting the  uniques.  Triplex  colors  lie  within  the 
four  triangular  spates. 


BLUE  Navy  BLACK 

FIGURE    108.       UNIQUE   AND    COMPLEX    COLORS 

Schematic  arrangement  of  the  five  uniciue  colors, 
white,  gray,  black,  yellow  and  blue,  with  duplex 
colors  along  the  lines,  and  triplex  colors  in  between. 


RED 


WHITE 


BLACK  GREEN 

FIGURE    109.       UNIQUE    AND    COMPLEX    COLORS 

Schematic  arrangement  of  the  five  unique  colors, 
white,  gray,  black,  red  and  green,  with  duplex  col- 
ors along  the  lines,  and  triplex  colors  in  between. 

corner  (Fig.  107).  If  we  had  taken  blue, 
white,  yellow  and  black,  or  red,  white, 
green  and  black,  similar  squares  would 
have  resulted  (Figs.  108,  109).  Gray  goes 
in  the  middle  of  each  of  these  squares  be- 
cause of  the  complementariness  of  the  re- 
maining three  pairs.  You  cannot  go  from 
red  to  green,  from  yellow  to  blue,  or  from 
white  to  black  without  passing  through 
gray. 

To  bring  these  three  squares  together,  as 
we  must,  since  we  have  in  all  only  six 
corner  points,  we  can  set  white  and  black 


The  Color  Pyramid 


273 


respectively  above  and  below  the  iniddlc; 
of  the  red-ycllow-grecn-bluc  square  and 
connect  them  with  its  corners.  The  identi- 
cal grays  at  the  middle  ol  cacli  scjuare  coin- 


WHITE 


FIGURE    110 


cide  in  the  middle  of  the  solid  figure 
which  results.  This  figure  is  a  double 
square  pyramid  or  octahedron.  Gray,  as 
we  have  said,  stands  at  one  end  of  series 
that  run  to  all  the  other  unique  colors.  Its 
place,  obviously,  is  at  the  center  of  the 
system.     (See  Fig.  110.) 

The  duplex  colors  lie  on   the  eighteen 


lines  of  the  pyramid,  the  lines  whirli  form 
the  edges,  and  the  six  lines  which  radiate 
from  gray.  Figure  112  is  one  of  the  eight 
tetrahedrons  which  make  up  the  color 
pyramid.        This      tetrahedron     has     four 


FIGURli    112.      lETRAHF.DRON   FROM  COU-K   T'S  RANfll) 

One  of  tlie  eight  tetrahedrons  in  the  color  p\ra- 
mid.  All  the  colors  in  this  tetrahedron  may  be 
specified  by  the  equation  Red  +  Yellow  +  White  + 
Gray  =  C. 

unique  colors  at  its  four  corners,  six  series 
of  duplex  colors  along  its  six  edges,  four 
sets  of  triplex  colors  in  its  four  triangular 
faces  and  all  the  red-yellow-white-gray 
quadruplex  colors  inside  its  volume.  Sal- 
mon and  pink  (see  Fig.  Ill)  would  lie 
near  the  top  of  the  front  face  (Fig.  112). 

The  color  pyramid  and  its  color  equation 
represent    every    knoAvn    or   hypothetically 


orange                                                                                                        Salmon 

White 

;;:;:;|re;D  ■  ^       ^_______^j^^ 

WHITE 

FIGURE    111.      TRIPLEX  SERIES   OF  COLORS  WITH  WHITE   CONTENT  VARIED 

The  diagram  shows  an  orange  getting  whiter.     The  proportion  of  yellow  to  red  remains  the  same,  btit 
!hc  ]>ioportion  of  while  to  orange  (vellow-and-red)  increases. 


274 


Color 


visible  color  quality.  The  only  oilier  ways 
in  which  visual  appearance  can  be  altered 
are  by  putting  cjualities  from  the  pyramid 
into  a  spatial  pattern  or  by  making  them 
change  in  time  or  by  both  together  or  by 
presenting  simultaneously  one  color  to  one 
eye  and  a  different  color  to  the  other  eye. 
In  the  last  case  avc  sometimes  see  luster. 

Chromatic  and  Achromatic  Colors 

This  is  the  newer  \  iew  of  the  classifica- 
lion  of  colors.      The  older  and  more  con- 


WHITE 


GRAY 


YELLOW 


BLACK 

IIGURE     113.        DIMKNSIONS    f)F    TUK    COI  OR    FIGURE 
SHOWING    HL'E,    SATl'RATION    AND    BRIGHTNESS 

ventional  ^  iew  separates  white,  gray  and 
black  from  the  rainbow  colors,  labeling  the 
former  achromatic  or  'uncolored'  colors 
and  the  latter  chromatic  or  'colored'  colors. 
Hue,  saturation  and  brightness  are  the 
conventional  terms  which  are  used  to  char- 
acterize the  attributes  of  colors.  Again  wc 
have  here  simply  a  different  set  of  terms, 
not  any  new  facts.    (Sec  I'ig.  1  K^.) 


Brightness  (sometimes  called  ligfitness, 
tint  or  value)  refers  to  variations  along  the 
achromatic  scale,  black-to-gray-to-white. 
Since  other  colors  also  show  gradations 
toward  white  and  toward  black,  a  chromatic 
color  may  also  ^ary  in  brightness. 

Saturation  is  represented  most  simply  by 
a  series  of  gradations  from  one  of  the  chro- 
matic colors,  like  red,  to  one  of  the  achro- 
matic colors,  like  gray.  In  the  conven- 
tional terminology,  the  series  representing 
change  of  saturation  would  be  all  the 
radial  lines  that  could  be  drawn  from 
gray  to  the  colors  on  the  outside  of  the 
color  square  of  Fig.  107.  The  newer  view 
puts  gray  at  the  middle  of  the  color  pyramid. 
All  radial  lines  that  go  from  it  to  any  color 
in  the  surface  of  the  pyramid  are  series 
which  show  increasing  richness  of  the  chro- 
matic or  achromatic  color  to^vard  which 
the  line  leads  and  diminishing  grayness. 
This  view  really  makes  the  pyramid  into  a 
double  hedgehog,  with  saturation  lines 
sticking  ovit  from  gray  towaicl  the  other 
colors  in  all  directions. 

Hue,  in  the  older  system,  refers  specifi- 
cally to  the  several  'chromatic'  colors— red, 
yellow,  green,  blue  and  their  intermedi- 
ates. 

THE    STIMULUS    TO    COLOR 

It  is  not  enough  to  know  the  number  of 
color  qualities  and  their  relations  to  one 
another.  We  must  know  also  how  the 
colors  are  produced,  the  nature  of  their 
physical  stimuli. 

Nature  of  the  Stimulus 

The  stimulus  to  color  is  light.  When 
electric  charges  are  mo\ing  through  space 
at  a  iinifonn  rate,  they  release  radiant 
rneigx   in  the  form  of  oscillations  in  imen- 


The  Stimulus  to  Co/or 


275 


sily  of  the  elcctroinagnelic  field  wliciievcr 
their  uniform  motion  is  altered.  This 
radiant  energy  is  light.  lis  visible  aspects 
are  related  to  three  important  character- 
istics of  these  electromagnetic  oscillations. 
(See  Fig.  114.) 

The  most  fundamental  characteristic  is 
the  distance  from  pulse  to  pulse  of  the 
vibration,  tlie  luoTr  l('n<>;lli  of  light.     Sudi 


wave  lengili  falls  in  a  different  jjlace.  J  bus 
the  heterogeneous  light  is  broken  up  into 
its  homogeneous  (oniponents.  What  you 
see,  of  course,  is  the  spectrum,  a  brilliant 
band  of  colors  shiinng  out  in  the  dark  in 
which  you  are  working.  Newton  called 
this  apparition  in  the  dark  a  spectrum 
because  of  its  specterlike  appearance.  It 
is  from  the  spec  trum  that  the  wave  lengths 


18M 

miles 

i 


y,        !/,o       33 

mile      mile     feet 

t  t  t 


1 

inch 

t 


16  millionths  inch  — i 
32  millionths  inch 
1  thousandth 
inch 
t 


Transoceanic   Broad    Short 
cast     wave 


Ultra 
short 
waves 


Radiation  used  in 
radio  communication 


Infra-red  _ 

radiation 


800  mn 


5  ten- 

millionths 

inch 

i 


400 
ilhonths 
inch 


4ten- 

trillionths 

inch 

♦ 


/ 

\ 

1 

^ 

T3 

on 

"    Orange 

"     Yellow 

Green 

Blue 
' '      Violet 

Radium/'' 
radiation 

j^ X-ray      ^ 

radiation 

\ 
\ 


V  ^400  m/i 


Cosmic  rays 
radiation 


FIGURK    114.      THE  R.\NGE   OF   ELECTROMAGNETIC   RADIATIONS 

The  range  is  so  Avide  that  this  diagram  had  to  be  plotted  on  a  logarithmic  scale  in  order  to  place  it  on 
this  page.     Note  the  small  portion  of  the  spectrum  in  which  visible  light  is  radiated. 


wave  lengths  cover  a  wide  range,  from 
tJiose  measured  in  units  of  10-trillionths  of 
an  inch  to  those  many  miles  long.  Light 
waves  are  among  the  shorter  ones,  lying 
between  16-  and  32-miIlionths  of  an  inch 
or,  in  the  more  usual  notation,  between 
400  and  800  millimicrons  (millionths  of  a 
millimeter,  abbreviated  m/x).  A  particular 
beam  of  light  may  consist  of  a  set  of  waves 
that  are  all  of  a  single  length  (homogene- 
ous), of  several  wave  lengths  (heterogene- 
ous) or  of  all  wave  lengths  between  the 
visible  limits  (heterogeneous). 

It  was  in  1666  that  Isaac  Newton  dis- 
covered that  a  beam  of  heterogeneous 
light  ('white'  light)  upon  passing  through 
a  triangular  glass  prism  is  dispersed  or 
spread  out  into  a  wide  band  so  that  every 


of  light  are  determined.  You  never  see 
wave  lengths  directly.  They  have  to  be 
computed  froin  physical  measurements. 

In  addition  to  wave  length  and  homo- 
geneity, radiant  energy  varies  also  in 
amount  or  intensity.  The  intensity  of  the 
color  stimulus  is  always  proportional  to 
the  rate  at  which  energy  comes  from  a  given 
surface.  You  measure  amount  of  radiant 
energy  to  measure  the  intensity  of  the 
stimulus. 

The  physical  stimulus  may  vary.  then. 
(1)  in  iL'ove  length,  (2)  in  homogeneity 
(number  of  wave  lengths  combined)  and 
(3)  in  intensity  of  luminous  energy.  ^Ve 
must  examine  the  dependence  of  the  vari- 
ous characteristics  of  color  upon  these 
physical  properties  of  the  stimulus. 


276 


Color 


Dependence  of  Color  on  Its  Stimulus 

There  is  a  fairly  simple  and  consistent 
correlation  between  wave  length  and  the 
first  half  of  the  color  equation,  that  is, 
red,  yellow,  gieen  and  blue  (the  chromatic 
colors,  the  hues).  The  long  waves  of  the 
spectrum  beginning  at  700  millimicrons 
are  seen  as  red  tinged  with  yellow.  As 
^v■e  go  from  that  point  toward  the  shorter 
wave  lengths,   colors   become   more   yellow 


wave  length.  At  the  red  end  there  is  no 
change  of  color  toward  yellow  until  you 
get  below  635  millimicrons.  The  colors 
there  get  less  black,  less  gray,  more  red,  but 
not  yellower.  Between  that  point  and  450 
millimicrons  the  difference  in  wave  length 
necessary  to  get  a  noticeable  change  in 
color  varies  aroimd  2  millimicrons.  (See 
Fig.  116.)  Differential  sensitivity  is  great- 
est  near   vellow   and   blue   and   least   near 


Unique     Unique 
blue         green 

i     li   . 


Unique 
yellow 

JL 


J L 


J L 


I  510 
500 


580 


600 


700 


_>>^ 


800  m/i 

/ 


Violets 


Blue- 
greens 

FIGURE 


15- 


Yellow-  Oranges 

greens 

RELATION   OF  HUE  TO  WAVE   LENGTH 


\\;i\e  leiigihs  of  spcclral  light  indicated  in  millimicrons.  Duplex  colors  shown  below  the  line.  Tlie 
lliree  uni(|iie  colors  which  lie  in  the  spectrum  are  shown  at  arrows  above  the  line,  but  unique  red  is 
:iuiispectral   and   does  not  show.     Spectral   "red"   (about  670-800  m^)  is  a  slightly  yellowish  (duplex)  red. 


and  less  red,  passing  through  the  red-yelloW 
series  until  unique  yellow  is  reached  at 
about  580  millimicrons.  Between  that 
point  and  green  at  510  millimicrons  lie 
the  greenish  yellows  and  yellow-greens. 
Between  510  and  476  millimicrons  is  the 
series  from  green  to  blue.  Shorter  wave 
lengths,  from  476  millimicrons  to  the  end 
of  the  visible  spectrum  at  about  435  milli- 
microns, give  reddish  blues  or  violets.  (See 
Fig.  115.)  Purples  and  bluish  reds  have 
no  simple  spectral  correlate  but  must  be 
obtained  by  mixtures  of  the  wave  lengths 
from  both  ends  of  the  spectrum.  Unique 
red  itself  requires  a  complex  physical  stimu- 
lus, since  the  longest  wave  length  visible  is 
distinctly  yellowish.  We  can  get  unique 
red  by  mixing  a  little  spectral  blue  with 
the  yellowish  spectral  red. 

Changes  in  color  through  the  spectrum 
are  not  uniform  for  equal  steps  of  physical 


green.  Below  450  millimicrons  the  only 
change  in  color  is  toward  black. 

This  relationship  holds  for  the  middle 
intensive  range  of  radiant  energy,  but  for 
high  energies  all  the  colors  become  whitish 
and  for  low  energies  blackish. 

The  whiteness  or  blackness  of  a  colo» 
depends  in  a  general  Avay  upon  the  amount 
of  visible  radiant  energy,  upon  what  is 
called  the  total  luminance.  An  illumi- 
nated spot  will  appear  lighter  or  darker, 
whiter  or  blacker,  as  the  intensity  of  the 
luminance  increases  or  decreases.  Whether 
the  spot  actually  looks  white  or  gray  or 
black  depends,  however,  upon  the  lumi- 
nance of  the  surrounding  field.  A  spot  of 
intermediate  luminance  may  look  white 
on  a  black  field,  black  on  a  white  field. 
The  ratio  of  the  spot's  luminance  to  the 
average  luminance  of  the  entire  field  is 
■  ]\e  determining  condition. 


The  Stimulus  to  Co/or 


277 


For  example,  a  spot  radiating  0.2  imil  oi 
energy  (or,  exactly,  0.2  lainberl  per  sc|iiare 
centimeter)  set  in  a  field  which  radiates 
an  average  ol'  1  unit  will  look  gray.  A 
spot  which  radiates  1  unit  in  the  same  field 
will  look  white.  Radiation  less  than  0.03 
unit  will  look  black.  If,  now,  the  lumi- 
nance of  the  whole  field  is  raised  to  10 
units,  it  will  require  2  units  to  look  middle 
gray,  whereas  the  0.2  unit  of  ihe  preceding 
example  will  now  look  black. 


420 


460         500         540         580         620 
Wave  length  in  millimicrons  (m//) 


FIGURE    11 6.      DISCRIMINATION   OF   HUE  AS   A   FUNC- 
TION   OF    WAVE    LENGTH 

Typical  hue  discrimination  curve  for  a  normal 
observer  using  a  2-degree  stimulus.  The  ordinate 
gives  the  just  noticeable  difference  in  hue  at  every 
wave  length  throughout  the  spectrum. 

The  whiteness  or  blackness  of  a  spectral 
color  depends  upon  the  same  ratios  of 
luminance  as  those  of  the  white-gray-black 
series.  With  a  white  surrounding  field, 
emitting  a  luminance  of  1  unit,  a  spot  of 
any  homogeneous  spectral  wave  length  (for 
instance,  520  millimicrons  which  looks 
green)  of  0.2  units  of  energy  will  look 
neither  blackish  nor  whitish  but  will  have 
a  brightness  of  gray.  If  we  increase  the 
energy  of  the  520  millimicrons  to  0.5  unit, 
the  color  will  appear  whitish  green  (light 
green);  if  we  reduce  it  to  0.1  imit  it  will 
look  blackish  green  (dark  green).  These 
appearances,  however,  also  depend  on  the 
laws  of  color  constancy  and  may  be  altered 
in  accordance  with  them  (pp.  234-237). 


Purity  and  Saturation 

We  saw  that  light  can  be  l>roken  up  by 
dispersion  into  many  different  wave 
lengths  and  that  each  wave  length  gives  a 
specific  color.  When  light  consists  en- 
tirely of  a  single  wave  length  it  is  said  to 
be  'spectrally  pure.'  For  the  physicist 
'white'  light  means  that  the  luminous 
energy  is  distributed  at  random  among  all 
wave  lengths.  It  is  maximally  hetero- 
geneous. Its  purity  is  zero.  Between  the 
two  extremes  of  complete  homogeneity  and 
maximal  heterogeneity  are  all  gradations 
of  spectral  purity.  \Vhen  spectral  purity 
of  a  light  stimulus  changes  alone  w'ith  no 
change  in  its  luminance  relative  to  the 
field  which  surrounds  it,  the  color  changes 
principally  in  grayness.  Grayness  tends  to 
diminish  and  saturation  to  increase  as 
purity  increases.  That  is  why  spectral 
lights  are  so  impressive;  the  colors  tend  to 
be  better  saturated  than  the  colors  from 
mixed  lights  which  objects  reflect. 

Sensation  versus  Stimulus 

There  are  three  important  ways  in  \\hich 
the  stimulus  to  color  can  change:  (1)  in 
wave  length,  (2)  in  energy  and  (3)  in 
purity.  The  preceding  sections  indicate 
the  more  obvious  ways  in  which  color  is 
affected  by  changes  in  these  three  dimen- 
sions of  its  stimulus.  Change  wave  length, 
and  you  get  change  in  tlie  red-yello^s-green- 
blue  dimension  of  color  quality.  Change  en- 
ergy, and  yoti  get  change  in  the  black-gi"ay- 
white  dimension  of  color  quality.  Change 
purity  and  you  get  change  in  the  grayness 
of  the  color  quality.  That  is  very  simple, 
but,  alas,  the  truth  is  more  complex!  All 
three  of  these  kinds  of  color  cliange  can 
be  made  to  occur,  under  certain  specific 
conditions,  bv  changing  anv  one  of  these 


278 


Co/or 


three  dimensions  ot  the  stimulus.  Here 
are  the  complexities. 

Change  ot  color  in  the  red-yellow-green- 
blue  chromatic  series  occurs  when  wave 
length  changes,  when  energy  changes  (with 
iliminished  energy  all  colors  converge  on 
red  and  green,  with  increased  energy  on 
yellow  and  blue)  and  when  the  hetero- 
geneity of  the  liglit  changes  (see  the  laws 
of  color  mixture  in  the  next  section). 

Change  of  color  in  the  black-gray-white 
achromatic  dimension  occurs  when  energy 
changes,  when  the  wave  length  of  homo- 
geneous light  changes  (pure  'yellow'  light 
is  brightest,  pure  'blue'  light  darkest)  and 
when  heterogeneity  changes  (adding  more 
lights  together  to  get  greater  heterogeneity 
makes  the  color  whiter). 

Change  of  color  in  grayness  occurs  when 
])urity  changes,  when  energy  changes  (very 
daik  and  very  light  colors  have  little  gray 
in  them;  they  are  near  to  unique  black  or 
unique  white)  and  when  wave  length 
changes  (for  instance,  the  two  ends  of  the 
spectrum,  being  very  black  have  but  little 
gray  in  them). 

There  is  an  important  lesson  to  be 
learned  here.  You  do  not  see  the  stimulus. 
Yoti  see  the  colors  which  the  stimulus  (op- 
erating under  the  laws  of  perception) 
creates.  It  is  not  true  that  in  seeing  hues 
vou  are  seeing  wave  lengths.  If  you  see  a 
green,  it  is  most  likely  a  complex  mixture 
of  wave  lengths,  and  there  are  many  dif- 
ferent mixtures  that  will  make  you  see  the 
same  green.  If  you  see  a  white,  you  are 
not  seeing  an  amount  of  energy.  You 
may  be  seeing  great  energy  for  a  single 
wave  length,  but  more  likely  you  are  see- 
ing many  wa\e  lengths  of  whicii  the  white- 
ness depends  in  part  on  color  constancy 
and  the  looks  of  the  field  around  the  white. 
If  you  see  a  gray  you  need  not  be  seeing 
maximal    heterogeneity    of    light,    for    the 


gray  may  come  from  all  the  visible  wave 
lengths  mixed  together  at  low  energy  with 
a  bright  field  around  them,  or  from  a  mere 
two  wave  lengths  mixed  in  the  right  pro- 
portions. 

Physics  depends  on  observation  as  much 
as  psychology,  but  its  obser\ations  arc  dif- 
ferent. Usually  they  are  the  visual  obser- 
vations of  scales  on  instruments.  You  can 
'see'  a  wave  length  by  reading  a  scale  on  a 
spectrometer.  You  can  'see'  light  energy 
by  reading  an  illuminometer.  And  wave 
lengths  themselves  are  not  colored,  even  if 
they  do  stimidate  the  retina  to  see  colors. 

COLOR    MIXTURE 

A  great  deal  happens  to  light  before  it 
becomes  a  proximal  stimulus  to  act  upon 
the  retina  and  produce  color.  'White' 
light  from  the  sun  is  a  heterogeneous  mix- 
ture of  all  the  visible  wave  lengths,  as  well 
as  the  invisible  infrared  and  ultraviolet 
beyond  the  spectrum.  It  falls  upon  green 
foliage  and  a  great  deal  of  the  energy  of 
every  wave  length  is  absorbed.  The  darker 
the  foliage,  the  greater  the  absorption.  The 
rest  of  the  light  is  reflected,  but  not  in  the 
random  balanced  mixture  that  makes 
'white'  light.  Light  from  the  green-yellow 
region  of  the  spectrum  predominates,  al- 
though some  red  and  some  blue  are  also 
reflected.  The  laws  of  the  mixture  of  color 
stimuli  tell  that  the  reflected  combination 
is  what  makes  the  foliage  look  yellowish 
green.  Most  'colored'  objects  reflect  all  the 
wave  lengths,  but  in  combinations  that 
give  the  objects  their  specific  colors.  The 
color  of  an  object  is  the  residt  of  what  it 
reflects  and  does  not  absorb. 

The  color  of  a  transparent  object  de- 
pends on  w^hat  it  transmits  and  does  not 
absorb.     Red  goggles   transmit  mostly   the 


Color  Mixture 


279 


'red'   end   of   the   spectrum,    absorbing   the 
'blue'  end. 

Laws  of  Mixture 

Three  laws  govern  the  mixture  of  color 
stimuli.  The  first  two  were  laid  down  by 
Isaac  Newton  in  1704.  The  third  is  not 
yet  quite  a  century  old.  They  apply  to 
what  is  called  additive  color  mixture,  the 
adciition  of  the  wave  lengths  of  one  stimu- 
lus to  the  wave  lengths  of  another  to  make 
a  total  wave  length  pattern  for  the  mixture. 
You  have  additive  mixture  when  you  have 
two  colored  lights  and  can  shine  them  su- 
perposed on  the  same  spot  on  a  white 
screen.  Or  for  additive  mixture  you  can 
use  the  device  of  Fig.  117,  where  light 
from  one  stimulus  is  reflected  from  a  half- 
silvered  mirror  at  forty-five  degrees,  while 
light  from  another  stimulus  is  transmitted 
directly  through  the  mirror,  so  that  you 
get  both  sets  of  light  added  together  along 
the  same  common  path.  Here  are  the  laws 
of  additive  mixture. 

Law  I.  For  every  color  stimulus  there  is 
another  color  stimulus  which,  when  mixed 
with  it  in  the  right  proportions,  will  can- 
cel it.  The  wave  lengths  of  both  stimuli 
will  be  present  in  the  mixed  stimulus  and 
the  total  energies  of  the  two  will  be  sum- 
mated.  The  mixture  will  be  the  color  of 
the  stronger  or,  if  the  two  are  equally 
strong,  the  mixture  will  be  gray. 

This  is  the  law  of  complementaries.  It 
agrees  with  the  color  ecjuation.  No  colors 
can  be  found  that  resemble  both  members 
of  a  complementary  pair,  both  red  and 
green,  both  blue  and  yellow,  both  black 
and  white.  Complementariness,  however, 
does  not  always  work  out  quite  so  simply. 

The  mixture  of  black  and  white  gives  a 
perfect  cancellation,  leaving,  of  course, 
gray.  Mixtuie  of  imique  blue  with  unique 
yellow   gives   giay.      The    mixture    of   red 


and  green  lights  on  the  other  liand  gives  a 
gray  so  yellowish  as  not  properly  to  be 
called  gray.  It  is  more  usual  to  say  that 
ihe  complementary  of  unicpie  md  is  bluish 
green,  and  the  complementary  of  unicjue 
green  a  bluish  red  or  purple. 

Law   II.      Color   stimuli    which   are   not 
complementary,     when     mixed,     give     re- 


S,f— 


V/* 


X 

Eye 

FIGURE     117.       SCHEME    FOR    EXPERIMENTATION    ON 
THE  MIXTURE  OF  COLORS 

The  glass  plate  P  reflects  the  light  rays  from  Sj 
into  the  observer's  eye;  the  ravs  from  So  pass  di- 
rectly through  the  glass  and  enter  the  e\e  in  ihe 
same   direction. 

sultant  colors  that  resemble  all  the  com- 
ponents to  the  same  degree  that  each  one 
is  present  in  the  mixture.  This  principle 
is  most  ob^'ious  in  the  combination  of  pairs 
of  hues  such  as  red  and  vellow  to  gi\e 
orange,  blue  and  green  to  give  bluish 
green  or  greenish  blue,  etc.,  and  it  holds 
equally  well  for  the  addition  of  black,  gray 
or  white  to  any  mixtine. 

The  stability  of  the  colors  obtained  by 
the  mixtiue  of  stimuli  is  guaranteed  by 
the  third  law. 

Laic  IIL  A  mixture  of  mixtures  that 
match   will    match    either   of   the   original 


280 


Color 


inixtmes  (provided  the  light  conditions 
remain  constant).  The  law  guarantees 
that  colors  can  be  dealt  with  as  visual  re- 
sultants on  the  basis  of  their  resemblances 
or  matches  without  reference  to  the  physi- 
cal composition  of  their  stimidi.  Thus 
another  wording  of  the  law  is:  Colors  com- 
bine no  matter  how  they  are  composed. 
You  cannot  tell  the  composition  of  a  color 
by  looking  at  it,  of  course,  but  that  fact 
does  not  matter— so  the  law  says.  If  you 
have  a  red  and  a  bluish  green  which  mix 
to  make  gray,  you  can  substitute  for  the 
red  any  other  red  that  looks  like  it  to  the 
eye,  no  matter  of  what  spectral  lights  it 
is  composed,  and  the  new  red  will  cancel 
the  bluish  green  just  as  well  as  the  old. 
You  can  make  colors  gray  by  mixing  gray 
with  them,  although  gray  can  be  made  of 
all  the  wave  lengths,  of  any  two  comple- 
mentary wave  lengths  or  in  hundreds  of 
other  ways.  You  have  only  to  be  sure 
that,  when  you  substitute  one  gray  for  an- 
other, the  grays  match.  You  may  need  to 
keep  the  illumination  constant,  but  that 
is  because  grays  and  other  colors  differently 
composed  change  color  differently  when 
illumination  shifts  from  daylight  to  the 
depths  of  night  vision. 

While  certain  exceptions  occur,  the  laws 
of  color  mixture  are  so  well  established 
that  the  important  technology  of  color- 
imetry  is  based  upon  them. 

Methods  of  Mixture 

There  are  three  important  scientific  de- 
\ices  for  mixing  color  stimuli.  The  first 
two  are  additive,  the  third  subtractive. 

(1)  Two  beams  of  light  may  be  combined 
so  that  they  act  as  a  single  effective  stimu- 
lus. Such  a  mixture  produces  a  physical 
resultant  which  is  the  sum  of  the  physical 
components.  The  method  already  men- 
tioned (p.  279  and  Fig.  117)  may  be  used. 


'I'he  simplest  way  to  do  it,  however,  is  to 
project  two  beams  of  light  upon  the  same 
area  of  a  nonselective,  diffusely  reflecting 
surface,  for  example,  matte  white  (Fig.  1 18). 
Another  way  is  to  bring  the  two  beams  to- 
gether  by   means   of  prisms   so   that   their 


White 
diffusing-^^ 
surface     \ 


>Gray 


>Gray 


FIGURE   11  8.      COLOR  MIXTURE:   THE  FIRST  LAW 

sources  are  viewed  directly  as  in  the  same 
place. 

(2)  Light  from  two  areas  may  be  rapidly 
alternated  so  that  the  two  components  are 
continuously  effective  over  the  whole  area. 
The  usual  device  of  this  sort  is  a  rotating 
disk  made  up  of  two  or  more  sectors.  At 
four  thousand  revolutions  per  minute  the 
component  sectors  fuse  and  summate  pro- 
portionately, giving  a  single  uniform  color. 

This  is  a  convenient  method  to  use  be- 
cause   of    its    simplicity.      The    method    is 


Co/or  Mixture 


281 


limited,  however,  because  its  summation 
is  proportional,  not  absolute,  that  is  to 
say,  the  color  of  each  sector  is  effectively 
spread  over  the  whole  disk,  thus  reducing 
the  stimulus  effect  per  unit  of  area  and 
making  the  mixture  grayer.  For  instance, 
if  you  want  to  mix  the  red  of  a  red  paper 
with  the  yellow  of  a  yellow  paper,  you 
can  view  both  papers  simultaneously  in 
the  same  place  by  the  use  of  prisms,  and 
you  get  an  orange  that  has  in  it  the  energ)' 
of  all  the  red  and  all  the  yellow.  But,  if 
you  put  the  two  papers  on  a  rotating  disk, 
you  have  to  make  the  disk  half  red  and 
half  yellow,  and  you  get  altogether  from 
the  disk  only  half  as  much  energy  as  you 
would  from  mixing  a  whole  red  disk  with 
a  whole  yellow  disk.  The  result  is  that 
colors  made  by  rotation  of  components  are 
duller  and  grayer  than  they  would  be  by 
simple  addition. 

(3)  When  a  beam  of  light  is  passed 
through  two  or  more  transparent  colored 
filters  in  succession,  we  have  what  is  known 
as  subtractive  color  mixture.  The  results 
are  quite  different  from  those  of  additive 
color  mixture.  In  fact,  the  subtractive 
procedure  should  not  properly  be  called 
color  mixture,  although  it  is  a  way  of  get- 
ting new  colors  from  the  combinations  of 
others. 

Two  or  more  filters  in  combination  will 
transmit  only  those  wave  lengths  common 
to  both  or  all.  For  example,  if  a  filter 
that  transmits  only  short  waves  below  550 
millimicrons  is  placed  over  one  that  trans- 
mits only  the  long  waves  above  550  milli- 
microns, no  light  will  pass  the  combina- 
tion, and  it  is  without  meaning  to  talk 
about  the  color  of  the  combination.  It  is 
not  only  complementary  filters  that  cancel 
each  other.  A  red  filter  may  cancel  a  blue 
because  the  two  filters  transmit  no  common 
wave  lengths.    On  the  other  hand,  a  yellow 


and  a  blue  fdter  that  are  foinplemcnlary 
may  give  a  green,  even  though  the  yellow 
and  blue  are  complementary.  Why!-  The 
two  filters  overlap  in  transmission.  The 
yellow  filter  lets  through  wave  lengths  from 
the  red,  yellow  and  green  regions.  The 
color  looks  yellow  because  the  stimulus  has 
more  yellow  than  red  and  green  and  be- 
cause the  red  and  green  tend  to  cancel  and 
make  a  gray  which  mixes  with  the  yellow. 
The  blue  fdter  lets  through  green,  blue  and 
violet  light,  and  looks  blue  because  blue 
predominates.  Together  the  filters  let 
through  only  the  green  light  which  is  all 
that  is  common  to  both  of  them.  .So  yel- 
low and  blue,  which  would  give  gray  by 
additive  mixture,  in  this  case  give  green  by 
subtractive  mixture.  The  yellow  filter  sub- 
tracts the  blue  and  violet,  and  the  blue 
filter  subtracts  the  red  and  yellow.  Only 
green  is  left. 

(4)  In  the  mixture  of  color  pigments,  all 
the  foregoing  factors  may  be  involved. 
Pigments  consist  of  fine  particles  which 
modify  the  light  falling  upon  them  bv 
selective  reflection,  by  selective  transmis- 
sion, by  both  at  once,  and  by  refraction. 
All  these  effects  are  modified  by  the  me- 
dium in  which  the  pigments  are  suspended. 
In  addition,  one  size  or  type  of  pigment 
particle  has  effects  on  another  size  or  type 
that  cannot  be  anticipated  from  the  mere 
color  of  either.  Therefore,  although  a  par- 
ticular yellow  pigment  and  a  particular 
blue  pigment  ma)'  result  in  a  green,  other 
pigments,  visually  identical  to  the  original 
yellow  and  blue,  may  mix  to  give  red  or, 
perhaps,  gray.  In  all  cases  the  la^\-s  of 
color  mixture  are  operative,  but  otlier  fac- 
tors control  the  selection  of  available  wave 
lengths.  For  instance,  to  cliange  tlie  color 
of  a  certain  yellowish  red  pigment  toward 
bluish  red,  it  may  even  be  necessan,-  to  add 
white  pigment,  not  blue. 


282 


Color 


Colorimetry 

Within  the  last  twenty  years  optical  in- 
struments have  been  so  developed  that  a 
relatively  simple  operation  can  obtain  a 
precise  quantitati\e  physical  measurement 


FIGURE    119.       THREE  COLOR    MIXTURE    TRIANGLE 


Curved  line  shows  spectrum:  small  triangle,  mix- 
lures  from  three  spectral  colors:  large  triangle,  three 
primaries  whose  mixture  would  give  all  the  spectral 
colors;  c493.6  (red)  is  nonspectral  and  comple- 
mentary to  493.6  (bluish  green). 

f)f  the  spectral  components  of  any  light 
source,  transmitting  medium  or  reflecting 
surface.  Given  a  spectral  distribution 
curve  for  some  color,  it  is  not,  however, 
easy  to  say  from  the  curve  just  what  the 
appearance  of  the  color  would  be.  Color- 
imetry puts  the  three  laws  of  color  mixture 
to  work  so  that  any  spectral  distribution 
can  be  translated  easily  into  a  statement 
of  what  color  the  distribution  would  give. 
(See  Fig.  119.) 

Since  every  component  wave  length  in  a 
spectral  distribution  combines  with  all  the 
rest  under  one  or  the  other  of  the  first  two 
laws  of  color  mixture,  and  since  under 
Law  III  any  resultant  is  equivalent  psycho- 
logically  to   any   other   resultant  which   it 


matches,  it  is  possible  to  equate  the  color 
of  any  spectral  distribution  to  a  much 
simpler  combination  of  wave  lengths.  For 
practical  purposes  three  wave  lengths  have 
been  found  to  answer  most  of  the  needs  of 
such  a  reference  system.  Obviously  the 
wave  lengths  must  be  carefully  chosen  and 
must  be  such  that  their  normal  colors  will 
include  unique  red,  yellow,  green  and  blue. 
There  are  many  possibilities,  all  of  which 
will  work  out  satisfactorily.  The  set  must 
include  a  wave  length  near  each  end  of  the 


520 


Mixture  diagram  according 

to  the  1931  I.C.I,  standard 

observer  and  coordinate  system 


FIGURE    120.      STANDARD  TRICHROMATK;   C;0L0R 
COORDINATES 

The  figure  shows  the  spectral  colors  plotted  on 
the  standard  ICI  (International  Congress  on  Illumi- 
nation) coordinates.  This  plot  permits  specifica- 
tion of  all  unique  or  duplex  colors.  The  yellow  in 
this  diagram  can  be  specified  by  x  =  0.512,  y  = 
0.488. 

spectrum  and  one  near  the  middle.  The 
international  standard  that  has  been 
adopted  specifies  wave  lengths  700,  546.1 
and  435.8  millimicrons,  which  give,  respec- 


Color  Phenomena 


283 


lively,  a  slightly  yellowish  red,  a  yellow 
green  and  a  reddish  blue. 

Data  have  been  obtained  which  stand- 
ardize the  amounts  of  these  three  stimuli 
(R  +  G  +  B)  that  will  match  evei-y  one  of 
the  monochromatic  spectral  stimuli.  These 
quantities  are  known  as  the  tri-stimulus 
values  of  a  color.  All  colors  having  the 
same  tri-stimulus  values,  no  matter  what 
the  physical  composition  of  their  stimuli 
may  be,  will  look  the  same.  That  is  l,aw 
III  of  color  mixture. 

A  still  simpler  form  of  representation  has 
been  made  by  taking  the  proportions  of  the 
tri-stimulus  values,  for  R,  G  and  B,  respec- 
tively, that  is,  R/{R  +  G  +  B),  G/(R  +  G 
+  B),  B/{R  +  G  +  B).  Any  two  of  these 
proportions  determine  the  third  and  thus 
specify  the  spectral  equivalent  of  a  stimu- 
lus, but  not  its  black-white  component. 
The  trichromatic  coordinates  can  be  plotted 
on  a  two-dimensional  diagiam  (Fig.  120). 
Trichromatic  colorimetry  which  has  a  wide 
field  of  applications  is  based  upon  this 
system  of  representation. 

COLOR    PHENOMENA 

We  come  now  to  a  consideration  of  the 
more  general  psychological  phenomena  of 
the  occurrence  of  color  in  human  experi- 
ence—the laws  of  adaptation,  contrast  and 
indirect  vision,  and  the  facts  of  color  blind- 
ness and  night  vision. 

Adaptation 

When  color  stimulation  is  continued,  the 
color  changes,  at  first  rapidly  and  then  more 
slowly,  tending  toward  gray.  A  bright 
light  retains  its  extreme  brightness  for  only 
a  brief  time.  The  sun  on  snow  gives  a 
blinding  glare  when  we  first  go  out  of  a 
more  dimly  lighted  building,  but  the  glare 
soon  moderates.     Similarly,   die  blackness 


of  the  dark  does  not  last.  The  darkened 
theater  is  hopelessly  black  when  we  first 
enter,  but  when  we  have  been  there  a  half 
hour,  the  blind  behavior  of  a  new  arrival 
seems  ludicrous.  The  same  thing  happens 
to  all  the  other  colors.  The  yellowness  of 
artificial  illumination,  as  it  is  first  turned 
on,  soon  disappears. 

The  phenomenon   we  are  describing  is 
known  as  sensory  adaptation  and  is  effet- 


FIGURE    121.       SENSORY    ADAPTATION 

Steadily  fixate  the  line  between  the  two  fields. 
Notice  how  the  black  lightens  and  the  while 
darkens. 

tive  for  all  visual  qualities  with  one  ex- 
ception, the  ever-constant  gray.  The  law 
of  color  adaptation  may  be  stated  as  fol- 
lows: With  continued  duration  all  colors 
tend  toward  gray.  Blacks  and  whites,  as 
well  as  reds,  oranges,  yellows,  greens,  blues 
and  purples,  get  grayer  when  the  stimula- 
tion for  them  continues  on  the  same  part 
of  the  retina. 

Sensory  adaptation  can  be  observed  and 
described  most  acctirately  if  you  fixate 
steadily  a  small  patch  of  color  or  a  parti- 
colored field,  to  give  a  basis  for  compari- 
son. Hang  up  side  by  side  a  sheet  of  white 
cardboard  and  a  sheet  of  black  caidboard, 
and  stare  fixedly  at  some  point  on  their 
line  of  junction.  (See  Fig.  121.)  Almost 
at  once,  clotids  of  gray  begin  to  form  over 
the  two  fields,  lightening  the  black  and 
darkening  the  white.  The  clouding  in- 
creases   as    fixation    continties    until    both 


284 


Color 


halves  of  the  field  approach  gray.  You 
could  get  the  whole  particolored  field  a 
uniform  gray  if  you  could  but  keep  your 
eyes  still.  Instead  you  find  that  you  keep 
twitching  them,  losing  fixation  and  then 
regaining  it. 

Afterimages 

The    effects    of    any    visual    stimulation 
persist   after   its   removal,   and    the    longer 


FIGURE    122.       NEGATIVE    .AFTERIMAGE 

Fixate  steadily,  for  about  a  minute,  one  of  the 
eyes  in  this  negative  portrait.  Then  shift  the  fixa- 
tion quickly  to  a  blank  sheet  of  white  paper, 
^'ou  will  see  a  negative  afterimage  of  this  negative, 
that   is  to  say,  a  positive.     [.After  A.  Noll   (1926).] 

the  original  stimulation,  the  greater  and 
more  persistent  are  the  after-effects.  The 
glare  of  the  sun  on  the  snow  will  be  modi- 
fied to  some  extent  according  to  the  illu- 
mination of  the  house  from  which  we  have 
just  come.  The  theater  is  darker  when  we 
enter  from  a  bright  day  than  when  the  day 
outside  is  dull  and  overcast.  When  colored 
glasses  have  been  worn  for  a  time  and  then 
removed,  everything  takes  on  a  color  com- 
plementary' to  the  color  of  the  glasses.  If, 
after  you  have  stared  at  the  particolored 
card  for  a  time,  someone  covers  it  with  a 
uniform  screen,  the  screen  appears  blackish 
where  the  card  was  white  and  whitish  where 


the  card  was  black.  (See  Fig.  121.)  The 
effects  are  even  more  striking  if  other  colors 
are  substituted  for  black  and  white.  If 
the  color  fixated  is  red,  the  after-effect  will 
be  green;  if  blue,  yellow;  and  vice  versa. 
Thus  white  follows  black  and  black,  white; 
red  follows  green  and  green,  red;  yellow 
follows  blue  and  blue,  yellow.  This  phe- 
nomenon is  known  as  the  negative  after- 
image. The  complementary  relationship 
of  the  opposing  color  pairs  of  the  color 
etjuation  appears  again.     (See  Fig.  122.) 

The  facts  of  adaptation  and  negative 
afterimage  show  that  we  are  dealing  with  a 
single  process.  Adaptation  to  one  color 
means  sensitization  to  its  complementary. 
That  is  what  you  are  seeing  when  you  try 
to  fixate  the  line  between  the  black  and 
white  fields  of  Fig.  121.  As  your  eyes 
twitch,  the  image  of  a  narrow  edge  of  white 
field  falls  upon  the  black-adapted,  white- 
sensitized  part  of  the  retina,  and  the  white 
looks  even  whiter  than  it  did  at  first.  So 
with  the  black,  when  the  eyes  twitch  the 
other  way. 

The  after-effects  of  continued  color 
stimulation  are  not,  however,  limited  to 
this  complementary  or  negative  afterimage. 
There  is  also  a  positive  afterimage,  so  called 
because  its  color  resembles  the  original 
color  although  somewhat  grayer.  A  color 
experience  does  not  cease  immediately 
when  the  color  stimulus  is  removed,  but 
persists  for  a  measurable  time  and  may, 
after  disappearing,  reappear  again.  It  is 
the  reappearance  that  is  the  positive  after- 
image. Sometimes  the  inevitable  lag  of 
every  sensation  after  its  stimulus  has  ceased 
may  be  prolonged  without  an  interval  into 
the  positive  afterimage.  Positive  after- 
images, especially  when  they  occur  after 
long  adaptation  to  the  dark  and  short  ex- 
posure to  a  brilliant  stimulus  can  be  very 
vivid,  showing  detail  and  reproducing  all 


Afterimages  and  Contrast 


285 


the  colors.  The  circle  of  light  produced 
by  the  revolving  pinwhecl  in  a  display  of 
fireworks  is  mostly  positive  afterimage. 

Contrast 

The  quality  of  a  color  varies  with  its 
background.  If  a  red  which  is  unique 
when  it  occupies  the  entire  visual  field  is 
restricted  in  size  and  surrounded  by  blue, 
it  becomes  yellowish.  If  the  surrounding 
color  is  changed  to  yellow,  the  red  turns 
bluish.  As  we  have  seen,  white  in  the  back- 
ground may  give  an  appearance  of  black, 
and  vice  versa.  A  green  background  makes 
the  red  redder,  and  conversely.  The  only 
background  color  that  does  not  alter  the 
original  quality  is  gray.  For  this  reason, 
when  we  wish  to  examine  a  color  accu- 
rately, we  always  place  it  upon  a  gray 
background.  Similarly  we  can  study  the 
effect  of  a  background  best  by  placing  a 
gray  strip  or  patch  upon  it.  The  gray  be- 
comes tinged  with  color  complementary  to 
the  background.  This  effect  of  back- 
ground upon  a  color  is  a  third  instance  of 
the  complementariness  of  colors.  (See  Fig. 
123.) 

We  may  state  the  general  law  of  contrast 
as  follows:  Every  color  in  the  visual  field 
affects  and  is  affected  by  every  otJier  color. 

Several  secondary  laws  made  specific  the 
nature  and  degree  of  the  effect.  (1)  The 
quality  of  the  induced  color  is  always  that 
of  the  compleinentary  of  the  inducing 
color.  (2)  The  induction  increases  with  a 
decrease  of  gray  in  the  inducing  color. 
(3)  The  induction  is  gi-eatest  when  there 
are  no  sharp  outlines  between  the  back- 
ground and  the  induction  field.  (4)  The 
induction  is  greatest  at  the  margins  near 
the  inducing  field.  (5)  The  induction  is 
greatest  when  the  background  and  the  in- 
duction field  are  in  the  same  plane.  (6) 
The  inducing  effect  of  red,  yellow,  blue  and 


green  is  greater  wlicii  there  is  no  white  or 
black  contrast. 

Everyday  experierue  affords  iriany  ex- 
amples of  color  induction.  Gray  stripes 
on  a  green  material  will  appear  a  purplish 
red.  A  bright  light  in  the  visual  field 
makes  everything  else   d;iik.     This   is  one 


FIGURE   123.      SIMULTANEOUS   INDUCTION   OF 
CONTR.\ST 

A  \diite  batkgiouml  induces  an  increment  of 
black  in  a  small  area  of  grav  placed  upon  it.  and 
vice  versa.  The  grav  dots  and  figures  are  all  identi- 
cal but  appear  dark  on  the  light  background  and 
light  on  the  dark  backgioinid. 


286 


Color 


reason  why  the  lights  of  an  oncoming  car 
'blind'  you.  They  cover  everything  else 
with  a  black  that  blots  out  contours.  A 
student  of  art  soon  learns  that  he  can  color 
some  objects  by  painting  only  the  surround- 
ing objects.  A  sailboat  against  a  blue  sky 
will  be  tinted  with  yellow.  Color  contrast 
contributes  to  everything  we  see  and  must 
be  taken  into  account  when  we  wish  to 
specify  or  control  the  color  of  an  object. 

A  manufacturer  once  tried  to  make  a 
green  and  gray  gingham.  When  he  wove 
the  gray  threads  among  the  green,  he  had 
a  green  and  pink  gingham.  Undoubtely 
the  gingham  fulfilled  the  conditions  of  the 
secondary  laws  of  contrast.  There  must 
have  been  little  gray  in  the  green.  The 
gray  and  gieen  threads  must  have  been 
equally  white  or  equally  black.  The 
checks  of  the  gingham  must  have  been 
small,  must  have  appeared  to  be  in  the 
same  plane  and  without  contours. 

Shadows,  when  black-white  equality  is 
seemed,  are  especially  subject  to  red-yellow- 
green-or-blue  contrast  effects,  because  a 
shadow  lies  exactly  in  the  plane  of  the  sur- 
face on  which  it  is  projected  and  has  no 
prominent  contours.  If  yoti  stand  under 
a  red  neon  light  you  will  notice  that  your 
shadow  is  green. 

A  piece  of  gray  paper  on  a  field  of  red 
paper  looks  greener  if  the  whole  field  is 
covered  with  thin  white  tissue  paper.  Why? 
Because  the  tissue  paper  cuts  out  perceived 
contours  and  puts  the  red  and  the  gray  in 
the  same  plane,  as  if  the  gray  were  a 
shadow.  The  tissue  works  against  contrast 
because  it  decreases  the  relative  intensity 
of  the  red,  making  it  giayer,  but  die  laws 
of  contour  and  of  plane  are  more  impor- 
tant and  make  up  for  the  disadvantage  of 
the  grayer  red. 


Indirect  Vision 

The  quality  of  a  color  varies  with  its 
position  in  the  visual  field.  If,  as  wc 
fixate  steadily  on  a  point  straight  ahead, 
a  color  stimulus  that  is  not  too  intensive 
enters  the  visual  field  from  the  side  and 
approaches  the  fixation  point,  the  color 
undergoes  a  series  of  changes.  In  the  ex- 
treme periphery  it  appears  gray,  light  or 
dark  according  to  its  whiteness  or  blackness. 
A  little  farther  in,  a  blueness  or  yellowness 
may  appear,  but  not  until  the  stimulus  has 
reached  a  position  near  the  center  of  the 
field  is  it  reddish  or  greenish.  If  the  en- 
tire vistial  field  of  each  eye  is  explored  in 
this  manner,  there  will  be  found  a  fairly 
restricted  zone  in  the  center  of  the  field  of 
vision  where  all  color  qualities  can  be  seen. 
Surrounding  this  area  lies  a  second  zone  in 
which  no  redness  or  greenness  is  visible 
but  where  blueness  and  yellowness  can  be 
seen.  In  the  extreme  periphery  all  color 
experience  is  restricted  to  blacks,  grays 
and  whites  except  with  very  intensive 
stimuli.  In  this  spatial  distribution  the 
colors  have  appeared  again  in  their  com- 
plementary pairs.      (See  Fig.  124.) 

Thus  a  dark  ptirple  disk,  being  moved 
from  the  outside  of  the  field  to  the  center, 
will  appear  first  black,  then  blue,  then 
purple.  A  light  orange  disk  will  appear 
first  white  or  light  gray,  then  yellow,  then 
orange. 

The  boundaries  of  the  color  zones  in  the 
field  of  vision  are  not  rigidly  fixed.  The 
more  effective  the  stimulus,  the  farther 
from  the  center  can  the  color  be  seen.  The 
zones  are  larger  for  a  spot  of  spectral  light 
than  for  a  patch  of  colored  paper,  because 
the  spectral  light  is  less  gray.  The  zones 
are  larger  for  large  stimuli  than  for  small. 
You  might  think  that  you  could  see  your 
own  color  zones  by  looking  with  one  eye  at 


Indirect  Vision 

90° 


287 


270" 

FIGURE    124.      COLORS  VISIBLE  IN    INDIRECT  VISION 

Chart  shows  the  portion  of  the  visual  field  of  the  right  eye  within  which  each  of  the  unique  colors 
can  be  seen  when  the  stimulus  is  a  small  patch  of  homogeneous  light.  At  these  intensities  red  and 
green  are  limited  to  an  area  of  approximately  20  degrees  about  the  fixation  point,  whereas  yellow 
and  blue  can  be  seen  out  to  40  or  50  degrees  in  the  vertical  and  50  to  60  in  the  horizontal  meridian. 


a  large  sheet  of  purple  paper  which  fills 
your  entire  field  of  vision.  You  cannot. 
The  large  color  stimulus  is  so  effective  that 
it  causes  you  to  see  the  purple  all  the  way 
to  the  limits  of  your  field  of  vision. 

In  the  course  of  exploration  of  the  visual 


field  of  a  single  eye  with  a  small  stimulus 
we  find  an  area  of  some  size  where  the 
stimulus  completely  disappears.  Known  as 
the  blind  spot,  it  occurs  because  tlie  eye's 
retina  is  practically  blind  where  the  optic 
nerve  enters  it.     You  do  not  see  vour  o\m 


288 


Co/or 


blind  spot  in  ordinary  vision.  For  one 
thing,  the  blind  spots  in  the  two  eyes  do 
not  coincide,  so  notliing  is  missing  in  two- 
eyed  vision.  Still  you  cannot  see  your 
blind  spot  for  one  eye  when  you  close  the 
other.  That  is  because  in  perception  you 
fill  in  the  field  with  ■\\hate\cr  the  surroinid- 
ings  would  make  you  think  belonged  there. 
As  we  have  seen  before,  perception  tries 
to  keep  objects  constant.  In  a  neutral 
field,  however,  with  only  a  fixation  point 


counted.  In  his  memoirs  Sir  John  Dalton, 
a  noted  chemist  of  the  late  eighteenth  cen- 
tury, gives  an  excellent  account  of  the  dif- 
ficulties into  which  his  own  peculiarities 
of  vision  had  led  him.  His  description  of 
them  gives  us  a  good  idea  of  how  the  world 
of  colors  looks  to  a  color-blind  person. 

Dalton  wrote:  "My  observations  began 
with  the  solar  spectrum,  or  coloured  image 
of  the  sun,  exhibited  in  a  dark  room  by 
means  of  a  glass  prism.  ...  I  see  only  two 


X 


FIGURE   125.      BLIND  SPOT 


Close  your  left  eye,  hold  the  book  at  a  distance  of  about  14  inches  in  front  of  you,  and  fixate  the  dot 
with  the  right  eye.  If  you  see  the  face  at  the  right,  move  the  book  a  little  nearer  or  farther  awav.  When 
I  he  right  distance  is  found  the  face  will  disappear  and  the  page  will  appear  blank. 


and  one  other  object  present,  the  existence 
of  the  blind  spot  can  be  readily  demon- 
strated.    (See  Fig.    125.) 

Color  Blindness 

A  certain  deviation  of  color  vision  ap- 
pears as  a  special  peculiarity.  About  four 
per  cent  of  the  population,  nearly  all  males, 
never  experience  the  color  qualities  red 
and  green.  They  see  only  five  unique 
colors,  blue,  yellow,  black,  white  and  gray. 
All  redness  or  greenness  of  normal  vision 
appears  to  them  gray,  just  as  they  do  out- 
side the  central  zone  of  the  field  of  vision. 
They  do  not  need  a  color  pyramid  to  dia- 
gram the  colors  visible  to  them.  They 
see  only  what  appears  in  the  color  square 
for  yellow-white-blue-black  with  gray  in  the 
center.    (See  Fig.  108,  p.  272.) 

Many  curious  instances  of  this  deficiency 
have  been  reported.  Attention  was  first 
called  to  the  defect  by  Huddart  in  1777, 
but    the    truth    of   his    assertions    was    dis- 


or  at  most  three  distinctions.  These  I 
should  call  yellow  and  blue;  or  yellow, 
blue,  and  purple.  My  yellow  compre- 
hends the  red,  orange,  yellow,  and  green 
of  others;  and  my  blue  and  purple  coincide 
with  theirs.  That  part  of  the  image  which 
others  call  red,  appears  to  me  little  more 
than  a  shade,  or  defect  of  light;  after  that 
the  orange,  yellow,  and  green  seem  one 
colour,  which  descends  pretty  uniformly 
from  an  intense  to  a  rare  yellow,  making 
what  I  should  call  different  shades  of  yel- 
low. The  difference  between  the  green 
part  and  the  blue  part  is  very  striking  to 
my  eye:  they  seem  to  be  strongly  contrasted. 
.  .  .  All  crimsons  appear  to  me  to  consist 
chiefly  of  dark  blue;  but  many  of  them  seem 
to  have  a  strong  tinge  of  dark  brown.  I 
have  seen  specimens  of  crimson,  claret,  and 
mud,  which  were  very  nearly  alike.  Crim- 
son has  a  grave  appearance,  being  the  re- 
verse of  every  shewy  and  splendid  coloirr. 
\Voolen  yarn  dyed  crimson  or  dark  blue 


Color  Blindness 


289 


is  ilie  same  to  inc.  Pink  scciiis  to  be  com- 
posed of  nine  parts  of  light  blue,  and  one 
of  red,  or  some  colour  which  has  no  other 
effect  than  to  make  the  light  blue  appear 
dull  and  faded  a  little.  .  .  .  My  idea  of 
red  I  obtain  from  vermilion,  minium,  .seal- 
ing wax,  wafers,  a  soldier's  uniform,  etc. 
These  seem  to  have  no  blue  whatever  in 
them.  .  .  .  Blood  appears  to  me  red;  but 
it  differs  much  from  the  articles  mentioned 
above.  It  is  inuch  more  dull,  and  to  me  is 
not  unlike  that  colour  called  bottle-green. 
Stockings  spotted  with  blood  or  with  dirt 
would  scarcely  be  distinguishable.  ...  I 
take  my  standard  idea  [of  green]  from 
grass.  This  appears  to  me  very  little  dif- 
ferent from  red.  .  .  .  Green  and  orange 
have  much  affinity  also.  .  .  .  Green  woolen 
cloth,  such  as  used  to  cover  tables,  appears 
to  me  a  dull,  dark,  brownish  red  colour. 
.  .  .  When  this  kind  of  cloth  loses  its 
colour,  as  other  people  say,  and  turns  yel- 
low, then  it  appears  to  me  a  pleasant 
green."  * 

In  the  same  class  with  Dalton's  experi- 
ence is  the  inability  of  color-blind  persons 
to  distinguish  ripe  red  cheiTies  from  the 
foliage  of  the  tree  upon  which  they  hang, 
and  red  flags  of  a  golf  course  from  green 
turf.  We  must  not,  however,  confuse  a 
lack  of  accuracy  in  color  naming  with  the 
true  lack  of  red-and-green  color  experience. 

Upon  careful  examination  color  blind- 
ness has  been  found  to  be  not  a  simple  all- 
or-none  phenomenon.  There  are  varying 
degrees  and  kinds  of  deficiency  in  color 
vision.  A  few,  no  more  than  one  hundred 
cases,  have  been  reported  in  which  the  only 
colors  seen  are  black,  gray  and  white.     For 

*  John  Dalton.  Extraordinary  Facts  relating  to 
the  Vision  of  Colours:  with  observations.  Read 
Oct.  31st,  1794.  Memoirs  of  the  Literary  and 
Philosophical  Society  of  Manchester,  1798,  5,  Part 
1,  pp.  31-35. 


tlicm  (<)\()r  vision  is  reduced  to  something 
like  the  extreme  peripheral  vision  of  a 
normal  observer.  Most  color  deficiencies, 
however,  involve  only  red  and  green. 

A  further  complication  is  that  red-green 
color  blindness  is  of  two  different  types. 
Most  color-blind  persons  see  gray  in  place 
of  both  red  and  green  with  the  relative 
brightnesses  of  the  spectral  colors  un- 
changed. Such  persons  have  been  called 
deuteranopes.  A  few  color-deficient  pei- 
sons  have  color  vision  further  complicated 
by  a  shift  of  relative  brightness  away  from 
the  long  wave  lengths  toward  the  short 
wave  lengths,  so  that  in  place  of  red  they 
see  black  and  in  place  of  green  they  see  a 
whitish  gray.  Such  persons  have  been 
called  protanopes.  The  names  are  derived 
from  the  fact  that  protanopic  vision  is  sup- 
posed to  be  more  primitive  than  deuter- 
anopic, just  as  all  red-green  color  blind- 
ness is  supposed  to  be  a  more  primiti\e— 
evolutionarily  older— kind  of  vision  than 
normal  vision. 

Between  deficiencies  in  which  all  sensi- 
tivity to  green  and  red  is  lacking  and  cases 
of  normal  sensitivity,  lie  manv  degrees  of 
color  weakness.  It  appears,  moreover,  from 
recent  measurements  that  red-green  defi- 
ciency is  accompanied  by  a  loss  in  blue- 
yellow  sensitivity.  The  color  blind  suffer 
an  overall  loss.  They  do  not  compensate 
for  the  loss  of  one  pair  of  complementaries 
by  increased  sensitivity  for  another  pair. 

In  spite  of  their  deficiency,  color-blind 
persons  name  colors  correctly  more  often 
than  not.  There  is  sufficient  difference  be- 
tween other  colors  and  the  didl  dark  yellow 
which  they  see  for  red,  or  the  light  yellow- 
ish gray  that  green  appears  to  be.  for  them 
correctly  to  identify  objects  designated  by 
those  color  names.  It  is  undoubtedly  for 
this  reason  that  color  deficiency  is  so  re- 
cent a  discovery.     In  our  complex  civiliza 


290 


Color 


lion  of  today,  color  discrimination  has  in- 
creased in  importance  so  that  color  defi- 
ciency is  a  disadvantage,  often  a  menace, 
in  numerous  occupations  (for  instance,  at 
sea  or  in  transportation  where  colored  sig- 
nals are  used).  Hence  many  tests  have 
been  devised  for  its  detection.  Identifica- 
tion of  color  samples  or  matching  and  sort- 
ing can  be  used  to  bring  out  color  anom- 
alies. Accuracy  of  results  depends  on  the 
care  with  which  the  color  samples  are  pre- 
pared. In  an  early  test  devised  by  Holm- 
gren, the  subjects  were  asked  to  find  among 
a  Aariety  of  skeins  of  yarn  samples  similar 
to  three  standards.  From  the  errors  ex- 
hibited, a  color-blind  subject  should  be  de- 
lected, were  it  not  for  the  fact  that  many 
such  people  learned  to  correct  their  errors 
and  so  appeared  to  pass  the  test.  Matching 
tests,  with  carefully  graded  series  of  color 
(hips,  work  better  and  can  be  used  to  meas- 
ure the  degree  of  the  defect. 

In  inany  ways  the  most  interesting  type 
of  test  is  one  in  which  patterns  are  made 
up  of  two  colors  which  appear  identical 
to  a  color-blind  person  but  are  quite  differ- 
ent to  nomial  vision,  such  as  orange  and 
yellow-green  or  blue-green  and  lavender. 
A  number  is  oiulined  in  dots  of  one  color 
on  a  background  of  the  other  color.  The 
color-blind  subject  is  unable  to  make  out 
such  a  concealed  pattern.  Still  other  tests 
present  small  areas  of  filtered  light  for  rec- 
ognition and  diagnose  color  deficiency  on 
llie  basis  of  confusions  of  'white'  light 
with  'green,'  or  'yellow'  with  'red,'  or  'red' 
with  'green.'  With  properly  chosen  filters 
this  test  can  be  very  accurate. 

Night  Vision 

Vision  in  the  ordinary  ranges  of  daylight 
from  fairly  faint  twilight  up  to  the  bright- 
est blaze  of  the  stm  is  called  daylight  insion 
or  photopic  vision.    Nearly  all  the  facts  de- 


scribed thus  far  in  this  chapter  are  facts  of 
daylight  vision.  Vision  from  the  point 
where  twilight  falls  down  to  what  you  see 
in  the  coimtry  on  a  moonless  night  when 
the  clouds  obsctue  some  of  the  stars  (you 
do  not  see  objects  unless  you  have  been 
some  time  in  the  dark)  is  night  vision  or 
scotopic  vision.  In  twilight,  daylight  vi- 
sion and  night  vision  overlap;  both  func- 
tion together.  The  next  section  shows 
that  we  believe  that  there  are  in  the  retina 
two  kinds  of  receptors  for  these  two  kinds 
of  vision:  cones  for  daylight  seeing,  rods 
for  night  seeing.  That  theory  gives  us  still 
another  set  of  names  for  the  same  differ- 
ence: cone  vision  and  rod  vision. 

What  happens  when  the  energy  of  the 
general  illumination  is  gradually  dimin- 
ished from  a  level  necessary  for  good  day- 
light vision  to  the  level  at  which  night 
\ision  is  working  alone?  You  can  see  the 
answer  for  yourself  if  you  watch  the  light 
fade  on  a  variegated  field  of  color  samples. 
You  can  make  the  obser\ation  during  a 
couple  of  hours  at  twilight  or  you  can 
hurry  the  process  up  by  arranging  very 
gradually  to  shut  the  door  of  a  room 
which  will  be  pitch  dark  when  the  door 
is  completely  closed.  At  first,  as  the  light 
fails,  the  colors  remain  the  same  in  respect 
of  the  red-yellow-green-blue  series,  though 
they  become  somewhat  blacker  and  grayer. 
Then  at  a  partictilar  point  the  reds  begin 
to  darken  considerably  and  the  greens  and 
blues  to  lighten.  This  change  is  called 
the  Purkinje  phenomenon,  after  the  physi- 
ologist who  discovered  it  in  1825.  Red 
finally  turns  to  black  while  green  and  blue 
become  a  silvery  light  gray.  Thus  in  com- 
plete night  vision  all  colors  reduce  to 
shades  of  black,  gray  and  white.  As  adap- 
tation goes  on,  the  blacks  disappear,  leav- 
ing onlv  grays  and  whites,  which  have  the 
bluish  cast  that  is  taken  for  granted  as  a 


Night  Vision 


291 


rharacteristic:  of  inof)nliffht.  Tims  in  mo- 
lion  pictures,  almost  any  scene  <an  i)e  con- 
verted into  'moonlif^Iil'  simjjly  by  dyeing 
the  whole  film  fjlue  withoiii  icducing  the 
intensity  of  tiie  illuminalion. 

We  can,  therefore,  in  tiiis  continuous 
process,  distinguisli  two  stages.  In  the 
Purkinje  phenomenon  daylight  and  night 
vision  act  together.  We  can  still  see  reds, 
yellows,  greens,  blues  and  violets,  but  the 
reds  are  very  dark,  and  the  IjIucs  and  vio- 
lets very  light.  In  complete  night  vision 
the  reds  have  become  black,  the  blues  and 
violets  light  bluish  gray,  and  the  yellow- 
greens  bluish  white.  After  long-continued 
night  vision,  most  of  the  blacks  disappear 
under  adaptation,  since  there  is  nothing 
darker  than  a  lightless  region  for  the  night 
eye  to  see  as  black.    (See  Fig.  126.) 

Full  sensitivity  of  night  vision  is  not  at- 
tained at  once,  if  illumination  suddenly 
drops  to  a  low  level.  It  develops  grad- 
ually at  a  decreasing  rate  over  a  period  of 
half  an  hour  to  an  hour.  In  that  time 
your  ability  to  discriminate  small  intensi- 
ties of  light  increases  by  at  least  ten  thou- 
sand times.  Thus  dark  adaptation  means 
not  only  that  the  blacks  have  become  gray, 
but  also  that  sensitivity  has  increased  enor- 
mously. In  the  Second  World  War  the 
psychology  of  night  vision  became  sud- 
denly important,  because  all  at  once  there 
was  need  for  men  to  see  in  the  dark.  In 
peacetime  the  way  to  see  in  the  dark  is 
to  turn  on  the  light.  In  war  you  dare  not— 
not  if  you  are  a  night  fighter  or  a  naval 
lookout  or  an  infantry  patrol  on  duty  at 
night.  Such  men  stayed  in  the  dark  half 
an  hour  before  they  went  on  night  duty 
so  that  their  night  vision  might  be  maxi- 
mally sensitive  after  thorough  dark  adap- 
tation. Or  else  before  duty  they  Avore  red 
goggles,  the  kind  of  red  goggles  that  let 
through  only  the  very  long  wave  lengths. 


- 

/ 

Y 

\ 
\ 

- 

/ 

'  \ 

— 

/ 

;  \ 

\ 

~ 

- 

1 

/ 
/ 

\ 

\ 
\ 

- 

- 

/ 

/ 
/ 
/ 

^ 

V 

\ 

- 

- 

^. 

V 

/ 

V 

\ 

Fn  this  way  they  kept  the  rods  in  their 
retinas  sensitive,  because  red  light  docs  not 
affect  the  rods  or  <ause  tfiein  to  becoim; 
dcscnsiti/ed.  (That  is  why  red  looks  bla<k 
in  rod  vision.) 

A  third  characteristic  of  night  vision  is 
that  objects  become  more  difficult  to  see 
when  they  arc  lookerl  at  directly.  That  is 
[)e(aiise  the  very  center  of  the  retina  is 
blind  at  night;  there  are  no  rods  there. 

1.0 

.•£■0.8 

> 

I  0.6 

I  0.2 

0  — 

700  650  600  550  500  450  400 

Wave  length  (m/i) 

FIGURE     126.       SENSITIVITY    CURVES    FOR    D.WLIGH  I 
AND    NIGHT    VISION 

The  solid  curve  is  the  sensitivity  curve  for  d;iv- 
light  vision,  and  the  dashed  curve  is  for  night 
\ision.  The  curves  show  relative  sensitivity,  and 
hence  brightness,  in  different  parts  of  the  spectnnn 
\\hen  the  light  at  all  wave  lengths  is  of  equal 
energy.  In  daylight  vision  hues  are  seen  at  the 
various  ^\ave  lengths.  In  night  vision  only  grays  of 
different  whitenesses  are  seen. 

You  can  demonstrate  this  fact  bv  setting 
in  a  dark  room  a  source  of  light  Avhich  is 
completely  covered  except  for  two  pin- 
holes a  few  centimeters  apart.  Try  to  fix- 
ate, from  a  distance  of  three  or  foiu"  yards, 
one  of  the  pinholes.  The  light  ^vhich  is 
fixated  "ivill  disappear  -^vhile  the  other 
shows  up  fairly  clearly.  A  shift  of  fixation 
from  one  pinhole  to  the  odier  Avill  make 
the  hole  at  which  you  look  invisible  and 
the  hole  at  which  you  do  not  look  directly 
visible.  "With  fixation  else^vhere  in  die 
field,  both  points  are  visible.  Small  weak 
stimuli  cannot  be  seen  at  all  in  the  center 


292 


Color 


of  the  field  of  vision  where,  in  good  hght, 
details  arc  seen  best.  The  region  in  the 
center  of  the  retina  is  called  the  fox>ea. 
One  of  the  characteristics  of  night  vision 
is  foveal  blindness. 

In  summary  we  may  note  that  niglit  vi- 
sion differs  from  daylight  vision  in  four 
ways.  (1)  All  color  qualities,  except  black, 
gray  and  white,  disappear.  (2)  The  grays 
and  whites  that  remain  are  slightly  tinged 
with  blue.  (3)  The  whitest  colors  at  night 
occur  for  color  stimuli  which  at  normal  in- 
tensities give  yellow-green.  (4)  The  fovea, 
at  the  center  of  the  field  of  vision  and  the 
spot  which  is  most  competent  in  daylight, 
is  blind  at  night. 

PHYSIOLOGY    OF    COLOR 
VISION 

The  eye  is  a  simple  form  of  photographic 
camera  consisting  essentially  of  a  dark 
(liamber  with  a  lens  at  the  front  and  a 
.'.cnsitive  film  (retina)  at  the  back.  (See 
Fig.    127.)     In   front  of  the   lens   is  a  dia- 


Cornea 


Sclerotic 


Choroid 


Optic  nerve 


FIGURE    127.       CROSS-SECTION    OF    THE    HUMAN    EYE 

This  figure  represents  a  cross-section  of  the  right 
eye,  as  viewed  from  aljove.  [.\fter  L.  T.  Troland, 
The  principles  of  psychophysiology,  1930,  II,  p.  98; 
bv  permission  of  D.  \'an  Nostrand  Company.] 


phragm  (pupil)  and  a  shutter  (eyelid).  The 
dark  box  is  approximately  spherical  and  is 
kept  in  shape  by  the  liquid  with  which  it  is 
filled.  The  lens  is  a  relatively  thick  trans- 
parent capsule  filled  with  a  liquid  whose 
refractive  power  is  different  from  that  of 
the  liquid  in  the  dark  chamber.  The 
focus  of  the  lens  is  altered  by  the  ciliary 
muscle,  a  circular  muscle  attached  to  its 
edge,  which  stretches  and  flattens  it  or  al- 
lows it  to  bulge,  according  to  the  distance 
of  the  object  viewed.  The  precise  nature 
of  the  sensitive  membrane,  the  retina, 
which  lies  at  the  back  of  the  dark  chamber 
has  been  studied  by  physiologists  and  psy- 
chologists who  are  interested  in  the  func- 
tioning of  the  eye. 

Microscopic  examination  of  the  retina 
shows  that  it  is  made  up  primarily  of  nerve 
cells  and  their  special  endings.  The  latter 
are  of  two  types.  One,  the  rod,  is  cylindri- 
cal in  form  and  ends  in  a  nerve  fiber  with  a 
cell  body  somewhat  removed  from  the  base 
of  the  rod.  The  other,  the  cone,  is  shorter 
and  thicker  and  somewhat  conical  in  shape, 
and  the  nerve-cell  body  is  incorporated  in 
its  base.  The  nerve  fibers,  which  thus  have 
their  origins  in  the  rods  and  cones,  end 
within  the  retina  in  synaptic  connections 
to  another  set  of  nerve  cells,  the  bipolar 
cells,  which  in  turn  connect  with  a  third 
group  of  gayiglion  cells  with  long  fibers 
which  join  to  form  the  optic  nerve  and 
run  back  to  the  nuclei  in  the  brain  and 
thence  to  the  cortex.     (See  Fig.  128.) 

The  latest  microscopic  examinations 
show  the  neural  connections  at  the  retina 
to  be  very  complex.  A  single  cone  is  con- 
nected to  several  bipolar  cells  and  by  way 
of  them  to  as  many  as  half  a  dozen  ganglion 
cells  whose  fibers  form  the  optic  nerve. 
Some  bipolar  cells  are  connected  to  both 
rods  and  cones  and  all  of  them  run  to  two 


Physiology  of  Color  Vision 


293 


'im 


- — I 


FIGURE    128.      CROSS-SECTION   OF  THE   RETINA 

The  numbers  on  the  left  indicate  different  la)ers  of  the  retina.  The  arrows  indicate  the  direction  in 
which  the  nerve  impulse  travels.  The  rods  (a)  and  cones  (h)  transmit  their  excitations  through  the  vari- 
ous kinds  of  bipolar  cells  (d,  e,  f,  h,  i),  sometimes  across  the  retina  through  horizontal  cells  {c,  I),  to  the 
ganglion  cells  (m,  n,  s,  p,  o),  and  on  through  the  optic  nerve  (lavers  9,  10)  to  the  optic  nuclei  and  the 
visual  cortex.     [From  S.  L.  Polyak,   The  retina,  Chicago:    University   of  Chicago   Press,   1941.1 


or  more  ganglion  cells.  In  addition  there 
are  horizontal  cells  that  connect  one  cone 
with  another  and  with  near-by  rods,  and 
others  that  make  horizontal  connections 
among  the  bipolar  and  ganglion  cells. 
Finally,  there  are  several  different  types 
of  connections   between   the   various   cells. 


It  is  believed  that  all  this  complication  is 
significant  in  the  functioning  of  die  retina, 
not  just  a  matter  of  accident.  After  all. 
in  inany  phenomena  the  retina  is  kno^^^^ 
to  act  as  a  whole  and  not  in  isolated  parts. 
\W&  can,  for  example,  see  pinple  at  the 
periphery  of  the  retina  provided  die  same 


294 


Color 


kind  of  sliinulalion  affeds  all  the  reniain- 
der  of  the  retina. 

Active  sensory  ner\cs  have  been  found 
to  exhibit  electrical  phenomena  in  the 
form  of  changes  in  electrical  potential 
which  give  rise  to  action  currents.  In  re- 
cent experiments  action  currents  have  been 
recorded  from  retinal  elements  in  response 
to  light  stitnuli.  From  them  it  appears 
that  some  retinal  elements— rods  or  cones 
or  both— respond  to  all  ranges  of  light 
stimuli.  Other  retinal  elements,  however, 
respond  to  only  limited  light-wave  ranges. 
Response  to  blue  has  been  definitely  iso- 
lated and  possibly  the  responses  to  green 
and  to  red. 

Since  the  cells  which  give  rise  to  the 
optic  fibers  lie  in  the  innermost  layer  of 
the  retina,  the  fibers,  in  order  to  leave  the 
eye,  must  pass  back  through  the  retina. 
All  the  fibers  come  together  as  they  leave 
the  eye,  producing  a  gap  in  the  retina.  At 
the  corresponding  area  in  the  field  of  \ision 
there  is  but  little  sensitivity,  and  that 
is  the  region  which  is  called  the  blind  spot. 
Since  the  optic  nerve  leaves  the  eye  about 
three  millimeters  to  the  nasal  side  of  the 
center  of  the  eye,  the  blind  spot  lies  to  the 
temporal  or  outer  side  of  the  field  of  vision 
of  each  eye. 

The  diameter  of  the  retinal  blind  spot  is 
about  two  millimeters.  Such  an  area  on 
the  retina  subtends  an  angle  of  about  six 
degrees  in  the  visual  field. 

Duplexity  of  Retinal  Function 

An  adecjuate  account  of  the  way  a  sense 
organ  functions  consists  in  a  careful  cor- 
relation of  the  physiological  and  physical 
facts,  on  the  one  hand,  with  the  parallel 
psychological  data,  on  the  other.  Usually 
not  all  the  necessary  facts  in  both  fields  are 
available,  and  the  psychologist  must  at- 
tempt  to   put   together   the  available   facts 


in  such  a  way  as  to  bridge  the  gaps  in 
knowledge.  Some  of  the  resulting  psycho- 
physiological correlations  are  quite  firmly 
established.  Others  are  tentative.  One  of 
the  best-established  correlations  is  the  prin- 
ciple that  the  retinal  rods  are  the  organs 
of  night  vision  and  the  retinal  cones  the 
organs  of  daylight  vision.  Let  us  sum- 
marize the  facts  by  which  this  correlation 
is  established. 

Vision  is  of  two  kinds.  (1)  First  there 
is  full  color  vision  as  represented  by  the 
color  equation,  (a)  Such  vision  is  maxi- 
mal at  the  center  of  the  field  of  vision  in 
the  region  surroimding  the  point  of  fixa- 
tion, (b)  It  diminishes  in  regions  away 
from  the  central  zone,  losing  first  the  red- 
green  member  of  the  equation  and  then 
the  yellow-blue  member  in  regions  that 
approach  the  periphery,  (c)  Color  vision 
requires  the  relatively  greater  stimulus 
energy  of  daylight  vision.  If  the  energy 
of  the  stimulus  falls  below  a  certain  level, 
color  vision  disappears. 

(2)  Second,  there  is  vision  that  consists 
(a)  only  of  black,  gray  and  white  (modified 
by  bluishness).  [b)  Such  vision  is  com- 
pletely lacking  in  the  center  of  the  field  of 
vision  and  improves  progressively  toward 
the  periphery,  (r)  It  requires  a  relatively 
low  level  of  stimulus  intensity,  the  maxi- 
mum being  slightly  above  the  minimum 
level  for  color  vision.  In  some  cases,  there- 
fore, the  two  visions  overlap,  and  we  can 
then  observe  that  various  stimuli  do  not 
have  the  same  effectiveness  in  both  kinds 
of  vision,  (d)  Red  stimuli  have  no  effect 
in  low-level  vision,  whereas  green  and  blue 
are  relatively  more  effective  than  they  are 
in  color  vision.  Moreover,  (e)  low-level 
vision  is  not  turned  on  immediately  as 
color  vision  is  turned  off,  but  requires  a 
considerable  time  to  appear,  during  which 
dark   adaptation   takes  place. 


Duplexify  of  Vision 


295 


Now,  oil  I  lie  physiological  side,  wc  have 
lound,  firsl,  tliat  llic  retina  contains  two 
distinctive  tyjjcs  ol  nerve  endings,  and, 
second,  that  tliesc  two  endings  have  sig- 
nificant dislribiitions  over  the  surface  of 
the  retina.  Cones  arc  closely  packed  in 
the  fovea  of  the  retina  and  thin  out  toward 
the  periphery.  Rods  are  (ompletely  absent 
from  the  fovea  and  increase  in  number, 
both  absolutely  and  relative  to  the  number 
of  cones,  toward  tlie  periphery. 

Putting  these  two  sets  of  facts  together 
gives  us  what  can  be  called  the  duplexity 
theoiy,  the  generalization  that  the  cones  are 
the  organs  of  daylight  or  color  vision  and 
that  the  rods  are  the  organs  of  night  vision. 

Further  physiological  facts  are  known 
about  the  rods,  facts  which  fit  in  with  psy- 
chological facts  and  tend  to  confirm  the 
duplexity  theory.  A  substance  known  as 
visual  purple  is  found  around  the  ends  of 
the  rods.  Its  chemical  formula  has  been 
determined  and  many  of  its  properties  re- 
corded. It  is  a  highly  unstable  compound, 
related  to  vitamin  A.  It  quickly  decom- 
poses in  the  presence  of  light  and  recom- 
bines  in  darkness,  when  the  proper  sub- 
stances are  present.  The  ideal  conditions 
for  the  formation  of  visual  purple  occur  in 
the  retina  in  total  darkness,  where  its  in- 
crease will  continue  for  a  considerable 
period  of  time.  We  can  conclude,  there- 
fore, that  the  visual  purple  of  the  retina 
acts  as  a  sensitizer  for  the  rods.  In  its  ab- 
sence they  fail  to  respond.  After  a  large 
accumulation  of  it  has  been  built  up,  the 
sensitivity  of  the  rods  is  ten  thousand  times 
that  of  the  cones  in  daylight.  The  rate  of 
the  accumulation  of  visual  purple  within 
the  natural  conditions  of  the  retina  in 
darkness  parallels  the  progress  of  dark 
adaptation.  Since  the  visual  purple  ab- 
sorbs yellow  and  green  light,  it  responds 
more    vigorously    to    those    wave    lengths. 


Correspondingly,  yellow-green  wave  Iciigtlis 
are  seen  in  night  vision  as  whiter  than 
other  wave  lengths,  whereas  red  wave 
lengths  give  no  white;  at  all  and  are  seen 
as  very  dark  or  as  black.  Sudi  a  psycho- 
physiological correlation  affords  an  accept- 
able theory  of  night  vision  in  terms  of  rod 
function. 

By  eliminalion,  then,  (olor  vision  is 
ascribed  to  the  cones  of  the  retina,  fjut 
physiological  facts  concerning  their  func- 
tioning are  insufficient  to  afford  a  detailed 
correlation.  It  has  been  suppcjsed  that 
various  cones  may  contain  differently  se- 
lective photochemicals,  but  no  such  sub- 
stances have  been  isolated  from  the  retinal 
tissue.  Another  hypothesis  supposes  that 
the  various  connecting  cells  respond  dif- 
ferently to  give  qualitative  differences  in 
color.  We  have  noted  that  one  iinestiga- 
tion  has  found  that  the  electrical  discharges 
from  various  retinal  elements  indicate  that 
some  elements  respond  to  all  light  waves 
whereas  others  are  more  selective.  This 
finding  may  mean  that  the  early  theorists 
were  right  in  ascribing  the  differentiations 
among  colors  to  the  retina,  but  there  is 
other  evidence  that  the  nerve  impulses  are 
not  completely  differentiated  until  they 
reach  the  brain.  An  acceptable  psycho- 
physiological theory  of  color  vision  still 
waits  upon  future  discovery. 

REFERENCES 

1.  Bartley,  S.   H.      lision.     New   York:    \an   Nos- 
trand,  1941. 

The  psychophysics  and  psychophysiolog^"  of 
most  of  the  phenomena  of  visual  sensation  and 
perception  except  the  correlates  of  wave  length. 

2.  Graham.  C.  H.  \'ision:  some  neural  correla 
lions.  In  -C.  Murchison  (Ed.1.  A  handbook  of 
i^eueral  experimental  psxclwlogy.  'Worcesier, 
Mass.:   Clark  University   Press,  193 1.     Cliap.   15. 


296 


Co/or 


A  technical  handbook  account  of  the  neural 
mechanisms  involved   in  visual   perception. 

3.  Hecht.  S.  \'ision:  the  nature  of  the  photo- 
receptor process.  In  C.  Murchison  (Ed.),  A 
handbook  of  general  experimental  psychology. 
Worcester,  Mass.:  Clark  University  Press,  1934. 
Chap.   14. 

A  rather  technical  presentation  of  the  physi- 
ological data  which  form  the  basis  for  theories 
of  the  neural  reception  of  light. 

4.  Ladd-Franklin,  C.  Colour  and  colour  theories. 
New  York:   Harcourt,  Brace,  1929. 

Reprints  of  a  score  of  the  author's  more  im- 
portant papers  on  color  theory  and  the  argu- 
ment which  supports  her  genetic  theory  of 
color. 

5.  Parsons.  }.  H.  .In  introduction  to  the  study 
of  colour  vision.  (■2nd  ed.)  Cambridge,  Eng- 
land: Cambridge  University  Press,  1924. 


The  most  complete  handbook  which  reports 
the  basic  investigations  on  color  up  to  1924, 
but  now  out  of  date. 

6.  Troland,  L.  T.  Vision:  visual  phenomena  and 
their  stimulus  correlations.  In  C.  Murchison 
(Ed.),    A    handbook    of    general    experimental 

psychology.    Worcester,  Mass.:  Clark  University 
Press,  1934.     Chap.  13. 

An  excellent  and  precise  summary  of  the 
psychophysical  relation  of  visual  phenomena  to 
visual  stimulation. 

7.  Troland,  L.  T.  The  principles  of  psycho- 
physiology.  New  York:  Van  Nostrand,  1930. 
Vol.  II,  Chap.  14. 

A  full  discussion  of  the  psychophysical  rela- 
tions of  visual  phenomena  to  visual  stimula- 
tion, somewhat  more  complete  than  the  preced- 
ing item. 


CHAPTER 


13 


Visual  Space  Perception 


THE  human  organism  lives  in  three-di- 
mensional space,  orients  itself  in  it,  re- 
acts to  stimulus  objects  in  it  and  is  fully 
aware  of  it  in  all  its  tridimensionality.  It 
has  equipment  for  perceiving  space,  equip- 
ment with  which  heredity  provides  it— eyes 
with  retinas  on  which  a  two-dimensional 
image  of  the  visual  field  can  be  focused,  eyes 
which  can  do  the  focusing,  which  can  con- 
verge more  or  less  toward  each  other, 
which,  being  separate,  get  dissimilar  views 
of  the  world,  which  move  in  the  head,  thus 
changing  the  visual  field.  It  has  a  head  to 
hold  the  eyes  and  to  move  them  around. 
It  has  also  mobile  arms  and  hands  to  ex- 
plore the  immediate  universe  and  to  re- 
spond within  this  universe  to  visual  stimvi- 
lation,  as  well  as  a  mobile  body  to  explore 
the  more  remote  world  and  to  make  more 
responses  to  stimulation.  This  equipment 
the  organism  uses  during  its  early  lifetime 
to  build  tip  its  knowledge  and  awareness 
of  tridimensional  space,  to  learn  how  to  re- 
act with  discrimination  to  objects  in  a 
three-way  visual  field.  The  retinas  could 
not  do  this  job  alone.  They  depend  on 
movements  of  the  eyes  to  make  images 
clear  and  to  gauge  distance,  and  on  move- 


ments of  the  body  and  limbs  to  give  spa- 
tial meaning  to  the  core  of  the  visual  per- 
ception, a  core  which  in  itself  consists  only 
of  a  bidimensional  pattern  of  colors.  We 
have  already  seen  how  a  man  can  learn 
to  react  properly  in  a  three-dimensional 
world  after  he  has  become  accustomed  to 
wearing  special  glasses  which  turn  his 
retinal  images  upside  down  and  right  for 
left  (p.  242).  That  experiment  showed  how 
definitely  the  'visual'  perception  of  space 
depends  on  motor  reactions  to  make  it 
meaningful.  For  instance,  a  visually  per- 
ceived object  is  localized  in  space  when 
you  know  where  to  reach  for  it.  If  \ou 
reach  up  to  get  something  off  the  floor  sim- 
ply because  you  think  the  floor  is  above 
you  (as  you  may  if  you  have  just  put  on 
these  special  glasses),  you  must  learn  some- 
thing before  you  know  your  'visual'  space. 
The  most  siuprising  fact  about  %-isual 
space  perception  is  that,  with  bidimen- 
sional retinas,  we  see  tridimensional  space. 
How  do  we  do  this?  ^Vhere  does  the  third 
dimension  come  from?  At  the  retina  the 
organism  has  stirrendered  one  of  the  three 
dimensions  of  space,  for  only  up-down  and 
right-left    are    directly   represented    in    the 


This  chapter  was  prepared  by  Forrest  L.  Dimmick  of  the  U.  S.  Naval  Medical  Research 
Laboratory  at  New  London. 

The  opinions  or  assertions  contained  in  this  cliapter  are  the  private  ones  of  die  collabo- 
rator and  the  editors  and  are  not  to  be  construed  as  official  or  reflecting  the  views  of  the 
Navy  Department  or  the  Naval  Service  at  large. 

297 


298 


Visual  Space  Perception 


retinal  image.  Yet  in  visual  perception  it 
has  got  back  again  the  lost  dimension.  It 
sees  solid  objects  in  tridimensional  space. 
How  it  has  contrived  to  do  that  is  the  topic 
of  the  first  section  of  this  chapter. 

VISUAL    PERCEPTION    OF    THE 
THIRD    DIMENSION 

You  can   think  of  the  perceiving  organ- 
ism as  instantly  knowing  how  to  build  up 


projected  retinal  image,  the  clues  to  depth 
and  solidity  that  you  can  see  with  one  eye 
or  in  a  photograph. 

Implicit  Clues 

There  are  half  a  dozen  of  these  implicit 
clues  to  tridimensionality  which  merit  spe- 
cial mention. 

(1)  Interposition.  If  one  object  partially 
obscines  another,  it  is  perceived  as  nearer. 
The  instantaneous  operation  of  this  clue. 


FIGURE    129.       INTERPOSITION 


its  picture  of  the  stimulus  world  from  clues 
which  the  senses  furnish  it.  The  organism 
is  an  instantaneous  detective  in  these  per- 
ceptual matters.  It  does  not  reason  its  per- 
ceptions out  and  sometimes  it  makes 
'errors.'  A  standard  habitual  error  we  call 
an  illusion.  Nevertheless  the  organism 
does  well  with  its  clues.  It  has  to  have 
some  basis  for  discriminative  reaction  and 
for  accurate  knowledge,  and  psychology's 
business  is  to  determine  the  character  of 
these  clues  upon  which  the  organism  acts. 
The  stimulation  clues  for  up-down  and 
right-left  perception  lie,  obviously,  in  the 
slinuilation  pattern  itself.  The  clues  to 
adequate  knowledge  of  the  third  dimen- 
sion are  less  direct.  Some  of  them  come 
from  eye  movements  and  some  from  the 
disparity  of  images  in  the  two  eyes,  due  to 
I  heir  spatial  separation;  but  the  simplest 
are  tlie  dues  implicit  in  the  pattern  of  the 


acting  by  itself,  is  evident  in  simple  line 
drawings  like  the  one  in  Fig.  129.  Its  ef- 
fectiveness is  increased  when  the  images 
represent  familiar  objects. 


^^"^^       '     ^-i-'T 

- 

^^^^^^ssfe. 

:r-- 

^^^ 

\x-^ 

3 

^^^^4^ 

FIGURE     130.       I  INF.AR    PERSPECTIVE 

(2)  Size  and  linear  perspective.  The 
larger  representation  of  an  object  appears 
nearer  than  a  small  one.  Linear  persjjec- 
tive  consists  in  grading  the  sizes  of  a  num- 
ber of  objects  to  represent  their  varying 
distances  (Fig.  130).     When  objects  do  not 


clues  to  the  Third  Dimension 


299 


lollow    lliis  iti)pli<it  incliciitioii  ol   distance,  ()|)|josiu-  (lii((  lion.     /\s  \oii  i  iric  in  a  liain, 

dislorlioiis  ol  si/.c  or  ol  dislaiuc  result.  iIk   hir  hills  move  with  you;  llie  near  feruc 

(3)     Aerial    pnspecline.       Objcits     with  posts  snap  hackvvaids,  so  wliat  moves  willi 

sharp  outlines  are  perceived  as  nearer  than  you  is  (ar.      I  hat  is  the  tlue. 

ihosc  that  are  indistiiK  t  or  ha/y.     In  actual  (fi)    I'ixalioii.      Fixated    ohjccts    lend    to 

scenes,    ohjeds   vary    in    perceived    distance  appear    nearer    than    ohjecis    not    lixaled, 

as   (he  changing  clarily  ol    the  atmosphere  hut   olhei    im|jlicit    clues,    like   peispective, 


FIGURE    131.      AERIAL  PERSPECTIVE 


alters  their  sharpness  of  outline  (Fig.  l.Hl). 
On  the  stage,  depth  is  increased  by  inter- 
posing layers  of  netting. 

(4)  Light  and  shade.  Light  is  taken  im- 
plicitly as  coming  from  above.  Thus  high- 
lights on  convex  surfaces  are  near  the  top, 
shadows  below.  Concave  areas  show  the 
reverse.  In  a  photograph  with  strong 
modeling  the  protuberances  and  indenta- 
tions can  be  reversed  by  inverting  the  pho- 
tograph  (Fig.   132). 

(5)  Movement.  Far  objects  appear  to 
move  in  the  same  direction  as  the  observer 
when  he  moves;  near  objects  move  in  the 


often  conflict  with  the  clue  from  fixation. 
It  is  thought  that  fixation  is  a  clue  because 
aerial  perspective  is.  The  fixated  object  is 
clear,  other  objects  are  blurred. 

These  clues  are  deeply  ingrained  in  per- 
ceptions, having  long  histories  in  the  ex- 
perience of  an  organism.  They  are  suffi- 
cient of  themselves  to  give  an  adequate  ap- 
prehension of  nearness  or  farness  of  objects, 
or  to  lead  to  proper  responses  to  the  dis- 
tances of  objects.  Soliditv.  as  perceived  in 
pictorial  art,  is  dependent  upon  the  manip- 
ulation of  such  clues.  The  clues  are  so 
fully  adequate  that  most  persons  have  no 


300 


Visual  Space  Perception 


difficulty  in  seeing  moving  pictures  in  three 
dimensions,  though  the  presentation  is 
only  shadows  on  a  flat  surface.  Moving 
pictures  have  much  more  depth  than  still 
pictures  because  they  move.  The  relative 
movement  of  objects  in  the  picture  gives 
it  great  depth,  which  can  be  achieved   in 


,v-i 

■: -iS^.:„  ' '^i^H 

';.■■  ■  LIHIfite:    .. 

t':-f\cit'^W^^f>fff'f'^^ml^K^^^KSi 

FIGURE   132.      INFLUENCE  OF  LIGHT  AND  SHADE 

The  dents  in  the  monitor's  turret  appear  as  dents 
if  the  light  seems  to  come  from  above,  and  turn 
into  bulges  if  this  page  is  turned  upside  down, 
provided  the  light  still  seems  to  come  from  above. 
If  the  light  can  be  imagined  as  streaming  up  from 
below,  the  dents  tmn  into  bulges  without  inverting 
the  page.  [Reprinted  bv  permission  of  C.  H.  Stoel- 
ting.  Chicago.] 

Still   scenes   by   moving   the   movie   camera 
while  taking  the  picture. 

Motor  Context 

Accurate  vision  involves  constant  motor 
adjustment  of  the  eyes  to  the  distances  of 
the  stimulating  objects.  Though  only  a 
single  visual  field  is  seen,  the  two  eyes 
must  be  aimed  coordinately  in  the  right 
direction.  This  adjustment  requires  a  pat- 
tern of  muscular  contractions  anci  tensions 
characteristic  of  every  distance.  It  is  gen- 
erally believed  that  these  contractions  and 
tensions  give  rise   to  proprioceptive  clues 


to  the  distance  of  a  fixated  object.  The 
clues  could  come  from  the  convergence  of 
the  two  eyes  upon  the  object— con\ergence 
—or  from  the  focusing  of  a  single  eye  upon 
the  object— accommodation. 

Convergence.  When  the  two  eyes  look 
at  a  distant  object,  their  lines  of  vision  are 
]:)arallel  and  the  muscles  that  move  them 
are  relatively  relaxed.  When  the  object 
moves  in  nearer  than  fifty  to  sixty  feet  in 
front  of  the  observer,  his  eyes  must  be 
pulled  out  of  their  parallel  position  so  that 
the  lines  of  vision  converge  and  intersect. 
A  new  pattern  of  muscular  pulls  is  rc- 
cjuired,  which  may  provide  a  propriocep- 
tive clue  for  the  perception  of  that  dis- 
tance. Certainly  the  clue  is  there.  The 
only  doubt  is  whether  the  observer  actually 
has  the  proprioception  to  make  the  clue 
available  to  him.  He  is  not  directly  con- 
scious by  somesthetic  sensation  of  the  con- 
vergence of  his  eyes,  but  not  all  proprio- 
ception is  somesthesis.  Some  is  effective 
without  becoming  conscious.  (See  Fig. 
133.) 


(a) 

FIGURE    133.      LINES   OF   SIGHT 

In  (a)  the  lines  of  sight  are  directed  toward  the 
horizon.  In  (b)  they  are  converged  upon  a  near  ob- 
ject. 

Accommodation.  In  fixating  an  object 
the  lens  in  each  eye  must  accommodate  its 
focus  to  produce  a  clear  image  of  the  ob- 
ject on  the  retina,  and  this  movement,  if 
it  gives  rise  to  proprioception,  would  fur- 
nish a  further  clue  to  distance.  (See  Fig 
1.34.) 


Convergence,  Accommoc/afion  and  Retinal  Disparify 


301 


Normally  actoiiiiiiodalion  ami  conver- 
gence work  together  to  jjroduce  sharp 
images  on  the  corresponding  jjarts  of  the 
two  retinas.  When  they  do  not  cooperate, 
vision  is  impaired  but  can  be  restored  by 
correcting  either  factor.  If,  for  a  given 
distance,  the  eyes  converge  too  near  for  tlie 
correct  focus,  or  focus  too  near  for  the  cor- 
rect convergence,  the  insertion  of  lenses  to 
correct  the  focus  or  prisms  to  bend  the  lines 
of  vision  to  the  proper  angle  will  correct 
the  visual  defect. 

Accommodation  appears  to  contribute- 
less  than  convergence  to  the  perception  of 
distance.  When  convergence  is  partially 
removed  by  closing  one  eye,  it  becomes  dif- 
ficult to  judge  accurately,  by  accommoda- 
tion alone,  the  distances  of  near  objects  and 
impossible  for  objects  more  than  six  feet 
away.  One-eyed  people  must  depend  upon 
the  implicit  clues  to  a  much  larger  degree 
than  those  with  two  eyes  and  are  greatly 
handicapped  when  these  clues  are  lacking. 
For  this  reason,  monocular  vision  is  not 
considered  adequate  for  airplane  pilots, 
and  even  pilots  with  binocular  vision  must 
be  carefully  tested  for  ability  to  judge  dis- 
tance accurately  when  the  only  available 
clues  are  accommodation  and  convergence. 

As  we  liave  already  noted,  it  is  character- 
istic of  an  organism  that  its  motor  re- 
sponses become  stereotyped  with  repetition 
and  that  an  habitual  action  gives  meaning 
to  the  object  or  situation  which  touched  it 
off.  Accommodation  and  convergence  are 
no  exceptions  to  this  rule.  Most  of  the 
time  our  eyes  aim  and  focus  themselves 
automatically,  making  our  perception  of 
distance  immediate  and  implicit.  The  first 
responses  that  make  the  perception  a  mean- 
ingful whole  are  these  focusings  and  con- 
vergences. After  them  come  the  other  re- 
actions to  complete  the  sense.  I  want  my 
pen.    Vaguely  I  see  it  lying  on  the  desk  in 


fiont  (jf  me.  At  once  and  automatically 
my  eyes  fixate  it,  focus  on  it,  converge  on 
it.  Tlien  I  verify  my  perception  of  loca- 
tion, for  I  reach  out  and  take  it,  my  hand 
finding  tfie  pen  at  cjnce.  All  that  seems  scj 
easy  and  natural,  and  yet  it  is  part  of  the 
learned  structure  of  perception.  If  I  had 
newly  put  on  those  special  reversing  spec- 
tacles, the  perception  would  start  cjff  in 
the  familiar  way,  but  presently  my  hand 
would   be   "rc;ninii    vainly   for   the    pen    bc- 


(o)  (6) 

FIGURE     134.       THE    ACCOMMODATION    OF    THE    EVE 

In  (a),  with  the  lens  more  convex,  the  images  are 
in  focus  on  the  retina.  In  (b)  the  focus  lies  behind 
the  retina  so  that  the  images  intercepted  fjv  the 
retina  are  out  of  focus. 

cause    the   visual    clues   set   off   the   wrong 
reaching  behavior. 

Retinal  Disparity 

The  fact  that  the  eyes  are  set  some  2i.', 
inches  apart  means  that  the  two  retinal 
pictures  of  an  object  are  never  identical. 
Only  the  point  fixated  and  a  fe^\-  others  will 
be  projected  upon  identical  points  on  die 
retinas.  Everywhere  else  the  two  eyes, 
viewing  the  scene  from  different  positions 
at  different  angles,  get  somewhat  different 
vie^vs.  This  difference  in  the  geometrv'  of 
seeing  is  called  binocular  parallax,  and  the 
resultant  difference  in  the  two  retinal 
images  is  called  retinal  disparity.  Most  of 
the  pattern  that  falls  on  your  retinas  at 
any  one  time  you  'ought'  to  see  doubled, 
because  corresponding  lines  in  the  pattern 
do  not  fall  on  corresponding  lines  in  your 
retinas.  But  you  do  not.  These  doubled 
images  do  not  remain  distinct  and  dispar- 
ate for  perception.     Instead,  thev  integrate 


302 


Visual  Space  Perception 


into,  and  arc  perceived  as,  solid  or  tridi- 
mensional. ^Vithin  limits  the  greater  dis- 
parity gives  the  greater  depth  or  solidity. 
Here,  if  ever,  you  have  a  rase  of  the  ef- 
fective operation  of  unconscious  clues.  The 
disparity  can  be  of  two  kinds.     (See  Fig. 


I  IGURE    135.       DOUBLE    IMAGES 

111  (fl)  the  double  images  of  A^,  a  point  nearer 
than  the  point  of  fixation,  X,  are  seen  at  NR  and 
NL.  In  (b)  the  double  images  of  F,  a  point  farther 
away  than  X,  are  seen  at  FR  and  FL. 

135.)  If  you  look  at  a  tree,  X,  in  the  mid- 
dle of  a  grove,  a  nearer  tree,  N,  will  have 
disparity  in  one  direction,  but  a  far  tree, 
F,  will  have  the  disparity  reversed.  The 
clues  to  distance  depend  on  which  eye  sees 
which  image.  You  yourself  are,  however, 
wholly  unconscious  of  what  it  is  that  you 
see  with  one  eye  and  what  with  the  other. 
(You  can  figure  it  out  by  closing  one  eye 
and  seeing  what  is  left  in  the  scene,  and 
then  trying  out  the  other  eye,  but  that  is 
an  elaborate  inference,  not  the  inference 
of  immediate  automatic  perception.)  Yet 
the  clues  woik,  even  if  you  are  not  im- 
mediately aware  of  them,  lliey  enable 
yoin-  brain,  without  your  knowing  how  it 
works,  to  'decide'  what  is  near  and  what 
far,  and  to  build  up  space  perception  in 
accordance  with  what  actually  exists  in  the 
stimulus  world  outside.  That  is  how  two 
bidimensional  retinas,  working  together, 
can  between  them  get  back  the  third  di- 
mension which  thev  seemed  to  have  lost. 


Stereoscopy 

While  the  best  depth  perception  is  ob- 
tained by  the  cooperation  of  all  three  of 
the  factors  we  have  just  discussed,  the  two 
proprioceptive  factors  can  be  eliminated 
and  an  excellently  deep  and  solid  percep- 
tion obtained  merely  from  two  fiat  dis- 
parate pictures,  presented  each  to  its  ap- 
propriate eye.  This  is  accomplisheci  by  a 
device  known  as  a  stereoscope.  Two  pho- 
tographs (stereograms)  are  taken  at  a  cer- 
tain distance  apart  and  are  then  presented 
so  that  the  right  eye  sees  only  the  right 
picture  and  the  left  eye  only  the  left  pic- 
ture. The  two  views  are  then  integrated 
by  the  brain  into  a  single  perception  that 
is  solid  or  tridimensional. 

Figure  136  shows  how  a  hollow  truncated 
cone  looks  to  each  eye  when  the  cone  is 


Small  end  protruding 


Small  end  receding 


Left  eye         Right  eye 

view  view 

(a) 


Left  eye  Right  eye 

view  view 

(6) 


FIGURE    136.      TRUNCATED    CONE   AS   SEEN    BY    EACH 
EYE    SEPARATELY 

The  small  circles  represent  the  small  end  of  a 
hollow  truncated  cone,  the  large  circles  the  large 
end,  the  straight  lines  the  sides.  In  (n)  are  shown 
the  views  for  each  eye  when  the  small  end  of 
the  cone  Is  near  the  observer;  in  (b)  the  views 
for  the  two  eyes  when  the  large  end  of  the 
cone  is  near  the  observer.  The  retinal  disparity 
for  (h)  would  be  the  reverse  of  that  for  (a).  It  is 
also  proper  to  regard  (a)  and  (b)  as  two  pairs  of 
stereograms  which,  being  reversed,  would  give  op- 
posite depths  in  perception. 

held  near  the  face  and  binocular  parallax 
is  great.  If  these  two  drawings,  each  of  a 
pair  of  images,  are  used  as  a  stereogram 
in  a  stereoscope,  you  see  down  into  a  hol- 
low cone  for  the  disparity  shown  at  the 
left  of  the   figure,  and  you  see  a  convex 


Stereoscopy 


303 


(oiic  lapered  toward  you  for  the  disparity 
at  the  right.  Figure  137  shows  how  binoc- 
ular parallax  gives  retinal  disparity.  The 
two  eyes  look  at  the  cube  A,  and  the  left 
eye  sees  the  image  li  while  the  right  eye 
sees  the  image  C.      The  dotted  lines  show 


D   a 


'a7- 


BINOCULAR    PARALLAX    AND    RETINAL 
DISPARITY 


./  shows  how  binocular  paralle,\  gives  to  each  eye 
a  different  image  of  a  cube.  B  and  C  show  what 
I  he  linages  in  the  two  eyes  are  like.  [From  E.  G. 
Boring  (Ed.),  Psychology  for  the  armed  services.  In- 
fantry Journal,  1945,  p.  41.] 

why   the  views   that   the   two   eyes   get   are 
different. 

If  desired,  solidity  can  be  exaggerated  in 
stereoscopic  vision.  You  will  perceive  an 
exaggerated  depth  if  the  two  photographs 
are  taken  at  a  distance  apart  which  is 
greater  than  the  distance  between  the  two 
eyes  (21^  inches).  Separating  the  cameras 
^v'hich  make  the  picttires  by  more  than  2% 
inches  exaggerates  the  binocular  parallax, 
and  thus  the  retinal  disparity,  and  thus 
the  perceived  depth.  In  fact  this  method  can 
be  used  to  reveal  small  differences  in  tlie 
distances  of  objects  whicli  are  both  miles 
away.  It  is  then  called  telestereoscopy.  In 
war,  to  find  out  which  airplanes  are  flat 
dummies  and  which  are  solid  and  real, 
camouficurs  in  airplanes  at  great  altitudes 


take  telestereoscopic  pictures  of  the  ground 
in  order  to  distinguish  the  heights  of 
(ainouflaged  objects  on  the  ground. 

The  stereoscope,  by  means  of  which  the 
stereograms  are  observed,  uses  either  a 
pair  of  lenses  (as  in  Fig.  138)  or  a  pair  of 
mirrors  to  bend  the  lines  of  vision  of  the 
two  eyes  so  that  the  two  stereograms  tan 
be  shown  individually  to  the  proper  eyes 
while  they  are  converged  normally  at  a 
point  some  convenient  distance  in  front. 
Naturally,  if  the  stereograms  are  re\ersed 
so  that  the  left  eye  sees  what  was  the  right 
pictine,  and  vice  versa,  a  pseudoscopir  ef- 
fect will  be  produced;  near  things  look  far 
away  and  far  things  near,  providing  the 
implicit  clues  are  not  too  dominant.  If 
they  are,  the  result  is  usually  confused  or 
flat.  By  reversing  the  stereograms,  \ou 
can  make  the  outside  of  a  teacup  look  like 
an  inside,  you  can  make  a  tennis  ball  look 
like  a  cup,  you  may  even  make  the  face  o( 


FIGURE    138.      BREWSTER  STEREOSCOPE 

The  double  stereogram  goes  in  the  card  hoKler. 
Each  eye  sees  but  one  drawing  or  photograph.  The 
lenses  allow  the  eyes  to  converge  so  that  the  two 
images  combine. 

a  plaster  bust  look  like  a  death  mask,  but 
you  cannot  turn  a  liimian  mobile  face  con- 
cave. There  the  implicit  clues  are  too 
strong  for  pseudoscopy  to  work. 

You  can  get  this  same  reversal  of  the 
third    dimension     by    looking    at    objects 


304 


Visual  Space  Perception 


through  a  system  of  lenses  called  a  pseudo- 
scope,  which  re\erscs  the  images  to  the  two 
eyes. 

VISUAL    PERCEPTION    OF    SIZE 

The  most  obvious  determinant  of  vis- 
ually perceived  size  is,  of  course,  the  size 
of  the  retinal  image,  which  stands  in  a 
fixed  relation  to  the  size  and  distance  of  the 
object.  It  is  customary  to  state  this  rela- 
tion in  terms  of  visual  angle.  (See  Fig.  91, 
p.  232.)  To  maintain  a  constant  visual 
angle,  and  thus  constant  size  of  retinal 
image,  the  size  (width,  diameter)  of  ob- 
jects must  vary  directly  as  the  distance  of 
the  objects  from  the  e)e.  With  an  object 
of  constant  size,  the  size  of  the  visual  angle 
varies  inversely  as  the  distance  of  the  ob- 
ject. Thus,  from  a  knowledge  of  the  physi- 
cal size  of  an  object  and  of  its  distance 
from  the  eye,  we  can  calculate  the  approxi- 
mate size  of  the  image  which  it  produces 
on  the  retina;  and,  on  the  basis  of  this  rule, 
-^ve  can  predict  how  large  the  object  ought 
to  look  at  any  given  distance  if  its  size 
were  determined  solely  by  visual  angle. 
That  is  the  rule  for  perceived  size  that 
Euclid,  the  geometrician,  laid  down  in  his 
Optics  over  two  thousand  )ears  ago. 

Perceived  Size  and  Perceived  Distance 

Euclid  was,  howe\er,  wrortg,  as  we  al- 
ready know  from  the  facts  of  object  con- 
stancy (p.  231).  Under  ordinary  conditions 
the  perception  of  size  deviates  from  Eu- 
clid's law.  A  negative  afterimage,  lor  in- 
stance, since  it  subtends  a  constant  vis- 
ual angle,  has  constant  retinal  size  and 
shotdd  therefore,  tmder  Euclid's  law,  remain 
constant  in  perceived  size;  nevertheless  it 
appears  to  get  larger  with  each  increase 
in  the  distance  at  which  the  afterimage  is 
projected.    Its  si/c  is  dctcrniiiucl  not  by  the 


visual  angle  and  retinal  image,  but  by  the 
percei\'ed  distance  of  the  projected  siuface. 
Con\'ersely,  if  we  look  at  two  objects  of  the 
same  physical  size,  but  at  different  dis- 
tances, the  nearer  object,  with  the  bigger 
retinal  image,  looks  no  larger  than  the  far- 
ther object.  This  is  the  principle  of  size 
co7istancy,  a  case  of  object  constancy,  a 
principle  which  holds  within  wide  limits. 

If,  on  the  other  hand,  we  view  two  ob- 
jects with  one  eye  looking  through  holes  in 
a  screen,  cut  in  such  a  way  that  the  condi- 
tions for  the  perception  of  distance  have 
all  been  eliminated,  we  find  that  the  ob- 
ject which  produces  the  smaller  retinal 
image  will  also  appear  to  be  smaller.  Ap- 
parently, then,  the  constancy  of  size  is  a 
special  case  of  the  relationship  between 
perceived  size  and  perceived  distance.  Au- 
toiuatically  the  organism  makes  an  adjust- 
ment of  the  perceived  size  which  allows  for 
the  changes  in  perceived  distance.  The 
screen  with  the  holes  in  it  is  the  reduction 
screen.  (See  p.  235.)  Here  it  reduces  the 
sensory  core  of  the  perception  to  the  retinal 
image,  eliminating  all  the  clues  to  dis- 
tance by  which  retinally  determined  size 
might  be  corrected  by  the  brain. 

Nor  does  the  principle  of  size  constancy 
hold  at  all  distances.  It  fails  for  small  ob- 
jects—such as  a  coin— when  held  within  a 
few  centimeters  of  the  eye  and  for  large 
objects  at  great  distances.  A  man  talking 
to  you  and  five  feet  away  is  not  five  times 
as  tall  as  the  man  twenty-fi^■e  feet  away,  for 
size  constancy  holds  appioximately;  but 
the  man  way  down  the  street  or  across  the 
valley  may  be  a  tiny  little  creature.  A  fa- 
miliar object  will,  other  things  being  equal, 
remain  constant  in  size  over  a  greater  range 
of  distances  than  an  unfamiliar  object.  In 
general,  then,  you  expect  constancy  of  size 
for  a  middle  ramre  of  distances.     Witliin 


Visual  Perception  of  Size 


305 


tlial,  range  familiarity   willi   llic  object   in- 
creases constancy. 

Perceived  Size  and 
Surrounding  Objects 

The  relationship  between  si/e  and  dis- 
tance is  one  of  many  instances  in  which  the 
specific  perception  of  things  is  determined 
by  their  situations.  If  an  object  appears 
at  a  great  distance,  as  in  a  [perspective  draw- 


FIGURE    139.      INFLUENCE  OF  LINEAR  FIGURE  TAKEN 
AS  A  WHOLE   UPON   THE  SIZE  OF   ONE   OF   ITS   PARTS 

ing  (see  Fig.  130,  p.  298),  its  size  corresponds 
approximately  to  that  distance. 

The  principle  holds  also  for  bidimen- 
sional  situations.  The  line  AX  in  Fig. 
139r/,  appears  longer  than  the  line  AY:  the 
former  is  apprehended  as  the  diagonal  of 
a  larger,  and  the  latter  as  the  diagonal  of 
a  smaller  parallelogram.  Similarly,  in  Fig. 
159b  the  difference  in  size  between  the  two 
circles  must  be  referred  to  the  influence  of 
the  included  and  excluded  lines.  In  the 
familiar  arrowhead  illusion  (Fig.  140rt)  the 
line  c  appears  longer  than  d  because  it  is 
a  part  of  the  larger  area  suggested  by  the 
direction  of  the  arrowheads.  Similarly,  in 
Fig.  \40b  it  is  almost  impossible  to  see  the 
distance  between  the  outer  limits  of  circles 


A  and  li  as  ecjual  to  the  distance  between 
the  right  extreme  of  li  and  the  left  ex- 
treme of  C.  The  perception  of  the  circles 
as  objects  constrains  us  to  perceive  the  dis- 


(6> 


0 


FIGURK   140.       EKKECJT  OF  A  TOTAL   FIGLRK  UPON   AN 
ISOLATED    LINEAR    DISl  A.NCE 

In  (a)  the  distance  c  ec]uals  the  distance  d.  In 
(b)  the  right  side  of  B  is  equidistant  from  the  left 
side  of  A  and  the  left  side  of  C.  In  'c)  there  is  a 
true  circle  which  looks  flattened. 

tance  as  between  circle  and  circle  rather 
than  as  between  point  and  point.  In  Fig. 
141  the  lower  object  looks  shorter  than  the 
upper  object,  possibly  because  of  a  con- 
trast between  the  short  upper  line  of  the 
lower  figure  and  the  long  lower  line  of  the 


FIGURE     141.       SPAIIAL    CONTR,\ST 

The  lower  figure  looks  shorter  and  stumpier. 

upper  figure,  possiblv  because  of  a  perspec- 
tive effect   induced  by  the  convergence  of 
the  straight  lines  at  the  two  extremes. 
^Vithin  limits  even  such  factors  as  white- 


306 


Visual  Space  Perception 


iiess  may  fuiu  tioii  as  determinants  of  size. 
Jf  two  equal  scjuares,  one  black  and  one 
white,  arc  jilaced  side  by  side  against  a 
gray  ground,  the  white  will  usually  appear 
larger  than  the  black.     DifFerenccs  in  hue 


^  IN 

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idt 


I  IFF 


UGL'RE    142.      ANGI.K  II.I.USIONS 

Distortion  of  siiniuhl  IIik-s  ;m(i  |);u;illcis  l)y  sui- 
rouiicling  olijctls. 

may  also  have  an  effect  on  aj^parent  size. 
To  most  people  a  red  object  will  appear 
slightly  larger,  and  nearer,  than  an  equally 
bright  blue  object,  and  in  some  patholog- 
ical cases  such  differences  become  pro- 
nounced. The  apparent  distance  of  color 
is  sometimes  used  by  artists  in  obtaining 
depth  in  their  pictures. 

Apparent  shape  and  direction  of  lines 
arc  similarly  modified  by  smrounding  ob- 
jects   that  set   up   imjilicit   pcneptual    atti- 


tudes. Because  of  the  tendency  to  perceive 
all  objects  as  tridimensional,  lines  in  a 
drawing  that  cross  each  other  at  ol)lic[uc 
angles  aie  taken  imj^licitly  to  represent 
right  angles  extending  into  spate.  For  ex- 
ample, a  vertical  line  with  several  oblique 
cross-lines  is  perceived  as  if  set  at  an  angle 
to  the  frontal  plane  like  a  telegraph  pole 
with  cross-arms.  Similarly,  all  acute  angles 
tend  to  be  overestimated  and  all  obtuse 
angles  tend  to  be  imderestimated,  making 
them  approach  right  angles.  Even  in  draAv- 
ings  to  which  perspective  perception  does 
not  apply,  distortion  in  direction  of  the 
lines  takes  place.  Many  of  the  so-called 
visual  illusions  are  of  this  sort.  Some  of 
them  are  shown  in  Fig.  142.  (See  also  Fig. 
1,  p.  6.) 

Visual  Acuity 

The  smallest  object  that  can  be  seen  de- 
pends upon  several  variables.  A  white  spot 
on  a  black  groiuid  in  sunlight  can  just  be 
seen  when  it  subtends  an  angle  of  about 
10  to  12  seconds  of  arc;  a  black  spot  on  a 
white  ground  in  diffuse  daylight  requires 
an  angle  of  25  to  36  seconds.  Similar  val- 
ues have  been  determined  for  the  smallest 
perceptible  degree  of  separation  between 
two  objects,  a  determination  which  de 
pends  iqDon  a  niunber  of  different  factors, 
The  sidewise  displacement  of  two  vertical 
lines,  placed  end  to  end,  may  be  perceived 
when  the  ends  are  displaced  by  an  amoimt 
etjuivalcnt  to  a  visual  angle  of  only  2  sec- 
onds. 

The  separation  between  points  in  space 
must,  however,  be  larger  in  order  to  be  per- 
ceived. In  a  well-lighted  room  two  black 
dots  can  just  be  seen  as  two  when  they  are 
separated  by  an  angle  of  60  seconds.  In 
abnormally  high  or  abnormally  low  il- 
huninations  the  angle  must  be  increased,  as 
it  must  also  if  lines  arc  sul)stilulcd  for  the 


Form  and  Movement 


307 


(lots  and  the  separation  is  ajjprehendecl  as 
a  gap  in  an  otherwise  complete  figure. 

The  threshold  ol  CA)  seconds  or  1  minute 
of  arc  for  the  just  noticeable  separation 
has  been  accepted  by  the  cKulist  as  the 
standard  visual  acuity  for  normal  vision. 
If  the  eye  can  see  a  letter  the  distance  be- 
tween whose  parts  (for  example,  the  hori- 
zontal bars  of  the  test  letter  E)  subtends 
an  angle  of  60  seconds,  it  is  in  that  respect 
considered  normal.  If,  on  the  other  hand, 
the  angle  subtended  by  the  parts  of  the 
letter  must  be,  say,  120  seconds  before  the 
letter  can  be  distinctly  seen,  visual  acuity 
is  said  to  be  one-half  normal.  The  test 
letters  are,  of  comse,  always  shown  under 
good  illumination. 

VISUAL    PERCEPTION    OF 
MOVEMENT 

When  we  look  fixedly  at  the  minute 
hand  of  a  watch  we  see  no  movement;  but 
if,  after  a  brief  interval,  we  look  at  the 
watch  once  more,  we  observe  the  hand  in  a 
new  position.  We  perceive  a  change  in  po- 
sition but  not  a  continuous  change.  When 
we  see  an  athlete  doing  a  standing  broad 
jump,  on  the  contrary,  we  see  him— as  we 
saw  the  hand  of  the  watch— first  in  one 
place,  then  later  at  another  place;  but,  in 
addition,  we  see  him  moving  or  changing 
his  position  from  one  place  to  another.  It 
is  the  perception  of  this  continuous  change 
in  position  of  an  object  that  is  called  the 
perception  of  movement. 

General  Conditions  for 
Perceived  Movement 

Usually  the  visual  perception  of  move- 
ment depends  upon  the  displacement  on 
the  retina  of  an  image  of  the  moving  ob- 
ject. There  are  exceptions.  Movement 
in  the  near-far  dimension   may  occur,   as 


when  the  approach  oi  an  cjbject  is  indicated 
\)y  an  increase  in  its  brightness  (lights  cjf  an 
apprc;aching  autcjmc>bile),  in  its  distinct- 
ness (ship  coming  toward  you  through  the- 
fog)  or  in  its  size  (an  approaching  object;. 
Watch  a  streetcar  as  it  comes  along  toward 
you  through  an  empty  street  from  too  far 
away  for  the  law  of  size  constancy  to  apply. 
It  gets  bigger  and  bigger,  by  little  jumps, 
and  you  see  this  increase  in  size  as  a  move- 
ment of  appioach. 

All  seen  movement  is,  of  course,  relative. 
It  occurs  with  respect  to  some  frame  of  ref- 
erence. So  the  clouds  scurry  across  the  face 
of  the  moon;  or,  if  the  larger  object  be- 
comes the  frame  of  reference  for  the  smaller 
—and  that  is  quite  usual— the  moon  scur- 
ries behind  the  clouds  (as  was  stated  on  p. 
239).  When  the  movement  is  a  simple 
displacement,  the  initial  position  of  the 
object  may  be  the  frame  of  reference.  That 
is  what  happens  when  a  spot  of  light  is  seen 
to  move  in  the  dark.  \Vith  continuous 
movement  of  an  object,  its  background  and 
the  surrounding  objects  become  important 
and  ordinarily  furnish  the  frame  of  refer- 
ence. 

Frequently  you  have  to  include  yourself 
in  the  system  of  relations  which  determines 
seen  movement.  You  sit  in  the  train  in  the 
station  watching  the  other  train,  and  all  at 
once  you  feel  yourself  begin  to  move  back- 
ward, because  the  other  train,  not  yours, 
has  started  to  move  forward.  You  rise 
from  the  ground  in  an  airplane,  and  sud- 
denly you  are  not  rising;  instead  you  see  the 
ground  falling  away  below  you.  There 
are  no  simple  rules  that  say  which  part  of 
the  system  will  be  the  frame  of  reference 
and  which  the  moving  object,  but  it  is 
clear  that  the  system  can  include  the  per- 
ceiving organism  and  that  the  visual  per- 
ception of  movement  is  not  dependent 
solely  on  visual  factors.     If  the  other  train 


308 


Visual  Space  Perception 


makes  you  see  that  you  and  your  own  train 
are  moving,  then  you  both  see  your  train 
moving  and  feel  yourself  moving. 

Other  complications  arise  because  the 
eyes  tend  to  fixate  a  moving  object  when 
it  is  the  center  of  attention.  The  conse- 
quence is  that  the  image  of  the  object  does 
not  move  across  the  retina  because  the  eyes 
move  with  the  object.  Instead  the  image 
of  the  stationary  background  moves  on  the 
retina,  looking  blurred.  It  is  really  quite 
remarkable  how  well  the  neural  coordina- 
tions take  care  of  fixation  when  the  head 
moves.  You  can  watch  a  bird  on  a  limb 
and  move  your  body  and  head  as  you  will, 
and  your  eyes  remain  fixed  on  the  bird. 
Moving  your  head  does  not  spoil  your  fix- 
ation for  a  moment.  You  do  not  have  again 
to  adjust  your  eyes  after  you  have  moved 
your  head.  The  same  innervation  that 
moves  the  head  moves  the  eyes  compensa- 
torily,  so  that  they  stay  still  with  respect  to 
the  bird.  When  the  bird  flies  off,  you  can 
still  watch  him,  your  eyes  moving  and  con- 
verging to  keep  fixation,  and,  if  you  move 
your  head  then,  compensation  stays  just  as 
good. 

There  are  really  two  different  ways  in 
which  movement  across  the  field  of  vision 
is  perceived.  (1)  The  bird  flies  across  the 
field.  Your  eyes  follow  him.  Other  ob- 
jects look  blurred.  The  bird  has  been  seen 
to  move.  (2)  The  bird  flies  across  the  field. 
Your  eyes  remain  fixed  on  the  distant  tree. 
The  tree  and  most  of  the  objects  in  sight 
are  clear.  The  bird  is  blurred,  because 
your  eyes  did  not  follow  him;  nevertheless 
you  saw  him  move.  (3)  The  bird  sits  on 
the  fence.  You  move  your  eyes  along  the 
top  of  the  fence.  Everything  is  blurred 
(except  when  your  eyes  stop  momentarily). 
Nothing  seems  to  move.  Your  eyes  are 
moving,  but  you  do  not  think  about  that. 

How  the  brain  puts  these  clues  together 


in  perceiving  movement  is  not  clear,  but 
put  them  together  it  does.  Here  there  are 
really  five  items  that  can  change  position 
in  relation  to  each  other:  (1)  the  object  of 
attention,  (2)  the  visual  frame  of  reference 
for  the  object,  (3)  your  eyes,  (4)  your  head 
and  (5)  your  body.  Proprioception,  a 
great  deal  of  it  unconscious,  tells  your 
brain  what  your  eyes,  head  and  body  are 
doing.  If  you  are  fixating  an  object— and 
almost  certainly  you  are— your  brain  has 
already  arranged  to  have  your  body  and 
head  movements  compensated  by  your  eye 
movements.  The  retinal  sensations  tell 
you  what  the  retinal  image  of  the  object 
is  doing  in  relation  to  the  retinal  image 
of  the  other  things  that  make  up  the  frame 
of  reference.  Any  wise  man  could  figure 
out  what  the  object  is  doing  with  respect 
to  any  frame  of  reference,  if  he  had  all 
these  clues.  The  brain  has  the  clues,  solves 
the  problem  and  puts  the  answer  into  per- 
ception. The  wonder  is  that  it  does  the 
job  so  immediately  and  accurately,  and 
does  it  without  setting  up  any  conscious- 
ness of  the  process  by  which  it  works. 

Afterimages  of  Movement 

If  you  look  fixedly  for  fifteen  or  twenty 
seconds  at  a  slowly  rotating  white  disk 
upon  which  has  been  drawn  a  heavy  black 
spiral  line,  the  disk  will  seem  to  contract 
or  expand,  depending  upon  the  direction 
of  rotation  of  the  spiral.  If  you  then  turn 
your  eyes  away  and  fixate  a  person's  face, 
the  face  too  will  appear  to  expand  or 
shrink  depending  upon  the  direction  of  ro- 
tation of  the  spiral.  Similarly  if  you  look 
steadily  for  a  minute  at  a  waterfall  or  at  a 
flowing  stream,  and  then  glance  away  at 
the  landscape,  the  latter  will  appear  to  flow 
in  the  opposite  direction.  If  you  are  rid- 
ing on  the  rear  platform  of  a  train  which 
suddenly   stops,    you    notice    that    the    for- 


Visual  Perception  of  Movement 


309 


nicriy  shrinking  ;iii(l  receding  objects  ap- 
pear to  broaden  or  come  nearer.  In  short, 
under  certain  conditions  a  movement  pro- 
duces an  atter-eficct  which  manifests  itself 
as  a  movement  in  the  opposite  direction. 
The  velocity  of  the  afterimage  of  move- 
ment corresponds  roughly,  but  by  no  means 
exactly,  to  the  relative  velocity  of  the  mov- 
ing object. 

We  see  here  that  perceived  movement 
exists  in  experience  in  its  own  right.  It 
does  not  consist  necessarily  in  the  displace- 
ment of  an  object,  for  some  of  these  move- 
ments move  without  getting  anywhere. 
The  rotating  spiral  keeps  expanding,  and 
yet  is  not  found  to  have  become  bigger. 
You  watch  the  waterfall  and  then  look  at 
tlie  rocks.  They  are  seen  to  keep  moving 
up  and  up  and  up,  and  yet  they  never  get 
away  from  where  they  were.  There  must 
be  a  physiological  label  for  movement 
which  the  brain  puts  on  to  that  part  of  a 
perception  which  is  not  the  frame  of  refer- 
ence. 

Perceived  Movement  with 
a  Moving  Stimulus 

A  stimulus  must  travel  a  minimal  dis- 
tance before  movement  is  perceived,  a  dis- 
tance depending  in  part  on  the  rate  at 
which  the  stimulus  travels.  It  depends  also 
upon  other  conditions,  such  as  the  part  of 
the  visual  field  involved.  Three  things 
may  be  noted  about  the  distance  traveled 
by  a  stimulus  before  perception  of  move- 
ment occurs. 

(1)  The  distance  is  always  larger  than  the 
extent  of  the  involuntary  tremors  of  the 
eye  that  occur  whenever  we  try  to  keep 
our  eyes  still. 

(2)  Except  in  the  center  of  the  visual 
field,  the  distance  is  always  smaller  than 
the  threshold  for  the  perception  of  the 
separation    of    two    points.      Thus    move- 


ments in  the  periphery  of  the  visual  field 
may  be  perceived  distinctly  when  objects 
are   indistinct. 

C6)  Nevertheless,  the  magnitude  of  the 
threshold  for  movement  varies  with  visual 
acuity,  although  in  the  periphery  of  the 
visual  field  the  decrease  in  .sensitivity  to 
movement  is  not  so  great  as  the  decrease  in 
visual  acuity.  Thus  at  the  center  of  the 
field  the  two  thresholds  are  approximately 
the  same,  but  at  a  distance  of  20  degiees 
from  the  center  the  threshold  for  acuity 
is  four  times  as  large  as  that  for  movement. 
When  you  look  directly  at  a  moving  auto- 
mobile, for  example,  you  can  see  the  auto 
mobile  as  distinctly  as  you  can  see  its  move- 
ment. When  you  look  out  of  the  corner 
of  your  eyes,  on  the  contrary,  though  you 
do  not  get  either  perception  so  clearly  as 
you  could  in  direct  vision,  still  you  can  see 
the  movement  of  the  automobile  even 
before  you  can  see  the  automobile  itself. 
That  is  another  fact  that  convinces  us  that 
movement  is  a  special  kind  of  perception 
with  its  own  'label,'  which  is  different  from 
the  'label'  of  the  object  perceived. 

What  are  the  limiting  rates  of  stimula- 
tion that  will  arouse  the  perception  of 
movement?  In  vision,  under  optimal  con- 
ditions and  at  a  distance  of  2  meters,  an 
object  must  move  about  0.2  centimeter  per 
second  before  it  is  perceived  as  moving. 
When  the  rate  becomes  about  150  centi- 
meters per  second,  the  perception  for  the 
same  distance  will  appear  as  a  flicker  or  a 
blur.  The  minute  hand  of  a  Avatch  -would 
ha^e  to  move  five  or  six  times  faster  tlian 
it  does  to  be  seen  as  moving. 

In  everyday  experience  the  rate  of  150 
centimeters  per  second  seems  slow,  for  it  is 
only  about  3  miles  per  hour.  If.  however, 
while  you  were  looking  at  the  groiuid  2 
yards  away  through  a  pipe  a  foot  long  and 
one  inch  in  inside  diameter,  a  mouse  run- 


310 


Visual  Space  Perception 


ing  at  the  rate  of  3  miles  per  hour  passed 
through  the  restiicted  field  of  your  vision, 
the  mouse  would  be  seen  as  a  blur:  it 
would  be  neither  a  mouse  nor  a  moving  ob- 
ject. 

The  remoteness  of  a  moving  object  de- 
creases the  percei\ed  rate  of  its  movement. 
At  a  distance  of  a  few  yards  an  automobile 
traveling  at  60  miles  per  hour  will  appear 
lo  be  moving  rapidly,  but  at  a  distance  of 
a  few  miles  only  slowly.  A  ship  on  the 
horizon  is  not  perceived  as  moving  at  all. 
The  decrease  in  rate  is  not,  however,  pro- 
portional to  the  distance  and  hence  not 
proportional  to  the  rate  of  the  movement 
of  the  object's  image  on  the  retina.  The 
tendency  for  objects  to  maintain  their  size 
with  increasing  distance  tends  to  keep  con- 
stant the  apparent  rate  as  distance  in- 
creases. Movement  on  the  retina  seems 
faster  in  perception  when  the  moving  ob- 
ject is  perceived  as  distant,  than  if  its  dis- 
tance were  not  perceived.  If  one  backs 
away  from  a  revolving  barber's  sign,  both 
the  perceived  size  of  the  sign  and  its  rate 
of  movement  remain  approximately  un- 
changed. If  perceived  size  stayed  constant 
with  changing  distance  and  perceived 
movement  altered  with  the  rate  of  move- 
ment on  the  retina,  we  should  liave  strange 
contradictions  in  perception. 

Perceived  Movement  with 
Stationary  Stimuli 

Since  stationary  stimuli  may  appear  to 
move  (afterimages,  autokinetic  movement) 
and  since  normally  the  perception  of  move- 
ment results  from  displacement  of  the 
stimulus  with  respect  to  a  frame  of  refer- 
ence, there  would  seem  to  be  no  funda- 
mental necessity  for  the  stimulus  itself  to 
be  moving.  Discrete  displacement  under 
proper  conditions  might  be  enough  to  win 
the  movement   'label'   for   the   perception. 


The  fact  is  that  series  of  discontinuous 
stimuli  will  produce  the  perception  of 
movement,  provided  the  illumination,  the 
distances  and  the  rate  of  succession  are 
within  the  proper  limits. 

Just  this  happens  in  Avhat  is  termed 
stroboscopic  or  apparent  inox'ement,  of 
which  there  arc  many  examples  in  every- 
day experience.  ITie  simplest  situation 
is  at  railroad  crossings  where  two  lights, 
placed  side  by  side,  light  up  alternately 
when  a  train  is  near.  With  continued  fix- 
ation the  light  seems  to  mo\e  back  and 
forth  from  one  position  to  the  other. 
Everyone  is  familiar  with  the  motion  seen 
in  electric  signs  before  theaters,  stores,  ho- 
tels and  on  billboards.  There,  of  course, 
no  actual  movement  is  present.  The  lights 
are  turned  on  and  off  in  proper  sequence 
and  with  proper  timing. 

The  commonest  example  of  all  is  the 
movies  themselves.  In  the  cinema  a  se- 
ries of  still  photogiaphs  is  projected  on  the 
screen,  every  photograph  representing  a 
slightly  different  position  of  a  moving  ob- 
ject. ^Vhen  the  series  is  projected  on  the 
screen  in  the  proper  order  and  at  tJie 
proper  rate  (usually  twenty-four  per  sec- 
ond), normal  movement  is  perceived.  The 
quality  of  the  movement  changes  with  the 
rate  of  projection.  If  this  rate  is  too  slow, 
Ave  see  a  succession  of  static  pictures.  If 
the  rate  is  then  increased,  the  movement 
becomes  first  a  flicker,  then  normal  mo\e- 
ment,  and  finally,  when  too  fast,  jerky  and 
blurry.  At  great  speed  of  projection  all 
movement  disappears,  and  we  see  only  a 
filmy  surface. 

A  situation  for  the  perception  of  appar- 
ent movement  with  two  successive  station- 
ary stimuli  at  different  places  is  shown  in 
Fig.  143.  If  a  vertical  line  A  is  shown, 
removed,  and  then,  after  an  interval  of 
0.06  second,  a  horizontal  line  B  is  shown. 


Visual  Perception  of  Movement 


311 


tlic  vertical  line  will  be  seen  io  lotate 
clockwise  Irom  the  12  o'clock  to  the  J5 
o'clock  position,  as  in  C  of  the  figure. 
Slioukl  the  interval  between  ex|K)snres  ol 
the  lines  be  shortened  U)  al)ont  0.02  second, 
the  two  lines  would  appear  simultaneously 
and  form  a  right  angle.  If,  on  the  other 
hand,  the  interval  between  the  exposures 
were  lengthened  to  0.20  second,  the  two 
lines  would  appear  successively  with  no 
movement  perceived  at  all. 


Li 


A 
;glire   143. 


STIMULI    FOR    APPARENT    MOVEMENT 


When  A  is  succeeded  by  B  and  the  lime  intervals 
are  correct,  you  see  llie  stroboscopic  or  apjjarent 
movement  as  indicated  in  C  The  line  moves  down 
through  the  angle. 

Exposing  the  two  lines  a  short  distance 
apart  always  produces  a  better  perception 
of  movement  than  exposing  them  farther 
apart.  The  motion-picture  cartoonist,  rec- 
ognizing this  fact,  makes  sure  that  the  dif- 
ference between  his  successive  drawings  is 
slight.  The  less  the  displacement  between 
successive  drawings,  the  more  lifelike  and 
complete  the  movements  of  the  figiues. 

Exposing  each  stimulus  briefly  gives  an 
impression  of  swifter  movement,  whereas 
lengthening  the  exposine  time  slows  down 
the  movement  and  makes  it  jerky.  Simi- 
larly, small  stimuli  tend  to  produce  smooth 
movement,  and  large  ones  jerky  movement. 
We  reject  the  front  seats  in  the  movies  to 
avoid  jerkiness  and  flicker. 

Apparent  movement  with  discretely  dis- 
placed stimuli  is  often  perceived  as  actually 
'better'  and  smoother  than  the  movement 
of  an  object  which  is  really  moving.  In 
one  experiment   two  rectangles  were   pro- 


jected, one  above  the  otiiei,  at  the  left  of 
a  screen.  Then  one  rectangle  was  made 
to  move  rapidly  across  the  screen  to  a  [x>- 
sition  at  the  right,  while  the  other  disaj>- 
pcared  at  the  left  and  reappeared  at  the 
right  without  having  moved  through  the 
intervening  space.  There  was  no  funda- 
mental difference  between  these  two  per- 
ceptions of  the  real  movement  and  appar- 
ent movement,  except  that  the  real  move- 
ment was  descriljcd  as  a  little  more  'jerky' 
and  less  unifoini  than  the  apparent  move- 
ment. Ihat  makes  sense.  All  the  brain 
needs  to  perceive  movement  is  discrete  dis- 
placement at  the  correct  rate.  It  can  be 
embarrassed  by  a  surplus  of  clues. 

Just  as  implicit  clues  add  the  meaning 
of  depth  to  a  flat  picture,  so  the  giayish 
flash  that  trails  a  moving  object  or  that 
appears  in  the  field  of  apparent  movement 
can  add  the  'label'  of  movement  to  a  sta- 
tionary object  in  a  picture.  A  blur  in  the 
form  of  a  few  indistinct  lines  behind  the 
wheels  of  a  car  in  an  advertisement  s;ives  it 


FIGURE    144.       USE    OF    LINES    TO    GIVE   THE   IMPRF_S 
SION    OF   MOVEMENT  TO   OBJECTS 

a  dash  as  if  it  might  mo\e  into  the  left  col- 
umn (Fig.  144).  Modern  illustrations  finnish 
many  more  examples  of  the  use  of  this  clue. 

REFERENCES 

1.  Boring,  K.  (;.  Seiisalion  and  perception  in  the 
histurx  of  experimental  psychology  New  York: 
Appleton-Ceniury,  1942.     Chaps.  8.  9  and  15. 

The  historv  of  research  and  iileas  in  the  fields 
of  visual  sensation  and  perception  from  the  sev- 
enteenth centurv  down  to  about  1930. 


312 


Visual  Space  Perception 


Carr,  H.  A.  An  introduction  to  space  percep- 
tion. New  York:  Longmans,  Green,  1935. 
Chaps.  3,  6,  7,  8,  9  and  10. 

A  clear  and  readable  handbook  of  the  psy- 
chology of  space  perception  (mostly  visual)  be- 
fore the  researches  of  Geslalt  psycliologists  had 
affected  the  field. 

Ellis,  "VV.  D.  .1  source  book  of  Gestalt  psy- 
chology. New  York:  Harcourt.  Brace,  1938. 
Sections.   II.  12.   13  and   14. 

Translation  of  papers  written  by  the  leaders 
of  the  school  of  Gestalt  psychology,  with  a  dozen 
oapers  on  topics  of  visual  perception. 


4.  Vernon,  M.  D.  Visual  perception.  Cambridge, 
England:  Cambridge  University  Press,  1937. 
Chap.   11. 

An  excellent  textbook  on  visual  space  per- 
ception, which  includes  the  contributions  of 
Gestalt  psychology-. 

5.  Woodworth,  R.  S.  Experimental  psychology. 
New  York:  Holt,  1938.  Chaps.  22,  23,  25,  26 
and  28. 

Excellent  up-to-date  handbook  chapters  on 
the  visual  perception  of  color,  form  and  the 
third  dimension. 


CHAPTER 


14 


Hearing 


FOR  the  most  part,  with  the  eye  we  see 
what  things  are,  and  with  tlie  ear  we 
hear  what  liappens.  Sight  is  primarily  con- 
cerned with  objects;  hearing  with  events. 

For  man  to  hear,  the  most  important 
events  are  the  sounds  of  speech.  It  is 
doubtful  whether  any  single  achievement 
more  sharply  separates  man  from  the  apes 
than  spoken,  and  heard,  speech.  It  is  the 
basis  of  our  culttne,  the  loom  within  which 
wc  weave  and  fashion  our  civilization. 
Two  men  talking  to  each  other  form  the 
simplest  element  of  society. 

Only  a  little  less  important,  of  course, 
are  the  other  events  about  which  our  ears 
tell  us.  We  know  when  people  come  and 
go,  when  a  car  is  approaching,  when  the 
clock  strikes,  or  the  telephone  rings,  when 
the  baby  is  hungry  or  wet,  when  people 
about  us  are  writing  or  coughing  or  asleep. 
While  we  may  be  looking  with  our  eyes  at 
some  single  object,  we  hear  the  flux  of 
sounds  which  conveys  to  us  news  of  the 
many  events  that  happen  around  us. 

The  loss  of  hearing  is  in  many  ways  inore 
disturbing  than  the  loss  of  sight.  Many 
people  fear  blindness  more  than  deafness. 
In  a  sense  they  are  right,  because  the  blind 
man  is  more  critically  dependent  upon  an- 
other person  than  the  deaf  man.  It  has 
been  found,  however,  that  the  deaf  adjust 
themselves  to  their  loss  more  poorly.    Thev 

This  chapter  was  prepared  by  Edwin 

3i: 


feel  tut  oil  hoiii  other  pcojjie  and  Ijttonic 
resentful  when  they  cannot  take  part  in  the 
give  and  take  of  conversation.  Their  feel- 
ings and  interests  grow  more  and  more 
shut-in.  Paranoid  symptoms  may  appear 
in  them.  Complete  loss  of  hearing  warps 
the  loser's  personality  and  social  adjust- 
ment far  more  seriouslv  than  it  disrupts 
his  ability  to  deal  with  his  physical  environ- 
ment. 

The  ear,  the  instrument  with  which  we 
hear,  accomplishes  a  remarkable  task.  It 
is  more  sensitive  than  the  element  of  anv 
practical  microphone.  It  can  respond  to  a 
pressure  as  small  as  one  three-millionth  of 
a  gram.  This  sensitivity  is  so  great  that 
the  keenest  ear  can  almost  hear-  the  random 
fluctuations  produced  when  the  individual 
molecules  of  the  air  strike  the  eardrum. 
When  a  person  is  listening  to  the  weakest 
sounds,  the  mo\ement  of  the  eardrum  is  so 
small  as  to  defy  imagination,  less  dian  the 
billionth  part  of  an   inch. 

At  the  same  time,  the  ear  can  respond  to 
pressures  ten  million  times  greater,  al- 
though it  must  be  said  diat  such  sound 
presstues  are  uncomfortable  and  residt  in 
temporary  deafness.  How  a  system  having 
such  extreme  sensiti\ity  can  continue  to 
respond  so  ^vell  o\"er  this  enormous  range 
of  intensities  is  not  well  kno^sn.  nor  do  we 
understand  fully  ho^v   the  ear  protects   it- 

B.  NcAvman  of  Har\ard  Uni\crsitv. 


314 


Hearing 


self  against  damage  while  listening  to  the 
loudest  sounds. 

Apart  irom  its  job  of  relaying  the  slight 
energy  of  sounds  to  the  brain,  the  ear  also 
aids  in  distinguishing  one  kind  of  sound 
from  another.  We  shall  see  later  some- 
thing about  how  this  takes  place.  It  is 
enough  to  note  here  that  the  ear  has  tw^o 
functions,  first,  to  receive  sounds  and  con- 
vert them  into  nervous  messages  and,  sec- 
ond, to  respond  in  a  different  way  to  differ- 
ent sounds  so  that  analysis  and  discrimina- 
tion among  sounds  is  possible. 

STIMULUS    FOR    HEARING 

To  understand  ho^v  it  is  that  we  hear,  we 
have  first  to  learn  a  little  about  the  physics 
of  sound. 

Sound  Waves 

The  immediate  stimulus  for  hearing  is 
normally  a  rapidly  fluctuating  pressure  on 
the  eardrum.  This  alternate  rise  and  fall 
of  pressure  is  the  result  of  sound  waxes 
which  are  transmitted  through  the  air  (or 
through  solid  objects  such  as  walls  or  win- 
dows) from  some  source  of  sound.  Soimd 
waves  beha\'e  in  much  the  same  way  as 
other  forms  of  wa\e  motion.  Once  the 
wave  motion  is  started,  it  travels  at  a  con- 
stant speed,  depending  upon  the  density 
and  elasticity  of  the  medium.  In  air  the 
speed  is  about  eleven  hundred  feet  per  sec- 
ond. A  sound  wave  bends  when  it  passes 
a  corner  or  when  it  goes  through  air  which 
is  not  all  equally  dense.  In  a  closed  room, 
sound  waves  are  reflected  very  well  (often 
more  than  ninety  per  cent  of  them)  from 
all  the  walls  and  hard  surfaces.  If  sound 
travels  away  from  a  point  in  the  open,  the 
amplitude  ('height')  of  the  wave  is  halved 
each   time  the  distance  is  doubled.      In   all 


these  ways,  sound  waves  are  like  light 
xvaves  or  waxes  in  w^ater. 

In  other  respects  sound  waves  are  differ- 
ent. ^\'a\es  on  the  surface  of  water  consist 
of  a  movement  which  is  mostly  up  and 
down,  at  right  angles  to  the  path  the  wave 
is  taking.  Soimd  Avaves  involve  movement 
forward  and  back,  in  line  with  the  direc- 
tion of  their  travel.  Each  bit  of  air  is 
pushed  forward  by  the  pressure  from  be- 
hind and  moves  back  as  it  passes  on  this 
pressure  to  the  air  ahead.  Also  sound 
waves,  unlike  light  waves,  are  commonly 
distorted  in  certain  ways  as  they  pass 
through  the  air.  Generallv,  the  sound  on 
arrival  at  the  ear  has  aboiu  the  same  wave 
form  it  had  when  it  left  the  source.  But 
if  it  is  of  very  high  intensity  (a  'shock 
wave'),  such  as  the  sound  of  an  explosion, 
it  changes  its  shape  in  its  hurry  to  leave  the 
place  from  which  it  started.  Further- 
more, high-frequency  waves  fall  off  in  en- 
ergy more  rapidly  than  loxv-frequency  waves 
when  they  have  to  travel  distance  of  a 
quarter  mile  or  more.  As  we  shall  see  later, 
we  are  able  to  make  use  of  our  familiarity 
with  such  distortions  in  judging  the  dis- 
tance of  a  source  of  sound  from  the  listener. 

Sound  is  produced  when  an  object  is  set 
into  vibration.  A  single  sharp  sound  arises 
when  an  object  is  struck.  The  drip  of 
water,  the  banging  of  a  door,  the  tick  of  a 
clock,  the  sound  of  a  hammer  or  rifle  are 
sounds  of  this  sort.  Each  of  them  produces 
a  single  sound  wave,  or  short  train  of  waves 
at  most,  which  is  transmitted,  pulse-like,  to 
the  ear.  If  there  is  a  series  of  clicks  or 
bangs  w^hich  follow  each  other  closely,  yet 
in  a  random  manner,  the  sound  becomes 
continuous.  The  drip  of  water  becomes 
the  drumming  of  rain  on  the  roof  or  the 
steady  roar  of  the  sm-f  or  the  waterfall. 
The  tap  of  one  leaf  on  another  becomes  the 
rustle  or  rush  of  wind   through   the   trees. 


Sound  Waves 


315 


y\ir  or  steam  in  its  disoidercd  Jiastc  lo 
escape  from  a  pipe  or  jet  produces  an 
equally  disordered  train  of  waves  which 
is  heard  as  a  hiss.  All  such  sounds  we  call 
random  noise  (or  fiitcluation  noise)  be- 
cause   no    two    succeeding    waves    are    the 


Flute 


Clarinet 


Human  voice  -A^' 


Explosion 


FIGURE    145.      TYPICAL  SOUND  WAVES 

The  first  three  are  periodic  waves,  repeated  regu- 
larly. The  last  is  highly  irregular.  [From  D.  C. 
Miller,  The  science  of  musical  sounds,  1926;  by 
permission  of  the  Macmillan  Company.] 

same;  the  amounts  of  pressure  existing 
in  successive  moments  is  governed  by 
chance.  We  may  equally  well  speak  of 
white  noise  because,  as  we  shall  see  in  a 
moment,  noise  can  be  broken  up  into  many 
different  frequencies  much  as  white  light 
can  be  broken  up  into  a  variety  of  spectral 
colors. 

So  much  for  noise.  Not  all  sounds  are 
noisy.  Instruments  ^vith  strings,  such  as 
violins  and  pianos,  are  constructed  in  such 
a  way  that   they  pioduce  smooth,   simple 


sounds.  1  licir  strings,  once  touched,  con- 
tinue to  vibrate  at  a  regular  rate.  Each 
successive  sound  wave  produced  by  the 
string  is  just  like  the  wave  which  went  be- 
fore. The  result  is  a  musical  tone.  The 
column  of  air  in  an  organ  pipe  acts  in 
much  the  same  way  as  the  string.  The  air 
inside  the  pipe  is  like  a  coiled  spring  Idl- 
ing the  pipe  and  attached  at  the  closed  end. 
Compressed  slightly,  then  released,  the  col- 
umn of  air  vibrates  with  a  fixed  period. 
Bells,  bugles,  bees,  humming  motors  and 
the  human  voice  all  are  sources  of  sound 
which  produce  trains  of  regular  waves. 
We  call  the  vibration  of  such  objects 
periodic. 


Time 


FIGURE    146.      A   SINE   WAVE 

Three  complete  cycles  of  a  wave  representing  a 
pure  tone. 

In  Fig.  145  are  pictures  of  sound  waves 
seen  on  the  face  of  an  oscilloscope.  This 
is  a  device  that  traces  the  fluctuating  pres- 
sure of  the  sound  wave  with  a  rising  and 
falling  finger  of  electrons  which  races  across 
a  screen.  The  first  three  patterns  in  the 
figure  are  of  periodic  waves;  the  last  is  the 
picture  of  a  noise,  a  highly  random  sound 
which  is  dying  away  rapidly  as  it  passes 
to  the  right. 

A  very  few  instruments  produce  what  are 
called  pure  tones,  dear  to  the  heai't  of  the 
experimental  psychologist  or  physicist. 
Tuning  forks,  weakly  blown  pipes  and,  to- 
day, electronic  oscillators  coupled  to  suit- 
able loudspeakers  or  earphones  produce  the 
pure  tones  with  which  these  scientists  work. 
In  comparison  Avith  die  notes  of  odier  in- 
struments, pure  tones  sound  diin  and  flat 
and    have    no    interest    for    the    musician. 


316 


Hearing 


They  represent,  however,  the  simplest  pos- 
sible wave  motion,  a  sine  wave,  tlie  form 
of  which  is  shown  in  Fig.  146.  This  wave 
form  can  be  represented  by  a  simple  mathe- 
matical expression,  the  sine  function,  fa- 
miliar to  students  of  trigonometry. 

Simple  Waves  and  Complex  Waves 

How  can  we  start  on  the  task  of  relating 
llie  many  things  that  we  hear  to  the  large 
variety  of  physical  soinids  with  their  com- 
]jle\  wave  forms?  What  are  the  more  im- 
portant things  to  know  about  a  sound 
wave?  Just  how  may  we  describe  it  most 
effectively?  We  are  faced  here  with  the 
problem  of  analysis  and  must  stop  to  be- 
come somewhat  familiar  with  the  meth- 
ods of  both  mathematical  and  physical 
analysis  of  sound  waves.  Analysis  provides 
the  tools  which  we  shall  need  to  under- 
stand how  we  hear. 

Fourier  Analysis 

In  1822,  Fourier,  a  French  physicist  and 
mathematician,  showed  that  it  is  possible 
to  express  any  periodic  wave  form,  such  as 
the  first  three  shown  in  Fig.  145,  as  the  siivi 
of  a  series  of  simple  waves,  each  of  which 
is  a  sine  wave. 

To  illustrate  how  one  complex  wave  is 
made  up,  we  may  look  at  the  wave  form 
shown  in  Fig.  147.  A  single  complete 
period  of  the  complex  wave  is  shown  at  the 
lower  right.  It  is  roughly  a  square  wave, 
such  as  that  produced  by  some  sirens.  The 
Fourier  analysis  of  this  tone  reveals  five 
components,  which  are  illustrated  to  the 
left.  The  relative  frequency  of  each  com- 
ponent is  proportional  to  the  numbers,  I, 
III,  V,  VII  and  IX,  to  the  left  of  each  line, 
and  you  can  check  this  frequency  by  coiuit- 
ing  the  waves  in  any  one  period  of  the  com- 
plex tone.  To  the  right  are  shown  the  suc- 
cessive steps  in  the  addition,  starting  with 


Component 


Composite 


FIGURE  147.     SIMPLE  WAVES  ADD  UP  TO  A  COMPLEX 
WAVE 

The  first  five  harmonic  components  of  a  single 
cycle  of  a  "square  wave'  are  shown  at  left.  Series  at 
light  show  progressive  change  from  a  simple  sine 
wave  as  each  component  is  added.  If  enough  ad- 
ditional odd  harmonics  were  added,  the  'square 
wave,'  a  rectangular  form  which  is  already  apparent 
in  the  form  at  the  lower  right  corner  of  the  figine, 
would  be  even  more  closely  approximated. 

the  wave  of  lowest  frequency  and  then 
showing  the  composite  wave  as  each  addi- 
tional component  is  added  in.  Examine 
carefidly  the  composite  waves  and  you  can 
see  how  the  wave  form  becomes  more 
nearly  square  as  this  summing  up  goes  on. 
The  Fourier  analysis  is  mathematical.  It 
starts  out  with  a  basic  or  fundamental  fre- 


Analysis  of  Sound 


317 


(|uenty  which  is  ihc  same  as  the  frequency 
with  which  the  complex  wave  repeats  itself. 
To  this  lunclamental  are  added  sine  waves 
of  other  higher  fre(]uencies.  These  added 
frequencies  will  always  be  some  even  mul- 
tiple of  the  fundamental  frequency.  If  the 
fundamental  is  n  cycles  per  second,  the 
harmonics  will  be  2n,  S?i,  4n,  bn  or  ()» 
cycles  per  second. 

In  the  development  of  the  physics  of 
sound,  the  Fourier  analysis  is  most  impor- 
tant. It  provides  a  mathematical  expres- 
sion which  can  be  subjected  to  many  fur- 
ther mathematical  operations.  These 
mathematical  manipulations  predict  how 
sound  waves  will  behave  as  they  arc  trans- 
mitted in  the  air  or  are  transformed  into 
electrical  waves  and  passed  through  elec- 
trical circuits.  Without  the  Fourier  anal- 
ysis we  should  be  at  a  loss  in  handling  such 
theoretical  problems.  The  Fourier  anal- 
ysis is  very  important  for  theory,  but  we 
should  keep  clearly  in  mind  what  it  is, 
namely,  a  mathematical  model  which  helps 
us  to  understand  and  predict  the  actions  of 
periodic  wave  forms. 

Analysis  by  Resonance 

Physical  methods  of  analysis,  as  distin- 
guished from  the  mathematical,  also  start 
with  the  idea  that  a  complex  wave  form  is 
made  up  of  a  number  of  simple  compo- 
nents. The  physical  analyzer  has  the  job 
of  responding  separately  to  each  of  the 
possible  component  sine  waves  in  order  to 
discover  which  are  present  and  which  ab- 
sent and  to  measure  the  amplitude  (height) 
of  those  present.  Most  simply,  this  anal- 
ysis is  made  with  a  series  of  resonators,  one 
of  which  is  tuned  to  each  of  the  possible 
component  frequencies  in  the  complex 
wave.  A  resonator  may  be  any  device  that 
has  a  natural  vibration  period  of  its  own, 
such  as  a  string  or  reed  or  pipe,   and,   in 


addition,  is  so  sensitive  to  sound  waves 
that  it  will  be  set  into  sympathetic  vibra- 
tion when  series  of  waves  strike  it. 

One  such  acoustic  resonator,  shown  in 
Fig.  148,  consists  of  a  brass  cylinder  with 
an  opening  in  the  outer  end  to  admit  the 
sound  and  a  small  lip  on  t!ie  inner  end  for 
insertion  into  the  cir.  1  he  length  of  the 
resonator  can  be  adjusted  by  sliding  the 
one  part  of  the  cylinder  in  or  out  of  the 


ACOUSTIC   RESONATOR 


The  tip  is  placed  in  the  car  and  the  lengili  ail- 
justed  until  the  enclosed  air  vibrates  in  resonance 
with  the  component  which  is  being  analyzed  out  o[ 
the  complex  tone.     [After  R.  Koenig  (1872).] 

Other,  like  a  telescope.  The  column  of  air 
in  the  cylinder  reinforces  by  its  own  reso- 
nance one  particular  frequency  as  it  passes 
through  the  resonator  into  the  ear.  AVith 
such  a  set  of  resonators  it  is  possible  to  hear 
each  of  the  component  tones  predicted  by  a 
Fourier  analysis.  If  the  tone  is  the  square 
wave  represented  by  the  w'ave  form  of  Fig. 
147,  resonators  can  be  tuned  to  each  of  the 
five  components  and  dieir  frequencies  and 
relative  strengths  can  be  estimated. 

The  resonators  can.  ho^vever,  do  much 
more  than  the  mathematical  analysis. 
They  are  not  limited  to  sounds  whose  com- 
ponent frequencies  are  in  a  simple  aritli- 
metic  ratio  to  one  another,  A\hich  is  the 
basic  requirement  of  the  Fourier  series. 
Many  large  bells,  for  instance,  give  out 
component  tones  which  are  quite  inhar- 
monic,   are    not   related   by   simple   ratios. 


318 


Hearing 


The  wave  form  produced  by  such  a  bell 
would  never  repeat  itself  exactly  and  it  is 
therefore  wholly  unsuitable  for  a  Fourier 
analysis.  But  by  means  of  an  acoustic 
resonator  it  is  possible  to  discover  just 
what  these  bell  frequencies  are. 

Today  we  have  the  electronic  wave  ana- 
lyzer, which  is  a  far  more  accurate  instru- 
ment than  the  acoustic  resonator.  The 
sound  to  be  broken  up  is  first  picked  up 
by  a  microphone  and  is  then  sent  through 
many  special  circuits.  Even  then  the  ac- 
tion of  the  wave  analyzer  depends  funda- 
mentally upon  a  kind  of  resonance,  but 
the  resonance  is  electrical  rather  than  acous- 
tic. The  advantages  of  the  electronic  ana- 
lyzer are  that  the  frec|uency  may  be  deter- 
mined easily  by  reading  a  single  large  dial 
and  the  strength  of  the  component  is  meas- 
ured on  an  accurate  meter.  With  this  ana- 
lyzer it  has  been  possible  to  find  the  com- 
ponents present  in  many  kinds  of  sounds, 
particularly  in  many  complex  noises  that 
])reviously  were  little  understood.  In  fact, 
I  he  physical  composition  of  practically  all 
sounds  is  now  fairly  well  known,  with  the 
exception  of  a  few  extremely  brief  tran- 
sient sounds. 

Sine  Waves 

In  describing  a  sine  wave  we  have  al- 
ways to  state  its  frequency  (or  wave  length) 
and  its  a?npUtude.  In  acoustics  frequency 
is  stated  in  cycles  per  second  (cps),  the  num- 
ber of  complete  waves  that  pass  a  given 
point  in  a  second.  The  amplitude  is  the 
size  of  the  wave.  In  waves  like  those  of 
Fig.  147  the  amplitude  is  the  height  of  the 
wave.  There  component  III  has  a  fre- 
quency three  times  the  frequency  of  I  and 
an  amplitude  somewhat  less  than  half  the 
amplitude  of  I. 

In  describing  the  relation  of  one  wave 


to  another,  the  phase  relation  of  the  two 
must  be  stated.  In  Fig.  147  the  phase  rela- 
tion of  III  to  I  would  be  changed  if  III 
were  shifted  to  the  right  a  fraction  of  its 
wave  length,  but  not  if  it  were  shifted  one 
whole  wave  length.  Two  waves  of  the 
same  frequency  are  said  to  be  in  phase 
when  their  crests  (or  troughs)  coincide  or 
to  be  in  opposite  phase  when  the  crest  of 
one  comes  with  the  trough  of  the  other. 

With  these  meanings  in  mind,  we  can 
now  draw  upon  our  knowledge  of  the  re- 
sults of  the  two  methods  of  analysis  of  com- 
plex waves  and  formulate  these  conclusions. 

(1)  A7iy  complex  stimulus  to  tone  or 
noise  may  be  described  adequately  as  the 
combination  of  a  number  of  components, 
each  one  a  sine  wave  with  its  own  fre- 
quency and  amplitude.  In  special  cases  it 
is  necessary  to  say  also  what  is  the  relative 
phase  of  the  components  or  to  tell  how 
their  amplitude  rises  and  falls. 

(2)  So  far  as  the  acoustic  and  mechanical 
parts  of  the  ear  are  concerned,  what  hap- 
pens to  any  complex  sound  is  described 
fully  by  telling  what  happens  to  each  of 
its  sine  wave  components.  As  we  shall  see 
later,  this  rule  no  longer  holds  when  loe 
begin  to  deal  with  the  action  of  the  nerv- 
ous system. 

(3)  Sounds  may  be  anything— an  occa- 
sional pure  tone,  musical  tones  which  have 
regularly  spaced  harmonic  components 
(Fourier  series),  clangs  and  tone-like  noises 
which  have  components  of  odd  frequencies 
irregularly  spaced  and  finally  random  and 
impulse-like  noises  in  which  the  individual 
components  can  no  longer  be  separated 
from  one  another.  In  this  last  case  we 
speak  of  a  contijiuous  sound  spectrum, 
meaning  that  all  frequencies  are  present, 
although  they  will  not  all  be  equally  strong 
(an  analogy  with  the  light  spectrum).     It 


Stimuli  and  Their  Sensations 


319 


is  clear  that  the  character  or  quality  of  a 
sound  is  determined  by  the  number  and 
distribution  of  the  components  which  make 
it  up. 

Harmonics 

We  think  of  a  simple  sine  wave  as  being 
the  stimulus  for  a  pure  tone,  but  actually 
exact  sine  waves  are  hard  to  create  and, 
when  they  are  formed  in  air  by  modern 
electrical  means,  they  are  almost  certain 
to  get  distorted  in  transmission  through 
any  communication  system,  a  telephone  sys- 
tem or  even  the  mechanism  of  the  human 
ear  itself. 

If  you  pluck  or  strike  a  piano  string,  hav- 
ing pressed  down  the  sustaining  pedal,  you 
get  from  it,  not  a  pure  sine  wave,  but  a 
complex  wave  which  is  the  sum  of  many 
waves  having  frequencies  in  the  ratios  of 
1:2:3:4:5:6:7:8  and  so  on.  If  the  string 
you  plucked  was  the  one  for  A  of  110 
cycles  per  second,  you  would  have  a  com- 
plex wave  of  a  frequency  of  110-1-220-f 
330  +  440  +  550  +  660  +  770  +  880  cycles 
per  second,  etc.,  that  is,  the  notes  A,  a, 
e',  a',  d",  e",  g",  a",  etc.  These  notes,  which 
tend  to  go  together  when  an  instrument 
produces  the  lowest  one  and  which  have 
these  simple  frequency  ratios  to  one  an- 
other, are  called  harmonics  and  are  said  to 
be  in  harmonic  relation  to  one  another. 
The  lowest  tone  of  a  set  of  harmonics  is 
called  the  fundamental  and  the  rest  the 
upper  harmonics. 

All  notes  of  musical  instruments  are  com- 
plex in  different  ways,  according  to  which 
harmonics  are  emphasized  in  them— whether 
all  the  first  ten,  as  in  the  plucked  piano 
string,  or  the  even  harmonics,  or  the  odd, 
or  the  high  ones.  The  distinctive  qualities 
of  different  musical  instruments  are  due  in 
part  to  the  pattern  of  harmonics  produced. 


It  is  safe  to  say  that  no  one  has  evei 
heard  a  loud  pure  tone.  Unless  the  stimu- 
lus is  very  weak,  even  a  pure  sine  wave  is 
distorted  by  the  transmission  apparatus  of 
the  ear,  so  that  for  a  pure  sine  wave  out- 
side we  get  inside  a  complex  wave  with 
all  the  components  that  the  Fourier  anal- 
ysis gives  for  the  distorted  sine  form. 

SOUNDS:    WHAT    WE    HEAR 

Sound  is,  after  all,  what  we  hear.  We 
have  taken  pains  to  understand  the  sources 
of  sound,  the  sound  waves,  because,  in  the 
end,  someone  was  going  to  hear  the  sound. 
Now  we  have  to  examine  what  is  heard  and 
relate  it  to  the  physical  events  outside  the 
ear  which  preceded  it.  Our  auditory  ex- 
periences need  to  be  arranged,  and  we  have 
to  find  the  common  attributes,  the  dimen- 
sions, with  respect  to  which  these  experi- 
ences may  be  ordered. 

The  simplest  ordering  of  sounds  is  in 
terms  of  their  quality.  All  sounds  may  be 
classified  into  tones  and  noises.  Tones  are 
smooth,  blended,  continuous;  noises  are 
rough,  irregular,  disorganized.  There  is. 
of  course,  no  sharp  line  between  the  two. 
Many  noises  have  a  tonal  character,  and 
almost  all  musical  instruments  make  noises 
that  form  a  part  of  their  normal  tones. 
Noises  may  be  continuous  noises,  like  roars, 
rattles,  squeaks  and  hisses,  or  they  may  be 
explosive  noises,  booms,  thuds,  bangs,  clicks 
and  pops. 

Tones  might  be  subdivided  as  tliey 
sound  like  a  bo^ved  string  (violin),  a 
plucked  or  struck  string  (piano),  an  open 
pipe  (pipe  organ),  a  reed  instrument  (clar- 
inet), etc.  Such  a  classification  would  be  of 
little  value,  as  it  would  serve  to  point  out 
only  what  is  obAious.  that  the  ear  can  and 
does  hear  differences  of  this  kind. 


320 


Hearing 


PITCH 

For  many  centuries,  certainly  since  the 
days  of  the  early  Greeks,  men  have  recog- 
nized pitch  as  an  attribute  of  tones.  Pitch, 
and  melody  which  in  jiart  depends  on 
pitch,  were  used  to  further  hiuiian  enjoy- 
ment long  before  anyone  understood  how 
they  come  about.  Indeed,  it  is  sometimes 
disconcerting    to    realize    how    much    men 


FIGURE    149.      TONAL  QUALITY  AND  PITCH 

Pitch  rises  steadily,  as  shown  by  height  above 
base.  Tonal  quality,  as  of  a  note  on  a  musical 
scale,  repeats  itself  through  each  octave  and  is 
shown  around  the  circle. 


once  achieved  without  the  tremendous 
body  of  scientific  knowledge  on  which  we 
may  draw  today! 

Tones  vary  in  j^itch  from  high  to  loiu. 
Just  why  we  use  words  describing  space 
also  to  describe  pitch  is  not  clear,  but  the 
same  pair  of  words  is  used  in  many  differ- 
ent languages.  A  psychologist  once  put  a 
loudspeaker  behind  a  black  curtain  and 
then  asked  students  seated  in  front  of  it 
where  they  heard  a  series  of  pure  tones. 
They  heard  the  higher  pitches  farther  from 
the  floor,  the  lower  pitches  nearer  the  floor. 
But  the  psychologist  could  find  no  explana- 
tion for  this  persistent  impression. 

Pitch  is  most  characteristic  of  tones  in 
the  middle  of  the  range,  roughly  within 
the  musical  scale.  Some  people  would  go 
so  far  as  to  say  that  pitch  does  not  describe 
the  extremely  high  notes.  Such  high  tones, 
they  say,  are  merely  piercing,  shrill,  bright, 
etc.  Nevertheless,  a  person  who  believed 
this  would  still  put  the  notes  in  the  same 
order  from  low  to  high,  perhaps  on  the 
basis  of  brightness.  Here  arises  a  prob- 
lem about  the  words  we  should  use,  and  it 
is  not  important  in  understanding  how  the 
ear  works.  The  important  fact  is  that, 
whatever  word  is  used,  people  who  can 
hear  the  very  high  notes  at  all  can  tell  them 
apart  and  put  them  in  order. 

A  more  difficult  problem  comes  up  be- 
cause some  pitches  seem  to  be  more  closely 
related  to  one  another  than  others.  In  par- 
ticular, tones  which  are  about  an  octave 
apart  bear  a  very  strong  resemblance  to 
each  other.  A  person  with  little  musical 
training  will  frequently  make  a  mistake  of 
a  fidl  octave  in  setting  a  pitch  from  mem- 
ory, particularly  if  he  is  dealing  with  pure 
tones.  It  has  been  stiggested  that  the 
proper  way  to  represent  pitch  is  not  in  a 
straight  line,  but  rather  in  a  spiral  as  shown 
in  Fig.  149.    The  height  above  the  base  is 


Pitch 


321 


the  quality  usually  recognized  by  the  psy- 
chologist as  pitch.  The  notes  within  an 
octave,  do,  re,  mi,  fa,  etc.,  would  then  he 
represented  around  the  circle,  and  two 
notes  an  octave  apart  would  come  one 
over  the  other.  Such  a  scheme  is  indeed 
useful,  for  it  makes  clear  a  set  of  relations 


frequency  are  used  interchangeably.  En- 
gineers and  physicists  are  particularly 
prone  to  this  error,  sf)eaking  of  a  'pitch 
of  1000  cycles.'  The  reader  should  he 
careful  not  to  make  this  mistake.  Pitch  is 
something  we  hear  that  is  high  or  low; 
frequency    is    something    measured     phys- 


i 


l>^jjjj|J^rrrr 


^ 


jiiih^f^ 


^ 


^ 


Range  of  human  voice 


AjBjCiOiE,  F|  G,  A|  B,  C  D  E   F   G    A   B    c    d   e   f    gob    c' d' e' f  g'   a'  b'   c"  d"e"  f  "g"  o"  b"  c"d"e"f  "9"a"b"'c"d'"e''«"*g~a~b"c'" 

llllllll!llllliillllllllllll!IIIIMm 


LL 


Piano  keyboard 

I 
Standard  pitch  =  440  cycles  per  second 


25  50  100  200  500  1000  2000  4000 

Frequency  in  cycles  per  second 

FIGURE    150.      FREQUENCY   OF   MUSICAL  TONES 

The  lowest  scale  shows  frequency  in  cycles  per  second.  Above  this  are  shown  the  piano  keys  correspond- 
ing to  each  frequency,  and  the  notes  of  the  staff:  which  are  commonly  sung.  The  musical  scales  are  re- 
ferred to  standard  orchestral  pitch  of  a'  =  440  cycles  per  second. 


among  pitches  which  to  the  musician  are 
all  important. 

Pitch  and  the  Sound  Wave 

The  pitch  of  a  tone  depends  principally 
upon  the  frequency  of  the  sound  waves 
reaching  the  ear.  High  pitches  are  heard 
when  the  frequency  is  high;  low  pitches  go 
with  low  frequencies.  The  frequencies  of 
the  notes  on  the  piano  keyboard  are  shown 
in  Fig.  150,  together  with  the  notes  that 
can  be  sung  by  the  human  voice.  Natu- 
rally not  all  pianos  are  tuned  to  just  these 
values,  and  some  artists  insist  upon  having 
instruments  tuned  a  little  higher  or  a  little 
low^er.      Sometimes    the    terms    pitch    and 


ically   by   counting   the   number   of   waves 
per  second. 

Pitch  Thresholds 

The  loW'Cst  pitch  which  can  be  heai^d  is 
produced  by  a  frequency  of  about  20  cycles 
per  second,  although  a  tone  of  this  fre- 
quency must  be  quite  intense  to  be  audible. 
Still  lower  frequencies  produce  in  the  ear 
sensations  which  vary  from  intermittent 
pressure  to  a  noisy  flutter.  At  the  opposite 
end  of  the  scale,  the  highest  frequencs- 
which  can  be  heard  is  about  20,000  cycles 
per  second.  The  exact  threshold  point 
depends  again  upon  the  tone's  being  suf- 
ficiently   intense.       There    are    plentv    of 


322 


Hearing 


sounds  in  the  air,  sounds  produced  by  in- 
sects and  by  tiny  objects,  which,  being 
above  the  upper  limit,  are  never  heard  by 
human  ears.  Bats  have  been  found  to  send 
out  a  series  of  short  squeaks  whose  fre- 
quency is  over  50,000  cycles  per  second. 
(See   pp.    386-389.)      By   listening   for    the 


Frequency  "^ 

FIGURE    151.      PITCH  DISCRIMINATION 

This  figure  shows  the  proportionate  or  per  cent 
change  in  jrequeitcy  necessary  on  the  average  to 
hear  a  change  in  pitch.  Data  are  for  tones  40  deci- 
bels above  threshold.  [From  E.  G.  Shower  and  R. 
Biddiilph,  /.  acous.  Soc.  Amer.,  1931,  3,  284.] 

echoes,  they  are  able  while  in  flight  to  lo- 
cate either  obstacles  or  prey,  much  as  a 
boat  finds  its  way  through  a  narrow  chan- 
nel in  a  fog  by  blowing  its  whistle.  The 
greater  sensitivity  of  some  animals  to  these 
ultrasonic  frequencies  is  almost  certainly  a 
result  of  the  small  size  of  the  moving  parts 
of  their  ears  rather  than  to  the  possession 
of  any  special  sense  which  man  does  not 
possess. 

Between  20  and  20,000  cycles  per  second 
there  are  about  1500  steps  of  pitch,  each  of 


which,  under  favorable  conditions,  is  just 
as  often  as  not  distinguishable  from  the 
next  one.  They  are  threshold  steps— dif- 
ferential thresholds.  Their  size  is  charted 
in  Fig.  151.  Notice  that  the  measure  of 
the  differential  threshold  used  in  this  fig- 
ure is  the  relative  amount  of  change  in 
frequency.  This  is  the  way  we  should 
draw  the  figure  if  we  expected  something 
like  Weber's  law  for  frequency,  and,  in- 
deed, a  constant  proportion  appears  to  be 
necessary  above  1000  cycles  per  second. 
Below  that  value  quite  the  reverse  holds, 
and  the  minimum  change  is  marked  off  by 
a  constant  number  of  cycles.  A  rule  of 
thumb  is  that  a  good  listener  can  hear  a 
difference  between  two  tones  3  cycles  per 
second  apart  up  to  1000  cycles  per  second, 
and  then  a  constant  fractional  difference 
of  0.3  per  cent  (%ooo)  above  1000  cycles 
per  second.  Judged  by  any  standard,  this 
is  truly  remarkable  discrimination. 

The  Scale  of  Pitch 

These  steps,  that  is  to  say,  the  series  of 
notes  which  can  just  be  distinguished  from 
each  other,  give  us  one  kind  of  unit  in 
which  to  step  off  the  scale  of  pitch.  Are 
these  the  best  units  to  employ?  One  other 
possibility  would  be  to  use  frequency,  but 
almost  no  one  would  listen  to  a  series  of 
tones  5  cycles  per  second  apart,  or  50  cycles 
per  second  apart,  and  say  that  they  fonned 
a  series  with  equal  steps.  There  are,  on  the 
other  hand,  many  persons  who  would 
argue  warmly  that  pitch  is  proportional  to 
musical  interval,  such  as  the  octave,  the 
fifth  and  the  third. 

In  its  origin  the  diatonic  scale,  which  is 
the  basis  of  our  music,  used  the  octave  as 
its  unit  or  step.  Then  other  intervals  were 
added,  the  fifth  and  the  fourth,  then  the 
third  and  sixth,  until  the  octave  had  been 
divided  up  into  the  seven  familiar,  though 


Pitch  and  Loudness 


323 


unequally  spaced,  notes.  The  important 
fact  about  this  musical  scale  is  that  the 
size  of  a  given  step  depends  on  a  ratio  of 
the  two  frct|uencies.  An  octave,  for  in- 
stance, is  always  measured  by  doubling  or 


ifUUU 

1    1    1      1 

1        1          1        1 

3000 

- 

/- 

E 

- 

/ 

.E  2000 

- 

/               - 

/ 

a. 

- 

/ 

1000 

- 

/ 

^^^ 

- 

0 

— _-4-----r'"'i      1 

i        1          1        I 

Frequency  in  cycles  per  second 

FIGURE    152.      SCALE  OF  PITCH 

The  subjective  magnitude  of  pitch  is  measured  in 
mels.  The  curve  shows  how  the  number  of  mels 
increases  as  frequency  increases.  [From  S.  S.  Stevens 
and  J.  Volkmann,  Amer.  J.  Psychol.,  1940,  S3,  336.] 

halving  the  frequency.  Thus  if  we  start 
from  1000  cycles  per  second,  an  octave 
higher  would  be  2000  cycles  per  second, 
and  the  octaves  lower  would  be  500  and 
250  cycles  per  second. 

Recent  experiments  have  shown  that  it  is 
better  to  start  out  without  knowing  about 
ratios  and  frequencies,  and  simply  to  ar- 


range a  series  of  notes  so  that  they  sound 
to  the  ear  ecjually  far  apart  in  pilch.  The 
distance  between  any  pair  of  notes  in  the 
series  becomes  a  unit  of  }>ilch.  One  such 
scale  is  shown  in  Fig.  152  in  which  the  unit 
has  been  called  the  mel.  The  figure  shows 
just  how  the  mels  of  pitch  increase  with 
cycles  per  second.  Another  way  of  show- 
ing the  same  thing  is  to  distort  the  con- 
ventional piano  keyboard  so  that  each  key 
is  as  wide  as  the  number  of  mels  it  in- 
cludes. The  result,  shown  in  Fig.  153, 
makes  very  clear  how  much  the  musical 
.scale  and  the  mel  scale  differ  from  each 
other. 

LOUDNESS 

An  even  more  general  characteristic  of 
sounds  than  pitch  is  loudness.  Both  tones 
and  noises  can  be  called  loud  or  soft. 
Loudness  is  easily  recognized  as  the  inten- 
sitive  aspect  of  sound,  the  more-or-less, 
which  corresponds  to  saturation  in  vision 
and  the  strength  of  a  smell  or  taste. 

For  any  single  kind  of  a  tone  or  noise, 
it  is  easy  to  say  what  is  the  physical  change 
which  makes  a  sound  louder.  Loudness 
depends  simply  on  the  amplitude  of  the 
sound  wave.  It  is  fairly  difficult  to  say 
what  will  be  the  comparative  loudness  of 
two  sounds  of  different  frequency  or  of  two 
noises.  As  we  shall  see  (pp.  325  f.),  we  have 
to  know  much  more  than  the  relative  am- 
plitudes of  the  two  waves. 


ill!lll!!l!!!l!!l!!! 


FIGURE    153.      THE  MEL  KEYBOARD 

The  piano  keyboard  is  distorted  so  that  equal  distance  represents  equal  amounts  of  pitch  rather  than 
equal  units  on  the  musical  scale.  This  shows  why  melodies  are  so  much  clearer  when  played  in  the 
treble  than  when  played  in  tlie  bass. 


324 


Hearing 


— 



r 

1 

"T" 

-f 



— 

Thre 

shold 

of  feeling 

1 

-^ 

\, 

/ 

\ 

s 

/ 

■Thres 

lold 

of  he 

aring- 

\^ 

/ 

Ag 

Age  f 

/ 

^ 

^v 

/ 

ZZ. 

y 

Loudness  Thresholds 

The  softest  sound,  the  weakest  intensity 
which  we  ever  hear,  lies  at  the  absolute 
threshold  for  hearing.  If  we  measure  the 
least  sound  pressure  under  an  earphone  at 
which  a  tone  can  be  heard,  we  get  results 
shown  in  the  lower  curve  of  Fig.  154.  No- 
tice how  different  are  the  amounts  required 

140 


^120 
tlOO 

a> 

c 

"°   80 

CNJ 
O 

§   60 
o 

'  II 
^   40 

T3 
O 

-   20 


Frequency  in  cycles  per  second 

FIGURE    154.      THRESHOLD    OF    HEARING 

Lower  solid  curve  shows  the  lowest  sound  pres- 
sure which  can  be  heard  by  a  practiced  listener  20 
to  30  years  of  age.  Above  this  the  dotted  curve 
shows  the  threshold  for  an  average  listener  of  60. 
The  dashed  line  at  the  top  shows  initial  threshold 
of  feeling  for  both  hard-of-hearing  and  normal  sub- 
jects. All  values  are  pressures  under  earphone  at 
entrance  to  ear  canal. 

at  different  frequencies.  A  pressure  1000 
times  (60  decibels)  greater  is  required  at  60 
cycles  per  second  than  at  2000  cycles  per 
second.  This  curve  shows  what  a  person 
with  good  hearing  can  do  when  he  is  about 
20  years  old.  As  he  grows  older,  the  mem- 
branes in  his  ear  stiffen  and  nerve  fibers 
degenerate.  The  average  sensitivity  of  a 
man  of  60  is  shown  in  the  dotted  curve. 
Note  that  he  has  lost  completely  his  hear- 
ing for  the  very  highest  frequencies  and 
that  he  has  some  loss  in  sensitivity  through 
the  middle  range. 


Just  how  loud  sound  can  be  before  hear- 
ing is  permanently  injured  cannot  be  speci- 
fied with  certainty.  Moderately  loud  noise, 
if  it  lasts  for  a  long  time,  will  produce  a 
measurable  deafness.  Instances  are  the 
deafness  produced  by  long  practice  on  a 
rifle  range,  flight  in  an  open  or  uninsu- 
lated airplane  or  work  in  the  jaiessroom  of 
a  large  newspaper.  More  severe  noises, 
noises  that  are  actually  painful,  such  as  the 
rapid  fire  of  anti-aircraft  guns  or  the  noise 
of  the  loudest  sirens,  will  produce  an  al- 
most complete  deafness  for  high  tones  in  a 
very  short  time.  So  far  as  laboratory  ex- 
periments have  gone,  normal  persons  ex- 
posed to  such  very  loud  noises  have  always 
recovered— fortunately.  The  uncertainty 
arises  from  the  fact  that  there  are  wide  dif- 
ferences among  people  in  the  ease  with 
which  they  suffer  injury.  Some  people 
may  perhaps  incur  not  only  temporary  but 
also  actually  permanent  losses  from  ex- 
posure to  continued  loud  noise.  Opinions 
on  this  point  differ  widely. 

Before  a  level  is  reached  which  causes 
the  most  severe  temporary  losses,  most  lab- 
oratory subjects  will  object  strenuously.  As 
the  sound  grows  louder  it  tickles,  then  can 
be  felt  as  something  jabbing  at  the  ear.  It 
is  piercing  and  unpleasant,  and  finally 
painful.  The  level  at  which  this  takes 
place  is  shown  in  Fig.  154  as  the  threshold 
of  feeling.  Hard-of-hearing  persons  report 
the  same  experiences  with  the  same  le\cls 
of  stimulation.  Appai'ently  the  small  hairs 
in  the  ear  canal  are  being  moved,  and  the 
drum  stretched  beyond  its  comfortable 
limit. 

The  Scale  of  Loudness 

Just  as  for  pitch,  a  scale  must  be  con- 
structed for  loudness.  The  physical  scale 
used  to  measure  the  amplitude  of  the  sound 
wave  is  a  logarithmic  scale  on  which  equal 


Loudness 


32t 


steps  stand  for  equal  ratios.  The  unit  is 
the  decibel  (clb),  which  represents  a  ratio 
of  1:1.13  between  two  pressures.  In  other 
words,  a  13  per  cent  increase  in  pressure 
equals  an  increase  of  one  decibel.  Decibels 
are  like  compound  interest,  and  successive 
decibel  steps  are  given  by  1.0  X  1.13  X  1.13, 
not  1.00  +  0.13  +  0.13.     Decibels  also  have 


20  40  60  80  100 

Sound  pressure  in  decibels 

FIGURE     155.       SCALE    OF    LOUDNESS 

How  loudness  as  judged  subjectively  grows  as  a 
function  of  sound  pressure  in  decibels.  Note  that 
sound  pressiues  below  40  decibels  have  almost  no 
loudness,  and  only  above  80  decibels  does  loudness 
grow  rapidly. 

to  start  from  somewhere  and  be  about 
something.  Actually,  decibels  are  just 
numbers,  like  2  or  10.  When  we  talk  about 
sound  pressure  level,  we  arbitrarily  use  as  a 
zero  point  0.0002  dyne  per  square  centi- 
meter. Then  0-decibel  sound  pressure 
level  equals  0.0002  dyne  per  square  centi- 
meter, 20-decibel  equals  0.002  dyne,  and  74- 
decibel  equals  1  dyne  per  square  centi- 
meter. 

This  physical  scale  makes  fairly  good  psy- 
chological sense,  for  the  number  of  just 
noticeable  differences  of  a  sound  above 
the  threshold  corresponds  roughly  with  the 
number  of  decibels  it  is  above  its  thresh- 
old.    Difficulty  occurs  when  ^^'e  divide  the 


whole  range  of  sound  intensities,  for  out  of 
120  decibels  between  the  absolute  thresh- 
old and  the  loudest  sound  corimionly  heard, 
the  first  40  decilK-ls  just  get  up  to  an  audi- 
ble whisper  and  80  decibels  are  only  a  good 
conversational  level.  To  get  a  proper 
psychological  scale  it  is  necessary  to  resort 
to  direct  judgment.  Suppose  we  begin 
with  a  certain  faint  sound  and  find  a  sec- 
ond sound  that  seems  twice  as  loud;  then 
we  find  a  third  sound  that  seems  twice  as 
loud  as  the  second;  and  so  on.  From  these 
results  we  can  construct  a  scale  of  loudness 
like  the  one  shown  in  Fig.  155.  Loudness 
grows  very  slowly  until  a  level  of  60  deci- 
bels is  reached,  and  then  it  goes  up  at  an 
ever-increasing  rate  as  far  as  the  function 
has  been  measured. 


140 
^120 

'iilOO 


^8    60 

°-  II 
"i.D    40 

O  o 

co^    20 


100       200  500      1000     2000        5000    10.000 

Frequency  in  cycles  per  second 

FIGURE    156.      EQUAL-LOUDNESS   CONTOURS 

Tones  corresponding  to  the  points  along  each 
curve  sound  equally  loud.  Near  each  cur\e  is  given 
the  loudness  in  sones.  Zero  sones  equal  the  abso- 
lute threshold. 

We  noted  earlier  that,  for  a  single  tone, 
it  is  the  amplitude  of  the  sound  wave  which 
determines  loudness.  Now  we  must  qualify 
that  by  saying  that  loudness  depends  also 
upon  the  frequency  of  the  tone.  First  of 
all,  we  observe  that  the  threshold  for  low 
tones  and  vevy  high  tones  is  much  larger 
than  the  threshold  for  tones  in  the  middle 


Thresho  d  of  feeling-^ 

150  sones 

^ 

- 

100  sones            _^ 

50  sones         ^^,,0^ 



20  sones      ^^^ 

v 

^^^ 

■ 

^ 

y 

^>-^ 

0  sones     ^.....^■•^^ 

326 


Hearing 


frequencies.  That  is  clear  in  Fig.  154.  At 
moderately  high  levels,  -vvell  above  thresh- 
old, loudness  shows  less  variation  with  fre- 
quency. To  show  this,  scientists  construct 
an  equal-loudness  contour  by  adjusting  a 
high  tone  to  a  low  tone  until  one  sounds 
just  as  loud  as  the  other.  Measuring  the 
intensity  of  each  tone  makes  it  possible 
to  draw  the  typical  equal-loudness  con- 
tours which  are  shown  in  Fig.  156.  Since 
the  distance  in  decibels  from  the  one-sone 
to  the  fifty-sone  contour  is  less  at  the  low 
frequencies  than  at  the  high,  it  follows  that 
loudness  must  grow  more  rapidly  at  low 
frequencies  than  at  high. 

INTERACTION    OF    STIMULI 

Next  we  ha\e  to  ask  what  happens  when 
two  or  more  tones  sound  together.  How  do 
they  affect  each  other? 

Beats  and  Combination  Tones 

To  many  a  novice  the  skill  of  the  piano 
tuner  appears  as  something  like  magic,  yet 
one  of  the  devices  he  uses  is  so  simple  that 
only  a  little  attention  is  required  for  any- 
one to  hear  it.  This  is  the  use  of  heats 
which  occur  whenever  two  tones  sound  to- 
gether while  differing  only  slightly  in  fre- 
quency. Beats  sound  like  an  alternate 
waxing  and  waning,  a  rhythmic  wow-wow 
of  the  two  almost  fused  tones.  A  keen  ear 
can  hear  a  very  slow  beat  requiring  as 
much  as  five  or  ten  seconds  to  come  and 
go.  As  beats  become  faster  they  sound 
like  a  pulsating  tone,  and  then  they  lose 
their  individual  identity  and  become  sim- 
ply a  roughness  which  is  superimposed  on 
the  two  now  distinguishable  tones. 

A  little  consideration  makes  the  origin 
of  beats  quite  clear.  Suppose  two  strings 
vibrate  at  slightly  different  rates,  say,  500 
and  501  cycles  per  second.     If  the  strings 


are  struck  simultaneously  both  strings  will 
move  together,  and  the  sound  waves  pro- 
duced by  each  will  reinforce  each  other. 
Now  notice  what  will  happen  one-half  sec- 
ond later;  the  one  string  will  have  com- 
pleted 250  vibrations  and  the  other  250^4 
vibrations.  In  other  words,  the  strings  will 
now  be  in  opposite  phases,  one  of  them 
producing  the  peak  of  a  pressure  wave 
while  the  other  produces  a  trough.  Under 
these  conditions  the  sound  waves  cancel 
each  other,  and  a  much  weaker  sound  will 
be  heard.  Finally  at  the  end  of  a  full  sec- 
ond, both  will  again  be  in  phase. 

Comparable  is  the  phenomenon  of  differ- 
ence tones  which  require  more  special  cir- 
cumstances if  they  are  to  be  heard.  When 
the  two  tones  that  are  led  to  the  ear  are 
fairly  strong,  and  have  a  frequency  differ- 
ence of  about  50  cycles  per  second  or  more, 
one  or  more  tones  may  be  heard  in  addi- 
tion to  the  primary  pair.  The  most  promi- 
nent of  such  tones  is  a  difference  tone;  it 
has  the  pitch  which  belongs  to  the  fre- 
quency equal  to  the  difference  in  frequency 
of  the  primaries.  Under  good  conditipns, 
when  the  primaries  are  loud,  a  summation 
tone,  whose  pitch  corresponds  to  the  sum 
of  the  frequencies  of  the  primary  tones,  can 
also  be  heard.  Thus,  for  example,  the 
tones  700  and  1200  cycles  per  second  may 
produce  a  difference  tone  of  500  and  a  sum- 
mation tone  of  1900  cycles  per  second.  If 
the  primary  tones  contain  strong  upper 
harmonics,  there  may  be  other  combina- 
tion tones,  although  they  usually  are  so 
faint  as  to  escape  notice. 

Masking 

Masking  is  the  official  name  given  to  the 
familiar  fact  that  one  soimd  drowns  out 
another.  Interest  in  masking  stems  from 
the  efforts  of  telephone  engineers  to  im- 
prove service  at  those  critical  points  where 


Beats,  Combination  Tones  and  Masking 


327 


messages  are  lost  in  the  background  of 
noise.  It  is  equally  important  in  radio 
communication  and  in  the  choice  of  bells 
and  alarms  which  must  be  lieard  under 
competition  with  other  noise. 

The  facts  about  the  masking  of  one  pure 
tone  by  another  are  summed  up  in  the 
curves  of  Fig.  157.  The  amount  of  mask- 
ing is  measured  by  how  much  change  there 


0  800  1600         2400        3200         4000 

Frequency  of  masked  tone  in  cycles  per  second 

FIG.    157.      AUDITORY    MASKING 

The  curves  show  how  much  the  threshold  is 
raised  at  each  frequency  as  a  result  of  the  masking 
by  a  1200  cycles  per  second  tone  40  decibels,  60 
decibels,  and  80  decibels  above  its  threshold.  [After 
R.  L.  Wegel  and  C.  E.  Lane,  Phys.  Rev.,  1924,  23, 
271.] 

is  in  the  absolute  threshold  for  any  given 
tone  when  it  is  masked  by  another.  In 
this  experiment,  for  instance,  the  threshold 
was  first  determined  in  a  quiet  room  for 
many  frequencies  between  400  and  4000 
cycles  per  second.  Then  a  masking  tone 
of  1200  cycles  per  second  was  turned  on, 
and  all  the  thresholds  were  found  to  have 
been  raised  by  the  amounts  shown  in  the 
figure.  The  results  for  three  levels  of  the 
masking  tone  are  shown,  with,  obviously, 
the  greater  amount  of  masking  when  the 
masking  tone  is  more  intense.  The  curves 
also  show  one  other  important  fact;  the 
masking    of    high    tones    by    a    low    tone 


is  much  greater  than  the  masking  of  low 
tones  by  a  higher  one.  The  practical  ef- 
fect of  this  principle  appears  when  some 
kinds  of  sound-deadening  treatment  give 
disappointing  results  in  a  room.  The 
sound-absorbing  material  may  remove  the 
high  frequencies  quite  well,  but  it  usually 
has  too  little  effect  at  medium  and  low  fre- 
quencies. Yet  it  is  just  these  low  frequen- 
cies which  do  most  of  the  masking. 

If  an  engineer  wishes  to  use  the  infor- 
mation about  masking  in  finding  out  how 
well  a  given  telephone  or  radio  circuit  will 
perform,  he  must  know  a  good  many  tech- 
nical details.  In  the  final  analysis  the  im- 
portant thing  is  the  ratio  of  the  desired 
sound  to  the  noise,  the  signal-to-noise  ratio, 
which  should  be  known  for  at  least  twenty 
bands  of  frequencies  spaced  equally  along 
the  mei  scale. 

HOW    THE    EAR    WORKS 

Up  to  this  point  we  have  been  describing 
what  the  ear  does;  now  we  must  see  hoiv 
the  ear  works.  What  kind  of  mechanism 
makes  possible  the  discriminations  of  pitch 
and  loudness?  To  answer  this  question,  it 
will  be  necessary,  first,  to  discover  how  the 
ear  is  constructed  and,  second,  to  explain 
what  the  various  parts  of  the  ear  do  in  re- 
ceiving a  sound  wave. 

Unfortunately,  the  obser^■ation  of  the  ear 
is  made  unusually  difficult  by  its  location 
buried  in  bones  of  the  head.  Anatomists 
have  disagreed  about  the  fine  structure  of 
the  inner  ear,  either  because  they  have  dam- 
aged the  ear  while  cutting  tlie  bone  away 
or  because  the  delicate  tissues  have  disinte- 
grated before  preservatives  could  penetrate 
the  bony  shell.  Only  in  very  recent  years 
has  anyone  seen  the  innermost  parts  of  the 
ear   actuallv   working,   and   todav   the   best 


328 


Hearing 


observations  lca\c  much  room  for  specula-  transmitting  this  motion  in  imn  through  a 

tion  and  opinion.  set  of  rods  to  a  small  piston;  and  third,  a 

In  its  basic  design  the  car  is  quite  nicely  hydraulic   analyzer   driven   by   this   piston. 

adjusted   for   its    jol).      It   has   three   parts:  Distributed    to   various   parts   of   this   ana- 


Inner  ear 


Auditory 
nerve 


Eustachian 
tube 


Hammer 


FIGURE   lfi8.      SECTION  THROUGH  THE  EAR 


This  cross-section  shows  the  principal  parts  of  the  outer,  middle  and  inner  ear,  nith  the  last  bur- 
ied within  the  skull.  The  inner  ear  has  been  rotated  so  it  may  be  seen  in  better  detail.  The  three  os- 
sicles, somewhat  enlarged,  are  also  shown  separately  at  the  bottom  of  the  figure.  [From  G.  McHugh,  in 
S.  L.  Polyak,  Tlie  liuiiian  car,  Sonotone  Corporation,  1946.] 


first,  the  recei\'ing  part,  a  horn  and  funnel- 
shaped  tube  which  collects  the  sound  and 
leads  it  to  the  ear;  second,  the  conducting 
part,  a  light  drum-head  diaphragm  which 
is   moved   back    and    forth    by    the    sound. 


lyzer  are  the  nerve  endings  which  start  im- 
pulses up  over  the  auditory  nerve  to  the 
hearing  centers  in  the  central  nervous  sys- 
tem. 

.\  vertical   cut   through   the  head,   made 


How  the  Ear  Works 


329 


in  a  siiilal)le  phmc,  would  lay  bare  the 
hidden  parts  ol  the  ear  shown  in  Fig.  158. 
'lo  the  left  is  the  rea:ivin<T  part,  the  outer 
car,  consisting  ol  the  pinna  and  the  ear 
canal.  The  eondiuting  part,  the  middle 
ear,  consists  of  the  cavity  behind  the  ear 
drum  and  includes  the  tiny  bones  and  mus- 
cles lying  within  that  cavity.  The  ana- 
lyzer is  contained  within  the  inner  ear, 
which  lies  buried  in  the  temporal  bone  in 
the  floor  of  the  case  surrounding  the  brain. 
The  important  part  of  the  inner  ear  for 
hearing  is  the  snail-shaped  cochlea  which 
we  shall  examine  in  detail  in  just  a  mo- 
ment. 

The  Outer  Ear 

In  many  animals  tlae  outer  ear  serves  as 
an  efficient  collector  of  sound  which  in- 
creases substantially  the  intensity  of  the 
waves  reaching  the  eardrum.  Equally  im- 
portant to  many  animals  is  the  fact  that  the 
pinna  is  often  movable,  a  capacity  which 
aids  them  in  locating  a  source  of  sound. 
In  some  animals,  such  as  the  seal,  the  parts 
of  the  outer  ear  may  be  folded  together  to 
form  a  tight  protective  cover  for  the  ear 
canal.  Men  get  along  without  much  help 
from  their  outer  ears  in  any  of  tliese  re- 
spects. Our  pinnas  help  us  slightly  in  lo- 
cating high-pitched  noises  as  being  in  front 
or  in  back.  Moreover,  our  ear  canals  are 
effective  horns  for  sound  frequencies  near 
3000  cycles  per  second,  amplifying  the 
sound  pressure  six  or  eight  times.  But 
principally  our  outer  ears  are  but  vestiges 
of  the  more  useful  ears  which  our  night- 
hunting  arboreal  ancestors  once  possessed. 

Across  the  inner  end  of  the  auditory 
canal,  and  closing  off  the  cavity  of  the 
middle  ear,  is  the  eardrum,  a  thin  skinlike 
membrane  pulled  slightly  inward  at  its  cen- 
ter where  it  is  attached  to  the  hammer,  the 
first  of  the  bony  links   to   the   inner  ear. 


I  Jie  (IniMi  in  area  is  a  little  larger  than  the 
end  of  a  pencil.  The  drum  itself  is  not 
under  particular  tension;  th(;  resistance  it 
r)ffers  lo  movement  by  sound  waves  is  a 
result  of  its  inertia  at  high  frequencies.  The 
(hum  si  ill  works  ama/ingly  well  when  it  is 
pierced;  the  loss  in  sensitivity  can  scarcely 
l)e  measured.  Even  a  small  remnant  of 
drum  attached  to  the  hammer  bone  of  thc 
middle  ear  permits  some  effective  heaiing. 

The  Middle  Ear 

The  middle  ear  is  a  small  air-fdled  cavity, 
lying  within  the  temporal  bone.  Its  loca- 
tion can  be  seen  in  Fig.  158.  The  front 
end  of  the  cavity  connects  with  the  back  of 
the  nose  through  the  Eustachian  tube,  and 
at  the  other  end  the  middle  ear  broadens 
out  into  the  sinuses  of  the  mastoid  bone. 
Its  roof  is  a  thin  plate  in  the  floor  of  the 
bony  brain  case. 

The  important  parts  lying  within  the 
middle  ear  are  shown  in  Fig.  159.  The 
three  small  bones  or  ossicles,  knoAvn  equally 
well  by  their  English  or  Latin  names,  the 
hammer  or  malleus,  the  anvil  or  iyicus  and 
the  stirrup  or  stapes,  form  a  bridge  to  carry 
sound  from  the  eardrum  to  the  cochlea. 
The  hammer  attaches  firmly  to  the  ear- 
drum while  the  foot  plate  of  the  stirrup,  in 
area  roughly  equal  to  a  section  of  a  pencil 
lead,  is  fitted  into  tlie  oval  icindow,  one  of 
two  openings  through  the  bone  from  the 
middle  ear  into  the  canals  of  the  inner 
ear.  The  second  opening,  the  round  irin- 
doiu,  affords  relief  for  the  pressure  pro- 
duced in  the  inner  ear  as  the  stirrup  mo\es 
in  and  out. 

The  action  of  the  middle  ear  is  to  make 
the  incomina:  sound  ^vave  most  effective  at 
one  point  in  the  inner  ear.  nameh,  at  die 
o\al  window.  The  sensiti\e  cells  of  the 
inner  ear  are  immersed  in  fluid:  their  stim- 
ulation   depends    on    movements    of    this 


330 


Hearing 


Footplate  of  stirrup 

Vestibule  of  inner  ear 


Centimeters 
0  0.2  0.4  0.6  O.i 


FIGURE    159.      THE  MIDDLE  EAR  AND  THE  OSSICLES 

This  cross-section  has  been  constructed  to  show  the  relative  size  and  spatial  relations  o£  the  ossicles 
acting  as  a  bridge  to  carry  sound  to  the  inner  ear.  [After  A.  Keith,  in  T.  Wrightson.  A„  enquin  into 
the  ntmhiical    mechanism    of   the   internal   ear,   Macmillan.   1918,  p.    190.] 


fluid.  The  sound  waves  consist  of  only 
small  changes  in  pressure  in  the  air,  an 
easily  compressible  medium.  Much  more 
pressure  is  required  to  set  the  fluid  in  mo- 
tion. This  pressure  is  obtained  by  hav- 
ing all  the  relatively  small  air  pressure 
over  the  large  eardrum  brought  to  bear  on 
the  small  foot  plate  of  the  stirrup  in  con- 


tact with  the  fluid.  Altogether,  a  mechan- 
ical advantage  of  about  thirty  to  one  is  ob- 
tained by  this  device. 

The   Inner  Ear 

Immersed  within  the  hard  petrous  por- 
tion of  the  temporal  bone  are  the  series  of 
canals  which  contain  the  ir^ner  ear.     They 


The  Inner  Ear 


331 


appear  in  shadowy  outline  in  Fig.  158. 
I'he  first  chamber  ciKcred  Ironi  the  middle 
car  is  the  vcslibule,  one  rorner  of  which  is 
shown  in  Fig.  1.59.  Leading  oil  to  the  back 
are  the  semicirculnr  (fiiuils  whidi  serve  an 
imjjortant  function  in  our  sense  ol  bodily 
movement  (pp.  .H7'1-.H77).  Fo  the  front  lies 
the  snail-shaped  coc/ilrn,  the  important 
organ  of  hearing. 

A  eu(  through  ihe  (en(er  of  the  snail 
shell  reveals  the  inside  of  the  canals,  as 
sliown  in  Fig.  160.  Fhis  reproduction  is  a 
considerable  enlargement.  'Fhe  lull  width 
of   the  section   shown    is   only   about   one- 


louitli  iiiih.  1  he  human  fochlea  has  three 
full  turns;  only  two  and  one-half  turns  aie 
shown  here.  Inspection  shows  that  ih( 
cochlea  is  actually  divided  into  three 
canals:  a  lower  canal,  called  the  sfala  tym- 
prnii,  an  upper  canal,  called  the  srala 
veslibuli,  and  a  small  canal  on  the  outer 
side,  called  the  rorhlenr  flurl.  The  two 
larger  canals  are  (onneded  logether  at  th( 
very  tip  of  the  cochlea  through  an  opening, 
the  hf'Ucotrema.  F'eeding  up  through  the 
very  middle  of  the  cochlea  is  the  auditory 
nerve. 

We   can   see   the   location   of   the   artual 


Scala  vestibuli 
Cochlear  duct 


FIGURE   l6o.      INSIDE  OF  THE  COCHLEA 

Section  through  the  'snail-shell,'  the  spiral  cochlea.  The  scala  vestibuli.  the  scala  tvpani  and  the  coch- 
lear duct  are  spiral  canals  which  can  be  seen  to  be  receding  and  curving  along  with  the  basilar  mem- 
brane, the  oigan  of  Corti,  the  spiral  ligament  and  the  bony  shelf.  (See  Fig.  161.)  The  auditory  nerve 
runs  up  the  middle  from  below. 


332 


Hearing 


sense  cells  and  the  nerve  endings  more 
readily  in  the  diagrammatic  cross-section  of 
Fig.  161.  We  can  recognize  here  the  larger 
features  of  the  cochlea  which  appeared  in 
the  previous  figiue.    In  addition  we  can  see 


organ  of  Corti  are  the  nerve  fibers  from 
the  spiral  ga}7gIiou,  the  first  way  station  on 
the  path  to  the  brain. 

The  organ  of  Corti  itself  consists,  as  Fig. 
162  shows,  of  a  framework  which  carries  in 


Cochlear  duct 


Tectorial  membrane 


Spiral  ligament 


Organ  of  Corti 


Spiral  ganglion 

Auditory  nerve 


FIGURE   l6l.      LOCATION  OF  THE  BASILAR  MEMBRANE  AND  ORGAN  OF  CORTI 

The  cochlear  lulie  is  divided  iiilo  two  parts  by  a  partition  consisting  of  the  bony  shelf,  the  basilar 
membrane  and  the  spiral  ligament.  [After  A.  Keith,  in  T.  VVrightson,  An  enquiry  into  the  aiialyliral 
iiiechaiiism   of  the  iuternal  ear,  Macmillan.   1918,  p.    192.1 


that  the  partition,  part  of  which  is  between 
the  scala  vestibuU  and  the  scala  tympani 
and  part  between  the  scala  tympani  and 
the  cochlear  duct,  is  made  up  of  a  bony 
shelf  as  inner  part,  the  thick  spiral  liga- 
ment attached  to  the  outer  wall,  and,  sus- 
pended between  them,  the  basilar  mevi- 
branc  on  which  rests  the  organ  of  Corti. 
Passing  out  through  the  bony  shelf  to  the 


its  upper  surface  the  hair  cells,  believed  to 
be  the  source  of  stimulation  for  tiny  end- 
ings of  the  nerve  fibers.  The  hair  cells  get 
their  name  from  the  fact  that  each  cell 
bears  a  series  of  fine  hairlike  projections  on 
its  upper  surface,  hairs  which  are  embed- 
ded in  the  jellylike  material  of  the  tectorial 
membrane.  The  thin  Reissner's  mem- 
brane   separates    the    two    cochlear    fluids, 


How  the  Cochlea  Works 


333 


perilymph  in  the  scala  vcstibuli  and  scala 
tympani  and  endolyrnph  in  the  cochlear 
duct,  but  it  has  no  inijjortant  effect  on  the 
way  the  sense  cells  on  the  basilar  mem- 
brane behave. 


FIGURE    l6a.      THE    ORGAN    OF    CORII 

Much  enlarged  view  of  actual  sensory  cells, 
single  inner  row  and  multiple  outer  row  of 
cells. 


Note 
bair 


How  the  Cochlea  Works 

In  explaining  the  action  of  the  outer  ear 
and  of  the  middle  ear,  we  have  had  to  deal 
solely  with  physical  principles,  how  sound 
waves  in  the  air  are  turned  into  to-and-fro 
movements  of  the  stirrup,  which  acts  like 
a  piston  to  pump  back  and  forth  the  fluids 
of  the  cochlea.  The  crux  of  the  problem 
of  hearing  comes  when  this  physical  move- 
ment in  the  cochlea  has  to  be  changed  into 
the  electrochemical  message  in  the  auditory 
nerve  and,  in  particular,  into  a  message 
which  can  be  interpreted  by  the  brain  in 
terms  of  the  psychological  characteristics  of 
pitch  and  loudness.  Of  course  not  all  of 
this  transformation  from  physical  move- 
ment to  psychological  attribute  need  take 
place  in  the  cochlea,  but  it  must  at  least 
start  there.  Let  us  see  first  what  happens 
in  the  cochlea  to  explain  loudness.  After 
that  we  may  turn  to  the  problem  of  pitch. 

Since  loudness  is  an  intensitive  attribute, 
we  should  expect  to  find  some  correspond- 
ing characteristic  of  the  nervous  response 
which  can  also  be  large  or  small,  greater  or 


less.  ()i\  lh(;  (jther  hand,  the  all-oi-none 
response  of  each  single  nerve  fiber  does  not 
permit  a  direct  transformation  from  me- 
chanical intensity  into  intensity  in  the  indi- 
vidual fifjcr.  I'hysiology  tells  us  that  the 
most  common  way  intensity  is  represented 
in  the  nervous  system  is  by  transforming  it 
into  the  frequency  of  response  of  any  given 
fiber  (p.  30).  This  probably  happens  in 
the  ear  as  well  as  in  other  sense  organs. 
When  a  weak  scnuid  leaches  the  threshold 
lor  a  given  libei,  ii  fires  off  only  now  and 
then;  as  the  stiiiiujus  becomes  more  in- 
tense, the  response  of  the  fiber  becomes 
more  frecjuent  until  that  fiber  is  working 
at  top  speed. 

This  cannot,  however,  be  the  sole  ex- 
planation of  loudness.  There  are  two  dif- 
ficulties. First,  the  range  of  intensities 
over  whicJi  the  response  of  a  single  fiber 
can  be  graded  in  frequency  is  quite  small, 
perhaps  only  as  much  as  30  to  1.  The 
range  of  intensities  over  which  the  ear  re- 
sponds with  distinguishable  steps  of  loud- 
ness is  very  large,  at  least  10,000,000  to  1. 
The  one  can  hardly  be  expected  to  take 
care  of  the  other.  The  second  difficidtv 
complicates  the  first.  At  low  frequencies, 
as  we  shall  see  in  a  moment,  the  nerve 
fibers  are  tripped  off  by  the  indi\idual 
sound  waves,  so  that  the  fibers  tend  to  ha^e 
the  same  frequency  of  response  as  the  fre- 
quency of  the  sound  ■^va^e. 

Loudness  must  be  explained,  tlierefore, 
also  in  terms  of  the  total  number  of  acti\e 
nerve  fibers.  At  low^  intensities  there  ai'e 
only  a  few  fibers  active,  at  high  intensities 
a  great  many  more.  Loudness  will  depend 
both  on  how  many  fibers  are  working  and 
on  how  often  each  one  of  them  fires.  It 
will  be  gauged  ultimatelv  bv  the  total  num- 
ber of  impulses  in  a  large  bundle  of  fibers. 
How  is  it  that  additional  fibers  go  into  ac- 
tion with  increased  intensitv? 


334 


Hearing 


Probably  two  things  happen.  First  of 
all,  not  all  fibers  have  the  same  threshold. 
Quite  different  sound  intensities  are  re- 
quired to  set  off  different  fibers.  Second, 
there  are  in  the  ear  two  mechanisms  which 
may  act  much  as  do  the  rods  and  cones  of 
the  eye.  They  are  the  inner  and  outer  hair 
cells  which  can  be  distinguished  by  a  care- 


•  Stapes 


IIGURE    163.      ACTION  OF  THE  COCHLEA 

Diagram  represenls  cochlea  unrolled,  and  indi- 
cates loughlv  how  it  responds  differently  to  vari- 
ous frequencies.  In  A,  slow  movement  of  stapes  de- 
presses basilar  membrane  and  pushes  fluid  through 
helicotrema.  In  B,  fast  movement  of  stapes  de- 
presses near  end  of  basilar  membrane  up  to  limit- 
ing point  where  circular  eddy  marks  end  of  stimu- 
lated area.  [.Adapted  from  G.  Bekcsy,  Phys.  Z.. 
1928.  29,  793-810.] 

fill  inspection  of  Fig.  152.  The  inner  hair 
cells  are  much  like  the  cones  for  they  have 
each  a  single  nerve  fiber  and  recjuire  more 
vigorous  stimulation  of  the  ear  to  set  them 
off.  The  outer  hair  cells  are  like  the  rods, 
connected  in  teams  to  each  nerve  fiber  and 
so  placed  that  the  least  movement  will  set 
them  off.  Third,  as  we  shall  see  presently, 
the  more  intense  sounds  bring  a  larger  pro- 
portion of  the  basilar  membrane  into 
action. 

To  sum  up,  loudness  depends  on  how 
many  impulses  arrive  at  some  center  in 
the  brain.     Just  how  many  impulses  there 


will  be  depends,  in  turn,  upon  how  fast 
each  single  fiber  is  firing,  upon  the  thresh- 
olds of  each  fiber,  and  whether  all  the 
fibers  in  one  area  have  been  called  into  ac- 
tion, upon  the  fiber's  connection  with  the 
outer  or  inner  hair  cells  and  upon  how 
wide  a  section  of  the  basilar  membrane  is 
involved. 

Pitch,  in  contrast  with  loudness,  requires 
that  the  receptors  make  some  discrimina- 
tion in  kind.  Either  there  must  be  differ- 
ent types  or  varieties  of  the  sense  cells,  as 
we  suppose  there  are  among  the  various 
skin  senses,  or  else  the  location  of  the  sense 
tell  and  the  particular  nerves  to  which  it 
is  connected  is  important,  as  in  visual  and 
tactual  space.  The  first  alternative  is 
scarcely  plausible,  and  the  weight  of  evi- 
dence today  favors  the  view  that  the  recep- 
tors giving  rise  to  the  experience  of  a  par- 
ticular pitch  have  a  particular  location  in 
the  cochlea. 

Let  us  look  more  closely  at  the  cochlea. 
Imagine  that  the  snail  shell  is  unrolled  so 
that  it  becomes  a  long  socklike  tube.  Cut 
lengthwise  it  would  look  like  Fig.  163. 
The  tube  is  divided  into  an  upper  and 
lower  half  by  the  bony  shelf  and  the  basilar 
membrane.  Only  at  the  extreme  tip  of 
the  tube  do  the  two  canals  join  (by  way  of 
the  helicotrema).  To  the  left,  forcing 
liquid  in  and  out  of  the  upper  canal,  is 
the  stirrup,  driven  by  the  sound  wave. 
Closing  the  lower  canal  is  the  round  win- 
dow which  can  bulge  into  the  middle  ear 
as  the  stirrup  pushes  in  at  the  top. 

Now,  if  the  stirrup  is  pushed  slowly  into 
the  upper  canal,  fluid  will  flow  up  along 
the  cochlea,  through  the  helicotrema  and 
down  to  the  round  window.  At  the  same 
time  the  pressure  will  be  slightly  greater  on 
the  one  side  than  on  the  other,  and  the 
basilar  membrane  will  be  bent  down  into 
the  position  shown  by  the  solid  line  in  A 


How  fhe  Cochlea  Works 


335 


of  Fig.  163.  It  will  be  depressed  somewhat 
more  at  the  end  aivay  from  the  oval  win- 
dow because  the  basilar  membrane  grows 
raider  toivard  the  tip  of  the  canal.  Pull  the 
stirrup  back  and  the  reverse  motion  lakes 
place  with  the  basilar  nicnibiane  in  the 
position  indicated  by  the  dashed  line. 

Let  the  movement  of  the  stirrup  be  more 
rapid,  and  there  will  no  longer  be  lime  lor 


different  investigators,  each  using  a  differ- 
ent method.  'Ihey  agree  about  as  well  as 
we  could  expect  on  the  basis  of  necessarily 
rough  methods.  Some  of  the  maps  have 
been  made  by  relating  deafness  lor  j;ariicu- 
lar  tones  in  men,  never  a  very  precise  af- 
fair, with  postmortem  examination  of  the 
cochlea.  Other  maps  show  how  the  condi- 
tioned responses  of  guinea  pigs  are  upset 


Human 


E 


Guinea  pig 


FIGURE    164.      MAP   OF   BASILAR   MEMBRANE 


Narrow  poriion  of  nieinbrane  comes  at  base  of  cochlea.  The  maximum  response  to  1000  cycles  per  sec- 
ond comes  at  point  indicated  by  line  marked  1000.  Experimental  data  obtained  by  drilling  into  coch- 
lea of  guinea  pig.     [From  S.  S.  Stevens,  H.  Davis  and  M.  H.  Lurie,  /.  gen.  Psychol.,  1935,  13,  312.] 


the  unhurried  movement  through  the  hel- 
icotrema.  The  pressure  on  the  lower  part 
of  the  basilar  membrane  will  be  greater, 
the  meinbrane  will  be  more  distorted,  while 
at  a  given  point  short  of  the  upper  end, 
something  like  an  eddy  de\elops  and  be- 
yond this  point  little  movement  takes  place. 
The  cochlea  acting  in  this  manner  is  rep- 
resented in  B  of  Fig.  163.  If  the  to-and-fro 
movement  of  the  stirrup  is  still  more  rapid, 
the  bulge  of  the  basilar  membrane  will  be 
confined  to  a  very  small  area  near  the  stir- 
rup. 

It  is  one  thing  to  know  that  different  fre- 
quencies stimulate  one  part  of  the  cochlea 
or  another.  It  is  a  different  matter  to  have 
a  ):)recise  map  and  know  that  a  given  pitch 
is  licard  when  a  known  point  is  stimulated. 
Stub  maj^s  ha^■c  been  made  by  a  number  of 


by  drilling  holes  in  one  part  of  the  cochlea 
and  destroying  the  underlying  sense  cells. 
Still  other  experiments  make  use  of  an 
electrical  voltage  generated  when  the  hair 
cells  are  stimulated.  One  of  these  maps, 
of  the  guinea  pig's  ear,  is  shown  in  Fig. 
164  together  with  the  presumed  parallel  in 
the  human  ear.  One  interesting  compari- 
son appears.  If  the  pitch  scale  of  Fig.  152. 
page  323,  which  shows  how  pitch  is  related 
to  frequency,  is  compared  with  this  map  of 
the  cochlea,  it  turns  out  that  pitch  is  pro- 
portional to  distances  along  the  basilar 
7nembrane. 

The  explanation  of  how  the  ear  distin- 
guishes pitch  may  be  summed  up  in  diree 
points.  First,  while  a  large  part  of  the 
basilar  membrane  may  be  deflected  by  any 
given  sound  wave,   there  is  a  point  along 


336 


Hearing 


the  membrane  where  the  deflection  is  max- 
imum for  a  tone  of  a  gi\en  frequency. 
Second,  this  maximum  is  near  the  base  of 
the  cochlea  for  liigh  frequencies  and  is 
progressi\eh  farther  from  the  stirrup  and 
round  Avindo^v  for  louver  frequencies. 
Third,  the  size  of  the  area  involved  on 
either  side  of  the  maximum  is  probably 
proportional  to  the  intensity  of  the  sound 
wave,  thus  providing  the  additional  factor 
needed  to  explain  loudness  and,  at  the 
same  time,  accounting  for  the  facts  of 
masking. 

One  important  fact  has  been  neglected 
in  the  account  given  above,  the  fact  that 
nerve  impulses  are  synchronized  with  the 
sound  waves.  "When  the  impulses  from  the 
auditory  nerve  are  picked  up  by  a  suitable 
device,  they  are  found  to  reproduce  jare- 
cisely  the  frequency  of  the  sound  wave  up 
to  at  least  2000  cycles  per  second.  So  exact 
is  this  synchronization  that  many  sounds, 
even  the  human  voice,  can  be  recognized  if 
the  impulses  are  amplified  and  led  to  a 
loudspeaker. 

Just  what  use  the  auditory  centers  in  the 
brain  make  of  these  paced  impulses  is  not 
fully  known.  They  are  certainly  most  im- 
portant for  the  localization  of  sounds. 
They  may  contribute  to  the  perception  of 
rough  and  intermittent  soimds.  Further- 
more, if  the  ear  itself  is  not  able  to  respond 
difFerentiallv  to  the  very  low  frequencies, 
this  mechanism  could  concei\ably  preserve 
the  low  frequencies  and  pass  them  on  to 
some  as  yet  undiscovered  analyzer  in  the 
brain. 

The  means  by  which  the  auditory  nerve 
can  transmit  a  frequency  as  high  as  2000 
cycles  per  second  when  an  individual  fiber 
cannot  respond  more  than  500  to  800  times 
a  second  is  explained  by  the  voUey  prin- 
ciple, in  accordance  w-ith  whicii  all  the 
available  fibers  arc  thought  of  as  divided 


up  into  scjuads  with  each  of  the  various 
squads  firing  in  rotation.  One  squad  of 
fibers  fires  on  the  first  sound  wa\e,  an- 
other squad  on  the  second,  still  another  on 
the  third,  and  then  the  first  squad  returns 
to  fire  again  on  the  fourth  or  fifth  wave. 
Many  facts  have  been  discovered  which 
prove  the  correctness  of  the  \  oUey  principle. 

LOCALIZATION    OF    SOUNDS 

Sounds  are  not  onl)  heard;  they  arc 
heard  coming  from  some  place  out  in 
space.  The  space  in  which  we  hear  things 
is  the  space  in  which  we  see  things;  having 
heard  a  sound  we  look  at  some  point  to 
see  what  made  it.  It  is  also  the  space  that 
we  know  through  touch  and  movement.  It 
is  the  space  in  which  we  mo\e  around  and 
act. 

In  one  sense,  therefore,  there  is  no  audi- 
tory space  or  Aisual  space;  there  is  a  single 
perceived  space  about  which  we  know 
through  the  joint  and  supplementary  ac- 
tions of  several  senses.  Only  a  person  who 
has  been  blind  since  birth  would  have  an 
auditory  space,  uncontaminated  by  visual 
factors,  but  that  is  not  the  space  that  we 
wish  to  study.  \Ve  are  interested  in  nor- 
mal space,  everybody's  space.  The  ques- 
tion is:  How  do  we  locate  sounds  in  this 
space,  what  clues  do  we  use,  and  what  dis- 
criminations can  we  make? 

Imagine  that  an  experiment  is  performed 
Avith  a  person  suspended  somewhere  in  free 
space  as  suggested  by  the  diagram  of  Fig. 
165,  so  that  sounds  might  come  from  any 
side  of  him.  What  will  he  be  able  to  do 
with  his  ears? 

First,  he  will  almost  never  confuse  any 
sound  on  the  right  with  one  on  the  left. 
He  mav  sometimes  report  a  sound  located 
behind  him  when  it  is  in  front  or  oAcrhead, 
or  he  will  hear  a  sound  to  the  right  in  front 


Localization  of  Sounds 


337 


when  it  is  actually  to  the  right  behind,  but 
never  will  he  confuse  right  with  left. 

Second,  if  his  confusions  are  examined, 
it  is  found  that  both  the  actual  and  ap- 
parent positions  lie  at  a  constant  angle 
from  the  median  plane  (I lie  up-down-front- 
back  plane,  F-U-B-D,  which  separates  his 


FIGURE    165.       LOCALIZATION    OF   SOUND 

The  circles  indicate  possible  positions  of  the 
sound  source  in  the  three  principal  planes  oE  the 
head.  Note  especially  the  cone  at  one  side.  Any 
position  on  its  surface  may  be  confused  with  any 
other  position  on  its  surface. 

right  half  from  his  left  half)  or,  equally 
well,  at  a  constant  angle  to  his  aural  axis 
(the  line,  R-L,  passing  through  his  head 
from  the  right  to  the  left  ear).  Thus,  we 
may  confuse  front,  back,  up,  down,  up- 
front, up-back,  etc.,  all  of  which  lie  in  the 
median  plane.  We  may  confuse  45  de- 
grees from  the  front  toward  the  left,  shown 
as  Z,  with  45  degrees  from  directly  overhead 
toward  the  left  in  the  vertical  plane,  shown 
as  Y.  The  locus  of  a  set  of  directions, 
Avliich  arc  confused  with  one  another,  is  a 


double  cone,  formed  about  the  aural  axis 
with  its  apex  at  the  very  center  of  the  head. 

'i'hird,  if  a  sound  stimulus  is  moved  by 
a  small  amount,  or  given  in  two  positions 
in  close  succession,  the  finest  discrimination 
will  be  made  in  the  horizontal  plane  di- 
rectly in  front  of  the  listener,  near  the 
point  F,  and  discrimination  will  become 
progressively  poorer  as  the  test  is  made  in 
positions  farther  and  farther  to  the  side. 

All  these  findings  point  very  clearly  to 
one  conclusion,  that  localization  depends 
upon  the  relative  stinuilation  of  the  two 
ears,  that  is,  upon  binnuml  clues.  These 
arc  not  the  only  clues  for  the  localization 
of  sounds,  but  they  are  certainly  the  most 
important. 

Binaural  Clues 

The  binaural  clues  for  localization  may 
be  of  two  kinds.  Consider  for  a  moment 
Fig.  166.  Any  sound  from  a  point,  A.  in 
the  median  plane  of  the  head  will  lia\e 
reached  the  two  ears  by  paths  equal  in  ail 
respects.  On  the  other  hand,  a  sound 
coming  from  a  point  to  one  side,  such  as 
B,  will  travel  farther  to  reach  the  one  ear 
than  the  other.  The  ear,  of  course,  does 
not  know  how  far  the  wave  has  traveled, 
but  the  brain  may  be  able  to  recognize  the 
later  arrival  of  a  given  wave  at  the  far  ear. 
This  clue  is  called  time  difference.  At  the 
same  time,  the  nearer  ear  has  a  second  ad- 
vantage because  it  receives  tlie  sound  di- 
rectly, broadside,  whereas  the  far  ear  is  be- 
hind the  head  and  in  the  sound  shadow 
of  the  head.  The  two  ears  receive  differ- 
ent intensities  of  sound  on  this  account, 
and  we  speak  of  an  intensity  difference  as 
the  second  clue. 

Each  of  these  clues  should  be  examined 
somewhat  more  closely,  for  each  is  limited 
in  its  usefulness.  Time  differences  will  be 
produced    when    the    stinudus    is    a    shaip 


338 


Hearing 


click.  Nerve  impulses  will  be  set  ofl.  mark- 
ing the  arrival  of  the  click  at  each  car  and 
furnishing  the  auditoiy  brain  center  with 
an  adequate  clue.  The  sudden  starting  or 
stopping  of  a  tone  or  noise  provokes  an 
equally  reliable  neural   event. 


© 


I  IGURE   itifi.      CIXIKS  lOR  SOUND  LOCALIZATION 

SoiiikI  w;i\cs  coming  from  ./  in  mcdinn  ])lanc  af- 
fctl  both  ears  equally.  .Sound  liom  li  reaches  lell 
car  before  right  ear  and  is  more  intense  because 
right  car   is  slightly  'sliadowcil." 

Tones,  on  the  other  hand,  furnish  ade- 
quate time  clues  only  at  low  frequencies 
when  the  successive  nerve  impulses  are 
slow  enough  to  furnish  distinguishable  time 
intervals.  The  best  localization  is  of  tones 
500  to  700  cycles  per  second.  Very  low  fre- 
(jucncies  have  the  disadvantage  that  the 
\ollcy   scl    off  Ijy  one   wa\c   is   laggctl   antl 


scattered  in  starting,  dulling  the  sharpness 
of  localization.  As  the  frequency  becomes 
higher,  on  the  other  hand,  a  point  is 
reached  where  the  time  difference  between 
successive  soimd  wa\es  at  one  car  is  twice 
the  time  difference  beliveen  the  two  cars. 
At  this  point  the  ears  fire  alternately,  and 
neither  one  is  clearly  first  any  longer.  At 
this  and  higher  frequencies,  localization 
becomes  ambiguous  and  may  finally  break 
down  altogether.  This  difficulty  starts  for 
tones  of  about  800  cycles  per  second,  lo- 
cated 90  degrees  to  the  right  or  left.  There 
are  also  classes  of  sounds  for  which  there 
can  never  be  significant  time  differences, 
notably  tones  of  very  high  frequency  and 
continuous  noises. 

Sound  shadows  are  much  less  sharp  than 
the  shadows  cast  by  light.  We  hear  a  per- 
son who  faces  away  from  us  as  he  speaks, 
or  the  roar  of  surf  before  we  come  over 
the  crest  of  a  hill,  but  in  both  cases  we 
hear  them  less  well  than  Avhen  the  sound 
comes  in  direct  line.  Measurements  about 
the  head  show  that  only  the  very  high  fre- 
(juencies  can  be  substantially  shut  off  by  an 
object  of  the  head's  size— roughly  frecjuen- 
cies  above  3000  cycles  per  second.  Thus 
there  will  be  intensity  differences  for  high- 
frequency  tones  and  hisslikc  noises,  and 
also  for  the  high-frequency  components  of 
other,  more  complex  soiuuls. 

It  is  one  thing  to  know  what  clues  arc 
available;  it  is  another  to  know  that  they 
are  used.  The  brain  may  not  have 
'learned'  to  use  all  the  information  that 
ears  could  provide.  To  test  this  point,  ex- 
periments have  been  designed  in  which 
time  differences  or  intensity  differences 
have  been  created  synthetically.  If  soimd 
is  led  to  the  two  ears  by  means  of  tubes, 
for  instance,  time  differences  can  be  cre- 
a(cd    b\     i('iig(h('niug    and    slioitcning    tiic 


Localizafion  of  Sounds 


339 


tubes  with  a  trombone  slide,  and  intensity 
differences  by  p:irliaily  closing  oft  one  tube 
or  the  other.  Kleclrical  means  would  do 
the  same  thing  more  elegantly. 

In  such  experiments,  suilable  lime  and 
intensity  difterences  make  the  sound  appear 
on  one  side  or  the  other,  just  as  we  should 


FIGURE  167.      UNITKD  STATES  ARMY  SOUND  LOCATOR 

Tubes  are  led  fidiii  a  pair  of  Iioiiis  10  an  observ- 
er's ears.  One  observer  turns  band  wheel  control- 
ling tbe  horizontal  traverse;  the  other  ol)server  tills 
the  horns  in  vertical  elevation.  [Courtesy  of  U.  S. 
Army  Signal  Corps.] 

expect  from  theory.  On  the  other  hand, 
what  is  heard  is  quite  disappointing;  for 
usually  a  phantom  sound,  starting  at  one 
ear,  with  an  extreme  difference  in  tiine  or 
intensity,  moves  through  the  head  or  just 
back  of  the  head  to  the  other  ear.  Real, 
lively  localizations  far  away  from  the  lis- 
tener do  not  often  occur.  It  is  apparent 
that  each  of  these  two  factors,  time  and  in- 
tensity,   contributes    to    localization,    but 


neither  in  itself  gives  the  whole  answer  to 
the  problem. 

An  instance  of  the  use  of  a  single 
binaural  clue  is  the  sonnd  locator  used  by 
the  Army  for  the  location  of  airplanes. 
Figure  H)7  shows  a  model  perfected  in 
1938.  Using  pairs  of  horns  spaced  well 
apart,  the  listener  makes  use  of  time  clues 
to  turn  the  horns  until  tliey  point  toward 
the  sound.  Witii  lliis  setting  a  sound  image 
is  heard  located  at  tiie  middle  of  tlie  head. 
The  locator  is  moderately  successful  in  the 
hands  of  an  experienced  operator,  but  it 
suffers  from  the  same  difficuUies  as  the 
synthetic  experiments. 

Secondary  Clues 

Three  secondary  factors  are  present  in 
the  natural  activity  of  localization.  In  the 
first  place,  many  sounds  present  double 
clues,  both  time  and  intensity.  Thus  in 
the  soimd  of  the  voice  there  are  starts  and 
stops  and  low-frequency  tones  which  give 
plenty  of  time  clues,  and  tiiere  are  also 
many  high-frequency  components  which 
give  intensity  clues.  Unless  both  sets  of 
clues  tell  the  same  story,  fuzziness  and  con- 
fusion result. 

The  second,  and  somewhat  more  spec- 
tacular, factor  has  to  do  with  head  or  bodv 
movement.  Just  as  it  is  important  for  a 
stable  visual  world  that  the  shifting  of  the 
image  on  the  retina  should  correspond 
closely  with  the  movement  of  die  head  and 
eyes,  so  is  it  important  for  our  heard  space 
that  binaural  clues  change  strictly  in  pro- 
portion to  movements  of  the  Iiead.  It  is 
this  change  of  binaural  clues  with  move- 
ment that  gives  us  the  out-there-in-space 
quality  of  sound  localization.  If  the  head 
is  turned  to  the  right,  a  sound  drat  was  pre- 
viously straight  in  front  of  the  listener 
shifts  to  the  left  of  the  head's  axis.  Or  sup- 
pose that  a  sound  is  o^erhead  and  the  head 


340 


Hearing 


is  tilled  toward  the  right  shoulder.  Now 
the  sound  is  heard  to  the  head's  left.  In 
normal  life  we  are  continuously  moving 
our  heads  and  bodies  and  changing  the 
binaural  clues  reaching  oiu'  ears.  In  the 
synthetic  experiment,  where  the  clues  fail 
to  change  with  head  mo\'ements,  the  phan- 
tom sound  attaches  itself  to  the  head. 

The  third  factor,  which  plays  a  subtle 
and  changing  role,  is  the  effect  on  localiza- 
tion of  our  knowledge  of  sounds  and  our 
expectations  about  them.  Sounds  that  are 
weaker  than  usual  may  be  behind  rather 
than  in  front  of  us.  Sounds  heard  at  a  dis- 
tance lose  their  high-frequency  compo- 
nents,   becoming    moie    mellow.      Sounds 


from  another  room  or  the  other  end  of  a 
large  hall  tend  to  roll  as  the  echoes  rein- 
force the  original  soiuid.  Heard  once,  a 
sound  may  not  be  well  localized;  Ireard  a 
dozen  times,  the  listener  will  'expect'  a  par- 
ticular intensity,  quality,  degree  of  rever- 
beration. As  it  departs  from  this  expecta- 
tion he  hears  the  sound  in  a  new  place  in 
space. 

In  conclusion,  we  may  note  again  that 
our  ears  are  not  provided  with  a  space  of 
their  own.  They  provide  additional  in- 
formation about  the  same  objects  which  we 
see  with  our  eyes  and  touch  with  our  hands. 
Usually  ears  tell  about  the  direction  in 
which  something  is  happening,  doing  it  so 


-20 

-10 

0 

10 

20 

30 

jn 

^40 

'o 

■^50 
§60 
70 
80 
90 
100 
110 
120 


^ 

-^^ 

^ 

\ 

®' 

^ 

\/ 

r^ 

\ 

V 

®\ 

V 

N 

r^^ 

\      1 

^-.^ 

A 

J 

1 
1 

\  ©\ 

J 

kn 

1 
1 

■" 

\ 

\ 
\ 

•"Si 

r^^ 

1 
1 

1 

\ 

1 
/ 

1 

\ 

/ 

/ 

Total  loss  ^\ 
of  hearing      ^, 

/ 
/ 

N 

■^ 

/ 

125 


250 


500 


1000 
Frequency 


2000 


4000 


8000    16,000 


FIGURE    l68.      TYPICAL   AUDIOGRAMS 


Normal  is  the  line  at  zero  level  near  tlie  top.  Complete  loss  of  hearing  is  shown  by  the  dashed  line  near 
the  bottom.  (A)  Typical  normal  ear.  (B)  Sloping  loss,  maximal  in  high  frequencies.  (C)  Flat  loss  Avith 
all  frequencies  cut  down  nearly  the  same.     (See  also  Fig.  169.) 


Deafness 


341 


(|iii(kly  tluil  tlu'  cvcnl  is  idciitificcl  iinfl  <on- 
(irmed  by  the  eye  hclorc  wc  (;m  discnianglc 
the  conlribution  of  ca(h  of  tlic  senses. 

DEAFNESS 

Normal  hearinj^,  like  normal  inlelligeiKc, 
is  something  wiiieh  exists  only  in  tiie  aver- 
ages of  the  statistic  ian.  All  ears  differ 
more  or  less  from  the  average  ear.  Unlike 
intelligence,  however,  the  ability  to  hear 
usually  starts  out  quite  near  'normal'  in 
small  children  and  declines  through  the 
natural  processes  of  aging  or,  sometimes, 
through  accident  or  disease. 

A  relatively  small  number  of  children  are 


born  deaf,  perhajjs  ouc  in  six  tiir,iis;nid. 
I  hey  are  also  nuites,  that  is,  without 
speech,  because  without  hearing  they  do 
not  have  the  natural  means  of  learning  to 
speak  words.  A  somewhat  larger  group  ol 
jKople  lose  their  hearing  entirely,  often  as 
a  result  of  infection  or  the  toxic  effects  of 
disease,  less  often  through  degeneration 
of  the  inner  ear  because  of  an  obscure 
hereditary  defect. 

With  no  hearing  the  totally  deaf  j^erson 
has  to  rely  on  visual  cjr  tactual  means  ol 
communication.  The  easiest  to  learn  is  a 
sign  language  which  is  an  elaborate  system 
of  manual  gestures  and  finger  spelling  in- 
vented for  the  deaf.     Better  schools  for  the 


-20 

-10 

0 

10 

20 

30 

I  40 

■°  50 
c 

I  60 

70 

80 

90 
100 
110 

120 

125  250  500  1000  2000  4000  8000         16,000 

Frequency 

FIGURE    l6l).      TYPICAL  AUDIOGRAMS 

(D)  High  frequency  loss,  with  sudden  drop  between  1000  and  2000  cycles  per  second,  frequently  asso 
ciated  with  exposure  to  damaging  explosion.  (£)  High  frequency  loss  with  prominent  'notch."  (F)  Ris 
ing  curve  with  greater  loss  in  low  frequencies.     (See  also  Fig.   168.) 


(E)i 

®\ 

^ 

\ 

N 

1 
I 

/ 

\r4 

r 

A 

A/ 

J 

I    N 

A/ 

\      ® 

V 

y 

1 

\ 
\ 

N 

/ 

1 
1 

\ 

1 

\ 

\ 
\ 

/ 

Total  loss  ^\ 
of  hearing      ^, 

^ 

y 

342 


Hearing 


deaf,  however,  insist  on  speech  and  lip- 
reading,  more  difficult  skills  to  accjuirc,  but 
skills  that  permit  a  far  more  normal  ad- 
justment of  the  deaf  to  ordinary  life.  The 
speech  of  persons  who  are  totally  deaf  is 
generally  intelligible,  but  it  has  a  charac- 
teristic monotone  quality  and  other  pecul- 
iarities that  are  due  to  the  lack  of  auditory 
control. 

A  far  larger  group  than  ihc  totally  deaf 
may  be  described  as  hard-of-hearing.  Per- 
sons in  this  group  have  a  measure  of  hear- 
ing, but  their  sensitivity  is  to  a  greater  or 
less  degree  below  normal.  These  are  the 
people  who  may  benefit  from  medical  care 
or  from  the  use  of  well-designed  hearing 
aids.  One  in  four  over  sixty-fi\e  years  old 
falls  into  this  group. 

Loss  of  sensitivity  for  the  hard-of-hearing 
is  commonly  shown  by  an  audiogram,  of 
which  samples  are  shown  in  Figs.  168  and 
169.  This  chart,  which  looks  much  like  the 
curve  of  auditory  sensitivity  shown  in  Fig. 
154,  page  324,  is  actually  an  upside-down 
plot  of  the  same  function.  'Normal'  hearing 
is  rcjjrcscnted  by  a  straight  line  near  the  top 
of  the  audiogram.  A  person  who  can  just 
hear  the  tone  heard  by  the  average  listener 
is  represented  by  points  along  the  normal 
line.  The  curve  A  in  Fig.  168  shows  a  typ- 
ical audiogram  with  the  ups  and  downs  of 
a  normal  ear.  Losses  of  sensitivity  are  then 
shown  below  this  line  in  terms  of  the  num- 
ber of  decibels  bv  which  a  tone  nnist  be  in- 
creased abo\c  the  normal  level  in  order  to 
be  heard. 

Abnormal  audiograms  are  giouped  into 
three  or  four  loosely  defined  classes.  Curve 
C  illustrates,  for  instance,  a  broad,  'flat' 
loss  in  which  all  frequencies  are  equally 
difficult  to  hear.  Another  common  picture 
is  shown  in  B  Avhere  the  loss  gradually  gets 
worse  as  frequencies  from  low  to  high  are 
tested. 


Not  all  audiograms  are  as  smooth  as 
these.  Often  there  is  a  sudden  drop  in  the 
audiogiam,  as  shown  in  D  of  Fig.  169. 
This  type  of  loss  is  common  among  soldiers 
Avhose  ears  have  been  injured  by  very  close 
explosions.  Some  ears  develop  such  losses 
Avithout  injiny,  as  illustrated  in  E  of  Fig. 
169.  The  loss  often  starts  near  4()()()  cycles 
per  second  as  a  notch  which  widens  and 
deepens.  This  notch  was  once  called  the 
"boilermakers'  notch"  because  it  was  be- 
lie\ed  to  be  caused  by  the  unusual  noise  of 
their  work.  Actually  it  can  be  foiuid  in 
any  large  group  of  people.  The  rarest 
type  of  audiogram  is  one  shown  as  F  in 
Fig.  169;  it  is  down  most  at  low  frequencies 
and  gradually  rises  toward  the  high  end. 

The  cause  of  the  deafness  may  be  located 
in  either  the  middle  ear  or  the  inner  ear. 
If,  for  instance,  scar  tissue  has  grown  over 
the  eardrum,  as  a  result  of  long-continued 
infection  of  the  middle  ear,  or  if  the  joints 
between  the  ossicles  become  fixed  through 
otosclerosis,  the  residting  deafness  we  call 
conduction  deafness.  Sound  is  blocked  be- 
fore it  reaches  the  inner  ear,  and  the  audio 
gram  shows  a  large  loss  at  all  frequencies. 
On  the  other  hand,  if  some  acute  infection, 
such  as  comes  with  scarlet  fever  or  menin- 
gitis, strikes  at  the  inner  ear,  the  hair  cells 
and  the  connecting  nerve  fibers  may  be  de- 
stroyed over  some  part  of  the  basilar  mem- 
brane. The  result  is  a  'perceptive,'  or  ijct- 
ter,  a  nerve  deafness.  Particular  frecjucncies 
are  no  longer  heard.  The  resulting  audio- 
gram may  shoAV  a  sharp  dip,  most  often  at 
high  frequencies  but  sometimes  at  the 
lower  end  or  in  the  middle. 

When  a  person  has  pure  conduction 
deafness,  sound  can  still  be  transmitted  to 
the  intact  cochlea  by  means  of  bone  con- 
duction. The  sound  wa\es  pass  readily 
through  the  bones  of  the  head  and  by  com- 
pressing the  walls  of  the  labyrinth  set  the 


^^^^^B^  ^Kl-'H 

Batteries  TivJ 

m^ 

H^  jyi iin '  f 

^*<--*^ 

y 

^ 

^ 

^     Ear  mold- 

\lt. 

^ 

i^^MtSt!"™*.™ 

k.  ^ 

^^ 

""•-^^^^SHS 

^am 

^N^ 

V 

■Volume  control  Volume  control- 

r^ Tone  control  — — *n 


Microphone 


Vacuum  tubes 


FICl'RK     170.       MODERN     ELECTRONIC    HEARING    AID 
343 


344 


Hearing 


fluids  of  the  cochlea  in  motion.  Anyone 
can  hear  bone-conducted  sound  by  touch- 
ing a  vibrating  tuning-tork  to  his  teeth. 

Tremendous  improvements  in  the  design 
of  hearing  aids  have  been  made  recently 
through  the  use  of  tiny  vacuum  tubes, 
shown  in  Fig.  170.  Unfortunately  these 
devices  are  still  not  so  common  as  glasses, 
and  too  many  people  struggle  along  with 
an  unnecessary  handicap.  The  choice  of 
a  suitable  hearing  aid  depends  largely 
on  the  degree  of  hearing  loss.  Moder- 
ate losses  are  helped  by  almost  any  good 
aid.  Purely  conductive  deafness  can  be 
overcome  by  the  use  of  a  bone  conduction 
receiver  which  rests  on  the  mastoid  bone 
just  back  of  the  ear.  Other  forms  of  deaf- 
ness merely  require  great  enough  amplifi- 
cation. To  be  sure,  there  must  be  wide- 
range,  high-fidelity  amplification,  which  it 
is  not  always  easy  to  attain.  Elaborate 
'fitting,'  widely  advertised  by  some  manu- 
facturers, has  recently  been  shown  to  be 
cjuite  unnecessary  provided  high-fidelity 
liearing  aids  are  available. 

MUSIC 

Soimds  are  not  only  useful.  Combined 
and  arranged  to  form  music,  they  also  af- 
ford us  never-ending  pleasure  and  relaxa- 
tion. A  few  sounds  are  probably  moder- 
ately pleasant  by  themselves,  such  as  the 
tones  of  a  fine  violin  or  a  rich  and  well- 
trained  voice.  But  our  real  enjoyment  of 
music  springs  from  the  movement,  and 
color,  and  pattern  of  tones  in  combination. 

Music  starts,  of  course,  with  the  basic 
discrimination  of  pitch  and  loudness,  but 
it  depends  also  on  the  more  complex  ap- 
preciation of  rhythm,  melody  and  har- 
mony. 

Rhythm  is  perhaps  the  oldest  and  most 
primitive    feature   of   music.      A   series   of 


sounds,  in  which  some  are  accented,  may 
form  quite  an  intricate  temporal  pattern. 
In  oiu"  music  two,  three  or  four  beats  are 
combined  to  form  a  unit  or  measure,  which 
is  then  repeated.  Each  beat  may  be  fur- 
ther subdivided  or  'figured.'  The  prin- 
ciples governing  the  combination  of  sounds 
in  a  rhythm  are  not  unlike  the  principles 
of  grouping  in  vision  (p.  222).  For  in- 
stance, two  sounds  close  together  in  time 
form  a  strong  'pair.'  A  tempo  has  unique 
and  compelling  character  as  it  is  fast  or 
slow.  Rhythms  distorted  by  syncopation 
have  qualities  distinct  from  rhythms  with 
more  even  spacing. 

Melody  lies  in  the  movement  of  a  voice 
or  instrument  up  and  down  the  scale  of 
pitch.  The  melodic  line  of  a  piece  of  mu- 
sic normally  follows  and  adds  to  the  under- 
lying rhythmic  pattern.  But  it  is  much 
more.  In  melodic  patterns  is  found  the 
richest  source  of  feeling  and  expression  in 
music. 

Many  elements  of  modern  melody  are 
highly  stylized.  We  might  use  a  scale 
consisting  of  five  notes,  or  twelve,  or  per- 
haps twenty-four.  Actually,  in  our  cul- 
ture, convention  has  chosen  a  scale  with 
seven  notes  to  an  octave.  A  melody  most 
often  starts  out  with  a  note  which  estab- 
lishes the  tonality,  that  is  to  say,  the  key  in 
which  the  melody  is  to  be  sung  or  played, 
and  ends  with  a  series  of  notes  called  a 
cadence  which  comes  back  to  the  keynote 
by  a  progression  which  provides  'resolu- 
tion.' 

The  existence  of  these  formal  rides 
should  not  be  stressed  too  much,  however. 
Psychologically,  a  melody  probably  con- 
sists of  a  series  of  jumps  or  steps,  some  up, 
some  down,  some  big,  some  small,  some 
held  for  emphasis,  others  passed  over 
lightly.  Naive  singers  preserve  carefidly 
the  direction  and  approximate  size  of  these 


Music 


345 


steps  while  they  play  havoc  with  the  strict 
tonality  of  a  melody.  Moreover,  melodies 
may  easily  be  transposed  not  only  by  mov- 
ing them  up  and  down  the  scale  but  by 
cutting  down  all  the  intervals,  producing 
'micromelodies,'  without  upsetting  the 
clear  recognition  of  the  original   pattern. 

Rhythm  and  melody  are  as  old  as  music 
itself.  Harmony  is  a  relative  newcomer. 
Harmony  arises  when  two  or  more  notes 
are  sounded  together.  Certain  combina- 
tions sound  smooth  and  fused;  others  are 
harsh  and  rough.  Combinations  may  also 
be  rated  rich  or  thin,  sweet  or  discordant, 
or  some  nuance  in  between. 

The  element  of  harmony  is  the  interval, 
a  combination  of  two  tones.  Intervals  are 
named  by  the  number  of  notes  on  our  scale 
which  they  include,  such  as  the  second  for 
do-re,  or  fa-sol;  the  third  for  do-mi,  or  mi- 
sol;  the  fourth  for  do-fa,  etc.  The  major 
intervals  contain  one  more  half  tone  than 
the  corresponding  minor  intervals.  For 
instance,  do-mi  is  a  major  third,  with  two 
full  tones,  whereas  mi-sol  is  a  minor  third 
with  one  full  tone  and  one  half  tone. 

Classical  musical  theory  once  ranked  the 
intervals  for  their  degree  of  fusion  or  con- 
sonance and  gave  a  simple  explanation  of 
this  order.  The  list,  in  order,  together  with 
the  ratio  of  the  two  frequencies  making  up 
the  interval,  was  as  follows. 


Interval 

Ratio 

Octave 

1:2 

Fifth 

2:3 

Fourth 

3:4 

Major  third 

4:5 

Minor  sixth 

5:8 

Minor  third 

5:6 

Major  sixth 

3:5 

Major  second 

8:9 

The  explanation  given  was  based  upon 
the  small  whole  numbers  which  make  up 
the  preferred  ratios;  but  such  a  theory  can 


hardly  be  correct  when  we  consider  how 
an  instrument  is  actually  tuned  off  of  these 
simple  ratios  to  fit  our  arbitrary  scale  of 
equal  temperament  or  when  we  discover 
how  inexact  is  even  a  skilled  musician 
when  producing  an  interval. 

Actual  harmony  is  perhaps  better  illus- 
trated by  chords,  combinations  of  three  or 
more  notes  which  form  a  set  of  consonant 
intervals.  The  major  chord  (like  c-e-g-c"^^, 
for  instance,  consists  of  four  notes  whose 
frequencies  stand  in  the  ratios  of  4:5:6:8. 
If  you  compare  this  chord  with  the  table 
above,  you  will  see  that  it  contains  the  oc- 
tave, fifth,  fourth,  major  third,  minor 
third  and  minor  sixth. 

A  good  explanation  of  consonance  has 
not  yet  been  given,  but  it  will  probably 
include  some  of  the  following  factors:  (1) 
the  absence  of  disturbing  roughness  pro- 
duced by  beats  lying  in  the  range  of  5  to  20 
per  second;  (2)  richness  which  arises  when 
the  notes  in  a  chord  are  as  close  together  as 
possible;  (3)  clear  tonality,  depending  on 
the  position  of  the  tonic  note  in  the  chord; 
and  (4)  balance  or  proportion  among  the 
various  notes. 

Music  is  too  rich  a  subject  to  be  treated 
adequately  here.  It  is  also  an  elusi\e 
thing.  Like  other  art,  its  perfection  doubt- 
less lies  in  a  nice  balance  between  sim- 
plicity and  variety,  between  expected  form 
and  novelty.  At  its  more  elementary  levels 
it  has  universal  appeal,  but  fully  developed 
it  is  appreciated  by  only  the  most  sophisti- 
cated ear. 

COMMUNICATION 

We  noted  at  the  start  of  this  chapter 
that  men  can  live  most  easily  together  in  a 
social  gioup  when  they  hear  each  other. 
Communication  is  as  vital  to  a  society  as 
nerx'ous  activity  is  to  an  organism.     It   is 


346 


Hearing 


the  process  by  which  an  aggregation  of  men 
is  changed  into  a  functioning  group. 
Moreover,  the  basic  mode  of  communica- 
tion is  speech.  Every  normal  man  speaks, 
though  only  the  more  enlightened  read  and 
■\vrite. 

The  ready  comprehension  of  spoken  lan- 
guage is  a  truly  remarkable  feat.  It  re- 
quires the  finest  discrimination.  A  well- 
educated  person  will  understand  by  ear 
alone  perhaps  ten  thousand  spoken  words, 
each  consisting  of  a  short  pattern  of  sound 
lasting  less  than  one  second.  Furthermore, 
each  of  these  words  is  a  sturdy  thing  which 
keeps  its  identity  in  the  face  of  marked 
changes.  A  word  is  understood  when 
spoken  by  men  or  women  or  by  people 
with  the  most  varied  accents  and  voice 
qualities.  Even  more  remarkable  are  the 
distortions  which  speech  undergoes  in  trans- 
mission over  a  radio  or  telephone  circuit. 
Almost  every  conceivable  characteristic  of 
speech  may  be  changed  in  some  degree, 
and  yet  a  large  measure  of  intelligibility 
will  remain.  Finally,  the  ear  is  able  to 
distinguish  words  and  some  measure  of 
sense  when  presented  against  a  background 
of  several  voices  or  of  a  steady  noise.  The 
sensory  and  perceptual  achievement  in- 
\olved  is  almost  without  parallel  elsewhere 
in  man's  experience. 

Speech  Sounds 

The  range  of  sound  employed  in  under- 
standing speech  is  limited  not  by  the  abil- 
ity of  the  ear  to  hear  but  rather  by  the 
mechanics  of  the  mouth  and  throat  which 
produce  the  sounds.  The  lowest  frequency 
to  be  found  in  speech  is  the  fundamental 
of  the  vocal  cords,  about  125  cycles  per  sec- 
ond for  men  and  250  cycles  per  second  for 
women.  The  highest  useful  frequencies 
are  near  5000  cycles  per  second,  just  a  bit 
more  than   five  octaves  higher.     Thus   the 


sounds  of  speech  occupy  just  under  a  quar- 
ter of  the  total  range  of  frequencies  which 
can  be  heard  at  all. 

The  range  of  intensities  is  also  relatively 
narrow.  Between  the  softest  sound  and 
the  loudest  in  any  single  sample  of  speech, 
there  will  be  a  range  of  only  about  30 
decibels.  There  will  be  a  difference  of 
perhaps  an  additional  40  decibels  between 
a  whisper  and  a  shout,  making  a  total  of 
70  decibels  between  the  softest  and  loudest 
sounds  in  the  human  voice.  But  the  whis- 
per is  still  well  above  the  softest  sound 
that  can  be  heard,  and  the  shout  well  short 
of  the  loudest  noise  to  be  tolerated. 

Many  engineering  calculations  can  be 
based  on  such  facts  about  the  overall  prop- 
erties of  speech;  but  for  a  better  under- 
standing of  how  we  make  the  many  fine 
discriminations  among  words,  we  need  to 
consider  not  the  total  spoken  but  rather 
the  individual  sounds  out  of  which  a  lan- 
guage is  built  up. 

Speech  sounds,  as  we  all  know,  can  be 
divided  first  of  all  into  vowels  and  con- 
sonants. Vowels  are  voiced  sounds  pro- 
duced by  the  vocal  cords  with  the  help  of 
the  resonance  of  cavities  in  the  throat  and 
open  mouth.  Consonants,  on  the  other 
hand,  are  those  sounds  which  we  make  with 
some  constriction  of  the  passage  through 
the  throat  and  mouth.  Roughly,  the 
vowels  are  tones,  and  the  consonants,  noise. 

The  consonants  can  be  divided  in  turn 
into  voiced  consonants,  such  as  t,  g  or  z, 
and  unvoiced  consonants  of  which  t,  s  or 
/  are  examples.  Or  they  may  equally  well 
be  divided  into  the  stops  or  plosive  sounds, 
p,  b,  t,  d,  k,  g,  as  opposed  to  the  aspirate 
or  fricative  sounds,  h,  ch,  s,  z,  j,  v.  A 
number  of  sounds  which  fall  in  between 
the  clearly  recognized  vowels  and  conso- 
nants are  called  semivowels,  sounds  like  ?/', 
T,  /,  r,  tn  and  n.    For  the  final  classification. 


Speech  Sounds 


347 


the  expert  in  phonetics  points  to  the  part 
of  the  mouth  which  is  used.  He  speaks 
of  dentals  and  labials,  of  front  and  back 
vowels.  These  distinctions,  although  real, 
are  difficult  for  the  layman  to  master. 

A  classification  like  this  calls  attention  to 
several  problems.  For  one  thing  our  alpha- 
bet is  fundamentally  phonetic,  and  our 
spelling  is  supposed  to  reflect  our  speech. 
Written  language  does  more,  of  course, 
than  simply  reflect  speech  sounds.  The 
best  written  language  would  not  necessarily 
be  the  one  which  gave  the  most  accurate 
phonetic  transcription.  There  is  little 
doubt,  however,  that  written  English  could 
be  improved  in  its  phonetic  representation 
without  losing  its  other  usefulness. 

Dividing  speech  sounds  into  these  classes 
also  helps  to  predict  what  sounds  will  be 
heard  when  listening  is  difficult.  Vowels 
are  by  their  very  nature  much  louder  than 
consonants,  and,  in  turn,  some  consonants 
are  much  louder  than  others.  Further- 
more, the  energy  in  a  vowel  sound  is  al- 
most entirely  in  the  frequencies  below 
2000  cycles  per  second  whereas  the  charac- 
teristic components  of  a  th  or  /  lie  above 
3000  cycles  per  second.  These  facts  are 
important  in  the  design  of  telephone  and 
radio  circuits,  for  great  care  must  be  taken 
to  preserve  the  weak  consonants  in  the 
high  range  of  frequencies. 

Finally,  a  knowledge  of  speech  sounds 
helps  the  teacher  or  speech  pathologist  to 
identify  and  correct  wrong  speech  habits. 

Sound  Pattern  in  Speech 

In  order  for  the  ear  to  distinguish  the 
various  vowels  and  consonants  of  speech, 
there  must  be  differences  among  them 
which  can  be  described  in  the  more  pre- 
cise terms  of  the  physical  sound  wave.  A 
good  account  of  these  differences  turns 
out,  however,  to  be  quite  complex.     Some 


of  the  sounds,  such  as  g  and  t  tor  instance, 
are  really  not  unique  sounds  at  ail  but 
are  mostly  ways  of  starting  or  stopping 
other  sounds.  None  of  the  speech  sounds 
consists  of  a  simple  pure  tone.  A  few  turn 
out  to  have  a  concentration  of  sound  energy 
in  a  limited  band  of  frequencies.  These 
are  sounds  like  m  at  the  low  end  of  the 
low  end  of  the  scale  and  s,  sh  and  /  at  the 
high  end.  Most  of  the  remaining  speech 
sounds  represent  some  complex  pattern  of 
frequencies. 

In  this  connection  vowels  present  per- 
haps the  most  interesting  problem.  How 
is  it  that  they  have  a  quality  so  much  like 
a  pitch  {oo  in  boot  seems  low;  ee  in  beet 
seems  high)  and  yet  they  are  not  pitch 
alone,  for  the  speaker's  voice  has  its  own 
pitch,  separate  from  the  vowel  being 
spoken?  The  answer  can  be  found  by  anal- 
ysis of  the  vowel  sound.  The  vowel  is 
found  to  be  a  sound  very  rich  in  har- 
monics. Thus  the  fundamental  frequency 
of  a  man's  voice  lies  near  125  cycles  per 
second,  but  various  vowels,  spoken  at  this 
pitch,  will  contain  harmonics  with  fre- 
quencies all  the  way  up  to  2500  cycles 
per  second.  Furthermore,  the  distinguish- 
ing characteristic  of  each  vowel  is  found 
to  be  the  presence  of  harmonics  in  a  par- 
ticular frequency  range.  These  character- 
istic regions  are  shown  in  Fig.  171.  Some 
vowels,  those  in  the  upper  part  of  tlie  dia- 
gram, may  have  only  a  single  region  em- 
phasized. Others,  like  e  and  ;,  always 
exhibit  two  regions  of  resonance. 

The  source  of  these  characteristic  pat- 
terns is  to  be  found  in  the  resonant  cavi- 
ties of  the  throat  and  mouth.  In  the  first 
instances  the  entire  mouth  acts  as  a  reso- 
nator to  emphasize  a  single  band  of  fre- 
quencies; in  the  latter  instances,  the  back 
of  the  mouth  and  throat  are  cut  off  from 
the  front  of  the  mouth  bv  the  tongue  and 


348 


Hearing 


palate,  forming  two  distinct  cavities.  Re- 
cently a  machine  has  been  invented  which 
presents  the  characteristic  regions  of  reso- 
nance as  bars  of  light.  A  well-trained 
person  can  recognize  at  once  in  this  'visible 
speech'  what  vowel  or  consonant  is  being 
spoken  and  in  this  manner  may  listen  with 
his  eye  to  continuous  speech. 


u  (Pool) 

r- 

,,,,,       , 

' 

u  (Put) 

1 

0 (Tone) 

1      'J 

a  (Talk) 

1     1 

0 (Ton) 

1 

a  (Father) 

1 

1 

a (Tap) 

1 

e  (Ten) 

. 

1 

a  (Tape) 

1 

i  (Tip) 

1 

1 

e  (Team) 

1 

1     1     r    1    1 

1 

1 

200 


400  1000  2000 

Frequency  in  cycles  per  second 


4000 


FIGURE    171.      RESONANT   FREQUENCIES    OF    VOWELS 

Bars  indicate  regions  in  which  strong  harmonics 
are  found  when  given  vowels  are  spoken.  Note 
especially  wide  separation  of  bars  in  lower  part  of 
figure.  [From  data  of  H.  Fletcher,  Speech  and 
hearing,  Van  Nostrand,  1929,  p.  58.1 

The  analysis  of  speech  into  sound  ele- 
ments is  artificial  in  one  important  respect. 
The  unit  of  speaking  is  really  the  syllable. 
The  chest  and  diaphragm  control  the  puff 
of  air  that  forms  the  syllable  unit.  Within 
the  syllable  the  rise  and  fall  of  sound,  and 
its  duration  and  relative  stress,  are  fully 
as  important  as  the  exact  quality  of  the 
vowel  or  consonant.  This  is  evident  when 
the  actual  vowels  or  consonants  in  speech 
are  changed  but  the  pattern  is  kept  the 
same.  Try  reading  aloud,  for  instance, 
this  paragraph  using  one  vowel  through- 
out. See  if  most  of  the  words  are  not  un- 
derstandable.     (See    eef    meest    eef    thee 


weerds  eere  neet  eendeersteendeeble.)  Syl- 
lables are  so  important,  in  fact,  that  they 
are  sometimes  used  as  the  phonetic  unit, 
as  in  written  Japanese. 

Perception   and  Speech 

The  recognition  of  a  pattern  of  har- 
monics as  a  vowel,  or  of  a  sequence  of 
sounds  as  a  word  or  syllable,  requires  the 
operation  of  mechanisms  in  the  brain  as 
well  as  in  the  ear.  In  contrast  with  the 
analytical  functions  of  the  ear,  we  are  deal- 
ing here  properly  with  auditory  perception. 
The  hearing  of  a  word  is  much  like  the 
seeing  of  an  object.  Sound  waves  reaching 
the  ear  are  broken  up  in  the  sense  that 
they  set  off  impulses  in  different  parts  of 
the  ear.  The  excitation  of  each  part  is 
transmitted  to  some  higher  center  where 
it  is  put  together  and  interpreted.  Just 
as  in  vision  a  person  can  see  a  hidden  face 
in  a  puzzle  picture  (Fig.  78,  p.  220),  so  also 
in  hearing  the  fragments  of  a  word  or 
phrase  are  fitted  together  to  form  under- 
standable speech. 

The  precise  manner  in  which  this  in- 
tegration is  accomplished  is  something  of 
a  mystery.  We  shall  have  to  be  content 
here  with  the  demonstration  of  how  im- 
portant auditory  perception  is  rather  than 
with  its  explanation.  As  with  many  abili- 
ties, the  hearing  and  understanding  of 
words  are  most  evident  when  it  is  absent. 
Brain  injuries,  for  instance,  in  certain 
parts  of  the  temporal  lobe  produce  disor- 
ders having  to  do  with  words.  One  of  these 
is  aphasia  in  which  the  patient  loses  his 
ability  to  form  or  speak  words,  although 
his  vocal  mechanism  is  intact.  In  alexia 
he  sees  but  cannot  get  the  sense  of  words 
that  are  read.  In  still  other  cases,  words 
and  sounds  are  heard  but  they  have  no 
meaning.  These  brain  injuries  appear  to 
abolish  the  particular  mental  processes  by 


Speech  Sounds 


349 


which  the  sensory  slufi  furnished  by  our 
ears  is  collated  and  synthesized  into  words 
and  language. 

A  rough  measure  ot  the  plus  furnished 
by  perception  comes  from  a  study  of  speech 
which  is  chopped  or  distorted.  In  one  set 
of  studies  whole  bands  or  ranges  of  fre- 
quencies   were    completely    icmoved    from 


2 

High  frequencies,,^ 

|/x^Low  frequencies 

o 

only                / 

\              only 

1  60 

—                             / 

\ 

v> 

\ 

1  40 

-                       / 

\ 

s 

\ 

^20 

—              / 

\v 

0 

-^          1 

1               1^ 

70     400 


1000      1900      3100 
Cut-off  frequency 


5100      9000 


FIGURE   172.      INTELLIGIBILITY  OF  FILTERED  SPEECH 

Curves  showing  number  of  words  correctly  under- 
stood when  all  frequencies  above  a  given  point  are 
removed  (leaving  low  frequencies  only)  or  all  fre- 
quencies below  a  given  point  are  removed  (leaving 
high  frequencies  only).  [Derived  from  N.  R.  French 
and  J.  C.  Steinberg,  /.  acoiis.  Soc.  Amer.,  1947,  19, 
90-119.] 

the  speech  of  men  and  women.  The  iri- 
telligibility  of  the  sound  that  remained 
was  amazingly  good.  For  instance,  the  re- 
moval of  all  frequencies  above  1900  cycles 
per  second  left  about  70  per  cent  of  words 
intelligible,  and  the  removal  of  all  sound 
below  1900  cycles  per  second  had  the  same 
result.  The  complete  results  are  shown 
in  Fig.  172.  In  other  words,  just  half  the 
component  frequencies  in  speech  are 
enough  to  give  much  better  than  half  intel- 
ligibility. 

Blanking    out    sections    of    the    flow    of 


speech  with  a  masking  noise,  when  drjnc 
at  moderate  rates,  has  the  same  effect. 
Intelligibility  is  upset  much  less  than  we 
might  expect.  Conversation,  blanked  out 
for  50  per  cent  of  the  time  (at  a  rate  ol 
9  times  a  second),  lost  only  15  per  cent  of 
its  words.  The  amount  heard  for  other 
proportions  of  blanking  can  be  seen  in 
Fig.  173.  To  be  sure,  not  everyone  will 
understand  such  distorted  c^r  chopped 
speech  equally  well.  Some  people  under- 
stand garbled  speech  without  trouble,  can 
listen  successfully  on  a  telephone  with  a  bad 
connection;    other    people    find    this    very 


20  40  60  80 

Per  cent  of  time  speech  was  on 


100 


FIGURE    173.      INTELLIGIBILITY  OF  CHOPPED  SPEECH 

Speech  was  turned  on  and  off  nine  times  per  sec- 
ond. Quite  short  bursts  of  speech  are  enough  to 
give   good   intelligibility.      [G.   A.   Miller,   Psychol. 

Bull.,  1947,  44,  120.] 

hard.      One   person    fits    together,    fills    in, 
hears  the  words;  the  other  does  not. 


REFERENCES 

1.  Beattv,   R.   T.     Hearing  in    man   and   animals. 
London:   G.  Bell,   1932. 

Intended  for  the  lavman,  but  worth  while  for 
his  readable  accoinit  of  hearing  in  general.     It 


350 


Hearing 


traces    lirieHy     the    evolution    of    the    ear    and 
hearing. 

2.  Davis,  H.  Hearing  and  deajness.  St.  Louis: 
Mosby,  1947.  6. 

A  recent  account  of  the  psychological  aspects 
of  deafness,  written  for  the  clinician  and  the 
intelligent  layman. 

3.  Fletcher,  H.  Speecfi  and  hearing.  New  'Sork: 
Van  Nostrand,  1929. 

A  standard  reference  on  the  physical  nature 
of  speech  sounds  and  the  psychophysics  of  the 
ear  that  hears   them. 

■1.  Geotschius.  P.  Theoiy  and  practice  of  tone- 
relations.     New  York:  G.  Schirmer,  1917. 

The  rules  and  conventions  followed  by  com- 
posers when  writing  music  in  our  times.  8. 

5.  Polyak,  S.  L.  The  human  ear  in  anatomical 
transparencies.  Elmsford,  N.  Y.:  The  Sonoto;ie 
Corporation,   1946. 


An  anatomist's  view  which  makes  it  easy  to 
see  the  relation  of  the  ear  to  the  other  parts 
of  the  head. 

Stevens,  S.  S.,  and  Davis,  H.  Hearing,  its  psy- 
chology' and  physiology.  New  York:  ^V'iIey, 
1938. 

A  standard  reference  work  on  hearing,  con- 
taining much  that  is  new  since  the  vacuum 
tube  revolutionized  our  knowledge  of  audition. 
Stevens  is  a  psychologist  and  Davis  a  physiologist. 

Wood,  .\.  The  ph\sics  of  music.  Cleveland: 
Sherwood,  1944. 

A    delightful    summary    of    what  is    known 

about  musical  instruments  and  how  they  work. 

Wood,  A.  B.  A  textbook  of  sound.  New 
York:  Macmillan,  1941. 

The  physical  characteristics  of  sound,  includ- 
ing the  mathematics  used  to  describe  it. 


CHAPTER 


15 


Taste  and  Smell 


THE  sense  of  taste,  by  which  we  detect 
the  flavor  ol  sugar  or  sah,  the  sense  of 
smell,  by  which  we  detect  the  aroma  of 
coffee  or  the  scent  of  perfumes,  and  the 
common  chemical  sense,  by  which  we  feel 
the  sharpness  of  pepper  and  the  irritation 
o£  chlorine  gas,  are  known  as  the  chemical 
senses.  It  is  by  them  that  we  obtain  not 
only  information  concerning  the  external 
chemical  environment,  but  also  information 
concerning  the  internal  chemical  environ- 
ment of  our  own  bodies. 

Although  adult  persons  of  our  culture 
are  largely  influenced  in  their  choice  of 
food  by  social  custom  and  personal  idio- 
syncrasy, it  appears  that,  when  given  a 
choice,  savages,  young  children  and  animals 
select  food  that  satisfies  their  nutritional 
needs.  (See  pp.  119-121.)  These  pref- 
erences seem  to  depend  in  gieat  measure 
on  the  chemical  senses,  particularly  the 
sense  of  taste. 

In  lower  animals  smell  probably  plays 
an  important  role  in  sexual  selection  and 
mating.  Some  animals,  like  the  musk  deer 
or  civet  cat,  apparently  find  their  mates 
by  means  of  the  extremely  strong  odors 
arising  from  glands  in  the  genital  regions. 
In  the  white  rat  experiments  show  that, 
although  the  surgical  removal  of  the  sense 
of  smell  does  not  impair  normal  copula- 
tion, the  level  of  sexual  activity  is  reduced. 

This  chapter  was  prepared  by  Carl 

351 


In  man  generally,  olfaction  is  probably 
less  important,  yet  its  role  is  not  altcjgether 
negligible;  strong  body  odors  may  have  a 
direct  efl^ect  on  the  course  of  sexual  excite- 
ment. It  has  been  suggested  that  the  use 
of  perfumes  to  disguise  personal  odors  is  a 
late  development,  that  the  more  primitive 
functions  of  perfumes  may  have  been  to 
heighten  and  fortify  the  natural  bodv  odors 
for  sexual  ends.  Even  today  some  of  the 
finest  perfumes  derive  their  potency  from 
the  presence  of  the  crude  animal  sexual 
odors  like  inusk  or  civet. 

Smell  may  also  give  warning  of  the  pres- 
ence of  undesirable  objects.  We  tend  to 
avoid  the  foul  putrid  odors  of  decaying 
animal  matter.  The  common  chemical 
sense  warns  of  iiritating  and  noxious 
fumes.  Yet  these  senses  are  not  infallible 
indicators  of  die  nature  of  our  chemical 
environment.  Poisonous  elements  in  footl 
which  do  not  readily  dissohe  in  the  sali\a 
may  not  be  tasted,  or,  when  tasted,  thev 
may  not  be  particularly  unpleasant.  Cer- 
tain war  gases  like  mustard  gas  can  do 
great  harm  in  concentrations  too  weak  to 
be  detected,  and  lewisite  can  prove  fatal 
without  being  smelled  at  all. 

Each  of  the  chemical  senses  has  distinct 
sense  organs  located  in  particular  parts 
of  the  nose  or  mouth,  and  each  possesses 
certain  distinctive   characteristics.     Yet   in 

Pfaffmann   of  Brown   ITniversitv. 


352 


Taste  and  Smell 


everyday  life  they  function  together  so  in- 
timately that  most  persons  arc  unaware  of 
their  separate  existence. 

TASTE,    SMELL    AND    THE 
COMMON    CHEMICAL    SENSE 

The  receptors  for  the  sense  of  taste  con- 
sist  of  spindle-shaped    cells    assembled    in 


Tongue 


Throat 


FIGURE     174.       SCHEMATIC    CROSS-SECTION    OF    THE 
HEAD 

The  olfactory  receptors  are  located  high  in  the 
nasal  passage,  the  taste  buds  are  primarily  distrib- 
uted over  the  tongue  and  the  free  nerve  endings  of 
the  common  chemical  sense  occur  throughout  the 
mucous  membrane  of  both  the  nose  and  the  mouth. 
[From  C.  Pfaffmann,  Smell  and  taste,  in  T.  G.  An- 
drews (Ed.),  Methods  of  psychology,  Wiley,  1948, 
p.  268.] 

groups  to  form  taste  buds.  They  are  lo- 
cated in  papillae  on  the  surface  of  the 
tongue  and  neighboring  areas  such  as  the 
epiglottis,  the  larynx  and  parts  of  the 
throat.  (See  Fig.  174.)  Mild  concentra- 
tions of  salt,  sugar,  acid  or  quinine  solu- 
tions elicit  sensation  qualities  of  saline, 
sweet,  sour  or  bitter  respectively,  being 
effective  only  in  those  regions  containing 
taste  buds.  Strong  salt  or  acid  may  also 
elicit  sting  or  pain  from  any  region  of  the 


mouth  cavity  by  stimulating  the  free  nerve 
endings    of    the    common    chemical    sense. 

The  receptors  for  the  sense  of  smell  are 
threadlike  cells  embedded  in  a  pigmented 
jjatch  of  the  mucous  membrane  of  the 
upper  nasal  passages.  Odorous  vapors  may 
enter  by  way  of  the  nostrils  or  from  the 
mouth  cavity  by  way  of  the  posterior  nares. 
(See  Fig.  174.)  The  normal  air  currents  of 
quiet  breathing  may  not  reach  up  to  the 
olfactory  cleft.  Sniffing  spreads  the  air 
currents  more  widely  into  the  upper  parts 
of  the  nasal  passage,  resulting  in  more  ef- 
fective olfactory  stimulation.  Fruity,  flow- 
ery, foul  and  burnt  are  the  names  of  typi- 
cal olfactory  qualities.  They  are  not  ex- 
perienced when  the  nostrils  are  plugged 
so  that  the  odorous  vapors  cannot  enter 
the  nasal  cavity.  In  addition  to  stimula- 
tion of  the  olfactory  receptors,  many  va- 
pors stimulate  the  free  nerve  endings  in 
the  nasal  passages.  Substances  like  am- 
monia have,  in  addition  to  their  typical 
aromatic  odor,  a  painful  or  stinging  quality 
which  can  be  readily  detected  by  persons 
who  lack  the  sense  of  smell.  Many  odor- 
ous substances  excite  the  sense  of  taste, 
and  few  are  purely  olfactory  stimulants. 
Alcohol,  for  instance,  has  an  ethereal  odor, 
a  sweet  taste  and  a  stinging  quality.  Its 
odor  can  be  detected  in  the  weakest  concen- 
tration, its  taste  at  a  somewhat  higher 
value,  whereas  its  mild  sting  appears  only 
in  a  still  higher  concentration.  One  might 
say  that  the  sense  of  smell  is  more  sensi- 
tive than  the  sense  of  taste,  and  taste  more 
sensitive  than  the  common  chemical  sense. 

The  mucous  membrane  of  the  mouth 
and  nose  is  also  endowed  with  cold,  warm, 
touch  and  pressure  sensitivity  much  like 
that  occurring  in  the  skin.  These  fre- 
quently add  still  other  components  to  our 
normal  perception  of  food,  drink  or  other 
chemical  stim.idi. 


Taste 


353 


Savor  a  moutlilul  ol  gootl  (old  Oxa- 
Cola.  What  do  you  sense?  It  has  an  odor 
which  probably  belongs  near  the  spicy 
group  (that  is  smell),  and  a  slightly  bitter 
and  very  sweet  quality  (taste),  and  the  sting 
of  all  carbonated  drinks  (touch),  and  cold 
(temperature  sense)  and  (he  awareness  of  a 
liquid  in  the  mouth  (somcsthesis). 

TASTE 

Primary  Tastes 

It  is  generally  agreed  that  there  are  four 
primary  taste  qualities:  saline,  sour,  bitter 
and  sweet.  Typical  stinudi  for  these  four 
are: 

Saline      sodium  chloride 
(common  salt) 
Sour         hydrochloric  acid 
Bitter      quinine 
Sweet      cane  sugar 

In  order  to  become  a  stimulus,  a  sub- 
stance must  be  in  solution  or  be  soluble 
in  the  saliva  which  fills  the  pores  of  the 
taste  buds.  A  large  number  of  substances 
will  elicit  the  pure  sour,  bitter  or  sweet 
tastes.  There  is,  however,  only  one  stimu- 
lus, sodium  chloride  (common  salt),  which 
calls  out  the  pure  saline  taste.  All  other 
mineral  salts  have  such  complex  tastes  as 
salty-bitter,  sour-salty-bitter,  etc.  These 
complex  tastes  can  be  compounded  by  ap- 
propriate mixtures  of  the  four  typical  stim- 
uli named  above. 

The  surface  of  the  tongue  is  not  equally 
sensitive  to  each  of  the  primary  tastes. 
The  tip  is  most  sensitive  to  sweet,  the  sides 
to  sour,  the  tip  and  sides  to  saline  and  the 
back  to  bitter.  Consequently  certain  sub- 
stances taste  differently  at  the  tip  and  at 
the  back  of  the  tongue.  Epsom  salts  taste 
salty   at    the   tip   and   bitter   at    the   back; 


other  substances  are  sweet  at  the   tip  and 
bitter  at  the  back. 

These  findings  suggest  that  a  different 
type  of  taste  receptor  exists  for  each  of  the 
primary  tastes,  and  that  each  type  pre- 
dominates in  a  different  part  of  the  tongue. 
Recent  experiments  in  which  the  sensory 
nerve  impulses  in  tlie  single  nerve  fibers 
of  the  taste  nerves  were  recorded  fjy  elec- 
trophysiological methods  indicate  that 
there  are,  in  fact,  these  different  kinds  of 
taste  receptors.  In  the  cat,  although  all 
taste  nerve  fibers  respond  when  acid  is 
placed  on  the  trjngue,  some  of  the  fibers 
respond  only  to  acid,  whereas  others  re- 
spond to  salt  as  well  as  to  acid,  and  still 
others  to  quinine  as  well  as  to  acid.  This 
discovery  suggests  that,  although  there  are 
different  types  of  receptors,  they  may  not 
correspond  exactly  to  each  of  the  four  pri- 
mary taste  qualities.  Similarly  the  retina 
is  known  to  receive  stimulation  which  is 
perceived  as  combinations  of  the  seven 
unique  colors,  although  it  is  usually  sup- 
posed that  there  are  only  three  different 
kinds  of  cones  in  the  retina. 

Sensitivity 

Of  the  four  tastes,  the  sensitivity  for  bit- 
ter is  the  keenest.  Quinine  can  be  detected 
in  a  solution  of  0.00005  per  cent.  Sweet  is 
next  for  such  synthetic  sweeteners  as 
saccharine,  although  the  sensitivity  for 
sugar  is  not  nearly  so  great.  Sour  and 
salty  are  next  and  in  that  order. 

Not  all  persons  are  equally  sensitive. 
The  most  dramatic  exaniples  are  cases  of 
'taste  blindness'  for  PTC  (phenyl-thio-car- 
bamide).  For  some  persons  tlie  crystals  of 
this  substance  are  bitter,  for  others  they 
are  tasteless.  This  deficiency  appears  to  be 
inherited  as  a  Mendelian  recessive  charac- 
ter. Actually  this  deficiency  is  relative 
rather  than  complete,  for  nearly  everyone 


354 


Taste  and  Smell 


can  taste  PTC  in  a  sufficiently  concentrated 
aqueous  solution. 

Taste  sensitivity  falls  off  with  increas- 
ing age.  Not  only  do  children  ha\e  a 
greater  number  of  taste  buds  than  adults, 


tea  becomes  more  sweet  as  the  tea  cools. 
Such  effects  account  in  part  for  the  way 
flavor  changes  with  temperature.  Those 
components  of  flavor  which  depend  on 
smell  are,  on  the  other  hand,   usually  en- 


20 


10 


1                1 

Adaptation 

1                        1 
Recovery 

15%  NaCl-^^,^''''^ 

W-15% 

/  y^0%  NaCl 

lVio% 

//A-5%  NaCl 

'^%  -^    "^          fl — : — 1 

'                                                 1                                                   1 

3/b            1             ^ a i 

20 


30 
Time  in  seconds 


10 


20 


30 


ADAPTATION   AND   RECOVERY   CURVES   FOR   SODIUM    CHLORIDE 


The  course  of  adaptation  to  three  concentrations  of  sodium  chloride,  1.5,  10  and  .'J  per  cent,  is  shown 
for  an  adaptation  period  of  30  seconds  and  a  recovery  period  of  30  .seconds.  Each  curve  indicates  the 
ihresliold  values  at  various  intervals  after  adaptation  or  recovery  had  be;;un.  The  unadapted  tlireshold  is 
0.24  per  cent.     [After  H.  Hahn  (1934).] 


but  their  taste  thresholds  are  lower  than 
those  of  older  people.  The  use  of  tobacco 
reduces  taste  sensitivity,  but  this  effect  ap- 
pears to  be  temporary.  Other  drugs  like 
cocain  will  reduce  or  abolish  taste  before 
the  other  senses  of  the  tongue  are  desensi- 
tized. 

Temperature  of  the  taste  solution  has  a 
definite  effect  on  the  intensity  of  taste. 
Extremely  high  or  low  temperatures  usually 
lower  taste  sensitivity.     The  sugar   in   hot 


lianccd  by  indcased  temperature,  for  more 
aroma  is  given  off  by  warm  substances. 

Adaptation 

Continuous  exposure  to  a  stimulus  leads 
to  sensory  adaptation,  the  diminution  or 
even  the  disappearance  of  the  sensation 
along  with  a  reduction  in  sensitivity.  (See 
Fig.  175.)  Sweet  candies  or  drinks  taste 
less  sweet  after  several  swallows. 

Adaptation  not  only  affects  the  taste  un 


Taste 


355 


clergoing  adaption    but   may   also   riiliaixc  tiicy   will    lake   fDoiij^li   salt   \(>   keep   ihern- 

the  sensitivity  to  other  stiimili,  a  plienoiiie-  selves  alive  and  in  good  health  (Fig.   176;. 

non   sometimes   called   successive    conlrasl.  H  the  taste   nerves   to  the   tongue  are  cut 

For  instance,  adaptation  to  salt  lowers  the  by  surgical  intervention,  however,  the  ani- 

threshold  for  sour,  sweet  and  bitter.     The  mal  loses  the  ability  to  make  this  selection 

sweet  taste  of  water  after  sour   pickle  or  and  soon  dies. 

sour  lemonade  is  an   example   familiar   to  'Ihis  craving   is  accompanied   by  an   in- 
all,  (rcased    sensitivity    to    salt.      Ail    rats    will 


«40 

E 
■£30 


■§20 

c 

ID 

c 

i  0 


350 
300 

„  250 

E 
«) 

c  200 

c 
op 

i  150 

>. 

T3 

O  ( 

h       100 

50 

0 


\ \ r 

Without  salt  choice 
Rat  No,  133T 

Body  weight ~TK^'''^'"^v, 


/ 


,'a*    i       8^=- Water      *i 


Adrenalectomy.      i,,Died 


With  salt  choice 
Rat  No.  141  N 


<. 


Body  weight 


If. 


-V^Water 


Adrenalectomy 


51        61  71         81 

Age  in  days 


Killed 


91         68         78 

FIGURE    176.      THE   INCREASED   SALT   APPETITE  AFTER  REMOVAL   OF  THE  ADRENAL  GLAND 


98         108        118        128        138        148 
Age  in  days 


Rat  133  T  had  no  access  to  salt  and  died  a  few  days  after  removal  of  the  adrenal  gland  (i.e..  after 
adrenalectomy).  Rat  141  N,  which  had  access  to  3  per  cent  sodium  chloride  solution,  started  taking 
more  salt  after  being  adrenalectomized  and  was  still  living  seven  weeks  later.  Arrows  show  when  the 
adrenal   glands  were   removed.      [After   C.   P.   Richter,  Harvey  Lectures  1942-1943,  p.  66.1 


Physiological  Effects 

Changes  in  taste  may  follow  changes  in 
the  physiological  condition  of  the  organ- 
ism. Diseases  of  the  adrenal  gland  or  re- 
moval of  the  same  organ  in  animals  pro- 
foundly upsets  the  salt  balance  in  the  tis- 
sues of  the  body.  Large  amounts  of  salt 
will  be  excreted  and,  unless  the  intake  of 
salt  is  increased,  the  animal  will  die.  Ani- 
mals with  this  gland  removed  show  a  great 
craving  for  sodium  chloride  if  they  are 
given   access   to   a  salt  soltition.      In   fact. 


show  a  preference  for  weak  salt  solution 
over  plain  water.  Normal  animals  first 
show  this  preference  at  concentrations  of 
0.055  per  cent.  Animals  with  their  adrenal 
glands  removed  first  show  a  preference  for 
salt  at  concentrations  as  low  as  0.0037  per 
cent,  a  concentration  too  low  to  have  any 
beneficial  effects.  Presumably  there  is  a 
salt  deficiency  in  all  tlie  tissues  of  tlie  body, 
a  deficiency  which  may  sensitize  the  tasre 
cells  or  make  the  animal  more  on  the  alert 
for  salt. 


356 


Taste  and  Smell 


That  such  a  process  can  occur  in  human 
beings  is  suggested  by  a  number  of  clini- 
cal reports.  One  of  the  most  dramatic 
of  these  relates  the  case  of  a  3^-year-old 
boy  with  a  disease  of  the  adrenal  gland. 
This  boy  kept  himself  alive  for  more  than 
two  years  by  eating  salt  by  the  handful. 
When  this  exaggerated  salt  intake  was  rc- 


105 
90 

I  75 

E 
on 
■o  60 


;;  45- 


30 


15  - 


~r 

1     1     1 

1     1     1     1     1     1 

__^ 

,,---'''' 

- 

^^^       ^-Unpleasant 

- 

/'Indifferent 

• 

- 

r 

- 

- 

X^'' 

- 

_/ 

.t^Pleasant 

^ 

— 

J. 

T'   1     1 

1    r  r^^«=4=-^ 

^ 

0.5  1 


23456789 
Per  cent  of  common  salt  In  solution 


10 


FIGURE    177.       THE    EFFECT    OF    STRENGTH    OF    SALT 
(sodium    chloride)    solution    on    THE    PLEASANT- 
NESS   OF   TASTE 

The  lolal  mniihcr  of  pleasant,  iiiipleasaiu  and 
iiiilitfeieiiL  juclgnieius  given  by  seven  subjecls  in 
seven  sittings  are  shown.     [After  R.  Engel   (1928).] 

duced  by  restriction  to  a  regular  hospital 
diet,  he  soon  developed  symptoms  of  salt 
deficiency  and  died. 

The  four  primary  tastes  are  not  all 
equally  pleasant.  Some,  like  quinine,  are 
almost  always  unpleasant  and  even  nau- 
seating in  all  but  the  weakest  concentra- 
tions; others,  like  sugar,  arc  nearly  always 
pleasant;  still  others,  like  salt  or  citric 
acid,  tend  to  be  pleasant  in  mild  concen- 
trations but  unpleasant  when  strong.  Fig- 
ure 177  shows  this  relation  for  salt  ex- 
pressed quantitatively.  In  the  weak  con- 
centrations the  indifferent  taste  predomi- 
nates. At  2  and  3  per  cent,  the  taste  is 
pleasant,  but  in  stronger  solutions  the  taste 


is  mostly  unpleasant.  Although  this  rela- 
tionship is  typical  for  most  of  the  persons 
tested,  there  may  be  individual  differences. 
One  subject,  liking  salt,  usually  reported 
the  salt  as  pleasant  in  all  but  the  most 
intense  concentrations.  How  stable  this 
preference  for  salt  would  remain  on  other 
occasions  when  his  salt  metabolism  might 
have  undergone  some  change  is  still  an  un- 
answered question.  Physiological  changes 
are  not,  of  course,  the  sole  determinants 
of  the  pleasantness  or  unpleasantness  of 
taste.  Many  of  the  more  sophisticated 
tastes  may  be  pleasant  only  to  the  initiated, 
like  black  coffee,  which  is  bitter  but  be- 
loved by  many.  Many  pleasantnesses  have 
to  be  acquired  before  they  can  be  appre- 
ciated. Some  unpleasantnesses  are  acquired 
too.  The  gourmet  does  not  accept  a  child's 
judgment  as  to  what  foods  need  sugar. 

SMELL 

Primary  Odors 

The  fundamental  odor  qualities  arc  less 
well  established  than  the  qualities  of  taste. 
For  one  thing  there  are  many  more  odors, 
and  the  chemist  is  continually  fabricating 
new  compounds  with  new  smells.  One 
classification  that  is  recommended  by  its 
relative  simplicity  and  clarity  is  the  one 
suggested  by  Hans  Henning.  He  argued 
for   six   fundamental   qualities   as   follows: 

Fragrant  like  the  odor  of  violets 

Ethereal  like  the  odor  of  oranges 

Spicy  like  the  odor  of  cloves 

Resinous  like  the  odor  of  balsam 

Burnt  like  the  odor  of  tar 

Putrid  like  the  odor  of  fecal  matter 

In  general,  putrid  and  burnt  odors  tend 
to  be  unpleasant;  fragrant,  ethereal,  spicy 
and  resinous  are  most  often  pleasant,   al- 


Smell 


357 


though  there  are  many  exceptions.  Some 
people  like  garlic  (Iragranl-burnt-pulrid), 
some  dislike  winlergrecn  (fragraiit-etliercal- 
resinous). 

It  is  obvious  that  many  of  the  smell 
names  are  the  names  of  objects.  Fragrant 
describes  a  quality  like  that  produced  by 
flowers.  The  real  stimulus,  ol  course,  is 
not  the  flower  but  some  property,  as  yet  un- 
determined, of  the  molecules  or  n\olecular 
groups  given  off  by  evaporation  of  the  es- 
sential oils  in  the  fiower.  These  particles 
ultimately  reach  and  dissolve  in  the  mucus 
which  covers  the  olfactory  sense  cells. 
Odorous  substances,  for  the  most  part,  are 
organic  substances,  that  is  to  say,  they  are 
compounds  of  carbon.  A  few  of  the  in- 
organic chemical  elements  like  chlorine 
and  bromine  are  odorous.  The  constitu- 
ent of  the  highly  fragrant  attar  of  roses, 
which  is  largely  responsible  for  rose  odor, 
has  been  identified  as  geraniol.  Since  sub- 
stances responsible  for  the  typical  odors  oi 
many  flowers  and  plants  have  been  iso- 
lated, the  perfume  chemist  can  often  de- 
scribe his  product  in  chemical  terms.  The 
essences  from  plants  are,  however,  such 
complex  mixtures  that  often  the  exact  odor 
of  the  natural  product  can  be  duplicated 
only  by  adding  a  small  amount  of  the  natu- 
ral essence  to  the  synthetic  odor.  The 
chemical  laws  of  olfactory  stimulation  are 
largely  practical  rules  which  at  the  present 
time  cannot  be  unified  by  any  simple  or 
rational  principle. 

Sensitivity 

The  sense  of  smell  is  extraordinarily  sen- 
sitive to  odorous  materials.  Substances  like 
natural  or  artificial  musk,  vanillin  or  the 
mercaptans  can  be  detected  in  exceedingly 
small  concentrations.  Only  1 /23,000,000th 
of  a  milligram  of  mercaptan  per  cubic 
centimeter  of  air  is  required   for  stimula- 


tion.     The   oliaccometer   is   used    lor   such 
measurements  (Fig.  178). 

Impairment  of  sensitivity,  called  anosmia, 
may  be  partial  or  complete,  congenital  or 
acquired,  permanent  or  temporary.  The 
frequent  colds  and  catarrhal  conditions  of 
mcjdern  civilized  life  aie  frequently  respon- 
sible for  the  temporary  anosmia  that  we 


FIGURE    178.      A   SIMPLE    OLI- ACTOMLTER 

The  subject  sniffs  at  the  end  of  the  bent-up  tube. 
Over  the  other  end  of  this  smaller  tube  fits  a  larger 
stimulus  tube  made  of  an  odoriferous  substance, 
like  India  rubber.  The  amount  that  the  stimulus 
tube  projects  beyond  the  outer  tube  measures  the 
distance  that  the  air,  which  the  subjects  sniffs, 
passes  over  the  stimulus  substance,  and  hence  the 
intensity  of  the  odor.  The  smaller  tube  is  markeil 
in  stimulus  units,  called  olfacties.  r.\fter  H. 
Zwaardemaker   (1888).] 

have  all  experienced  from  time  to  time. 
A  kind  of  partial  anosmia  has  been  ob- 
served in  which  the  sensiti\ity  to  certain 
odors  differs  markedly  among  a  group  of 
apparently  normal  individuals.  For  in- 
stance, in  one  gioup  of  persons,  some  were 
able  to  detect  fragrance  in  a  particular  red 
verbena  plant,  but  not  in  a  pink  one.  The 
converse  was  true  for  other  people.  Only  a 
few  could  detect  fragrance  in  bodi.  These 
effects  appear  to  lie  quite  within  the  range 
of  normal  sensitivitv.     The  same  odor  mav 


358 


Tasfe  and  Smell 


even  have  different  qualities  in   the   right 
and  left  nostrils  of  the  same  person. 

Adaptation 

Sensitivity  may  be  reduced  as  a  result  of 
fatigue  or  adaptation  to  the  continued 
presence  of  an  odorous  stimulus.  This 
phenomenon  makes  it  possible  for  persons 


20  40  60  80         100 

Adaptation  time  in  seconds 

FIGURE  179.   OLFACTORY  ADAPTATION  CURVES 

Increasing  adaptation  is  measured  by  the  increase 
of  the  olfactory  threshold  (in  olfacties).  Adaptation 
is  shown  to  be  faster  for  benzoin  than  for  rubber, 
and  also  with  each  substance  it  is  faster  for  the 
more  intense  stimulus  (as  indicated  in  olfacties). 
[After  H.  Zwaardemaker  (1895).] 

working  in  a  foul  atmosphere  to  endure  the 
stench.  Medical  students  in  the  dissecting 
rooms  soon  become  adapted  to  the  odors 
of  the  cadavers. 

The  amount  of  adaptation  depends  on 
the  nature  and  intensity  of  the  adapting 
stimidus.  Complete  adaptation  to  cam- 
phor may  occur  in  5  to  7  minutes;  to  balsam 
in  3  to  4  minutes.  The  stronger  the  odor 
the  faster  the  adaptation  (Fig.  179).  Com- 
plete adaptation  to  a  weak  stimulus  is  only 
partial    adaptation    to    a    strong    one.      It 


can  be  shown,  for  instance,  that  the  use 
of  camphor  lotion  for  chapped  lips  elevates 
the  threshold  for  camphor,  and  that  chew- 
ing peppermint  chewing  gum  elevates  the 
threshold  for  peppermint. 

During  adaptation  not  only  will  the  ap- 
parent intensity  of  the  smell  diminish,  but 
sometimes  the  odor  quality  itself  may 
change.  lonone,  which  at  first  resembles 
cedarwood  in  odor,  becomes  less  intense 
and  then  changes  to  a  quality  like  violet. 
This  change  in  quality  of  the  odor  may 
sometimes  be  disastrous  for  cheap  per- 
fumes, which  shift  from  a  flowery  odor  to- 
ward putrid  as  the  stimulation  continues. 

Adaptation  may  be  selective.  Sensitiv- 
ity is  then  reduced  most  for  the  adapting 
stimulus,  somewhat  for  other  substances 
and  not  at  all  for  still  others.  Adaptation 
to  camphor  reduces  the  sensitivity  to  co- 
logne, cloves  and  ethereal  oils.  Adaptation 
to  ammonium  sulphide  reduces  the  efl^ec- 
tiveness  of  hydrogen  sulphide  and  bro- 
mine, but  not  of  etherial  oils  and  coumarin. 

Recovery  after  complete  adaptation  is 
relatively  rapid,  seldom  requiring  more 
than  5  minutes.  The  rate  of  recovery  de- 
pends on  the  time  of  adaptation  and  the 
intensity  of  the  stimulus.  On  the  other 
hand,  fatigue  or  the  action  of  such  drugs 
as  anesthetic  ether  or  gasoline  may  lead 
to  a  leduction  in  the  sensitivity  which  lasts 
for  hoius. 

Physiological  Effects 

Physiological  changes  may  also  influ- 
ence the  acuity  of  smell.  In  women,  for 
example,  an  enhancement  of  sensitivity 
has  been  observed  just  prior  to  the  onset 
of  menstruation  and  during  pregnancy. 
Changes  in  smell  in  relation  to  nutrition 
have  not  been  studied  systematically,  but 
diininished  thresholds  are  said  to  occur 
during  piolonged  fasts. 


Smell 


359 


Odor  Mixtures  and  Blends 

Odors  mix  in  twf)  w;iys.  In  one  way  llu; 
odorous  materials  inlerad  <Iunii(aily  lo 
produce  a  third  substance.  That  is  noi  a 
true  example  of  (lie  mixliue  ol  siinudi, 
because  a  new  stimulus  is  created.  True 
odor  mixture  occurs  wlun  two  or  more 
odorous  compoimds,  whicii  do  not  react 
chemically,  are  combined.  If  the  compo- 
nents are  of  imccpial  strength,  the  stronger 
predominates.  If  the  two  are  ecpially  bal- 
anced, a  fusion  or  blend  results.  Selective 
adaptation  to  one  of  the  components  brings 
out  the  imadapted  member  of  the  pair. 

In  certain  mixtures  another  effect,  co7n- 
prnsntion,  may  occur.  The  effectiveness 
of  each  component  is  reduced  by  the  pres- 
ence of  the  other.  Hence  the  resultant  is 
weaker  than  either  component  alone. 
Compensation    has    been    said    to    operate 


in  the  effectiveness  of  certain  perfumes  in 
ovcicorin'ng  body  odc^rs.  This  effect  of 
coiMpcnsaiicni  was  used  particularly  a  few 
(cnturies  agcj  when  h;i thing  was  not  ccjm- 
nicjn. 

REFERENCES 

1.  C.'roc:kfT,    K.    C:.     flinior.      New    ^Ork:    \U(',raw- 
Hill,   1915. 

I'hc  Knili  rhiilioii  of  Uistc  :iiiil  Miicll  lo  fla%or 
is  prcstnlcd  largely  lioiii  llic  poijit  r,f  \  ic^^  of 
the  food  technologist. 

2.  Moiiciielf,    R.    W.      'I'lir   ilniniiiil    \t  iisf\.      New 
■iork:   Wiley,   1916. 

A  more  extensive  work  which  inc:lti<l(;s  a 
compielieiisi\e    treatment   of    the   themisiry    of 

taste  and  smell. 

3.  Parker,  Ci.  H.     Smell,  l/isir  mid  allied  senses  in 
verlehrales.     Philadelphia:    I.ippincolt,   1922. 

A  clear,  concise,  general  account  of  the  chem- 
ical  senses. 


CHAPTER 


16 


Somesthesis 


SOMESTHESIS,  which  means  literally 
"body  feeling,'  is  the  general  name  for 
all  systems  of  sensitivity  present  in  the  skin 
and  internal  organs  of  the  body.  The  clas- 
sical view  is  that  there  are  five  senses:  sight, 
hearing,  smell,  taste  and  'feeling.'  Aris- 
totle had  it  that  way,  and  current  popular 
usage  preserves  the  traditional  list.  How- 
ever, from  time  to  time  other  classifications 
have  been  made,  some  of  them  distinguish- 
ing more  than  a  score  of  separate  senses. 
Always,  when  the  list  has  been  expanded 
beyond  five,  the  new  senses  have  come  out 
of  'feeling,'  and  whene\'er  the  list  has 
dwindled  the  extra  senses  have  gone  back 
into  feeling  again.  The  reason  for  uncer- 
tainty appears  to  lie  in  the  multiplicity  of 
sense  processes  in  the  skin  and  internal 
organs.  The  skin,  a  complexly  formed 
organ,  contains  nerve  endings  of  several 
kinds.  The  endings  are,  moreover,  vari- 
ously embedded  in  the  skin  and  can  be 
stimidated  in  a  variety  of  ways.  Deeper 
lying  tissues,  such  as  muscles  and  organs 
of  the  viscera,  are  supplied  with  still  dif- 
ferently housed  nerve  terminations.  There 
are,  however,  similarities  among  the  sen- 
sations coming  from  these  different  parts 
of  the  body,  a  fact  which  leads  us  to  regard 
somesthesis  as  involving  several  systems  of 
sensibility  that  essentially  belong  together. 
We  shall  consider  first  the  types  of  sensi- 


bility present  in  the  skin,  then  those  found 
in  internal  bodily  structures,  the  muscles, 
\isceral  organs  and  the  nonauditory  laby- 
rinth of  the  inner  ear. 

CUTANEOUS    SENSIBILITIES 

The  skin  mediates  at  least  four  funda- 
mental qualities  of  sensation— pressure, 
pain,  cold  and  warmth— and  is  supplied 
with  a  variety  of  receptors. 

The  Skin  and  Its  Receptors 

From  its  external  aspect  the  skin  pre- 
sents a  highly  variegated  structure.  In 
some  parts  of  the  body  it  has  a  relatively 
smooth  appearance,  it  is  deeply  creased 
and  furrowed  in  others;  in  some  places 
it  is  stretched  to  the  point  of  tautness,  in 
others  it  is  relatively  mobile;  in  some  re- 
gions it  is  thickened  and  tough,  but  in 
others  thin  and  pliable;  in  some  places  it 
is  hairless,  but  in  others  highly  endowed 
Avith  hairy  appendages.  Moreover,  the 
nerve  supply  to  the  skin  is  highly  variable. 
In  some  parts  of  the  body,  such  as  the  lips 
and  fingertips,  there  are  abundant  nerve 
terminations;  in  others,  such  as  the  middle 
of  the  back,  nerve  endings  are  sparsely  dis- 
tributed. If  different  skin  regions  show 
widely  differing  sensitivities,  it  should  not 
be  surprising.    In  fact,  were  it  not  for  some 


This  chapter  was  j^rcparcd  iiy  Frank  A.  Gcldard  of  the  University  of  Virginia. 

360 


Cutaneous  Sensibilify 


361 


fundanicntiil  iitiiroi  milics  of  stihsmliui; 
structure,  wc  inif^ht  ('vcn  rcj^ard  llic  skin 
as  a  (ollcction  of  ([uilc  sejjaratc  oigaus. 

.Several  successive  layers  comprise  the 
skin,  and  it  is  conventional  to  mark  off 
three  major  j^roupings  ol  them:  the  f;pi- 
dermis,  the  coriuin,  or  true  dermis,  and 
subcutaneous  tissue  (Fig.  180).  The  epi- 
dermis, over  most  of  tlie  body  surface  tough 
and  resistant  to  external  influences,  serves 
as  a  protective  coat.  It  varies  from  a  thin 
layer  only  a  few  cells  thick  at  the  lips  to  a 
relatively  thick  structure  several  milli- 
meters deejj  in  the  callous  ball  of  the  foot. 
Fine  nerve  fibrils,  'free  nerve  endings,' 
penetrate  the  lower  epidermal  layers.  The 
corium,  subjacent  to  the  epidermis,  is  con- 
tinuous with  it,  the  boundary  between  the 
two  being  generally  irregular.  The  upper- 
most level  of  the  corium  consists  of  papil- 
lae, conical  mounds  of  connective  tissue 
projecting  into  the  basal  floor  of  the  epi- 
dermis. It  is  the  regular  lineal  arrange- 
ment of  the  papillae,  giving  form  to  the 
overlying  epidermis,  that  provides  the  or- 
derly lines  of  fingerprints  and  toeprints. 
As  well  as  housing  the  smaller  hair  fol- 
licles, the  ducts  of  sweat  glands  and  the 
greater  portion  of  the  smaller  blood  ves- 
sels of  the  skin,  the  corium  contains  nerve 
fibers  and,  especially,  the  great  majority  of 
cutaneous  nerve  terminations.  They  exist 
in  a  multiplicity  of  forms  and  occur  at 
varying  depths.  The  legend  of  Fig.  180 
provides  an  introduction  to  some  of  them. 
In  the  subcutaneous  tissue,  made  up  largely 
of  fatty  cells  and  loosely  interwoven  con- 
nective tissue  fibers,  which  form  a  bond 
with  underlying  muscles  and  bones,  are  to 
be  found  the  major  blood  vessels,  the  larger 
hair  follicles,  sweat  glands  and  also  a  vast 
network  of  nerve  fibers. 

The  nerve  endings  found  at  all  levels  of 
the  skin  are  unquestionably  the  receptors 


lor  the  various  kinds  oi  (uraneous  sensa- 
tions, though  whether  a  particular  type  of 
end  organ  exclusively  initiates  a  (crtain 
kind  of  sensation  is  by  no  means  established 
with   certainty.      As   we   jjroceed    we   shall 


Mcisinei's  coffiuide 


End  bulbs  ol  Krauie 


free  rwve  trtS'<^ 
I 
Eptd«rmis       I        Demki 


Subcutaneous       Pacinian 
fat  corpusde 


OuO  ol       Ruffini 
»r«at  {land     endin; 


FIGURE    ISO.      THE  SKIN   IN   CROSS-SECTION 

A  composite  drawing  of  the  sl<in,  showing  the  epi- 
dermis, the  underlyifig  dermis  and,  below  the  der- 
mis, the  subcutaneous  tissue,  with  the  stump  of  a 
hair  and  seven  kinds  of  cutaneous  nerve  endings: 
(I)  tactile  discs  within  the  epidermis,  (2)  free  end- 
ings at  the  epidermis,  (3)  Meissner  corpuscles  be- 
neath the  epidermis,  (4)  Krause  end  bulbs  in  the 
dermis,  (5)  Ruffini  endings  in  the  dermis,  (6)  free 
endings  about  the  hair  follicle  and  (7)  Pacinian 
corpuscles  within  the  subcutaneous  tissue.  [Modi- 
fied from  H.  H.  Woolard,  G.  Weddell  and  J.  .\. 
Harpman,  by  E.  Gardner,  Fundamentals  of  neu- 
rology, Saunders.  1947.  p.  111.1 

examine  briefly  the  evidence  for  die  various 
proposed  correlations  between  types  o£  sen- 
sibility and  kinds  of  nerve  terminations. 

Exploration  of  the  Skin  Surface 

The  first  thing  to  be  noted  about  the 
skin's  sensitivitv  is  that  it  is  not  uniformly 


362 


Somesfbesis 


distributed,  even  within  relatively  re- 
stricted areas.  If  a  pencil  point  is  moved 
gently  across  the  back  o£  the  hand,  sensa- 
tions of  touch  or  pressure  are  aroused  at 
some  places.  At  others  cold  sensations  are 
likely  to  flash  out,  and  at  some  point  in  the 
course  of  stimulation  tickle  or  even  itch 
may  be  aroused.  Moreover,  if  tlie  explor- 
ing stimulus  is  changed  to  a  sharper  or 
duller  object,  or  if  the  mode  of  attack  is 
\aried  to  involve  direct  pressure  into  the 
skin,  or  if  warmed  or  cooled  metal  points 
are  substituted,  a  considerable  range  of  sen- 
sations may  result.  This  suggests  that  the 
skin's  potentialities  for  sensations  may  be 
gauged  by  exploring  sample  areas  in  a  .sys- 
tematic manner  and  by  using  a  variety  of 
stimidi.  The  possibilities  are  extensive, 
for  the  skin  proves  to  be  responsive  not 
only  to  mechanical  force  exerted  on  it  but 
also  to  electrical,  thermal  and  chemical 
stimuli  as  well. 

To  make  possible  systematic  exploration 
it  is  ob\iously  necessary  to  use  some  sort 
of  mapping  technicjue.  You  can  mark  the 
skin  off  by  using  a  rubber  stamp  which 
impresses  on  it  a  large  grid,  divided  into 
many  tiny  squares,  each  one  millimeter  on 
a  side.  Then  you  study  separately  the 
sensitivity  of  each  square  millimeter;  or, 
using  a  binocular  microscope,  you  can  study 
and  map  the  cutaneous  topography  (fur- 
rows, hair  stumps,  sweat  ducts,  etc.)  and 
localize  your  stimidi  with  respect  to  these 
signs. 

PRESSURE    SENSITIVITY 

For  the  arousal  of  pressure  sensations 
the  conventional  stimidus  is  a  hair,  human 
or  animal,  of  suitable  length,  diameter  and 
stiffness.  Several  hairs,  each  attached  at 
right  angles  to  a  wooden  holder,  may  be  ar- 
ranged to  provide  a  graded  pressure  series. 


You  place  the  end  of  the  hair  over  the 
spot  to  be  stimidated,  then  press  the  holder 
down  to  the  point  of  bending  the  hair. 


I  1  I    t  i   u  1 


ij  1    ii  J  1  i    i 
I   i    i    I  I  u 
I    I  i 


•  =  Pressure  spot  |  =  Hair 

A.B  =  Apparently  hairless 
pressure  spots 

FIGURE    l8l.       PRESSURE   SPOTS   ANO    HAIRS 

Map  from  \olar  side  of  luidiile  forearm. 
H.  Stnishold  (1925).] 


[After 


If  a  sample  area  on  the  under  side  of  the 
forearm  is  explored  point  by  point  with 
a  hair  stimulus  of  moderate  strength,  the 
kind  of  map  of  pressure  sensitivity  shown 
in  Fig.  181  results.  The  striking  thing 
about  the  distribution  of  sensitive  points 
is  that  it  almost  coincides  witli   the  distri- 


«   • 
•  •  • 


•  ••• 


'•••.. 


r. 


(1  sq  cm) 

I  lf;URE    l8i!.       PRK.SSURE   SPO  IS   ON    HAIRLESS  REGION 
OF    SKIN 

y\dp  from  web  heiween  tliiimb  and  index  finger. 
^After  A.  Goldscheider  (188.5).] 

bution  of  liairs,  Avhich,  in  this  region,  are 
plentiful.  Moreover,  it  is  notable  that  tiie 
'spots'  of  high  sensitivity  found  in  iliis  man- 


Pressure  Sensitivity 


363 


ncr  are  quite  consistently  located  to  liie 
'windward'  of  the  hairs  as  they  emerge 
obliquely  from  the  epidermis,  as  if  the  le- 
ceptors  lay  below  the  surface  at  the  bases 
of  the  hairs.  Nevertheless,  a  similar  ex- 
ploration,   confined    to    a    hairless    region, 


100 
80 

1 

\ 

1                1 

^ 

00 

/ 

leo 

_ 

/ 

— 

V 

/ 

£ 

/ 

a 

/ 

140 

o 

- 

/  o 

- 

■/ 

20 

'/ 

/ 

1 

1            1 

0.1     0.4     0.6  1.0  1.6 

Stimulus  intensity  in  grams 

FIGURE   l8lj.      PRESSURE  .SENSniVrrV  AS  DETER^nNEU 
BV    INTENSITY 

I'loporlions  of  spots,  in  a  one-centimeter  area, 
responsive  lo  hair  stimuli  of  graduated  intensity 
(grams).  [From  the  data  of  J.  P.  Guilford  and 
E.  M.  Lovewell,  /.  gen.  Psychol,  1936,  IS,  154.] 

such  as  the  web  between  the  thumb  and 
index  finger,  also  yields  a  pattern  of  'spots' 
of  high  sensitivity  (Fig.  182).  If  pressure 
reception  in  the  hairy  regions  of  the  skin 
is  in  some  manner  connected  with  end 
organs  at  hair  follicles,  this  explanation 
will  not  serve  for  the  hairless  regions. 

Something  more  about  the  way  pressure 
sensitivity  is  distribtited  may  be  learned 
by  repeating  the  exploration,  in  either  of 
these  areas,  with  stronger  stimuli.  If  this 
is  done,  more  'spots'  will  appear  and,  if 
strong   enough,    there    is   no    place   where 


the  sliinulus  hair  may  be  set  down  without 
evoking  a  response.  The  relation  between 
stimulus  intensity  and  the  percentage  of 
'spots'  in  a  sample  area  one  centimeter 
square  is  .shown  graphically  in  Fig.  18.S. 
It  would  appear  that  every  point  on  the 
skin  has  the  potentiality  for  arousing  pres- 
sure sensations. 

The  elie<t  of  medianiral  impad  on  the 
skin  is  not,  of  (ourse,  (onlnu-d  to  a  single 
point,  howcNcr  small  ihc  stimidiis  may  be. 


IIGURE     184.        EKKECT    OF    .SII.MUII     OF     DIFFERENT 

INTENSITIES   APPLIED    lO   DIFFERENT   SPOIS    OF   1  HE 

SKIN 

'Ihe  stimidi  are  hairs  wliicli  are  pres.sed  against 
the  skin.  The  longer  and  finer  the  stimulus  hair, 
the  less  the  pressure.  The  diagonal  lines  are  hairs 
protruding  fronr  hair  follicles  in  the  skin.  [.Xfter 
K.  M.  Dallenbach  (1935).] 

The  cutaneous  tissues  are  highly  elastic 
and  transmit  to  considerable  distances  and 
in  all  directions  disturbances  created  at  a 
point  on  the  surface.  The  greater  the  sur- 
face distortion,  the  farther  into  the  skin 
and  along  its  surface  will  the  deformation 
be  carried.  Thus  are  set  up  tensions, 
which,  occurring  in  the  right  places,  may 
initiate  nerve  discharges.  Figtire  184  shows 
four  possibilities  of  stimulation  bv  hairs. 
.Stimulus  B  in  this  case  is  most  favorablv 
located  to  affect  end  organs  and  thus  arouse 
pressure  sensations. 

Experiments  have  shown  that  die  stimti- 
lus  can  consist  of  an  outward  distortion 
of  the  surface,  and  the  resulting  sensation 
will  be  the  same.  An  up^^•ard  tug  on  a  hair 
or  on  a  thread  glued  to  die  skin  surface 
may  produce  a  pressure  sensation  indis- 
criminable  from  that  brought  about  bv  a 


364 


Somesthesis 


depression  made  by  a  stimulus  hair.  Herein 
lies  another  reason  for  supposing  that  the 
true  stimulus  for  the  pressure  sensation  is 
tension  set  up  within  the  skin  and  not 
actual  pressure  on  the  skin. 

Perception  of  Vibration 

The  skin  is  very  sensitive  to  vibration 
and  to  differences  in  rates  of  vibration.  It 
it  possible  to  discriminate  acciuately  be- 
tween 420  and  425  cycles  per  second,  when 
the  two  rates  are  Aibration  pressiues  pro- 
duced by  holding  tuning  forks  against  the 
skin.  There  has  been  some  talk  about 
there  being  a  special  'vibration  sense,"  but 
recent  experiments  make   it  clear   that  vi- 


0.300 


0.050 


Pressure  insensitive 


Pressure  sensitive_- 


64 


128  256  512 

Frequency  in  cycles  per  second 


1024 


FIGURE     185.       VIBRATORY    THRESHOLDS    FOR    PRES- 
SURE-SENSITIVE  AND    PRESSURE-INSENSITIVE    REGIONS 

-Absolute  thresholds  for  the  'whirring"  feeling  de- 
termined at  five  frequencies  (64  to  1024  cycles  per 
second)  on  a  region  especially  sensitive  to  pressure 
and  on  another  region  especially  insensitive  to 
pressure.  Sensitivity  to  vibration  increases  greath 
\vith  sensitivity  to  pressure.  Dotted  lines  show 
\ariabilily  of  measurement.  [.After  F.  A.  Geldard, 
/.  gen.  Psychol.,  1940,  22,  286.1 


bration  is  perceived  by  way  of  the  pres- 
sure receptors,  that  percei\ed  \ibration  is 
pressure  in  inovement. 

The  results  of  such  an  experiment  are 
shown  in  Fig.  185.  Two  regions  of  the 
skin  were  selected,  one  containing  ten  very 
sensitive  presstire  'spots,'  and  one  with  ten 
Aery  insensitive  pressure  'spots.'  Then  the 
absolute  thresholds  for  the  perception  of 
A'ibration  were  determined  for  each  region 
at  each  of  five  vibration  frecjuencies  (64 
to  1024  cycles  per  second).  The  figure 
shows  that  the  pressure-insensitive  region 
is  in  all  cases  also  the  vibration-insensitive 
region.  It  does  not  take  much  movement 
of  the  skin  to  set  up  the  perception  of 
vibration.  In  the  sensitive  region  0.025 
millimeter  was  enough.  In  the  insensitive 
region  the  thresholds  ran  from  0.100  to 
0.250  millimeter. 

Tickle,  sometimes  introduced  to  students 
as  a  separate  sense,  is  really  a  vibratory 
perception  which  occurs  when  the  stimulus 
'teeters'  or  when  several  nerve  fibers  are 
successively  activated.  It  is  not  known 
certainly  why  some  intense  stimulation  of 
this  sort  gives  rise  to  reflex  movements  of 
escape  or  laughter. 

Pressure  Adaptation 

Pressure  sensitivity  displays  the  phe- 
nomenon of  adaptation.  Continuous 
stimulation  results  in  a  fading  and,  eventu- 
ally, in  complete  abolition  of  sensation. 
The  time  taken  for  the  sensation  created 
by  a  weight  resting  on  the  skin  to  disap- 
pear completely  is  directly  proportional  to 
the  size  of  the  weight  and  inversely  pro- 
portional to  the  skin  area  contacted. 

There  is  good  evidence  to  belieAC  that 
pressure  adaptation  has  a  simple  mechani- 
cal basis.  A  weight  placed  on  the  skin 
surface  continues  to  compress  the  under- 
lying tissues  and  'settle'  into  the  skin  for  a 


Pressure  Sensibility 


365 


surprisingly  long  liiiic.  In  one  cxp(  i  iincnt 
it  was  shown  that  pressure  sensations  le- 
main  only  as  long  as  the  settling  (ontinues 
or  until  the  rate  of  movement  into  the  skin 
is  reduced  below  the  intensitive  threshold. 
At  that  point  adaptation  is  complete,  lor 
effective  stimuhition  has  ceased. 

Aftersensations,  which  occur  commonly 
in  the  realm  of  pressure  sensitivity,  repre- 
sent a  renewal  of  positive  stinudaticjn. 
Upon  removal  of  the  deforming  stimulus 
the  skin  tissues  tend  to  resume  their  nor- 
mal positions.  So  long  as  restorative 
movements  are  occurring  within  the  cu- 
taneous tissues  aftersensations  will  be 
aroused,  actually  in  the  absence  of  an  ex- 
ternal stimulus. 

Localization  of  Pressures 

The  ability  to  localize  pressure  sensations 
varies  greatly,  depending  on  the  bodily  re- 
gion involved.  If  an  observer  is  blind- 
folded and  is  touched  lightly  on  the  finger- 
tip, he  will  usually  indicate  the  spot 
touched  with  an  error  under  two  milli- 
meters in  extent.  At  the  tip  of  his  tongue 
his  error  is  almost  too  small  to  be  meas- 
ured. Touch  him  on  the  thigh  or  upper 
arm,  however,  and  he  is  likely  to  miss  by 
several  centimeters.  Localization  is  best 
in  relatively  mobile  areas  of  the  skin,  in  the 
hands,  feet  and  mouth  regions. 

A  different  kind  of  capacity  for  localiza- 
tion is  found  in  exploring  the  body  sur- 
face with  compass  points  to  find  the  so- 
called  two-point  threshold.  In  each  skin 
area  there  is  some  separation  of  two  points 
which  just  gives  rise  to  two  discrete  im- 
pressions; if  the  points  are  brought  closer 
together  and  are  simultaneously  applied, 
they  arouse  a  unitary  impression.  On  the 
average  the  values  of  the  two-point  thresh- 
old shown  in  Table  XVIII  will  be  found 
to  hold  for  the  normal  observer.     In  cer- 


TABLE  XVIII 

Rkprkskntativk  Values  of  thk  Two-Point 
Thre.shold 

metm 

Tip  of  the  tongue  1 

Palmar  side  of  the  last  phalanx  of  the  finger  2 

Red  part  of  the  lips  5 
Palmar  side  of  the  second  and  dorsal  side  of  the 

third  phalanx  of  the  finger  7 

White  of  the  lips,  and  metacarpus  of  the  thumb  9 
Cheek,  and  plantar  side  of  the  last  phalanx  of 

the  great  toe  1 1 

Dorsal  side  of  the  first  phalanx  of  the  finger  16 

Skin  on  the  back  part  of  cheek  bone,  and  forehead  23 

Back  of  the  hand  31 

Kneepan,  and  surrounding  region  36 

Forearm,  lower  leg  40 

Back  of  foot,  neck,  chest  54 

Middle  of  the  back,  and  of  the  upper  arm  and  leg  68 

tain  cases  of  brain  tumor  and  other  abnor- 
malities of  the  central  ner\ous  system,  the 
ability  both  to  localize  touches  on  the  skin 
and  to  discriminate  two  simultaneously 
applied  points  becomes  markedly  impaired 
or  is  even  absent,  despite  retention  of  bare 
pressure  sensibility.  Tests  incorporating 
these  two  performances  are,  therefore,  made 
a  part  of  routine  clinical  examination  of 
the  nervous  system. 

Receptors  for  Pressure 

The  receptor  organs  for  pressure  have 
not  been  identified  with  certainty.  The 
common  location  of  spots  of  highest  pres- 
sure sensitivity  to  the  'windward'  of  hairs 
suggests  that  the  receptors  should  lie  at  the 
hair  follicles,  which  are  known  to  be  well 
supplied  with  sensory  nene  terminations. 
These  fibers  twine  so  freely  around  tlie 
base  of  a  hair  that  diey  have  been  called 
basket  endings.  Presumably  they  are  pres- 
sure receptors.  But  what  about  hairless 
regions?  Pressure  sensiti^  ity  on  the  hairless 
palms  is  very  high.  The  guess  has  been 
that    Meissner    corpuscles,    sensory    nene 


366 


Somesthesis 


endings  situated  in  the  papillae  of  the 
coriiun,  are  the  receptors  here.  They  arc 
abundant  in  the  palms  of  the  hands  and  the 
soles  of  the  feet,  occiuring  in  some  profu- 
sion in  the  tips  of  the  fingers  and  toes,  and 
thus  seem  to  have  the  proper  distribution. 
However,  the  evidence  is  no  more  formid- 
able than  this.  It  may  eventually  turn  out 
that  other  forms  of  specialized  endings  can 
also  initiate  pressure  impidses. 

PAIN    SENSITIVITY 

Pain,  of  all  the  cutaneous  sensations,  is 
aroused  most  generally  over  the  skin  sur- 
face. It  is  produced  by  several  forms  of 
stimuli:  mechanical,  chemical,  thermal  and 
electrical.  If  mechanical  stimuli  are  used, 
they  must  either  be  applied  with  consider- 
able force  or  they  must  be  sharply  pointed, 
sufficiently  so  to  penetrate  the  epidermis  or 
produce  a  deep  depression  in  it.  This 
deformation,  of  covnse,  causes  the  prior 
arousal  of  pressure  sensations,  and  with 
mechanical  stimulation  pain  cannot  be  iso- 
lated from  pressure.  Many  chemicals, 
when  injected  into  the  skin,  elicit  pain. 
The  hydrogen  ion  is  particularly  powerful 
in  liiis  respect,  the  intensity  of  the  pain 
being  determined  by  the  degree  of  acidity 
of  the  injected  solution.  Chemical  stimuli 
cannot,  however,  be  confined  to  a  local 
area,  and  with  their  use  it  is  difficult  to 
determine  the  distribution  of  pain  sensi- 
tivity and  the  exact  mode  of  operation  of 
the  receptor. 

The  production  of  pain  by  extremes  of 
temperature  is  familiar.  As  with  mechani- 
cal stimuli,  however,  pain  is  not  produced 
in  isolation  when  warm  or  cold  objects  are 
used  as  stimulators.  Pressme  is  a  neces- 
sary accompaniment  to  warmth  and  cold. 
One  recently  devised  technique,  however, 
circimivents   this  difficulty.      It   consists   in 


using  radiant  heat  from  the  type  of  bulb 
used  in  a  'sini  lamp'  and  focusing  its  rays 
sharply  on  the  skin  by  means  of  a  lens. 
Warmth  is  aroused  by  such  a  method,  but 
it  is  not  hard  to  distinguish  the  sharp, 
stabbing  pattern  of  pain  from  the  diffuse 
background  of  warmth.  Concomitant 
pressiue  is  entirely  avoided.  If  the  time 
of  exposure  is  held  constant  and  the  inten- 
sity of  the  heat  source  is  varied  in  small 
steps,  it  is  possible  to  measiue  the  pain 
threshold  with  some  precision.  For  a 
group  of  150  subjects  of  both  sexes  and  of 
wide  age  range  the  absoliue  threshold 
proved  to  be  constant  at  0.21  gram-calories 
per  second  per  square  centimeter,  with  a 
variation  of  about  15  per  cent. 

Perhaps  the  best  of  the  methods  to  arouse 
ptue  local  pain  and  chart  its  distribution 
is  to  make  use  of  electrical  stimuli.  A  cir- 
cuit may  be  arranged  to  permit  a  high 
potential  discharge  to  the  skin  from  an 
electrode  held  just  above  it.  Such  a  'spark- 
ing' method  brings  out  the  essentially  punc- 
tate distribution  of  pain  sensitivity.  Not 
all  local  points  on  the  skin  respond  with 
pain.  Some  spots  give  pressure,  others 
cold,  and  some  warmth.  But  pain  is 
aroused  from  the  largest  number-  of  points, 
and  the  distribution  of  its  'spots'  appears 
to  be  quite  haphazard. 

Pain  Adaptation 

It  is  not  immediately  obvious  that  pain 
subsides  with  continued  stimidation.  A 
cut  or  bruise  seems  no  less  painfid  imtil 
'something  is  done  for  it.'  Cutaneous  pain, 
however,  does  undergo  adaptation.  Press 
a  needle  into  the  skin  with  a  steady,  un- 
varying force  and  pain  is  aroused  which 
gradually  loses  its  intensity  and  eventually 
disappears  altogether,  leaving  a  sensation  of 
pressure.  Produce  pain  by  radiant  heat 
and,  if  stimulation  remains  steady,  the  pain 


Pain 


367 


will  subside,  leaving  a  residue  of  warmth. 
Similarly  the  pain  accompanying  extreme 
cold,  such  as  is  induced  i;y  dry  ice  held 
dose  to  the  skin,  will  lade  out  slowly  leav- 
ing behind  only  cold.  For  a  long  time  it 
was  supposed  that  pain  had  no  separate 
sensory  existence  but  was  simply  the  result 
of  overstimulation  of  other  senses.  'Ihese 
facts  of  adaptation,  however,  taken  tc> 
gcther  with  the  demonsi ration  of  'spot' 
distribution,  make  it  appear  that  pain  con- 
stitutes a  separate  system  of  sensitivity  with 
its  own  special  receptors. 

Pathways  for  Pain 

Ihe  arousal  of  pain  is  notoriously  slow. 
Touch  a  hot  object  or  stub  your  toe  and  a 
noticeable  interval  passes  before  the  pain 
is  felt.  Meanwhile  there  is  appreciation, 
by  way  of  pressme  sensations,  that  the  ob- 
ject has  been  contacted.  The  delay  in  the 
])ain  response  suggests  that  it  is  carried  by 
fibers  of  slow  conduction  rate.  The  weight 
of  evidence  is  that  pain  is  mediated  chiefly 
by  fibers  of  small  diameter,  and  it  is  well 
known  that  the  smaller  the  fiber  the  more 
slowly  it  conducts  impulses.  We  should, 
therefore,  expect  reaction  time  to  pain- 
producing  stimuli  to  be  relatively  long, 
and  it  is.  As  much  as  a  full  second  may 
elapse  after  the  onset  of  the  stimulus  be- 
fore pain  is  felt. 

Not  only  is  there  e\'idence  that  pain  in- 
volves a  separate  jaeripheral  mechanism 
but  it  is  known  also  that,  in  the  course  of 
conduction  up  the  spinal  cord,  tracts  dif- 
fering from  those  responsible  for  pressure 
sensations  are  used  for  pain.  Pain  impulses 
ascend  the  spinal  cord  in  the  so-called 
anterolateral  tract,  a  region  through  which 
impulses  for  pressure  do  not  pass.  In  the 
disease  known  as  syringomyelia,  the  central 
canal  of  the  cord  widens  and  interrupts 
these  pain   tracts.     Clonseciuentiy  a   loss  of 


j^ain  sensaticjtis  (and  usually  <A  tempera- 
ture) with  full  preservation  of  pressure 
sensitivity  is  bnjught  abcjut.  The  arrange- 
ment of  the  conducticjn  jjailis  also  makes 
possible  a  surgical  cjj^eration  lor  peisistent 
and  unbearable  jjain.  Culling  through  the 
anterolateral  tract  at  a  suitable  level  abol- 
ishes pain  sensitivity  in  the  affected  region 
but  dcjes  ncjt  interfere  with  tcjuch  cjr  pres- 
sure from  the  same  area. 

Pain  Receptors 

Since  pain  has  been  disccjvercd  to  consti- 
tute a  separate  system  there  is  naturally  an 
effort  to  link  it  with  a  special  type  of  nerve 
ending.  The  very  general  occurrence  of 
pain  in  all  regions  leads  one  to  attribute 
it  to  the  operation  of  the  most  connnonly 
found  type  of  nerve  termination,  the  free 
nerve  ending.  The  most  excjuisitely  pain- 
ful regions  of  the  body  are  the  cornea  of 
the  eye  and  the  inner  reaches  of  the  exter- 
nal auditory  canal.  Only  free  nerve  end- 
ings can  be  foimd  in  these  tissues.  This 
sort  of  evidence  cannot,  however,  be  re- 
garded as  final.  There  must  be  receptors 
in  the  skin  for  pain,  biu  we  cannot  )et  be 
sure  what  they  are. 

TEMPERATURE    SENSITIVITY 

For  the  production  of  warm  and  cold  sen- 
sations heated  or  cooled  metal  points  will 
serve.  Ihe  best  temperature  stimulators 
are  arranged,  usually  by  the  aid  of  circu- 
lating water,  to  maintain  constant  a  pre- 
determined temperatine. 

Sensitivity  to  warmth  and  to  cold,  like 
sensitivity  to  pressure  and  pain,  is  distrib- 
uted in  'spots'  over  the  skin.-  Exploration 
with  warmed  or  cooled  metal  points  reveals 
'spots'  especially  sensitive  to  cold,  others 
readih  responsive  to  \var!nth.  As  with 
pressure,  however,  the  number  of  spots  re- 


368 


Somesthesis 


spoiiding  in  a  given  liiniied  region  depends 
on  the  intensity  of  the  stimulus.  Let  the 
point  of  the  stimuhitor  be  maintained  at 
a  temperatme  just  a  little  above  that  of 
the  skin  and  only  a  few  warm  spots  will 
be  located;  raise  its  temperature  appreciably 
and  the  population  will  increase.  A  com- 
parable rule  holds  for  cold. 


COLD    SPOT    PATTERNS 


Successive  mappings,  A  and  B,  5  minutes  apart, 
of  a  one  square  centimeter  area  on  the  forearm.  In 
each  exploration  every  square  was  stimulated  once 
with  a  metal  point,  one  millimeter  in  diameter,  at 
a  constant  temperatme  of  17°  C  and  at  a  constant 
pressure.  Blackened  squares  indicate  reports  of 
cold.  In  A,  33  per  cent  of  the  millimeter  squares 
responded  with  cold  sensation;  in  B,  31  per  cent. 
The  two  maps  agree  exceptionally  well  (88  per 
cent).     [Unpublished  data  from  F.  A.  Geldard.] 

When  careful  measurement  is  undei- 
taken,  it  is  found  that  the  sensitivity  of 
the  temperattne  spots  varies  from  time  to 
time,  even  from  minute  to  minute.  Figure 
186  shows  the  same  area  mapped  twice  for 
the  location  of  cold  spots  with  the  stimulus 
at  17°  C  and  with  an  interval  of  5  minutes 
between  the  mappings.  The  agreement  is 
good  (about  88  per  cent)  but  not  perfect, 
in  spite  of  the  fact  that  great  care  was 
taken  to  keep  conditions  the  same.  It  is 
probable  that  the  sensitivity  of  some  of  the 
spots  has  decreased  in  this  short  interval. 
On  the  other  hand,  it  is  possible  to  identify 
and  mark  especially  sensitive  temperature 
spots,     finding     that     llicy     respond     witli 


warmth  or  cold,  as  the  case  may  be,  when- 
ever stimulated  o\cr  a  period  of  )cars. 

Skin  Temperature 

At  least  a  part  of  the  apparent  instabil- 
ity of  warm  and  cold  spots  can  be  explained 
by  reference  to  the  temperature  shifts 
within  the  skin  itself.  The  cutaneous  tis- 
sites  are  constantly  undergoing  thermal 
changes.  Some  of  the  changes  residt  from 
heat  radiation  and  the  evaporation  of  mois- 
ture from  the  epidermis.  The  cliief  fac- 
tor, however,  is  dilation  and  contraction  of 
blood  vessels  in  the  corium  and  stibcuta- 
neous  tissue.  A  vast  number  of  influences 
can,  by  reflex  ner\ous  action,  create 
changes  in  the  size  of  cutaneous  blood  ^es- 
sels.  With  dilation  comes  a  larger  blood 
flow  and  warming  of  stirrounding  tissues; 
with  contraction  there  is  a  reduction  of 
heat  supply.  Thus,  with  heat  interchanges 
occurring  at  the  site  of  nerve  stimulation, 
it  is  not  sin-prising  that  some  of  the  less 
favorably  disposed  receptors  are  at  times 
influenced,  at  others  uninfluenced,  by  a 
small  metal  point  set  down  on  the  skin 
surface. 

The  amount  of  heat  delivered  to  or  car- 
ried away  from  the  skin  by  a  thermal 
stimulator  is  not  great.  The  epidermis  is 
a  good  insulator.  In  experiments  in  which 
sensitive  thermocouples  have  been  em- 
bedded in  the  skin,  it  has  been  shown  that 
a  relatively  large  stimulus,  10°  C  above 
skin  temperature  and  applied  for  6  sec- 
onds, raised  the  local  siuface  temperature 
only  5°  C  and  the  tissue  1  millimeter  be- 
low the  surface  only  2°  C.  A  large  cold 
stimulus,  14°  C  below  skin  temperature, 
lowered  surface  and  deep  temperatures  by 
corresponding  amounts.  The  changes  pro- 
duced by  a  metal  point  of  the  size  ordi- 
narilv  used  in  exploration,  particidarjy 
with   momentary   application,   must   reprc- 


Thermal  Sensibilify 


369 


scnl     only    vciy    .small     liiuiions    ol    these 
values. 

U'he  net  results  of  all  the  eomplcx  thet- 
mal  adjustments  being  made  unceasingly 
in  the  skin  is  that  the  body  surface  is  nor- 
mally held  in  quite  stable  heat  equilib- 
rium with  its  immediate  environment. 
Over  the  clothed  areas  skin  temperature 
remains  at  about  35°  C,  on  the  exposed 
hands  and  face  it  is  about  33°,  and  under 
the  tongue  it  is  37°  (98.6°  F).  The  tem- 
perature of  the  ear  lobe,  where  blood  (low 
is  sluggish,  may,  however,  be  as  low  as 
26°  C. 

Physiological  Zero  and  Adaptation 

The  temperature  to  which  a  given  skin 
region  is  thermally  indifferent,  that  is  to 
say,  will  respond  with  neither  the  sensa- 
tion of  cold  nor  of  warm,  is  called  its 
physiological  zero.  Thus  plunging  a  hand 
into  water  at  the  temperature  of  its  skin 
(33°  C)  normally  produces  neither  a  feel- 
ing of  warm  nor  of  cold.  But  let  the  hand 
previously  be  exposed  to  40°,  and  the  33° 
water  seems  distinctly  cold.  Similarly, 
previous  exposure  to  20°  will  render  the 
water  at  33°  decidedly  warm.  Physiologi- 
cal zero  has  shifted,  in  each  instance,  as  a 
result  of  adaptation. 

The  phenomenon  of  thermal  adaptation 
is  familiar  enough.  Dive  into  a  pool,  and 
the  cold  may  at  first  be  breath-taking.  Re- 
main there,  and  the  water  may  eventually 
be  only  pleasantly  cool.  Continued  stimu- 
lation has  lowered  sensitivity  and  has 
brought  physiological  zero  closer  to  the 
temperature  of  the  stimulus.  Complete 
thermal  adaptation,  reduction  of  the  sensa- 
tion of  warm  or  cold  to  the  zone  of  thermal 
indifference,  occurs  only  within  a  restricted 
range  of  temperatures.  For  the  hands  the 
limits  are,  roughly,  17°  C  for  cold  and 
40°  C  for  Avarm.     Temperatures  below  or 


abf>ve  these  pf>ints  srein  not  to  undergo 
complete  adaptation  but  to  (oniiriue  to 
give  rise  to  cold  or  warmth.  I  he  more 
extreme  the  temperature,  the  longer  the 
time  required  for  adaptation. 

The  fact  that  physiological  zero  can  be 
moved  by  adaptation  and  the  related  fact 
that  both  warm  and  cold  sensitivities  are 
simultaneously  affected  are  important  be- 
cause they  suggest  that  either  both  kinds 
of  temperature  sensations  are  mediated  by 
the  same  mechanism,  behaving  in  two  dif- 
ferent ways,  or  the  two  systems  of  sensi- 
tivity, if  they  are  separate,  have  certain 
operating  characteristics  in  common. 

Paradoxical  Cold  and  'Heat' 

Two  phenomena  occurring  in  the  realm 
of  temperatine  sensitivity  are  remarkable 
and  of  considerable  theoretical  importance. 
One  of  them  concerns  the  arousal,  by  a 
warm  stimulus,  of  the  sensation  of  cold. 
If  a  number  of  spots  especially  sensitive 
to  cold  are  located,  then  are  gone  o\er 
with  a  very  warm  stimulus  (43°  C  or 
higher),  a  certain  number  of  them  are 
likely  to  respond  with  their  own  proper 
sensation,  cold.  Since  it  seems  paradoxi- 
cal that  a  hot  stimulus  should  arouse  cold, 
this  phenomenon  has  received  the  desig- 
nation paradoxical  cold.  The  theoretical 
significance  of  paradoxical  cold  lies  in  its 
support  of  the  view  that  both  cold  and 
Avarm  sensations  involve  their  own  specific 
receptors  and  nerve  paths. 

The  other  phenomenon  has  to  do  widi 
a  complex  perception,  usually  called  heat. 
The  condition  necessary  for  its  arousal  is 
the  simultaneous  stimulation,  within  a 
given  area,  of  both  the  warm  and  the  cold 
mechanisms.  This  can  be  accomplished 
by  the  use  of  the  'heat  grill, '  a  device  con- 
sisting of  parallel  metal  or  glass  tubes  on 
Avhich  the  forearm  or  some  other  brciad  skin 


370 


Somesthesis 


surface  is  rested.  Cold  water  (about  15°  C) 
runs  through  the  even-numbered  tubes; 
warm  water  (about  44°  C)  flows  through 
the  odd  ones.  There  is  nothing  about 
either  stimulus  which  would  lead  us  to 
expect  that  the  total  pattern  would  be 
'hot,'  yet  when  the  arm  is  placed  on  the 
giill  the  experience  is  uncomfortable  and 
there  is  a  strong  tendency  to  pull  it  away. 
The  experience  is  very  similar  to  the  feel- 
ing aroused  by  a  large,  hot  object  contact- 
ing the  skin.  There  the  receptor  process 
is  perhaps  the  same,  warm  spots  giving 
their  normal  response,  while  cold  spots 
are  simultaneously  and  paradoxically 
aroused  to  action. 

Receptors  for  Temperature 

If  uncertainty  exists  about  the  receptor 
organs  responsible  for  pressure  and  pain, 
there  is  still  more  concerning  those  for 
warm  and  cold  sensations.  It  has  been 
seen  that  some  facts  point  to  a  common 
mechanism  for  both  kinds  of  thermal  sen- 
sitivity while  others  seem  to  demand  sepa- 
rate processes  for  the  two. 

A  currently  debated  theory  is  that  nerve 
endings  in  the  walls  of  tiny  blood  vessels 
of  the  corium,  the  arterioles,  mediate  both 
warm  and  cold.  When  a  warm  stimulus 
is  applied  to  the  skin  a  local  dilation  of 
arterioles  is  produced,  so  this  theory  as- 
serts that  the  nerve  discharges  created  by 
relaxation  of  this  smooth  muscle  tissue  is 
the  basis  of  the  warm  sensation.  A  cold 
stimulus  causes  the  arterioles  to  contract, 
and  this,  it  is  said,  sets  up  a  pattern  of 
discharge  which  eventuates  in  the  cold 
sensatiop.  The  chief  advantage  of  this 
neurovascular  theory  of  temperature  sensi- 
tivity is  that  it  provides  a  ready  interpre- 
tation of  the  facts  of  adaptation  and  shift- 
ing of  the  physiologiral  zero.  F "he  innc- 
lialnlily   of   spot   mapping   would   also   be 


expected  if  nerve  endings  in  the  walls  of 
the  unstable  blood  vessels  are  responsible 
for   temperature   sensitivity. 

The  classic  view  is  that  two  separate 
mechanisms  are  involved.  Because  they 
seem  to  lie  at  about  the  right  depths  in 
the  cutaneous  tissues  to  account  for  the 
time  relations  in  thermal  stimulation,  it 
has  been  supposed  that  cold  is  mediated 
by  Krause  end  bulbs,  specialized  nerve 
endings  found  in  the  upper  portion  of  the 
corium,  and  that  warm  is  cared  for  by 
Ruffini  cylinders,  sensory  nerve  termina- 
tions located  considerably  deeper  in  the 
corium  and  subcutaneous  tissue.  The  quick 
arousal  of  cold  and  the  relatively  slow 
response  of  warm  accord  well  with  this 
guess. 

We  should  suppose  that  a  direct  solu- 
tion of  the  problem  would  be  jjossible  by 
mapping  sensitivity  in  a  given  skin  region, 
then  excising  the  tissue  and  subjecting  it 
for  microscopical  examination.  Such  ex- 
periments have  been  made  a  number  of 
times,  and  the  results  have  been,  in  gen- 
eral, disappointing.  In  one  such  attempt 
both  warm  and  cold  spots  were  carefully 
mapped  and  remapped.  When  the  tissue 
was  cut  out  and  examined,  not  a  single 
specialized  nerve  ending  was  foimd  to  be 
present;  only  free  nerve  endings  appeared 
in  the  tissue  sections.  In  general,  the 
results  are  not  such  as  to  give  any  confi- 
dence in  the  conclusion  that  the  receptors 
for  warm  and  cold  can  be  discovered  in 
this  simple  and  direct  fashion. 

KINESTHESIS 

All  the  structures  involved  in  bodily 
movements— muscles,  their  attached  ten- 
dons and  the  articulations  between  bones 
—arc  well  supplied  with  sensory  nerves, 
and   they   originate   patterns   of  sensation. 


Kinesthesis 


371 


KineslJiesis  ('feeling  of  motion')  is  ihe 
name  given  to  these  patterns.  By  its  aid 
we  aie  able,  without  the  help  of  vision,  to 
(arry  on  complicated  activities  calling  for 
considerable  nicety  of  muscular  adjust- 
ment or  to  judge  accurately  the  positions 
of  limbs. 

The  relative  contribution  made  by  sen- 
sations  from   muscles,    tendons   and   joints 


that  correct  judgments  of  limb  position 
are  impossible.  That  muscle,  by  itself, 
has  a  sensory  contribution  to  make  is  shown 
by  the  fact  that  movements  of  the  tongue 
can  be  appreciated.  Fine  discrimination 
of  tongue  movements,  however,  is  not 
possible  kinesthetically,  as  may  be  amply 
demonstrated  by  noting,  in  a  mirror,  the 
discrepancy  between  what  is  seen  and  wliat 


Muscular  fibers 


FIGURE    187.       KINF.STHKTIC    RECEPTORS    IN    TENDON 


Freely  branching  sensory   fibers  with   specialized    terminations,  the  so-called  Organ  of  Golgi,  found   in 
tendinous   tissue.      [From  J.   D.   Lickley,   The   nervous  system,  Longmans,  Green,   1931,  p.   132.1 


is  not  easy  to  assess  by  simply  observing 
their  'feel'  while  making  a  limb  move- 
ment. The  patterns  are  massive  and  dif- 
fuse, and  their  exact  localization  is  diffi- 
cult. Abnormalities,  however,  provide  a 
fairly  conclusive  answer.  In  certain  rare 
nerve  afflictions  joint  sensibility  may  be 
retained  while  sensations  originating  in 
muscles  and  their  attachments,  as  well  as 
those  from  the  overlying  skin,  are  abol- 
ished. In  such  cases  the  appreciation  of 
posture  and  movement  is  very  little  af- 
fected, indicating  that  the  joints  play  the 
major  role  in  this  capacity.  Confirmation 
of  this  conclusion  comes  from  pathological 
cases  of  the  opposite  variety.  In  a  bone 
disease  which  destroys  joint  sensibility 
without  disturbing  the  sensibility  of  mus- 
cles and  tendons,  it  has  been  demonstrated 


is  felt  when  the  tongue  is  moved  about  the 
open  mouth  without  touching  the  cheeks 
or  lips.  Sensations  originating  in  tendinous 
tissue  apparently  make  their  chief  contri- 
bution when  heavy  weights  are  supported 
or  during  extreme  exertion.  Then  feelings 
of  strain,  even  ache,  appear. 

Kinesthetic  sensibility  may  be  tested  by 
mechanically  moving  a  finger,  toe  or  limb 
and  measuring  either  the  minimal  observ- 
able rate  of  motion  or  the  smallest  angular 
displacement  that  can  be  detected.  Sur- 
prisingly high  sensitivity  is  found.  The 
thresholds  for  the  displacement  of  differ- 
ent joints  vary  between  0.2  and  0.7  de- 
gree. The  lower  value  is  for  the  shoulder. 
When  measured  by  minimal  rate  of  move- 
ment, again  the  shoulder  proves  to  be  the 
most  sensitive  joint. 


372 


Somesthesis 


Kinesthetic  Receptors 

The  probable  nerve  endings  for  kines- 
thesis  have  been  described  fairly  inti- 
mately. Whereas  sensory  nerves  appar- 
ently do  not  terminate  directly  at  the  joint 
surfaces,  large  ner\e  endings  known  as 
Pacinian  corpuscles  are  obser\ed  in  the 
ligaments  of  joints  and  in  the  bone  cov- 
ering near  joints.  Free  nerve  endings  are 
also  found  in  these  regions.  Embedded  in 
tendinous  tissue  are  so-called  Golgi  spin- 
dles, specialized  portions  of  the  tendon 
containing  several  sensory  nerve  fibers  each 
terminating  in  freely  branching,  club- 
shaped  enlargements  (Fig.  187).  They 
seem  admirably  located  and  adapted  to 
respond  to  changes  of  tension.  The  fleshy 
parts  of  nearly  all  skeletal  muscles  are 
supplied  with  special  structures,  a  few  mil- 
limeters long  and  definitely  known  to  be 
sensory  in  function,  called  muscle  spindles. 
These  spindles  are  complex  in  their  nerve 
supply,  at  least  three  different  forms  of 
terminations  being  found  in  them.  Two 
types  signal  stretching,  not  contraction,  of 
the  muscle,  whereas  the  third  responds  to 
varying  states  of  tension.  The  muscle 
spindle  would  seem  to  be  best  adapted  to 
providing  information  about  cessation  of 
muscle  activity.  Perhaps  this  is  why  recog- 
nition of  posture  and  movement  depends 
so  much  on  the  joints. 

ORGANIC    SENSIBILITY 

.As  compared  with  the  skin  the  deep- 
lying  internal  organs,  even  those  of  the 
alimentary  canal,  are  very  insensitive  struc- 
tures. Surgeons  have  long  known  that,  in 
the  absence  of  anesthetics,  intestines  may  be 
cut,  squeezed,  scraped  or  even  cauterized 
without  so  much  as  producing  discomfort. 
Are  visceral  organs,  then,  normally  anes- 
thetic? 


Experimentation  provides  a  different  an- 
swer. By  means  of  stomach  tubes  and  al- 
lied equipment  it  has  been  possible  to  estab- 
lish the  fact  that  the  stomach  and  esophagus 
are  sensitive  to  both  warmth  and  cold. 
Internal  distension  of  these  organs,  pro- 
duced by  inflating  a  balloon,  may  result 
in  massive  and  vaguely  localized  feelings 
of  pressure  or,  if  the  distension  is  rapid 
enough,  pain.  All  visceral  organs,  in- 
deed, seem  capable  of  yielding  pain  if 
stretching  of  their  walls  is  sufficiently  rapid 
or  extensive.  Gas  pains  and  cramps  are 
conunon  testimony  to  visceral  sensitivity. 
Sensations  from  the  deep  organs  have  their 
own  modes  of  arousal;  large  distending 
pressures  are  usually  involved  when  pres- 
sure or  pain  is  felt. 

Hunger  and  Appetite 

In  view  of  the  generally  low  level  of  sensi- 
tivity displayed  by  visceral  organs,  it  may 
seem  surprising  that  the  unpleasant,  gnaw- 
ing pangs  called  hunger  have  their  origin  in 
local  activity  of  one  of  them.  Nevertheless 
the  facts  are  clear.  The  hunger  sensation 
has  been  definitely  shown  to  come  from 
strong  contractions  of  the  musculature  of 
the  stomach  wall  and  thus  to  constitute  a 
kinesthetic  pattern.  Figure  188  illustrates 
the  recording  of  hunger  pangs.  A  subject, 
habituated  in  advance  to  the  presence  of  a 
balloon  in  his  stomach  and  a  rubber  tube 
down  his  throat,  presses  a  key  whenever  he 
feels  the  hunger  pangs.  His  reports  are 
seen  to  coincide  with  the  occurrence  of  the 
strongest  stomach  contractions.  \Vhile 
considerable  activity  of  the  stomach  walls 
is  going  on  between  pangs,  these  mo^•e- 
ments  are  unknown  to  the  subject  through 
direct  observation.  Only  the  intense  peaks 
of  contraction,  occurring  evei")'  half  min- 
ute or  so,  create  sensations  which  get  or- 


Hunger  and  Appetite 


373 


ganizcd   into  a  (onscious  .soincsilictic   pat- 
tern. 

A  clear  distinction  nuist  be  made  be- 
tween the  hunger  pangs,  which  constitute 
a  definite  sensory  experience,  and  hunger- 
as-appetile,  which  is  the  desire  to  eat  and 


meals  vvfMild  bcfome  \(.ry  Ijriei  affairs,  fjiit 
liunger-as-appctitc  carries  on  after  the 
liunf^er  pangs  have  lapsed.  Even  non- 
nutritive  and  indigestible  substances- 
pieces  of  leather,  bits  of  moss  or  clay— will 
temporarily  allay  these  pangs.     Hard  swal- 


RECORDING    OF    HUNGER    CONTRACTIONS 


The  subject  records,  by  a  magnetic  marker  on  line  D,  the  occurrence  of  hunger  pangs,  while  the  un- 
dulating record,  A,  shows  the  state  of  the  muscular  activity  of  his  stomach.  Time  is  marked  otf  on  line 
C.  £  is  a  breathing  record,  taken  for  control  purposes.  Note  correspondences  between  D  and  A.  [From 
W.  B.  Cannon,  in  Handbook  of  general  experimental  psychology,  Clark  University  Press,  1934,  p.  250.] 


does  not  necessarily  have  any  special  sens- 
ory form.  When  you  have  the  hunger 
pangs,  you  want  to  eat;  that  is  true.  On 
the  other  hatid,  you  may  also  want  to  eat 
when  you  do  not  have  the  pangs,  and  then 
all  the  sensation  you  have  is  the  kinesthesis 
of  wanting  to  get  hold  of  food  when  you  see 
it.  It  is  hunger-as-appetite  that  makes  you 
eat  desserts— all  desserts,  for  the  hunger 
contractions  of  the  stomach  and  thus  the 
hunger  pangs  are  stopped  by  ingesting  the 
food  which  precedes  a  dessert.  If  eating 
were  entirely  a  matter  of  satisfying  hunger. 


lowing  or  tightening  the  belt  Avill  do  die 
same.  Emotion  is  a  very  effective  inhibitor 
of  the  hunger  contractions  and  pangs.  But 
appetite  is  the  motivation  that  lasts  when 
the  pangs  are  gone.  In  modern  civiliza- 
tion hunger  pangs  have  become  increas- 
ingly rare,  but  they  are  common  enough  in 
China  and  were  too  well  known  in  Eirrope 
during  and  after  the  Second  AVorld  War. 

The  psychologists  use  the  A\ord  hunger 
both  for  the  sensory  ]:)attern  of  the  pangs 
and  for  the  motive  that  makes  animals  eat 
wheti  they  have  been  depri\  ed  of  food  (pp. 


374 


Somesthesis 


1 15  f.).  It  is,  therefore,  important  to  remem- 
ber this  difference  between  appetite  and 
Ininger  pangs. 

Thirst 

The  chief  source  of  thirst  is  not  difficult 
to  find.  Direct  observation  tells  us  that 
thirst  is  primarily  referred  to  the  mouth 
and  throat;  a  state  of  intense  thirst  consists 
in  a  very  unpleasant  dryness  of  the  mouth 
cavity.  Experiment  confirms  obsei'vation 
and  demonstrates  further  that  thirst  arises 
whenever  the  mucous  lining  of  the  mouth 
and  pharynx  becomes  dehydrated  through 
a  failure  of  the  salivary  glands  to  provide 
these  tissues  with  a  normal  amount  of  mois- 
ture. Thirst  may  be  induced  by  bodily 
changes  quite  remote  from  the  mouth,  as  in 
the  general  drying  out  of  tissues  due  to 
excessive  perspiration  or  in  the  dehydra- 
tions of  diabetes  and  certain  kidney  dis- 
orders. In  such  instances,  however,  it  can 
be  shown  that  there  is  also  a  reduction  in 
salivary  output  and  that  the  thirst  is  really 
of  local,  rather  than  of  general,  origin. 
Moreover,  with  full  retention  of  body 
fluids,  it  is  possible  to  create  an  intense 
thirst  by  subcutaneous  injection  of  atro- 
pine, one  of  the  first  effects  of  which  is 
greatly  to  interfere  with  output  of  saliva. 
Dryness  of  mouth  tissues  through  salivary 
deficiency  seems  clearly  to  be  the  basis 
of  the  organic  pattern  we  call  thirst. 

Thirst,  this  sensory  perception  of  dry- 
ness of  the  movul),  normally  acts  as  the  first 
term  in  the  stimulus-response  pattern  for 
satisfying  the  body's  need  for  water.  Thirst, 
like  hunger,  is  a  perception  that  acts  as  a 
motive. 

EQUILIBRIUM 

The  cochlea  is  part  of  the  labyrinth  of 
the  inner  ear.     It  functions  in  hearing,  as 


we  have  already  seen  (pp.  331-336;  see 
Fig.  158,  p.  328).  The  other  divisions  of 
the  complexly  formed  labyrinth— the  semi- 
circular canals,  the  utricle  and  the  saccule 
—are  concerned  with  equilibrium  of  the 
body.     (See  Fig.  189.) 

In  the  functioning  of  tlie  nonauditory 
labyrinth  we  are  dealing  with  a  system  of 
sensibility  which,  ciuiously  enough,  yields 
no  direct  sensations.  Unlike  the  cochlear 
branch  of  the  so-called  auditory  nerve, 
those  branches  supplying  the  remaining 
parts  of  the  labyrinth  do  not  have  direct 
pathways  to  the  cerebral  cortex  but,  in- 
stead, make  numerous  connections  at  lower 
brain  levels  with  outgoing  fibers  to  striped 
muscles  of  the  eyes,  neck,  limbs  and  trunk 
and  also  with  fibers  to  smooth  muscles  of 
the  viscera.  The  nonauditory  labyrinth 
is  thus  the  point  of  initiation  of  a  vast 
array  of  proprioceptive  reflexes,  most  of 
them  concerned  with  the  preservation  of 
body  equilibrium  or  with  the  making  of 
new  postural  adjustments  when  equilib- 
rium is  upset. 

There  are,  of  course,  consequences  for 
sensation  in  all  these  changes,  since  kines- 
thetic, cutaneous  and  organic  patterns  are 
necessarily  aroused  by  such  widespread  re- 
actions. Unusual  visual  sensations  some- 
times attend  labyrinthine  stimulation  also. 
Objects  'swim'  in  the  visual  field  of  a  dizzy 
person  because  of  a  rapid  involuntary 
jerking  of  his  eyeballs,  a  response  known 
as  nystagmtis.  For  the  most  part,  however, 
labyrinthine  stimulation  sets  up  the  un- 
conscious proprioception  that  aids  in  main- 
taining equilibrium  of  the  body. 

The  Semicircular  Canals 

Each  labyrinth  has  three  highly  special- 
ized branches  called  semicircular  ducts  or 
canals.  The  three  lie  at  approximately 
right  angles  to  each  other,  and  each  is  sym- 


Equilibrium 


375 


FIGURE    189.       INNER    EAR:    SEMICIRCULAR    CANALS    AND    COCHLEA 

Three  .semicircular  canals  willi  oiiler  hone  cut  awav  to  show  nieinhianous  lahviintli,  inchuiinsr  the 
utricle  and  tlie  saccule.  The  cochlea  is  shown  at  the  right.  [.Adapted  from  G.  McHui^li.  in  S.  1..  I'olsak, 
The  human  ear,  Sonotone  Corporation,   1916.] 


metrically  paired  in  position  with  one  on 
ihe  opposite  side  ol'  the  head.  Figure  190 
shows  the  spatial  relations  among  the  six 
canals  of  the  two  ears.  When  the  head  is 
inclined  slightly  forward  (about  25  de- 
grees) the  external  canals  are  parallel  with 
the  ground,  the  anterior  canals  point  for- 
ward at  a  45-degree  angle,  and  the  poste- 
rior canals  project  backward  at  the  same 
angle.     It  is  clear  that  the  arrangement  of 


the  canals  in  the  head  provides  a  three- 
dimensional  coordinate  system,  and  move- 
ment of  the  head  will  create,  through  lag. 
a  flow  of  the  watery  fluid  (endolymph)  in 
one  or  more  of  the  canals. 

Each  canal  has  a  bulge  near  one  eml,  an 
ampulla,  within  which  are  to  be  found 
specialized  nerve  endings,  hair  tufts  called 
cristae.  The  hairs  are  embedded  in  a  gelati- 
nous  mass,    the   cupula    (Fig.    191).   which 


376 


Somesthesis 


extends  across  the  ampulla  and  is  bent 
over  in  one  direction  or  the  other,  depend- 
ing on  the  h)draulic  pressure  created  by 
the  flow  of  endolymph.  It  is  this  movement 
of  the  fluid,  producing  bending  of  the 
cupula   and   consequent   distortion   of   the 


Right 

anterior 

canal 


Left  Right^ 

•^posterior      posterior^ 

canal  canal 


FIGURE    190.       POSITIONS    OF    THE    SEMICIRCULAR 
CANALS 

The  right  and  left  sets  of  canals  are  paired:  the 
left  anterior  with  the  right  posterior,  the  right  an- 
terior with  the  left  posterior  and  the  right  external 
with  the  left  external.     [From  \Ven7el.] 

crista,  that  constitutes  the  immediate  stim- 
uhis  for  the  initiation  of  nerve  impulses. 

Since  there  is  a  certain  ainount  of  fric- 
tion between  the  endolymph  and  the  walls 
of  the  canals,  it  follows  that,  in  any  con- 
tinuous movement  of  the  canals,  the  endo- 
lymph will  soon  'catch  up';  then  there  will 
be  no  relative  motion  between  the  fluid 
and  its  containing  walls  and  hence  no 
stimulation.  It  is,  therefore,  only  speed- 
ing up  or  slowing  down  of  the  canals,  that 
is  to  say,  positive  or  negative  acceleration, 
that  constitutes  the  stimulus  for  the  hair 
cells  of  the  crista. 

This  analysis  of  the  action  of  the  semi- 
circular canals  is  borne  out  by  a  variety 
of  experiments.  Spin  a  blindfolded  sub- 
ject in  a  smoothly  rotating  chair,  have 
him  indicate  his  direction  of  motion  by 
raising  the  appropriate  hand,  and  the  fol- 


lowing events  will  ordinarily  occur.  First, 
as  momentum  is  being  gathered  (positive 
acceleration),  the  subject  will  report  the 
correct  direction  of  rotation.  Then,  if 
speed  is  maintained  constant  (canals  and 
endolymph  moving  together),  he  will  drop 
his  hand  and  indicate  that  he  feels  no  mo- 
tion at  all.  If  brakes  are  then  silently  ap- 
plied, quickly  slowing  him  down  (negative 
acceleration),  he  will  raise  his  other  hand. 
He  feels  himself  to  be  rotating  in  the  oppo- 
site direction  (aftersensation).  If,  while 
traveling  at  high  speed,  he  is  stopped 
abruptly,  there  may  be  other  reactions- 
compensatory  movements  of  his  arms,  legs 
and  head,  all  designed  to  prevent  him  from 


FIGURE  igi. 


STRUCTURE  AND   LOCATION    OF 
CRISTAE 


The  hairs,  B,  project  from  their  cells,  C,  into  ihe 
gelatinous  cupula,  A.  The  location  of  the  crista  in 
the  basal  swelling,  or  ainpulla,  of  a  semicircular 
canal   is  shown  in  the  inset,  D. 

falling  over.  If,  after  rapid  and  uniform 
rotation  to  the  left  for  a  dozen  revolutions, 
he  is  required  to  stand  and  hold  his  arms 
out  forward,  he  will  usually  turn  his  head 
and  arms  to  the  left,  his  right  arm  will  go 
up,  his  left  down,  and  he  may  be  in  danger 


Equilibrium 


377 


of   falling   backward   and    to    llic    left.      If  (anals,  mechanical  pressure  on   the  (anals, 

his  head  position  is  then  changed  radically,  hetier   localized  electrical   stirmdation   and 

he  is  sure  to  fall  unless  sujjjjorted.  drugs  applied  near  the  cupula.     Because  in 

The  amount  of  angular  acceleration  ncc-  man   the  labyrinth   is  one  of  the  most  in- 

essary  to  set  the  canals  in  operation  is  not  accessible   of   structures,    the   experimental 

great.     You  perceive  rotation  in  the  hori-  possibilities  are  limited, 
zontal  plane  when  your  body  is  accelerated 

as  little  as  one  degree  per  second.     I'hcre  Receptors  in  the  Sacs 

are  also  other  ways  of  arousing  your  laby-  The    utricle    and    the    saccule,    the    two 

rinthinc  reflexes.    Let  the  external  auditory  structures  continuous  with  each  other  and 


Hairs  of  sensory  cells 


Sensory 


FIGURE     192.    STRUCTURE    OF    THE    MACULA 

In  three-dimensional  cross-section.     [After  W.  Kolmer  (1926).] 


canal  of  your  ear  be  syringed  with  water 
well  above  or  below  body  tempera ttire; 
compensatory  movements  of  your  head  and 
nystagmic  jerking  of  your  eyeballs  will  re- 
sidt.  The  basic  mechanism  is  the  same  as 
in  rotary  moveinents.  Thermal  changes  in 
the  endolymph  create  convection  currents 
which  affect  the  position  of  the  cristae. 
The  vestibular  nerves,  like  all  others,  may 
also  be  stimulated  electrically.  If  a  direct 
current  is  passed  transversely  through  your 
head,  just  back  of  your  ears,  your  head  will 
incline  sharply  to  one  side.  In  animals  ad- 
ditional stimuli  can  be  shown  to  be  effec- 
tive—heat  applied   locally   to   the   exposed 


collectively  called  the  sacs  (Fig.  189),  ha\e 
nerve  temiinations  of  a  different  tvpe,  and 
they  operate  on  a  different  principle.  It  is 
belie\'ed  that  the  semicircidar  canals  are 
stimulated  only  by  motions  involving 
changes  of  direction,  whereas  die  sacs  are 
continuously  responsive  to  straight-line 
iBOtions  and  to  gra\'ity.  The  sacs  must 
have  much  to  do  with  die  maintenance  of 
posture,  though  that  they  are  not  die  sole 
determiners  of  this  important  function  is 
attested  to  by  the  fact  that  many  deaf- 
mutes  who  have  degenerate  vestibular  ap 
paratuses  are  able  to  get  along  quite  "well 
by  stibstituting  visual  and  kinesthetic  clues. 


378 


Somesthesis 


The  nerve  endings  of  the  sacs  are  con- 
tained in  the  maculae  of  these  structures 
(Fig.  192).  They  consist  of  specialized  hair 
terminations  which  have  at  their  ends,  em- 
bedded in  a  gelatinous  mass,  tiny  crystals 
of  calcium  carbonate.  It  is  believed  that 
these  crystals  'load'  the  hair  cells  and  ren- 
der them  susceptible  to  stimulation  by 
gravitational  pull.  Moreover,  as  the  body 
speeds  up  or  slows  down,  the  inertia  of 
the  crystals  causes  the  hair  cells  to  bend  in 
one  direction  or  another,  and  the  resulting 
tensions  to  initiate  impulses  in  the  attached 
nerve  fibers. 

Adaptation  and  Habituation 

It  has  been  noted,  throughout  the  entire 
realm  of  somesthesis,  that  adaptation  is  a 
generally  observed  phenomenon.  The  non- 
auditory  labyrinth  provides  no  exception. 
In  continuous  oscillatory  motion,  which 
keeps  the  cristae  constantly  stimulated,  sen- 
sitivity is  reduced  after  a  time.  Both  the 
perception  of  bodily  movement  and  the 
nystagmic  twitching  of  the  eyes  are  re- 
duced. 

Adaptation  should  not,  however,  be  con- 
fused with  habituation.  Many  of  the  bod- 
ily reactions  initiated  by  the  labyrinth  are 
subject  to  modification  through  central  in- 
fluences with  the  result  that  a  man  may 
learn  to  alter  behavior  in  response  to  a 
given  set  of  rotational  and  gravitational 
forces.  Thus  the  ballet  dancer,  the  whirl- 
ing dervish  and  the  acrobat,  despite  vio- 
lent labyrinthine  stimulation,  make  skill- 
ful muscular  adjustments  and  achieve  equi- 
librium through  substitution  of  visual,  tac- 
tual and  kinesthetic  clues  for  the  usual 
proprioceptive  ones  from  the  labyrinth. 
Sailors  do  the  same  in  acquiring  'sea  legs.' 

Nowhere  is  the  importance  of  habitua- 
tion greater  than  in  learning  to  fly.  The 
high  speeds  and   maneuverabihty  of  mod- 


ern aircraft  place  great  demands  on  the 
ability  of  the  flier  to  disregard  many  direct 
sensations  and  to  learn  to  make  his  stick- 
and-rudder  adjustments  in  accordance  with 
his  instrument  board.  In  the  beginning 
of  a  dive  the  pilot  is  very  light  and,  at  its 
end,  extremely  heavy.  In  evasive  maneu- 
vers his  cristae  and  maculae  prompt  re- 
actions which,  if  blindly  carried  out,  would 
be  disastrous.  The  pilot  must  learn  to 
accept  these  new  and  unusual  forces  as 
normal  to  the  flying  situation  and  make 
suitable  adjustments  in  terms  of  what  he 
knows  and  what  his  instruments  tell  him. 
We  have  come  a  long  way  in  aviation  psy- 
chology since  the  days  of  the  First  World 
War  when,  because  of  the  recognized  im- 
portance of  labyrinthine  mechanisms  in 
flying,  it  was  the  practice  to  select  pilots 
for  their  high  sensitivity  to  gravitational 
and  rotational  changes.  It  is  important  to 
the  flier  to  have  an  intact  labyrinth,  but 
much  more  important  that  he  be  able  to 
learn  to  resist  many  of  the  urges  it  creates. 

REFERENCES 

1.  Boring,  E.  G.  Sensation  and  perception  in  the 
history  of  experimental  psychology.  New  York: 
Appleton-Century,  1942.    Chaps.  13  and  14. 

Chapter  13  is  an  interesting  and  well-docu- 
mented account  of  the  development  of  ideas 
concerning  the  cutaneous  sensibilities,  and 
Chap.  14  performs  a  similar  service  for  the  in- 
ternal sensibilities. 

2.  Cannon,  W.  B.  Hunger  and  thirst.  In  C. 
Murchison  (Ed.),  A  handbook  of  general  ex- 
perimental psychology.  Worcester,  Mass.: 
Clark  University  Press,  1934.     Chap.  5. 

A  brief  but  competent  treatment  of  the 
theories  and  most  decisive  experiments  on  hun- 
ger and  thirst. 

3.  Dusser  de  Barenne,  J.  G.  The  labyrinthine 
and  postural  mechanisms.  In  C.  Murchison 
(Ed.)  .     .4     hntidhnok     nf    grtwrnl    expnimejitnl 


References 


379 


psychology.  Worcester,  Mass.:  C;i;iik  Uiiiversiiy 
Press,    1934.     Chap.   4. 

A  systematic  discussiuti  of  the  reflex  mech- 
anisms involved  in  the  maintenance  of  equi- 
librium and  posture,  with  an  excellent  bibli- 
ography to  19.^.1 

Nafe,  J.  P.  The  pressure,  pain  and  tempera- 
ture senses.  In  C.  Murchison  (Ed.),  A  hand- 
book of  general  experimental  psychology. 
Worcester,  Mass.:  Clark  University  Press,  1934. 
Chap.  20. 


'J  he  cutaneous  tienxibililiex  are  treated  in  a 
Ky.stcmatic  fa.shion,  with  particular  emphasis  on 
the  problem  of  scn.salion-rccepior  coirelation*. 

5.  Ruch,  T.  C.  .Somatic  sensation,  and  Neural 
basis  of  somatic  sensation.  Howell's  textbook 
of  physiology,  Cl.Tth  ed.,  J.  F.  Fulton,  Kd.; 
I'hiladcl()hia:  Saunders,  1916.  C^haps.  16  and 
'7- 

A  dearly  written  and  up-to-date  attouiit  of 
the  nervous  mechanisms  involved  in  MlIaneou^ 
and  internal  sensations. 


CHAPTER 


17 


Topographical  Orientation 


To  be  successful  in  your  daily  business 
you  must  know  where  you  are  going,  and 
your  brain  has  few  more  important  tasks 
than  keeping  you  oriented  in  space.  To 
know  where  you  are  going,  you  must  know 
where  you  are  now,  and  also  know  some- 
thing of  your  immediate  surroundings. 
This  knowledge  of  special  relationship  with 
objects  in  your  environment  is  called  topo- 
graphical orientation.  A  minimum  of  it 
is  reqiured  when  you  move  about  by 
merely  following  a  road,  a  trail  or  a  leader. 
This  type  of  locomotion  is  often  called 
'blind';  its  opposite  is  the  well-oriented  be- 
havior of  a  person  who  knows  where  he 
is  and  where  he  is  heaiding.  So  basically 
true  is  this  statement  in  its  literal  sense 
that  the  term  well  oriented  has  taken  on 
the  familiar  connotation  of  competence  to 
deal  with  social  surroundings. 

THE     TOPOGRAPHICAL     SCHEMA 

Let  us  consider  first  the  simplest  type  of 
topographical  orientation,  finding  the  way 
by  following  a  path.  It  may  be  a  footpath 
on  a  college  campus,  a  city  street,  a  num- 
bered route  on  a  highway  or  a  blazed  trail 
in  a  forest.  At  all  times  you  need  clues 
which  tell  you  how  to  stay  on  the  path; 
and  usually  they  are  obvious— the  edge  of 
the    path    or   street,    the    undergrowth    on 


both  sides  of  the  forest  trail.  If  the  path 
is  well  defined,  it  may  be  sufficient  to  fol- 
low your  nose,  provided  it  was  pointed  in 
the  right  direction  to  begin  with;  yet  most 
paths  have  branches  and  crossings  where 
some  other  procedure  is  reqiured.  Sup- 
pose that  you  are  driving  an  automobile 
and  seeking  a  certain  numbered  highway 
which  you  know  leads  to  your  destination. 
You  may  reach  a  crossroad  which  bears  the 
correct  route  nimiber;  yet  this  clue  is  in- 
sufficient by  itself.  You  must  also  know 
which  way  to  turn.  For  example,  U.  S. 
Route  1  runs  from  Maine  to  Florida  along 
the  Atlantic  coast;  if  you  are  driving  east 
in  Virginia  and  come  to  a  highway  marked 
"Route  1,"  you  must  decide  whether  to 
turn  right  (towards  Miami)  or  left  (towards 
Boston).  Once  this  decision  has  been  made 
correctly  you  need  merely  follow  the  signs. 
Thvis  it  is  clear  that  even  a  simple  path 
cannot  be  followed  blindly  without  some 
idea  of  its  spatial  relationship  to  other  ob- 
jects. In  practice  the  following  of  a 
marked  path  is  supplemented  by  some  sort 
of  mental  map  or  schema  in  which  this 
path  is  perceived  in  spatial  relationship 
to  other  paths  and  places.  In  familiar  sur- 
roundings people  are  usually  quite  un- 
aware that  they  are  using  such  a  schema, 
even  though  they  can  orient  themselves  cor- 
rectly when  placed  in  an  unexpected  part 


This  chapter  was  prepared  by  Donald  R.  Griffin  of  Cornell  University. 

380 


The  Topographical  Schema 


381 


ol  this  lamiliar  territory.  Tlicy  <aii  recall 
the  hinchnarks  and  otlier  topoj^raphical 
clues  in  such  a  well-organ i/cci  reiationshi]) 
to  one  another  that  each  landmark  can  \n: 
related  to  any  one  of  several  others  and 
serve  for  guidance  along  a  variety  of  routes 
of  travel. 

Components  of  the  Schema 

Our  mental  maj)  may  include  all  sorls 
of  memories  of  objects,  once  perceived  as 
"we  moved  about— visual  memories  of  the 
appearance  of  buildings,  trees  or  hills, 
bird's-eye  views  of  buildings,  pathways  or 
streets  and,  in  some  cases,  kinesthetic  or 
auditory  clues.  The  schema  may  also  in- 
volve the  realization  that  certain  places  or 
objects  not  immediately  perceived  lie  in 
the  same  direction  as  other  objects  close  at 
hand  which  we  can  perceive  directly.  We 
may  think  of  the  post  office  as  beyond  a 
seen  window,  or  to  our  right,  or  over  that 
hill  yonder.  Thus  familiar  places  or  parts 
of  our  own  bodies  become  points  of  refer- 
ence for  other  more  distant  objects  or 
places.  London  lies  in  the  same  direction 
as  the  post  office  but  beyond  it;  China  is 
beyond  the  railroad  station.  If  our  schema 
has  been  much  influenced  by  the  use  of 
maps,  it  will  include  the  cardinal  points 
of  the  compass. 

Graphic  Representation  of  the  Schema 

A  map  is,  in  fact,  a  graphic  representa- 
tion of  such  a  schema,  rendered  more  ac- 
curate by  the  techniques  of  surveying. 
The  better  oriented  a  person  is,  the  more 
closely  his  schema  is  likely  to  resemble  a 
map.  For  many  people,  however,  geo- 
graphical accuracy  is  not  necessary  or  even 
important.  A  person  who  does  all  his 
traveling  by  street  car  may  have  a  schema 
built  aroimd  the  street  car  lines.  If  asked 
to  sketch  the  schema,  he  will  simplify  the 


street  car  routes,  presumably  smoothing 
( iirves  into  straight  lines,  and  tending  lo 
sJiow  most  turns  as  right  angles.  His  cus- 
tomary stops  are  likely  to  be  prominent, 
and  other  sections  of  the  line  may  be  tele- 
scoped or  omitted  altogether.  Thus  his 
schema  will  be  quite  distorted  when  com- 
pared with  an  accurate  map,  yet  schemata 
of  this  kind  fit  the  psychological  needs  of 
the  person  who  travels  cjver  fixed  routes. 
They  are  exemplified  by  the  'maps'  in- 
serted in  railroad  timetables,  where  the 
railroad  route  is  usually  made  to  appear 
straight  with  geography  forced  to  conform 
to  it.  The  motivation  behind  the  drawing 
of  railroad  maps  is  partly  a  desire  to  make 
the  route  of  the  particular  railroad  appear 
short  and  direct,  but  the  gross  distortion 
of  geographical  fact  also  serves  a  real  pur- 
pose for  the  traveler,  for  the  railroad  map 
conforms  more  closely  to  the  topographical 
schema  of  the  average  tra\eler  than  the 
geographer's  accurate  maps.  The  tra\eler 
can  turn  this  sort  of  schematic  map  into  a 
mental  schema  more  readily  because  it  is 
already  in  the  right  form.  The  traveler  is 
interested  primarily  in  his  starting  point 
and  destination.  He  has  a  secondary  in- 
terest in  the  stations  along  the  way  and 
cares  little  or  nothing  about  the  twists  and 
turns  of  the  route.  The  railroad  map  and 
the  mental  map  do  not  confuse  him  with 
geographical  information  which  is  of  no 
immediate  concern  to  him. 

Not  only  are  directions  distorted  in  the 
topographical  schemata  of  most  people, 
but  distances  and  the  relative  areas  of 
various  regions  also  reflect  their  impor- 
tance to  the  individual  rather  tlian  geo- 
graphical reality.  This  is  best  illustrated 
by  asking  an  adult  person  who  has  not  for 
some  years  studied  geography  to  draw  a 
map  of  die  United  States.  Almost  invari- 
ablv   the   area   in   which   he   lives   will   be 


382 


Topographical  Orientafion 


The  Topographical  Schema 


383 


drawn  larger  and  in  more  detail  tlian  ilic 
rest  of  the  country.  A  somewhat  facetious 
map  of  this  kind  is  shown  in  Fig.  193;  it 
purports  to  show  a  typical  New  England- 
er's  concept  of  the  United  States,  and  its 
distortions  are  but  little  greater  than  those 
characteristic  of  many  persons'  topograph- 
ical schemata. 

Extension  of  the  Schema 
to  New  Territory 

When  a  person  goes  to  a  strange  place 
he  takes  with  him  parts  of  his  old  schema, 
which  may,  depending  upon  the  circum- 
stances, aid  or  hinder  him  'in  learning  his 
way  about'— in  developing  a  new  schema 
for  the  new  locality  or  in  extending  the 
old  one  to  include  it.  The  old  schema  is 
an  aid  when  it  includes  the  points  of  the 
compass  or  other  geographical  relation- 
ships such  as  the  bearings  of  shorelines, 
rivers  and  mountain  ranges  which  remain 
pertinent  when  the  old  schema  is  extended 
to  include  the  new  area. 

Often,  however,  the  old  schema  does  not 
fit  because  there  were  unnoticed  turns  in 
the  road,  and  hence  the  extension  is  in 
error.  Then  part  at  least  of  the  person's 
schema  conflicts  with  the  realities  of  his 
new  environment.  "When  I  was  in  Wil- 
kinsburg.  Pa.,"  a  psychologist  writes,  "the 
trolleys  for  the  eastern  suburbs  ran  north 
through  the  town,  but  the  east-bound 
trains  ran  south  through  the  town.  I  ar- 
rived on  the  train  and,  of  course,  took  the 
trolley  going  the  wrong  way  to  get  to  the 
west.  My  frame  of  reference  was  in  con- 
flict all  that  summer." 

In  learning  a  new  schema,  one  may  be 
led  astray  by  the  assumed  directions  of 
street  or  paths.  If  the  assumption  is  wrong 
and  the  road,  instead  of  being  straight, 
runs  at  an  angle  or  bends  in  its  course, 
and   if   these   deviations   are    not   noticed. 


the  topographical  orientation  becomes  ut- 
terly confused.  The  Boston  CJommon  is 
surrounded  by  five  streets  which  make  ap 
proximately  right  angles  with  each  other. 
Some  of  the  streets  are  bowed  inward 
enough  to  make  this  circumstance  possible, 
but  the  stranger  rarely  notices  the  bends. 
Hence  those  who  take  the  Common  as  a 
point  of  reference  may  often  he  ninety  de- 
grees out  of  reckoning. 

What  we  call  a  'sense  of  direction'  is  a 
skill  at  retaining  orientation  or  expanding 
the  topographical  schema  sufficiently  to 
keep  it  up  to  date  as  we  travel  about. 
People  vary  greatly  in  this  ability,  which 
depends  upon  the  rapid  and  accurate  as- 
similation of  new  scenes  into  the  schema. 
Like  any  type  of  learning,  its  perfection 
depends  partly  upon  practice  and  partiv 
upon  motivation  and  attention.  It  is  com- 
mon experience  that,  in  a  strange  city,  we 
remain  much  better  oriented  if  we  find 
our  own  way  about  than  if  we  cover  the 
same  ground  in  the  company  of  a  local 
inhabitant  who  leads  the  way.  Active  par- 
ticipation demands  attention  and  facili- 
tates learning  (pp.  159-161). 

Nonvisual  Clues 

We  may  use  a  topographical  schema  to 
find  our  way  about  even  when  the  land- 
marks must  be  perceived  through  a  differ- 
ent sensory  modality  from  the  one  when 
they  were  first  encountered.  Often  the 
landmarks  are  first  learned  as  visual  clues 
and  later  felt  by  means  of  other  senses.  .A 
familiar  instance  of  this  is  our  ability  to 
walk  about  in  our  own  homes  in  the  dark. 
We  are  likely  to  kno^v,  without  conscious 
effort  or  counting,  such  topogiaphical  rela- 
tionships as  three  steps  from  the  bed  and  it 
is  time  to  reach  for  the  knob  on  the  bed- 
room door,  six  more  steps  to  the  left  brings 
us  to  the  stairs,  after  four  steps  doA\*n  we 


384 


Topographical  Orienfaiion 


reach  a  landing  and  must  turn  right  be- 
fore continuing  down  ten  more  steps  to  the 
downstairs  hall.  (Perhaps  the  ten  steps 
have  to  be  counted,  but  the  others  usually 
can  be  perceived  correctly  without  enumer- 
ation.) All  this  information  gets  organized 
into  so  coherent  a  topographical  schema 
that  a  man  can  walk  safely  anywhere  in  his 
own  house  in  pitch  darkness  even  though 
he  is  nearly  or  quite  asleep.  In  such  case 
the  mental  schema  was  probably  first 
erected  on  the  basis  of  visual  clues,  but  in 
the  dark  it  gets  transferred  to  substitute 
senses.  We  can  recognize  the  round  door 
knob,  the  hard  hall  floor  and  the  mount- 
ing staii^s  by  the  somesthesis  of  hands  or 
feet,  the  somesthesis  of  what  it  is  like  to 
take  six  steps.  Hearing  may  also  provide 
clues.  The  sounds  of  walking  on  a  carpet 
and  on  a  bare  floor  are  different.  We 
never  have  an  auditory  map,  but  Ave  can 
have  a  kinesthetic  one,  the  feel  of  how  it 
is  to  cover  the  whole  route;  and  we  may 
have,  not  a  verbal  map,  but  a  verbal  guide 
by  which  we  instruct  ourselves  how  to  go. 
In  other  words,  the  equipment  of  imagery 
that  we  use  in  other  kinds  of  thinking  is 
available  for  use  in  mental  map  making. 

SENSORY  BASIS  OF 
ORI  ENTATION 

Thus  far  we  have  outlined  the  mental 
processes  invohed  in  organizing  into  a  men- 
tal schema  certain  sensory  data  which  consti- 
tute topographical  landmarks.  Usually  the 
schema  is  visual,  the  landmarks  are  carried 
as  visual  imagery.  The  real  problem  in 
building  up  a  mental  map  is  to  select  froin 
a  multitude  of  available  visual  impressions 
the  few  appropriate  ones  which  can  easily 
be  remembered  and  ser\'e  as  landmarks. 
There  are,  however,  some  situations  where 
visual  clues  are  lacking  and  successfid  ori- 


entation is  nevertheless  quite  possible,  and 
to  such  cases  we  may  now  turn  our  atten- 
tion. 

Orientation  by  the  Blind 

Consider  the  difficulties  and  dangers  of 
traveling  through  a  strange  city  when 
tightly  blindfolded.  At  first  thought  such 
action  seems  impossible,  and  yet  some  blind 
people  do  it  as  a  part  of  everyday  life.  Not 
all  totally  blind  people  can  move  freely 
about  without  the  guidance  of  human 
friends  or  'seeing-eye'  dogs,  but  a  few 
skilled  and  experienced  members  of  that 
handicapped  group  can  do  so  with  aston- 
ishing precision.  These  blind  men  and 
women  can  walk  about  indoors  without 
striking  furniture  or  other  obstacles,  find 
doors,  negotiate  stairways  and  perform 
numerous  other  feats  of  orientation  and 
obstacle  avoidance  which  are  quite  be- 
yond the  ability  of  the  newly  blind  and 
of  sighted  persons  who  are  blindfolded. 

A  blind  man  who  possessed  this  ability 
to  a  high  degree  has  written:  "^Vhether 
within  a  house  or  in  the  open  air,  whether 
walking  or  standing  still,  I  can  tell,  al- 
though quite  blind,  when  I  am  opposite 
an  object  and  can  perceive  whether  it  be 
tall  or  short,  slender  or  bulky.  I  can  also 
detect  whether  it  be  a  solitary  object  or 
a  continuous  fence,  whether  it  be  a  closed 
fence  or  composed  of  open  rails;  and  often 
whether  it  be  a  wooden  fence,  a  brick  or 
stone  wall  or  a  thickset  hedge." 

What  sensory  clues  can  enable  a  totally 
blind  man  to  perceive  such  details  when  he 
is  still  at  a  distance  of  many  feet  from  the 
objects  which  he  is  describing?  Of  the 
several  explanations  which  have  been  ad- 
vanced, two  principal  theories  have  gener- 
ally been  considered  more  plausible  than 
a  variety  of  other,  semimystical  explana- 
tions which  postulate  the  development  of  a 


Orienfafion  of  ihe  Blind 


385 


'sixth  sense'  in  the  l)Iin(l  or  their  depend- 
ence on  ill-defined  'waves  in  the  ether'  oi 
even  telepathy.  The  first  of  these  two 
theories  holds  that  the  cutaneous  senses  of 
touch  and  temperature  arc  developed  to  a 
keenness  sufficient  to  enable  the  blind  man 
to  feel  air  currents  as  they  are  influenced 
by  the  proxiiuity  of  obstacles.  Ihe  face 
was  believed  to  be  the  seat  of  this  highly 
developed  cutaneous  sensitivity,  and  for 
this  reason  the  term  facial  vision  has  been 
applied  to  the  ability  of  the  blind  to  per- 
ceive objects  at  a  distance.  Until  very  re- 
cently this  theory  of  a  facial  cutaneous  sen- 
sitivity was  generally,  though  tentatively, 
accepted  by  most  psychologists.  It  was  sup- 
ported by  the  reports  of  many  gifted  blind 
men  that,  when  they  approached  obstacles, 
they  felt  cutaneous  sensations  on  their  faces, 
especially  their  foreheads. 

Auditory  Perception  of  Obstacles 

The  sense  of  liearing,  however,  has  ap- 
pealed to  some  psycliologists  as  a  more 
probable  basis  for  the  obstacle  perception 
of  the  blind.  Their  opinions  were  based 
on  experiments  in  which  blind  men  lost 
mucli  of  their  skill  if  their  ears  were  cov- 
ered. Since  men  can  localize  quite  accu- 
rately the  source  of  a  sound,  it  seems  pos- 
sible that  objects  are  detected  at  a  distance 
by  means  of  their  effects  on  the  total  sound 
field  perceived  by  the  blind  man.  Many 
psychologists  have  believed,  however,  that 
a  combination  of  cutaneous  and  auditory 
clues  enables  the  blind  to  perceive  obstacles 
at  a  distance. 

Recent  results  have  sliown  conclusively 
that  the  auditory  theory  is  in  the  main  cor- 
rect. Blind  men,  as  well  as  some  blind- 
folded seeing  persons  who  learned  with 
practice  to  duplicate  some  of  the  feats  of 
the  blind,  lost  virtually  all  their  ability 
when  their  ears  were  tightly  stopped.    This 


shovv(-(l  t)i;ii  (  niaiK.-ous  receptors  by  them- 
selves were  not  sufficient  for  obstacle  per- 
ception. The  entire  skin,  furthermore, 
could  be  (overed  by  heavy  felt  and  similar 
materials  witfiout  any  impairment  of  tfic 
ability  to  detect  obstacles  before  collision, 
provided  that  small  openings  were  left  over 
the  ears.  Thus  the  ears  were  shown  to  fjc 
both  necessary  and  sufficient  for  the  detec- 
tion of  obstacles.  Finally,  it  was  demon- 
strated tliat  the  ability  could  be  retained 
when  the  judgment  of  proximity  to  an  ofj- 
stacle  was  based  entirely  on  auditory  clues 
transmitted  fjy  telephone. 

In  this  crucial  experiment  one  experi- 
menter walked  toward  an  obstruction  carry- 
ing a  microphone,  while  the  subject— a 
blind  man  or  someone  else  playing  the 
blind  man's  role— sat  in  an  isolated  room 
listening  with  headphones  to  the  sounds 
which  the  microphone  picked  up  as  it  was 
carried  toward  the  obstacle.  The  subject 
with  headphones  coidd  detect  the  proxim- 
ity of  solid  objects  and  signal  to  the  carrier 
of  the  microphone  when  to  stop  within  a 
few  inches  of  the  obstacle.  To  rule  out 
any  possible  clues  being  gi\'en  by  the  car- 
rier of  the  microphone,  another  group  of 
tests  was  conducted  with  the  microphone 
carried  not  by  a  man  but  on  a  carriage 
moved  by  electric  motor  toward  the  ob- 
stacle and  remotely  controlled  by  the  sub- 
ject in  another  room.  Both  blind  and 
sighted  subjects  could  with  practice  bring 
the  carriage  close  to  the  movable  obstacle 
and  stop  it  just  before  collision,  even 
though  at  the  start  of  a  trial  they  did  not 
know  how  far  from  the  carriage  the  ob- 
stacle lay.  Thus  the  entire  operation  of 
approaching  the  obstacle  and  stopping 
just  before  collision  A\as  accomplished  with 
purely  auditory  clues. 

It  is  not  yet  clear  just  ivhat  kinds  of 
sound  blind   men   use   to   detect   obstacles. 


386 


Topographical  Orientation 


but  we  know  that  the  ability  is  lost  when 
there  is  no  sound  at  all  or  when  very  loud 
distracting  noises  are  present.  Objects  are 
apparently  detected  by  noticing  changes  in 
the  perceived  quality  of  sounds,  changes 
due  to  the  presence  of  the  obstacles.  Street 
noises  have  a  different  sound  when  we  are 
close  to  a  building  from  their  sound  when 
we  are  walking  past  a  vacant  lot.  Often 
the  sounds  are  made  by  the  blind  man  him- 
self, consciously  or  unconsciously,  to  aid  in 
the  auditory  perception  of  obstacles. 
There  is  the  blind  man's  traditional  tap: 
ping  with  his  cane  (as,  for  instance,  the 
blind  man  Pew  in  Treasure  Island),  al- 
though he  also  uses  his  cane  to  feel  out  the 
ground  immediately  ahead.  Or  he  makes 
sounds  such  as  tapping,  shuffling  his  feet, 
snapping  his  fingers  or  short  sharp  whistled 
or  vocal  sounds.  In  such  instances  blind 
men  are  apparently  able  to  make  use  of  the 
echoes  of  such  sounds  as  clues  to  the  prox- 
imity of  solid  objects. 

The  auditory  clues  must  be  very  subtle 
indeed,  since  very  few  blind  men  are  aware 
that  it  is  hearing  which  warns  them  of  ob- 
stacles. Yet  that  should  not  surprise  us. 
A  clue  to  be  effective  in  perception  does 
not  have  to  be  conscious  in  the  sense  that 
the  organisrh  which  uses  the  clue  knows 
that  he  has  the  clue  or  that  he  uses  it.  Un- 
awareness  of  clues  is  rather  the  rule  in  well- 
established  perceptions  like  the  perceptions 
of  spatial  relations.  Most  proprioceptive 
clues  are  unconscious.  We  do  not  directly 
perceive  excitation  from  the  nonauditory 
labyrinth,  although  we  perceive  the  effects 
in  the  perception  of  rotation,  dizziness  and 
the  visual  'swimming'  of  nystagmus.  Only 
by  indirect  means  can  we  demonstrate  that 
the  retinal  disparity,  which  comes  about 
because  of  binocular  parallax,  provides  the 
clues  for  the  perception  of  depth  and  solid- 
ity.     One    clue    used    here    involves    the 


brain's  'knowing'  what  its  owner  nevei 
'knows'  in  any  full  verbally  expressive 
sense,  that  is  to  say,  which  eye  perceives 
which  disparate  image.  No  man  judging 
distance  on  the  basis  of  the  convergence 
or  accommodation  of  his  eyes  knows  that 
he  uses  these  clues.  The  blind  man  in  his 
'facial  vision'  is  thus  not  out  of  line  with 
the  psychology  of  perception.  He  presents 
simply  a  new,  interesting  case,  which  is 
somewhat  surprising  because  facial  vision 
is  presumably  learned  and  not  necessarily 
learned  in  infancy. 

Why  do  the  blind  think  that  facial  vision 
is  a  cutaneous  perception  and  not  audi- 
tory? There  may  be,  of  course,  some  use- 
ful cutaneous  clues  for  them,  but  the  ex- 
periments have  shown  that  such  clues  are 
neither  necessary  nor  sufficient  for  the 
blind's  perception  of  obstacles.  Still,  if 
there  is  some  cutaneous  experience  and  if 
the  blind  are  constantly  in  fear  of  bumping 
into  objects  and  have  sometimes  bumped 
into  them,  they  may  be  especially  aware  of 
their  cutaneous  experience  and  may  come 
to  associate  it  with  the  auditorially  condi- 
tioned facial  vision. 

Auditory  Orientation  by  Bats 

The  use  of  sound  for  purposes  of  topo- 
graphical orientation  is  also  developed  to  a 
high  degree  of  perfection  in  one  group  of 
lower  animals,  the  bats.  Bats  are  noc- 
turnal flying  mammals,  mostly  smaller  in 
body  than  a  mouse,  and  not  only  do  they 
fly  at  night  in  thick  woods  but  they  are 
also  very  frequently  found  flying  through 
the  total  darkness  of  underground  caverns. 
Under  these  circumstances  they  are,  never- 
theless, able  to  negotiate  tortuous  passages 
without  colliding  with  the  irregular  rocky 
walls  or  with  each  other.  Furthermore,  it 
was  shown  long  ago  that  after  being 
blinded  bats  can  avoid  obstacles  as  well  as 


Echolocation 


387 


ever,  even  when  the  obstacles  are  wires  as 
small  as  one  millimeter  in  diameter.  Just 
as  cutaneous  perception  was  once  the  most 
generally  accepted  explanation  of  the  abil- 
ity of  blind  men  to  find  their  way  around, 
so  the  sensory  basis  of  the  bat's  ability  was 
long  thought  to  depend  on  a  highly  devel- 
oped sense  of  touch.  And  the  parallel  ex- 
tends fiuther;  a  few  biologists  felt  that 
hearing  was  more  important  for  the  bats 
than  touch,  especially  since  bats  lost  much 
of  their  ability  when  their  ears  were 
stopped.  The  bat's  flight,  however,  ap- 
peared to  be  quite  silent,  and  for  this  rea- 
son the  auditory  theory  was  not  widely  ac- 
cepted until  it  was  shown  recently  that  the 
animals  were  actually  emitting  sounds 
which  were  'ultrasonic'  in  the  sense  that 
they  were  too  high  in  frequency  to  be  de- 
tected by  human  ears. 

Although  bats  can  make  shrill  cries 
which  men  have  no  difficulty  in  hearing, 
they  also  emit  during  flight  special  ultra- 
sonic cries  which  have  a  frequency  of 
30,000  to  70,000  cycles  per  second,  whereas 
the  upper  limit  of  human  hearing  is  only 
about  20,000  cycles  per  second.  The  pro- 
duction of  these  ultrasonic  cries  is  neces- 
sary if  the  bats  are  successfully  to  avoid 
obstacles.  When  a  bat's  ears  are  stopped, 
it  becomes  helpless  and  strikes  whatever 
obstacles  beset  its  path.  In  short,  the  bat's 
eyesight  is  so  poor  (at  least  in  some  spe- 
cies) that  hearing  has  become  for  it  the 
principal  sensory  avenue  by  which  it  per- 
ceives objects  at  a  distance  from  its  body. 

Echolocation 

More  is  known  about  the  clues  used  by 
bats  to  detect  obstacles  than  about  the 
clues  used  by  blind  men.  The  bats  ap- 
parently rely  entirely  on  their  own  ultra- 
sonic cries  which,  because  of  their  short 
wave  length,  are  propagated  and  reflected 


less  diffusely  than  sounds  in  the  audiblc 
range.  The  duration  of  a  bat's  cry  is  very 
short,  usually  0.001  to  0.002  second.  It  is 
essentially  a  click,  and  the  individual  clicks 
are  emitted  as  often  as  fifty  times  a  second. 
Apparently  the  bat  hears  echoes  of  these 
pulses  of  high-frequency  sound  and  detects 
obstacles  by  auditory  localization  of  the 
source  of  the  echo.  The  time  elapsing  be- 
tween the  original  pulse  and  the  return  of 
the  echo  probably  tells  the  bat  its  distance 
from  the  obstacle.  The  short  duration  per- 
mits the  echo  to  be  heard  without  inter- 
ference from  the  original  pulse  even  at 
close  range.  Figure  194  shows  the  waves  in 
a  single  pulse  of  the  bat's  cry  in  true  pro- 
portion to  the  animal's  own  size.  Each 
curved  line  in  this  figure  represents  the 
crest  of  a  sound  pressure  wave.  The  wave 
length  of  each  sound  wave  is  5  to  10  milli- 
meters, and  the  entire  pulse  is  spread  over 
a  distance  of  only  a  foot  or  so. 

There  is  an  obvious  parallel  between  the 
bat's  method  of  locating  obstacles  and  the 
newly  developed  sonar  instruments.  Sonar 
instruments  send  sound  waves  through  the 
water  and  detect  echoes  from  submarines, 
fish  and  other  objects,  including  the  bot- 
tom itself.  In  the  last  case  the  instrument 
becomes  a  sonic  depth  finder,  an  extremely 
useful  aid  to  navigation.  Thus  bats,  sonar 
instruments  and  blind  men  all  seem  to  be 
employing  the  same  fundamental  process, 
the  sending  out  of  exploratory  sounds  and 
the  detection  of  distant  objects  by  means  of 
echoes.  In  view  of  this  similarity  the  term 
echolocation  has  been  proposed  to  cover 
all  such  uses  of  echoes  to  aid  in  topograph- 
ical orientation. 

Strictly  speaking,  we  cannot  be  certain 
a  priori  that  a  blind  man  always  uses  eclio 
rather  than  unreflected  sound.  There  are 
four  possible  ways  in  which  objects  could 
be  localized  by  auditory  means.  (1)  The  ob- 


388 


Topographical  Orientation 


ject  itself  could  be  a  source  of  sound,  and 
as  such  it  would  be  localized  by  any  person 
with  normal  hearing.  (2)  There  is  nearly 
always  a  certain  amount  of  random  sound 
in  any  region,  for  absolute  quiet  is  rare  in- 
deed. The  presence  of  an  object  will  affect 
the  character  of  these  random  sounds,  and 


the  conclusion  that  blind  men,  as  well  as 
bats,  use  echolocation  for  their  orientation 
in  space. 

The  blind  man's  ability  at  echolocation, 
remarkable  as  it  is,  cannot,  however,  com- 
pare in  refinement  to  the  bat's.  A  blind 
man  is  expert  if  he  can  detect  a  lamp  post 


fij.GUtRRiene 


FIGURE    194.      A  FLYING   BAT  AND   ITS   ULTRASONIC   CRY 


The  curved  lines  represent  individual  sound  waves  of  a  single  pulse.  Bats  emit  as  many  as  50  of  these 
pulses  per  second  and  locate  obstacles  by  hearing  the  echoes.  The  sound  waves  are  represented  here  in 
true  proportion  to  the  size  of  the  bat,  and  it  is  clear  that  the  entire  pulse  occupies  only  a  space  of  about 
a  foot.  This  permits  even  objects  at  a  short  distance  to  be  perceived  without  overlap  of  the  original  pulse 
and  the  returning  echo. 


they  will  also  be  reflected  from  it.  A  blind 
man  could  get  clues  in  that  manner.  (3) 
An  object  can  also  indicate  its  presence 
by  obstructing  random  sound  or  sound 
from  other  objects.  Perceiving  its  sound 
shadow  indicates  something  about  the  lo- 
cation of  an  object.  (4)  Finally,  as  we  have 
seen,  the  blind  man  like  the  bat,  frequently 
makes  his  own  sound,  the  echoes  of  which, 
being  localized,  reveal  the  position  of  the 
object  reflecting  the  echoes.  There  can  be 
little  doubt  that  echoes  play  an  important 
role  in  the  auditory  perception  of  the  posi- 
tion of  silent  objects,  and  we  may  accept 


six  inches  in  diameter,  but  flying  bats  can 
dodge  wires  as  small  across  as  one  milli- 
meter. This  three  hundredfold  difference 
in  minimum  perceptible  size  of  a  remote 
obstacle  far  exceeds  the  ratio  in  size  be- 
tween bats  and  men  and  likewise  the  differ- 
ence in  wave  length  of  the  sounds  em- 
ployed. It  represents  largely  the  difference 
in  perceptual  skill  between  an  animal 
whose  sensory  world  is  largely  auditory  and 
a  man  who  ordinarily  relies  primarily  on 
vision  and  has  learned  only  under  stress  of 
necessity  to  use  his  sense  of  hearing  for 
topographical  orientation.     A  congenitally 


Migration  and  Homing 


389 


blind  man  witli  special  tiaining  from  in- 
fancy on  might  hv  able  to  develop  a  skill 
at  echolocation  rivaling  the  bat's. 

Other  Problems  of  Animal  Orientation 

There  are  other  inlrahuman  animals 
which  keep  themselves  oriented  under  cii- 
cumstances  where  a  man  would  be  quite 
unable  to  do  so.  In  some  of  these  cases  we 
know  the  clues  and  the  sense  organs  which 
are  involved;  in  others  we  do  not. 

Animals  such  as  dogs,  cats,  foxes  and  deer 
have  the  sense  of  smell  far  better  developed 
than  man.  A  hunting  dog  following  the 
trail  of  a  rabbit  is  analogous  to  the  man 
following  a  marked  path;  here  the  edges  of 
the  path  are  fixed  by  the  absence  of  rabbit 
scent.  The  direction  in  which  to  follow 
the  trail  presents  a  problem  even  to  skilled 
dogs;  they  often  start  in  the  wrong  direc- 
tion and  discover  their  error  only  after 
some  distance,  probably  because  of  a  de- 
crease in  the  intensity  of  the  scent. 

Fish  can  detect  food  at  distances  of  sev- 
eral feet  through  water,  apparently  because 
their  chemical  receptors  are  stimulated  by 
molecules  diffusing  from  the  food  material. 
Since  fish  can  often  turn  quickly  toward  the 
food,  they  must  perceive  the  direction  from 
which  the  molecules  are  diffusing.  Perhaps 
they  do  this  on  the  basis  of  'diffusion  shad- 
ows' cast  by  their  own  bodies.  If  the  food 
is  to  the  fish's  right,  more  molecules  will 
strike  the  right  side  of  its  body  than  the 
left.  Few  details  are  known  about  the 
sensory  basis  of  orientation  or  even  the  de- 
tection of  food  by  other  cold-blooded  ani- 
mals. 

MIGRATION    AND    HOMING 

Very  remarkable  is  the  ability  of  many 
animals  to  travel  over  long  distances  with  a 
considerable   degree   of   accuracy    in    their 


navigation.  The  annual  fli^his  of  migra- 
tory birds  are  the  most  striking  examples. 
Figure  195  shows  the  migration  route  of 
the  golden  plover,  a  bird  which  is  little 
larger  than  a  robin.  It  breeds  on  the 
shores  of  the  Arctic  Ocean  and  flies  each 
year  about  eight  thousand  miles  to  a  win- 
tering range  in  South  America.  Further- 
more, the  route  it  follows  during  the  south- 
ward autumn  flight  is  quite  different  from 
its  route  returning  in  the  spring.  Other 
golden  plovers  migrate  between  Alaska  and 
the  Hawaiian  Islands,  and  long  overwater 
flights  are  regular  occurrences  with  many 
other  birds.  In  certain  species  the  young 
birds  apparently  perform  their  first  migra- 
tion without  the  companv  of  the  older  birds 
who  might  act  as  guides. 

Long  annual  migrations  are  not  con- 
fined to  birds.  Seals  and  whales  migrate 
thousands  of  miles.  Even  some  bats,  de- 
pendent as  they  are  on  echolocation,  man- 
age to  migrate  at  least  five  hundred  miles 
between  summer  and  winter  quarters. 
Fish  present  us  with  equally  baffling  in- 
stances. Salmon  spawTi  in  fresh-water 
streams  which  are  often  tributaries  of  large 
rivers.  Some  species  descend  the  rivers 
and  swim  many  miles  into  the  ocean,  well 
away  from  the  influence  of  the  river  water; 
yet  in  subsequent  seasons  they  return  to 
their  own  spawning  grounds,  not  only  find- 
ing the  river  as  it  flows  into  the  sea  but 
also  selecting  the  correct  tributary.  Eels 
migrate  in  the  opposite  direction,  spawning 
in  mid-Atlantic  and  migrating  slowly  as 
immature  fish  toward  the  coast,  where  thev 
find  their  way  into  rivers  and  streams. 
Even  butterflies  migrate;  one  species 
emerges  from  cocoons  in  North  .Africa,  and 
the  individuals  fly  north  and  west  across 
western  Europe  as  far  as  the  British  Isles 
and  even  Iceland. 


FIGURE    195.       MIGRATION    ROUTE    OF    THE    GOLDEN    PLOVER 

The  dotted  areas  in  the  Arctic  are  the  summer  range  and  the  lined  areas  the  winter  range.  One  form 
migrates  across  Canada  to  South  America.  The  other  goes  from  Alaska  to  Hawaii  and  the  South  Seas. 
[Reproduced  by  permission  of  the  U.  S.  Department  of  Agriculture,  Circular  363,  Fig.  22.] 

390 


The  Sensory  Basis  of  Migration 


391 


The  Sensory  Basis  of  Migration 

To  date  no  truly  salisraclory  answer  can 
be  given  to  the  question,  "How  do  animals 
find  their  way  about?" 

Birds  have  been  most  studied,  and  some 
information  has  been  obtained  from  hom- 
ing experiments  in  which  a  migratory  flight 
is  simulated  by  removing  birds  from  their 
nests  and  releasing  them  at  a  distance. 
Many  wild  birds  will  return  to  their  nests, 
like  homing  pigeons,  from  one  thousand 
miles  or  more  away.  The  results  of  such 
homing  experiments  show  that  birds  rely 
to  some  extent  on  visual  landmarks,  for 
when  experimental  shipments  are  made 
over  equal  distances  into  familiar  and  un- 
familiar territory,  more  birds  return  from 
the  familiar  territory,  usually  an  area  which 
they  were  known  to  have  traversed  pre- 
viously during  their  natural  migration. 
Also  the  speed  of  the  return  flight  is  higher, 
on  the  average,  from  familiar  territory. 
Furthermore,  birds  which  have  returned 
from  unfamiliar  territory  evidently  learn 
new  landmarks  in  the  process;  after  a  sec- 
ond shipment  to  the  same  release  point, 
they  return  much  sooner.  For  instance, 
three  sea  gulls  shipped  250  miles  inland 
from  their  nests  on  an  island  near  the 
coast  of  Massachusetts  returned  in  10,  6 
and  414  days  respectively.  The  following 
year  they  were  shipped  again  to  the  same 
release  point  and  returned  in  29,  18  and 
48  hours.  The  first  two  birds  required  only 
one-eighth  as  long  to  make  the  second  trip 
as  the  first. 

But  something  more  than  visual  land- 
marks seems  necessary  to  account  for  the 
longer  homing  flights  and  natural  migra- 
tions. For  instance,  one  strictly  marine 
species,  the  shearwater,  has  been  shipped 
from  a  nesting  island  off  the  coast  of  Wales 
to  points  in  the  Swiss  Alps  and  to  Venice, 


Italy.  Shearwaters  never  normally  fly  any 
appreciable  distance  inland;  only  during 
the  nesting  season  do  they  come  to  land  at 
all  (usually  on  small  islands).  The  rest  of 
their  lives  are  spent  at  sea.  Furthermore, 
this  particular  species  is  not  found  in  the 
Mediterranean.  Clearly  both  Venice  and 
the  Swiss  Alps  lie  in  totally  unfamiliar  ter- 
ritory, yet  both  of  the  shearwaters  shipped 
to  Venice  returned,  one  in  14  days,  and  three 
out  of  twelve  came  back  from  the  Alps 
after  13  to  17  days. 

Sensitivity  to  the  earth's  magnetic  field 
has  been  postulated  as  a  means  by  which 
birds  might  navigate  over  these  long  dis- 
tances, but  there  is  no  physiological  evi- 
dence that  birds  have  such  sensitivity  any 
more  than  men.  In  some  cases  the  direc- 
tion of  the  sun  may  be  used  as  a  clue  to 
direction,  yet  some  birds  migrate  at  night, 
in  overcast  weather  and  in  fog.  Another 
possibility  is  that  birds  are  aware  of  the 
prevailing  wind  direction  when  various 
types  of  air  mass  cover  the  region  through 
which  they  are  traveling.  Air  masses  are 
bodies  of  air  several  hundred  miles  in  ex- 
tent which  are  characterized  by  tempera- 
ture, degree  of  visibility  (the  distance  we 
can  see)  and  turbulence  (the  presence  of 
updrafts  and  downdrafts).  Each  of  the 
common  types  of  air  mass  has  a  roughly 
constant  prevailing  wind  direction,  and.  if 
birds  can  perceive  temperature,  visibility, 
tiubulence  and  wind  direction,  they  can 
perhaps  find  their  way  over  long  distances 
with  considerable  success  by  flying  up- 
wind, downwind,  crossAvind  or  quartering, 
whichever  is  appropriate  to  the  situation. 
Some  migrating  birds  have  actually  been 
observed  to  change  the  direction  of  their 
flight  with  shifts  in  the  direction  of  the 
wind.  This  hypothesis  of  navigation,  based 
on  atmospheric  clues,   is.   ho^vever.   largely 


392 


Topographical  Orienfation 


speculati\c  at  present,  and  it  is  obviously 
not  applicable  to  the  migration  of  fish. 

Some  men  have  also  developed  an  ability 
to  navigate  Avithout  obvious  sensory  clues. 
Among  the  best  examples,  so  far  studied 
only  casually,  are  certain  fishermen  who 
spend  much  of  their  time  sailing  in  small 
boats  through  foggy  waters.  Often  they 
can  steer  a  course  for  several  miles,  from 
one  island  to  another,  through  thick  fog, 
without  benefit  of  compass  or  other  instru- 
mental aid,  allowing  for  the  effects  of  wind 
and  strong  tidal  currents,  and  striking  the 
desired  landfall  with  an  angular  error  of 
only  a  very  few  degrees.  The  sensory  basis 
of  their  ability  is  as  obscure  as  the  migra- 
tory birds'. 

REFERENCES 

1.  Boiino;.  E.  G.  ('Ed.).  P.s\rlioln<r\'  for  ihr  armed 
services.  ■Washington:  Iiifantvy  |ouiiial.  194."). 
Chap.  8. 

A  twelve-page  chapter  on  how  lo  i;ct  lo 
strange  places,  how  to  get  home  and  how  lo 
find  your  wav  when  lost. 

2.  Hayes,  S.   P.     Contributions  lo  a  psyclwlogy  oj 


blindness.      New    Vork:    .Vnicrican    Eoutulation 
for  the  Blind,  1941.     Chap.  3. 

A  chapter  which  gives  a  good  accoinil  of  the 
early  experiments  on  'facial  vision'  and  the 
avoidance  of  obstacles  by  the  blind. 

3.  Lincoln,  F.  C.  The  migration  of  American 
birds.     New  Vork:  Doubleday  Doran,  1939. 

A  well-known  classic  study  of  bird  migra- 
tions written  by  an  ornithologist.  It  contains 
numerous  maps  showing  the  courses  of  the 
migrations. 

4.  Thompson,  .\.  L.  The  problems  of  bird  migra- 
tion.    London:  Witherby,  1926. 

.\  descriptive  studv  of  the  problems  involved 
in   bird  migration. 

5.  ^Vardcn,  C.  J.,  Jenkins,  T.  N.,  and  Warner,  L. 
H.  Comparatiite  ps^'cliologx.  a  comprehensive 
treatise:  vertebrates.  New  York:  Ronald  Press, 
1936. 

Brief  discussions  of  homing  in  animals.  See 
pp.  236-249  et  passim,  using  the  inilcx. 

6.  AVatson,  |.  B.,  and  Lashley,  K.  S.  Homing  and 
related  activities  of  birds.  Washington:  Car- 
negie Institute,  1915.     Pp.  9-60. 

.Vn  account  of  some  experiments  on  homing, 
a  review  of  the  theories,  a  sound  discussion 
which  is  now  out  of  dale  l)ut  dispenses  with 
many  current  mysteries. 


CHAPTER 


18 


Individual  Differences 


INDIVIDUAL  differences  in  behavior  are 
characteristic  of  all  living  organisms. 
Casual  or  superficial  acquaintance  with  a 
group,  even  within  our  own  species,  often 
creates  an  erroneous  impression  of  uni- 
formity and  leads  to  the  false  generaliza- 
tions at  the  basis  of  many  of  our  social 
stereotypes.  "All  cats  look  gray  at  night," 
but  upon  closer  acquaintance  each  becomes 
an  individual  in  his  own  right.  Not  only 
within  the  human  species,  but  also  among 
lower  forms,  wide  variations  in  individual 
capacity  and  behavior  are  to  be  found. 

Every  laboratory  investigation  employ- 
ing more  than  one  animal  subject  reveals 
extensive  individual  variation.  Such  vari- 
ation has  been  observed  in  amount  of  spon- 
taneous activity,  in  relative  strengths  of 
needs,  in  speed  of  movement,  in  speed  of 
learning  and  in  problem  solving.  In  ex- 
periments on  conditioning,  for  example,  the 
number  of  trials  required  to  establish  a 
given  conditioned  response  ranged  from  79 
to  284  in  a  group  of  82  protozoa;  in  a 
similar  conditioning  experiment  with  14 
crustaceans,  the  range  of  trials  was  from  34 
to  1112;  in  a  group  of  59  fish,  from  3  to  35; 
among  13  pigeons,  from  30  to  40;  and 
among  11  sheep,  from  3  to  17. 


MEASUREMENT    OF    INDIVIDUAL 
DIFFERENCES 

It  has  become  increasingly  evident  in 
recent  years  that  the  more  we  know  about 
individual  differences  in  intelligence,  in 
aptitudes  for  particular  tasks  and  in  the 
ability  to  make  good  adjustments  in  social 
living,  the  better  able  we  shall  be  to  train 
and  guide  the  individual  in  making  the 
most  of  his  physical  and  mental  equip- 
ment. 

It  is  not  enough  to  know  the  ways  in 
which  a  single  person  differs  from  others. 
We  must  also  know  how  in  a  particular 
way  a  number  of  persons  differ  with  re- 
spect to  one  another.  Only  then  can  we 
properly  judge  the  capacity  of  any  one  per- 
son relative  to  that  of  his  fellows.  The  one 
reliable  method  of  obtaining  this  knowl- 
edge is  by  measurement. 

We  have  already  considered  some  of  the 
basic  problems  of  psychological  measure- 
ment in  Chapter  11.  ^Ve  have  seen  that,  in 
order  to  measure  sensibility,  special  methods 
of  measurement  had  to  be  invented  and  a 
unit  of  measurement  found.  In  this  chap 
ter  we  shall  see  that  many  other  methods 
ha\e  been  devised  to  measure  psycholog- 
ical    capacities,     abilities     and     aptitudes. 


This  chapter  was  prepared  by  Anne  Anastasi  of  Fordliam  I'niversity. 

393 


394 


Individual  Differences 


They  differ  widely  among  themsehes,  but 
in  principle  they  are  all  alike.  They  are 
called  psychological  tests. 

Characteristics  of  a 
Psychological  Test 

Basically  every  psychological  test  is  an 
objective  and  standardized  nieasine  of  a 
sample  of  the  individual's  behavior.  Such 
a  test  is  merely  a  small  sample  ol  the  type 
of  behavior  being  explored.  The  psychol- 
ogist proceeds  in  much  the  same  way  as, 
for  example,  the  chemist  who  'tests'  a  quan- 
tity of  milk  or  iron  by  analyzing  one  or 
more  samples  of  it  and  deducing  from  his 
results  the  approximate  characteristics  of 
the  entire  quantity.  Similarly,  when  the 
psychologist  wishes  to  measure  an  individ- 
ual's vocabulary,  arithmetic  ability  or  hand 
coordination,  lie  observes  the  person's  per- 
formance with  only  a  limited  number  of 
words,  arithmetic  problems  or  hand  move- 
ments, carefully  chosen  so  as  to  be  typical 
of  the  total  behavior  he  wishes  to  assess. 

Standardization 

If  tlie  results  of  a  psychological  test  are 
to  have  value  in  diagnosing  or  predicting 
behavior,  the  testing  procedure  must  be 
standardized.  The  standardization  of  a 
test  consists  in  the  establishment  of  uniform 
cnnditioju  for  administering  the  test  to  all 
individuals,  as  well  as  a  uniform  method 
for  evaluating  responses.  The  one  variable 
in  a  test  situation  is  the  person  being  tested. 
If  all  other  conditions  are  kept  rigidly  con- 
stant, then  (and  then  only)  can  differences 
in  score  be  correctly  attributed  to  the  indi- 
vidual himself,  who  should  be  the  sole 
variable. 

Norms 

When  the  testee  has  taken  the  test,  the 
psychologist  has  for  him  a  score,  the  total 


number  of  correct  items,  the  time  required 
to  complete  the  task  or  some  other  ob- 
jective index  of  response  suited  to  the  spe- 
cific test  content.  That  is  the  testee's  raiv 
score. 

Such  a  raw  score  has  little  meaning  in 
itself,  however,  because  a  psychological  test 
imposes  no  arbitrary,  predeterminetl  stand- 
ards of  'passing'  or  'failing.'  Thus  a  score 
of  78  items  correct  out  of  100  on  a  par- 
ticular test  of  arithmetic  reasoning  could 
indicate  an  excellent  performance,  or  it 
could  be  just  fair,  or  quite  inferior.  Tiie 
evaluation  of  the  raw  score  depends  upon 
norms,  which  must  be  objectively  deter- 
mined for  each  test  before  it  can  be  put  to 
practical  use.  A  norm  is  simply  the  normal 
or  average  performance  on  the  test  in  ques- 
tion. If  we  are  designing  a  test  for  8-yeai- 
olds,  we  must  first  administer  it  to  a  large, 
representative  group  of  8-year-olds  in  ordei 
to  determine  what  is.  the  average  8-year-(>ld 
performance.  Then  if  we  find,  for  ex- 
ample, that  the  average  8-year-oId  com- 
pletes 6  out  of  15  problems  coneclly,  a  raw 
score  of  6  becomes  the  8-year  norm  on  this 
test.  Such  a  norm  can  then  be  used  in  \\\c 
future  in  evaluating  the  performance  of 
any  8-year-old  child  we  wish  to  examine. 

Raw  scores  are  frequently  translated  into 
percentile  norms  in  order  to  express  their 
relationship  to  the  performance  of  the 
group  used  for  standardization.  A  percen- 
tile is  the  percentage  of  individuals  who 
fall  below  the  given  score.  Thus  if  ()5  per 
cent  of  the  subjects  in  the  standardization 
group  score  below  20  in  a  vocabulary  lest, 
a  raw  score  of  20  on  this  test  corresponds 
to  a  percentile  of  65.  Thus  to  know  that 
an  individual  has  received  a  percentile 
score  of  65  on  any  test  enables  us  to  con- 
clude immediately  that  his  performance  ex- 
cels that  of  the  lower  65  per  cent  of  the 
standardization  group  on  that  test. 


Measurement 


395 


The  [ilticth  pcnciiLilc  score  is  obviously 
tlic  iiiicli)oint  or  average  score.  The  zero 
percenlilc  signifies  a  score  below  the  low- 
est ol  any  in  the  standardization  group;  the 
one  hundredth  percentile  is  above  the  best 
score  obtained  by  anyone  in  the  groujj. 
The  former  does  not  usually  represent  a 
zero  raw  score,  nor  the  latter  a  perled 
score.  Percentile  scores  are  expiessed  in 
terms  of  people,  not  the  number  ol  items 
passed.  In  a  good  test  or  examination  the 
zero  percentile  should  be  above  zero  score, 
for  a  test  on  which  anyone  tested  can  get 
zero  fails  to  show  how  much  less  than  zero 
he  might  have  got,  had  he  but  had  the 
chance.  Similarly  every  test  and  examina- 
tion shoidd  have  the  one  hundredth  per- 
centile below  the  perfect  score,  for  the 
person  who  gets  a  perfect  score  has  lost  the 
chance  to  show  how  much  better  than  per- 
fect he  can  be  in  his  performance.  He  is 
the  victim  of  too  easy  a  test. 

Reliability 

A  test  is  said  to  have  reliability  if  it 
gives  the  same  results  on  different  occa- 
sions. The  reliability  of  a  test  refers  to 
the  consistency  of  the  subjects'  scores  when 
they  are  tested  again.  You  do  not,  of 
course,  expect  to  get  identically  the  same 
result  on  a  second  trial.  The  testee  may 
have  changed  or  the  test  may  be  working 
differently.  You  can  rule  out  variation  in 
(he  testee's  ability  by  taking  a  large  num- 
ber of  subjects.  If  the  test  then  seems  not 
to  give  consistent  residts,  it  lacks  reliability 
and  cannot  be  used  for  accurate  measure- 
ment. You  can  measure  the  length  of  a 
room  by  a  yardstick  or  by  pacing  the  dis- 
tance off.  Which  is  more  reliable?  You 
can  tell  by  seeing  which  method  gives  you 
more  variability  when  you  repeat  the  meas- 
urement. If  the  yardstick  gives  results 
varying  between  23  feet  2  inches  and  23 


feet  2'/;  indies,  and  if  pacing  gives  rcsulUt 
varying  Ijeiwccn  22|/,  feet  and  23 '/C  feet,  it 
is  plain  tfiat  your  yardstick  is  more  reliable 
than  your  stride  as  a  measuring  instrument. 
There  are  three  ways  in  which  the  relia- 
bility of  a  test  may  be  measured.  (I)  A 
large  number  of  persons  may  be  tested  and 
then  relested,  and  their  scores  on  the  lest 
and  the  retest  comjjared.  (2)  A  test,  which 
consists  of  many  items,  may  be  dividend  in 
half,  and  scores  obtained  from  one  half  the 
items  taken  alone  compared  with  scores 
from  the  other  half.  (3)  Different  forms  of 
the  test  may  be  constructed,  as  is  necessary 
if  experience  with  one  form  makes  retest- 
ing  unfair,  and  the  scores  of  many  persons 
on  each  of  the  forms  can  be  compared.  A 
coefficient  of  correlation  (see  below)  may  be 
used  to  measure  these  relationships  and 
thus  the  reliability. 

Validity 

The  degree  to  which  the  test  actually 
succeeds  in  measuring  what  it  sets  out  to 
measure  is  called  its  validily.  In  order  to 
determine  test  validity,  it  is  necessary  to 
have  an  independent  criterion  of  the  trait 
being  measured,  so  that  the  results  of  the 
test  can  be  compared  ^vith  the  criterion, 
validated  against  it.  For  example,  in  ^ali- 
dating  a  test  of  musical  aptitude,  actual 
performance  by  the  testees  in  music  schools 
was  used  as  the  criterion.  A  test  designed 
for  the  selection  of  taxicab  drivers  would 
be  ^alidated  against  subsequent  job  per- 
formance of  a  sample  of  the  group  of 
drivers— for  example,  against  the  numbers 
of  their  accidents.  A  scholastic  aptitude 
test  for  college  freshmen  woidd  be  checked 
against  the  students'  grades  in  college 
comses.  If  a  test  has  high  validity,  tliose 
persons  scoring  high  on  the  test  will  do 
well  in  their  subsequent  performance  on 
the  job,  in  school  or  in  whatever  activity 


396 


Individual  Differences 


the   test  ought   to  predict;   and   conversely 
tor  those  with  low  scores. 

Two  illustrations  of  test  Aalidation  taken 
Irom  the  military  use  of  tests  in  the  Second 


140 


130-139 


120-129 


110-119 


under 
110 


mmm 
mmm 
nmum 
amm 

fimm 


(I 


Officer  Candidates 
=  10%  U    =10% 


Receiving 
a  commission 


Not  receiving 
a  commission 


FIGURE     196.        TEST    ^•ALIDATIO^'     WITH     OFFICER 
CANDIDATES 

Shows  the  percentage  of  officer  candidates  in  the 
U.  S.  Army  who  received  their  commissions  in  rela- 
tion to  their  scores  on  the  Army  General  Classifica- 
tion Test  (14  schools,  5520  men).  [From  E.  G. 
Boring  (Ed.).  Psychology  for  the  aimed  seniices.  In- 
fantry Journal,  1945,  p.  242.] 

\Vorld  War  are  to  be  found  in  Figs.  196 
and  197.  Both  are  concerned  with  the 
validity  of  the  Army  General  Classification 
Test  (AGCT).  Figure  196  indicates  the 
degree  to  which  this  test  could  be  used  to 
predict    the    success    of    officer    candidates. 


The  actual  commissioning  of  the  men  at 
the  completion  of  their  officer-training 
course  was  the  criterion.  The  data  on  5520 
officer  candidates  distributed  in  fourteen 
schools  suggest  a  fairly  close  correspondence 
between  test  score  and  criterion.  Thus,  of 
the  men  scoring  140  or  higher  on  the  test, 
over  90  per  cent  received  commissions. 
Of  those  scoring  under  110,  on  the  other 
liand,  less  than  50  per  cent  succeeded  in 
obtaining  the  commission,  although  they 
had  gone  through  the  same  training  course. 
Similar  data  for  tank  mechanics  are  gi\cn 
in  Fig.  197.  Grades  obtained  in  a  tank 
mechanics  course  constituted  the  criterion 
for  this  group.  The  figure  shows  that  the 
AGCT  score  (lower  half  of  the  figine)  pre- 
dicts success  well.  It  is  liardly  worth  while 
to  train  men  in  groups  III,  IV  or  V.  The 
upper  half  of  the  figure  shows  that  the 
amount  of  schooling  which  the  men  had  is 
not  so  good  a  criterion  in  predicting  suc- 
cess as  the  AGCT  score. 

The  Correlation  CoeflFlcient 

In  measuring  either  the  reliablity  or  the 
\alidity  of  a  test,  the  closeness  of  corrr- 
spoTidence  between  two  sets  of  measures 
must  be  ascertained.  A  single  index  of 
such  correspondence  is  furnished  by  the 
coefficient  of  correlation  (>),  a  value  which 
can  vary  numerically  from  -)-1.00,  a  perfect 
positive  correlation,  through  0,  to  —1.00,  a 
perfect  negative  or  inverse  correlation. 

A  correlation  of  -1-1.00  between  the  re- 
sults of  two  tests  means  that  all  the  persons 
tested  on  the  two  tests  rank  in  the  same 
order  on  each,  and  that  their  scores  are 
proportionally  spaced  in  the  same  way  on 
the  scale  of  each  test.  If  you  measure  the 
heights  of  people  in  inches  and  in  centi- 
meters, you  should  find  a  perfect  correla- 
tion between  the  two  measurements,  r  = 
-1-1.00.      Usually    a    perfect    correlation    is 


The  Correlafion  Coefficient 


397 


14 


mm 


tiC: 


^m 


Getting  an  above 
average  grade 


FIGURE    197.       TF.ST    VALIDATION    WITH    TANK 
MECHANICS 


taken  to  incaii  iliat  tlic  tests  (orrelated  arc 
measuring  the  same  thing. 

A  good  example  of  a  perfcf  t  negative  eor- 
relation,  r  -1.00,  comes  from  physics.  If 
you  can  keep  the  temperature  of  an  amount 
of  air  constant,  you  can  halve  the  volume 
by  doubling  the  pressure,  or  you  can  halve 
the  pressure  by  doubling  the  volume,  r  = 
-1.00.  Negative  correlations  sometimes 
mean,  however,  that  the  stale  of  measure- 
ment should  be  reversed.  If  industry  and 
poverty  were  to  be  found  negatively  corre- 
lated, undoubtedly  industry  and  wealth 
would  be  positively  correlated,  since  wealth 
is  the  opposite  of  poverty. 

A  zero  correlation  means  that  there  is  no 
relationship  at  all.  You  would  expect  a 
zero  correlation  between  the  heights  of 
adults  and  their  intelligences.  Zero  corre- 
lation is  the  indicator  of  complete  inde- 
pendence. Tall  adults  are  neither  brighter 
nor  duller  than  short  ones,  but  you  would 
not  get  zero  correlation  with  children,  for 
the  children  grow  both  brighter  and  taller 
at  the  same  time. 

The  meaning  of  a  correlation  coefficient 
may  be  further  clarified  by  reference  to 
Table  XX,  which  shows,  by  means  of  a 
scatter  diagram,  the  relationship  between 
intelligence  test  scores  and  school  grades 
in  a  group  of  480  students.  The  numbers 
in  each  box  or  cell  of  the  scatter  diagram 
represent  the  number  of  people  who  fall 
Avithin  each  categoi'y  or  class  inten'al  with 
reference  both  to  intelligence  score  and  to 
school  gTades.    We  can  see  at  once  from  the 


Shows  the  percentage  o£  men  receiving  an  above- 
average  grade  in  tank  mechanics  course  in  relation 
to  score  on  the  .\rmv  General  Classification  Test. 
The  relationship  between  school  grade  and  per- 
formance in  tank  mechanics  course  is  included  for 
comparative  purposes.  [From  E.  G.  Boring  iTd.^. 
Psychology  for  the  armed  sen-ices.  Infantry  Journal, 
1945,  p.  251.] 


398 


Individual  Differences 


diagram  that  correlation  is  positive  and 
neither  zero  nor  +1.00.  The  upper  left  and 
lower  right  corners  of  the  table  are  empty. 
There  are  no  children  with  very  high 
school  grades  and  very  low  intelligence, 
nor  with  very  low  grades  and  very  high 
intelligence.  Still  there  is  a  great  deal  of 
scattering;  we  could  not  predict  school 
grades  accurately  from  intelligence  scores, 


nor  conversely.  Actually  the  coefficient  of 
correlation  for  this  table  is  r  =  +0.460. 
That  is  moderately  high,  yet  far  from  per- 
fect. 

A  glance  at  Table  XX  as  a  whole  im- 
mediately reveals  the  fact  that  the  subjects 
tend  to  cluster  in  an  area  of  the  table 
which  extends  diagonally  from  lower  left 
to  upper  riglu.     This  means  (hat,  in  gen- 


TABLE  XIX 

Scatter  Diagram  for  a  Low  Correlation 

r  =  +0.128        A^  =  216  cases 


Mental  Age 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

in 

o 
'5 

a 

u 

4.3-45 

1 

40^2 

37-39 

1 

1 

34-36 

1 

2 

1 

31-33 

1 

1 

28-30 

2 

2 

1 



25-27 

1 

2 

2 

3 

1 

2 

22-24 

1 

2 

1 

1 

2 

2 

19-21 

1 

4 

3 

4 

1 

16-18 

1 

2 

3 

4 

2 

2 

1 

13-15 

2 

3 

4 

6 

1 

1 

10-12 

1 

2 

7 

6 

7 

4 

1 

7-  9 

1 

7 

6 

11 

7 

3 

1 

1 

4-  6 

1 

1 

11 

13 

12 

7 

4 

1 

1 

0-  3 

1 

5 

4 

4 

4 

1 

1 

I 

The  Correlation  Coeffic/en/ 


399 


TABLE  XX 

ScArrF.R  Diagram  for  a  Corrklation  of  Intkrmkoiatk  Value 
r  =  +0.460        A^  =  480  cases 


Infelligence  Test  Scores 

School 

• 

Grades 

Below 

85 

85-89 

90-94 

95-99 

100-104 

105-109 

110-114 

115-119 

120-124 

Above 
124 

90  and  over 

3 

3 

15 

12 

9 

9 

5 

85-89 

8 

17 

15 

24 

13 

6 

6 

80-84 

4 

6 

22 

21 

20 

10 

5 

1 

75-79 

7 

25 

33 

23 

10 

7 

4 

70-74 

4 

10 

18 

14 

22 

12 

1 

1 

65-69 

1 

3 

3 

12 

7 

8 

8 

1 

60-64 

2 

5 

3 

1 

1 

oral,  those  students  who  received  poorer 
grades  (lower  part  oi  the  table)  also  had 
relatively  low  intelligence  test  scores  (left 
part  of  the  table),  and  those  receiving  good 
grades  tended  to  score  higher  on  the  intelli- 
gence test.  For  the  correlation  to  be  a  per- 
fect +  1.00,  however,  all  entries  would  be 
in  a  single  diagonal  row,  a  relation  ap- 
proximated in  Table  XXI,  where  the  cor- 
relation is  +0.994. 

Further  light  on  the  meaning  of  a  coeffi- 
cient of  correlation  is  obtained  by  compar- 
ing Tables  XIX,  XX  and  XXI,  which 
show  the  scatter  diagrams  for  correlations 
of  +0.128,  +0.460  and  +0.994,  respectively. 
The  correlation  between  mental  age  and 
mechanical  skill  shown  in  Table  XIX  is 
only  a  little  removed  from  a  random  scat- 
ter. AVe  do  not  take  such  a  correlation 
seriously  unless  it  is  for  a  veiy  large  num- 
ber of  cases,  or  its  lowness  as  such  has  sig- 
nificance. Table  XX,  as  we  have  just  seen, 
shows  a  definite  positive  relation  between 
school  grades  and  intelligence  scores.  This 
is  llic  sort  of  relationshij)  that  keeps  turn- 


ing up;  two  measures  of  ability  vary  to- 
gether, yet  are  by  no  means  identical.  You 
can  say  of  such  abilities  that  they  have  a 
common  factor  and  that  each  also  has  a 
specific  factor.  Table  XXI  shows  a  correla- 
tion that  is  nearly  +1.00.  It  means  that  the 
two  measures  are  measuring  practically  the 
same  thing.  We  can  see  how  that  is,  when 
we  note  that  the  table  gives  the  correla- 
tion between  raw  Alpha  test  scores  and 
weighted  Alpha  test  scores.  The  scores 
were  supposed  to  have  been  improved  by 
the  use  of  statistical  weights,  but  the  table 
shows  that  the  weights  did  little  good. 

The  coefficient  of  correlation  is  negative 
when  high  rank  in  one  ability  is  related 
to  low  rank  in  a  second  ability  (see  Fig. 
199). 

Figure  198  shows  five  scatter  diagrams 
for  different  degrees  of  correlation  varying 
from  r  =  0  to  r  =  1.00.  These  are  actual 
photographs  of  the  way  a  beam  of  elecuons 
varies  at  random  right  and  left,  and  also 
up  and  down,  when  the  variation  is  con- 
trolled I)v  the  random  movements  of  elec- 


400 


Individual  Differences 


TABLE  XXI 

Scatter  Diagram  for  a  High  Correlation 

r  =  -1-0.994        .V  =  2856  cases 


Alpha  Test:  Weighted  Scores 

0-  9 
10-  19 
20-  29 

30-  39 
40-  49 
50-  59 

60-  69 
70-  79 
80-  89 

g;  S  2 

On       a       O 
fN      f*:      tj. 

S   S  £ 

c^     cs     c^ 

00      OS      O 

210-219 
220-229 
230-239 

240-249 
250-259 
260-269 

270-279 
280-289 
290-299 

300-309 
310-319 
320-329 

330-339 
340-349 
350-359 

g  ^  2 

k  i  i 

s  s  s 

O     O     O 
00     Os     O 

a 
< 

180 
175 
170 

■ 

1     1 

165 
160 

155 

1 

1 
3     1 
2 

150 
145 
140 

1 
1 

1     2     1 
3     1 

135 
130 
125 

1 

2 
1    4    4 
4    2 

1 



120 
115 
110 

2     3 

2     2 

4    2    4 

9          1 

2 

2 

105 
100 
95 

1  1 

2  5 
1     9    3 

5     1 
2     1 

90 
85 
80 

1 

5 

6 

4    8    5 

10    7    2 
7          2 
3 

75 
70 
65 

2 

4 

4 

3  116 

14  11    4 
6    4 
2 

60 

55 
50 

1 
2     7    6 

10  15    3 
13    4 
4 

45 
40 

35 

3 

1  2    6 

2  8  13 

4    9    3 
12     3 
6 

30 

25 
20 

3 

1  17 

4  12  15 

10  16    3 
10    8 
2 

15 
10 

3 

21 
1  22  10 

10    9    2 

15 

0-4 

40    9 

The  Correlofion  Coefficient 


401 


•  ### 


r  =  0.00  r  =  0.25  r  =  0.50  r  =  0.75  r=1.00 

riciURE  ig8.     scattkr  diagrams  for  corrki.ations  jrom  r  =-  o  'lo  r=  i.o'i 

Photographs  ol  a  beam  of  elcciroiis  impinging  on  ihe  screen  of  an  osciilostopc.  A  voltage  with  raiuloin 
variation  (the  kind  used  to  produce  white  noises;  see  p.  315)  is  used  to  make  the  beam  vary  at  random 
horizontally.  You  would  then  see  a  horizontal  line.  Similarly  another  random  voltage  makes  the  beam 
vary  vertically.  If  the  two  voltages,  each  varying  randomly  and  having  no  relation  to  each  other,  act 
simultaneously,  the  projected  beam  will  fill  the  field,  producing  the  circular  scalier  diagram  for  r  =  0, 
If  the  same  random  voltage  is  used  at  the  same  time  for  both  horizontal  and  vertical  variation,  you  gel 
the  line  for  the  perfect  correlation,  r  =  1.00.  The  intermediate  diagrams  arc  obtained  by  keeping  .some 
of  the  variation  in  the  two  voltages  independent,  wliile  making  the  remainder  of  the  variation  common  lo 
both  voltages.     [Courtesy  of  J.  C.  R.  Licklider.] 


troiis  in  another  stream.  The  correlation 
is  zero  when  the  right-left  and  np-down 
variations  have  nothing  in  common.  It  is 
{perfect  (+1.00)  when  the  same  random 
variation  controls  both  the  right-left  and 
np-down  movement  of  the  beam.  It  is  in- 
termediate when  the  two  variations  are 
partly  the  same  and  partly  different. 

The  uses  of  correlation  coefficients  in 
psychology  are  many.  In  test  construction, 
the  validity  coefficient  is  the  correlation 
between  test  scores  and  the  criterion  meas- 
ure on  a  group  of  subjects.  Similarly,  the 
reliability  coefficiejiL  is  the  correlation  be- 


tween two  scores  on  tlic  same  test,  obtained 
by  retesting,  parallel  forms,  or  split-half 
procedures.  The  chief  use  of  the  correla- 
tion coefficient  is,  however,  the  determina- 
tion of  the  relationship  between  two  abili- 
ties. Will  ability  to  pass  a  certain  test  pre- 
dict ability  to  do  a  certain  job?  .-Vre  the 
skills  required  in  t-\\'o  different  jobs  the 
same,  similar  or  different?  'When  a  man 
has  learned  one  of  the  jobs,  how  much  of 
the  other  one  has  he  learned?  It  will  be 
by  answering  many  such  questions  that  the 
inventory  of  human  abilities  will  finally 
be  made  out. 


\ 

\\ 

v^ 

;^ 

C) 

() 

/^> 

/ 

r  =  -1.00      r=-0.75      r  =  -0.50      r  =  -0.25       r  =  0.00 


r  =  0.25         r  =  0.50 


r  =  0.75         r  =  1.00 


FIGURE    199.      COEFFICIENTS  OF  CORRELATION   AND   SC.\TTER  DIAGR.\MS 

The  lines  and  ellipses  of  scatter  diagrams  which  show  the  relationships  between  two  variables  for  co- 
efficients of  correlation  from  r=  -1.00  through  r  =  0  to  r=  -1-1.00.  Figure  198  shows  the  correlations 
for  the  actual  photographed  scatter  of  electrons  for  different  degrees  of  correlation.  This  figure  shows 
the  same  relation  with  the  ellipses  computed  mathematicallv  and  indicates  further  the  relation  between 
ncgati\c    and    positive    correlations.      [Courtesy    of    J.   C.    R.   Licklider.] 


402 


Individual  Differences 


INTELLIGENCE    TESTING 

During  the  last  forty  years  the  concept 
of  intelligence  has  grown  and  changed  with 
the  development  of  the  intelligence  tests. 
In  general  intelligence  is  thought  of  as 
general  ability,  a  cointnon  factor  in  a  wide 
variety  of  special  aptitudes.  The  concept 
becomes  clearer  as  the  discussion  continues. 

The  Binet  Tests 

The  first  intelligence  test  was  prepared 
by  the  French  psychologist,  Alfred  Binet. 
In  1904  the  French  Minister  of  Public  In- 
struction appointed  a  committee  to  investi- 
gate the  causes  of  retardation  among  public 
school  children.  Binet  was  a  member  of 
this  committee.  As  a  direct  outgrowth  of 
his  work  on  this  committee,  Binet  pub- 
lished (with  a  collaborator)  the  1905  scale 
for  measuring  intelligence.  This  scale  con- 
sisted of  thirty  problems  arranged  in  an 
approximate  order  of  difficulty.  In  1908 
appeared  Binet's  first  revision  of  the  scale, 
in  which  the  tests  were  grouped  into  age 
levels,  and  he  introduced  the  concept  of 
fnental  age.  In  such  a  scale,  the  tests  are 
assigned  to  'year  levels'  on  the  basis  of  the 
performance  of  representative  groups  of 
children  of  different  ages.  Thus  tests 
passed  as  often  as  not  by  the  8-year-olds 
are  grouped  into  the  8-year  level,  those 
passed  as  often  as  not  by  the  9-year-olds 
into  the  9-year  level,  etc.  A  child's  score 
on  the  scale  is  then  expressed  as  the  men- 
tal age  (M.A.)  that  he  is  able  to  reach.  If, 
for  example,  he  passes  all  tests  assigned  to 
the  10-year  level  and  none  at  the  ll-year 
level,  he  has  a  mental  age  of  10,  regardless 
of  what  his  chronological  age  (C.A.)  may 
be,  because  he  has  succeeded  as  well  as 
the  average  10-year-old  and  no  better.  It 
his  C.A.  is  8.  such  a  child  would  be  two 
years    accelerated    in    his    intellectual    per- 


formance; if  he  is  11  years  old,  he  would 
be  one  year  retarded. 

The  Binet  tests  have  been  translated  into 
more  than  a  do/en  languages,  and  their  use 
has  spread  to  every  continent.  In  America 
five  independent  revisions  have  appeared, 
of  which  the  best  known  is  the  Stanford- 
Binet,  prepared  by  L.  M.  Terman  and  his 
associates  at  Stanford  University.  In  his 
first  revision  of  the  Binet  scale,  appearing 
in  1916,  Terman  increased  the  number  of 
tests,  substituted  some  new  tests  for  less  suit- 
able ones  in  the  original  scale,  and  revised 
others.  The  scale  was  readjusted  on  the 
basis  of  American  norms.  The  most  far- 
reaching  innovation  in  this  revision,  how- 
ever, was  the  introduction  of  the  concept 
of  the  Ititellige)ice  Qiiotient  (IQ).  The  IQ 
is  the  ratio  of  Mental  Age  to  Chronologi- 
cal Age,  multiplied  by  100  to  get  rid  of 
decimals.  IQ  =  lOOM.A./C.A.  Thus,  if  a 
child  of  10  passes  the  12-year  level,  he  will 
have  an  IQ  of  100  X  12/10  =  120.  If  he 
just  passes  his  normal  level  for  10  years,  his 
IQ  will  be  100  X  10/10  =  100.  If  he  can 
pass  the  9-year  level  and  no  more,  then  he 
is  retarded  with  an  IQ  of  100  X  9/10  =  90. 

The  chief  advantage  of  the  IQ,  as  con- 
trasted with  a  statement  of  mental-age  re- 
tardation or  acceleration  as  used  by  Binet, 
is  its  comparability  at  different  ages.  An 
IQ  of  100  means  a  normal  performance 
regardless  of  the  child's  age;  IQ's  of  80  or 
120  represent  comparable  degrees  of  retar- 
dation and  acceleration,  respectively,  at  all 
ages.  In  terms  of  M.A.,  however,  a  retarda- 
tion of  one  year  in  a  4-year-old  child 
(IQ  =  75)  is  a  more  serious  degree  of  back- 
wardness than  a  retardation  of  one  year 
in  a  12-year-old  (IQ  =  92).  This  follows 
from  the  fact  that  intellectual  development 
is  more  rapid  during  early  life  and  exhibits 
a    gradual    slowing   down    with    increasing 


The  Binet  Tests 


403 


age.  Tlierc  is  a  more  marked  diHerence 
between  the  behavior  ol  the  average  3-year- 
olds  and  4-year-olds  than  there  is  between 
11-year-olds  and  12-year-olds.  Actually,  the 
child  who  is  retarded  one  year  at  the  age 
of  4,  is  likely,  when  retested  at  age  12,  to 
be  found  to  be  three  years  retarded 
(IQ  =75).  Under  these  circumstances,  the 
IQ,  being  a  relative  measure,  remains  con- 
stant. It  is  clear  that  mental-age  deviations 
from  the  norm  increase  with  age  and  that 
the  IQ  tends  to  remain  approximately 
constant  throughout  life,  provided  that  the 
individual  is  not  subjected  to  drastic  en- 
vironmental changes  or  other  unusual  con- 
ditions. 

On  most  intelligence  scales  of  the  Binet 
type,  the  average  individual  does  not  im- 
prove in  performance  with  age  beyond  15 
years.  The  average  22-year-old  or  30-year- 
old  would  thus  do  no  better  on  the  Stan- 
ford-Binet  test  than  the  average  15-year- 
old.  For  this  reason,  in  computing  the  IQ 
of  an  adult  on  such  a  test,  the  C.A.  is  taken 
arbitrarily  as  15.  That  is  because  the  M.A. 
of  the  average  adult  is  15.  That  creates  a 
complication.  An  M.A.  of  12  is  the  aver- 
age performance  for  persons  12  years  old. 
An  M.A.  of  18  is  not  the  average  perform- 
ance of  persons  18  years  old.  Persons  18 
years  old  have  an  M.A.  of  15,  the  M.A. 
of  the  average  adult.  An  M.A.  of  18 
means  merely  that  statistical  analysis  indi- 
cates such  a  person  to  be  about  as  much 
brighter  than  a  person  with  an  M.A.  of 
15,  as  the  M.A.  =  15  is  brighter  than 
M.A.  =  12. 

There  are,  in  these  scales,  three  "Superior 
Adult"  levels  (S.A.I,  S.A.  II  and  S.A.  Ill) 
of  increasing  difficulty.  Mental  ages— and 
the  IQ's  derived  from  them— are  not,  how- 
ever, well  suited  to  testing  adults.  Other 
types   of  scores,    such    as    percentiles,    and 


other  sjjecially  designed  tests,  arc  more 
coiTunonly  used  in  the  testing  of  adults. 
The  Stanlord-Binet  itself  has  undergone 
repeated  revisicjn.  Its  latest  revision,  the 
Terman-Merrill  Scale,  appeared  in  1937. 
The  content  of  the  Stanford-Binet  exami- 
nation samples  a  wide  variety  of  intellec- 
tual functions  in  the  effort  to  arrive  at  the 
sul)jcct's  'general  mental  level.'  A  few 
examples  will  suggest  the  range  covered. 
At  the  lower  age  levels  many  of  the  tests 
involve  the  manipulation  or  identification 
of  objects;  the  standard  materials  employed 
in  such  tests  are  reproduced  in  Fig.  200. 
For  example,  at  the  2-year  level  the  child 
identifies,  by  pointing,  small  toy  objects 
such  as  cat,  button,  thimble  and  cup,  as 
the  examiner  names  each  object.  At  a 
slightly  higher  level,  similar  objects  (tov 
cup,  shoe,  penny)  are  identified  in  term>> 
of  use,  the  examiner  saying,  "Show  me 
what  we  drink  out  of,"  "Show  me  what 
goes  on  our  feet,"  etc.  Identification  oi 
pictures  of  objects  in  terms  of  use  or  other 
characteristics  occurs  at  the  4-year  le\el. 
Memory  tests  are  included  at  several  levels, 
involving  objects,  pictures,  numbers,  words, 
sentences  and  the  content  of  a  passage. 
A  vocabulary  test,  consisting  of  45  words 
steeply  graded  in  difficulty,  from  orange 
and  envelope  to  homuncidus,  sudorific  and 
parterre^  extends  from  the  6-year  level  to 
Superior  Adult  level  III.  Naming  simi- 
larities among  objects  is  also  found  at  sev- 
eral levels;  for  example,  "In  what  way  are 
wood  and  coal  alike?"  (year  MI):  "In  what 
way  are  a  teacher,  a  book  and  a  newspaper 
alike?"  (year  XI);  "What  is  the  principal 
way  in  which  farming  and  manufacturing 
are  alike?"  (S.A.  I).  The  detection  of  ab- 
surdities in  pictures  and  in  short  passages 
likewise  appears  at  various  year  levels.  For 
example,  a  9-year-old  should  be  able  to  sav 


404 


Individual  Differences 


FIGURE   200.      SOME   MATERIALS  USED   IN   ADMINISTERING  THE   STANFORD-BINET   INTELLIGENCE   SCALE   AT 

THE  YOUNGER  AGE  LEVELS 

[Materials  used  by  L.  M.  Teiman  and  M.  A.  Merrill,   The   new   revised  Slanford-Biuet    lesls   of   intelli- 
gence, Houghton  Mifflin,  1937.] 


what  is  foolish  about  this  statement:  "In 
an  old  graveyard  in  Spain  they  have  dis- 
covered a  small  skidl  which  they  believe 
to  be  that  of  Christopher  Columbus  when 
he  was  about  ten  years  old."  Similarly,  an 
11-year-old  should  be  able  to  detect  the 
absurdity  in  the  following:  "When  there 
is  a  collision  the  last  car  of  the  train  is 
usually  damaged  most.  So  they  have  de- 
cided that  it  will  be  best  if  the  last  car 
is  always  taken  off  before  the  train  starts." 


Group  Testing 

The  Binet  type  of  test  is  known  as  an 
individual  test  since  only  one  subject  can 
be  tested  at  a  time.  Because  of  the  com- 
plexity of  directions  and  scoring,  further- 
more, the  administration  of  such  tests  re- 
quires a  highly  trained  examiner.  As  long 
as  this  was  the  only  type  of  available  in- 
telligence test,  large-scale  testing  programs 
were  not   feasible.     It  is  undoubtedly  the 


Group  Testing 


405 


development  ol  grotip  tests  of  irUclligcncc 
vvhidi  is  largely  responsil)le  for  the  wide- 
spread popidarity  of  mental  testing.  Group 
tests  are  not  only  designed  for  the  simul- 
taneous testing  of  large  groups,  but  their 
administration  has  also  been  so  simplified 
as  to  require  relatively  little  training  for 
the  examiner.  Scoring  has  also  been  higlily 
simplified,  some  of  the  tests  being  adapted 
for  scoring  by  electrical  machine. 

The  immediate  stimulus  which  led  to 
the  development  of  the  first  group  test  of 
intelligence  was  furnished  by  the  urgent 
need  for  testing  soldiers  in  the  United 
States  Army  during  the  First  World  War. 
A  quick,  rough  classification  of  the  men 
with  respect  to  intelligence  was  needed 
for  many  purposes,  including  discharge  for 
mental  defect,  assignment  to  special  bat- 
talions demanding  a  relatively  low  level 
of  ability  and  selection  for  officer  training. 
The  test  designed  to  meet  this  need  was 
the  well-known  Army  Alpha.  Many  revi- 
sions of  this  test  have  been  prepared  in 
the  intervening  years,  and  its  latest  revi- 
sions are  still  used  today  for  civilian  testing. 

Alpha  established  a  pattern,  in  both  pro- 
cedure and  content,  which  has  been  closely 
followed  in  most  group  intelligence  tests. 
On  Alpha,  as  well  as  on  most  other  group 
scales,  perfonnance  is  usually  expressed  in 
terms  of  percentiles  or  some  other  similar 
score  which  indicates  in  a  convenient  and 
comparable  unit  the  subject's  position  rela- 
tive to  a  group  average. 

Among  the  best-known  intelligence  tests 
for  general  adults  is  the  Otis  Self-Adminis- 
tering Test  of  Mental  Ability  (Otis  S.A.). 
In  this  test  the  role  of  the  examiner  is  re- 
duced to  a  minimum  since  all  necessary 
directions  are  printed  on  the  test  booklet. 
The  examiner  is  needed  only  to  see   that 


jjrojxr  testing  conditifiiis  arc  maintained 
and  to  give  the  starting  and  stoj;ping  sig- 
nals for  the  entire  test. 

The  student  is  probably  already  fann'jiar 
with  at  least  one  of  the  tests  which  have 
been  especially  designed  for  college  fresh- 
men. Tlie  American  Council  Psychological 
PIxarnination,  prepared  under  the  auspices 
of  the  American  Council  on  Education, 
and  the  Scholastic  Aptitude  Test  of  the 
College  Entrance  Examination  Board  arc 
among  the  most  widely  used.  A  new  form 
of  such  tests  is  prepared  each  year,  and 
norms  are  computed  for  the  several  thou- 
sand college  freshmen  who  are  tested 
throughout  the  country  every  year. 

During  the  Second  World  War,  the 
United  States  Army  developed  the  Army 
General  Classification  Test  (AGCT),  which 
was  used  in  place  of  Alpha  of  the  First 
World  War.  This  test  provided  a  means 
of  classifying  the  men  roughly  according 
to  their  general  ability  to  learn  the  \arious 
duties  required  in  military  life.  It  was 
prepared  in  four  equivalent  interchange- 
able forms,  each  requiring  about  one  hour, 
including  preliminary  instructions,  a  fore- 
exercise  and  the  test  proper  given  -^vith  a 
40-minute  time  limit.  The  test  involved 
verbal,  numerical  and  spatial  skills,  ha\- 
ing  its  items  ananged  in  order  of  difficulty. 
Upon  arrival  at  a  reception  center,  each 
man  who  could  read  English  was  given  one 
of  the  four  forms  of  the  AGCT.  On  the 
basis  of  his  performance,  he  was  classified 
into  one  of  five  Army  Grades.  His  score 
was  also  recorded  on  his  Qualification  Card 
in  tenns  of  a  standard  scale  in  whicli  100 
represents  the  average  score  of  men  of  mili- 
tary age.  The  scores  on  this  scale  corre- 
sponding to  each  of  die  five  grades  are  as 
follows: 


406 


Individual  Differences 


I  130  and  over 

II  110-129 

III  90-109 

IV  70-89 
V  below  70 

A  more  analytical  score  could  be  ob- 
tained by  means  of  a  later  form  of  the 
AGCT  test,  recjuiring  two  hours  and  yield- 
ing separate  scores  in  (1)  verbal  ability, 
(2)  spatial  comprehension.  (3)  arithmetic 
computation  and  (4)  arithmetic  reasoning. 

Performance  and  Nonlanguage  Tests 

Early  in  the  history  of  intelligence  test- 
ing, psychologists  began  to  realize  that  the 
Binet  type  of  test,  depending  so  largely 
upon  language,  is  not  suited  to  all  types 
of  persons.  The  testing  of  illiterates,  the 
foreign-speaking,  the  deaf  or  those  who 
have  speech  disabilities  requires  a  differ- 
ent kind  of  test.  Performance  tests  were 
designed  to  meet  this  need.  Among  the 
earliest  was  the  Pintner-Paterson  Scale 
(Fig.  201),  consisting  of  fifteen  tests  which 
can  be  administered  without  the  use  of 
language,  oral  or  written,  on  the  part  of 
either  examiner  or  subject.  Blocks,  pic- 
tures of  simple  objects  or  scenes  and  geo- 
metric forms  are  the  principal  materials 
of  these  tests.  In  picture  completion  tests, 
for  example,  the  subject  inserts  irregularly 
shaped  blocks  into  a  board  to  complete  a 
picture,  much  in  the  manner  of  a  jig-saw 
puzzle.  Form-board  tests,  involving  the 
insertion  and  assembling  of  variously 
shaped  blocks  to  fill  in  recesses,  vary  from 
those  simple  enough  for  a  preschool  child 
to  some  which  will  baffle  the  average  col- 
lege student.  Most  of  these  tests  are  scored 
in  terms  of  time  required  to  complete  the 
task,  as  well  as  number  of  errors.  The 
scores  can  be  interpreted  as  M.A.  and  IQ 
or  as  percentiles. 


A  more  recently  standardized  perform- 
ance test  is  the  Arthur  Perfonnance  Scale, 
consisting  of  ten  of  the  original  Pintner- 
Paterson  tests,  a  series  of  paper  maze  tests 
and  a  block  design  test  in  which  the  sub- 
ject duplicates  with  colored  blocks  the  de- 
signs on  a  series  of  printed  cards.  All  per- 
formance tests  are  by  their  very  nature  in- 
dividual tests.  Besides  their  usefulness  in 
testing  subjects  with  a  language  handicap, 
they  are  also  sometimes  employed  to  sup- 
plement the  Binet  type  of  test  in  order 
to  achieve  a  better-rounded  picture  of  the 
individual's  abilities. 

A^oulanguage  scales  are  group  scales  for 
testing  persons  incapable  of  taking  the 
usual  intelligence  scales.  Unlike  perform- 
ance tests,  they  involve  the  use  of  paper  and 
pencil  rather  than  the  manipulation  of 
objects.  They  do  not,  however,  require 
the  ability  to  read  or  write  anything  but 
single  digits.  The  subject  uses  a  pencil 
merely  to  underline,  cross  out  or  connect 
items,  or  to  make  other  nonlinguistic 
marks.  The  directions  are  given  by  black- 
board demonstrations,  charts,  gestures  and 
pantomime.  As  with  the  Alpha,  speed  of 
performance  contributes  to  the  score,  since 
each  test  is  given  with  a  time  limit  too 
short  to  permit  any  but  the  very  fastest  to 
complete  it.  Special  nonlanguage  tests 
for  the  illiterate  and  foreign-speaking  sol- 
diers were  also  developed  for  use  in  the 
Second  World  A\^ar. 
/  No  one  has  as  yet  succeeded  in  creating 
a  good  international  or  so-called  ctdture- 
free  test.  All  the  tests  depend  upon  lan- 
guage and  other  ideas  peculiar  to  the  par- 
ticular culture  for  which  the  test  was  con- 
structed. Until  such  tests  are  made,  how- 
ever, it  is  not  possible  safely  to  use  test 
results  to  compare  the  'intelligence'  of  dif 
ferent  nations  or  'races.' 


Performance  and  Nonlanguage  Tests 


407 


iU^I^Mtfll^ 


f2D 


v^Kt 

\ 

wiri 

BmasB, 


FIGIIRK    aoi.      MATERIALS   FOR  ADMINISTERING   THE    PINTNER-PATERSON    PERFORMANCE    SCALE 

fFiom  C.  H.  Stoelting,  Catalogue  of  apparatus,  tests  and  supplies,  1939,  p.  172.] 


408 


Individual  Differences 


Testing  Infants  and  Preschool  Children 

A  recent  development  in  mental  testing 
is  the  construction  of  scales  for  nxeasuring 
the  intelligence  of  very  young  children, 
some  scales  extending  down  almost  to 
birth.  Infant  tests,  covering  the  period 
from  birth  to  about  fi/^  years,  are  often 
essentially  a  series  of  developmental  norms 
which  can  be  applied  to  an  evaluation  of 
the  child's  everyday  behavior  in  such  activ- 
ities as  crawling,  walking,  sitting  up,  stand- 
ing, picking  up  and  manipulating  objects, 
recognizing  colors  and  shapes  and  acquir- 
ing the  use  of  language.  Among  the  most 
accurately  established  and  extensive  norms 
are  those  prepared  by  Gesell  and  his  co- 
workers at  Yale,  where  hundreds  of  infants 
have  been  periodically  examined  in  prac- 
tically every  type  of  behavior  under  care- 
fully controlled  conditions   (p.   78). 

Preschool  tests,  generally  designed  for 
children  between  the  ages  of  1^4  ^^^  5- 
present  the  child  with  simple,  standardized 
tasks.  Many  involve  motor  coordination, 
as  in  throwing  a  ball,  folding  paper,  cut- 
ting with  scissors,  inserting  buttons  in  but- 
tonholes and  copying  simple  geometric 
figures  such  as  circles  and  crosses.  Some  of 
them  test  the  development  of  perceptual 
skills,  as  in  color  and  form  matching,  recog- 
nizing oneself  in  a  mirror,  identification  of 
pictures  and  picture  completion.  Execut- 
ing simple  commissions,  as  in  response  to 
the  directions  to  "take  the  box  from  the 
table  and  put  it  on  the  chair,"  as  well  as 
simple  tests  of  memory  and  learning,  are 
also  used. 

Infant  and  preschool  tests  ha\e  proved 
highly  sensitive  in  detecting  individual  dif- 
ferences in  behavior,  wide  differences  in 
score  being  revealed  even  among  the  young- 
est subjects  tested.  These  tests  fiunish  an 
effective  practical   technique   for   the   com- 


parison of  the  developmental  status  of  any 
given  child  with  the  norms  for  his  own 
age.  The  use  of  scores  obtained  below 
the  age  of  6  for  the  prediction  of  later 
'intelligence'  is,  however,  regarded  as  ques- 
tionable by  most  psychologists.  In  general, 
follow-up  studies  have  as  yet  failed  to  sub- 
stantiate the  predictive  value  of  such  meas- 
ures. 

Evaluation  of  Intelligence  Tests 

To  make  the  most  effective  use  of  intel- 
ligence tests,  we  must  be  clearly  aware  of 
what  not  to  expect  as  well  as  ^v'hat  to  expect 
of  them.  Only  with  the  full  recognition 
of  such  limitations  can  we  determine  when 
to  use  the  tests  and  how  to  interpret  the 
results.  The  rapid  popularization  result- 
ing from  the  development  of  easily  ad- 
ministered group  scales  dtuing  the  First 
World  War  was  inevitably  followed  by 
skepticism  since  many  fantastic  expecta- 
tions remained  unfulfilled.  Nevertheless 
the  proved  value  of  such  tests  as  the  AGCT 
in  the  Second  World  War  attested  to  the 
fundamental  soundness  of  intelligence  tests 
when  properly  applied. 

The  first  consideration  in  interpreting 
intelligence  test  scores  is  to  remember  that 
no  intelligence  test  measures  native  capac- 
ity independently  of  the  individual's  back- 
ground of  experience.  Only  insofar  as  the 
testees  have  had  common  opportimities  for 
acquiring  the  same  general  information  and 
skills  can  the  differences  in  test  scores  be 
diagnostic  of  futtire  performance.  An  in- 
teresting illustration  of  this  fact  is  offered 
by  some  of  the  results  obtained  with  the 
United  States  Army's  Special  Training 
Units  in  the  Second  'World  War.  Follow- 
ing an  intensive  twelve-week  course  of  in- 
strtiction  in  these  units,  many  men  ^vhose 
initial  AGCT  score  placed  them  in  Army 
Grade  V  were  able  to  raise  their  standing 


Evaluation  of  Infelligence  Tests 


409 


to  Army  Grade  IV  or  even  higher.  Most 
of  the  men  selected  lor  such  training  were 
either  illiterate  or  had  a  very  interior  edu- 
cational background.  Had  the  initial 
classification  oi  these  men  been  regarded 
as  an  index  of  their  'native  intellectual 
capacity'  without  reference  to  their  poor 
education  and  other  experiences,  the  pos- 
sibility of  raising  them  to  Grade  IV  level 
would  have  been  overlooked. 

In  constructing  any  intelligence  test,  the 
effort  is  made  to  include  only  materials 
which  are  common  to  the  experience  of  all 
individuals  to  be  tested,  so  that  everyone 
will  at  least  have  had  the  opportunity  to 
acquire  the  necessary  information  in  the 
course  of  his  evei'yday  experiences.  Care  is 
exercised  to  avoid  special  information  or 
skills  which  are  not  available  to  all  sub- 
jects. On  the  other  hand,  it  is  obvious 
that  the  common  knowledge  vipon  which 
intelligence  tests  are  based  is  common  only 
within  certain  limits.  It  follows  that,  to 
have  full  diagnostic  significance,  intelli- 
gence tests  should  be  given  only  to  persons 
whose  backgrounds  are  similar  to  the  back- 
ground of  the  group  by  which  the  test 
was  standardized.  Only  in  that  way  can 
the  effect  of  previous  experience  be  held 
sufficiently  constant  or  be  ruled  out  for 
practical  purposes.  It  follows  also  that  in 
interpreting  any  intelligence  test  score, 
knowledge  of  the  subject's  education,  socio- 
economic level  and  similar  environmental 
conditions  is  essential. 

A  second  consideration  is  that  no  intelli- 
gence test  samples  all  intellectual  functions 
to  an  equal  degiee.  Most  tests  are  over- 
loaded by  one  or  two  types  of  ability. 
Tests,  such  as  the  Binet,  the  National  Intelli- 
gence Test  and  the  Otis,  are  predominantly 
verbal  or  linguistic  in  content,  with  some 
dependence  on  numerical  ability,  but  mak- 
ing little  if  any  use  of  spatial  or  mechanical 


insight.  It  is  for  this  reason  that  routine 
clerical  workers,  for  example,  frequently  do 
better  on  such  tests  of  'intelligence'  than 
persons  in  high-grade  mechanical  jobs 
which  require  considerable  judgment  and 
originality.  In  brief,  most  of  the  'intelli- 
gence' tests  are  in  large  measure,  though 
not  entirely,  tests  of  verbal  aptitude. 

An  examination  of  the  criteria  against 
which  intelligence  tests  are  validated  pro- 
vides illuminating  data  on  what  it  is  tliat 
such  tests  are  actually  measuring.  One  of 
the  most  common  criteria  is  school  achieve- 
ment. If  those  individuals  receiving  high 
test  scores  do  well  in  school  and  those  re- 
ceiving low  test  scores  do  relati\ely  poorly, 
we  conclude  that  the  intelligence  test  in 
question  has  high  validity.  This  means, 
of  course,  that  the  test  is  effective  in  pre- 
dicting scholastic  aptitude  or  those  abilities 
which  are  important  for  success  in  school 
work.  The  verbal  nature  of  so  much  of 
our  school  instruction  is  undoubtedly  an 
important  factor  in  this  correlation. 

We  should  also  note  that  not  all  tests 
labeled  'intelligence'  measure  the  same 
combination  of  abilities.  Performance  and 
nonlanguage  tests,  for  example,  stress  spa- 
tial insight  to  a  greater  extent.  It  is  not 
enough  to  know  a  child's  IQ.  "We  must 
also  know  on  what  test  it  was  obtained. 
It  is  entirely  possible  for  the  same  child 
to  receive  a  high  IQ  on  one  occasion  and  a 
considerably  lower  one  on  another,  not  be- 
cause the  tests  are  unreliable  or  because 
the  individual's  intellect  fluctuates  hap- 
hazardly, but  because  different  abilities 
were  measured  on  the  t^vo  occasions  by 
different  tests. 

Finally,  we  may  ask  why  intelligence 
tests  are  not  designed  to  coAer  equally  all 
the  individual's  abilities.  "Would  this  not 
give  us  the  'general  mental  level"  which 
would  enable  us  to  make  predictions  in  all 


410 


Individual  Differences 


situations?  To  a  certain  extent,  as  more 
information  was  acquired  regarding  the 
organization  of  abilities,  this  has  been  done. 
For  example,  the  inclusion  of  equal  parts 
of  materials  for  assessing  verbal,  numerical 
and  spatial  abilities  in  the  AGCT,  as  con- 
trasted with  the  predominantly  verbal  con- 
tent of  the  old  Army  Alpha,  was  a  move 
in  this  direction.  The  solution,  however, 
is  not  so  simple  as  it  might  seem.  In  the 
first  place,  for  a  number  of  purposes  an 
intelligence  test  which  is  overloaded  with 
certain  functions,  such  as  verbal  ability,  is 
more  diagnostic  than  one  which  samples  all 
functions  equally.  The  classification  of 
school  children,  the  selection  of  college 
applicants,  the  evaluation  of  probable  em- 
ployee success  in  many  types  of  positions, 
for  example,  are  themselves  largely  depend- 
ent upon  a  knowledge  of  the  individual's 
verbal  ability.  A  test  which  reflects  the 
same  disproportionate  representation  of 
abilities  will  have  higher  validity  in  such 
situations. 

A  further  point  is  that  a  single  score 
indicating  the  average  or  general  level  of 
all  the  individual's  abilities  is  not  enough. 
For  the  most  effective  educational  or  voca- 
tional guidance,  for  selection  of  employees 
and  in  similar  practical  problems,  it  is 
necessary  to  know  also  the  individual's 
strong  and  weak  points.  Two  testees  with 
identical  IQ's  or  percentile  scores  may 
have  very  different  patterns  of  abilities  and 
disabilities,  since  the  differences  balance  out 
and  disappear  in  the  total  score.  The  in- 
creasing use  of  intelligence  tests  which 
yield  partial  scores  is  one  solution  for  this 
problem.  For  example,  both  the  American 
Council's  Psychological  Examination  and 
the  Scholastic  Aptitude  Test  of  the  College 
Entrance  Examination  Board  now  report 
separate  scores  for  verbal  and  numerical 
abilities   for   each   student.     The   develop- 


ment of  the  later  AGCT,  which  yields  four 
separate  scores,  has  already  been  described. 
Another  solution  is  the  use  of  special 
aptitude  tests  to  supplement  the  prelim- 
inary screening  and  classification  provided 
by  the  intelligence  tests.  These  tests  are 
discussed  in  the  following  section. 

MEASUREMENT    OF    SPECIAL 
APTITUDES 

Tests  of  special  aptitudes  are  now  regu- 
larly employed  in  individual  guidance  as 
well  as  in  industrial  personnel  selection. 
Although  a  general  intelligence  test  is  given 
as  a  preliminary  instrument  of  classification 
for  most  jobs,  such  a  measure  is  nearly  al- 
ways supplemented  with  more  specific  test- 
ing in  especially  relevant  areas.  Many  of 
these  tests  are  tailor-made  for  the  particu- 
lar job  and  are  validated  locally  through 
a  direct  follow-up  of  a  typical  group  of 
new  employees.  The  United  States  Army 
and  Navy  also  made  much  more  extensive 
use  of  special  ability  tests  in  the  Second 
World  War  than  in  the  First,  when  such 
tests  were  almost  nonexistent.  Special  bat- 
teries or  combinations  of  tests  were  con- 
structed for  pilots,  bombardiers,  range- 
finder  operators,  radio  operators  and  scores 
of  the  other  specialized  occupations  of  mod- 
ern warfare.  Tests  of  mechanical  apti- 
tude, clerical  aptitude,  motor  dexterity, 
speed  of  reaction,  visual  and  auditory  acuity 
under  different  conditions,  perception  of 
distance  or  dej^th  and  radio  code  learning 
were  among  the  special  areas  covered  in 
such  batteries. 

Trait  Variability 

We  have  seen  that  the  recognition  of 
specialized  abilities,  or  differences  within 
the  individual  from  trait  to  trait,  has  im- 
portant   practical    implications    in    the    in- 


Measurement  of  Aptitudes 


411 


tcrprclalloii  of  iiitelJif^ciKc  test  scores  as 
well  as  in  tlic  scj^arale  testing  of  special 
aptitudes.  Such  variation  within  the  in- 
dividual is  known  as  trail  variability.  It 
can  be  readily  seen  by  the  examination  of 
any  individual's  psychograph,  that  is  to 
say,  a  graph  showing  the  subject's  relative 
standing  in  a  series  of  different  tests,  with 
all  scores  reduced  to  such  comparable  units 
as  percentiles  or  mental  ages. 

A  more  jjrecise  way  of  gauging  the  extent 
of  such  variability  is  illustrated  in  the  fol- 
lowing study.  A  group  of  107  high  school 
freshmen  were  given  a  series  of  35  tests, 
some  being  parts  of  standardized  intelli- 
gence tests  and  others  being  special  tests  of 
motor  abilities,  perception,  attention  and 
emotional  characteristics.  All  scores  were 
transmuted  into  the  same  kind  of  units, 
making  direct  comparison  possible  from 
one  test  to  another.  The  extent  of  trait 
variability,  based  upon  the  differences  be- 
tween each  person's  own  average  and  each 
of  his  35  scores,  was  computed  and  was 
found  to  be  almost  as  great  as  the  variations 
in  score  from  one  person  to  another  in  any 
one  test. 

The  study  of  individual  cases  exhibiting 
striking  irregularities  of  mental  develop- 
ment suggests  the  extremes  of  trait  varia- 
bility which  may  occur.  From  time  to 
time,  persons  liave  been  found  who  were 
so  deficient  in  general  intelligence  that 
they  had  to  be  confined  in  institutions 
for  the  feebleminded  but  who  were,  never- 
theless, remarkably  gifted  in  some  one 
trait.  Mechanical  aptitude,  ability  in 
drawing  or  painting,  a  phenomenal  mem- 
ory, arithmetic  proficiency  and  musical 
talent  have  all  been  found  as  exceptional 
abilities  of  persons  who  seemed  in  every 
other  respect  to  be  feebleminded.  There 
are  also  available  descriptions  of  persons 
who  are  not  in  institutions,  who  are  dull  or 


medifjcrc  in  most  resjjec  ts,  but  who  have  a 
special  gift  along  erne  particular  line.  It  is 
also  true  that  a  prcjnounced  deficiency  in 
any  one  of  these  characteristics  can  occur 
in  combination  with  superior  general  in- 
telligence. It  is  noteworthy  that  verbal  or 
linguistic  abilities  are  conspicuously  absent 
from  these  lists  of  special  talents  and  de- 
fects. Good  verbal  ability  does  not  cxcur  in 
individuals  of  very  low  intelligence,  or  defi- 
cient verfjal  ability  in  those  of  high  intel- 
ligence, ff^r  the  reason  that  verbal  ability 
is  closely  associated  with  general  intelli- 
gence, as  assessed  by  intelligence  tests  de- 
veloped in  and  for  our  own  culture. 

Factor  Analysis 

The  method  of  correlation  is  especially 
well  adapted  for  the  study  of  the  relation- 
ships among  traits.  Suppose  you  have  un- 
der consideration  two  abilities,  like  the 
capacities  to  perceive  verbal  analogies  and 
spatial  relations,  and  you  have  for  each  a 
particular  test.  You  wish  to  find  out 
whether  the  particular  abilities  which  each 
test  measures  are  related  to  each  other  or 
independent  of  each  other.  ^Vhat  do  you 
do?  You  give  both  tests  to  a  large  number 
of  persons  whom  you  would  expect  to  vary 
considerably  among  themselves  in  each  of 
these  abilities,  and  then  you  compute  r,  the 
coefficient  of  correlation.  If  r  were  to  come 
out  near  zero,  you  would  conclude  that  vou 
had  been  testing  two  independent  abilities. 
If  r  were  very  high  (in  this  case  it  would 
not  be),  you  would  conclude  that  the  two 
abilities  were  closely  related,  probably 
that  they  both  depended  principally  on 
some  common  factor  like  general  intelli- 
gence. If  r  were  an  intermediate  value— say, 
0.20  to  0.80— you  would  see  that  the  two 
abilities  that  your  two  tests  test  are  related: 
that  they  involve,  perhaps,  more  or  less  of 


412 


Individual  Differences 


some  factor  common  to  both  and,  in  addi- 
tion, two  specific  factors,  each  of  them  in- 
volved in  one  test  and  not  in  the  other. 
This  is  the  simplest  and  usual  correlational 
analysis  of  two  test  abilities:  one  common 
factor  and  two  specific  factors. 

Usually,  however,  we  are  interested  in 
many  more  tested  abilities  than  two.  In 
that  case  we  can  perform  a  general  factor 
analysis.  The  tests  are  paired,  and  r  is 
worked  out  for  every  pair.  If  there  are  n 
tests,  there  will  be  n{n  -  l)/2  pairs  of  them 
-10  r's  of  5  tests,  45  r's  of  10  tests,  190  r's 
of  20  tests.  If  every  test  shows  some  signifi- 
cant positive  correlation  with  every  other 
test— not  at  all  an  unusual  finding— we  have 
evidence  of  the  existence  of  a  general  factor, 
one  which  is  common  to  all  the  abilities 
tested,  as  'intelligence'  has  been  thought 
to  be.  If  several  tests  show  intercorrela- 
tions  with  one  another  and  not  with  the 
remaining  tests,  we  have  evidence  of  the 
existence  of  a  group  factor  common  to  this 
group  of  tests.  A  battery  of  tests  may  in- 
volve quite  a  number  of  group  factors.  A 
test  which  stands  off  by  itself  and  has  only 
low  correlations  with  the  other  tests  gives 
evidence  of  a  specific  factor.  The  princi- 
pal result  of  much  work  with  factor  analysis 
is  finding  that  the  tested  abilities  form 
groups  or  clusters  because  they  involve 
common  gioup  factors. 

The  most  clearly  demonstrated  group 
factors  are  the  verbal,  numerical  and  spa- 
tial. Tests  of  any  one  of  these  skills  or  in- 
sights show  low  correlations  with  the  other 
two,  whereas  two  tests  in  the  same  cate- 
gory show  a  high  correlation.  The  verbal 
factor  is,  as  we  have  seen,  the  most  im- 
portant in  'intelligence'  tests,  although  the 
numerical  and  space-perceiving  abilities 
may  also  be  included,  as  they  were  by  de- 
sign in  .Army  Alpha  and  in  the  AGCT. 


Dynamic  Organization  of 
Mental  Traits 

The  pattern  of  trait  relationships  is  not 
fixed  and  static  but  changes  with  age  and 
probably  Avith  other  conditions.  Preschool 
children,  for  instance,  depend  largely  on  a 
general  factor  for  their  performance  in 
widely  different  tests.  With  advancing  age, 
however,  they  show  more  and  more  spe- 
cialization. In  other  words,  they  use  the 
general  factor  first,  and  then  improve  in 
test  performance  by  adding  group  factors 
to  the  general  factor. 

In  one  investigation,  three  groups  of 
school  children  aged  9,  12  and  15,  respec- 
tively, were  given  tests  of  memory,  verbal, 
numerical  and  spatial  aptitudes  and  of 
motor  speed.  The  correlations  among  all 
these  tests  tended  to  decrease  with  their 
age,  as  is  indicated  by  the  average  ?''s  of 
0.29  for  the  9-year-olds,  0.26  for  the  12- 
year-olds  and  0.14  for  the  15-year-olds. 
Factor  pattern  analyses  showed  a  large 
general  factor  whose  relative  importance 
decreased  consistently  from  ages  9  to  15. 
In  a  second  study,  a  single  gioup  of  school 
children  was  retested  after  three  years  with 
eight  tests  covering  verbal,  numerical  and 
spatial  tasks.  The  correlation  coefficients 
dropped  from  the  first  to  the  second  testing, 
and  the  decrease  was  greater  between  groups 
of  tests  than  within  groups.  Factor  pattern 
analyses  corroborated  these  results.  A  large 
general  factor  was  found  at  both  ages,  but 
its  magnitude  decreased  over  the  three-year 
period. 

Tests  of  college  students  have  repeatedly 
brought  out  large  independent  group  fac- 
tors, with  little  or  no  general  factor  com- 
mon to  all  the  tests. 

Some  evidence  is  also  available  to  indi- 
cate that  these  age  changes  in  factor  pat- 
tern are  not  a  phenomenon  of  maturation 


Measurement  of  Personalify  Characterisfics 


413 


but  the  result  of  the  type  ol  training  which 
tlic  individual  receives.  Thus  it  has  been 
lound  that  in  trait  organization  adults  with 
only  an  elementary  school  education  re- 
semble school  children  more  closely  than 
college  students.  Educational  level  rather 
than  age  appears  to  have  determined  the 
pattern. 

Further  evidence  is  furnished  by  the  fact 
that  it  is  possible  to  alter  the  pattern  of 
trait  relationship  experimentally  within  a 
short  period.  Such  a  change  occurred  in 
one  investigation  in  which  five  tests  (vo- 
cabulary, memory  for  digits,  verbal  reason- 
ing of  the  syllogistic  type,  code  multiplica- 
tion and  spatial  pattern  analysis)  were  ad- 
ministered to  two  hundred  sixth-grade 
school  children.  Instruction  was  then  given 
them  in  the  use  of  special  techniques  which 
would  facilitate  performance  on  the  last 
three  tests  only.  This  instruction  was  simi- 
lar, in  general,  to  that  received  in  the  course 
of  school  work— for  example,  they  were 
taught  computation  short-cuts  in  arith- 
metic. After  thirteen  days,  equivalent 
forms  of  all  five  tests  were  given  them  un- 
der the  same  conditions  as  in  the  initial  test- 
ing. The  intercorrelations  among  the  five 
tests  showed  no  changes  between  the  two 
tests  for  which  no  special  instruction  had 
been  given,  a  slight  change  between  tests 
which  had  had  special  instruction  and  tests 
which  had  not  had  it  and  a  marked  change 
between  the  tests  with  the  special  aids. 
The  relative  importance  of  the  group  fac- 
tors was  altered. 

This  experiment  represents  a  highly  con- 
densed version  of  the  type  of  experience 
to  which  the  child  is  exposed  in  the  coiuse 
of  school  work  and  other  everyday  activi- 
ties. It  is,  therefore,  entirely  possible  that 
factor  patterns  are  determined  in  the  first 
place  by  the  nature  of  such  experiences. 
Under  existing  cultural  conditions,  a  cer- 


tain degree  of  unilormity  of  factor  pat- 
terns is  found  because  of  common  en- 
vironmental conditions.  Traditional  edu- 
cational curricula  and  vocational  classifi- 
cations contribute  to  this  uniformity.  'I'hus 
in  the  young  child  we  find  a  relatively 
large  general  factor  occurring  in  all  the 
types  of  activities  taught  in  the  schools, 
that  is  to  say,  the  so-called  higher  mental 
processes.  As  the  child  grows  older  and 
specialization  is  encouraged,  certain  cul- 
turally determined  differentiations  begin  to 
appear.  Group  factors  are  produced  for 
linguistic,  mathematical  and  mechanical 
skills  and  possibly  for  other  functions.  At 
the  same  time,  the  increasing  identification 
of  the  linguistic  or  verbal  group  factcjr 
with  'general  intelligence'  as  the  individual 
grows  older  is  quite  understandable  in  a 
culture  in  which  language  plays  so  impor- 
tant a  part  in  a  wide  variety  of  fields. 

MEASUREMENT    OF    PERSON- 
ALITY   CH  ARACTERISTI  CS 

Now  we  must  consider  the  ways  of  testing 
those  human  traits  which  are  of  special  im- 
portance in  determining  how  persons  will 
act  toward  one  another. 

What  Are  Personality  Tests? 

The  term  personality  is  sometimes  used 
in  psychology  to  refer  to  the  individual 
considered  as  a  whole,  the  composite  pat- 
tern of  all  his  behavior  characteristics.  A 
narroAver  and  more  common  meaning  of 
the  term  restricts  it  to  those  traits  which 
are  of  chief  importance  in  the  individual's 
relations  to  other  people.  It  is  in  this 
latter  sense  that  the  term  is  used  in  con- 
nection with  personality  tests.  (See  pp.  487  f. 
for  more  on  the  meaning  of  personalir\-.) 
Any  trait  may,  a£  course,  play  an  impor- 
tant part   in   the   individual's   social  rela- 


414 


Individual  Differences 


tions.  To  be  exceptionally  tall  or  short, 
handsome  or  ugly,  or  to  have  very  poor 
motor  coordination,  an  excellent  memory 
for  names  and  faces,  a  flair  for  dealing 
with  mechanical  gadgets  or  a  genius  for 
well-turned  phrases— any  of  these  attributes 
could  be  the  determining  factors  in  a  per- 
son's relations  to  his  fellows.  In  such 
traits,  however,  only  extreme  deviations 
play  a  significant  role  in  social  behavior. 
Those  traits  classified  under  personality  in 
the  more  restricted  sense,  on  the  other 
hand,  play  a  dominant  part  in  the  social 
behavior  of  all  individuals,  and  in  them 
e\en  slight  deviations  from  the  norm  are  of 
paramount  importance. 

Among  the  traits  most  commonly  as- 
sessed by  personality  tests  is  emotional 
stability  or  relative  freedom  from  such 
neurotic  symptoms  as  phobias  (abnormal 
fears),  compulsions,  obsessions,  frequent 
nightmares,  insomnia,  sleep  walking,  shifts 
of  mood  without  apparent  cause,  uncon- 
trolled outbursts  of  temper,  excessive  wor- 
ries and  many  others.  Although  the  aver- 
age person  has  at  some  time  experienced 
a  mild  degree  of  a  few  such  symptoms, 
when  their  number  or  severity  exceeds  a 
certain  'normal'  maximum,  serious  malad- 
justment is  likely  to  result.  Social  traits 
such  as  introversion-extroversion  and  domi- 
nance-submission are  also  commonly  con- 
sidered in  personality  testing.  The  former 
refers  to  the  tendency  to  be  shut  in  or  out- 
going in  your  interests  and  social  relations; 
the  latter,  to  the  tendency  to  dominate  your 
associates  in  face-to-face  situations  or  be 
dominated  by  them.  Tests  have  also  been 
devised  to  measure  character  traits,  such  as 
honesty,  perseverance  and  cooperativeness. 
The  measurement  of  attitudes,  interests  and 
sense  of  values  represents  another  recent 
development  in  personality  testing. 


Construction  of  Personality  Tests 

The  most  widely  popularized  type  of 
personality  tests  is  the  questionnaire.  There 
are  also  the  much-used  projection  tests. 
(These  tests  are  described  on  pp.  495-497.) 

Personality  tests  are  constructed  by  essen- 
tially the  same  principles  as  all  psycholog- 
ical tests.  Norms  are  empirically  estab- 
lished by  giving  the  test  to  a  large  repre- 
sentative group  of  subjects  and  ascertaining 
the  average  score.  A  norm  is,  however, 
neither  an  ideal  nor  a  perfect  score,  nor 
is  it  predetermined.  Thus  the  norm  in  a 
neurotic  inventoi-y  might  be  fifteen  ques- 
tions answered  in  the  neurotic  direction. 
That  would  show  how  normal  neuroticism 
is.  On  the  tests  of  introversion-extraver- 
sion  and  of  ascendance-submission  the 
norm  generally  falls  at  a  point  approxi- 
mately midway  between  the  extremes. 

Besides  adequately  determined  norms, 
personality  tests  must  have  demonstrated 
reliability  in  order  to  be  of  practical  value. 

The  validity  of  personality  tests  is  more 
difficult  to  establish  than  that  of  other 
types  of  tests  because  of  the  difficulty  of 
finding  a  satisfactory  independent  measure, 
or  criterion,  for  most  personality  traits. 
One  technique  for  checking  such  validity 
is  by  correlating  test  scores  with  ratings  by 
associates,  teachers,  job  supervisors  or 
others  who  have  had  an  opportunity  to  ob- 
serve the  subjects  over  an  adequate  period 
of  time.  (See  pp.  492  f.)  In  general,  such 
criterion  ratings  should  be  made  by  more 
than  one  observer  in  order  to  guard  against 
individual  bias  and  other  idiosyncrasies  of 
the  raters.  Similarly,  care  should  be  exer- 
cised to  make  sure  that  the  raters  have  had 
'trait  acquaintance,'  that  is,  that  they  have 
had  the  opportunity  to  observe  the  sub- 
jects in  those  specific  aspects  of  behavior 
covered    by    the    test.       Correlation    with 


Construction  of  Personality  Tests 


415 


psychialric  diagnosis  has  liccn  ciiiployed  in 
validating  certain  tests  of  emotional  nrial- 
adjustment.  Such  a  procedure  is  satisfac- 
tory if  the  criterion  itself  is  based  upon  a 
careful  and  prolonged  follow-up  rather 
than  upon  a  cursory  psychiatric  examina- 
tion which  may  itself  be  no  more  valid  than 
the  test  being  validated.  Correlations  with 
other  personality  tests  have  sometimes  been 
vised  as  an  index  of  validity,  biU  this  pro- 
cedure presupposes  that  the  criterion  itself 
has  previously  been  validated. 

The  method  of  contrasted  groups  is  es- 
sentially based  upon  a  variety  of  criteria 
which  operate  in  the  situations  of  everyday 
life.  Suppose  that  occupational  selection 
is  taken  as  the  'criterion'  and  that  a  test  of 
extraversion  or  sociability  is  given  to,  let 
us  say,  salesmen  and  engineers.  If  the 
salesmen's  scores  are  clearly  higher  than  the 
engineers'  scores,  some  evidence  will  have 
been  furnished  that  the  test  is  valid,  or 
some  information  will  be  gained  about 
salesmen  in  relation  to  engineers,  depend- 
ing upon  which  way  you  think  about  the 
matter.  If  you  are  ready  to  define  socia- 
bility, for  instance,  as  what  salesmen  ex- 
ceed engineers  in,  you  can  validate  the  test 
in  this  way.  Delinquent  and  nondelin- 
quent  children  have  sometimes  been  used  in 
a  similar  way  to  check  the  validity  of  cer- 
tain character  tests.  Or  the  scores  of  neu- 
rotics under  treatment  can  be  compared 
with  those  of  a  matched  normal  group  of 
persons  who  have  never  been  under  psychi- 
atric care,  in  order  to  see  whether  a  test 
or  inventory  really  does  indicate  neuroti- 
cism. 

In  tests  of  neuroticism  or  emotional  in- 
stability, the  frequency  of  a  response  in  a 
normal  group  is  a  further  check  on  ab- 
normality. If  a  particular  'symptom'  or 
response  occurs   in   a   large  percentage  of 


normal  peisoiis,  ifjso  farto  it  raiiiKU  be  ab- 
normal. 

Finally,  there  is  tlie  metliod  of  internal 
consistency.  It  consists  of  a  comparison  of 
the  subjects'  performance  on  each  item  or 
part  of  the  test  with  their  performance  on 
the  test  as  a  whole.  For  example,  the  25 
per  cent  most  introverted  and  the  25  per 
cent  most  exlraverted  subjects  in  the  group 
are  selected  on  the  basis  of  their  total  scores 
on  an  introversion-extraversion  test.  The 
responses  of  these  two  groups  to  each  item 
on  the  test  are  then  compared.  If  a  sup- 
posed characteristic  of  introverted  behavior 
occurs  as  often  among  the  'best'  extraverts 
as  among  the  'best'  introverts,  obviously  it 
should  be  discarded  as  not  being  correctly 
diagnostic.  To  be  retained,  an  'introver- 
sion' item  must  occur  with  significantly 
higher  frequency  in  the  introverted  than  in 
the  extraverted  group.  The  reader  may 
have  already  perceived  a  difficulty  with  this 
method.  To  be  of  any  value,  such  a  check 
of  validity  must  assume  the  complete,  or  at 
least  high,  validity  of  total  scores  on  the 
test,  since  such  scores  actually  constitute 
the  criterion  against  which  indi\idual  items 
are  being  checked.  Actually  all  that  the 
method  does,  as  its  name  implies,  is  to  in- 
crease the  internal  consistency  of  the  test, 
to  make  sure  that  the  different  items  are 
directed  upon  closely  related  characteris- 
tics. A  consistent  test,  ho^vever,  is  more 
likely  to  be  valid  than  an  inconsistent  one. 
At  least  it  is  easier  to  mistake  the  signifi- 
cance of  a  self-contradictory  test  than  of  a 
test  which  always  points  the  same  -svay. 
With  a  consistent  test  there  is  some  mean- 
ing in  defining  the  characteristic  tested  as 
being  'what  the  test  tests.' 

Evaluation  of  Personality  Tests 

There  is  considerable  value  in  personal- 
ity tests,  but,  as  with  all  tests,  there  is  need 


416 


Individual  Differences 


for  caution  in  their  use  and  interpretation. 
In  the  first  place,  most  of  the  terms  used 
in  describing  personality  do  not  correspond 
\  to  clearly  defined  traits  in  the  sense  of  traits 
as  independent  group  factors.  In  fact, 
when  factor  pattern  analyses  of  personality 
test  responses  are  made,  the  traits  which 
emerge  cut  across  the  traditional  classifi- 
cations of  introversion-extraversion,  ascend- 
ance-submission, emotional  adjustment  and 
the  like.  These  categories  have,  neverthe- 
less, been  retained  for  practical  conven- 
ience in  describing  the  social  and  emo- 
tional aspects  of  behavior.  As  such,  how- 
ever, they  do  not  lend  themselves  to  rigid 
and  unambiguous  definition.  Somewhat 
different  areas  of  behavior  may  therefore 
be  designated  when  different  investigators 
use  the  terms  introversion,  dominayxce, 
honesty  or  sense  of  humor. 

The  available  evidence  suggests,  further- 
more, a  greater  specificity  of  behavior  in 
the  realm  of  personality  than  among  intel- 
lectual abilities.  Thus  a  man  may  be  quite 
extraverted  toward  his  business  associates 
and  relatively  introverted  in  his  other  so- 
cial contacts.  In  the  same  way,  in  their 
studies  on  character  traits.  May  and  Harts- 
horne  found  honesty  to  be  specific  to  the 
situation.  The  correlations  between  hon- 
esty in  the  classroom  and  in  out-of-class 
situations,  for  example,  were  very  low. 

Personality  characteristics  are  also 
changeable  with  time.  The  individual's 
shifting  pattern  of  experience  is  reflected 
more  readily  in  his  emotional  than  in  his 
intellectual  behavior.  Changes  in  ability 
do  occur  as  a  person's  environment  changes, 
but  such  alterations  are  slow  and  come 
only  from  drastic  and  prolonged  modifica- 
tions of  environment.  Personality  charac- 
teristics, on  the  other  hand,  may  show  sig- 
nificant variations  following  such  episodes 
as  living  away  from  home  for  the  first  time. 


taking  a  new  job  or  going  from  high  school 
to  college.  For  this  reason,  retests  of  the 
same  individual  over  fairly  long  periods  of 
time  may  reflect  actual  changes  in  behavior, 
not  merely  poor  test  reliability.  It  is  for 
this  reason  also  that  many  questionnaires 
ask  only  about  the  subject's  behavior  dur- 
ing the  past  few  months.  Many  persons 
would  answer  a  particular  question  very 
differently  when  it  refers  to  recent  behavior 
from  the  way  they  would  answer  it  with 
respect  to  their  customary  behavior  up  to, 
for  example,  a  year  before  they  took  the 
test. 

One  of  the  chief  j^ractical  difficulties, 
particularly  in  the  use  of  questionnaires, 
is  their  susceptibility  to  faking,  to  delib- 
erate deception  on  the  part  of  the  subject. 
It  is  undoubtedly  possible  on  such  tests  for 
subjects,  especially  the  brighter  or  better 
educated  ones,  to  falsify  their  responses  in 
the  direction  of  the  impression  they  wish 
to  create.  An  individual  could  make  him- 
self appear  more  neurotic  or  less  neurotic 
than  he  actually  is,  more  dominant  or  more 
submissive,  depending  upon  the  exigencies 
of  the  situation.  Various  partial  solutions 
to  this  problem  have  been  attempted.  One 
technique  is  to  disguise  the  purpose  and 
nature  of  the  test.  In  practically  every  per- 
sonality test  this  is  done  to  a  certain  extent 
by  careful  wording  of  the  instructions,  by 
elimination  of  suggestive  trait  labels  and 
by  keeping  the  subject  in  ignorance  of  the 
way  the  responses  will  be  scored.  When 
only  gioup  results  are  needed,  preserving 
the  anonymity  of  individual  papers  is  a 
way  of  reducing  faking  by  eliminating  the 
principal  motive  for  misrepresentation. 
Similarly,  when  the  test  results  are  to  form 
the  basis  for  advice  and  gviidance,  the  ex- 
aminer can  more  often  count  upon  the 
cooperation  and  truthfulness  of  the  subject 
than  when  the  test  is  being  used  to  select 


Distribution  of  Individual  Differences 


417 


employees,  'llie  indivicliial  will  in  general 
—but  not  always— be  relatively  iruthful 
when  he  is  himself  seeking  help  in  his  per- 
sonal adjustment  or  his  educational  or  vo- 
cational planning. 

Even  when  the  subject  is  cooperative  and 
frank,  his  ability  to  report  his  own  per- 
sonality characteristics  may  be  questioned. 
This  criticism  obviously  applies  especially 
to  the  questionnaire.  It  should,  however, 
be  noted,  first,  that  most  personality  test 
questions  do  not  require  the  subject  to 
judge  or  describe  his  characteristics  but  to 
report  what  he  has  actually  done  in  cer- 
tain situations  in  the  immediate  past.  Fur- 
thermore, the  questions  in  personality  tests 
are  not  so  much  concerned  with  the  appar- 
ent facts  involved  as  with  the  individual's 
reactions  to  them.  For  example,  if  the 
subject  is  asked  whether  his  associates  gen- 
erally treat  him  fairly,  the  real  interest  lies 
in  knowing  whether  he  believes  that  he  is 
treated  fairly. 

It  is  not  wise  in  the  present  day  to  rely 
on  the  results  of  personality  tests  alone 
when  important  decisions  about  human  be- 
ings are  to  be  made.  The  test  scores  aid  the 
diagnostician— be  he  psychiatrist,  psycholo- 
gist or  personnel  expert.  The  results  must 
be  supplemented  by  all  the  other  informa- 
tion which  it  is  possible  to  obtain.  A  can- 
didate for  a  job,  a  person  seeking  advice 
about  choosing  a  profession  or  his  personal 
problem,  a  patient  who  might  conceivably 
turn  out  to  need  institutional  care  or  at 
least  temporary  psychiatric  treatment  is  in- 
terviewed. The  technique  of  the  inter- 
niew  is  well  worked  out,  and  it  supplies  a 
great  deal  of  information  which  supple- 
ments test  results.  When  possible  the  case 
history  is  also  worked  up,  the  details  of  the 
person's  past  life  being  got  from  all  avail- 
able sources.    (These  techniques,  which  are 


beyond    the   scoj>e  ol    the   piesent   chapter, 
are  considered  on   pp.  49.^-497;   5.^9-541.) 

DISTRIBUTION    OF    INDIVID- 
UAL   DIFFERENCES 

We  may  now  turn  our  attention  to  un- 
derstanding how  individuals  vary  with  re- 
spect to  different  traits,  to  the  question  of 
whether  individual  types  exist  and  to  a 
description  of  extreme  degrees  of  intelli- 
gence. 

Frequency  Distributions 

How  are  the  \aiious  degrees  of  psychrj- 
logical  traits  distributed  among  the  gen- 
eral population?  Are  individuals  scattered 
uniformly  over  the  entire  range,  or  do  they 
cluster  at  one  or  more  points?  AVith  what 
relative  frequency  do  the  different  trails, 
abilities  and  other  human  characteristics 
occur?  These  questions  are  answered  for 
any  particular  case  by  dra\\ing  up  a  fre- 
quency distribution. 

Table  XXII  shows  a  typical  frecjuency 
distribution  for  the  scores  of  1000  college 
students  on  a  simple  learning  test.  The 
scores  are  divided  into  class  intervals,  in 
this  test  intervals  of  four  points  each.  The 
frequency  with  which  scores  fall  in  each 
class  interval  is  shown  as  number  of  cases 
and  as  percentage.  In  this  instance,  since 
there  are  1000  cases  altogether,  the  percent- 
age frequency  looks  like  the  case  frequenc\. 
but  ordinarily  you  could  not  be  sure  about 
the  percentages  by  merely  inspecting  the 
numbers  of  cases.  It  is  often  useful  to 
change  cases  into  percentages  in  order  to 
make  different  curves  comparable.  Since 
no  student  obtained  a  score  below  8  or 
above  55,  extreme  class  intenals  do  not 
have  to  be  shown.  Higher  and  lower  scores 
might  have  occurred  if   10.000  or   100.000 


418 


Individual  Differences 


TABLE  XXII 

Frequency  Distribution  of  the  Scores 

OF  One  Thousand  College  Students 

ON  A  Simple  Learning  Test 

[Data  from  A.  Anastasi] 


Score 

Freq 

uncy 

Class  Intervals 

Cases 

Per  Cent 

52-55 

1 

0.1 

48-51 

1 

0.1 

44-47 

20 

2.0 

40-43 

73 

7.3 

36-39 

156 

15.6 

32-35 

328 

32.8 

28-31 

244 

24.4 

24-27 

136 

13.6 

20-23 

28 

2.8 

16-19 

8 

0.8 

12-15 

3 

0.3 

8-11 

2 

0.2 

N  =  1000 

100.0 

Students  liad  been  tested  instead  of  only 
1000. 

The  data  of  Table  XXII  are  plotted  in 
Fig.  202,  which  shows  the  frequency  dis- 
tribution in  two  forms.  The  dotted  lines 
form  a  histogram,  the  kind  of  graph  in 
which  the  frequency  for  each  class  interval 
is  drawn  as  a  horizontal  line  and  the  result- 
ing distribution  curve  appears  stepped.  If 
the  frequency  for  each  interval  is  plotted 
as  a  point  in  the  middle  of  its  interval  and 
the  points  are  then  connected  by  straight 
lines,  the  resulting  curve  is  called  a  polygon 
distribution. 

Both  table  and  curve  show  what  a  typ- 
ical distribution  is  like.  Some  midpoint  is 
its  highest  point,  that  is  to  say,  some  mid- 
value  is  the  most  frequent  and  thus  the 
value  you  would  be  most  likely  to  get  if 
you  had  to  pick  out  one  at  random.  Fre- 
quencies decrease  in  both  directions  from 
the  middle.  Extreme  values— very  high 
and  very  low— are  very  infrequent,  and 
there  are  practical  limits  to  the  curve   in 


both  directions,  although  you  may  get 
greater  extremes  when  you  have  more  cases. 
If  the  frequency  with  which  college  stu- 
dents will  get  a  score  of  3  (Table  XXII)  is 
only  once  in  10,000,  more  often  than  not 
you  will  get  no  score  so  low  as  3  when  you 
have  only  1000  cases. 


ODU 

320 

r- 

-| 

1/ 

1 
1 

280 

/ 

1  1 

/ 

\l 

240 

, 

.J 

|/ 

200 

\ 

l\ 

j 

ll 

160 

\ 

1 

h 

1 

120 

r 

'' 

V 

\\ 

\ 

80 

I 

l\ 

i 

'-^ 

n 

40 

h 

y 

-J 

i\ 

/j 

\ 

0 

8-11 
2-15 
6-19 
0-23 
4-27 
!8-31 
2-35 
6-39 
10-43 
14-47 
18-51 
52-55 
36-59 

^^       ^      Csl       CM      C\J 


Scores 

figure   202.      DISTRIBUTION   CURVES:    FREQUENCY 
POLYGON    AND    HISTOGRAM 

[Data  from  Table  XXII.] 

The  standard  form  of  frequency  distribu- 
tion is  the  normal  distribution  curve, 
shown  in  Fig.  102  (p.  262)  and  already  dis- 
cussed. It  is  the  symmetrical  curve  that 
you  get  when  the  positive  and  negative 
deviations  from  the  average  are  made  up 
of  the  sum  of  many  small  factors,  and  the 
positive  and  negative  factors  occur  equally 
often,  as  they  do  when  a  coin  is  tossed  with- 
out bias.  Suppose  you  took  6  pennies,  and 
tossed  them  all  together  64  times,  and  every 


Frequency  Distributions 


419 


penny  came  equally  often  heads  and  tails, 
and  every  combination  of  heads  and  tails 
occurred  ecjually  often,  which  is  to  say  onre 
for  each  combination,  since  there  arc  (J4 
jiossible  combinations  and  only  M  tosses. 
Then  suppose  you  counted  up  tiic  num- 
bers of  heads  in  each  throw  of  (i  pennies 
and  tabulated  the  frequencies.  You  would 
have: 


Number  of  heads  6 

.5      4      'i      2 

1 

0 

Frequency                 1 

6    15    20    15 

6 

1 

(Total  =  64) 

That  makes  sense.  There  is  only  one 
way  in  which  all  6  pennies  can  turn  up 
heads,  but  there  are  6  ways  of  getting  5 
heads,  for  any  one  of  the  6  pennies  might 
be  tails.  There  are  15  ways  of  getting  4 
heads  and  2  tails,  20  ways  of  coming  out  3 
and  3,  and  of  course  the  right  half  of  the 
distribution  must  be  symmetrical  with  the 
left  because,  if  there  are  6  ways  of  getting 
5  heads,  there  must  also  be  6  ways  of  get- 
ting 5  tails  (and  one  head).  If  you  graph 
these  frequencies  as  a  histogram,  you  get 
approximately  the  normal  curve.  If  you 
draw  a  smooth  curve  through  the  points, 
you  get  exactly  the  bell-shaped  normal  dis- 
tribution curve,  which  is  also  the  mathema- 
ticians' normal  probability  curve  (Fig.  102). 

The  normal  curve  is  'normal'  because  it 
is  what  happens  when  everything  is  sym- 
metrical, when  'more'  is  just  as  likely  to 
happen  as  'less,'  when  events  vary  in  a 
random  fashion.  In  fact  the  mathemati- 
cians define  the  term  random  as  the  kind 
of  variation  which  gives  normal  distribu- 
tions, as  does  penny  tossing  when  it  satis- 
fies the  conditions  just  enumerated.  Math- 
ematical statistics  has  been  built  up  to  ap- 
ply more  accurately— at  least  in  its  simpler 
forms— to  normal  distributions  than  to 
asymmetrical  distributions.  For  this  rea- 
son psychologists  prefer  distributions  that 


are  symmetrical  enough  lo  approximate 
normality.  If  they  get  distributions  that 
are  very  much  distorted,  being  much 
steeper  on  one  side  than  the  other,  they 
look  for  some  different  .scale  of  nicasurc- 
ment  or  scoring,  one  that  will  expand  the 
steep  side  and  compress  the  gradual  slope, 
making  the  distiibulion  more  symmetrical. 


^ir)iX)r~cooOi-<ojm^ir>vOp^oo 


mmmiDinir) •       >      • 

O^O^HCNi    CO    ^invor^ 

FIGURE   203.      IQ's   of    2904    UNSELECTED   CHILDREN 
BETWEEN    THE   AGES    OF    2    AND    18 

[From  L.  M.  Teriiian  and  M.  A.  Memll,  Measur- 
ing intelligence,  Houghton  Mifflin,  1933,  p.  37.] 

If  they  get  two  humps  in  the  curve,  a 
bimodal  distribution  (Fig.  207),  they  try 
to  analyze  the  characteristic  being  meas- 
ured into  two  factors,  each  of  which  will 
have  a  unimodal  distribiuion.  It  is  for 
this  reason  that  we  find  so  many  approxi- 
mately normal  distribiuions  of  psycholog- 
ical data.  The  tests  are.  often  uncon- 
sciously, adjusted  to  give  symmetrical  dis- 
tributions in  order  that  a  common  preju- 
dice for  symmetry  may  be  satisfied  and  that 
statistical  treatment  of  the  results  may  be 
easier. 

Figures  203  to  206  are  examples  of  dis- 
tribution curves  based  upon  the  test  scores 
of  large  groups  of  subjects.  Figure  203  is 
a  frequency  polygon  of  the  Stanford-Binet 


420 


Individual  Differences 


IQ's  of  2904  children  between  the  ages  of 
2  and  18.  It  will  be  noted  that  the  largest 
percentage  of  cases  receive  IQ's  in  the  mid- 
dlemost class  interval,  from  95  to  104,  the 
percentage  tapering  off  gradually  until  only 
a  small  fraction  of  I  per  cent  is  found  with 


30.7% 
(38) 

28.5% 
(24) 

26.2% 
(24) 

8.8% 
(7) 

5.8% 
(7) 

IV 


III 


FIGURE    204.       DISTRIBUTION    OF    ARMY    GRADES    OF 
THE  ARMY  GENERAL  CLASSIFICATION  TEST 

The  percentages  for  a  theoretical  normal  curve 
are  shown  in  parentheses.  [Data  from  W.  V.  Bing- 
ham, Science,  1946,  104,   148.] 

IQ's  from  35  to  44  and  from  165  to  174. 
The  scale  is  adjusted  to  have  the  average 
the  most  frequent  value  and  to  have  it  fall 
at  IQ  =  100. 

Figure  204  is  a  histogram  showing  the 
percentage  of  men  falling  into  the  five 
Army  grades  on  the  basis  of  their  AGCT 
scores.  These  percentages  are  based  upon 
a  group  of  nearly  ten  million  men.  For 
comparison,  the  percentages  which  would 
fall  in  each  grade  in  a  perfect  normal  curve 
are  given  in  parentheses.  It  will  be  seen 
that  the  correspondence  is  fairly  close  but 
not  exact.  The  test  was  constructed  with 
the  intention  of  getting  exact  correspond- 
ence, but  it  is  impossible  to  predict  exactly 
just  what  will  happen  with  frequencies. 

Figure  205  is  a  frequency  polygon  of  the 
scores  obtained  by  400  college  men  on  the 
AUport  Ascendance-Submission  Test.    The 


peak  falls  approximately  midway  between 
the  ascendant  and  submissive  extremes,  the 
number  of  cases  tapering  off  gradually  as 
ihese  extremes  are  approached.  Similarly, 
the  scores  of  801  school  children  on  one  of 
the  May  and  Hartshorne  tests  for  measur- 
ing cooperativeness,  as  shown  in  Fig.  206, 
are  symmetrically  distributed  in  accordance 
with  normal  expectation  for  a  unitary  trait. 
If  the  curve  had  been  asymmetrical  or  bi- 
modal,  the  authors  of  the  test  would  prob- 
ably have  done  something  to  the  test  to 
make  it  more  'normal'  or  else  have  dis- 
carded it  and  tried  to  in\ent  something 
'better.' 


Scores 


FIGURE  205.      SCORES  OF  4OO  COLLEGE  MEN  ON  THE 
ASCENDANCE-SUBMISSION    TEST 

[From  G.  \V.  Allport,  /.  ab)i.  soc.  Psycfwl.,  1928. 
23,    129.] 

In  a  number  of  behavior  characteristics 
indicative  of  social  conformity,  a  type  of 
distribution  known  as  the  J-ciin>e  is  often 
found.  This  curve,  named  after  its  resem- 
blance to  the  letter  J,  is  in  reality  a  greatly 
distorted  distribution  curve,  with  the  ma- 


Distributions  and  Types 


421 


jority  of  people  falling  al  tlic  end  which 
represents  complete  or  nearly  complete  con- 
formity. A  favorite  example  is  the  behav- 
ior of  motorists.  At  an  ordinary  intersec- 
tion with  no  traffic  signal,  drivers'  Ijehavior 
will  probably  be  symmetrically  distributed. 
The  majority  will  exhibit  a  moderate 
amount  of  caution,  very  few  will  come  to  a 


_l    1    1    1    M    1    1    N 

.    M    1    1    1    M    M_ 

140 

/ 

\ 

120 

/ 

\ 

/ 

\ 

Sioo 

—                          / 

\                           — 

s 

/ 

\ 

^80 

-                         / 

\                         - 

E 
^   60 

:           / 

\           : 

/ 

\ 

40 

/ 

\          - 

u              / 

\ 

20 

L                     / 

\        - 

H-+^-in    1    1    1    1 

1  1  1  1  n-+-4-i_ 

o    o    —    — 


O    O    ^     — ' 


FIGURE    206.       DISTRIBUTION    OF    COOPERATIVENESS: 
TEST  SCORES  AMONG   8oi    SCHOOL   CHILDREN 

[After  unpublished  data  of  H.  Hartshorne,  M.  A. 
May  and  J.  B.  Moller.  From  A.  Anaslasi,  Differen- 
lial  psychology,  Macmillan,   1937,  p.  51.1 

full  Stop,  and  equally  few  will  continue  at 
the  same  rate  of  speed  with  no  observation 
of  oncoming  traffic.  If,  however,  a  stop 
light  and  a  policeman  are  installed  at  the 
intersection,  these  external  constraints  will 
pull  the  distribution  into  a  J-cune.  In 
this  situation  over  ninety  per  cent  of  the 
drivers  will  come,  as  they  should,  to  a  full 
stop;  of  the  remaining  small  percentage,  a 
few  will  slow  down  markedly,  still  fewer 
will  slow  down  slightly,  and  a  very  small 
number  will  continue  at  the  same  rate  of 
speed.  Such  a  J-curve  could,  of  course,  be 
turned  back  into  a  symmetrical  cur\e  by 
stretching  the  full-stop  class  interval.     For 


inslarue,  you  cfiuld  divide  the  lull-stop  in- 
terval into  several,  according  vo  the  drivers' 
attitudes  that  jiroducccl  the  full  stop.  Vou 
might  be  able  to  separate  out  and  plot 
separately  almosl-did-nol-stop,  stoppcd-bul- 
rKsented-having-to,  slopped-as-a-matter-of- 
course  and  always-stop-wheriftier-lhcre-is- 
any-possible-reason-jor-it. 

Types 

In  popular  characterizations,  people  are 
often  classified  into  distinct  types.  The 
slieep  are  clearly  separated  liom  iIk-  goats, 
the  honest  from  the  dishonest,  the  brilliant 
from  the  dull,  the  meek  from  the  aggres- 
sive. Our  language  usage  is  undoubtedly 
an  important  factor  in  this  tendency  to- 
ward twofold  categorizing.  Such  categories 
imply  a  bimodal  distribution,  with  two  dis- 
tinct peaks,  or  modes,  and  perhaps  a  few 
mixed  or  intermediate  cases  falling  between 
the  peaks  (Fig.  207).  W'e  ha\e  already  seen 
that  studies  of  the  actual  distributions  of 
traits  almost  never  ha\e  more  than  one 
mode.  Individuals  cluster  around  a  single 
peak,  usually  located  near  the  center  of  the 
scale.  The  majority  of  persons  seem  to  fall 
in   the   intennediate   or   'mixed"  area,   and 


Scores 


FIGURE     207.        A     BIMODAL     DISTRIBUTION 

there  is  no  sharp  line  of  demarcation  be- 
tween different  degrees  of  a  trait.  People 
do  not  fit  into  separate  groups  ^vithout  in- 
termediates—not very  often.  Continuity  is 
the  rule,  and  all-or-none  typing  is  rare. 

Is  the  biolog)'  of  sex  an  exception?     Is 
sex  bimodal?     It  is  if  vou  take  overall  sex- 


422 


Individual  Differences 


uality  and  count  frequencies.  Most  persons 
are  either  male  or  female,  and  the  her- 
maphrodites—some verging  toward  male, 
some  toward  female,  some  half  and  half- 
are  the  infrequent  intermediates.  Hair-on- 
chin  would  be  bimodally  distributed  in  a 
total  population  of  men  and  women.  You 
could  take  as  a  measure  the  average  growth 
of  a  hair  in  one  month  on  one  square  cen- 
timeter of  initially  shaved  skin.  It  has 
never  been  done,  but  it  is  dear  that  a  bi- 
modal  distribution  would  result.  There 
would  be  variable  amounts  of  very  little 
growth  (the  women  mostly,  a  few  men), 
variable  amounts  of  heavy  growth  (the  men 
mostly,  the  bearded  women)  and  a  sparse 
sprinkling  of  men  and  women  in  between. 
There  are  some  biological  types  in  this 
sense  of  differences  existing  with  but  few 
intermediates.  Continuity,  is,  however,  the 
rule  in  biology,  largely  because  characteris- 
tics and  traits  are  so  complexly  determined 
tiiat  it  is  not  so  often  that  all  the  predis- 
posing factors  are  present  together  or  ab- 
sent together.  If  you  consider  the  heights 
of  men  and  women,  you  find  that  the  men's 
heights  are  distributed  according  to  a 
smooth  unimodal  curve,  the  women's  ac- 
cording to  another  smooth  unimodal  curve, 
and  that,  when  you  add  the  two  curves  to- 
gether, you  have  still  another  smooth  uni- 
modal curve.  Yet  the  fact  remains  that 
women  are  shorter  than  men,  oti  the  aver- 
age, although  the  tallest  woman  is  ever  so 
much  taller  than  the  average  man,  and  con- 
versely. 

It  is  the  same  way  with  the  other  sec- 
ondary sexual  characteristics.  You  can 
find  traits  that  are  properly  called  mascu- 
line and  others  that  are  properly  labeled 
feminine,  and  you  can  measme  both  men 
and  women  in  respect  of  them.  The  re- 
sult is  like  the  one  for  human  statures;  on 
the  average  men  are  more  masculine  than 


women,  IjiU  the  most  masculine  woman  is 
more  mascidine  than  the  average  man,  and 
conversely. 

One  might  expect  color  sensitivity  to  be 
bimodally  distributed,  but  it  is  not  except 
when  the  method  of  testing  for  color  blind- 
ness makes  it  so.  True,  there  are  two  types 
of  people,  those  who  can  pass  a  certain  test 
for  color  blindness  and  those  who  cannot. 
But  careful  measinement  of  color  sensitiv- 
ity soon  reveals  the  fact  that  there  are  in- 
termediates, persons  with  diminished  sensi- 
tivity who  see  all  the  colors  and  color-blind 
persons  who  are  no  longer  color-blind  when 
the  stimuli  are  made  very  effective. 

Whereas  the  all-or-none  types  are  rare, 
bipolar  continuity  is  common.  That  is 
what  you  usually  find  instead  of  types. 
There  is  red,  and  there  is  yellow,  and  there 
are  also  all  the  oranges  between  the  red 
and  yellow  poles.  There  are  color  nor- 
mality and  color  blindness  and  many  stages 
of  color  weakness  in  between.  There  are 
masculinity  and  femininity  and  all  possible 
degrees  between  the  two  poles.  When  you 
know  what  your  poles  are,  it  becomes  a 
matter  of  observation  whether  the  poles  are 
themselves  approximated  more  frequently 
than  their  intermediates  (bimodal  distribu- 
tion) or  whether  the  poles  are  rarely 
reached  and  some  midmixture  is  the  most 
frequent  case  (unimodal  distribution,  pre- 
sumably more  or  less  symmetrical). 

Constitutional  Types 

There  has  been  a  great  deal  of  talk  in 
psychology  about  constitutional  types,  each 
of  which  is  distinguished  by  its  own  physi- 
cal or  psychological  characteristics.  This 
is  an  old  theoiy  and  many  commonplaces  of 
language  attest  the  favor  it  has  enjoyed  in 
the  past.  The  jolly  fat  man,  the  square 
jaw  of  determination,  the  receding  chin  of 


Constitutional  Types 


423 


ihe  timid  soul— all  these  are  rciniiuicrs  ol 
ancient  systems  ol   typology. 

Rsythologisls  have  subjected  lo  sliidy 
many  ol  the  claims  that  have  been  |)ut 
forth  regaiding  the  reialion  between  be- 
havior and  physical  traits.  Three  probleiTis 
always  present  themselves:  (1)  how  to  meas- 
ure and  describe  the  human  body,  (2)  Ik)w 
to  select  and  evaluate  the  basic  traits  oi 
personality  or  temperament  and  (3)  how 
to  determine,  if  there  seems  to  be  a  rela- 
tionship between  the  two,  just  what  aspects 
of  physique,  on  the  one  hand,  are  related 
to  just  what  aspects  of  human  behavior, 
on  the  other. 

That  people  differ  in  shape  and  appear- 
ance has  always  been  obvious.  Long  ago 
an  ancient  Greek  divided  people  into  two 
categories:  the  short-thick  and  the  long- 
thin.  Many  bodies  fit  one  or  the  other  of 
these  descriptions  and  from  time  to  time 
this  two-categoiy  system  has  reappeared 
with  modifications  and  elaborations.  One 
well-known  typologist  distinguished  be- 
tween pyknic  (short,  thick)  and  leptosome 
(long,  thin)  body  builds.  Patients  with 
manic-depressive  psychosis  tend  to  be  pyk- 
nic, whereas  schizophrenic  patients  are  fre- 
quently leptosome.  Continuity  is,  how- 
ever, the  rule.  Neither  height  nor  width 
of  the  human  frame  is  bimodal  in  distribu- 
tion. (For  further  criticism  of  the  type 
theory,  see  pp.  488  f.) 

Recognition  of  this  fact  has  led  recently 
to  the  abandonment  of  the  notion  of  dis- 
tinct types  in  favor  of  a  description  of  hu- 
man physiques  in  terms  of  mixtures  of 
three  basic  components.  A  few  individuals 
have  one  or  another  component  developed 
to  an  extreme  degree,  but  in  most  people 
the  components  tend  toward  a  more  bal- 
anced development.  Accurate  description 
is  made  possible  by  a  system  for  measin-ing 
each  component  on  a  scale  of  1  to  7,  where 


I  is  the  least  and  7  is  the  greatest  amount 
possible.  These  ihrec  (omponrnts  are  de- 
scribed as  follows. 

(1)  Endornorphy.  I  he  degree  lo  which 
softness  and  roundness  predominate. 
When  high  cjn  the  scale  ol  ciiclcjinorphy 
(near  degree  7),  a  jjeisc>n  is  llabby,  soft 
and  rolypoly.  He  is  usually  'fat,'  in  the 
ordinary  sense,  but  not  all  jjcople  of  large 
girth  are  predcjminantly  endomorphic 
Some  'fat'  may  be  mainly  muscle. 

(2)  Mesomorpliy.  The  degree  to  which 
bone  and  muscle  predominate.  Weight 
lifters  and  professional  strong  men  usually 
have  7  degrees  in  mesomorphy.  They  are 
neither  fat  nor  thin;  they  are  mostly  bone 
and  muscle. 

(3)  Ectotnorphy.  The  degree  to  which 
linearity  and  fragility  predominate.  Peo- 
ple extreme  in  ectomorphy  are  'skinny,' 
with  long,  thin  bones  and  stringy  muscles. 

A  person  is  given  a  rating,  which  is  called 
his  sornatotype.  He  is  rated  in  each  of  the 
three  components,  in  the  order  in  which 
they  are  given  above:  endomorphy-meso- 
morphy-ectomorphy.  If  a  man  is  rated  a 
"2-6-1,"  that  means  that  he  is  low  (only  2) 
in  endomorphy,  very  high  (a  6)  in  meso- 
morphy and  as  low  as  anyone  could  be  (1) 
in  ectomorphy. 

Figure  208  shows  examples  of  physiques 
extreme  in  each  of  the  three  components 
and  one  case  in  which  the  components  are 
nearly  in  balance.  The  extreme  meso- 
morph  has  the  sornatotype  1-7-1  i^o.  The 
most  common  somatotype  found  among 
male  college  students  is  3-4—4.  There  are 
about  58  of  them  in  every  thousand. 

We  have  here  a  system  for  classifying 
human  physiques.  In  itself  it  is  an  an- 
thropometric system,  not  a  psychological 
one.  It  shows,  however.  ho^\'  to  deal  ^\ith 
the  problem  of  types  and  polarities.  ^Vhen 
continuity    is    the    rule    vou    can    still    find 


424 


Individual  Differences 


poles  and  describe  in  terms  of  components.  negligible  relation  to  physique,  such  as  ac- 

This  is  a  tripolar  system,  and  the  individ-  quired    attitudes,    for    example.      That    is 

ual  cases  are  regarded  as  having  three  com-  plain.      Political    persuasion    and    chinch 

ponents.     (The  color  system  has  four  poles,  membership  probably  have  nothing  to  do 

and  colois  arc  describable  in  terms  of  four  with  bod}   build.     Intelligence  shows  only 


(a)  Predominant  endomorphy,  7-1-1^2 


(h)  Predominant  mesomorphy,  l-J-iyo. 


t 


(c)  Predominant  ectomorphy,  114~1^4~7.  (d)  Balanced   physique,  4—5i^{r-i. 

FIGURE   208.      REPRESENTATIVE   SOMATOT\'PES 
[lioiii   W".  H.  Sliekloii  and  S.  S.  bie\cns,   I'inielies  uf  hiniitiii  leiiij>c)iniiciil.  Harper,   1012.  pp.  8  f  .1 


components:  R-G,  Y~B,  Wh-Bh,  Gy.     See 
p.  270.) 

Given  this  system  the  question  conies  up 
as  to  whether  there  is  any  psychological 
system  associated  with  it.  "Would  tempera- 
ment, personality,  intelligence,  psychoses  or 
any  other  psychological  characteristic  turn 
out  to  be  related  10  physique?  Some  ]xsy- 
rhologital    Aariabics    ha\e    at    best    onlv    a 


a  ^•ery  slight  relation:  a  low  negati\e  cor- 
relation with  mesomorphy,  a  low  positi\e 
correlation  with  ectomorphy.  On  the  other 
hand,  measures  of  physical  strength  and 
dexterity  are  coirelated  well  ^vith  meso- 
morphy, as  we  might  expect,  and  they  show 
a  moderate  negati\e  correlation  with  each 
of  the  other  two  coinponenis. 

The    most    interesting   relation    thus    far 


Constitutional  Types 


425 


demonstraled  is  bcLwccii  jjhysii|uc  and 
tcmpcranicnl.  rciii|K'iai)iciiL  iclcrs  lo  an 
individual's  basic:  cniolional  natinc,  the 
(jualily  ol'  his  mood,  ihc  direction  of  his 
deeper  motivations,  the  stamp  ol  his  char- 
acteristic reactions.  It  vvoiikl  not  be  sur- 
prising that  temperament  so  defined  should 
be  closely  linked  with  man's  physical  con- 
stitution, including  his  physiology  and  his 
glandular  functioning;  but  the  task  of  dem- 
onstrating the  linkage  is  not  easy.  The 
basic  components  of  temperament  must 
first  be  identified  and  measured. 

In  a  recent  study  a  group  of  200  men 
was  subjected  to  a  temperament  analysis 
in  which  each  individual  was  rated  on  60 
traits  of  temperament.  These  60  traits 
were  divided  into  three  groups,  one  for 
each  of  three  components  of  temperament. 
The  three  components  had  been  isolated  by 
a  process  of  correlational  analysis.  The 
components  of  temperament  defined  by 
these  three  clusters  of  traits  were  named 
and  briefly  characterized  as  follows. 

(1)  Viscerotonia.  General  relaxation, 
love  of  comfort,  need  for  affection  and  ap- 
proval, pleasure  in  eating  and  in  digesting, 
indiscriminate  amiability,  easy  emotional 
expression,  complacent  tolerance  and  need 
of  people  when  troubled. 

(2)  Somatotonia.  General  assertiveness 
in  posture  and  movement,  energetic  activ- 
ity, love  of  power  and  risk,  physical  cour- 
age, directness  of  manner,  psychological 
callousness,  general  noisiness  and  need  of 
action  when  troubled. 

(3)  Cerebrotoyiia.  General  restraint  and 
tightness  in  posture  and  movement,  love 
of  privacy,  emotional  restraint,  sociopho- 
bia,  unpredictability  of  attitude,  vocal  re- 
straint, poor  sleep  habits  and  need  of  soli- 
tude when  troubled. 

Twenty  traits  were  used  to  define  each  of 
these  three  components,  and  for  each  of  the 


()0  traits  tlje  subject  is  rated  on  a  7-point 
scale.  'J  hen  from  the  average  rating  on 
each  group  of  20  traits  an  index  ol  tem- 
perament wa.s  derived.  The  procedure  is 
analogous  to  that  used  for  the  designation 
of  the  somatotype.  An  extremely  viscero- 
tonic  temperament  scores  7-1-1;  a  perfectly 
balanced  temperament  scores  4-4-4.  The 
parallel  between  the  .system  for  physifjue 
and  the  system  for  temperament  is  close 
and  obvious. 

For  the  200  cases  of  this  study,  the  rela- 
tions between  the  components  of  physicjue 
and  the  components  of  temperament 
showed  positive  correlations  near  +0.80. 
These  correlations  are  high,  but  they  are 
not  perfect,  and  they  are  based  on  but  few 
cases. 

Certainly  it  is  not  yet  clear  that  there  is 
a  fixed,  one-to-one  relation  between  phy- 
sique and  temperament,  nor  is  it  in  order 
to  say  that  the  one  causes  the  other.  All 
we  can  say  as  yet  is  that  nature  seems  not 
to  assemble  physiqties  and  temperaments  in 
a  purely  chance  or  random  fashion.  It  be- 
gins to  look  as  if  either  the  shape  of  a  man 
has  something  to  do— by  and  large— with 
the  way  he  behaves,  or  the  way  he  behaves 
has  something  to  do  with  his  shape. 

The  Subnormal  Person 

The  subnormal  shoidd  be  regarded,  not 
as  a  distinct  class  of  persons,  but  as  consti- 
tuting the  lower  end  of  a  continuous  dis- 
tribution of  indi\idual  differences.  Among 
the  subnormal  are  included  the  feeble- 
minded, who  are  deficient  intellectually, 
and  the  mentally  diseased,  or  psychotics, 
who  deviate  from  the  norm  principally  in 
emotional  adjustment  and  odier  personal- 
ity characteristics.  The  neurotic  person 
displays  a  milder  degree  of  emotional  mal- 
adjustment, than  the  psycliotic.     (For  the 


426 


Individual  Differences 


description  of  psychoses  and  neuroses,  see 
pp.  531-537.) 

For  practical  convenience  in  treatment 
and  commitment  to  institutions,  certain 
classifications  of  feebleminded  persons  are 
accepted.  The  most  common  among  psy- 
chologists is  in  terms  of  IQ,  thus: 


Category 

JQ 

Normal 

90-110 

Dull 

80-  90 

Borderline 

70-  80 

Moron 

50-  70 

Imbecile 

20-  50 

Idiot 

Below  20 

The  IQ's  from  90  to  110  are  classified  as 
normal,  because  normal  is  thought  of  as  a 
class  with  some  range  to  it  and  not  as  lim- 
ited to  the  point  which  is  the  average.  In 
this  case  the  average  is,  of  course,  an  IQ  of 
100.  The  dull  and  borderline  groups  rep- 
resent intermediate  categories  between  the 
normal  and  the  feebleminded  levels,  the 
feebleminded  group  generally  including 
persons  with  IQ's  of  70  and  below.  Within 
the  feebleminded  group,  the  three  cate- 
gories of  moron,  imbecile  and  idiot  are 
commonly  employed  as  subdivisions.  Since 
the  distribution  curve  is  unimodal,  there 
are  fewer  idiots  than  imbeciles,  and  fewer 
imbeciles  than  morons. 

It  is  not  possible  to  say  in  general  what 
makes  people  feebleminded  or,  for  that 
matter,  what  makes  them  geniuses.  We 
have  the  unimodal  distribution  curve  as  a 
fact.  It  seems  to  be  the  sort  of  variation 
we  shoidd  expect.  We  cannot  explain  the 
intellectual  variability  of  mankind  in  terms 
of  brain  changes  or  of  differences  in  moti- 
vation. On  the  other  hand,  there  are  cer- 
tain known  physical  defects  and  diseases 
which  cause  feeblemindedness  in  some  in- 
stances, though  not  all.  The  microcephalic 
is  a  mentally  defective  person.  He  has  an 
abnormally  small,  pointed  skull  and  a  brain 


to  fit  his  skull.  'I'he  hydrocephalic  has  a 
very  large  skull,  but  with  an  excessive 
amount  of  cerebrospinal  fluid  between  his 
skidl  and  his  undersized  brain  within  it. 
Cretinism  is  due  to  insufficient  secretion  of 
the  thyroid  gland.  It  is  a  deficiency  which 
produces  both  intellectual  defect  and  char- 
acteristic physical  symptoms,  such  as  stunted 
growth,  short  and  podgy  limbs,  dry  rough 
skin  and  loss  of  hair.  Other  pathological 
varieties  of  feeblemindedness  have  been 
identified,  biU  they  remain  exceptional.  In 
most  cases  we  know  about  the  causes  of 
mental  deficiency  only  as  much  as  we  know 
about  the  causes  of  our  own  normality  and 
—we  all  have  them— our  flashes  of  genius. 

The  Genius 

Genius  may  be  regarded  as  the  upper 
end  of  the  distribution  of  intelligence.  Al- 
though the  observation  of  isolated  extreme 
cases  may  suggest  that  the  genius  is  so  un- 
like his  fellows  as  to  be  qualitatively  dif- 
ferent, here  again  we  find  borderline  in- 
stances of  mental  superiority  which  bridge 
the  gap  with  the  normal. 

Investigations  of  adult  geniuses  have  used 
three  methods:  biographical,  statistical  or 
historiometrical.  In  the  first,  all  available 
printed  material  about  a  single  genius  is 
examined  in  the  effort  to  understand  the 
nature  and  origin  of  his  genius.  Statistical 
surveys  are  likewise  based  upon  printed  rec- 
ords but  are  more  concerned  with  general 
trends  in  large  groups  of  eminent  men,  the 
information  being  obtained  from  biograph- 
ical dictionaries  or  questionnaires  filled  out 
by  living  men  of  great  distinction.  The 
method  of  historiometry  attempts  to  evalu- 
ate biographical  records,  especially  those 
dealing  with  childhood  accomplishments, 
in  terms  of  current  mental  test  standards. 
On  this  basis  an  approximate  estimate  can 


Subnormal  and  Supernormal  Persons 


427 


be  made  of  an  eminent  man's  IQ  in  child- 
hood. 

Intellectually  superior  diildren  are  more 
readily  available  lor  direct  psychological 
study  than  adult  geniuses.  A  number  of 
individual  child  prodigies,  including  some 
well-known  juvenile  wiiters,  have  been  the 
subjects  of  detailed  and  prolonged  observa- 
tion by  psychologists.  In  general,  the  re- 
sults of  such  case  studies  are  in  agreement 
with  the  findings  obtained  by  mental  test 
surveys  on  large  groups  of  superior  chil- 
dren. 

One  of  the  most  extensive  of  these  inves- 
tigations is  by  L.  M.  Terman  and  his  asso- 
ciates on  643  California  school  children  be- 
tween the  ages  of  2  and  14,  all  of  whose 
IQ's  were  140  or  above.  These  children 
were  found,  on  the  whole,  to  come  from 
homes  of  higher-than-average  social  and 
cultural  level.  Parents'  occupational  and 
educational  levels  were  likewise  above  aver- 
age. A  number  of  popular  misconceptions 
regarding  the  child  prodigy  were  disproved 
by  this  sttidy.  Thus  gifted  children  as  a 
group  were  equal  to  or  better  than  the 
normal  in  health,  physical  development 
and  emotional  adjustinent.  They  were  not 
narrow  and  specialized  in  either  abilities 
or  interests,  but  showed  wider  breadth  in 
both  respects  than  the  normal  groups  with 
which  they  were  compared. 

A  six-year  'follow-up'  of  a  large  part  of 
the  original  group  and  another  'foUow-tip' 
after  sixteen  years  indicate  that  the  group 
tended  to  retain  its  intellectual  superiority 
and  to  make  highly  successful  educational, 
vocational  and  personal  adjustments,  when 
it  was  compared  with  the  general  popula- 
tion. Within  the  group,  however,  the  de- 
gree of  advdt  success  did  not  seem  to  de- 
pend on  the  degree  of  intellectual  superior- 
ity. A  detailed  comparison  of  the  'most 
successful'    and    'least    successful'    men    in 


the  reexamination  after  sixteen  years  led 
the  investigatois  to  (onclude  that  "afxjve 
the  IQ  level  of  140,  adult  success  is  largely 
determined  by  such  factors  as  social  adjust- 
ment, emotional  stability  and  drive  to  ac- 
complish." The  two  groups— 'most  suc- 
cessful' and  'least  successful'— did  ncjt  dif- 
fer significantly  in  initial  IQ  or  in  initial 
educational  ac  hicvenicnt. 

GROUP    DIFFERENCES 

Sometimes  the  psychologist  is  mrjre  inter- 
ested in  differences  between  groujjs  than  in 
differences  between  the  individuals  who 
make  up  the  group.  He  wants  to  ccjmpare 
old  people  with  young,  college  graduates 
with  those  who  left  school  after  the  eighth 
grade,  men  with  women,  w'hite  persons 
with  Negroes.  How  do  you  go  about  the 
comparison? 

Sampling 

Not  often,  when  you  are  interested  in  a 
possible  difference  between  two  groups  of 
people,  are  you  able  to  measure  every  mem- 
ber of  each  group  and  then  draw  your  con- 
clusion. You  can  do  that  sometimes,  but 
only  when  the  groups  are  small.  If  you 
want  to  compare  the  intelligence  of  the 
girls  and  the  boys  in  a  gi\en  class,  you  can, 
indeed,  test  -them  all  and  then  see  what  you 
have;  but,  if  you  want  to  compare  the  in- 
telligence of  just  girls  and  just  boys,  or 
even  the  intelligence  of  all  girls  and  boys 
aged  twelve  in  the  United  States  in  1948, 
you  have  got  to  take  samples  and  compare 
them.  The  correctness  of  your  conclusion 
will  depend  upon  -^vhether  your  samples 
really  represent  your  gxoups  or  -^vhether 
they  are  biased. 

The  first  thing  you  do  is  to  measme  yotir 
sampling  error,  and  you  do  that  very  much 
as  you  measure   the  reliability  of  a   test 


428 


Individual  Differences 


You  take  several  samples,  each  as  good  as 
you  know  how  to  take,  and  compare  them. 
Vou  mtended  them  to  be  the  same.  The 
amount  that  they  differ  is  your  sampling 
error.  A  small  difference  between  your 
groups  would  not  be  regarded  as  signifi- 
cant if  your  sampling  error  were  large.  A 
small  sampling  error  indicates  the  validity 
of  your  sampling,  though  the  true  validity 
you  would  ne\  er  know  unless  you  measured 
the  entire  gioup— and  then  you  would  not 
need  a  sample. 

Mostly  in  interpreting  measurements  you 
deal  with  differences— individual  differ- 
ences, group  differences,  other  differences. 
Nearly  always  the  differences  are  between 
samples.  You  are  comparing  samples  of 
adults  when  you  say  that  some  people  are 
color-blind  and  others  are  not.  You  are 
comparing  samples  when  you  say  'intel- 
ligence' increases  during  childhood  and 
not  during  adulthood— samples  of  ten-year- 
olds,  twelve-year-olds,  twenty-year-olds, 
forty-year-olds.  When  you  compare  two 
groups,  you  generally  get  the  mean  meas- 
urement of  each,  see  what  is  the  difference 
between  these  means,  and  then  decide 
whether  the  difference  is  significant  or 
merely  what  might  have  occurred  by 
chance.     How  is  that  done? 

There  are  three  factors  that  affect  the 
significance  of  a  difference:  (1)  the  size  of 
the  difference  between  the  means  of  the 
samples,  (2)  the  variability  of  the  samples 
and  (3)  the  number  of  cases  in  each  sample. 
A  large  difference  is  more  likely  than  a 
small  difference  to  be  due  to  something 
other  than  chance  variability.  The  greater 
the  ^■ariability  of  the  samples,  however,  the 
less  likely  is  it  for  the  difference  to  be  sig- 
nificant. It  may  have  resulted  merely  from 
this  variability.  Still  if  the  difference  is 
maintained  when  the  number  of  cases  is 
very  large,  the  probability  that  it  is  due 


to  chance  is  greatly  diminished.  The 
larger  the  samples,  the  more  reliable  the 
difference. 

It  is  possible  b)  a  very  simple  formula 
to  compute  the  standard  deviation  of  a  dif- 
ference between  the  means  of  t^vo  samples 
{(td)-  We  get  it  from  the  standard  devia- 
tions (ff)  of  the  two  samples  and  the  num- 
bers of  cases  measured.  (For  the  meaning 
of  the  standard  deviation,  o-,  see  p.  263.) 
Then  we  determine  what  is  called  the  criti- 
cal ratio,  the  ratio  of  the  difference  to  its 
standard  deviation  (D/ao)-  The  larger  the 
difference  in  relation  to  its  standard  devia- 
tion, the  less  likely  is  it  to  vary  enough  to 
be  reversed.  If,  for  instance,  a  conclusion 
from  two  samples  were  to  be  that  high 
school  girls  of  twelve  are  brighter  than  high 
school  boys  of  twelve,  we  should  want  to 
know  how  likely  it  is  that,  in  taking  other 
samples,  the  difference  might  be  reversed  so 
as  to  show  the  boys  brighter  than  the  girls. 
A  modern  convention  is  to  require  the  dif- 
ference to  be  at  least  three  times  its  stand- 
ard deviation,  to  ask  that  the  critical  ratio 
equal  at  least  3.  Then  the  difference  is  re- 
garded as  significant  enough  for  use  in  im- 
portant conclusions.  There  is,  of  course, 
no  point  at  which  significance  begins  nor 
any  other  point  at  which  it  is  complete. 
Values  less  than  3  show  low  significance,  and 
values  greater  than  3  do  not  mean  'cer- 
tainty.' Forty  years  ago  scientists  were  re- 
jecting results  when  the  critical  ratio  was 
less  than  5,  but  nowadays  they  are  satisfied 
with  smaller  samples.  What  has  happened 
is  that  they  have  gained  confidence  in  their 
ability  to  choose  samples  with  few  errors. 

In  choosing  samples  it  is  especially  im- 
portant to  avoid  special  selection.  Any 
group  that  is  not  a  representative  sample 
of  the  population  from  and  for  which  it  is 
drawn  is  said  to  be  a  selected  group.  Se- 
lection vitiates  group  comparison  in  exag 


Sampling 


429 


lilt-  girls?  At  some  ages  tlicy  do,  but  that 
is  not  the  answer  here.  The  groups  were 
differently  selec  teri.  Ilie  hoys  wlio  <lo 
jjoorfy  in  s(liof>l  work  lend  v<>  di(jp  out  he- 
lore  higli  srhoo!  ;ind  get  jofjs;  th<-  dull  girls 
more  often  keep  on.  Ilie  sampling  was 
nf)(  <fjmp;ir;il)lc  in   ihc  two  eases. 


gerated  degree  when  it  occurs  differently  in 
the  two  groups  compared. 

Innnigrant  groups  lurnisii  a  good  ex- 
ample of  tin's  diffeieniiaf  operation  of  se- 
lective lactors.  Immigrants  coming  to  the 
United  States  from  different  countries  are 
usually  neither  lair  samples  of  their  home 
populations  nor  comparable  selecticjns  lor 
tlie  different  coimtries.  II  it  could  be 
shown  that  immigrants  fi'om  all  nations 
were  diawn  (onsisteiilly  IVom,  let  us  say, 
ihe  lower  sodo-economic  and  intellectual 
levels,  such  groups  would  at  least  be  ccmi- 
parable  with  one  another.  But  it  is  well 
known  that,  largely  because  of  economic 
and  political  factors,  the  immigrants  from 
certain  nations  at  a  given  time  may  repre- 
sent a  relatively  inferior  sampling  of  their 
home  population,  from  others  a  more 
nearly  random  sample,  and  from  still  oth- 
ers a  fairly  superior  sample.  You  cannot 
say  that  the  British  are  brighter  than  the 
Italians  just  because  the  British-born  re- 
cruits in  the  First  World  War  got,  on  the 
average,  higher  scores  on  Alpha  than  the 
Italian-born  recruits.  The  samples  for  the 
United  States  Army  were  fair  enough.  The 
Italians  in  it  were  not  so  bright  as  the 
British.     But  the  samples  were  selected  as 

against    the    populations    of    Great    Britain        B.  Schiller.     From  A.  Anastasi,  Differential  psyclwl- 

and  Italy,  selected  by  the  economic  condi-      "S^'-  Macmillan.  1937,  p.  403.] 


40 

- 

— 1 1 \ ' ' — ■ — ' 

:          1 

\ 

- 

7     /   \ 

\ 

30 

- 

/    ^ 
1     j 

\       \ 
\       \ 

20 

- 

1    / 

1    / 

/     X    --Boys 

\      \ 
\      \ 

\      \ 
\      \ 

/  f 
1   1 

1   / 

\     \ 

V       \ 

10 

'^ 

/  1 

/     / 
/      / 

\  \ 
\  V- 
\  \ 

1                M 

0 

1         1         1         1         1         1 

Scores 

FIGLIRE    2CJ9.       OVERLAPPI.NG    DISTRIBUTIONS 

Shows  the  distribution  of  boys'  and  girls"  scores 
on  a  test  of  arithmetic  reasoning.     [After  data  from 


tions  which  controlled  immigration  differ- 
ently for  the  two  countries  at  the  tiine 
when  men  of  recruit  age  in  1917  were  im- 
migrating to  America. 

Selective  factors  can  operate  just  as  well 
in  studies  of  sex  differences.  There  are, 
for  instance,  two  studies  of  sex  differences 
in  an  intelligence  test.  One  study,  with  a 
total  sample  of  2544  elementary  school 
children,  showed  that  the  girls  did  better 
than  the  boys.    The  other,  with  5929  high 


It  must  be  borne  in  mind  that  two  distri- 
butions can  overlap  each  other,  and  vet  the 
diffei'ence  bet^veen  the  means  may  be 
highly  significant.  See  Fig.  209,  which 
shows  the  overlap  of  the  distributions  for 
boys  and  girls  in  a  test  of  arithmetic  rea- 
soning. The  boys,  with  a  mean  score  of 
40.4,  are  better  than  the  girls,  with  a  mean 
score  of  35.8.  The  difference  is  4.6,  and 
the  critical  ratio  is  found  to  be  about  6. 


school  students,  came  out  in  favor  of  the      Certainly  it  is  no  chance  ^ariability   that 
boys.  Why?  Do  the  boys  mature  faster  than      makes  this  sample  of  boys  better  than  this 


430 


Individual  Differences 


sample  of  girls.  Nevertheless,  38  per  cent 
ot  the  girls  scored  higher  than  the  boys' 
average,  and  24  per  cent  of  the  boys  scored 
lower  than  the  girls'  average.  The  differ- 
ence between  the  groups  is  significant,  but 
you  cannot  safely  predict  about  individual 
boys  and  girls.  This  point  was  succinctly 
put  by  Samuel  Johnson  who,  when  asked 
which  was  superior,  man  or  woman,  is  said 
to  have  replied:  "AVHiich  man?  which 
woman?" 

Psychological  Sex  Differences 

A  comparison  of  lest  results  of  men  and 
women,  even  when  interpreted  with  the 
caiuions  discussed  in  the  preceding  section, 
can  only  show  sex  differences  under  exist- 
ing conditions  in  our  presejjt  society.  The 
tests  cannot  in  themselves  indicate  the 
origin  of  such  differences.  It  is,  however, 
of  practical  value  to  ascertain  the  typical 
behavior  characteristics  of  men  and  women, 
whatever  the  origin  of  such  characteristics. 
In  many  fields  definite  assimiptions  are 
made  regarding  sex  differences  in  abilities, 
interests,  attitudes  and  similar  traits.  This 
discrimination  between  the  sexes  is  notice- 
able in  advertising  and  selling,  political 
campaigning,  the  organization  of  newspa- 
pers and  magazines,  social  work,  crime  pre- 
vention and  the  treatment  of  offenders,  to 
name  only  a  few  outstanding  examples. 
Insofar  as  cultural  conditioning  may  have 
produced  certain  clear-cut  sex  differences, 
these  cannot  be  ignored  in  the  practical  ad- 
justments of  everyday  life. 

Test  results  show  with  considerable  con- 
sistency that  men  excel,  on  the  average,  in 
skill  with  numbeis  and  the  understanding 
of  spatial  relations,  women  in  verbal  apti- 
tude and  memory.  These  differences  ap- 
pear fairly  early  in  life  and  tend  to  increase 
with  age.  Several  studies  on  preschool 
children  have  brought  out  these  character- 


istic differences  in  test  performance. 
Among  college  students,  the  differences  are 
large  and  clear-cut.  For  example,  the  re- 
sidts  of  the  Scholastic  Aptitude  Test,  given 
to  4394  men  and  3318  women  applying  for 
admission  to  colleges  throughout  the  coun- 
try, showed  a  large  and  reliable  difference 
in  favor  of  the  women  on  the  verbal  part 
of  the  test  and  an  equally  large  difference 
in  favor  of  the  men  on  the  numerical  pai  t. 
The  critical  ratios  of  these  differences  were 
13.5  and  11.6,  respectively. 

Nearly  all  tests  of  'spatial'  or  mechanical 
aptitude  have  shown  male  superiority. 
Among  them  are  the  puzzle  boxes,  form 
boards,  slot  mazes,  paper-and-pencil  mazes, 
construction  tests  and  most  of  the  tests 
which  make  up  performance  scales  of  'in- 
telligence.' In  numerical  aptitude  and 
arithmetic  reasoning  (both  the  speed  and 
accuracy  of  computation)  the  boys  are  fa- 
vored, although  the  differences  are  not 
quite  so  consistent  as  in  mechanical  apti- 
tude. This  result  might  be  expected  from 
social  tradition  and  environmental  condi- 
tions, since  the  sex  differentiation  with  re- 
gard to  mathematical  work  is  not  so  pro- 
nounced as  it  is  for  mechanical  pursuits. 
Girls  are  given  more  opportunity  for  the 
development  of  numerical  than  space-per- 
ceptive functions.  In  both  the  elementary 
school  and  high  school,  for  example,  girls 
are  taught  arithmetic  in  the  same  classes  as 
boys,  but  the  boys  are  segregated  for  shop 
courses.  The  superiority  of  women  on  tests 
of  memory  is  found  with  all  types  of  ma- 
terial and  all  methods  of  testing  memory. 
Women  also  excel  in  tests  of  association 
and  in  vividness  of  mental  imagery.  Their 
superiority  in  verbal  ability  is  likewise  evi- 
denced in  a  variety  of  functions.  Observa- 
tions on  normal  as  well  as  gifted  and  feeble- 
minded children  have  shown  that,  on  the 
average,    girls   begin   to   talk   earlier   than 


Sex  and  Race  Differences 


431 


hoys.  Similarly  girls  oi  picscliool  ;if^c  arc 
known  to  have  larger  v()cai)iilaries  than 
boys  of  the  same  age.  Girls  excel  con- 
sistently in  reading  and  in  such  tests  as 
sentence  completicjn  and  story  completion. 
The  large  verbal  content  oi  mcjst  intelli- 
gence tests  often  results  in  a  dillerence  in 
favor  of  girls  in  total  score. 

The  results  of  personality  tests  reflect  the 
traditional  sex  stereotypes  of  our  culture. 
Thus  on  such  tests  as  Bcrnreuter's,  men's 
scores  indicate  more  extraversion,  domi- 
nance and  self-sufficiency,  as  well  as  fewer 
neurotic  symptoms.  On  the  Allport-Ver- 
non  Study  of  Values,  men  obtain  high  aver- 
ages in  theoretical,  economic  and  political 
values;  women  in  esthetic,  social  and  reli- 
gious values.  The  May  and  Hartshorne 
character  tests  indicated  no  sex  difference 
in  honesty,  but  a  slight  tendency  for  the 
girls  to  be  more  cooperative  and  more  per- 
sistent, and  a  large,  reliable  difference  in 
favor  of  the  girls  in  'inhibition'  or  self- 
control. 

A  comprehensive  approach  to  the  meas- 
urement of  sex  differences  in  personality 
traits  is  represented  by  the  Terman-Miles 
Masculinity-Femininity  Index  (M/F  index). 
This  index  is  obtained  from  a  series  of  tests 
in  which  each  item  was  chosen  because  it 
differentiated  significantly  between  the  re- 
sponses of  men  and  women  in  our  society. 
The  M/F  index  thus  shows  the  degree  to 
which  the  individual's  responses  coincide 
with  those  typical  of  the  majority  of  men 
or  women  in  our  culture.  Plotting  the  dis- 
tribution cvirves  for  men's  and  women's 
M/F  ratios  results  in  an  extreme  case  of 
overlapping  in  the  face  of  a  significant  aver- 
age difference.  The  most  masculine 
woman  is  much  more  masculine  than  the 
average  man.  and  conversely. 

A  growing  body  of  evidence  suggests  that 
the  observed  sex  differences  in  psycholog- 


ical ( haiac  Icristics  are  chic-fh  irarc-able  i<> 
certain  environmenial  lactors  rather  tlian 
to  any  innate  tendencies  associated  with 
sex.  Terman  and  Miles  found,  fc^r  exam- 
ple, that  the  M/F  index  for  both  sexes  was 
significantly  influenced  by  educaticjn,  cxcu- 
jjation,  soc  io-ecf^nomic:  level  and  fann'lial 
pattern,  such  as  ruuiiber  of  brothers  and 
sisters  or  death  of  one  parent.  .Similarly, 
in  an  investigation  of  neurrjiic  tendencic;s 
in  children,  it  was  found  that  ten-year-f»lcl 
boys  manifested  a  greater  average  number 
of  such  tendencies  than  ten-year-old  girls. 
The  difference  decreased  sharply  at  age 
eleven  and  was  reversed  among  tw-elve-year- 
olds.  Thereafter  the  girls  showed  an  in- 
creasingly greater  number  of  neurotic  tend- 
encies. The  increasing  differentiation  in  the 
social  environment  of  the  two  sexes  after 
puberty  and  in  the  cultural  pressures  which 
come  upon  them  at  that  time  may  explain 
these  changes  in  emotional  stability.  It  is 
also  interesting  to  note  that  anthropolo- 
gists have  reported  that,  in  certain  primi- 
tive cultures,  the  traditional  personality 
characteristics  of  the  two  sexes  are  vei")' 
unlike  those  in  our  society.  In  some  groups 
the  pattern  is  nearly  the  reverse  of  ours. 

Are  There  Racial  Differences? 

The  classification  of  men  into  racial 
groups  is  essentially  biological  and  corre- 
sponds to  such  divisions  as  breed,  stock  and 
strain  in  infrahuman  organisms.  In  its  sim- 
plest terms,  the  concept  of  race  implies 
common  physical  characteristics  deriving 
from  a  similar  heredity. 

The  task  of  classifying  people  into  races 
is  far  more  difficult  and  complex  dian 
would  appear  from  the  glibness  Avidi  -which 
individuals  are  popidarly  assigned  to  one 
race  or  another.  The  essential  problem 
in  such  classification  is  the  identification  of 
inheritable    physical    characteristics    which 


432 


Individual  Differences 


differ  clearly  from  one  group  to  another 
and  which  can  therefore  serve  as  criteria  of 
race.  A  wide  ^•ariety  of  such  criteria  ha\e 
been  proposed,  including  skin  color,  eye 
color,  hair  color  and  texture,  gross  bodily 
dimensions,  facial  and  cranial  measure, 
blood  groupings  and  endocrine  gland  ac- 
tivity. 

In  the  application  of  any  of  these  criteria 
of  race,  several  difficulties  appear  at  once. 
In  the  first  place,  there  is  wide  variability 
in  all  these  charatceristics  within  any  one 
racial  gioup.  The  overlapping  between 
groups  in  respect  of  each  of  these  criteria 
is  likewise  large.  The  indications  of  one 
criterion,  moreover,  are  often  contradicted 
bv  those  of  another.  A  person  can  ha^e  the 
skin  color  of  one  racial  group,  the  bodily 
proportions  of  a  second  and  the  head  di- 
mensions of  a  third.  Finally,  there  is  the 
fact  that  several  alleged  racial  characteris- 
tics, w^hich  were  formerly  regarded  as  in- 
nate, have  proved  to  be  changeable  under 
the  influence  of  environmental  factors. 
Even  such  apparently  hereditary  traits  as 
height,  shape  of  the  skull  and  facial  con- 
formation have  been  shown  to  depend  in 
part  upon  environmental  conditions  in 
early  life. 

The  study  of  racial  differences  is  further 
complicated  by  the  frequent  confusion  of 
racial  with  national  or  linguistic  categories, 
as  in  speaking  of  a  French  'race'  or  a 
Latin  or  Aryan  'race.'  The  extent  of  race 
mixture  Avhich  has  gone  on  for  many  gen- 
erations makes  any  such  simple  classifica- 
tion impracticable.  The  psychological 
study  of  mixed  or  hybrid  individuals  is 
beset  with  more  complications.  On  the 
one  hand,  the  social  disapproval  of  certain 
race  mixtures  creates  an  atmosphere  which 
may  produce  characteristic  personality  devi- 
ations in  tlic  hybrid  person.  On  the  other 
liand,   the  hybrid   may  ha\c  opportunities 


for  educational  and  social  development  not 
open  to  the  relatively  purer  stock  of  certain 
racial  groups.  This  is  undoubtedly  an  im- 
portant factor  in  the  common  finding  that 
•American  Indians  and  Negroes,  with  con- 
siderable white  mixture  in  their  ancestry, 
tend  to  do  better  on  our  intelligence  tests 
than  the  American  Indians  and  Negroes 
with  less  -white  blood.  The  hybrid  may 
get  some  of  the  advantages  of  both  the  cul- 
tures which  he  combines.  The  Indian- 
white  hybrid,  for  example,  gets  the  white 
man's  schooling,  which  helps  him  with  tlie 
white  man's  intelligence  test;  but  he  may 
be  better  than  the  white  man  and  poorer 
than  the  purer  Indian  in  woodcraft. 

A  serious  barrier  in  the  comparati\e  test- 
ing of  diff^erent  racial  or  cultural  groups  is 
language  handicap.  It  is  obvious  that  in 
testing  people  who  speak  different  lan- 
guages, verbal  tests  cannot  be  employed. 
Nonlanguage  tests  and  performance  tests 
have  been  constructed  for  this  purpose.  It 
will  be  recalled,  however,  that  the  same 
traits  are  not  measured  by  all  these  differ- 
ent tests  of  intelligence.  Furthermore,  dif- 
ference of  language  makes  the  use  of  verbal 
tests  impossible,  and  the  range  of  functions 
which  can  be  measured  is  greatly  narrowed, 
for  there  is  as  yet  no  good  substitute  for 
verbal  tests.  You  cannot  eliminate  the 
verbal  content  of  a  test  ^vithout  altering 
the  abilities  involved.  The  translation  of 
an  intelligence  test  into  different  languages 
does  not  solve  this  problem,  for  transla- 
tion renders  the  original  norms  inapplica- 
ble and  makes  the  test  useless  for  inter- 
group  comparisons. 

The  effect  of  language  handicap  upon 
test  performance  is  actually  most  serious 
for  those  individuals  with  sufficient  knowl- 
edge of  English  to  admit  them  to  the  ordi- 
nary verbal  tests.  It  has  not  generally  been 
considered  necessary  to  give  these  persons 


Racial  Differences 


433 


pcrloiinancc  or  nonlanguagc  tcsls,  al- 
though it  is  now  known  that  even  mild  de- 
grees of  language  handicap  will  signifi- 
cantly lower  test  scores.  In  studies  made 
of  the  American-born  children  of  innni- 
grant  parents,  the  bilingual  children  who 
spoke  English  in  school  but  a  foreign  lan- 
guage at  home  made  consistently  poorer 
scores  on  'intelligence'  tests  than  the  'niono- 
glots'  who  spoke  English  at  home  as  well 
as  in  school.  It  might  be  argued  that  the 
more  intelligent,  adaptable  and  progres- 
sive families  are  more  likely  to  learn  and 
adopt  English  and  that  these  initial  differ- 
ences in  intelligence— rather  than  language 
handicap— account  for  the  differences  in 
test  scores.  Such  an  ^planation  is  contra- 
dicted, however,  by  studies  which  reveal 
that,  on  nonlanguage  and  performance 
tests,  the  bilingual  children  do  not  show  a 
clear-cut  inferiority.  In  some  studies  they 
actually  excel  the  performances  of  the 
monoglots  and  even  the  norms  for  Ameri- 
can children. 

It  is  apparent,  also,  that  immigrant 
groups  in  America,  as  well  as  the  American 
Indians  and  Negroes,  frequently  differ  from 
the  native  white  American  in  educational 
and  occupational  opportunities,  in  socio- 
economic level  and  in  other  circumstances 
which  undoubtedly  influence  intelligence 
test  performance.  Customs  and  traditions 
must  likewise  be  taken  into  consideration 
in  evaluating  test  scores.  The  emphasis 
placed  upon  speed  of  performance  as  a 
desirable  objective  varies  widely  in  differ- 
ent cultures  and  is  thus  a  case  in  point.  In 
one  investigation  with  a  performance  scale 
used  with  groups  of  American  Indians,  Ne- 
groes and  white  boys,  the  average  IQ's 
placed  the  white  group  first,  the  Indians 
second  and  the  Negroes  third.  An  anal- 
ysis of  total  scores  into  errors  and  times, 
however,  showed  that,  in  accuracy  of  per- 


formance, the  whites  and  Negroes  had  ap- 
jjroximale.'y  ecjual  scoies,  whereas  the  In- 
dians excelled  both  groups  in  this  respect. 

There  is,  therefore,  no  answer  to  the 
(juestion:  Are  there  racial  differences? 
There  is  too  much  intermixture  of  races 
to  get  fjurc  strains.  You  cannot  test  ac- 
curately lor  differences  in  'intelligence,' 
when  there  are  language  differences  or 
even  broad  cultural  differences.  In  the 
few  cases  where  this  difficulty  is  not  en- 
countered, as  with  while  persons  and  Ne- 
groes in  the  United  States,  there  are  socio- 
economic differences  which  vitiate  a  differ- 
ence in  scores  on  intelligence  tests.  Social 
and  cultural  differences  obviously  create 
personality  differences.  A  minority  group, 
which  is  discriminated  against  by  the  ma- 
jority, will  develop  certain  defensive  atti- 
tudes and  traits.  So  may  the  majority  if 
the  minority  is  strong  and  dangerous. 
There  are  ever  so  many  demonstrable  dif- 
ferences between  groups,  but  they  are  not 
between  races.  Races  scarcely  exist  any 
more. 

The  basic  scientific  question  that  is 
raised  here,  however,  is  this:  Are  psycho- 
logical characteristics  inherited?  That  is 
the  topic  of  the  next  chapter. 

REFERENCES 

1.  An.islasi.  A.  Dif]erenlial  psyrlinlogx.  Xcw 
York:    Macmilhin.    19.^7. 

An  intioduction  to  the  piolilcms.  nietlioils 
and  results  of  the  studv  of  individual  and 
group  differences  in  behavior. 

2.  Carmichael.  L.  (Ed.).  Manual  of  child  ps}- 
cholog}-.  New  York:  AViley,  1947.  Chaps.  9  to 
19. 

Eleven  chapters  bv  eleven  authors  on  differ- 
ences in  children  and  adolescents  in  respect  of 
culture,  language,  intelligence,  emotions  and 
sex. 

3.  Freeman.  E.  S.  hidiridual  differences.  New 
York:   Holl.   1931. 


434 


Individual  Differences 


A  textbook  on  tlie  ps\cholog)-  of  individual 
differences. 

I.  Garrett,  H.  E.  Slalislics  in  psychology  and 
education.  (2nd  ed.)  New  York:  I.onginiins, 
Green,  1937.  '2. 

A  standard  lextliook  on  psychological  meas- 
urement and  slatislics.  coxerin^  dislribulioii, 
variabililv.  .sampling,  reliability,  \alidi!y  and 
correlation. 

5.  Garrett.  H.  F...  and  Schneck.  M.  M.  R.     Psycho-        13. 
loe,ical   tests,   methods   and   results.      New    \oyl^: 
Harper,  1933. 

A  sinvey   of  connnon    psvchological    tests,   in- 
cluding   .sensory    and    motor    f mictions,    .special  , 
aptitudes,    general    intelligence    and    personality 
characteristics,  together  \vith  some  of  the  prob- 
lems involved  in  their  construction  and  u.se. 

6.  Gilliland,  A.  R..  and  Clark.  E.  I..  Psychology 
of  indix'idual  differences.  New  ^'ork:  Prentice- 
Hall.  1939. 

Another  textlwok  on  the  ps\chol()gv  of  indi- 
vidual differences. 

7.  (irecnc.  1".  li.  .Measurements  of  Innnan  be- 
havior.    New   ^■ork:  Odvssev.  1941. 

Hi. 
A  text  on   psvchological    testing.  co\ering  the 

topics  of  intelligence,  special  aptitude  and  per- 
•sonalitv  tests,  and  including  several  chapters  on 
the  more  technical  prol)lems  of  test  construc- 
tion. 

8.  Huxley.  J.  S..  and  Haddon,  A.  C.  IIV  Eurn- 
peenis:  a  sunry  of  "racial"  problems.  Eondon: 
Cape,  1935.  '' 

A  sound,  popular  introduction  to  the  critical 
evaluation  of  studies  on  race  differences  in  psy- 
chological characteristics. 

9.  Klineberg.  O.  Race  differenea.  New  Voik: 
Harper,    1935. 

,\  comprehensive  sinvey  of  psvchological  data 
on  race  differences,  discussed  from  the  biolog- 
ical, psychological  and  cultural  approach. 

10.  Lindquist,  E.  F.  A  first  course  in  statistics. 
Boston:   Houghton  Mifflin,  1938. 

Another  standard   textbook  on   psychological 
statistical  methods,  discussing  distribution,  vari-       19. 
ability,   sampling,   reliability,   validity   and   cor- 
relation. 

II.  Mead,  M.  Sex  and  temperament  in  three 
primith'e  societies.     New   ^oik:    Morrow.    1935. 


18. 


An  anthropologist's  field  ob.servations  in  three 
primitive  cultines,  which  have  a  bearing  on 
the  problem  of  sex  differences  in  personality 
characteristics. 

Paterson.  D.   G.     Physit/ue  and  intellect.     New 
York:   .Appleton-Century,  1930. 

.\  standard  textbook,  somewhat  out  of  date, 
discussing  the  relation  of  |)liysiquc  to  intelli- 
gence, mental  efficiency  and  temperament. 

Penrose.  E.  S.     Mental  defect.     New  ^'ork:   Ear- 
rar  and  Rinehart,   1931. 

.\  sy.stematic  treatise  on  feebleiitindedncss.  its 
diagnosis,  varieties  and  treatment. 

.Scheinfeld,  A.     ]\'onien   and   men.     New   \oik: 
Harcoiut,  Brace,  1943. 

.\  popidarlv  written  but  thorough  rc\ievv  ol 
the  whole  problem  of  sex  differences. 

Sheldon,  W.  H.,  and' .Stevens,  S.  S.  Tlie  varie- 
ties of  temperament.  New  York:  Harper,  1942. 
'Ehe  case  for  the  relation  of  temperament  to 
plnsique— the  relation  of  viscerotonia.  .somalo- 
tonia  and  ccrebrotonia  to  endomorphy,  nieso- 
inorph\    and  ectomorphy. 

.  Sheldon,  W.  H.,  Stevens.  S.  S..  and  1  ucker,  W. 
B.  The  varieties  of  human  pb\siijue.  New 
York:   Harper,   1940. 

The  .system  for  the  characterization  of  human 
physiques  in  respect  to  endomorphy,  mesomor 
phy  and  ectomorphy,  with  some  psychology 
thrown   in  on   the  side. 

.  Termaii.  L.  M.,  and  Miles,  C.  C.  Sex  and 
personality.     New  York:   McGraw-Hill,    1936. 

Report  of  an  extensive  research  project  on 
sex  differences  in  personality  characteristics  in 
our  culture:  the  most  comprehensive  treatment 
of  this  (juestion   to  date. 

lerman.  E.  M.,  and  Oden,  M.  H.  The  gifted 
child  grows  up.  Stanford,  Calif.:  Stanford  Uni- 
versity Press,  1947. 

The  fourth  volume,  a  folloxv-up  after  twenty- 
fne  years,  of  Terman's  well-known  study  of  a 
thousand  very  gifted  children. 

Tyler,  L.  E.  Psychology  of  human  differences. 
New  York:   .\ppleton-Century,   1947. 

A  recent  textbook  which  considers  the  gen- 
eral problems  of  measuring  individual  diffei- 
cnccs    and    summarizes    the    evidence    for    dif- 


References  435 

fcienccs  dcpc-ndcnl  on  svs.  race,  sfxial  (lass,  aj;c  Woiceslcr,   Mass.:   Clark    Universily   I'r«.<i,   1933. 

and  intelligence,  and   llic  present  stains  of  aiti-  C;hap.   1.5. 

tudes  and  traits.  .  ,,.,,. 

A    .summary    of    the    major    findings    on    ucx 

20.  Wellman,  R.  I,.     Sex  dillerences.     In  C.  Miirchi-  fliffcrenccs  in  psycholo(;ital  characlcristirs  prior 

son    (Ed.),   A    handbook    of   child    psychology.  to  1933. 


CHAPTER 


19 


Heredity  and  Environment 


THE  underlying  causes  of  individual  dif- 
lerences  in  behavior  are  to  be  lound  in 
the  subjects'  varied  hereditary  backgrounds 
and  in  the  differing  environmental  condi- 
tions to  which  they  have  been  exposed. 
Besides  its  basic  theoretical  significance, 
the  cjuestion  ot  the  causation  of  individual 
differences  has  important  practical  appli- 
cations. Any  procedure  concerned  with 
the  control  or  modification  of  human  de- 
velopment must  be  based  upon  an  under- 
standing of  the  factors  which  influence 
such  development.  All  educational  meth- 
ods, for  example,  make  some  assumption, 
tacitly  or  explicitly,  regarding  the  causes 
of  human  traits.  Is  it  the  function  of  edu- 
cation to  produce  certain  desirable  traits 
or  merely  to  offer  opportimities  for  the  de- 
velopment of  the  individual's  inborn  po- 
tentialities? 

For  instance,  what  causes  sex  differences? 
Biologically  sex  is  inherited,  for  it  depends 
upon  the  characters  in  the  germ  cells  that 
unite  to  form  the  new  individual.  How 
much  of  the  psychological  sex  differences 
depend  also  on  the  germ  cells  or  on  other 
differences  which  in  their  turn  are  depend- 
ent on  the  germ  cells,  and  how  much  do 
they  result  from  experience  and  social  pres- 
sure? Can  you,  do  you,  learn  to  be  a  man? 
or  a  woman?  The  beliefs  about  what  is 
the   right    answer    to    this    question    affect 


the  answer,  for  they  determine  the  types 
of  educational  programs,  vocations  and 
many  other  activities  that  are  assigned  tra- 
ditionally to  men  and  to  women,  and  which 
thus  help  to  make  masculinity  and  feminin- 
ity what  they  are  today. 

It  is  the  same  way  with  the  problems  that 
concern  racial  or  national  groups.  If  you 
think  that  the  characteristics  of  such  a 
group  are  inherited,  you  will  be  recom- 
mending one  kind  of  action  about  the 
groujD.  If  you  think  the  characteristics 
are  gained  through  formal  education  or 
through  the  informal  education  of  living, 
you  may  have  a  different  set  of  recommen- 
dations. You  cannot  deal  wisely  with  such 
problems  unless  you  know  what  has  caused 
the  differences  that  create  the  problems. 

FUNDAMENTAL    CONCEPTS 

Every  trait  of  the  individual  and  every 
reaction  which  he  manifests  depend  both 
upon  his  heredity  and  upon  his  environ- 
ment. We  have  already  met  that  truth  in 
our  study  of  the  facts  of  maturation 
(Chapter  4).  Traits  or  activities  cannot 
be  divided  into  those  which  are  inherited 
and  those  which  are  acquired.  Since  it  is 
now  recognized,  however,  that  hereditary 
and  environmental  influences  interact  in 
the    production    of   all    the    characteristics 


This  chapter  was  prepared  by  Anne  Anastasi  of  Fordham  University. 

436 


Whai  Is  Heredity? 


437 


ol  (.lie  iiulividiKil,  tlic  ptoblciii  resolves  it- 
sell  into  a  dcleniiiiiation  ol  the  relative 
contribution  of  each  in  the  development  of 
any  given  function.  How  much  is  nature 
and  how  much  nurture?  wc  may  ask,  using 
the  pair  of  words  that  Francis  Gallon  intro- 
duced when  he  discussed  this  jjroblem.  To 
what  extent  can  the  development  of  a  func- 
tion be  altered  by  the  control  of  environ- 
mental conditions,  and  to  what  extent  is 
such  modification  limited  by  hereditary 
factors?  Individual  differences  occurring 
under  the  same  heredity  may  be  attributed 
to  the  operation  of  different  environmental 
factors.  Similarly,  when  the  environments 
are  sufficiently  alike,  dissimilarities  of  be- 
havior indicate  differing  heredity. 

What  is  Heredity? 

It  should  be  borne  in  mind  that  the  term 
heredity  signifies  biological  heredity.  It  is 
only  figuratively  that  we  speak  of  'social 
heredity,'  as  in  such  expressions  as  'the 
cultural  heritage  of  the  twentieth  century' 
or  'the  inheritance  of  the  family  fortune.' 
Society  is  in  the  environment,  and  social 
inheritance  is  actually  a  kind  of  environ- 
mental influence. 

The  hereditary  factors  which  contribute 
to  the  development  of  the  individual  are 
referable  to  the  genes,  minute  structures 
occuiring  within  the  nucleus  of  all  living 
cells.  The  genes  are  grouped  into  chromo- 
somes, 'colored  bodies,'  so  named  because 
they  become  visible  when  the  cell  is  stained 
by  certain  dyes  for  observation.  These 
chromosomes  occur  in  pairs,  the  two  mem- 
bers of  each  pair  being  similar  in  appear- 
ance. The  number  of  chromosomes  in  each 
cell  is,  in  general,  constant  for  every  spe- 
cies, but  differs  from  one  species  to  another. 
Each  human  cell,  for  example,  contains  48 
chromosomes  (24  pairs);  in  each  cell  of  the 
mosquito,  there  are  6  (3  pairs);  and  in  each 


cell  ol  a  certain  sjjccies  of  riayfisli,  z!00  MOO 
jjairs).     (See  I-'ig.  210.) 

Giowth  takes  place  by  cell  division.  Cjne 
cell  divides  into  two;  later  these  two  into 
four,  and  so  on.  When  a  cell  divides,  the 
48  chromosomes  split  longitudinally,  pre- 
sumably splitting  each  gene  in  two,  and  one 
half    of    each    chromosome    goes    to    each 


FIGURE    2IO.       MICROSCOPIC   VIEW    OF    HLMAN 
CHROMOSOMES 

Shows  the  IS  human  chromosomes.  The  ^- 
chromosonie  deteimines  sex.  Sex  is  hereditary,  de- 
pending on  the  genes  of  the  father.  [From  H.  >r. 
Evans  and   O.   Swezy,  Mem.    Univ.   Calif.,   1929,   9, 

No.  1.] 

daughter  cell.  Thus  the  daughter  cells— 
and  what  we  might  call  the  granddaughter 
and  great-granddaughter  cells,  all  down  the 
line— have  exactly  the  same  constitution  as 
to  chromosomes  and  genes  as  the  original 
parent  cell  which  started  the  individual  off 
in  life. 

At  puberty  the  germ  cells  are  formed. 
ova  in  the  female  and  sperms  in  the  male. 
Thev  are  formed  from  other  cells  by  a  dif- 
ferent kind  of  division,  known  as  reduc- 
tion dii'isioii,  because  the  chromosomes  do 
not  split  longitudinally  in  t^\o.  but  pass 
one  set  of  24  to  one  cell  and  tlie  other  set 
to  the  other  cell.     An  o\um  or  a  sperm 


438 


Heredify  and  Environmeni 


has,  thereafter,  only  24  chromosomes,  half 
the  equipment  of  a  normal  cell,  and  thai 
means  only  half  of  the  normal  cell's  double 
set  of  genes.  Although  the  chromosomes 
do  not  split  longitudinally  in  this  division, 
tliey  may  divide  trans\ersely,  recombining 
genes  in  new  combinations  in  a  single  one 
of  the  new  diromosomes.  The  parent  cell, 
il  will  hf  seen,  has  many  pairs  of  genes, 
(■\er  so  man\  of  them,  although  we  do  not 
know  just  how  many  genes  are  in  one  chro- 
mosome. Every  germ  cell  gets  one  gene 
from  each  pair  of  genes  in  the  parent  cell, 
but,  since  there  is  some  crossing  over,  a  new 
chromosome  may  contain  some  genes  from 
a  given  parent  chromosome  and  the  other 
genes  from  the  mate  of  that  chromosome. 

AVhen  a  new  individual  is  begun  at  con- 
ception, an  oA'um  and  a  sperm  combine  to 
make  the  first  parent  cell  which  is  the  new 
organism.  It  will  have  24  chromosomes 
tliat  came  from  the  ovum  and  24  that  came 
from  the  sperm.  Together  they  make  up 
tlic  normal  complement  of  48  chromosomes 
in  24  pairs.  Half  the  genes  are  from  one 
jjarent,  and  half  from  the  other.  When 
this  single  cell  has,  by  repeated  division, 
grown  into  a  mature  individual,  it  will 
pass  half  its  genes  to  its  ova  or  its  sperms 
and  thus  to  its  progeny.  There  is,  how- 
ever, no  way  of  predicting  which  genes  of 
any  pair  will  be  the  ones  included  in  any 
one  germ  cell  and  thus  be  the  ones  inher- 
ited by  the  new  individual. 

Chromosomes  are  visible  under  a  micro- 
scope, appearing  as  rodlike,  sausage-shaped, 
or  V-shaped  bodies.  A  microscopic  view  of 
himian  chromosomes  is  shown  in  Fig.  210. 
Within  each  chromosome  are  the  genes,  par- 
ticles so  minute  that  they  are  invisible, 
even  with  a  high-power  microscope.  Re- 
cent observations  of  the  giant  chromosomes 
in  the  salivary  glands  of  the  fruit  fly  have, 
however,   opened  a  way  for  the  study  of 


the  internal  structuie  of  chromosomes  atid 
may  thus  lead  to  a  direct  knowledge  of  the 
genes.  Figure  211  is  a  photograph  of  such 
a  giant  chromosome,  with  its  characteristic 
pattern  of  transverse  bands.  It  has  been 
suggested  that  the  bands  may  bear  some 
relation  to  the  theoretically  inferred  genes. 
A  gene  is  the  carrier  of  a  unit  rhdvacler, 
an  hereditary  factor  wliich  is  always  tians- 
mitted  as  a  unit  in  all-or-none  fashion. 
The  imit  characters  carried  by  the  genes 
are  not  to  be  confused  with  traits,  for  the 
genes  are  of  a  much  more  elementary  na- 
ture. Thus,  even  such  a  relatively  simple 
characteristic  as  the  eye  color  of  the  fruit 
fly  depends  upon  more  than  fifty  separate 
genes.  Such  complex  hereditary  determi- 
nation will  of  course  produce  varying  de- 
grees of  a  trait,  even  though  each  indi- 
A'idual  gene  is  transmitted  in  an  all-or-nonc 
manner. 

Any  attempt  to  identify  psychological 
characteristics,  and  especially  such  complex 
and  vaguely  defined  behavior  phenomena 
as  'intelligence,'  with  unit  characters  is 
wholly  unjustified  when  we  know  so  little 
about  the  genes.  So  simple  a  relation  is 
also  highly  improbable.  The  experimental 
identification  of  the  specific  genes  which 
itifluence  the  development  of  observable 
characteristics  of  the  organism  is  an  ex- 
tremely difficult  task.  In  recent  years  some 
[progress  has  been  made  in  this  work  by 
geneticists.  T.  H.  Morgan  has  mapped 
genes  on  the  chromosomes  of  the  fruit  fly. 
No  one,  however,  expects  to  find  a  gene  or 
even  a  simple  set  of  genes  for  the  mental 
diseases  or  other  complex  human  behavior 
characteristics,  the  incidence  of  which  Ave 
should  like  to  control  by  eugenics. 

The  hereditary  basis  of  individual  dif- 
ferences lies  in  the  almost  unlimited  variety 
of  possible  gene  combinations  which  may 
occin,  especially  in  so  complex  an  organ- 


Biology  of  Heredity 


439 


ism  as  man.     Hcie  you   aie.     Could   ycnir  sisters   or    a    bi oilier    and    sister)    will    not 

parents,     knowing    theniselves,    have     pre-  have  identical  heredity.    'I  hey  will  not  gel 

dieted    what    you    would    be    like?      Could  the   same    ^enes    Irom    each    parent.      Fm- 

they  even  have  piediclcd  your  complement  IcyikiI  hriiis,  bom  ol   the  same  parents  at 

ol   genes?      No.  ol    course   they  could   not.  the  same  time  Init  irom  diHerent  pairs  of 

It  you  got  only  a  thousand  genes  from  one  germ   cells,    will    also    not   have    the   same 

])areiit  and  a  complementary  thousand  from  complement  of  genes.     On  the  other  hand, 


FIGl'RF,    211.       MICROSCOPIC    \IK\\     Ol-    ClANT   C:HRO.MOS()M  K    IROM     llli;    SAM\Ak\ 
GLAND   OF  THE  FRUIT  FI.V 

[From  T.  S.  Painter.  /.  Heredity,  19.S4,  25,  464.] 


the  Other  parent,  the  number  of  possible 
combinations  of  genes  is  so  large  that  it 
makes  the  number  of  electrons  yon  could 
pack  into  a  sphere  with  the  diameter  of  the 
stellar  universe  (10"^)  seem  like  a  very 
small  number  indeed.  Of  course  not  every 
gene  combination  makes  a  difference. 
Nevertheless,  the  wonder  is  that,  in  spite 
of  the  fact  that  everyone  has  only  half  the 
genes  that  his  parents  had  and  many  of 
them  have  no  apparent  effect,  the  resem- 
blances due  to  heredity  are  as  recognizable 
as  they  are. 

It  is  clear  that  t^vo  siblings  (brothers  or 


identical  tivi>is.  which  develop  from  the 
same  sperm-and-o\ima  ^vill  have  exactly 
the  same  set  of  genes,  for  they  get  their 
genes  by  division  of  the  common  set.  For 
this  reason  there  has  been  a  great  deal  of 
study  of  identical  twins,  because  they  con- 
stitute cases  where,  heredity  being  the  same, 
differences  of  enA'ironment  can  be  found 
acting  alone. 

Popular  Misconceptions 
Regarding  Heredity 

(1)  In   the  eaily   part  of  the  nineteenth 
century,  the  naturalist  Lamarck  put  forth 


440 


Heredity  and  Environment 


ihe  theory  of  the  iiihcriUnice  of  acquired 
characteristics.  This  theory  claimed  that 
the  evolution  of  species  characteristics 
through  successive  generations  resulted  from 
the  transmission  of  the  effects  of  use  or 
disuse  of  functions  by  the  parent  organism. 
.\  classical  example  was  the  assertion  that 
the  long  neck  and  legs  of  the  giraffe  were 
produced  by  the  gradual  stretching  of  neck 
and  legs  as  the  animals  reached  for  food 
among  the  tree  tops,  such  accjuired  elonga- 
tion being  transmitted  by  each  successive 
generation  to  its  offspring.  No  acceptable 
evidence  has  ever  been  found  to  support 
such  an  hypothesis.  In  fact,  present-day 
knowledge  regarding  the  mechanism  of 
heredity  tends  to  contradict  it.  Only  genes 
in  the  germ  cells  can  be  transmitted  to  the 
offspring,  whereas  acquired  characteristics 
are  modifications  of  the  nonreproductive 
body  cells  of  the  organism.  Despite  the 
lack  of  scientific  support,  the  popular  be- 
lief that  children  can  inherit  the  musical 
training,  artistic  sophistication  or  acquired 
muscular  skills  of  the  parents  still  survives. 
(2)  A  related  popular  superstition,  even 
farther  removed  from  the  known  facts  of 
heredity,  is  that  experiences  of  the  mother 
during  pregnancy  exert  prenatal  influences 
upon  the  developing  offspring.  Birth- 
marks, as  well  as  numerotis  other  abnor- 
malities of  appearance  or  behavior,  ha\e 
from  time  to  time  been  erroneously  at- 
tributed to  such  maternal  experiences. 
One  is  told,  for  example,  that  a  disfiguring 
hairy  mole  on  the  chin  resulted  from  the 
subject's  mother  having  touched  her  chin 
when  frightened  by  a  shaggy-haired  Aire- 
dale. Or  a  child's  agility  in  climbing  will 
be  ascribed  to  his  mother's  frequent  visits 
to  the  monkey  house  at  the  zoo  during 
her  pregnancy.  Although  there  is  no  pos- 
sible wav  in  which  such  experiences  of  the 
parent  can   affect   the  developing  embryo. 


hopeful  mothers  can  still  be  found  who 
frequent  art  museums  or  concerts  dining 
their  pregnancies  in  the  fond  expectation 
of  developing  their  children's  interests 
along  these  socially  esteemed  lines! 

(3)  Anotlier  popular  misconception  is 
that  the  inheritance  of  a  characteristic  is 
indicated  only  by  resemblance  to  parents. 
\  consideration  of  the  mechanism  of  hered- 
ity fails  to  support  such  a  belief.  The 
genes  continue  from  generation  to  genera- 
tion and  are  not  produced  new  by  the  in- 
dividual parent.  The  parents  merely  trans- 
mit genes  to  their  offspring.  Thus  a  per- 
son gets  half  his  genes  from  each  parent, 
a  quarter  of  them  from  each  grandparent, 
and  ^0  24  of  them  from  each  ancestor  ten 
generations  back.  He  has  no  genes  that 
his  parents  did  not  have.  Many  genes  are 
latent  or  recessixie  in  that  they  are  not 
effective  when  paired  with  a  dominant^ 
gene,  yet  may  become  effective  when,  in 
the  later  generations  to  which  they  have 
been  transmitted,  the  operation  of  chance 
in  gene  pairing  may  have  taken  away  the 
dominant  inhibitor.  When  a  person  gets 
two  recessive  genes  from  his  parents,  both 
of  whom  were  hybrids  with  their  observable 
characteristics  determined  by  dominant 
genes,  he  will  resemble  neither  parent.  He 
may,  howe\er,  resemble  an  ancestor,  for  he 
is  still  what  his  genes  make  him  so  far  as 
hereditary  characteristics  go,  and  his  an- 
cestors were  also  what  their  genes  made 
them,  and  it  was  from  his  ancestors  that  he 
got  his  genes. 

These  facts  become  clearer  when  we  un- 
derstand the  Mendelian  scheme  of  inheri- 
tance, which  shows  how  dominant  and  re- 
cessive genes  interact  to  give  different  ob- 
ser^'able  characteristics  in  offspring.  Fig- 
ure 212  shows  how  inheritance  of  black  and 
white  coat  color  in  guinea  pigs  works  out. 
Black  being  dominant,  a  black  guinea  pig 


Mendeitan  Inherifance 


441 


may  be  cilhcr  pure  biiuk  or  a  liybrid. 
Figure  213  shows  the  same  relations  sche- 
matically, with  recessive  white  hitltlen  un- 
der dominant  black  in  tiie  hybrids.  In 
other  words,  when  both  parents  are  hy- 
brids, about  one-fourth  of  the  children 
resemble  neither  parent. 


CD 


FIGURE    212.       MENDELIAN    INHERITANCE    OF    COAT 
COLOR    IN    THE   GUINEA    PIG 

The  black,  coat  is  dominant  over  the  recessive 
white  coat.  The  first  pair  here  shows  the  mating 
of  an  animal  from  a  pure  black  strain  with  one 
from  a  pure  white  strain.  All  guinea  pigs  of  the 
second  generation  are  hybrids,  but  they  look  black 
because  black  is  dominant  over  white.  In  the  third 
generation  you  get  pure  blacks,  black  hybrids  and 
pure  whites  in  the  ratios  shown  in  Fig.  213. 

Not  all  characteristics  follow  the  rule  of 
doininance  and  recession.  Some  hybrids 
are  intermediate  between  their  parents. 
Thus  the  white  and  Negro  genes  combine 
to  gi^'e  mulattoes  of  varying  degrees  of 
whiteness  and  blackness. 

(4)  Still  another  popular  misconception 
about  inheritance  is  that  rvhatener  is  pres- 
ent at  birth  is  inherited  and  whatever  de- 
velops subsequently  is  acquired.  Taken  as 
it  stands,  this  statement  is  inconsistent 
with  the  concept  of  development  as  an  in- 
teraction of  heredity  and  environment. 
Even  if  reformulated  to  state  that  heredi- 
tary influences  cease  at  birth,  however,  it 
is  still  incorrect.  Hereditary  factors  may 
influence  the  development  of  the  individ- 


ii;il  long  alter  birth,  and  in  lact  tlirougfioui 
his  life  span.  Even  the  onset  of  deaili  it- 
self may  be  dcternn'ncd  partly  fjy  hf-reditary 
factors,  as  is  suggested  by  the  observation 
that  longevity  tends  to  run  in  families. 
Hereditary  influences  may  first  become 
manifest  at  any  age.  Similarly,  environ- 
mental influences  begin  to  operate  upon 
the  organism  before  birth  and  from  the 
moment  of  conception,  fiirih  is  not  to  be 
regarded  as  a  beginning  in  the  life  of  the 
individual,  but  as  one  important  event 
which  occurs  in  a  long  lilc  history  extend- 
ing from  conception  to  death. 

What  specifically,  then,  do  the  genes  ac- 
complish? In  an  earlier  chapter  Ave  have 
seen  that  heredity,  working  in  an  adequate 

Dominant      Recessive 


•S 


i=^ 


1=^ 


FIG.    213.       MENDELIAN    INHERITANCE:     SCHEMATIC 

Comparable  to  Fig.  212.  Black  is  dominani. 
white  is  recessi\e.  Hvbrids  are  shown  with  black 
on  top  of  white.  Pure  dominants  and  pure  reces- 
sives  are  solid  black  and  solid  white.  rcspecti\eh. 
The  figine  shows  the  ratios  of  progenv  that  differ- 
ent matings  ^vould  vieid.  For  example,  two  h\brids 
mated  should  have  progenv  in  the  ratio  I  pure 
dominant  :  2  hybrids  :  1  pure  recessive,  but  to  ob- 
servation the   1:2:1  ratio  looks  like  3:1. 

environment,  determines  the  groA\th  and 
development  not  only  of  all  die  structures 
of  the  body,  but  also  dieir  organization  into 
a  functional  Avhole.  and  in  particular  the 
neuromuscular  coordinations  that  occur 
before  any  unlearned  form  of  behavior  can 
take    place.      These    coordinations    of    un- 


442 


Heredity  and  Environment 


learned  behavior  are  common  to  e\ery  nor- 
mal human  being  o£  whatever  race  or  cul- 
ture. 

A  large  proportion  of  man's  behavior, 
liowever,  is  learned.  What  part  does  hered- 
ity play  in  learning?  In  the  first  place, 
man's  bodily  structine  determines  some 
things  that  he  cannot  learn  to  do.  He 
cannot  learn  to  fly  like  a  bird  because  he 
has  no  wings.  He  cannot  learn  to  breathe 
under  water  because  he  has  no  gills.  In 
learning  he  is  limited  by  the  equipment 
which  the  genes  have  provided.  He  can 
develop  muscles  he  already  has,  but  he 
cannot  create  new  ones.  He  can  strengthen 
nerve  connections  and  perhaps  open  new 
paths  through  the  synapses,  but  he  cannot 
create  new  connectors  or  paths.  In  other 
words,  heredity  has  furnished  him  with  an 
equipment  that  is  capable  of  doing  many 
more  things  than  are  necessary  for  the  main- 
tenance of  his  life  and  the  reproduction  of 
his  species,  and  man  in  learning  utilizes 
this  equipment. 

Environment 

Now  environment.  What  is  it?  The 
concept  of  environment  also  requires  some 
clarification.  Psychologically,  a  person's 
environment  consists  of  the  sum  total  of 
the  stimulation  which  he  receives  from  his 
conception  until  his  death.  Physical  ob- 
jects are  in  the  environment  only  when 
they  serve  to  stimulate.  There  are  many 
kinds  of  stimulators,  situations  as  well  as 
energy  changes,  objects  and  events,  light 
radiations  and  sound  waves,  as  well  as  a 
teacher's  command,  a  friend's  request,  an 
emotion  or  the  result  of  a  bit  of  thinking. 
The  environment  is  everything  that  affects 
the  individual  except  his  genes.  The  genes 
have  furnished  the  mechanisms  of  behav- 
ior. Only  the  environment  can  actuate 
it,  (an  set  it  going.     Only  the  environment 


can  start  the  learning  of  new  forms  of  be- 
ha\ior  which,  when  established,  must  in 
turn  be  actuated  by  stimulation. 

The  popular  definition  of  environment 
is  a  geographical  or  residential  one.  A 
child  is  said  to  have  a  "poor  en\iron- 
ment,'  for  example,  because  he  lives  in  the 
shuns.  Or  his  'environment'  is  specified 
as  a  French  village,  an  American  small  toAvn 
or  a  British  mining  commiuiity.  Psycho- 
logically these  are  inadequate  characteri- 
zations of  environment.  We  cannot  even 
conclude,  for  example,  that  an  eight-year- 
old  boy  and  his  five-year-old  brother  stand- 
ing in  the  same  room  at  the  same  time  have 
identical  psychological  environments  at 
that  moinent.  The  very  fact  that  the  im- 
mediate environment  of  the  former  in- 
cludes the  presence  of  a  younger  sibling 
and  that  of  the  latter  the  presence  of  an 
older  sibling  constitiues  a  significant  psy- 
chological difference.  Furthermore,  the 
differing  backgrounds  of  previous  experi- 
ence of  the  two  siblings  will  in  ttn"n  catise 
a  difference  in  what  each  gets  out  of  the 
present  situation.  For  such  reasons  it  is 
possible  for  differences  in  abilities,  emo- 
tional characteristics,  interests  and  other 
psychological  characteristics  to  be  found  in 
siblings  and  to  result  from  different  en- 
vironmental influences,  even  though  the 
siblings  have  been  brought  up  in  the  same 
home. 

Structure  and  Function 

It  is  a  mistake  to  speak  of  functions  and 
activities  as  if  they  were  directly  inherited. 
As  we  have  seen,  functions,  activities  and 
all  forms  of  behavior  result  from  the  inter- 
action of  heredity  (the  structures  and  their 
organization)  with  environment.  Func- 
tions as  such  cannot  possibly  be  inherited. 
Can  abilities?  An  ability  is  the  poten- 
tiality -(vhich  you   possess  for  producing  a 


Hereditary  and  Environmental  Influences 


443 


certain  result,  and  the  measure  ol  the  re- 
sult—your performance— is  the  measure  of 
your  ability.  It  is  almost  impossible,  how- 
ever, to  determine  how  much  of  an  ability 
is  the  result  of  heredity.  Consider,  for 
example,  a  race  horse.  Horses  are,  of 
course,  bred  for  speed.  There  must,  there- 
fore, be  unit  characters  that  make  for  a 
body  conformation  that  in  turn  makes  for 
speed.  A  horse,  thus  bred,  must  demon- 
strate his  ability  by  performance.  He  must 
show  what  he  can  do  in  a  race.  But,  before 
the  race,  he  goes  through  a  long  period  of 
training  (environment)  and  in  the  race  he 
runs  in  competition  with  other  horses 
(more  environment)  under  the  guidance  of 
a  jockey  (still  more  environment).  If  he 
wins  his  race  he  has  turned  in  a  good  per- 
formance, but  not  even  the  breeders  them- 
selves can  accurately  evaluate  his  perform- 
ance in  terms  of  heredity  and  environment. 
The  breeding  of  animals  for  some  par- 
ticular ability  has  thrown  some  light  on  the 
influence  of  heredity,  but  in  man  breeding 
still  goes  by  natural  selection.  Since  men 
and  women  mate  for  a  wide  variety  of  rea- 
sons we  have  no  way  of  knowing  for  cer- 
tain whether  there  are  in  fact  unit  char- 
acters for  some  abilities,  for  example,  in- 
telligence. Consequently  many  experi- 
mental techniques  have  been  devised  for 
the  study  of  the  problem.  Some  of  these 
together  with  their  results  we  shall  now 
consider. 

THE    STUDY    OF    HEREDITARY 

AND    EN  VI  RONMENTAL 

INFLUENCES 

The  difficulty  of  isolating  the  influence 
of  heredity  from  that  of  environment  is 
the  chief  problem  ^vhich  must  be  met  by 
investigators  in  this  field.  If  heredity  can 
be  assumed  to  be  constant,  as  in  identical 


twins,  differences  can  be  attributed  to  en- 
vironment. Similarly,  if  environment 
could  be  held  constant,  any  observed  dif- 
ferences would  be  the  result  of  hereditary 
influences.  In  view  of  our  discussion  of 
what,  psychologically,  constitutes  environ- 
ment, it  should  be  apparent  that  it  is  im- 
possible to  hold  environment  wholly  con- 
stant for  any  two  individuals,  especially  for 
human  subjects.  Nevertheless  there  have 
been  many  efforts  to  distinguish  between 
the  effects  of  heredity  and  environment,  and 
to  the  chief  techniques  employed  we  may 
properly  turn  our  attention  now. 

Selective  Breeding 

Since  the  famous  experiments  of  Mendel, 
geneticists  have  made  constant  use  of  se- 
lective breeding  to  investigate  the  inheri- 
tance of  the  characteristics  of  bodily  struc- 
ture. So  far,  however,  the  experimental 
mating  of  animals  selected  on  the  basis  of 
psychological  characteristics  has  been  in- 
frequent. One  such  investigation  has,  how- 
ever, dealt  with  maze  learning  in  white 
rats.  An  initial  group  of  142  rats  were 
given  19  trials  in  running  a  maze,  and  the 
number  of  errors  was  determined  for  each 
animal.  The  group  exhibited  wide  indi- 
vidual differences  in  maze-leaming  ability, 
the  total  number  of  blind-alley  entrances 
in  19  trials  ranging  from  7  to  214.  On  the 
basis  of  these  scores,  a  group  of  the  bright- 
est and  a  group  of  the  dullest  rats  were 
selected  for  experimental  mating.  The 
bright  rats  in  this  parent  generation  (P) 
were  mated  with  each  other  and  the  dull 
were  likewise  mated  together.  This  pro- 
cedure was  followed  through  22  successive 
filial  generations  (Fi  to  F22).  In  each  suc- 
cessive generation,  the  brightest  rats  were 
selected  and  were  bred  togetlier,  the  dullest 
were  selected  and  interbred.  Environment 
—food,    lighting,    temperature    and    li^■ing 


444 


Heredity  and  Environment 


ior^00C7i'-«miDr^o^-^ 

Total  blind  alley  entrances  in  19  trials 
FIGURE   214.      EFFECT  OF  SELECTIVE   BREEDING   FOR 
A    PSYCHOLOGICAL    TRAIT 

Number  of  errors  (blitid-alley  entrances)  in  maze 
learning  of  white  rats  when  brightest  rats  {B,  solid 
line)  are  bred  together  and  dullest  rats  {D,  dotted 
line)  are  bred  together  in  each  successive  genera- 
lion.    Many  errors  =  dullness;  and  conversely.    After 


quarters— was  .kept  constant  for  all  rats  in 
the  different  generations. 

The  effect  of  such  selective  breeding 
upon  maze  performance  is  illustrated  in 
Fig.  214.  The  distribution  curves  indicate 
the  percentage  of  rats  in  each  group  who 
made  the  number  of  errors  given  on  the 
baseline.  It  will  be  noted  that  the  dis- 
tributions of  the  bright  and  dull  subgroups 
gradually  separate  until  there  is  virtually 
no  overlapping  between  them  when  the 
seventh  generation  is  reached.  Beyond 
the  seventh  generation,  the  effects  of  fur- 
ther selective  breeding  were  negligible;  in- 
dividual differences  within  the  bright  and 
dull  groups  remained  virtually  unchanged 
and  the  differentiation  between  the  two 
groups  showed  no  appreciable  increase. 
^Vhen  groups  of  bright  and  dull  rats  were 
bred  with  each  other,  a  distribution  similar 
to  that  of  the  original  parental  group  re- 
sulted; most  of  the  animals  obtained  inter- 
mediate scores,  with  relatively  few  at  the 
dull  and  bright  extremes.  The  distribu- 
tions of  the  bright  and  dull  parental  groups 
and  of  two  such  crossbred  filial  generations 
are  given  in  Fig.  215.  No  simple  relation 
of  dominance  and  recession  holds  for  the 
ability  of  rats  to  learn  mazes.  Here  bright- 
ness and  dullness  mix  like  white  and  black 
in  the  mulatto. 

Such  an  experiment  demonstrates  that 
hereditary  factors  play  an  important  part 
in  the  maze  performance  of  rats.  Through 
what  specific  structural  characteristics  the 
hereditary  influences  operated  is  not,  how- 
ever, indicated.  It  cannot  be  concluded 
that  there  is  a  specific  gene  or  combination 
of  genes  directly  concerned  with  the  trans- 

7  selections  and  7  generations  the  distribution 
curves  hardly  overlap  at  all.  [From  R.  C.  Tryon, 
Thirty-ninth  Yearbook  of  the  National  Society 
for  the  Study  of  Education,  1940,  Part  I,  p.  113.] 


Family  Resemblances 


445 


mission  ol'  any  sikIi  (  h;ira( let  isLi'c  as  iiia/c- 
learning  ability.  'Jlic  lcarninf(  of  a  maze 
was  a  performance  employed  as  a  measure 
of   the   general    ability    tailed    intelligence. 


40 
35 
30 
25 
20 
15 

to 

5 

V   0 


- 

r- Parental  group 

- 

Bright            1 

\                         Dull              Ax 

- 

(A'  =  85i~^ 

\                    (A'=53)^-v'    \            ~ 
\                                        '              ' 

^ 

\                            '                                   *     - 

i\  -  Progeny  of  B  X  O  { W  =  134  > 

15 

- 

- 

10 

- 

/^^/X 

- 

5 
n 

- 

y^           ^ 

^- 

I    I    I    I 
Total  errors  ("normalized"  scale) 

I'lGURE   215.      THE  EFFECT  OF   MATING   BRIGHT  AND 
DULL    RATS 

Reversing  the  selection  shown  in  Fig.  214.  The 
bright  and  dull  maze-learning  rats  were  mated,  and 
at  once  the  progeny  spread  over  the  entire  range 
of  maze-learning  ability,  with  the  average  bright- 
ness more  frequent  than  either  extreme.  [From  R. 
C.  Tryon,  Thirty-ninth  Yearbook  of  the  National 
Society  for  the  Study  of  Education,  1940,  Part  I,  p. 
115.] 

The  results  may  be  regarded  as  showing 
that  this  ability  may  perhaps  be  inherited, 
but  it  is  also  possible  that  hereditary  factors 
may  influence  a  number  of  characteristics, 
such  as  laealth,  physical  vigor,  brain  devel- 


opiiicMt,  eiuirjf  1  iijc  JKihinee,  intensity  of  the 
hunger  drive,  activity  level,  which  in  turn 
affect  indirectly  tlie  ma/e  learning  of  white 
rats.  For  example,  in  the  experiment  just 
described,  clear-cut  differences  in  emotion- 
ality were  observed  between  the  bright  and 
dull  groups. 

Family  Resemblances 

Jt  is  a  cf)iinnon  belie!  that  family  resem- 
blances in  psychological  characteristics 
furnish  direct  evidence  of  the  influence  cjf 
heredity.  Thus  a  child  may  be  described 
as  having  his  father's  flair  for  public  speak- 
ing, his  aunt's  musical  sensitivity,  'taking 
after'  his  paternal  grandfather  in  obsiinacy 
and  inheriting  his  sense  of  humor  from  an 
Irish  grandmother  on  his  mother's  side! 
Nor  is  this  type  of  interpretation  to  be 
found  exclusively  in  naive  popular  discus- 
sions. Many  otherwise  accurate  and  well- 
conducted  studies  on  family  resemblances 
contain  the  same  fallacy  in  that  they  fail 
to  consider  the  fact  that  close  relatives 
commonly  live  together.  The  environment 
of  individuals  who  share  the  same  home 
is  certainly  more  similar  than  that  of  per- 
sons chosen  at  random.  The  closer  the 
hereditary  relationship,  furthermore,  the 
greater,  in  general,  will  be  the  en\iron- 
mental  similarity.  Siblings  usually  live  in 
the  same  home,  but  more  distant  relatives 
—uncles,  nephews,  grandparents,  cousins- 
come  into  less  frequent  contact  and  may 
vary  more  widely  in  socio-economic  back- 
ground and  in  other  environmental  condi- 
tions. Persons  who  live  together  or  are 
associated  in  the  same  community  also 
constitute  in  part  each  other's  environment 
and  may  become  more  alike  by  such  inter- 
action. 

The  two  principal  methods  employed  in 
die  study  of  family  resemblances  are  forn- 
ily  Jiistory  and  correlation.     In  the  family 


446 


Heredity  and  Environment 


history  method,  genealogies  are  traced  and 
pedigree  charts  constructed  for  families 
selected  as  outstanding  either  in  their  tal- 
ents or  in  their  deficiencies.  This  method 
was  launched  by  Francis  Galton  in  1869  in 
his  book  Hereditary  Genius,  where  he  sum- 
marized data  on  997  eminent  men  in  a 
total  of  300  British  families.  Later  studies 
in  different  coimtries  have,  in  general,  cor- 
roborated Galton's  findings.  All  show  that 
eminence  tends  to  run  in  families.  In  some 
families  there  is  even  a  succession  of  per- 
sons of  similar  talents,  as  in  science,  or 
literature,  or  engineering.  Similarly,  the 
investigations  of  degenerate  and  feeble- 
minded families,  of  which  the  most  widely 
quoted  in  the  psychological  literature  are 
known  by  the  pseudonyms  of  the  Jukes  and 
the  Kallikaks,  show  that  svich  characteris- 
tics as  crime,  pauperism  and  other  social 
ills  also  tend  to  run  in  families.  To  argue 
from  such  results  to  hereditary  causation, 
however,  is  not  justified.  The  operation  of 
environmental  family  influences  in  such 
instances  is  too  obvious  to  be  ignored. 

Investigations  by  the  correlation  method 
are  based  upon  the  mental  test  scores  of  a 
group  of  individuals  bearing  a  certain  fam- 
ily relationship  to  each  other.  For  ex- 
ample, pairs  of  siblings  from  one  hundred 
different  families  may  be  given  the  Stan- 
ford-Binet  Intelligence  Test.  The  IQ's  of 
the  two  siblings  in  each  family  are  then 
paired  off  and  a  correlation  coefficient  com- 
puted between  these  two  sets  of  IQ's.  The 
size  of  the  correlation  indicates  the  degree 
of  resemblance  or  correspondence  in  the 
performance  of  siblings  within  the  group. 

The  trend  of  results  in  such  mental  test 
sttidies  is  illustrated  in  the  correlations 
reproduced  in  Table  XXIII.  It  will  be 
noted  that  the  coefficients  fall  into  a  hier- 
archy which  parallels  closely  both  the  de- 
gree of  family  relationship  and  the  extent 


.  TABLE  XXIII 

Hierarchy  of  Correlation  Coefficients  Indicating 
Family   Resemblances   in    Intelligence   Test 
Scores 
[From  A.  N.  VVingfield,  Twins  and  orphans:  the  inheri- 
tance of  intelligence.  Dent,  1928,  p.  106.] 


Correlation 

Type  oj  Relationship 

Coefficient 

Identical  twins 

0.90 

All  fraternal  twins  (both  sexes) 

0.70 

Fraternal  twins  of  unlike  sex 

0.59 

Siblings 

0.50 

Parent  and  child 

0.31 

Cousins 

0.27 

Grandparent  and  grandchild 

0.16 

Unrelated  children 

0.00 

of  environmental  community  and  contact. 
Thus  a  correlation  of  +0.90  is  found  for 
identical  twins,  who  have  identical  heredity 
and  are  also  exposed  to  more  nearly  iden- 
tical environmental  influences  than  any 
other  type  of  siblings.  Fraternal  twins, 
including  both  like-sex  and  unlike-sex  pairs, 
yield  a  correlation  of  0.70,  which  drops  to 
0.59  when  only  unlike-sex  pairs  are  in- 
cluded. In  interpreting  this  drop  we  must 
recall  the  traditional  differences  in  training 
and  play  activities  and  in  attitudes  of  par- 
ents and  associates  toward  boys  and  girls. 
Such  differences  in  the  environments  of  the 
two  sexes  would  serve  to  increase  the  dis- 
crepancy in  ability  between  unlike-sex  fra- 
ternal twins  as  contrasted  to  the  twins  of 
like  sex.  Another  interesting  comparison 
is  that  between  the  total  fraternal-twin  cor- 
relation of  0.70  and  the  sibling  correlation 
of  0.50.  The  degree  of  hereditary  resem- 
blance within  these  two  types  of  family  re- 
lationship is  the  same,  since  all  develop 
from  different  germ  cells  of  the  same  par- 
ents. The  difference  between  these  two 
correlations  can  therefore  be  attributed 
primarily  to  the  greater  environmental 
similarity  of  twins  as  compared  to  siblings 
born  at  different  times. 


Foster  Family  Relaiionships 


447 


On  the  other  hand,  the  difference  be- 
tween the  0.90  correlation  of  identical  twins 
and  the  0.70  of  fraternals  is  more  commonly 
attributed  to  heredity.  A  word  of  caution 
should,  however,  be  added  here.  Because 
of  their  closer  physical  resemblance,  identi- 
cal twins  generally  receive  more  similar 
treatment  than  fraternal  twins.  Fraternal 
twins  may  be  children  who  vary  as  much 
in  health,  physical  vigor  and  attractiveness 
as  two  ordinary  siblings.  Such  physical 
differences  may  in  turn  lead  to  differences 
in  social  acceptance  and  in  attitudes,  inter- 
ests, motivation  and  habitual  activities. 
Furthermore,  it  should  be  noted  that  if 
only  like-sex  fraternal  twins  had  been  con- 
sidered, the  correlation  would  undoubtedly 
have  been  considerably  higher  than  0.70. 
The  identical-twin  correlation  is,  of  course, 
derived  only  from  like-sex  pairs,  for  all 
identical  twins  are  of  the  same  sex.  Sex 
is  inherited;  it  depends  on  a  gene. 

Further  reference  to  Table  XXIII  shows 
that  the  correlations  between  parents-and- 
children,  cousins  and  grandparents-and- 
grandchildren  follow  in  decreasing  order 
of  magnitude.  The  correlation  between 
unrelated  children  is  zero  by  definition, 
since  to  compute  a  correlation  in  such  a 
group  the  children  would  have  to  be  paired 
off  by  chance. 

Foster  Family  Relationships 

Foster  children,  as  well  as  orphans  reared 
in  institutions,  offer  a  special  opportunity 
to  isolate,  to  a  certain  extent,  the  influence 
of  heredity  from  that  of  environment,  since 
such  children  are  not  in  contact  with  per- 
sons related  to  them  by  heredity.  Such 
isolation  is  not,  however,  perfect.  When 
the  children  have  spent  the  first  few  years 
with  their  natural  parents,  an  uncontrolled 
environmental  influence  is  introduced 
which    tends    to   heighten   resemblance    to 


parents.  Nor  can  we  ignore  the  role  of 
prenatal  environment,  with  possible  dif- 
ferences in  the  nutrition  of  the  mother  and 
the  adequacy  of  prenatal  medical  care 
which  usually  occurs  with  difference  in 
socio-economic  level.  At  best  the  isolation 
of  hereditary  and  environmental  factors 
in  such  investigations  is  only  partial. 

Foster  children,  nevertheless,  show  a  rise 
in  IQ  after  adoption  into  a  foster  home. 
The  rise  is  greater  the  younger  the  child  at 
the  time  of  adoption  and  the  higher  the 
socio-economic  level  of  the  foster  home. 
Usually  adoption  means  increase  of  socio- 
economic level,  although  there  may  be  ex- 
ceptions in  the  adoption  of  illegitimate 
children  shortly  after  birth.  The  resem- 
blance between  siblings  living  in  different 
foster  homes,  furthermore,  is  much  less 
than  that  ordinarily  found  between  siblings 
in  the  same  home.  For  example,  in  one 
group  of  125  siblings,  each  of  whom  was 
adopted  into  a  different  foster  home  and 
separated  for  a  period  ranging  from  4  to 
13  years,  the  sibling  correlation  in  Stan- 
ford-Binet  IQ  was  only  0.25,  in  contrast  to 
the  correlation  of  about  0.50  usually  found 
between  siblings  living  together.  Foster 
siblings  who  are  unrelated  by  heredity  but 
live  in  the  same  home,  on  the  other  hand, 
yield  correlations  even  higher  than  0.25. 
Significant  and  moderately  high  correla- 
tions are  also  found  between  the  IQ's  of 
foster  children  and  the  intelligence  test 
scores  of  their  foster  parents.  The  chil- 
dren's IQ's  also  show  good  correlation  widi 
indices  of  the  cultural  level  of  the  foster 
home.  All  these  findings  indicate  how  im- 
portant is  the  role  which  em  ironment  plays 
in  the  development  of  intelligence. 

On  the  other  hand,  certain  investigators 
have  stressed  the  influence  of  heredity  on 
the  giounds  that  the  correlation  between 
the  intelligence  of  foster  parents  and  fostei 


448 


Heredity  and  Environment 


children  is  appreciably  lower  than  between 
children  and  their  own  parents  when  the 
latter  are  living  together.  Thus  in  one 
study  194  foster  children,  adopted  under 
the  age  of  6  months,  were  compared  with 
a  matched  control  group  of  194  children 
living  with  their  own  parents.  The  chil- 
dren in  the  foster  and  control  group  were 
paired  off  in  sex,  mental  age,  father's  occu- 
pation and  father's  and  mother's  school- 
ing. The  socio-economic  levels  of  both 
groups  were  similar  and  quite  homoge- 
neous. The  children  were  5  to  14  years  of 
age  at  the  time  of  testing;  thus  the  foster 
children  had  lived  in  their  adopted  homes 
tor  many  years.  The  correlations  between 
foster  children's  Stanford-Binet  IQ  and 
foster  father's  score  on  the  Otis  Intelligence 
Test  was  0.19,  with  the  foster  mother's  Otis 
score,  0.24,  and  with  the  cultural  index 
of  the  foster  home,  0.26.  In  the  control 
group,  all  three  correlations  were  0.51. 

A  similar  emphasis  upon  hereditary  fac- 
tors is  found  in  an  investigation  on  illegiti- 
mate children  placed  in  an  orphanage  un- 
der the  age  of  one  year  and  reared  there 
together,  without  home  contacts.  Such 
children  developed  large  differences  in  in- 
telligence which  were  found  to  be  corre- 
lated significantly  with  the  socio-economic 
level  of  their  own  parents.  Orphans  of 
merchants  and  professional  men,  for  ex- 
ample, scored  on  the  average  about  10 
points  higher  in  IQ  than  the  orphans  of 
laborers  in  the  same  institution.  Such 
differences  may  result  in  part  from  prenatal 
care  and  in  part  from  hereditary  factors 
which  affect  health,  stamina,  physical  vigor 
and  other  characteristics  and  thus  influence 
'intelligence'  indirectly. 

An  even  more  crucial  isolation  of  factors 
may  be  achieved  in  the  study  of  identical 
twins  who  have  been  separated  in  infancy 
or  early  childhood  and  reared  in  different 


foster  homes.  In  one  investigation  19  such 
pairs  of  twins  were  studied  intensively 
through  psychological  tests,  interviews  with 
the  twins  and  their  associates  and  visits  to 
the  foster  homes.  The  interpair  difference 
in  IQ  ranged  from  1  to  24  points,  with  an 
average  of  8.2.  A  fairly  close  correspond- 
ence was  found  between  difference  in  edu- 
cational opportunities  and  difference  in  IQ 
from  one  twin  to  the  other  in  each  pair. 
Differences  in  personality  characteristics 
tended  to  be  larger,  but  they  also  showed 
the  same  variation  as  the  IQ's,  some  pairs 
being  closely  alike  and  others  very  differ- 
ent. Such  variations  in  interpair  differ- 
ences, both  in  intelligence  and  personality, 
are  not  surprising.  The  accidental  sepa- 
rations of  e\eryday  life,  which  any  one 
pair  of  twins  may  undergo,  cannot  be  re- 
garded in  the  same  light  as  an  experi- 
mentally controlled  segregation.  In  the 
latter  every  effort  is  made  to  choose  en- 
vironments which  are  as  unlike  as  possible, 
in  order  to  make  the  test  more  crucial  and 
the  results  more  distinct.  In  the  19  pairs 
under  consideration,  however,  a  certain 
element  of  chance  entered  into  the  alloca- 
tion of  the  twins  in  each  pair  to  specific 
foster  homes.  Thus  certain  pairs  may 
have  been  adventitiously  adopted  into 
homes  which  differed  markedly,  other  pairs 
reared  in  surroundings  Avhich  shared  a  few 
important  features,  and  still  others  put  in 
environments  which,  although  geographi- 
cally remote,  may  have  been  fundamentally 
alike  in  their  influence  upon  the  gro^^'ing 
child.  Let  us  examine  a  sample  case,  show- 
ing a  relatively  large  discrepancy  between 
the  twins. 

The  case  of  M  and  R.  These  twin  girls 
were  fifteen  years  old  when  examined,  hav- 
ing been  separated  at  the  age  of  three 
months  and  reared,  one  of  them  in  the 
home  of  a  maternal  uncle  and  the  other 


Heredity  and  Maturation 


449 


with  the  uncle's  brolhcr-in-law.  M  lived 
in  a  small  town  where  she  knew  nearly 
everybody  and  had  many  friends  and  play- 
mates. Her  foster  father  was  well  educated 
and  had  a  cultured  home,  with  gcjod  books, 
good  music,  etc.  R  was  brouglit  up  in  a 
large  city  bu^  was  kept  closely  at  home  and 
had  few  friends.  Her  home  environment 
is  described  as  narrow  and  unstimulating. 
Neither  of  her  foster  parents  had  received 
much  education.  Formal  schooling  dif- 
fered little  for  the  twins;  M  was  in  grade 
lOA  and  R  in  grade  lOB  at  the  time  of 
examination.  The  physical  environment 
was  reported  to  be  about  the  same  for  both 
girls.  When  examined,  the  twins  showed 
remarkable  similarity  in  physical  charac- 
teristics. Mentally,  however,  there  was  a 
large  difference,  M  doing  consistently  bet- 
ter on  all  the  tests.  The  Stanford-Binet 
IQ's  were  92  and  77,  respectively,  for  M 
and  R.  In  temperament  their  differences 
were  also  large,  as  indicated  both  by  per- 
sonality tests  and  by  general  observation. 
R  was  described  as  timid  and  retiring,  with 
a  marked  lisp  in  her  speech,  and  appar- 
ently unhappy.  M,  on  the  other  hand, 
seemed  quite  normal  in  emotional  adjust- 
ment. One  might  expect  a  girl  with  few 
friends  not  to  be  very  happy;  the  point 
here  is  that  she  also  had  a  lower  IQ.  The 
IQ  is  favored  by  a  high  level  of  motiva- 
tional alertness  which  may  in  turn  arise 
from  environmental  stimulation. 

Evidence  from  Maturation 

We  have  already  seen  how  the  matura- 
tion of  the  organism  depends  both  on  the 
contribution  of  the  genes  in  heredity  and 
on  the  effect  of  the  environment  and  ex- 
perience as  maturation  proceeds.  In  both 
children  and  infrahuman  animals  new  items 
of  behavior  are  added  to  the  repertoire 
when  certain  levels  of  development  have 


been  reached.  The  child  must  have  usable 
legs  to  walk  on  before  it  can  walk,  but  it 
also  needs  a  certain  development  of  its 
nervous  system.  'J'he  embryo  and  the  fetus 
develop  regularly,  dependent  largely  on 
heredity  for  what  happens  to  them,  but 
also  to  some  extent  upon  the  environment 
as  they  meet  it  in  the  uterus.  A  baby  born 
one  month  prematurely  needs  one  month 
of  development  before  it  is  able  to  do  what 
can  be  expected  of  a  child  born  at  the  nor- 
mal term;  and  a  baby  born  one  month  late 
is  found  to  have  matured  beyond  the  level 
normal  for  a  neonate.  Psychological  age 
at  this  period  is  better  measured  from  the 
time  of  conception  than  from  the  time  of 
birth. 

Further  evidence  on  this  nature-nurture 
problem  has  been  gained  by  controlling  the 
environment  and  noting  whether  matura- 
tion takes  place  without  the  aid  of  nurture. 
How  far,  the  question  is  asked,  can  the 
flying  or  singing  of  birds,  the  swimming  of 
tadpoles  or  the  sexual  behavior  of  monkeys 
develop  in  the  absence  of  relevant  en\iron- 
mental  stimulation?  We  have  seen  that 
preparation  for  them  may  develop  without 
practice  or  exercise,  that  the  unpracticed 
organism  quickly  picks  up  the  new  behav- 
ior when  it  has  matured  enough  and  when 
it  is  at  last  provided  with  the  situations 
that  call  for  the  use  of  the  beha^■ior  (pp. 
79  f.). 

Sometimes  normal  maturation  is  altered 
by  environmental  change.  An  example  of 
this  process  occurs  in  the  sexual  behavior 
of  animals  who  are  reared  in  isolation 
from  other  members  of  their  species  or  in 
exclusive  association  with  individuals  of 
their  own  sex.  They  often  develop  sexual 
perversions  which  persist  after  a  normal  en- 
vironment has  been  provided  for  them. 
Although  the  causes  of  the  comparable  de- 
velopment   in    human    beings    have    been 


450 


Heredity  and  Environment 


much  disputed,  there  seems  to  be  little 
doubt  that  environmental  factors  have 
played  an  important  role  in  the  develop- 
ment of  many,  perhaps  all,  human  sexual 
perversions. 

Of  special   interest   for   the   problem   of 
heredity  and  environment  are  the  experi- 
ments by   the  method  of  co-twin   control. 
This  technique  uses  pairs  of  identical  twins. 
One  member  of  each  pair  is  gi\en  inten- 
sive training  in  certain  functions;  the  other 
is  used   as   the   control   subject,    being   al- 
lowed to  continue  his  normal  everyday  life 
without  special  training.     In  general,  such 
studies  ha\e  shown  that  the  effects  of  spe- 
cific environmental  stimulation  are  either 
slight  or  temporary  in  the  dcA-elopment  of 
motor  and  sensory  behavior  in  young  chil- 
dren.    For  example,  a  pair  of  46-week-old 
identical-twin  girls  were  examined  for  stair 
climbing   and   for    behavior    toward    play 
cubes,  including  their  ability  to  reach  for 
and  grasp  the  cubes,  to  manipulate  them 
and  to  play  constructively  with  them.    The 
trained  twin   (T)   received  20  minutes   of 
training  daily  for  6  weeks.    At  the  end  of 
this  period,  the  control  tAvin  (C),  having 
had  no  specific  training  in  either  function, 
proved  equal  to  the  trained  twin  in  her  be- 
havior with  cubes.    In  stair  climbing,  T  ex- 
celled, but  this  difference  disappeared  after 
C  had  recei\ed  only  2  weeks  of  training. 
Thus,  because  she  was  53  weeks  old  when 
she  began  the  training,  twin  C  was  able 
to   accomplish    in   2  weeks  what   had   re- 
quired  6   weeks   of  training   for   T,   who 
began  when  only  46  weeks  old.     (On  the 
deA'elopment    of    the    twins,    Johnny    and 
Jimmy,  see  pp.  80  f.) 

Experiments  with  human  infants  who 
have  been  artificially  prevented  from  exer- 
cising such  motor  functions  as  standing, 
sitting  or  reaching  for  objects  show  at  first 
considerable    retardation    in    the    develop- 


ment of  these  functions  as  compared  with 
the  norms.  After  only  a  short  unrestricted 
period,  however,  the  normal  activities  ap- 
pear. 

A  natural  experiment  of  this  type  is  fur- 
nished by  the  cradling  practices  prevalent 
in  certain  cultures.  Among  the  Hopi  In- 
dians, for  example,  the  newborn  child  is 
bundled  tightly  in  a  blanket  and  then  tied 
securely  to  a  stiff  board.  In  such  a  posi- 
tion the  infant  cannot  move  his  arms  or 
legs  or  even  turn  his  body.  For  the  first 
three  months  he  is  kept  in  these  wrappings 
except  for  about  one  hour  each  day,  when 
he  is  cleaned  and  bathed.  Despite  this  ex- 
treme early  restriction  of  movement,  Hopi 
children  when  released  later  show  the  same 
sitting,  creeping  and  walking  behavior  and 
in  the  same  sequence  as  white  American 
children.  During  the  short  daily  periods 
when  they  are  freed  of  their  wrappings, 
furthermore,  they  assume  the  usual  flexed 
position,  reach  for  objects  and  carry  them 
to  the  mouth,  reach  for  their  toes  and  put 
them  into  the  mouth,  and  manifest  the 
other  characteristic  motor  behavior  of  an 
unrestricted  infant.  No  significant  differ- 
ence has  been  found  between  the  average 
walking  age  of  Hopi  infants  cradled  in  the 
traditional  manner  and  other  Hopi  chil- 
dren who  were  reared  in  the  manner  of 
white  American  children. 

Effect  of  an  Unusual  Environment 

There  are  some  instances  of  children 
who  have  grown  up  wild  with  animals  and 
then  have  been  brought  into  civilization. 
The  results  do  not  indicate  that  this  is  a 
good  way  to  prepare  children  for  modern 
civilization,  but  the  accounts  of  what  the 
children  were  like  contain  so  many  vague 
interpretations  that  they  cannot  be  reduced 
to  the  status  of  scientific  data.  Besides 
there   was   no   control,    no   identical    twin 


Environment  and  Development 


451 


who  was  not  brought  up  by  wolves  and 
went  to  gTanimar  school  inslcadl 

There  is,  however,  on  record  the  case  of 
a  human  infant  and  a  chimpanzee  infant 
who  were  for  nine  months  reared  together, 
(Other  details  of  this  case  have  already  been 
reported  on  p.  81.)  The  chimpanzee  infant, 
Gua,  was  isolated  from  lier  mother  at  the 
age  of  7)/,  months  and  lived  in  the  psy- 
chologist's home,  together  with  his  10- 
months-old  son.  The  chimpanzee  was 
treated,  not  as  a  pet,  but  as  a  child,  and 
the  two  infants  were  given  as  nearly  identi- 
cal care  as  possible.  A  photograph  of 
them  is  reproduced  in  Fig.  216.  Gua  wore 
the  same  articles  of  clothing  as  the  child 
and  manifested  no  difficulty  in  keeping  on 
her  shoes,  stockings  and  other  clothing. 
She  slept  in  her  own  bed  equipped  with 
pillow,  sheets  and  blankets.  She  learned 
upright  locomotion  quickly,  although  that 
is  not  normal  to  chimpanzees.  Gua  also 
made  excellent  progress  in  learning  to  eat 
with  a  spoon  and  drink  out  of  a  glass. 
She  was  able  to  manipulate  pencil,  crayons 
and  paper  to  produce  simple  scribblings. 
She  also  learned  to  respond  correctly  to 
oral  language,  and  by  the  end  of  the  ex- 
perimental period  understood  over  fifty 
words  or  simple  phrases,  such  as  "Show  me 
your  nose,"  "Take  it  out  of  your  mouth," 
"Do  you  want  to  go  bye-bye?"  and  "Blow 
the  horn."  The  degree  to  which  it  proved 
possible  to  'hvimanize'  the  behavior  of  this 
ape  is  especially  significant  in  view  of  the 
shortness  of  its  residence— nine  months— in 
a  human  environment. 

Let  there  be  no  mistake,  however,  about 
this  matter.  Environment  was  not  the 
only  influence  effective  on  Gua's  behavior. 
Gua  could  not  have  been  made  into  a 
homely  child,  sent  to  high  school  and  col- 
lege or  put  to  work  in  a  store.  Heredity 
was    limiting    her,    not    only    in    personal 


beauty  as  judged  by  human  standards,  but 
also  in  intelligence  and  many  other  psycho- 
logical characteristics,  while  at  the  same 
time  it  was  giving  her  superhuman 
strength.  The  boy  soon  outstripped  the 
ape  in  verbal  facility,  and  the  ape  the  boy 
in  ability  to  climb  and  jump. 


FIGURE   2l6.      HUMAN    IMAM    A.\U    CHIMPANZEE 
INFANT  REARED  TOGETHER 

For  nine  months  the  two  infants  were  reared  to- 
gether. In  Fig.  36,  p.  81,  another  such  pair  is 
shown.  [From  W.  N.  Kellogg  and  L.  A.  Kellogg, 
The  ape  and  the  child,  McGraw-Hill,  1933,  p.  275.] 

Effect  of  Parents'  Socio-economic 
and  Occupational  Status 

Comparison  of  the  intelligence  test 
scores  of  children  reared  in  different  socio- 
economic le^•els  presents  less  dramatically 
the  same  type  of  environmental  dissimilari- 
ties and  concomitant  behavior  differences 
observed  in  wild  children.  Altliough  over- 
lapping is  lai-ge,  as  in  most  group  compari- 
sons, it  can  be  said  diat  the  average  IQ  of 
children  shows  a  consistent  relationship  to 
their  father's  occupational  level.    In  an  in- 


452 


Heredity  and  Environmenf 


vestigation  on  380  preschool  children  be- 
t^veen  the  ages  of  18  and  54  months,  for 
example,  the  average  Kuhlman-Binet  IQ's 
of  the  children  of  unskilled  laborers  was 
95.8,  that  of  the  children  of  professional 
men  125.0.  The  average  IQ's  of  the  inter- 
mediate occupational  groups  fell  consis- 
tently between  these  two  extreme  values. 
In  another  study,  a  group  scale  of  intelli- 
gence was  administered  to  6688  elementary 
school  children  and  1433  high  school  stu- 
dents. The  results  were  similar.  The  num- 
ber of  children  in  each  occupational  group, 
together  with  the  median  and  range  of 
IQ,  are  given  in  Table  XXIV. 

TABLE  XXIV 

IQ  OF  Children  in  Relation  to  Father's  Occu- 
pation Level 
[From    M.    E.   Haggerty   and   H.   B.   Nash,  /.   educ. 
Psychol.,  1924,  15,  569  f.] 


Elementary  School 

High  School 

Children 

Students 

Father's 

Occupational 

Level 

No. 

Median 

Range 

No. 

Median 

Range 

Cases 

IQ 

inlQ 

Cases 

IQ 

inlQ 

I.  Professional 

349 

116 

70-177 

201 

121 

80-167 

2.  Business  and 

clerical 

944 

107 

54-169 

374 

112 

60-168 

3.  Skilled 

1028 

98 

54-177 

54 

111 

69-139 

4.  Semiskilled 

524 

95 

53-152 

267 

108 

78-149 

S.  Farmer 

3098 

91 

50-161 

48 

108 

90-159 

6.  Unskilled 

745 

89 

51-146 

489 

106 

72-155 

^Vc  note  there  that  the  occupational 
group  differences  tend  to  be  smaller  in  the 
older  groups— the  high  school  groups  as 
compared  with  the  elementary  school 
groups.  This  difference  may  result  in  part 
from  selection,  the  duller  children  in  all 
occupational  groups  having  left  school  be- 
fore reaching  the  high  school  level,  and  in 
part  from  the  equalizing  influence  of  the 
common  school  environment.  The  associa- 
tion   between    father's    occupational    level 


and  children'^  IQ  in  itself  could  be  inter- 
preted as  the  result  of  either  hereditary  or 
environmental  influences,  or  both.  Thus 
it  might  be  argued  that  the  brighter  fa- 
thers are  more  likely  to  qualify  for  higher 
le\el  occupations  and  are  likewise  more 
likely  to  have  brighter  children.  On  the 
other  hand,  the  sujaerior  home  environ- 
ment furnished  by  fathers  in  the  higher 
occupational  levels  may  have  determined 
the  higher  IQ's  of  the  children  in  these 
levels. 

The  testing  of  children  reared  in  isolated 
rural  communities  and  other  environments, 
which  provide  but  limited  opportunities 
for  intellectual  development,  furnishes  data 
bearing  upon  these  two  interpretations. 
Children  living  under  these  conditions  are 
not  exposed  to  equalizing  school  influences 
as  they  grow  older,  since  their  formal 
schooling  is  itself  inferior.  Their  other 
contacts  outside  the  home  are  usually  few 
and  of  the  same  general  level  as  those 
within  the  home.  In  such  groups  the  aver- 
age IQ's  of  young  children  is  close  to  the 
normal,  but  it  decreases  sharply  in  the 
older  groups.  Thus  in  one  investigation 
of  children  living  in  an  isolated  mountain 
community  in  Kentucky,  the  median  IQ 
dropped  steadily  from  83.5  at  age  7  to  60.6 
at  age  15.  It  would  hardly  be  heredity 
producing  that  change.  Presently  we  shall 
see  how  rural  and  urban  children  compare 
in  intelligence. 

A  survey  conducted  in  England  on  a 
group  of  children  living  on  canal  boats 
and  a  group  of  gypsy  children  showed  simi- 
lar trends.  Both  groups  of  children  had 
very  inferior  schooling,  being  able  to  at- 
tend school  only  during  short  periods  of 
each  year.  Home  en\ironment  was  also 
intellectually  inferior,  many  of  the  parents 
being  illiterate. 

The  average  IQ  of  all   the  canal  boat 


Culture  and  Infelligence  Testing 


453 


children,  whose  school  attendance  was  esti- 
mated to  be  only  about. 5  per  cent  of  that 
of  ordinary  elementary  school  children,  was 
69.6.  An  analysis  of  the  IQ's  by  age  level, 
however,  shows  a  marked  negative  correla- 
tion (-0.75)  between  IQ  and  age.  Most  of 
the  yoinigest  children  had  IQ's  between  90 
and  100.  Among  the  eldest,  on  the  other 
hand,  were  several  IQ's  which,  at  face 
value,  would  have  led  to  the  diagnosis  of 
feeblemindedness.  A  comparison  of  sib- 
lings again  revealed  a  consistent  drop  in 
IQ  from  the  youngest  to  the  oldest  child  in 
the  same  family. 

The  scores  of  the  gypsy  children  corrob- 
orated in  general  the  conclusions  reached 
with  the  canal  boat  children,  although  the 
gypsy  children  as  a  group  obtained  some- 
what higher  IQ's.  This  finding  is  under- 
standable in  view  of  the  better  schooling 
of  this  group,  their  school  attendance  be- 
ing approximately  35  per  cent  of  the  nor- 
mal in  contrast  to  the  canal  boat  children's 
5  per  cent. 

The  decline  in  IQ  with  age  in  these 
groups  suggests  the  influence  of  environ- 
ment. Under  normal  conditions  the  IQ 
remains  very  nearly  constant  at  different 
ages.  In  these  atypical  environments,  how- 
ever, the  inadequate  education  and  re- 
duced opportunities  for  intellectual  devel- 
opment become  increasingly  influential 
with  age.  The  intellectual  requirements  of 
a  three-year-old  child  can  be  satisfied  about 
as  adequately  on  a  canal  boat  or  in  an  iso- 
lated mountain  community  as  in  a  prosper- 
ous urban  home.  The  older  child,  how- 
ever, with  his  broadening  intellectual 
needs,  will  be  seriously  affected  by  these 
environmental  limitations. 

At  the  other  extreme,  we  may  note  that 
gifted  children  generally  come  from  homes 
whose  social  and  cidtural  level  is  above 
average.     Terman,  you  will  recall,  in  his 


study  of  California  school  children  with 
IQ's  of  140  or  above,  found  that  the  cul- 
tural rating  of  the  homes,  as  well  as  ihc 
educational  level  reached  by  parents  and 
grandparents,  were  well  above  the  average 
of  the  general  population,  although  income 
levef  was  not.  An  analysis  of  the  fathers' 
occupations  showed  nearly  one-third  (31 
per  cent)  to  be  in  professions,  50  per  cent 
in  semiprofessional  or  higher  business  oc- 
cupations, 11.8  per  cent  in  skilled  lafjor 
and  less  than  7  per  cent  in  semiskilled  or 
unskilled  labor  (see  p.  427). 

Urban,  Rural  and  Regional  Influences 

In  most  current  intelligence  tests,  chil- 
dren in  rural  areas  receive  lower  average 
scores  than  those  living  in  cities.  This 
difference  is  greater  in  those  districts  with 
poorer  school  facilities,  as,  for  example, 
those  having  only  one-room  schools.  The 
difference  between  rinal  and  urban  chil- 
dren is  larger  in  verbal  than  in  perform- 
ance tests,  and  larger  in  individual  than  in 
gioup  scales.  A  possible  explanation  of 
the  latter  finding  is  the  rural  child's  greater 
shyness  with  strangers,  which  may  handicap 
his  performance  in  tests  administered  bv 
an  outside  examiner.  In  the  administra- 
tion of  an  individual  test,  this  difficldt^ 
shoidd  be  in  part  overcome  by  the  exam- 
iner's tact  and  skill. 

We  should  also  note  that  the  majority  of 
intelligence  tests  have  been  standardized 
largely  or  even  exclusively  wida  city  chil- 
dren. Thus  the  selection  of  content,  allo- 
cation of  items  to  difficidtv  le^•els  or  age 
levels  and  the  establishment  of  nonns  have 
been  based  primarily  upon  the  perfonu- 
ance  of  children  reared  in  urban  environ- 
ments. The  influence  of  sucli  a  selection 
is  indicated  in  a  iew  investigations  in 
which  the  process  was  re\ersed,  die  choice 
and  placement  of  items  being  determined 


454 


Heredity  and  Environment 


with  rural  samplings.  In  a  test  so  con- 
structed, the  urban  children  as  a  group 
turned  out  to  make  the  poorer  showing. 

The  comparison  of  rural  children  of  dif- 
ferent ages  reveals  the  same  trend  in  intelli- 
gence test  scores  obser\ed  in  isolated  or 
educationally  limited  environments.  In  an 
intensive  study  of  farm  children  in  Iowa, 
for  example,  the  older  children  were  found 
to  be  farther  below  the  urban  norm  than 
the  younger.  Thus  a  group  of  123  infants 
between  the  ages  of  4  and  40  months 
showed  no  noticeable  inferiority  to  urban 
norms  on  the  Iowa  Baby  Tests.  Nor  could 
this  lack  of  urban-rural  difference  be  at- 
tributed to  inadequate  discriminative 
power  of  the  tests,  since  wide  individual 
differences  were  repealed  by  these  tests.  In 
a  preschool  group  of  163  children  between 
the  ages  of  3  and  6  years  tested  with  the 
Detroit  Kindergarten  Test,  an  inferiority  of 
the  rural  children  appeared  at  ages  5  and 
6,  but  no  significant  difference  was  found 
in  the  lower  age  levels.  A  group  of  871 
rural  school  children,  however,  showed  a 
clear  mental  retardation  which  increased 
with  age. 

In  addition  to  this  difference  between 
urban  and  rural  groups,  other  regional  in- 
fluences have  been  found.  In  the  United 
States,  for  example,  differences  in  intelli- 
gence test  performance  occur  among  differ- 
ent states,  paralleling  closely  the  educa- 
tional opportunities  available  in  each  state. 
Similarly,  clear-cut  differences  in  average 
intelligence  test  score  have  been  noted  be- 
tween northern  and  southern  Negroes.  On 
Army  Alpha,  for  example,  the  median 
scores  of  northern  and  southern  Negroes 
were  38.6  and  12.4,  respectively,  and  on 
Beta  (a  performance  test)  32.5  and  19.8. 
Similar  results  have  been  obtained  in  stud- 
ies with  Negro  school  children.  So  large 
are    the   regional    differences   among   both 


Negroes  and  whites,  in  fact,  that  the  'racial 
difference'  may  be  completely  reversed 
when  comparing  samples  from  different 
regions.  For  example,  the  median  Alpha 
score  of  Negro  soldiers  from  certain  north- 
ern states  was  higher  than  that  of  white 
soldiers  from  some  southern  states  which 
were  poor  in  educational  facilities. 

The  poorer  performance  of  rural  and 
other  regional  groups  on  intelligence  tests, 
per  se,  could  be  interpreted  in  terms  of 
either  selective  migration  or  environmental 
handicap.  The  former  hypothesis  main- 
tains that  the  more  progressive,  intelligent 
or  energetic  families  are  attracted  to  the 
more  favorable  localities,  whereas  the 
duller  and  less  ambitious  remain  in  the 
poorer  areas.  The  action  of  such  a  se- 
lective process  for  several  generations 
would,  according  to  this  hypothesis,  even- 
tually produce  a  segregation  of  the  inferior 
stock  in  the  regions  which  offer  fewer  op- 
portunities. Urban-rural  and  other  re- 
gional differences  in  intelligence  would 
thus  be  attributed  primarily  to  an  heredi- 
tary basis.  The  hypothesis  of  environmen- 
tal handicap,  on  the  other  hand,  attributes 
regional  inferiority  to  the  poorer  facilities 
for  schooling  and  other  educational  oppor- 
tunities, as  well  as  differences  in  home  en- 
vironment, parental  education,  play  activi- 
ties,  traditions  and  other  cultural  factors. 

Many  of  these  results  on  urban-rural  dif- 
ferences in  'intelligence'  suggest  the  en- 
vironmental explanation,  although  the  ex- 
planation by  heredity  is  not  ruled  out. 
There  are,  however,  a  few  other  studies 
which  furnish  direct  evidence  in  support 
of  the  environmental  explanation.  Thus 
among  Negro  children  who  had  migrated 
from  the  countr)'  to  the  city,  it  was  found 
that  the  longer  the  period  of  their  resi- 
dence in  the  urban  environment,  the  higher 
was    their   averasie    intelligence    test   score. 


Culture  versus  Biology 


455 


Another  technique  consisted  of  the  exam- 
ination of  the  previous  rural  school  records 
of  both  white  and  Negro  children  who  had 
subsequently  migrated  to  cities.  In  no 
case  was  the  migrating  group  superior  to 
the  nonmigrating  at  the  time  when  both 
were  living  in  the  same  area.  Studies  of 
Negro  children  who  had  moved  from  the 
South  to  the  North  yielded  results  similar 
to  those  for  rural-urban  migrations. 

Cross-comparisons  of  Cultural 
and  Biological  Groups 

Another  fruitful  approach  to  this  anal- 
ysis of  the  hereditary  and  environmental 
contributions  to  the  psychological  reper- 
toire is  the  comparison  of  overlapping  bio- 
logical and  environmental  groupings.  The 
same  individuals,  for  example,  may  be 
classified  according  to  nationality  and 
'racial'  category.  The  former  is  a  cultural 
and  environmental  classification,  the  latter 
a  biological  category  based  upon  physical 
characteristics.  This  approach  is  illus- 
trated by  an  investigation  conducted  on 
boys  from  ten  to  twelve  years  old  in  rural 
areas  of  Germany,  France  and  Italy.  Each 
of  these  countries  contains  more  than  one 
of  the  subgroups  of  the  Caucasian  race  in 
its  population.  In  Geimany,  Nordic  and 
Alpine  samples  were  obtained;  in  France, 
Nordic,  Alpine  and  Mediterranean  sam- 
ples; and  in  Italy,  Alpine  and  Mediter- 
ranean samples.  The  boys  were  selected 
from  those  areas  in  which  'pure  types'  of 
each  of  these  physical  subgroups  were  sup- 
posed to  be  most  likely  to  be  found.  Only 
boys  born  in  each  specified  area,  whose 
parents  had  also  been  born  in  that  area, 
were  included.  The  boys  were  further 
chosen  on  the  basis  of  their  eye  color,  hair 
color  and  cephalic  index  so  as  to  fall  within 
the  specified  limits  of  Nordic,  Alpine  or 
Mediterranean  stocks.     Six  tests  from  the 


Pintner-Paterson  Performance  Scale  were 
administered  with  brief  oral  instruction!! 
in  the  child's  own  language.  VV'hen  the 
boys  were  classified  as  Nordic,  Alpine  and 
Mediterranean,  without  regard  to  national- 
ity, no  reliable  difference  in  average  score 
was  found.  Larger  and  reliable  differ- 
ences appeared,  on  the  other  hand,  among 
the  three  national  groups,  when  the  three 
racial  groups  were  combined.  Marked  var- 
iation was  observed,  furthermore,  within  a 
single  racial  group  when  samples  of  differ- 
ent nationalities  were  compared.  The  dif- 
ference between  two  Nordic  groups  of  dif- 
ferent nationality,  for  example,  was  larger 
than  that  between  the  Nordic  and  Medi- 
terranean groups  as  a  whole. 

The  major  role  played  by  en\ironmen- 
tal,  rather  than  biological,  factors  in  deter- 
mining group  difl:erences  is  also  indicated 
in  a  study  of  Indian,  Negro  and  white 
school  boys  in  the  United  States.  Selected 
tests  from  the  Pintner-Paterson  Scale  were 
also  used  in  this  investigation.  The  Indian 
boys  included  a  group  attending  a  govern- 
ment school  and  a  group  living  on  an  In- 
dian reservation.  Similarly,  two  groups 
were  Negi'o  boys,  one  from  Ne'^v  York  City 
and  another  from  rural  AVest  \'irginia. 
The  white  boys  were  taken  from  New  York 
City,  rural  West  Virginia  and  a  rural  dis- 
trict near  the  Indian  reservation.  A  com- 
parison of  average  scores,  especially  in 
speed  of  performance,  yielded  much  larger 
differences  between  two  groups  of  the  same 
race  living  in  different  regions  than  be- 
tween different  racial  groups  in  the  same 
region.  Thus  tlie  Ne-i\-  York  City  Negro 
boys  did  better  than  those  in  rural  West 
Virginia,  and  the  government  school  In- 
dians scored  higher  tlian  tlie  reser\-ation 
Indians.  These  differences  were  larger 
than  the  differences  among  white.  Indian 


456 


Heredity  and  Environment 


and   Negro   boys   as   a   whole   or   in    com- 
parable areas. 

You  now  have  a  fair  sample  o£  the  evi- 
dence. 

THE    HEREDITY-ENVIRONMENT 

QUESTION:    PRESENT 

STATUS 

So  what  makes  the  adult?  Heredity  or 
environment?  His  genes  or  the  life  he  has 
lived  since  he  was  conceived?  Obviously 
both.  Both  in  general,  and  both  in  par- 
ticular. There  is  no  item  of  the  behavior 
repertoire,  no  intellectual  trait  nor  person- 
ality characteristic  that  is  wholly  independ- 
ent of  the  genes  of  its  possessor  or  of  the 
events  which  haxe  altered  him  since  he 
began  living.  Those  events  include,  of 
course,  all  his  learning,  but  besides  learn- 
ing, and  genes,  there  are  the  effects  upon 
the  organism  of  health  and  disease  and 
accidents.  They  too  help  to  make  the 
adult  what  he  is. 

If  we  are  so  sure  about  this  answer,  why 
do  we  say  that  this  question  of  heredity 
and  environment  is  a  problem,  a  contro- 
versial problem?  Because  we  want  to  know 
how  much  of  each  factor  is  effective.  Ac- 
tually what  we  are  after  is  knowledge  of 
how  to  change  people,  knowledge  of  how 
much  they  can  be  changed.  The  solutions 
of  all  the  great  social  problems,  all  social 
progiess,  depend  on  that.  Is  our  behavior 
as  fixed  and  stereotyped  as  the  behavior  of 
bees  and  ants,  who  have  a  very  well-organ- 
ized totalitarian  and  socialistic  order,  or 
can  present  experience  and  learning  undo 
what  the  genes  and  past  experience  seem  to 
have  fixed?  No  wonder  everyone  is  curious 
about  the  answer  to  this  question. 

Present-day  psychologists  are  not  in 
agreement  on  this  matter.    Some  lean  more 


heavily  upon  heredity,  others  upon  environ- 
ment, in  their  explanations  of  behavior. 
Even  when  all  the  approaches  are  taken 
into  consideration,  the  available  data  are 
still  inadequate  for  a  conclusive  answer. 
As  in  all  experimental  design,  the  essen- 
tial prerequisite  is  the  control  of  condi- 
tions in  such  a  way  that  all  variables  shall 
be  constant  except  the  one  whose  influence 
is  being  investigated.  Since  in  nearly  all 
investigations  of  individual  and  group 
differences,  the  two  variables— heredity 
and  environment— have  operated  together 
though  differentially,  the  resulting  data 
are  usually  ambiguous  and  incapable  of 
definitive  interpretation.  The  crucial  ex- 
periment is  yet  to  be  performed. 

It  is  correct  to  state  that  general  agree- 
ment exists  regarding  the  interaction  of 
hereditary  and  environmental  influences  in 
the  development  of  all  characteristics, 
structural  as  w'ell  as  behavioral.  It  is  the 
degree  to  which  any  one  aspect  of  behavior 
depends  upon  structural  limitations  trace- 
able to  heredity  and  the  degree  to  which 
it  depends  upon  the  accumulated  effects  of 
environment  that  is  the  area  of  controversy. 

In  the  development  of  motor  and  sen- 
sory capacities,  the  role  of  hereditary  fac- 
tors is  commonly  emphasized.  The  results 
of  developmental  studies  on  young  chil- 
dren and  animals  are  cited  in  support  of 
such  a  view.  The  close  dependence  of 
motor  and  sensory  functions  upon  physical 
structures  makes  such  functions  more  di- 
rectly susceptible  to  hereditary  determina- 
tion although  both  capacities  depend  in 
part  on  environmental  influences.  In  intel- 
lectual functions,  extreme  deviations  in 
either  direction  from  the  norm  often  re- 
flect, in  part,  the  influence  of  health,  stam- 
ina, endurance,  glandular  activity  or  path- 
oloaiical  conditions  which  make  normal  in- 


tellcctual  develojjincnl  impossible.  Inso- 
far as  these  influences  axe  effective,  liered- 
ity  is  playing  a  part.  Within  the  broad 
range  of  intermediate  deviations,  the  range 
which  includes  most  persons,  the  role  of 
heredity  is,  however,  much  less  apparent. 
It  is  in  regard  to  such  minor  individual 
differences  in  intellectual  functions  that 
one  finds  the  greatest  divergence  of  opin- 
ion among  psychologists.  In  respect  of 
emotional  and  social  characteristics,  atti- 
tudes, moral  standards  and  other  aspects  of 
personality,  most  psychologists  recognize  a 
major  contribution  by  environmental  fac- 
tors. 

To  those  whose  chief  concern  is  with  so- 
cial progress,  who  fear  that  heredity  may 
make  the  human  race  as  unprogressive  as 
the  ants,  the  answer  is  this:  There  is  plenty 
of  opportunity  for  change  and  develop- 
ment. The  genes  may  have  been  altered 
little  since  the  dawn  of  history,  yet  look  at 
what  civilization  has  accomplished!  Even 
intelligence,  as  the  tests  test  it,  is  not  be- 
yond improvement.  And  the  personality 
traits,  the  psychological  items  that  worry 
the  social  planners  most,  are  notoriously 
dependent  on  learning  and  not  on  the 
genes.  The  trouble  with  the  traits  is  that 
they  tend  to  get  fixed  in  childhood,  so  that 
we  turn  up  with  an  adult  society  that  is 
almost  as  unalterable  as  if  it  were  gene- 
determined.  Infantile  fixations,  however, 
are  not  gene-determined.  The  matter  of 
their  adjustment  belongs  in  a  later  chapter 
(pp.  516-523). 


Heredity  and  Environment:  Present  Status  457 

e  [itoljlcin  (A  heredity  and  cnviron- 


REFERENCES 

1.  Anastasi,    A.      Differential    psycljology. 
York:   Macmillan,   1937. 


Ne\\' 


Icrjtioti  lo 
riicnl. 

2.  Irceniari,  I'.  S.  Individual  ilijjerenres.  New 
York:   Holt,  1934. 

An  elementary  treat ment  of  individual  and 
fjroup  dilFercnces,  including  many  Mudics  on 
the  cfleds  of  heredity  and  environment. 

3.  Cilliland,  A.  R.,  and  Clark,  E.  I..  Psycholofry 
of  individual  differences.  New  ^'ork:  Prentice- 
Hall.  1939. 

Another  more  recent  textbof>k  on  individual 
:iri(l  group  differences,  including  .some  of  I  he 
heredity-environment  data. 

4.  Hegner,  R.  W.  College  zoology.  (.5tfi  ed.) 
New  York:  Macmillan,  1943.     Chap.  35. 

This  chapter  is  a  good  orientation  in  the 
l)io!ogical  mechanism  of  heredity  for  those 
students  who  have  not  had  courses  in  biolog)' 
at  the  college  level. 

5.  Jennings,  H.  S.  The  biological  basis  of  human 
nature.     New  York:  Norton,  1930. 

A  famous  biologist's  discussion  of  the  roles 
of  genes  and  environment  in  human  develop- 
ment and  of  the  social  implications  for  eugen- 
ics, the  family  and  intermarriage. 

6.  Kellogg,  W.  N.,  and  Kellogg,  L.  A.  The  ape 
and  the  child.    New  York:  McGraw-Hill,  1933. 

Report  of  the  widely  quoted  experiment  in 
^vhich  a  young  chimpanzee  was  reared  in  the 
manner  of  a  human  child. 

7.  National  Society  for  the  Study  of  Education. 
Thirty-ninth  yearbook:  Intelligence,  its  nature 
and  nurture.    Chicago,  1940.    Parts  I  and  II. 

The  tivo  volumes  of  this  yearbook  consti- 
tute a  rich  source  of  research  data  on  the  roles 
of  heredity  and  environment  through  the  anal- 
ysis of  mental  test  scores.  Topical  survevs,  criti- 
cal articles  and  original  studies  are  included. 


H.,  Freeman,  F.  N.,  and  Holz- 
Twins:  a  study  of  heredity  and 
Chicago:    Universitv   of   Chicago 


An  introduction  to  the  psychology  of  indi\id- 
iial  and  group  differences,  with  considerable  at- 


Newman,   H. 
inger,   K.  J. 
environment. 
Press,  1937. 

Survey  of  research  on  nineteen  pairs  of  iden- 
tical t^vins  who  had  been  reared  apart. 

Schwesinger,  G.  C.    Heredity  and  environment. 
New  York:   Macmillan.  1933. 

A  critical   sin\ev  of  the  psvchological   litera 


458                                             Heredity  and  Environment 

ture  prior  to  1933  on  the  effect  of  heredity  and  11.  Woodworth,  R.  S.     Heredity  and  environment, 

environment.  Soc.  Sci.  Res.  Council  Bull.,  1941,  No.  47. 

10.  Snvder,  L.  S.     The  principles  of  heredity.     (3rd  A  clear  presentation  and  critical  analysis  of 

ed)     Boston:  Heath,  1946.  recent   material   on    twins  and   foster   children, 

The  latest  revision  of  one  of  the  most  widely  with  reference  to  its  implications  for  the  rela- 

known  standard  textbooks  on  genetics.  tion  of  heredity  to  envnonment. 


CHAPTER 


20 


Efficiency 


CONSIDERATION  of  the  conditions 
tor  efficient  human  action  constitutes 
an  important  chapter  of  psychology.  These 
are  the  sort  of  questions  put  to  psycholo- 
gists: "What  are  the  most  efficient  condi- 
tions of  study?"  "Is  efficiency  impaired  by 
the  use  of  alcohol  and  tobacco?"  Such 
questions  have  known  answers,  but  to  state 
the  answers  we  shall  have  first  to  come  to  a 
clear  understanding  of  what  is  meant  by 
efficiency. 

The  psychologist's  and  the  physiologist's 
notion  of  human  efficiency  is  derived  from 
the  concept  of  mechanical  efficiency.  In 
order  to  get  a  machine  to  work  we  must 
supply  it  with  energy,  and  the  efficiency  of 
a  machine  is  defined  as  the  ratio  of  the  use- 
ful work  it  performs  (output)  to  the 
amoinit  of  energy  it  consumes  (input).  Ef- 
ficiency =  Output/Input.  For  example,  the 
efficiency  of  a  good  automobile  engine 
is  said  to  be  about  twenty-five  per  cent  be- 
cause only  about  one  quarter  of  the  energy 
of  the  gasoline  is  converted  into  useful 
work,  the  rest  being  lost  as  heat.  In  gen- 
eral, the  greater  the  output  per  unit  of 
input,  or,  conversely,  tlae  smaller  the  input 
per  unit  of  output,  the  greater  is  the  effi- 
ciency of  the  machine. 

In  a  similar  manner  we  conceive  of  hu- 
man efficiency  as  the  ratio  between  achieve- 
ment (output)  and  the  cost  of  ivork  to  the 


organism  (input),  and  we  set  ourselves  the 
task  of  determining  the  methods  and  con- 
ditions of  work  which  will  lead  to  maxi- 
mum achievement  at  a  minimum  cost. 

Research  upon  the  practical  control  of 
human  efficiency  has  been  developed  ex- 
tensively in  the  past  few  decades.  There 
are  two  major  phases  of  this  research.  One 
major  advance  has  occurred  in  the  area  of 
vocational  selection  and  guidance,  which 
is  the  subject  of  a  subsequent  chapter. 
The  invention  of  techniques  for  the  meas- 
urement of  skill,  aptitude,  interest  and 
temperament  makes  it  possible  to  assign 
men  to  jobs  for  which  their  individual 
characteristics  best  suit  them.  It  is  obvious 
that  a  man  ^vho  is  working  at  a  job  for 
which  he  has  little  aptitude,  or  which  does 
not  interest  him,  is  working  inefficiently. 
His  level  of  production  will  be  low,  and  the 
cost  of  his  output  will  be  unnecessarily 
high. 

The  other  major  phase  of  this  research, 
and  the  subject  of  the  present  chapter,  is 
the  discovery  of  the  most  efficient  methods 
and  conditions  of  work.  Even  if  a  man 
has  the  right  job,  he  does  not  necessarily 
work  as  efficiently  as  he  might.  The  way 
he  performs  his  task  and  the  conditions 
under  which  he  works  are  important  vari- 
ables. Progress  toward  a  solution  of  these 
practical   problems   depends,    however,    on 


This  chapter  was  prepared  by  M.  E.  Bitterman  and  T.  A.  Ryan  of  Cornell  University. 

459 


460 


Efficiency 


the  cle\eIopnient  of  dependable  measures 
of  efficiency.  To  that  problem  -we  turn 
our  attention  first. 

MEASUREMENT    OF    HUMAN 
EFFICIENCY 

Since  efficiency  is  output  tU\idecl  by  in- 
piu.  to  measure  efficiency  ^ve  ha\e  to  meas- 
ine  both  these  factors. 

Output:  Evaluation  of  Performance 

Output  is  measured  by  the  amount  of 
the  product  produced— the  number  of 
pages  read,  the  number  of  bricks  laid,  the 
number  of  pieces  assembled  on  the  assem- 
bly line.  You  cannot  compare  a  page  read 
with  a  brick  laid,  but  seldom  do  you  wish 
to.  WTiat  you  want  to  know  is  whether 
certain  conditions  get  more  pages  read  or 
more  bricks  laid  than  other  conditions.  Is 
it  more  efficient  to  read  under  direct  or 
indirect  illumination?  How  do  outdoor 
temperature  and  humidity  affect  the  effi- 
ciency of  brick  laying? 

The  problem  seems  simple  enough  with 
pages  and  bricks,  but  it  becomes  difficult 
when  the  product  is  a  coinplicated  high- 
level  activity.  How  do  you  measure 
amount  of  good  piloting  of  an  airplane? 
In  the  Second  World  War  the  Army  was 
reduced  to  the  use  of  a  rating  scale  which 
was  of  doubtful  reliability;  yet  it  was  im- 
portant that  it  know  what  training  meth- 
ods produced  good  results,  and  how  good 
the  product  was. 

A  better  method  than  the  rating  scale  is 
to  set  up  some  standard  test  of  pilot  per- 
formance. You  arrange  to  ha\'e  every  pilot 
whose  efficiency  is  being  measured  fly  a 
bomber  from  one  predetermined  point  to 
another  at  a  fixed  speed  imder  specified 
weather  conditions.  You  set  up  this  task 
as  a  constant  standard.    Then  you  see,  not 


how  much  you  get  out  of  the  pilot,  but  ho^v 
much  you  have  to  put  into  him  to  get  him 
trained  to  this  required  standard  of  expert- 
ness.  In  other  words,  you  measure  effi- 
ciency by  input  instead  of  output. 

Input:  Expenditure  of  Bodily  Resources 

Input  is  best  regarded  as  the  cost  of 
work  to  the  organism.  In  general  the  cost 
is  known  by  fatigue.  For  how  much  fa- 
tigue can  you  get  this  amount  of  the 
product? 

Fatigue  is  not  easily  measured,  yet  it  is  a 
common  experience.  Any  continued  ■vvork 
in\'olves  effort,  e\'en  reading  a  detective 
story.  You  can  note  when  you  are  done, 
how  much  the  reading  has  tired  you. 
Often  you  are  aware  of  effort  while  you  are 
making  it.  It  is  easier  to  lift  a  50-pound 
bar-bell  with  two  hands  than  with  one.  It 
is  easier  to  read  by  the  light  of  a  100-watt 
lamp  than  by  the  light  of  a  candle.  It  is 
easier  to  study  in  a  room  at  70°  F  than  in 
one  at  45°.  Effort  is  different  in  the  dif- 
ferent cases,  and  so,  after  the  work  is  done, 
is  fatigue. 

Fatigue  of  some  sort  is  characteristic  of 
all  continued  effort  or  activity.  The  or- 
ganism wants  change,  at  least  eventually. 
As  the  need  for  change  increases,  the  or- 
ganism's effort  increases.  If  it  does  not, 
the  quality  and  rate  of  its  performance 
suffer. 

Fatigue  is  best  defined  as  reduction  in 
efficiency  resulting  from  continuous  ^\ork. 
There  are  two  ways  of  measuring  it.  (1) 
If  a  suitable  index  of  effort  is  available, 
fatigue  can  be  taken  as  the  increase  in  ef- 
fort per  imit  of  accomplishment  ^vhen  work 
is  continued.  (2)  Or  fatigue  may  be  re- 
garded as  the  physiological  changes  which 
produce  this  loss  in  efficiency  with  contin- 
ued work. 

The  initial  efficiency  of  a  given  method 


Measurement  of  Efficiency 


461 


is  not  necessarily  its  later  efficiency.  Fa- 
tigue may  come  on  faster  with  one  methocl 
tlian  with  another.  If  you  have  five  letters 
to  sign,  you  Iiacl  best  sit  clown  and  do  it 
quickly  without  any  fuss,  for  that  way  of 
doing  the  job  is  most  efficient.  You  can 
even  do  it  while  standing.  On  the  other 
hand,  if  you  have  a  hundred  letters  to  sign, 
you  had  better  fuss  a  little— make  yourself 
comfortable,  get  the  best  pen,  arrange  the 
letters  systematically,  for  you  will  tire  less 
and  thus  turn  out  to  be  more  efficient  in 
the  long  lun,  even  though  you  are  less  ef- 
ficient on   the  first  five  letters. 

Physiological  Indicators  of 
Effort  and  Fatigue 

At  the  present  time  we  do  not  know  a 
great  deal  about  the  physiology  of  effort. 
We  should  like  to  know  what  bodily 
changes  go  on  when  effort  is  expended; 
then  we  could  measure  effort  by  measiuing 
these  changes.  Let  us  see  exactly  what  is 
the  extent  of  our  knowledge  in  this  field. 

(1)  Oxygeji  consumption.  Since  the 
body  is  a  machine  which  converts  food 
energy  into  useful  work,  it  is  reasonable 
to  assume  that  the  energy  released  in  the 
body  during  work  should  provide  a  good 
index  of  effort  expenditure.  We  cannot, 
liowevef,  use  food  consumption  as  a  meas- 
ure of  energy  cost  for  any  given  period  of 
time,  because  the  body  stores  up  food  with- 
out consuming  it.  On  the  other  hand, 
using  the  food  consumes  oxygen,  which 
cannot  be  stored,  and  thus  oxygen  con- 
sumption itself  can  be  used  as  a  measure 
of  energy  expenditure.  For  each  liter  of 
oxygen  consumed,  about  five  calories  of 
energy  are  liberated  in  the  body,  although 
this  value  varies  to  some  extent  with  diet. 

Figure  217  illustrates  a  technique  for 
measuring  oxygen  consumption  which  is 
employed  when  freedom  of  locomotion  is 


desirable.  The  subject  inliales  the  sur- 
rounding air  Ijut  exhales  into  a  sack  at- 
tached If)  his  person.  Ry  comparing  the 
oxygen  cfjiiiciii  ol  the  inspired  and  expired 
air  it  is  possible  to  compute  the  amount  of 
oxygen  consumed.  Other  more  tonvenient 
and  accurate  devices  are  available  for  ex- 


FIGURE   217.      THE  MEASUREMENT  OF  OXYGEN   CON- 
SUMPTION   DURING    PHYSICAL    WORK 

[After  A.  V.  Hill,  Muscular  movement  in  man, 
McGraw-Hill,  1927,  p.  9.] 

periments  in  which  the  subject  can  remain 
attached  to  a  stationary  apparatus. 

This  technique  was  used  to  compare  the 
efficiency  of  pushing  a  load  -vvith  that  of 
pulling  it.  A  number  of  different  loads 
were  used.  The  ^vork  was  measured  in 
meter-kilograms  (mkg).  This  unit  is  the 
amount  of  work  required  to  push  or  pull 
one  kilogi-am  through  a  distance  of  one 
meter.  The  oxygen  ^vas  measured  and  the 
consumed  calories  computed.  Table  XX\' 
gi\'es  the  results.  At  each  of  the  four  loads 
pushing  is  more  efficient  (uses  less  oxvgen) 
than  pulling,  and  both  pushing  and  pull- 
ing are  most  efficient  at  13.6  kilosiams. 


462 


Efficiency 


TABLE  XXV 

Relative  Energy  Cost  of  Pushing  and  Pulling 

Input  is  energy  or  oxygen  consumed  in  calories. 
Output  is  work  in  meter-kilograms  pushed  or  pulled. 
Thus  efficiency  is  output/input  in  mkg/cal.  [Data 
from  E.  Atzler,  Ergebnisse  der  Physiol.,  1928,  27,  742.] 


efficiency 

mkg/cal 

oad,  kg 

Pushing 

Pulling 

10.3 

0.109 

0.094 

11.6 

0.111 

0.098 

13.6 

0.115 

0.102 

16.1 

0.112 

0.101 

If  oxygen  consumption  i.s  a  valid  indi- 
cator of  effort,  and  prolonged  effort  pro- 
duces fatigue,  we  should  expect  oxygen 
consumption  to  be  related  to  fatigue.  Fig- 
ure 218  presents  sample  curves  that  show 
changes  in  the  rate  of  oxygen  consump- 
tion in  the  course  of  work  in  a  printing 
factory.  The  increasing  rate  of  oxygen 
utilization  indicates  a  decrease  in  efficiency 
with  the  passage  of  time. 


The  use  of  oxygen  consumption  as  a  meas- 
ure of  the  cost  of  work  is  limited  largely 
to  those  activities  which  involve  the  gio.ss 
bodily  musculature.  Sedentary  activities— 
often  called  'mental'— such  as  reading  a 
book  or  solving  an  arithmetic  problem  re- 
quire the  expenditure  of  physical  energies 
which  are  so  minute  that  it  is  almost  im- 
possible to  measure  them  reliably  by  meth- 
ods now  available. 

(2)  Cardiovascular  indicators.  The  func- 
tioning of  the  cardiovascular  or  circulatory 
system— the  heart  and  the  blood  vessels- 
gives  evidence  of  being  related  to  energy 
expenditure.  It  is  possible,  for  example, 
by  combining  measures  of  blood  pressure 
and  heart  rate  to  derive  an  index  known 
as  pulse  product  which  is  correlated  with 
oxygen  consumption  in  muscular  work. 
The  measurement  of  blood  pressure  is  a 
rather  cumbersome  procedure,  however, 
and  very  often  requires  the  interruption  of 

18.2 


Casting  Room 

15 

f^^ 

5^ Ji 

Restine         ,^„„ ■ — ' 

5 i 

9.^—- 

i 

'mm/mm 

'mm. 

eM 

'mm 

'mm. 

mm///. 

5  P.M. 


10 


11 


Composing  Room 


Resting 

level 


2.6 


9.58 


13  13.4 


8  P.M.  9  10  11  12  1A.M.  2  3  4 


18.9 


20.4 


FIGURE  2  1 8.      INCREASING  RATE  OF  OXYGEN  CONSUMPTION   DURING  WORK   IN    PRINTING   FACTORY 

Shows  oxygen  consumption  for  1^^  hours  work  in   casting  room  and   composing  room  for   12   nights. 
[After  A.  D.  Waller  and  G.  DeDecker,  /.  Physiol.,  1919,  S3,  cvi.] 


Physiological  Indicators  of  Effort  and  Fatigue 


463 


activities  in  progress.  Heart  rate,  on  the 
other  hand,  tan  be  recorded  very  easily. 
The  small  electrical  changes  which  spread 
through  the  body  during  each  'beat'  of  the 
heart  are  aniplilied  and  used  to  activate  a 
pen  writing  on  a  moving  sheet  of  paper. 
The  procedure  recjuires  only  that  two  small 
metal  disks  (called  electrodes)  be  taped 
firmly  to  the  body  of  the  sufjject.  These 
electrodes  may  be  connected  to  the  ampli- 
fiers by  wires  long  enough  to  permit  free- 
dom of  activity.  In  Fig.  219  there  is  a 
record  of  heart  rate. 

Heart  rate  is  usually  higher  during  seden- 
tary work  than  during  rest,  and  frequently 
it  is  found  to  rise  as  work  continues.  If 
we  compare  two  conditions  of  work  which 
we  can  assume  to  be  different  in  difficulty, 
we  find  that  heart  rate  is  sometimes  higher, 
and  never  lower,  for  the  more  difficult  task. 
For  example,  in  one  recent  experiment 
heart  rate  was  found  to  be  greater  during 
mental  work  done  in  the  presence  of  in- 
tense distraction  than  during  work  under 
conditions  of  comparative  silence,  despite 
the  fact  that  the  quality  of  performance 
was  the  same  in  both  cases.  Heart  rate  is 
not,  however,  as  certain  an  indicator  as 
would  be  desirable. 

(3)  Muscular  tension.  There  is  reason 
to  believe  that  muscular  tension  will  ulti- 
mately furnish  us  with  a  sensitive  and  con- 
venient index  of  effort  expenditure.  The 
muscles  of  the  body  always  show  a  certain 
minimal  level  of  activity  or  tension,  and 
tension  seems  to  be  a  function  of  the  dif- 
ficulty of  a  task  and  the  adequacy  of  the 
conditions  under  which  the  work  is  done. 
In  one  early  experiment,  for  example,  a 
group  of  subjects  was  set  to  work  trans- 
lating code.  The  typewriters  used  for  the 
task  were  so  constructed  that  it  -vvas  pos- 
sible to  record  the  pressure  exerted  on  the 


keys.  When  work  was  done  in  the  presence 
cjf  loud  noise,  much  mcjre  pressure  was  ex- 
erted than  under  the  ccjntrol  conditicjns  ol 
cjuiet.  It  has  also  been  demonstrated  that 
tension  and  restlessness  increase  in  the 
course  of  sedentary  work  as  the  subjects 
become  fatigued. 

In    modern    experiments    very    sensitive 
electrical     measurements     of     tension     are 


4 — I — / — f — 1—4-4- 


12  3  4  5  6  7 

Time  in  seconds 

Muscle  potentials 

I I I I I I I 

12  3  4  5  6  7 

Time  in  seconds 

FIGURE    219.       GRAPHIC    RECORDS    OF    HEART    BEATS 
AND   MUSCLE   POTENTIALS 

The  upper  figure  is  the  graphic  record  of  the 
heart  rate.  The  lower  figure  is  the  graphic  record 
of  the  electrical  potentials  arising  from  tension  in 
the  triceps  muscle  of  the  arm. 

made.  All  muscular  activity  gives  rise  to 
very  small  changes  of  electrical  potential 
(voltage)  which  can  be  picked  up  through 
a  pair  of  small  silver  electrodes  taped  to 
the  skin  over  the  muscle  in  question,  and 
suitably  amplified  and  recorded.  Figirre 
219  shows  a  sample  of  the  kind  of  record 
which  is  obtained.  In  one  experiment  the 
subjects  were  asked  to  relax  upon  a  couch 
and  potentials  arising  from  the  muscles  of 
their  arms  were  recorded.  When  the  sub- 
jects were  given  simple  arithmetic  prob- 
lems to  do  'in  their  heads,'  the  recording 
apparatus  indicated  a  significant  increase 
in  muscle  tension.     The  more  difficult  the 


464 


Eificiency 


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problems,    the   greater   were    the   potential 
changes  registered. 

There  is  some  evidence  that  muscle  ten- 
sions facilitate  'mental'  ^v'ork  and  help  the 
organism  to  compensate  for  and  overcome 
resistances  encountered  in  its  cotnsc.  For 
example,  it  has  been  discovered  that  ten- 
sions artificially  induced  by  instructing  the 


26 

24 

i  22 

^20 

i 

■§  18 
•S  16 

C 

o  14 


10 

0    5    10  15    5    10  15  20  25  30  0    5    10  15  20   0    5    10 
Minutes 

FIGURE  220.      ELECTRICAL  RESISTANCE  OF  THE  SKIN 
DURING   REST  AND   DURING   MENTAL   WORK 

[After  T.  K.  Kirby,  in  A.  G.  Bills,  The  psychol- 
ogy of  efficiency,  Harper,  1943,  p.  119.] 

subject  to  pull  on  a  weight  speed  up  the 
learning  of  nonsense  syllables.  Perhaps 
furrowing  the  brow  really  does  help  think- 
ing. It  is  quite  often  that  the  feeling  of 
effort  in  'exerting  one's  will'  comes  from 
tension  in  the  facial  muscles. 

(4)  Skin  resistance.  The  electrical  re- 
sistance of  the  skin  is  another  indicator  of 
exertion.  As  muscle  tension  increases,  skin 
resistance  decreases,  that  is  to  say,  the  skin 
becomes  more  conductive.  Measurement 
of  this  resistance  requires  much  less  tech- 
nical skill  than  is  needed  for  the  measure- 
ment of  muscle  potentials.  Figure  220 
shows  how  skin   resistance   falls  rapidly   at 


the  onset  of  mental  work  and  remains  low, 
rising  rapidly  again  at  the  termination  of 
the  work.  The  fact  that  emotion  has  an 
effect  on  the  electrical  resistance  of  the 
skin  must  be  taken  into  account  in  the 
use  of  til  is  method  in  the  measurement  of 
exertion. 

(5)  Fatigue  products.  Muscular  activity 
gives  rise  to  certain  chemical  end  products, 
notably  lactic  acid,  which  probably  are  re- 
sponsible in  part  for  fatigue  effects.  These 
products  may  be  found  in  the  muscles 
themselves  or  in  the  blood  stream  which 
carries  them  from  the  muscles  of  origin  to 
the  organs  of  excretion.  The  importance 
of  this  function  of  the  blood  is  suggested 
by  the  fact  that  muscle  groups  deprived  of 
their  blood  supply  become  fatigued  and 
lose  the  power  of  contraction  long  before 
those  whose  blood  supply  is  intact.  The 
adverse  effect  of  fatigue  products  is  demon- 
strated by  the  fact  that  the  symptoms  of 
fatigue  can  be  produced  in  a  rested  animal 
if  it  is  injected  with  a  quantity  of  blood 
taken  from  a  fatigued  one. 

AtlemjDts  to  discover  fatigue  products  re- 
sulting from  activities  other  than  gross 
muscular  work  have  thus  far  been  largely 
unsuccessful.  Recent  studies  of  pilot  fa- 
tigue, however,  suggest  that  some  chemical 
measure  of  fatigue  may  presently  be  foimd. 

Measuring  Efficiency  and 
Fatigue  by  Performance 

The  worker  turns  effort  into  the  product 
of  his  work.  If  he  keeps  at  work  he  also 
turns  effort  into  fatigue. 

Effort  is  important.  You  cannot  meas- 
ure efficiency  and  fatigue  unless  you  can 
measure  effort  or  at  least  keep  it  constant. 
Too  often  in  industry  a  change  of  condi- 
tions, which  increases  production,  is  sup- 
posed to  increase  efficiency.  That  conclu- 
sion follows  only  if  there  is  control  of  the 


Measuring  Efficiency  and  Fatigue  by  Performance 


465 


eftorl  which  ihc  workers  put  into  the  j)io- 
duction. 

There  is  a  well-known  experiment  whitli 
illustrates  this  point.  The  workers  were 
engaged  in  assembling  electrical  fixtures, 
and  records  of  their  production  were  kept 
as  the  illumination  under  which  they 
worked  was  increased.  1  hey  worked  first 
at  24  foot-candles,  then  at  46  and  finally 
at  70.  With  each  increase  in  iliuniination 
production  increased.  Do  not  such  results 
show  that  increased  illumination  increases 
efficiency?  No,  they  do  not,  lot  in  a  sec- 
ond part  of  the  experiment  production  was 
found  to  increase  regularly  when  illumina- 
tion was  decreased.  This  experiment  was 
begun  at  an  illumination  of  10  foot-candles 
which  was  then  regularly  decreased  until 
finally  at  3  fpot-candles  the  workers  began 
to  complain  that  they  could  not  see  what 
they  were  doing.  Why  did  any  change  in 
illumination,  up  or  down,  increase  produc- 
tion? Because  the  change  increased  the 
workers'  motivation,  anci  increase  of  mo- 
tivation increases  effort.  The  workers  were 
responding  not  to  the  improved  visual 
acuity  which  goes  with  greater  illumina- 
tion, but  to  the  seeming  interest  of  man- 
agement in  their  welfare.  They  were  pre- 
pared to  work  harder,  to  put  more  effort 
into  their  jobs  because  they  believed  that 
working  conditions  had  been  bettered. 

The  c]uestion  can  be  raised  as  to  whether 
management  did  not  really  get  increased 
efficiency  with  lowered  illumination.  Cer- 
tainly it  got  greater  production— at  the 
start.  The  output  was  increased  and  the 
input,  in  terms  of  workers'  pay,  was  con- 
stant. The  input  in  terms  of  workers'  ef- 
fort "was  not,  however,  constant.  It  cost  the 
workers  more  effort  to  assemble  parts  at 
lowered  illumination,  even  if  at  first  it  cost 
management  the  same  number  of  dollars. 
Had  the  low  illumination  been  continued, 


fatigue  would  have  been  greater,  and  the 
increased  motivation  would  not  have  re- 
mained high.  Management  was  fooling  the 
workers,  making  the  work  harder  and  let- 
ting them  suppose  that  it  was  trying  to 
make  the  work  easier.  The  factory's  effi- 
ciency was  up  temporarily,  but  the  worker's 
efficiency  was  not,  for  he  had  increased  his 
input  of  effort. 

Jt  is  not  often  the  case  that  any  change 
in  working  conditions  by  management 
leads  to  increased  output  merely  because 
the  workers  have  confidence  that  manage- 
ment is  acting  in  their  interests.  Too  often 
an  'efficiency  expert'  devises  a  new  method 
for  doing  a  job  and  then,  with  no  evidence 
that  he  has  cut  effort  in  half,  asks  for  dou- 
ble production.  Piece  rates  are  then  cut, 
and  the  worker  must  increase  his  total  ef- 
fort or  accept  less  pay.  At  first  production 
may  gain  at  the  expense  of  the  worker,  bnt 
usually  there  is  no  permanent  gain,  not 
even  for  the  factory.  The  demand  for 
greater  effort  presently  results  in  gi^eater 
waste,  poorer  cjuality,  increased  rates  of 
turnover,  absenteeism,  sickness,  accident 
and  unfavorable  public  relations.  The 
workers  suspect  that  management  is  trying 
to  make  the  work  harder  and  the  effort 
greater,  and  they  build  up  their  own  stand- 
ards of  what  constitutes  a  fair  day's  work. 
These  standards  they  maintain  bv  social 
pressure.  A  violator  is  labeled  a  'rate 
buster'  and  subjected  to  scorn  and  ostra- 
cism. In  this  way  labor  builds  up  its  de- 
fense against  the  'efficiency  expert'  and  the 
'speed-up,'  all  because  the  'efficiency  ex- 
pert' is  developing  a  false  increase  in  effi- 
ciency. The  true  efficiency  expert— the 
methods  engineer  or  industrial  engineer,  as 
they  like  to  be  called— knows  that  the  way 
to  increase  efficiency  is  to  reduce  effort.  If 
the  engineer  aims  at  increase  of  individual 
efficiency  by  decreasing  the  necessary  input 


466 


Efficiency 


of  effort,  he  may  find  that  the  workers  re- 
spond by  maintaining  effort  constant  and 
gi\ing  the  .tattory  more  production.  In 
that  case  both  personal  and  industrial  ef- 
ficiency are  increased  together,  and  effi- 
ciency remains  high  because  it  is  supported 
by  good  morale. 

Laboratory  Tests  of  Efficiency 

Since  many  of  the  conditions  of  work  can 
be  duplicated  in  the  experimental  labora- 
tory, efficiency  has  been  measured  there. 
The  speed  test  is  one  of  the  more  common 
techniques.  In  it  the  subject  is  asked  to 
work  at  maximal  effort,  and  the  experi- 
menter undertakes  to  see  how  much  he  can 
produce  under  different  conditions.  Il- 
lumination, temperature,  humidity,  distrac- 
lion,  distribution  of  rest  periods  can  all  be 
A  aried  and  the  effect  of  the  changes  on  pro- 
duction noted.  Such  speed  tests  are  not, 
howeAer,  as  reliable  as  they  would  be  if 
effort  could  be  satisfactorily  controlled. 
Merely  telling  a  man  to  use  maximal  effort 
does  not  make  sure  that  he  will.  Nor  does 
the  worker's  conscious  intent  to  use  maxi- 
mal effort  insure  his  doing  so. 

For  instance,  you  can  measure  strength 
of  grip  with  a  hand  dynamometer.  You 
ask  your  subject  to  squeeze  the  handles 
each  time  as  hard  as  he  possibly  can,  and 
you  hope  to  measure  his  fatigue  by  keeping 
effort  constant  and  noting  how  strength  di- 
minishes in  successive  squeezes.  But  effort, 
intended  to  be  inaximal,  is  not  constant. 
If  you  tell  your  subject  that  he  is  to  make 
fifteen  successive  contractions,  each  as 
strong  as  he  possibly  can  make  it,  he  will 
give  you  fifteen  contractions  diminishing  in 
strength,  but  the  first  contraction  will  not 
be  so  strong  as  it  is  when  you  ask  him  to 
give  you  but  a  single  contraction  as  strong 
as  jiossiblc.     His  knowledge  that  he  lias  fif- 


teen efforts  to  make  reduces  his  'maximal' 
effort  on  the  first  trial. 

It  is  also  true  that  when  a  muscle  be- 
comes so  fatigued  that  its  owner  'can  no 
longer  mo\e  it,*  a  sudden  increase  in  mo- 
tivation, like  pride  in  showing  off  before 
an  important  person,  will  often  result 
in  movement  of  the  'exhausted'  muscle. 
Great  feats  of  strength  performed  in  emer- 
gencies are  partly  due  to  this  ability  of  mo- 
tivation to  command  reserves  of  effort,  al- 
though also  to  the  more  fully  understood 
ways  in  which  emotion  increases  efficiency 
by  endocrine  secretion   (pp.   95  f.). 

There  are  other  expei  iments  which  show 
how  unpredictable  degree  of  effort  in  the 
input  may  be.  Ordinarily  you  would  ex- 
pect a  distraction  to  reduce  efficiency,  but 
actually  potential  distractors  often  work  in 
the  opposite  way.  Persons  may  be  working 
at  what  they  think  is  maximal  speed  on  an 
intelligence  test.  A  loud  noise  is  sounded 
in  the  room.  It  bothers  them.  They  screw 
themselves  up  in  their  chairs,  grit  their 
teeth,  grasp  their  pencils  harder  and  go 
determinedly  on,  with  the  result  that  they 
do  more  work  within  the  time  limits  than 
they  would  have  done  without  the  poten- 
tial distractor,  which  really  acted  as  a  stim- 
ulator to  effort.  Measurement  of  heart  rate 
and  muscle  tension  show  that  the  'both- 
ered' subject  is  truly  giving  more  to  his 
task  tlian  lie  was  able  to  gi\'e  by  '\oluntary 
intention.' 

Work  Decrement 

The  attempt  has  often  been  made  to 
measure  fatigue  b)  plotting  production 
against  the  duration  of  continued  work. 
This  method  uses  work  decrement  as  a 
measure.  If  we  could  assume  that  effort 
remained  constant  during  the  day,  the 
work  decrement  woidd  be  a  \ery  satisfac- 
tory measure  ol   fatigue.     A   typical   work 


Methods  of  Working 


467 


curve  for  a  day  in  a  faclory  shows  pro- 
duction increasing  at  first  as  the  worker 
warms  up,  then  decreasing  steadily  through- 
out the  morning,  rising  a  little  as  the  lunch 
hour  approaches,  falling  further  through- 
out the  afternoon,  rising  again  in  anticipa- 
tion of  the  quitting  time.  These  irregu- 
larities in  the  curve  obviously  are  not  due 
to  fatigue  alone.  They  are  the  result  of 
a  mixtine  of  fatigue  and  the  variations  of 
effort  due  to  boredom  and  the  anticipation 
of  release  from  work.  It  shows  what  man- 
agement can  normally  expect  from  workers, 
but  not  the  efficiency  of  the  worker. 

When  a  work  curve  actually  rises  as  work 
is  continued,  it  is  likely  that  the  worker  is 
exerting  greater  effort.  Often  a  worker 
consciously  tries  to  compensate  for  his  fa- 
tigue, attempting  to  keep  his  output  con- 
stant. He  may  succeed  for  a  while  or  even 
overcompensate,  doing  better  as  he  gets 
more  fatigued.  Sooner  or  later,  of  course, 
a  decrement  will  appear,  because  the 
worker  cannot  or  'will'  not  exert  the 
amount  of  effort  required  to  maintain  his 
previous  level  of  performance. 

Summary 

We  may  summarize  our  discussion  of 
the  various  means  and  methods  of  meas- 
uring efficiency  by  saying  that  we  could 
study  efficiency  mucli  better  if  we  knew  how 
to  control  input.  Output  by  itself  tells 
nothing  about  efficiency,  which  depends 
upon  output's  relation  to  inpvit.  Input  is 
what  the  worker  puts  into  the  work,  his 
effort.  We  ought  to  be  able  to  measure  it, 
or  at  least  to  keep  the  worker's  contribu- 
tion constant,  so  that  we  can  discover  the 
effect  of  changing  other  conditions  upon 
the  output.  At  present  attempts  at  accu- 
rate measurement  of  efficiency  remain  un- 
satisfactory because  we  are  so  uncertain  of 
the  cost  of  work  to  the  working  organism. 


As  we  turn  next  in  iliis  fhapter  to  some  o( 
the  practical  generalizations,  we  must  re- 
member that  word  of  caution.  Exact 
knowledge  in  the  field  of  human  efficiency 
waits  upon  more  knowledge  of  the  physi- 
ology of  work  and  effort. 

METHODS    OF    WORKING 

Any  given  task  can  usually  be  accom- 
plished in  a  variety  of  ways,  some  of  which 
are  more  efficient  than  others.  This  con- 
sideration is  extremely  important  even  in 
so  simple  a  job  as  carrying  a  load,  as  Fig. 
221  shows.  The  development  of  the  best 
methods  of  work  is  one  of  the  most  im- 
portant problems  in  the  field  of  human 
efficiency. 

The  'Natural'  Way  versus 
the  'One  Best'  Way 

A  worker  who  is  given  a  job  but  not 
given  any  information  as  to  how  it  should 
be  done  is  not  likely  to  work  out  the  most 
adequate  method.  Even  after  years  of  ex- 
perience, he  may  still  be  using  inadequate 
methods.  To  appreciate  this  fact  it  is  only 
necessary  to  compare  the  performance  of 
an  athlete  trained  by  a  skillful  coach  with 
that  of  an  athlete  who  had  no  benefit  of 
coaching,  or  the  performance  of  a  trained 
typist  witli  that  of  a  person  who  has 
learned  by  trial-and-error.  That  the  'nat- 
ural' or  spontaneous  method  of  doing  a  job 
is  not  necessarily  the  best  method  is  further 
demonstrated  by  the  following  example 
taken  from  industrial  practice. 

The  work  in  question  was  the  inspection 
of  tin  plates  for  imperfections.  The  in- 
spector's task  was  to  leaf  through  a  pile  of 
plates  in  much  the  same  ^v^av  as  a  reader 
leafs  through  the  pages  of  a  book  and  to 
remove  any  defective  plates  from  the  pile. 
The    natural    tendency    of    the    untrained 


468 


Efficiency 


Oxygen  consumption 
133 


Hip  [ 


115 


Head 


100 


Shoulder 


Yoke 


FIGURE  221.  RELATIVE  EFFICIENCY  OF  FOUR  DIF- 
FERENT  METHODS    OF   CARRYING   A    3O-POUND    LOAD 

Bars  shoiv  oxygen  consumption  per  horizontal 
kilogram-meter.  [Adapted  from  E.  M.  Bedale,  In- 
dustrial Fatigue  Research  Board  Report,  No.  29, 
His  Majesty's  Stationery  Office,  1921,  p.  37.] 

worker  was  to  inspect  each  plate  as  she 
turned  it  from  one  pile  to  the  second  (Fig. 
222,  left),  just  as  if  turning  the  pages  of  a 
book.  As  the  first  sheet  was  being  turned, 
side  la  and  then  side  \b  were  examined; 
then  the  next  sheet  was  turned,  and,  while 
it  was  being  turned,  sides  2a  and  then  26 


(the  two  sides  of  the  second  sheet)  were 
examined.  This  method  made  for  inac- 
curacy since  it  required  the  inspection  of 
moving  surfaces.  Investigation  led  to  the 
development  of  a  new  method  which  re- 
quired the  worker  to  ignore  the  plate  in 
motion  and  inspect  the  one  at  rest.  First 
side  Ifl  would  be  inspected;  then  side  2a 
would  be  inspected  as  the  first  sheet  was 
being  turned;  then  as  the  second  sheet  was 
being  turned,  first  side  16  and  then  side  Sa 
would  be  examined;  as  the  third  sheet  was 
being  tinned,  sides  2b  and  4fl  would  be  ex- 
amined, and  so  on  (Fig.  222,  right).  Adop- 
tion of  the  new  method  led  to  a  consider- 
able improvement  in  accuracy. 

While  studies  of  this  sort  indicate  that 
the  problem  of  deAeloping  suitable  meth- 
ods should  not  be  left  entirely  to  the 
worker,  there  is  a  question  as  to  how  far 
standardization  can  be  pushed.  Many  in- 
vestigators proceed  on  the  principle  that 
there  is  'one  best'  way  of  doing  any  given 
job  and  that  all  workers  should  be  re- 
quired to  adopt  this  method  with  no  varia- 
tion in  detail.  On  the  other  hand,  the 
facts  of  individual  differences  suggest  the 
possibility  that  a  method  which  is  best  for 
one  individual  inay  not  be  best  for  another. 
This  problem,  however,  does  not  have  a 
great  deal  of  practical  importance.  First, 
the  procedures  employed  for  selecting  work- 
ers usually  narrow  the  range  of  individual 
differences  to  a  very  great  extent.  Second, 
we  are  usually  more  interested  in  the  effi- 
ciency of  groups  than  in  the  efficiency  of 
individuals,  and  a  new  method  may  be  re- 
garded as  more  efficient  than  the  old  if  it 
increases  the  efficiency  of  most  members  of 
a  group,  despite  the  fact  that  it  may  reduce 
the  efficiency  of  certain  individual  workers. 
The  workers  adversely  affected  can  be 
transferred  to  new  jobs  for  which  they  are 
better  suited. 


The  "natural"  way  is  wrong 


This  learned  way  is  right 


Q) 


r\ 


r\ 


r\ 


r\ 


r^ 


0 


(t) 


FIGURE   222.      ANALYSIS  OF  TWO   METHODS   OF   INSPECTING   TIN   PLATES 

Five  successive  phases  of  the  ■natinal'  way  and  of  the  better  learned  way.  The  sheets  are  turned  over 
(semicircular  arrow)  from  the  inspector's  left  to  her  right.  The  upper  arrow  in  each  sketch  shows  where 
she  directs  her  eyes.     See  text.     [Adapted  from  J.    Tiffin,  Indiistria]  psychology  (2nd  ed.),  1947,  p.  312.] 

469 


470 


Efficiency 


Motion  Study 

In  modern  industry  the  development  of 
efficient  working  methods  and  procedures  is 
more  often  the  concern  of  engineers  than 
of  psychologists.  The  reason  is  in  part  his- 
torical; engineers  first  drew  the  attention 
of  management  to  the  potentialities  of 
methods  research.  Important,  too,  is  the 
fact  that  the  working  out  of  new  methods 
usually  invohes  the  redesign  of  machinery 
and  equipment,  work  for  which  the  en- 
gineer is  specifically  trained.  This  devel- 
opment within  the  field  of  engineering  is 
commonly  known  as  motion  study  or  meth- 
ods engineering. 

The  first  step  in  the  process  of  working 
out  new  methods  is  to  make  a  careful  study 
of  present  methods  of  doing  a  job.  Often 
motion  pictures  are  made,  each  phase  of 
the  work  being  carefidly  timed,  and  these 
data  are  then  studied  in  order  to  determine 
whether  time  or  effort  is  being  wasted  at 
any  particular  point.  In  recommending 
changes  the  motion  analyst  is  guided  by  a 
set  of  general  rules  relating  to  the  proper 
use  of  the  body,  the  arrangement  of  work- 
ing materials  and  the  design  of  tools  and 
equipment,  most  of  which  seem  to  be  very 
sensible.  One  rule  states,  for  example,  that 
Avherever  possible  the  hands  should  be  re- 
lieved of  holding  opeiations  by  the  intro- 
duction of  mechanical  devices  so  that  the 
hands  can  be  used  instead  for  more  com- 
plex operations  which  cannot  easily  be  per- 
formed mechanically.  Another  rule  states 
that  tools,  materials  and  controls  should 
have  definite  fixed  stations  so  that  the 
worker  will  not  have  to  search  for  them 
each  time  they  are  required.  Still  another 
rule  suggests  that  wherever  possible  the 
two  arms  shoidd  be  used  simultaneously 
and  symmetrically. 

To  illustrate  the  changes  which  result 


from  the  application  of  rules  of  this  sort, 
we  shall  consider  the  modification  of  one 
routine  industrial  job.  The  task  of  the 
worker  was  to  coat  the  ends  of  small  blocks 
with  solder  so  that  wires  could  be  attached 
to  them  later  on  in  the  manufacturing 
process.  Originally  the  job  was  done  ac- 
cording to  the  diagiam  in  Fig.  22SA.  The 
left  hand  selected  a  block  from  the  supply 
pan  and  passed  it  to  the  right  hand.  Then 
the  left  hand  remained  idle  while  the 
right  hand  dipped  the  block  first  into  the 
fiux  pot  and  then  into  the  solder  pot, 
knocked  it  against  the  knock-off  plate  to 
remove  the  excess  solder,  and  dropped  the 
block  into  the  box  of  completed  pieces. 
Figure  2235  shows  a  diagram  of  the  new 
method.  Tliere  are  two  supply  pans,  two 
knock-off  plates,  and  one  pan  for  finished 
stock.  Each  cycle  of  movement  now  results 
in  two  finished  pieces,  the  two  hands  work- 
ing symmetrically  and  simultaneously. 

Time  Study 

When  the  new  method  has  been  devised, 
some  estimate  of  its  advantage  over  the 
old  method  must  be  obtained.  For  this 
purpose,  a  technique  known  as  ti7ne  study 
is  used,  a  method  of  establishing  standards 
of  performance  for  any  given  job.  The 
residt  of  a  time  study  is  a  standard  time 
which  is  used  for  determining  piece  rates 
of  pay,  working  out  schedules,  estimating 
costs  and  the  like,  as  well  as  for  evaluating 
the  residts  of  a  motion  study.  Standard 
time  is  defined  as  the  time  required  for  the 
job  by  a  person  of  'average'  skill  working 
with  'average'  effort  under  'average'  con- 
ditions. 

One  widely  used  method  for  determining 
this  time  value  is  the  following.  A  single 
worker,  preferably  one  who  is  above  aver- 
age, is  selected  for  study.  His  perform- 
ance  is   timed  by   the   engineer,   who   also 


Motion  and  Time  Study 


471 


makes  a  rating  of  liis  skill  and  cdoi  I  as  well 
as  of  the  adequacy  of  working  conditions. 
Tlie  measured  time  is  then  modified  in  the 
light  of  these  ratings  in  order  to  obtain 
the  standard  time.  For  example,  the  meas- 
ured time  is  increased  if  the  worker  is 
superior  in  skill  to  the  average  worker  and 
this  increase  is  in  proportion  to  his  rated 


(liture,  ruled  out.  I  he  method  is  based 
upon  a  complex  series  of  subjective  judg- 
ments and  the  results  which  it  gives  can  be 
only  as  accurate  as  these  judgments. 

Evaluation  of  Motion  and  Time  Study 

There  is  little  doubt  that  many  of  the 
principles  upon   which   methcjds  engineer- 


Solder 

Knock-off 

pot 

, 

. 

\ 

Flux  pot 

\ 

_^^ 

^^ 

\ 

Finished  stock 


.    Solder 
S"    pot 


-Flux  pot 


Supply  pan  Finished  stock 

A.  Original  Method 


Supply  pan  Supply  pan 

B.  New  Method 


FIGURE  223.      TWO  METHODS  OF  DOING  A  SIMPLE  REPETITIVE  JOB 
[Afler  Mogensen,  Common  Sense  Applied  to  Motion  and  Time  Study,  1932,  p.  58.  McGraw-Hill  Co.] 


superiority.  If  the  worker  is  thought  to 
be  expending  more  than  average  effort,  a 
certain  amount  is  added  to  the  measured 
time;  if  he  is  thought  to  be  expending  less 
than  average  effort,  a  certain  amount  is 
subtracted.  Other  amounts  are  added  or 
subtracted  depending  upon  how  adequate 
the  rater  considers  the  conditions  of  work 
to  be. 

The  final  time  value  which  is  arrived  at 
by  the  engineer  is  thus  in  one  sense  a  per- 
formance measure  of  efficiency.  It  is  an 
estimate  of  the  relation  between  method 
of  work  and  output,  with  the  influence  of 
all  other  variables,  including  effort  expen- 


ing  is  based  are  fundamentally  sound  and 
that  their  application  has  led  to  consider- 
able improvement  in  working  efficiency. 
In  any  given  instance,  liowe\er,  it  is  hard 
to  say  just  how  much  improvement,  if  any 
at  all,  has  been  made,  since  standard  times 
are  derived  from  subjecti\'e  judgments  and 
no  attempts  are  made  to  check  them  against 
objective  measures  of  the  cost  of  work. 
At  present,  motion  study  should  not  be 
used  as  a  basis  for  cutting  piece  rates  or 
speeding  up  production  belts  if  the  evi- 
dence for  improvement  is  based  only  on 
standard  times. 

One  major  criticism  of  time  and  motion 


472 


Efficiency 


study,  -which  is  really  a  criiicisin  of  an  im- 
portant trend  in  modern  industry,  has  been 
that  it  results  in  the  breaking  up  of  com- 
plex jobs  into  simpler  ones.  This  process 
of  simplification,  so  the  argument  runs,  de- 
prives the  worker  of  the  opportunity  to 
exercise  judgment  and  initiative  and  con- 
sequently leads  to  boredom,  loss  of  interest 
and  discontent.  This  criticism  must  be 
given  carefid  consideration  because  job 
satisfaction  is  extremely  important  for  the 
■well-being  of  the  worker  as  well  as  to  man- 
agement for  -^vhom  it  may  have  a  direct 
economic  import. 

It  is  certainly  true  that  most  people  find 
it  extremely  boring  to  perform  a  meaning- 
less repetitive  task  for  more  than  a  short 
period  of  time.  They  welcome  any  pos- 
sibility for  variation  which  presents  itself. 
On  the  other  hand,  the  more  routine  the 
activity,  the  less  attention  it  requires,  and 
the  more  free  is  the  worker  to  engage  in 
conversation  or  to  listen  to  music.  It  is  also 
clear  that  the  nature  of  the  job  activity  is 
by  no  means  the  only  factor  responsible  for 
the  de\elopment  of  monotony  in  industry. 
The  emotional  problems  of  the  worker,  his 
attitude  toward  the  company,  the  super- 
visor, his  fellow  workers,  and  his  concep- 
tion of  the  importance  of  his  job— these 
factors  and  many  others  are  related  to  re- 
ports of  boredom.  It  is  safe  to  conclude 
that  mass  production  methods  do  not  in- 
evitably produce  discontent. 

THE     WORKING     ENVIRONMENT 

There  ha\e  been  numerous  in\estigations 
of  the  relation  between  the  efficiency  of 
work  and  certain  important  environmental 
variables,  such  as  atmospheric  conditions, 
illumination  and  noise.  We  may  now  re- 
view the  current  status  of  research  with  re- 
spect to  these  factors. 


Atmospheric  Conditions 

Atmospheric  conditions— the  chemical 
composition  of  the  air,  barometric  pressure, 
air  temperature,  humidity  and  so  forth— 
are  principally  related  to  hinnan  efficiency 
only  insofar  as  they  affect  two  vital  physio- 
logical functions— respiration  and  the  main- 
tenance of  body  temperature. 

Respiration 

In  order  to  live  and  function  normally, 
man  must  be  provided  with  a  sufficient  sup- 
ply of  oxygen.  Under  ordinary  conditions 
of  life  on  earth,  however,  maintaining  an 
adequate  supply  of  oxygen  is  rarely  a  diffi- 
cult problem.  Atmospheric  air,  the  chemi- 
cal composition  of  which  remains  remark- 
ably constant,  contains  about  20  or  21  per 
cent  of  oxygen.  Actually  air  which  con- 
tained only  14  or  15  per  cent  of  oxygen 
would  be  perfectly  suitable  for  human  use. 
Of  course,  if  a  man  is  enclosed  in  a  space 
which  is  sealed  off  from  the  rest  of  the  at- 
mosphere, sooner  or  later  his  supply  of  oxy- 
gen will  fall  below  the  level  necessary 
for  his  normal  functioning,  which  is  about 
14  per  cent.  But  even  in  the  most  poorlv 
ventilated  rooms  which  contain  large  num- 
bers of  people  the  oxygen  content  of  the  air 
is  well  above  that  level.  The  feeling  of 
suffocation  and  the  other  ill  effects  that  we 
experience  in  such  places  may  be  attributed, 
not  to  inadequate  oxygen  supply,  but  to 
the  high  temperature  and  humidity.  This 
interpretation  is  supported  by  the  restdts 
of  an  experiment  in  which  it  was  found 
that  people  enclosed  in  a  small  sealed  room 
were  not  relieved  when  they  were  permitted 
to  breathe  through  a  tube  'fresh  air'  from 
the  outside,  whereas  other  people,  stationed 
outside  the  room  but  breathing  the  air  of 
the  room  by  means  of  tubes,  did  not  suffer 
any  discomfort. 


The  Working  Environmeni 


473 


Under  special  conditions,  however,  oxy- 
gen deficiency— flnoxk^  as  it  is  called— does 
become  a  problem  of  special  interest.  The 
develoj^ment  of  modern  aviation  has  stimu- 
lated a  great  deal  of  research  on  the  rela- 
tion between  anoxia  and  efficiency.  At  high 
altitudes  the  percentage  of  oxygen  in  the 
air  remains  constant,  but  the  decreased 
barometric  pressure  results  in  a  decreased 
passage  of  oxygen  from  the  lungs  to  the 
blood.  Breathing  atmospheric  air  at  an 
altitude  of  10,000  feet  is  about  the  ecjuiva- 
lent  of  breathing  air  which  contains  only 
14  per  cent  of  oxygen  at  sea  level.  Above 
this  altitude,  unless  steps  are  taken  to  in- 
crease the  oxygen  supply,  the  first  signs  of 
anoxia  will  appear.  One  solution  is  to 
increase  the  percentage  of  oxygen  in  the 
air  which  the  pilot  inspires  by  the  use  of 
an  oxygen  mask,  but  this  solution  is  satis- 
factory only  at  altitudes  below  about  40,000 
feet.  Above  this  level,  barometric  pressure 
is  so  low  that,  even  if  pure  oxygen  is 
breathed,  there  will  be  an  insufficient  pas- 
sage of  oxygen  into  the  blood  stream.  Pro- 
longed flying  at  very  high  altitudes  is  pos- 
sible only  in  sealed  cabins  in  which  normal 
air  pressure  is  maintained. 

During  the  Second  World  War  many  in- 
vestigations of  the  effects  of  anoxia  were 
conducted.  It  was  for  the  most  part  un- 
necessary to  risk  studying  the  phenomenon 
under  actual  flight'conditions,  because  high 
altitudes  could  be  simulated  by  the  use  of 
controlled-pressure  chambers  in  ground 
laboratories.  One  of  the  earliest  symptoms 
of  anoxia  to  appear,  usually  at  about  the 
pressure  equivalent  to  10,000  feet  altitude, 
is  an  unmistakable  euphoria— a.  pronounced 
experience  of  well-being  and  self-confidence 
similar  to  that  often  produced  by  small 
amounts  of  alcohol.  As  altitude— real  or 
simulated,  it  makes  no  difference— increases, 
huthcr   marked   emotional   chanees   occur. 


The  individual  may  be  intensely  happy, 
angry  or  depressed,  and  he  has  usually  be- 
come quite  delirious  before  he  finally  loses 
consciousness  at  about  20,000  feet.  Psycho- 
logical tests  administered  at  various  alti- 
tudes show  many  other  pronounced  func- 
tional changes.  Muscular  coordination  be- 
comes very  poor,  reaction  time  is  length- 
ened, visual  and  auditory  acuity  are  re- 
duced, range  of  attention  becomes  re- 
stricted, and  intellectual  capacities  are  im- 
paired. 

Temperature  Regulation 

Under  ordinary  circumstances  atmos- 
pheric conditions  arc  important  because 
they  affect  the  maintenance  of  body  tem- 
perature. The  temperature  of  the  body 
varies  about  a  mean  of  approximately 
98.6°  F,  and  the  body  is  pro\ided  with 
mechanisms  which  maintain  this  level  of 
temperature  in  the  face  of  wide  variations 
in  atmospheric  conditions.  If  the  environ- 
ment cools  the  body,  the  oxidati\e  proc- 
esses of  the  body  will  be  speeded  up  to 
produce  more  heat.  There  is  a  further  con- 
trol of  body  temperature  which  can  operate 
without  changing  bodily  heat  production. 
•If  the  air  is  cool,  the  skin  cools  down,  con- 
stricting the  blood  vessels  and  thus  cooling 
the  skin  even  more.  Less  heat  is  trans- 
ported from  the  inside  of  the  body  to  its 
surface,  and  the  cool  skin  radiates  less  heat 
to  the  surrounding  air  than  it  would  had 
the  skin  remained  ■warm  Avhile  die  air  ^vas 
cool.  On  the  other  hand,  ^vhen  the  sur- 
roundings are  warm  die  blood  vessels  of 
the  skin  dilate,  and  more  heat  is  trans- 
ferred to  the  surface  of  the  body  for  radia- 
tion to  the  air.  In  addition,  s'weating  be- 
gins, and  its  evaporation  takes  additional 
heat  from  the  skin  surface. 

The  ease  ^vith  -which  optimal  bodv  teni- 
peratine  can  be  maintained  is  a  function. 


474 


Efficiency 


not  of  one,  but  of  a  number  of  environ- 
mental variables.  Air  temperature  is  im- 
portant because,  depending  on  the  differ- 
ence between  air  temperature  and  skin 
temperature,  the  air  conducts  heat  away 
from  or  to  the  body.  But  humidity,  rate 
of  air  movement  and  the  temperature  of 
surrounding    objects    also    are    important 


90 Ill M    I   I   I   I  I  V  I  I    I  I 

^    s.    ^   ^    ,'^    z     ^    s    ^ 


v> 


oo 


FIGURE  224.      SEASONAL  VARIATION   IN   PRODUCTION 
AS  AFFECTED  BY  VENTILATION 

[.After  H.  M.  Vernon,  Industrial  fatigue  and  effi- 
ciency', Dutton,  1921,  p.  242.] 

variables.  Humidity  affects  the  rate  of 
evaporation  of  sweat  from  the  skin;  air 
movement  serves  to  carry  warm  moist  air 
away  from  the  skin  and  to  replace  it  with 
cooler,  drier  air;  and  the  temperature  of 
surrounding  objects  is  important  because 
much  heat  exchange  between  organism  and 
environment  occurs  as  radiation.  This  ex- 
change of  radiant  energy  is  largely  inde- 
pendent of  the  air  temperature;  we  can  be 
cool  when  the  air  is  hot  provided  we  are 
surrounded  by  cool  walls.  Any  study  of 
the  efficiency  of  atmospheric  conditions 
must  therefore  take  all  these  variables  into 
account.  At  a  given  air  temperature  a  per- 
son may  feel  very  wann,  very  cold  or  quite 
comfortable    depending    on    whether    his 


body  is  losing  too  much  or  not  enough  heat 
to  keep  its  own  temperature  close  to  normal. 

The  principal  method  of  experimental 
study  of  the  effects  of  these  environmental 
factors  has  been  the  speed  test  rather  than 
the  complete  analysis  of  efficiency.  Tem- 
perature has  a  marked  influence  upon 
amount  of  muscular  work  as  measured  by 
speed  of  performance.  In  one  experiment 
the  amount  of  work  done  was  40  per  cent 
less  at  86°  F  and  80  per  cent  relative  hu- 
midity than  it  was  at  68°  F  and  50  per  cent 
relative  humidity.  The  first  condition  was 
experienced  as  uncomfortably  warm,  and 
the  second  as  comfortable.  It  has  also 
been  found  that  factory  production  is  much 
lower  in  the  summer  than  in  the  winter, 
and  that  this  variation  can  be  partially 
controlled  by  improved  methods  of  venti- 
lation (Fig.  224). 

For  tasks  which  require  little  muscular 
exertion,  however,  speed  tests  do  not  show 
any  consistent  effect  of  temperature  varia- 
tion over  a  wide  range.    (See  Table  XXVI.) 

T.ABLE  XXVI 

Effect  of  Ventilation  on  Mental  Work. 
[Adapted  from   Ventilation,  Report  of  the  New  York 
State  Commission  on  Ventilation,  Dutton,  1923,  p.  102.| 

RELATIVE  PERFORMANCE 

Uncomfortably 

Comjortable  Warm 

(68°  F;  50  per  (86°  F;  80  per 

cent  relative  cent  relative 

humidity;  good  humidity;  poor 

Mental  Test           air  circulation)  air  circulation) 
Number  cancellation 

Test  1                                  100  93.6 

Test  2                                 100  99.8 

.Addition                                 100  106.1 

Multiplication                       100  102.4 

Typewriting                           100  101.1 

Although  this  result  is  important  in  itself, 
it  does  not  necessarily  mean  that  efficiency 
is  also   unaffected.     Discomfort  and  disin- 


Temperafure  and  Illumination 


475 


clination  lo  work  arc  Lluinsclvcs  iiidic  atioiis 
that  efficiency  is  down,  although  we  cannot 
be  sure  that  the  temperature  which  we 
prefer  is  necessarily  the  most  advantageous 
from  the  point  of  view  of  health  and  well- 
being.  The  chief  difficulty  here  lies  in  the 
influence  of  acclimatization  and  adaptation. 
In  sinnmer  warmer  temperatures  are  pre- 
ferred than  in  winter,  and,  in  general,  the 
(emperatures  to  which  an  individual  has 
become  accustomed  determine  to  a  large 
extent  what  his  preferences  will  be. 

Illumination 

The  light  which  is  available  for  visual 
work  is  a  fimction  of  the  light  source  and 
of  the  reflecting  surfaces  in  the  environ- 
ment of  the  work.  It  can  be  described  in 
terms  of  three  important  variables— amount, 
spectral  composition  and  distribution.  In 
practice  a  change  in  one  of  these  aspects 
of  lighting  often  produces  a  change  in  one 
or  both  of  the  others,  but  theoretically  at 
least  each  aspect  can  be  considered  inde- 
pendently. Each  of  the  three  variables 
has  been  shown  to  be  related  in  an  im- 
portant way  to  the  efficiency  of  visual  work. 

Amount  of  illumination.  Amount  of  il- 
lumination has  for  the  most  part  been 
studied  in  terms  of  performance.  In  a  wide 
variety  of  industrial  and  laboratory  situa- 
tions it  has  been  possible  to  demonstrate 
increases  in  output  owing  to  increases  in 
intensity  of  light.  Table  XXVII  shows 
representative  examples  of  such  changes 
for  a  number  of  factory  jobs.  Further  in- 
vestigation indicates,  however,  that  output 
does  not  continue  to  rise  indefinitely  as 
brightness  is  progressively  increased.  For 
every  task  thus  far  sttidied  an  intensity 
level  is  found— often  called  the  'critical' 
level— beyond  which  there  is  no  further  im- 
provement in  performance.  The  critical 
level  varies  with  the  nature  of  the   task. 


TABLE  XXVII 

Effect  of  Increased  Illumination  ow  I.vdustrjal 

Production 
[After  L.  T.  Troland,  in  M.  A.  Tinker,  Illuinination 
standards    for   effective   and   comfortable   vision, 
/.  consu/t.  PiychoL,  1939,  3,  17.) 

Initial 

Level  New  Level  Increase  in 

{foot-  {foot-  Production 

Factory                candles)  candles)  {per  cent) 

Electrical                      3.8  11.4  8.5 

Piston  ring                   1.2  6.5  13.0 

Piston  ring                   1.2  9.0  17.9 

Piston  ring                   1.2  14.0  25.8 

Roller  bearing             5.0  6.0  4.0 

Roller  bearing             5.0  13.0  8.0 

Roller  bearing             5.0  20.0  12.5 

For  speed  of  reading  easy  passages  printed 
in  good-sized  type  it  is  about  3  or  4  fooi- 
candles,  which  is  relatively  low  illumina- 
tion. (Three  foot-candles  is  the  amount  of 
light  which  is  thrown  on  a  surface  52  inches 
away  by  a  50-watt  bulb  in  an  ordinary 
bridge-lamp  shade.)  For  general  study  15 
foot-candles  is  about  the  critical  level;  for 
speed  of  threading  needles,  30  foot-candles; 
and  for  certain  tests  of  visual  acuit)'  the 
critical  level  may  be  above  100  foot-candles, 
provided  the  illimiination  is  fairly  uniform 
throughout  the  visual  field. 

The  eff^ect  of  ilhimination  level  upon 
performance  is,  as  usual,  better  known 
than  its  effect  upon  efficiency.  Increases 
in  industrial  production  resulting  from 
changed  conditions  of  illumination  may 
perhaps  be  attributed  to  better  morale  as 
often  as  to  greater  efficiency.  On  the  ^\hole, 
however,  the  opinion  has  more  often  been 
given  that  performance  indices  point  to 
optimal  illuminations  which  are  too  low 
rather  than  too  high.  This  stispicion  arises 
from  the  fact  that,  since  critical  levels  de- 
rived from  speed  tests  are  often  only  a  small 
fraction  of  daylight  levels,  there  is  the  pos- 
sibility that  ease  of  seeing  may  continue 


476 


Efficiency 


to  increase  with  increasing  illumination  far 
beyond  the  point  at  which  there  are  no 
further  gains  in  speed  of  work.  There  is 
some  evidence  for  this  point  of  view  from 
studies  of  muscular  tension,  at  least  in  the 
case  of  reading.  Although  speed  of  reading 
does  not  increase  as  intensity  is  raised  be- 


Intensity  in 
foot-candles 


''X    0-5 
•I--5-.0         . 

10-15 
''^' '  15-20 

iiliL 

--jl'*^  20-30 

liii 

-1-    30-40 

I 
40  and  over 


Percentage  of  subjects 

preferring  intensity 

shown  at  left 

"'20.8 


14.0 


FIGURE   225.      DISTRIBUTION   OF    ILLUMINATION 
LEVELS  PREFERRED  FOR  READING 

[Adapted  from  C.  E.  Ferree  and.  G.  Rand,  Good 
Working  Conditions  for  the  Eyes,  Personnel  Jr., 
1936,  15,  330-340  by  F.  K.  Berrien  in  Practical 
Psychology,   Macmillan,   1944.] 

yond  3  or  4  foot-candles,  tension  developed 
in  the  course  of  reading  appears  to  be  re- 
duced significantly  by  increases  in  intensity 
up  to  10  or  20  foot-candles. 

Another  approach  to  the  problem  of  best 
illumination  has  been  to  determine  what 
intensities  people  prefer  for  work  of  vari- 
ous sorts.  In  most  of  these  experiments 
the  subject  is  allowed  to  select  any  inten- 
sity within  a  wide  range  by  means  of  a  con- 
trol knob.  Distributions  of  choices  ob- 
tained under  such  conditions  show  a  great 
deal  of  variability,  probably  reflecting  dif- 
ferences in  personal  experience  that  need 
have   no  relation   to   efficiency   (Fig.   225). 


Furthermore,  it  can  be  shown  that  the  aver- 
age level  of  illumination  selected  by  a  group 
of  subjects  is  to  a  large  extent  determined 
by  the  level  to  which  they  are  light-adapted 
at  the  time  they  made  the  choice.  Thus 
there  is  danger  in  recommending  illumina- 
tion for  factories,  offices  or  schoolrooms  on 
the  basis  of  preferences. 

Certain  investigators  have  issued  recom- 
mendations for  lighting  in  schools,  fac- 
tories, offices  and  homes  which  are  no  bet- 
ter than  good  guesses.  Some  of  these  recom- 
mendations have  been  high,  for  the  'ex- 
perts' assimie  that  light  is  cheap  in  com- 
parison with  the  value  of  good  eyesight  and 
that  we  can  never  have  too  much  light. 
One  investigator  has  gone  so  far  as  to  sug- 
gest the  use  of  100  or  more  foot-candles 
for  ordinary  reading.  This  extravagant 
approach  to  the  problem  of  lighting  may 
be  dangerous.  For  one  thing,  although 
the  visual  mechanism  can  adjust  to  a  wide 
variety  of  illumination  levels,  anybody  who 
has  tried  to  read  by  the  light  of  the  summer 
sun  will  be  able  to  conceive  of  the  possibil- 
ity of  too  much  light  for  a  given  purpose. 
Then  again,  these  recommendations  assume 
that  special  precautions  have  been  taken 
to  prevent  glare  and  bad  distribution, 
whereas  the  layman,  attempting  to  follow 
instructions,  may  easily  overlook  these  pre- 
cautions and  thus  make  reading  more  dif- 
ficult than  with  less  light. 

Distribution  of  light.  It  is  generally 
agreed  that  the  distribution  of  light  in  the 
visual  field  should  be  as  uniform  as  possible 
—that  areas  of  relatively  high  or  relatively 
low  brightness  should  be  avoided.  Uneven 
illumination  produces  glare;  the  transmit- 
ting media  within  and  without  the  eye 
(fog,  dirty  windshields,  cloudy  media  within 
the  eye)  diffuse  the  light  and  blur  the 
retinal  images.  Glare  spots  are  especially 
harmful  because  they  produce  conflicts  in 


Illumination  and  Noise 


477 


the  mechanisms  ol  (ixalion  and  atcoinnio- 
dation.  There  is  a  reflex  tendency  to  look 
toward  points  of  high  brightness  which  oc- 
cur in  peripheral  vision,  and  this  tendency 
must  be  inliibited  if  the  visual  task  is  to  be 
uninterrupted.    Such  a  competition  of  reac- 


Kind  of  illumination 


Percentage  of  loss  in 
ability  to  maintain  clear 
2hr[~35%      vision  after  number  of 


hours  stated 


3hr[l5% 


Daylight 


;   yy  \2hrl      110% 


Indirect 


FIGURE    226.       DECREMENTS    IN    ABILITY    TO    MAIN- 
TAIN    CLEAR     VISION     AFTER     SEVERAL     HOURS     OF 
READING      UNDER     DIFFERENT     TYPES      OF      ILLUMI- 
NATION 

[After  C.  E.  Ferree  and  G.  Rand,  from  F.  K.  Ber- 
rien, Practical  psychology,  Macmillan,  1944,  p.  251.1 

tion  systenTS  produces  muscular  tension, 
discomfort  and  fatigue,  although  it  may 
not  affect  performance  measures  such  as 
speed-of-reading  tests. 

Unshaded  or  only  partially  shaded  light 
sources  are  probably  the  commonest  cause 
of  glare,  and  the  superiority  of  indirect 
lighting  is  attributable  to  the  fact  that  the 
light  sources  are  never  directly  visible. 
Figure  226  shows  the  relative  adequacy  of 
these  different  types  of  lighting  in  terms  of 


ciec.remcMts  in  ability  to  maintain  clear 
vision  alter  .several  hours  of  work  under 
the  various  conditions. 

Spectral  composition.  Since  modern  il- 
luminating engineers  have  developed  illu- 
ininants  of  many  different  spectral  compo- 
sitions, the  relation  between  this  variable 
and  visual  efficiency  presents  a  problem. 
Certain  general  relationships  have  already 
been  established.  When  lights  of  various 
colors  are  compared,  yellow  is  found  to 
make  for  the  greatest  initial  acuity  and  the 
least  impairment  of  clear  vision  after  sev- 
eral hours  of  reading.  This  result  still 
holds  even  after  the  intensities  are  ad- 
justed for  the  differential  sensitivity  of  the 
eye;  that  is  to  say,  even  if  the  blue  light 
is  made  as  bright  as  the  yellow,  the  yellow 
is  still  inore  satisfactory. 

Because  of  the  phenomenon  of  chromatic 
aberration  (unequal  refraction  of  lights  of 
different  wave  lengths),  it  might  be  ex- 
pected that  monochromatic  sources,  such 
as  the  sodium  vapor  lamp,  would  be  supe- 
rior to  more  complex  sources,  such  as  ordi- 
nary tungsten  lamps;  but  in  practice  the 
differences  in  performance  have  not  been 
large,  and  in  some  studies  tliey  have  been 
in  favor  of  the  tungsten.  Among  complex 
sources,  those  whose  spectral  composition 
approximates  that  of  daylight  seem  to  be 
superior  to  the  yellower  tungsten  illumi- 
nants. 

Noise 

The  principal  experimental  studies  of 
the  effect  of  noise  upon  efficiency  have  been 
Iaboratoi7  investigations  of  relatively  short 
duration.  Industrial  studies  have  con- 
sistently sho-^vn  inaeases  in  production 
^vhen  noise  is  reduced.  Performance  in 
speed  tests  given  under  laboratoiy  condi- 
tions, hoAv'e\er,  has  not  been  found  to  be 
very  markedly  affected  by  noise.     The  in- 


478 


Efficiency 


troduction  of  noise  often  produces  short 
term  decrements,  but  performance  soon  re- 
turns to  approximately  the  original  level, 
sometimes  a  little  lower  and  sometimes 
even  somewhat  higher.  Despite  this  fact 
there  is  some  evidence  to  show  that  heart 
rate,  muscular  tension  and  oxygen  consump- 
tion are  all  somewhat  higher  during  the 
noise,  indicating  increased  effort.  As  we 
have  already  noted,  performance  may  even 
be  increased  by  noise  because  it  spurs  ef- 
fort. Airplane  noise  tires  pilots  but  does 
not  seem  to  reduce  the  quality  of  their 
work.  Most  persons  seem  to  become  rap- 
idly accustomed  to  noise,  and  the  effects 
of  noise  both  upon  bodily  tension  and  upon 
skilled  performance  usually  disappear  in 
time. 

REST    AND    SLEEP 

What  is  the  best  distribution  of  work 
and  rest  from  the  point  of  view  of  overall 
efficiency  in  any  given  activity?  Study  of 
this  problem  has  been  carried  out  both  in 
industrial  and  in  laboratory  settings,  and 
in  each  case  output  indices  have  been  relied 
upon  almost  exclusively. 

Hours  of  Work 

It  is  fairly  easy  to  demonstrate  that  effi- 
ciency is  a  function  of  the  rate  of  work. 
Studies  of  speed  of  walking  indicate,  for 
example,  that  it  is  more  efficient  in  terms 
of  oxygen  consumption  to  walk  at  the  rate 
of  four  miles  per  hour  than  at  three  or 
five  miles  per  hour.  Because  of  the  rela- 
tion of  efficiency  to  rate  of  work,  the  length 
of  the  working  day  becomes  an  important 
problem.  If  a  worker  is  expected  to  pro- 
duce a  certain  amount  on  a  given  day,  over 
how  many  hours  shall  the  work  be  dis- 
tributed (at  what  rate  shall  it  be  done)  so 
that  the  total  cost  will  be  minimal?     Con- 


versely, if  the.  worker  comes  prepared  to 
expend  a  given  amount  of  effort,  over  how 
many  hours  shall  this  effort  be  distributed 
so  that  the  total  achievement  will  be  maxi- 
mal? 

The  earliest  systematic  studies  of  the 
length  of  the  working  day  were  conducted 
during  the  First  World  War.  In  that  pe- 
riod of  manpower  shortage  and  high-pro- 
duction requirements,  hours  of  work  were 
very  long,  often  seventy  or  more  per  week, 
and  it  soon  became  apparent  that  total 
production  could  actually  be  increased  by 
reducing  working  hours.  In  other  words, 
the  increases  in  rate  of  production  which 
resulted  more  than  compensated  for  the 
decrease  in  number  of  hours  worked  (Fig. 
227).  Financial  incentives  were  not  re- 
sponsible for  the  results,  which  held  for  the 
workers  paid  by  the  hour  as  well  as  for 
the  piece  workers.  As  the  investigators 
continued  to  reduce  the  number  of  hours 
worked,  however,  production  eventually 
fell  off  because  rate  of  work  did  not  in- 
crease so  rapidly  as  before.  The  optimal 
length  of  the  woiking  day  or  week  varied 
considerably  from  job  to  job. 

Although  interest  in  these  studies  was 
largely  centered  in  production,  there  was 
some  reason  for  believing  that  the  differ- 
ences in  production  which  were  foimd  rc])- 
resented  real  differences  in  efficiency,  ll 
seemed  that  the  workers  came  to  their 
jobs  prepared  to  expend  a  fixed  amount  of 
effort  irrespective  of  the  length  of  the  work 
spell.  The  gradual  manner  in  which  in- 
creases in  production  appeared  after  a  re- 
duction in  working  hours— often  the  full 
effects  of  the  change  were  not  realized  for 
several  months— suggested  that  the  workers 
were  learning  to  redistribute  the  amount  of 
effort  which  they  were  ready  to  expend. 


Resf  and  Sleep 


479 


Aug.  15 

Oct.  24 

Jan.  2 

Mar.  12 

May  21 

July  30 

Oct.  7 

Dec.  16 

Feb.  24 

Mays 

1915 

1915 

1916 

1916 

1916 

1916 

1916 

1916 

1917 

1917 

FIGURE  227.      RATE  OF  PRODUCTION  IN  RELATION  TO  LENGTH  OF  WORKING  WEEK 

Shows  how  increase  of  production  during  pressure  of  war  emergency  was  secured  by  decreasing  working 
hours  per  week.  "Nominal  hours"  are  those  present  in  the  plant.  "Actual  hours"  represent  actual 
working  time.  The  upper  curve  (scale  reversed)  shows  decrease  in  working  hours  that  accompanied  the 
increase  in  output  shown  on  the  lower  curve.  [From  H.  M.  V6rnon,  Industrial  fatigue  and  efficiency,  But- 
ton, 1921,  p.  39.] 


Rest  Periods 

The  efficiency  of  prolonged  work  can  be 
notably  increased  by  the  introduction  of 
periodic  rest  pauses  which  permit  a  certain 
amount  of  recovery  from  fatigue.  Indus- 
trial observations  show  clearly  that,  when 
there  are  no  regularly  scheduled  rest  pauses, 
workers  manage  to  find  many  reasons  for 
stopping  work  in  the  course  of  the  work- 
ing day.  These  'unofficiar  rests  are  less 
efficient  than  regularly  scheduled  ones  be- 
cause they  may  not  come  at  the  proper 
times  and  because  they  are  usually  furtive 
and  incomplete. 


The  efi:ectiveness  of  regularly  scheduled 
rest  periods  has  been  demonstrated  in  terms 
of  production.  It  has  also  been  shown  that 
rest  intervals  should  be  brief  and  fiequent, 
although  the  optimal  schedule  varies  from 
job  to  job.  Frequency  is  important  because 
of  the  relation  between  duration  of  ■svork 
and  the  development  of  fatigue.  Fatigue 
develops  slowly  at  first  and  then  more  and 
more  rapidly;  if  one  unit  of  work  produces 
one  unit  of  fatigue,  two  successive  units  of 
work  may  produce  three  or  e\  en  four  units 
of  fatigue.  In  one  experiment  it  was 
shown,  for  example,  that  it  takes  four  times 
as  lonff  to  recover  from  the  effects  of  lift- 


480 


Efficiency 


ing  a  weight  thirt)  times  as  it  does  to  re- 
cover from  the  effects  of  lifting  it  fifteen 
times. 

In  addition,  short  rest  periods  are  more 
efficient  than  longer  ones  because  recovery 
from  fatigue  is  also  rapid  at  first  and  then 
more  and  more  gradual.  In  another  ex- 
periment on  weight  lifting,  it  was  found 
that  there  was  72  per  cent  recovery  5  min- 
utes after  a  period  of  work,  75  per  cent 
after  10  minutes  and  only  77  per  cent  after 
twenty  minutes. 

The  so-called  warming-up  phenomenon 
also  suggests  that  rest  periods  be  kept  fairly 
short.  At  the  beginning  of  the  work  spell 
a  certain  amount  of  time  usually  elapses 
before  a  stable  level  of  production  is 
reached.  During  this  time  the  worker  is 
giadually  developing  the  proper  attitudes 
and  muscular  sets.  If  rest  pauses  are  too 
long  this  process  of  warming-up  or  getting 
into  the  swing  of  activity  must  be  repeated 
all  over  again. 

It  should  be  noted,  however,  that  in- 
creases in  production  after  the  introduction 
of  regularly  scheduled  rest  periods  may 
often  represent  changes  in  motivation 
rather  than  changes  in  efficiency.  Al- 
though studies  of  oxygen  consumption 
have  demonstrated  genuine  increases  in 
efficiency  under  such  conditions,  other  evi- 
dence indicates  that  production  increments 
are  to  some  extent  a  function  of  improved 
employee  morale  and  resulting  additional 
exertion.  Only  through  a  measurement 
of  effort  expenditure  would  it  be  possible 
to  distinguish  between  the  effects  of  these 
two  variables. 

Sleep 

Since  the  average  individual  may  spend 
anywhere  from  a  quarter  to  a  third  of  his 
life  in  sleep,  it  is  a  phenomenon  of  con- 
siderable importance.    As  yet,  however,  we 


know  very  little  about  the  efficiency  of  our 
sleeping  habits;  we  cannot  tell  how  much 
sleep  a  given  individual  requires  or  under 
what  conditions  sleep  is  most  beneficial. 

Investigations  of  the  need  for  sleep  have 
been  based  largely  on  the  use  of  fatigue 
tests,  the  usual  procedure  being  to  adminis- 
ter batteries  of  physical  and  mental  tests 
before  and  after  certain  schedules  of  sleep 
and  wakefulness  and  to  compare  the  effec- 
tiveness of  these  schedules  in  terms  of  dif- 
ferences in  performance.  In  general,  how- 
ever, fatigue  tests  ha^■e  proved  to  be  very 
insensitive,  and  even  after  several  days 
^vithout  sleep  a  person's  performance  may 
be  just  as  good  as  it  was  when  he  was  rested. 
Only  those  tests  which  require  continuous 
attention  and  effort  are  much  affected  by 
loss  of  sleep.  Of  course,  the  person  who 
has  been  awake  for  a  long  period  of  time 
knows  that  he  needs  sleep  and  has  to  try 
^'ery  hard  to  keep  awake,  but  performance 
scores  give  little  indication  of  his  condi- 
tion. There  is  some  evidence  to  show, 
nevertheless,  that  j^erformance  levels  are 
maintained  under  such  conditions  only  at 
the  expense  of  additional  expenditure  of 
effort. 

EFFECTS    OF    COMMON    DRUGS 

The  widespread  use  of  alcohol,  coffee, 
tea  and  tobacco  has  given  rise  to  much 
speculation  concerning  their  effects  upon 
the  organism.  The  usual  experimental 
procedure  has  been  to  administer  batteries 
of  physical  and  mental  tests  before  and 
after  the  administration  of  various  quanti- 
ties of  the  substance  in  question  and  to 
study  the  effects  on  performance.  The  data 
of  such  experiments  must  be  interpreted 
cautiously  for  a  number  of  reasons.  For 
one  thing  the  insensitivity  of  performance 
measures,    when    effort    is    not    controlled, 


Sleep,  Alcohol  and  Tobacco 


481 


makes  it  dangerous  to  coiitlude  thai  a  given 
substance  has  no  eflect  upon  efficiency  when 
test  scores  are  unchanged.  When  test 
scores  do  change  alter  achninistration  of  a 
drug,  the  drug  ilsclf  is  not  necessarily  the 
responsible  factor.  "I'lie  change  may  have 
stemmed  from  the  subject's  expectation 
that  the  drug  would  have  some  effect- 
either  facilitating  or  detrimental— upon  his 
behavior.  For  this  reason  it  is  always 
necessary  to  arrange  the  conditions  so  that 
the  subjects  never  know  when  they  have 
taken  the  substance  in  question  or  how 
much  they  have  had.  We  should  also  bear 
in  mind  in  evaluating  available  informa- 
tion that  most  experimental  studies  deal 
only  with  the  short-term  effects  of  the  vari- 
ous drugs  and  tell  us  nothing  about  the 
consequences  of  the  continued  use  of  these 
substances  over  a  period  of  years. 

Alcohol 

Alcohol  is  not  a  stimulant  but  a  depres- 
sant. Moderate  doses  have  an  apparently 
stimulating  effect  presumably  because  the 
higher  neural  centers  are  most  easily  af- 
fected and  tlie  inhibitory  control  wliich  they 
ordinarily  exert  on  the  louver  centers  is 
impaired.  It  is  difficult  to  administer  alco- 
hol without  the  subject's  knowledge.  Its 
presence  can  be  partly  disguised  by  giving 
it  in  mixed  drinks  or  injecting  it  directly 
into  the  blood  stream,  but  the  subject  can 
usually  detect  the  presence  of  more  than 
very  small  quantities  from  its  'warming' 
effect. 

It  is  well  recognized  that  alcohol  taken 
in  fairly  large  quantities  leads  to  serious 
impairment  in  motor  and  intellectual  fimc- 
tions.  When  the  leAel  of  alcohol  in  the 
blood  stream  has  reached  about  three  or 
four  tenths  of  one  per  cent,  the  individual 
is  usually  in  a  comatose  state.    It  is  difficidt 


to  fjc  specific  about  the  consequences  of 
moderate  doses,  however,  since  people  vary 
considerably  with  respect  to  their  suscep- 
tibility to  alcohol,  their  'tolerance'  of  it. 
Experiments  nevertheless  indicate  that, 
whenever  alcohol  is  found  to  influence  fx:r- 
formance  at  all,  the  eflect  is  Cfjnsistently 
adverse. 

The  deleterious  effects  of  relatively  small 
quantities  of  alcohol  have  been  demon- 
strated fcjr  a  wide  variety  of  functicjns  in- 
cluding muscular  coordination  and  control, 
speed  of  muscular  reactions,  simple  arith- 
metic operations,  memory  and  intelligence 
test  performance.  Although  it  is  not  pos- 
sible to  rule  out  completely  the  influence 
of  suggestion  in  these  results,  the  fact  that 
these  effects  vary  in  a  consistent  manner 
with  the  amount  of  the  dose  indicates  that 
it  is  the  alcohol  in  the  blood  stream  which 
is  responsible.  It  should  be  noted  that  the 
effects  disappear  in  a  few  hours  as  the  alco- 
hol is  absorbed  and  excreted. 

This  type  of  experimentation  does  not, 
of  course,  answer  the  question  as  to  whether 
the  continued  use  of  alcohol  in  moderate 
amotmts  produces  a  permanent  impairment 
of  efficiency. 

Tobacco 

It  is  well  known  that  tobacco  contains  a 
substance  known  as  nicotine  which  has 
certain  toxic  effects  on  the  bod\.  Actu- 
ally, however,  very  little  nicotine  enters 
the  body  during  smoking  because,  as  the 
tobacco  burns,  the  nicotine  ^vhich  it  con- 
tains is  broken  do^vn  into  less  harmful 
substances. 

At  present  time  there  is  very  little  de- 
pendable evidence  concerning  die  relation 
between  the  use  of  tobacco  and  efficiencv. 
The  only  well-controlled  investigation  tliat 
has  been  reported  is  limited  to  the  {>eriod 


482 


Efficiency 


o[  an  hour  and  forty-five  minutes  directly 
after  the  smoking  of  a  single  pipeful  of 
tobacco.  The  important  feature  of  this 
experiment  is  that  the  subjects  could  not 
tell  whether  they  were  smoking  tobacco  or 
not.  The  investigator  invented  a  bogus 
pipe  through  which  the  subjects  could  draw 
warm  moist  air.  When  they  were  blind- 
folded the  subjects  could  not  distinguish 
between  the  real  pipe  and  the  control  de- 
vice since  the  odor  of  smoke  was  present 
in  the  air  from  the  experimenter's  pipe. 
The  results  of  the  experiment  showed  that 
smoking  unmistakably  increased  pulse  rate 
and  unsteadiness  of  the  hands  in  both  ex- 
perienced and  inexperienced  smokers.  For 
inexperienced  smokers  speed  of  addition 
was  decreased  slightly  by  tobacco  but  in- 
creased slightly  for  habitual  smokers.  A 
variety  of  other  motor  and  intellectual 
functions  could  not  be  shown  to  be  affected 
by  the  tobacco. 

Caffeine 

Caffeine,  which  is  found  in  various  'soft' 
drinks  as  well  as  in  coffee  and  tea,  has 
significant  stimulating  properties.  Al- 
though the  average  cup  of  coffee  does  not 
contain  enough  caffeine  to  interfere  with 
sleep,  larger  doses  may  do  so.  A  number 
of  controlled  laboratory  investigations 
demonstrate  the  facilitating  effects  of  mod- 
erate amounts  of  caffeine  on  a  variety  of 
muscular  and  simple  mental  performances, 
although  adverse  effects  upon  muscular 
steadiness  have  also  been  found.  Larger 
amounts  of  caffeine  often  reverse  these  fa- 
vorable effects.  It  has  also  been  demon- 
strated that  tolerance  for  caffeine  develops 
very  rapidly,  so  that  the  effectiveness  of  a 
given  dose  varies  inversely  with  the  amount 
that  any  given  individual  is  accustomed 
to  using. 


JOB    SATISFACTION 

In  any  discussion  of  working  efficiency 
we  must  not  fail  to  consider  the  attitude 
of  the  worker  toward  his  job.  Not  only  is 
psychological  well-being  as  important  to 
the  worker  himself  as  his  physiological 
well-being,  but  it  is  also  clear  that  the  dis- 
contented worker  expends  more  effort  for 
the  same  result  than  the  worker  who  likes 
his  job.  The  resentful,  antagonistic  em- 
ployee, who  goes  through  the  motions  of 
working,  yet  slacks  at  every  opportunity, 
may  actually  be  putting  in  more  energy 
for  a  given  accomplishment  than  the  worker 
whose  morale  is  good  and  whose  rate  of 
production  is  relatively  high.  Certainly, 
from  the  point  of  view  of  management,  dis- 
content aiTiong  employees  is  costly.  It  may 
be  responsible  not  only  for  low  production 
levels,  but  also  for  wasted  materials,  de- 
terioration of  plant  and  equipment,  absen- 
teeism, excessive  turnover  and  work  stop- 
pages. 

Although  many  theories  have  been  ad- 
vanced as  to  why  men  work  and  the  con- 
ditions which  make  them  satisfied  or  dis- 
satisfied with  their  jobs,  reliable  informa- 
tion can  be  obtained  only  from  a  direct 
study  of  the  worker  himself.  One  nation- 
wide study  shows  that  there  may  be  very 
little  relation  between  what  the  worker 
wants  from  his  job  and  what  his  employer 
thinks  he  wants.  The  eight  factors  listed 
in  Table  XXVIII  were  ranked  with  respect 
to  their  relative  importance  as  factors  in 
morale  by  three  thousand  employees  and 
several  hundred  employers.  The  rank  of 
1  indicates  that  a  given  factor  was  con- 
sidered to  be  most  important,  and  the  rank 
of  8  that  it  was  considered  least  impor- 
tant. The  table  lists  the  average  ranks 
assigned  to  each  item  by  the  two  groups 
of  raters.     The  correlation  between  these 


Job  Satisfaction  and  Accident  Control 


483 


TABl.E  XXVIII 

Rank.    Assionkd    Various    Factors    in    Morai.k    by 
Employrrs  and  Employeks 

The  correlation  between  the  two  rankings  is  approxi- 
mately zero.  [After  S.  J.  Fosdick,  in  Industrial  conflict: 
a  psychological  interpretation,  F'irst  Yearbook  of  the 
Society  for  the  Psychological  Study  of  Social  Issues, 
Cordon,  1939,  p.  119.] 

Employee   Employer 
Morale  Item  Ranking     Ranking 

Credit  for  all  work  done  1  7 

Interesting  work  2  3 

Fair  pay  3  1 

Understanding  and  appreciation  4  5 

Counsel  on  personal  problems  5  8 

Promotion  on  merit  6  4 

Good  physical  working  conditions         7  6 

Job  security  8  2 

two  sets  of  rankings  is  practically  zero. 
(The  coefficient  of  correlation  is  actually 
-0.10.)  Certainly  the  employers  did  not 
know  what  their  workers  wanted,  even 
though  the  table  does  not  prove  that  the 
workers  would  have  been  best  satisfied  by 
having  their  preferences  accepted  as  the 
basis  for  improved  working  conditions. 

In  recent  years  much  use  has  been  made 
of  questionnaire  and  rating  techniques 
of  this  sort  in  the  study  of  industrial 
morale.  The  information  obtained  from 
these  investigations  has  been  useful  both 
for  getting  at  the  general  principles  of 
worker  motivation  and  for  uncovering  spe- 
cific sources  of  discontent  in  particular  in- 
dustrial organizations.  One  of  the  most 
general  conclusions  to  be  drawn  from  these 
studies  relates  to  the  importance  of  finan- 
cial incentives.  Good  pay,  it  appears,  is 
not  the  only  important  factor  in  job  satis- 
faction, nor  is  it  the  most  important  factor. 
The  worker  must  be  treated  with  considera- 
tion and  respect;  he  must  be  made  to  feel 
that  his  contributions  are  valued;  he  must 
be  encouraged  both  to  offer  suggestions  and 


to  seek  advice  in  case  of  need;  and  liis  su- 
pervisors must  be  leaders  rather  than 
'bosses.'  In  otlier  words,  what  seem.s  to  be 
essential  is  ihat  the  worker  be  dealt  witli 
as  an  entire  jjcrsoii  rather  than  as  a  pair  of 
hands. 

ACCIDENT    CONTROL 

Accidents  represent  an  imporiani  lacioi 
in  the  personal  and  social  cost  of  work, 
much  more  important  than  is  commonly 
realized.  For  example,  during  the  period 
of  the  Second  World  War  accidental  deaths 
in  the  United  States  numbered  about 
355,000,  and  there  were  approximately 
36,000,000  accidental  injuries.  W^ar  casual- 
ties in  the  United  States,  on  the  other 
hand,  totaled  only  about  295,000  killed  or 
missing  and  652,000  wounded.  Research  in 
accident  prevention  has  centered  largely 
about  industrial  and  highway  accidents, 
the  kinds  which  account  for  a  large  portion 
of  the  toll. 

The  problem  of  accident  control  has  been 
approached  from  two  principal  directions. 
One  approach  is  the  search  for  general  fac- 
tors influencing  the  accident  rates  of  an  en- 
tire group— motorists,  miners,  factory  work- 
ers—and the  attempt  to  reduce  the  incidence 
of  accidents  by  controlling  these  factors. 
It  has  been  found,  howe\er.  that  in  any 
group  there  is  a  minority  of  so-called  acci- 
dent-prone individuals  who  are  responsible 
for  a  major  share  of  the  group's  accidents. 
Thus  the  other  approach  to  the  problem  of 
accident  control  consists  of  the  attempt  to 
identify  these  persons,  to  determine  the 
principal  reasons  for  their  high  liability 
to  accident,  and  either  to  correct  the  con- 
ditions which  endanger  their  safety  or  to 
reduce  their  exposure  to  hazardous  situa- 
tions. 


484 


Efficiency 


General  Causes  of  Accidents 

There  are  a  number  of  general  factors 
which  affect  o\eraIl  accident  rates  regard- 
less of  individual  differences  in  liability. 
The  earliest  phase  of  accident  research  cen- 
tered about  the  hazards  inherent  in  par- 
ticular activities  such  as  driving  an  auto- 
mobile,  mining  coal   or  operating  a   drill 


•i  140 

13 

cr 

^  130 

"c 

■g 

8  120 

< 

110 
100 


1 

1 

1      1      1 

/ 

/   — 
/ 

/ 

_  ^^ 

^ 

V\v>-Women 

/      — 
/ 
/ 
Men~^' 

/     / 
/    / 

/  / 
1  / 
'/'■^Mean 

1 

1 

1          I^L 

M~~7 

47.5     52.5     57.5     62.5     67.5     72.5     77.5 
Temperature  in  degrees  F 


FIGURE    228.       ACCIDENT    FREQUENCY    IN    RELATION 
TO  TEMPERATURE 

The  best  teniperatuie  is  near  BS"  F.  [From  H.  >r. 
A'ernon,  Accidents  and  llicir  prcveiUion,  Macmillan, 
1936,  p.  76.] 

press.  The  reduction  of  these  hazards, 
which  usually  requires  the  redesign  of 
processes  and  equipment,  has  largely  been 
the  work  of  safety  engineers,  but  the  prob- 
lem has  not  been  entirely  an  engineering 
one.  Surprising  as  it  may  seem,  people  are 
often  reluctant  to  observe  safety  regula- 
tions. We  are  all  familiar  with  the  kind  of 
educational  campaigns  which  have  been 
developed  for  the  purpose  of  persuading 
drivers  and  workers  of  the  necessity  for 
protecting  themselves. 

Many  conditions  that  affect  accident  rate 
are  foimd  in  the  working  environment. 
Illumination  is  extremely  important;  a 
stairwell  which  is  relatively  dimly  illumi- 


nated, a  source  of  glare  in  the  visual  field 
of  a  worker  who  is  tending  a  dangerous 
machine,  the  blinding  headlights  of  an 
approaching  automobile,  all  may  take  a 
heavy  toll.  Temperature  is  another  signifi- 
cant factor  (see  Fig.  228).  Accidents  increase 
when  it  is  too  hot  and  when  it  is  too  cold. 
Many  factors  determine  what  temperature 
is  optimal,  but  the  value  is  likely  to  lie 
in  the  region  of  65  to  70°  F.  There  is  good 
reason  to  believe,  therefore,  that  in  many 
industrial  plants  the  introduction  of  air- 
conditioning  equipment  would  result  in 
considerable  decreases  in  accident  rates. 
Indeed,  it  seems  likely  that  any  condition 
of  work  which  makes  for  the  elimination 
of  excessive  fatigue  will  tend  to  decrease  the 
likelihood  of  accident. 

In  industry,  the  eight-hour  day  does  not 
usually  produce  enough  fatigue  to  have  a 
significant  effect  upon  accident  rates.  Ac- 
cident rates  flucttiate  during  the  day  and 
are  primarily  a  function  of  the  rate  of  work. 
During  peak  performance,  accidents  reach 
their  highest  hourly  rate.  In  longer  work- 
ing days,  however,  there  is  some  evidence 
that  fatigue  increases  the  frequency  of  acci- 
dents toward  the  end  of  the  day.  The 
number  of  accidents  in  relation  to  the 
amount  of  production  is  found  to  be  high- 
est in  the  tenth  hour  of  a  ten-hour  day. 
On  the  highway  the  large  number  of  acci- 
dents involving  a  driver  asleep  is  another 
instance  of  the  role  of  fatigue. 

Accident  Proneness 

\Vith  general  factors  such  as  we  have 
been  disctissing  held  constant,  there  are 
still  wide  individual  differences  in  liability 
to  accident.  Statistics  for  any  randomly 
selected  group  always  show  a  minority  of 
people  who  have  consistently  high  accident 
records  over  long  periods  of  time.  The 
majority,  of  course,   are  just  average,   and 


Accident  Proneness 


485 


the  average  does  not  make  a  great  deal  of 
trouble.  It  is  these  people  at  the  extreme 
end  of  the  distribution  curve  of  accidents 
that  need  special  attention.  Figure  229 
shows  that  the  men  who  had  to  go  to  the 
hospital  often  in  1938  had,  on  the  average, 
to  go  often  in  1939;  and  conversely.  The 
men  who  got  along  without  any  hospital 
visits  in    1938   averaged  only   0.H5   visit   in 


0         12        3        4         5        6         7 
Number  of  hospital  visits  in  1938 

FIGURE    229.       CONSISTENCY    IN    ACCIDENT    TENDEN- 
CIES AMONG  A  GROUP  OF  90OO  STEEL  WORKERS 

Average  numbers  of  tiospital  visits  in  1939  for 
men  who  had,  respectively,  1,  2,  3,---8  hospital 
visits  in  1938.  Accident  hazards  were  similar  for 
all.  [From  J.  Tiffin,  Industrial  psychology,  Pren- 
tice-Hall, 1943,  p.  290.] 

1939,  whereas  the  men  with  8  visits  in  1938 
averaged  almost  4  in  1939.  There  are  two 
kinks  in  this  cui-ve,  but  the  relationship  is 
unmistakable. 

In  recent  years  many  attempts  have  been 
made  to  develop  psychological  tests  which 
would  make  it  possible  to  identify  accident- 
prone  individuals  in  various  kinds  of  work. 
Tests  of  reaction  time,  motor  coordination, 
distractability  and  visual  functioning  have 
been  employed  for  this  purpose  with  some 
success.  Research  of  this  sort  will  even- 
tually enable  us  to  determine  the  extent 
to  which  accident  proneness  is  a  general- 
ized characteristic  of  the  individual  and  to 
what  extent  it  varies  with  the  activity  in 
which  he  is  engaged.     It  ought  eventually 


to  be  possible  to  keep  people  from  engaging 
in  pursuits  in  which  they  are  particularly 
prone  to  accident  or  at  least  to  provide 
them  in  advance  with  special  training  or 
equipment  designed  to  reduce  their  acci- 
dent liability. 

y\lthough  these  tests  point  to  the  possi- 
bility of  detecting  accident-prone  individ- 
uals before  they  have  had  serious  accidents, 
the  past  accident  history  of  the  individual 
is  still  the  most  reliable  indicator  we  have 
of  accident  tendencies.  For  one  thing  iIk 
tests  measure  only  some  of  the  factors  which 
make  an  individual  accident-prone,  and  for 
this  reason  a  person  can  be  accident-prone 
even  though  his  test  performance  is  good. 
On  the  other  hand,  a  person  can  very  often 
compensate  for  his  deficiencies  and  conse- 
quently can  have  a  good  safety  record  al- 
though his  test  scores  are  not  at  all  satis- 
factory. At  present,  therefore,  best  results 
are  obtained  when  the  diagnosis  is  based 
both  upon  test  scores  and  upon  previous 
accident  history. 

REFERENCES 

1.  Bartley,  S.  H.,  and  Chute,  E.  Fatigue  and  im- 
pairment in  man.  New  York:  McGraw-Hill. 
1947. 

A  recent  book  on  the  psvcholog)'  and  phvsi- 
ology  of  fatigue,  reporting  researches  and  clearlv 
written.  It  stresses  the  role  of  psychological 
factors  in  fatigue,  especially  of  frustration. 

2.  Berrien,  F.  K.  Practical  psychologx.  New 
York:    Macmillan,   1944.     Part  3. 

A  well-written  siuvev  of  applied  psychology' 
with   some   useful   chapters  on   efficiency. 

3.  Carmichael,  L.,  and  Dearborn.  W.  F.  Reading 
and  visual  fatigue.  Boston:  Houghton  Mifflin, 
1947. 

An  experimental  study  of  prolonged  reading 
which  failed  to  find  visual  fatigue  or  a  decre- 
ment in  the  eye's  performance. 

4.  DeSilva,  H.  R.  Why  we  have  automobile  acci- 
dents.    New  York:  Wilev,  1942. 


486 


Efficiency 


Some  interesting  statistics  and  a  program  for 
research  into  the  causes  of  highway  accidents. 

5.  Poffenberger,  A.  T.  Principles  of  applied  psy- 
chology.    New   York:    Appleton-Century,    1942. 

A  mature  presentation  containing  fairly  de- 
tailed accounts  of  important  experiments  on 
efficiency. 

6.  Roethlisberger,  F.  J.,  and  Dickson,  W.  J.  Man- 
agement and  the  worker.  Cambridge,  Mass.: 
Harvard  University  Press,  1939. 

A  detailed  description  of  the  well-known 
Western  Electric  experiments  which  bear  pri- 
marily upon  the  problem  of  industrial  motiva- 
tion and  morale. 

7.  Ryan,  T.  A.  Work  and  effort.  New  York: 
Ronald  Press,  1947. 

,\nother  recent  book,  an  extensive  analysis  of 
theory  and  experiment  in  the  field  of  efficiency 
bv  one  of  the  authors  of  the  present  chapter. 


8.  Tiffin,  J.  Industrial  psychology.  (2iul  ed.) 
New  York:  Prentice-Hall,  1947. 

A  new  and  enlarged  edition  of  a  standard 
textbook  dealing  with  the  applications  of  psy- 
chology in  industry  with  a  relatively  brief  dis- 
cussion of  fatigue  and  efficiency. 

9.  Vernon,  H.  M.  Industrial  fatigue  and  effi- 
ciency.   New  York:  Diuton,  1921. 

A  description  of  British  experiments  con- 
ducted during  the  First  World  War. 

10.  Vernon.  H.  M.  Accidents  and  their  prevention. 
New  York:  Cambridge  University  Press  and 
Macmillan,  1936. 

A  statistical  and  psychological  analysis  of  in- 
dustrial, domestic  and  highway  accidents. 

11.  Viteles,  M.  S.  Industrial  psychology.  New 
York:  Norton.  1932. 

\  good  general  account  of  industrial  psychol- 
ogy which  presents  detailed  discussions  of  re- 
search up  to  1932. 


CHAPTER 


21 


Personality 


IN  our  culture,  with  its  emphasis  on  the 
importance  of  being  liked  by  people, 
nothing  is  more  important  than  'personal- 
ity.' In  this  popular  sense,  personality  is 
conceived  by  most  people  as  an  intangible 
quality  that  makes  an  individual  attractive 
or  unattractive  to  his  fellows.  Psychology 
uses  the  word  personality  in  a  much 
broader  meaning.  Every  human  being  has 
characteristics  which  are  shown  in  his  typ- 
ical ways  of  reacting  to  common  situations; 
they  make  up  his  personality. 

Personality  differences  are  evident  in 
every  classroom.  Some  students  are  confi- 
dent of  their  own  ideas,  readily  contrib- 
uting to  the  discussion;  others  are  inhib- 
ited and  seem  afraid  to  raise  their  voices. 
One  student  may  be  rigid  and  inflexible 
in  his  thinking  so  that  nothing  can  alter 
his  preconceptions.  At  the  opposite  and 
no  more  desirable  extreme,  another  student 
may  be  swayed  by  every  passing  fad,  may 
lack  independence  and  decisiveness. 

Classroom  behavior  is  highly  conven- 
tionalized and  is  governed  by  certain  social 
rules,  thus  minimizing  the  expressions  of 
individuality.  Personality  differences  are 
demonstrated  more  clearly  in  freer  situa- 
tions which  are  less  bound  by  custom. 
When  a  group  of  college  students  come 
together  informally,  each  one  is  more  at 


liberty  to  'be  himself.'  Student  A  is  vig- 
orously assertive,  trying  to  dominate  the 
others.  B  is  easy-going,  adaptable,  tending 
to  agree  with  the  majority.  C  is  sensitive, 
regarding  opposition  to  his  opinions  as  a 
personal  injury.  These  characteristics  do 
not,  of  course,  always  occur  in  the  same 
combinations.  One  student  whose  actions 
are  calm  and  secure  may  yet  be  friendly 
and  warm-hearted,  whereas  another  eciually 
calm  and  stable  person  may  be  coldly  aiti- 
cal  of  his  associates.  If  enough  obscr\a- 
tions  can  be  made  of  each  person,  it  be- 
comes possible  to  make  a  word  picture  of 
him,  a  description  of  his  typical  style  of 
behavior  in  interpersonal  relationships. 
This  total  picture  is  what  we  call  his 
personality. 

PSYCHOLOGICAL    CONCEPTS 
OF    PERSONALITY 

So  we  begin  with  the  definition  of  per- 
sonality and  the  consideration  of  what  is 
meant  by  personality  types  and  personality 
traits. 

Definitions  of  Personality 

The  word  personality  comes  from  the 
Latin  persona,  which  was  the  mask  worn 
by  players  in  the  theater.    Thus  at  its  very 


This  chapter  was  prepared  by  Laurancc  F.  Shaffer  of  Teacliers  College.  Columbia 

University. 
487 


488 


Personality 


beginning,  the  word  implied  a  false  ap- 
pearance, which  in  today's  slang  might  be 
termed  a  'front,'  showy  but  deceptive. 
Then,  even  in  Roman  times,  an  interesting 
shift  of  meaning  occurred,  so  that  persona 
came  to  mean  the  player  himself,  as  an  in- 
dividual with  distinct  qualities.  This  is 
almost  the  opposite  of  the  first  meaning, 
for  it  makes  personality  signify  the  true 
character  of  the  individual,  rather  than 
merely  his  appearance. 

The  ancient  contradiction  in  the  defini- 
tions of  personality  is  of  continued  interest 
because  it  throws  light  on  the  difference 
between  the  popular  and  psychological 
usages.  Popular  speech  still  tends  toward 
the  meaning  of  'mask'  or  appearance  in  its 
concept  of  personality.  This  kind  of 
personality  is  the  individual's  superficial 
attractiveness  or  his  social  effect  upon  oth- 
ers. At  the  opposite  extreme,  certain  phi- 
losophers have  used  the  word  for  the  inner 
essence  of  the  individual,  the  ultimate  real- 
ity that  organizes  and  controls  his  observ- 
able behavior.  This  is  a  development  of 
the  'true-character'  definition;  personality 
is  viewed  as  a  first  cause,  and  everything 
about  the  individual  is  explained  as  due 
to  his  personality. 

To  the  psychologist,  however,  personality 
is  neither  a  false  appearance  nor  an  ulti- 
mate cause.  Since  people  are  products  of 
their  biological  structures  and  their  en- 
\  ironments,  personality  has  come  to  be  re- 
garded as  the  individuality  that  emerges 
from  the  interaction  between  a  biological 
organism  and  a  social  and  physical  world. 
Personality  can  be  described  only  in  terms 
of  the  behavior  of  the  individual— his  acts, 
postures,  words  and  thoughts.  It  is  there- 
fore an  appearance,  as  are  all  phenomena 
of  nature,  but  not  a  false  appearance.  In 
this  conception  the  'mask'  and  'substance' 
views  of  personality  arc  fused.     Personality 


consists  of  observable  behavior,  and  it  is 
also  individual  and  intrinsic.  It  is  defined 
as  an  individual's  typical  or  consistent  ad- 
justments to  his  environment. 

Personality  Types 

The  complex  phenomena  of  personality 
can  be  understood  only  if  they  are  de- 
scribed in  detail.  One  of  the  earlier  ap- 
proaches to  the  description  of  personality, 
formerly  much  used,  was  the  division  of 
people  into  types.  According  to  this  usage, 
one  individual  would  be  said  to  be  of  a 
dominating  type,  another  of  a  sociable  type, 
and  a  third  of  a  seclusive  type.  Type  theo- 
ries have  persisted  because  they  appeal  to 
a  long-standing  habit  of  popular  thinking. 
There  is  a  very  common  tendency  to  speak 
of  people  as  being  tall  or  short,  good  or 
bad,  blond  or  brunet.  On  more  careful 
consideration,  everyone  will  recognize  that 
the  extremes  are  exceptional  and  that  most 
people  are  not  tall  or  short,  nor  entirely 
good  or  bad.     (See  pp.  421-425.) 

In  spite  of  their  serious  shortcomings, 
type  theories  of  personality  have  contrib- 
uted to  psychology  concepts  and  terms  that 
have  had  a  wide  influence.  One  of  the  best 
known  is  the  classification  of  introvert  and 
extravert.  The  introvert  is  one  who  turns 
from  active  participation  in  the  objective 
world  to  an  inner  world  of  thought  and 
fantasy.  The  extravert,  on  the  other  hand, 
is  more  directly  governed  by  objective  data 
and  by  a  perception  of  necessity  and  social 
expediency.  This  bipolar  classification  is 
seen  to  be  closely  related  to  the  popular 
distinction  between  the  practical  man  and 
the  visionary.  The  usual  concept  of  extra- 
version  also  has  other  implications.  An 
extravert  is  supposed  to  be  thick-skinned 
and  relatively  insensitive  to  criticism, 
spontaneous  in  his  emotional  expression, 
impersonal  in  arginncnt,  neither  deeply  af- 


Personality  Types  and  Trails 


489 


fected  by  liis  failures  nor  iiuuli  (k:(  iijjicd 
with  self-analysis  or  self-criticism.  Intro- 
version is  associated  with  opposite  tenden- 
cies: sensitivity  to  criticism,  inhibition  of 
emotional  expression,  personalization  in 
discussion,  magnification  of  failures  and 
preoccupation  with  self-analysis  and  self- 
criticism. 

Another  widely  discussed  pair  of  person- 
ality types  is  the  schizoid  and  cycloid. 
These  concepts  are  based  on  the  character- 
istics of  the  two  most  common  types  of 
serious  mental  disorder,  schizophrenia  and 
manic-depressive  psychosis.  The  schizoid 
type  is  tliought  of  as  a  normal  person  whose 
behavior  tends  toward  that  of  the  schizo- 
phrenic. The  schizoid  is  therefore  self- 
centered,  given  to  fantasy,  shyly  withdrawn 
from  social  participation,  highly  strung  and 
sensitive.  The  cycloid  personality  is  char- 
acterized as  emotional,  active,  readily  re- 
sponsive to  external  stimulation  and  given 
to  instability  of  mood.  The  schizoid- 
cycloid  classification  is  not  entirely  inde- 
pendent of  the  introvert-extravert  'types.' 
Although  based  on  different  approaches  to 
the  problem  of  personality,  the  two  systems 
use  many  of  the  same  descriptive  terms. 

The  type  theories  are  unacceptable^  be- 
cau#/jtney  oversimplify  the  description  of 
personality.  First,  as  we  have  just  seen, 
they  assume  that  all  persons  will  fit  into 
one  or  the  other  of  two  categories.  This 
is  contrary  to  the  facts  of  observation  and 
measurement,  which  indicate  that  most 
persons  lie  between  the  two  extremes,  and 
that  there  is  a  continuous  gradation  from 
one  Jgoie  of  a  bipolar  continuum  to  the 
othe^^i^cond,  the  type  tlieories  throw  to- 
gether characteristics  that  are  not  always 
associated  in  real  persons.  For  example, 
the  concept  of  an  introvert  demands  that 
he  be  both  seclusive  and  emotionally  sensi- 
tive.    These  qualities  may  or  may  not  ac- 


tually occur  logeilici.  An  emotionally  sen- 
sitive person  may  be  either  withdrawing  or 
gregarious;  an  aloof  individual  may  be 
either  emotionally  self-criti(al  or  (oidly  in- 
dependent. Fxperimental  studies  of  per- 
sonality characteristics  show  that  the  'types' 
are  comjjosiies,  and  not  pure  or  (iindamen- 
^;^«i>romponents. 

J^^other  objection  to  type  theories  is 
-^heir  tendency  to  give  rise  to  a  confusion 
between  cause  and  effect.  To  say  that  an 
individual  adjusts  by  withdrawing  berausr 
he  is  an  introvert  is  a  superficial  and  circu- 
lar explanation.  The  person's  typical  ad- 
justments are  the  result  of  many  factors, 
the  most  important  of  which  are  found  in 
his  life  history.  His  introversion  is  the 
result  of  these  same  causes.  Classifying  an 
individual  as  belonging  to  a  certain  psycho- 
logical type  does  not  explain  why  he  acts 
as  he  does,  but  only  describes  his  behaxior. 

Personality  Traits 

The  description  of  personality  in  terms 
of  traits  is  clearly  superior  to  its  classifica- 
tion into  types.  A  trait  may  be  regarded 
as  a  dimension  of  personality,  as  a  scale 
along  which  one  characteristic  or  aspect  of 
personality  may  be  measured.  For  exam- 
ple, dominance-submission  is  a  trait  that  a 
person  may  show  in  any  degree.  It  is  con- 
ceived quantitatively,  as  a  continuous  scale 
of  measurement  from  the  greatest  domi- 
nance to  the  most  abject  submission.  Few- 
people  lie  at  either  extreme:  most  shoAv 
the  characteristic  in  a  moderate  or  inter- 
mediate degree.  As  a  trait,  dominance- 
submission  is  regarded  as  only  one  dimen- 
sion of  personality.  People  also  var\  in 
other  dimensions,  and  as  manv  traits  niav 
be  identified  as  are  retjuired  to  account  for 
observations  of  behavior.  Unlike  the  type 
theories,  the  analvsis  of  ti'aits  does  not  re 


490 


Personality 


quire  ihat  all  people  be  cast  into  a  small 
number  of  molds. 

Although  a  trait  is  a  description  of  hu- 
man behavior,  not  every  word  that  de- 
scribes behavior  defines  a  trait.  That  is 
indeed  fortunate,  since  one  study  has 
shown  that  there  are  approximately  eight- 
een thousand  words  in  the  English  lan- 
guage that  designate  forms  of  behavior. 
These  words  specify  behaviors  that  may  be 
observed  in  large  numbers  of  people,  such 
as  accurate,  active,  agile,  alert  and  assertii'e, 
and  also  rarer  qualities,  including  agnos- 
tical,  alarmist,  anarchistic  and  atavistic. 
Designations  such  as  these  are  traits  only 
if  they  fulfill  certain  conditions.  The  most 
important  rec|uirement  is  that  the  trait 
must  describe  the  consistent  behavior  of  an 
individual.  Thus,  in  order  for  accuracy 
to  be  a  trait,  an  individual  must  con- 
sistently display  about  the  same  degree  of 
accmacy,  which  may  be  at  any  point  on  a 
scale  from  very  accurate  to  very  inaccurate, 
in  a  great  variety  of  situations.  If  his  ac- 
curacy fluctuates  widely  from  one  time  to 
another,  or  if  it  depends  on  the  situation 
instead  of  on  his  own  quality,  accuracy  is 
not  a  trait.  It  can,  therefore,  be  seen  that 
a  trait  such  as  accuracy-inaccuracy  may  ex- 
ist in  some  persons  and  not  in  others.  This 
fact  places  limitations  on  the  quantitative 
investigation  of  some  traits,  especially  on 
rare  qualities  such  as  those  of  being  an 
alarmist,  being  anarchistic  or  being  Machi- 
avellian. These  characteristics  cannot  be 
discovered  at  all  in  most  people,  but,  when 
they  do  occur,  they  may  be  the  most  sig- 
nificant personal  quality  in  the  individual. 

Common  traits,  which  exist  in  some  de- 
gree in  almost  all  people,  can  be  studied 
statistically.  The  usual  method  of  investi- 
gation is  to  discover  characteristics  that 
xmiy  together.  It  may  be  found,  for  exam- 
ple, that  people  who  are  idealistic  are  also 


cooperative,  and  friendly,  and  cheerful, 
and  trustful,  and  that  the  opposites  of 
these  qualities  also  go  together.  This  clus- 
ter of  characteristics,  then,  defines  a  trait 
that  has  a  broader  meaning  and  is  there- 
fore more  useful  for  description  than  the 
component  qualities  taken  separately.  We 
have  already  seen  that  the  statistical 
method  that  has  been  applied  for  this  pur- 
pose is  factor  analysis,  which  makes  use  of 
intercorrelations  to  reduce  to  group  factors 
those  measiues  which  vary  together.  (See 
pp.  411  f.) 

As  a  result  of  factor  analysis,  psycholo- 
gists now  agree  that  introversion-extraver- 
sion  is  not  a  trait.  It  is  a  collection  of  a 
number  of  imperfectly  correlated  traits. 
One  research  made  a  factor  analysis  of  a 
large  number  of  questionnaire  items  origi- 
nally intended  to  measure  introversion- 
extraversion.  By  studying  the  questions 
that  fell  into  gioups  as  defined  by  factors, 
it  was  foiuid  that  introversion-extraversion 
consisted  of  five  separate  traits.  They  were 
identified  as  social  introversion  (shyness, 
withdrawal),  thinking  introversion  (medi- 
tation, philosophizing),  depression  (un- 
worthiness,  guilt),  cycloid  tendencies  (ups 
and  downs  of  mood)  and  rhathymia  (happy- 
go-lucky  or  carefree  disposition).  This 
factorial  study  clarified  the  concept  of  in- 
troversion, showing,  for  example,  that  a 
person  who  is  shy  need  not  be  meditative 
or  moody. 

Many  writers  have  attempted  to  make 
lists  of  the  common  traits  of  human  per- 
sonality. When  prepared  by  arm-chair 
speculation,  these  lists  often  have  been  in 
disagreement.  Some  were  short  and  ob- 
viously incomplete,  others  were  long  and 
repetitive.  An  application  of  factor  anal- 
ysis to  the  identification  of  the  common  hu- 
man traits  has  given  a  solution  that  is  a 
marked    advance   over   unsupported   opin- 


Personalify  Traits 


491 


TABLE  XXIX 

Primary  Traits  ok  Pkrsonalitv 

[After  R.   B.   Cattcll,  Description  and  measuremenl  of 

personality,  World  Book  Co.,  1946,  pp.  .313-336.] 


I.  Cyclothymia 
Outgoing 
Good-naturc'l 
Adaptable 
II.  Jntelligcncr 
Intelligent 
Conscientious 
Thoughtful 

III.  Emolionally  mature 

Realistic 

Stable 

Patient 

IV.  Domiimnce 

Boastful 

Egotistic 

Tough 
V.  Surgency 

Cheerful 

Optimistic 

Sociable 
VI.  Sensitive,  imaginative 

Idealistic 

Intuitive 

Friendly 
VII.  Trained,  socialized 

Thoughtful 

Sophisticated 

Aesthetic 
Vin.  Positive  integration 

Independent 

Persevering 

Practical 
IX.  Charitable,  adventurous 

Kindly 

Cooperative 

Frank 
X.  Neurasthenia 

Languid 

Quitting 

Incoherent 
XI.  Hypersensitive,  infantile 

Infantile 

Restless 

Impatient 
XII.  Surgent  cyclothymia 

Enthusiastic 

Friendly 

Trustful 


Schiznthymia 
Withdrawn 
Surly 
Inflexible 

Mental  defer' 

Stupid 

Slipshod 

Unreflective 
Demoralized  emotionality 

Subjective 

Uncontrolled 

Excitable 
Submissiveness 

Modest 

Self-effacing 

Sensitive 
Melancholic  desurgency 

Unhappy 

Pessimistic 

Aloof 
Rigid,  tough,  poised 

Cynical 

Logical 

Hardhearted 
Boorish 

Narrow 

Simple 

Coarse 
Immature,  dependent 

Dependent 

Slipshod 

Unrealistic 
Obstructive,  withdrawn 

Cynical 

Obstructive 

Secretive 
Vigorous  character 

Alert 

Painstaking 

Strong-willed 
Frustration  tolerance 

Adjusting 

Calm 

Phlegmatic 
Paranoia 

Frustrated 

Hostile 

Suspicious 


ion,  although  it  can  undoubtedly  be  im- 
proved by  additional  research.  Starting 
with  a  list  of  some  4000  trait  terms,  the 
number  was  reduced  to  171  descriptive  con- 
cepts   by    eliminating   near-synonyms    and 


rare  characteristics.  A  preliminary  .study 
of  the  relationships  of  the  171  concepts  fur- 
ther rc(hiccd  the  list  to  35  'clusters'  of 
traits.  A  substantial  group  of  adult  men 
was  then  rated  on  each  of  the  .S.5  personal- 
ity variables.  The  correlation  of  each  char- 
acteristic with  each  other  characteristic 
was  calculated,  and  tlie  undeilying  factors 
were  extracted  statistically.  Ihc  twelve 
factors  specified  in  'lable  XXIX  were 
found.  Below  each  factor  in  the  table 
three  descriptive  words  are  given  to  help 
define  the  area  of  personality  indicated. 

By  thus  identifying  and  defining  traits, 
psycholog)'  has  made  considerable  prog- 
ress toward  a  specific  and  objective  under- 
standing of  personality.  Instead  of  a  vague 
and  philosophically  defined  concept,  per- 
sonality has  become  an  observable  and  po- 
tentially measurable  system  of  characteris- 
tics. There  is  a  danger,  however,  that  the 
wholeness  and  uniqueness  of  the  human 
being  may  be  lost  in  the  enumeration  of 
his  separate  qualities.  This  fault  should 
be  o\ercome,  not  by  a  return  to  obscure 
generalities  but  by  increasingly  penetrating 
research  on  the  interdependences  and  inte- 
grations of  the  characteristics  of  person- 
ality. 

MEASUREMENT    OF 
PERSONALITY 

The  measurement  of  personality  senes 
both  theoretical  and  practical  purposes. 
Many  of  the  problems  concerning  the  na- 
ture and  development  of  personality  coidd 
be  solved  satisfactorily  if  we  had  more  pre- 
cise methods  for  measuring  traits.  Meas 
urements  could  be  made  of  aspects  of  per- 
sonality and  also  of  relevant  factors  tliat 
might  affect  personal  development.  The 
relationships  could  then  be  examined  to 
reveal    the    sources    of    personality.      This 


492 


Personaliiy 


ideal  program  of  research  lies  chiefly  in  the 
future,  but  useful  beginnings  have  been 
made,  and  much  of  our  present  knowledge 
of  personality  has  come  through  quantita- 
ti\e  measurement. 

Personality  measurement  also  has  many 
practical  applications.  AV'hen  an  individ- 
ual who  has  difficulties  of  personal  adjust- 
ment comes  for  help  to  a  psychiatrist  or  to 
a  psychological  clinic,  it  is  valuable  to  as- 
sess his  personality.  An  appraisal  of  his 
personality  deficiencies  inchcates  the  degree 
of  disturbance  present  and  the  handicaps 
that  he  will  have  to  overcome.  A  study 
of  his  assets  reveals  the  sources  of  his 
strength  that  can  be  used  in  helping  him 
overcome  his  troubles.  Another  common 
use  of  personality  measurement  is  in  the 
screening  of  large  gioups  of  students,  mili- 
tary personnel  and  others,  to  discover  indi- 
viduals who  need  psychological  assistance 
in  dealing  with  their  personal  adjustments. 
Personality  measurement  has  also  been  at- 
tempted for  positive  aspects  of  individual 
diagnosis,  as  in  the  selection  of  leaders  and 
of  stable  persons  for  responsible  positions. 
At  least  moderate  success  has  been  achieved 
in  all  these  applications. 

Informal  Diagnosis 

The  original  method  of  personality  ap- 
praisal, and  still  a  basic  one,  is  the  inter- 
view. In  using  this  type  of  evaluation,  the 
psychologist  usually  starts  by  listening  to 
the  subject's  own  story,  hearing  his  prob- 
lems or  complaints,  his  interpretation  of 
their  meanings  and  his  account  of  his  past 
experiences.  By  accepting  the  subject's 
story  without  condemnation,  the  psychol- 
ogist frees  him  to  talk  of  more  intimate 
and  emotionally  tinged  matters  and  draws 
out  from  him  a  full  picture  of  his  personal- 
ity. Sometimes  he  questions  the  subject  in 
order  to  probe  attitudes  and  areas  of  ex- 


perience whi<:h  are  suppressed.  In  some 
instances,  especially  when  working  with 
children,  facts  about  the  subject's  life  his- 
tory are  gathered  from  parents,  teachers 
and  other  observers. 

A  highly  skilled  interviewer  gains  im- 
jDressions  from  this  procedure  far  beyond 
those  conveyed  by  the  subject's  words.  Ob- 
servation is  an  integral  part  of  the  method. 
The  subject's  manner  of  speaking,  his  hesi- 
tations, his  averted  glances,  his  signs  of 
emotional  resjDonse,  provide  clues  that  are 
as  valuable  as  his  story  or  even  more  valu- 
able. Because  of  the  opportunity  that  it 
provides  for  making  observations  and  be- 
cause of  its  flexible  adaptability  to  various 
circumstances,  the  interview  will  continue 
to  be  an  indispensable  technique  for  per- 
sonality study. 

Nevertheless,  in  spite  of  all  its  merits, 
the  interview  has  serious  limitations.  Peo- 
ple vary  greatly  in  their  skill  as  interview- 
ers, so  that  the  conclusions  obtained  by 
this  method  are  not  uniformly  valid. 
Moreover,  skill  in  interviewing  is  difficult 
to  teach.  An  excellent  interviewer  rarely 
can  describe  just  how  he  accomplishes  his 
task.  The  skill  has  to  be  acquired  by  a 
trial-and-error  process  of  learning.  The  re- 
sults of  interviews,  clear  to  the  interviewer, 
are  difficult  to  communicate.  They  arc 
not  readily  expressed  in  quantitative  terms 
or  by  precise  description.  For  these  rea- 
sons, psychologists  have  made  many  at- 
tempts to  develop  more  refined  methods 
for  assessing  personality. 

Rating  Methods 

A  rating  scale  is  a  technique  for  quanti- 
fying observations  based  on  acquaintance 
or  on  interviews.  In  the  most  usual  foim, 
a  rating  scale  consists  of  a  question  defin- 
ing an  aspect  of  personality,  followed  by 


Interviews,  Ratings  and  Questionnaires 


493 


Always  at    Seldom 

Self-con- 

Frequently   Painfully  sclf- 

ease.             flustered 

scious  on 

embar-          conscious  and 

by  actions 

occasions. 

rassed.           ill  at  ease. 

or  remarks 

of  others. 

four  or  five  altcinativc  (Icsciiptioiis.     Here       Icadcrshijj,   ingenuity,   tolerant  <■  of  frustra- 
is  an  example.  lion,    etc.,    more    validly    than    they    could 

Is  the  subject  at  ease  or  .self-conscious?  IVom  less  sjjecific  evidence. 

Questionnaires 

In  an  interview  conducted  for  the  pur- 
pose of  assessing  personality,  much  inlor- 
ination  is  gained  hy  asking  questions  and 
evaluating  the  subject's  answers.  Usually 
the  Cjuestions  are  ].)rinlecl,  and  the  subject  is 
instructed  to  mark  or  write  his  respcjnses. 
.Such  a  set  <jf  cpiestions  is  known  as  a 
persondlhy  (juesliofniaiir.  \  question- 
naire obtains  more  uniform  information 
than  an  interview,  since  all  examinees  are 
asked  the  same  questicjns.  That  permits 
the  quantitative  study  of  the  results  and 
the  comparison  of  one  person  with  others. 
The  questionnaire  saves  time,  for  it  is  a 
group  test. 

The  printed  questionnaire  was  first  used 
in  the  First  World  War  for  the  detection 
of  recruits  who  were  emotionally  unstable. 
A  large  number  of  questions  were  assem- 
bled from  the  case  histories  of  persons  who 
suffered  from  maladjustments  of  all  kinds. 
The  typical  style  of  questions  is  sliown  by 
the  following  samples.* 

Do  you  usually  sleep  well?  yes  no 

Do  you  ever  walk  in  your  sleep?  yes  no 
Do   you    feel    tired   most   of   the 

time?  yes  no 
Did  you  ha\e  a  happy  childhood?  yes  no 
Were  you  shy  with  other  boys?  yes  no 
Do  you  make  friends  easily?  yes  no 
Are  you  ever  bothered  by  a  feel- 
ing that  tilings  are  not  real?  yes  no 
Do  you  get  rattled  easily?  yes  no 

*  R.  S.  Woodworth's  Psychoneurotic  Inventorv.  in 
S.  I.  Franz,  Handbook  of  mental  examination 
methods  (2nd  ed.)  ,  1919.  bv  permission  of  The 
Macmillan  Co. 


The  rater  places  a  mark  above  the  most 
appropriate  dcsciiptive  phrase,  or  between 
phrases,  and  his  rating  is  easily  converted 
into  a  numerical  score  on  a  scale  of  1  to  5, 
or  1  to  9  if  the  line  is  checked  between  the 
phrases  as  well  as  at  them.  Another  valu- 
able method  of  rating  requires  the  observer 
to  rank  a  gioup  of  persons  in  the  order  in 
which  they  show  a  characteristic,  as,  for  ex- 
ample, from  the  most  dominant  individual 
to  the  most  submissive  one. 

A  rating  scale  is  not  a  substitute  for  lack 
of  information.  You  cannot  rate  another 
man  unless  you  know  him  and  have  also 
observed  in  him  the  trait  on  which  you  are 
rating  him.  There  has  been  ample  demon- 
stration of  this  point.  Teachers  can  rate 
their  students  well  in  scholarship  but  not 
on  some  other  characteristics,  like  adapt- 
ability or  impulsiveness.  Enlisted  men  do 
a  better  job  in  rating  each  other  on  leader- 
ship than  the  officers  in  charge  of  the  men. 
The  men  know  each  other  intimately  from 
constant  mutual  observation  under  a  Made 
variety  of  circumstances.  Similarly  stu- 
dents can  rate  the  teaching  ability  of  their 
teachers  better  than  the  supervisors  who  do 
not  see  the  teachers  constantly  in  action. 

Sometimes  a  trait  can  be  brought  into 
use  for  special  observation  by  raters.  For 
instance,  a  man  may  be  required  to  build  a 
small  bridge,  being  provided  with  several 
helpers  and  a  very  limited  supply  of  ma- 
terials. By  watching  his  behavior  in  this 
sitviation,  practiced  observers  can  rate  his 


494 


Personality 


This  questionnaire  was  a  'blunderbuss,' 
intended  to  detect  all  sorts  of  maladjusted 
behavior.  It  did  not  attempt  to  measure 
any  personality  traits  separately.  It  was  as- 
sumed that  a  greater  number  of  symptoms 
indicated  a  more  severe  degree  of  malad- 
justment, so  the  score  was  the  number  of 
questions  answered  in  the  imfavorable  di- 
rection. 

Many  recent  personality  cjuestionnaires 
have  limited  themselves  to  a  specified  trait 
or  to  a  series  of  defined  traits,  and  have 
made  some  effort  to  validate  the  score.  An 
example  is  the  Allport  Ascendance-Subinis- 
sion  Reaction  Study,  from  which  the  fol- 
lowing items  are  taken.* 

At  church,  a  lecture,  or  an  entertainment,  if 
vou  a^ri^■e  after  the  program  has  commenced  and 
find  tliat  there  are  people  standing  but  also  that 
there  are  front  seats  available  v\  hich  might  he  se- 
cured without  'piggishness'  or  discointesy,  but  with 
considerable  conspicuousness,  do  you  take  the  seats? 

habitually      

occasionally  

never  


When  you  see  someone  in  a  public  place  or 
crowd  whom  vou  think  you  have  met  or  known, 
do  you  inquire  of  liim  whether  vou  have  met  be- 
fore? 

sometimes      

rarely  

never  

The  validity  of  this  questionnaire  was 
established  by  comparing  its  results  with 
ratings  on  college  students  made  by  them- 
selves and  their  close  associates.  Only  the 
significant  items  were  retained.  Stich  a 
combination  of  the  questionnaire  and 
rating  methods  reduces  the  author's  de- 
pendence on  his  unsupported  opinion  in 
the  construction  of  a  questionnaire. 

Another  method  used  in  the  construction 

•  G.  W.  Allport,  /.  abn.  soc.  Psychol..  1928,  23, 
12.5. 


of  personality  questionnaires  is  to  make  up 
a  very  large  number  of  questions  and  then 
to  determine  by  experimental  study  which 
items  will  distinguish  between  normal  per- 
sons and  definite  groups  of  individuals  that 
deviate  froiu  normal.  For  example,  if  cer- 
tain questions  are  answered  no  by  normal 
persons,  and  yes  by  depressed  persons,  these 
cjuestions  constitute  a  scale  for  measuring 
depression.  The  Minnesota  Multiphasic 
Personality  Inx'entory  is  a  questionnaire 
prepared  by  this  method.  It  consists  of 
550  statements,  phrased  in  simple  language, 
to  which  the  examinee  responds  by  indi- 
cating whether  or  not  the  statement  is  true 
for  him.  Examples  of  statements  are:  "I 
do  not  tire  quickly";  "Someone  has  it  in 
for  me  ";  "At  times  I  think  I  am  no  good 
at  all."  By  comparing  the  answers  of  nor- 
mal people  with  groups  ha\ing  psychiatric 
diagnoses,  keys  have  been  constructed  to 
measure  hypochondriasis  (undue  concern 
about  bodily  complaints),  depression,  hys- 
teria, psychopathic  tendency  (disregard  of 
social  motives),  parajioia  (suspiciousness 
and  delusion),  psychasthenia  (phobias  and 
compulsive  beha^■ior),  schizophrenia  and 
hypomania  (excessive  level  of  activity). 
There  is  also  a  masculinity-femininity 
scale,  consisting  of  the  items  on  which  the 
responses  of  men  and  women  differ.  Each 
of  these  traits  is  scored  by  means  of  a  sep- 
arate key,  and  the  results  may  be  expressed 
as  a  profile  that  shows  the  individual's  rela- 
tive standing  in  each  characteristic  (Fig. 
230).  Several  studies  have  shown  that  this 
questionnaire  is  an  aid  to  the  diagnosis  of 
disturbances  of  personality. 

Performance  Tests 

Performance  tests  have  been  devised  for 
certain  traits,  some  of  the  best-known  be- 
ing the  May  and  Hartshorne  tests  for  meas- 
uring character   traits   in   school   children 


Performance  Tests  and  Projecfive  Methods 


493 


120 

110 
100 
90 
80 

0  70 

1  60 
■^  50 

40 
30 
20 
10 
0 


t' 

Psychosis-^ 

/ 

\ 

:i^ 

) 

>< 

^ 

\ 

Neurosis—^ 

\ 

/ 

'^V 

^N 

_^-. 

V 

^'' 

-— - 



V 

■Normal 

Hs    D     Hy   Pd    Mf    Pa    Pt     Sc    Ma 
Profile  chart 


FIGURE    230.      THRF.E    PROFILES    FROM    THE    MINNE- 
SOTA   MULTIPHASIC   PERSONALITY    INVENTORY 

The  sMiibols  of  tfie  profile  identify  these  scores: 
Hs,  hypochondriasis;  D,  depression;  Hy,  hysteria; 
Pd,  psychopathic  deviate;  Mf,  masculinity-feminin- 
ity; Pa,  paranoia;  Pt,  psychasthenia;  Sc,  schizo- 
phrenia; and  Ma,  hypomania.  The  defined  normal 
score  is  50,  and  scores  abo\'e  70  are  regarded  as  af)- 
normal.  The  lowest  line  represents  the  scores  of 
98  normal  soldiers.  The  dashed  line  shows  64  cases 
of  severe  psychoneurosis  (note  typically  high  Hs,  D 
and  Hy).  The  solid  line  is  the  scores  of  13  cases  of 
psychosis  (note  high  D,  Pa  and  Sc).  [After  H.  O. 
Schmidt,  J.  appl.  Psychol,  1945,  29,  115-131.] 

They  comprise  an  extensive  series  of  tests, 
covering  such  behavior  as  cheating,  lying, 
stealing,  cooperation,  persistence  and  inhi- 
bition. All  the  tests  are  administered  in 
everyday-life  situations,  including  class- 
work,  assigned  'homework,'  athletics  or 
party  games.  The  children  are  not  aware 
that  they  are  being  tested  or  that  their  be- 
havior can  be  detected  or  identified  with 
them. 

An  example  of  one  of  the  cheating  tests 
is  the  'self-scoring'  technique,  in  which 
children  are  given  a  test  of  arithmetic, 
spelling  or  some  other  regular  school  sub- 
ject. The  papers  are  collected,  and  a  rec- 
ord is  made  of  each  child's  answers.     Then 


the  papers,  whirl)  have  not  been  marked 
in  any  way,  are  returned  to  the  children 
together  with  the  rorrect  answers.  The 
children  are  now  told  to  grade  their  own 
papers,  after  which  the  papers  are  again 
collected.  Any  change  which  the  child  has 
made  in  his  answers  can  of  course  be  de- 
tected by  checking  against  the  previous 
records. 

Several  of  the  May  and  Hartsliorne  tests 
use  the  'improbable  achievement'  tech- 
nique. For  example,  the  subject  is  given 
seven  pill  boxes  to  arrange  in  order  of 
weight,  the  correct  rank  order  being  printed 
on  the  bottom  of  each  pill  box.  The  dis- 
criminations required  are  very  fine  and,  if 
the  child  achieves  a  perfect  or  nearly  per- 
fect arrangement,  it  is  clear  that  he  must 
have  cheated  by  looking  at  the  printed 
weights  despite  instructions  not  to  do  so. 

Projective  Methods 

A  new  approach  to  the  exploration  of 
personality  has  received  much  attention 
from  psychologists  in  recent  years.  The 
new  methods  are  called  projective,  because 
in  them  the  subject  tends  to  project  his 
own  characteristics  into  a  response  to  a  sit- 
uation that  is  vague  and  undefined. 

The  use  of  projective  methods  is  based 
on  the  hypothesis  that  the  mechanism  of 
projection  (p.  521)  is  operating,  and  that  an 
indi\idual  reveals  his  own  characteristics 
by  what  he  sees  in  his  environment.  The 
indefinite  character  of  the  material  used 
in  the  projective  tests  frees  the  person  from 
social  conventions  and  from  reality,  so  diat 
he  can  'be  himself.'  These  teclmiques  are 
subtle,  because  the  examinee,  not  knowing 
what  is  a  'good'  answer,  is  less  able  to  dis- 
tort his  responses  deliberately  to  make  a 
favorable   impression. 

The  RorscJtadi  test  is  the  most  widcb 
used    projective    mcthotl.      In    its    present 


496 


Personality 


[onii.  it  was  first  described  in   1921  by  Her-  The  scores  from  the  ten  blots  are  added, 

niann  Rorschach,  a  Swiss  jjsychiatrist.    The      so  as  to  give  the  total  number  of  responses 
material  consists  of  ten   ink-blot  patterns,      referring    to    whole    blots,    determined    by 


similar  in  character  to  Fig.  231.  Five  of 
the  blots  are  in  black  only,  two  are  black 
and  red.  and  three  are  entirely  in  colors. 
The  cards  are  presented  to  the  subject  one 
at  a  time,  the  examiner  saving  only, 
"^\'h;lt  nii"lu  lliis  l:)C?""  Tlic  fxaniincr  ^\•ritcs 


IIGURE   231.      AN   INK   BIOT  SnULAR  TO  THOSE  EM- 
PLOM.D  IN  THE  RORSCHACH  TEST 

the  subject's  responses  in  full.  Alter  the 
ten  cards  are  completed,  the  examiner  goes 
through  them  a  second  time  to  make  a  rec- 
ord of  where  the  subject  saw  each  thing 
that  he  mentioned. 

Each  response  is  scored  with  respect  to 
three  principal   fea lines: 

1.  Location.  AVhcther  the  response  was 
based  on  the  whole  i)loi  or  on  a  detail. 

2.  Determining  quality.  Whether  the 
response  Avas  determined  by  the  form  of 
the  blot,  by  color,  by  shading  or  by  move- 
ment. (The  latter  is  assumed  if  figures  are 
seen  in  motion,  for  instance,  "two  bears 
dancing.") 

3.  Content.  This  refers  to  what  is  seen, 
as  human  figiucs,  animals,  objects,  land- 
scajjes,  maps,  anatomical  details. 


movement,  concerned  ^viih  animals  and  the 
like.  A  number  of  other  scores  are  also 
noted,  such  as  the  total  number  of  re- 
sponses, the  reaction  time  to  each  card,  and 
whether  or  not  the  responses  are  com- 
monly made  ones. 

The  interpretation  of  a  Rorschach  test 
s  a  complicated  task.  Most  of  the  conclu- 
sions dra^vn  from  a  subject's  responses  are 
based  on  logic  and  on  psychiatric  'experi- 
ence,' rather  than  on  formal  experimental 
proof.  For  example,  a  person  with  an  un- 
duly large  number  of  'whole'  responses  is 
described  as  theoretical  rather  than  prac- 
tical, and  gi\en  to  expansive  generalities. 
If  he  gi\es  notably  more  responses  based 
on  small  details  than  most  people,  that 
^hows  a  j^reoccupation  widi  minor  matters, 
a  petty  person  or  even  a  compulsive  one. 
Movement  responses  are  supposed  to  indi- 
cate introversion  or  fantasy,  and  color 
responses  to  show  warmth  of  emotional 
tone.  In  general,  however,  no  interpreta- 
tion is  based  on  a  single  sign.  Responses 
are  compared  to  one  another,  ratios  are 
calculated,  and  an  elaborate  system  of 
checking  and  balancing  factors  is  employed. 
Although  much  work  has  been  done 
with  the  Rorschach  test,  its  validity  is  not 
firmly  established,  largely  because  it  is  so 
difficult  to  find  other  good  measures  of  per- 
sonality against  which  to  check  the  Ror- 
schach results.  Some  of  the  Rorschach 
ratings  have  been  validated  against  other 
test  results,  but  the  final  decision  about 
the  validity  of  the  test,  in  spite  of  the  en- 
thusiasm of  some  of  the  specialists  who 
use  it,  waits  upon  the  future. 

Another  widely  used  projective  method 
is  the  Thrmatir  Apperception  Test.  It 
consists  of  a  scries  of  standard  pictures,  al- 


Projective  Methocis 


497 


inos(  all  ol  whidi  contain  human  figures, 
but  which  arc  sufficiently  aiiiljiguous  lo 
permit  a  variety  of  inlcrprctations  in  terms 
of  desires,  threats  and  emotional  responses. 
I'hc  subject  is  told  to  make  up  a  sif)ry 
alxnit  each  picture.  The  examine)  may 
ask,  "W^hat  is  happening?  What  led  up  to 
it?  What  will  be  the  outcome?  What  are 
the  feelings  and  thoughts  ol  the  charac- 
ters?" It  has  been  iound  that  jjeisons  tak- 
ing this  test  usually  idenlily  themseixcs 
with  one  of  the  characters  in  a  picture,  and 
that  the  stories  become  implicitly  autobio- 
graphical. 

One  of  these  pictures,  reproduced  in  Fig. 
232,  shows  the  head  of  a  young  woman  witli 
a  very  wrinkled  old  woman  behind  hei 
shoulder.  The  older  woman  has  her  chin 
resting  on  her  bony  hand.  The  following 
story  was  told  about  this  picture  b\  a  niitl- 
dle-aged  woman  who  was  diagnosed  as  a 
case  of  conversion  hysteria.  Prominent  in 
her  history  was  an  unfortunate  relationship 
with  her  mother  which  is  reflected  in  this 
account. 

"A  younger  woman  and  an  older  woman, 
very,  very  old,  weatherbeaten.  They  cer- 
tainly don't  do  justice  to  women  in  this,  do 
they?  The  older  woman  looks  as  if  she 
might  have  said  something  to  the  younger 
woman  to  hurt  her  .  .  .  make  her  feel  bad 
or  something.  She  looks  sort  of  pleased 
with  herself  to  see  that  she  could  hint  her. 
Makes  me  think  of  a  witch.  W^ell,  maybe 
this  woman  has  some  sort  of  power  over 
the  girl— as  if  she's  afraid  to  break  away 
from  her.  She  has  a  sort  of  sly  smile  on 
her  face.     Oh,  I  can't  say  anything  more." 

Unlike  the  Rorschach  test,  the  Thematic 
Apperception  Test  has  no  quantitative 
scoring.  The  value  of  the  method  is  that 
it  induces  the  subject  to  verbalize  his 
thoughts,  attitudes  and  feelings  behind  the 
thin     disguise     of     making     uja     a     story. 


riieines  that  recur  in  more  than  one  pic- 
ture are  noted,  and  analyses  aie  made  of 
the  prevailing  emotional  tone  of  the  nar- 
ratives, ol  tli(  subject's  identifications  witli 
characters,  oi  his  strivings  or  needs,  of  liis 
ihwartings    and    conflicts    and    of    his    de- 


FIG.   232.      THEMATIC  APPERCEPTION  TEST 

One  of  the  series  of  pictures  used.  fFioni  H.  .\. 
Miirray,  Thematic  AppercepliDti  Test,  Harvard  L'lii- 
versity    Press,    19^3.] 

fenses.  The  experienced  clinical  ps\cholo- 
gist  can  gain  a  conception  of  the  si:bjccl"s 
personalitv  that  is  rich  and  suggestive.  e\cn 
though  it  is  lacking  in  quantitative  pre- 
cision. 


THE    ORIGINS    OF    PERSONALITY 

Thus  far  our  analvsis  and  description  of 
personality  are  representati\e  of  the  ooss- 
sectional  approach  which  seeks  to  deter- 
mine the  status  of  the  personalitv  at  a 
given    time   in    the    indi\iduars   life.      An- 


498 


Personality 


other  and  probably  more  valuable  ap- 
proach is  the  longitudinal  one,  which  traces 
the  development  of  a  personality  and  tries 
to  identify  the  influences  that  contribute 
to  its  formation.  The  longitudinal  point 
of  view  is  genetic  and  developmental,  see- 
ing a  person  as  a  continuously  growing  and 
learning  organism. 

The  variety  of  influences  that  contribute 
to  the  formation  of  personality  can  be  seen 
quite  clearly  by  case  studies  of  individual 
development.  As  an  example,  we  may 
trace,  by  means  of  a  hypothetical  case,  the 
factors  that  could  produce  a  dominant  or 
ascendant  person.  Suppose  that  a  boy  de- 
velops with  better  than  average  size, 
strength  and  skill.  His  activity  level  is 
high,  owing,  in  part,  to  the  excellence  of 
his  glandidar  balances,  to  his  high  metab- 
olism and  to  his  freedom  from  hampering 
diseases.  In  his  infancy  he  was  given  lov- 
ing acceptance  by  his  parents,  so  that  he 
developed  a  basic  sense  of  security  and  be- 
longing. He  readily  identified  himself 
with  his  father,  who  is  a  large,  secure,  domi- 
nant person.  He  has  had  ample  oppor- 
tunity for  contacts  with  other  children.  He 
is  the  largest  boy  in  his  particular  play 
group  and  has  become  accustomed  to  the 
role  of  initiating  and  leading  their  activi- 
ties. His  parents  encourage  his  independ- 
ence of  action  and  give  him  responsibilities 
in  keeping  with  his  developing  ability  to 
fulfill  them.  Although  he  is  bright  enough, 
bookish  accomplishments  are  not  highly 
regarded  in  his  family  or  in  his  social 
group,  so  he  never  becomes  distinguished  for 
scholarship.  He  is,  however,  rewarded  for 
proficiency  in  sports  and  for  taking  an  as- 
sertive part  in  school  activities.  The  end 
result  of  such  a  development  is  very  likely 
lo  be  a  man  with  a  dominant  personality, 
sure  of  himself,  accustomed  to  being  liked 


by  others,  and  with  values  based  on  vigor- 
ous physical  and  social  activities. 

The  personality  just  sketched  is  by  no 
means  an  ideal  one.  If  other  traits  were 
favorable,  he  could  become  a  successful  ex- 
ecutive, salesman  and  golfer.  Suppose, 
howe\er,  that  he  is  also  insensitive  to  the 
Aveaknesses  and  troubles  of  others,  and  ob- 
tuse to  aesthetic  values  and  intellectual  in- 
terests. Then  he  will  probably  be  a  bore. 
He  is  also  poorly  prepared  for  catastrophe. 
If  failure  should  overtake  him  later  in  life, 
he  will  be  unprepared  for  it,  inexperienced 
in  it. 

More  than  one  pattern  of  conditions  may 
lead  to  approximately  the  same  result  in 
the  development  of  a  personality.  Another 
individual  may  be  reared  in  a  home  in 
which  he  evolves  aspirations  for  domi- 
nance. Some  qualities  or  circumstances 
may  frustrate  the  direct  realization  of  these 
motives.  He  may  be  oAerprotected  by  his 
parents,  or  imable  to  compete  physically 
with  other  boys,  or  lacking  in  skill  or  in- 
telligence. Such  circumstances  may  lead 
him  to  acquire  a  compensatory  dominance, 
which  can  be  recognized  in  its  earlier  stages 
by  excessive  striving,  by  emotional  reac- 
tions to  threats  or  competition  and  by 
other  evidences  of  insecurity.  If  his  at- 
tempted compensation  is  unsuccessfid,  he 
may  become  soiu,  obstructi\e  and  hostile. 
Some  compensations  are  ^•ery  successful  ad- 
justments, however,  and  this  person  as  an 
adult  may  seem  as  genuinely  ascendant  as 
our  first  hypothetical  example.  It  may 
take  a  very  penetrating  psychological  inves- 
tigation to  discover  the  differences  in  their 
origins. 

Both  these  illustrations  show  the  effects 
of  a  great  nimiber  of  factors  on  the  growth 
of  an  aspect  of  personality.  Physicjue, 
glandular  and  metabolic  processes,  health, 
tlie  pattern  of  the  cultine,  social  contacts 


Biological  Factors  in  Personality 


499 


and  opportunities,  paicriial  iiiotlcls,  abili- 
ties and  skills,  all  contribute.  Above  all, 
adjustive  learning  is  important,  for  an  in- 
dividual's personality  is  the  residual  of  all 
the  behavior  that  he  has  found  successful 
in  satisfaction  of  his  needs  and  in  the  reso- 
lution of  his  frustrations  and  conflicts. 
These  factors  do  not  act  separately,  but  are 
interdependent,  so  that  a  change  in  one  of 
the  causal  fac  tors  not  only  changes  the  re- 
sulting personality  directly  but  also  modi- 
fies some  of  the  other  determining  in- 
fluences as  well. 

BIOLOGICAL    FACTORS    IN 
PERSONALITY 

Personality  emerges  from  the  interac- 
tions of  a  biological  organism  with  a  social 
world.  Before  beginning  a  detailed  consid- 
eration of  the  social  development  of  per- 
sonality, it  is  necessary  for  us  to  investigate 
the  influence  of  some  of  the  most  signifi- 
cant biological  factors. 

A  division  of  developmental  factors  into 
biological  and  social  is  like  the  old  oppo- 
sition between  heredity  and  environment 
which  we  have  already  studied.  According 
to  it  an  individual's  attainments,  capacity 
and  character  are  regarded  as  the  result 
of  both  natuie  and  nurtine.  Whatever 
cannot  be  ascribed  to  learning  and  training 
is  attributed  to  the  genes,  the  carriers  of 
inheritance.  In  this  division  between 
heredity  and  environment,  however,  certain 
types  of  environmental  factors  are  omitted. 
Such  environmental  forces  as  temperature 
and  the  chemistry  of  nutrition  contribute 
to  the  growth  of  the  nervous  system,  of  the 
glands  and  of  man's  physical  structure  in 
general,  and  to  the  functioning  of  these 
structures.  The  genes  likewise  make  their 
contribution,  of  course,  but  it  is  a  common 
error  to  classify  as  inherited  all  those  char- 


actciistics  of  man  which  are  not  due  lo 
learning.  The  strength  and  quickness  of 
the  vigorous  child,  for  example,  are  not 
wholly  a  matter  of  his  good  luck  in  draw- 
ing the  right  pattern  of  genes.  They  de- 
pend also  upon  a  fortunate  interaction  of 
the  right  genes  with  favorable  environ- 
mental forces.     (See  pp.  441^43.) 

Evidence  on  this  point  from  anthropo- 
logical studies  is  fairly  conclusive.  The 
physical  measurements  of  American-born 
children  of  southeastern  European  peoples 
have  been  compared  with  measurements  of 
their  parents.  East  European  Hebrews  are 
below  the  American  norms  in  height  and 
skeletal  structure;  yet  their  children,  reared 
in  a  more  favorable  environment,  deviate 
from  their  parents  in  the  direction  of  the 
American  norms.  Even  the  form  of  the 
head  undergoes  change.  The  south  Italian 
has  an  exceedingly  long  head,  but  his 
American-born  children  are  more  short- 
headed.  The  east  European  Hebrew  has  a 
very  round  head,  biU  his  American-born 
children  are  more  long-headed.  In  this 
country  these  immigrant  groups  approach 
a  uniform  type  with  respect  to  head  form. 

Since  even  biological  factors  are  not 
wholly  the  effects  of  inheritance,  personal- 
ity can  no  longer  be  considered,  as  was  for- 
merly the  case,  the  progressive  unfolding  of 
an  innate  constitution.  The  blue-bloodecl 
aristocrat  does  not  owe  his  polished  tastes 
and  manners  to  his  genes.  Nor  does  the 
thief  come  by  his  antisocial  habits  tlirough 
genes  which  make  for  thie%ing. 

The  role  of  biological  factors  is  to  set  the 
limits  within  which  the  individual's  per- 
sonality will  develop.  Their  influence  is 
general  and  indirect  as  compared  witli  the 
influence  of  social  and  psychological  forces. 
This  fact  will  appear  more  clearly  if  we 
consider  specific  biological  factors  in  devel- 
opment.    Three  such  factoids  are  (1)  body 


500 


Personality 


chemistry,  (2)  physique  and  (3)  the  nervous 
system. 

Body  Chemistry  and  the 
Endocrine  Glands 

Most  of  us  are  aware  of  differences  in 
mood  and  behavior  due  to  physical  well- 
being  or  ill-being.  At  times  we  are  slug- 
gish and  despondent;  at  other  times  we  feel 
alert  and  animated.  And  we  are  sometimes 
correct  in  attributing  these  changes  to  diet, 
sleep,  toxins  and  infections.  In  addition, 
however,  the  body  contains  within  itself  a 
mechanism  of  chemical  control  in  its  endo- 
crine organs,  or  glands  of  internal  secre- 
tion. These  glands  release  chemical  sub- 
stances, or  hormones,  into  the  blood  stream, 
which  carries  them  to  all  parts  of  the  body. 
The  hormones  sensitize  or  desensitize  nen'- 
ous  and  muscular  tissue,  the  particular  ef- 
fect depending  upon  the  chemical  compo- 
sition of  the  hormone.  Hence  our  re- 
sponses to  external  objects  are  facilitated 
or  retarded  by  the  activity  of  the  endocrine 
organs.  Thus,  though  the  primary  func- 
tion of  these  glands  is  concerned  with  the 
growth  and  metabolism  of  the  body,  they 
also  influence  behavior.  Clearly  the  endo- 
crine glands  are  important!  ^Ve  have  al- 
ready learned  something  about  them  in 
Chapter  4  in  their  relation  to  development, 
in  Chapter  5  in  their  relation  to  emotion, 
and  in  Chapter  6  in  their  relation  to  mo- 
tivation. Now  we  have  to  examine  their 
relation  to  personality,  reviewing  some  of 
the  facts  which  we  have  already  learned, 
so  that  we  may  have  the  whole  picture 
clearly  in  mind. 

The  thyroid  glatid  is  directly  related  to 
the  metabolism  of  the  body,  that  is  to  say, 
the  destructive  and  constructive  changes  in 
body  tissues.  Its  hormone  acts  as  a  cata- 
lyzer to  facilitate  the  breaking  down  of 
waste  products  so  that  they  can  be  readily 


eliminated  from  the  body.  If  the  thyroid 
gland  is  underactive,  partially  decomposed 
proteins  are  retained  in  the  tissues  and 
further  cell  destruction  is  diminished.  Ox- 
idation is  lessened  and  blood  pressure  falls. 
^Vith  the  metabolic  processes  slowed  up  in 
this  manner,  the  individual  becomes  lethar- 
gic and  despondent.  Easily  fatigued,  he 
often  suffers  from  states  of  depression.  If 
tile  thyroid  gland  is  overactive,  on  the  other 
hand,  metabolism  is  increased  and  body  tis- 
sues are  overstimidated.  An  increase  in 
muscidar  tension  follows,  and  the  person 
appears  excitable,  restless,  worried. 

The  thyroid  gland  is  balanced  by  the 
parathyroids.  An  overacti\e  parathyroid 
tends  to  quiet  and  slow  down  the  individual. 
The  mechanism  involved  is  the  regulation 
of  the  calcium  balance  of  the  body;  a  low- 
ered supply  of  calcium  in  the  blood  stream 
sensitizes  nerves  and  muscles  and  makes  the 
individual  overexcitable.  This  supply  of 
calcium  is  associated  with  the  parathyroid 
hormone.  An  excess  of  the  hormone  means 
an  excess  of  calcium  salts;  a  diminution 
means  a  lowered  calcium  supply.  The  re- 
moval of  the  parathyroids  produces  mus- 
cular tremors,  spasms  and  cramps— an  in- 
dication that  the  nervous  system  is  oversen- 
sitive. An  underactive  parathyroid  may 
thus  be  one  determinant  of  an  excessively 
high  acti\ity  level. 

The  pituitary  gla?id  is  important  in  its 
contribution  to  body  growth.  Impaired 
functioning  of  the  pituitary  in  childhood 
is  related  to  a  generally  deficient  bony 
structure,  weakened  skeletal  muscles  and 
underdeveloped  sex  organs.  The  child 
thus  afflicted  lacks  aggressiveness,  gives  up 
easily,  cries  readily  and  is  regarded  as  cow- 
ardly. Overactivity  of  this  gland  (specifi- 
cally of  its  anterior  lobe)  results  in  gi- 
gantism, thick  skin  and  precocious  sex  de- 
velopment.    The  behavior  picture  in  this 


Physiological  Factors  in  Personality 


501 


case  may  be  one  of  aggressiveness  and  pug- 
nacity. 

The  development  of  the  secondary  sex 
characteristics  is  a  function  of  the  gonadal 
glands.  These  secondary  characteristics  in- 
clude height,  weight,  the  distribution  of 
hair  over  the  body,  subcutaneous  fat  and 
the  mammary  glands.  Experimenters  have 
transplanted  ovaries  from  female  rats  and 
guinea  pigs  to  castrated  male  rats  and 
guinea  pigs.  The  result  has  been  that  the 
male  animals  have  taken  on  the  character- 
istics of  the  female  both  in  physical  and  in 
behavioral  traits.  Similarly,  the  transplan- 
tation of  interstitial  tissue  from  the  male 
testes  to  female  animals  whose  ovaries  had 
been  removed,  has  produced  male  charac- 
teristics. These  experiments  indicate  that 
the  sex  hormones  are  a  contributing  factor 
to  masculine  and  feminine  traits  of  per- 
sonality. 

Extreme  instances  of  glandular  malfunc- 
tioning have  been  mentioned  to  illustrate 
the  importance  of  the  endocrine  organs. 
Normal  individuals,  however,  may  vary 
slightly  in  either  direction  from  the  norm 
of  glandular  balance.  For  example,  the 
sensitivity  of  the  excessively  timid  child  is 
sometimes  a  matter  of  body  chemistry.  Ob- 
servations of  children  show  great  differ- 
ences in  personality  from  infancy  on,  dif- 
ferences which  cannot  be  explained  en- 
tirely on  the  basis  of  experience.  In  gen- 
eral, however,  the  endocrines  do  not  have 
direct  effects  upon  personality.  Rather 
they  initiate  physiological  changes,  the 
final  results  of  which  are  complicated  by 
habit  and  experience.  Not  infrequently 
the  physiological  state,  produced  by  ab- 
normal endocrine  functioning,  seriously  af- 
fects the  individual  through  his  realization 
of  his  condition.  The  depression  caused 
by  an  underactive  thyroid  condition  is  gen- 


erally accentuated  by  a  knowledge  oJ  the 

deficiency. 

Physique  and  Physical  Health 

The  most  obvious  aspects  (A  the  individ- 
ual are  his  physical  characteristics,  his 
height,  weight,  bodily  prr;portirms,  color- 
ing and  physical  beauty.  Their  impor- 
tance in  the  development  of  personality  is 
generally  misconstrued.  Since  they  are 
easily  noticed,  they  have  been  unduly  em- 
phasized as  indicators  of  personality.  Pop- 
ular opinion  persists  in  evaluating  people 
according  to  physical  appearance,  although 
phrenology  and  related  arts  of  character 
reading  have  long  been  thoroughly  discred- 
ited. For  the  most  part  physical  charac- 
teristics are  not  so  much  significant  as  ex- 
ternal signs  of  the  internal  man,  as  that 
they  play  a  part  in  the  development  of 
personality.  Their  effect  is  likely  to  be 
mediated  through  the  social  reception  ac- 
corded to  various  types  of  physical  appear- 
ance. The  undersized  child,  for  example, 
may  acquire  a  feeling  of  inferiority  if  both 
adults  and  children  react  differently  to  him 
than  to  his  fellows. 

Before  parents  can  compare  their  chil- 
dren with  other  children  on  the  basis  of  in- 
tellectual attainment,  they  can  and  do  con- 
sult height  and  weight  norms  and  pro- 
nounce judgment  accordingly.  Their  con- 
stant attention  to  physical  growth  means 
that  the  youngster  builds  up  a  notion  of 
himself  as  a  normal  or  an  abnormal  person 
physically.  This  concept  of  himself  is  also 
fostered  by  the  competitive  advantage  or 
disadvantage  of  his  size  and  weight.  Most 
individuals  tend  to  place  themselves  nearer 
the  desirable  norm  than  they  really  are. 
Most  men  a  little  under  average  in  height, 
for  example,  think  of  themselves  as  taller 
than  they  are. 

Actual    deformity    handicaps    the    ciiild 


502 


Personality 


both  physically  and  psychologically.  Fewer 
physically  handicapped  children  develop 
into  normal  personalities  than  physically 
Avell-favored  children.  One  study  oi  this 
problem  compared  the  responses  of  crip- 
pled girls  with  the  responses  of  normal  girls 
of  the  same  age  on  a  test  of  emotional  sta- 
bility. The  average  score  for  the  crippled 
groiij)  was  75  per  cent  greater  in  the  direc- 
tion of  instability  than  the  score  of  the 
normal  group. 

Sheer  size  and  weight  are  less  important 
in  the  development  of  personality  than 
sticngth  and  agility.  It  is  not  so  often  the 
undersized  child  who  is  pushed  around  by 
other  children  as  it  is  the  physically  weak 
youngster.  Health  and  vigor  are  signifi- 
cant in  the  formative  years,  since  contacts 
and  competition  among  children  are  often 
on  the  physical  level.  Even  in  adult  years 
the  man  with  a  rugged  constitution  is  at  an 
advantage  in  maintaining  an  aggressive  at- 
titude toward  life  and  in  preserving  his 
emotional  balance. 

The  jjarticidar  way  in  which  a  given  per- 
son is  affected  by  his  physical  constitution 
is  further  shaped  by  social  experience.  In 
general  the  physically  inferior  child  follows 
one  of  two  courses  of  development.  If  he 
is  pampered  and  humored  at  every  turn, 
he  under-reacts  toward  his  world.  He  never 
acquires  the  ability  to  solve  his  own  prob- 
lems. If,  however,  his  inferiority  bars  him 
from  the  center  of  the  stage,  he  may  ox>er- 
rcdd  to  compensate  for  his  deficiency.  It 
is  characteristic  of  compensation  that  the 
individual  exceeds  the  normal  person  in 
striving  for  perfection  or  for  power.  One 
of  the  most  famous  track  athletes  of  our 
time  owes  his  career  to  an  accident  in  which 
his  legs  were  badly  burned.  He  persevered 
in  his  running  to  develop  the  injured  leg 
muscles   until   he   outran   all   competitors. 

It  is  true  that  there  is  current  a  theory 


of  three  constitutional  bodily  components 
which  are  held  to  be  diagnostic  of  three 
patterns  of  personality.  This  theory  of  con- 
stitutional types,  one  which  still  awaits  con- 
firmation, has,  however,  already  been  out- 
lined on  pages  422-425. 

The  Nervous  System 

In  enumerating  the  biological  factors 
that  contribute  to  personality,  it  is  easy  to 
overlook  the  most  obvious  of  all— the  qual- 
ity and  effectiveness  of  the  individual's 
nervous  system.  In  addition  to  their  de- 
pendence on  environmental  influences  and 
training,  a  person's  mental  ability,  inanipu- 
lative  and  motor  skills,  and  special  talents 
are  due  in  some  degree  to  the  structure  and 
properties  of  his  nervous  system.  In  par- 
ticular instances  it  is  usually  impossible  to 
distinguish  the  exact  contribution  of  such 
biological  factors  to  performance.  It  seems 
probable,  however,  that  a  person's  neural 
equipment  sets  certain  limits  beyond  which 
training  is  ineffective.  No  amount  of  spe- 
cial teaching  will  enable  a  moron  to  handle 
adequately  problems  of  symbolic  logic. 
Similar  limitations  affect  the  development 
of  special  motor  and  manipulative  skills. 
Each  athletic  coach  knows  that  certain 
tricks  can  be  taught  and  certain  techniques 
perfected,  but  that  motor  coordination, 
speed  of  response  and  physical  alertness  arc 
in  good  measine  determined  by  a  man's 
biological  equipment. 

Although  they  are  truly  important,  the 
limitations  set  by  the  properties  of  the 
nervous  system  are  frequently  exaggerated. 
Most  people  do  not  develop  their  abilities 
as  far  as  their  biological  endowment  per- 
mits. It  is  also  true  that  limitations  of  ca- 
pacity usually  affect  personality  more  strik- 
ingly through  indirect  social  interaction 
than  b)  direct  hindrance.  Failure  is  more 
important  psychologicall)'  when  others  can 


Influence  of  Culfure  on  Personality 


503 


succeed  than  when  no  one  is  successliil. 
Even  when  a  person  can  accomplish  an  end 
by  strenuous  effort,  it  is  not  comforting  to 
see  another  reach  the  same  goal  easily. 

INFLUENCE    OF    CULTURE    ON 
PERSONALITY 

The  culture  in  which  an  individual  is 
reared  exerts  the  broadest  kind  of  social 
influence  upon  his  personality  traits.  An- 
cient man  is  not  like  modern  man,  and 
primitive  peoples  are  not  like  civilized  peo- 
ples, because  of  the  interactions  between 
individual  personalities  and  their  cultural 
backgrounds. 

For  instance,  modern  Western  man  con- 
trasts strikingly  with  the  Greek  of  classical 
times.  The  orientation  toward  time  and 
space  in  the  classical  period  is  quite  for- 
eign to  the  modern  mind.  Classical  man 
lived  completely  in  the  present.  The  cal- 
endar and  the  clock,  those  dread  symbols 
of  the  flow  of  time,  did  not  regulate  his 
life.  He  had  no  conception  of  historical 
development.  So  completely  did  classical 
writers  lack  historical  feeling  that  their  fine 
pieces  of  history  writing  were  confined  to 
events  occurring  within  their  own  memo- 
ries. Thucydides,  it  has  been  said,  would 
have  been  unable  to  handle  even  the  Per- 
sian Wars,  let  alone  the  general  history  of 
Greece,  and  the  history  of  Egypt  would 
have  utterly  confounded  him.  Likewise 
the  spatial  world  of  classical  man  was  lim- 
ited to  his  own  narrow  experience.  Olym- 
pus to  him  represented  extreme  distance, 
and  even  the  Gods  were  no  farther  away. 
As  against  the  unhistorical,  timeless,  spa- 
tially restricted  mind  of  the  classical  Greek 
stands  modern  man  with  his  sensitive  con- 
sciousness of  temporal  distinctions,  his  his- 
torical perspective,  his  appreciation  of  dis- 
tances beyond  his  immediate  horizon  and 


his  orientation  to  an  ever-expanding  spa- 
tial world. 

These  differences  between  classical  man 
and  modern  men  are  not  to  be  explained, 
as  some  historians  have  attempted,  as  the 
difference  between  the  Appollonian  soul 
and  the  Faustian  soul.  Modern  man  is 
what  he  is  because  he  develops  in  a  certain 
social  environment.  He  grows  up  in  a  me- 
chanical world.  He  learns  to  adjust  his 
]>roblems  by  machines  which  annihilate 
spate.  Collective  adjustments  in  a  niedi- 
anized  age  call  for  specialization  of  labor 
and  synchronization  of  effort.  Trains  run 
according  to  schedule  and  factories  accord- 
ing to  the  timeclock,  and  schools  open  and 
close  their  doors  by  the  bell.  The  pure 
present  of  the  classical  mind  becomes  trans- 
muted into  a  finely  discriminating  liine 
sense  which  relates  each  moment  as  it 
passes  to  the  future  and  to  the  past. 

Or  consider  the  personalities  of  people 
in  primitive  societies.  The  Mountain 
Arapesh  of  New  Guinea  are  said  to  lack 
egotism.  These  people  are  by  and  large 
peaceful,  friendly,  genuine,  cooperati\e. 
but  lacking  in  foresight  and  ambition. 
Among  them  there  is  no  definite  hierarchy 
of  leaders.  They  recognize  no  single  scale 
by  which  success  may  be  socially  meas- 
ured. The  admired  personality  is  the  all- 
round  man.  In  contrast  to  these  mild  peo- 
ple of  New  Guinea  are  the  Eskimos  of 
Greenland.  They  are  rampant  individual- 
ists. The  cardinal  traits  of  personal it\  in 
their  society  are  initiative,  self-reliance  and 
aggression. 

Again  these  differences  in  personality 
grow^  in  part,  out  of  different  conditions 
of  life  to  w'hich  the  Arapesh  and  the  Eski- 
mos have  been  compelled  to  adjust,  al- 
though they  also  depend  in  part  upon  the 
way  in  which  each  tribe  treats  its  young 
children.     The  Arapesh  occupy  a  moiui- 


504 


Personality 


tainous  lerrain  which  guarantees  ihcir 
safety  from  invasion  and  at  the  same  time 
yields  them  a  dependable  though  a  meager 
living.  They  eke  out  a  bare  existence 
through  agiiculture,  trading  and  hiniting. 
Not  menaced  by  danger  from  without  and 
not  facing  actual  starvation,  the  Aiapesh 
have  never  de\'eloped  a  strong  social  organi- 
zation. The  tortuous  nature  of  the  country 
\\ith  its  narrow  paths  and  slippery  rocks, 
moreover,  makes  standardization  of  compli- 
cated cooperative  gioup  activit)  difficult. 
Social  relationships  are  consequently  per- 
sonal in  nature.  Though  common  owner- 
ship of  property  is  not  the  usual  practice, 
there  are  exceptions,  such  as  the  com- 
munal sharing  of  food  through  gifts  to 
friends  and  the  giving  of  public  feasts. 

The  personality  of  the  Arapesh  is  thvis 
partly  the  product  of  these  material  and 
social  conditions  of  life.  Their  enemies 
are  natural  forces  so  much  be)ond  their 
control  diat  it  seems  to  them  useless  to 
work  very  hard  to  produce  a  bumper  crop. 
Their  friends  are  their  fellowmen,  and 
the\  all  help  one  another  in  the  work  of 
living.  Both  the  absence  of  organized  pres- 
sure upon  the  individual  to  spur  his  com- 
petitiveness and  the  lack  of  social  approval 
for  the  aggressive  individual  make  for  a 
mild,   imambitious   personality. 

The  Eskimos  of  Greenland,  on  the  other 
hand,  face  such  rigorous  conditions  of  life 
that  only  strong  individuals  can  sur\'ive. 
Any  individual  who,  through  infirmity  or 
other  physical  handicap,  cannot  make  his 
economic  contribution  perishes,  commits 
suicide  or  is  killed.  The  technology  of  the 
group  is  highly  individualistic.  Every  man 
hunts  for  himself  and  manufactures  his  own 
tools  and  weapons.  For  open-sea  hunting 
each  man  uses  his  own  kayak.  Shoidd  he 
capsize,  he  must  be  prepared  to  right  it 
without   help   from   others.     The   Eskimo 


couple  is  a  self-sufficient  economic  unit. 
In  addition  to  her  other  household  tasks, 
the  wife  converts  animal  skins  into  clothing 
and  equipment— an  arduous  procedure. 

This  type  of  individualism  is  favored  bv 
the  difficidty  of  sur\iving  in  the  frigid  zone 
with  the  aid  of  only  a  very  primiti\e  cul- 
tural heritage.  Simple  individual  adjust- 
ment rather  than  cooperative  group  activity 
is  the  first  adaptation  to  such  a  situation. 
For  example,  e\en  when  a  number  of  fami- 
lies li\e  together  in  one  house  during  the 
winter  season,  each  woman  cooks  the  food 
for  her  family  in  her  own  pot  over  her  own 
lamp.  Communal  cooking  is  impractical, 
because  it  woidd  take  too  long  to  heat  the 
food  for  the  gioup  over  blubber  lamps  and 
because  it  woidd  be  difficult  to  transport 
from  summer  to  winter  quarters  a  pot  large 
enough  for  the  group. 

Adaptation  to  environmental  demands  is, 
however,  not  the  only  important  determiner 
of  the  personality  pattern  of  a  cidture. 
Other  factors  may  enter  in.  In  New 
Guinea,  not  far  frorn  the  peaceful  and  un- 
aggiessive  ^Arapesh,  live  the  Mundagumor, 
a  tribe  whose  typical  personality  is  quite 
different.  They  are  described  as  arrogant, 
impatient,  suspicious  and  extremely  quar- 
relsome. These  characteristics  do  not  seem 
to  arise  from  economic  hardships,  as  they 
live  in  a  fertile  lowland.  One  hypothesis 
that  accounts  for  the  difference  between 
these  two  peoples  arises  from  observations 
of  their  treatment  of  children.  The  Ara- 
pesh nurse  their  infants  frequently  and 
affectionately,  wean  them  late  and  offer 
few  frustrations  to  their  young  children. 
The  Mimdagiuiior,  on  the  contrary,  nurse 
their  children  briefly,  slap  them  when  they 
cry  and  e\en  let  some  infants  die  from 
neglect.  It  is  not  hard  to  see  that  the  fomier 
type  of  treatment  would  lead  to  a  secure 


Developmenf  of  Personality 


505 


and  peacetul  personality,  and  the  latter  to 
insecurity  and  aggressiveness. 

Studies  of  a  number  of  other  prinn'tive 
(ultures  have  shown  a  simihir  trend  toward 
a  marked  relationship  between  the  treat- 
ment of  children  and  the  resulting  typical 
personality.  The  interesting  further  ques- 
tion as  to  why  these  tribes  differ  in  their 
attitudes  toward  children  has  not  yet  been 
answered. 

DEVELOPMENT    OF 
PERSONALITY 

The  development  of  personality  does  not 
mean  the  automatic  unfolding  of  intrinsic 
characteristics.  It  refers  to  a  continuous 
process  of  learning  through  which  individ- 
uals acquire  their  typical  modes  of  response. 
Aside  from  the  biological  factors  that  have 
been  described,  the  major  determiners  of 
personality  seem  to  be  the  individual's  ad- 
justments—the ways  in  which  he  has  learned 
to  cope  with  his  conflicts  and  frustrations. 
Unfortunately  for  our  knowledge,  there  are 
relatively  few  satisfactory  experiments  on 
personality  development.  It  has  not  been 
possible  to  subject  children  to  experimental 
procedures  to  determine  what  experiences 
make  a  person  sociable,  or  hostile,  or  out- 
going, or  shy,  and,  indeed,  it  would  prob- 
ably be  highly  undesirable  to  carry  out 
such  researches.  Most  of  our  hypotheses 
come  from  case  studies  of  persons  with 
strikingly  deviant  personalities.  The  back- 
ground factors,  the  presumed  causes  of  the 
personality  traits,  often  have  to  be  deter- 
mined in  retrospect.  They  are  therefore 
subject  to  many  errors  of  observation,  and 
usually  are  not  susceptible  to  quantitative 
treatment.  For  these  reasons,  the  study  of 
personality  development  is  one  of  the  least 
certain  areas  of  psychological  knowledge, 
although  it  is  one  of  the  most  important. 


If  personality  traits  arise  from  the  ways 
in  which  persons  solve  their  conflicts,  it 
will  be  important  to  examine  the  conflict 
situations  to  which  adjustments  must  be 
made.  .Sonic  conflicts  occur  in  the  lives  of 
all  persons  in  our  culture,  and  therefore  are 
the  common  background  of  personality. 
These  conflicts  arise  from  situations  that 
occur  at  all  periods  of  life,  in  infancy, 
childhood,  adolescence  and  maturity.  They 
include  the  experiences  of  weaning,  group 
socialization,  breaking  away  from  parents, 
becoming  economically  .sufficient  and  mar- 
riage. How  an  individual  adjusts  to  these 
critical  situations  in  part  determines  his 
personality.  In  addition  to  the  adjust ivc 
conflicts  that  are  common  to  all  people, 
there  are  many  less  universal  adjustive  situ- 
ations that  influence  individual  personali- 
ties, such  as  rejection  by  parents,  being  less 
favored  than  his  brothers  and  sisters,  social 
isolation  and  physical  disabilities.  Adjust- 
ments to  such  difficulties  also  leave  their 
residua  in  personality  traits. 

Infancy 

The  importance  of  early  infancy  in  the 
development  of  personality  has  been  recog- 
nized for  about  forty  years.  It  is  believed 
that  the  primary  psychological  need  of  the 
infant  is  for  affection  and  security,  which 
are  proA'ided  by  mothering  and  nursing. 
Nursing  is  interrupted  by  weaning,  which 
is  often  regarded  as  the  first  critical  frus- 
tration in  every  person's  life. 

An  experiment  with  puppies  has  sho^\n 
that  they  too  have  a  need  for  suckling  be- 
yond the  requirements  of  nutrition.  Those 
puppies  whose  need  for  suckling  was  frus- 
trated tended  to  suck  other  objects  between 
meals  and  to  show  evidences  of  emotional 
upset.  Evidence  from  case  studies  tends 
to  shoiv  that  this  need  is  also  felt  bv  himian 
infants.     A  studv  of  rats  has  demonstrated 


506 


Personality 


that  feeding  frustration  in  infancy  may 
have  an  enduring  effect  on  the  behavior  of 
aduhs  of  the  species.  The  rats  which  were 
frustrated  early  in  life  by  being  deprived  of 
food,  hoarded  food  to  a  much  greater  de- 
gree, when  again  kept  hungry  as  aduhs, 
than  those  rats  which  had  not  experienced 
the  infantile  food  deprivation. 

We  have  already  noted  that  differences  in 
the  care  of  )oung  children  in  different  cul- 
tures may  cause  variations  in  adult  per- 
sonality. The  same  hypothesis  has  been 
advanced  to  account  for  differences  between 
individuals  in  our  own  culture. 

A  group  of  college  students  were  tested 
with  a  questionnaire  designed  to  measure 
security-insecurity ,  and  they  also  obtained 
from  their  mothers  information  about  the 
age  at  which  they  were  weaned.  A  very 
striking  relationship  was  found.  Those 
who  were  weaned  rather  early  (at  six  to 
nine  months)  had  an  average  security  score 
significantly  lower  than  those  who  were 
breast-fed  nine  months  or  more.  It  was 
found,  however,  that  those  not  nursed  at  all 
or  who  were  weaned  at  a  very  early  age  (at 
three  to  six  months)  did  not  suffer  from 
insecurity.  This  result  was  interpreted  in 
terms  of  the  other  observation  that,  in  the 
cultural  group  of  first-generation  Americans 
from  which  these  students  were  drawn,  the 
failure  to  nurse  the  child  at  all  or  its  ex- 
tremely early  weaning  arises  from  the  in- 
ability of  the  mother  to  nurse  and  not  from 
her  unwillingness  to  do  so.  The  study 
suggests  that  early  weaning  is  perhaps  not 
the  basic  causal  factor,  but  that  it  is  a 
symptom  of  the  mother's  unwillingness  to 
be  bothered  with  the  child,  which  also  mani- 
fests itself  in  many  other  ways  that  affect 
the   infant's   adjustments. 

Although  the  evidence  is  incomplete,  it 
favors  the  view  that  the  character  of  the 
parent-child    relationship    in    infancy   is   of 


permanent  significance  in  the  formation 
of  personality.  Children  who  have  ac- 
quired feelings  of  insecurity  or  anxiety 
during  this  period  have  to  adjust  to  con- 
flict, and  they  may  do  so  by  developing 
traits  that  range  from  the  depressed  and 
withdrawing  to  the  compensatingly  hostile 
and  aggressive,  according  to  the  other  cir- 
cumstances that  shape  the  trials,  errors  and 
successes  of  adjustive  effort. 

Nursing  and  weaning  have  been  de- 
scribed at  length  as  one  area  of  infant 
adjustment.  There  are  many  others,  in- 
cluding later  feeding  problems,  toilet  train- 
ing, displacement  by  a  new  baby  in  the 
family  and  the  beginnings  of  social  con- 
tacts with  other  children. 

Childhood 

Entering  school  at  five  or  six  years  of  age 
is  another  critical  point  in  the  life  of  a 
child,  as  he  is  then  confronted  with  a  new 
world  of  strange  children  and  strange 
adults.  He  has  to  relinquish  the  specially 
privileged  and  protected  position  that  he 
enjoyed  at  home  and  to  learn  the  meanings 
of  equality  and  fairness.  The  extent  to 
which  he  is  prepared  to  meet  this  conflict 
depends  on  the  somewhat  opposed  factors 
of  his  personal  security  as  established  by 
earlier  experiences  and  his  readiness  to 
assume  independence.  The  protective 
mother  that  seems  to  be  good  for  infancy 
is  not  necessarily  beneficial  at  this  time. 
She,  too,  has  an  adjustment  to  make  to 
the  child's  increasing  range  of  individual 
action. 

A  little  later,  approximately  at  seven 
to  twelve  years  of  age,  the  youngster  en- 
counters a  new  social  situation  in  the  de- 
mands of  his  own  group.  Whether  the 
boy  becomes  a  member  of  a  'gang'  or  only 
associates  with  his  school  friends,  in  most 
cases  he  does  enter  a  group  of  his  own  age 


Childhood  and  Adolescence 


507 


that  has  its  own  standards.  Jo  win  appro- 
bation in  this  group,  he  must  show  his 
independence  of  adult  control.  The 
youngster  who  fails  to  make  this  adjust- 
ment may  be  ridiculed  as  a  'sissy'  or  may 
be  excluded  or  avoided.  Inability  to  ad- 
just to  a  social  group  in  later  childhood 
may  arise  from  a  number  of  causes.  A 
youngster  may  not  have  solved  the  problems 
of  earlier  development  constructively,  or, 
conversely,  he  may  be  so  thoroughly  satis- 
fied with  his  dependent  infantile  adjust- 
ments that  he  is  unable  to  relinquish  them. 
The  latter  difiicidty  almost  always  arises 
when  the  parents  have  overprotected  their 
child,  a  relationship  which  makes  depend- 
ence satisfying  to  the  child  because  it  is 
satisfying  to  the  parent. 

Because  the  first  important  social  ad- 
justments are  made  in  the  childhood  pe- 
riod, the  individual  most  often  forms  his 
pattern  of  social  traits  at  this  time.  On 
the  positive  side,  he  learns  leadership, 
friendliness,  sympathy  and  social  adapta- 
bility or  carries  them  over  from  earlier 
experience.  It  is  now  that  compensating 
factors  in  one  phase  may  overcome  handi- 
caps that  originated  in  earlier  development. 
Children  who  are  insecure  in  their  relation- 
ships with  their  parents  may  find  satisfac- 
tions for  their  needs  in  their  associations 
with  contemporaries.  Thus  each  develop- 
mental period  presents  corrective  oppor- 
tunities in  the  development  of  personality, 
as  well  as  new  hurdles  to  be  overcome. 

Frustration  or  conflict  in  the  social  rela- 
tions of  childhood  is  a  frequent  cause  of 
a  feeling  of  inferiority  or  inadequacy.  It 
may  arise  directly  from  the  social  evalua- 
tion of  the  youngster  by  his  fellows,  and  in- 
directly from  his  shortcomings  in  physique, 
skill,  cooperation  or  other  traits  that  his 
fellows  assess.  In  the  initial  adjustments 
to  a  sense  of  inadequacy,  a  boy  or  a  girl 


may  seem  to  show  iiKonsislciii  iiaiis  <>i 
personality,  being  shy  and  full  of  worry 
at  one  time  and  overaggressive  or  exces- 
sively eager  at  other  times.  These  super- 
ficial inconsistencies  are  understandable  in 
terms  of  an  underlying  real  consistency,  the 
need  to  adjust  to  the  demands  of  the  group. 
If  the  young  person's  withdrawing  reac- 
tions are  more  rewarded,  he  will  learn 
them.  In  other  instances  he  will  become 
assertive,  or  hostile,  or  independent  be- 
cause external  circumstances  combine  to 
make  these  attitudes  more  satisfying  to 
him.  The  fixed  social  adjustments  of  many 
adults,  often  not  very  appropriate  to  their 
mature  abilities  and  opportunities,  may 
frequently  be  traced  to  such  childhood 
origins. 

Adolescence 

Adolescence  has  been  defined  in  two 
ways,  as  a  physiological  event  dependent 
on  the  maturing  of  the  sex  functions  and 
as  a  social  period  bridging  the  interval 
from  childhood  to  maturity.  There  is 
some  evidence  that  physiological  adoles- 
cence has  some  effect  on  personalitv  traits 
but  that  this  is  less  extensive  than  popular 
opinion  believes.  Sex  interests,  although 
by  no  means  absent  in  infancy  and  child- 
hood, become  more  intense  and  more  spe- 
cific after  puberty.  Se^•eral  studies  have 
sho^vn  that  boys  and  girls  after  pubert\ 
have  gi-eater  social  maturity  than  those  of 
the  same  age  who  have  not  vet  reached  pu- 
berty. The  interpretation  of  this  finding 
is  not  altogether  clear.  It  may  be  due  to 
physiological  factors,  or  it  may  onlv  reflect 
the  individual's  conception  of  himself  as  a 
more  mature  person  according  to  his  own 
social  norms,  since  the  fact  of  his  or  her 
own  puberty  is  not  unknown  to  the  voimg- 
ster. 

The  social   problems   of  adolescent   ad 


508 


Personality 


justment  vary  greatly  from  one  culture  to 
another.  Adolescence  hardly  exists  in  a 
society  such  as  that  of  Samoa,  in  which 
children  do  not  form  strongly  dependent 
.attachments  to  their  parents,  sex  behavior 
is  relatively  uninhibited,  and  self-support 
is  possible  at  an  early  age  in  a  primitive 
economic  structure.  The  Samoan  boy  or 
girl  slips  from  childhood  into  maturity 
with  little  or  no  transition,  and  certainly 
without  revolt,  conflict  or  'storm  and  stress.' 

The  main  social  problems  of  adolescent 
adjustment  in  our  cidture  have  been  de- 
fined as  emancipation  from  psychological 
dependence  on  parents,  sex  adjustment, 
self-support,  including  the  choice  of  a  voca- 
tion, and  the  development  of  an  adult 
philosophy  of  life.  If  adolescence  is  a  diffi- 
cult period,  it  is  so  because  of  the  conflicts 
involved  in  the  solution  of  these  adjust- 
ments, not  because  of  any  inherent  quality 
of  adolescent  youngsters  themselves.  Par- 
ents often  add  to  the  complexity  of  the 
adjustments  by  refusing  to  recognize  that 
the  child  is  growing  to  maturity.  The  ado- 
lescent is  often  still  a  child,  in  the  eyes  of 
his  father  and  mother,  and  is  treated  ac- 
cordingly. The  result  may  be  either  a 
thoroughgoing  rebellion  or  an  acquiescence 
that  makes  for  arrested  personality  devel- 
opment. 

The  neglect  of  sex  training  in  our  cul- 
ture makes  adolescence  often  a  critical  pe- 
riod of  development,  for  both  boys  and 
girls  are  rarely  prepared  for  the  physical 
and  psychological  changes  in  sex  functions 
that  occur  at  and  after  puberty.  They 
learn  the  meaning  of  these  changes  through 
their  own  groups,  often  with  more  misin- 
formation than  truth,  rather  than  from 
their  parents  or  through  constructively 
planned  education.  Consequently  they 
regard  their  inevitable  sex  interests  and 
feelings  as  private  and  guilty,  finding  them- 


selves in  conflict  because  their  past  training 
is  not  integrated  with  their  present  con- 
cepts of  social  values.  Since  most  adoles- 
cents feel  that  they  cannot  discuss  sex  prob- 
lems with  their  parents  or  with  other  ex- 
perienced adults,  conflicts  of  this  sort  are 
likely  to  remain  unresolved,  causing  much 
needless  anxiety  and  other  disturbances  of 
personality. 

The  impact  of  the  economic  realities  of 
life  hits  most  persons  in  late  adolescence, 
when  they  face  the  choice  of  a  career  and 
the  necessity  for  self-support.  Getting  a 
job,  and  thereby  becoming  an  economically 
independent  person,  is  a  highly  critical 
stage  of  development.  Because  of  the  stand- 
ards of  education  and  experience  that  are 
required  for  superior  positions,  many  young 
people  find  a  serious  gap  between  their 
aspirations  and  what  they  can  realize. 
Their  inability  to  earn  a  living,  or  to  hold 
a  position  that  is  felt  to  be  significant  and 
creative,  often  creates  in  them  attitudes  of 
inadequacy  and  inferiority.  Many  of  the 
irresponsible  and  aggressive  personality 
characteristics  of  youth  are  compensatory 
responses  to  the  frustrations  of  economic 
adjustments. 

There  is  a  popular  belief  that  a  sweeping 
reorganization  of  personality  occurs  in  ado- 
lescence and  that  the  individual  becomes  a 
'new  person'  at  that  time.  This  belief  is 
unfounded.  There  is  a  continuity  of  per- 
sonal development  from  infancy  through 
childhood  and  adolescence  to  maturity,  and 
the  foundations  of  any  one  period  may  be 
found  in  the  preceding  ones.  At  the  same 
time,  it  is  true  that  undesirable  personal- 
ity traits,  brought  along  from  childhood, 
are  sometimes  modified  by  adolescent  ad- 
justments. For  example,  a  youngster  who 
could  not  gain  childhood  recognition  be- 
cause of  physical  weakness  may  readjust  as 
an  adolescent  by  success  in  scholarship,  in 


Adolescence  and  Mafurity 


509 


debating  or  in  other  activities  that  are  more 
valued  by  adolescents  ,  than  by  children. 
Adolescence  has  no  magic  qualities,  but 
personality  changes  can  occur  then  as  at 
any  period,  according  to  the  experiences 
and  learnings  of  the  individual. 

Personality  in  Maturity 

Recently  psychologists  have  paid  increas- 
ing attention  to  the  problems  of  maturity 
and  old  age,  formerly  a  neglected  period. 
The  new  interest  is  due  to  a  recognition 
that  mature  people  do  most  of  the  work 
of  the  world  and  that  the  elderly,  who 
are  becoming  an  increasing  proportion  of 
the  population,  present  special  problems 
of  adjustment. 

Several  questionnaire  studies  of  adults 
over  a  wide  age  range  confirm  the  conclu- 
sion that  early  maturity  and  old  age  are 
periods  of  stress,  with  a  long  interval  of 
relatively  stable  adjustment  in  between. 
This  finding  agrees  with  an  analysis  of  the 
causal  factors.  In  the  early  adult  years, 
usually  in  the  twenties,  the  typical  individ- 
ual completes  his  adolescent  adjustments 
by  finding  his  permanent  life  work,  marry- 
ing and  becoming  a  parent.  These  three 
major  adjustments  inevitably  demand  some 
modifications  of  personality  traits.  The 
following  thirty  years— the  thirties,  forties 
and  fifties— are  the  most  stable  period  of 
life,  with  little  incentive  or  need  for  change. 
With  this  stability  usually  come  gradually 
the  personality  trends  toward  greater  con- 
servatism, tolerance  and  breadth  of  social 
outlook.  There  are  individual  exceptions, 
to  be  sure,  which  can  be  understood  by  a 
psychological  study  of  the  persons  who 
show  them. 

The  personality  changes  of  older  people 
are  in  a  very  large  degree  due  to  the  adjust- 
ment problems  of  senescence.  The  elderly 
begin  to  have  anxieties  about  their  health. 


their  earning  povvet  and  their  sor  ial  acccp 
taljility  in  a  world  dominated  by  those  who 
are  younger.  I  he  mother  whose  children 
are  grown  finds  her  vocation  gone  and  may 
begin  to  doubt  her  real  usefulness.  Unless 
she  achieves  more  successful  adjustments, 
she  may  accjuire  such  compensatory  inter- 
ests as  meddlesome  or  suspicious  interfer- 
ence with  the  lives  of  others.  The  older 
man  who  is  unable  to  work  may  find  him- 
self returned  to  a  dependence  unpleasantly 
reminiscent  of  his  adolescence.  Those  for- 
tunate enough  to  retire  with  a  living  in- 
come often  do  not  have  enough  to  do,  un- 
less they  liave  maintained  strong  avoca- 
tional  interests  through  their  adult  years. 
In  response  to  the  needs  of  the  increasing 
number  of  elderly  persons,  social  and  edu- 
cational programs  are  being  developed  in 
many  centers  to  assist  their  adjustments. 
(See  also  pp.  83-87  for  changes  with  age.) 
The  drama  of  personality  has  the  same 
broad  pattern  from  the  nursing  infant  to 
the  lonely  senile  person.  It  consists  of  mak- 
ing adjustments  to  needs,  frustrations  and 
conflicts,  which  give  rise  to  learning  proc- 
esses by  which  the  individual  acquires  the 
characteristics  of  his  personality. 

REFERENCES 

1.  Allpovt,  G.  \V.  Personal itv.  a  psycholngiral 
interpretation.     New  York:  Holt,  1937. 

A  comprehensive  treatise  on  persoiialitv  that 
takes  lip  the  definition  of  personalitv.  its  de- 
velopment, structme  and  measurement. 

2.  Cattell,  R.  B.  Description  and  measurement 
of  personality.  Yonkers-on-Hiidson,  N.  Y.: 
^Vorld  Book  Co.,  1946. 

A  report  of  a  research  studv,  leading  to  a 
factor  analysis  of   personality   traits. 

3.  Dennis,  W.     The  adolescent.     In  L.  Carmichael 

(Ed.),  Manual  of  child  psychology.     Sew   York: 
"Wiley,  1946.     Chap.  12. 

A   review  of  research    up    to    1940  on   adoles- 


510 


Personalify 


cence,  which  is  defined  in  terms  of  its  biolog- 
ical meaning. 

4.  Greene,  E.  B.  Measurements  of  human  be- 
havior.    Xew  'iork:  Odyssey  Press,  1911. 

An  excellent  survey  of  all  types  of  psycho- 
logical and  educational  measurement,  includ- 
ing measures  of  abilities,  personality  and  edu- 
cational achievement. 

5.  Hunt,  J.  McV.  (Ed.) .  Personality  and  the  be- 
havior disorders.  2  \ols.  New  York:  Ronald 
Press,  1944. 

These  two  volumes,  the  work  of  forty  col- 
laborators from  psychology,  medicine,  anthro- 
pology and  other  fields,  give  the  most  compre- 
hensive survey  of  personality  and  its  abnormali- 
ties. 

6.  I.awton,  G.  New  goals  for  old  age.  New  York: 
Columbia  University  Press,   1943. 

A  popular  presentation  of  the  adjustment 
problems  of  older  persons. 

7.  Mead.  M.  Cooperation  and  competition  among 
primitive  peoples.  New  York:  McGraw-Hill, 
1937. 

An  anthropological  study  that  illustrates  the 
dependence  of  personality  upon  culture. 

8.  Mead,  M.  Research  on  primitive  children.  In 
L.  Carmichael  (Ed.),  Manual  of  child  psy- 
chology.    New  'iork:  Wiley,  1946.     Chap.  13. 

.\  summary  of  anthropological  research 
methods  that  contribute  to  an  understanding 
of  human  personality. 


9.  Murphy,    G., .  and   Jensen,    F.     Approaches    to 

personality.     New  York:  Coward-McCann,  1933. 

One  of  the  clearest  presentations  of  various 

theories  of  personality— the  beha\iorist,  Gestalt, 

psychoanalytic  and  genetic  theories. 

10.  Murphy,  G.,  Murphy,  L.  B.,  and  Newcomb,  T. 
M.  Experimental  social  psychology.  New 
^■ork:   Harper,   1937. 

Contains  important  material  on  motivation, 
personality  and  development. 

11.  Murray,  H.  A.  Explorations  in  persounlity. 
New  York:  Oxford  University  Press,  1938. 

A  classic,  intensive,  research  study  of  the  per- 
sonalities of  a  group  of  normal  men.  The 
Thematic  Apperception  Test  is  described  in 
this  volume. 

12.  Rorschach,  H.  Psycliodiagnostics.  Berne, 
Switzerland:   Hans  Huber,   1942. 

The  description  of  the  use  of  the  Rorschach 
ink-blot   test. 

13.  Stagner,  R.  Psychology  of  personality.  New 
York:   McGraw-Hill,   1937. 

An  excellent  textbook,  recommended  as  the 
first  reference  for  students  interested  in  further 
study  of  personality. 

14.  Tomkins,  S.  S.  The  thematic  apperception  test. 
New  York:    Griuie  and  Siratton,   1947. 

The  manual  on  the  theory  and  technit]iie  of 
the  interpretation  of  this  test. 


CHAPTER 


22 


Personal  Adjustment 


THROUGHOUT  their  lives  all  living  or- 
ganisms, from  amoeba  to  man,  meet  situ- 
ations in  which  they  are  unable  to  satisfy 
their  motives  promptly  or  completely.  A 
hungry  wild  animal  may  not  find  food  in 
the  accustomed  places.  A  college  student, 
hampered  by  the  competitive  activities  of 
other  persons  and  by  his  own  limitations, 
may  not  be  able  to  achieve  as  much  prestige, 
approval  or  success  as  he  feels  he  needs. 
All  these  situations  call  for  adjustment, 
that  is  to  say,  for  persistent  activities  di- 
rected toward  the  realization  of  goals  in 
the  face  of  difficulties. 

It  is  fortunate  that  the  frustration  of 
needs  is  most  often  followed  by  successful 
adjustment.  There  is  special  psychological 
interest,  however,  in  instances  in  which  a 
person  is  unable  to  reach  his  original  goal. 
In  such  cases,  since  the  needs  persist,  indi- 
viduals do  not  usually  give  up  their  mo- 
tives entirely,  but  instead  tend  to  make 
inferior  or  substitute  adjustments.  If  even 
these  substitute  goajs  prove  unattainable, 
the  person  may  remain  in  a  tense  and  un- 
adjusted state,  showing  anxiety  and  other 
varieties  of  behavior  that  are  commonly 
known  as  psychojieiirotic  or  'nervous.' 

The  psychological  study  of  personal  ad- 
justments is  an  examination  of  the  processes 
by  which  people  cope  with  their  needs,  limi- 


tations and  thwartings.  It  tries  to  throw 
light  on  the  conditions  which  lead  to  solu- 
tions of  superior  or  inferior  quality.  No 
other  topic  in  psychology  contributes  more 
directly  to  an  individual's  understanding 
of  his  own  life  problems. 

THE    ADJUSTMENT    PROCESS 

Adjustment  is  the  process  by  which  a 
living  organism  maintains  a  balance  be- 
tween its  needs  and  the  circumstances  that 
influence  the  satisfaction  of  these  needs. 
Many  of  the  simpler  and  more  common  ad- 
justments can  be  described  by  the  pattern 
shown  in  Fig.  233.  An  indi\idual  is  pro- 
ceeding in  a  course  of  action  (1)  that  tends 
toward  some  end  result  (4),  representing 
the  satisfaction  of  a  need.  An  obstacle 
blocks  or  thwarts  the  activity,  leading  (2) 
to  varied  and  usually  intensified  behavior. 
At  length,  some  response  (3)  circimi vents 
the  obstacle  and  readjustment  is  accom- 
plished. This  analysis  indicates  that  the 
essential  aspects  of  the  adjustment  process 
are  the  existence  of  a  motive,  circumstances 
leading  to  its  thwarting,  resulting  in  varied 
responses,  which  may  eventually  lead  to  the 
discovery  of  a  solution.  You  will  notice 
that  this  process  is  basically  similar-  to  die 
one  which   describes   adjustment   as   learn 


This  chapter  was  prepared  by  Laurance  F.  Shaffer  of  Teachers  College,  Columbia 

University. 
511 


512 


Personal  Adjustment 


ing  and  as  thinking,  both  of  which  are 
special  means  for  accomplishing  personal 
adjustment. 

The  adjustment  process  is  a  universal 
sequence  that  can  be  identified  in  the  be- 
havior of  organisms  from  the  lowest  species 
up  to  man.  If  a  paramecium,  a  single- 
celled  animal,  meets  an  obstruction  while 
swimming,  it  will  back  up,  turn  through  a 
small   angle   and   swim   forward   again.      If 


(1) 


(2) 


(4) 


(3) 


FIGURE    233.      SEQUENCE    OF   ADJUSTMENT 

The  iiidh  idiial  is  proceeding  (1)  in  the  direction 
of  the  goal  (4),  when  he  is  blocked  by  an  obstacle. 
He  makes  varied  responses  (2).  nntil  he  disco\ers 
some  response  (3)  that  gets  around  the  obstacle. 
[From  J.  F.  Dashiell,  Fundamentals  of  general  psy- 
chology, Houghton  Mifflin,  1937.] 

the  change  of  angle  is  enough  to  avoid  the 
obstacle,  its  problem  is  solved.  If  the  angle 
is  not  enough,  the  paramecium  goes  through 
the  act  again.  If  it  is  constrained  by  being 
confined  in  a  little  bit  of  water  in  a  fine 
capillary  tube,  whose  diameter  is  hardly 
more  than  the  length  of  the  paramecium, 
it  will  try  to  turn  again  and  again  when 
it  gets  to  the  end  of  the  water  in  the  tube, 
and  will  finally  succeed  by  making  one 
great  'superparamecimn'  effort,  turning 
half  way  around  in  a  single  try.  The  same 
process  is  illustrated  by  many  experiments 
in  animal  learning.  A  hungry  rat  placed 
in  a  maze  is  stirred  to  varied  activity  until 
its  frustration  is  overcome  by  finding  the 
food.  AVe  do  not  have  to  look  to  the  be- 
havior of  lower  animals  for  illustrations, 
however.    Human  responses  to  the  lost  col- 


lar biuton,  the  stalled  automobile  or  the 
failed  examination  are  examples  of  normal 
adjustment  processes. 

Motives  in  Adjustment 

In  its  broadest  sense  adjustment  may  be 
evoked  by  any  motives  whatsoever.  Vital 
physiological  needs  for  air,  water,  food, 
warmth  and  the  like,  when  thwarted,  arouse 
repeated  adjustive  behavior,  but  they  are 
not  of  wide  psychological  interest  for  two 
reasons.  First,  they  are  reasonably  well 
satisfied  under  the  usual  conditions  of  civi- 
lized culture.  Second,  the  thwarting  of  the 
most  vital  needs  may  lead,  not  to  substitute 
adjustments,  but  to  death.  There  can  be 
no  continued  satisfactory  adjustment  to 
lack  of  air,  water  or  food,  except  breath- 
ing,  drinking  or  eating. 

Of  greater  significance  in  human  adjust- 
ments aie  the  social  motives  that  are 
learned  from  the  cultine  in  which  an  indi- 
vidual develops,  or  at  least  are  greatly 
modified  by  it.  In  our  culture  the  needs 
for  affection,  security,  approval,  recogni- 
tion, mastery,  prestige  and  self-realization 
are  among  the  strongest  social  motives. 
This  group  also  includes  the  sex  motives 
which,  although  fundamentally  biological, 
are  strongly  influenced  by  cultural  learn- 
ing. 

All  strong  motives  are  persistent.  Once 
aroused,  they  continue  to  operate  until  re- 
duced by  some  adjustive  act.  In  this  re- 
spect they  reseinble  an  appetitive  desire 
like  hunger,  which  persists  imtil  the  drive 
stimulus  has  been  removed  by  the  inges- 
tion of  food.  The  principal  physiological 
mechanism  of  social  motives  seems  to  be 
tension.  (On  tension  in  relation  to  needs, 
see  p.  114.)  When  confronted  by  a  moti- 
vating circumstance,  as  for  example  a 
competitive  situation  that  calls  forth  a  need 
for  mastery,  a  person  becomes  alert,  ready 


The  Adjustment  Process 


513 


to  react  and  selective  in  making  responses 
that  are  pertinent  to  his  motivation.  His 
set  is  evidenced  by  a  persistent  muscular 
and  visceral  tension  that  continues  until 
adjustment  has  been  accomplished.  I)c- 
velopmentally,  the  tensions  o[  strong  mo- 
tivation are  related  to  the  physiological 
changes  that  occur  in  emotional  states. 

Thwarting 

The  second  aspect  of  an  adjustment 
process  is  the  thwarting  or  nonfulfillment 
of  an  aroused  motive.  Thwarting  may  oc- 
cur in  a  number  of  ways.  A  simple  and 
common  type  of  thwarting  is  the  blocking 
of  an  adjustment  by  a  material  obstacle 
or  by  the  opposition  of  other  people.  This 
is  often  called  frustration.  If  a  man  is  late 
for  an  important  engagement  because  his 
alarm  clock  fails  to  operate,  or  because  his 
train  is  not  on  time,  he  usually  regards  his 
frustration  as  environmental  and  external 
to  his  own  character.  Many  man-made 
thwartings,  due  to  laws,  customs  and  com- 
petitive activities,  are  also  viewed  objec- 
tively. The  usual  response  to  frustration 
is  an  intensification  of  activity  and  effort. 
If  the  frustrator  is  a  person,  an  aggressive 
attack  against  him  is  a  common  reaction, 
and  this  attitude  is  often  shown  against 
inanimate  things  also,  as  when  a  man  kicks 
a  stool  over  which  he  has  tripped.  Un- 
complicated frustration  evokes  vigorous  be- 
havior but,  as  will  be  shown  later,  is  not 
likely  to  result  in  serious  personal  malad- 
justment. 

A  second  general  type  of  th^varting  is 
conflict.  A  conflict  situation  evokes  two  or 
more  motives,  the  satisfactions  of  which  are 
incompatible.  For  example,  it  is  normal 
for  a  boy  to  be  motivated  to  engage  in 
rough-and-tumble  play  with  his  contem- 
poraries, for  this  is  one  of  the  most  ap- 
proved  ways    of   satisfying   his    needs    for 


mastery,  prestige  and  recognition,  i£  a 
certain  youngster  has  developed  a  fear  of 
Ixiug  hurt,  he  has  conflicting  motives  when 
(onlrontcd  with  a  group  of  playing  boys. 
He  sinuiltaneously  wants  someiliing,  and 
lears  the  outcome  of  his  want.  That  is  the 
essence  of  conflid.  An  individual  cannot 
fight  against  his  conflicts  directly,  as  he  can 
against  his  simple  frustrations.  For  that 
reason  conflicts  underlie  most  instances  of 
futile  and  maladaptcd  behavior. 

There  is  a  relationship  between  frustra- 
tion and  conflict.  The  usual  first  response 
to  frustration  is  an  aggressive  attack  on  the 
person  or  thing  that  caused  it.  In  a  child, 
this  aggression  may  be  very  direct  and  ob- 
vious, and  usually  meets  with  punishment 
or  disapproval.  After  the  connection  be- 
tween aggression  and  punishment  has  been 
learned,  the  overtly  aggressive  behavior 
may  be  inhibited  and  replaced  by  a  fearful 
and  insecure  attitude.  In  his  subsequent 
life,  this  person  may  respond  to  frustration 
not  with  aggression  only,  but  also  by  a  con- 
flict between  his  impulses  for  aggression 
and  his  fear  of  retaliation.  Simple  obstruc- 
tions may  be  sufficient  stimuli  under  such 
circumstances  for  arousing  strong  conflicts 
in  some  individuals. 

Adjustment  by  Trial  and  Error 

The  presence  of  th\\arting  implies  that 
an  individual's  first  or  habitual  response 
to  a  need  is  unsuccessful.  The  subsequent 
course  of  his  activity  is,  therefore,  to  try 
another  response,  and  then  another,  until 
some  action  is  discovered  tliat  leads  to  ad- 
justment (see  Fig.  233).  The  early  responses 
to  thwartings  are  varied  activities.  The 
ones  which  are  relati^•ely  more  satisfpng, 
the  adjusting  person  retains.  The  less  suc- 
cessful ones  he  discards  as  'errors.' 

If  a  bov  is  unable  to  compete  Avidi  his 
fellows  because  he  feais  his  o^vn  ■weakness 


514 


Personal  Adjustment 


or  lack  of  skill,  he  is  likely  to  exhibit  a 
number  of  other  adjustive  attempts.  He 
may  bully  younger  children,  daydream  of 
imaginary  accomplishments,  develop  skill 
in  an  unusual  hobby  or  a^'oid  his  friends 
and  sulk  in  his  room.  Superficially  re- 
garded, these  actions  seem  to  be  inconsist- 
ent; the  boy  is  a  dreamer  one  moment  and 
a  btilly  the  next.  Psychologically  they  are 
not  at  all  inconsistent,  for  they  have  a  com- 
mon meaning  to  the  boy  who  is  making 
the  adjustments.  They  are  varied  trials 
that  attempt  to  meet  his  needs  by  substitute 
or  evasive  behavior  when  the  more  usual 
forms  of  satisfaction  are  blocked. 

As  in  all  learning  processes,  the  relatively 
more  satisfying  adjustments  tend  to  be  re- 
tained and  used  again,  whereas  the  less  suc- 
cessful ones  tend  to  be  extinguished.  In 
later  stages  of  adjustment  to  thwarting,  the 
range  of  activities  becomes  narrower,  and 
the  thwarted  person  specializes  in  the  kind 
of  adjustment  that  he  is  most  able  to  make. 
In  this  way  the  changeable  adjustments  of 
childhood  crystallize  into  the  less  flexible 
traits  of  adults.  Thus  one  man  may  be 
aggressive  in  most  of  his  adjustment-de- 
manding situations,  another  may  be  unduly 
suspicious,  and  a  third  habitually  seclusive. 

Adjustive  Solutions 

The  concept  of  what  constitutes  'success' 
or  'satisfaction'  in  the  solution  of  an  ad- 
justment needs  to  be  defined  more  specifi- 
cally, since  it  is  obvious  that  many  cher- 
ished individual  adjustments  are  not  suc- 
cessful in  the  social  sense.  Psychologically 
an  adjustive  solution  is  an  act  that  com- 
pletes or  reduces  the  motivation  that  started 
the  sequence.  When  a  need  is  unfulfilled, 
muscular  or  visceral  tension  keeps  an  in- 
dividual stirred  tip  and  active,  so  that  he 
makes  one  adjustive  attempt  after  another. 
When  this  tension  is  reduced,  the  source 


of  this  self-stimulation  has  been  eliminated. 
The  criterion  of  an  adjustive  solution  is, 
therefore,  tension  reduction.  This  is  true 
whether  the  solution  is  socially  'good'  or 
not.  It  is  an  adjustment  if  it  satisfies  a 
person's  feeling  of  need.  One  of  the  most 
significant  generalizations  of  psychology  is 
that  all  behavior  is  satisfying  to  some  mo- 
tive of  the  individual,  and  that  this  rule 
holds  even  when  the  resulting  actions  are 
illogical,  queer  or  socially  unacceptable. 
That  is  another  way  of  saying  that  all  action 
is  motivated  and  purposive.  The  general 
principle  is  a  key  to  understanding  a  large 
part  of  human  behavior. 

RESPONSES    TO    THWARTING 

To  have  one's  motives  thwarted  is  by  no 
means  an  uncompensated  evil.  If  human 
beings  had  no  needs,  or  if  all  needs  were 
easily  satisfied,  civilization  might  be  re- 
duced to  an  effortless  Nirvana  in  which 
there  might  be  neither  maladjustments  nor 
accomplishment.  It  is  an  accepted  part  of 
our  cultural  pattern  for  persons  to  be 
thwarted  and  to  make  adjustments  that  re- 
sult in  achievement. 

Constructive  Adjustments 

Since  constructive  adjustments  are  as- 
sumed to  be  commonplace,  no  psychologi- 
cal techniques  have  been  developed  for 
assessing  them  in  detail.  Examples  can  be 
found  in  everyday  life.  College  courses, 
for  example,  often  present  difficulties  to 
individual  students  that  thwart  both  their 
educational  and  vocational  aims,  as  well  as 
some  of  their  basic  social  needs  like  the 
needs  for  prestige,  approval  and  self-reali- 
zation. Threatened  with  possible  failure 
in  college,  most  students  adjust  construc- 
tively by  discovering  the  causes  of  the  diffi- 
culty, by  expending  more  time  and  effort 


Responses  to  Thwarting 


515 


on  woi'k,  by  getting  help  or,  if  the  troubles 
are  insurmountable,  by  changing  their 
plans  and  accepting  more  attainable  goals. 
The  normal  thwartings  of  business  exec- 
utives and  of  research  scientists,  and  of  all 
of  us  in  our  social  relationships,  are  most 
often  met  by  similar  procedures.  The  rea- 
sons why  one  person  will  make  a  construc- 
tive adjustment,  whereas  another  person  in 
the  same  situation  will  made  an  inadequate 
adjustment,  are  very  intricate.  This  chap- 
ter seeks  to  clarify  some  of  them.  Two 
preliminary  observations  can  be  made  now: 
(1)  Mere  frustration  more  often  results 
in  better  adjustments  than  conflict;  (2)  a 
strong  emotional  reaction  to  difficulties  is 
detrimental  to  good  adjustment. 

Substitute  Adjustments 

Constructive  adjustments  are  not  the 
only  means  for  reducing  individual  ten- 
sions. The  student  who  is  faced  with  fail- 
ure in  his  college  work  may  adjust  by  mak- 
ing excuses  that  put  the  blame  on  his 
teachers  or  on  irremediable  causes,  by  giv- 
ing an  exaggerated  emphasis  to  his  accom- 
plishments in  athletics  or  other  activities, 
by  daydreaming  about  imagined  success  or 
by  a  host  of  other  actions.  He  may  even 
become  ill  as  a  way  to  explain  his  failure 
respectably  and  thus  escape  censure. 

One  may  wonder  why  these  events  are 
considered  to  be  adjustments  at  all,  since 
they  do  not  overcome  the  real  difficulty  at 
hand.  The  answer  lies  in  an  understand- 
ing of  the  motivation  of  the  student.  When 
he  is  in  danger  of  failing,  not  only  are  his 
vocational  and  educational  plans  endan- 
gered, but,  more  importantly,  his  strongest 
social  motives  are  thwarted.  His  adjustive 
attempts  are  not  directed  to  the  present 
situation,  but  they  are  means  for  coping 
with  the  tensions  of  his  basic  motives.   The 


a(  lions  arc  therefore  substitute  adjustments 
to  the  dominant  needs.  They  give  indirect 
or  partial  satisfaction  to  strong  motives, 
and  hence  tend  to  reduce  tension  and 
anxiety. 

The  chief  shortcoming  of  sutjstitutc  ad- 
justments, however,  is  not  their  failure  to 
remedy  immediate  and  practical  difficulties. 
Since  a  sulistitute  adjustment  usually  is 
driven  by  an  intense  urge  to  satisfy  one 
particularly  strong  need,  it  may  end  by 
thwarting  other  ecjually  important  motives. 
For  example,  showing  off  and  excuse  mak- 
ing may  be  satisfying  to  a  person's  drives 
for  mastery  and  prestige,  but  these  very 
forms  of  behavior  invite  scorn  and  criticism 
from  others,  and  make  it  more  difficult  for 
him  to  satisfy  another  need,  his  need  for 
social  approval.  'Withdrawing  from  the 
company  of  other  people  may  help  a  man 
to  adjust  to  a  fear  of  competition,  but  it 
thwarts  his  needs  for  companionship  and 
security. 

Another  defect  of  substitute  adjustments 
is  that  they  are  usually  antagonistic  to  the 
well-being  of  other  people.  If  a  boy  gains 
adjustive  satisfaction  by  being  a  bully,  or 
if  a  young  woman  asserts  her  feminine 
charms  by  stealing  the  men  friends  of  her 
acquaintances,  such  adjustments  create 
risks  of  retaliation,  of  isolation  and  of  the 
loss  of  social  cooperation. 

While  it  is  not  possible  to  classify  all 
adjustments  as  'good'  or  'bad,'  there  is  un- 
doubtedly a  continuum  from  tlie  most  to 
the  least  effective  ones.  In  general,  tlie  bet- 
ter adjustments  satisfy  an  individual's  mo- 
tives as  an  integrated  system,  without  tlie 
undue  slighting  of  some  needs  at  die  ex- 
pense of  others.  Good  adjustments  also 
facilitate  the  life  processes  of  otiier  per- 
sons, so  that  mutually  helpful  social  rela- 
tionships are  encouraged. 


516 


Personal  Adjustment 


Consciousness  in  Adjustment 

It  must  not  be  thought  that  people  adopt 
inferior  forms  of  adjustment  dehberately 
and  maliciously.  It  is  a  universal  finding 
that  very  few  people,  e\en  quite  normal 
persons,  have  a  clear  insight  into  their 
strong  motives  and  typical  adjustments. 
Persons  who  are  making  poor  adjustments 
usually  have  less  than  aAerage  insight  into 
their  own  behavior.  An  adjustive  act  is 
impulsive,  and  results  in  the  reduction  of 
tension.  The  individual  feels  vaguely  re- 
lieved after  an  aggressive  or  evasive  act, 
but  he  does  not  often  understand  why. 
Since  learning  can  take  place  without  full 
insight,  the  adjustive  response  is  likely  to 
be  made  again  and  to  become  habitual, 
still  without  a  real  understanding  of  its 
significance  in  the  person's  life. 

The  fact  that  people  do  many  things 
without  understanding  why  they  do  them 
is  the  basis  of  the  psychological  concept  of 
unconscious  processes.  This  is  one  of  the 
great  discoveries  of  modern  psychology, 
but  it  is  often  misunderstood.  It  does  not 
mean  that  there  is  a  place  or  organ  called 
the  unconscious  to  which  rejected  motives 
and  shameful  adjustments  are  somehow 
relegated.  In  an  earlier  period  of  psychol- 
ogy, the  intellect  and  the  will  were  much 
discussed,  as  well  as  the  unconscious.  We 
now  know  that  all  these  terms  represent 
dynamic  or  functional  concepts.  They  arc 
descriptions  of  how  people  act,  not  of  or- 
gans or  faculties  that  people  'have.'  Intel- 
lect is  sho'svn  only  by  intelligent  behavior, 
and  will  by  voluntary  behavior  (p.  50). 
Unconscious  has  no  different  significance; 
its  'existence'  is  shown  only  by  the  fact  that 
people  do  not  know  or  understand  their 
most  basic  motives  or  most  habitual  ad- 
justments. (On  the  unconscious,  see  also 
p.  5.) 


Unconscious  aspects  of  individual  be 
havior  arise  from  two  sources  that  are  dis- 
tinguishable, although  closely  related.  (1) 
Much  that  is  imconscious  comes  through 
learning  processes  that  begin  so  early  and 
are  so  gradual  that  they  are  never  raised  to 
perceptual  clearness.  Very  small  children 
learn  to  act  so  as  to  be  approved,  to  fear 
scorn  and  criticism,  and  to  seek  prestige 
through  mastering  others.  These  derived 
needs  continue  to  be  strong  motives  even 
in  adult  life,  but  few  people  are  clearly 
aware  of  the  important  part  they  play  in 
determining  behavior.  (2)  Another  source 
of  unconscious  functioning  is  the  adjustive 
forgetting  of  some  motives  and  adjust- 
ments. This  type  of  forgetting,  called  re- 
pression, will  be  described  more  fidly  later. 
One  way  of  adjusting  to  a  pain-producing 
memory  is  to  forget  about  it.  You  can,  if 
remembering  the  unpleasant  item  is  Aery 
painful.  Nevertheless,  the  experience  may 
continue  to  influence  your  subsequent  be- 
havior, even  though  you  cannot  recall  it 
consciously. 

TYPI  CAL    ADJ  USTMENT 
MECHANISMS 

To  enumerate  all  the  habits  that  even  a 
single  person  uses  adjustively  would  be  an 
impossible  task,  because  the  number  of 
such  responses  is  so  great.  To  a  degiec, 
it  is  adjustive  to  read  the  newspaper,  to 
see  a  motion  picture,  to  smoke  a  cigarette 
or  to  take  a  brisk  walk  around  the  block. 

A  few  adjustive  habits,  however,  are  so 
widely  and  frequently  used  that  they  have 
been  named  and  defined.  These  are 
known  as  adjustment  mechanisms,  or  some- 
times as  dynamisms,  a  term  that  empha- 
sizes the  active  or  functional  nature  of  such 
adjustments.  Although  the  details  of  be- 
havior differ  considerably  from  one  person 


Adjustment  Mechanisms 


517 


to  another,  the  named  mechanisms  provide 
useful  conceptual  point-s  of  reference  for 
describing  conduct.  Thus,  to  designate  a 
type  of  response  as  compensation  or  ralion- 
alization  or  the  like,  saves  the  necessity  of 
a  longer  description  of  its  nature  and  func- 
tion. 

The  common  adjustment  mechanisms 
are  found  in  the  behavior  of  all  people. 
They  are  used  by  the  most  normal  of  peo- 
ple. No  one  need  be  alarmed  when  he 
finds  that  the  mechanisms  are  descriptive 
of  his  own  conduct.  At  the  same  time, 
these  same  mechanisms  are  also  the  basis 
of  some  of  the  most  bizarre  symptoms  of 
the  serious  mental  disorders,  in  which  they 
occur  in  exaggerated  form.  All  people 
have  a  tendency  to  blame  their  shortcom- 
ings on  others;  that  is  normal.  It  is  an  ex- 
treme when  persons  with  delusions  believe 
that  their  families  or  associates  are  con- 
spiring against  them.  A  knowledge  of 
these  commoner  adjustment  mechanisms  is 
essential  to  an  understanding  of  both  nor- 
mal and  abnormal  behavior. 

Compensation 

In  a  culture  such  as  ours  that  places  a 
great  premium  on  competitive  achieve- 
ment, adjustment  mechanisms  are  needed 
to  cope  with  feelings  of  failure  and  in- 
feriority. Several  mechanisms  that  serve 
this  purpose  are  often  grouped  together  as 
defense  mechanisms,  since  they  tend  to  de- 
fend an  individual  against  a  recognition 
of  his  inadequacies.  Compensation,  the 
most  common  of  the  defense  mechanisms, 
consists  of  an  excessive  display  of  a  charac- 
teristic, or  an  overemphasis  of  it,  so  as  to 
balance  or  conceal  a  deficiency. 

Since  the  concept  of  compensation  is 
very  broad,  it  covers  a  great  variety  of  spe- 
cific forms  of  behavior.  The  most  obvious 
forms  of  compensation  are  found  in  child- 


hood. Because  of  their  lack  of  size  and 
strength,  their  great  dependence  on  others 
and  their  constant  frustration  by  adults, 
children  have  especially  strong  needs  for 
comjjcnsatory  adjustment.  Normally  they 
achieve  this  end  by  aggressive  play  and 
noisy  roughliouse,  and  hy  the  inevitable 
teasing,  taunting  and  quarreling  that  chil- 
dren do  among  themselves.  Under  some 
circumstances  children  are  prevented  or  in- 
hibited from  using  these  normal  outlets. 
A  boy  who  has  a  very  great  need  for  ex- 
pressing his  adequacy,  or  who  is  afraid  to 
assert  himself  in  the  common  ways,  may 
bully  younger  children,  steal,  destroy  prop- 
erty and  show  other  marked  compensations. 
These  maladjustments  differ  from  normal 
compensatory  behavior  only  in  degree. 

Adults  also  have  their  normal  compen- 
sations that  help  them  relieve  the  hum- 
drum of  ordinary  existence.  They  include 
hobbies,  sports,  secret  societies,  card  play- 
ing, gossip  and  scores  of  other  activities 
that  balance  frustrations.  Unfortunate 
compensations  can  be  observed  in  persons 
who  tyrannize  over  their  business  subordi- 
nates, or  over  their  families,  usually  be- 
cause they  feel  basically  insecure  of  their 
o\vn  competence.  Parents  often  seek  com- 
pensation through  the  accomplishments  of 
their  children,  pushing  the  youngsters  at 
times  toward  achievements  that  are  be- 
yond their  abilities  or  into  occupations  for 
which  they  are  unfitted. 

As  in  other  substitute  adjustments,  the 
individual  who  compensates  excessi\elv 
satisfies  a  limited  part  of  his  motivation 
at  the  expense  of  thwarting  his  other  needs, 
and  sometimes  at  the  risk  of  retaliation. 
His  total  tension  is  therefore  not  reduced 
fully,  and  his  unacceptable  behavior  is 
likely  to  continue  as  a  vicious  circle,  un- 
less relieved  by  a  fa\orable  change  of  cir- 
cumstances or  by  psychological  counseling 


518 


Personal  Adjusiment 


At  one  time  defensive  behavior  was  re- 
garded as  an  adjustment  to  personal  in- 
feriority, and  an  individual  who  showed  it 
Avas  said  to  have  an  inferiority  complex. 
More  recent  interpretations  of  the  evidence 
show  that  this  generalization  is  faulty.  In- 
ferior strength,  skill,  beauty  or  intelligence 
do  not  in  themselves  evoke  defensive  be- 
havior. In  fact  many  inferior  persons  show 
no  compensations,  whereas  many  really 
adequate  individuals  do.  The  important 
factor  is  the  individual's  conception  of  his 
own  characteristics,  which  he  learns  from 
the  evaluations  made  by  his  social  group. 
A  child  of  average  intelligence  whose  broth- 
ers or  sisters  are  brilliant  may  be  so  much 
criticized,  because  he  fails  to  reach  their 
level  of  achievement,  that  he  accepts  the 
conception  of  himself  as  an  inferior.  He 
may  then  develop  a  fear  of  competition  and 
resort  to  defensive  behavior  in  order  to 
maintain  some  deaaee  of  satisfaction  of  his 


Rationalization 

Persons  may  defend  themselves  by  words 
or  thoughts  as  well  as  by  actions.  Ration- 
alization is  a  defense  mechanism  in  ^vhich 
persons  justify  their  behavior  by  giving  so- 
cially acceptable  reasons  for  it,  with  the 
effect  of  concealing  motives  and  impulses 
that  they  have  learned  to  regard  as  inferior 
or  shameful.  The  rationalizer  seldom  un- 
derstands the  'real'  reasons  underlying  his 
conduct  or  else,  sensing  them  vaguely,  re- 
jects them  as  unworthy.  These  rejected 
motives  include  the  basic  ones  for  mastery 
and  prestige  and  the  aggressive  impulses 
directed  against  frustrating  circumstances 
and  persons.  To  deceive  himself  with  a 
sense  of  virtue  and  to  evade  the  recogni- 
tion of  his  own  antisocial  tendencies,  the 
rationalizer   invents   'good'   reasons   to  ex- 


plain his  conduct.  They  are  his  rationali- 
zations. 

A  boy  who  is  late  for  school  finds  many 
excuses.  Perhaps  the  clock  was  slow,  or 
breakfast  late.  These  are  the  simple  ra- 
tionalizations of  blaming  impersonal  or  in- 
cidental factors  for  which  the  individual 
cannot  be  held  responsible.  Or  perhaps 
the  boy  rationalizes  his  tardiness  as  due  to 
has  having  taken  time  to  do  chores  at 
home;  thus  he  both  places  the  blame  on 
his  parents  and  shows  himself  as  a  willing 
but  unappreciated  worker.  His  real  rea- 
sons may  be  a  fear  of  failure  or  scorn  at 
school,  or  a  need  to  show  his  hostility  to- 
ward his  parents  who  are  pressing  him  to 
greater  academic  effort.  These  motives  he 
recognizes  vaguely  or  not  at  all.  They  are 
'unconscious.' 

Adults  also  rationalize.  Indeed,  almost 
all  human  beings  make  use  of  this  mech- 
anism every  day  in  the  year.  The  un- 
pleasant task  is  not  completed  because 
more  urgent  matters  have  to  be  pursued. 
A  job  is  done  poorly  because  the  right  tools 
were  not  available.  A  promotion  is  not  re- 
ceived because  the  employer  is  biased.  The 
game  is  lost  because  the  opponent  has  all 
the  'luck.'       »  , 

Because  of  its  common  use,  ordinary  ra- 
tionalization cannot  be  regarded  as  a  seri- 
ous maladjustment,  but  it  assumes  exag- 
gerated proportions  in  some  instances.  If, 
through  his  past  experiences,  an  individual 
has  acquired  a  very  strong  need  for  success 
and  an  excessive  fear  of  failure,  his  ra- 
tionalizations can  approach  the  intensity  of 
delusions  of  persecution.  A  woman  stu- 
dent once  attempted  a  difficult  subject 
while  she  was  emotionally  disturbed  by 
other  matters.  She  failed  to  meet  the  re- 
quirements of  the  course.  Unable  to  ac- 
knowledge her  failure  or  its  causes,  she 
placed   the  blame  on   the  professor.     She 


Adjusfment  Mechanisms 


519 


asserted  that  he  was  unfair,  that  he  had 
singled  her  out  lor  jierscciition,  that  he 
took  a  perverse  delight  in  making  a  stu- 
dent miserable.  This  •woman  was  able  to 
tite  many  incidents  that  pointed  to  the 
jjrofessor's  persecution  of  her.  In  the  end 
she  managed  to  transfer  to  another  college, 
'because'  she  could  not  be  associated  with 
an  institution  that  had  such  a  perverted 
character  on  its  faculty.  The  severity  of 
this  student's  adjustment  problem  is  easily 
recognized.  It  accounts  for  the  intensity 
of  her  rationalization. 

Identification 

Adjustive  satisfaction  can  be  gained 
through  the  accomplishments  of  other  per- 
sons and  of  social  groups.  In  using  this 
mechanism,  an  individual  is  said  to  identify 
himself  with  the  person  or  institution 
through  which  he  fulfills  his  needs.  A  sim- 
ple and  almost  universal  type  of  identifi- 
cation is  seen  in  the  relationship  of  a  child 
to  his  parents.  Because  of  his  own  help- 
lessness and  the  apparent  omnipotence  of  a 
parent,  the  child  adopts  the  parent's 
achievements  as  his  own.  Youngsters  often 
show  this  by  imitation.  The  boy's  play  fol- 
lows his  father's  hobby  or  profession;  the 
girl  dresses  up  in  adult  clothes  and  mimics 
her  mother's  household  or  social  activities. 
Less  obviously,  the  child  takes  pride  in  the 
parents'  status  or  strength,  and  adjusts  to 
his  own  frustrations  by  accepting  their  su- 
perior attainments  as  in  part  his  own. 
Since  identification  motivates  the  youngster 
in  learning  the  manners,  attitudes  and  in- 
terests of  his  parents  and  of  his  social 
group,  it  is  a  major  factor  in  personality 
development. 

Other  identifications  develop  outside  the 
family  group,  and  act  as  adjustments  to  in- 
dividual social  thwartings.  By  hero  wor- 
ship, children,   adolescents  and   not  a  feiv 


adults  identify  themselves  with  popular 
public  figures,  imitate  their  characteristics 
and  vicariously  enjoy  their  accomplish- 
ments. Identification  with  clubs,  schools, 
cities,  athletic  teams  and  many  other  cul- 
tural units  may  result  in  as  great  a  feeling 
of  satisfaction  in  their  victories  as  if  the 
achievement  were  a  personal  one.  On  the 
whole,  the  mechanism  of  identification  is 
constructive,  with  many  values  and  few 
harmful  effects.  Harm  comes  when  the 
parent,  identifying  himself  with  the  child, 
puts  pressure  on  the  child  to  achieve  what 
is  impossible  for  him. 

Seciusiveness 

Compensation  and  rationalization  are 
relatively  aggressive  and  externally  ori- 
ented types  of  substitute  adjustment.  An- 
other means  that  a  person  may  employ  to 
cope  with  his  difficulties  is  to  run  away 
from  them.  There  are  several  varieties  of 
these  escape  mechanisms,  of  which  simple 
seciusiveness  is  the  most  basic.  \VithdraAV- 
ing,  timid  or  seclusive  behavior  is  very  di- 
rect evidence  of  a  fearful  response  to  social 
situations.  In  addition,  withdrawing  has  a 
substitute  adjustive  value,  since  the  ^vith- 
drawer  avoids  failure  by  not  attempting  to 
place  himself  in  competition  with  others. 
Seciusiveness  is  an  incomplete  adjustment, 
however,  as  it  provides  no  satisfaction  for 
the  person's  continuing  social  needs.  Un- 
less accompanied  by  other  mechanisms,  it 
usually  residts  in  attitudes  of  self-condem- 
nation and  anxiety. 

Although  everyone  sho^vs  the  seclusi^■e 
adjustment  to  some  extent,  especially  when 
in  a  new  environment  in  which  normal  ad- 
justi^■e  satisfactions  have  not  been  estab- 
lished, its  continued  or  excessive  use  is  un- 
fortunate. Wididrawing  is  less  often  de- 
tected as  a  sign  of  adjustive  need  dian  the 
aggressi\e  defenses,  for  the  seclusive  person 


520 


Personal  Adjustment 


is  not  troublesome.  Indeed,  some  parents 
and  teachers  may  encourage  escape  mech- 
anisms in  children,  mistaking  them  for 
quiet  and  orderly  adjustments.  An  habit- 
ually seclusive  person  is  difficult  to  read- 
just, because  he  has  not  acquired  the  minor 
skills  in  dealing  with  people  that  most  per- 
sons use  in  their  social  contacts.  It  is 
harder  to  break  up  a  seclusi\e  adjustment 
than  an  aggressive  one. 

Fantasy 

Daydreaming,  or  fantasy,  is  both  an  es- 
cape and  a  compensatory  mechanism.  Re- 
leased from  the  bounds  of  reality,  a  person 
can  imagine  any  of  the  satisfactions  that 
he  does  not  attain  moie  directly,  including 
vocational  success,  money  and  possessions, 
sex  satisfactions,  intellectual  brilliance, 
physical  strength  and  beauty  and  all  the 
other  goals  toward  which  he  strives.  Every- 
one daydreams.  In  one  survey  of  college 
students,  all  reported  that  they  had  done 
so  at  one  time  or  another,  and  ninety-eight 
per  cent  admitted  fantasies  during  the  pre- 
ceding month.  It  is  evident  that  this  is  a 
universal  source  of  adjustive  satisfaction. 

A  frequent  type  of  daydream  is  the  con- 
quering hero  pattern,  in  which  the  fantasy 
is  of  accomplishment,  prestige  or  conquest. 
The  martyr  daydream,  an  expression  of 
self-pity  in  which  the  dreamer  pictures  him- 
self injured,  is  really  satisfying  even  if 
superficially  unpleasant,  for  it  is  an  adjust- 
ment to  a  lack  of  appreciation  from  others. 

The  principal  fault  of  daydreaming  is 
the  amount  of  time  that  it  consumes.  A 
student  with  a  habit  of  daydreaming  may 
take  to  compensatory  revery  whenever  he 
meets  a  difficulty,  and  thereby  take  twice 
as  long  as  necessary  to  complete  his  work. 
Fantasy  occurs  frequently  in  persons  with 
markedly  sedusive  adjustments  and  is  their 
principal  means  of  tension  reduction.     In 


some  of  the  sqrious  mental  disorders,  fanci- 
ful delusions  are  found  which  correspond 
in  content  and  function  to  the  daydreams 
of  normal  persons.  Obviously,  fantasy  is 
not  the  cause  of  these  severe  maladjust- 
ments, but  only  an  incidental  symptom. 

Because  of  its  common  occurrence,  day- 
dreaming cannot  be  considered  as  a  path- 
ological condition,  and  no  one  shoidd 
wori'y  about  the  fact  that  he  daydreams. 
Indeed,  fantasy  is  only  narrowly  separated 
from  imaginative  planning.  It  has  posi- 
ti\e  A'alues  in  invention,  literatiue  and  art. 

Repression 

Thoughts  and  impulses  that  are  in  con- 
flict with  the  social  values  of  an  individual 
are  unpleasant  and  troublesome.  Satisfy- 
ing these  rejected  motives,  or  even  think- 
ing about  them,  results  in  unpleasant  feel- 
ings of  guilt  and  anxiety.  Consequently, 
an  individual  may  adjust  by  inhibiting  his 
responses  to  these  needs  and  by  keeping 
himself  from  even  remembering  their  exist- 
ence. This  substitute  adjustment  is  known 
as  repression.  The  repression  of  response 
to  certain  motives  does  not  remove  the 
motives,  however.  Repression  merely  keeps 
them  from  being  recognized  and  satisfied. 
They  may  still  continue  as  tensions  which 
are  either  partially  reduced  by  other  substi- 
tute mechanisms  or  remain  to  serve  as  a 
basis  for  vagaie  anxiety. 

Repression,  like  the  other  mechanisms,  is 
found  in  the  behavior  of  quite  normal  peo- 
ple as  well  as  of  the  seriously  maladjusted. 
As  Freud  pointed  out  long  ago  in  his 
Psychopathology  of  Everyday  Life,  all  per- 
sons have  lapses  of  memory,  make  slips  of 
the  tongue  or  pen  or  have  strange  blind 
spots  in  their  understanding  of  their  en- 
vironments that  point  to  the  existence  of 
repression.  A  man  wished  to  invite  a 
couple  to  dinner.     He  greatly  admired  the 


Adjusfment  Mechanisms 


521 


wile.  His  note  lo  ihe  liusband  read:  "I 
liope  to  sec  your  wile  -and  me  at  dinner 
tomorrow."  A  vain  physician  says,  "  1  lie 
number  ol  physicians  who  understand  the 
nostril,  even  in  this  great  city,  can  be 
counted  on  one  fin(rer—p'drdon  me,  I  meant 
to  say  on  the  fingers  ol  one  hand."  Se- 
cretly, he  believes  that  he  is  the  only 
authority,  and  his  real  but  ordinarily  in- 
hibited vanity  appears  in  an  'uninten- 
tional' slip  of  the  tongue.     (See  p.  175.) 

The  basis  of  repression  is  the  phenome- 
non of  inhibition,  which  has  already  been 
described  in  connection  with  conditioning 
and  learning  (p.  142).  It  requires  no  oc- 
cult explanation  such  as  the  'damming  up' 
of  repressed  memories  in  the  'unconscious.' 
One  way  to  adjust  to  a  situation  is  simply 
to  fail  to  respond  to  it,  and  this  failure  may 
operate  in  the  verbal  or  other  symbolic  be- 
havior in\'olved  in  recall,  as  well  as  in  the 
case  of  motor  responses.  The  chief  danger 
in  repression  is  that  it  hampers  your  re- 
education. In  order  to  learn  a  new  re- 
sponse to  a  situation,  often  a  more  con- 
structive adjustment,  you  have  to  recognize 
and  respond  to  the  problem.  You  cannot 
do  that  if  the  problem  has  been  repressed. 

Projection 

A  rejected  or  repressed  motive  is  not  reC' 
ognized  in  your  own  behavior,  yet  you  will 
still  be  excessively  sensitive  or  defensive  to 
evidences  of  it.  This  often  leads  to  seeing 
your  own  inferior  impulses  in  other  people, 
and  that  is  the  mechanism  of  projection. 
An  awkward  person  sees  and  criticizes  awk- 
wardness in  others.  Doing  so  has  an  ad- 
justive  value  similar  to  that  of  rationaliza- 
tion, for  it  bolsters  up  his  self-esteem  by 
emphasizing  that  others  are  worse  than  he. 
A  person  with  conflicts  about  his  own  hon- 
esty is  more  likely  to  see  cheating  and  other 


loims  ol  dishonesty  in  the  world  around 
liiiii.  I»y  condemning  such  faults  strongly, 
he  ( rxpresses  his  own  guilt  and  self-tondem- 
nation  indirectly,  with  less  anxiety  than  if 
he  recognized  his  own  shortf oniings.  Pro- 
jection is  especially  noticeable  in  sexual 
conflicts.  An  individual  with  unsolved  .sex 
problems  imputes  sexual  aims  to  others, 
and  may  be  excessive  in  denouncing  them 
or  in  guarding  against  them.  Such  is  the 
traditional  'old  maid's  delusion,'  thougli 
fortunately  only  a  small  proportion  of  un- 
married older  women  really  show  it  in  ap- 
preciable degree. 

The  mechanism  of  projection  is  seen 
most  clearly  in  delusions  of  persecution 
and  in  the  less  severe  but  similar  attitudes 
of  chronically  suspicious  people.  Feeling 
thwarted,  the  individual  has  an  impulse  to 
attack  the  sources  of  his  frustration  aggres- 
sively. If  the  expression  of  his  aggressions 
is  inhibited  because  they  conflict  with  his 
social  training,  the  aggressiveness  may  be 
attributed  to  others.  This  leads  a  man  to 
suspect  his  associates'  motives  and  actions 
and,  at  the  extreme,  to  have  delusions  that 
he  is  the  victim  of  persecution  or  conspir- 
acy. This  kind  of  adjustment  usually  in- 
cludes aspects  of  t^vo  mechanisms;  it  is  ra- 
tionalization in  that  it  excuses  failure,  but 
it  is  also  projection  in  attributing  self-ag- 
gression to  the  external  -world. 

Regression 

Another  form  of  escape  from  difficulties 
is  to  revert  to  solutions  that  were  satisfying 
at  an  earlier  period  of  personal  develop 
ment.  Such  return  to  the  past  has  been 
termed  regression.  Its  clearest  manifesta- 
tions are  seen  in  the  behavior  of  young 
children.  'When  thwarted,  they  tend  to 
regress  to  obviously  infantile  responses.  A 
two-year-old   who   no   longer  gets   his   par- 


522 


Personal  Adjustmeni 


ents'  undivided  attention  because  of  a  new 
baby  in  the  family  may  revert  to  crawling 
instead  of  walking  or  may  demand  that  he 
be  fed  by  hand.  A  number  of  experiments 
with  animals  have  shown  that  they  tend  to 
return  to  earlier  and  simpler  types  of  re- 
sponses to  problem  situations,  even  though 
these  are  ineffective,  when  blocked  by  an 
excessive  increase  in  the  difficulty  of  the 
adjustment  required.  Experiments  with 
children  have  shown  that  the  quality  of 
their  plav  is  likely  to  deteriorate  to  that 
typical  of  younger  ages  when  they  are 
thwarted  by  being  deprived  of  attractive 
toys.  Normal  regression  in  adults  is  shown 
by  the  tendencies  of  men  to  revert  to  ado- 
lescent boisterousness  at  conventions  and 
reunions.  Every  college  has  alumni  who 
are  perennial  undergraduates,  seeking  to 
recaptme  the  most  satisfying  period  that 
came  into  their  lives  before  fully  adult  re- 
sponsibilities fell  upon  them. 

In  describing  more  serious  maladjust- 
ments, the  concept  of  regression  is  some- 
times used  in  a  broader  sense,  to  imply  a 
simplification  of  response  to  more  rudi- 
mentary le\els.  An  example  is  the  psycho- 
logical invalid,  who  takes  to  bed  in  order 
to  escape  a  need  for  adjustment,  demand- 
ing that  others  care  for  all  his  needs.  Re- 
gression is  even  more  striking  in  the  serious 
mental  disorders  of  the  withdrawing  types, 
in  which  a  patient  may  long  remain  mute 
and  unresponsive  to  adjustive  demands. 
In  this  second  sense,  all  maladjustments 
are  somewhat  regressi\e  in  that  they  are  re- 
treats from  the  intricate  adaptations  re- 
quired in  dealing  effectively  with  reality. 
The  two  meanings  of  regression  must  not 
be  confused.  A  withdrawn  adjustment  is 
oversimplified  but  it  is  not  truly  childlike, 
for  normal  children  are  active  and  outgo- 
ing in  their  behavior. 


Sublimation 

Since  everyone  is  thwarted  to  some  ex- 
tent and  yet  is  able  to  make  a  passably  suc- 
cessful adjustment  to  life,  there  must  be  a 
mechanism  or  means  of  substitute  satisfac- 
tion that  is  healthful.  Perhaps  it  is  suffi- 
cient to  refer  to  such  solutions  merely  as 
good  adjustments,  but  they  are  often  desig- 
nated sublimations.  A  sublimation  is  a 
substitute  response  that  is  socially  accept- 
able and  does  not  interfere  appreciably 
with  the  satisfaction  of  other  motives.  Ex- 
amples of  sublimation  can  be  found  in  all 
persons'  lives.  Aggressive  responses  to 
thwarting  are  sublimated  into  interests  in 
participant  and  spectator  sports,  especially 
those  requiring  physical  force  such  as  box- 
ing or  football.  Anxieties  concerning  in- 
feriorities may  find  constructive  reduction 
in  drives  leading  to  achievement  in  busi- 
ness, professions  or  the  arts.  Thwartetl 
needs  to  'mother'  people  and  to  ha\e  them 
dependent  may  be  sublimated  into  work  in 
child  welfare  or  social  welfare. 

Although  sublimations  are  common  ad- 
justments, it  is  a  mistake  to  suppose  that 
they  underlie  all  achievements.  This  hy- 
pothesis would  assume  that  all  personali- 
ties are  essentially  sick  or  inadequate,  and 
that  even  good  adjustment  is  a  'mechanism' 
or  remedial  measure  to  alleviate  an  infirm- 
ity. Most  well-balanced  adjustments  are 
direct  responses  to  motives.  There  is  some 
experimental  evidence  that  achievement  is 
not  usually  due  to  sublimation.  For  exam- 
ple, it  is  often  assumed  that  creativeness  in 
the  arts  is  a  sublimation  of  sex  motives. 
If  this  were  true,  the  need  for  sexual  grati- 
fication AvoiUd  be  lessened  in  creative  indi- 
viduals. One  study,  of  a  group  of  crea- 
tively superior  single  men,  found  no  evi- 
dence that  their  normal  sex  needs  were  re- 


Conflict 


523 


placed   by   their  outlets   in   iiU(;llcctual   or      icr  ol   the  person   and   the   environmental 
artistic  achievements.  forces  acting  on  him. 


CONFLICT 

Among'  the  various  types  of  thwarting, 
conHi(t  has  the  broadest  signihcance,  espe- 
cially in  contributing  to  an  iniderstanding 
of  the  more  disabling  maladjustments. 
Conflict  has  already  been  defined  as  a  state 
of  affairs  in  which  two  or  more  incom- 
patible behavior  trends  are  evoked  that 
cannot  be  satisfied  fully  at  the  same  time. 
In  recent  years  psychology  has  given 
much  attention  to  the  problem  of  conflict 
by  making  theoretical  analyses  of  various 
types  of  conflict,  by  performing  experi- 
ments on  conflict  behavior  and  by  studying 
its  effects  in  men  and  animals. 

An  Analysis  of  Conflicts 

Conflict  can  be  described  in  terms  of  the 
interactions  between  an  individual  and  his 
environment.  This  is  the  field  theory  of 
behavior,  developed  chiefly  by  Kurt  Lewin 
and  his  associates,  and  named  by  analogy 
to  a  theory  of  electricity  and  magnetism. 
It  emphasizes  the  observation  that  behavior 
does  not  depend  on  the  organism  alone  or 
on  the  environment  alone,  but  on  what 
goes  on  between  the  two. 

Tendencies  to  behavior  may  be  repre- 
sented by  vectors,  which  show  the  direction 
and  strength  of  the  individual's  striving. 
Most  impulses  can  be  described  as  directed 
toward  or  away  from  an  environmental 
event.  This  is  stated  in  terms  of  valences, 
of  which  positive  (+)  valences  are  tenden- 
cies to  approach,  and  negative  (-)  valences 
are  tendencies  to  withdraw  and  avoid  (Fig. 
234).  It  will  be  seen  that  valences  and 
vectors  are  both  field  phenomena,  and  can 
be  defined  only  in  terms  of  both  the  charac- 


Approach-Approoch  Conflicts 

Field  theory  shows  that  there  can  be 
only  three  basic  types  of  conflict.  A  lyfjc  1 
conflict  is  between  two  positive  valences 
that  are  about  equal  in  strength.  Ihis  is 
an  approach-approach  conflict  (Fig.  2;1t). 
A  child  may  have  to  choose  between  read- 
ing an  interesting  book  and  going  out  to 


G> 


G> 


0 


FIGURE    234.       \ALENCES    AND    VECTORi 

III  A,  the  interaction  of  the  individual  (I)  and  the 
situation  (S)  may  be  described  as  a  positive  valence, 
in  B  as  a  negative  valence.     [After  K.  Lewin.] 

play  football.  A  young  man  mav  have  a 
conflict  of  this  type  when  he  can  choose 
freely  between  two  offered  positions,  or  a 
young  woman  when  faced  with  a  decision 
between  two  equally  qualified  suitors. 

Theoretical,  experimental  and  practical 
observations  all  show  that  approach-ap- 
proach conflicts  rarely  result  in  distiub- 
ances  of  behavior.  For  one  reason,  the  ab- 
sence of  any  negative  valences  means  the 
lack  of  fear,  anxiety  or  restraint,  which  arc 
basic  to  maladjustment.  Also,  once  a  per- 
son starts  in  the  direction  of  one  alterna- 
tive, its  nearness  adds  to  its  strength,  so 
that  the  vectors  are  no  longer  equal  and  a 
choice  is  found  to  have  been  made.  The- 
ory indicates  that  some  vacillation  mav 
take  place,  however.  If  the  person  attains 
one  goal,  and  if  then  satiation  reduces  the 
strength  of  the  drive  toward  that  goal,  the 
opposite  vector  is  now  stronger  and  will  at- 


524 


Personal  Adjusfmeni 


tract.  After  tiring  of  the  ball  game,  the 
boy  returns  to  his  book.  Relinquished  jobs 
and  lovers  sometimes  seem  more  attractive 
in  retrospect,  and  the  grass  is  greener  on 
the  other  side  of  the  fence. 


+  S. 


<z> 


+  s. 


+  s, 


+  s, 


+  s. 


FIGURE    235.       APPROACH-APPROACH    CONFI  ICTS: 
T\PE    1 

The  approach -approach  conflict,  A,  is  solved  eas- 
ily. If  some  \ariatioii  in  behavior  brings  the  indi- 
vidual a  little  closer,  physically  or  psychologically, 
to  the  attracting  situation  5^  and  away  from  the 
other  attracting  situation  So,  the  vector  for  Sj  is  in- 
creased in  strength  because  of  the  decreased  dis- 
tance, and  the  conflict  is  resolved  by  the  individ- 
ual's going  in  that  direction  (B).  In  C,  satiation 
of  the  Si  motive  may  weaken  its  vector.  The  indi- 
vidual then  vacillates  to  the  Sg  choice.  The  dotted 
vectors  indicate  actual  movements  and  the  solid 
vectors  motivational   forces.     [After  K.  Lewin.l 

Avoidance-Avoidance  Conflicts 

Conflicts  of  Type  2  are  evoked  by  two 
negative  valences.  Both  tendencies  are  to 
retreat  from  or  to  avoid  something;  this 
is  being  caught  between  the  devil  and  the 
deep  sea  (Fig.  236).  A  youngster  may  want 
to  avoid  doing  an  unpleasant  task  and  also 
want  to  escape  the  threat  of  parental  pun- 
ishment for  his  failure  to  perform.  The 
soldier  in  battle  has  a  conflict  between  his 
need  to  run  away  and  save  his  skin  and  his 
need  to  avoid  being  scorned  as  a  coward. 
The   most   usual   solution   of   an   avoid- 


ance-avoidance conflict  is  leaiimg  the  field 
that  is  to  say,  taking  a  third  course  of  ac- 
tion which  avoids  both  the  threatening  al- 
ternati\es.  That  may  be  regarded  as  a  re- 
sponse toward  the  resultant  of  the  two  vec- 
tors, as  suggested  by  B  of  Fig.  236.  Most 
escape  mechanisms  are  methods  for  leaving 
the  field.  The  boy  just  cited  may  develop 
a  headache,  thereby  avoiding  both  the  task 
and  parental  displeasure.  Or  he  may  ap- 
parently work  at  the  job,  but  really  be  en- 
gaged in  daydreaming,  which  is  a  common 
way  to  escape  unpleasant  alternatives.     On 


-s, 

+  s, 

A 

■o- 


-s. 


-s. 


i L 


J i 


-s, 


<Z> 


-s. 


1     r 


1     r 


FIG.    2^6.       AVOIDANCE-AVOIDANCE    CONFLICTS: 
TYPE    2 

The  usual  response  to  a  1  ypc  2  conflici  in  .7  is 
to  leave  the  field,  as  shown  by  B.  If  niateiial  or 
])sychological  barriers  prevent  this,  as  in  C,  the  in- 
dividual shows  vacillating  behavior  (two  dotted  vec- 
tors) at  the  choice  point,  and  has  unreduced  ten- 
sion.    [.\fter  K.  Lewin.] 

the  other  hand,  psychological,  social  or 
physical  boundaries  may  keep  the  individ- 
ual from  leaving  the  field.  Common 
boundaries  include  his  social  values  ac- 
quired through  learning  ('conscience')  and 


Conflict 


525 


various  other  more  dirccL  social  picssurcs. 
If  unable  to  escape  the  dilemma,  the  indi- 
vidual may  he  forced  to  solve  it  fjy  strength- 
ening or  weakening  one  of  the  vectors.  I*or 
example,  he  may  put  off  a  disagreeable  task 
until  social  pressure  mounts  so  high  that 
the  penalty  for  nonperformance  is  greater 
than  the  unpleasantness  of  the  duty.  This 
pattern  is  often  seen  in  students  who  put 
off  studying  until  they  are  forced  by  the  im- 
minence of  examinations. 

If  a  person  cannot  solve  an  avoidance- 
avoidance  conflict  at  all,  he  remains  in  a 
vacillating,  insecure  condition,  usually  with 
a  strong  emotional  tone  induced  by  the 
unremoved  needs  for  escape  (C  of  Fig.  236). 
He  feels  tension,  which  is  often  partially 
reduced  by  defense  or  escape  mechanisms 
not  directly  related  to  the  original  conflict. 
If  even  this  means  of  adjustment  fails,  the 
result  is  unreduced  tension  with  its  symp- 
toms of  anxiety,  'nervousness'  and  the  like. 

Approach-Avoidance  Conflicts 

The  remaining  variety  of  conflict.  Type 
3,  is  seen  when  a  situation  elicits  both  ap- 
proaching and  avoiding  tendencies  simul- 
taneously (Fig.  237).  The  antagonistic 
valences  may  lie  in  the  relationship  of  the 
individual  to  the  situation,  as  for  example, 
when  a  child  wants  to  play  football  but  is 
afraid  of  being  hurt,  or  when  he  both  loves 
and  fears  his  mother  (A  of  the  figure).  In 
other  instances,  one  valence  may  be  'in- 
duced' by  a  psychological  field  set  up  by 
another  person  or  by  a  cultural  group. 
Thus,  a  child  may  w^ant  to  take  a  forbidden 
piece  of  candy,  but  the  parent's  watchful 
eye  surrounds  the  dish  with  negative  val- 
ences (B  of  the  figure).  The  opposite  can 
also  be  observed,  as  when  a  person  is  in 
conflict  toward  an  irksome  duty,  because 
it  lies  in  a  positive  field  representing  the 


prospective  ajjproval  ol  jjarents,  teachers  or 
associates. 

Many  serious  conflicts  that  lead  to  sub- 
stitute adjustments  can  be  described  in 
terms  of  the  approach-avoidance  situation. 
Feelings  of  personal  inadcfjuacy  evoke  this 
type  of  conflict.  The  individual  is  strongly 
motivated  to  achieve  prestige  and  approval, 
but  also  has  a  fear  of  effort  or  competition 


^0: 


GX 


-   +.S 


eV^A 


FIG.     237.       APPROACH-AVOIDANCE    CONFLICTS: 
TYPE    3 

An  unresolved  approach-avoidance  conflict  in  A 
results  only  in  unreduced  tension,  since  leaving  the 
field  is  not  a  solution.  In  manv  instances  this  tvpe 
of  conflict  results  from  induced  valences,  as  shown 
in  B,  where  a  parent  (P)  forbids  an  approach,  sur- 
rounding the  desired  goal  (+5)  with  an  atmosphere 
of  negative  valences,     [.^fter  K.  Lewin.] 

because  of  his  disbelief  in  his  own  compe- 
tence. He  may  want  to  act  aggressively 
against  persons  who  thwart  him  yet  be  in- 
hibited by  fear  of  retaliation.  Most  serious 
of  all  is  a  conflict  based  on  responses  of 
love  and  fear,  or  of  dependence  and  resent- 
ment, directed  against  the  same  person. 

Approach-avoidance  conflicts  cannot  be 
solved  by  leaving  the  field,  because  tlie  im- 
pulse for  approach  (positive  valence)  keeps 
the  individual  from  retreating  too  far. 
The  person  in  conflict  thus  tends  to  re- 
main at  a  point  of  vacillating  equilibrium, 
at   which    the    strengths    of    tlie    opposing 


526 


Personal  Adjustment 


forces  are  about  equal.  His  impulses  do 
not  cancel  each  other,  but  leave  him  in  a 
continued  state  of  unreduced  tension. 
More  than  either  of  the  other  two  types, 
approach-avoidance  conflicts  are  likely  to 
underlie  either  inferior  adjustment  mech- 
anisms or  unreduced  anxiety. 

EXPERIMENTS    ON    CONFLICT 

The  study  of  conflicts  can  be  explored 
experimentally  by  exposing  subjects  to  sit- 
uations in  which  two  opposed  needs  are 
activated.  Such  experiments  add  to  the 
knowledge  that  can  be  obtained  from  the 
clinical  study  of  individuals,  because  of 
greater  precision  in  the  arrangement  of  the 
situations,  in  the  control  of  other  in- 
fluences, and  in  the  tabulation  of  the  re- 
sults. Some  experiments  on  minor  con- 
flicts have  been  done  with  human  beings  as 
subjects,  but  the  most  revealing  studies 
have  used  animals.  You  may  not,  merely 
for  scientific  purposes,  create  neuroses  in 
human  beings,  but  human  welfare  justifies 
the  induction  of  neurosis  in  a  cat  or  a 
sheep. 

Conflicts  in  Cats 

In  an  extensive  series  of  experiments 
with  cats,  an  investigator  has  studied  the 
effects  of  conflict  between  a  feeding  re- 
sponse and  an  avoiding  reaction  to  a  fear- 
provoking  stimulus.  Hungry  cats,  placed 
in  the  apparatus  (Fig.  238),  learned  to  go 
to  the  feeding  box  when  a  light-and-buzzer 
signal  was  given.  After  this  response  was 
established,  conflict  was  introduced  by  giv- 
ing the  cat  a  strong  blast  from  a  com- 
pressed air  nozzle  near  the  feeding  box,  or 
an  electric  shock  from  the  floor  grid,  or 
both.  This  was  an  approach-avoidance,  a 
Type  3,  conflict. 


The  effects  of  the  experimentally  in- 
duced conflict  were  striking.  Typically, 
cats  that  were  normally  quiet  showed  an 
inhibition  of  feeding  responses,  signs  of 
emotional  reaction  such  as  the  erection  of 
hairs  and  the  dilation  of  the  pupils  and  ex- 
tremely restless  and  agitated  behavior  that 
might  properly  be  interpreted  as  evidence 
of   tension  and   anxiety.     Cats    that   were 


1    \    r 
I    I    I 


-L-^l 


I    I    I    ! 


I   I    I 


[\A    1 


I        I 
I       I        I 

I     !     I 


I  I 
I  I 
I  I 
I     I 


1  1 


1  1 


G   I 


FIG.    238.      APPARATUS    FOR   SIUDVING   CONFLICT   IN 
CATS 

The  cat  is  iiitroduced  through  tlie  door  D,  and 
learns  to  feed  at  the  food  box  F  when  light  L  and 
buzzer  signal  B  are  given.  Conflict  is  introduced 
by  stimulating  the  cat  with  an  air  blast  A  while  he 
is  feeding,  or  by  an  electric  shock  applied  by  the 
floor  grid  G,  or  by  both.  [After  J.  H.  ^fasse^man, 
Behavior  and  neurosis,  Chicago  University  Press, 
1943.  Plate  IV.] 

rather  active  and  excitable  in  their  normal 
condition  tended  to  become  passive  and 
immobile,  remaining  in  set  postures  over 
periods  of  ten  to  twenty  minutes  even  Avhile 
receiving  electric  shocks.  Cats  also  de\el- 
oped  'phobic'  reactions,  cowering  and  show- 
ing signs  of  fear  and  avoidance  when  the 
feeding  signals  were  given,  even  when  the 
air  blast  or  shock  in  a  particular  trial  was 
being  omitted.  They  showed  the  defense 
or  tension  reduction  mechanisms  in  some 
cases,  especially  in  continued  cleaning,  lick- 
ing and  preening  of  their  fur. 

The  most  striking  findings  of  this  series 


Experimental  Conflict 


527 


of  experiments  concerned  tlic  duration  and 
^generalization  of  the  eflects  of  conflict. 
Conflicts  set  up  by  only  two  or  three  repe- 
titions of  the  training  situation  remained 
unmodified  for  months.  Also,  the  cats'  be- 
havior outside  the  exj^erimental  box  was 
profoundly  affected  in  almost  every  in- 
stance. Some  cats  who  had  been  made 
'neurotic'  starved  themselves  imtil  they 
had  to  be  force-fed.  Others  became  either 
excessively  wild,  or  timid,  or  fearful,  or 
aggressive.  It  was  evident  that  tiie  experi- 
mental conflict  made  profound  and  endur- 
ing changes  in  their  ability  to  make  their 
usual  life  adjustments. 

Experimental  Neurosis 

Another  experimental  approach  to  the 
study  of  conflict  was  first  made  in  Pavlov's 
laboratories  by  use  of  the  conditioned  re- 
sponse technique.  Many  experimenters 
have  made  further  observations  by  this 
method,  with  dogs,  sheep,  pigs,  rats  and 
even  with  a  few  human  subjects. 

Most  studies  set  up  conflicts  by  requiring 
excessively  fine  discriminations  of  condi- 
tioned responses.  In  the  first  classic  ex- 
periment, a  dog  was  trained  to  salivate 
when  a  perfect  circle  was  shown  and  not  to 
salivate  when  the  visual  stimulus  was  an 
ellipse.  Then  the  dog  was  given  a  series  of 
ellipses,  which  approached  nearer  and 
nearer  to  the  form  of  the  circle.  That 
produced  the  significant  j^henomenon.  In- 
stead of  simply  failing  in  discrimination, 
the  dog  'broke  down.'  He  showed  fren- 
zied emotional  behavior,  salivated  for  any 
stimulus  even  remotely  connected  with  the 
experiment  such  as  the  sight  of  the  experi- 
menter and  was  unable  to  make  easy  dis- 
criminations that  he  formerly  made  with- 
out difficulty.  He  had  developed  what  is 
now  called  an  experimoiial  ururosis. 


It  is  evident  that  experimental  neurosis 
can  be  regarded  as  a  result  of  a  conflict  be- 
tween excitatory  and  inhibitory  tendencies 
evoked  by  the  same  situation.  It  is  essen- 
tially a  Type  3  conflict.  Many  studies  have 
shown  that  not  all  animals  are  ecjually  sus- 
ceptible to  this  breakdown,  some  appearing 
to  have  higher  conflict  tolerance  than 
others.  Among  those  that  do  succumb, 
there  is  a  tendency  for  formerly  placid  ani- 
mals to  show  an  excited  neurosis,  and  for 
active  ones  to  be  overinhibited,  just  as  hap 
pened  with  the  cats.  An  experimental  neu- 
rosis spreads  to  include  the  animals'  be- 
havior out  of  the  laboratory,  and  it  lasts 
for  a  long  time.  One  sheep  and  one  dog 
remained  'neurotic'  for  the  rest  of  their 
lives,  periods  of  thirteen  and  ten  yeais  re- 
spectively. One  very  important  finding 
was  that  sheep,  which  were  free  to  move 
about  in  a  pen  during  the  experiment 
could  not  be  'broken  down,'  whereas  those 
strapped  in  the  conditioning  apparatus 
could  be.  The  former  were  able  to  lea\e 
the  field  and  escape  the  impact  of  the  con- 
flict.   (Compare  B  with  C  in  Fig.  236.) 

Effects  of  Conflict 

These  experiments  on  conflict  have  made 
an  invaluable  contribution  to  the  under- 
standing of  human  adjustments.  Conflicts 
are  not  only  the  precipitating  causes  of 
adjustive  difficulties,  but  also  have  a  rela- 
tionship to  the  ability  to  adjust  when  con- 
fronted by  new  problems.  The  experi- 
ments shoA\'  that  strong,  unsohed,  early  con- 
flicts make  enduring  changes  in  personality, 
and  case  studies  of  people  confirm  these 
findings.  If  a  person  persists  over  a  period 
of  years  in  making  inferior,  excessi\  ely  sub- 
stituted or  nonadjusti^•e  responses,  it  is  very 
probable  that  earlier  disabling  influences 
have  reduced  his  general  ability  to  adjust. 


528 


Personal  Adjustment 


COMMON    SOURCES    OF 
CONFLICT 

In  infancy  and  childhood  the  family, 
being  the  chief  social  background  of  the 
individual,  is  the  scene  of  most  of  these 
conflicts.  Later  sex  comes  to  determine 
many  of  the  conflicts,  for  the  reason  that 
the  demands  of  our  culture  have  not  been 
well  adjusted  to  the  sexual  needs  of  the 
individual.  And  there  are  many  other 
ways  in  which  cultiual  values  can  give 
rise  to  conflicts. 

Family  Conflicts 

The  many  interactions  of  personalities 
that  take  place  within  the  family  are  of 
the  greatest  significance  in  determining  re- 
actions to  conflict,  because  they  are  the 
most  perA-asive  and  intimate  and  are  highly 
motivated.  A  child's  relations  with  mem- 
bers of  his  family,  moreover,  mold  his  ad- 
justive  behavior  when  he  is  inmiature  and 
least  able  to  cope  with  difficulties  inde- 
pendently. 

Conflicts  of  insecurity  are  among  the 
most  common  and,  when  severe,  are  among 
the  most  disabling.  Insecurity  results  from 
a  conflict  between  dependence  and  fear.  A 
child  is  inevitably  dependent  on  his  par- 
ents not  only  for  food  and  shelter  but  also 
for  protection,  approval  and  affection. 
The  urgent  nature  of  these  latter  needs  has 
been  recognized  more  fully  in  recent  years. 
If  parents  are  cold,  disinterested  or  ex- 
cessi\ely  demanding,  or  if  they  use  scolding 
and  punishment  as  the  major  technique  for 
securing  the  child's  compliance  with  do- 
mestic routines,  the  result,  from  the  child's 
point  of  view,  is  rejection.  Parents,  of 
course,  seldom  reject  a  child  intentionally 
or  consciously,  but  the  child  feels  rejected 
because  he  gets  from  them  so  much  less 
than  he  needs.     There  arc  many  reasons 


^vhy  parents  fall  short  of  their  children's 
necessities.  For  some  parents  a  child  rep- 
resents a  frustration  of  their  own  needs,  in 
that  the  care  of  an  infant  may  prevent  them 
from  having  their  desired  social  recreations 
or.  when  both  parents  have  professional  am- 
bitions, a  child  may  interfere  with  the  career 
of  one  of  them— usually  the  mother.  If  the 
parents  feel  'unconsciously'  guilty  about 
their  relation  to  a  child,  they  may  project 
their  guilt  upon  the  child,  finding  fault  with 
it  or  becoming  angry  with  it.  Or  they  may 
project  other  maladjustments  of  their  own 
upon  their  children.  Another  difficulty 
arises  when  parents  who  ha\'c  a  strong  need 
for  social  approval  feel  that  their  child's  bad 
manners  reflect  adversely  on  them.  They 
do  not  consciously  admit  the  blame,  but 
project  it  upon  the  child  by  nagging  or 
punishing  him.  Rejecting  parents  defend 
their  treatment  of  their  children  by  ration- 
alizations, making  themselves  believe  that 
their  actions  are  all  for  the  child's  good. 
So  closely  are  the  personalities  of  children 
dependent  in  these  ways  upon  the  personal- 
ities of  their  parents  that  a  child  guidance 
clinic,  when  asked  to  advise  about  a  prob- 
lem child,  always  studies  the  parents  too. 
A  problem  child  at  once  creates  the  pre- 
sumption that  there  may  also  be  a  problem 
parent  needing  attention.  In  line  with  this 
reasoning,  parents  have  been  sentenced  by 
the  court  for  the  delinquency  of  their  chil- 
dren. 

The  relationships  of  a  cliild  with  his 
brothers  or  sisters  may  also  be  the  basis  of 
conflicts  which  arise  from  sibling  rivalry. 
Children  in  the  family  are  always  competi- 
tors, in  some  degiee,  for  the  attention  and 
love  of  their  parents.  If  one  child  succeeds 
more  than  another,  because  he  has  more 
approved  traits  or  because  the  parents  are 
'partial'  to  him,  the  result  may  be  the 
equi\alent  of  rejection  for  the  less  favored 


Family  and  Sex  Conflicis 


529 


youiigstci.  Invidious  (omparisoiis  o(  diil 
dren  with  respccl  to.  their  ititclhgcruc, 
willingness,  strength  or  appearance  may 
cause  conflicts  of  inferiority. 

In  our  culture,  especially  in  urban  fami- 
lies of  the  higher  economic  levels,  parental 
overprotection  is  a  common  source  of  con- 
flicts. It  may  take  either  of  two  forms. 
Parental  dominance  is  found  when  the 
parents  refuse  to  permit  the  child  to  bear 
responsibility  for  any  decision  or  duty. 
Everything  is  done  for  him,  because  adults 
can  carry  out  the  tasks  more  quickly  or 
cffi(  iently  than  a  child.  The  other  form  is 
parental  .sithmissiveness.  The  child  is  per- 
niitted  to  do  as  he  wishes.  The  parents  not 
only  gratify  every  need  that  he  expresses, 
but  protect  him  from  the  consequences  of 
his  immature  judgment.  With  either  type 
of  overprotection,  the  child  may  show  no 
signs  of  conflict  during  the  earlier  years 
that  are  normally  spent  in  the  home. 
When  he  begins  to  have  social  contacts 
with  other  children,  or  when  he  starts  at- 
tendance at  school,  the  trouble  is  likely  to 
begin.  The  overprotected  child  lacks  inde- 
pendent social  skills,  and  his  demand  for 
special  consideration  may  lead  to  his  perse- 
cution by  his  contemporaries.  He  is  then 
likely  to  develop  defense  or  escape  mech- 
anisms, or  to  regress  to  the  protection  of  his 
family,  leaving  an  even  more  difficult  read- 
justment to  be  made  in  his  adolescent  or 
adult  years. 

Sex  Conflicts 

The  sexual  functions  are  often  causes  of 
severe  conflicts  because  of  the  way  they  are 
regarded  in  our  culture.  Conflict  is  not  in- 
herent in  sex,  as  studies  of  other  cultures 
show  very  clearly.  There  are,  however,  a 
number  of  reasons  why  sex  underlies  so 
much  conflict  in  our  own  particular  pat- 
tern of  civilization.    One  reason  is  foimd  in 


(lie  Ifiug  lime  inicrval  that  separates  physi- 
ological and  sofial  maturity.  Young  men 
and  women  aie  adults  sexually  from  five 
lo  fifteen  years  before  they  can  marry  and 
support  themselves  and  a  family.  This 
period  of  Irustrarion  is  absent  in  primitive 
cultures  in  which  occupational  and  educa- 
tional demands  for  marriage  are  simpler. 
y\n  even  more  important  reason  is  the  cul- 
tural standard  that  holds  all  sex  desires, 
thoughts  or  acts  to  be  indecent  or  guilty, 
and  forbids  open  discussion  or  expression 
of  them.  Many  parents  effectively  condi- 
tion their  children  to  regard  anything  sex- 
ual as  clandestine  and  guilty.  When  sex 
drives  occur,  a  conflict  between  the  sexual 
need  and  the  sense  of  guilt  is  likely.  From 
a  broad  social  point  of  view,  the  repression 
of  sex  has  served  the  functions  of  reducing 
illegitimacy  and  the  spread  of  venereal  dis- 
ease. From  the  standpoint  of  individual 
adjustment,  it  often  achieves  this  end  at 
the  cost  of  conflict  and  anxietv. 

Casual  sexual  relations  among  young  un- 
married persons  are  not,  however,  a  good 
solution  of  the  sex  problem.  The  anxieties 
caused  by  the  conflict  with  early  training 
and  Avith  the  dominant  cidtural  ethics  pro- 
duce tensions  that  are  greater  than  those  re- 
lieved. Also,  casual  relationships  are  a 
poor  substitute  for  the  more  broadly  satis- 
fying condition  of  marriage,  A\hich  fidfills 
many  needs  besides  the  needs  of  sex.  In 
general,  it  is  the  experience  of  psycholog- 
ical consultants  Uiat  young  people  who  are 
promiscuous  create  more  conflicts  than  they 
solve.  Sometimes  the  exaggerated  sex  needs 
are  themselves  substitutes  for  motives  to 
prove  one's  manliness  or  attractiveness,  a 
need  which  can  be  satisfied  directly  by  odier 
acti\ities.  In  other  instances,  exaggerated 
l)eha\  ior  is  evidence  of  an  intercultural  con- 
flict, in  Avhich  a  smaller  'liberated"  group 


530 


Personal  Adjusfment 


feels  a  need  to  show  iis  aggressive  defiance 
of  the  larger  culture  by  assauUing  its 
standards. 

It  is  the  experience  of  many  well-adjusted 
young  peojale  that  sex  desires  can  be  recog- 
nized as  normal,  ^vithout  fear  or  shame,  but 
can  be  controlled  by  constructive  substitute 
adjustments,  chiefly  of  the  type  of  sublima- 
tion. Among  the  sublimations  that  reduce 
sex  needs  are  well-motivated  work,  ade- 
quate recreation  and  amusement,  and  op- 
portunities for  social  contacts  Avith  the  op- 
posite sex.  No  psychological  harm  comes 
from  sexual  abstinence  itself  during  the 
adolescent  or  young  adult  years,  whereas 
disabling  conflicts  can  indeed  be  induced 
by  fears  about  the  sex  function,  fears  that 
may  arise  either  in  connection  with  sex 
fulfillment  or  with  nonfulfillment. 

Many  yoimg  persons  ha\e  grave  conflicts 
over  autoerotic  practices  (masturbation). 
This  method  of  relieving  sex  tension  is 
used  by  almost  all  adolescent  boys  and  by 
many  girls,  and  is  often  continued  into 
the  young  adult  years.  Physiologically  it 
is  harmless  and  does  not  cause  insanity  or 
loss  of  virility,  as  are  the  common  miscon- 
ceptions. It  does,  however,  involve  psycho- 
logical difficulties.  Most  persons  have  been 
.so  thoroughly  taught  that  the  act  is  harm- 
ful and  wicked  that  they  have  strong  feel- 
ings of  guilt  about  masturbation.  Also, 
masturbation  is  ridiculed  by  young  people 
themselves,  and  one  who  is  detected  is  sub- 
jected to  humiliation.  Guilt  induced  by 
masturbation  does  not  reduce  the  practice, 
for  the  increased  tension  often  causes  a 
greater  need  for  relief.  Psychological  coun- 
selors have  found  that  the  most  eff^ective 
treatment  for  masturbation  anxieties  is  to 
reduce  the  feelings  of  unworthiness  and  to 
encoiuage  sublimations  tiiat  satisfy  social 
motives  broadh. 


Other  Cultural  Conflicts 

The  pattern  of  values  that  exists  in  our 
c ultme  is  responsible  for  a  number  of  other 
conflicts  that  may  ojjerate  from  childhood 
on  through  maturity.  One  of  them  is  the 
conflict  between  the  learned  needs  for 
competithie  achievement  and  for  coopera- 
tion and  submission.  From  an  early  age 
rewards  of  approval  by  parents  and  com 
munity  are  gi\en  for  competitive  success  in 
school  marks,  in  sports  and,  later,  in  voca- 
tions. As  a  result,  Americans  learn  to 
place  a  high  evaluation  on  assertion  and 
aggressiveness.  At  the  same  time  an  oppo- 
site set  of  values  is  taught  equally  vigor- 
ously. We  learn  to  try  to  be  popular,  to 
be  liked  and  to  be  appreciated.  This  de- 
mand places  a  strong  emphasis  on  our 
needs  for  the  appro\al  and  affection  of 
others.  The  conflict  between  these  two 
tendencies  is  one  of  the  most  connnon 
causes  of  tension  and  of  substitute  adjust- 
ments. It  has  been  described  as  basic  to 
"the  neurotic  personality  of  our  time." 

A  somewhat  related  conflict,  peculiar  to 
the  American  culture  and  to  others  like  it, 
arises  from  the  need  for  status.  Surveys  of 
the  occupational  preferences  of  high  school 
students  show  that  a  large  majority  want 
to  enter  the  professions  and  white-collar 
occupations.  They  want  to  become  physi- 
cians, lawyers,  engineers  and  owners  of 
businesses,  in  a  proportion  that  is  beyond 
their  possible  realization.  In  a  few  ycar."^ 
most  of  these  would-be  professional  men 
will  be  factory  workers  and  clerks.  Thif 
conflict  does  not  occur  in  an  old  culture, 
in  which  a  son  expects  to  follow  his  father's 
occupation,  or  at  the  best  not  to  rise  much 
above  his  level.  The  good  aspects  of  free 
opportunity  are  to  some  extent  counterbal- 
anced by  these  feelings  of  frustration  and 
failure.     Status  conflicts  are  likely  to  con- 


Psychoneuroses 


531 


liiuu;  throughout  many  people's  lives,  as 
they  try  to  equal  or  excel  their  neighhors 
in  houses,  automobiles,  ( lollies,  entertain- 
ment and  many  other  things.  These  con- 
flicts underlie  many  financial  worries  and 
not  a  little  of  domestic  discord. 

Another  variety  of  cultural  conflict  in 
America  is  found  in  the  confusion  of  group 
loyalties  and  group  identifications.  This 
conflict  is  very  evident  in  the  children  of 
inmiigrants,  whose  parents  and  whose  own 
early  home  training  represent  one  culture, 
and  whose  schooling  and  outside  experi- 
ences are  in  another.  Insecurity  and  anx- 
iety often  ensue.  They  may  be  reduced  by 
aggressive  defenses  that  relieve  tensions  but 
hinder  social  adjustment.  (On  conflict,  see 
p.  570,  and  on  group  identification,  see 
pp.  598  f.) 

PSYCHONEU  ROSES 

If  an  individual's  adjustments  are  so  in- 
adequate that  they  cause  him  chronic  dis- 
comfort, and  interfere  markedly  with  his 
efficiency  in  ordinary  living,  they  may  be 
characterized  as  psychoneurotic  or  neurotic. 
As  used  today,  these  two  terms  are  synony- 
mous. The  psychoneuroses  are  not  specific 
entities  or  diseases,  but  represent  a  certain 
range  of  severity  in  the  continuum  of  mal- 
adjustments. They  are  more  disabling 
than  the  reactions  that  can  be  classed  as 
normal,  but  are  less  so  than  the  psychoses, 
which  are  the  most  serious  form  of  mental 
disturbance  and  will  be  described  presently. 
Since  there  is  a  continuous  gradation  of 
quality  of  adjustment  from  the  best-bal- 
anced person  to  the  most  obviously  dis- 
turbed, no  exact  line  can  be  drawn  to  sep- 
arate normality  from  neurosis.  Some 
writers  have  tended  to  use  the  term  neu- 
rotic to  characterize  all  adjustments  short 
of  the  most  excellent.    There  is  even  a  "be- 


glad-you'ie-neurotic"  school  o(  ihouglil 
which  goes  farther  to  ascribe  all  driving 
energies,  and  hence  all  achievement,  to 
neurosis.  According  to  this  conception, 
everyone  is  neurotic  at  times,  and  many  of 
us  are  neurotic  most  of  the  time,  and  the 
activity  which  builds  civilization  gets  its 
power  from  the  need  to  substitue  readjust- 
ment for  maladjustment.  It  seems  best, 
however,  to  reject  a  definition  that  identi- 
fies neurosis  with  all  imperfect  adjustment 
and  to  restrict  the  use  of  the  term  to  the 
more  severe  cases. 

Although  the  psychoneuroses  show  a 
gieat  variety  of  symptoms,  there  seem  to  be 
a  number  of  common  elements  that  consti- 
tute the  psychoneurotic  personality.  The 
most  striking  characteristic  is  a  low  toler- 
ance for  conflict.  Neurotic  persons  worry 
over  matters  that  are  not  of  immediate  im- 
portance and  show  strong  reactions  to  slight 
degrees  of  frustration.  Furthermore,  this 
pattern  is  persistent  and  chronic,  often  con- 
stituting a  life  style  that  can  be  observed 
from  the  individual's  childhood.  As  to 
symptoms,  a  neurosis  is  distinguished  either 
by  a  marked  degree  of  anxiety  that  is  out 
of  proportion  to  the  situation  evoking  it,  or 
by  certain  typical  mechanisms  which  sene 
to  reduce  strong  anxiety  but  hamper  social 
adjustments.  This  description  of  die  char- 
acteristics of  neurotic  behavior,  of  course, 
again  emphasizes  the  fact  that  it  differs  only 
in  degree  from  the  nonnal. 

Anxiety 

Fear  is  a  'catastrophic  response'  that  all 
persons  make  when  faced  ■svith  a  highlv  mo- 
tivated situation  to  -^vhich  thev  can  make 
no  effective  adjustment  (see  p.  104).  ^Anx- 
iety is  distinguished  from  fear  in  that  it  is 
a  response  to  an  anticipated  danger,  or  to 
a  symbol  of  one,  rather  than  to  the  threat- 
ening situation  itself.     Normal  anxietv  is 


532 


Personal  Adjusfment 


present  when  the  aniitipated  peril  is  innni- 
nent  and  probable.  It  is  sometimes  called 
situational  anxiety,  for  it  is  relieved  when 
the  situation  that  aroused  it  is  past.  For 
a  military  aviator  in  wartime  to  suffer  a 
severe  emotional  disturljance  when  under 
enemy  fire  is  normal  fear.  For  him  to  sho^v 
signs  of  emotion  as  he  contemplates  the 
next  combat  mission  is  normal  anxiety. 
But  if.  in  time  of  peace  and  in  the  safety 
of  his  own  country,  he  trembles  when  an 
automobile  backfires,  or  if  he  breaks  into 
perspiration  when  someone  slaps  hiin  on 
the  back,  he  is  showing  neurotic  anxiety, 
because  these  stimuli  are  only  partial  or  in- 
adequate symbols  of  the  original  fear-pro- 
ducing situation. 

Anxiety  manifests  itself  in  three  ways, 
which  are  the  usual  evidences  of  fear: 
through  a  conscious  state  of  discomfort  and 
apprehension,  through  ^•isceral  distiub- 
ances  especially  of  the  digestive  and  cir- 
culatory systems  and  through  motor  symp- 
toms which  include  restlessness,  trembling, 
irritability  and  the  like.  At  one  time,  these 
symptoms  were  regarded  as  separate  psy- 
choneuroses.  If  a  person  showed  mainly 
the  signs  of  apprehension,  he  was  diagnosed 
as  having  an  anxiety  neurosis.  The  vis- 
ceral upsets  were  labeled  neurasthenia  or 
hypochondria,  whereas  the  motor  symp- 
toms were  ascribed  to  neiuousness.  It  is 
now  recognized  that  all  anxious  persons 
show  all  three  of  these  effects  of  emotion, 
but  that  the  intensity  of  a  particular  symp- 
tom may  vary  from  one  person  to  another. 
It  is  fruitless  to  try  to  classify  anxiety  states 
as  if  they  were  types  of  diseases.  Real  un- 
derstanding can  be  achieved  by  regarding 
anxiety  as  an  emotional  and  nonadjustive 
response  which  a  person  is  making  to  his 
conflicts. 

Sometimes  anxiety  is  directed  toward  the 
real  source  of  the  conflict,  as  when  a  child 


who  is  reacting  to  a  conflict  between  de- 
pendence and  rejection  fears  that  liis  par- 
ents do  not  love  him  or  that  they  will  leave 
him.  More  often  the  most  important  cause 
of  the  conflict  is  not  identified,  because  the 
individual  has  repressed  his  responses  to  it. 
Such  a  repression  is  a  partial  adjustment, 
but  it  does  not  reduce  the  emotional  ten- 
sion of  the  conflict  entirely.  Anxiety  may 
then  take  a  generalized  form,  in  which  the 
individual  shows  dread,  indecision  and 
fear  in  many  aspects  of  his  life.  The  spread 
of  anxiety  to  remote  symbols  of  the  original 
conflict  is  the  same  phenomenon  as  that 
found  by  the  experimental  studies  of  con- 
flict in  animals.  "When  an  intense  con- 
flict has  not  been  solved,  its  effects  are 
'generalized'  to  many  facets  of  behavior. 

The  visceral  results  of  anxiety  can  be 
understood  in  terms  of  the  physiological 
effects  of  emotion.  Momentary  fear  in- 
hibits digestion,  accelerates  heart  beat, 
raises  blood  pressure  and  influences  a  num- 
ber of  glandvdar  secretions  (p.  104).  The 
chronic  anxiety  often  seen  in  psychoneu- 
rotic states  has  similar  effects,  but  these 
are  intensified  because  of  the  long  duration 
of  the  fear.  One  of  the  most  common 
symptoms  is  'nen'ous  indigestion.'  The 
anxious  person  does  not  enjoy  eating,  suf- 
fers gastric  distress  after  meals  and  may 
therefore  be  unable  to  assimilate  food,  even 
to  the  point  of  malnutrition.  An  extreme 
example  of  the  effect  of  anxiety  on  the 
digestive  system  is  the  development  of  gas- 
tric ulcers.  This  'psychosomatic'  disorder 
results  from  disturbances  of  the  gastric  se- 
cretions and  of  the  normal  mucous  lining 
of  the  stomach  and  seems  clearly  related  to 
the  emotional  tensions  resulting  from  con- 
flicts. Chronic  high  blood  pressure  can 
also  residt  from  nonadjustment. 

Since  strong  emotion  is  an  emergency 
condition  (p.  95),  it  rapidly  exhausts  the 


Anxiety  and  Phobias 


533 


body's  nulrilional  reserves.  Alter  a  loiij^ 
period  of  anxiety,  some  people  may  show 
symptoms  of  'nervous  exliaustion,'  inciiul- 
ing  fatigue,  weakness  and  lowered  effi- 
ciency. This  end  result  of  chronic  anxiety 
has  an  anomalous  adjustive  value,  similar 
to  that  of  an  escape  or  withdrawal  mech- 
anism. If  a  person  is  ill,  his  failures  are 
excused. 

Common  'nervousness'  is  a  very  frequent 
symptom  of  anxiety.  The  nervous  individ- 
ual is  irritable  and  'jumpy.'  He  is  given  to 
random  motor  outlets,  from  pacing  the 
floor  to  chewing  his  fingernails.  The  term 
also  includes  over-reaction  to  stimuli  that 
do  not  disturb  most  people,  such  as  startle 
responses  for  moderate  sounds  and  undue 
irritation  at  petty  annoyances.  A  common 
misconception  of  long  standing  has  re- 
garded nervousness  as  an  organic  condition 
due  to  'weak  nerves,'  and  countless  bottles  of 
'nerve  tonics'  have  been  consumed  futilely. 
Nervousness  cannot  be  understood  by  it- 
self, but  is  clearly  explained  as  a  diffused 
motor  response  under  emotional  tensions. 

Phobias 

In  many  instances  a  fear  response  is  at- 
tached to  a  specific  type  of  situation,  and 
it  is  then  known  as  a  phobia.  Mild  pho- 
bias, which  are  very  common,  may  be  stim- 
ulated by  almost  every  kind  of  situation 
imaginable.  Among  the  more  common 
phobias  are  fears  of  the  dark,  of  small  en- 
closed places,  of  heights,  of  animals,  of 
cro^\'ds,  of  water  and  of  thunderstorms. 
The  list  could  be  continued  endlessly.  A 
person  with  a  phobia  admits  that  his  fear 
is  groundless  but  he  is  unable  to  control  it. 
Although  many  normal  people  have  minor 
phobias,  the  condition  is  regarded  as  psy- 
choneurotic when  it  is  severe  and  of  long 
duration,  and  when  it  interferes  with  ordi- 
nary life  activities  to  an  appreciable  degree. 


Sonic  jjhobias  have  been  traced  to  spe- 
cific instances  in  the  earlier  life  of  the  in- 
dividual by  which  he  learned  to  fear  a  cer- 
tain type  of  situation.  These  are  essen- 
tially conditioned  lear  reactions.  In  one 
classic  case  of  phobia  a  British  officer  in 
the  war  of  1914-1918  was  so  afraid  of  small 
enclosed  places  that  he  could  not  enter  a 
dugout.  At  first,  he  could  not  remember 
any  cause  for  this  phobia,  but  a  long  series 
of  psychological  consultations,  probing  his 
early  experiences,  eventually  resulted  in  the 
recall  of  a  pertinent  childhood  experience. 
When  he  was  about  three  or  four  years  of 
age,  he  had  been  caught  in  a  narrow  corri- 
dor with  a  vicious  dog,  from  which  he 
could  not  escape.  He  had  never  related 
this  incident  to  anyone,  for  he  had  re- 
pressed a  recall  of  it  as  a  partial  adjustment. 
When  he  finally  was  helped  to  remember 
the  event,  his  phobia  of  enclosed  places 
was  cured.  In  another  case  a  college  girl's 
fear  of  eyes  was  traced  to  a  childhood 
fright  occasioned  by  finding  a  pair  of  glass 
eyes  while  she  was  guiltily  peeping  in  the 
bureau  drawers  at  the  home  of  an  aunt. 
As  in  the  other  case,  memory  of  the  event 
had  been  inhibited,  but  the  conditioned 
emotional  reaction  remained  to  constitute 
the  phobia. 

Not  all  phobias  have  been  traced  to 
specific  conditioned  fears.  In  some  in- 
stances, including  the  more  severe  and  dis- 
abling ones,  the  feared  situation  is  a  svm- 
bol  of  the  real  cause  of  die  emotion.  For 
example,  a  young  girl  who  had  a  phobia  for 
open  places  and  large  rooms  Avas  found 
really  to  have  a  feai-  of  death.  These  sym- 
bolic phobias  are  very  similar  to  anxieties, 
except  that  the  individual  has  displaced 
his  fear  to  a  specific  kind  of  situation,  in- 
stead of  having  it  remain  generalized. 

The  part  that  repression  plays  in  many 
severe  maladjustments  is  most  clearly  seen 


534 


Personal  Adjustment 


in  the  phobias.  They  show  that  a  'for- 
gotten' event  can  continue  to  influence 
behavior.  From  a  single  experience,  a 
j:)erson  can  acc[uire  several  responses  that 
may  be  somewhat  independent  of  one  an- 
other. He  may  learn  to  represent  the  event 
b\  words  or  otlier  symbols  when  an  appro- 
priate stimulus  is  presented  in  the  future; 
that  is  recall.  He  may  also  learn  to  make 
certain  emotional  responses,  and  to  have 
certain  feelings  or  attitudes  when  a  stimu- 
lus associated  with  the  experience  occurs. 
The  recall  can  be  repressed  as  an  adjustment 
to  its  unpleasantness  without  the  occur- 
rence of  a  corresponding  inhibition  of  the 
emotion  or  attitude.  This  is  a  factor  worth 
luiderstanding  in  the  'unconscious'  deter- 
mination of  behavior.  On  the  other  hand, 
the  inability  to  remember  an  experience 
inevitably  makes  it  difficult  or  even  impos- 
sible to  readjust  to  it  rationally.  A  phobia 
persists  because  an  individual  cannot  learn 
to  make  a  new,  more  constructive  response 
to  a  past  event  which  he  cannot  remember. 
The  recall  of  the  basic  experience  often 
cures  a  phobia,  not  because  of  any  magic 
of  'getting  a  complex  out  of  the  uncon- 
scious' but  because  the  individual  is  now 
able  to  work  out  a  readjustment,  using  his 
more  mature  adult  capacity  to  deal  with 
the  problem. 

Compulsions  and  Obsessions 

Most  persons  can  remember  normal, 
childish,  compulsive  acts  and  obsessive 
thoughts:  not  stepping  on  the  cracks  of  the 
sidewalk,  a  silly  phrase  running  through 
the  head.  Such  aflairs  may  be  greatly 
exaggerated  in  some  psychoneurotics. 

W'hen  a  compulsion  occurs  in  connection 
with  a  phobia,  its  adjustive  value  is  seen 
most  clearly.  To  an  individual  who  has  a 
fear  of  being  attacked  in  the  night,  tension 
is  obviously  reduced  by  examining  all  the 


bolts  and  locks  repeatedly  and  by  making 
several  inspections  of  the  closets  and  un- 
der the  beds.  A  compulsion  is  a  routine 
that  gives  a  sense  of  security.  It  is  exag- 
gerated beyond  the  bounds  of  ordinary 
prudence  because  the  anxiety  that  it  re- 
duces is  itself  not  ordinary.  A  similar 
psychological  function  is  served  by  the  com- 
pulsive tendencies  of  persons  who  must  al- 
ways perform  their  common  tasks  in  ex- 
actly the  same  way.  Such  a  person  is  usu- 
ally insecure,  finding  safety  in  living  by 
rules  and  routines  in  a  rigidly  orderly  man- 
ner. Persons  with  well-developed  compul- 
sions may  reduce  their  anxieties  so  well  that 
they  have  little  consciousness  of  fear.  Usu- 
ally, however,  compulsive  behavior  is  ac- 
companied by  visceral  upsets  and  'nervous' 
mannerisms  that  reveal  the  existence  of  a 
strong  tension. 

An  obsession  is  a  compulsive  thought  that 
keeps  recurring,  even  when  the  person  tries 
to  banish  it.  The  obsessive  thought  is  an- 
noying, sometimes  because  it  is  distressing 
in  itself  and  sometimes  because  it  seems 
foolish  and  irrational.  In  one  case  a  man 
had  an  obsessive  thought  that  he  would 
cut  his  wife's  throat.  He  said  that  his 
relationship  with  his  wife  was  excellent 
and  that  the  unreal  obsession  troubled  him 
seriously.  In  a  long  series  of  psychiatric 
interviews,  it  was  discovered  that  the  man's 
mother  had  been  harsh  and  exacting.  Re- 
cently he  had  given  up  activities  in  which 
he  was  interested  on  the  demand  of  his 
wife.  He  transferred  to  his  wife  the  re- 
sentment that  he  had  felt  toward  his  mother 
but  had  repressed  any  open  hostility.  The 
obsession  was  a  substitute  expression  of  this 
aggression,  a  thought  which  he  was  able  to 
allow  himself  because  he  disowned  any 
desire  to  harm  her  as  absurd  and  unreal. 
The  obsession  disappeared  after  he  had 
readjusted  his  attitudes  toward  his  wife  and 


Compulsions,  Obsessions  and  Ailment  Adjustmenis 


536 


his  mother.  Another  common  type  ol  (Aj- 
session  is  a  compulsive  worry  lest  some  harm 
Ijelall  a  member  of  the  worrier's  family. 
Often  this  fear  has  been  found  to  be  a 
defense  against  a  rejected  aggressiveness. 
What  the  worrier  really  fears  is  that  he  will 
himself  bring  harm  to  the  person  about 
whom  he  worries. 

One  shoidd  not  generalize  unduly  from 
these  few  instances,  for  the  meaning  of  any 
compulsion  or  obsession  can  be  ascertained 
only  by  a  careful  study  of  the  individual 
who  shows  the  symptom.  In  all  cases,  how- 
ever, a  compulsion  or  obsession  has  some 
relationship  to  personal  conflicts  and 
anxieties. 

Ailment  Adjustments 

Another  way  by  which  people  can  adjust 
to  serious  conflicts  is  by  developing  symp- 
toms that  give  them  the  status  of  disabled 
persons,  so  that  they  receive  sympathy  and 
protection.  Some  very  striking  disabilities 
can  be  acquired  adjustively,  including 
pains,  blindness,  deafness  and  muscidar 
paralysis.  Historically,  conditions  of  this 
sort  have  been  called  conversion  hysteria^ 
and  the  adjustive  conflict  is  said  to  have 
been  'converted'  into  the  physical  symp- 
tom. Psychoneurotic  reactions  of  this  type 
are  so  bizarre  that  laymen  are  often  skepti- 
cal of  their  existence,  or  else  confuse  them 
with  malingering,  the  conscious  faking  of 
symptoms.  It  is  possible,  however,  to  un- 
derstand them  in  terms  of  the  psychological 
principles  of  learning  and  adjustment. 

Suppose,  for  example,  that  a  high  school 
girl's  social  adjustment  is  so  poor  that  she 
has  a  need  to  shun  the  company  of  other 
young  people.  One  day,  when  she  is  par- 
ticularly distressed  by  her  basic  conflict, 
her  leg  'goes  to  sleep,'  a  temporary  condi- 
tion of  numbness  that  is  commonly  experi- 
enced   by    normal    people.      This    passing 


symptom  is  seized  upon  as  a  solution  of  h^-; 
adjustmeiu.  If  her  leg  is  paralyzed,  .she 
cannot  go  to  school,  and  will  receive  the 
sympathy  that  is  extended  to  one  who  is 
ill.  SiiKC  muscular  responses  arc  subject 
to  learning  and  inhibition,  'learning  to  have 
a  jjaralysis'  as  a  solution  to  a  tf>nfli(t  can 
be  explained  by  the  same  psychological 
concepts  that  are  used  to  account  for  other 
adjustments.  Similar  accounts  can  be  given 
of  cases  of  hysterical  blindness,  deafness, 
nausea  and  other  symptoms. 

Although  severe  cases  of  conversion  hys- 
teria are  classed  as  psychoneuroses,  fjecause 
they  are  socially  disabling  and  are  responses 
to  major  conflicts,  a  similar  mechanism 
can  be  found  in  a  milder  degree  in  normal 
people.  It  is  not  entirely  a  figure  of  speecli 
that  a  disagreeable  task  'gives  vou  a  pain.' 
The  'nine  o'clock  headache,'  which  disajj- 
pears  when  it  is  too  late  to  go  to  work  or 
to  school,  is  essentially  a  mild  hysterical 
adjustment.  Almost  everyone  becomes 
more  fatigued  when  a  given  amoiuit  of 
effort  is  to  be  expended  on  a  distasteful  job 
than  Avhen  it  is  to  be  devoted  to  play  or  to 
a  hobby.  There  is  a  continuum  from  the 
defense  mechanisms  of  normal  people  to 
the  most  severe  hysterical  psychoneuroses. 

PSYCHOSES 

The  most  seriously  nonadjustive  condi- 
tions are  the  psychoses,  popularly  known 
as  insanities  or  mental  disorders.  Socially, 
a  considerable  gidf  separates  the  psyclioses 
from  the  maladjustments  and  psychoneu- 
roses. A  psychoneurotic  person  is  a  discom- 
fort to  himself  and  may  be  a  nuisance  to 
others,  but  a  person  with  a  fully  developed 
psychosis  is  dangerous  to  himself  and  to 
society. 

There  is  no  continuity  betAveen  psyclio- 
neurosis  and  psvchosis.     In  fact,  very  few 


536 


Personal  Adjustment 


psychoneurotics  e\cr  develop  a  psychosis. 
Making  an  adjustment  by  developing 
anxiety  and  by  reducing  it  with  defense 
mechanisms,  which  is  typical  of  neurosis, 
seems  to  be  an  alternative  to  the  more  seri- 
ous psychotic  response  of  adjusting  by  re- 
treat from  reality. 

Psychoses  are  more  common  than  is  ordi- 
narily realized.  There  are  about  half  a 
million  persons  in  mental  hospitals  in  the 
United  States.  More  hospital  beds  are  de- 
voted to  the  mentally  ill  than  to  all  other 
kinds  of  patients  together.  Of  every  thou- 
sand persons  born,  approximately  fifty 
will  be  admitted  to  a  mental  hospital  at 
some  time  in  their  lives.  On  the  brighter 
side  of  the  j^icture,  mental  disorders  are  not 
as  hopeless  as  uninformed  popular  opinion 
holds.  A  very  large  proportion  of  psychotic 
patients  are  discharged  from  hospitals  as 
cured  or  as  sufficiently  improved  to  make  a 
passable  adjustment  to  everyday  life.  Re- 
cent developments  in  treatment  seem  to 
be  increasing  the  proportion  of  successful 
outcomes. 

Organic  Psychoses 

About  one-half  the  patients  in  mental 
hospitals  suffer  from  disorders  that  are 
caused  by  identified  organic  conditions. 
They  include  brain  injuries,  syphilis  of  the 
nervous  system,  chronic  addiction  to  alco- 
hol and  other  drugs  and  brain  deteriora- 
tion associated  with  old  age.  All  except 
the  senile  conditions  can  be  treated  with 
some  effectiveness  if  not  in  too  advanced  a 
stage. 

Functional  Psychoses 

The  remaining  half  of  mental  disorders 
are  called  functional  psychoses,  a  term  that 
implies  that  they  are  due  to  adjustive  causes, 
that  is  to  say,  to  the  defective  functioning 
of  organically  intact  individuals.    As  a  mat- 


ter of  fact,  the  causes  of  these  psychoses 
are  \'ery  inadequately  kno^vn.  The  same 
adjustive  mechanisms  that  are  foimd  in  nor- 
mal people  occm-  in  extravagant  forms  in 
these  psychoses,  which  seems  to  support 
tlie  interpretation  that  they  are  extreme 
reactions  to  conflict.  Some  case  histories 
appear  to  explain  a  psychosis  adequately 
as  a  response  to  a  very  severe  conflict,  but 
in  other  instances  people  break  down  under 
circumstances  that  do  not  ordinarily  cause 
great  difficulties.  It  may  be  supposed  that 
all  the  functional  psychoses  are  not  due  to 
the  same  causes,  and  that  physiological  con- 
ditions as  yet  undiscovered  may  be  impor- 
tant factors  in  some  or  even  in  all  cases. 

Almost  all  patients  with  functional  psy- 
choses fall  in  one  of  the  two  main  classes 
of  such  disorders,  which  are  schizophrenia 
and  manic-depressive  psychosis.  Classic 
cases  of  these  two  psychoses  are  clearly 
distinguishable,  but  there  are  also  mixed 
or  variable  forms  that  cannot  be  classified 
so  easily.  Until  we  know  more  about  the 
causes  of  the  functional  psychoses,  even 
their  diagnosis  will  remain  uncertain. 

The  common  behavior  pattern  of  schizo- 
phrenia, which  is  also  known  as  dementia 
praecox,  is  a  lack  of  appreciation  of  reality, 
usually  accompanied  by  apathy  or  a  flat  im- 
responsive  emotional  tone.  This  funda- 
mental characteristic  has  associated  with 
it  a  great  variety  of  more  specific  symp- 
toms. Some  schizophrenics  show  little 
more  than  apathy,  indifference  and  marked 
withdrawal  from  social  demands.  In  ex- 
treme instances  this  withdrawal  is  so  pro- 
nounced that  the  patient  sits  or  lies  for 
hours  in  the  same  posture,  does  not  attend 
to  his  bodily  needs  or  keep  himself  clean, 
and  has  to  be  fed  by  force.  Other  schizo- 
phrenic patients  are  more  active  but  show 
the  common  loss  of  connection  with  reality. 
They    may    talk    in    a   silly   or    incoherent 


Psychoses 


537 


manner,  laugh  or  cry  when  there  is  no 
observable  reason,  destroy  clothing  and 
furniture  and  be  difficult  to  care  for  with- 
out force  or  restraint.  Hallucinations,  es- 
pecially of  hearing  accusing  voices,  are  com- 
mon. 

Delusions,  or  false  beliefs  held  without 
reference  to  reality,  occur  frequently  in 
schizophrenia.  In  one  type,  called  para- 
noid schizophrenia,  the  delusions  are  the 
most  noticeable  symptom.  The  most  fre- 
quent delusion  is  persecution.  The  pa- 
tient declares  he  has  been  robbed,  cheated 
or  imprisoned  by  his  family,  or  that  people 
have  conspired  to  cause  him  to  lose  his 
position.  Delusions  of  grandeur  are  less 
frequent  and  are  believed  to  be  secondary 
to  those  of  j^ersecution,  arising  because  the 
patient  has  to  build  a  false  belief  about  his 
own  importance  to  explain  why  he  is 
singled  out  for  oppression.  Delusions  in 
the  mentally  disordered  serve  the  same  pur- 
poses that  rationalization  and  projection  do 
in  normal  persons.  Dekisions  help  to  ex- 
plain defeats  and  to  build  a  sense  of  im- 
portance. They  are  tolerated  by  the  pa- 
tient because  his  distorted  perception  of 
reality  prevents  their  critical  appraisal. 

Schizophrenia  is  a  psychosis  typical  of 
young  persons.  Although  there  are  cases  at 
all  ages,  the  peak  of  hospital  admissions 
with  this  diagnosis  lies  in  the  decade  of  the 
twenties.  In  most  instances  the  disorder 
has  been  developing  over  a  considerable 
period  of  time,  having  begun  with  seclu- 
siveness  and  queer  behavior.  It  becomes  a 
full-blown  {psychosis  when  the  individual  is 
unable  to  make  the  adjustments  that  aduh 
life  demands. 

Manic-depressive  psychosis  is  the  other 
frequent  psychotic  condition.  It  consists 
either  of  overactivity  and  an  elated  feeling 
tone  in  the  manic  phase  or  of  retardation 
and    sadness    in    the    depressed    condition. 


Usually  a  patient  has  an  attack  in  one  or 
the  other  of  these  forni.s,  and  then  rccovcr<>. 
In  some  instances  there  may  be  a  series  of 
episodes,  sometimes  alternating  between 
mania  and  depressifjn.  It  is  for  this  rea- 
son that  the  psychosis  is  regarded  as  one 
condition  rather  than  as  two  separate  dis- 
orders. Less  is  known  about  the  psycho- 
logical basis  of  the  manic-depressive  state 
than  about  that  of  schizophrenia.  It  has 
been  suggested  that  manic-depressives  are 
persons  who  have  never  learned  how  tfj 
compromise,  who  are  either  completely  de- 
feated by  conflict  or  else  deny  it  by  an 
unreal  elation.  No  hypothesis  is  very  satis- 
factory, however,  and  the  major  factors  un- 
derlying this  psychosis  remain  to  be  discov- 
ered. Manic-depressive  conditions  are  most 
frequent  in  middle  life,  the  greatest  fre- 
quency occurring  in  the  decade  from  fort\ 
to  fifty  years. 

The  Treatment  of  the  Psychoses 

The  functional  psychoses  have  not  been 
treated  with  great  success  in  the  past,  al- 
though many  cases  show  spontaneous  im- 
provement. The  most  promising  method 
of  treatment  so  far  devised,  developed  in 
the  1930's,  is  known  as  shock  therapy.  In 
one  technique,  a  drug  (insulin,  metrazol) 
is  used  to  induce  unconsciousness,  con^•ul- 
sions  or  both  in  the  patient.  In  another 
method,  electric  currents  are  passed  through 
the  brain  to  cause  convulsions  and  uncon- 
sciousness. After  a  shock  treatment  the 
patient  is  found  to  be  confused.  ^Vhen 
his  confusion  clears,  his  basic  psvcliosis  is 
often  much  improved.  Insulin  and  meu^a- 
zol  have  been  used  most  successfullv  with 
schizophrenia  and  electric  shock  widi  de- 
pressed conditions,  but  ueatments  are  not 
entirely  specific. 

Another  very  radical  treatment  is  pre- 
frontal lobotomy  (p.  38),  a  surgical  opera- 


538 


Personal  Adjustment 


tion  that  severs  the  connection  of  a  part  of 
the  frontal  lobes  from  the  rest  of  the  brain. 
It  has  brought  improvement  to  some  cases 
of  depression  and  of  schizophrenia,  but  it 
results  in  permanent  changes  in  personal- 
ity. Topectomy  is  a  recent  operation  more 
selective  in  the  destruction  of  tissue. 

The  shock  and  surgical  treatments  are 
empirical  and  are  not  based  on  any  gen- 
erally accepted  theory.  Some  hypotheses 
are  that  shock  treatment  stimulates  the 
autonomic  nervous  system,  leading  to  new 
adjustive  attempts,  or  that  it  influences  the 
metabolism  of  the  brain.  Other  interpre- 
tations suggest  that  shock  therapy,  like 
lobotomy,  damages  the  brain  and  destroys 
the  pathways  representing  the  nonadjustive 
reactions.  The  patient  then  has  to  learn 
new  adjustments,  using  different  neural 
connections.  It  is  also  argued  that  injury 
to  the  frontal  lobes  and  their  connections 
reduces  the  total  integration  of  the  brain 
and  thus  the  patient's  ability  to  relate  to 
each  other  events  that  occur  or  are  due 
to  occur  at  different  times.  Thus  the  pa- 
tient becomes  thoughtless  and  his  planning 
superficial.  It  is  possible  that  a  psychosis 
might  get  disrupted  in  this  way  along  with 
a  patient's  'time  perspective.' 

Psychotherapy  is  treatment  carried  out 
by  consultations  and  interviews,  that  is  to 
say,  by  psychological  methods  as  distin- 
guished from  medical.  Psychotherapy  has 
not  been  of  great  value  in  treating  fully 
developed  psychoses,  because  of  the  pa- 
tients' disturbed  perception  of  reality  and 
their  inability  to  communicate  with  the 
psychiatrist  as  intelligibly  as  can  a  psycho- 
neurotic person.  It  is  effective  with  some 
incipient  disorders  that  are  not  very  severe 
and  is  of  especial  usefulness  with  patients 
whose  psychoses  ha\e  been  terminated  by 
shock  therapy.  In  these  cases,  psychological 
consultation  helps  to  work  out  the  old  con- 


flicts  and    to   establish    more    constructive 
adjustments  to  them. 

All  types  of  treatment  have  a  greater 
chance  of  being  effective  if  they  are  begun 
early  in  the  development  of  a  psychosis. 
Early  treatment,  however,  ■  requires  the 
prompt  recognition  of  symptoms  of  with- 
drawn, erratic  or  depressed  behavior.  The 
chief  obstacle  to  such  recognition  is  not 
ignorance  but  the  superstitious  fear  of 
mental  disorders  that  prevents  families 
from  recognizing  the  condition  and  seek- 
ing professional  assistance.  Educated  per- 
sons can  do  much  to  aid  mental  hygiene 
in  their  communities  by  combatting  the 
fear  of  mental  disorders,  by  helping  people 
to  realize  that  psychoses  are  not  more  dis- 
graceful than  other  illnesses  and  by  pro- 
moting the  development  of  psychiatric 
clinics  at  which  reliable  help  can  be  ob- 
tained. 

TECHNIQUES    FOR 
READJ  USTMENT 

Persons  who  are  worried  about  their  so- 
cial relationships  or  personal  problems,  or 
who  recognize  signs  of  maladjustment  in 
themselves,  can  get  substantial  help  from 
trained  consultants  whose  profession  is  to 
assist  anyone  in  working  out  his  psycho- 
logical problems.  The  qualifications  for 
professional  work  in  this  area  are  not  as  yet 
well  standardized.  Many  psychiatrists  are 
excellently  equipped  to  serve  persons  who 
need  this  kind  of  help.  A  psychiatrist  is  a 
medical  doctor  who  has  specialized  in  the 
care  of  mental  disorders  and  psychological 
problems.  Some  psychiatrists  are  experi- 
enced only  in  the  care  and  handling  of  the 
psychoses  and  are  not  interested  in  less 
severe  conditions,  but  psychiatrists  are  now 
being  trained  whose  major  interest  is  in  the 
psychoneuroses  and  maladjustments.   Many 


Counseling  and  Psychotherapy 


539 


clinical  and  cou.sull.ing  jjsychologists  ate 
also  competent  to  give  eflective  counseling 
on  personal  problems.  Not  all  psycholo- 
gists are  included  in  this  category,  of  course, 
as  those  with  a  primary  interest  in  pure  and 
experimental  psychology,  or  in  applications 
to  industry,  personnel  selection,  test  con- 
struction and  the  like,  may  have  no  ex- 
perience at  all  as  counselors.  In  addition 
to  psychiatrists  and  clinical  psychologists, 
there  are  some  social  workers,  teachers, 
school  counselors  and  clergymen  who  can 
give  adecjuate  psychological  guidance,  but 
the  majority  of  persons  in  these  professions 
are  not  prepared  to  do  so. 

Counseling  and  Psychotherapy 

Psychological  treatment  is  usually  called 
counseling  when  it  deals  with  minor  adjust- 
ments and  psychotherapy  when  it  treats 
psychoneuroses  or  psychoses.  The  aims  of 
counseling  and  psychotherapy  are  essen- 
tially the  same:  to  free  the  individual  from 
inhibitions  and  repressions  and  to  give  him 
improved  insight  into  his  own  conflicts  and 
adjustments,  so  that  he  can  work  out  a  more 
satisfactory  solution  to  his  problems.  In 
most  instances,  the  objective  is  to  relieve 
him  of  anxieties  and  to  change  his  atti- 
tudes rather  than  to  teach  him  better  con- 
duct. The  person's  distress  is  the  main 
problem,  not  his  specific  behavior.  When 
the  tensions  are  reduced,  social  behavior 
usually  rights  itself. 

Experience  shows  that  advice  is  a  poor 
tool  for  counseling.  A  maladjusted  per- 
son usually  knows  what  he  should  do,  but 
finds  himself  unable  to  carry  out  his  own 
best  judgment.  Reassurance,  the  technique 
of  convincing  the  client  that  he  is  not 
badly  off,  is  also  of  limited  value.  It  may 
be  serviceable  in  specific  and  limited  prob- 
lems, as  in  dealing  with  a  boy  who  is  wor- 
ried about  masturbation.     A  person  with 


real  anxiety,  howevc)',  knows  that  some- 
thing is  the  matter  with  him,  and  reassur- 
ance does  not  reduce  his  anxiety,  but  only 
discredits  the  counselor  for  his  apparent 
lack  of  understanding.  In  general,  coun- 
selors have  found  that  they  cannot  solve 
a  client's  problems  for  him;  they  can  only 
provide  an  atmosphere  that  aids  the  suf- 
ferer to  work  out  his  own  solutions. 

A  universal  technique  in  counseling  and 
psychotherapy  is  to  get  the  client  to  talk 
about  his  conflicts  and  feelings.  After  he 
has  told  about  his  complaint,  the  counselor 
often  uses  questioning  to  draw  out  further 
information.  Questioning  has  limitations, 
however,  as  it  may  cause  the  client  to  be- 
come defensive  and  to  resort  to  rationali- 
zations. A  superior  method  is  reflection 
of  feelings.  When  using  this  technique, 
the  counselor  responds  to  each  statement 
of  the  client  by  showing  that  he  under- 
stands it,  is  deeply  interested  in  the  client 
and  appreciates  how  the  client  feels.  This 
method,  which  is  sometimes  called  nondi- 
rective  counseling  and  sometimes  client- 
centered  counseling,  is  illustrated  by  the 
following  fragment  of  an  interview.  The 
client,  L.  H.,  is  a  discharged  serviceman, 
whose  problem  is  restless  and  'nervous'  be- 
havior.* 

1.  L.  H.  "I  don't  know  what's  the 
matter  with  me.  I  just  can't  seem  to 
settle  down.  I  don't  like  to  stick  to  any- 
thing. This  job  I've  got  should  be  all 
right  for  me,  but  I  can  hardly  stand  it 
to  keep  on  working." 

2.  Counselor.  "You're  wonied  and 
upset  because  you  can't  buckle  do^sTi  to 
whatever  you  start  to  do." 

3.  L.  H.  "That's  right— I  get  all  up- 
set—I—I always  seem  to  remember  -what 

*  C.  R.  Rogers  and  J.  L.  ^Va^en.  Counseling  with 
returned  sen'icemen,  McGraw-Hill,  1946,  pp.  62-64. 


540 


Personal  Adjustment 


happened  to  me  in  the  Army.       I  really 
went  through  hell!" 

4.  Counselor.  "You  feel  that  you 
really  had  a  very  tough  time  while  in  the 
Army." 

5.  L.  H.  "I'll  say  I  did.  [Pause.] 
Well,  the  first  few  years  weren't  so  bad, 
but  the  last  year  was  terrible.  I  never 
want  to  go  through  that  again  as  long 
as  I  live.  The  men  didn't  associate  with 
me  much.  I  wouldn't  say  I  had  any 
friends  there.  Nobody  had  any  use  for 
me,  and  my  commanding  officer  rode  me 
something  awful— you  can't  imagine  how 
it  was." 

6.  Counselor.  "You  feel  that  quite  a 
few  people  had  it  in  for  you." 

7.  L.  H.  "Yes,  that's  putting  it  mildly. 
It  got  so  bad  that  they  were  always 
calling  me  A'ile  names  and  I  had  to  fight 
for  any  rights  I  wanted,  and  then  finally 
I  was  wounded  and  got  away  from  all 
that." 

8.  Counselor.  "It  was  almost  a  re- 
lief to  you  to  be  wounded  and  get  away 
from  all  the  things  you  went  through." 

9.  L.  H.  "Yes,  it  was.  [Pause.]  But 
the  pay-off  to  all  this  came  when  an  Army 
doctor  got  hold  of  me.  I  told  him  a  lot 
of  very,  very  personal  things  that  had  no 
concern  with  the  Army.  He  betrayed 
my  trust  and  told  my  commanding  offi- 
cer all  that  I  had  confided  in  him.  I 
could  have  killed  him  for  that!  I  had  a 
bad  time  telling  anybody  anything  after 
that.  [Pause.]  But  for  some  reason  it 
seems  different  with  you— you  know  I 
wouldn't  tell  you  all  this  if  I  didn't  trust 
you." 

10.  Counselor.  "Although  the  doc- 
tor made  it  hard  for  you  to  talk  aboui 
your  feelings,  you  have  some  confidence 
in  me." 

11.  L.  H.     "Yes.     You  know  I  hated 


those  men  so  much  I  could  kill  them.  I 
would  just  think  of  all  the  things  I'd 
like  to  do  to  them.  Maybe  that's  not 
right,  but  that's  the  way  I  felt." 

12.  Counselor.  "You  feel  a  little 
guilty  about  these  intense  feelings  of 
hatred,  but  they  were  there  neverthe- 
less." 

13.  L.  H.  "Yes— in  fact  [pause]— I  just 
about  did  kill  a  fellow.  We  got  in  a 
fight  [tells  details  of  the  quarrel],  and  I 
hit  him  with  a  wrench.  I  guess  I  went 
out  of  my  head." 

14.  Counselor.  "You  feel  you  lost  all 
control  of  your  emotions  for  a  while." 

15.  L.  H.  "You  know  I  seem  to  get 
relief  by  just  getting  this  out.  You're 
the  first  person  I've  ever  told  that  to." 

16.  Counselor.  "It  helps  you  to  talk 
about  these  things  that  you  have  been 
keeping  to  yourself." 

The  remainder  of  the  inter\'iew  was  con- 
cerned with  other  aspects  of  his  problem. 

In  addition  to  the  reflection  of  feeling, 
interpretation  is  sometimes  used  to  speed 
insight,  that  is  to  say,  the  counselor  ex- 
plains to  the  client  something  of  the  mean- 
ing and  origin  of  his  conflicts.  When  done 
skillfully,  interpretation  may  be  of  gi'eat 
value.  If  it  is  given  prematurely,  before 
the  client  is  ready  to  admit  the  interpreta- 
tion himself,  it  may  produce  anxiety  or 
cause  the  client  to  discontinue  the  consul- 
tations. If  it  is  incorrect,  the  client  may 
be  anxious  and  confused.  For  these  rea- 
sons, many  counselors  avoid  interpretation 
altogether,  and  trust  the  client  to  gain  in- 
sight through  his  own  recollections. 

In  successful  counseling  the  client  gains 
insight  into  the  sources  and  meaning  of  his 
feelings  and  behavior,  and  no  longer  reacts 
emotionally  to  his  problems.  Sometimes 
the  insight  comes  gradually,  sometimes  sud- 


Psychotherapy 


541 


dently  alter  a  considerable  number  of  inter- 
views. When  his  tensions  are  reduced,  tlie 
client  is  able  to  attack  his  difficulties  ration- 
ally instead  ol  emotionally.  He  overcomes 
some  of  his  limitations  and  accepts  those 
that  he  cannot  overcome.  Such  a  mixed 
solution  is  regarded  as  a  satisfactory  out- 
come of  psychotherapy. 

Psychoanalysis  is  a  particular  form  of 
psychotherapy  and  also  a  theory  of  the  na- 
ture of  the  process  of  treatment.  A  stand- 
ard psychoanalysis  is  a  very  lengthy  type 
of  treatment,  usually  requiring  daily  ses- 
sions for  a  period  of  a  year  to  several  years. 

The  psychoanalytic  theory  of  treatment 
is  based  on  the  hypothesis  that  all  malad- 
justments originate  from  the  conflicts  that 
a  child  has  toward  his  parents.  In  the 
analysis,  the  client  develops  transference 
toward  his  analyst,  that  is  to  say,  the  analyst 
becomes  an  emotional  substitute  for  the 
client's  father  or  mother.  The  infantile 
conflicts  are  then  reenacted  and  worked 
through,  with  the  result  that  the  client  is 
freed  of  their  effects.  Many  psychologists 
believe  that  psychoanalysis  as  a  theory 
neglects  immediate  conflicts  and  cultural 
influences  by  its  excessive  emphasis  on  the 
influence  of  early  childhood.  It  does,  how- 
ever, produce  strikingly  favorable  results  in 
some  cases. 

Interpretation  of  Psychotherapy 

The  explanation  of  how  and  why  psycho- 
therapy is  effective  does  not  require  any 
far-fetched  hypotheses,  but  can  be  made  in 
terms  of  familiar  psychological  principles. 
Essentially  it  is  a  subtle  kind  of  learning 
process. 

The  relationship  between  the  client  and 
the  counselor  is  the  first  essential  of  psycho- 
therapy. The  therapist  is  warm  and  inter- 
ested, and  evokes  an  attitude  of  trust  and 
friendliness.      He    never    expresses    disap- 


proval or  disgust  at  any  of  the  client's  rev- 
elations, and  never  criticizes,  lectures  or 
advises.  The  counseling  atmosphere  is 
therefore  a  new  .social  experience  for  the 
client.  He  finds  after  a  few  sessions  that 
he  does  not  have  to  be  defensive  and  can 
talk  freely  about  his  fears,  conflicts  and 
aggressive  tendencies  without  expecting 
censure. 

As  the  client's  social  inhibitions  are  re- 
leased by  the  counselor's  attitude  and 
method,  he  finds  himself  describing  emo- 
tionally toned  experiences  about  w^hich  he 
is  ordinarily  unable  to  talk,  and  remember- 
ing events  whose  recall  had  been  repressed. 
In  this  phase  of  treatment,  sometimes  called 
catharsis,  meaning  purge,  the  client  is  re- 
sponding to  emotion-evoking  stimuli  in  a 
nonreinforcing  situation.  Extinction  of 
emotional  responses  takes  place  by  unrein- 
forced  repetition,  as  in  the  conditioned  re- 
action experiments  (p.  142).  The  client 
now  finds  that  he  can  face  his  conflicts  with 
reduced  anxiety. 

The  expression  of  pre\iously  inhibited 
emotional  attitudes  and  the  recall  of  re- 
pressed experiences  permit  the  client  to 
view  his  adjustive  life  more  comprehen- 
sively than  he  could  before  the  treatment. 
Thus  he  is  led  to  gain  insight  about  him- 
self, his  problem,  his  relationships  to  odier 
people  and  the  demands  of  his  environ- 
ment. Insight  can  sometimes  be  promoted 
by  the  counselor's  interpretations,  but  it 
never  can  be  foixed.  It  has  to  be  con- 
structed by  the  client  through  his  o-wn 
probIem-sol\  ing  efforts.  Insight  is  genuine 
and  functional  only  Avhen  the  client  ac- 
cepts it  emotionally  as  Avell  as  intellect- 
ually. After  insight  has  been  adiieved,  the 
client  usually  makes  his  o'^vn  self-initiated 
attempts  toward  readjustment.  His  new 
adjustments  are  superior  to  his  old  ones, 
because  of  his  freedom  from  tension  and 


542 


Personal  Adjustment 


his  superior  appreciation  of  reality.  After 
all  you  can  come  to  accept  life— your  own 
life— as  it  really  is  (1)  if  you  can  realize 
fully  just  what  the  reality  of  yourself  in 
your  world  is  like  and  (2)  if  you  can  get 
rid  of  the  bitterness  and  emotion  which  go 
with  not  being  able  to  have  what  you  very 
much  want.  Psychotherapy  helps  you  to 
learn  how  to  want  most  what  you  can  have. 

MENTAL    HYGIENE 

The  aim  of  mental  hygiene  is  to  aid 
people  to  achieve  more  satisfying  and  more 
producti\'e  lives,  through  the  prevention  of 
anxieties  and  maladjustments.  It  is  un- 
likely that  mental  hygiene  will  ever  be  able 
to  reach  its  goal  completely,  but  much  good 
can  be  done,  comparable  to  the  gains  that 
medical  hygiene  has  made  in  reducing  the 
occurrence  of  disease. 

Mental  Hygiene  in  Childhood 

The  early  years  of  life  are  most  signifi- 
cant for  mental  hygiene  because  the  initial 
habits  of  adjustment  to  human  relation- 
ships are  being  formed  during  that  period. 
A  young  child  has  limited  resources  for 
coping  with  his  difficulties,  as  compared 
to  an  adult,  and  has  a  great  need  for  under- 
standing and  assistance.  Intense  and  un- 
solved conflicts  in  childhood  can  predis- 
pose an  individual  to  adjustive  difficulties 
throughout  his  life,  just  as  the  laboratory 
studies  of  experimental  neurosis  show  that 
'breakdown'  leads  to  a  continued  impair- 
ment of  the  ability  to  resolve  new  conflicts. 
The  relationships  of  the  parents  to  a  child 
are  the  basis  of  his  principal  early  adjust- 
ments, because  of  the  dependence  of  the 
child  on  his  parents,  the  greater  number  of 
contacts  he  has  with  them  and  the  emo- 
tional responses  that  the  parent-child  asso- 
ciation   evokes.      Since    parenthood    is    al- 


most universal,  progress  in  mental  hygiene 
depends  more  on  the  understanding  of  chil- 
dren by  parents  than  on  any  other  factor. 

Mental  hygienists  today  agree  that  the 
most  important  characteristics  of  the 
parent-child  relationship  are  warmth  and 
acceptance.  The  child  is  inevitably  de- 
pendent on  his  parents  (or  on  parent  sub- 
stitutes) and  experiences  serious  conflict  if 
he  feels  that  he  is  unwanted  or  unloved. 
This  condition  of  rejection,  leading  to  in- 
security for  the  child,  is  probably  the  most 
important  single  cause  of  subsequent  ad- 
justive difficulties.  Two  causes  of  parental 
rejection  of  children  can  be  distinguished. 
Some  parents  reject  children  because  they 
are  prevented  from  accepting  and  giving 
love  by  their  own  conflicts,  or  because  the 
child  represents  to  them  a  thwarting  of 
their  other  motives.  Such  parents  can  be 
helped  by  working  out  their  own  problems 
with  a  counselor,  but  cannot  be  aided  ap- 
preciably by  books  or  advice.  On  the 
other  hand,  many  parents  reject  children 
because  they  do  not  understand  what  a 
child  needs,  or  because  they  have  miscon- 
ceptions concerning  the  value  of  'disci- 
pline' and  'obedience'  in  character  forma- 
tion, or  because  they  overvalue  the  child's 
need  for  independence.  This  kind  of  re- 
jection is  more  easily  remediable. 

The  acceptance  of  a  child  by  his  parents 
can  be  defined  only  in  terms  of  the  parents' 
real  attitudes,  not  in  terms  of  specific  do's 
and  don't's  of  child  care.  For  example, 
there  can  be  no  rigid  rule  as  to  whether  a 
child  should  be  punished  or  not.  It  is 
true  that  continued  and  severe  pimishment 
almost  always  implies  rejection  and  results 
in  anxiety,  aggressive  antagonism  or  both. 
Occasional  and  appropriate  punishment, 
however,  may  not  be  rejecting.  It  may 
actually  relieve  a  child's  anxiety  when  he 
feels  guilty  over  his  act,  or  it  may  show 


Mental  Hygiene 


543 


Iiim  that  the  parent  cares  about  how  he 
behaves.  In  fact  a  parent  who  never  pun- 
ishes may  be  rejecting,  if  his  told  and  ex- 
cessive stress  on  independent  responsibility 
shows  that  he  does  not  care  what  happens 
to  the  child  or  what  the  child  does. 
Warmth  shows  itself  in  a  cumulative  num- 
ber of  small  expressions,  not  in  accordance 
with  any  set  of  rules. 

As  in  many  other  human  problems,  mod- 
eration is  essential  in  the  emotional  devel- 
opment of  children.  Spinach  may  be 
healthful,  but  a  whole  diet  of  it  is  certainly 
not.  Warmth  and  acceptance  must  be  dis- 
tinguished from  a  parental  submission 
which  fulfills  a  child's  every  whim,  and  is 
not  hygienic.  A  mother  who  smothers  a 
child  with  excessive  affection  is  usually 
fulfilling  some  exaggerated  need  of  her 
o^vn  and  is  not  warmly  accepting  the  child 
for  his  own  worth.  Acceptance  implies  not 
only  the  recognition  of  the  child's  need  for 
dependence  when  he  is  very  young,  but 
also  means  the  recognition  of  his  need  for 
independence  as  he  grows  older.  An  ac- 
cepted child  is,  therefore,  neither  retarded 
nor  pushed  ahead  in  the  development  of 
his  initiative  but  is  permitted  to  grow  to 
the  adult  state  at  his  own  pace.  The  child 
needs  freedom  as  well  as  security  and 
should  not  be  prevented  from  growing  up 
by  the  selfish  needs  of  a  dominating  or 
possessive  parent  who  wishes  to  maintain 
the  child's  dependence. 

Another  important  aspect  of  the  parent- 
child  relationship  is  its  consistency.  The 
child's  security  depends  on  the  depend- 
ability of  his  environment.  He  must  know 
what  he  can  count  on.  The  most  obvious 
inconsistencies  are  to  be  found  in  situa- 
tions in  which  a  child  is  praised  for  an  act 
at  one  moment  because  it  is  'cute*  and  pun- 
ished at  another  time  for  substantially  the 
same  act  because  the  parents  are  bored  or 


annoyed.  More  subtle  and  frequent  in- 
consistencies arise  when  a  child  is  expected 
to  he  independent  and  capable  in  one  re- 
spect, but  is  treated  as  immature  and  as 
requiring  rigid  supervision  in  another.  In- 
consistency prevents  a  child  from  learning 
his  role  in  the  family  and  from  developing 
a  clear  conception  of  his  own  indi\  iduality. 
It  may  result  in  conflict,  giving  rise  to 
either  anxiety  or  aggression. 

Another  requirement  for  good  mental 
hygiene  is  that  a  child  must  always  be  able 
to  talk  about  his  worries  and  problems 
with  a  parent,  without  fear  of  being  ridi- 
culed or  rebuffed.  A  confidential  relation- 
ship with  a  parent  has  the  value  of  psycho- 
therapy, in  that  the  child  can  express  his 
conflicts  and  get  better  insight  into  his  own 
adjustments.  Like  a  therapist,  a  good  par- 
ent recognizes  the  child's  problems  calmly 
and  also  does  not  rob  him  of  the  oppor- 
tunity to  work  them  out  on  his  own  terms. 

A  handicap  of  many  educated  parents, 
especially  of  those  who  have  studied  psy- 
chology, is  oversensitivity  to  a  child's  im- 
perfections. If  they  recognize  signs  of  anx- 
iety in  him,  or  defense  mechanisms,  they 
may  be  unduly  disturbed  about  their  own 
guilt  and  may  rush  in  to  make  amends, 
often  doing  more  harm  than  good  with 
their  emotional  fervor.  It  must  be  remem- 
bered that  a  full  acceptance  of  a  child  im- 
plies accepting  him  as  the  imperfect  hu- 
man being  that  every  one  of  us  is.  A  sense 
of  proportion,  and  more  than  a  touch  of 
humor,  will  in  these  circumstances  make  a 
satisfactory  therapist  of  the  wayward 
parent. 

Mental  Hygiene  for  Adults 

For  adults  who  ha%e  anxieties,  or  ^^•ho 
recognize  evidences  of  poor  adjustment  in 
themselves,  the  most  consuuctive  step  for 
mental    hygiene   is    to   secure    professional 


544 


Personal  Adjustment 


help,  from  psychiatrists,  consulting  psychol- 
ogists, college  counselors  or  other  qualified 
persons.  Lacking  such  facilities,  some  aid 
can  often  be  secured  from  friends  who  can 
be  -warm  but  objecii\e  listeners,  from  fam- 
ily physicians,  teachers  or  clergymen.  Rec- 
ognizing the  prevalence  of  the  mechanism 
of  projection,  people  who  are  having  trou- 
ble with  their  parents,  spouses,  children  or 
employers  ^vill  also  be  wise  to  seek  counsel- 
ing for  themsehes.  It  is  axiomatic  at  every 
child  guidance  clinic  that  the  parents  of  a 
problem  child  need  psychological  aid  as 
much  as  the  child  himself. 

Most  people  do  not  need  professional  as- 
sistance, but  can  get  some  benefit  from  fol- 
lowing some  principles  of  mental  hygiene, 
as  indeed  they  do  from  knowing  the  com- 
mon requirements  of  physical  health.  Just 
as  acceptance  is  basic  to  the  mental  hygiene 
of  childhood,  so  self-acceptance  is  a  funda- 
mental healthful  factor  in  adult  life.  Self- 
acceptance  does  not  mean  smug  com- 
placency, but  the  recognition  of  faults  and 
limitations  that  permits  your  living  in 
peace  with  yourself.  Most  defenses  and  ra- 
tionalizations are  used  for  their  individual 
adjustive  value  rather  than  for  their  social 
effect.  Self-acceptance  enables  an  individ- 
ual to  get  along  with  a  minimum  of  these 
hampering  types  of  behavior  and  thought. 
For  the  more  intellectually  inclined,  self- 
understanding,  through  a  study  of  the  psy- 
chology of  personal  adjustment,  may  con- 
tribute to  acceptance.  The  study  of  your 
own  behavior  can  become  morbid  if  it 
leads  you  to  feelings  of  inferiority.  The 
person  who  sees  himself  reflected  in  a  psy- 
chology book  may  be  reassured,  however, 
that  he  is  reading  of  common  human  na- 
ture, and  that  untold  numbers  of  other 
people,  who  are  functioning  effectively  in 
life,  show  the  same  mechanisms. 

Psychological  principles   and  experience 


point  to  a  number  of  other  generalizations 
about  adult  mental  hygiene.  Social  par- 
ticipation is  invaluable  for  mental  health, 
for  a  person  who  is  a  participant  in  a  group 
forgets  himself  and  directs  his  attention  to 
reality  and  to  the  present.  E%erybody 
needs  an  experience  of  some  success  in  self- 
expression.  Many  obtain  it  in  their  work, 
others  in  sports  and  hobbies.  A  rhythm  of 
■work,  recreation  and  rest  breaks  up  non- 
adjustive  responses  and  gives  you  an  op- 
portunity to  attack  problems  more  effec- 
tively when  the  inhibitions  arising  from 
continued  effort  have  been  lessened. 

A  very  general  principle  of  mental  hy- 
giene is  to  apply  the  technique  of  scien- 
tific method,  or  of  rational  problem  solv- 
ing, to  personal  matters.  Many  people 
who  are  not  markedly  maladjusted  rush 
into  their  interpersonal  relationships  with 
an  unthinking  abandon  that  they  would 
condemn  if  it  were  applied  to  investing 
money,  building  a  house  or  even  to  buying 
a  new  suit  of  clothes.  The  technique  of 
defining  the  problem,  gathering  the  data, 
making  hypotheses  and  checking  the  results 
can  profitably  be  applied  by  intelligent 
persons  to  the  management  of  their  own 
lives. 

REFERENCES 

1.  Freud,  S.  Psychopathology  of  everyday  life. 
The  basic  iL'ritings  of  Sigmund  Freud.  New 
York:  Modern  Library,  1938. 

Slips  of  the  tongue,  forgetting  of  names  and 
similar  e\ents  illustrate  the  common  'abnor- 
malities' found  in  normal  people. 

2.  Homey,  K.  The  neurotic  personality  of  our 
time.     New  York:  Norton,  1937. 

A  modified  psychoanalytic  theory,  with  em- 
phasis on  cultural  conflicts  as  sources  of  mal- 
adjustment. 

3.  Hunt,  J.  McV.  (Ed.).  Personality  and  the  be- 
havior disorders.  2  vols.  New  York:  Ronald 
Press,  1944. 


References 


543 


These  Ivvo  voluriies,  llie  work  ol  loily  col- 
laborators from  psychology,  niedicJDe,  anthro- 
pology and  allied  fields,  give  the  most  compre- 
hensive survey  of  personality  and  its  ahnor- 
malities. 

1.  Landis,  C,  and  IJowles,  M.  M.  Textbook  of 
abnormal  psychology.  New  Vork:  Macmillaii. 
1946. 

An  excellent  description  of  mental  disorders, 
their  exj^lanation  and  treatment. 

5.  Lewin,  K.  Environmental  forces.  In  C.  Murchi- 
son     (Ed.)  ,    A    handbook    of    child    psychology. 

(2nd  ed.)     Worcester,   Mass.:    Clark    University 
Press,  1933.     Chap.   14. 

A  clear  introduction  to  the  author's  topolog- 
ical theory  of  personality. 

6.  Leivin,  K.  Behavior  and  development  as  a 
finiction  of  the  total  situation.  In  L.  Car- 
michael  (Ed.),  Manual  of  child  psychology. 
New  York:  Wiley,  1946.     Chap.  16. 

The  'field  theory'  or  topological  approach  to 
personality  and  conflict,  considered  as  an  inter- 
action between  the  individual  and  his  environ- 
ment. 

7.  Maslow,  A.  H.,  and  Mittelmann,  B.  Principles 
of  abnormal  psychology.  New  York:  Harper, 
1941. 

A  good  introduction  to  abnormal  psychology 
which  skillfully  blends  the  experimental,  ps\- 
choanalytic  and  cultural  approaches. 

8.  Masserman,  J.  H.  Behavior  and  neurosis.  Chi- 
cago: University  of  Chicago  Press,  1943. 


Rejjorls  lA  ingenious  experimcntx  with  lati 
clarify  many  problems  of  the  production,  tf- 
feels  and  cure  of  conflids. 

9.  McKinney,   F.     Psychology    of  personal  adju.il- 
menl.     New  York:   Wiley,  VMl. 

Recommended  to  the  college  student  who 
.seeks  hel[>  for  his  own  academic,  personal  and 

s(i(ial    adjustments. 

10.  Rogers,  C.  R.  Counseling  and  psychotherapy. 
Boston:  Houghton  Mifflin,  1912. 

The  book  gives  an  excellent  idea  of  the  non- 
directive,  client-centered  method  in  interview- 
ing by  means  of  a  full  description  of  a  series  of 
eight   interviews. 

11.  Rogers,  C.  R.,  and  Wallen,  J.  L.  Counseling 
u'ith  returned  seri'icemen.  New  York:  .Mc- 
Graw-Hill,   1946. 

One  of  the  clearest  elementary  descriptions 
of  personal  counseling,  applicable  to  others  as 
well  as  to  servicemen. 

12.  Shaffer,  L.  I".  The  psychology  of  adjustment. 
Boston:   Houghton  Mifflin,  1936. 

An  account  of  the  social  and  individual  ad- 
justment problems  of  normal  people,  from  the 
point  of  view  of  objective  psychology. 

13.  Shaffer,  L.  F.  Abnormal  psychologv.  In  J.  P. 
Guilford  (Ed.),  Fields  of  ps\cholog\.  New 
York:  Van  Nostrand,  1940.  Chaps.  9,  10  and 
11. 

The  three  chapters  give  a  brief  and  clear 
survey  of  the  significance,  causes  and  varieties 
of  abnormal  behavior. 


CHAPTER 


23 


Vocational  Selection 


THE  individual's  basic  problem  in  life  is 
his  adjustment  to  the  circumstances  in 
which  life  places  him,  the  personal  adjust- 
ment which  makes  him— when  it  succeeds— 
what  is  called  a  'well-adjusted  person.'  In 
the  preceding  chapter  we  have  considered 
the  psychological  mechanisms  by  which 
tliat  adjustment  takes  place. 

Within  the  total  area  of  his  life,  the  in- 
(li\'idual  usually— especially  if  he  is  a  man 
—has  to  earn  his  living.  He  needs  a  job 
and,  unless  there  is  unemployment,  he  has 
a  job.  That,  however,  is  not  the  same 
thing  as  having  the  right  man  in  the  right 
job.  Some  men  are  better  fitted  for  one 
kind  of  work  than  another;  different  men 
have  different  aptitudes.  And,  if  the  men 
are  properly  fitted  into  their  jobs,  everyone 
benefits— the  employee,  the  employer  and 
society. 

The  employee  benefits  because  either  his 
work  is  easier  or  his  production  and  pay 
are  greater.  Consequently  his  morale  and 
job  satisfaction  are  likely  to  be  better.  The 
employer  benefits  because  he  gets  more 
work  done.  Either  the  worker  produces 
more  per  hour  or,  because  good  morale  re- 
duces turnover,  absenteeism  and  illness,  the 
worker  produces  more  per  year.  Society 
benefits  because  maximal  efficiency  and  the 
maximal  contentment  are  got  by  the  best 
adjustment  of  men  to  their  jobs. 


Both  the  recent  World  Wars,  with  their 
shortages  of  manpower,  have  made  it  clear 
that  aptitudes  and  skills  are  part  of  a  na- 
tion's limited  resources.  They  must,  when 
short,  be  rationed  and  used  with  planned 
efficiency.  This  idea  in  itself  is  not  new. 
As  long  ago  as  1884  Francis  Gallon  was 
sponsoring  a  plan  to  inventory  the  brains 
and  abilities  of  all  Englishmen  so  that  his 
Government  might  know  what  resources  it 
had  for  use  in  the  promotion  of  British 
civilization.  (He  feared  that  the  British 
were  not  so  able  as  the  ancient  Greeks  and 
hoped  that,  if  the  facts  were  known,  se- 
lective parenthood  might  do  something 
about  the  matter.)  The  Second  World 
War  with  its  manpower  shortage  forced  at- 
tention to  this  basic  problem  of  the  use  of 
human  resources,  and  now  vocational  guid- 
ance and  selection  are  used  wherever  prac- 
ticable. 

Since  this  development  has  grown  out  of 
psychological  testing  and  is  itself  an  impor- 
tant phase  of  modern  applied  psychology, 
the  present  chapter  is  devoted  to  an  ex- 
planation of  how  in  business  and  industry, 
and  even  in  the  professions,  the  right  man 
can  be  got  into  the  right  job. 

Contentment  and  satisfaction  are  not  the 
proper  criteria  to  use  for  this  selection  since 
employee  and  employer  may  easily  not  be 
satisfied  with  the  same  performance.     For 


This  chapter  was  prepared  by  Carroll  L.  Shartle  of  Ohio  State  University. 

546 


Criteria 


547 


example,  a  worker  may  consider  that  he  is 
making  a  satislaclory  vocational  adjust- 
ment. He  feels  that  he  is  earning  a  good 
living,  he  likes  the  kind  of  work  and  the 
work  surroundings,  and  he  considers  he  has 
reasonable  security  in  his  position.  On  tlie 
other  hand,  his  employer  may  have  quite  a 
difiEerent  view  of  the  matter  and  reports 
that  the  worker,  although  steady  and  reli- 
able, is  a  low  producer  compared  with 
others.  If  the  employee  is  then  discharged, 
his  union  may  present  evidence  that  he  is  a 
success.  In  an  arbitrated  dispute  it  may 
be  ruled  that  the  employee  was  after  all 
successful  and  must  be  retained  by  the  em- 
ployer. The  employer,  however,  remains 
dissatisfied.  It  ought  to  be  possible  for  all 
concerned  to  measure  success  more  cer- 
tainly. 

Suppose  we  were  making  an  occupa- 
tional follow-up  of  graduates  of  a  school. 
Should  we  consider  the  aforementioned 
worker  successful  in  his  chosen  occupation? 
For  such  decisions  criteria  must  be  set  up. 
Let  us  see  what  they  may  be. 

CRITERIA 

In  studies  of  workers  and  their  jobs  a 
number  of  indices  or  criteria  of  success  are 
usually  explored.  Sometimes  a  single  cri- 
terion of  success  is  chosen.  In  other  cases 
two  or  more  criteria  are  utilized,  either 
singly  or  in  combination.  For  example, 
success  in  selling  a  product  may  be  judgeci 
by  the  number  of  new  steady  customers  ob- 
tained during  a  given  length  of  time,  or 
the  criterion  may  be  put  in  terms  of  total 
sales  or  it  may  be  a  combination  of  both 
variables. 

To  a  great  extent  the  soundness  of  voca- 
tional selection  depends  upon  Vow  well  the 
criteria  of  success  have  been  developed  and 
how  they  are  interpreted  in  the  applica- 


tions of  research  fnidings  to  vocational 
guidance,  vocational  selection,  training, 
promotion  and  other  personnel  procedures. 
For  example,  tests  may  be  developed  to 
measure  the  human  characteristics  required 
in  a  given  occupation.  The  tests  are  ad- 
ministered to  persons  in  the  occupation. 
The  scores  of  persons  within  the  occupa- 
tion who  are  most  successlul  are  then  com- 
pared witii  those  persons  less  successful.  Is 
this  a  good  method?  It  is,  if  wc  know 
how  to  assess  success.  The  criteria  of  suc- 
cess are  crucial.  Let  us  see  what  some  of 
them  are. 

Criteria  of  Vocational  Success 

Every  person  has  his  own  set  of  values 
that  he  considers  important  in  judging  vo- 
cational success.    Here  are  some  of  them. 

Productivity.  How  much  does  the  worker 
produce  per  hour,  per  day  or  per  month? 
Wide  differences  are  frecjuently  found 
among  workers  in  any  gi\en  job.  Figure 
239  shows  the  distribution  of  sixty-two 
card-punch  machine  operators  according  to 
their  criterion  scores,  the  average  number 
of  cards  punched  per  hour. 


14 
12 

?i  10 


■■I"  I  1   1   1   1  1   1 

:        r 

"  n  1  1  1  1  1  1 

1  1  1  1  1  1  1  1 

28     42      56      70      84      98     112    126    140 
Average  number  of  cards  punched  per  hour 

FIGURE    239.       DISTRIBUTION    OF    CRITERION    SCORES 
OF    SIXTY-TWO    CARD-PUNCH    MACHINE    OPER.\TORS 

The  criterion  scores  are  a\erage  number  of  cards 
punched  per  hour. 


548 


Vocational  Selection 


Errors  and  accidents.  Mistakes  are  often 
costly  and,  when  adequate  records  of  mis- 
takes or  errors  are  a\ailable,  they  may  be 
used  as  one  factor  in  judging  success.  Ac- 
cidents are  also  sometimes  used  as  a  cri- 
terion.. One  worker  may  have  several  times 
as  many  accidents  during  a  given  period  as 
another  worker  in  the  same  job. 

Tenure.  \Vorkers  who  are  unsuccessful 
in  a  job  may  be  discharged  or  may  leave 
of  their  own  accord.  It  is  assumed  in  some 
occupational  studies  that,  if  a  person  re- 
mains in  an  occupation  for  se\eral  years, 
he  is  successful  in  it.  For  example,  in 
standaidizing  an  employment  question- 
naire, several  hundred  persons  in  each  of 
several  occupations  filled  in  the  items.  It 
was  decided  to  use  five  years  of  continuous 
experience  in  the  occupation  as  the  cri- 
terion for  selecting  the  subjects. 

Attendance.  ^Vorkers  who  are  frequently 
absent  from  a  job  or  are  tardy  for  work 
may  be  judged  less  successful  than  others. 
The  employer  wishes  continuity  and  pre- 
dictability. MoreoAer,  frequent  absence 
suggests  discontent.  Even  illness  can 
sometimes  be  had  by  wishing  (p.  535). 

Salary.  Salary  received  has  been  used  as 
a  criterion  of  success,  particularly  in  fol- 
low-up studies  of  college  graduates.  Per- 
sons, in  occupations  which  have  similar 
wage  structures  and  where  promotion  is 
open  to  all,  have  been  evaluated  in  terms 
of  salary  attained  after  a  given  length  of 
time  on  the  job.  The  individual  worker 
often  uses  salary  as  a  criterion  in  judging 
his  own  success.  He  may  compare  him- 
self with  others  in  his  occupation  or  with 
associates  in  other  occupations.  His  wife 
is  likely  to  make  similar  comparisons. 

Social  values.  A  worker  may  evaluate 
his  vocational  success  personally  in  terms  of 
certain  values  outside  of  salary.  The  social 
position    associated    with    various    occupa- 


tions is  part  of  the  psychological  pay. 
\Vhat  he  lacks  in  dollars  he  gains  in  status. 
A  worker  also  likes  to  feel  that  he  is  con- 
tributing something  that  society  wants. 
Such  values  frequently  come  up  in  voca- 
tional counseling  and  may  constitute  a 
good  reason  for  a  worker's  desire  to  change 
his  occupation  to  one  in  which  he  believes 
his  status  will  be  better  or  where  he  be- 
lieves he  can  make  a  greater  social  contri- 
bution. 

Supewision.  A  man  may  be  highly 
skilled  in  performing  most  of  the  tasks  in 
his  occupation,  yet  fail  to  work  satisfac- 
torily under  supervision.  He  may  have 
conflicts  with  his  supenisor.  Or  the  job 
may  include  the  supervision  of  others,  and 
the  worker  may  fail  in  this  respect.  In  a 
study  made  of  jobs  held  by  psychologists, 
proficiency  in  supervision  was  indicated  as 
an  important  criterion  of  success  in  many 
of  the  jobs. 

Cooperation  witli  associates.  Closely  re- 
lated to  supervision  is  proficiency  in  work- 
ing efl:ecti\  ely  with  others.  A  man  may  be 
highly  successful  in  all  phases  of  his  occu- 
pation but  fail  to  work  congenially  as  one 
of  a  group.  Although  his  individual  pro- 
ductivity is  high,  he  may  reduce  cooperative 
activity  and,  for  that  reason,  be  judged  rela- 
tively unsuccessful  as  an  overall  worker. 
These  social  factors  often  receive  greater 
■\veight  as  a  criterion  of  success  than  pro- 
ductiveness and  tenure.  Many  employers 
believe  that  deficiencies  in  skill  can  be 
remedied  bv  on-the-job  training,  but  that 
it  is  difficult  or  impossible  to  train  an  un- 
cooperative employee  to  work  congenially 
with  his  associates. 

Choice  of  Criterion 

In  problems  of  occupational  adjustment 
the  choice  of  a  criterion  or  criteria  of  suc- 
cess depends  upon  many  things.     We  may 


choice  of  Criterion 


549 


obtain  an  idea  ol  some  ol  llu:  ladois  that 
must  be  considered  [vom  ilie  lollowing  dis- 
cussion of  sclt-evaluation,  eniployer-evahi- 
ation  and  kind  of  tasks. 

Self-evaluation.  One  of  the  most  fre- 
quent evaluations  is  made  by  the  worker 
himself.  He  wants  to  know  how  successful 
or  how  unsuccessful  he  is  in  his  job.  He 
attempts  to  appraise  Ins  own  progress  not 
only  in  his  present  job  but  also  in  regard 
to  his  overall  occupational  plans.  Such 
appraisals  are  usually  highly  subjective  for 
they  are  likely  to  be  based  upon  limited 
factual  information.  The  worker  hesi- 
tates to  ask  his  supervisor  for  a  frank  ap- 
praisal of  his  performance  or  to  seek  ad- 
vice from  a  competent  vocational  coun- 
selor. Supervisors  are  usually  negligent  in 
telling  their  subordinates  exactly  what  is 
expected  of  them  and  how  well  they  are 
progressing  in  the  various  phases  of  their 
jobs.  It  also  may  happen  that  events  cause 
a  worker  to  change  his  vocational  plans 
and  to  apply  a  different  set  of  values  in  at- 
tempting to  judge  his  own  progress.  For 
example,  the  knowledge  that  a  close  friend 
has  just  received  a  substantial  raise  in  sal- 
ary may  cause  a  w^orker  to  believe  that  he 
is  quite  unsuccessful  and  should  change  to 
some  other  kind  of  work.  It  is  indeed  sel- 
dom that  any  worker  lists  and  attempts  ob- 
jectively to  consider  all  the  factors  which 
are  important  in  judging  his  own  occupa- 
tional achievement.  He  needs  the  help  of 
a  counselor. 

A  vocational  counselor  should  be  well  in- 
formed concerning  the  various  criteria  fre- 
quently considered  by  workers  as  well  as 
the  criteria  used  by  employers.  The  coun- 
selor can  thus  aid  the  counselee  in  evalu- 
ating his  adjustment  more  objectively  or 
in  foreseeing  the  criteria  which  might  be 
applied  in  the  future  if  he  entered  a  gi\en 
occupation. 


/•'.infjloycr  cvahiulion.  I  lie  <  luj^loycr  fre- 
quently sets  up  criteria  for  evaluating  job 
performarue.  Sometimes  he  uses  rating 
scales,  which  are  fdlcd  in  by  the  supervisrjr 
at  periodic  intervals  (p.  414).  The  results 
may  be  used  as  evidence  in  determining 
who  sliall  be  promoted,  laid  off,  given  ad- 
tlitional  training,  transferred  or  demoted. 
Table  XXX  (jj.  .550)  reproduces  a  rating 
form  used  by  one  employer  for  this  purpose. 

Employers  also  use  rating  scales  in  stand 
ardizing  tests  to  discover  the  relationship  of 
test  scores  to  job  performance.  Production 
records,  accident  records  and  the  apprais- 
als of  samples  of  work  are  likewise  em- 
ployed for  the  standardization  of  tests  and 
are  generally  considered  more  objective 
and,  therefore,  better  measures  than 
ratings. 

Kinds  of  tasks.  The  nature  of  the  tasks 
in  the  job  necessarily  affects  the  kind  of 
criteria  which  are  available.  In  some  oc- 
cupations accidents  occur  so  rarely  that 
they  are  not  a  factor.  In  others  the  work- 
ers perform  their  tasks  in  groups,  so  that 
individual  production  records  are  not  a\ail- 
able.  Sometimes  a  ^vork-sample  perform- 
ance test  is  set  up  to  allow  the  workers  to 
perform  for  appraisal  a  sample  of  tasks 
that  occin-  in  the  job.  Each  Avorker,  of 
course,  performs  the  same  set  of  tasks  under 
controlled  conditions.  This  method  has 
been  used  for  establishing  a'iteria  for  sens- 
ing machine  operators,  typists  and  package 
wrappers. 

For  standardizing  tests  an  objective  cri- 
terion is  desirable.  AVhen  that  is  not  pos- 
sible, ratings  by  supervisors  must  be  used. 
If  two  or  more  criteria  are  available,  tlie 
single  best  index  of  success  is  used  or  tlie 
several  criteria  are  combined.  Occasion- 
ally two  criteria  may  be  used  independ- 
entlv.  For  example,  in  a  study  of  bus 
operators,  both  the  supen'isors*  ratings  of 


550  Vocational  Selection 

TABLE  XXX 

Rating  Form  for  Vocational  Counselor 

^Jarne — — - Date  employed 

(Check  the  one  item  in  each  case  which  best  describes  the  worker.) 

1.   How  well  informed  is  this  counselor  concerning  occupational  information,  test  score  interpretation  and  other 
technical  subject  matter  necessary  for  satisfactory  performance? 

.Fairly  well  informed  but  needs  more  background. 

About  as  well  informed  as  one  would  expect  for  the  work. 

Quite  deficient,  needs  considerable  training. 
Excellent  knowledge,  none  could  be  better. 


Comments- 


2.   In  face  to  face  situations  how  well  does  this  counselor  handle  clients  and  their  problems? 

Needs  considerably  more  training  and  experience. 

^One  of  the  best  in  this  phase  of  the  work. 

Does  an  ordinary  job. 

Can  be  counted  upon  to  do  better  than  average. 

Comments — ■ 


.3.  In  maintaining  case  records  how  successful  is  this  counselor  in  understanding  and  following  good  practices? 

Records  are  complete  and  accurate  at  all  times. 

Needs  considerably  more  training. 

Does  better  than  the  average. 

Records  are  fairly  well  kept. 


Comments- 


How  do  you  size  up  this  counselor  in  following  through  and  maintaining  continued  and  effective  counseling 
relationships  with  clients  until  the  cases  are  closed? 

Does  reasonably  well. 

One  of  the  best. 

Needs  more  supervision  on  this  part  than  most  other  counselors. 

Seldom  can  be  trusted. 


Com  men  ts- 


5.  What  is  your  overall  appraisal  of  this  counselor's  work  performance  and  prospects  in  the  organization? 

Promising  but  needs  more  experience. 

Is  ready  for  promotion  now. 

Nr>t  very  satisfactory,  should  be  encouraged  to  try  some  other  job. 
.'^bout  an  average  worker 


Comments- 


Date  Supervisor 


Job  Analysis 


551 


performance  and  the  accident  records  were 
available.  In  standardizing  selection  tests 
the  overall  rating  of  performance  showed  a 
satisfactoiy  correlation  with  one  set  of  tests 
and  the  accident  records  were  positively 
related  to  another  test.  In  the  selcciion 
process  applicants  were  required  to  pass 
both  sets  of  measures.  The  personnel  of- 
fice hoped  in  this  way  to  get  men  who 
would  have  both  high  performance  ratings 
and  good  accident  records. 

JOB    ANALYSIS 

Two  terms  are  frequently  used  in  voca- 
tional psychology;  they  are  worker  analysis 
and  job  analysis.  Worker  analysis  refers  to 
a  study  of  workers  in  jobs  either  individ- 
ually or  in  groups.  The  workers  may  be 
given  tests  and  interviews,  and  their  back- 
grounds studied  in  order  to  discover  their 
characteristics  both  on  and  off  the  job. 

In  job  analysis  the  job  is  studied  by  ob- 
serving what  the  workers  do,  by  question- 
ing supervisors  and  workers  and  by  observ- 
ing how  the  job  fits  into  the  organization 
and  structure  of  the  particular  office  or 
plant.     The  characteristics  of  the  workers 


themselves  are  not  studied,  although  tlu 
analyst  may  estimate  what  worker's  tharac 
teristics  appear  important  for  the  job.  A 
job  analysis  is  made  to  get  the  picture  ol 
the  duties,  the  tools  needed  and  machines 
used,  the  hiring  re(|uirenient-s,  the  working 
conditions,  the  kind  of  supervision  receivfd 
and  the  apparent  worker  characteristi(>- 
that  are  important  for  success  in  the  job. 
The  job  analysis  should  precede  a  stud\ 
of  the  workers,  for  it  gives  the  essential 
background  which  the  analyst  must  have  tf) 
know  what  tests  or  other  measures  can  b( 
applied  in  a  worker  analysis. 

In  analyzing  a  job  the  investigator  may 
actually  learn  the  duties  himself,  becoming 
one  of  the  workers,  or  he  may  act  as  an 
assistant  to  the  worker  whose  position  is 
being  analyzed,  or  he  may  be  only  an  ob- 
server. The  first  two  methods  are  em- 
ployed when  detailed  analysis  is  wanted, 
as  in  the  development  of  testing  procedures 
to  measure  the  aptitudes  required  in  an 
occupation.  In  other  instances,  job  anal- 
ysis may  be  very  brief,  being  only  such  as 
is  necessary  to  develop  definitions  or  short 
descriptions  of  jobs.  Sometimes  a  job  speci- 
fication is  developed.     That  is  a  descrip- 


TABLE  XXXI 

Job  Specification  for  Personnel  Assistant 

Summary  of  Duties:  After  arrangements  have  been  made  by  supervisor,  analyzes  jobs  by  observation  of  worker, 
by  obtaining  information  from  foremen  and  workers  and  other  plant  personnel.  According  to  prescribed  procedure, 
writes  up  each  analysis  and  presents  to  supervisor  for  approval.  Administers  group  tests  to  employed  workers, 
scores  tests  and  performs  statistical  analysis  including  computation  of  means,  standard  deviations  and  product- 
moment  correlations. 

Minimum  Requirements 

Educational:  Graduate  of  an  accredited  college  or  university  with  at  least  20  semester  hours  in  psychology 
including  one  or  more  courses  in  tests  and  measurements  and  statistics. 

Previous  Experience:  None.    Age:  22-25.     Sex:  Male. 

Special  Characteristics:  Must  be  able  to  write  understandably  and  to  work  congenially  with  others  in  obtaining 
information. 

Starting  Salary:  $175.00  per  month.    Hours  per  week:  40. 

Promotional  Possibilities:  Top  salary  $225.00  after  two  years  on  the  job.  Ph.D.  degree  required  tor  next  highei 
position. 


552 


Vocational  Selection 


tion  in  which  the  hiring  requirements  are 
listed  in  some  detail,  ahhough  the  descrip- 
tion of  the  job  is  fairly  brief.  Table  XXXI 
reproduces  specification  lor  the  job  of  per- 
sonnel assistant. 

NATURE    OF    OCCUPATIONS 

You  begin  to  get  some  idea  of  the  dif- 
ficulty of  vocational  guidance  when  you 
discover  how  many  different  kinds  of  jobs 
there  are. 

A  job  is  defined  as  a  group  of  similar  po- 
sitions, and  an  occupation  as  a  group  of 
similar  jobs.  There  are  around  30,000  oc- 
cupations in  the  United  States.  Of  course, 
the  number  of  jobs  is  many  times  that 
number,  and  there  are  as  many  positions 
as  there  are  employed  workers— 58  million 
in  1947. 

Dictionary  of  Occupations 

Based  upon  job  analyses,  about  21,000 
( ivilian  occupations  have  been  classified 
and  defined.  The  classification  structure 
and  the  definitions  have  been  developed 
by  the  United  States  Employment  Service 
and  published  in  a  document  called  the 
Dictionary  of  Occupational  Titles. 

The  occupations  defined  in  the  Diction- 
ary are  grouped  under  seven  major  break- 


downs. Table  XXXII  shows  the  major 
groups  and  the  number  of  occupations  de- 
fined in  each. 

Census  Classification 

Ci\  ilian  occupations  have  been  classified 
ilirough  the  years  by  the  Bureau  of  Censtis. 
This  classification  uses  occupational  and  in- 
dustrial titles  only  and  does  not  include 
definitions,  since  in  taking  the  federal  cen- 
sus the  respondents  are  not  asked  to  list 
the  duties  of  the  job  in  which  they  are  em- 
ployed. Table  XXXIII  shows  the  major 
breakdown  of  the  census  classification  and 
the  total  number  of  employed  workers  in 
each  group. 

The  Army  and  Navy  have  also  developed 
definitions  of  their  various  ntilitary  spe- 
cialties. 

Characteristics  of  Occupations 

In  studying  the  characteristics  of  occupa- 
tions it  is  found  that  occupations  may  be 
grouped  in  many  types  of  classifications. 
Such  special  groupings  are  sometimes  called 
occupational  families.  For  example,  occu- 
pations may  be  grouped  according  to  the 
hiring  specifications,  types  of  machines 
used,  special  abilities  required  and  other 
characteristics. 

A  study  of  the  characteristics  of  occupa- 


TABLE  XXXII 

Major  Occupational  Groupings  and  the  Number  of  Occupations  Defined  under  Each  in  Dictionary  of 

Occup.^TioNAL  Titles 

Number  of  Occupations 
Major  Occupational  Groups  Defined 

Professional  and  managerial  occupations  1,837 

Clerical  and  sales  occupations  1,454 

Service  occupations  557 

Agricultural,  fishery,  forestry  and  kindred  occupations  297 

Skilled  occupations  3,820 

Semiskilled  occupations  7,819 

Unskilled  occupations  6,016 


Total 


21,800 


Trade  Knowledge  and  Performance 


553 


TAHLK  XXXIII 

MaJOK    CkNSUS    GROtll'INfiS    AND    NwMHER    OF    VVoKKF.RS    HmIM.OVF.D   IN    F.ACH    (■19'K)) 


Experienced  Labor  Force 
Professional  and  semiprofessional  workers 
Proprietors,  managers  and  officials,  including  farm 
Clerical,  sales  and  kindred  workers 
Craftsmen,  foremen  and  kindred  workers 
Operatives  and  kindred  workers 
Protective  service  workers 
Service  workers,  except  protective 
Laborers,  including  farm 
Occupation  not  reported 

Employed  (except  emergency  work) 

tions  shows  that  the  majority  of  them  do 
not  have  any  specific  educational  require- 
ment although  the  ability  to  read  and  write 
is  required  for  some  of  them.  About  half 
of  occupations  do  not  require  previous 
work  experience  for  entrance;  more  than 
half  require  an  unusual  amount  of  dexter- 
ity of  hands,  arms  or  fingers;  and  about  a 
third  are  occupations  requiring  unusual 
strength.  About  47  per  cent  of  the  occupa- 
tions involve  the  use  of  machines,  and 
about  the  same  proportion  involve  the  use 
of  tools.  Unusual  keenness  of  vision  is  es- 
sential in  about  20  per  cent,  and  color  dis- 
crimination is  important  in  about  4  per 
cent  of  the  occupations. 

About  55  per  cent  of  the  working  popu- 
lation are  employed  as  machine  operators, 
service  workers  and  laborers,  and  about  7 
per  cent  in  the  professional  and  semipro- 
fessional  occupations. 

These  figures  outline  the  American  scene. 
They  do  not  show  the  resources  of  the 
United  States  in  skills  and  aptitudes,  but 
they  show  its  needs.  To  maintain  produc- 
tion requires  plenty  of  manual  dexterity 
and  quite  a  little  strength,  but  not  so  much 
education.  It  is  with  such  qualities  that 
the  personnel  expert  concerns  himself. 


'I'rjtal 

52,022,158 
.3, 549,. 154 
9,026,984 
S,. 107, 490 
5,877,094 
9,415,901 

740,876 
5,517,194 
8,605,256 

982,009 

45. 166. OSS 


Male 

39,481,880 

2,006,073 

8,443,063 

4,809,619 

5,751,857 

7,009,752 

733,420 

1,900,476 

8,139,309 

688,311 

34,027.905 


Female 

12,540,278 

1,543,281 

583,921 

3,497,871 

125,237 

2,4^J6,)49 

7,456 

3,616,718 

465,947 

293,698 

II .138.178 


TRADE    KNOWLEDGE    AND 
PERFORMANCE 

The  measurement  of  trade  knowledge 
and  j^erformance  has  been  applied  in  in- 
dustry, education  and  government  to  aid 
in  the  selection  and  assignment  of  persons 
to  jobs  which  require  previous  experience 
or  a  specific  skill.  "We  have  for  use  both 
trade  tests  and  performance  tests. 

Oral  Trade  Tests 

Oral  trade  tests  were  de\eIoped  by  the 
government  for  both  World  Wars  to  aid  in 
evaluating  the  extent  of  kno^vledge  in  cer- 
tain skilled  trades,  such  as  automobile  me- 
chanic or  bartender.  (The  armed  services 
do  have  uses  for  bartenders— with  a  change 
of  name.)  These  tests  measine  kno^vledge 
only,  and  thus  have  definite  limitations. 
Kno^vledge  is  not  skill.  A  man  may  pick 
up  a  good  deal  of  knowledge  about  an 
occupation  from  reading  or  conversation. 
It  is  also  true  that  a  highly  skilled  -^vorker 
may  be  handicapped  in  his  skill  A\ith  lan- 
guage and  do.  poorly  on  tire  test  for  that 
reason.  Many  a  skilled  craftsman  does  not 
quite  know  how  he  does  what  he  does.  He 
has  his  required  skills  biu  cannot  \erbalize 
them.     Or  he  kno\\s  Avhat  he  does  ^vitliout 


554 


Vocational  Selection 


being  able  to  state  the  general  rule.  He 
cannot  tell  you  that  the  proper  distance  be- 
tween the  points  on  a  timer  is  twenty  thou- 
sandths of  an  inch,  but  he  does  know  that 
a  timer  will  work  it  you  separate  the  points 
by  the  thickness  of  a  tobacco  tin. 

Oral  trade  tests  are  composed  of  a  series 
of  trade  questions  which  have  been  care- 
fully worded  and  tried  out  on  a  group  of 
subjects.  The  questions  are  put  in  simple 
language  and  in  such  a  way  that  the  correct 
answer  can  be  given  in  a  word  or  two.  For 
example,  it  would  be  quite  useless  for  a  psy- 
chologist or  interviewer  to  ask  an  applicant 
to  describe  how  he  would  build  a  wooden 
structure.  The  answer  would  be  long  and 
detailed,  and  the  interviewer,  unless  he  was 
a  skilled  carpenter,  could  not  judge  its  ade- 
quacy. On  the  other  hand  a  specific  ques- 
tion, such  as,  "What  do  you  call  the  timbers 


that  brace  the  studs?"  could  be  evaluated 
at  once  by  an  intei^viewer  if  he  had  a  key 
of  correct  answers.  (The  correct  answer  is, 
"Spacers,"  and  in  some  localities  "Bridgers" 
is  just  as  good.) 

Oral  trade  questions  are  standardized  by 
administering  them  to  skilled  workers  in  a 
trade,  to  learners  and  helpers  and  to  work- 
ers in  closely  related  occupations  who  might 
in  their  work  gain  knowledge  of  the  trade. 

Table  XXXIV  shows  how  a  set  of  fifteen 
oral  trade  questions  differentiated  expert 
machinists  from  apprentices  and  helpers, 
and  apprentices  and  helpers  from  workers 
in  related  occupations.  The  median  scores 
are  shown  by  rows  of  x's.  There  is  an  over- 
lapping of  the  scores  between  the  experts 
and  the  apprentices  and  helpers,  but  the 
poorest  of  the  experts  scored  higher  than  the 
best  of  the  related  group.    In  the  standard- 


TABLE  XXXIV 

Distribution  of  Scores  on  Oral  Trade  Test  Questions 


Score 

Expert  Machinists 
(Total:  101) 

Apprentices 
and  Helpers 
(Total:  50) 

Related  Group 
(Total:  50) 

15 

xxxxxxxxxxxxxxxxxx 

14 

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx  * 

13 

xxxxxxxxxxxxxxxxxxxx 

X 

12 

xxxxxxxxxxx 

XX 

11 

xxxxxxxxx 

X 

10 

xxxxx 

XX 

9 

X 

XXXX 

8 

XXX 

XX 

7 

XXX 

6 

X 

5 

xxxxx 

X 

4 

xxxxx  * 

XX 

3 

XXX 

XX 

2 

XXXXXX 

XXXXX 

1 

XXXXX 

XXXXXXXX 

0 

XXXXXXXXXX 

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX  * 

Median  score. 


Vocational  Potentiality 


555 


ization,  each  question  was  evaluated,  and 
only  those  questions  were  retained  which 
significantly  differentiated  both  apprentices 
and  helpers  and  the  related  group  Ironi 
the  experts. 

A  satislactory  oral  trade  question  is  usu- 
ally answered  correctly  by  at  least  80  per 
cent  of  the  experts,  by  not  more  than  50 
|)er  cent  ol'  tiie  apprentices  and  helpers  and 
by  less  than  10  per  cent  of  the  related 
group. 

Written  tests  have  also  been  developed 
to  measure  occupational  proficiency.  Like 
the  trade  tests  they  are  primarily  tests  of 
knowledge  about  the  occupation.  Civil 
service  examinations  are  frequently  of  this 
type- 
Performance  Tests 

Performance  trade  tests  are  a  sample  of 
the  job  performance.  Stenographic  and 
typing  tests  and  performance  tests  for  weld- 
ers, automobile  drivers  and  aircraft  pilots 
are  examples  of  performance  tests  which 
are  frequently  used. 

Performance  trade  tests  are  used  in  voca- 
tional selection,  in  evaluating  progress  in 
learning  an  occupation  and  in  appraising 
proficiency  for  granting  permits  or  licenses. 

Occupational  proficiency  can  also  be 
evaluated  indirectly  by  appraising  a  per- 
son's experience  or  training  in  a  personal 
interview  or  by  a  study  of  his  work  history 
and  school  record.  Applicants  for  posi- 
tions are  more  frequently  examined  by 
these  less  formal  methods.  In  many  in- 
stances, however,  such  records  are  not  ac- 
curate or  comparable,  and  it  is  difficult  ac- 
curately to  appraise  job  proficiency  from 
them. 

Actual  tryout  in  the  job  itself  is  the  best 
measure  of  proficiency.  It  is,  however,  usu- 
ally an  expensive  procedure.  Many  em- 
ployers have  the  practice,  however,  of  hir- 


ing all  new  employees  on  a  provisional 
basis.  During  this  trial  period  the  em- 
ployee may  be  dismissed  at  once  if  he  does 
not  show  the  re(|uired  profuiency. 

VOCATIONAL    POTENTIALITY 

Everyone  who  works  has  at  some  tiine 
learned  how  lo  jjerlonn  the  tasks  in  a  job. 
The  preparation  for  prolessional  occupa- 
tions involves  several  years.  In  the  simpk-r 
occupations  where  academic  backgiound  is 
unimportant,  often  a  worker  would  like  to 
know  how  he  would  'make  out'  if  he  en- 
tered a  given  job.  Employers  are  reluctant 
to  hire  inexperienced  workers  unless  there 
is  evidence  that  the  worker  is  capable  of 
learning  the  job  satisfactorily. 

How  well  a  vocationally  untrained  indi- 
^'idual  can  learn  and  succeed  in  an  occu- 
pation depends  upon  a  number  of  factors 
and  conditions.  Psychologists  have  devel- 
oped measures  of  potentiality  that  are  use- 
ful as  aids  in  attempting  to  estimate  prob- 
able achievement. 

Aptitude  tests,  for  example,  have  been 
constructed  to  measure  specific  reactions 
which  are  analogous  to  those  which  occur 
in  occupations.  In  the  selection  of  street- 
car motormen,  applicants  may  be  required 
to  respond  rapidly  to  signals  \vith  hand  and 
foot  levers  in  a  laboratory.  Such  a  test  is 
not  a  measure  of  skill  in  street-car  opera- 
tion, but  it  does  show  in  some  degiee  how 
quickly  and  how  well  applicants  could  learn 
the  job  once  they  -tvere  employed. 

Intelligence  tests,  interest  tests,  personal- 
ity tests  and  personal  inten'iew  data  are 
also  used  as  indicators  of  occupational  po- 
tentiality to  aid  an  indi^idual  in  making 
vocational  plans  and  to  aid  professional 
schools  and  employers  in  selecting  indivitl- 
uals  who  will  most  likely  succeed  in  train- 
ing and  in  subsequent  perfonnance  on  the 


556 


Vocafional  Selection 


jolj.  Measures  of  potentiality  are  not  al- 
Avays  sharply  defined  from  tests  of  voca- 
tional  knowledge  and  proficiency.  For  ex- 
ample, in  one  study  a  \ocabulary  test  was 
found  useftd  as  an  aid  in  predicting  success 
in  an  engineering  occupation.  The  test 
contained  engineering  and  related  terms. 
Although  the  test  was  used  as  one  of  po- 
tentiality, it  contained  some  items  of  knowl- 
edge required  directly  in  the  occupation. 


Best  operators 


Average  operators 


Least  proficient  operators 


20        40        60 
Per  cent 

FIGURE      240.        PERCENTAGE     OF     POWER     SEWING- 
MACHINE   OPERATORS   WITH    LOW   TEST  SCORES   FOR 
EACH    OF    THREE    GROUPS    RATED    DIFFERENTLY    IN 
PROFICIENCY 

Based  on  seventy-seven  ojaeialors  in  two  different 
])lants. 

Measures  of  potentiality  must  be  stand- 
ardized for  any  particular  occupation. 
The  usual  method  is  to  try  out  the  meas- 
ures on  workers  already  in  the  occupation 
to  discover  the  potentialities  and  what 
measures  are  related  to  them. 

Figure  240  shows  the  results  of  adminis- 
tering a  battery  of  aptitude  tests  to  two 
groups  of  sewing-machine  operators.  It  is 
noted  that  only  14  per  cent  of  the  best  op- 
erators had  low  aptitude  test  scores,  whereas 
62  per  cent  of  the  least  proficient  023er- 
ators  had  low  scores.  The  supervisor  of 
the  workers  in  each  sample  compared  eacli 
worker  with  ^eiy  other  worker,  indicating 
which  worker  in  each  successive  pair  was 


the  more  proficient.  The  worker  with  the 
greatest  number  of  'firsts'  received  the  high- 
est rating. 

The  names  given  to  tests  do  not  always 
indicate  what  it  is  that  the  tests  test.  The 
tests  given  the  sewing-machine  operators  in- 
cluded two  subtests  that  are  supposed  to 
measure  clerical  aptitude  and  others  that 
are  meant  for  mechanical  aptitude.  A 
tester  never  knows  what  a  test  will  do  until 
after  he  has  tried  it  out  and  determined  its 
\alidity. 

Intelligence 

Intelligence  tests  have  been  related  to  oc- 
cupational status  more  frequently  by  show- 
ing the  differences  in  average  test  scores  be- 
tween occtipational  groups  than  by  finding 
that  they  will  differentiate  the  better  from 
the  poorer  workers. 

In  both  World  Wars  millions  of  men  in 
uniform  were  given  'intelligence'  tests.  The 
scores  made  by  soldiers  who  came  from 
specific  occupations  were  compared. 

Table  XXXV  shows  by  civilian  occupa- 
tions the  mean,  standard  deviation  and 
range  of  Army  General  Classification  Test 
scores  for  a  sample  of  white  enlisted  men 
in  the  Army  Air  Forces.  The  differences 
between  the  mean  scores  of  accountant 
and  lawyer  are  not  significant,  but  the 
means  for  these  two  occupations  are  sig- 
nificantly higher  than  those  of  any  of  the 
other  occupations  listed.  In  general,  dif- 
ferences of  five  points  or  more  between 
mean  scores  are  significant  in  this  sample. 
As  in  other  such  studies  the  overlapping  of 
scores  is  considerable,  but  the  overlapping 
up  from  the  lower  occupations  is  greater 
than  down  from  the  higher  occupations. 
The  upward  overlapping  inay  be  due  in 
part  to  the  youth  of  so  many  of  the  sub- 
jects.   Youth,  lacking  experience,  seldom  ii 


Intelligence  and  Interesis 


557 


TABLE  XXXV 

Mi-;AN    GkNKRAI,    Cj.ASSIFICATION  TkST    StANIMRIJ    ScOKKS,    SiANIJAKIJ    Di.VIAIIONS    ANIJ    RaNOK    or    .SCORKS    FOR 

Akmy  Ajr  Forck  Whiik  Enlistko  Mkn  bv  Civilian  Occupation 
[Dat;i  from  T.  W.  Harrell  and  M.  S.  Harrell,  Educ.  and psychol.  Meas.,  1945,  6,  231-232.J 


Number 

Mean 

Standard 

Range 

Civilian  Occupation 

of  Cases 

Score 

Deviation 

of  Scores 

Accountant 

172 

128.1 

11.7 

94-157 

Lawyer 

94 

127.6 

10.9 

96-157 

Teacher 

256 

122.8 

12.8 

76-155 

Draftsman 

153 

122.0 

12.8 

74-155 

Stenographer 

147 

121.0 

12.5 

66-151 

Tabulating  machine  operator 

140 

120.1 

13.3 

80-151 

Bookkeeper 

272 

120.0 

13.1 

70-157 

Clerk,  general 

496 

117.5 

13.0 

68-155 

Clerk-typist 

468 

116.8 

12.0 

80-147 

Radio  repairman 

267 

115.3 

14.5 

56-151 

Salesman 

494 

115.1 

15.7 

60-153 

Manager,  retail  store 

420 

114.0 

15.7 

52-151 

Machinist 

456 

110.1 

16.1 

38-153 

Airplane  mechanic 

235 

109.3 

14.9 

66-147 

Receiving  and  shipping  checker 

281 

107.6 

15.8 

52-151 

Sheet  metal  worker 

498 

107.5 

15.3 

62-153 

Auto  serviceman 

539 

104.2 

16.7 

30-141 

Butcher 

259 

102.9 

17.1 

42-147 

Carpenter,  construction 

451 

102.1 

19.5 

42-147 

Auto  mechanic 

466 

101.3 

17.0 

48-151 

Truck  driver 

817 

96.2 

19.7 

16-149 

Laborer 

856 

95.8 

20.1 

26-145 

Farmer 

700 

92.7 

21.8 

24-147 

Farmhand 

817 

91.4 

20.7 

24-141 

Miner 

156 

90.6 

20.1 

42-139 

placed  where  all  its  intelligence  can  be 
used.  Given  time  more  men  would  rise  in 
the  occupational  levels  which  the  table 
shows  than  would  fall,  and  eventually  the 
spread  about  the  average  for  each  occupa- 
tion would  be  just  as  much  down  as  up. 

In  industry,  intelligence  tests  are  often 
administered  to  workers  in  order  to  deter- 
mine hiring  standards.  Then  lower  limits 
and  sometimes  higher  limits  are  set  for  em- 
ployment. Sometimes  a  relationship  has 
been  found  between  intelligence  test  scores 
and  job  proficiency,  but  usually  there  are 
other  better  indicators  of  potentiality.  (For 
a  description  of  the  Army  General  Classifi- 
cation Tests,  see  p.  405.) 


Interests 

Tests  of  vocational  interest  have  been  ob- 
tained by  administering  questionnaires  to 
persons  employed  in  various  occupations. 
Items  in  the  scales  are  then  weighted  so 
that  in  the  scored  test  the  client  can  see 
how  his  pattern  of  interests  compares  with 
the  patterns  for  various  occupations  and 
fields  of  work. 

In  one  interest  test  (Kuder  Preference- 
Record)  scores  are  obtained  for  nine  gen- 
eral areas:  (1)  mechanical,  (2)  computa- 
tional, (3)  scientific,  (4)  persuasive.  (5)  artis- 
tic, (6)  literary,  (7)  musical,  (8)  social  ser\-- 
ice,  (9)  clerical.  Chemists  have  been  found 
to  be  high  in  the  scientific  area.  clerg)Tnen 


558 


Vocational  Selecfion 


in  the  literary  and  social  service  areas  and 
insurance  agents  in  the  persuasive  area. 

Occasionally  items  from  interest  ques- 
tionnaires are  used  to  differentiate  poorer 
from  better  workers.  For  instance,  in  de- 
veloping tests  for  the  selection  of  salesmen, 
such  items  have  been  found  useful.  Each 
item  is  weighted  by  comparing  the  re- 
sponses of  the  less  proficient  with  the  more 
proficient  salesmen.  In  one  study  interest 
in  music  was  found— surprisingly  enough!— 
to  differentiate  salesmen  significantly  with 
respect  to  their  proficiency. 

Other  Measures 

Personality  tests  and  personal  data  items 
(pp.  491-497)  have  been  utilized  as  meas- 
ures of  occupational  potentiality.  Such 
items  have  been  found  useful,  for  ex- 
ample, in  differentiating  better  from  poorer 
salesmen.  In  one  study  of  department 
store  salespersons,  the  more  proficient  work- 
ers showed  responses  on  personality  test 
items  which  suggested  that  they  were  more 
'extraverted'  than  the  poorer  salespersons. 

In  another  study,  place  of  birth,  age  at 
time  of  hiring,  previous  occupation,  grade 
completed  in  school  and  other  personal 
data  were  found,  when  weighted  by  statis- 
tical procedures,  to  differentiate  better 
from  poorer  wholesale  salesmen.  That  is 
a  good  example  of  how  necessary  it  is  to 
find  out  what  the  tests  actually  do.  It  is 
evident  that  you  could  not  know  which  of 
these  items  would  make  up  a  suitable  test 
until  you  had  tested  tlie  test. 

BASIC    FACTORS    I  N 
OCCUPATIONAL    SKILLS 

When  the  scores  on  various  measures  of 
occupational  potentiality  are  correlated 
with  one  another  and  given  further  statis- 


tical treatment,  it  is  found  that  a  relatively 
few  factors  seem  to  account  for  the  ntnuer- 
ous  characeristics  measured  in  the  tests. 
Some  of  the  factors  foimd  thus  far  in  stud- 
ies of  aptitudes  are  indicated  by  the  terms 
dexterity,  spatial^  numerical,  verbal,  aim- 
ing, mechanical  and  speed.  Further  re- 
search may  result  in  the  development  some 
day  of  a  basic  test  battery  for  occupational 
potentiality  which  will  cover  the  essential 
factors  now  found  in  the  various  aptitude, 
intelligence,  interest  and  personality  tests. 
The  amounts  of  these  basic  factors  required 
for  success  in  families  of  occupations  can 
then  be  determined.  It  would  become  pos- 
sible for  a  person,  after  taking  the  basic 
battery,  to  know  how  his  potentialities 
measure  up  to  the  recpiirements  in  occu- 
pational families  which  cover  thousands  of 
separate  occupations.  And  it  woidd  be 
just  as  possible  for  the  employer,  knowing 
the  requirements  of  the  job  from  his  job 
analysis,  to  select  the  proper  men  for  the 
job.  The  job  and  the  worker  can  be 
brought  together  with  the  greatest  efficiency 
and  the  greatest  satisfaction  to  all  con- 
cerned, when  worker  analysis  and  job  anal- 
ysis have  shown  clearly  which  belongs  to 
which. 

REFERENCES 

1.  Bingham,    W.   V.    D.      Aptitudes   and   aptitude 
testing.     New  York:   Harper,   1937. 

An  authoritative. description  of  aptitudes  and 
their  measurement.  A  book  widely  used  by  vo- 
cational counselors. 

2.  Bunt,   H.    E.     Principles   of   employment    psy- 
chology.    New  York:   Harper,  1942. 

Devoted  to  the  descriptions  of  psychological 
techniques  as  applied  to  the  selection  of  per- 
sons for  jobs. 

3.  Shartle,  C.  L.     Occupational  information.     New 
York:   Prentice-Hall,  1946. 


References 


559 


Describes  liovv   inroniKition   ;i1khiI    jobs  is  <ie- 
vcioiied  and   apjjhcd,  niviiif;  many  cxainjjles. 

'I.  .Slead,  W.  H.,  .Sharlie,  C.  I,.,  and  Associates. 
Occupational  counseling  lerhniqucs.  New 
York:   American   Book.   1910. 

l)e.scril)es  Ihe  developineni   ol   irade  and  apli- 
Uidc  lesls  for  use  in  vocational   toiniscling. 


.5.  Tidm,    J.      Industrial    psycholot^y.      (2nd    cd.) 
New  York:    Prenlicc-Hali,    1947. 

Covers   the   use  of  tests  in    their  a|>pliuition 
to  industry,  giving  many  examples. 

(j.  Viteles,    M.    .S.      Industrial    psychology.      New 
York:   Norton,  19.82. 

An  older  bool;.  ubid]   ne^crllle^■ss  toveis  ihe 

held   ucll. 


CHAPTER 


24 


Attitudes  and  Opinions 


EACH  individual  starts  life  in  a  particu- 
lar culture  composed  of  institutions, 
laws,  fashions,  language  and  objects  of  all 
kinds  that  are  characteristic  of  it.  To  keep 
this  seemingly  obvious  fact  ever  in  mind  is 
essential  from  the  outset.  If  we  propose 
to  study  our  own  culture,  we  must  under- 
stand with  as  much  objectivity  and  per- 
spective as  possible  the  basic  assumptions 
and  the  predominant  modes  of  thought  and 
behavior  that  pro\ide  the  framework  for 
our  observation.  We  must,  somehow,  jump 
out  of  our  own  skins  in  order  to  look  at 
ourselves  and  our  own  kind  as  we  would 
at  laboratory  subjects. 

For  example,  suppose  an  American,  in- 
terested in  determining  the  attitudes  of 
adolescents  toward  different  occupations, 
finds  that  the  banker  and  the  business 
executive  are  most  highly  esteem_ed,  the 
lawyer  and  the  doctor  next,  the  engineer 
and  the  carpenter  and  the  mason  last.  Can 
he  conclude  that  there  is  something  about 
banking  or  the  practice  of  law  that  makes 
its  devotees  more  respectable  than  would 
carpentry  or  brick  laying?  He  should  not 
come  to  such  a  conclusion,  although  he 
often  does.  There  is  a  fallacy  here.  The 
American  is  observing  within  a  particular 
social  framework— the  United  States— and  it 
is  only  within  this  framework  that  his  con- 
clusions are  valid.    Were  he  to  go  to  Soviet 


Russia,  he  might  find  his  conclusions  com- 
pletely reversed.  Or  even  were  he  to  carry 
on  his  study  in  a  small  rural  community 
where  the  local  doctor  was  the  outstanding 
citizen,  his  findings  might  likewise  be  tip- 
set. 

If  he  decides  to  compare  the  vocational 
ambitions  of  children  in  different  cultures, 
instead  of  inquiring  what  the  attitudes  of 
children  are  toward  different  occupations, 
the  question  which  he  must  really  ask 
turns  out  to  be:  How  does  the  social  frame- 
work within  which  an  individual  is  born 
determine  his  attitude  toward  different  vo- 
cations? In  other  words,  unless  an  Ameri- 
can has  this  perspective,  he  will  fail  to 
recognize  some  of  the  major  problems  in 
his  field.  ' 

SOCIAL    NORMS 

Every  culture  surrounding  every  indi- 
vidual is,  then,  more  or  less  specific.  In 
s(jme  cases  its  limits  are  natural  bounda- 
ries, such  as  mountains  or  oceans.  In  other 
cases  it  is  limited  by  the  imaginary  lines 
separating  one  'nation'  from  another.  In 
still  other  situations,  the  boundaries  are 
merely  class,  custom,  language,  income,  edu- 
cation, sex  or  age.  Two  j^eople  living  in 
the  same  city  may,  from  the  point  of  view 
of  psychology,  be  living  in  quite  different 


This  chapter  whs  prepared  by  Hadley  Oantril  of  Princeton  University. 


560 


Socio/  Norms 


561 


cultures,  siibjcctcci  lo  (|uitc  (lillcrcnt  social 
stimulus  situations.  To  one  man  may 
come  wcaltli,  prestige,  security,  while  no 
more  than  a  block  away  there  may  live  an 
unskilled  laborer,  poor,  unknown  and  un- 
sure of  his  job.  The  social  Irames  of  refer- 
ence within  which  these  two  men  think, 
feel  and  act  will  turn  out  to  be  almost 
as  different  as  those  of  an  Eskimo  and  an 
Australian  Bushman— possibly,  indeed,  even 
more  different.  If  both  the  Eskimo  and 
the  Bushman  happen  to  be  leaders  or  slaves, 
their  social  frames  of  reference  may  have 
a  good  deal  more  in  common  than  those 
oi  the  two  neighbors  in  the  city. 

There  are  many  assumptions,  habits  and 
customs  that  most  people  living  in  the 
United  States  at  the  present  time  take  for 
granted  but  that  would  seem  queer  enough 
to  many  an  outside  observer  unacquainted 
with  our  culture.  A  few  examples  are  the 
following:  that  a  man  should  have  only 
one  wife,  a  woman  only  one  husband;  that 
we  should  eat  three  times  a  day,  using 
knives  and  forks;  that  we  should  regard 
roast  beef  and  roast  pork  as  delicacies  but 
eschew  whales'  fins  or  dried  mice;  that  most 
business  and  professional  work  should  be 
done  by  men,  and  most  housework  by 
women;  that  we  should  elect  people  to 
govern  us;  that  we  should  have  a  stock 
exchange. 

Such  basic  assumptions,  customs,  insti- 
tutional patterns  of  behavior— as  well  as 
forms  of  art,  of  buildings,  and  the  charac- 
teristic shapes,  sizes  and  uses  of  the  prod- 
ucts of  our  particular  technological  society 
in  which  we  happen  to  live— may  all  be 
described  by  the  term  social  norms.  In 
our  own  culture  these  norms  may  be  repre- 
sented by  such  widely  different  examples 
as  a  football  game,  a  skyscraper,  democracy, 
a  diatonic  musical  scale  or  an  automobile, 
all    of   whicli    mav    be    regarded    as    social 


norms,  siiue  each  has  been  created  and 
accepted  and  passed  on  to  the  next  genera 
tion  by  groups  of  individuals.  Other  cul- 
tures, however,  have  other  norms:  cricket, 
igloos,  dictatorship,  the  five-interval  musi- 
cal .scale  or  jinrikishas. 

Particularly  important  for  those  who 
would  study  people's  attitudes  and  opin- 
ions is  the  fact  that,  among  these  norms, 
there  are  standardized  and  accepted  value 
judgments  which  are  transmitted  to  the 
newborn  individual.  When,  for  example, 
we  learn  about  democracy,  we  also  learn 
that  democracy  is  a  'good'  thing;  when  we 
hear  about  football  games,  we  infer  that 
people  'approve'  of  them;  when  we  learn 
about  thieves,  we  are  warned  that  they 
are  'bad'  men.  As  we  shall  see,  the  fact 
that  we  learn  how  we  should  judge  or 
evaluate  a  custom,  an  institution,  a  shape 
or  a  symbol  at  the  same  time  that  we  learn 
about  that  custom,  institution  or  shape  is 
of  the  utmost  importance  if  we  are  to  un- 
derstand social  behavior. 

It  is  these  social  norms  that  form  a  large 
share  of  the  social  stimulus  situation  to 
which  a  person  resj^onds.  The  person  does 
not,  to  be  sure,  react  to  the  abstract  value 
or  norm  itself;  he  reacts  to  its  concrete 
representation.  We  do  not  stop  at  a  cor- 
ner because  of  a  vague  norm  called  'the 
law,'  but  because  the  policeman  bars  the 
way,  because  there  is  a  traffic  signal  and 
because  ^ve  ourselves  fear  ^\hat  might  hap- 
pen to  us  if  we  did  not  stop.  We  are  taught 
to  salute  the  flag,  to  sing  The  Stai-Spangled 
Banner,  to  buy  Liberty  Bonds,  and  in  all 
these  ^vays  we  learn  the  abstract  Aalue  of 
patriotism.  Yet  each  of  these  specific  ob- 
jects or  modes  of  behavior  must  in  the  end 
be  regarded  merely  as  sociallv  accepted 
representations  of  those  more  generalized 
ways  of  thinking  or  acting  approved  by  oiu^ 
particular  society. 


562 


Attitudes  and  Opinions 


These  norms  have  emerged  in  the  long 
process  of  human  interaction.  In  spite 
of  the  fact  that  norms  generally  tend  slowly 
to  change,  it  is  not  true  that  there  is  any- 
thing absolute  or  fixed  about  them.  If 
this  Avere  true,  ob\iously,  we  should  not 
experience  the  social  change  which  is  so 
characteristic  of  man's  society. 

'  We  have  seen  that  these  norms  make  up 
the  social  stimulus  situation  for  an  indi- 
vidual. The  importance  of  this  fact  must 
be  underlined  if  we  are  to  avoid  the  pit- 
falls of  those  writers  who  have  tried  to 
explain  the  behavior  of  different  peoples  by 
mystical  racial  theories  or  by  typologies  of 
one  sort  or  another  (pp.  43 1-433).  For  since 
norms  are  first  external  to  the  individual, 
the  conclusion  is  inevitable  that  no  person 
—and  that  means  the  members  of  no  group 
nor  of  any  particular  nation  or  culture- 
is  endowed  at  birth  with  any  particular  set 
of  attitudes  or  opinions.  They  are  all 
acquired  (learned)  in  the  process  of  sociali- 
zation. Therefore,  if  we  really  want  to 
understand  what  is  meant  by  the  phrase 
liumnn  nature,  about  which  many  laymen 
and  political  leaders  make  hasty  generaliza- 
tions, we  must  understand  what  this  proc- 
ess of  socialization  involves.  We  shall 
trace  this  process  briefly  in  the  present 
rha]3ter  and  leave  for  the  next  a  more  de- 
tailed account  of  some  of  the  mechanisms 
involved  and  some  of  the  consequences  in 
lerms  of  individual  group  relations  and 
social  adjustment. 

THE    PROCESS    OF 
SOCIALIZATION 

Social  norms  may  be  regarded  as  form- 
ing the  superstructure  of  the  society  into 
which  the  individual  is  born.  If  he  is  to 
live  satisfactorily  in  his  society,  avoiding 
jails  and  mental  hospitals  where  the  per- 


sons who  deviate  from  the  norms  are  iso- 
lated, he  must  as  he  grows  up  somehow 
make  these  values  or  norms  a  part  of  him- 
self. Most  of  us  have  unwittingly  incor- 
porated in  our  conduct  the  behavior  and 
thought  patterns  of  our  particular  culture. 
AVhat  this  means,  essentially,  is  that  some- 
how the  norms  of  the  culture,  which,  to 
repeat,  are  first  external  to  us,  have  become 
an  intimate  part  of  us,  have  become  our 
attitudes,  attitudes  that  direct  or  determine 
oin-  behavior  and  thoughts.  We  may  de- 
fine an  attitude  as  a  mental  set  lohich  di- 
rects an  individual's  response.  (On  the  re- 
lation of  attitude  to  need  and  set,  see  p. 
126.) 

There  are,  of  course,  many  ways  in  which 
we  derive  or  learn  our  attitudes.  If  wc 
really  want  to  know  how  a  particular  per- 
son has  acquired  a  particular  attitude,  wc 
must  probe  deeply  into  his  life  history  and 
personality  make-up.  The  chances  are  that 
we  woidd  find  his  attitude  was  determined 
in  one  of  the  following  three  ways:  (1)  by 
the  uncritical  acceptance  of  social  norms, 
usually  through  suggestion,  (2)  by  the  gen- 
eralization of  personal  experience  or  (3)  by 
some  strong  emotional  experience. 

Acceptance  of  Social  Norms 

The  first  and  by  far  the  most  important 
and  most  common  method  is  for  the  indi- 
Aidual  to  accept  an  attitude  whole  from  a 
culture  before  he  has  necessarily  had  any 
contact  with  the  specific  objects  toward 
which  the  attitude  is  later  directed.  We 
learn,  that  is,  how  we  should  regard  things 
before  we  see  the  things  themselves.  A 
demonstration  of  this  fact  is  found  in  a 
study  of  the  development  of  attitudes  to- 
ward the  Negro.  An  investigator  was  in- 
terested in  determining  the  differences  be- 
tween the  attitudes  of  northern  and  south- 
em   children   toward   the   Negro.      He   ob- 


The  Process  of  Socialization 


563 


tained  for  his  study  different  groups  ol 
children:  groups  in  rural  and  in  urban 
Georgia  and  Tennessee,  children  in  an  all- 
white  school  in  New  York  City,  children 
in  a  mixed  school  in  New  York  City  and 
children  of  Communist  parents.  His  re- 
sults indicated  that  there  are  no  great  dif- 
ferences in  the  attitudes  of  rural  and  urban 
children  in  the  south,  that  children  in  both 
the  north  and  the  south  have  about  the 
same  prejudices  at  about  the  same  age,  that 
(hildren  in  an  all-white  school  develop  the 
same  prejudice  as  children  in  a  mixed 
school,  but  that  children  of  Communist 
parents  do  not  develop  an  unfavorable  atti- 
tude toward  the  Negro.  On  the  basis  of 
these  results  it  was  concluded  that  "atti- 
tudes toward  Negroes  are  chiefly  deter- 
mined not  by  contact  with  Negroes,  but  by 
contact  with  the  prevalent  attitude  toward 
Negroes."  In  other  words,  children  accept 
in  toto  and  uncritically  the  frame  of  refer- 
ence provided  in  their  immediate  culture, 
and  that  without  necessarily  having  had 
any  experience  whatsoever  upon  which  to 
base  the  standards  they  accept.  (See  also 
p.  604.) 

Another  study  illustrating  the  same  point 
was  made  by  investigators  who  had  students 
place  in  rank  order  their  preferences  for 
various  national  and  racial  groups.  A 
comparable  set  of  students  was  asked  to 
pick  out  from  a  long  list  of  adjectives 
those  terms  they  thought  most  character- 
istic of  the  same  national  and  racial  gioups. 
Those  groups  that  had  been  rated  high  by 
the  first  set  of  students  were  assigned  the 
most  favorable  adjectives  by  the  second 
set.  Similarly  the  racial  groups  at  the  bot- 
tom of  the  list  were  characterized  unfavor- 
ably. The  important  point  of  the  experi- 
ment is  that  all  the  students  who  partici- 
pated in  this  experiment  made  their  judg- 
ments glibly  and  easily  or  selected   their 


adjectives  without  any  real  knowledge  ol 
the  racial  or  national  groups  or  any  pre- 
vious experience  with  them.  In  othtT 
words,  they  blindly  applied  the  traditional 
stereotypes  of  their  culture  to  these  groups. 
A  stereotype  is  a  conventional  concept  of 
the  appearance,  character  or  habitual  be- 
havior of  a  person  or  thing.  It  is  derived 
—usually  unwittingly— from  the  culture 
more  than  from  experience  and  it  is  changed 
only  with  difficulty.     (See  p.  599.) 

Suggestion 

One  of  the  most  important  basic  con- 
cepts in  the  field  of  social  relations  is  sug- 
gestion, for  it  is  largely  by  its  means  that 
a  person  acquires  the  stereotyped  norms  of 
his  community,  his  religion,  his  politics,  his 
racial  prejudices,  his  ethical  and  esthetic 
standards.  If  the  majority  of  people  in  this 
country  are  Democrats  or  Republicans,  it  is 
not  because  they  have  made  careful  anal- 
yses of  Anarchism,  Socialism,  Fascism  or  tlie 
other  political  points  of  view  found  in  our 
modern  world,  not  because  they  ha\e  de- 
cided on  the  facts  of  their  study  that  the 
particular  principles  for  which  the  Demo- 
crats or  Republicans  may  stand  are  superior 
to  those  of  other  doctrines.  On  the  con- 
trary, they  are  Democrats  or  Republicans 
because  they  have  acquired  the  particular 
norms  of  their  culture. 

The  norms  have  the  advantage  of  pro- 
viding US  with  relatively  fixed  and  limited 
standards  of  jiidgment  by  means  of  which 
we  interpret  or  give  meaning  to  specific 
events.  Without  such  standards  of  judg- 
ment, which  we  may  call  frames  of  refer- 
ence, we  should  be  at  a  loss  how  to  con- 
duct ourselves  in  a  complex  Avorld.  Since 
the  limits  of  time  and  energy  forbid  our 
reasoning  out  an  opinion  on  every  issue 
where  Ave  need  to  ha\e  some  such  opinion, 
we  uncritically  accept,  instead,  die  pre\ail- 


564 


Attitudes  and  Opinions 


ing  norms  and  then  try  to  rationalize  them 
to  ourselves. 

We  may  define  suggestion  as  the  accep- 
tance by  an  individual  of  a  frame  of  refer- 
ence without  the  iiitewention  of  critical 
thought  processes.  When  a  person  has  no 
standard  of  judgment  but  has  a  desire  for 
some  standard,  he  may  accept  a  judgment 
uncritically.  For  example,  a  person,  who, 
knowing  nothing  about  music,  nevertheless 
feels  that  he  should  know  something  about 
it,  will  accept  the  critic's  judgment  of  an 
artist's  performance  or  of  a  new  symphony. 
Or  an  individual  may  accept  a  suggestion 
because  it  is  consistent  with  some  frame 
of  reference  (attitude,  opinion,  belief) 
which  he  already  possesses.  In  this  latter 
case,  the  suggestion  merely  reinforces  his 
established  opinion. 

It  is  largely  because  of  suggestion  that 
advertising  is  so  successful.  Generally  the 
advertiser  tries  to  show  how  his  product 
will  help  us  attain  some  desired  goal,  how 
vital  it  is  in  achieving  that  end.  If  we 
use  his  soap,  we  shall  all,  he  tells  us,  be 
social  successes;  if  we  smoke  his  cigarette, 
we  shall  be  athletic;  if  we  serve  his  whis- 
key, we  shall  impress  business  associates. 

Frequently  the  advertiser  makes  use  of 
what  we  know  as  prestige  suggestion  by  tell- 
ing us  of  the  famous  people  who  vise  his 
product.  A  recent  automobile  advertise- 
ment informs  us,  "During  the  past  year,  for 

instance,  was  chosen  by  2  members  of 

the  English  Royal  Family,  33  diplomatic 
representatives  of  21  countries,  8  govern- 
ment officials  of  Ecuador,  a  judge  of  the 
Supreme  Court  of  China,  etc."  Such  an 
advertisement  not  only  calls  attention  to 
the  product,  it  also  provides  a  highly  valued 
frame  of  reference  (the  prestige  of  the  diplo- 
mat) by  means  of  which  the  product  may 
be  judged. 

The  influence  of  prestige  in   the  accep- 


tance of  dogmatic  statements  has  frequently 
been  demonstrated.  In  one  study  the  ex- 
perimenter first  determined  from  his  sub- 
jects what  well-known  persons  they  liked 
best  and  what  ones  least.  Then  he  pre- 
sented the  subjects  with  a  questionnaire 
containing  thirty  statements,  such  as  the 
following,  with  instructions  to  mark  on  a 
five-point  scale  the  degree  to  which  they 
agreed  or  disagreed  with  the  statement: 
"There  is  nothing  sacred  about  the  Ameri- 
can Constitution.  If  it  doesn't  serve  its 
piupose,  it  should  be  changed  as  often  as 
necessary." 

A  third  of  the  subjects  were  given  the 
impression  that  the  statement  had  been 
made  by  one  of  their  best-liked  people  (like 
Mark  Twain  or  Woodrow  Wilson).  An- 
other third  were  given  to  imderstand  that 
it  had  been  made  by  one  of  their  most 
disliked  people  (like  Big  Bill  Thompson  or 
Aimee  Semple  McPherson).  For  the  third 
group  the  statement  was  attributed  to  no 
one.  In  this  manner  the  investigators 
found  that  statements  were  in  general  more 
likely  to  be  accepted  when  attributed  to 
well-liked  people  than  when  attributed  to 
disliked  persons. 

Suggestibility  to  majority  opinion  is  also 
common  in  everyday  life.  In  another  ex- 
periment a  test  of  attitudes  was  given  to 
nine  hundred  people,  who  were  subse- 
quently divided  into  three  groups,  A,  B 
and  C.  One  month  later  the  persons  in 
Group  A  were  told  that  the  majority  of 
people  had  answered  a  certain  way  in 
the  previous  test;  Group  B  was  told  that 
certain  experts  had  given  unanimous  opin- 
ions in  a  certain  direction;  and  Group  C, 
used  as  a  control  group,  was  told  nothing. 
When  the  three  groups  were  retested,  it 
was  fotind  that  those  in  Group  A  had 
changed  their  opinion  in  the  direction  of 
the  majority  about  four  times  as  much  as 


Suggestion  and  the  Formation  of  Attitudes 


565 


tlic  control  group,  whereas  tlic  people  in 
Group  B  had  changed  ahiiost  twice  as  nuuli 
as  those  in  Group  C. 

Studies  on  the  conditions  of  suggestibil- 
ity have  indicated  that  children  are  more 
suggestible  than  adults,  that  women  are 
more  suggestible  than  men,  that  certain 
primitive  peoples  are  more  suggestible 
than  more  civilized  groups.  It  would  be 
easy  to  draw  false  conclusions  from  these 
experiments.  There  is  almost  certainly 
nothing  inherent  in  the  child,  the  female 
or  the  primitive  to  make  them  more  sug- 
gestible. These  groups  have  merely  had 
comparatively  little  experience  in  certain 
fields  of  activity  and  consequently  possess 
less  knowledge  concerning  the  propositions 
on  which  tests  are  usually  made.  As  their 
training  and  experience  increase,  so  will 
their  dependence  and  suggestibility  dim- 
inish. Factors  such  as  fatigue,  depression, 
excitement  and  fear  also  increase  suggesti- 
bility, inhibiting  or  interfering  as  they  do 
with  maximum  critical  thought.  (For  more 
on  suggestion,  see  pp.  55  f.  and  593.) 

Formation  of  Attitudes 

A  second  way  in  which  we  get  our  atti- 
tudes is  the  reverse  of  the  uncritical  accept- 
ance of  social  norms.  We  generalize  on 
the  basis  of  our  own  present  or  past  experi- 
ence rather  than  accept  a  conventionality 
for  the  interpretation  of  later  experience. 

Experiments  indicate  that  the  pattern 
of  behavior  which  we  call  honesty  is,  in  our 
own  culture,  acquired  by  a  person  only 
after  he  has  learned  to  react  in  specific 
ways  in  specific  situations.  A  child  can 
learn  not  to  steal  apples,  not  to  copy  from 
his  neighbor's  arithmetic,  not  to  tell  lies. 
He  has,  at  first,  no  idea  that  these  specific 
behaviors  are  called  by  society  "dishonest." 
But,  as  he  matures,  he  gradually  learns 
the  meaning  of  the  concept  honesty  so  that. 


by  the  time  he  is  an  adult,  he  is  able  to 
interpret  a  new  possible  behavior  as  honest 
or  dishonest.  A  difficulty  which  an  indi- 
vidual encounters  in  forming  consistent  at- 
titudes derives  from  the  fact  that  the  norms 
of  different  reference  or  membership  groups 
—groups  with  which  the  individual  identi- 
fies himself— confiict  with  one  another,  so 
that  what  may  be  regarded  as  honest  be- 
havior by  a  child's  classmate  at  school  may 
be  something  quite  different  from  what  is 
regarded  as  honest  behavior  by  the  same 
child's  neighborhood  alley  gang.  An  adult 
also  may  be  subjected  to  a  confiict  of  the 
norms  of  different  membership  gioups  to 
which  he  feels  he  belongs.  A  businessman 
who,  as  a  church  member,  accepts  the 
golden  rule  may,  as  a  businessman  in  a 
sharply  competitive  system,  find  that  he 
cannot  survive  unless  he  outwits  his  com- 
petitors. 

Emotional  Origin  of  Attitudes 

A  third  way  in  which  the  indi%idual 
may  evolve  an  attitude  is  by  means  of  some 
intense,  traumatic  experience.  Though 
this  particular  method  is  comparati\ely 
rare,  it  may  be  of  the  utmost  importance 
in  determining  certain  attitudes  of  certain 
people.  For  example,  a  young  American 
soldier  who  had  believed  strongly  in  God 
and  had  in  civilian  life  attended  church 
regularly  was  severely  ■wounded  in  action 
during  the  Second  ^Vorld  AVar.  \Vhile  ly- 
ing on  the  battleground  he  prayed  that  the 
medics  would  reach  him  in  time  to  bind 
his  wounds  and  carry  him  to  safety;  but 
before  they  came  a  shell  exploded  near  bv. 
blinded  the  young  man  and  tore  off  one 
of  his  arms.  As  he  reports  tlie  case,  at  diat 
point  he  became  a  confirmed  atlieist.  Some 
persons  may  develop  an  attitude  toward  a 
certain  race  because  they  were  once  fright- 
ened  (or   imagined   diey  Avere  frightened) 


566 


Atfitudes  and  Opinions 


by  a  member  of  that  rate.  Others  may 
change  their  attitudes  toward  money  be- 
cause they  have  suddcnl)  lost  or  suddenly 
acquired  a  fortune. 

EFFECTS    OF    ATTITUDES 

Once  attitudes  have  been  learned  they 
determine  to  a  large  extent  what  an  indi- 
\idual  percei\es  and  how  he  behaves.  For 
example,  two  obser\ers  watching  the  same 
event  take  place  may,  if  they  differ  in  their 
attitudes  toward  the  stimulating  situation, 
perceive  quite  different  things.  An  ob- 
server's set  or  readiness  to  perceive  a  cer- 
tain thing,  usually  the  thing  he  wants  to 
perceive,  may  modify  greatly  his  interpre- 
tation of  the  situation. 

Two  college  students  from  two  different 
schools  watched  representatives  of  their 
respective  institutions  engage  in  a  boxing 
match  in  a  college  tournament.  The  fight 
was  the  last  and  deciding  bout  in  a  tourna- 
ment to  determine  the  Intercollegiate 
Championship.  Although,  as  a  matter  of 
fact,  the  two  boxers  were  very  closely 
matched,  they  did  not  seem  so  to  these  two 
observers.  Observer  A  thought  that  the 
boxer  from  his  school  gave  his  opponent 
a  sound  thrashing.  His  every  punch  landed 
with  a  thud,  whereas  the  blows  he  himself 
received  were  but  glancing  blows  that  did 
not  appear  to  bother  him.  Observer  B 
thought  that  his  school's  representative  was 
making  such  effective  use  of  his  right  hand 
that  the  other  fighter  was  groggy  during  the 
third  round.  ^Vhen  the  judges  decreed  that 
A's  boxer  had  won,  B  went  home  complain- 
ing about  the  poorly  qualified  judges.  The 
attitude  of  each  student  toward  anything 
identified  with  his  college  had  determined 
in  part  what  he  would  perceive. 

An  experimental  study  involving  sug- 
gestion by  prestige  was  made  of  the  effect 


of  attitude  on  perception  with  the  use  of 
the  autokinetic  phenomenon  (p.  239).  It 
will  be  recalled  that  this  is  the  phenome- 
non in  which  an  observer  in  a  strange  dark 
room  watches  a  tiny  stationary  point  of 
light,  which,  though  actually  immobile,  is 
perceived  to  move.  It  has  been  found 
that  induced  attitudes  will  affect  an  ob- 
server's illusory  perceptions  of  the  move- 
ments of  such  a  light.  When  a  naive  sub- 
ject is  asked  to  make  judgments  as  to  the 
amount  and  direction  of  the  movement 
after  hearing  like  judgments  made  by  an 
advanced  student  in  psychology,  he  tends 
to  follow  the  sophisticated  student  in  his 
judgment.  That  is  prestige  suggestion. 
An  attitude,  built  up  during  the  time  the 
observer  heard  judgments  being  made,  de- 
termines his  perception  of  the  ambiguous 
stimulus. 

The  literature  of  social  psychology 
abounds  in  studies  which  show  that  our 
everyday  behavior  is  directed  by  acquired 
attitudes  and  follows  the  same  psychologi- 
cal principles  that  can  be  studied  in  strict 
experimental  situations. 

Experiments  have  demonstrated  the  ef- 
fect of  the  attitudes  of  college  students 
toward  artists  on  their  judgments  of  the 
esthetic  value  of  pictures.  To  one  large 
group  of  college  students  an  experimenter 
showed  eight  pictures,  to  some  of  which 
were  attached  the  names  of  artists  known 
to  be  great  (Raphael,  Rubens,  Rembrandt, 
da  Vinci),  whereas  the  others  revealed 
names  of  little-known  artists.  The  students 
rated  each  picture  on  a  five-point  scale  (1  for 
'best,'  2  for  'next-best,'  etc.).  A  second 
comparable  group  of  students  rated  the 
same  pictures,  with  the  famous  names  sub- 
stituted for  the  unknown  names,  and  con- 
versely. The  students  tended  to  rate  the 
pictures  higher  when  the  name  of  a  person 
who  was  known  to  be  a  great  artist  was 


Effects  of  Attitudes 


567 


attached.  Here  the  attitude  ol  the  observer 
toward  certain  artists  consisted  in  part  of 
a  readiness  to  see  beauty  in  a  picture— a 
predisposition  which  resulted  in  his  seeing 
what  he  expected  to  see.  Suggestion  by 
prestige  depends  on  the  fact  that  individ- 
uals acquire  toward  well-known  people  at- 
titudes which  influence  favorably  the  inter- 
pretation of  their  statements. 

Studies  made  on  the  voting  Ijehavioi'  of 
American  citizens  show  that,  by  and  large, 
tile  overwhelming  majority  of  people  vote 
for  the  party  they  have  learned  to  identify 
tiiemselves  with,  the  one  for  which  they 
have  acquired  a  favorable  attitude.  Only 
a  very  small  percentage  of  American  voters 
seem  in  any  way  to  cast  their  ballots  ac- 
cording to  any  logical  analysis  they  make 
of  the  major  issues  of  the  day.  They 
tend,  on  the  other  hand,  to  rationalize 
the  particular  point  of  view  of  their  party 
or  the  particular  candidate  their  party  has 
proposed  for  a  given  office  as  the  'right' 
stand  to  take  on  the  issue  or  as  the  'best' 
candidate  available.  Over  two-thirds  of 
the  people  who  actually  vote  a  straight  party 
ticket  say,  at  the  same  time,  that  they  al- 
ways vote  for  the  'man'  rather  than  the 
'party.'  Yet  analysis  of  their  past  voting 
behavior  shows  that  the  'man'  they  have 
voted  for  has  always  been  a  member  of 
their  party. 

Other  studies  concerned  with  people's 
judgments  of  different  occupations  in  terms 
of  their  social  usefulness,  their  prestige  and 
the  liLe  clearly  indicate  that  these  judg- 
ments are  the  result  of  acquired  attitudes 
and  have  practically  no  relationship  what- 
ever to  any  experience  a  person  has  had 
with  that  occupation  or  any  real  knowl- 
edge of  its  requirements  or  social  useful- 
ness. Comparative  studies  of  the  values 
children  in  the  United  States  and  children 
in    the    Soviet    Union    place    on    different 


occupations  show  quite  clearly  how  ilicii 
preferences  derive  from  social  values  un- 
critically accepted.  American  children,  for 
example,  tend  to  rate  bankers  and  lawyers 
higher  than  skilled  workers,  whereas  the 
reverse  is  true  for  children  brought  up  un- 
der the  Soviet  system. 

Studies  of  Tumor  show  that  the  rumors 
we  tend  to  Inlieve  aie  those  that  fit  in 
with  our  preexisting  attitudes  and  thai  lu- 
mors  become  changed,  twisted  or  disiorteti 
as  they  are  passed  on  according  to  the  par- 
ticular cultural  traditions  or  groujj  inter- 
ests of  the  individuals  who  accept  liiem 
and  adjust  them  before  pjassing  them   on. 

DEVELOPMENT    OF    THE    EGO 

1  he  attitudes  a  person  acquires— whether 
they  are  widely  accepted  social  attitudes  or 
whether  they  are  attitudes  almost  unique 
to  a  single  individual  and  acquired  fiom 
his  own  experience— do  not  exist  in  a 
vacuum,  unrelated  to  one  another,  'i'ou 
can  see  from  your  own  introspection  that 
your  attitudes  have  a  peculiarly  personal 
quality,  that  they  are  your  attitudes,  that 
they  are  in  large  part  what  )ou  regard  as 
yourself.  If  someone  insults  the  parents 
whom  you  dearly  love,  you  are  insulted. 
If  someone  praises  your  college,  you  are 
pleased.  If  someone  you  regard  highly 
receives  a  great  public  honor,  \uu  are 
happy.  Most  of  our  atdtudes,  then,  can 
properly  be  described  as  ego  attitudes,  as 
attitudes  that  involve  us.  that  form  the 
constellation  of  our  egos. 

The  development  of  the  ego  from  the 
newborn  child  to  the  adult,  although  a 
long  and  complicated  storv.  is  nevertheless 
a  clear  storv  from  the  point  of  view  of  the 
psvcliological  principles  it  reveals,  for  it 
shoAvs  that  the  formation  of  the  ego  in  the 
individual  is  concomitant  Avith  the  devel- 


568 


Attitudes  and  Opinions 


opmem  of  the  perceptual  processes  and  the 
formation  of  attitudes.  The  infant,  for 
example,  has  to  learn  fairly  early  in  life 
to  differentiate  his  own  body  from  the 
objects  that  surround  him.  And  gradually 
he  does  learn  that  he  is  something  somehow 
different  from  the  tilings  around  him  and 
something  to  which  things  happen  and 
something  which  can  cause  things  to  hap- 
pen. The  child  learns  that  he  has  a  name; 
he  learns  that  certain  things  are  his;  he 
learns  that  there  is  such  a  thing  as  his 
family,  as  his  playmates,  and  his  home,  his 
school,  liis  country,  his  race,  his  religion, 
his  political  party  and  the  thousand  and 
one  other  identifications  which  go  to  form 
the  particular  pattern  of  attitudes  that  be- 
come his  ego— for  that  is  what  the  ego  is, 
a  pattern  of  attitudes.    (See  also  pp.  593  f.) 

The  ego  "vve  are  considering  here  is,  there- 
fore, nothing  innate  or  biologically  deter- 
mined as  a  person's  sex,  his  abilities  or  the 
color  of  his  hair  is  determined.  The  ego 
is  acquired,  and  the  particular  ego  an  indi- 
vidual forms,  the  attitudes  that  constitute 
a  large  and  important  part  of  his  n7e,  de- 
pend to  a  very  large  extent  on  the  particu- 
lar cultural  and  group  influences  to  which 
he  has  been  exposed.  And  since  the  social 
stimuli  that  surround  us  are  constantly 
changing,  constantly  varying  as  we  grow 
up  and  are  subjected  to  new  influences  or 
new  social  conditions,  our  egos  can  never 
be  regarded  as  static.  For  example,  in  the 
important  period  of  adolescence,  \vhen  the 
individual  is  developing  sexually  and  be- 
coming conscious  of  a  whole  host  of  social 
conditions  and  groupings  his  culture  has 
created  to  take  account  of  sex  distinctions, 
mating  and  the  care  of  children,  we  can 
very  properly  say  of  the  adolescent  at  this 
time  that  his  ego  is  being  re-formed. 

Just  as  the  ego  develops  in  the  child  and 
becomes    re-formed    in    the    adolescent,    so 


also  it  can  break  down,  disintegrate  or 
change  radically  under  catastrophic  or 
otherwise  exceptional  conditions.  For  ex- 
ample, there  is  ample  e\idcnce  that  the 
egos  of  many  people  who  had  been  put  in 
Nazi  concentration  camps  became  com- 
pletely altered  by  the  horrible  experiences 
to  which  they  were  subjected.  In  time  a 
number  of  people  in  these  camps  lost  many 
of  their  old  allegiances  and  identifications 
and,  in  order  to  survive  in  the  camp  at 
all,  came  gradually  to  accept  new  alle- 
giances and  identifications  more  in  con- 
formity to  Gestapo  standards  and  practices. 
In  critical  times— during  severe  depressions 
or  periods  when  old  social  standards  have 
so  broken  down  that  they  no  longer  pro- 
vide a  person  with  the  status  his  former 
ego  identifications  had  given  him— people 
are  likely  to  seek  new  allegiances,  identify 
themselves  with  new  leaders,  be  attracted 
by  new  slogans  or  in  other  ways  acquire 
new  ego  attitudes  which  give  new  direction 
to  their  behavior. 

It  is  impossible  to  understand  the  moti- 
vation of  a  person  in  his  social  life  unless 
we  take  into  account  these  ego  attitudes, 
these  identifications  which  provide  status 
and  the  goals  which  an  individual  thinks 
are  worth  striving  for. 

Effects  of  Ego  Involvement 

A  few  illustrations  taken  from  the  ex- 
perimental laboratory  and  from  everyday 
life  will  show  the  functional  role  played 
by  ego  involvement  in  determining  per- 
ception and  behavior. 

In  one  experiment  the  degiee  of  confi- 
dence which  subjects  felt  with  respect  to 
various  tasks  they  were  asked  to  perform 
was  clearly  shown  to  be  a  function  of  ego 
involvement.  The  subjects  in  this  experi- 
ment were  asked  in  their  first  experimental 
session   to   perform   various   operations   in 


Development  of  fhe  Ego 


569 


v(>lviiig  menial  acklilioti,  (Icfiiiitioii  and  i\u: 
like.  All  were  asked  to  inxlicate  on  a  seven- 
point  scale  how  murh  ronfidcncc  they  had 
in  their  answers.  In  lliis  first  session  the 
subjects  participated  in  a  Iree  and  easy 
manner  without  any  emotional  strain. 
Then  a  few  days  later  they  were  asked  to 
participate  in  a  second  session,  and  this 
time  they  were  told  that  the  tests  they 
were  about  to  take  were  part  of  a  general 
intelligence  test  and  that  the  results  of  it 
were  to  be  put  on  record  in  the  jDersonnel 
bureau  of  the  college.  All  the  subjects 
in  this  second  sesson  felt  under  strain  and 
all  exerted  themselves  considerably  more 
than  they  did  in  the  first  session.  The 
results  of  the  whole  experiment  showed 
that  in  the  first  or  'neutral'  session  there 
were  very  low  correlations  between  the 
scores  on  various  tests  and  the  confidence 
rating  on  those  tests;  whereas  in  the  sec- 
ond or  ego-involved  session,  althotigh  the 
correlations  between  the  scores  on  the  vari- 
ous tests  remained  low,  the  correlations  of 
the  subjects'  confidence  ratings  were  high. 
In  other  words,  the  introduction  of  ego 
involvement  aroused  a  general  level  of 
confidence  not  aroused  under  a  situation 
which  was  similar  in  all  respects  except 
the  important  one  of  motivation. 

The  effect  of  ego-involved  attitudes  on 
the  learning  and  forgetting  of  material  has 
been  demonstrated  in  a  number  of  dif- 
ferent studies.  We  have  already  seen  how, 
in  one  study,  investigators  measured  their 
subjects  with  an  attitude  scale  toward  Com- 
munism, and  then  later  asked  the  subjects 
to  learn  materials,  some  of  ^vhich  contained 
matter  favorable  to  the  Soviets  and  some 
matter  unfavorable  (p.  193).  The  subjects 
learned  more  and  remembered  more  of  the 
material  that  agreed  with  their  beliefs. 
Usually  it  is  harder  to  learn  and  harder  to 
remember  what  you  disbelieve. 


The  ego  involvcmcrii  in  everyday  life  is 
apparent  whenever  we  turn  to  look  for  it. 
P'or  example,  people  who  pay  some  auen- 
tion  lo  tlie  clothes  they  wear  (and  that  in- 
cludes most  of  us)  find  that  clothes  offer 
one  of  the  easiest  and  most  coiurete  ex- 
pressions of  their  status.  Frcfjuently  those 
who  are  members  of  the  'upper  class'  or 
who  are  eager  to  distinguish  themselves 
in  some  way  from  other  people  indulge  in 
some  kind  of  exclusive  attire.  Professors 
will  display  Phi  Beta  Kappa  keys  but  not 
wear  zoot  suits.  The  enormous  succe.ss  of 
advertising  in  the  United  States  cannot  be 
accounted  for  unless  we  have  regard  to  the 
ego  attitudes,  for  a  great  deal  of  advertising 
is  meant  to  show  how  your  status— by  your 
bodily  appearance,  your  lack  of  bodily  odor, 
the  kind  of  radio  you  have  or  the  kind  of 
car  you  drive— can  be  maintained  or  en- 
hanced if  you  will  but  buy  the  product  the 
advertiser  has  to  sell.  Studies  made  on  job 
satisfaction  repeatedly  show  that  a  worker's 
satisfaction  with  hours  and  usages  is  not 
enough  to  give  him  real  psychological  satis- 
faction in  his  job.  Although  fair  Avages 
and  hours  are,  of  course,  essential  to  job 
satisfaction,  a  major  component  of  such 
satisfaction  is  the  worker's  own  feeling  of 
his  importance,  his  role  or  his  status  and 
involvement  in  carrying  out  his  job.  He 
wants  to  feel  that  he  is  an  active  participant 
in  the  particular  process  of  production  or 
distribution  with  which  he  is  associated, 
and  he  does  not  get  complete  satisfaction 
until  he  is  able  to  identify  himself  A\ith 
this  process.     (See  pp.  482  f.) 

The  Ego  and  Group  Loyalty 

We  haA'e  already  noted  how  one  of  the 
important  sources  from  Avhich  an  individ- 
ual acquires  or  learns  his  attitudes  is  the 
nexus  of  group  relationships  in  which  he 
participates.      In    imderstanding   some    of 


570 


Attitudes  and  Opinions 


the  group  relationships  discussed  more  in 
detail  in  the  next  chapter,  it  may  be  help- 
ful here  to  make  a  distinction  between 
what  we  may  call  an  individual's  reference 
groups  and  his  ynembership  groups.  Refer- 
ence group  refers  to  a  broad  grouping,  like 
a  nation,  a  class,  an  occupation,  an  age 
group.  Membership  group  refers  to  a 
smaller,  more  specific  gi'oup,  like  the  fam- 
ily, the  school,  the  club,  the  union  or  the 
church.  We  all  develop  certain  loyalties 
and  allegiances  to  certain  reference  and 
membership  groups.  These  loyalties  and 
allegiances  are  ego-involved  attitudes  that, 
by  and  large,  determine  our  general  social 
status.  Generally  speaking,  we  achieve 
status  by  identifying  ourselves  with  refer- 
ence to  membership  groups  that  are  socially 
acceptable.  Some  people  at  some  times, 
however,  find  it  difficult  to  satisfy  their 
needs  or  achieve  certain  goals  by  accepting 
as  their  attitudes  the  norms  of  society  or 
the  norms  of  difFerent  groups  that  are  so- 
cially acceptable. 

Members  of  delinquent  gangs,  for  ex- 
ample, are  by  and  large  members  of  such 
gangs  not  because  of  inborn  personality 
traits  or  characteristics  but  because,  for 
some  reason  or  other,  the  socially  approved 
ways  of  achieving  status  have  been  denied 
them  or  are  inaccessible.  So  these  boys 
and  girls  drift  into  already  established 
groups  or  create  groups  of  their  own  which 
have  standards  or  norms  that  do  not  con- 
form to  those  of  the  larger  society  that  sur- 
rounds them.  Within  the  microcosm  of 
the  gang  they  find  they  are  able  to  achieve 
status  by  allowing  the  norms  of  the  gang 
to  determine  the  definition  of  what  is  right 
and  wrong,  what  is  honest  and  dishonest. 
They  accept  these  standards  as  their  own, 
identify  themselves  with  them  and  become 
delinquents. 


Many  of  the  conflicts  which  the  'normal' 
individual  experiences  in  our  society  are 
due  to  the  fact  that  individuals  identify 
themselves  with  membership  or  reference 
groups  that  have  themselves  contradictory 
or  conflicting  standards.  Identification 
with  a  group  in  conflict  means  assimilation 
of  the  conflict.  For  example,  one  of  the 
luiderlying  psychological  reasons  for  the 
difficulties  encountered  in  forming  an  in- 
ternational organization,  like  the  United 
Nations  or  some  other  form  of  world  gtn  - 
ernment,  is  that,  although  the  majority  of 
people  want  some  form  of  international 
regulation,  they  have  so  identified  them- 
selves with  their  own  countries  that  they 
are  unwilling  to  give  up  what  they  regard 
as  their  oxun  national  sovereignty  in  favor 
of  the  larger  grouping.  In  the  same  way. 
a  man  who  is  called  out  on  strike  often 
suffers  from  the  conflicting  allegiances  he 
has  to  his  union  and  to  his  family.  I'he 
union  uses  these  strikes  as  a  weapon  for 
eventual  higher  standards  of  living,  but  his 
family  will  suff^er  an  immediate  and  per- 
haps prolonged  lowered  standard  of  living 
if  the  breadwinner  goes  on  strike.  The 
American  college  student  may  experience 
conflicts  because  of  contending  standards 
of  different  membership  or  reference  groups 
with  which  he  has  identified  himself.  What 
is  expected  of  him  as  a  fraternity  man  may 
not  completely  conform  to  what  is  expected 
of  him  as  a  scholar.  His  desire  to  achieve 
a  prominent  place  on  an  athletic  team  may 
interfere  with  his  loyalty  to  his  parents 
who  expect  of  him  an  outstanding  academic 
record.  He  may  feel  that  some  of  the  sub- 
jects he  has  to  take  in  college  in  order  to 
achieve  the  status  of  a  college  graduate 
conflict  with  his  ideas  of  what  he  should 
be  learning  in  order  to  achieve  success  in 
his  chosen  vocation. 


Attitudes  and  Social  Change 


571 


ATTITUDES    AND    SOCIAL 
CHANGE 

Broadly  speaking,  social  ciiangc  depends 
on  the  relationshijjs  that  hold  in  any  so- 
ciety or  group  between  the  superstructure 
oi  norms  of  that  society  or  group  and  the 
needs  ot  its  individuals.  These  needs  of 
the  individual  include  not  only  the  bio- 
logical needs  like  the  needs  for  food,  sex, 
shelter,  but  also  the  learned  needs,  which 
are  based  on  such  attitudes  as  our  desires 
for  a  certain  kind  of  food,  a  certain  kind  of 
mate,  a  certain  kind  of  house,  as  well  as  our 
ego  strivings,  which  include  our  desires  for 
status,  for  certain  social  rewards  and  a 
place  within  a  group  which  we  respect  and 
with  which  we  have  learned  to  identify 
ourselves. 

Most  of  these  learned  needs  derive  from 
social  norms,  and  frequently  the  individual 
is  frustrated  in  his  attempt  to  satisfy  the 
demands  which  his  culture  makes.  It  is  our 
purpose  here  to  enter  into  the  many  rea- 
sons for  the  discrepancies  that  exist  in 
most  societies  between  the  needs  of  the  in- 
dividuals and  their  satisfaction.  We  should 
have  to  explain  why  it  is  that  some  people 
do  not  get  all  the  food  they  want  in  coun- 
tries potentially  able  to  produce  enough 
food  for  all,  why  more  people  cannot  have 
as  much  education  as  they  want  and  many 
other  matters  that  depend  on  the  structure 
of  society  and  its  functioning.  The  point 
that  needs  emphasizing  here  is  that  the 
frustration  of  needs,  whether  these  needs 
are  biologically  rooted  or  whether  they  are 
socially  derived  like  ego  strivings,  produce 
constant  undercurrents  tending  to  force 
changes  in  the  established  norms. 

There  are,  however,  two  aspects  of  social 
change  that  are  of  special  concern  to  psy- 
chologists. The  first  is  the  general  effect 
of  technological  inventions  upon  our  think- 


ing and  behavior.  Changes  of  this  sort  arc, 
by  and  large,  unplanned  alterations  in  our 
thought  and  behavior  by  the  many  prfnl- 
ucts  of  man's  inventive  genius.  A  second 
force  affecting  change  in  our  thought  anri 
behavior  is  what  we  have  come  to  know  as 
propaganda.  Unlike  the  changes  brought 
about  by  technological  developments, 
propaganda  is  a  planned  and  deliberate  at- 
tempt on  the  part  of  some  interested  group 
to  mold  the  attitudes  of  others  in  a  specific 
direction. 

The  Effects  of  Technology  on 
Thought  and  Behavior 

Few  of  us  realize  the  extent  to  which  the 
ways  we  think  and  the  ways  we  act  are  pat- 
terned by  the  man-made  products  of  oin 
physical  environment.  For  example,  we 
know  that,  by  and.  large,  people  in  the 
United  States  place  more  emphasis  on 
cleanliness  and  personal  hygiene  than  peo- 
ple in  many  other  parts  of  the  world.  And 
some  of  us  may  flatter  ourselves  by  think- 
ing that  we  have  these  habits  of  cleanliness 
simply  because  we  are  'as  a  people'  some- 
how different  in  nature  from  people  who 
live  in  certain  other  countries  in  condi- 
tions of  comparative  filth  and  squalor.  We 
tend  to  forget  that  our  modern  habits  of 
cleanliness  in  the  United  States  are  pos- 
sible and  came  only  as  a  consequence  of 
technological  developments  connected  whh 
plumbing,  sewage  disposal  and  the  inven- 
tion of  mass  production  which  made  pos- 
sible the  enormous  supply  of  piping,  hot 
water,  soap  and  all  the  other  things  neces- 
sary for  millions  of  people  to  keep  them- 
selves clean.  The  sociologist,  AV.  F.  Og- 
burn,  has  pointed  out  tliat  "The  Eskimos 
are  dirty;  but  when  one  considers  tliat  tliey 
have  to  hang  a  bag  of  snow  doAvn  their 
backs  to  melt  it  in  order  to  get  water,  it  is 
seen  tliat  it  is  not  so  easy  to  be  clean  as 


572 


Attitudes  and  Opinions 


when  one  has  only  to  turn  on  a  lancet  of 
hot  or  cold  water  and  reach  for  the  soap. 
In  comparing  peoples,  therefore,  cleanli- 
ness is  seen  to  be  a  matter  not  of  heredity 
but  of  the  type  of  cultine."  * 

Ogburn  also  points  out  how  "Inventions 
such  as  the  -watch  and  the  clock  encourage 
the  habit  of  punctuality.  The  American 
Indians  who  have  no  clocks  or  watches  in 
their  culture  have  little  notion  of  keeping 
appointments  with  any  exactness,  Avhereas 
commuters  working  in  any  large  city  have 
a  very  acute  sense  of  time.  Appointments 
are  regulated  with  precision  and  daily 
schedules  are  laid  off  in  units  of  time.  .  .  . 
Why  primitive  peoples  have  little  use  for 
punctuality  and  why  it  is  so  important  in 
modern  civilization  depend  on  many  other 
factors  than  the  ^vatch,  of  course,  but 
promptness  is  in  general  a  reaction  to  ob- 
jective products  of  ctdtural  life.  Modern 
culture  is  loaded  with  tools  like  the  radio, 
the  railroad  and  the  timeclock,  all  de- 
manding punctuality  of  those  who  use 
them."  f 

Field  studies  made  in  this  country  and 
in  Turkey  show  conclusively  that  people 
who  live  nearest  large  urban  centers,  where 
punctuality  is  necessary  to  carry  on  the  busi- 
ness of  life  as  determined  by  industrial 
activity,  have  much  more  precise  concep- 
tions of  time  than  persons  living  in  remote 
areas  who  may  think  of  time,  not  in  terms 
of  days,  hours  or  minutes,  but  in  terms  of 
the  cycle  of  the  moon,  whether  it  is  before 
or  after  dinner,  the  length  of  time  it  takes 
to  walk  a  certain  distance,  or  the  length  of 
time  it  takes  to  smoke  a  cigarette. 

We  need  not  consider  in  detail  here  the 
countless  ways  in  which  the  thoughts  and 
behavior  of  men  have  been  affected  during 

*  W.   F.   Ogburn   and    M.    I".    Xinikoff,   Sociology, 
Houghton  Mifflin,  1940,  194. 
t  W.  F.  Ogburn  and  .M.  F.  Niml^otf,  op.  cil.,  193  f. 


the  past  few  decades  by  inventions  that 
have  revolutionized  many  of  our  ways  of 
life.  The  student  himself  will  be  able  to 
think  of  niunerous  examples.  The  advent 
of  the  railroad  rapidly  encouraged  the 
gi-owth  of  cities  with  all  the  social  and  psy- 
chological consequences.  The  automobile 
has  brought  us  much  greater  flexibility  of 
movement  and,  among  hundreds  of  other 
effects,  has  tended  further  to  emancipate 
women  by  making  it  easier  for  them  to  get 
away  from  their  homes,  to  see  their  friends 
and  to  work  in  factories  or  offices.  The 
radio  has  increased  our  musical  knowledge 
and  taste  and  made  us  aware  of  what  is  go- 
ing on  in  other  parts  of  the  world. 

The  unleashing  of  atomic  power  appears 
to  be  the  greatest  technological  advance 
made  since  the  invention  of  the  steam  en- 
gine, and  its  enormous  consequences  arc 
now  the  subject  of  much  speculation.  For 
just  as  the  invention  of  the  catapult  tended 
to  make  obsolete  the  castles  of  feudal  times 
with  their  high  surrounding  walls  and  their 
moats  and  played  its  role  in  breaking  down 
the  pattern  of  life  and  the  norms  of 
thought  and  behavior  associated  with  feu- 
dalism, so  the  invention  of  the  atomic  bomb 
seems  likely  to  have  profound  effects  on 
international  relationships,  on  the  value  of 
some  sort  of  world  organization  and  thus 
eventually  on  our  conceptions  of  national 
sovereignty  and  national  rights. 

The  effects  of  technolog)'  on  thought  and 
behavior  are  all  of  necessity  subsequent  to 
the  technological  improvements  themselves. 
The  point  is  obvious,  yet  it  is  important  to 
bear  it  in  mind.  It  means,  as  we  have  al- 
ready noted,  that  the  consequences  of  the 
technological  developments  of  the  past  and 
of  those  yet  to  come  are  not  deliberate,  are 
not  thoroughly  planned  out  ahead  of  time. 
Instead  they  emerge  slowly,  after  their 
causes  have  become  fully  established.    Thus 


Propaganda 


573 


they  appear  lo  have  about  thein  a  certain 
inevitability.  We  cannot  reverse  an  inven- 
tion or  decide  to  do  without  its  conse- 
quences. 

Propaganda 

No  discussion  of  the  processes  of  sociali- 
zation and  of  social  change  would  be  com- 
plete without  mention  of  propaganda. 
The  widespread  use  of  propaganda  today 
is  itself  one  of  the  by-products  of  our  tech- 
nological age  and  of  the  enormous  devel- 
opments that  have  taken  place  in  the  media 
of  communication.  Newspapers,  the  radio 
and  the  movies  are  all  vehicles  of  propa- 
ganda. And  propagandists  of  all  sorts  are 
competing  for  the  attention  of  the  bewil- 
dered layman,  who  is  influenced  by  them 
much  more  than  he  is  likely  to  suspect. 

We  may  define  propaganda  as  a  deliber- 
ate attempt  by  interested  individuals  or 
groups  to  influence  opinions  or  actions  of 
other  individuals  or  groups  with  reference 
to  predetermined  ends.  As  we  have  noted 
above,  propaganda  is  a  consciously  planned 
attempt  to  affect  opinion.  It  is  also  selfish, 
and  it  is  one-sided,  making  use  of  sugges- 
tion and  not  reason.  On  this  account  it 
does  not  include  formal  education.  It 
may  be  good  or  bad  depending  upon  the 
point  of  view  of  the  individual  judging  it. 

Techniques  of  Propaganda 

When  you  observe  the  work  of  the  propa- 
gandist, you  see  essentially  two  psycholog- 
ical techniques  employed  in  ingenious  ways 
to  influence  the  actions  of  people.  The 
first  of  them  is  the  very  simple  device  of 
linking  the  object  or  idea  to  be  propagan- 
dized with  some  attitude,  symbol  or  value 
already  known  to  an  individual  and  al- 
ready likely  to  effect  emotional  reaction. 
If  the  propagandist  is  to  use  this  principle, 
he  must,  of  course,  first  of  all  be  thoroughly 


ac(juainted  with  the  social  values  and  sym- 
bols of  the  culture  in  which  he  works. 

The  clever  propagandist  generally  tries 
to  join  his  idea  to  vague  values  or  symbols 
which  people  tend  to  be  for  or  against,  arul 
about  which  they  feel  stiongly  withrjut 
knowing  precisely  what  the  symbols  mean. 
Take,  for  example,  the  often-repeated  sym- 
bols of  justice,  beauty,  liberty,  economy, 
patriotism,  security,  happiness.  To  these 
and  other  such  attitudes  we  find  the  propa- 
gandist connecting  soaps,  cigarettes,  politi- 
cal camjjaigus,  appeals  to  join  the  Army  or 
to  engage  in  some  crusade.  Vague  emo- 
tionally toned  words,  such  as  Fascist,  Com- 
munist, Red,  atheist,  slacker,  are  used  to 
arouse  us  against  governiTient  officials,  labor 
leaders  or  any  other  individuals  whom  the 
propagandist  thus  freely  labels. 

Most  people  will  agree  that  they  either 
like  or  dislike  what  is  implied  by  these 
vague  words;  and  that  is  precisely  why  the 
propagandist  is  careful  not  to  define  them. 
If  different  individuals  or  groups  should 
ask  themselves  what  they  mean  by  these 
terms,  they  might  discover  themsehes  in 
disagreement.  The  propagandist,  if  forced 
to  define  his  words,  would  lose  part  of 
his  group.  For  example,  suppose  he  is  ap- 
pealing to  liberty  in  a  campaign.  'What  is 
meant  by  that  word?  Liberty  for  whom? 
For  workers  or  for  business?  For  radicals 
or  for  conservatives?  For  Negroes  or  for 
\\'hites?  For  you  or  for  me?  Most  Amer- 
icans claim  they  believe  in  freedom  of 
speech.  Yet  almost  every  week  there  are 
instances  of  these  same  Americans'  protest- 
ing to  a  broadcasting  companv  because  a 
Commiuiist  or  a  Catholic  is  allo^ved  access 
to  the  studios  or  criticizing  a  newspaper 
because  it  has  printed  tlie  speech  of  a  CIO 
organizer,  a  pacifist  or  a  capitalist.  This 
first  method  of  propaganda— the  use  of 
emotionally  toned  symbols— is  illustrated  iii 


^^.^o.Q(D  ^^ 


K 


^. 


'<^ 


dftc/y^c^G^^e^z^^^t^on^^c^ii' 


What  excitement  there  was  when  she  got  her  first 
tooth.  And  her  second!  And  now  there  are  seven. 
Already  she  is  making  brave  attempts  to  say  a 
word  or  two. 

Much  of  your  life  is  given  over  to  keeping  her 
well  and  happy.  For  she  is  so  little  and  lovable  — 
and  so  dependent  on  you. 

During  the  day  and  through  the  darkness  of  night 
you  have  a  feeling  of  safety  and  security  because  of 
the  telephone.    It  is  an  ever-watchful  guardian  of 


your  home  —  ready  to  serve  you  in  the  ordinary 
affairs  of  life  and  in  time  of  emergency. 

In  ofRce  and  store  and  factory  and  on  the  farm 
the  telephone  is  an  equally  important  part  of  every 
activity. 

The  telephone  would  not  be  what  it  is  today  if 
it  were  not  for  the  nation-wide  Bell  System.  Its 
unified  plan  of  operation  has  developed  telephone 
service  to  its  present  high  efficiency  and  brought  it 
within  reach  of  people  everywhere. 


An  extension   telephone  in  your  bedroom,  sun  room,  kitchen  or  nursery  teill  save  many 
steps  each  day.   it  insures  greater  safety  and  privacy  yet  the  monthly  charge  is  small, 

BELL         TELEPHONE  SYSTEM 


FIGURE  241.      PROPAGANDA  WHICH   USES  AN  ESTABLISHED  SYMBOL 

[Reprinted   by   permission  of  the  American  Telephone  and    Telegraph   Company.] 

574 


Propaganda 


575 


Fig.  241,  where  we  see  a  symbol  of  some- 
thing nearly  everyone  loves— a  baby— used 
to  catch  the  eye  and  to  be  associated  witli 
the  services  of  a  commercial  organization. 

The  simple  device  of  piopaganda  just  de- 
scribed is  so  commonly  employed  that  most 
people  are  by  now  aware  of  the  trick. 
Thus,  if  the  propagandist  has  some  pur- 
pose to  conceal  because  it  is  not  socially 
acceptable,  or  if  he  believes  he  must  use 
more  subtle  methods,  he  employs  a  second 
principle.  He  builds  up  an  attitude  or 
value  around  a  product  or  an  idea  by 
means  of  indirect  suggestion.  The  specific 
use  of  this  principle  is  so  varied  and  so 
changing  that  even  the  most  expert  analyst 
is  often  fooled  unless  he  knows  the  selfish 
interests  of  the  groups  conducting  the 
propaganda  and  carefully  scrutinizes  all 
that  he  reads  and  hears.  In  using  this 
technique,  for  instance,  the  propagandist 
frequently  gets  his  propaganda  into  news- 
papers as  news  or  as  editorial  opinion.  An- 
other method  used  to  build  up  an  attitude 
or  value  for  some  idea  is  to  disguise  propa- 
ganda as  explanation— explanation  which 
is,  however,  distorted  and  incomplete. 
Since  the  use  of  this  second  principle  is  so 
dependent  upon  the  situation  in  question 
and  upon  the  tenor  of  the  time,  a  great 
company,  organization  or  government  will 
hire  an  expert  in  propaganda  who  calls 
himself  a  public  relations  counsel,  and 
whose  business  it  is  to  feel  the  public's 
pulse  in  all  classes  and  vocations  and  to 
find  out  where  people  are  most  suggestible. 
The  public  relations  counsel,  once  hired, 
will  work  for  his  client  through  the  news- 
papers, the  radio,  the  medical  journal,  the 
textbook,  the  cut-out  for  the  kiddies.  This 
use  of  such  indirect  suggestion  is  illustrated 
in  Fig.  242. 

If  we  really  want  to  understand  this  im- 
portant  force  in  modern  life,   however,   a 


knowledge  of  the  techniques  of  the  propa- 
gandist is  only  half  the  story.  As  psyclio]f>- 
gists  we  must  ask  ourselves  what  it  is  in 
us  that  makes  projjaganda  possible  and  ef- 
fective.    Why  do  the  technicjues  work.' 

Quite  a  Handicap 


FIG.    242.      PROPAGANDA  DliSIG.NED  TO   BLILD   UP   AN 
ATTITUDE 

Cartoon  printed  on  the  editorial  page  of  a  dailv 
paper  in  a  Pennsylvania  town  of  about  100,000  pop- 
ulation. [From  the  Gazette  and  Daily,  York,  Pa., 
April  21,  1947.] 

Receptivity  to   Propaganda 

There  are  several  good  psychological  rea- 
sons for  the  success  of  propaganda.  First, 
as  we  have  already  seen,  the  great  major- 
ity of  the  words  in  our  language  or  any 
other  language  are  freighted  with  emo- 
tion. Most  of  the  time  we  do  not  react 
to  the  dictionary  meaning  of  the  ^vord,  but 
to  a  whole  complex  of  feeling  that  sur- 
rounds it.  The  word  love  can  hardly  be 
mentioned  without  arousing  a  host  of  senti- 
ments in  every  individual.  The  word 
Turk  will  arouse  in  some  Americans  an 
unfavorable  attitude  even  though  most  of 
these  same  Americans  have  never  knoAsm  a 


576 


Atfifudes  and  Opinions 


Turk.  We  learn  and  accept  these  attitudes 
toward  words,  our  society's  value  of  words, 
at  the  same  time  that  we  learn  their  mean- 
ing. Our  attitudes  are  determined  for  us 
by  others. 

A  second  reason  why  the  propagandist  is 
so  successful  is  that  most  of  us  are  unsure 
of  oiuselves.  We  seek  a  meaning  for  those 
things  we  do  not  understand.  Since  we 
usually  have  neither  the  time  nor  the  fa- 
cilities for  studying  problems  ourselves  and 
since  we  do  not  want  to  appear  ignorant 
on  many  questions,  we  accept  the  judgment 
of  some  authority,  of  some  official,  of  some 
newspaper  editor,  of  some  columnist  or 
radio  commentator.  We  feel  that  he  must 
know  more  about  the  issue  than  we  do,  but 
we  forget  that  the  opinions  of  such  experts 
are  frequently  only  elaborated  rationaliza- 
tions of  their  own  points  of  view,  ration- 
alizations which  are  given  to  us  as  ob- 
jective, critical  analyses.  With  life  becom- 
ing more  and  more  specialized,  we  have  to 
depend  more  and  more  upon  other  people 
for  oiu"  judgments.  The  propagandist 
snatches  at  this  opportunity.  He  gives  us 
Ills  meaning.  He  satisfies  our  desire  for  a 
solution  to  such  questions  as  what  shall  I 
buy,  how  shall  I  vote,  what  shall  I  believe— 
satisfies  us  so  as  to  satisfy  himself. 

A  third  reason  for  his  success  is  that 
nearly  everyone  is  anxious  to  presei've  his 
own  position  in  life,  to  maintain  or  to  en- 
hance his  status.  A  person  has,  therefore, 
a  tendency  to  accept  the  type  of  propa- 
ganda which  makes  him  feel  superior  to 
other  persons  or  makes  him  feel  that  his 
own  status  is  better  than  the  other  fellow's. 
One  race  likes  to  be  reassured  that  it  is  su- 
perior to  another  race.  Some  rich  people 
like  to  think  of  the  poor  as  happy-go-lucky 
or  as  irresponsible.  We  accept  the  political 
philosophy  best  suited  to  our  interests. 
That  is  one  reason  why  most  people  read 


a  newspaper  wdiose  editorials  or  news  slants 
fit  their  prejudices,  why  many  people  turn 
off  the  radio  if  a  speaker  begins  to  tell  them 
what  they  hope  is  not  true. 

In  brief,  the  propagandist  by  appeals  to 
a  man's  already  existing  frame  of  referent  c 
leads  him  to  extend  that  frame  to  include 
the  object  or  the  idea  in  ^vhich  the  propa- 
gandist is  interested.  Or  the  propagandist 
may  try  to  impose  on  the  individual  a 
frame  of  reference  which  he  will  accept 
because  it  gives  meaning  to  his  environ- 
ment or  because  it  enables  him  the  better 
to  rationalize  his  own  position  in  life. 

Social  Bias  of  Propaganda 

We  must  remember  that  the  tools  and  fa- 
cilities which  provide  the  means  for  propa- 
ganda are  mainly  in  the  hands  of  those  who 
own  and  control  the  mass  media  of  com- 
niunication  or  of  those  whose  business  in- 
terests or  political  power  directly  or  indi- 
rectly control  these  mass  media.  In  oin- 
own  country,  for  example,  the  newspapers 
and  radio  are  supported  by  advertisers  who 
pay  for  space  or  time.  Most  of  us  have  be- 
come so  accustomed  to  this  fact  that  avc 
take  it  for  granted,  although  in  many  coun- 
tries of  the  world  the  radio  is  either  a  go\- 
ernment  monopoly  or  a  public  corpora- 
tion, and  in  some  the  newspapers  are  gov- 
ernment controlled. 

Even  our  popidar  magazines  tend  to  per- 
petuate, presumably  unconsciously,  oin^ 
ciurent  majority  biases.  Figure  243,  for 
example,  based  on  an  analysis  of  a  sample 
of  popular  magazines  which  appeared  be- 
tween 1937  and  1943,  shows  how  these 
magazines  tend  to  misrepresent  in  their  se- 
lection of  characters  the  true  complexion 
of  our  population.  "The  Americans"  indi- 
cated in  this  figure  are  tliose  people  who 
are  portrayed  as  "white  Protestants  with  no 
distinguishable  ancestry  of  foreign  origin.'" 


Propaganda 


577 


In  this  sense  of  an  'American'  only  sixty 
per  cent  of  the  people  in  the  United  States 
but  ninety  per  cent  of  the  people  in  the 
stories  are  'Americans.' 

Thus  it  tomes  about  that  public  opin- 
ion is  truly  biased  by  propaganda.  Insofar 
as  propaganda  is  effective,  public  opinion 


Jews 
Negroes 

Other 
descent 

Anglo-Saxon  b^8.8%^ 
and  Nordic  ^-^^ ' '  ^ '  '^^ 
descent 


The 
Americans 


.1.9% 
-2.8% 
-3.3% 


Distribution  Distribution 

of  the  of  the 

population  characters 

in  the  stories 

FIGURE  243.      HOW  MAGAZINE  STORIES  DISTORT  THE 
POPULATION   OF  THE   UNITED   STATES 

Shows  the  true  distribution  of  the  United  States 
population  about  1940  and  the  counts  of  fictional 
characters  in  magazine  stories.  Foreigners  in  the 
stories  are  omitted.  An  'American'  is  anyone  who 
does  not  fall  in  one  of  the  other  categories.  In  this 
sense  only  60  per  cent  of  the  people  in  the  United 
States,  but  90  per  cent  of  the  people  in  the  stories, 
are  'American.'  [From  B.  Berelson  and  P.  J.  Salter, 
Public  Opinion  Quarterlx,  1946,  10,  175.] 

lias  a  dependence  on  wealth,  for  control  of 
the  sources  of  propaganda  costs  money,  and 
the  social  norms  of  those  who  have  con- 
trol inevitably  affect  the  way  they  use  the 
control.  No  agency  or  government  is  likely 
to  support  views  that  lessen  its  own  power. 
Thus  in  the  United  States  the  means  of 
propaganda  favor  those  attitudes  which  go 
along  with  belief  in  private  enterprise, 
whereas  the  government-controlled  propa- 


ganda of  tlic  Soviet  Union  favors  a  wholly 
different  set  of  norms.  As  the  inevitable 
biases  come  to  be  recognized  there  may  be, 
as  there  is  in  the  United  States,  an  attempt 
to  offset  them  fjy  counterpropaganda,  but 
the  bias  for  self-defense  of  the  controlling 
interests  is  as  unavoidable  as  are  the  ego 
involvements  that  make  propaganda  ef- 
fective. 

The  goals  of  propaganda  are  not  neces- 
sarily evil.  I^ropaganda  may  be  directed 
toward  the  selfish  ends  of  some  small  gioup 
or  toward  the  enlightenment  and  the  im- 
provement of  living  conditions  for  a  whole 
people.  In  either  case  the  psychological 
role  of  propaganda  is  the  same. 

MEASUREMENT    OF    ATTITUDES 
AND    OPINIONS 

We  have  seen  what  attitudes  do  and 
where  they  come  from.  Our  next  topic  is 
their  measurement. 

The  word  opinion  is  generally  used  to 
refer  to  attitudes  which  have  been  ex- 
pressed. The  measurement  of  attitudes  is 
now  generally  termed  measurement  of 
opinions,  and  the  most  significant  methods 
of  measuring  opinions  today  are  those  we 
associate  with  public  opinion  surveys. 

Since  the  results  of  public  opinion  polls 
are  becoming  of  increasing  interest  to  the 
layman  as  he  reads  them  in  his  ne^\spapers 
or  in  a  magazine  and  since  the  technique 
of  appraising  public  opinion  is  now  being 
widely  used  by  psychologists  and  odiers  in 
the  social  sciences,  we  can  confine  our  dis- 
cussion of  attitude  measurement  to  a  dis- 
cussion of  the  measurement  of  public  opin- 
ion by  the  survey  technique.  It  should  be 
borne  in  mind,  however,  that  the  public 
opinion  survey  described  here  is,  as  a 
method,  only  one  of  many  different  meth- 
ods available  to  the  social  scientist  for  gadi- 


578 


Attiiudes  and  Opinions 


ering  information.  He  also  relies  on  case 
studies,  on  analyses  of  gioup  situations,  on 
developmental  studies,  on  the  comparative 
field  studies  of  the  ethnologist,  as  well  as  on 
experiments. 

Sampling 

There  is  nothing  mysterious  about  a  pub- 
lic opinion  poll.  It  operates  on  the  very 
simple  principle  that  if  an  accurate  minia- 
ture sample  of  the  total  population  is  made, 
the  opinions  of  the  people  in  that  sample 
will  faithfully  reflect  the  opinions  of  the 
population  as  a  whole.  The  basic  problem 
of  the  public  opinion  poll  is  to  select  an 
accurate  miniature  sample— one  that  con- 
tains people  of  every  variety,  one  that  con- 
tains people  who  have  all  the  different  char- 
acteristics, occupational  groupings,  geo- 
graphic distribution,  religious  affiliation  or 
any  other  affiliations  or  identifications  that 
might  be  expected  to  affect  their  opinions 
in  a  significant  way.  So  every  miniature 
sample  of  the  population  will  have  its  fair 
share  of  old  people  and  young  people,  of 
Protestants  and  Catholics,  of  Democrats  and 
Republicans,  of  men  and  women,  of  people 
who  live  in  cities,  of  farmers,  of  business- 
men and  skilled  workers,  etc. 

Incredible  as  it  seems,  if  3000  prop- 
erly representative  voters  in  the  United 
States  are  questioned,  the  statistical  chances 
are  99  out  of  100  that  their  answers  to  a 
question  will  not  vary  more  than  4  or  5 
per  cent  from  the  opinions  of  the  whole 
voting  population  of  50,000,000.  And  the 
chances  are  95  out  of  100  that  these  opin- 
ions of  a  sample  of  3000  will  not  vary  more 
than  3  per  cent  in  another  sample  of  3000. 
As  the  size  of  the  sample  is  reduced,  the 
size  of  the  error  increases  but  not,  perhaps, 
as  much  as  we  might  expect.  For  example, 
the  chances  are  95  out  of  100  that,  if  1500 


people  are  included  in  a  carefully  selected 
sample,  the  maximum  error  due  only  to 
sampling  would  not  be  more  than  5  per 
cent;  with  500  people  the  maximum  error 
would  not  be  expected  to  be  over  8  per 
cent;  but  with  only  100  people  the  error 
expected  from  sampling  alone  would  rise 
to  20  per  cent. 

How  do  we  go  about  getting  this  minia- 
ture sample  of  the  population?  So  far  two 
major  methods  of  sampling  for  opinion 
have  been  developed.  One  is  known  as 
areal  sampling,  the  other  as  quota  sam- 
pling. Areal  sampling  involves  the  careful 
selection  ahead  of  time  of  specified  people 
who  li\'e  in  specified  dwelling  units.  This 
selection  is  made  on  the  basis  of  maps  from 
which  specific  counties  may  be  chosen,  on 
the  basis  of  further  information  obtained 
about  that  county,  on  the  basis  of  city  di- 
rectories and  many  other  sources  of  data 
■iv'hich  tell  the  investigator  how  people  are 
distributed  in  different  dwelling  units. 
The  purpose  of  this  specification  is  to  in- 
crease the  randomness  of  the  sample  and 
leave  as  little  selection  as  possible  to  the 
individual  interviewer.  We  can  describe 
the  method  of  quota  sampling  more  in  de- 
tail since  it  is  less  complicated  and  is 
mainly  used  by  those  organizations  whose 
survey  results  are  publicly  known,  such  as 
the  Gallup  Poll,  the  Fortune  survey,  the 
National  Opinion  Research  Center  and 
many  other  investigators  sampling  on  a 
statewide  or  local  basis. 

Suppose  the  poll  administrator  decides 
that  he  will  have  3500  persons  in  his  quota 
sample.  First  of  all,  the  poll  administrator 
determines  on  the  basis  of  census  figures 
what  percentage  of  these  persons  should 
come  from  each  of  the  major  sections  of  the 
country— in  other  words,  what  quota  to  as- 
sign  each    sectional    unit.      Then,    within 


Measurement  of  Attitudes  and  Opinions 


579 


each  section,  he  decides  on  the  basis  of  cen- 
sus figures  what  proportion  of  the  inter- 
views sliould  be  with  farmers,  wliat  jjro- 
portion  should  come  from  small  towns, 
what  proporlion  from  large  cities.  Then, 
still  on  the  basis  of  known  information,  he 
decides  how  many  of  these  people  should 
be  in  the  upper  income  group,  how  many 
in  the  middle  income  group,  how  many  in 
the  lower  income  group,  how  many  on  re- 
lief. He  also  decides  how  many  should  be 
white  and  how  many  colored  people.  Most 
polling  organizations  have  representatives 
scattered  throughout  the  country  who  do 
their  interviewing  for  them.  Nearly  all 
polls  rely  on  personal  contact  rather  than 
on  mail  ballots,  for  mail  ballots  are  un- 
reliable. They  are  generally  returned  in 
greater  proportion  by  the  better-educated, 
upper  income  group. 

An  interviewer  in  a  certain  town  is  then 
instructed  from  his  central  office  to  inter- 
view, let  us  say,  20  people.  Of  these,  4 
are  to  be  fanners,  the  rest  are  to  be  people 
living  in  the  interviewer's  own  town.  The 
interviewer  is  told  to  get  so  many  people 
in  the  upper  income  group,  so  many  in  the 
middle  and  so  many  in  the  lower  income 
group.  He  is  also  told  to  get  about  half 
men  and  half  women,  to  divide  his  sample 
more  or  less  evenly  between  people  who 
are  over  40  years  of  age  and  those  who  are 
under  40.  We  have,  then,  six  'controls'  in 
determining  this  quota  sample:  section  of 
the  country,  rural-urban  distribution  within 
each  section,  income  distribution,  race 
(white  or  Negro),  sex  and  age.  Such  fac- 
tors as  education,  religion  or  occupation 
are  not  used  because,  obviously,  one  cannot 
easily,  if  at  all,  judge  these  things  by  a 
person's  appearance  or  by  where  he  hap- 
pens to  li^e.    But  by  and  large  it  is  found 


that,  if  tlic  controls  we  have  noted  arc  used, 
the  miniature  sample  thus  obtained  will 
faithfully  reflect  the  educational,  religious 
and  occujjational  distribution  of  the  total 
jjopulation. 

Accuracy 

One  leason  for  tlic  increasing  use  of  pub- 
lic opinion  surveys  in  commercial,  govern- 
ment and  scientific  work  is  the  accuracy 
they  have  demonstrated  in  predicting  be- 
havior. Their  validity  has  been  shown 
with  respect  to  elections.  So  far  the  polls 
have  made  forecasts  of  365  national  or  state 
elections,  and  their  average  error  has  been 
around  4  per  cent.  Improvement  has  gone 
on  with  the  years.  For  example,  the  Amer- 
ican Institute  of  Public  Opinion  (Gallup 
Poll),  which  has  made  197  of  these  365 
forecasts,  had,  in  1936,  an  average  error  of 
6  per  cent.  Between  the  years  1936  and 
1940  its  error  was  reduced  to  an  average 
of  4^  per  cent.  From  1940  to  the  present 
writing,  the  Institute's  average  error  has 
been  only  2^  per  cent. 

Aside  from  occasional  referenda,  elec- 
tions provide  the  only  easy  means  for  test- 
ing poll  accuracy.  In  many  ways  this  fact 
is  unfortunate  and  unfair  to  the  polls  them- 
selves, since  there  are  so  many  variables 
that  determine  an  election  that  cannot  pos- 
sibly be  foi'ecast  by  a  poll.  For  example, 
elections  are  often  determined  by  the 
•weather,  with  bad  weather  tending  to  keep 
the  farmers  at  home  and  tlius  reducing  the 
Republican  vote,  since  farmers,  by  and 
large,  vote  Republican.  Furthermore,  al- 
though an  interview^  can  determine  with 
high  accuracy  how  a  person  "will  vote,  no 
sure-fire  method  has  yet  been  discovered  to 
determine  whedier  or  not  a  person  will 
vote  even  thoudi  he  savs  he  will.     Hence 


580 


Atfitudes  and  Opinions 


only  about  2  per  cent  of  an  error  made  by 
a  public  opinion  poll  in  forecasting  an 
election  can  be  charged  to  sampling;  the 
rest  is  caused  by  such  other  factors  as  turn- 
out, last-minute  shifts  and  the  effect  of 
political  party  machines. 

To  illustrate  how  much  more  important 
is  the  selection  of  a  sample  than  the  size  of 
a  sample,  two  predictions  based  on  ex- 
tremely small  samples  may  be  cited.  In 
one  instance,  with  only  200  cases  carefully 
distributed,  the  New  York  gubernatorial 
election  in  1942  was  forecast  with  an  ac- 
curacy of  3  per  cent.  In  the  same  year  a 
referendum  taken  in  Canada  was  correctly 
forecast  within  414  per  cent  with  only  200 
cases.  Such  small  samples  are,  of  course, 
not  adequate  substitutes  for  larger  surveys. 
For  one  thing  the  investigator  is  likely  to 
be  accurate  with  so  small  a  sample  only 
when  opinion  is  fairly  uniform  within  the 
various  population  groups. 

Setting  the  Problems  and  Questions 

Certainly  the  most  important,  the  most 
difficult  and  the  most  delicate  operations 
connected  with  any  survey  of  public  opin- 
ion are  slicing  issues  meaningfully  and  sig- 
nificantly and  preparing  questions  that  are 
clear  and  understandable  and  are  so  un- 
biased that  they  will  not  affect  the  answer 
itself.  The  investigator  must  be  very  cer- 
tain in  his  own  mind  just  what  he  is  try- 
ing to  find  out,  what  relationships  of  opin- 
ion might  exist,  what  possible  determinants 
of  opinion  he  can  look  for  and   the  like. 


His  questions  must  be  neither  vague  nor 
obscure.  They  should  not  encourage  stere- 
otyped answers  unless  rigid  stereotypes  are 
part  of  the  problem  to  be  studied.  Ques- 
tions should  avoid  technical  or  unfamiliar 
words.  They  should  not  force  answers 
into  only  a  few  categories  unless  and  until 
the  investigator  knows  by  asking  free  and 
open  questions  what  is  the  respondent's 
point  of  view  before  any  alternatives  for 
choice  have  been  presented  to  him.  Fur- 
thermore, before  asking  a  person's  opinion 
on  some  subject,  it  is  of  the  utmost  impor- 
tance to  find  out  if  the  person  questioned 
has  ever  thought  about  that  subject  or  has 
ever  heard  about  it.  And  in  addition  to 
the  problem  of  determining  the  direction 
of  opinion,  it  is  often  important  to  discover 
another  dimension  of  opinion,  its  intensily, 
if  the  investigator  is  interested  in  finding 
out  how  tenaciously  that  opinion  is  likely 
to  be  held  and  how  much  it  means  to  the 
individual. 

We  can  illustrate  some  of  the  problems 
encountered  in  constructing  a  survey  by 
reference  to  an  actual  questionnaire  pre- 
pared by  the  American  Institute  of  Public 
Opinion  in  March,  1947.  The  purpose  of 
this  study  was  to  find  out  what  the  reaction 
of  the  American  people  was  to  what  has 
become  known  as  the  "Truman  Doctrine" 
as  enunciated  by  President  Truman  in  his 
speech  to  Congress  asking  for  loans  to 
Greece  and  Turkey.  The  complete  Gallup 
ballot  follows.  We  may  consider  these 
questions  in  order. 


THE  GALLUP  POLL 

The  American  Institute  of  Public  OriNioN 
—Wants  YOUR  Opinion— 


L     If  the  question  of  national  prohibition  should  come  up  again,  would  you  vote  wet  or  drr  ? 
(  )  WET  (  )  DRY  (  )  NO  OPINION 


Polling  581 

2.  Have  you  heard  or  read  about  Truman's  speech  to  Congress  asking  for  J4^X)  million  to  help  Greece  and 

Turkey? 

(  )  YES  (  )  NO 

IF  YES,  ASK  ALL  OF  THE  FOLLOWING  QUESTIONS;  IF  NO,  SKIP  TO  QUESTION  16: 

3.  What  do  you  think  are  the  chief  reasons  FOR  helping  Greece  and  Turkey? 


4.     Can  you  tell  me  what  are  the  chief  reasons  AGAINST  helping  Greece  and  Turkey?- 


5.     What  is  your  own  feeling  as  to  what  we  should  do  about  this?- 


6.     Why  do  you  feel  this  way?_ 


7a.  Would  you  like  to  see  your  Congressman  vote  for  or  against  the  bill  asking  for  $250  million  to  aid  Greece? 

(  )  FOR  (  )  AGAINST  (  )  NO  OPINION 

l>.  How  strongly  do  you  feel  about  this — very  strongly,  fairly  strongly,  or  not  at  all  strongly? 

(  )  VERY  (  )  FAIRLY  (  )  NOT  STRONGLY  (  )  NO  OPINION 

c.   And  would  you  like  to  see  your  Congressman  vote  for  or  against  the  bill  asking  for  $1  SO  million  to  aid  Turkey : 

(  )  FOR  (  )  AGAINST  (  )  NO  OPINION 

J.  How  strongly  do  you  feel  about  this — very  strongly,  fairly  strongly,  or  not  at  all  strongly? 

(  )  VERY  (  )  FAIRLY  (  )  NOT  STRONGLY  (  )  NO  OPINION 

8a.  Would  you  favor  sending  American  civilian  experts  over  to  CJreece  to  help  supervise  the  uses  to  which  this 
money  will  be  put? 

(  )  YES  (  )  NO  (  )  NO  OPINION 

/>.   Would  you  favor  sending  American  civilian  experts  over  to  Turkey  to  help  supervise  the  uses  to  which  this 
money  will  be  put? 

(  )  YES  (  )  NO  (  )  NO  OPINION 

9a.  Would  you  favor  sending  American  military  advisers  to  train  the  Greek  army? 

(  )  YES  (  )  NO  (  )  xNO  OPINION 

i.  Would  you  favor  sending  them  to  train  the  Turkish  army? 

(  )  YES  (  )  NO  (  )  NO  OPINION 

10.     Why  do  you  think  this  problem  was  not  turned  over  to  the  L^nited  Nations  Organization  to  handler 


582  Atiitudes  and  Opinions 

11.     Do  you  think  it  should  have  been  turned  over  to  the  United  Nations  Organization? 

(  )  YES  (  )  NO  (  )  NO  OPINION 


12.     If 

we 

aid  Greece 

and  Turkey, 

what 

do 

you 

think  Russia 

will  Ho? 

\3a.  Do  you  think  that  lending  money  to  aid  Greece  and  Turkey  is  or  is  not  likely  to  get  us  into  war? 
(  )  IS                                               (  )  IS  NOT                                       (  )  NO  OPINION 
i.  Why  do  you  feel  this  way  ? 


14a.  Do  you  think  the  present  Greek  government  has  the  backing  of  the  majority — that  is,  more  than  half^ 
of  the  Greek  people? 

(  )  YES  (  )  NO  (  )  NO  OPINION 

i.   Do  you  think  the  present  Turkish  government  has  the  backing  of  the  majority — that  is,  more  than  half — 
of  the  Turkish  people? 

(  )  YES  (  )  NO  (  )  NO  OPINION 

15.  Suppose  other  nations  find  themselves  in  the  same  fix  as  Greece.     Do  you  think  the  United  States  will  have 

to  do  something  about  it? 

(  )  YES  (  )  NO  (  )  NO  OPINION 

16.  (Tenerally  speaking,  should  the  United  States  take  a  strong  stand  in  European  affairs,  or  should  we  try  to  get 

out  of  European  affairs? 

(  )  TAKE  STAND  (  )  GET  OUT  (  )  NO  OPINION 

17rt.  Do  you  remember,  FOR  CERTAIN,  whether  or  not  you  voted  in  the  1944  presidential  election,  or  did 
something  keep  you  from  voting? 
1(  )  YES,  VOTED  4(  )  KEPT  FROM  VOTING 

2(  )  NO,  DIDN'T  VOTE  5(  )  DON'T  REMEMBER 

.-?(  )  NO,  TOO  YOUNG  TO  VOTE 
IF  YES,  VOTED,  ask: 
i.  Did  you  vote  for  Dewey,  Roosevelt,  or  Thomas? 

6(  )  DEWEY  7(  )  ROOSEVELT  8(  )  THOMAS  9(  )  OTHER 

18.  If  a  presidential  election  were  being  held  TODAY,  which  party  would  you  vote  for — the  Democratic  or 

Republican? 

(  )  DEMOCRATIC  (  )  REPUBLICAN 

(  )  SOCIALIST  (  )  OTHER  (  )  UNDECIDED 

And  now,  just  a  question  or  two  to  help  me  keep  track  of  the  cross-section  I'm  getting: 

19.  What  is  the  last  grade  or  class  you  completed  in  school? 
1(  )  NO  SCHOOLING 

2(  )  GRAMMAR  SCHOOL  (GRADES  1  THROUGH  8) 


Polling 


583 


3(  )  HIGH  SCHOOL,  INCOMPLETE  (9th,  10th  or  11th  GRADE) 
4(  )  HIGH  SCHOOL,  GRADUATED  (12th  GRADE) 
5(  )  COLLEGE,  INCOMPLETE! 
6(  )  COLLEGE,  GRADUATED  I 


-What  type  of  college? 


20.  What  is  your  occupation?  (Record  SPECIFIC  occupation,  not  just  industry  or  name  of  organization  worked 

for.) 

(If  housewife,  widow  or  student,  record  occupation  of  head  of  family.     If  retired  or  unemployed  give 
former  occupation.) 


(  )  YES 


(  )  NO 


21«.  Is  there  a  telephone  in  your  home? 
IF  YES,  ask: 
i>.   Is  the  telephone  listed  either  under  your  name  or  the  name  of  a  member  of  your  immediate  family? 

(  )  YES  (  )  NO 


PLEASE  COMPLETE  ALL  VITAL  INFORMATION  BEFORE  LEAVING  RESPONDENT 
Classify  respondent  as:  Check  whether: 

(  )  Wealthy  (  )  Average     (  )  Old  Age  Assistance  (  )  Car  (  )  Man  (  )  White 

(  )  Average  plus     (  )  Poor  (  )  On  Relief  (  )  No  Car  (  )  Woman  (  j  Colored 


Respondent's  Age_ 
City 


Address- 
State 


(Street  and  numberj 


Date  of  interview. 


1947      Interviewer- 


We  see  that  the  first  question  has  noth- 
ing whatever  to  do  with  the  topic  under 
consideration.  Why,  then,  was  it  asked? 
The  reason  is  that  this  particular  question, 
dealing  with  national  prohibition,  has  been 
found  from  experience  to  be  one  that  peo- 
ple enjoy  answering.  In  other  words,  it 
makes  a  good  opener.  People  begin  to 
think  the  interview  is  going  to  be  fun.  So 
this  question  is  included  only  in  order  to 
enlist  the  cooperation  of  the  respondent. 
In  question  2,  the  respondents  are  asked  if 
they  have  ever  heard  or  read  of  President 
Truman's  speech  to  Congress  asking  for  the 
loans  to  Greece  and  Turkey.  This  is 
known  as  a  filter  question.  Obviously,  if 
people  have  never  heard  of  the  speech, 
there  is  no  use  asking  them  a  lot  of  ques- 


tions about  it,  for  any  opinions  they  might 
give  would  only  be  useless  falsifications. 

Questions  3,  4  and  5  are  examples  of 
what  are  known  as  open-ended  or  jree  an- 
swer- questions.  Here  the  investigator  tries 
to  find  out  before  he  asks  any  specific  ques- 
tions involving  alternative  courses  of  ac- 
tion, what  the  respondent  himself  thinks 
about  President  Truman's  statement. 
What  are  the  arguments  for  and  against  the 
Truman  Doctrine  and  how  does  the  re- 
spondent himself  feel  about  it?  Question 
6  is  a  probing  question  in  -which  the  investi- 
gator tries  to  find  out  what  some  of  the 
underlying  reasons  are  for  die  person's 
opinion. 

In  questions  7a  and  Ic,  tlie  respondent 
is   confronted   with    the   same   proposition 


584 


Attitudes  and  Opinions 


that  his  Congressman  must  face,  whether 
or  not  to  vote  for  or  against  the  bill  ask- 
ing for  the  loans.  Although  the  respond- 
ent may  have  expressed  one  point  of  view 
or  another  with  definite  qualifications  in 
question  5,  and  although  similar  qualifica- 
tions may  exist  in  the  mind  of  his  Congress- 
man, both  the  citizen  and  the  Congress- 
man in  the  end  have  to  choose  one  or  the 
other  course  of  action.  Questions  7b  and 
7d  are  intensity  questions,  designed  to  find 
out  how  strongly  a  person  feels  tlie  way  he 
does.  Questions  8a  and  8b  and  9fl  and  9b 
are  designed  to  tap  opinion  on  some  of  the 
more  important  qualifications  which  the 
pretesting  (preliminary  interviewing  before 
the  final  ballot  was  prepared)  had  shown 
were  important.  Questions  10  through  15 
are  designed  to  find  out  what  people  see 
as  some  of  the  implications  of  the  policy 
enunciated  by  President  Truman  and  how 
the  policy  will  affect  the  United  Nations, 
the  Soviet  Union,  and  the  likelihood  of 
war.  Question  16  is  a  question  that  has 
been  asked  many,  many  times  by  the  Gal- 
lup Poll  as  one  of  its  trend  questions. 
These  trend  questions  are  particularly  valu- 
able in  determining  to  what  extent  opinion 
changes  with  events.  An  illustration  of  the 
use  of  trend  questions  in  public  opinion 
studies  is  found  in  Fig.  244.  All  the  rest 
of  the  Institute's  ballot  is  made  up  of  ques- 
tions which  give  the  'background'  data  on 
the  respondent. 

Analysis  of  Results 

With  this  information  the  sample  popu- 
lation can  be  'broken  down'  in  a  number 
of  ways.  The  opinions  of  different  groups 
of  people  may  be  compared;  that  is  to  say, 
we  can  compare  the  opinions  of  Republi- 
cans and  Democrats,  people  of  different  oc- 
cupations, people  of  different  income 
groups,  and,  if  we  want  a  more  elaborate 


analysis,  we  can  make  what  are  known  as 
'two-way'  or  'three-way'  breakdowns  by  fur- 
ther stlbdi^■iding  the  population.  For  ex- 
ample, we  could  make  a  two-way  break- 
down and  find  out  what  differences,  if  any, 
appeared  between  Democrats  and  Republi- 
cans who  were  further  classified  according 
to  their  economic  status.  How  the  differ- 
ences between  rich  and  poor  Democrats 
compared  with  the  differences  between  rich 
and  poor  Republicans.  Or  we  could  make 
a  three-way  breakdown  and  find  out  how 
the  opinions  of  the  Democrats  and  Repub- 
licans, that  we  had  divided  into  different 
income  groups,  compared  when  the  popu- 
lation was  further  subdi\ided  into  educa- 
tional levels.  That  would  give  us  rich 
Democrats  who  had  been  to  college,  poor 
Democrats  from  college,  rich  Democrats 
who  stopped  at  the  eighth  grade,  and  all 
the  other  combinations  for  Democrats  and 
the  corresponding  combinations  for  Repub- 
licans. In  making  these  elaborate  break- 
downs, the  investigator  must  always  watch 
the  number  of  respondents  who  finally  fall 
into  one  of  the  small  subcategories  ob- 
tained. For  unless  his  sample  has  a  large 
enough  number  of  cases,  he  may  end  up 
with  so  few  people  in  various  categories 
that  his  results  will  be  statistically  insignifi- 
cant. An  example  of  a  two-way  break 
down  by  political  party  affiliation  (as  de- 
termined by  how  a  person  voted  in  1944) 
and  economic  status  on  one  of  the  ques- 
tions asked  is  shown  in  Table  XXXVI.  It 
can  be  seen  there  that  the  people  who  did 
not  vote  in  1944  were  more  ignorant  of 
Truman's  speech  to  Congress  proposing  aid 
to  Greece  and  Turkey  than  those  who  did 
vote,  and  that  those  who  voted  for  Roose- 
velt were  less  aware  of  the  speech  than 
those  who  voted  for  Dewey.  However,  to 
infer  from  this  that  political  affiliation  as 
such  is  a  'cause'  of  ignorance  of  Truman's 


Analysis  of  Public  Opinion 


585 


3     <       = 


sjaqiunu  xspuj  ssuof-MOQ 


586 


Attitudes  and  Opinions 


TABLE  XXXVI 

Breakdown    of   Opinion    by   Vote    and    Economic 
Status 

"Have  you  heard  or  read  about  Truman's  speech  to 
Congress  asking  for  $400  million  to  help  Greece  and 
Turkey?" 

Number 

of  Cases    Yes        No 

Dewey:  Tot3l  806      92%       8% 

Upper  Income  186     100  0 

Middle  Income  309       93  7 

Lower  Income  311       86         14 


oosevelt:  Total 

1217 

83 

17 

Upper  Income 

121 

99 

1 

Middle  Income 

374 

92 

8 

Lower  Income 

722 

76 

24 

idnt  vote:  Total 

821 

80 

20 

Upper  Income 

69 

91 

9 

Middle  Income 

221 

89 

11 

Lower  Income 

531 

76 

24 

speech  would  be  quite  unjustified.  For  we 
find  that  people  in  the  lower  income 
groups,  irrespective  of  whether  or  not  they 
\oted  or  how  they  voted,  show  significant 
and  consistent  variations.  We  can  see  in 
this  table  that  Dewey  voters  represent 
a  higher  income  group  than  Roosevelt 
voters,  and  we  know  from  previous  studies 
that  economic  status  is  correlated  positively 
with  education.  So  this  two-way  break- 
down begins  to  show  us  what  other  factors 
to  look  for  in  order  that  our  understanding 
of  the  figures  obtained  in  the  original  ques- 
tion should  be  more  complete. 

Another  useful  method  of  analyzing  the 
data  obtained  is  to  make  a  comparison  of 
people's  opinions  on  different  questions. 
This  gives  the  investigator  some  idea  of 
how  opinions  hang  together,  which  ones 
are  related  to  which  other  ones,  what  some 
of  the  more  basic  attitudes  of  people  are. 
In  Table  XXXVII  we  find  from  this  cross- 
tabulation  that  those  people  who  believe 
the  problem  of  aiding  Greece  and  Turkey 


TABLE  XXXVII 

Cross-Tabulation  Comparing  Opinion  on  Likeli- 
hood OF  War  as   Consequence   or  Loans   to 
Greece  and  Turkey  and  Advisability  of 
Turning  Problem  Over  to  United 
Nations 
[Based  only  on  those  who  had  heard  of  Truman 
proposal.] 

Should  problem  of  aiding 

Greece  and  Turkey  be  turned 

over  to  United  Nations? 

Yes  No  No  opinion 


loan  likely  to  get 

us  into  war? 

Is 

41% 

30% 

28% 

Is  not 

47 

61 

28 

No  opinion 

12 

9 

44 

should  be  turned  over  to  the  United  Na- 
tions are  more  inclined  than  others  to  be- 
lieve the  loans  are  likely  to  get  us  into  war. 

How  to  Poll     " 

Suppose  you  wanted  to  carr)'  out  a  pub- 
lic opinion  survey.  What  steps  would  you 
have  to  follow?  First  of  all,  of  course,  you 
would  have  to  find  the  money  necessarj'  to 
conduct  your  survey.  In  actual  practice  in 
this  country,  surveys  are  supported  either 
by  newspapers,  magazines,  government  de- 
partments or  agencies,  foundations,  busi- 
ness or  labor  organizations,  or  some  group 
interested  in  obtaining  information  on  a 
specific  problem.  You  would  then  go  about 
designing  your  sample  according  to  the 
problem  at  hand  on  the  basis  of  the  quota 
or  areal  method  or,  possibly,  some  com- 
bination of  the  two.  After  your  sample 
had  been  designed,  you  would  know  at 
what  points  you  would  need  to  have  inter- 
views made.  Then,  unless  you  had  full- 
time  interviewers  to  travel  around  from 
place  to  place,  you  would  recruit  an  inter- 
viewing staff  distributed  among  the  locali- 
ties  you    had    selected    as    sample    points. 


How  to  Poll 


587 


These  people  would  not  be  employed  lull 
time  but  would  merely  take  on  your  inter- 
viewing assignment  as  an  extra  part-time 
job. 

How  would  you  go  about  finding  inter- 
viewers? The  most  efficient  method  seems 
to  be  to  write  to  reliable  people  in  the 
different  towns  who  are  in  a  position  to 
understand  your  problem  and  to  recom- 
mend someone  for  the  job  of  interviewing. 
Newspaper  editors,  school  superintendents, 
principals  have  proved  to  be  good  'recom- 
menders.'  Then  you  yourself  or  a  highly 
trained  representative  in  whom  you  have 
confidence  would  talk  to  each  potential  in- 
terviewer and  tiy  to  judge  him  on  the  basis 
of  his  stability,  his  honesty,  the  ease  and 
ability  with  which  he  meets  people,  the 
interest  he  is  likely  to  have  in  his  work, 
etc.  It  is  known  that  housewives,  school 
teachers,  social  service  workers  and  stu- 
dents have  proved  to  be  conscientious  in- 
terviewers, interested  in  the  work,  with 
extra  time  to  spend  and  a  desire  to  earn 
some  extra  money.  When  you  have  de- 
cided that  a  person  is  a  good  bet,  he  must 
be  trained  by  you  or  your  field  representa- 
tive. He  must  be  told  something  of  the 
whole  method  of  public  opinion  polling, 
he  must  know  how  ballots  are  made  up,  he 
should  watch  you  conduct  several  inter- 
views and  then  conduct  some  himself  while 
you  watch  him  and  until  you  are  satisfied 
with  his  work.  After  the  interviewers  have 
been  hired  and  trained,  you  must,  from 
your  central  office,  do  all  you  can  to  keep 
up  their  interest  and  morale  in  such  ways 
as  providing  them  with  results  of  surveys 
they  have  w^orked  on,  sending  them  news- 
letters in  which  their  names  are  mentioned 
occasionally  and  some  interesting  experi- 
ences of  interviewers  are  recited.  You  must 
keep  a  careful  check  on  the  quality  of  their 
work  and  on  their  integiity  by  reviewing 


the  interviews  they  return,  checking  them 
against  other  interviewers  in  the  same  or 
comparable  locality  or,  occasionally,  using 
in  your  surveys  questions  known  as  'trap' 
questions  which  will  enable  you  to  tell 
whether  or  not  an  interviewer  has  actually 
gone  out  and  made  interviews  or  whether 
he  has  sat  at  home  filling  out  his  ballots. 

After  your  sample  has  been  designed  and 
your  interviewers  employed,  you  will  be  in 
a  position  to  go  ahead.  But  no  matter  how 
smart  you  are  or  how  much  experience  you 
have  had  in  the  construction  of  actual 
questionnaires,  you  cannot  merely  sit  in 
your  office,  write  out  questions  and  then 
send  them  to  your  interviewers.  All  the 
questions  must  be  carefully  pretested  in 
your  local  area  by  you  and  others  who  are 
trained  to  detect  flaws  in  the  questions. 
You  must  be  sure  that  the  questions  you 
are  asking  are  completely  unambiguous, 
that  they  are  unbiased.  Even  the  most  ex- 
perienced poll  administrators  will  find  in 
actual  practice  that  new  cjuestions  they  ask 
have  to  be  revised  many  times  before  they 
are  properly  stated  for  inclusion  on  the 
questionnaire. 

When  your  questionnaire  has  been  con- 
structed, pretested  and  accepted,  you  have 
it  printed  or  mimeographed.  You  send  to 
each  of  your  interviewers  the  number  of 
copies  he  needs  to  complete  his  assignment, 
together  with  an  instruction  sheet  Avhich 
gives  him  his  particular  quota,  that  is  to 
say,  which  tells  him  how  many  people  and 
what  types  of  people  you  want  him  to  in- 
terview and  explains  to  him  some  of  the 
background  of  the  particular  questions  con- 
tained on  the  sursey.  The  interviewer  is 
usually  given  three  or  four  days  in  Avhich 
to  complete  his  assignment.  He  then  re- 
turns the  questionnaires  to  yoirr  office, 
■where  they  go  through  the  processes  of 
coding   (getting   punch    card    numbers    on 


588 


Attitudes  and  Opinions 


them)  and  o£  actual  transference  of  infor- 
mation to  the  punch  cards.  Then  the  cards 
:ire  put  through  the  sorting  and  tabulating 
machines.  Your  final  job  is  analyzing  and 
interpreting  the  data  you  have  thus  col- 
lected. It  may  be  that  you  will  find  out 
that,  after  all,  you  have  not  asked  the  right 
questions  or  enough  questions  and  that  you 
will  have  to  undertake  more  probing  be- 
fore you  get  what  you  think  is  a  reliable 
answer  to  your  original  general  query. 
Such  is  the  modern  method  of  opinion 
measurement. 

REFERENCES 

1.  Allport,  G.  \V.  .Mtiiudes.  In  C.  Murchison 
(Ed.)  ,  ./  handbook  of  social  psychology. 
^Vorceste^■.  Mass.:  Clark  University  Press,  1935. 
Chap.  17. 

.\  comprehensive  review  and  evaluation  of 
studies  dealintr  with  the  nature  of  attitudes. 

2.  Cantril,  H.  (Ed.),  Gauging  public  opinion. 
Princeton:   Princeton  University  Press,  1944. 

.\  compilation  of  studies  dealing  with  some 
of  the  major  problems  of  measuring  public 
opinion  and  interpreting  data. 

3.  Coffin,  T.  E.  Some  conditions  of  suggestion 
and  suggestibility:  a  study  of  some  attitudinal 


and  situational  factors  influencing  the  process 
of  suggestion.  Psychol.  Monogr.,  1941,  No.  241. 
.\n  excellent  study  reporting  experiments  and 
studies  based  on  questionnaires.  The  author 
brings  all  his  data  together  in  a  systematic 
formulation. 

4.  Gallup,  G.  A  guide  to  public  opinion  polls. 
Princeton:    Princeton    University    Press.    1944. 

The    best    introduction    yet    written  to    the 

problems     encountered     in     measuring  public 

opinion.      Prepared    in    question    and  answer 
form. 

5.  Horowitz.  E.  L.  The  development  of  attitude 
toward  the  Negro.  Arch.  Psychol.,  1936,  No. 
194. 

An  excellent  study  of  the  way  in  which  atti- 
tudes are  formed.  The  study  takes  full  account 
of  the  social  context  and  reports  data  from  dif- 
ferent parts  of  the  country. 

6.  Murphy,  G.,  Murphy,  L.  B.,  and  Ne^vcomb,  T. 
M.  Experimental  social  psychology.  New 
York:   Harper,  1931. 

A  monimiental  \olume  reviewing  with  some 
interpretation  and  evaluation  much  of  the 
work  in  the  field  of  .social  psvcholog^•  up  to 
1937. 

7.  Sherif,  M.,  and  Cantril.  H.  The  psychology 
of  ego-involvements.     New  York:  Wiley,  1947. 

A  systematic  discussion  of  the  process  of  so- 
cialization, with  the  subtitle  Social  attitudes 
and  idei7tifications. 


CHAPTER 


25 


Social  Relations  of  the  Individual 


I T  is  a  commonplace  that  society  is  deli-         PRIMARY    SOCIAL    RELATIONS 


widely  understood  is  the  consequence  that 
the  old  philosophy  (or  absence  of  one)  of 
letting  problems  of  social  relations  resolve 
themselves  through  conflict  and  'muddling 
through'  no  longer  serves.  Nowadays  we 
all  know  how  a  small  conflict  between 
labor  and  management  can  tie  up  an  en- 
tire economy.  It  takes  no  crystal  ball  to 
see  that  presently  a  small  national  conflict 
would  'atomize'  civilization.  The  fact 
must  be  faced;  civilization  today  must  work 
efficiently  to  work  at  all.  And  it  cannot 
work  efficiently  except  through  a  knowl- 
edge of  human  relations. 

The  acquisition  of  the  elements  of  that 
knowledge  is  the  aim  of  this  chapter.  For 
the  purposes  of  discussion  it  is  convenient 
to  treat  social  relations  under  three  broad 
headings:  (1)  primary  social  relations,  (2) 
relations  of  the  individual  to  the  group, 
both  the  assembled  group  and  the  dispersed 
group,  and  (3)  relations  between  groups, 
the  social  interaction  of  groups  upon  each 
other.  The  special  example  of  the  relation 
of  the  individual  to  the  group  is  found  in 
leadership  and  of  social  interaction  in 
group  prejudice.  The  latter  we  shall  con- 
sider in  detail. 


Direct  person-to-person  relationships 
constitute  the  primai7  interactions  of  so- 
cial life.  They  are  primary  in  respect  of 
time,  directness  and  importance.  They  are 
primary  in  respect  of  time  because  person- 
to-person  relations  constitute  the  earliest 
social  experiences  of  the  organism  in  the 
history  of  both  the  individual  and  his 
group.  They  are  primary  in  directness  be- 
cause as  face-to-face  relations  they  are  the 
most  influential  point  of  contact  between 
the  individual  and  his  culture.  They  are 
primary  in  importance  because  it  is  the 
early  parent-child  relationship  Avhich  deter- 
mines, in  large  part,  the  adult  personality. 

General  Functions  of  the  Family 

The  origin,  as  well  as  the  most  signifi- 
cant setting,  of  the  primary  social  relations 
lies  within  the  family.  Largely  through 
the  medium  of  intimate  face-to-face  con- 
tacts the  family  serves  three  general  func- 
tions in  social  life. 

First,  the  family  is  the  major  agency  for 
socialization  of  the  child.  The  new  recruit 
to  life  initially  wants  what  he  wants  when 
he  wants  it.  This  biological  egoism  must 
be  reduced  to  mutual  gi\e-and-take  if  so- 
ciety is  to  function  efficiently.  So  the  child 
is  compelled  to  learn  that  to  have  his  cake 


This  chapter  was  prepared  by  Leo  P.  Crespi  of  Princeton  University. 

589 


590 


Social  Relations  of  the  Individual 


he  must  drink  his  milk  first,  to  enjoy  his 
own  toys  he  must  respect  the  property  of 
others.  Through  primary  experience  with 
frowns  and  smiles,  cuffs  and  caresses,  the 
child  is  ultimately  domesticated  to  the  re- 
quirements of  social  living. 

Second,  the  family  functions  importantly 
in  transmitting  the  cultural  heritage. 
Through  its  intimate  contacts,  the  spe- 
cific ways  of  thinking,  doing  and  feeling, 
which  are  the  traditions  of  a  society,  are 
channeled  into  the  individual.  The  child 
acquires  folkicays— the  routine  habits  of 
life  in  his  culture,  like  wearing  shoes,  ad- 
dressing people  as  Mr.  or  Mrs.  and  eating 
with  a  knife  and  fork.  He  acquires  mores 
—the  customs  buttressed  with  moral  sanc- 
tions as  codes  of  decency  and  respect  for 
property.  And,  especially  in  primitive  so- 
cieties, he  acquires  <flZ;oo5— prohibitions 
which  arouse  feelings  of  fear  or  horror  at 
the  thought  of  their  violation,  like  the  gen- 
eral incest  taboo  or  the  reaction  in  our  so- 
ciety to  cannibalism.  Finally,  among  the 
most  important  of  the  child's  acquisitions 
are  stereotypes  (p.  563)  and  prejudices. 
Prejudice  is  treated  in  the  last  half  of  the 
present  chapter,  -which  contains  also  nu- 
merous examples  of  stereotypes. 

The  processes  of  socialization  and  cul- 
tural transmission  produce  the  overall  simi- 
larity of  social  habits  in  a  culture.  It  must 
not  be  forgotten,  however,  that  they  also 
produce  the  differences.  The  family  is  the 
main  agency  for  perpetuating  the  social 
hierarchies  of  a  society.  In  particular  it 
inculcates  class  differences,  the  differences 
in  social  habits  associated  with  differences 
in  the  income  and  occupational  levels  of 
parents.  Although  both  of  them  wear  shoes 
and  eat  with  a  knife  and  fork,  there  is  a 
vast  difference  between  the  attitudes  and 
actions  of  the  boy  brought  up  on  the  lower 
East  side  of  New  York  City  and  those  of 


his  compatriot  brought  up  on  a  Long 
Island  estate.  Upper  class  families  perpet- 
uate elaborate  codes  of  etiquette  which  dis- 
play their  superior  status,  whereas  lower 
classes  lack  the  means  to  participate  in 
such  customs. 

The  third  function  of  the  family  derives 
most  directly  from  primai-y  social  relations. 
It  is  the  provision  of  an  outlet  for  the  ex- 
pression of  personality.  Group  relation- 
ships dominate  our  modern  life,  and  in 
them  there  is  scant  opportunity  to  express 
the  whole  personality.  As  a  member  of  a 
business  organization  or  a  church  or  a 
political  party,  you  generally  participate 
only  as  a  part  of  yourself.  You  reveal  in 
the  setting  of  each  group  only  that  facet 
of  your  personality  which  is  advantageous. 
It  is  in  the  intimate  family  group  that  you 
can  cease  functioning  as  a  cog  in  a  ma- 
chine. There  you  can  be  yourself.  You 
can  know  and  be  known  for  what  you 
really  are  as  a  whole  personality.  That 
there  is  a  real  need  for  such  intimate  group- 
ings is  shown  by  the  substitvUes  for  the 
family  circle  which  a  person  quickly  finds 
once  he  has  departed  from  the  home. 

The  Family  in  Relation 
to  Social  Control 

The  family,  like  the  church,  the  school 
and  the  state,  is  an  institution.  That  is  to 
say,  it  is  a  grouping  of  individuals  whose 
attitudes  and  actions  are  organized  toward 
the  cooperative  pursuit  of  mutual  ends. 
Yet,  over  and  above  being  itself  an  institu- 
tion, the  family  is  also  the  matrix  of  all  the 
other  institutions  in  a  society.  This  fact 
is  obvious  in  many  ways,  especially  in  the 
manner  in  which  social  control,  without 
which  institutions  could  not  exist,  is  itself 
rooted  in  the  institution  of  the  family. 

Social  control  embraces  the  processes  by 
means  of  which  groups  of  people  are  ma- 


Primary  Social  Relations 


591 


nipulated,  led  and  sometimes  regimented 
into  conformity  with  Xraditional  social 
norms.  It  is  a  significant  fact  that  people 
obey  their  institutional  leaders  in  part  be- 
cause they  have  learned  to  obey  their  par- 
ents. It  is  no  accident  that  the  empire 
builder  wishes  to  preserve  the  family. 

Social  control  draws  upon  the  family  in 
four  ways. 

First,  it  feeds  upon  the  emotional  attach- 
ments which  have  developed  in  the  family. 
Much  of  the  hold  of  religion  upon  the  in- 
dividual, for  example,  stems  from  the  fact 
that  children  generally  absorb  their  reli- 
gious attitudes  at  their  mother's  knee  and 
hence  unconsciously  weave  into  them  their 
affection  for  their  parents.  For  a  man  later 
to  reject  religion  may  prove  to  be  emotion- 
ally equivalent  to  his  rejecting  his  mother. 

Second,  social  control  draws  upon  fear 
and  dependency  in  family  relationships. 
The  child  learns  both  to  fear  and  to  be  de- 
pendent upon  the  authority  of  his  parents. 
These  reactions  are  later  transferred  to 
other  sources  of  authority.  In  this  connec- 
tion it  may  be  said  that  not  a  little  of  the 
German  acceptance  of  an  authoritarian 
regime  can  be  traced  to  the  habits  of  rigid 
obedience  inculcated  in  German  family 
life. 

Third,  the  family  makes  social  control 
possible  through  the  consta?icy  and  the  per- 
sonal quality  of  its  relationships.  Where 
relations  are  shifting,  retribution  often 
fails  to  catch  up  with  asocial  acts.  Where 
relations  are  impersonal,  the  individual 
tends  to  be  indifferent  to  what  others  think 
of  his  actions.  It  is  only  through  the  con- 
stancy and  intimacy  of  the  primary  social 
relations  of  the  family  that  the  conscience 
can  develop  which  makes  men  responsive 
to  social  demands. 

Finally,  the  family  directly  makes  for  so- 


cial control  in  the  adult  life  of  the  individ- 
ual through  the  responsibilities  that  mar- 
riage and  parenthood  impose  upon  him. 
The  necessities  of  bread  winning  cuib  irre- 
sponsibility and  make  more  difficult  the 
challenging  of  traditional  values. 

With  the  content  of  socialization  and  cul- 
tural transmission  sketched  in,  we  may  now 
turn  our  attention  to  the  mechanisms. 
The  four  of  them  which  stand  out  in  signifi- 
cance are  imitation,  suggestion,  identifica- 
tion and  language. 

Imitation 

Observers  have  long  noted  the  similari- 
ties of  behavior  in  a  society,  how  its  newly 
born  members  tend  to  mirror  the  patterns 
of  behavior  exhibited  by  those  about  them. 
To  account  for  this  mirroring  some  have 
supposed  that  there  is  an  instinct  of  imi- 
tation, an  innate  tendency  for  individuals 
to  behave  in  the  manner  in  which  others 
are  behaving.  The  notion  that  imitative- 
ness  is  innate  and  instinctive  has,  however, 
now  been  disproved.  Imitation  does  not 
occur  automatically  whenever  the  oppor- 
tunity arises,  but  only  under  particular  con- 
ditions. For  instance,  the  adolescent  boy 
imitates  the  ball  playing  of  his  older 
brother,  but  he  definitely  does  not  imitate 
the  doll  playing  of  his  younger  sister. 

Imitativeness  is  simply  a  learned  mech- 
anism of  satisfying  motives.  People  learn 
to  imitate  whene\er  it  helps  them  to 
achieve  satisfaction.  They  learn  equally 
well  not  to  imitate  w^hen  imitation  leads 
to  no  rewards  or  to  punishment.  Three 
types  of  imitation  are  distinguishable  in 
terms  of  how  it  is  learned.  There  are 
simple  imitation,  matched-dependent  be- 
havior and  copying.  Not  all  similarities  in 
group  behavior,  ho^vever,  need  be  cases  of 
imitation.     People  may  respond  similarly 


592 


Social  Relations  of  the  Individual 


to  the  same  stimulus  quite  independently 
of  one  another.  Good  examples  are  the  so- 
called  coenotropes.  All  the  members  of  a 
group  may  turn  up  their  collars  in  the  face 
of  a  blizzard  not  because  of  imitation,  but 
because  such  a  response  is  to  each  of  them 
his  obvious  and  compelling  means  of  ad- 
justment to  the  stomi. 

Simple  imitation  is  a  kind  of  condition- 
ing. It  is  used  in  the  acquisition  of  lan- 
guage by  the  child,  a  process  which  is  de- 
scribed farther  on. 

Matched-dependent  behavior  develops 
from  chance  learning.  An  illustration  of 
it  might  run  as  follows.  Jim  and  Bobby 
are  playing  in  a  room  when  Jim  hears  his 
father's  footfall  on  the  stairs.  He  has 
learned  that  it  means  candy,  so  he  runs  to 
greet  his  father.  His  younger  brother, 
Bobby,  has  not  learned  to  use  this  clue, 
but  by  chance  on  this  occasion  he  hap- 
pened to  be  running  in  the  same  direction 
as  his  brother  when  his  father  arrived— so 
he  too  receives  candy.  The  law  of  effect 
operates.  Thereafter  Bobby  tends  to  run 
more  frequently  at  the  mere  sight  of  his 
brother  running,  in  this  situation  and  even- 
tually in  others  as  well.  In  a  word,  Bobby 
has  learned  to  imitate  Jim  because,  more 
often  than  not,  he  has  got  candy  for  do- 
ing it. 

The  combination  of  learning  and  mo- 
tivational conditions  involved  in  matched- 


dependent  behavior  has  been  conveniently 
diagrammed  in  Table  XXXVIII.  Jim's 
response  to  his  father's  footfall  is  to  run 
to  him.  Jim's  running  becomes  the  stimu- 
lus for  a  similar  response  by  Bobby,  who 
thus,  being  rewarded,  has  his  response  re- 
inforced. Since  Bobby  can  also  hear  the 
footfall,  he  will  soon  become  conditioned 
to  it,  and  then  can  get  candy  without  hav- 
ing Jim  for  a  stimulus. 

Copying  is  an  elaboration  of  matched- 
dependent  behavior  in  which  a  critic  func- 
tions as  well  as  a  model.  For  example,  the 
model  may  sound  a  certain  note  which  the 
imitator  wishes  to  copy  without  being  able 
to  know  when  his  attempted  matchings  are 
correct.  Hence  he  needs  a  critic  to  point 
out  similarities  and  differences.  In  copy- 
ing, the  critic  is  also  a  guide  in  the  specifi- 
cation of  such  environmental  clues  as  will 
ultimately  enable  the  copier  to  become  in- 
dependent of  the  model.  A  matcher 
knows,  for  example,  that  at  certain  points 
in  the  ceremony  he  ought  to  stand  or  kneel 
in  church  but  does  not  know  the  precise 
occasions.  So  he  continues  to  match  those 
who  do.  The  copier,  on  the  other  hand, 
will  have  eventually  learned  not  only  to 
perform  the  proper  responses  but  also  to 
interpret  the  environmental  signals  for 
himself.  He  acquires  the  conditioned  re- 
sponses of  those  who  know. 


TABLE  XXXVIII 

Matched-Dependent  Imitation 

The  model  is  already  conditioned  for  running  to  the  stimulus  of  the  father's  footfall,  and  the  model's  response 
becomes  the  stimulus  to  the  same  (imitative)  response  in  the  imitator.  [Adapted  from  N.  E.  Miller  and  J.  Bollard,. 
Social  learning  and  imitation,  Yale  University  Press,  1941.] 


Motivating  drive 
Stimulus  to  response 
Conditioned  response 
Reinforcing  reward 


Model 
appetite  for  candy 
father's  football 
running  (of  model) — matched- 
eating  candy 


Imitator 
appetite  for  candy 
dependent — >  running  of  model 

running  (of  imitator) 
eating  candy 


Imitation,  Suggestion  and  Identification 


593 


Suggestion 

Suggestion,  as  we  have  already  learned 
(p.  564),  can  be  looked  upon  most  simply 
as  the  unreasoned  acceptance  of  proposi- 
tions. To  the  degree  that  an  individual 
accepts  ideas  or  courses  of  action  without 
exercising  his  powers  of  reasoning  or  log- 
ical analysis,  he  is  said  to  be  influenced  by 
suggestion. 

Proneness  to  suggestion  or  suggestibility 
is  promoted  by  conditions  which  produce 
either  inhibition  or  dissociation  of  critical 
thought  processes.  The  simplest  kind  of 
inhibition  is  caused  by  fatigue  or  emotional 
excitement.  When  a  person  is  either  too 
tired  or  too  excited  to  think,  he  is  ready 
prey  to  suggestion.  That  the  Nazis  knew 
this  fact  well  is  indicated  by  their  care  in 
scheduling  party  rallies  in  the  evening 
when  the  people  were  weary,  and  by  their 
calculated  efforts  to  stir  vip  excitement. 

The  most  important  inhibitory  condi- 
tion of  suggestibility  is  not  physiological 
or  emotional  in  origin,  like  those  above, 
but  motivational.  Reasoning  gets  inhib- 
ited by  wishful  thinking.  In  such  cases  in- 
dividuals are  suggestible  because  either  (1) 
they  badly  need  an  interpretation  for  a  be- 
wildering situation  or  (2)  they  already  have 
a  fixed  interpretation  for  a  situation,  and 
hence  a  'will  to  believe.'  It  is  for  the  first 
reason  that  perplexed  citizens  accept  the 
oversimplified  schemes  of  crackpot  Utopi- 
ans. It  is  for  the  second  that  staunch  party 
members  accept  without  qualification  the 
line  laid  down  by  party  leaders. 

Suggestibility  through  dissociation  arises 
when  the  individual  is  thinking  about 
something  else.  To  secure  his  effects  the 
magician  often  makes  use  of  deliberate  dis- 
sociation or  misdirection.  In  the  perform- 
ance of  a  card  trick,  he  may  patter  on  about 
mathematical  formulas  to  get  his  audience 


thinking  in  this  vein  so  that  ho  may  plant 
other  ideas  about  the  pack  of  cards,  ideas 
which  they,  otherwise  occupierl,  fail  to  scru- 
tinize critically. 

Suggestion  plays  a  very  important  part 
in  propaganda.  Since  propaganda  is  es- 
sentially an  attempt  to  secure  acceptance 
of  propositions  through  any  and  all  means, 
propagandists  find  suggestion  of  great  ad- 
vantage, especially  when  the  attitudes  or 
actions  they  are  seeking  to  promulgate  are 
not  likely  to  be  accepted  in  the  light  of 
critical  sci-utiny.  Education,  unlike  propa- 
ganda, minimizes  suggestion  as  much  as  pos- 
sible and  aims,  though  not  always  %vith  suc- 
cess, to  have  all  propositions  accepted  only 
when  they  have  passed  critical  examination. 

Identification 

In  the  preceding  chapter  we  noted  that, 
at  the  beginning  of  life,  the  individual 
cannot  distinguish  at  all  between  himself 
and  his  environment.  He  never  completely 
succeeds.  Initially  the  infant  is  not  able 
to  distinguish  what  is  his  self  from  what 
is  not.  He  does  not  know  the  boundaries 
of  his  body.  He  draws  his  thumb  from 
his  mouth  and  then  cries  because  the  thumb 
has  got  away.  He  pulls  his  toes  so  hard 
that  they  hurt  and  cries  the  while  because 
something  is  hurting  him.  Since  he  can  in 
some  measure  predict  and  control  his  par- 
ents, he  feels  that  their  qualities  and  ac- 
tions are  part  of  him. 

Later  through  a  process  of  learning  tlie 
bodily  self  becomes  differentiated.  It  is 
probably  significant  that  ^vhen  the  child 
strikes  his  body,  he  recei\es  two  stimula- 
tions—one from  the  part  struck  and  one 
from  the  offending  member;  but  that,  when 
he  strikes  an  object,  there  is  only  one 
stimulation.  He  perceives  also  that  he 
can  both  feel  and  see  his  own  movements, 
whereas  external  movements  can  onlv  be 


594 


Social  Relaiions  of  the  Individual 


seen.  Through  these  and  further  processes 
the  bodily  self  becomes  a  stable  individu- 
ated perception.  But  what  is  true  in  per- 
ception need  not  hold  for  emotion.  From 
childhood  on  through  adulthood  to  death, 
the  things  and  actions  that  the  individual 
likes  and  can  control  he  still  feels  are  a  part 
of  his  ego,  even  though  he  perceives  them 
as  beyond  the  boundaries  of  his  body.  The 
workman  regards  his  tools  as  part  of  him- 
self, as  extensions  of  his  arms  and  fingers. 
The  horseman  feels  his  horse  a  part  of 
himself  as  it  responds  to  his  slightest  signal. 

Language 

One  of  the  most  significant  factors  in 
human  socialization  is  language.  It  is  it- 
self a  cultural  acquisition,  but  once  ac- 
quired it  becomes  the  master  key  to  vast 
stretches  of  culture  beyond  the  individual 
in  time  and  place.  The  development  of 
language  in  the  race  is  too  uncertain  a 
speculation  to  be  considered  here;  but  of 
its  development  in  the  individual  we  know 
a  great  deal.  The  four  important  stages  in 
the  development  of  language  are  as  follows. 

(1)  Random  vocalization.  From  the 
birth  cry  on,  an  infant's  wiggling  of  toes 
and  waving  of  arms  are  accompanied  by 
the  constituents  of  words— distinguishable 
vowels  and  consonants,  'clicks,'  'giunts'  and 
'gurgles.'  This  wide  repertory  of  random 
vocalizations  that  the  infant  early  exhibits 
is  the  raw  material  for  his  communication, 
all  ready  to  be  fashioned  through  learning 
into  language. 

(2)  Circular  conditioned  responses.  Be- 
tween five  and  twelve  months  of  age,  the 
infant  becomes  repetitious  in  his  vocaliza- 
tions, uttering  the  same  syllable  repeatedly. 
This  'babbling'  reflects,  according  to  one 
accepted  theory,  an  intricate  process  of 
learning,  the  circular  conditioned  response. 


A.  Circular  conditioned  response 


■Do;/ — i% 


B.  Simple  imitation 


W3^ 


L 


C.  Con'^itioning  of  meaning 


D.  Meaning  acquired 

FIGURE   245.      PROCESSES   IN    LANGUAGE  DEVELOP- 
MENT 

[.\dapted  from  J.  F.  Dashiell,  Fundamentals  of 
general  psychology,  Houghton  Mifflin,  1937,  p.  527.] 

As  shown  in  Fig.  245^^  when  the  child 
articulates  da,  for  example,  he  hears  his 
own  sound  while  he  makes  the  response. 
Thus  the  sound  da  becomes  a  conditioned 
stimulus  for  saying  da.  So  the  infant  keeps 
on  hearing  da,  saying  da,  hearing  doj  saying 
da,  a  circular  conditioning  which  continues 


Language 


595 


indefinitely.  Presumably  the  initial  utter- 
ance was  a  matter  ol  chance,  and  the  cessa- 
tion of  babbling  is  a  matter  ol  fatigue. 

(3)  Social  selection  of  particular  vocali- 
zations. The  child  will  in  this  way  estab- 
lish through  his  own  vocal  play  a  wide 
variety  of  circular  conditioned  responses. 
Once  they  are  established  the  adults  around 
him  begin  to  have  a  voice  in  which  of  them 
will  be  emphasized.  If  they  utter  the  right 
conditioned  stimuli,  their  sounds  will  acti- 
vate in  the  child  particular  babbling 
chains.  Suppose,  as  in  Fig.  2i5B,  the  adult 
says  doll,  which  may  sound  somewhat  like 
da  to  the  child.  He  starts  babbling  da. 
This  event  marks  a  case  of  simple  imita- 
tion, the  illustration  of  which  was  delayed 
until  now.  It  rests  simply  upon  activation 
of  circular  conditioned  responses  by  some 
other  person. 

By  virtue  of  this  conditioning-born  imi- 
tation, the  sounds  the  child  practices  and 
thus  makes  his  own  are  those  which  he 
hears  about  him.  So  it  is  that  he  acquires 
the  linguistic  stamp  of  his  specific  culture, 
be  that  anything  from  German  with  its 
gutturals  to  Hottentot  with  its  clicks.  The 
selection  of  the  proper  babblings  is  hastened 
by  parental  interest  in  the  child's  new 
'words.'  Let  the  child  approximate  any 
word  of  his  mother's  tongue  and  she  will 
echo  it  back  with  enthusiasm,  thus  reward- 
ing the  child  with  attention  and  reinforc- 
ing the  response. 

(4)  Acquisition  of  meaning.  In  prompt- 
ing the  child's  babblings  the  mother  will 
employ  words  in  reference  to  specific  ob- 
jects. As  shown  in  Fig.  245C^  in  saying 
doll  she  is  likely  to  wave  a  doll  in  the 
child's  face.  Gradually  through  condition- 
ing the  sight  of  the  doll  comes  to  reinstate 
the  verbal  response  to  it  (Fig.  245D).  This 
is  the  birth  of  meaning.  Through  this  proc- 
ess the  child  comes  to  name  objects  and 


situations.  At  first  the  naming  is  char- 
acteristically too  general.  The  word  milk, 
lor  example,  may  stand  for  the  entire  feed- 
ing situation.  Soon,  however,  this  vague 
meaning  gives  place  to  greater  specificity 
as  the  child  hears  the  word  spoken  in  dif- 
ferent contexts,  yet  always  with  reference 
to  the  same  object. 

With  meaning  initiated,  vocabulary  be- 
gins to  form.  Once  the  child  catches  on 
to  the  fact  that  everything  has  a  name— an 
event  which  occasionally  happens  with 
great  suddenness— vocabulary  may  grow  by 
leaps  and  bounds.  It  is  at  this  stage  that 
the  child  begins  to  combine  words  into 
sentences.  At  first  vocabulary  is  limited 
to  nouns  (the  names  of  conditioned  stimuli); 
later  the  child  acquires  verbs,  and  last  the 
qualifying  words  and  those  denoting  rela- 
tionships. 

Primarily  we  ha\'e  been  considering  the 
acquisition  of  substantive  meanings,  but 
words  can  also  have  affective  or  emotional 
significance.  Suppose  little  Bobby  of  four- 
teen months  is  being  taken  for  a  walk 
when  a  large  dog  trots  up  and  tries  to  lick 
his  face.  Should  Bobby  be  teiTified  by  his 
nurse's  screaming  in  fright,  it  is  quite  pos- 
sible that  a  conditioned  fear  response  will 
thereafter  be  associated  w'ith  the  w-ord  dog. 
one  that  may  persist  for  years.  Nor  need 
all  affective  values  be  acquired  so  dramati- 
cally. Many  of  them  are  simply  taken  over 
from  parental  evaluations  as  embodied  in 
pronouncements  that  this  is  good  and  that 
is  bad. 

Semantics 

For  centuries  language  has  been  largelv 
taken  for  gianted,  but  in  recent  years  there 
has  been  a  movement  to  overhaul  language 
habits  with  the  aim  of  improving  social 
relations.  This  movement  is  called 
semantics. 


596 


Social  Relations  of  the  Individual 


One  of  the  major  contentions  of  the 
semanticists  is  that  people  fail  to  appreciate 
that  the  connection  between  symbols  and 
their  referents  is  purely  arbitrary  and  con- 
ventional. To  illustrate  this  confusion  be- 
tween words  and  things,  they  point  to  state- 
ments like  "The  pig  is  rightly  named  for  it 
is  such  a  dirty  animal."  Or  better,  the 
story  of  the  Englishman  who,  in  undertak- 
ing to  prove  that  English  is  the  best  lan- 
guage, said:  "Take  the  word  knife;  the 
French  call  it  coiiteau,  the  Germans  Messer, 
the  Danes  kniv,  while  the  English  say 
knife,  and  that's  what  it  really  is." 

In  advertising  particularly,  semanticists 
believe  that  people  are  being  misdirected 
by  word  magic  when  they  act  as  if  naming 
things  agreeably  somehow  makes  them  bet- 
ter. Three  times  as  many  men  buy  a  felt 
hat  when  it  is  named  Tyrolia  as  when  it  is 
unnamed.  If  sofas  sell  well,  "snuggle 
sofas"  of  the  same  shape,  appearance  and 
quality  sell  better.  Ten  times  more  women 
buy  hosiery  when  the  shade  of  it  is  called 
Gala  than  when  it  is  offered  as  just  plain 
beige.  Euphemisms,  semanticists  hold,  also 
illustrate  the  confusion  of  words  with 
things  in  that  they  rest  upon  the  assump- 
tion that  agreeable  names  for  disagreeable 
things  better  the  things. 

Undoubtedly  there  is  truth  in  the  seman- 
ticists' indictment.  To  most  of  us  a  rose 
by  another  name  does  not  smell  so  sweet. 
The  Nazis  in  the  Second  World  War  made 
heavy  use  of  the  converse  principle— that 
a  stinkweed  by  another  name  does  not  smell 
so  bad— when  they  called  their  retreats 
"planned  withdrawals,"  "defensive  suc- 
cesses," "successful  disengagements"  and 
"unencircling  maneuvers."  The  semanti- 
cists' means  for  avoiding  this  'primitive 
and  infantile'  use  of  words  seems  to  be  to 
get  rid  of  all  our  euphemisms  and  other 
similar  graceful  distortions  of  language.     It 


is  doubtful,,  however,  if  people  could  be 
taught  to  face  reality  and  truth  simply  by 
forbidding  them  all  the  ameliorating  charm 
of  figures  of  speech  and  pinning  them  down 
to  harsh  unimaginative  description.  If 
man  were  denied  language  as  a  medium  for 
his  repressions,  suppressions  and  wishful 
distortions,  he  would  find  another  way  to 
be  himself  and  to  escape  the  unpleasant. 
Mankind,  which  made  words  for  its  pur- 
poses, is  not  likely  to  truckle  to  semanti- 
cists wishing  to  change  human  nature. 

THE    INDIVIDUAL    IN    RELATION 
TO    THE    ASSEMBLED    GROUP 

Persons  have  relations  with— affect  and 
are  affected  hy— assembled  groups  and  dis- 
persed groups.  An  assembled  group  is  all 
together  physically,  like  a  congregation  in 
a  church,  or  an  audience  in  an  auditorium; 
but  it  is  not  the  'audience'  for  whom  a  book 
is  written,  which  is  a  dispersed  group.  A 
town  meeting  is  an  assembled  group.  A 
political  party  is  a  dispersed  group,  for 
most  of  its  members  never  see  one  another. 
As  the  means  of  communication  (air  travel, 
radio,  movies,  etc.)  get  better  and  the  world 
'gets  smaller,'  as  the  phrase  is,  dispersed 
groups  can  be  more  closely  integrated  and 
so  become  more  important  than  assembled 
groups.  A  dispersed  group  may  consist 
of  millions  of  persons,  an  assembled  group 
is  limited  to  a  few  thousands.  In  this  sec- 
tion we  are  considering  the  individual  in 
the  assembled  group. 

Social  Facilitation  and 
Social  Inhibition 

Improvement  of  any  aspect  of  a  person's 
performance  by  virtue  of  the  sight  and 
sound  of  other  persons  simultaneously  en- 
gaged in  similar  activities  has  been  termed 
social  facilitation  (p.   124).     When  impair- 


The  Assembled  Group 


597 


incfil  results,  sonal  uihibilion  is  said  lo 
have  occurred.  In  everyday  lile  social 
tacilitation  is  illustrated  in  such  obvious 
occurrences  as  people's  eating  more  and 
drinking  more  in  company  than  when 
alone.  Experiments  show  the  same  rela- 
tionship; workers  turn  out  more  work  in  a 
room  with  others  busy  at  the  same  kind 
of  task  than  they  do  working  in  isolation. 

Social  inhibition  has  been  demonstrated 
in  the  same  experiments  which  revealed 
social  facilitation.  For  while  the  speed 
and  amount  of  performance  increases  in 
a  co-acting  group,  the  quality  of  perform- 
ance often  goes  down.  These  opposing 
trends  are  not  illogical  if  it  is  remembered 
that  the  effect  of  a  co-acting  group  upon  the 
individual  derives,  in  theory,  from  an  in- 
crease in  motivation.  Gross  motor  re- 
sponses profit  from  the  whip,  but  accurate 
discrimination  and  thought  are  disrupted. 
It  is  for  this  reason  that  in  tasks  calling 
for  thought  the  solitary  performance  of  an 
individual  is  often  better  than  his  per- 
formance in  a  group. 

Social  inhibition  may  occur  even  in 
activities  where  facilitation  is  the  rule  if 
the  individual  happens  to  be  particularly 
susceptible  to  emotional  excitement  or  the 
competition  is  particularly  intense.  In  one 
experiment  fourteen  out  of  fifteen  normal 
subjects  wrote  more  in  the  presence  of  co- 
workers than  alone.  But  in  another  experi- 
ment eight  out  of  ten  stammerers— stam- 
mering is  known  to  be  caused  in  part  by 
emotionality  in  social  situations— produced 
more  written  material  in  isolation. 

Crowds  and  Mobs 

The  most  striking  instances  of  the  influ- 
ences of  assembled  groups  upon  the  indi- 
vidual are  to  be  observed  in  crowd  and 
mob  behavior.  Indeed,  so  different  is  the 
action  of  j^ersons  in  mobs  from  their  ordi- 


nary behavior  that  some  early  writers  Icll 
impelled  to  invoke  a  'group  mind'  which 
presumably  took  over  in  an  active  crowd 
to  bend  the  individual  lo  its  wishes.  Such 
a  notion  is  (juite  unacceptable  as  an  ex- 
planation since  minds  pertain  to  indi- 
\icluals.     It  is  also  quite  unnecessary. 

A  crowd  may  be  said  to  come  into  being 
whenever  an  assembled  group  of  people  is 
attracted  to  a  common  focus  of  attention 
and  shares  similar  emotions.  They  may 
be  a  group  of  curious  and  fearful  spectators 
of  a  fire,  or  sympathetic  onlookers  at  an 
accident  or  excited  fans  at  a  sports  con- 
test. If  the  common  emotion  is  intense, 
especially  if  it  is  anger,  and  if  concerted 
action  eventuates,  the  crowd  has  turned  into 
a  mob. 

We  may  now^  turn  our  attention  to  a 
consideration  of  some  of  the  factors  which 
seem  to  be  instrumental  in  the  develop- 
ment of  mob  action,  drawing  illustrations, 
when  they  are  needed,  from  the  formation 
of  a  lynching  mob  in  the  South. 

(1)  Background  factors.  Mob  outbreaks 
are  most  likely  to  occur  in  areas  where  there 
exist  long-standing  frustrations,  which  cre- 
ate general  susceptibility  to  mob  action  in 
pent-up  hostility  and  specific  susceptibility 
in  antagonisms  toward  particular  gioups. 
Laying  the  background  for  lynching  mobs, 
the  depressed  socio-economic  conditions  of 
the  South  have  produced  many  potential 
white  mob  members,  all  with  the  general- 
ized hostility  of  frustrated  men  and  com- 
mon antagonisms  toward  employers  and 
possible  Negro  competitors. 

(2)  Precipitating  factors.  In  such  a  situ- 
ation some  incident  occurs.  Let  us  say  a 
Negro  is  presumed  to  have  attacked  a  white 
woman.  This  incident  generates  a  crowd 
by  focalizing  attention  and  initiating  com- 
mon emotions.  People,  stirred  by  the  ru 
mor,  gather  where  talk  of  the  matter  is  go- 


598 


Social  Relations  of  the  Individual 


ing  on.  Immediately,  there  is  intensifica- 
tion of  emotion,  Avhich  is  the  most  signifi- 
cant factor  in  changing  a  crowd  into  a 
mob.  Crowd  excitement  increases  in  the 
milling  or  muttering  stage,  primarily 
through  the  process  of  social  facilitation. 
The  sights  and  sounds  of  others  expressing 
similar  emotions  serve  to  heighten  the  feel- 
ings and  demonstrativeness  of  the  individ- 
ual. His  increased  expressiveness  intensi- 
fies the  feelings  of  others.  Thus  there  is  a 
circular  working  up  of  anger  from  indig- 
nation to  fury. 

Strong  emotion,  as  we  have  seen,  inhibits 
critical  thought  and  makes  the  individual 
highly  suggestible.  This  suggestibility  un- 
derlies the  next  stage  of  mob  de\-elopment, 
which  is  directed  action.  The  infuriated 
group,  probably  with  the  most  suggestible 
acting  first,  plunges  into  concerted  action, 
if  the  course  is  obvious,  or  if  a  leader  arises 
to  voice  the  sentiment  of  the  crowd  by 
shouting  "Break  into  the  jail!"  or  "Get  a 
rail  and  batter  in  the  door!" 

(3)  Reinjorcing  factors.  Primarily  be- 
cause it  short-circuits  critical  thought,  mob 
action  usually  produces  psychological  ef- 
fects which  reinforce  the  participants.  Sup- 
pose you  get  caught,  psychologically  as  well 
as  physically,  in  a  mob.  \Vhat  happens 
to  you?  First,  you  feel  a  sense  of  univer- 
sality. Coursing  along  with  the  group, 
you  are  elated  because  you  'know'  that 
everyone  is  with  you  in  what  you  are  doing. 
Second,  you  have  the  sense  of  righteous- 
ness. High-sounding  rationalizations  you 
hear  and  repeat  with  satisfaction.  "South- 
ern womanhood  must  be  protected."  "The 
Negro  must  learn  to  keep  his  place."  ^Vith 
so  many  people  sure,  how  could  you  be 
wrong?  Third,  you  have  a  sense  of  power 
or  righteous  might.  You  know  what  to  do, 
why  you  should  do  it,  how^  it  should  be 
done  and  that  you  can  do  it.     There   is 


nothing  left  lo  stop  you.  Yet,  if  more  re- 
inforcement were  needed,  there  is  in  addi- 
tion your  se7ise  of  anonymity  and  yoiu" 
consequent  invidnerability  to  reprisals. 
"How  could  so  many  be  punished?"  you 
might  ask  yourself,  thus  becoming  confi- 
dent of  immiuiity. 

There  is  no  need  to  invoke  a  mysterious 
group  mind  to  understand  why  people  will 
commit  acts  of  violence  in  a  mob  which 
they  would  not  dream  of  doing  singly.  The 
violence,  the  suggestibility  and  the  inflexi- 
bility of  mobs  all  derive  from  the  extraor- 
dinary intensity  of  emotion  which  ener- 
gizes action  and  inhibits  both  reason  and 
conscience. 

THE    INDIVIDUAL    IN    RELATION 
TO    THE    DISPERSED    GROUP 

We  come  now  to  the  indi\'iduars  rela- 
tion to  the  dispersed  gioup— the  questions 
of  how  and  why  he  identifies  himself  with 
so  invisible  a  being  and  just  what  he  thinks 
this  invisible  gioup  is  like.  A  dispersed 
group  may  not  seem  the  same  to  two  men 
both  of  whom  are  loyal  to  it  or  antagonistic 
to  it. 

Group  Attachment 

The  cement  which  binds  spatialh  sepa- 
rate individuals  into  group  membership 
flows  from  motivational  and  emotional  con- 
ditions. Appreciation  of  common  interests 
yields  an  intellectual  sense  of  membership. 
Then  the  emotional  process  of  identifica- 
tion can  supervene  to  develop  feelings  of 
solidarity  and  loyalty.  Particularly  when 
the  group  members  occasionally  come  to- 
gether physically  and  there  is  some  degree 
of  formal  organization,  interested  persons 
tend  to  identify  themsehes  with  the  group 
leaders,  the  group  symbols  and  the  group 
values.     Thus   they   become   loyal  Ameri- 


The  Dispersed  Group 


599 


cans,  Democrats,  Rotarians  or  I'lcsl^yUi iaiis. 
Assembly  of  a  part  ot  a  dispersed  gnnijj 
is  not  essential  for  group  identification,  but 
it  is  an  aid.  A  Presbyterian  in  Tibet  may 
be  less  faithful  than  in  Scotland.  The 
faith  of  a  Rotarian  may  weaken  in  Ant- 
arctica. Yet  any  of  these  persons  can  main- 
tain a  sense  of  group  membership  with- 
out a  congregation.  The  Roman  in  con- 
quered provinces  never  lost  his  sense  of 
identity  with  Rome,  nor  did  the  British 
public  servant  of  the  Victorian  empire  ever 
forget  he  was  British.  He— the  story  has  it- 
dressed  for  dinner  in  the  remote  provinces 
of  India  or  in  the  wastes  of  the  Sudan. 

Perhaps  the  most  significant  expression 
of  group  identification  today  is  nationaUsin 
—the  identification  of  the  individual  with 
the  national  group  or  state.  This  kind  of 
identification  has  the  advantage  of  allow- 
ing the  individual  to  share  the  prestige 
and  power  of  the  largest  group  of  which 
he  can  claim  to  be  a  member.  Especially 
do  frustrated  persons  need  the  vicarious 
sense  of  greatness  and  achievement  that 
can  come  from  nationalistic  identification. 
It  has  been  remarked  that  the  fiercest  na- 
tionalism is  found  in  the  countries  where 
the  peoples'  lives  have  been  most  hopeless 
and  thwarted. 

Nationalistic  identification  is  also  grati- 
fying because  it  provides  an  opportunity 
for  venting  frustration-born  hostility  on 
the  outgToups.  The  ingruup  is  the  group 
with  which  you  identify  yourself.  The 
other  groups  outside  the  boundaries  or  bar- 
riers of  the  ingroups  are  outgroups.  The 
structuring  of  society  into  groups  creates 
this  social  cleavage.  The  more  closely  its 
members  identify  themselves  with  their 
ingroup,  the  more  they  separate  themselves 
from  the  outgroups  which  the  formation 
of  the  ingroup  has  created.  That  is  why 
an  intense  nationalism  can  be  fierce.     It 


(b'recls  lialicd  at  those  who  are  not  of  )our 
kind,  those  who  are  not  identified  with 
your  group.  Hatred  is  satisfying,  and  fruv 
trated  people  need  it.  The  prerequisite 
for  forming  "one  world"  is  not  the  aboli- 
tion of  hatred  but  its  redirection  against 
the  true  enemies  of  all  mankind— want, 
fear,  ignorance  and  disease. 

Group  Conception 

The  individual's  conception  of  a  div 
persed  groiq)  may  be  fairly  well  specified 
and  it  is  generally  much  simpler  than  the 
reality  which  it  represents.  The  individual 
never  sees  his  total  ingroup,  and  his  out- 
groups may  be  so  remote  from  him  that  he 
has  no  direct  acquaintance  with  their  mem- 
bers. Here  is  the  situation  in  which  ignrj- 
rance  and  ego  involvement  favor  the  for- 
mation of  rigid  stereotypes,  especially  con- 
cerning outgroups.  So  it  is  that  the  white 
American  picks  up  oversimplified,  undis- 
criminating  conceptions  like  "the  shiftless 
Negro,"  "the  sly  Oriental,"  "the  terrible 
Turk,"  and  lets  them  serve  him  as  outgioup 
representatives. 

Ingroup  stereotypes  are  more  fa\oraijle 
to  the  insiders.  No  man  identifies  himself 
with  what  he  disparages  nor  disparages 
what  he  has  identified  himself  with.  The 
Nazis  accepted  for  themselves  the  Aryan 
stereotype  of  the  blond  \'iking,  thus  af- 
fording an  opportunity  to  those  in  their 
outgroups  to  retaliate  by  phrasing  the  lam- 
poon, "as  blond  as  Hitler,  as  tall  as  Goel> 
bels  and  as  slim  as  Goering." 

LEADERSHIP 

Leadership  can  arise  in  an  individual's 
relation  to  eitlier  an  assembled  group  or  a 
dispersed  group,  but  the  requirements  aie 
different  in  the  two  cases.  The  leader  of 
an  infantry  squad,  as  well  as  the  chainnan 


600 


Social  Relations  of  ihe  Individual 


of  a  board  of  directors,  are  in  a  face-to- 
face  relation  with  their  groups.  They  can 
use  simple  emotional  appeals,  discussion 
and  argument,  peremptory  demand  or  any 
of  the  subtler  devices  whereby  the  egos  of 
the  group  members  are  moved  toward  iden- 
tification with  the  leader.  The  president 
of  a  great  institution,  on  the  other  hand, 
has  a  dispersed  group  to  lead.  He,  too, 
through  tactful  propaganda,  may  appeal 
to  the  emotions  of  his  group,  but  in  general 
his  procedure  is  more  intellectualized.  He 
attempts  to  get  his  group  members  to  iden- 
tify themselves  with  the  institution,  not 
with  him.  The  boss  of  a  political  machine 
is  intermediate  between  the  squad  leader 
and  the  president.  His  group  is  some- 
^v'hat  dispersed,  but  he  deals  face-to-face 
with  many  individuals  and  trusts  them 
to  spread  the  word  about  him  to  the  others. 

Leadership  is  a  relation  of  an  individual 
to  a  group,  established  in  the  interests  of 
achieving  some  end.  There  are  so  many 
kinds  of  groups,  and  of  ends,  and  of  ways 
of  achieving  the  same  end  and  of  securing 
the  loyalty  of  the  same  group  that  the  prob- 
lem has  turned  out  to  be  a  sheaf  of  prob- 
lems. 

This  much,  however,  can  we  say.  The 
physical  and  personality  characteristics  of 
leaders  may  vary  gieatly  from  successful 
leader  to  successful  leader,  yet  their  suc- 
cesses seem  to  hinge  upon  two  necessar)' 
conditions. 

The  first  is  that  they  possess  membership 
character  in  the  group  they  are  undertak- 
ing to  lead,  that  is  to  say,  they  must  share 
the  values,  attitudes  and  interests  of  the 
group.  This  psychological  similarity  is 
necessary  for  the  identification  of  the  fol- 
lowers with  the  leader.  Politicians  know 
this  fact  well.  \Vhen  they  run  a  candidate 
for  office  in  a  particular  district,  they  make 
every  effort  to  get  a  man  with  whom  the 


district  can  readily  identify  itself.  It  is 
no  accident  that  the  late  Governor  Tal- 
madge  of  Georgia  appeared  in  red  'galluses' 
and  shirtsleeves  when  he  addressed  his 
backwoods  constituents.  And  no  small  part 
of  Hitler's  success  as  a  leader  was  due  to  his 
reflection  of  the  aspirations  and  experiences 
of  so  many  of  his  countrymen. 

The  second  condition  of  leadership  is 
that  the  leader  should  be  somewhat  supe- 
rior to  the  members  of  the  group  in  the 
qualities  esteemed  by  them.  People  are 
not  satisfied  to  identify  themselves  with 
someone  who  is  not  greater  than  they.  On 
the  other  liand,  the  stiperiority  must  be 
temperate  and  not  so  great  or  obvious  that 
it  destroys  the  leader's  membership  char- 
acter in  the  group. 

RELATIONS     BETWEEN     GROUPS 

With  the  modern  de\elopment  of  so- 
ciety it  has  become  increasingly  true  that 
to  be  effective  the  individual  must  often 
act  as  a  member  of  a  group.  Many  of  the 
most  significant  social  interactions  of  to- 
day operate  in  and  through  group  rela- 
tions—national groups,  political  groups,  so- 
cial groups,  racial  or  ethnic  groups,  etc. 
Two  of  the  important  groupings,  which 
have  been  subjected  to  recent  analysis  are 
socio-economic  interest  groups  and  social 
participation  groups. 

Socio-economic  Interest  Groups 

\Vhen  a  national  sample  of  the  popula- 
tion was  polled  as  to  whether  they  belonged 
to  the  upper,  lower,  middle  or  working 
class,  only  one  per  cent  answered,  "I  don't 
believe  in  classes,"  and  only  one  per  cent 
said,  "I  don't  know."  So  the  existence  of 
'class  consciousness'  among  the  American 
people  cannot  be  denied.  The  chief  divi- 
sion lay  between   the   working  class  with 


Relations  between  Groups 


601 


fifty-one  per  cent  of  tlic  sample  polled 
and  the  middle  class  with  foriy-iliree  per 
cent.  That  these  two  classes  exist  as  more 
than  mere  labels  is  shown  by  the  occupa- 
tions, and  also  attitudes  and  interests,  of 
the  respondents.  In  Fig.  246  it  may  be 
abserved  that  members  of  the  middle  class 


who  pill  tliemselves  in  ilie  middle  class. 
This  result  is  giaplied  in  1-ig.  247  for  a  bat- 
tery of  six  issues  presented  to  a  national 
sample. 

The  existence  of  class  opposition  in 
socio-economic  interests  makes  plain  the 
necessity   of   adjusting   and    compiomising 


Large  business 

Professional 

Small  business 

White  collar 

Skilled  manual 

Semi  skilled  manual 

Unskilled  manual 


25 


50 
Per  cent 


75 


100 


if^^  Upper  class  HIQIl  Middle  class  [Xvi^  Working  class  |      |  Lower  class 

H  Don't  know  illiil  Don't  believe  in  classes 

FIGURE    246.       CLASS    IDENTIFICATIONS    OF    OCCUPATIONAL    STRATA 

For  simplicity  rural  groups  have  been  eliminated  from  the  above  results.  Otherwise  they  are  based 
upon  a  national  sample.  [Adapted  from  R.  T.  Centers,  Psychological  aspects  of  socio-economic  stratifi- 
cation: an  inquiry  into  the  nature  of  class,  Princeton   University  Press,   1948;   by  permission.] 


come  predominantly  from  business,  profes- 
sional and  other  white  collar  occupations, 
whereas  members  of  the  working  class  come 
froin  skilled  and  unskilled  manual  occu- 
pations. 

Consistent  with  their  differences  in  occu- 
pation, the  iniddle  class  and  working  class 
divide  in  their  attitudes.  If  opinions  upon 
social,  political  and  economic  issues  are 
classified  as  radical  when  desire  for  change 
is  expressed,  and  consewative  when  adher- 
ence to  the  status  quo  is  preferred,  those 
who  put  themselves  in  the  working  class 
are,  on  the  average,  more  radical  than  those 


such  differences  before  the  classes  pull 
widely  apart.  If  the  opposition  increases, 
violent  class  struggle  and  revolutionary  up- 
heavals may  be  the  result. 

Social  Participation  Groups 

A  social  participation  group,  in  the  sense 
of  the  present  paragraph,  is  a  class  of  peo- 
ple who  associate  together  even  to  die  ex- 
tent of  intermaiTiage  and  regard  diem- 
selves,  and  are  regarded  by  others,  as  simi- 
lar in  social  status.  Investigation  has 
sho^vn  diat  there  are  three  such  main 
groups:    the   upper  doss,   the   middle  class 


602 


Social  Relations  of  the  Individual 


and  the  lower  class.  It  is  useful  to  sub- 
divide each  of  tliese  classes,  as  for  example 
upper  and  lower  middle  class,  to  form  a 
total  of  six  groups.  Some  social  mobility 
is  possible  among  these  classes,  for  indi- 
viduals can,  by  their  actions  and  achieve- 
ments, raise  or  lower  their  class  status. 

In   the  study  of  participation  classes  in 
the  South,  the  additional  concejjt  of  caste 


days  of  slavery  has  gradually  pushed  the  tojj 
Negro  class  above  the  lowest  white  class  in 
wealth  and  the  other  desiderata  of  class 
status.  The  upper  Negro  class  in  the  South 
is  now  in  the  anomalous  and  conflict-ridden 
position  of  being  superior  to  many  whites 
in  class,  but  inferior  in  caste.  When  such 
Negroes  engage  in  a  social  interaction  with 
a  low-class  white,   they  can  never  be  cer- 


^ 


L_ 

80 


Middle  class 


^ 


Working  class 


m Ill iiiiijsisii^i^ 


60 


40 


20 


0 
Per  cent 


20 


40 


60 


80 


Ultraconservative 


[]  Conservative        ]M^  Indeterminate       ^sj  Radical       |      |  Ultraradical 

CiLASS    DIFFERENCES    IN     CONSERVATISM-RADICALISM 


These  results  are  based  upon  llie  responses  of  a  national  sample  to  six  socio-economic  issues.  [Ailaplecl 
from  R.  T.  Centers,  Psychological  aspects  of  socio-economic  siralificalion:  an  iuqiiin'  into  Ihc  nature  of 
class,  Princeton  University  Press,  1948;  by  permission.] 


has  arisen.  The  Negro  is  of  lower  caste 
than  the  white  in  the  sense  that  he  cannot 
marry  into  the  white  group. 

A  revealing  chart  of  the  relationship  be- 
tween caste  and  class  in  the  South  is  repro- 
duced in  Fig.  248.  The  caste  line  separates 
the  white  and  Negro  groups;  the  dotted 
lines  show  the  three  general  classes  in  each 
caste.  The  double-headed  arrows  repre- 
sent the  mobility  which  is  socially  accept- 
able between  classes,  but  not  between 
castes. 

The  most  interesting  feature  of  the  dia- 
gram lies  in  the  tilt  of  the  caste  line.  At 
an  earlier  period  this  division  was  hori- 
zontal—the white  man's  floor  was  the 
Negro's  ceiling.  But  the  development  of 
class  strata   in   thr   Negio  group  since   the 


tain  whether  they  will  receive  deferential 
treatment  based  upon  class  lines  or  arro- 
gant treatment  based  on  caste.  The  hypoth- 
esis has  been  advanced  that  the  dispropor- 
tionate amount  of  emotional  instability  in 
the  upper-class  Negro  group  is  due  to  this 
objective  instability  in  the  social  situation 
in  which  they  live. 

The  conception  of  two  parallel  civiliza- 
tions as  the  solution  of  the  Negro  problem 
envisions  a  time  when  the  caste  line  shall 
have  rotated  to  the  vertical  position  d-e. 
The  "two  civilizations"  would  then  be 
"separate  but  equal." 

We  turn  next  to  the  basic  problem  of 
relations  between  groups,  the  problem  of 
social  conflict  which  is  rooted  in  social 
prejudice. 


Social  Prejudice 


603 


Lower  class 


FIGURE    2^8.       THK    REIAIION    BKTVVEEN    CASTE   AND 
CLASS    IN    THE    DEEP    SOUTH 

Relative  class  levels  shown  for  each  caste.  The 
arrows  represent  the  range  ol  socially  acceptable 
mobility  between  classes  in  each  caste.  Area 
roughly  indicates  nimibers  of  persons.  The  caste 
line,  once  horizontal,  is  now  tilted.  If  the  castes 
were  to  form  two  parallel  civilizations,  the  caste 
line  would  become  vertical  at  d-e.  This  diagram 
does  not  portray  quantitative  relations,  [.'\dapted 
from  W.  L.  Warner,  in  A.  Davis,  B.  B.  Gardner  and 
M.  R.  Gardner,  Deep  South,  a  social  anthropolog- 
ical sliuly  of  caste  and  class,  Chicago  University 
Press,  1941.] 

SOCIAL    PREJUDICE 

With  some  understanding  o£  the  social 
relations  between  individuals  and  groups 
we  can  now  push  ahead  into  the  difficult 
area  of  social  conflict.  Disputes  today  in- 
volve a  much  larger  area  and  a  greater 
population  than  formerly.  Once  they  were 
nearly  individual  and  settled  with  clubs 
or  spears.  Now  that  the  individuals  are 
identified  with  groups,  the  groups  fight 
with  total  war  and  atomic  techniques.  The 
ultimate  cost  to  civilization  is  incalculable. 
Some  wise  men  and  women  think  that  the 
continuity  of  civilization  itself  is  threatened 
by  its  own  achievements.  Fortunately  this 
book  does  not  have  to  provide  an  answer 
to  that  question. 

Nevertheless  it  behooves  not  only  the 
psychologist,  but  also  all  men  who  would 
be  wise,  to  gain  understanding  of  the  na- 
ture of  social   conflict   and   of   the   never- 


ending  war  between  the  ingroup  and  the 
outgroup,  for  that  is  the  pattern  of  every 
war.  Why  do  men  fight?  Why  do  they 
contend?  They  contend  with  each  other 
in  order  to  defend  and  enlarge  their  egos. 
They  fight  because  that  is  nature's  rude 
technique  for  remedying  frustration.  Pre- 
sumably they  may  stop  fighting  when  edu- 
cation and  emotional  maturity  of  the  two 
or  three  billion  people  who  will  probably 
then  be  occupying  the  five  continents  is 
sufficient  to  make  it  clear  to  all  that  mutual 
destruction  does  not  pay  in  the  long  run. 
We  advance  in  that  direction  when  we  seek 
to  understand  the  nature  jf  conflict. 

Conflict  is  fundamentally  psychological. 
Its  tools  are  physical,  but  its  origin  and 
sustaining  force  lie  in  human  hostility,  in 
the  opposition  between  ingroup  and  out- 
group. The  power  to  change  such  discoid 
to  concord  among  groups  lies  largely  in 
whatever  understanding  and  control  can 
be  won  over  the  working  of  prejudice,  lot 
it  is  from  the  fires  of  prejudice  that  most 
human  conflicts  derive.  It  will  serve  us 
well,  therefore,  to  scrutinize  exhaustively 
prejudice  as  a  primaiy  threat  to  peace. 

Nature  of  Prejudice 

Fundamentally  prejudices  have  their 
basis  in  preferences,  the  simple  judgments 
of  pleasantness  and  unpleasantness  that 
everyone  makes  so  easily.  Such  judgments 
are  not  rational.  They  depend  upon  the 
basic  needs  of  the  organism  and  upon 
learned  needs.  A  person  does  not  know 
why  he  dislikes  yellow  and  prefers  red,  yet 
he  may  find  that  he  cannot  change  his 
likes  by  any  simple  act  of  'will'  and  that 
his  preferences  remain  constant  until  he 
has  some  very  unpleasant  experience  with 
red  or  some  very  great  pleasure  from  yel- 
low. Then,  by  conditioning,  his  prefer- 
ences may  be  altered. 


604 


Social  Relations  of  the  Individual 


Literally  prejudice  means  prejudgment. 
All  individual  action  and  choice  is  pre- 
judged. It  is  prejudged  in  the  constitu- 
tion of  the  genes,  insofar  as  heredity  con- 
tributes to  choice.  It  is  prejudged  in  past 
experience  insofar  as  conditioning  affects 
preference.  Prejudice  is  need  and  set,  and 
basically  it  is  irrational.  Only  a  small  part 
of  human  behavior  has  rational  processes 
as  its  immediate  antecedents,  and  these 
antecedents  themselves  have  antecedents, 
being  at  the  end  of  a  chain  of  events  that 
begins  with  the  needs.  In  this  sense  all 
human  action  is  prejudiced  by  what  the 
organism  is— by  what  every  human  organ- 
ism is  and  also  by  what  each  particular 
organism  has  become. 

There  is,  however,  a  practical  problem 
of  prejudice,  which  leads  to  a  limiting  defi- 
nition of  the  word.  Some  of  your  learned 
needs  and  sets,  some  of  your  habits  of 
thought  and  action  are  good,  forming  part 
of  the  behavior  repertoire  of  the  well- 
adjusted  man  and  the  good  citizen.  But 
you  may  have  other  sets  and  habits  which 
need  altering  for  your  own  good.  They 
are  'irrational'  in  the  sense  that  adhering 
to  them  works  to  your  own  disadvantage  in 
the  long  run.  Perhaps  indulging  them  at 
the  moment  is  pleasant,  but  in  the  long 
run  they  may  make  you  lose  friends  and 
gain  enemies  or  create  trouble  for  you  in 
some  other  way.  You  'ought'  to  change 
them,  that  is  to  say,  it  would  be  best  for 
you  if  you  did  change  them.  We  shall 
not  go  far  wrong  if  we  limit  the  use  of  the 
word  prejudice  to  those  sets  and  preferences 
which  'ought'  to  be  changed,  which,  if 
changed,  would  be  of  advantage  to  the  in- 
dividual or  his  ingroup  or  presumably 
both. 

The  assumption  of  the  remainder  of 
this  chapter  is  that  the  extreme  dislike  of 
outgToups  is  a  mark  of  immaturity  in  the 


ingroup  and  not  to  the  advantage  of  the 
ingroup's  members.  It  seems  quite  clear 
that  tolerant  understanding  is  the  best  mu- 
tual relation  between  groups,  that  social 
conflict,  because  it  arouses  emotion,  tends 
to  shut  off  the  wise  insight  which  might 
lead  to  the  solution  of  the  problem  that 
caused  the  conflict.  Nor  shall  we  go  far 
wrong  if  we  lay  down  the  rule  that,  when- 
ever we  hear  that  what  the  outgroup  wants 
is  bad  and  what  the  ingroup  wants  is  good, 
we  are  facing  an  instance  of  prejudice,  a  set 
which  could  with  advantage  be  changed. 

Origin  of  Prejudice 

In  the  early  days  of  social  psychology, 
when  it  was  customary  to  invent  'instincts' 
to  explain  social  behavior,  many  psycholo- 
gists believed  that  prejudices  were  instinc- 
tive. They  thought  of  race  prejudice  as  a 
consequence  of  innate  "consciousness  of 
kind"  associated  with  an  instinctive  "dis- 
like of  the  unlike."  Only  a  few  of  the 
considerations  need  be  cited  to  show  why 
this  historically  important  but  short-sighted 
theory  could  not  persist. 

(1)  There  is  no  evidence  of  race  preju- 
dice in  very  young  children.  On  the  con- 
trary, as  a  classic  study  in  a  Tennessee 
community  revealed,  white  and  Negro  chil- 
dren play  together  until  forbidden  to  do 
so,  and  some  continue  to  do  so  even  after 
repeated  punishment.  A  recent  investi- 
gation found  that  not  until  the  school  years 
do  prejudices  begin  to  develop  in  any  num- 
ber. The  average  of  remembered  onset 
for  cases  of  Negro  prejudice  in  whites  was 

12.6  years,  of  Jewish  prejudice  in  gentiles, 

13.7  years. 

(2)  The  visibility  of  differences  between 
groups  seems  to  be  more  an  effect  of  preju- 
dice than  a  cause.  Anti-Semitism  occurs 
even  where,  in  large  numbers  of  cases, 
Jews   cannot   be   distinguished   from   non- 


Origin  of  Prejudice 


605 


Jews.  In  such  instances  prejudice  has  had 
to  create  visibility  through  such  means  as 
requiring-  the  Jews  lo  wear  distinctive  gar- 
ments or  yellow  badges. 

Even  where  natural  differences  do  exist 
between  two  groups,  preexisting  prejudice 
seems  necessary  to  insure  attention  to  them. 
Visibility  depends  upon  learning.  When 
racial  differences  mean  little,  they  go  unre- 
marked. There  is  a  story  of  six-year-old 
Tommy  who  asked  his  mother  if  he  might 
bring  his  friend  Sammy  home  to  lunch. 
His  mother,  knowing  that  Tommy  attended 
a  'mixed'  school,  asked  if  Sammy  were  white 
or  colored.  "I  don't  know,"  said  Tommy, 
"but  I'll  look  next  time  I  see  him  and  tell 
you." 

A  recent  experiment  supports  the  view 
that  visibility  depends  on  prejudice.  Sub- 
jects were  asked  to  judge  which  photo- 
graphs of  twenty  presented  were  Jewish 
and  which  non-Jewish.  It  was  found  that 
the  subjects  who  disliked  Jews  were  both 
more  'suspicious'  (judged  more  faces  to  be 
Jewish)  and  more  accurate  (better  able  to 
distinguish  Jewish  from  non- Jewish  faces). 
The  unprejudiced  were  less  sensitive  to  the 
ethnic  affiliation  of  those  whom  they 
judged.  That  is  natural.  In  perception 
you  see  what  you  use.  Perception  exists  be- 
cause it  is  useful  to  the  organism. 

(3)  If  anti-Negro  prejudice  were  univer- 
sal among  whites,  it  might  be  regarded  as 
associated  with  the  white  gene,  and  then  it 
surely  would  be  called  'instinctive.'  But 
the  prejudice  is  not  universal.  There  is 
little,  for  example,  in  Brazil. 

(4)  Dislike-of-the-unlike  cannot  be  an  'in- 
stinct.' Too  many  people  desire  new  ex- 
periences. In  some  groups  the  foreign  and 
the  bizarre  are  welcomed.  Strange  people 
and  things  are  liked  when  they  enlarge  the 
ego,  disliked  when  their  novelty  threatens 
security. 


(F))  I'inally,  we  may  note  that  two  pio- 
fessional  musicians  of  different  races  have 
more  'consciousness  of  kind'  than  you 
could  expect  to  find  between  either  of 
them  and,  say,  a  peddler  of  the  same  race. 

Since  prejudice  is  not  innate,  the  ques- 
tion arises  as  to  what  kind  of  experiences 
produce  prejudices.  Arc  the  key  experi- 
ences generally  direct  personal  contacts 
with  the  members  of  minority  groups? 
Certainly  they  may  be.  An  intensely  un- 
pleasant episode  with  a  Negro  can  leave  a 
lasting  antagonism  to  all  Negroes.  In  gen- 
eral, however,  the  conclusion  has  been 
that  the  attitudes  of  whites  toward  Negroes 
are  chiefly  determined  "not  by  contact  with 
Negi^oes,  but  by  contact  with  the  prevalent 
attitude  toward  Negroes." 

It  is  the  culture  that  provides  us  with 
these  many  ready-made  prejudices.  It  is 
true  that  some  of  them  have  sprung  from 
experiences,  but  most  of  them  are  deri\ed 
from  second-hand  experiences  which  ha\e 
been  passed  on  by  the  many  who  have  used 
them.  This  fact  has  been  brought  into 
focus  through  the  sttidies  of  what  is  called 
social  distance.  In  these  studies  persons 
were  asked  to  check  the  degree  of  intimacy 
with  which  they  would  be  willing  to  admit 
members  of  various  grotips  to  association 
with  themselves.  In  an  early  inquiry  it 
was  found  that  students  sho^ved  the  great- 
est prejudice  toward  the  Turks,  though 
most  of  them  had  never  even  seen  a  Turk. 
It  developed,  upon  analysis,  diat  the  preju- 
dices stemmed  from  the  second-hand  ac- 
ceptance of  traditions  and  current  opin- 
ions. 

The  results  of  a  study  of  racial  prefer- 
ences in  1939  are  sho^^•n  in  Table  XXXIX. 
The  steps  in  the  scale  are  listed  at  the  top 
of  the  table.  The  general  pattern  of  liking 
Canadians  and  English  best  (after  Amer- 
icans)  and  preferring  Turks  and  Hindus 


606 


Social  Relations  of  the  Individual 


TABLE  XXXIX 

Average   Tolerance    of    Princeton   Students   toward   Ethnic  Groups   as   Measured   bv   a   Scale   of 

Social  Distance 

The  Japanese  are  lower  here  than  in  earlier  studies  of  social  distance.    The  drop  is  due  to  the  antagonism  that 
was  developing  toward  their  foreign  policy.    These  data  are  for  1939. 


The  scale  runs  as  follows: 

1.  Would  exclude  from  my  country. 

2.  As  vi.sitors  only  to  my  country. 

3.  To  citizenship  in  my  country. 

4.  'i"o  employment  in  any  occupation  in  any  country. 


5.  To  my  school  as  classmates. 

6.  To  my  street  as  neighbors. 

7.  To  my  club  as  personal  chums. 

8.  To  close  kinship  by  marriage. 


[.'\fter  E.  L.  Hartley,  Problems  in  prejudice.  Kings  Crown  Press,  1946.] 


Nationality 

Median 
tolerance 

Nationality 

Median 
tolerance 

American 

8.0 

Russian 

3.3 

Canadian 

8.0 

Latvian 

3.3 

English 

8.0 

Polish 

3.2 

Irish 

7.5 

Portuguese 

3.2 

Swedish 

7.3 

Negro 

3.1 

Swiss 

7.3 

Lithuanian 

3.0 

German 

6.8 

Greek 

2.9 

French 

6.6 

Filipino 

2.8 

Danish 

6.5 

Arab 

2.8 

Austrian 

6.4 

Wallonian 

2.8 

Finn 

5.9 

Mexican 

2.7 

Vrench  Canadian 

5.9 

Chinese 

2.7 

American  Indian 

5.3 

Turk 

2.7 

Argentine 

5.1 

Hindu 

2.6 

Czechoslovak 

4.5 

Danirean 

2.6 

Hungarian 

4.0 

Pirenean 

2.4 

Italian 

3.6 

Japanese 

2.3 

Rumanian 

3.5 

least  is  almost  an  American  (ustoni.  In 
1928  a  definitive  survey  of  the  country  re- 
\calecl  this  hierarchy,  which  has  been  veri- 
fied ever  since.  A  study  of  seven  colleges 
from  Florida  to  Washington  produced  co- 
efficients of  correlations  among  these  rank- 
ings varying  from  -1-0.84  to  -}-0.99.  School 
children  in  St.  Louis  gave  similar  results. 
Among  them  the  preferences  were  similar 
for  Jews,  Catholics  and  Protestants,  for 
rural  and  urban  children,  for  Negro  and 


white  children  and  for  children  of  differ- 
ent economic  levels. 

The  one  limitation  to  the  overall  con- 
stancy in  such  a  series  is  that  members  of 
minority  groups  who  rank  low  in  the  hier- 
archy accept  the  pattern  with  the  single 
modification  that  they  place  their  own 
group  at  the  top. 

Such  a  national  uniformity  of  ethnic 
preference,  covering  as  it  does  a  great  di- 
versity of  individuals,   makes   the   conclu- 


Motivations  for  Prejudice 


607 


sion  inescapable  that  jjcrsonal  experience 
plays  at  most  a  minor  role  in  initiating  rare 
prejudice.  Such  prejudices  (ome  as  part  of 
the  social  heritage  which  the  new  recruits 
to  society  absorb  from  early  childhood. 
Children,  eager  to  be  adults,  emulate  the 
prejudiced  attitudes  and  discriminatory  be- 
haviors of  their  parents.  Like  conscience, 
these  prejudices  follow  the  parent  pattern 
and  are  not  easily  (hanged. 

Now  what  about  the  Pireneans,  Dan- 
ireans  and  Wallonians  who  are  ranked  low 
in  Table  XXXIX,  along  with  the  Turks 
and  Hindus?  These  are  entirely  fictitious 
groups.  Most  of  the  subjects,  however, 
evaluated  them  with  the  other  groups,  put- 
ting them  at  the  bottom  of  their  prefer- 
ence rankings.  This  apparent  trick  is  in 
reality  a  significant  finding.  First,  it  shows 
that  racial  evaluations  are  prejudicial  and 
not  judicial,  except  insofar  as  complete  ig- 
norance about  a  man  is  a  reason  for  dis- 
liking him.  Second,  it  shows  how  uncriti- 
cal is  the  absorption  and  how  undiscrimi- 
nating  the  application  of  these  stereotyped 
racial  attitudes.  Third,  it  indicates  how 
prejudice  goes  hand  in  hand  with  igno- 
rance. There  is  a  large  measure  of  truth 
in  the  homely  dictum,  "Prejudice  is  being 
down  on  what  you  are  not  up  on."  On  the 
other  hand,  it  may  be  said  that  it  is  no 
great  achievement  on  the  part  of  the  cul- 
ture to  make  people  feel  a  distaste  for  what 
is  strange.  Safety  first  and  action  second 
is  the  ride  of  survival.  Conservatism  is  the 
first  way  of  playing  safe.  Cultivating  the 
novel  comes  under  the  rule  of  'nothing 
ventured,  nothing  won.'  If  perceptions 
were  not  stereotypes— for  that  is  what  the 
principle  of  object  constancy  means  (p.  231) 
—the  organism  would  fail.  The  point  here 
is  that,  although  the  fear  of  what  is  strange 
may  be  sound  basic  policy  for  the  organism. 


social  progress,  nevertheless,  lies  along  the 
path  of  liking  what  is  novel. 

One  further  point  needs  to  be  made. 
Iliough  the  reality  is  otherwise,  most  pef>- 
ple  believe  that  their  prejudices  fiow  from 
personal  experiences.  The  explanation  of 
this  widespread  discrepancy  between  belief 
and  reality  lies  principally  in  the  fact  that 
adults  do  not  remember  how  they  learned 
their  attitudes  from  their  parents  and  the 
further  fact  that  prejudice,  since  it  is  an 
ego  defense,  is  itself  preserved  fjy  a  largely 
unconscious  process  of  rationalization. 

Motivations  for  Prejudice 

A  prejudice  like  race  prejudice  is  likelv 
to  be  ever  so  much  more  strongly  held  than 
a  simple  like  or  dislike  as,  for  instance,  tlu- 
prejudice  for  tea  instead  of  coffee.  It  is 
plain  that  such  a  strong  prejudice  is  re- 
inforced. All  motives  work  because  they 
promise  gain  to  the  organism— now  or  in 
the  past  when  the  habit  was  formed.  E\en 
conscience  has  this  history.  What  then, 
we  may  ask,  are  the  more  important  kinds 
of  reinforcement  which  make  a  person  dis- 
like or  hate  the  members  of  outgroups  in 
these  cases  of  'race'  prejudice? 

There  are  three  large  advantages  which 
'race'  prejudices  seem  to  offer  to  some  of 
those  who  have  them.  They  are  (1)  eco- 
nomic gain,  (2)  gain  in  status  and  (3) 
outlet  for  hostility.  All  three  are  related, 
but  we  may  consider  them  in  order. 

(I)  Economic  gain.  It  is  a  commonplace 
that  ours  is  a  competitive  acquisitive  so- 
ciety where  often  one  man's  success  is  pred- 
icated upon  another  man's  failure.  Play- 
ing the  economic  game  bv  such  rules  puts 
a  premium,  of  course,  upon  anything  which 
gives  an  advantage  in  the  struggle.  And 
race  prejudice  definitely  offers  economic 
advantage  to  some  members  of  the  superior 


608 


Social  Relations  of  ihe  Individual 


group  and  may  seem  to  oHer  advantages  to 
all. 

The  economic  motive  for  the  disposses- 
sion of  Jews  in  Na/i  Germany  was  never 
far  beneath  the  smface.  Long  before  the 
Nazis  took  over  the  government  they  had 
promised  their  followers  the  jobs  held  by 
the  Jews.  By  widening  the  term  Jew  to 
apply  to  anyone  who  could  not  prove  pure 
'Aryan'  ancestry  as  far  back  as  January  1, 
1800,  they  greatly  increased  their  gains. 
Later,  as  the  necessity  for  subtlety  disap- 
peared, the  Nazis  began  to  expropriate  all 
Jewish  belongings. 

The  close  dependence  of  group  prejudice 
upon  economic  factors  is  also  well  illus- 
trated by  the  manner  in  which  group  an- 
tagonisms fluctuate  with  changes  in  eco- 
nomic conditions.  When  the  Chinese,  as 
one  study  revealed,  first  came  to  the  Pacific 
Coast,  there  was  great  need  for  their  labor. 
During  this  era  they  were  described  as  or- 
derly, industrious,  thrifty,  adaptable,  in- 
offensive and  law  abiding.  Then  came 
white  competition  for  the  jobs  which  the 
Chinese  had.  Soon  they  were  being  said  to 
be  clannish,  servile,  deceitful,  vicious  and 
generally  undesirable.  Prejudice  appeared 
when  there  was  work  for  it  to  do. 

The  same  kind  of  revealing  about-face 
occurred  during  the  Second  World  War  in 
connection  with  the  Japanese  evacuees  at 
Poston,  Arizona.  When  the  ranchers  of  a 
near-by  valley  found  that  they  needed 
evacuee  help  to  harvest  their  cotton,  there 
was  in  the  space  of  a  few  weeks  a  remark- 
able shift  of  opinion.  Whereas  previously 
all  evacuees  had  been  regarded  as  treacher- 
ous enemies,  now  they  were  hailed  as  hard- 
working and  cooperative  Americans  of 
Japanese  ancesti7.  And,  as  the  reporter 
dryly  remarked,  when  the  cotton  picking 
was  halted  l)y  military  order,  the  drift  back 


to   former   prejudices   was   equally   notice- 
able. 

(2)  Gniii  in  social  status.  Along  with  the 
economic  competition  in  American  society 
goes  a  struggle  for  social  status.  The  two 
are  related,  for  each  helps  the  other.  Still 
they  can  be  distinguished.  All  of  us  have  a 
desire  for  superiority  and  social  recogni- 
tion. All  of  us  are  pleased  to  look  down 
upon  those  who  seem  to  be  beneath  us  in 
social  status  or  who  act  as  if  they  were. 

For  persons  at  the  upper  levels  of  the 
socio-economic  hierarchy  there  are  many 
people  to  whom  they  can  feel  superior.  On 
the  other  hand,  those  at  the  bottom  are 
hard  put  to  gratify  their  desire  for  recogni- 
tion and  superiority.  Their  need  for  ego 
enhancement  is,  moreover,  whipped  up  by 
the  fact  that  there  are  so  many  others  to 
whom  they  must  defer.  For  the  poor  south- 
ern whites,  who  need  inferiors,  it  is  no 
trick  at  all  to  discover  that  the  Negro  ex- 
actly fits  the  role.  So  prejudice  is  rein- 
forced by  an  undeniable  gain  in  status. 

There  is  the  story  about  a  little  southern 
white  girl  who  was  found  weeping  bitterly 
over  the  news  that  the  Negroes  in  that  area 
were  all  departing  for  the  North.  Asked 
why  she  was  crying  over  the  Negroes'  de- 
parture, she  answered,  "When  all  of  them 
leave,  we  won't  have  nobody  to  be  better 
than." 

(3)  Outlet  for  hostility.  Frustration  be- 
gets aggression— not  always  but  usually  (p. 
513).  When  you  see  the  sequence  working 
it  is  almost  as  if  they  were  parts  of  the 
same  mechanism,  as  if  frustration  were  a 
need  and  aggression  were  its  satisfaction. 
At  any  rate,  aggressive  action  does  relieve 
frustration,  and  from  that  fact  spring  many 
social  phenomena.  There  are  two  furtlier 
facts  about  aggression  that  become  impor- 
tant here. 

In  the  first  place,  we  jnust  note  that  ag- 


Rationalizations  about  Prejudice 


609 


grcssion  may  be  latent.  Jlic  need  lor  il 
persists  when  it  has  no  opportunity  to  exer- 
cise itself.  The  frustration  may  come  and 
go,  but  the  need  for  aggression  persists  and 
is  reinforced  if  the  same  frustration  recurs 
soon  enough.  Any  man  whom  you  see  on 
the  street  has  in  him  a  great  deal  of  bot- 
tled-up  aggression  which  he  would  vent 
quickly  were  the  object  of  his  aggression  to 
appear  and  were  all  restraint  to  be  re- 
moved. 

The  other  fact  is  that  aggression  may  l)e 
displaced.  Your  needs  do  not  require  you 
to  work  olf  your  aggression  on  the  person 
or  persons  for  whom  it  was  intended.  You 
can  let  go  at  someone  else  and  very  often 
you  do  (see  Compensation,  p.  517). 

When  the  little  boy  who  cannot  go  out 
fishing  because  of  the  downpour  pulls  his 
sister's  liair  and  gives  his  hound  a  rough 
time,  he  is  storing  up  and  displacing  ag- 
gression. Tlie  worker  who,  tongue-laslied 
by  his  boss,  comes  liome  and  beats  his  wife 
is  illustrating  the  same  principle.  Elab- 
orate experimental  evidence  is  not  lacking. 

Displacement  is  a  failure  of  specification, 
a  case  of  generalization  in  learning.  Two 
rats  were  trained  in  aggression,  trained  to 
strike  at  each  other  on  receiving  a  mild 
shock.  A  doll  placed  in  the  enclosure  was 
ignored  as  long  as  two  rats  could  strike  each 
other;  but,  when  one  was  removed  and  the 
shock  administered,  the  other  rat  would 
strike  the  doll. 

It  is  through  displacement  that  scape- 
goating  comes  about.  Vulnerable  out- 
groups  are  scapegoated  for  the  thwarting 
difficulties  of  the  ingroup.  When  the  price 
of  cotton  falls  in  the  South,  the  number  of 
Negro  lynchings  goes  up.  The  process  is 
bereft  of  logic— the  Negro  could  hardly  be 
even  remotely  the  cause  of  the  price  of  cot- 
ton—but it  is  psychologic.    The  scapegoatcr 


is    seeking    tcmsion    icduftioM,    not    justice. 
Unfortunately  he  docs  not  know  it. 

Rationalizations  about  Prejudice 

Persons  are  rationalizing  when,  instead 
of  stating  the  actual  motives  for  their  atti- 
tudes or  actions,  they  offer  'good'  reasf;ns. 
Rationalization  is  a  reversal  of  the  logical 
process  of  generating  belief  from  evidence. 
Instead  the  belief  generates  evidence.  It  is 
a  process  not  of  verification,  but  of  justifi- 
cation. Ordinarily  peojjle  who  are  ration- 
alizing do  not  know  it  (pjj.  518  f.). 

Rationalizations  abound  in  the  area  of 
prejudice.  The  reason  is  not  difficult  to 
find.  The  more  rigid  prejudices,  we  have 
seen,  involve  the  absorption  of  social  tradi- 
tions. Unfavorable  stereotypes  are  uncriti- 
cally taken  over,  particularly  in  childhood 
when  critical  abilities  are  meager  and  de- 
pendence upon  parental  instruction  is 
great.  Parental  injunctions,  regardless  of 
supporting  evidence,  are  accepted  as  be- 
liefs. But,  as  children  grow  to  be  adults, 
developing  their  critical  abilities,  discom- 
fort arises.  We  have  learned  that  our  judg- 
ments should  follow  from  evidence  for  that 
is  the  method  of  reason  and  science,  and 
these  traditions  are  valued  highly  in  our 
culture.  This  difficulty  can,  however,  be 
resolved  through  rationalization.  People 
find  what  they  call  'good'  reasons  for  their 
antagonisms. 

Not  only  ideas  but  experiences  can  be 
found  to  fortify  preconcei\'ed  beliefs.  An\ 
anti-Semite  can  recount  the  time  that  he 
was  tricked  by  a  Jewish  merchant.  "What 
he  fails  to  remember  are  the  times  that  he 
was  treated  fairly  or  with  generosity.  He 
may  call  the  generosity  "unctuous  insin- 
cerity." If  you  project  die  prejudice  into 
the  issue,  you  ■will  not  see  it  in  yourself. 

That  preconceived  likes  and  dislikes  can 
q;o  far  in  influencina  obser\ations  has  been 


610 


Social  Relafions  of  the  Individual 


demonstrated  in  an  experiment.  The  ex- 
perimenter first  ascertained  in  a  classroom 
which  children  were  almost  vmiversally 
liked,  and  which  generally  disliked.  She 
then  had  subjects  from  each  of  these  two 
groups  perform  calisthenics  under  her  di- 
rection in  front  of  the  class.  She  had  pre- 
viously instructed  the  'liked'  children  to 
make  mistakes,  the  'disliked'  children  to 
follow  her  signals  precisely.  After  the  per- 
formance she  asked  the  class  to  indicate 
which  group  had  done  the  exercises  cor- 
rectly. The  striking  outcome  was  that  the 
majority  of  the  votes  went  to  the  popular 
group.  On  the  basis  of  subsequent  inter- 
views the  experimenter  decided  that  the 
children  actually  'saw'  the  residts  they  re- 
])orted,  were  letting  their  own  perceptions 
deceive  them,  in  the  way  that  perceptions, 
working  in  the  interests  of  their  owners,  al- 
ways do. 

Since  scientific  investigation  fails  in  gen- 
eral to  support  race  prejudice,  the  process 
of  distortion  has  gone  to  great  lengths  in 
this  area  in  erecting  defenses.  Let  us  ex- 
amine a  series  of  alleged  Negro-white  racial 
differences  to  see  how  facts  and  logic  can 
be  twisted  to  provide  the  'good'  reasons  for 
a  prejudice. 

(1)  Negroes  naturally  give  off  a  charac- 
teristically uj^pleasant  body  odor.  This  be- 
lief is  as  dubious  as  it  is  widespread.  Re- 
sults of  experiments  show  that  there  was 
neither  consistent  preference  for  samples  of 
perspiration  from  the  whites  nor  for  sam- 
ples from  Negroes. 

(2)  Negro  blood  is  different  from  the 
blood  of  whites.  Biologists  have  failed  to 
find  racial  differences  in  blood. 

(3)  Negro  legs  are  different  from  the  legs 
of  xuhites  so  that  the  whites  are  penalized 
in  athletic  competition.  The  legs  of  Negro 
athletes  are  longer  than  the  legs  of  the 
average  white  man,  but  so  are  the  legs  of 


white  athletes.  The  longer  heel  of  the 
Negro,  which  is  alleged  to  give  him  greater 
leverage  in  running  and  jumping,  is  the  re- 
sult of  nothing  more  than  a  thick  layer  of 
subcutaneous   fat. 

(4)  The  A^egro  is  more  apelike  than  the 
white.  Both  the  Negro  and  the  ape  have 
flat  noses,  but  the  lips  of  the  ape  are  like 
those  of  the  white  man.  In  general  body 
hairiness  and  in  the  size  of  the  brow  ridge, 
the  white  man  is  much  more  like  the  ajic 
than  the  black  man. 

(5)  Tlie  Negroes  are  naturally  inferior  in 
ijitelligence  to  xuJiites.  White  children 
have,  on  the  average,  done  better  upon  in- 
telligence tests  than  Negro  children,  but 
the  consensus  of  scientific  opinion  favors 
the  view  that  the  inferior  performance  of 
the  Negi'o  is  due  primarily  to  inferior  en- 
vironmental opportunities. 

There  is  a  certain  circularity  in  the  ef- 
fects of  prejudice.  Prejudice  can  feed  on 
what  it  creates.  Hostility  toward  Jews  has 
driven  them  into  ghettos  for  self-protection. 
Then  it  is  claimed  that  the  Jews  are  se- 
clusive  and  live  by  themselves,  and  preju- 
dice is  increased.  Hostility  toward  Negroes 
has  deprived  them  of  educational  advan- 
tages that  are  provided  for  white  persons. 
Then  it  is  claimed  that  Negroes  are  stupid, 
and  prejudice  against  them  is  increased. 
It  is  hostility  toward  a  bright  and  compe- 
tent Jew  that  makes  of  him  an  insecure 
person,  who  shifts  quickly  from  the  self- 
assertion  of  competence  to  the  submission 
of  appeasement.  Then  it  is  said  of  him 
that  he  is  inconsistent  and  insincere.  This 
is  the  process  that  electronic  engineers  call 
positive  feedback,  the  process  that  facili- 
tates itself. 

There  are  many  situations  in  psychology 
where  positive  feedback  builds  up  a  situa- 
tion and  renders  it  stable.  There  are  in- 
stances of  perception  and  instances  of  mo- 


Individual  Differences  in  Prejudice 


611 


tivation.  Prejudice  f^ets  stabili/.ed  in  (he 
same  way.  There  is  nothing  wrong  about 
stability  itscll'.  The  organism  needs  it. 
The  only  reason  why  we  wish  to  get  rid  of 
prejudice,  why  we  regret  its  stability,  is 
that  we  defined  prejudice  at  the  outset  as 
those  sets  or  attitudes  which  'ought'  to  be 
changed.  An  ought  does  not,  however, 
mean  a  psychological  difference,  and  there 
really  are  both  good  prejudices  and  bad, 
as  those  who  are  prejudiced  against  preju- 
dice presumably  know. 

Individual   Differences  in   Prejudice 

Common  experience  shows  that  people 
differ  in  prejudice.  Habitually  we  distin- 
guish between  tolerant  and  intolerant  per- 
sons. There  is  not  much  experimental  evi- 
dence on  this  point,  but  we  already  know 
enough  about  the  mechanisms  of  motiva- 
tion and  personality  to  understand  why 
these  differences  should  exist. 

There  are  really  two  reasons  for  the 
growth  of  tolerance,  one  negative  and  one 
positive.  Tolerance  may  be  caused  by 
lack  of  frustration  in  the  personal  life  or 
by  specific  motivation  which  sets  up  toler- 
ance as  a  goal. 

(1)  Persons  who  experience  many  frustra- 
tions accumulate  a  supply  of  latent  aggres- 
sion. The  frustration  may  be  constantly 
recurring  in  the  same  situation,  as  it  often 
is  with  the  very  poor  man  or  can  be  with 
the  richer  ambitiotis  man  who  is  much 
poorer  than  his  level  of  aspiration  would 
have  him  be.  Or  the  frustrations  may 
occur  in  many  different  areas.  Some  peo- 
ple seem  to  be  frustration-prone,  just  as 
others  are  accident-prone.  It  is  hard  to  say 
why  they  are,  yet  it  is  clear  that  persons 
who  have  set  their  ambitions  high  above 
their  abilities  woidd  be  perpetually  refrus- 
trated  by  having  'bitten  off  more  than  they 
can  chew.' 


i he  recuireiue  of  frustration,  whellicr 
for  the  same  cause  or  for  difftrrent  ones, 
builds  up  a  stock  of  latent  aggression. 
Here  again  there  are  individual  differences, 
for  some  persons  are  known  to  have  more 
frustration  tolerance  than  others,  that  is  to 
say,  they  can  accept  more  frustration  with- 
out gaining  commensurately  in  latent  ag- 
gression. Given  eiunigh  of  it,  latent  ag- 
gression comes  out  when  there  is  an  oppor- 
tunity. Aggression  called  latent  is  readily 
displaced;  it  is  'looking  for'  a  victim.  Mobs 
are  formed  by  frustrated  persons  with  ag- 
gression waiting  for  use.  Scapegoating  is 
a  common  relief  for  latent  aggression.  .So 
is  that  mild  form  of  half-conscious  scajje- 
goating  called  gossip.  Why  is  gossip  usu- 
ally more  unfavorable  to  its  subject— to  its 
'victim?  Because  it  is  a  means  of  relieving 
latent  aggression. 

Not  all  prejudice  operates  in  this  genera] 
way.  It  may  occur  within  a  specific  area  or 
between  two  people  only.  Di\orce  cases 
show  how  one  spouse— perhaps  with  misdi- 
rected hopes  and  aspirations— can  come  to 
be  perpetually  frustrated  by  the  other  until 
his  love  has  changed  to  hatred.  No  pro- 
fessional counselor  expects  to  get  an  ob- 
jective account  of  the  imloved  spouse  from 
the  unloving  one.  In  such  a  case  prejudice 
is  normal,  and  insight  is  offered  as  a  pai- 
tial  remedy. 

It  is  obvious  that  one  way  to  get  rid  of 
prejudice  is  to  remove  or  diminish  the 
frustrations.  Sometimes  that  method  works. 
A  man  changes  to  a  job  at  which  he  is 
more  likely  to  succeed.  People  take  vaca- 
tions to  dodge  the  daily  round  of  frustra- 
tion. It  is  hoped  that  the  diminution  of 
the  frustrations  of  the  working  classes  bv 
raising  the  standard  of  their  living  will 
reduce  social  conflict. 

(2)  The  other  w^ay  in  which  tolerance  is 
substittited  for  prejudice  is  by  motivation. 


612 


Social  Relations  of  the  Individual 


Many  people  have  the  insight  into  the  na- 
ture of  prejudice.  They  see  how  waste- 
ful prejudice  is  and  seek  to  substitute  un- 
derstanding for  it.  They  form  groups  and 
associations  to  promote  understanding  and 
get  support  from  their  members  and  from 
foundations.  Nowadays  the  old-fashioned 
pacifists  have  become  the  international  un- 
derstanders.  Such  persons  accept  tolerance 
as  a  goal  and  succeed  in  avoiding  many 
common  prejudices.  They  usuallv  side 
with  the  under-dog  in  a  social  conflict  be- 
cause they  feel  that  the  top-dog,  being  on 
top,  must  accept  responsibility  for  it.  If 
at  times  they  overcompensate  in  furthering 
the  equality  of  status  which  must  precede 
mutual  understanding,  they  are  being  hu- 
man and  illustrating  a  common  mechanism 
of  motivation. 

In  the  individual,  tolerance  accompanies 
emotional  maturity.  Not  all  physiolog- 
ically mature  persons  are,  however,  emo- 
tionally mature.  Many  old  people  are  em- 
bittered by  frustration.  The  Second  \Vorld 
\\'ar  showed  us  how  much  latent  aggiession 
can  issue  suddenly  from  men  in  their  thir- 
ties, forties  and  fifties  who  have  come  sud- 
denly to  power.  Yet,  for  all  this,  there  is 
a  psychological  and  emotional  maturity 
which  makes  for  tolerance  and  understand- 
ing; and  some  young  men  are  further  along 
in  this  development  than  others  of  their 
age.  These  people  believe  in  tolerance  and 
are  against  prejudice.  They  believe  in 
insight  into  themselves,  and  by  constant 
self-criticism  and  psychological  learning 
they  achieve  a  fair  amount  of  self-under- 
standing. They  are  shamed  by  their  own 
prejudices,  when  they  find  them,  and  try 
to  eliminate  them.  Being  unprejudiced  is 
not  always  simple  for  them,  for  often  they 
lack  the  wisdom  or  the  evidence  which  is 
necessary  for  a  decision  between  conflicting 
prejudices.      The   point    is,    however,    that 


there  are  these  individual  differences  in 
motivation  and  that  motivation  is  not  im- 
potent in  the  operation  of  rooting  out  per- 
sonal intolerance. 

Elimination  of  Prejudice 

Have  we  hope  of  getting  rid  of  those 
social  prejudices  which  are  known  to  hin- 
der social  progress  by  producing  social  con- 
flict? A  positi\e  answer  to  that  question 
would  consist  of  a  practicable  program  of 
social  engineering.  Many  men  could  for- 
mulate a  program,  but  each  would  have  his 
own.  Most  of  the  factors  to  be  considered 
and  changed  would  not  be  psychological. 
Getting  frustration  reduced  involves  sociol- 
og)',  economics  and  government— all  the  so- 
cial sciences.  It  involves  engineering  and 
agriculture  too— getting  cheap  houses  and 
plenty  of  food— and  is  plainly  not  a  topic 
for  consideration  in  this  book,  even  if  it 
could  be  reduced  to  a  statement  of  facts. 

The  chief  psychological  factors  that  can 
be  used  for  the  elimination  of  conflict-pro- 
ducing prejudice  have  been  stated  in  the 
preceding  section.  Reduce  frustration. 
Promote  the  understanding  of  outgroups. 
To  these  rules  the  psychologist  has  no  other 
magic  to  add. 

Social  science  can  supplement  psycholog)' 
if  it  can  find  ways  to  reduce  the  economic 
gain  and  the  gain  in  personal  status,  which 
are  supported  by  the  maintenance  of  group 
prejudice.  Education  can  be  aimed  di- 
rectly at  the  increase  of  social  tolerance 
and  also  at  the  acceptance  of  that  social 
engineering  which  bids  fair  to  reduce 
group  conflict.  The  present  situation  in 
the  United  States  is  by  no  means  hopeless, 
and  it  is  fortunate  that  the  social  entre- 
preneurs are  angi7  about  the  status  quo  and 
are  trying  vehemently  to  change  it.  Their 
prejudice  against  prejudice  shows  us  that 
not  all  prejudice  is  to  be  condemned,  even 


Elimination  of  Prejudice 


613 


though  it  may  seem  better  to  find  another 
word  than  prejudice  for  the  personal  drive 
whicli  makes  some  men  devote  their  Jives 
to  striving  for  the  greatest  good  to  the 
greatest  number. 

REFERENCES 

1.  Beiiedicl.  R.  Race:  science  and  jyolil'ns.  New 
^■oI•k:  Viking  Press,  1945. 

A  compact  treatment  of  the  proljlems  of  de- 
fining and  classifying  races,  and  of  the  nature 
and  history  of  race  prejudice. 

2.  Cantril,  H.  The  psychology  of  social  titoxie- 
menls.     New  York:    Wiley,   1938. 

A  very  readable  psychological  analysis  of 
some  of  the  more  significant  contemporary  so- 
cial movements. 

3.  Centers,  R.  T.  Psycliological  aspects  of  socio- 
economic stratification:  an  inquiry  into  the  na- 
ture of  class.  Princeton,  N.  J.:  Princeton  Uni- 
versity Press,  1948. 

A  detailed  public  opinion  study  directed  to- 
ward the  analysis  of  status  and  class  relation- 
ships in  American  life. 

4.  Davis,  A.,  Gardner,  B.  B.,  and  Gardner,  M.  R. 
Deep  South.  A  social  anthropological  study  of 
caste  and  class.  Chicago:  Chicago  University 
Press,  1941. 

A  revealing  application  of  the  methods  of  an- 
thropology to  the  s(udy  of  a  segment  of  oiu" 
own  American  culture. 

5.  Freeman,  E.  Social  psychology.  New  York: 
Holt,  1936. 

A  critical  exposition  of  social  psvchologv 
Avith  special  emphasis  upon  the  analysis  of  con- 
X'cntional   social   values. 


6.  Gracbcr,  I.,  and  Britl,  .S.  H.  (Lds.).     Jews  in  a 
gentile  world.     New  York:  Macmillan,  1942. 

A  series  of  searching  essays  by  outstanding 
authorities  upon  the  biological,  MX-iolf^ical, 
psycliological  and  economic  aspects  of  anti- 
Semitism. 

7.  Hartley,   E.   I,.     Problems  in   prejudice.      Sew 
■^'ork:   Kings  Crown   Press,  1946. 

An  informative  presentation  and  discussion 
of  a  series  of  large-stale  studies  in  prejudice. 

8.  Kalz,  D.,  and  Sclianck,  R.  L.    Social  psychology. 
New  York:   Wiley,   1938. 

A  systematic  and  thoroughly  docunienied 
textbook  of  social  psychology  wiih  careful  and 
precise  handling  of  basic  concepts. 

9.  Klineberg,   O.     Social   psychology.      New   York: 
Holt,  1940. 

An  illuminating  comparative  treatment  of  sf)- 
cial  |)sychology  from  the  perspective  of  social 
anthropology. 

10.  Miller,  N.  E..  and  Bollard,  J.  Social  learning 
and  imitation.  New  Haven:  ^ale  Uni\ersitv 
Press,    1941. 

A  fresh  and  closely  reasoned  analysis  of 
learning  in  social  situations  and  the  problem 
of  imitation. 

11.  Montague,  M.  F.  .\.  Man's  most  dangerous 
myth:  the  fallacy  of  race.  (2nd  ed.)  New  ^'ork: 
Cohmibia  University  Press,  1945. 

A  critical  analysis  of  the  concept  of  race  and 
iis  dangerous  implications  in  gioup  life. 

12.  AVarner,  W.  L.,  Havighurst,  R.  J.,  and  Loeh. 
^f.  B.  ]Vho  shall  be  educated?  New  York: 
Harper,   1944. 

A  brief  discussion  of  the  status  s\stem  in 
American  cultiue  and  its  implications  for  edu- 
cational  policy. 


INDEX 

Names.  The  full  names  with  dates  oi  birth  and  death  are  given  for  a  few  of  the 
very  important  psychologists  whose  names  are  cited.  After  any  names,  abbreviated 
terms  have  these  meanings:  "auth."  =  contribution  to  this  book  as  collaborator;  "bk."  = 
a  book  or  contribution  to  a  book,  cited  in  the  book  lists  at  the  ends  ol  the  chapters; 
"ref."  =  a  reference  to  the  literature  occurring  usually  in  a  legend  to  a  figure  or  table; 
"inc."  =  the  mention  is  incidental  and  of  minor  importance. 


Al)iliiies,  basic,  412f.,  558 

See  also  Aptitudes,  Tests,  Traits 
Abnormal  psychology,  12 
Accidents,  causes,  484 

control,  483f. 

incidence,  483 

proneness,  484f. 

vocational  selection,  548 
Accommodation,  visual,  300f. 
Ach,  N.,  set,  202f. 
Achromatic  colors,  274,  277 
Acoustics,     see     Hearing,     Sound 

(stimulus) 
Acquired    characters,    inheritance, 

439f. 
Action,    see    Behavior,    Reaction, 

Response 
Active      participation,      learning, 

159-61 
Acuity,  visual,  306t. 
Adaptation,  color,  283f. 

dark,  291 

equilibrium,  378 

pain,  366f. 

jaressme,  364f. 

smell,  358 

taste,  354f. 

temperature,  369 
Additive  color  mixture,  279f. 
Adequate  stimulus,  25 
Adjustment,  ailments,  535 

compensation,  517f. 

conflict,  513,  523-31 

conscious,  516 

constructive,  514f. 

counseling,  539-42 

defense,  51 9f. 

escape,  519-22 

experiments,  526f. 

family,  528f. 

fantasy.  520 

frustration  tolerance,  134 

identification,  519 

mechanisms,  516-22 

mental  hygiene,  542-4 

motivation,  512f. 

projection,  521 

psychoanalysis,  541  f. 


Adjustment  (conlinuecl) 

psychoneurosis,  511-35,  538—1! 

psychotherapy,  538—12 

rationalization,  5181. 

regression,  521f. 

repression,  520f.,  533-5 

seclusiveness,  519f. 

sex,  528f. 

solutions,  514-25 

sublimation,  522f. 

substitutive,  515 

thwarting,  511-35 

trial-and-error,  513f. 

imconscious,  516 

See  also  Conflict,  Psychoses 
Adjustors,  21,  26 
Adolescence,  maturation,  83f. 

personality,  507-9 
Adrenal  glands.  23f. 
Adrenalin,  emotion,  95f. 

hormone,  23f. 

taste,  355f. 
Adrian,  E.  D.,  bk.,  38 
Adulthood,  maturation,  84-6 

mental  hygiene,  543f. 
Advertisement,  propaganda,  573-5 
Aerial    perspective,    visual    space, 

299 
Affective  states,  90-3 

See  also   Feeling 
Afferent  neurons,  26f. 
Afterimages,  color,  284f. 
AGCT,  405f.,  408-10,  420,  555f. 
Age,  ability,  84-8 

achievement,  84—8 

degeneration,  87 

interests,  86 

learning,  154f. 

memory,  85f. 

mental,  402f. 

senescence,  86f. 
Aggression,  anger,  105f. 

cultiue,  125 

See  also  Frustration 
Ailment  adjustments,  535 
Alcohol,  effects,  481 
All-or-none  law,  neuron,  28-30 
615 


Allport,  G.  W.,  values,  431 

bk.,  213,  509,  588;  ref.,  187,  420.        ^ 
494 
Alpha,  test,  405 

Amatruda,  C.   S.,  bk.,  88;   ref..  7« 
Ambiguous  figures,  220,  227 
Amblystoma,  maturation,  67,  78f. 
Amnesia,   193f. 
.Amoeba,  response,  20f. 
Ampulla,       semicircular       canals. 

375-7 
.Anastasi,  A.,   auth.,  393-458;   bk.,         ^^ 

433,   457;    ref.,   418     "      ' 
Androgens,  116-8 
Anc.fll,    James    Rowla.nd    0869- 
),    fimctional    psychology 
10 
Anger,  105f. 
.'\nimal  psychologv,  10 
Anosmia,  357 
Anoxia,  473 
Anvil,  ear,  329f. 
Anxiety,  emotion,  108f. 

psychoneurosis,  531-3 

psychosomatic,  532f. 

situational,  532 
Apathy,    108f. 

.\pes,  matmation.  81  f..  450f. 
Aphasia,  348f. 
-Apparent  movement,  310f. 
Appetite,   119-21,  372-t 
.\ptitudes.  measurement.  410-3 

tests,  555f. 
.Arapesh,   personality.  503f. 
Army,  occupations,  555f. 

tests,  405f..  408-10.  420.  555f. 
.Arthur,  G.,  test.  406 
.Articular  sensibility.  370-2 
Ascendance,  trait.  489-91,  494.  498 
.Ascendance-submission    scale.    494 
.Aspiration  le\el.  136 
.Assimilation,  feeling.  91f. 
.Association  reactions.  61  f. 
.Associationism.  7 
.Associati\e  inhibition.  180 
.Associative  learning.  138—44 
.Attention,  conditions,  218-20 

set,  220 


616 


Index 


Attitudes,  autokinesis,  566 

effects,  566f. 

ego,  567-70 

formation,  565f. 

loyalty,  569f. 

measurement,  577-88 

polling.  577-88 

propaganda,  573-7 

recollection,   191-3 

social  atmosphere,  560 

social  change,  571f. 

social  norms.  560-2 

stereotypes,  563 

suggestion,  563-7.  593 

thought,  202f..  208-12 

See  also  Needs.  Polling,  Set 
Attributes,  intensity,  252,  251f. 

quality,  252,  254 

sensation,  252-5 
Audiograms,  deafness,  340-2 
Audition,  see  Hearing 
Autokinetic  movement.  239,  566 
Automatic  behavior,  50-3 
Autonomic  nervous  system,  35 
Axons,  27 

Babinski  reflex,  75 
Barcroft,  J.,  ref..  69 
Bard,  P.,  emotion,  100 

bk.,  Ill 
Bartlett,  F.  C,  bk.,  213;  ref.,  191 
Hartley,  S.  H.,  bk.,  268,  295,  485 
Basic  abilities,  558 
Basilar  membrane,  ear,  331-6 
Basket  endings,  skin.  365 
Bats,  avoidance  of  obstacles,  386-8 

echolocation,  387f. 
Bayliss,  W.  M.,  ref.,  34 
Beats,  tones,  326 
Beatty,  R.  T.,  bk.,  349 
Bechterev,    Vladimir    Michailo- 
vicH    (1857-1927),    condition- 
ing, 143 
Bedale.  E.  M..  ref.,  468 
Beebe-Center,  J.  G.,  bk..  Ill;  ref.. 

259 
Behavior,  automatic.  50-3 

aitastrophic.   104 

covert.  48f. 

definition,  16 

dependent      on      environment 
122-5 

Descartes,  7 

empathy,  54f. 

expression,  96-9 

ideomotor,  54 


Behavior  (conlinued) 
implicit,  48f. 
instinct.  45f.,  119 
locomotion,  40f. 
manipulation.  40f. 
motivated,  45-9 
needs.  114-22 
neonate,  75-7 
physiological  basis,  114-22 
prenatal,  69-71 
problem-solving,  47f. 
reaction,  57-62 
relation  to  structure,  119 
role  in  psychology,  4,  10 
set,  49,  59-61 
sex,   116-8 
suggestion,  54-7 
voluntary,  50-3 
See  also  Reaction,  Response 
Behaviorism,  lOf. 
Bekesy,  G.,  ref.,  334 
Belongingness,  learning,   155f. 
Benedict,  R.,  bk.,  613 
Bendey,  M.,  bk.,  213 
Berelson,  B.,  ref.,  577 
Berrien,  F.  K.,  bk.,  485 
Biddulph,  R.,  ref.,  322 
Bilateral  transfer,  179 
Bimodal   distribution,  419,  421f. 
BiNET,  Alfred   (1857-1911),  intel- 
ligence, 402f. 
Binet  tests,  402-4 
Bingham.  W.  V.,  bk.,  558;  ref.,  420 
Binocular  parallax,  301-3 
Bipolar      distribution,      measure- 
ment, 422 
Bird,  C..  bk.,  165 
Bird,  D.  M.,  bk.,  165 
Birds,  migration,  389-92 
Bitterman,  M.  E.,  auth.,  459-86 
Blind,  perception  of  objects,  384—6 
Blind  spot,  287f.,  294 
Blood  pressure,  emotion,  106f. 
Bloom.  ^V.,  lef.,  22 
Bodv-mind  theories.  7f. 
L  Boring,    E.    G.,    auth..    1-18:    bk., 
17,38,249,268,311.378,392: 
ref.,  303.  396f.:  inc..  28 
Bowles,  M.  M.,  bk.,  545 
Brain,  association  areas,  36f. 
auditory  area,  36 
frontal  areas,  37f. 
functions.  35-8 
localization  of  function,  36-8 
motor  area.  36f. 
somesthetic  area.  36f. 


Brain  (conlinued) 

visual  area,  36 
Breaking  habits,  176f. 
Breeding,  selective,  443-5 
Brewster,  D.,  inc.,  303 
Brightness,  color,  274,  276f. 

constancy,  234—7 
British  as.sociationism,  7 
British  empiricism,   7 
Britt,  S.  H.,  bk.,  613 
Brooks,  F.  D.,  bk.,  88 
Brown,  J.  F.,  inc.,  240 
Bryan,  W.  L.,  ref.,  151 
Burtt,  H.  E.,  bk.,  558 

Caffeine,  efficiency,  482 
Cannon,  Walter  Bradford  (1871-     *^ 
1945),  emotion,  95,  100 
bk.,  38,  111,  378;  ref.,  372 
Cannon-Bard  theory,  emotion,  100 
Cantril.    H.,    auth.,    560-88;    bk., 

588,  613;  ref.,  585 
Carmichael,  L.,  auth.,  64-89;  bk.. 

88,  433,  485;  ref.,  68,  71,  192         *' 
Carr,  H.  A.,  bk.,  249,  312;  ref.,  150       * 
Cartoons,  propaganda,  575 
Caste.  602f. 

Catastrophic  beha\ior.  104 
Catharsis,  psychotherapy,  541 
Cattell,  R.  B.,  bk.,  509;  ref.,  491 
Centers,  R.  T.,  bk.,  613;  ref.,  601f 
Central  tendency,  261-3 
Cephalocaudal  maturation,  67 
Cerebellum.  33 
Cerebrotonia,  425 
Cerebrum,  34 
Chemical  sense,  351-3 
Child  psychology.  12 
Childhood,  mental  hygiene,  542f. 

personality,  506f. 
Chimpanzees,  see  Apes 
Choice  reaction.  61 
Chromosomes,  437-9 
Chute,  E.,  bk.,  485 
Circular  response,  44 
Clark,  E.  L.,  bk.,  434,  457 
Class  intenal,  statistics,  397f. 
Clinical   psychology,   12f.,  538-44 
Clues,  auditory  localization.  336- 
41.  381-92 

topographical  orientation,  381- 
92 

visual  space,  298-300 
Cochlea,  anatomy,  331-3 

basilar  membrane,  331-6 

loudness.  333f. 


Index 


617 


Coclilea   (conliniied) 

mechanics,  33.S-(i 
organ  of  Colli,  331-G 

pitch,  33'1-6 
Coenotropcs,  592 
CofTee,  ediciency,  '1H2 
Comn,  T.  F...  hk.,  588 
i^  CoRhill,  C;.  V...  ici„  67 
Cohen,  M.  R..  I)lv.,   17 
Cold,   paradoxical.  369f. 

See  also  Temperature  sensibility 
Cold  emotion,  96 
Color,  achromatic,  274,  277 

adaptation,  283f. 

afterimages,  284f. 

characteristics,  269-74 

chromatic,  274 

color  blindness,  288-90 

colorimetry,  282f. 

complementary,  271 ,  279f.,  283-6 

cones,  292-5 

constancy,  236 

contrast,  285f. 

Dalton,  288f. 

deuteranopia,  289 

duplex,  271 

duplexity  theory,  294f. 

equation,  270-2,  282-3 

homogeneous  light,  275-8 

indirect  vision,  286f. 

intensity,  275-8 

laws,  279f. 

mixture,  278-83 

names,  269f. 

night  vision,  290-2,  294f. 

physiology,  292-5 

protanopia,  289 

pyiamid,  272-4 

quadruplex,  272    , 

rods,  292-5 

saturation,  277 

scotopia.  290-2,  294f. 

specification,  270-2,  282-3 

stimulus,  274-8 

tests,  290 

theory,  292-5 

triplex,  27lf. 

unique  qualities,  254,  270,  276 

visual  purple,  295 

wave  length,  275-8 
Colored  hearing,  196 
Combination  tones,  326 
Common  fimctioning,  perception, 

222f. 
Communication,   intelligibility, 
346-9 


C:omnuinication   kinilinued) 

learning,  591f. 
Coriiparalivc    psychology,    12 
C()iii[)ensation,    adjusltiiftii,    51 7f. 
Competition,  conflict,  530 

motivation,  149 
Complementary  colors,  271,  279f., 

283-6 
Compulsions,  534f. 
Concepts,  thinking.  198f. 
Conditioned     reflex,     see     Condi- 
tioned  response 
Conditioned  response,  acouisition, 
140 

anticipatory,  144 

backward,  141 

contiguity,  144 

differentiation,  141f.,  146 

emotion,  143f. 

external  inhibition,  142 

extinction,  142,  146 

generalization,  141 

higher  orders,  142f. 

language,  44,  143 

nature,  43f.,  139-44 

time  intervals,  140f. 

voluntary,  44f.,  51f. 

See  also  Learning 
Conduct,  see  Needs 
Conell,  J.  C,  ref.,  234 
Cones,  292-5 
Conflict,  ability  to  adjust,  527 

adjustment,  523-31 

approach-approach,  523f. 

approach-avoidance,  525f. 

avoidance-avoidance,  524[. 

cats,  526f. 

cultural,  530f. 

effects,  527 

experimental   neurosis,  527 

experiments,  526f. 

family,  528f. 

group  loyalty,  531 

hedonic,  93 

sex,  529f. 

sources,  528-31 
Consciousness,  Descartes,  7 

illusion,  5f. 

nature,  5-7,  9 

role  in  psychology,  4-7,  9 
Consonance,  music,  345 
Constitutional  types,  422-5,  502 
Contiguity,  law,  144 
Contour,  perception,  229 
Contradiction,   hvpnosis.   56f. 


ixtnuml,  color,  285f. 
feeling,  91  f. 

si/c,  305 
taste,  355 
C:ontrol,  cxiK-rimental,   I  If. 
Con\ergcnfe,  cyc-s,  3fK)f. 
C:onvcrsion  hysteria,  535 
C:ooperalion,  conflict,  5.30 
Correlation,  coefficient.  396-401 

electrical,  399-401 
Cortex,  maturation,  77 
Corticalization,  68 
Cortin,  23 

Corti's  organ,  ear,  331-6 
Co-twin  control,  450 
Counseling,    client-centered,    539- 
41 

nondirective,  539-41 

psvchoanalysis.   54 If. 
Covert  behavior,  48f. 
Cowdry,  E.  V.,  bk.,  88 
Crafts,  L.  W.,  bk.,  62 
Cranial  autonomic  system.  35 
Creed,  R.  S.,  bk.,  38 
Crespi,  L.  P.,  auth.,  589-613 
Cretinism,  426 
Crime  detection,  62 
Crisler,  G.,  ref..  140 
Crista,   semicircular  canals.  375-7 
Criterion,  tests,  395 
Critical  ratio,  statistics,  428 
Crocker,  E.  C,  bk..  359 
Cross-education,  179 
Crowds,  597f. 
Cruze,  W.  W.,  ref.,  79 
Crying,  104 
Culture,  biological  groups.  455f. 

conflicts,  530f. 

culture-free  test,  406 

heritage.  590 

infants,  450 

needs,  124f. 

personality.  503-5 

racial  differences.  431-3 

regional  influences.  453-5 

rural  influences,  453-5 

socio-economic  status,  451-3 

technology,  571  f. 

urban  influences.  453-5 

See  also   Heredity  vs.   environ- 
ment. Social  norms 
Cupula,  semicircular  canals,  375f. 
Custom,  see  Social  norms 
Cutaneous  sensibilitv,  localization 
365 


618 


Index 


Cutaneous   sensibility   (conlinued) 

receptors,  360-2,  365-7,  370 
Cycloid  type,  489-91 

Dallenbach,  K.  M.,  ref.,  173,  190; 

inc.,  363 
Dalton,  J.,  color  blindness,  288f. 
Darrow,  C.  W.,  ref.,  170 
Darwin,   Charles   Robert   (1809- 
1882),  emotion,  96 
evolution,  9 
Dashiell,  J.  F.,  ref.,  512,  594 
Davis,  A.,  bk.,  613 
Davis,  H.,  bk.,  268,  350:  ref.,  335 
Deafness,  conduction,  342 
hearing  aids,  343f. 
nature,  340-4 
nerve,  342 
Dearborn,  AV.  F.,  bk.,  485 
Decibel,  sound,  324f. 
DeDecker,  C,  ref.,  462 
Defense  mechanisms,  519f. 
Definitions,  basic,  16f. 
Delusion,  dreams,  196 

perception,   188f. 
Dementia  praecox,  536 
Dendrites,  27 
Dennis,  W.,  bk.,  17,  509 
Denny-Brown,  D.,  bk.,  38 
Depression,  psychosis,  536f. 
Derived  needs,  121  f. 
Descartes,       Rene       (1596-1650), 

dualism,    7 
De  Silva,  H.  R.,  bk.,  485 
Determining  tendency,  see  Set 
Detour,  problem -solving,  129 
Deuteranopia,  289 
Development,  64-89 

See  also  Growth,  Maturation 
Dewey,  E.,  bk.,  88 
Dewey,    John    (1859-        ).    func- 
tional  psychology,   10 
Dickson,  W.  J.,  bk.,  486 
Dictionary  of  Occupations,  552 
Diet,  natural,  119-21 
Difference  tones.  326 
Dimmick,  F.  L.,  auth.,  269-312 
Diplopia,  302 
Discrimination,  reaction,  61 

senses,  268 
Distributed      practice,      learning, 
156f.,  164 
retention,  171 
Distribution,   bimodal,   419,   421f 
bipolar,  422 
individual  differences,  417-27 


Distribution  (conlinued) 

normal,    262f.,    418f. 

normal  curve,  41 8f. 

observed,  262f. 

overlapping,  428f. 
Dollard,  J.,  bk.,  166,  613;  ref.,  592 
Dominance,  compensatory,  498 

parental,  529 

trait,  489-91,  494,  498 
Dominance-submission,    test,    414, 

420 
Dominant      characters,      heredity. 

440f. 
Dreams,  196 
Drives,  see  Needs 
Drugs,  efficiency,  480-3 
Dualism,  7f. 
Duct  glands,  23 
Ductless  glands,  22-4 
Duncker,  K.,  bk.,  213;  inc.,  239 
Dunlap,  K.,  habits,  176 
Duplexity  theory,  vision,  294f. 
Dusser  de  Barenne,  J.  G.,  bk.,  378 
Dynamic  psychology,  Lewin,  523- 
.Sl 

movement,  12 

needs,  126 

Ear,  anatomy,  328-33 

functions,  327-36 

inner,  330-6 

middle,  329f. 

outer,  329 

saccule,  374-8 

semicircular  canals,  331,  374-8 

utricle,  374-8 

vestibule,  331 

See  also   Hearing 
Ebbinghaus,      Hermann      0850- 

1909),  memory,   167.   173 
Eccles,  J.  C,  bk.,  38 
Echolocation,  387f. 
Economic  status,  abilities,  451-3 
Ectomorphy,  423f. 
Educational  psychology,  12 
Effect,  learning,  147f.,  163 
Effectors,  21^ 
Efferent  neurons,  26f. 
Efficiency,  accidents,  483-5 

alcohol.  481 

bodily  expense,  460f. 

coffee,  482 

drugs,  480-3 

effort,  461-6 

fatigue,  460-6 

fatigue  products,  464 


Efficiency  (continued) 
heart  and  blood,  462f. 
ilhmiination,  475-7 
input,  460f. 

job  satisfaction,  465,  472,  482f. 
meaning,  459 
measurement,  460-7 
methods  engineering.  465f. 
morale,  465,  472,  482f. 
motion  study,  470-2 
muscle  tension,  463f. 
noise,  477f. 
output,  460 
output/input,  459,  467 
oxygen  consimiption,  461f.,  468, 

472f. 
performance,  460,  464-6 
rating  scale,  460 
rest,  478-80 
skin  resistance,  464 
sleep,  480 
speed  tests,  466 
tea,  482 

temperature,  473-5,  484 
time  study,  470-2 
tobacco,  481  f. 
work,  467-78 
work  decrement,  466f. 
ivork  hours,  478 
See  also. Study,  Work 
Effort,  efficiency,  461-6 
heart  and  blood,  462f. 
muscle  tension,  463f. 
oxygen  consimiption.  461f.,  468, 

472f. 
skin  resistance,  464 
Ego,  attitudes,  567f. 
change,  568 
development,  568 
involvement,  568f. 
needs,  135f. 
Eidetic  images.  187f. 
Ellis,  W.  D.,  bk.,  17,  312 
Embryo,  growth,  69-72 
Emergency  theory,  emotion,  95f. 
Emotion,  adrenalin,  95f. 
anger,  lOSf. 

attitude  formation.  565f. 
autonomic  system.  94—6 
blood  pressine,  106f. 
Cannon-Bard  theory,  100 
conditioned,  143t. 
consciousness,  99f. 
crying,  104 
disorders,  108-10 
emergency  theory,  95f. 


Index 


619 


Emotion  {conlinued) 

expression,  96-9 

fear,  104f. 

functional   disorders,   109 

galvanic  skin  response,  106 

genesis,  101  f. 

hygiene,  11  Of. 

infants,  102 

James-Lange  theory,  100 

laughing,  103f. 

learning,  lOOf. 

maturation,  77 

measurement,  106-8 

nature,  93f. 

observation,   107 

pathology,  108-10 

primitive,  102 

psychoanalysis,  107 

psychosomatics,  109f. 

questionnaires,  108 

rating  scales,  107 

recollection,  190 

smiling,  103 

stability,  414 

startle  pattern,  98f. 

tension,  96 
Emotionality,   108 
Empathy,  54f. 
Empiricism,  7 
Encephalization,  68 
Endocrine  glands,  drives,  118 

functions,  22-4 

personality,  500f. 
Endomorphy,  423f. 
Engel,  R.,  inc.,  356 
Engineering,  methods,  465f.,  470-2 
English  associationism,  7 
English  empiricism,  7 
Environment,  conception,  442 

needs,  116,  122-5 

5eea/50  Heredity  vs.  environment 
Equilibrium,  adaptation,  378 

affective,  92 

habituation,  378 

receptors,  375,  377f. 

semicircular  canals,  374-8 
Erlanger,  J.,  bk.,  38 
Escape  mechanisms,  519-22 
Eskimos,  personality,  503f. 
Estabrooks,  G.  H.,  bk.,  62 
Estrogens,  116-8 
Euphoria,  anoxia,  473 

emotion,  108 
Evans,  H.  M.,  ref.,  437 
Exercise,  learning,  153f. 
Experiment,  nature,  13-6 


Experimental   neurosis,  527 
Experimenter,  definition,  17 
Exploratory  behavior,  47 
Expressive  behavior,  90-9 
External  inhibition,  142 
Exteroccptors,  26 
Extinction,    conditioned    response, 

142,  146 
Extraversion,  type,  488f.,  490f. 
Eye,  accommodation,  300f. 

ciliary  muscle,  292 

convergence,  300f. 

duplexity  theory,  294f. 

physiology,  292-5 

retina,   292-5 

structure,  292f. 

See  also  Color 
Eye  movements,  reading,  182 

Facial  expression,  97f. 
Facial  vision,  blind,  384-6 
Facilitation,  neural,  35 
Factors,  analysis,  41  If. 

group,  412 

organization,  412f. 

specific,  412 
Fallacies,  thinking,  206-8 

word,  207f. 
Family,  conflict,  528f. 

cultural  heritage,  590 

dependency,  591 

emotional  attachment,  591 

institution,  590f. 

permanency,  591 

resemblance,  440f.,  445-7 

responsibility,  591 

social  control,  590f. 

socialization,  589 
Fantasy,  adjustment,  520 

need,  130-2 
Fatigue,  efficiency,  460-6 

heart  and  blood,  462f. 

measurement,  460-6 

muscle  tension,  463f. 

oxygen  consimiption,  461  f.,  468. 
472f. 

physiological  products,  464 

skin  resistance,  464 
Fear,  emotion,  104f. 

phobia,  533f. 

unlearning,   175f. 
Fearing,  F.,  bk.,  17 
Fechner,  Gustav  Theodor  (ISOI- 
1887),    experimental    psychol- 

ogy,  8 

psychophysics,  255 


Fecblcmindcdiicss,  425f. 
Feeling,   as.<iimilation,  91f, 
biological   use,  91 
contrast,  91  f. 
cquilifjrium,  92 
learning,  92f. 
relativity,  91f. 
retention,   170 
stimuli,  90f. 
tastes,  356 
\(tvi,   C,   galvanic  skin   response, 

106 
I  erree,  C.  E.,  ref.,  477f. 
Fetus,  growth,  69-72 
Field  theory,  conflict,  523-31 
Figure    and    ground,    perception, 

224-8 
Final   common  path,  neural,  34f. 
Fixation,   space   clue,  299 
Fletcher,  H.,  bk.,  350;  ref.,  348 
Flight  from  reality,  131 
Flugel,  J.   C,  bk.,'  17 
Folkways,  590 
Forbes,  A.,  bk.,  38 
Forgetting,  see  Retention 
Formal  discipline,  177f. 
Fosdick,  S.  J.,  ref.,  483 
Foster  family  relationships,  447-9 
Fourier,    J.     B.    J.,     analysis    of 

sound,  316-9 
Foveal     blindness,     night    vision, 

291  f. 
Fraser,  J.,  ref.,  6 
Fraternal     twins,     heredity,     439. 

446f.,  450 
Freeman,  E.,  bk.,  613 
Freeman,  F.  N.,  bk.,  457 
Freeman,  F.  S.,  bk.,  433,  457 
Freeman,  W.  J.,  bk..  38 
French,  N.  R.,  ref.,  349 
Frequencv,  learning,   153f. 
Frequency  distributions.  417-21 
Freud,    Sigmind    (1856-1939).    re- 
pression, 170,  520 
imconscious  mind,  10 
bk.,  544 
Frontal     lobes,    association    area 
36f. 
prefrontal  lobotoiuy,  38 
Frustration,  anger.  185f. 
emotion.   130f. 
proneness,  611 
psychoneurosis.  511-35 
tolerance.  134,  491.  611 
Fulton,  J.  F.,  bk.,  SS 
Functional  psycholog^■,   lOf. 


620 


Index. 


Functional   psychoses,  536t. 
Fundamental  tone,  319 

Gallup,  G.,  polling,  578-84 

bk.,  588 
Gallup  poll,  580-3 
Galton,       Francis       (1822-1911), 
ability  inventory,  546 

heredity,  446 

mental   inheritance,  9 

nature-nurture,  437 
Galvanic  skin  response,  106 
Galvanotropism,  42 
Gangs,  loyalty,  570 
Gardner,  B.  B.,  bk.,  613 
Gardner,  E.,  bk.,  38 
Gardner,  M.  R.,  bk.,  613 
Garrett,  H.  E.,  bk.,  165;  ref.,  145, 

434 
Gasser,  H.  S.,  bk.,  38 
Gates,  A.  I.,  ref.,  161 
Geldard,  F.  A.,  auth.,  360-79;  ref., 

364;   inc.,  368 
Gellerman,  L.  W.,  ref.,  253 
General  psychology,  12 
General  type,  growth,  73 
Generalization,  experimental,   14 

stimulus,   141,    146 

thinking,   198f. 
Genes,  growth,  65f. 

heredity,  437-9 
Genital  type,  growth,  73 
Genius,  426f. 
Geotropism,  42 
Geotschius,  P.,  bk.,  350 
Gerard,  R.  W.,  bk.,  88 
German  psychology,  8-11 
Gesell,  A.,  tests,  408 

bk.,  88;  ref.,  78 
Gestalt  psycholog)',   lOf. 
Gibson,  J.  J.,  ref.,  192 
Gilbert,  M.  S.,  bk.,  88 
Gilbert,  R.  S.,  bk.,  62 
Gilliland,  A.  R.,  bk.,  434,  457 
Glands,  duct,  23 

effectors,  21-4 

endocrine,  22-4 
Glare,  efficiency,  476 
Goal  gradient,  learning.   163 
Goldscheider.  A.,  inc.,  362 
Golgi    spindles,    tendons,   372 
Gonads,  growth,  65 

hormones,  24 

personality,  501 
Graeber,  I.,  bk.,  613 
Grah,im,  C.  H.,  bk.,  295 


Grasping  reflex,   75 

Gray,  unique  color,  272-4.  283 

Greeks,  personality,  503 

Greene,   E.  B.,  bk.,  434,  510 

Griffin,  D.  R.,  auth.,  380-92 

Group  tests,  404-6 

Groups,  assembled,  596-8 

attachment,  598f. 

conception,  599 

crowds,  597f. 

dispersed,  598f. 

interrelations,  600-3 

loyalty.  569f. 

membership,  570 

mobs,  597f. 

social  participation,  601-3 

socio-economic  interest,  600f. 
Growth,  abilities,  78-89 

body  proportions,  72 

definition,  64f. 

embryo,  69-72 

exercise,  66 

fetus,  69-72 

food,  65 

germinal  period,  68 

heredity,  65 

hormones,  65 

maturity,  74 

prenatal,   68-72 

types,  72-4 

0-5  years,  78f. 

See  also  Development,  Matura- 
tion 
Guerriere,  M.  J.,  inc.,  388 
Guilford,  J.  P.,  bk.,  17,  268;  ref., 

363,  376 
Guilt,  see  Anxiety 
Gurnee,  H.,  bk.,  18 
Guthrie,  E.  R.,  bk.,  166 
Guyer,  M.  F.,  ref.,  22 

Habits,  breaking,  176f. 
Habituation,  rotation,  378 
Haddon,  A.  C.,  bk..  434 
Haggeriy,   M.   E.,  ref.,  452 
Hahn,  H..  inc.,  354 
Hair  cells,  ear,  334 
Hallucinations,    188f.,    196f.,    216f. 
Hannner,  ear,  329f. 
Harmonics,  tones,  319 
Harmony,   music,  344f. 
Harper,  R.  S.,  ref.,  261 
Harpman,  J.  A.,  ref.,  361 
Harrell,  M.  S.,  ref.,  557 
Harrell,  T.  W.,  ref.,  557 
Harris,  J.  A.,  ref.,  73 


narrower,  M.,  bk.,  249 
Harier,  N.,  ref.,  151 
Hartley,  E.  L.,  bk.,  613;  ref.,  606 
Hartmann,  G.  W.,  bk.,  17 
Hartshorne,  H.,  character,  494f. 

test,  420f.,  431 

ref.,  421 
Havighurst,  R.  J.,  bk.,  613 
Hayakawa,  S.  I.,  bk.,  213 
Hayes,  S.  P.,  bk.,  392 
Hearing,  aids,  343f. 

bats,   386-8 

Ijeats,  326 

characteristics,  313f. 

combination  tones,  326 

deafness,  340-4 

echolocation,  387f. 

localization,  336-41 

perception  of  obstacles,  384-8 

stimulus,  314-9 

See  also  Communication,  Deaf- 
ness,    Ear,     Localization     of 
sound.  Music,  Speech 
Heat,  perception,  369f. 
Hecht,  S.,  bk.,  296 
Hedonic  tone,  90-3 

See  also  Feeling 
Hedonism,  93 
Hegner,  R.  AV.,  bk.,  457 
Heidbreder,  E.,  bk.,   17 
Helicotrema,   ear,   331 
Heliotropism,  41f. 
Helmholtz,     Hermann      Liiuwir, 
Ferdinand    von     (1821-1894), 
experimental   psvchology,  8 
Henning,  H.,  smell,  356 
Henry,  G.  W.,  bk.,   18 
Heredity,      acquired      characters, 
439f. 

biology,  436-43 

chromosomes,  437-9 

family  resemblance,  440f.,  445-7 

function,  442f. 

genes,  437-9 

growth,  65 

learning,  442f. 

mechanism,  65f. 

Mendelian,  440-2 

misconceptions,  439-42 

jjrenatal   influence,  440 

selective  breeding,  443-5 

structure,  442f. 

twins,  439,  446f.,  450 

unit   characters,  438f. 
Heredity     vs.     environment,     ape 
and    child,    Hlf.,     ir.Of. 


Index 


621 


Heredity    vs.    enviioimieiit     (run- 
tinned) 

blood   reliilioiiship,  446f. 

culture  vs.  biology,  45.5f. 

family   relationships,  4'15-7 

foster  families,  447-9 

learning,  78-82 

maturation,  449f. 

pre.sent  status,  456f. 

problem,  436 

rural   influence,  453-5 

socio-economic  status,  4.')l-3 

urban   influences,  453-.') 

See  also  Maturation 
Heron,  W.  T.,  ref.,  170 
Herrick,  C   J.,  bk.,  38;  ref.,  33 
Hertz,  M.,  inc.,  225 
Heterozygous  individuals,  441 
Hilgard,  E.  R.,  bk.,  62,  166;   ref., 

43 
Hill,  A.  v.,  bk.,  38;  ref.,  461 
Hill,  W.  E.,  inc.,  220 
Histogram,  statistics.  418 
Hogan,  H.  P.,  ref.,  192 
Hollingworth,  L.  .S.,  bk.,  88 
Holmgren,     F.,     color     blindness, 

290 
Holzinger.  K.  J.,  bk.,  457 
Homeostasis,  sex,  116 

temperature,  473f. 
Homing,  389 

Homogeneous  light,  275-7 
Homozygous  individuals,  441 
Honzik,  E.  H.,  ref.,  148 
Hooker,  D.,  ref.,  70 
Hormones,  glands,  23f. 

growth,  65 

personality,  500f. 

sex,  116-8 
Homey,  K.,  bk.,  544 
Horowitz,  E.  L.,  bk.,  588 
Hoskins,  R.  G.,  ref.,  23 
Hovland,    C.    I.,    auth.,     138-84; 

ref.,  141  f.,  156,  162,  172 
Huddart,  J.,  color  blindness,  288 
Hue,  274 
Hull,  C.  L.,  bk.,  63,  166;  ref.,  141, 

147,  157 
Humidity,  efficiency.  474 
Hunches,  thinking.  207 
Hunger,  appetite,  373 

contractions,  115.  372f. 

drive,  115f.,  373f. 

food  needs,  119-21 

habit,  115f. 

pangs,  372f. 


Hunger   (ronliruied) 

physiology,  1 15 

.social,  116,  124 

suggestion,  115f.,  124 
Hunt,  I.  McV.,  bk.,  510,  .54  I 
Hinit,   W.   A.,  auth.,  90-111;    ref., 

99.   Ill 
Hunter,  W.  S.,  bk.,  166 
Hurlock,  E.  B.,  ref.,  149 
Husband,  R.  W.,  ref.,  1.59 
Huxley,  J.  S.,  bk.,  434 
Hybrids,  heredity,  441 
Hydrocephalic  deficiency.   120 
Hygiene,    emotion,    llOf. 

mental,  542-4 
Hyperthyroidism,  108 
Hypnosis,    contiadiction,    56f. 

phenomena,  56f. 

posthypnotic   suggestion,    57 
Hypochondria,  532 
Hypothalainus,  brain,  34 

maturation,  77 
Hypothesis,  experimental,   13-6 

thinking,  203-7 
Hypothetico-deductive  method.  15 
Hysteria,   conversion,   535 

Idealism,  perception,  216 
Identical      twins,     heredity,     439. 

446f.,  450 
Identification,  mechanism.  519 

socialization,  593f. 
Ideomotor  action,  54 
Idiot,  426 
Illumination,  efficiency,  47.5-7 

indirect,  476f. 
Illusions,  moon,   15f. 

optical,  305f. 

perception,  216 
Image,    change   with    time.    190-3 

types,   194f. 

See  also  Recollection 
Imagination,   dreams,   196 

eidetic.   187f. 

false,  197 

hallucination,   196f. 

nature.   185,    195 

needs,  130-2 

perception,  196f. 

synesthesia,   196 

types.    194f. 
Imbecile.  426 
Imitation.  591f. 
Implicit  behavior,  48f. 
Incentives,  needs.   116,  123f. 
Incidental    learning.   153 


Incubation,  ihougJil,  20'{,  212 
Incus,  ear,  329f. 

Jiiflircct   vision,   blinrl    ifKjt,  287f., 
294 

color   zones,   280f. 
Individual     differences,     distribu- 
tion, 417-27 

genius,  420f. 

history,  12 

imagery,    194f. 

intelligence,  402-10 

learning,    15  If. 

nieasuremeiu,  393-401,  410-27 

needs,  134-6 

prejudices,  61  If. 

reaction,  62 

retention,  169 

sex,  430f. 

subnormals,  425f. 

thinking,  211 

types,  421-7 

See     also     Culture,      Hereditv 
Heredity  vs.  environment,  In- 
telligence, Tests 
Industrial   psychology,  12 
Infants,  intelligence,  408 

personality,  505f. 
Inferiority,  feeling,  507 
Ingroup,  599 

Inheritance,    acquired    characters 
439f. 

biological.  436-13 

See  also  Hereditv 
Inhibition,  associative,   180 

external,  142 

neural,  35 

repression,  521.  533-5 

retroactive,  173f. 
Ink-blot  test.  495f. 
Input,  see  Efficiencv 
Insecurity,  adjustment.  528 

personality,  506f. 
Insight,  learning,   152—4 

psychotherapv,  541  f. 

thought,  203-6 
Instinct,  birds,  46 

chicks,  45f. 

cultural.  125 

fish.  46 

maternal,   125 

nests.  46 
Insulin,  honnone,  24 

shock   therapv.  537f. 
Intelligence,   adult.   40°: 

Binet  tests,  402-4 

genius,  426f. 


622 


Index 


Intelligence  (continued) 

group   tests,  404-6 

infants,  408 

mental   age,  402f.,   409f.,   425-7 

occupations,  556f. 

performance  tests,  406f. 

quotient,  402f.,  409f.,  425-7 

race,  431-3 

subnormal,  425f. 

test  evaluation,  408-10 

See  also  Tests 
Intensity,  attribute,  252.  254f. 

neural  conduction,  30 
Interoceptors,  26 
Interposition,  visual  space,  298 
Interval  scale,  measurement,  259f. 
Interview,  personality,  492 
Introspection,  8-10 
Introversion,  type,  488,  490f. 
Introversion-extraversion,  test,  414 
IQ,  402f.,  409f.,  425-7 

Jackson,  C.  M.,  ref.,  72f. 
James,  William  (1842-1910),  emo- 
tion, 99f. 

functional  psycholog^•,  10 

laboratory,  8 

transfer,  178 

bk.,  249;  inc.,  243 
James-Lange  theory,  emotion,  100 
Japanese    art,   size    and    distance, 

233f. 
J-curves,  420f. 
Jenkins,  J.  G.,  ref.,  173 
Jenkins,  T.  N.,  bk.,  392;  ref.,  127 
Jennings,  H.  S.,  bk.,  457 
Jensen,  F.,  bk.,  510 
Jersild,  A.  T.,  bk..  Ill 
Job,  analysis,  551-3 

satisfaction,  465,  472,  482f. 

specification,  551 
Joints,   sensibility,   370-2 
Jukes,  family  resemblance,  446 
Jung,    Carl    Gustav    (1875-        ). 
galvanic  skin  response,  106 

Kallikaks,  family  resemblance,  446 

Kasner,  E.,  bk.,  213 

Katz,  D.,  bk.,  136,  613 

Keith,  A.,  ref.,  330,  332 

KeUer,  F.  S.,  bk.,  17 

Kellogg,  L.  A.,  bk.,  88,  457;  ref., 

451 
Kellogg,  W.  N.,  bk.,  88,  457:  ref., 

451 


Kinesthesis,  nature,  370-2 
receptors,   372 

See   also    Equilibrium,    Organic 
sensibility.    Proprioception 
Kingsley,  H.  L.,  bk.,  166 
Kinsey,  A.  C,  bk.,  136 
Kirby,  T.  K.,  ref.,  464 
Kleitman,  N.,  ref.,  140 
Klineberg,   O.,  bk.,   136,  434,  613 
Koenig,  R.,  inc.,  317 
KoFFKA,    Kurt    (1886-1941).    bk.. 

249 
KoHLER,    Wolfgang    (1887-        ), 
bk.,    17,    214,    249;    ref.,    136, 
205;  inc.,  203 
Kolmer,  W.,  inc.,  377 
Krause  end  bulbs,  skin,  361,  370 
Kuder,  G.  F.,  inc.,  557 

Ladd-Franklin,  C.,  bk.,  296 
Lamarck,  J.  B.  P.  A.  M.  de,  in- 
heritance, 439f. 
Landis,  C,  bk..  Ill,  544;  ref.,  99 
Lane,  C.  E.,  ref.,  327 
Lange,    Carl    Georg    (1834-1900), 

emotion,  100 
Langfeld,  H.  S.,  ref.,  196 
Language,  acquisition,  594f. 

circular  response,  44 

conditioning,   143 

functions,  200 

maturation,  82f. 

semantics,  595f. 

thought,  200f.,  207f. 
Lashley,  Karl  Spencer  (1890-    ), 

bk.,  392 
Laughter,   103f. 
Lawton,  G.,  bk.,  510 
Leadership,  599f. 
Learning,  age,  154f. 

annoyance,  147 

associative,   138^4 

associative  inhibition,  180 

automatic  acts,  52f. 

avoiding  distraction,   163f. 

avoiding  errors,  163 

belongingness,   155f. 

bilateral   transfer,   179 

conditioning,   139-44 

contiguity,  144 

cinves,   150-3 

distributed    practice,    156f.,    164 

effect,  147f.,  163 

emotion,   lOOf. 

exercise,   153f. 

feeling,  92f. 


Learning  {conlimied) 
formal  discipline,   177f. 

frequency,   153f. 
goal  gradient,  163 

guidance,  165 

heredity,  442f. 

heterogeneous   transfer,    179f. 

liomogeneous   transfer,    178f. 

incidental,  153 

individual  differences,  154f. 

insight,  152-1,  203-6 

kind  of  material,  155f. 

language,  200-2 

limits,   152f. 

logical,   156 

massed  practice,  156f. 

maturation,  79-83 

maze,  161-3 

meaning,   155f.,   183 

memory  systems,  183f. 

motivation,    146,    148f.,    159-61, 
165,  181 

needs,   128L 

negative  transfer,  177,   180f. 

overlearning,  164f. 

participation,   159-61,   183f. 

parts,  157f. 

perception,  241  f. 

plateaus,  151f. 

positive  transfer,  177f.,  180f. 

practical  rules,   163-5 

practice,   149-54,   156f. 

primacy,   163 

recency,  163 

recitation,  160f. 

reinforcement,   142,   147 

satisfaction,  147,  163 

serial,  161-3 

sex,  154 

skills,  161-5 

speed  vs.  accuracy,  165 

transfer,  177-81 

trial-and-error,  144-8,  203-6 

verbalization,    158f. 

verbatim,  156 

voluntary  acts,  52f. 

wholes,   157f.,   164 

See    also     Adjustment,     Condi- 
tioned    response.     Retention. 
Study,   Unlearning 
Leptosome  type,  423f. 
Lewin,     Kurt     (1890-1947),     con 
flict,  523-31 

bk.,  136,  545;  inc.,  523-5 
Lickley,  J.  D.,  ref.,  371 


Inde 


623 


Licklider,    J.    C.    R.,    correlation, 

401 
Liddell,  E.  G.  T.,  bk.,  38 
Lie  detectors,   106f. 
Light,  purity,  277 

range  of  radiation,  275 

spectrum,  275f. 

stimulus,  274-8 
Light     and    shade,    visual     space, 

2991. 
Lillie,  R.  S.,  bk.,  38 
Limen,  see  Thresholds 
Limits,  learning,  152 
Lincoln,  F.  C,  bk.,  392 
Lindquist.  E.  F.,  bk.,  434 
Linear    perspective,    visual    space, 

298f. 
Lobotomy,  prefrontal,  38,  537f. 
Localization  of  felt  pressmes,  er- 
rors, 365 
Localization   of   obstacles,  echoes, 

387f. 
Localization  of  seen  objects,  con- 
stancy, 236 
Localization    of    sound,    binaural 
clues,   337-9 

characteristics,  236,  336f. 

intensitive  clues,  337-9 

secondary  clues,  339f. 

time  clues,  337-9 
Locke,     John     (1632-1704),     em- 
piricism, 7 
Locomotion,   response,   40-3 
Loeb,  M.  B.,  bk.,  613 
Logical  learning,  156 
Loudness,  cochlea,  333f. 

constancy,  236 

scale,  324-6 

thresholds,  324 

tones,   323-6 
Lovewell,  E.  M.,  ref.,  363 
Loyalty,   attitude,   569f. 
Luh,  C.  W.,  ref.,  168 
Luminance,  color,  276f. 
Lurie,  M.  H.,  ref.,  335 
Lymphoid  type,  growth,  73 
Lyon,  D.  O.,  ref.,  155,  157 

Mach,  E.,  inc.,  225f. 
MacKinnon,  D.  W.,  auth.,  112-36 
Macula,  sacs,  377f. 
Maier,  N.  R.  F.,  ref.,  42 
Malleus,  ear,  329f. 
Man,  nature,  1-4 
Mania,  psychosis,   536f. 
Manic-depressive   psychosis,   536f. 


Manipulation,  response,  40f. 
Marquis,  D.  C,   bk.,  39,  G2,   160, 

ref.,  43 
Martin,  C.  E.,  I)k.,  136 
Masculinity-femininity,  index,  4.')1 

scale,  494 
Masking,   tones,  326f. 
Maslow,  A.  H.,  bk.,  545 
Massed  practice,  learning,  15Gf. 

retention,   171 
Masserman,  J.  H.,  ref.,  526 
Masturbation,  530 
Materials,  learning,  155f. 

retention,   169-71 
Maternal  instinct,  125 
Maturation,  adaptive  behavior,  78 

adolescence,  83f. 

adulthood,  84-6 

Ambly stoma,  67,  78L 

apes,  81  f.,  450L 

cephalocaudal,  68 

chicks,  79 

children,  79-83 

cortical  restraint,  77 

corticalization,  68 

definition,  64f. 

emotion.  77 

encephalization,  68 

heredity  vs.  environment,  449f. 

integration,  66 

language,  82f. 

learning  ability,  79-83 

neonate,  74-7 

personality,  505-9 

postnatal,  77-83 

prenatal,  67f. 

puberty,  83f. 

receptors,  76f. 

speech,  82f. 

trajectory  of  life,  84-8 

twins,  80f. 

See  also  Development,  Growth, 
Heredity  vs.  environment 
^L-lturity,  growth,  74 

personality,  509 
Maximow,  A.  A.,  ref.,  22 
May,  M.  A.,  character,  494f. 

test,  420L,  431 

reL,  421 
Maze,  learning,  47,  161-3 
McBride,  K.,  bk.,  39 
McDouGALL,  William  (1871-1938), 

social  psychology,  13 
McGeoch,    J.    A.,    bk.,    166;    ref., 
151,  170f. 


.McGraw,  .M.  B.,  bk.,  89;   ref.,  76 

80 
.McHugh,  G.,  ref.,  328,  375 
.McKinney,  V.,   bk.,  545 
.VIead,  .VL,  bk.,   136,  434,  510 
.Mean,  261-3 
.Meaning,  learning,  155f. 

perception,  230f. 

semantics,  595f. 
Measurement,  aptitudes,  410-3 

attitudes,   577-88 

central   tendency,  261-3 

efficiency,  460-7 

factor   analysis,   41  If. 

fatigue,  460-6 

individual    differences.   393-101 
410-27 

loudness  scale,  321-6 

masculinity-femininity,   431 

opinions,  577-88 

personality,  413-7,  491-7 

pitch  scale,  322f. 

psychological,   250-68 

psychophysics,  255-68 

sampling,  427-30 

scales,  257-61 

somatotypes.  422—4 

temperament,  425 

thresholds,  263-7 

traits,  410-3 

types,  421-5 

^V'ebe^  fractions,  267f. 

weight  scale,  260f. 

See  also  Polling,  Psychophysics, 
Statistics 
Mechanisms,    compensation,   517f, 

defense,  519f. 

escape,  519-22 

fantasy,  520 

identification.  519 

projection,  521 

psvchological,   516-22 

rationalization.  518f. 

regression,  521  f. 

repression,  520f.,  533-5 

seclusiveness,  519f. 

sublimation.  522f. 
Median,  261-3 
Medulla  oblongata.  33 
Meissner     corpuscles,     skin,     361 

365f. 
Mel,  pitch,  32If. 
Melody,  344f. 

Membrane  theorv,  neuron,  28f 
Memory,  see  Retention 
Memorv  svstems,  18of. 


624 


Index 


Mendelian    inheritance,   440-2 

Mental  age,  402f. 

Mental        hygiene,       adjustment, 

542-i 
emotion,   11  Of. 
Mental   maps,  see  Topographical 

orientation 
Mental  tests,  see  Tests 
Merrill,     M.     A.,     Stanford-Binet 

tests,  403 
ref.,  404,  419 
Mesomorphy,  423f. 
Method,  science,  13-6 
Methods  engineering.  465f.,  470-2 
Metrazol,  shock  therapy,  537f. 
Microcephalic  deficiency,  426 
Microstructure,    perception,    226, 

229 
Migration,  birds,  389-92 
Miles,  C.  C,  sex,  431 

bk.,  434 
Miles,  W.  R.,  bk.,  89;   ref.,  85 
Miller,  D.  C,  ref.,  313 
Miller,  G.  A.,  ref.,  267,  349 
Miller,  N.  E.,  bk.,   166,  613;   ref., 

592 
Mills,  M.  W.,  inc.,  331 
Mind,  see  Consciousness 
Mind    reading,     covert     behavior, 

48f. 
Mind-body  theories,  7f. 
Minnesota   midtiphasic  in\entory, 

494f. 
Mittelmann,  B.,  bk.,  545 
Mixture,  color,  278-83 
Mobs,  597f. 
Mode,  261-3 
MoUer,  J.  B.,  ref.,  421 
Moncrieff,  R.  AV.,  bk.,  359 
Monism,  8 

Montague,  M.  F.  A.,  bk.,  613 
Moon  illusion,   15f. 
Moore,  J.  S.,  bk.,  18 
Morale,    industry,   465,    472,   482f. 
Mores,  590 
Morgan,  C.  T.,  auth.,  19-63;  bk., 

63;   ref.,  25,  32,  36,   100 
Morgensen,  A.  G.,  ref.,  471 
Morgulis,  S..  ref.,  139 
Moron,  426 
Motion  study,  470-2 
Motivation,  adjustment,  512r. 
attention,  220 
behavior,   4,5-9 
competition,   149 
culture,  124f. 


Motivation  {continued) 

derived   needs,   121f. 

drives,   115-8 

food,   119-21 

forgetting,   175 

hunger,  115f. 

imagination,  129-32 

incentives,  123f. 

individual  differences,  134-6 

learning.  146,  148f.,  159-61,  165, 
181 

measurement,  126-9 

needs,   47,    112-4,    121-36 

perception,  129-34 

physiology,  114-21 

piaise,  149 

prejudice,  607-9 

recollection,  191-3 

reproof,  149 

retention,   171 

sensitivity,    132-4 

sex,  116-8 

study,   181 

tension,  512f. 

thinking,  208,  213 

tolerance,  61  If. 

wishful  thinking,  207,  213 

See  also  Needs 
Motor  reaction,  60f. 
Movement,  apparent,  310f. 

autokinetic,  239,  566 

clue  to  space.  299 

discrete  stimulation,  310f. 

moving  stimulus,  309f. 

perceived  rate,  309f. 

perception,  239-41 

pressure,  364 

relativity,  307f. 

stroboscopic,  31  Of. 

suggested,  311 

visual,  307-11 

\isual  afterimages,  308f. 
Muenzinger,  K.  F.,  bk.,  136 
MiiLLER,     Johannes     (1801-1858), 

sense  ph)siology,  8 
Multiphasic      personality      inven- 
tory, 494f. 
Mundagumor,  personality,  504f. 
Munn,  N.  L.,  bk.,  89 
Murphy,  G.,  bk.,  18,  510,  588 
Murphy,  L.  B.,  bk.,  510,  588 
Murray,  H.  A.,  bk.,  137,  510;  ref.. 

497 
Muscle,  contraction,  22 

effector,  21  f. 

scnsibililv,  370-2 


Muscle  {continued) 

smooth,  22 

spindles,  372 

striped,  22 
Muscle  reading,  48f. 
Muscular  tension,  efficiency,  463f. 
Music,  intervals.  345 

tones,  320f.,  344f. 

Nafe,  J.  P.,  bk.,  379 

Nagel,  E.,  bk.,  17 

Napoleon  Bonaparte,  inc.,  131 

Nash,  H.  B.,  ref.,  452 

National   differences.  432f. 

National  loyalty.  570 

Nature  vs.  nurture,  see  Heredity 

vs.  environment 
Needs,  activity,  47 

aspiration,  136 

biological,    113f. 

culture.   124f. 

definition.  114,  126 

derived,  113f.,  121f.,  148f. 

ego,  135f. 

environment,   114 

himger,    115f. 

imagination,    129-32 

incentives,   116,   123f. 

individual  differences,  134-6 

lacks,   114 

learning  method,   128f. 

measurement,  126-9 

nature,   112-4 

obstruction  method,  126-8 

particular  foods,  119-21 

perception,   129-32 

persistence,  133f. 

personality,   134-6 

physiological,  113f. 

primary,  113-8 

recollection,   191-3 

relation    to   environment,    122-5 

relation  to  structure,  114 

secondary.   113f..  121f. 

sensitivity,   132f. 

sex,  116-8,  529f. 

situation,  116,  122-5 

social,   113f.,  134-6 

testimony,   189 

vital,  112-1 

See   also   Attitudes,   Moti\ation 
.Set 
Negative  afterimages,  color,  281 
Negative  transfer,  177,  180f. 
Negroes,  caste,  602f. 


Index 


625 


Neonate,   niatiitalioii,  71-7 

sensation.  7()r. 
Nerve  concliKtioii,  rale.  K 
Nervous  system,  adjtislors,   21,  26 

autonomic.  SH,  9-1— 6 

brain,  33-8 

central,  26 

cerebellum,  33 

cerebrum,  34 

effectors,  21-4 

efferent.  34f. 

hypotlialamiis,  34 

integration,  66-8 

intensity,   30 

medulla,  33 

neurons,  26-32 

pain,  367 

peripheral,  26f.,  34f. 

personality,  502f. 

pons.  33 

receptors,  21,  25f. 

recruitment,  32 

reflex,  42f.,  51  f. 

reverberation,  32 

spinal  cord,  33 

structure,  32-5 

synapses,  31f. 

thalamus,  34 

^'olley  principle,  336 

See    also    Brain,    Neurons,    Re- 
sponse  mechanlsin 
Nervousness,  532f. 
Neural  types,  growth,  73 
Neurohumoral  system,  35 
Neurons,  afferent,  26f. 

all-or-none  law,  28-30 

conduction,  28-30 

efferent,  26f. 

electrical   polarization,  29f. 

intensity,  30 

refractory  period,  28-30 

reverberation,  32 

stimulation,  27-30 

structure,  27 

supernormal   period.  30 

synapses,  31  f. 
Neurosis,     see     Adjustment.     Psy- 

choneurosis 
Newcomb,  T.,  bk..  510.  588 
Newman,    E.    B.,    auth.,    215-49, 

313-50 
Newman,  H.  H..  bk.,  457 
Newman,  J.,  bk.,  213 
Newton,  Isaac  (1642-1727),  color 
mixture,  279 

spectrum,  275 


Night  vision,  290-H,  291f. 
Nimkoff,  M.  I.,  ref.,  572 
Noise,  efficiency,  477f. 

hearing,  315,  319 
Noll,  A.,  inc.,  284 
Nominal  scale.  258 
Normal    dislribulion,   262-6,    HSI. 
Norms,  social,  560-2 

tests,  394f.,  414 
Novelty,  attention.  219 
Number  forms.  196 
Nurture,  see  Environment,  Hered- 
ity vs.  environment 

Objects,  meaning,  230f. 
perception,  220,  224-37 

Observer,  definition,   17 

Obsessions,  534f. 

Obstruction  method,  needs,  126-8 

Occupations,  classification,  552f. 

Oden,  M.  H.,  bk.,  434 

Odor,  see  Smell 

Ogburn,    W.    F..    social    change. 
571f.;  ref.,  572 

Ogive,      psychometric      function, 
264-6 

Old  age,  86f. 

Olfactometer,  357 

Opinions,  measurement,  577-88 
See      also      Attitudes,      Polling, 
Propaganda,    Public    opinion 

Ordinal  scale,  258 

Organic  psychoses,  536 

Organic  sensibility,  nature,  372 
See  also  Appetite,  Equilibrium. 
Hunger,  Kinesthesis,  Proprio- 
ception.  Thirst 

Orientation,       see       Equilibrium. 
Topographical   orientation 

Ossicles,  ear.  329f. 

Otis,  A.  S..  test,  405 

Outgroup,  599 

Output,  see  Efficiency 

Ova,  437f. 

Oval  window,  ear,  329f. 

Overlearning,   164f. 

Overprotection,  parental,  529 

Overtones,  319 

Pacinian     corpuscles,     subcutane- 
ous, 361,  372 
Pain,  adaptation.  366f. 

ner\e   fibers,  367 

nerve  paths,  367 

receptors,  367 

sensibilitv.  366 


I'ain  (conlinued) 
.sfKds.  366 
sliiiMilus,  ,366 
Painter,  T.  .S.,  ref.,  4.19 
Pancreatic  gland,  24 
Pape/,  J.  VV..  bk..  39 
Paradoxical   told.  369f. 
I'.irallclism.   7f. 
I'arasympalhelic    nervous    system, 

35,  94  f. 
Parathyroid    glands,    personality, 

500 
Parent-child   relation.   5421. 
Parker.  G.   H.,   bk.,  39,  359;   ref., 

21:   inc.,  25 
Parsons,  J.  H.,  bk..  296 
Part    learning,    157f. 
Participation,  learning,   159-61 

study.    183f. 
Paterson,    D.    C.    test,   406f.,   455; 

bk..  434:  ref.,  73 
Pa\lov.    Ivan    Petrovich    n849- 
1936),       conditioning,       139f., 
142f. 
Penrose.  L.  S.,  bk..  434 
Perception,      ambiguous      figures, 
220    227 

anchoring.  238f. 

animal.  225 

attention.  218-20 

attribute.  252-5 

community,  222f. 

constancies.  231-7 

continuity.  222 

contour.   229 

definition,   216f. 

facial  yision.  384-6 

figure-ground,  224—8 

frame  of  reference.  238f. 

hallucinations.    216f. 

illusions.  216 

imagination.    196f. 

integration  of  senses.  229.  240 

intention,  220 

inverted    field,    241  f. 

learning.  241f. 

meaning.  230f. 

microstructure.  226.  229 

moxement.  223.  239-41 

nature.  215f..  224 

noveltv.  219 

objects.  220,  224-37 

organization.  220-4.  224-37 

proximity.  221 

pseudophone.  241 

recollection.  ISSf. 


626 


lnde> 


Perception  {continued) 
relativity,  218,  238-tO 
repetition,  219f. 
rhythm,  246f. 
rotation,  376-8 
satiation,  228 

selection,  218-20 

sensation,  250f. 

shape,  225f.,  233 

short  intervals,  245f. 

similarity.  221 

size,  253 

size  constancy.  231-1.  236f. 

space.  237-42 

speech,  347-9 

stimulus.   215.   2l7f. 

stimulus  intensity,  219 

symmetry,  221f. 

t:iu  effect,  223f. 

time,  242-9 

vibration,    364 

whiteness  constancy,  234-7 

fiee   also    Movement,   Sensation. 
Space   perception.  Time.  \'is- 
ual   space  perception 
Performance  tests,  406f..  555 
Peripheral      vision,      blind      spot. 
287f.,  294 

color  zones,   286f. 
Persistence,  needs,  133f. 
Personal   equation,  58 
Personality,  adjustment,  511—15 

adolescence,  507-9 

biological   factors,  499-503 

body  chemistry,  500f. 

childhood.   5061. 

cultural    factors.   503-5 

definitions.  487f. 

development.  505-9 

diagnosis.  492 

cndocrines,  500f. 

expression  in  family,  590 

health,  501f. 

infancy,  505f. 

interview,  492 

in\entory,  493f. 

mature,  509 

measurement,   491-7 

needs,  134-6 

nervous  system.  502f. 

origin  of  term.  4S7f. 

origins,  497-9 

physique,  501  f. 

projective  methods,  49.5-7 

questionnaire.  493f. 
rating.  492f. 


Personality  (conlinued) 
Rorschach  test,  495t. 
security,  506f. 
tests,  413-7,  494f. 
Thematic     Apperception     Test 

496f. 
traits,  489-91 
tvpes.  488f. 
vocations,  558 

See  also  Adjustment.  Traits 
Perspective,  visual  space.  298f. 
I'etermann.  B.,  bk..  18 
IMalfmann,  C,  auth.,  351-9;   ref., 

352 
Phobias,  conditioned.  143f. 
emotion.    109 
psychoneurosis,  533f. 
Phototropism,  42 
Physiological  limits,  learning,  152 
Physiological  psychology,  8,  12 
Physiological   zero,  369 
Physiology,   psychology,   8 
Piano  scale,  321 
Pigments,  mixture,  281 
Pintner,  R.,  test,  406f.,  455 
Pitch,  cochlea,  334-6 
discrimination,  266f. 
frequency.  321 
place  theory,  334-6 
scale,  322f. 
thresholds,  321  f. 
tones,  320-3 
Pituitary  gland,  growth,  65 
hormones,  24 
personality,  500f. 
Plantar  reflex,  75 
Plateaus,  learning,  151f. 
Pleasantness    and    unpleasantness, 
90-3 
See  also  Feeling 
Poffenberger,  A.  T.,  bk.,  486 
Polling,  accuracy,  579f. 
analysis  of  results,  584-6 
definitions,  577f. 
filter  questions,  583 
free-answer  questions,  583 
Gallup  poll.  580-3 
intensity   questions.   584 
open-ended  questions,  583 
pretesting,  587 
probing  questions.  583 
problems.  580.  583f. 
(luestions.  580-4 
sampling.  578f. 
techniques,  586-8 
trend  questions.  584 


Polyak,  S.   L.,  bk..  350;    ref.,  293 
Pomeroy,  W.  B.,  bk.,  136 
Pons.  33 

Positive   afterimages,  color,  284f. 
Positive   transfer,   177f.,   180f. 
Posthypnotic    suggestion,    behav- 
ior, 57 
retention,  175 
Postman,  L.  J.,  bk.,  213 
Practice,  learning.  149-54.  156f. 
massed     or     distributed,     1.56f., 
164 
Praise,  molivalion.   149 
Predictions,  experimenlal.   15f. 
Prefrontal    lobotomy.   537f. 
Prejudice,  attitudes,  566f. 
displaced  aggression,  609 
economic.  607 f. 
ego  involvement,  568f. 
elimination,    612f. 
family,  .590 
foreigners,  605-8 
hostility,  607-9 
individual    differences,  61  If. 
Jewish,  605.  608f. 
loyalty,  569f. 
motivation.  607-9 
nature,  603f. 
Negro.  602-5,  610 
origins,  604-7 
propaganda.  573-7 
rationalizations.  609-11 
scapegoating.  609 
status,  607f. 
stereotypes.  563 
suggestion,  564 
Prenatal   growth,  68-72 
Prenatal    influence,   heredity,   410 
Preschool  intelligence.  408 
Present,  perceived.  243-5 
Pressme,   adaptation.   364f. 
localization.  365 
receptors.  362f.,   365f. 
sensitivity,  362f. 
spots,  362f..  365f. 
siimulus.  363 
vibration  sense.  364 
Prestige,  suggestion,  564.  566f. 
Primacy,  learning.  163 
Primary  needs.   113-8 
Primitive     cultures,     personality 

503-5 
Probable  error.  263 
Problem  solving,  behavior,  47f. 
insight,    1,52^.  20.3-6 
thought.  203-13 


Index 


627 


I'loblem  solving  (continued) 

See.   also  AdjustmoiU 
I'rocligics,  cliild,  -127 
I'rojcclion,  521 
Projective  methods,  495-7 
Pro|jaganda,    Americanisin,    5761. 

association,  5731'. 

definition,  57.S 

distortion,  575 

goals,  573,  576f. 

leceptivily,  575f. 

social  bias,  576f. 

suggestion,  593 

techniques,  575-5 

See  also  Suggestion 
Proprioception,  26 

See    also    Eciuilibriuin,     Kines- 
thesis.  Organic  sensibility 
I'rotanopia,  289 
Proximal  stimulus,  16 
Proximity,  perception,  221 
Pseudophone,  241 
Pseudoscopy,  303f. 
Psychoanalysis,   emotion,   107 

therapy,  541  f. 
Psychogalvanic  reflex,  106 
Psychographs,  411 
Psychological  mechanisms,  516-22 
Psychology,  abnormal,  12 

American,  lOf. 

animal,  10 

behaviorism,   lOf. 

British.  7 

child,  12 

clinical,  12f. 

comparative,  12 

dynamic,  12 

educational,  12 

fields,  12f. 

functional,   I  Of. 

general,  12 

German,  8-11 

Gestalt,  lOf. 

history,  7-9 

individual  differences,  12 

industrial,  12 

introspective,  9 

modern,  11 

nature,   1-18 

physiological,  8,   12 

schools,  9-11 

social,  13 
Psychometric  function,  264-6 
Psychoneurosis,     ailment     adjust- 
ment, 535 

anxiety,  531-3 


Psychoncuiosis  (continued) 

(ompulsion,  5341. 

definition,  531 

emotional    disorder,    109 

experimental,  527 

hysteria,  535 

obsession,  5341. 

phobias,  533f. 

See  also   Adjustment 
Psychophysics,       intervals,      2561., 
259t. 

methods,  256f. 

nature,    255-7 

problems,  256f. 

ratios,  257,  260f. 

thresholds,   256,   263-7 

Weber  fractions,  267f. 

See  also   Measurement 
Psychoses,  character,  535f. 

functional,  536f. 

manic-depressive,  536f. 

organic,  536 

prefrontal  lobotomy,  537f. 

schizophrenia,  536-8 

shock   therapy,  537f. 
Psychosomatic      medicine,      func- 
tional disorders,  109f. 
Psychosomatic  symptoms,  anxiety, 

532f. 
Psychotherapy,  counseling,  539—11 

psychoanalysis,   541 

techniques,  538^2 
Puberty,   maturation,   83f. 
Public     opinion,      American      in 
1939-1941,  585 

economic  status,  586 

See  also  Polling 
Punishment,  breaking  habits.  177 

learning.  92f. 
Pure  strains,  heredity,  441 
Purkinje.   J.    E.,   brightness   shift, 

291 
Purkinje  phenomenon,  291 
Puzzle  box,  145f. 
Pyknic  type,  423f. 

Quality,  attribute,  252,  254 

unique,  254 
Questionnaire,   personality.  493f. 

polling.  580-8 

Race,  differences,  431-3 
Rand,  G.,  ref.,  477f. 
Random  noise,  315 
Rating   scales,   efficiency,   460 
emotion,   107 


Ratings,  personality,  414,  4921. 
Ratio   scalers,    psychophysics,   260f. 
Rationalization,  arljustmcnl,  5IHf. 

prejudice,    609-11 
Reaction,  association,  61f. 

astnjnomy,  58 

choice,   61 

discrimination,  61 

flistraction,  60 

experiment,  5H-62 

guilt,  62 

individual    flillerences,    62 

motor,  60f. 

jjersonal  equation,  58 

rcadine.ss,   49,  59-61 

sensory,  60f. 

simple,   59-61 

stimulus  intensity,  60 

suppressed   complexes,   62 

times,  57-62 

word,  61f. 
Reading,  eye  movements,  182 

habits,   182f. 

meaning,  201  f. 

psychology,  201f. 

regression,  182 

speed,   182f. 

visual,  201  f. 
Recall,   memory   method,    168 
Recency,  learning,  163 
Receptors,  cutaneous.  360-2,  365- 
7,  370 

equilibrium,  375,  377f. 

kinesthesis,  372 

maturation,  76f. 

nervous  system,  21.  25f. 

pain,  367 

pressure,  362f..  365f. 

temperature.  370 
Recessive  characters,  heredity,  440f. 
Recitation,  learning.  I60f. 

retention,    171 
Recognition,  memory  method,  168 
Recollection,    change    with    time, 
190-3 

eidetic.  187f. 

errors.   192f. 

exceptional.  186-8 

failures.  193f. 

image  types.  194f. 

meaning.  191-3 

nature,  185-7 

perception,  lS8f. 

reliability,  189-94 

testimony,  189f. 

Scr  also  Retention 


628 


Index 


Reconditioning,  see  Unlearning 
Reconstruction,   memory  mctiiod, 

168f. 
Recruitment,  neural,  32 
Recurrent  nervous  circuit,  32 
Reduction,   perception,  235 
Reduction  division,  heredity,  '137f. 
Reflex,  arc,  42f. 

Babinski,  75 

circle,  45 

grasping.  75 

plantar,  75 

response,  41-3,  51C. 
Refractory   period,  neuron.  28-30 
Regression,  frustration,  521f. 
Reinforcement,  learning.  142,   147 
Rejection,  family,  528,  542f. 
Relearning,  memory  method,   168 
Reliability,  statistics,  395,  401,  414 
Reminiscence,  172 
Repetition,  attention,  219f. 

experimental,  14 
Repression,   193f.,  520f.,  533-5 
Reproduction,  heredity,  437-9 

memory  method,  168 
Reproof,  motivation,   149 
Resonance,  acoustic,   317f. 

electrical,  318 
Response,  circular,  44 

conditioned,  43-5,  51f.,  139-44 

definition,   16 

empathy.  54f. 

instinct,   45f. 

neonate.  75-7 

prenatal.  69-71 

reaction,  49,  57-62 

reflex,  41-3 

reflex  circle,  44 

set,  49 

suggestion.  54-7 

tropisms,  4 If. 

iniconditioned,  139-44 

varieties,  40-53 

voluntary.   45f.,  50-3 

See  also  Behavior,  Conditioned 
response.  Reaction 
Response   mechanism,  autonomic. 
94-fi 

differentiation,  20-6 

elleclors,  21-t 

evolution,  21 

fimction,   19f. 

nervous  system,    19-39 

receptors,  21,  25f. 

stimulation.  20f. 

Srr  also   \cr\ous  svstcni 


Rest,  periods,  479f. 

work,  478-80 
Retention,     change     with      time, 
190-3 

changed  environment,  174 

changed  set,   175f. 

distributed  practice,  171 

cidetic,  187f. 

exceptional,  169,  186-8 

feeling  tone,  170 

forgetting,  172-5,  193f. 

forgetting  curve,  167 

individual  differences.  169 

kinds  of  material,  169-71 

length  of  material,  170 

massed  practice,  171 

meaning,   169f. 

measurement,  168f. 

memory  types,  194f. 

motivation,  171 

original  learning,  171 

recall,  168f. 

recitation,  171 

recognition,   168 

reconstruction,    168f. 

reminiscence,  172 

repression,   170f. 

reproduction,    168f. 

retroacti\e  inhibition,  173f. 

saving,   168 

sleep,  173 

wishfid   forgetting,   175 

See  also  Learning,  Recollection, 
Unlearning 
Retina,  cones,  292-5 

duplexity,  294f. 

rods,  292-5 
Retinal  disparity,  301-4 
Retroactive  inhibition.  173f. 
Reverberation,   neuron,   32 
Re\ersible  figures.  220.  227 
Reward,  breaking  habits,  177 

intensity,  147 

learning,   92f.,   146 

needs,  128f. 
Rheotropism,  42 
Rhythm,  music.  344 

perceived.  246f. 

physiological,  247-9 
Richter,  C.  P..  inc.,  355 
Rivalry,  motivation,  149 

sibling.  528 
Robinson,  E.  E.,  bk.,  62 
Robinson,  E.  S.,  ref.,  170 
Rods,  292-5 
Rocthlisl)Cigcr,  F.   }.,  hk.,  486 


Rogers,  C.   R..  bk.,  545:   ref.,  533 
Roischach,  H.,  lest,  495f. 

bk.,  510 
Rorschach  test,  495f. 
Rosenblueth,  A.,  bk.,  38 
Rotation,  adaptation,  378 

habituation,  378 

perception,  376-8 

See  also  Equilibrium 
Rote  learning,  156 
Roimd  window,  ear,  329f. 
Ruch,  T.  C,  bk.,  379 
Ruckmick,  C.  A.,  bk.,  Ill 
Ruffini  endings,  skin,  361,  370 
Rural   influence,  abilities,   463  -5 
Ryan,  T.  A.,  auth.,  185-214,  459- 
86;  bk.,  486 

Saccule,  ear,  374-8 
Sacral  autonomic  system,  35 
Salter,  P.  J.,  ref.,  577 
Samoa,  adolescence,  508 
Sample,  area,  578 

polling,  578f. 

quota,  578 
Sampling,  statistics,  427-30 
Satiation,  perception,  228 
Saturation,  color,  274,  277 
Saving,  memory  method,  168 
Scala  tympani,  ear,  331f. 
Scala  vestibuli,  ear,  331f. 
Scales,  loudness,  324-6 

measmement,  257-61 

pitch,  322f. 

weight,  260f. 
Scammon,  R.  E.,  bk.,  89;  ref..  73 
Scapegoating.  gossip,  611 

nature,  609 
Scatter  diagrams,  correlation,  397- 

401 
Schanck,  R.  L.,  bk.,  613 
Scheinfeld,  A.,  bk.,  434 
Schiller,  B.,  ref.,  429 
Schizoid  type,  489-91 
Schizophrenia,  536-8 
Schmidt,  H.  O..  ref.,  495 
Schneck.  M.  M.  R..  bk.,  434 
Schneirla.  T.  C,  bk.,  62;   ref.,  42 
Schools.  beha\iorism.  lOf. 

functional.  lOf. 

Gestalt,  lOf. 

introspection,  9 

modern,   11 

psychology,  9-1 1 
Schwesinger,  G.  C.  bk.,  457 
Scientific  method.  13-6 


Inde 


629 


Scolopk:  vision,  290-2,  291f. 
Seclusivencss,  5191'. 
Security,  personality,  50(5f. 
Si  lection,  vocational,  .')'16-59 

See  also  Vocational  selection 
Selective  breeding,  443-5 
Semantics,  207f.,  595r. 
Semicircular       canals,       function, 
374-8 
structure,  331,  374-8 
See  also  Ecjuililiriurn 
Senescence,  86f. 
Sensation,  attributes,  252-5 
|)erception,  250f. 
stimulus,  2771'. 
unique,  270,  276 
See  also  Color,  Cutaneous  sensi- 
bility.  Equilibrium,   Hearing, 
Movement,    Organic    sensibil- 
ity.   Pain,    Perception,    Pres- 
sure, Smell,  Taste,  Tempera- 
ture sensibility.  Time,  Visual 
space  perception 
Sensitivity,  needs,  132f. 
See  also  Thresholds 
Sensory  reaction,  60f. 
Serial  learning,   161-3 
Sesshu,  inc.,  234 
Set,  attention,  220 
reaction,  49,  59-61 
recollection,   191-3 
retention,    175f. 
thought,   202f.,  208-12 
See  also  Attitudes,  Needs 
.Sex,  adjustment,  529f. 
adolescence,  507-9 
cycles,  116-8 
derived  need,  118 
differences,  430f. 
drive,  116-8 
hormones,  116-8 
learning,  154 
maturation,  83f. 
See  also  Gonads 
Shaffer.  L.  F.,  auth.,  487-545;  bk., 

63,  88,  545 
Sham  rage,  77 
Shape  constancy,  236 
Shartle,  C.  L.,  auth.,  546-59:  bk., 

558f. 
Sheldon,  W.  H.,  somatotvpes,  424 

bk.,  434 
Sherif,  M.,  bk.,  137,  588 
Sherrington,  C.  S.,  bk.,  38 
Shock  therapy,  psychoses,  537f. 
Shower,  E.  G..  ref.,  322 


Siblings,   beredily,    l.'i9,  4101. 

rivalry,  528 
Signs,  thinking,   199-201,  207f. 
Similarity,  perception,  221 
Simple  reaction,  59-61 
Sims,  V.  M.,  ref.,  149 
Simultaneous  contrast,  color,  2851. 
Situation,  definition,  16 

needs,   116,  122-5 
Si/e,  clue,  298f. 

constancy,    231-4,    236r. 
perceived,  304-6 
Skills,  learning,   161-5 
Skin,  anatomy,  361 

receptors,  360-2,  365-7,  370 
sensory  spots,  361f. 
temperature,  368f. 
Sleep,  rest,  480 

time  estimation,  247f. 
Smell,  adaptation,  358 
anosmia.  357 
blends,  359 
characteristics,  351-3 
compensation,  359 
fasting,  358 
menstruation,  358 
mixtures,  359 
olfactometer,  357 
pregnancy,  358 
primary  qualities,  356f. 
receptors,  352 
sensitivity,  357 
stimuli,  352f. 
unique  qualities,  254 
Smiling,   103 
Smith,  M.  P.,  ref.,  71 
Snyder,  L.  S.,  bk.,  458 
Social  change,  attitudes.  571  f. 
technology,  571  f. 
See  also  Propaganda 
Social  conflict,  see  Prejudice 
Social  control,  family,  590f. 
Social  facilitation,  596f. 
Social  inhibition,  596f. 
Social  mobility,  602f. 
Social  norms,  acceptance,  562f. 
nature,  560-2 
stereotypes,  563 
suggestion,  563-7 
Social  participation  groups,  601-3 
.Social  psychology,  13 
Social  relations,  assembled  groups, 
596-8 
between  groups,  600-3 
control,  590f. 
crowds,  597f. 


Sotial    iclations   (roritiriutfd) 
dis|jcis<!d  groups,  ,598f. 
fafilitalion,  .596f. 
family,  589-91 
idcniilitalion,  .593f. 
imilalion,  591  f. 
inhibition.  596f. 
language,  594-6 
leadership,  599f. 
mobs,  597f. 
prejudice,  603-13 
primary,  589-96 
suggestion,  593 
whiles  and  Negroes,  602f. 
See  also  Family 
Socio-economic     interest      groups, 

600f. 
Socio-economic     status,     abilities, 

451-3 
Somatotonia,  425 
.Somatotypes,  422-4 
Somesthesis.  definition,  360 
unique  qualities,  254 
weight  scale.  260f. 
See   also    Cutaneous   sensihilitv. 
Equilibrium.  Kinesthesis,  Or- 
ganic  sensibility.    Pain.    Pres- 
sme.  Temperature  sensihilitv 
Sone,  loudness,  325f. 
Soul,  Descartes,  7 
Sound  locator.  339 
Sound  (sensation),  loudness,  323-6 
pitch,  320-3 
tones,  319-27 
See  also  Tones 
Sound  (stimnlusV  amplitude.  318f. 
analysis,  316-9 
beats,  326 

combination  tones,  326 
complex  waves,  316-9 
decibel.  324f. 
Fourier  analvsis,  316-9 
frequency.   318f. 
harmonics.   319 
interaction,  326f. 
masking.  326f. 
noise,  314f.,  319 
periodicitv.  315f.,  318f. 
resonance.  31 7f. 
tone,  315f..  31Sf. 
\\'aves.  314-9 

See  also  Localization  of  sound 
Space  perception,  cutaneous.  365 
echolocation.  387f. 
general   theorv.  237—12 


630 


Index 


Space  perception   (conlinuecl) 

mechanism,  238 

See  also  \'isual  space  perception 
Spectrum,  radiation,  '2.7ri 
Speech,  integration,  31Sf. 

intelligibility,  346-9 

maturation,  82f. 

perception,  348t. 

sound  patterns,  347f. 

sounds,  346f. 

syllables,  348 

vowels,  347f. 
Speed,  efficiency,  466 
Sperms.  437f. 
Spinal  cord,  33 

Spontaneous    recovery,    condition- 
ing, 142,  146 
Siagner,  R„  bk.,  .510 
Standard  deviation,  262t. 
Stanford-Binet  test,  402-4 
Stapes,  ear,  329f. 
Startle  pattern,  emotion,  98f. 
Statistics,  central   tendency,  261-3 

class   interval,   397f. 

correlation.  396-401 

critical  ratio,  428 

distributions,  418-22 

factor  analysis,  41  If. 

histogram,  418 

norms,  394f.,  414 

]3olling,  .578-80 

reliability,  .39.5,  401,  414 

sampling,  427-30,  578f. 

scatter  diagrams.  397-401 

significance  of  difference,  428 

thresholds,  263-7 

validity,  395f.,  401,  414 

variability,  262f. 

See  also  Measurement 
Status,  conflict,  530 
•Stead,  H.  W..  bk.,  5,59 
Steinberg,  J.  C.  ref.,  349 
Slereoscopy,  302-4 
Stereotropism,  42 
Stereotypes,  family,  590 

groups,  598f. 

social  norms,  563 
Stern,  W.,  bk.,  214 
Stevens,  S.  S.,  somatotypes,  424 

auth.,  250-68;  bk..  268.  350,  434; 
ref.,  261.  323,  335 
Stimulus,  acoustic,  251  f. 

adequate,  25 

attributes,  252-5 

chemical,  2.52 

•iclcr.  274-8 


Stimulus  (continued) 

conditioned,   139-43 

definition.  16,  20,  215,  251 

differentiation.  Itlf,,  116 

examples,  20 

generalization,  141,  146 

mechanical,  251 

neuron,  27-30 

photic,  252 

proximal,  16 

sensation,  277f. 

thermal,  251 

unconditioned,  139-43 
Stimulus  object,  definition,   16 
Stirrup,  ear,  329f. 
Sioelting,  C.  H.,  ret.,  407 
Stomach,     hunger     contractions, 

372f. 
Stone,  C.  P.,  ref.,  47 
Stroboscopic  movement,  310f. 
Strughold,  H.,  inc.,  362 
Study,  acti\e  participation.  183f. 

meaning,  183 

memory  systems,  183f. 

motivation.  181 

o\erlearning,  184 

phmning.  181f. 

reading  habits,  182f. 

rules.  181-4 
Subject,  definition,  17 
Sublimation,  522f. 
Submission,  parental,  529 

trait,  489-91,  494 
Subnormality,  425f. 
Substitute  adjustments,  515 
Subtractive  color  mixture,  281 
Successive  contrast,  color,  284f. 
Suggestion,  attitudes,  563-7 

hypnosis,  56f. 

perception.  .55f. 

prejudice.  564 

prestige,  564.  566f. 

response.  54-7 

.socialization,  593 

testimony,  189f. 

See  also  Propaganda 
Smnmation  tones,  326 
Superstition,  207 
Swezy,  O.,  ref..  437 
Svllogism,  reasoning,  210 
Symbols,   thinking,   199-201,  207f. 
Symmetry,  perception.  221  f. 
Sympathetic    nervous    system,    35, 

94-6 
Synapses,  31  f. 
Synesthesia,  196 


Taboos,  590 
Taste,  adaptation,  354f. 

adrenalin,  3.55f. 

cliaracteristics,  351-3 

liedonic  tone.  356 

primary  qualities,  353 

receptors,  352f. 

sensitivity,  353f. 

stimuli,  352f. 

unique  qualities,  251 
Tau  effect,  223f. 
Tea,  efficiency,  482 
Technology,  .social  attitudes,  5711. 
Telestereoscopy,  303 
Temperament,  types,  425 
Temperaline,      body      regulation. 
473f, 

efficiency,  474f.,  484 
Temperatine    sensibility,    ada|ii:i- 
tion,  369 

heat,  369f. 

mapping,  368 

paradoxical   cold,  369f. 

physiological  zero,  369 

receptors,  370 

skin  temperature,  368f. 

spots,  367f. 

stimulus,  368-70 
Tendinous  sensibility,  370-2 
Tension,  motivation,  51 2f. 

needs,  130-2 

persistence,  133f. 
Tkrman,    Lewis    Madison    (1877- 
).  genius,  427 

■sex,  431 

Stanford-Binet  tests,  402f. 

bk.,  434;  ref.,  404.  419 
Ternus,  j.,  inc..  223 
Testimony,  reliability,  189f. 
Tests,  American  Council,  405 

aptitude,  555f. 

Army,  -I0.5f.,  408-10.  420 

Arthur,  406 

Binet,  402-4 

characteristics,  394 

College  Board,  405 

correlation,  396-401 

evaluation,  408-10 

faking,  416 

group,  404-6 

individual,  402-4 

infants,  408 

intelligence.  555f. 

May-Hartshorne,  420f..  431 

nonlanguage,  406f. 

norms,  394f..  414 


Index 


631 


'I'esls  {continued) 

Otis,  iOS 

perlonnaiice,  400f.,  555 

pcisonality,  413-7 

I'intiier-l'aierson,  406f. 

preschool,  408 

recent   use,  408f. 

relial)ility,  395,  401,  414 

standardization,  394 

trade,  553-5 

validity,  395r.,  401,  414 

Sec  also  Individual  difTerences 
riialanuis,  34 

Thematic       Apperception       Test, 
needs.  132 

personality,  496f. 
Therapy,  psychological,  538-42 
Thinking,  wishfid,  130-2 

See  also  Thought 
Thirst,  118,  374 
Thompson.  A.  L.,  bk..  392 
Thompson.  L.,  ref.,  159 
Thorndike,    Edward    Lee    (1874- 
),    animal    intelligence,   9 

belongingness,  155 

law  of  effect,  147 

transfer,  179 

trial -and-error,   144-6,   162 
Thought,  atmosphere,  209f. 

concepts.  198f. 

elaborative,   197f. 

fallacies,  206f. 

faulty,  206-11 

good  thinking,  211-3 

habits,  210f. 

hunches,  207 

individual  differences,  211 

insight,  203-6 

language,  200f.,  207f. 

logic,  197,  210,  213 

methods,  211 

motivation,  207,  208 

nature,  185f.,  197f. 

problem,  202f. 

reaction,  202 

reading,  201f. 

rules  for  thinking,  211-3 

set,  202f.,  208-12 

superstition,  207 

symbols,  199-201,  207f. 

tacit  assumptions,  208f..  212 

tools,  198-200 

trial-and-error.   203-6 

unconscious.  201 

\icarious   trial-and-error.   205f. 

word  fallacies.  207f. 


Ihoulcss,  R.  H..  bk.,  214 
•Jhrcsholds,  absolute,  256,  263-7 

dilfcrential,  256.  263-7 

feeling  (ear),  324 

kinesthetic.  371 

loudness,  324 

pitch,  321f. 

psychometric   function,   264-6 

smell,  357 

taste,  .353f. 

two-|K)int,   365 
I'hutidides,  time  span.  503 
Thwarting,  frustration,  511-35 
Thyroid  gland,  gtoulh,  65 

hormone.  24 

personality,  500 
Thyroxin.  24 

Tiffin,  J.,  bk.,  486,  ,5.59;   ref.,    16!) 
Time,  clues,  248r. 

dating,  244 

estimation,  245-9 

filled  and  empty,  245f. 

frame  of  reference,  242 

indifference  point,  245 

orientation,  247-9 

patterns,  245-7 

perception,  242-9 

present,  243-5 

rhythm,  246f. 

thresholds,  245 
Time  and  motion  study,  470-2 
Tint,  color,  274,  276f. 
TiTCHENER,      Edward      Bradford 
(1867-1927),   introspectionism, 
9 
Tobacco,  effects,  481  f. 
Tolerance,  frustration.  134 

See  also   Prejudice 
Tolman,  E.  C,  ref.,  148 
Tomkins,  S.  S.,  bk.,  63,  510 
Tones,  beats,  326 

combination,  326 

difference.  326 

do-re-mi,  320f. 

loudness.  323-6 

masking,  326f. 

music,  320f. 

pitch,  320-3 

quality,  320f. 

sensation,  319 

summation.  326 

See      also      Soimd      (sensationV 
Sound  (stimulus") 
Topectomv.  538 

Topographical    orientation,    bats, 
386-8 


I  oj>ographical    orientation    (con- 
tinued) 

blind,  384-6 

clues,  381-92 

development,  383 

errors,  381-3 

homing,  389 

mental   maps,  380-4 

migration,  38&-92 

schema,  380-1 
Totipotency,  86 
Trade   tests,  553-5 
Traits,  character,  414 

dominance,  489-91,  494,  498 

list,  491 

names,  490 

organization,  4l2f. 

personality,  489-91 

submission,   489-91,  494 

\ariability,  410f. 
Trajectory  of  life,  87f. 
Transfer  of  training,  see  Learning 
Trial-and-error,  adjustment,  513f. 

learning.  144-8 

thought.  203-6 

\icarious,  205f. 
Trichromatic  coordinates.  282f. 
Tri-stimulus  values,  colors,  2S2f. 
Troland,  L.  T.,  bk.,  268,  296:  ref.. 

292,  475 
Tropism.  41  f. 
Tryon,  R.  C,  ref.,  444f. 
Tucker,  W.  B.,  bk.,  434 
Twins,  heredity,  439,  446f.,  450 

maturation.  80f. 
Two-point  threshold,  skin,  365 
Tyler,  L.  E..  bk..  434 
Tvpes.   constitutional,   422-5,   502 

individual  differences.  421  f. 

personalitv.  488f. 

Unconscious   acts,   50-3 
Unconscious  adjustment.  516 
I'nconsciousness.  nature.  5-7.  10 
L'nique  colors.  270,  276 
L'nit  characters,  438f. 
Unlearning,  breaking  habits,  176f. 

fears.  175f. 

reconditioning.  176 
Urban   influences,  abilities.  453-5 
Utricle,  ear.  374-8 

\'alences.  field  theorv.  523-31 
Vahditv.  statistics,  395f..  401.  414 
\"alue,  color.  274.  276f. 
Variation,  experimental,  IS 


632 


Index 


X'cctois.  field  theory,  523-31 
\eg  scale.  260f. 
X'erbal  reactions,  61  f. 
Verbalization,  learning,   1581. 
Verbatim  learning,  156 
Vernon,  H.  M.,  bk.,  486;  ref.,  174. 

•179 
Vernon,  M.  D.,  bk.,  312 
Vernon,  P.  E.,  values,  431 
Vibration,  perception,  364 
Vicarious  trial-andcrror,  205f. 
Vigouroiix,    R..   galvanic   skin    re- 
sponse.  106 
\'is(eral  response,  autonomic.  94-6 
X'isceral     .sensibility,    sec    Organic 

sensibility 
Viscerotonia,  425 
Vision,  see  Color,  Eye.  Perception, 

\isiial  space  perception 
Visual  amity.  306f. 
\'isual  purple.  295 
X'isiial  sensation,  blind  spot.  2871., 
294 

indirect.  286f. 

iniitpie  qualities.  254 

See  also  Color 
\'isiial    space    perception,    accom- 
modation, 300f. 

acuity,  306f. 

assimilation.  305 

binocular    parallax.   301-3 

characteristics,  2971. 

contrast,  305 

convergence.  3001. 

distance.  3041. 

illusions.  304f. 

implicit   clues.  298-300 

inverted  field.  2411. 

motor  context.  300f. 

movement.  307-1 1 

pscudosropy.  303f. 

retinal  disparity.  301-1 

size.  304-6 

size  constancy.  231-1,  236f. 

solidity,  226 

stereoscopy.  302— t 

third  dimension.  298-304 

See  also  Movement 
Vital  needs,  112-4 
Viteles.  M.  .S..  bk..  486.  559 
Vocational      selection,      accidcnis, 
548 

aptitude,  555f. 

attendance,  548 

(■ooperalion,  548 


\ocaiional  selection  [continued) 

employer  evaluation,  549 

errors,  548 

intelligence,  5561. 

interests,  5571. 

job  analysis,  551-3 

occupations,  5521. 

performance  tests,  555 

personality,  558 

potentiality,  555-8 

])rinciples,  546f. 

productivity.  547 

rating  form.  550 

salary.  ,548 

.self-evaluation,  549 

social  values,  548 

success  criteria,  547-51 

supervision,  548 

tasks,  549 

tenure,  548 

trade  tests.  553-5 

worker  analysis.  553-8 
X'olkmann.  J.,  ref..  .323 
\'olley  principle,  hearing.  336 
X'oluntary  action,  50-3 
X'owels,  characteristics,  347f. 

Walking,  maturation.  78 

Wallen,  J.  L.,  bk.,  545;  ref.,  539 

Waller.  A.  D..  ref.,  462 

AVallingford,  D.  K.,  inc.,  382 

Walter,  A.  A.,  ref.,  192 

Ward,  L.  B.,  ref.,  173 

Warden,  C.  J.,  bk.,  136.  392:  ref., 

127,  162 
Warmth,   see   Temperature   sensi- 
bility 
W^arner,  L.  H.,  bk.,  392.  613;  ref., 

127,  603 
Warthin,  A.  S.,  bk..  89 
\V.vrsoN,    John     Broadus     (1878- 
),  behaviorism,  10 

emotion,  lOlf.,  143 

bk.,   18,  392;  ref..  75 
Watts,  J.  W.,  bk.,  38 
Wave  length,  light,  275-7 
Webb,  L.  W.,  ref.,  178 
Weber,    Ernst    Heinrich     (1795- 

1878),  Weber's  law,  8 
Weber  fractions,  267f. 
AVeber  functions,  267f. 
Weber's  law,  8,  267f. 
Wcddell.  G.,  ref.,  .361 
AVegel,  R.  L.,  ref..  327 
AVeigbt  scale,  \egs,  260f. 


Weisenburg,  T.,  bk.,  39 
Wellman,  B.  L.,  bk.,  435 
Wertheimer,     Max      (1880-1943), 
Gestalt  psychology,  11 

thinking.  210f. 

bk.,  214;  inc.,  223 
\V'hite  noise,  315 
Whitely,  P.  L.,  ref.,  170 
Whiteness    constancy,    234-7 
Whole  learning,  157f.,  164 
Will.  50-3 

Willoughby,  R.  R.,  ref..  154 
Windle,  W.  F.,  bk.,  89 
AVingfield,  A.  N.,  ref.,  446 
Wishful  thinking.  130-2,  207,  213 
Wolle,  J.  B..  ref..  147 
Wood,  A.,  bk.,  350 
Wood,  A.  B.,  bk..  350 
XVooDWORTH,      Robert      .Sessions 
(1869-        ).  bk..   18.  63,  214. 
249.  312,  458.  493:  ref.,  493 
Woolard.  H.  H..  ref.,  361 
Word,  fallacies.  207f. 

magic,  208 

maturation.  82f. 

reactions.  61  f. 
Work,  climate,  472 

decrement,  466f. 

environment,  472-8 

hours,  478 

illumination,  475-7 

motion  study,  470-2 

natural  method,  467-71 

noise,  477f. 

one  best  way,  467-9 

oxygen.  472f. 

respiration,  472f. 

rest,  478-80 

speed.  478 

temperature.  473-5,  484 

time  study,  470-2 

weather.  472^ 

See  also  Efficiency 
Worker  analysis,  553-8 

WUNDT,        WiLHELM        (1832-1920). 

experimental  psychology,  8 

Verkes,    Robert    Mearns    (1876- 

),  ref.,  81,  139 
Young,   P.   T..  bk.,  63,   136;   ref.. 
Ill;  inc.,  241 

/ilboorg.   G.,   bk..   18 

ZWAARDEMAKr.R,      HENfJRIK       (1857- 

1930),  inc.,  357f. 


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