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THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

LOS  ANGELES 


T1  '     book  is  DUE  on  the  last  date  stamped  below 


SOUTHERN    BRANCH 

JNIVERSITY  OF  CALIFORNIA 
LIBRARY 

LOS  ANGELES.  CALIF. 


PSYCHOLOGY 


GENERAL   INTRODUCTION 


BY 


CHARLES  HUBBARD  JUDD 

PROFESSOR   OF   EDUCATION  AND   DIRECTOR   OF  THE 
SCHOOL   OF   EDUCATION    OF  THE    UNIVERSITY   OF   CHICAGO 


SECOND  COMPLETELY  REVISED  EDITION 


GINN  AND  COMPANY 

BOSTON  •  NEW  YORK  •  CHICAGO  •  LONDON 
ATLANTA  •  DALLAS  •  COLUMBUS  •  SAN  FRANCISCO 


i.KS  SOUHNEK'S  SONS 
AU 


fflt>tn«nm 


GINN  AMJ  COMPANY  •  PRO- 
PRIETORS •  BOSTON  •  U.S.A. 


Library 

13  I 
88p 


PREFACE  TO  THE  SECOND  EDITION 

This  revised  edition  has  been  very  largely  rewritten.  The 
emphasis  which  was  laid  on  motor  processes  in  the  volume 
when  it  appeared  in  1907  has  been  more  than  justified  by 
recent  developments  of  "behaviorism"  in  psychology.  The 
present  edition  goes  further  than  did  the  first  in  working  out 
the  doctrines  of  functional  psychology,  especially  in  so  far  as 
these  use  motor  processes  in  explaining  mental  organization. 

The  doctrine  of  attitudes  which  was  presented  in  the 
first  edition  has  been  much  expanded. 

The  applications  of  psychology  have  been  elaborated, 
especially  through  a  new  chapter  on  mental  hygiene. 

The  view  with  regard  to  the  importance  of  consciousness 
in  evolution  which  was  set  forth  in  my  paper  before  the  Amer- 
ican Psychological  Association  in  1909  has  been  adopted  as 
a  guiding  principle  in  this  volume.  In  keeping  with  this 
view,  the  chapter  on  volition  has  been  wholly  rewritten,  and 
several  earlier  sections  have  been  largely  worked  over. 

Perhaps  the  simplest  method  of  economizing  the  time 
of  those  who  are  interested  merely  in  the  new  parts  will 
be  to  enumerate  the  chapters  which,  are  not  greatly  modi- 
fied. These  are  Chapters  I,  II,  III,  V,  VIII,  IX,  X,  XI, 
XIV,  and  XVII.  The  remainder  of  the  volume  includes 
liberal  revisions.  Chapters  IV,  VI,  VII,  XII,  XV,  and 
XVI  are  new  or  very  largely  so.  The  book  has  been  freed 
so  far  as  possible  from  technical  controversial  discussions, 
with  the  result  that  some  chapters,  notably  Chapter  XIII, 
have  been  reduced. 


iv  P.sYt   1 1<  •  !.»  '( .Y 

Many  new  obligations  have  accumulated  since  the  first 
edition  appeared.  Those  who  have  used  the  book  in 
class  or  have  read  it  in  individual  study  have  in  many 
instances  sent  to  the  author  helpful  criticisms.  All  of 
these  have  teen  kept  in  mind  m  the  revision  and  are 

here  gratefully  acknowledged. 

:i  J. 
CHICAGO.  It  i : 


PREFACE  TO  THE  FIRST  EDITION 

There  is  very  general  agreement  as  to  the  main  topics 
which  must  be  treated  in  a  textbook  on  psychology.  There 
is,  however,  no  accepted  method  of  approaching  these 
topics,  and,  as  a  result,  questions  of  emphasis  and  propor- 
tion are  always  matters  of  individual  judgment.  It  is, 
accordingly,  not  out  of  place  for  one  to  attempt  in  his 
preface  to  anticipate  the  criticism  of  those  who  take  up 
the  book,  by  offering  a  general  statement  of  the  princi- 
ples which  have  guided  him  in  his  particular  form  of 
treatment.  This  book  aims  to  develop  a  functional  view 
of  mental  life.  Indeed,  I  am  quite  unable  to  accept  the 
contentions  or  sympathize  with  the  views  of  the  defenders 
of  a  structural  or  purely  analytical  psychology.  In  the 
second  place,  I  have  aimed  to  adopt  the  .genetic  method 
of  treatment.  It  may  be  well  to  remark  that  the  term 
"  genetic  "  is  used  here  in  its  broad  sense  to  cover  all  that 
relates  to  general  evolution  or  individual  development.  In 
the  third  place,  I  have  attempted  to  give  to  the  psycho- 
logical conditions  of  mental  life  a  more  conspicuous  place 
than  has  been  given  by  recent  writers  of  general  textbooks 
on  psychology.  In  doing  this  I  have  aimed  to  so  coordi- 
nate the  material  as  to  escape  the  criticism  of  producing 
a  loose  mixture  of  physiology  and  introspective  description. 
In  the  fourth  place,  I  have  aimed  to  make  as  clear  as 
possible  the  significance  of  ideation  as  a  unique  and  final 
stage  of  evolution.  The  continuity  running  through  the 
evolution  of  the  sensory  and  motor  functions  in  all  grades 
of  animal  life  is  not,  I  believe,  the  most  significant  fact  for 
psychology.  The  clear  recognition  of  this  continuity  which 


P8Y(  n«  'i  - 

•indent  reaches  through  studies  of  sen 

and  <  :  rincst  possit  a  on 

i    to   IMSC   an    intelli  mate   of   the-    significance 

of   human    idcational   process*  :ision 

of  the  dominant  importun  -ses  in  man's 

the  ih 

•  tion  for  a  science  of  psychology,  <  :iom 

all  of  the  oti.  il  disciplines  \\hich  deal  with  life  and 

The  purjxjse  of  this  book  may  therefore  be 
.s  \\hich  mark  as  sharp  a  contrast  as  possible 
with  much  that  !  -.ml  and  written  of  late  regarding 

the  advantages  of  a  biological  point  of  view  in  the  study 
of  const  1  his  work  is  intended  to  develop  a 

point  of  view  \\hich  shall  include  all  that  is  given  in  the 
biological  doctrine  of  adaptation,  while  at  the  same  time  it 
passes  beyond  the  biological  doctrine  to  a  more  elaborate 
principle  of  indirect  idcational  adaptation. 

In  the  preparation  of  this  book  I  am  under  double  obli- 
gation to  A.  ('.  Armstrong.  As  my  first  teacher  in  psy- 
chology, he  has  by  his  broad  sympathies  and  critical  insight 
influenced  all  of  my  work.  Furthermore,  he  has  given  me 
the  benefit  of  his  judgment  in  regard  to  all  parts  of  this 
book  while  it  was  in  preparation.  Two  others  I  may  men- 
tion as  teachers  to  whom  I  am  largely  indebted.  The 
direct  influence  of  \Vilhelm  \Vundt  will  be  seen  at  many 
points  in  this  book.  As  the  leader  in  the  great  advances 
in  modern  psychology,  especially  in  the  adoption  of  experi- 
mental methods,  and  as  the  most  systematic  writer  in  this 
field,  he  has  left  his  impression  on  all  who  have  worked 
in  the  Leipzig  laboratory  to  an  extent  which  makes  such 
a  book  as  this  in  a  very  large  sense  of  the  word  an  expres- 
sion of  his  teaching.  Finally,  I  am  indebted  to  William 
James.  I  have  received  instruction  from  him  only  through 
his  writings,  but  take  this  opportunity  of  acknowledging  his 
unquestioned  primacy  in  American  psychological  thought 


PREFACE  vii 

and  the  influence  of  his  genius  in  turning  the  attention  of 
all  students  to  the  functional  explanations  of  mental  life 
which  it  is  one  of  the  aims  of  this  book  to  diffuse. 

My  colleagues,  Dr.  R.  P.  Angier  and  Dr.  E.  H.  Cameron, 
read  the  manuscript  and  gave  me  many  valuable  sugges- 
tions which  have  been  incorporated  into  the  text.  Mr.  C.  H. 

Smith  assisted  me  in  the  preparation  of  the  figures. 
• 

C.  H.  J. 
NEW  HAVEN,  CONNECTICUT 


CONTENTS' 

PAGE 

CHAPTER  I.  THE  SCOPE  AND  METHODS  OF 
PSYCHOLOGY i 

Psychology  a  study  of  conscious  processes.  The  motive  of  wonder. 
Discovery  of  individual  differences  as  motive.  Differences  between 
experience  and  physical  facts.  Place  of  consciousness  in  evolution. 
The  first  method  of  psychology.  Nervous  processes  as  conditions  of 
consciousness.  Studies  of  behavior.  Overemphasis  of  slower  forms 
of  mental  activity  through  introspection.  Experiment  in  psychology. 
Explanation  at  variance  with  mere  observation.  Subdivisions  of 
psychology.  Summary  and  definition  of  psychology.  Definitions  of 
certain  general  psychological  terms. 

CHAPTER  II.  THE  BODILY  CONDITIONS  OF  BE- 
HAVIOR AND  EXPERIENCE 14 

The  introspective  approach.  Indirect  method  of  approach  to  psy- 
chological facts.  Characteristics  of  unicellular  animals.  Simplest 
types  of  behavior.  Consciousness  no  more  complex  than  behavior. 
Behavior  more  limited  than  sensitivity.  Specialization  of  cell  struc- 
tures and  functions  in  higher  animals.  Specialized  nervous  processes. 
Nervous  processes  of  three  distinct  types.  Behavior  varied  and  much 
more  complex.  Progressive  evolution  in  both  structure  and  behavior. 
Centralized  nervous  system.  Coordinating  center  of  the  body.  Com- 
plex paths  within  the  nervous  system.  Experience  comparable  to 
the  lower  forms  of  human  experience.  Differentiation  of  vertebrate 
central  nervous  system.  Two  types  of  higher  centers  :  first,  higher 
sensory  centers ;  second,  indirect  centers.  Large  indirect  centers 
characteristic  of  highest  animals.  Traces  of  past  impressions  also 
present.  Meaning  of  evolution  of  complex  organisms.  Inner  organi- 
zation essential  to  highest  forms  of  personal  behavior.  Characteristics 
of  behavior  of  higher  animals. 

CHAPTER  III.    THE  HUMAN  NERVOUS  SYSTEM    .     .     38 

External  plan  like  that  of  all  vertebrates.  General  plan  of  the  minute 
nervous  structure  as  related  to  consciousness.  The  nerve  cell  and  its 
parts.  Complexity  of  structure  related  to  forms  of  action.  Synapses 
as  paths  of  organization.  Paths  in  spinal  cord.  Reflex  tracts.  Trans- 
mission to  higher  centers.  All  nervous  organs  in  part  independent 


HOLOGY 


C«Bt»r*.   Cerebellum.    < 'erebrum  and  its  systems  of  fibers 

lirum  .>%  imiicatmK  w 

bral  cortex  complex.    I.«HM  :  unction*. 

mrth»d  of  discovering  cerebral  local 

pariso:  v    Embr>  l».    Associ 

ureas.    Significance  of  the  central  position  of  the  general  motor  area. 
Speech  centers.     Broca's  convolution  an  association  cen: 
nology  not  in  ai  >  v  known  facts.    Frontal  as»oc 

r.tl  principles  of  nervous  a>  '«ans  as  termini 

of  all  nervous  impulse  Ic  of  asso- 

ciation of  centers  of  high  tension.    Diffusion  as  opposed  to  organiza- 
*tion.    Principle  of  progressive  organization. 

I  HAITI .K      1'                                    iln.N      <>K      CONSCIOUS 
PROCESSES    .     .     .  

Classification  derived  from  study  of  nervous  organs.  Classification 
from  observation  superficial.  Historical  threefold  classification 
torical  twofold  classification.  Classification  according  to  nervous 
processes.  Example  of  scientific  analysis  and  classification.  Relation 
of  classification  to  introspection.  Sensations.  Reactions  and  atti- 
tudes. Fusion  and  perception.  Memory.  The  process  of  ideation. 
Higher  forms  of  action.  Relation  to  !  Practical 

applications. 

CHAITKK   V.    SENSATIONS 71 

Sensations  not  copies  of  external  forces.  Laws  of  sensation  as  one 
•of  the  first  problems  in  psychology.  Relation  of  sensations  to  sen- 
sory nervous  processes.  Sensations  as  elements.  Psycho-physics  as 
a  division  of  psychology.  Meaning  of  term  "quality."  Chromatic 
(or  color)  series  and  achromatic  (or  gray)  series.  Fundamental  color 
names.  The  color  spectrum  and  circle.  Saturation,  brightness,  and 
mixtures.  External  light.  Comparison  of  physical  and  mental  series. 
Relation  between  the  physical  and  the  psychical  facts  dependent  in 
part  on  the  organs  of  sense.  Evolution  of  organ  Organ  of 

sense  as  selective  organ.  The  human  eye  —  its  muscles.  The  outer 
wall  and  the  lens.  Transparent  media.  Choroid  coat  The  retina. 
Rods  and  cones  and  their  functions.  Color  blindness.  Color-mixing. 
Pigment-mixing  subject  to  physical  law.  After-images.  Contrasts. 
Theories  of  color  vision.  Mrs.  Franklin's  penetic  theory  of  processes 
in  the  retina.  Physical  sound.  Pitch,  or  tonal  quality.  Intcnsit 
loudness.  Complexity  of  a  regular  type  the  source  of  differences  in 
timbre.  Noise  due  to  irregular  vibrations.  Evolution  of  the  ear.  The 
human  ear,  pinna,  and  meatus.  The  tympanic  membrane.  Air  cham- 
ber on  inner  side  of  the  tympanic  membrane.  Chain  of  ossicles.  The 
inner  ear.  The  semicircular  canals.  The  cochlea  and  sensory  areas 


CONTENTS  xi 


in  the  vestibule.  Sensory  cells  in  the  cochlea.  Contrast  between 
auditory  and  visual  processes.  Beats,  difference  tones.  Summation 
tones.  Harmony  not  a  matter  of  sensation.  Absence  of  after-images 
in  auditory  sensations.  Tone  deafness.  Taste  and  smell  differenti- 
ations of  a  primitive  chemical  sense.  Position  of  olfactory  organ  in 
the  nasal  cavity.  Structure  and  function  of  the  olfactory  surface. 
Olfactory  stimuli.  Smell  a  rudimentary  sense  in  man.  Taste  quali- 
ties and  taste  organs  specialized.  Organs  of  taste.  Gustatory  stimuli. 
Organs  of  touch.  Differentiation  of  the  tactual  fibers ;  temperature 
spots.  Pressure  spots.  Other  "  spots."  Relativity  of  temperature 
sense ;  chemical  and  mechanical  senses.  Organs  of  touch  at  the 
periphery.  Muscle  sensations  and  organic  sensations.  Intensity  a 
general  characteristic.  Weber's  Law.  General  statement  of  the  law. 
Mechanical  explanation  of  Weber's  Law.  Other  views  regarding 
Weber's  Law. 

CHAPTER  VI.    EXPERIENCE  AND  BEHAVIOR  ...     130 

All  consciousness  complex  and  selective.  The  selective  character 
of  conscious  processes  related  to  sensory  impressions.  Selective 
consciousness  related  to  behavior.  Common  interests  and  their  re- 
lation to  behavior.  Study  of  evolution  of  organs  of  action  as  impor- 
tant as  study  of  senses.  Evolution  from  gross  muscles  to  highly 
differentiated  muscles.  Behavior  dependent  on  nervous  control. 
Coordination  as  necessary  counterpart  of  differentiation.  Individual 
development  in  behavior.  Inherited  coordinations  or  instincts. 
Glands  as  active  organs.  A  constant  tension  of  active  organs 
as  background  of  all  behavior.  Meaning  of  sensory  impressions 
dependent  upon  inner  conditions.  Sensory  processes  and  the 
equilibrium  of  action.  Importance  of  sensations  dependent  on 
organization.  Sensations  unduly  emphasized  through  introspection. 
Attitudes.  Attitudes  not  related  to  sensations  but  to  behavior. 
Relation  of  sensation  to  reaction. 

CHAPTER  VII.  CERTAfN  FUNDAMENTAL  ATTI- 
TUDES   146 

Reactions  toward  objects  and  reactions  away  from  objects.  Pleasure 
and  displeasure.  Cultivated  feelings.  Fear  as  a  typical  emotion. 
How  to  change  the  attitude  of  fear.  Fear  an  emotion  of  complex 
beings.  Fear  and  pathology.  Parental  love  and  altruism.  Anger. 
Other  emotions.  Emotions  as  fundamental  forms  of  experience. 
Higher  forms  of  experience  as  related  to  behavior.  Feelings  of 
organic  type.  Flexor  and  extensor  movements  related  to  character- 
istic attitudes.  Changes  in  circulatory  movements  as  parallels  of 
conscious  changes.  Disappointment  as  negative  emotion.  External 
attitudes.  Attention  as  an  attitude.  Experiment  to  demonstrate 


tension.   Various  forms  <>t  •  :  trllow  hrinjt 

Sympathy  involved  in  all  recognition  of  object*.     lllu> 
muscular  tension.   Such  muscu!  ,  common  to  m 

•new.  All  ness  a  form  of  sympathetic  alter  tudes 

aa  related  to  higher  processes  of  recognit 

(  HAPTKR    VIII.      COMU: 

\1I.N  I     • 

Sensory  experience  always  complex.  Sensation  combinations  or 
fusions.  Space  not  a  sensation,  but  a  product  of  fusion.  Tactual 
space  as  a  simple  example  of  fusion.  Subjective  and  obj< 
space.  Perception  and  training.  Development  of  spatial  arrange- 
ments in  the  course  of  individual  experience.  Vision  and  move- 
ment as  aids  to  touch.  Tactual  percepts  of  the  blind.  \Vundt  on  the 
tactual  perception  of  the  blind.  Lotze's  local  signs.  Inner  tactual 
factors.  Space  not  attached  to  any  single  sense.  General  conclu- 
sions regarding  tactual  space.  Auditory  recognition  of  location. 
Influence  of  movements  in  auditory  experience  of  position.  '. 
tative  differences  and  localization.  Distance  of  sounds  recognized 
only  indirectly.  Unfamiliar  sounds  difficult  to  locate.  Visual  space 
and  optical  illusions.  Effects  of  practice.  Percepts  always  complex. 
Contrast  Common  facts  showing  size  to  be  a  matter  of  relations. 
Physiological  conditions  of  visual  perception.  Psychological  state- 
ment. Photographic  records  of  percepted  movements.  Relation 
between  size  and  distance.  Definite  optical  relation  between  the 
distance  and  the  size  of  an  object  and  the  size  of  the  retinal  image 
from  this  object.  Berkeley's  statement  of  the  problem  of  visual 
depth  perception.  Experiments  on  binocular  vision.  Difference 
between  the  images  in  the  two  eyes.  Stereoscopic  figures  and 
appearance  of  solidity.  Retinal  rivalry.  Factors  other  than  those 
contributed  by  the  two  eyes.  Aerial  perspective.  Geometrical  per- 
spective and  familiarity.  Shadows.  Intervening  objects.  Depth  a 
matter  of  complex  perception.  Relation  to  movements.  General 
movements  as  conditions  of  fusion  of  retinal  sensations.  Space 
a  system  of  relations  developed  through  fusion.  Movement  and 
mechanical  laws.  Perception  of  individual  objects.  Mere  coexist- 
ence of  sensations  no  explanation  of  unity  in  the  percepts  of 
objects.  Range  of  fusion  determined  by  practical  considerations. 
Changes  in  percepts  through  repetition.  Parallel  development  of 
perception  and  habit  Time  as  a  general  form  of  experience.  Ex- 
perimental determination  of  the  scope  of  "  the  present."  Scope  of 
"  the  present "  and  its  varying  conditions.  Time  relations  in  verse 
and  related  systems  of  experience.  Time  arrangement  as  condi- 
tioned by  the  rhythmical  changes  in  nervous  processes.  Perception 
more  than  the  flux  of  sensations.  Discussions  of  perception. 


CONTENTS  xiii 

PAGE 

CHAPTER  IX.    HABITS 195 

Organic  retentiveness.  Remoter  conditions  of  retention.  Instincts. 
Protective  instincts.  Food-taking  instinct.  Instincts  established 
through  selection.  Delayed  instincts  common.  Impossibility  of  dis- 
tinguishing instincts  from  later-acquired  forms  of  behavior.  Habits 
from  instincts  and  from  independent  conditions.  Development  of 
habit  through  conflict  of  instincts.  Nervous  development  concerned 
in  the  selection  of  instincts.  Habit  as  a  modified  instinct.  Importance 
of  heredity  in  explaining  consciousness.  Diffusion  a  mark  of  lack 
of  organization.  Development  of  habit  from  diffusion.  Undeveloped 
movements.  Diffusion  analogous  to  all  forms  of  overproduction. 
Conscious  correlates  of  habit.  Instinct,  habit,  and  mental  attitudes. 
Applications  of  the  doctrine  of  attitudes  to  social  science. 

CHAPTER  X.    SPEECH  AS  A  FORM  OF  BEHAVIOR  .     209 

Speech  as  a  highly  important  special  habit.  Speech  and  ideas  closely 
interrelated.  Speculations  regarding  the  nature  and  origin  of  speech. 
The  special  creation  theory.  The  imitation  theory.  The  interjection 
theory.  Roots  of  language  in  natural  emotional  expressions  and  their 
imitation.  Imitation.  Other  imitative  communications  of  animals  and 
man.  Value  of  sounds  as  means  of  social  communication.  Limita- 
tion of  forms  of  animal  communication.  The  first  stages  of  human 
articulation  like  animal  cries.  Articulations  selected  from  the  sum 
of  possible  activities.  Evolution  of  ideas  and  speech.  Gestures  and 
broad  scope  of  attention.  Evolution  of  gestures  in  direction  of  sim- 
plification. Speech  a  highly  specialized  mode  of  behavior.  Conse- 
quences of  specialization.  Speech  an  indirect  form  of  behavior. 
Evolution  of  writing.  Writing  at  first  direct  in  form.  Images 
reduced  to  lowest  terms  as  powers  of  reader  increase.  Written 
symbols  and  their  relation  to  sounds.  The  alphabet.  Social  motives 
essential  to  the  development  of  language.  Social  system  as  source 
of  the  form  of  words.  Social  usage  and  the  domination  of  individual 
thought.  Social  ideas  dominate  individual  life.  Experimental  evi- 
dence of  importance  of  words.  Number  terminology  as  a  device 
for  recording  possessions.  Symbols  for  groups  of  tallies.  Parallel 
growth  of  number  names  and  system  of  ideas.  Development  of 
arithmetic  depends  on  an  appropriate  system  of  numerals.  Social 
world  unified  through  common  forms  of  thought.  Changes  in  words 
as  indications  of  changes  in  individual  thought  and  social  relations. 
Illustration  of  change  in  words.  Words  as  instruments  of  thought 
beyond  immediate  experience.  Images  and  verbal  ideas.  Mental 
attitudes  as  characteristic  phases  of  verbal  ideas.  Other  illustrations 
of  thought  relations.  Concrete  words.  Examples  of  words  arousing 
tendencies  toward  action.  Abstract  words.  Contrast  between  con- 
crete images  and  abstract  ideas.  Particular  images  as  obstructions  to 
thought.  Ideas  or  indirect  forms  of  experience  characteristic  of  man. 


f(  HOLOGY 

fAGl 

>RY  AND  II  240 

The  problem  of  describing  ideas.    Ideas  t  I  from  present 

impressions.    Ideas  as  revivals.   Advantages  of  reb  end 

•f  sensory  impressions.  Individual  variations  in  imagery.  The 
accidents  of  individual  experience  and  mental  imagery.  Dependence 
on  vividness  and  ro  •  .img  of  memory.  Retention  as 

distinguished  from  recall.    Association  by  contiguity.    Associ 
by  similarity.   Association  by  contrast   New  products  evolved  in 
I  .leas  not  all  images.  Tendency  to  revert  to  imagery  type. 
Advantages  of  indirect  forms  of  experience.    Animal  bcha\ 
and  perceptual,  human  behavior  indirect  and  ideational.    Influence 
of   ideas   on   things.   Tool-consciousness.    Knowledge   of   nervous 
process  limited.    Consciousness  as  product  of  evolu 

(.  H AITLK    XII.      IMAGINATION   AND    THK    FORMA 
\  OF  CONCEIT'S 

Adaptation  through  ideas.  Early  stages  of  barter.  Barter  perceptual. 
.Standard  values.  Symbolic  values.  Evolution  from  perception  to 
ideas.  Higher  controls  of  conduct.  Ideational  attitudes.  Ideas  as 
substitutes  for  impressions.  Imagination  as  reorganization  of  ideas. 
Personifying  imagination.  Imaginations  occasions  of  useless  a. 

il  tests  of  imaginations.  Empirical  test  often  inapplica- 
ble. The  test  of  internal  agreement.  The  criterion  of  coherency  a 
product  of  development.  The  demand  for  coherency  as  exhibited 
in  constructive  scientific  ideas.  Uncritical  imaginations.  Literary 
imagination  and  the  canon  of  coherency.  The  uncritical  forms  of 
thought  which  preceded  science.  First  sciences  limited  to  facts 
remote  from  life.  Scientific  concepts.  Validity  of  concepts.  Abstrac- 
tion. Generalization,  judgments  and  reasoning.  Logic.  Primitive 
belief.  Belief  after  hesitation.  Belief  a  positive  psychological  fact. 
Spurious  verbal  belief.  Habitual  belief.  Religious  belief  not  in- 
stinctive. Sentiments  not  instinctive.  Social  life  and  the  higher 
mental  processes.  Fields  for  the  application  of  psychology  of  ideas. 

CHAPTER  XIII.    THE  IDEA  OF  THE  SELF     ....     269 

The  idea  of  self  sometimes  regarded  as  matter  of  direct  knowledge. 
Idea  of  self  a  concept  First  stages  of  personal  development  not 
self-conscious.  Gradual  discrimination  of  self  from  things.  Child's 
early  notion  of  self  largely  objective.  The  idea,  of  self  as  related  to 
discrimination  between  the  objective  and  subjective.  The  self  dis- 
covered by  contrast  with  not-self.  Social  consciousness  and  self- 
consciousness.  The  self  at  first  not  a  scientific  concept  but  a 
practical  concept.  Cultivated  self-consciousness.  The  religious 
motive  for  self-consciousness.  Scientific  idea  of  personality.  The 
chief  item  in  the  concept  of  life  the  abstract  idea  of  organization. 


CONTENTS  xv 

PAGE 

Unity  of  self.  The  self  as  an  efficient  cause.  Self  as  a  valid  scien- 
tific concept.  Concept  of  unity.  The  self  a  concept. 

CHAPTER  XIV.    DISSOCIATION 278 

Disorganized  personality  in  contrast  with  normal  self.  Illusions  and 
hallucinations.  Sleep,  the  influence  of  drugs,  hypnosis,  and  insanity 
as  forms  of  disorganization.  The  physiological  conditions  of  sleep. 
The  closing  of  avenues  of  stimulation  in  sleep.  Various  degrees  of 
dissociation.  Dissociation  in  the  central  processes.  Dreams  as  dis- 
sociated groups  of  ideas.  Dreams  impressive  only  because  they  are 
uncriticized.  Motor  processes  suspended  by  dissociations  in  sleep. 
Narcotic  drugs  dissociative  in  their  effects.  Effect  of  alcohol  on 
the  nervous  system.  Overexcitation  is  also  dissociative.  Toxic 
effects  of  certain  diseases.  These  negative  cases  as  evidences  of  the 
relation  between  normal  consciousness  and  organization.  Hypnosis 
a  form  of  dissociation  closely  allied  to  sleep.  Hypnosis  as  partial 
dissociation.  Methods  of  inducing  hypnosis.  Hypnosis  more  readily 
induced  after  it  has  once  been  established  in  a  subject.  Various 
characteristics  of  the  hypnotized  subject.  Ideas  not  subjected  to 
criticism  in  hypnosis.  Dual  personalities  in  hypnosis.  Dual  per- 
sonalities in  other  than  hypnotic  conditions.  Dual  and  multiple  per- 
sonalities analogous  to  the  various  selves  of  normal  life.  Hypnosis 
a  transient  condition,  insanity  permanent.  Movements  sometimes 
normal  in  hypnosis,  because  the  lower  centers  are  not  dissociated. 
The  after-effects  of  hypnosis  tend  to  become  permanent.  Insanity 
a  permanent  form  of  disorganization,  introduced  in  many  cases  by 
dissociation  and  settling  into  an  abnormal  reorganization.  Melan- 
cholia as  a  typical  form  of  dissociation.  Excessive  excitation  as  a 
second  typical  case  of  insanity.  Fundamental  disturbances  of  in- 
stinctive and  emotional  life.  Relation  of  psychiatry  to  psychology. 

CHAPTER  XV.  VOLUNTARY  ACTION  AND  VOLUN- 
TARY ATTENTION 301 

Voluntary  action  a  special  form  of  behavior.  Instinctive  behavior 
different  from  voluntary  action.  Impulsive  acts  distinct  from  higher 
forms  of  voluntary  action.  Impulsive  acts  as  phases  of  general  mus- 
cular tension.  Impulsive  acts  explicable  through  nervous  organiza- 
tion. Impulse  comparable  to  involuntary  attention.  Impulse  and 
involuntary  attention  related  to  perception  and  habit.  Simple  case 
of  choice.  Behavior  of  the  higher  types  dependent  on  ideas.  Volun- 
tary action  and  its  complex  background  as  contrasted  with  lower 
forms  of  behavior.  Decision  a  process  of  balancing  ideas.  Decision 
largely  influenced  by  organization  built  out  of  past  experiences. 
The  meaning  of  prevision.  The  problem  of  the  freedom  of  the  will. 
Voluntary  choice  guided  by  purposes.  Behavior  of  a  higher  type 


l->\(  ill  ll.t 


is  related  to  education.    Early  socntifu   studies  of  behavior  purely 

•>ugations  not  prod 

investigation*  and  their  stress  on  introspection  and  analysis  of 
movement  An*  nent.  Concept  of  organ- 

ization as  fundamental  in  all  psychological  studies. 

VI     MENTAL  IT,  314 

<  nc  *  suggestive  term  for  psychology.  Relation  of  p»\ 
logical  hygiene  to  physiological,  I'oordi  nation  of  bodily  activities. 
>\  of  excessive  stimulations.  I'crccptual  analysis.  Perceptual 
synthesis.  Dangers  of  specialization.  Control  of  perceptual 
tudes.  Control  of  attitudes  as  a  case  of  volition.  Rules  of  whole- 
some ideation.  Economy  of  mental  effort.  Preparation  as  aid  to 
memory.  Organization  the  key  to  all  correct  thought.  The  domi- 
nation of  thought  by  some  leading  idea.  Language  of  great  im- 
portance in  furnishing  central  ideas.  The  ineffectiveness  of  a 
detached  verbal  idea.  Higher  organization  as  a  cure  for  verbalism. 
Self-directed  organization  as  the  goal  of  the  higher  mental  life. 

CHAPTER  XVII.   APPLICATIONS  OF  PSYCHOLOGY  .     325 

Psychology  a  basis  of  scientific  thinking  about  human  conduct. 
Design  in  art  as  a  psychological  fact  Freedom  in  art.  Architectural 
harmony  analogous  to  musical  rhythm  and  harmony.  Literary  art 
and  psychological  laws.  Prose  rhythms  as  related  to  the  personal 
organization  of  writers.  Verse  another  example  of  the  same  type. 
Literary  content  controlled  by  psychological  laws.  Feeling  and 
intuition.  Many  of  the  social  sciences  predominantly  objective  in 
their  methods.  Introspective  psychology  and  its  limited  support 
to  social  science.  Interrelation  of  psychology  and  social  science. 
Human  evolution  psychical.  An  hypothesis  to  explain  the  break  be- 
tween man  and  the  animals.  Spencer's  application  of  psychology  to 
sociology.  Relation  of  educational  practices  to  scientific  psychology. 
Psychology  as  a  preparation  for  the  intelligent  diagnosis  of  particular 
situations  which  arise  in  educational  practice.  A  curve  illustrating 
the  process  of  learning.  Significance  of  a  "  plateau  "  in  development. 
Other  examples  of  the  same  type  of  development.  Motor  habits  in- 
termittent. School  training  in  its  relation  to  the  stage  of  develop- 
ment attained  by  the  mind.  Significance  of  scientific  studies  often 
indirect  Expression  as  an  essential  condition  of  mental  life.  Psy- 
chology historically  a  part  of  philosophy.  Relation  of  psychology  to 
philosophy  closer  than  that  of  any  of  the  special  sciences.  Psy- 
chology and  logic.  Psychology  and  aesthetics.  Psychology  and 
ethics.  Psychology  and  metaphysics. 

INDEX  ...................     349 


LIST  OF   ILLUSTRATIONS 


1 .  Diagram  for  use  in  demonstration  of  the  blind  spot   ....       9 

2.  Movements  of  a  unicellular  animal 1 6 

3.  The  hydra 18 

4.  Much-enlarged  section  of  a  muscle  cell  and  a  sensory  cell  of  a 

hydra,  together  with  the  connecting  cells  which  lie  between 
them 20 

5.  Outline  of  a  starfish,  and  nervous  system  of  the  same     ...     24 

6.  A  stag  beetle,  showing  the  outline  of  the  body  and  the  dis- 

tribution of  the  nerve  cells  and  fibers 25 

7.  The  nervous  system  of  a  frog  as  it  would  appear  if  the  skin 

and  muscles  and  protecting  bone  were  removed    ....     28 

8.  Plate  snowing  successive  stages  in  the  evolution  of  the  verte- 

brate nervous  system 31 

9.  General  form  and  position  of  central  nervous  organs      ...     38 

10.  Two  nerve  cells 39 

1 1 .  A  number  of  different  types  of  connection  between  nerve  fibers 

and  cells 40 

1 2.  The  development  in  complexity  of  nerve  cells  in  the  course  of 

animal  evolution  and  in  the  course  of  the  development  of  a 
single  individual 41 

13.  Transverse  section  across  the  spinal  cord 42 

14.  A  diagram  to  illustrate  the  course  of  the  sensory  stimulation 

when  it  passes  upward  from  the  level  of  the  spinal  cord  at 
which  it  is  received 44 

15.  A  diagrammatic  section  through  a  part  of  one  of  the  folds  in 

the  cerebellum 45 

1 6.  The  brain  seen  from  below  and  cut  open  to  show  the  paths  of 

fibers  from  the  cortex  of  the  cerebrum  to  the  lower  organs     46 

1 7.  Sketch  showing  some  of  the  association  fibers  connecting  vari- 

ous parts  of  the  cortex  of  the  cerebrum  with  one  another     47 

1 8.  A  transverse  section  across  the  two  hemispheres  in  a  pl#ne 

passing  vertically  through  the  cheek  bones  parallel  to  a 

line  connecting  the  two  ears 48 

xvii 


\\iii  l'>\<  HI 

wo  sections  representing  portions  of  the  cerebral  a» 

•  areas  of  the  human  brain 
20.  A  diagrammatic  section  showing  the  sin  :,c  cortex 

of  '                     nil    .      .  50 
he  outline  of  the  lateral  surface  of  the  cerebrum  with  tin- 
ts pica!  convolutions,  as  given  by  Flechsig      .  52 
.  he  median  surface  of  the  human  cerebrum  showing,  as  in 

:he  various  areas  ....  53 

76 

24.  \Vave  forms 77 

V    series  of   eyes   which    have    re...  .us    lc\<-! 

development 82 

unmatic  section  of  the  human  eye  85 

27.  A  diagrammatic  section  of  the  retina  88 

28.  Diagrammatic  section  showing  the  structure  of  the  car      .     .  104 

29.  Diagrammatic  section  of  the  sensory  cells  in  the  vestibule     .  108 

30.  The  structure  in  the  cochlea  as  seen  when  a  transverse  sec- 

tion is  made  across  the  canal 109 

31.  Diagram  to  represent  the  formation  of  beats 113 

32.  The  inner  cavity  of  the  nose in- 

33.  Section  showing  the  different  cells  which  compose  the  mucous 

lining  of  the  nose  in  the  olfactory  region 117 

34.  Olfactory  cells  and  supporting  cells 118 

35.  The  depression  between  the  sides  of  two  papilkr  on  the 

face  of  the  tongue 119 

$<<.  .\  diagrammatic  section  of  a  single  taste  bulb  showing 

character  of  the  different  cells i  20 

\  diagrammatic  sketch  showing  two  neighboring  taste  bulbs  i  2 1 

38  A.  Tactual  end  organs i  24 

38  B.  A  Pacinian  corpuscle I  24 

38  C.  A  Misscnian  corpuscle 124 

39.  Two  Golgi-Mazzoni  corpuscles  of  the  type  found  by  Ruffini 

in    the   cutaneous   connective   tissue  of   the   tip  of   the 
human  finger 125 

40.  The  complex   distribution  of  a  tactual   nerve  fiber  in   the 

immediate  vicinity  of  a  hair 

41.  Tooth  of  <  i.'himiN  ^bowing  distribution  of  nerve  fiber  through- 

out the  canal  of  the  tooth 127 


LIST  OF  ILLUSTRATIONS  xix 

FIGURE  PAGE 

42.  A  highly  developed  muscle  cell 134 

43.  The  contracted  and  relaxed  state  of  a  muscle 135 

44.  Diagram  showing  relation  of  sensory  impressions  to  reactions  143 

45.  Involuntary  hand  movements  made  by  the  right  and  left  hands 

of  an  observer  who  is  thinking  of  a  building  situated  in 

front  of  him 157 

46.  Unaesthetical  balance 158 

47.  Miiller-Lyer  illusion 172 

48.  Illusion  of  contrast 1 74 

49.  Zollner  illusion 1 76 

50.  Poggendorff  illusion 1 76 

5 1 .  Figures  showing  the  path  followed  by  the  eye  of  an  observer 

in  examining  certain  of  the  foregoing  illusions    ....  177 

52.  Relation  of  retinal  image  to  objects 179 

53.  Binocular  parallax » 182 

54.  An  Ojibwa  love  letter 220 

55.  Ancient  and  modern  Chinese  writing 221 

56.  Derivation  of  the  Roman  letter  M  from  the  ancient  Egyptian 

hieroglyphic  owl 222 

57.  Association  by  similarity 245 

58.  Fatigued  cells 280 

59.  Curve  showing  the  intensity  of  sound  necessary  to  awaken  a 

sleeper  at  different  periods  of  sleep 282 

60.  Curves  for  sending  and  receiving  telegraphic  messages      .     .  338 

61.  Analysis  of  the  receiving  curve 340 


PSYCHOLOGY 

CHAPTER  I 
THE  SCOPE  AND  METHODS  OF  PSYCHOLOGY 

Psychology  a  study  of  conscious  processes.  "  The  under- 
standing, like  the  eye,  whilst  it  makes  us  see  and  perceive 
all  other  things,  takes  no  notice  of  itself ;  and  it  requires 
art  and  pains  to  set  it  at  a  distance,  and  make  it  its  own 
object."1  Thus  did  one  of  the  earliest  English  psychologists 
point  out  the  distinction  between  ordinary  experience  and 
the  scientific  study  of  mental  processes.  A  man  may  be 
afraid,  or  enthusiastic,  or  lost  in  reverie ;  in  each  case  his 
mind  will  be  full  of  emotions  and  ideas,  but  he  will  not  be 
led  by  the  intensity  of  his  experiences  to  make  them  sub- 
jects of  analysis  and  explanation.  Indeed,  the  more  he  is 
absorbed  in  the  experience  itself,  the  less  likely  he  is  to 
psychologize  about  himself.  We  all  have  the  raw  materials 
for  a  science  of  mental  processes  within  us,  but  we  require 
special  motives  to  lead  us  to  that  careful  study  of  these 
processes  which  gives  rise  to  the  science  of  psychology. 

The  motive  of  wonder.  The  motives  which  have  led  men 
to  make  a  scientific  study  of  their  conscious  processes  are 
numerous  and  varied  in  character.  Perhaps  the  most  com- 
mon of  these  motives  is  to  be  found  in  the  exceptional  and 
baffling  experiences  through  which  one  passes  from  time  to 
time.  I  think  I  hear  a  voice,  but  find  on  examination  that 
no  one  spoke.  I  try  to  grasp  an  object,  but  find  that  for 

1  John  Locke,  Essay  concerning  Human  Understanding,  Bk.  I,  chap,  i, 
sect.  i. 


2  PSYCHOLOGY 

my  sense  of  touch  tli-  b  not  what  it  seems  to  be  for 

my  sense  of  \  >uch  experiences  as  these  require  some 

explanation,  and  even  the  most  superficial  obsr:  ikely 

to  become  interested,  at  least  for  the  moment,  in  th 
pretatioii.     Popular  psychology  seldom  gets  beyond  in 
amination  of  striking  and  unique  experiences; 
the  notion    has   gained  wide  currency   that    p^.i-hology  is 
•ted  entirely  to  the  i:  m  of  occult   ph- 

Discovery  of  individual  differences  as  motive.    Interest  in 
>tional  experiences  is  hardly  a  sufficient  motive,  how 
,  to  lead  to  long-continued  systematic  study.     It  is  to  be 
doubted  whether  psychology  would  ever  have  developed 
a  serious  science  unless  other  more  fundamental   m- 
had  arisen  to  turn  the  attention  of  men  to  the  examin 
and  explanation  of   their  conscious   processes.    The   : 
fundamental  motives  began  to  appear  as  far  back  as  the  time 
of  the  Greeks.    These  early  thinkers  found  themsehv 
bitter  intellectual  controversies.    Given  the  same  facts  and 
the  same  earnest  effort  to  use  these  facts  in  the  establish- 
ment of  truth,  the  Greeks  found  that  two  individuals  - 
arrive  at  opposite  conclusions.    This  made  it  clear  that  like 
facts  may  lead  in  two  different  minds  to  entirely  different 
processes  of  thought.     So  striking  were  the  individual  dif- 
ferences that  early  thinkers  despaired  of  finding  any  general 
Gradually,  however,  as  the  way  in  which  men  remem- 
ber and  the  way  in  which  men  relate  their  ideas  were  studied, 
it  became  apparent  that  back  of  the  seeming  variety  there 
are  certain  common  forms  of  consciousness,  certain  funda- 
mental laws  of  mental  activity  which  can  be  discovered  and 
matically  arranged  into  a  science  of  mental  life.   To  this 
task  the  Greek  philosophers  set  themselves  with  enthusiasm, 
though  with  inadequate  methods,  and  out  of  their  efforts  arose 
the  earliest  schools  of  serious  psychological  investigation. 

Differences  between  experience  and  physical  facts.    An- 
other fundamental   motive  appeared   early  in   the  modern 


SCOPE  AND  METHODS  OF  PSYCHOLOGY          3 

period  as  a  direct  outgrowth  of  the  discovery  that  there  is 
a  disparity  between  the  facts  discovered  by  physical  science 
and  the  direct  testimony  of  consciousness.  Thus  Sir  Isaac 
Newton  discovered  that  he  could  break  up  white  light  into 
all  the  colors  of  the  rainbow.  Conscious  experience  of 
white  light  is,  on  the  contrary,  absolutely  simple  and  unana- 
lyzable.  Even  among  the  students  of  physical  science  there 
had  never  been  any  hesitation  up  to  the  time  of  Newton 
in  assuming  that  external  white  light  is  just  as  simple  as 
human  consciousness  of  whiteness.  The  ancients  had  a 
definite  explanation  of  vision  which  shows  that  they  explic- 
itly believed  in  the  simplicity  of  external  white  light.  Light 
was  for  them  a  series  of  particles  emanating  from  the  object 
and  entering  the  eye.  When  they  saw  white,  they  believed 
that  the  experience  was  due  to  white  particles  in  the  eye, 
and  that  these  white  particles  came  from  a  white  body.  All 
was  uninterrupted  likeness  from  the  physical  object  to  con- 
sciousness. Such  an  explanation  of  white  light  as  that 
offered  by  the  ancients  was  rendered  utterly  untenable  by 
Newton's  discovery.  When  further  investigations  led  physi- 
cists to  define  light  and  other  forms  of  physical  energy 
as  modes  of  vibration,  the  breach  between  conscious  experi- 
ence and  external  reality  became  so  wide  that  men  felt  com- 
pelled to  study  conscious  experience  as  well  as  physical  facts. 
It  is  noteworthy  that  the  period  during  which  Newton  and 
his  successors  were  making  their  discoveries  in  physics  was 
a  period  of  the  profoundest  interest  in  psychological  problems. 
Place  of  consciousness  in  evolution.  As  reinforcements 
to  the  impetus  given  to  psychological  study  by  discoveries 
in  physics,  new  motives  for  such  study  arose  with  the 
development  of  physiology,  and  especially  with  the  estab- 
lishment of  the  biological  doctrine  of  evolution.  Every 
highly  developed  function  of  an  animal  is  recognized  in 
biology  as  having  its  relation  to  the  struggle  for  existence. 
If  an  animal  can  run  well,  we  find  this  ability  serviceable 


4  VCHOLOGY 

in  saving  the  'animal  from  enemies,  or  in  helping  it  to 
procure  food.  If  an  animal  has  keen  vision,  we  find  that 
the  animal  depends  on  this  sense  in  the  esset  ities 

of  life.  With  such  facts  clearly  before  us,  we  cannot  escape 
the  question,  What  part  does  consciousness  play  in  the 
economy  of  1  '»m  the  lower  forms  of  animal  life  up 

to  the  highest,  we  find  a  steady  increase  in  the  scope  of 
intelligence.  In  the  highest  animals  we  find  mental  t 
tion  carried  so  far  that  intelligence  is  very  often  of  more 
significance  than  any  other  single  function  or  even  group 
of  functions.  Certainly  this  is  true  of  man.  The  digestive 
functions  of  a  man  differ  very  little  from  those  of  the 
higher  animals ;  the  muscles  and  bones  and  organs  of  cir- 
culation in  man  are  very  much  like  those  of  his  near  rela- 
I  in  the  animal  kingdom.  In  matters  of  intelligence,  on 
the  other  hand,  man  has  never  been  in  any  doubt  as  to  the 
wide  difference  between  himself  and  even  the  highest  of 
the  animals.  Man  lives  in  a  world  of  ideas  from  which 
animals  are  excluded  by  their  lack  of  intelligence  and  by 
their  lack  of  that  means  of  social  intercourse  which  is  the 
possession  of  man  alone,  namely,  language.  Furthermore, 
in  his  dealings  with  the  physical  world  man  discovered  the 
use  of  tools  through  which  he  has  been  able  to  reshape  his 
environment.  Man  has,  in  short,  through  his  conscious 
activities,  attained  to  a  mode  of  struggle  for  existence  which 
is  unique.  We  cannot  understand  and  explain  human  life 
and  human  institutions  without  studying  the  facts  and 
of  consciousness,  without  raising  the  question  of  the  relation 
of  consciousness  to  all  of  man's  other  attributes. 

The  first  method  of  psychology.  The  methods  of  psy- 
chological investigation  have  progressed  with  the  rise  of 
each  new  motive  for  the  study  of  conscious  life.  At  first, 
the  method  was  one  of  direct  self-observation.  This  method 
is  known  as  introspection.  When  one  has  an  emotion,  others 
may  see  its  external  expressions,  but  only  the  man  himself 


SCOPE  AND  METHODS  OF  PSYCHOLOGY          5 

can  observe  the  conscious  state  which  constitutes  the  emo- 
tion. In  looking  inward  and  observing  this  conscious  state, 
one  is  said  to  introspect. 

The  early  psychologists  were  so  impressed  with'  the 
importance  of  introspection  that  they  regarded  it  as  the 
sole  method  of  collecting  facts  for  their  science.  They  thus 
seriously  limited  the  scope  of  their  studies.  Mental  proc- 
esses are  fully  understood  only  when  the  relations  of  these 
inner  events  to  the  outer  world  are  taken  into  account. 
When  a  man  meets  his  friend  and  greets  him,  the  psychol- 
ogist is  interested  not  only  in  the  inner  fact  of  conscious 
recognition  but  also  in  the  impression  made  on  the  eye,  for 
it  is  in  this  impression  that  recognition  originates ;  further- 
more, the  psychologist  must  study  the  bodily  activities  of 
greeting  which  follow  recognition.  Indeed,  the  most  pro- 
ductive discoveries  of  modern  psychology  have  come  from 
a  study  of  the  setting  in  which  conscious  processes  belong. 

Nervous  processes  as  conditions  of  consciousness.  Thus 
we  see  that  among  the  facts  which  are  not  open  to  intro- 
spection but  are  of  importance  in  explaining  consciousness 
are  the  processes  which  go  on  in  the  organs  of  sense  and 
in  other  parts  of  the  nervous  system.  One  cannot  introspect 
brain  processes,  but  much  light  has  been  thrown  on  the  way 
in  which  men  think  by  a  study  of  both  the  structure  and 
action  of  the  brain. 

Studies  of  behavior.  Another  type  of  indirect  or  non- 
introspective  investigation  which  has  of  late  been  culti- 
vated with  very  great  advantage  to  psychology  deals  with 
the  facts  of  human  and  animal  behavior.  Here,  as  in  the 
examination  of  the  nervous  activities,  it  is  possible  to  dis- 
cover certain  stages  of  development  and  to  relate  these  to 
the  well-recognized  general  fact  that  there  are  progressive 
stages  of  intelligence  in  the  animal  kingdom. 

If  these  and  other  modes  of  indirect  study  of  mental  life 
are  judiciously  added  to  introspective  observations  of  one's 


6  PSY<  IIOLOGY 

own  conscious  processes,  psychology  loses  nothing  of  its 

-s,  and   it  gains   much   in   breadth. 
Overemphasis  of  slower  forms  of  mental  activity  through 

introspection.    A  turthcr  advantage  which  is  secured  In 
that   introspection  is  not  tin-  only  jx>ssiblc  im  • 
'Meeting  psycholoMR-a.  that  tin-  .ces  most 

tly  open   to   introspection  arc  thrown   into  a  truer 
spective  by  the  combination  of  indirect  and  direct  examina- 
tion.    The  student  who  depends  solely  on  introspection  will 
give  the  larm  of  his  attention  to  that  which  is  in  the 

foreground  ot  Dually  to  some  compU 

process  which  passes  slowly  across  t!.  of  const 

He    will    often    give    undue    weight   to   some   single 
Hence  because  it  is  so  clear,  adopting  this  clear  experi- 
ence as  typical,  and  depending  upon  it  for  the  cxplan 
of  many  of  the  less  obvious  facts  of  mental  life.    For  exam- 
ple, when  one  hears  a  word  and  stops  to  consider  deliber- 
ately the  conscious  process  by  which  he  interprets  the  * 
he  is  very  likely  to  experience  a  series  of  memory  images 
which  follow  upon  the  word  and  give  it  meaning.    Thu 
the  reader  ask  himself  what  he  thinks  of  when  he  sec 
word  "  house."    The  more  carefully  he  searches  in  his 
sciousness,-the  more  he  becomes  aware  of  trains  of  memory 
images.    Many  psychologists  having  made  this  introsrx 
observation  set  it  down  as  a  general  fact  of  all  mental  life 
that  the  process  of  recognition  always  consists  in  the  revival 
of  trains  of  memory  images.    If  the  skeptical  observer  ven- 
tures to  say  that  he  does  not  find  in  his  ordinary  recognition 
of  words  such  attendant  trains  of  memory   images,  he  is 
reproved  for  incomplete  introspection.    When  we  come  to 
the  problem  of  recognition  of  words  in  our  later  discussions, 
this  question  will  be  taken  up  in  detail,  and  it  will  be  shown 
that  what  is  needed  is  not  a  formula  borrowed  from  the 
more  elaborate,  easily  introspected  case,  in  which  recogni- 
tion  is  slow  and  long  drawn  out.    What  is  needed 


SCOPE  AND  METHODS  OF  PSYCHOLOGY          7 

formula  derived  from  a  study  of  habit.  When  we  become 
very  familiar  with  an  object  we  are  less  and  less  likely  to 
attach  to  it  trains  of  images  ;  we  respond  to  it  promptly  and 
skillfully  without  waiting  for  a  full  picture  to  be  developed 
in  the  mind.  So  it  is  also  with  words.  The  more  familiar 
the  word,  the  less  the  mind  delays  and  pictures  its  mean- 
ings. This  example  shows  that  psychology  must  not  adopt 
as  its  chief  bases  for  explanation  the  long-drawn-out  mental 
processes  which  furnish  the  most  content  for  introspection. 

Experiment  in  psychology.  When  psychology  is  recog- 
nized as  a  broad  science,  dealing  with  many  facts  related 
to  consciousness  as  well  as  with  consciousness  itself,  it  will 
be  understood  why  recent  studies  in  this  field  have  made 
liberal  use  of  experimental  methods.  Experiment  became 
a  conspicuous  method  in  psychology  about  fifty  years  ago. 
Prior  to  that  time  the  observations  of  psychologists  were 
limited  by  the  opportunities  of  personal  experience. 

Let  us  see  the  advantages  of  deliberate  experimentation 
by  canvassing  an  example.  A  psychologist  is  studying 
memory.  He  notes,  when  he  tries  to  recall  objects  which 
he  has  observed,  that  there  is  a  certain  incompleteness  in 
his  mental  reproduction  and  that  this  incompleteness  be- 
comes increasingly  impressive  with  the  passage  of  time.  He 
will  hardly  fail  to  find  out  by  this  sort  of  self-observation 
much  that  will  help  him  in  describing  his  processes  of 
memory.  Suppose,  however,  that  he  wishes  to  find  out 
with  definiteness  the  law  which  memory  exhibits  in  its 
decay,  or  suppose  that  he  wishes  some  final  decision  as  to 
the  best  way  of  examining  groups  of  objects  in  order  that 
he  may  carry  away  a  complete  and  permanent  memory  of 
them.  He  will  find  it  advantageous  for  this  more  complete 
study  to  arrange  the  objects  with  a  view  to  the  questions 
which  he  wishes  to  answer.  He  will  observe  the  objects 
during  a  fixed  period,  and  after  a  known  interval  will 
submit  his  memory  to  a  definite  test.  This  illustration  is 


8  I'M'    li 

sufficient  to  show  that  there  are  advantages  in  the  precise 
control  of  the  conditions  of  obser  -.vim  h  is  the  first 

step  in  experimentation.  It.  n<>\\,  the  psychologist  adds 
certain  aids  in  the  way  of  apparatus  which  will  m.i 
easy  to  record  the  time  intervals  and  t<>  present  the  matter 
to  be  memorized  in  absolutely  Uniterm  fashion,  it  will  be 
recognized  at  once  that  the  mou  tully  developed  and 
cise  method  of  in\ estimation  leads  to  a  degree  of  accuracy 
in  ascertaining  the  facts  which  is  otherwise  quite  impos- 
sible. The  experimental  method  also  makes  it  possible  for 
observers  remote  from  one  another  to  collect  their  observa- 
tions under  the  same  conditions,  so  that  they  can  compare 
their  results  and  generalize  the  information  which  they  have 
gathered. 

There  has  been  much  discussion  as  to  the  exact  place  of 
experiment  in  psychology,  some  holding  that  it  is  the  only 
true  scientific  method,  others  holding  that  it  is  very  limited 
in  its  application.  Those  who  are  most  devoted  to  experi- 
mental methods  have  sometimes  gone  so  far  as  to  assert 
that  experimental  psychology  is  a  separate  discipline.  Those 
who  criticize  the  method  point  out  that  the  profounder 
emotions,  such  as  intense  sorrow,  and  the  higher  forms  of 
abstract  thought,  such  as  are  involved  in  a  scientific  dis- 
covery, cannot  be  produced  and  modified  at  will.  Hoth 
extreme  positions  are  to  be  avoided.  Carefully  prearranged 
observation  under  controlled  conditions,  wherever  this  is 
possible,  is  the  true  ideal  of  scientific  psychology.  Where 
experiment  is  not  possible,  other  forms  of  observation  must 
and  should  be  employed. 

Explanation  at  variance  with  mere  observation.  It  may 
be  well,  both  for  the  sake  of  defining  the  scope  of  psychol- 
ogy and  for  the  purpose  of  illustrating  its  methods,  to  call 
attention  to  the  fact  that  this  science,  like  other  sciences, 
frequently  brings  out  in  its  explanations  facts  which  seem 
to  run  counter  to  direct  observation.  Thus,  before  we  study 


SCOPE  AND  METHODS  OF  PSYCHOLOGY          9 

any  of  the  physical  sciences,  we  observe  that  the  surface  of 
the  earth  about  us  is  apparently  flat.  As  we  progress  in 
science  we  come  on  facts  which  are  incompatible  with  the 
notion  that  the  earth  is  flat.  We  note  all  these  observations 
and  compare  them,  and  finally  accept  as  our  general  scien- 
tific conclusion  the  statement  that  the  earth  is  spherical  and 
not  flat,  as  it  seems  to  ordinary  observation.  Again,  we  do 
not  hesitate  to  accept  the  dictum  of  science  that  the  earth  is 
moving  at  a  tremendous  rate,  although  we  do  not  observe 
the  movement  directly.  These  illustrations  go  to  show 
that  scientific  conclusions  are  broader  in  scope  than  single 
observations,  and  frequently  so  different  from  the  single 
observations  as  to  constitute  essentially  new  facts. 


FIG.  i.    Diagram  for  use  in  demonstration  of  the  blind  spot  (see  page  10) 

When  we  leave  physical  science  where  we  have  learned 
easily  to  accept  the  results  of  inference,  and  turn  to  psy- 
chology, we  do  well  to  remember  that  earlier  generations 
less  trained  in  the  methods  of  science  found  it  difficult, 
indeed  quite  impossible,  to  substitute  inferences  about  the 
shape  and  motion  of  the  earth  for  the  facts  of  sense  ex- 
perience. We  should  therefore  be  prepared  by  the  con- 
sideration of  these  analogies  to  recognize  the  necessity  of 
comparison  and  interpretation  in  our  psychology  and  to 
overcome  our  own  hesitation  in  accepting  psychological 
inferences  as  substitutes  for  introspective  observations. 

A  simple  mental  experience  which  offers  an  excellent 
opportunity  for  the  application  of  the  principle  of  inference 
is  as  follows  :  Let  an  observer  close  one  eye  and  look  with 
the  open  eye  at  the  printed  page  before  him.  He  will 
undoubtedly  observe  what  seems  to  be  an  uninterrupted 


10  l'>\'    li 

series  of  impressions  coming  to  him  from  all  parts  of  the 
page.    This  is.  :  quite  as  incomplete  a  description 

of  thr  tai-is  as  is  the  description  of  the  earth's  surface 
based  upon  direct  observation.  To  demonstrate  this,  let 
tlu-  observer  close  or  cover  the  left  eye  and  look  steadily 
with  the  right  eye  at  the  small  cross  in  1  Sg,  i  Now  let 
him  move  the  book  backward  and  forward  from  seven  to 
eight  inihes  in  front  of  his  face  until  the  black  circle  dis- 
appears. Me  will  thus  discover  that  a  certain  part  of  the 
page  is  not  yielding  an  uninterrupted  series  of  impress 
The  explanation  of  the  facts  here  involved  cannot  be  ob- 
tained through  introspective  observation,  for  it  depends  on 
the  structure  of  the  eye,  there  being  in  the  sensory  surface 
of  the  eye  an  area  that  cannot  receive  impressions.  This 
is  the  area  where  the  optic  nerve  leaves  the  eye.  This  illus- 
tration should  prepare  the  student  to  find  in  the  science  of 
hologv  many  statements  about  the  nature  of  his  conscious 
processes  which  he  cannot  expect  to  verify  by  a  simple  proc- 
ess of  observation.  Observation  is  indispensable,  but  the  sci- 
entific understanding  of  consciousness  requires  an  elaborate 
interpretation  of  all  the  facts  which  can  be  obtained. 

Subdivisions  of  psychology.  Psychology  as  a  science 
dealing  in  a  broad  way  with  conscious  processes  and  with 
the  conditions  and  results  of  these  processes  has  proved 
to  be  most  fruitful  in  its  applications.  Wherever  human 
nature  is  to  be  influenced,  whether  it  be  in  the  writing  of 
an  advertisement  or  in  convincing  a  jury,  the  psychology  of 
the  process  is  worth  understanding.  If  the  study  of  the 
process  can  be  made  exact  through  experimentation  and 
comparison,  applications  will  be  the  safer  and  more  effec- 
tive. There  has  been  in  recent  years  a  vigorous  cultivation 
of  psychology  in  all  its  possible  forms  and  in  all  its  possible 
applications.  Thus,  there  is  a  psychology  of  animal  con- 
sciousness. There  is  a  psychology  of  the  child's  conscious- 
ness, especially  cultivated  by  those  who  wish  to  ascertain 


SCOPE  AND  METHODS  OF  PSYCHOLOGY        II 

the  laws  of  mental  development  which  underlie  education. 
There  is  a  psychology  of  abnormal  human  minds  known  by 
the  special  name  of  psychiatry.  There  is  a  psychology  of  the 
products  of  human  minds  when  they  act  in  social  groups, 
as  in  the  development  of  language,  customs,  and  institutions. 
This  is  called  social  psychology  or  folk  psychology.  Certain 
other  lines  of  subdivision  are  sometimes  drawn.  Thus, 
experimental  psychology  has  sometimes  been  marked  off 
from  other  forms  of  investigation.  Physiological  psychology 
has  also  been  treated  as  a  separate  science.  Finally,  it  is 
not  uncommon  to  meet  such  titles  as  the  psychology  of  art, 
or  of  literature  ;  the  psychology  of  religion,  of  the  crowd ; 
and  so  on  through  a  long  list  of  highly  differentiated 
specialties. 

Some  confusion  has  resulted  because  of  the  tendency 
of  psychology  to  break  up  into  so  many  minor  disciplines. 
The  confusion  disappears,  however,  as  soon  as  one  recog- 
nizes that  in  methods  and  subject  matter  all  the  special 
psychologies  are  merely  parts  of  the  general  science.  The 
explanation  of  the  subdivisions  is  partly  historical.  As  new 
interests  or  new  methods  have  asserted  themselves,  the 
traditions  of  the  earlier  stage  of  psychology  have  often 
resisted  the  innovation  to  such  a  degree  that  a  new  disci- 
pline was  for  a  time  necessary  to  accomplish  the  develop- 
ment of  the  science.  In  addition  to  these  historical  reasons, 
the  breadth  of  human  interests  in  the  study  of  experience 
is  so  great  that  the  mastery  of  any  single  phase  of  mental 
life  involves  a  concentration  somewhat  more  pronounced 
than  that  which  is  required  in  many  sections  of  the  physical 
sciences. 

Summary  and  definition  of  psychology.  The  special  de- 
partments of  psychology  cannot  all  be  fully  treated  in  a 
general  course,  such  as  that  which  is  to  be  given  in  the 
following  chapters.  Much  can  be  touched  upon  only  by  way 
of  illustration.  The  general  treatment  must  confine  itself  to 


12 

the  establishment  of  broad  principles  applicable  in  greater 
or  less  degree  to  all  of  the  special  fields.    With  this  neces- 

of  general  exposition  in  mind,  the  statement  with  i 
this  introductory  chapter  began  may  be  amplified  as  follows: 
The  legitimate  function  of  a  course  in  general  psychology 
is  to  consider  the  typical  processes  of  mental  life  with  refer- 
ence to  their  internal  constitution  and  also  with  reference  to 
their  external  conditions  ;  to  examine  these  processes 
the  aid  of  experiments  and  observations  from  both  the  intro- 
spective and  impersonal  points  of  view;  and,  finally,  to  relate 
consciousness  to  the  other  phases  of  life,  especially  to  human 
and  animal  behavior,  and  also  to  external  reality  in  such  a 
way  as  to  furnish  the  basis  for  an  adequate  understanding 
not  only  of  individual  consciousness  but  also  of  the  experi- 
ence of  all  conscious  beings. 

Definitions  of  certain  general  psychological  terms.  In  this 
statement  and  throughout  the  chapter  the  terms  "conscious- 
ness," "mental  life,"  and  "experience"  have  been  used  with- 
out any  effort  to  define  them.  Complete  critical  definitions 
of  these  terms  presuppose  a  knowledge  of  the  results  of 
psychological  study,  for  it  is  the  function  of  psychology  to 
ascertain  the  characteristics  of  consciousness.  In  the  mean- 
time there  is  no  clanger  of  confusion  in  the  preliminary  use 
of  the  terms.  Consciousness  is  what  each  one  of  us  has 
when  he  sees  and  hears,  when  he  feels  pleasure  or  sorrow, 
when  he  imagines  or  reasons,  or  decides  to  pursue  a  line  of 
action.  Experience  is  a  general  word  which  may  conven- 
iently be  used  to  cover  the  same  group  of  facts.  Stones  do 
not  experience  impressions  or  emotions.  Man,  on  the  other 
hand,  lives  in  a  world  of  experiences.  His  inner  life  is  not 
made  up  of  objects,  but  of  experiences  of  objects.  When- 
ever we  think,  or  remember,  or  try  to  understand  an  object 
presented  to  the  senses,  we  have  an  experience.  As  pointed 
out  in  the  discussion  of  introspection,  conscious  processes 
may  be  distinguished  from  other  facts  by  the  possibility  of 


SCOPE  AND  METHODS  OF  PSYCHOLOGY        13 

self-observation  or  introspection,  by  which  method  alone 
these,  conscious  facts  can  be  directly  observed.  Facts  of 
external  reality  are  open  to  general  observation  by  many 
different  individuals ;  conscious  experiences  are  purely  per- 
sonal, open  to  introspective  observation  only.  We  sometimes 
express  the  contrast  between  the  facts  of  conscious  experi- 
ence and  the  facts  of  external  reality  by  the  use  of  the  terms 
"subjective"  and  "objective."  Whatever  belongs  exclusively 
to  the  world  of  experience  is  called  subjective.  Thus,  ideas 
and  feelings  are  subjective.  The  facts  with  which  physics 
and  chemistry  deal  are  not  exclusively  subjective ;  they  have 
objective,  external  characteristics.  Indeed,  physics  and  chem- 
istry are  interested  in  facts  only  in  so  far  as  they  are  objec- 
tive. For  these  natural  sciences  the  subjective  ideas  of  the 
individual  physicist  or  chemist  are  merely  the  means  to  an 
end,  which  end  is  the  intelligent  comprehension  of  the  ob- 
jective world.  The  same  antithesis  which  is  expressed  by 
the  terms  "  subjective  "  and  "  objective  "  is  expressed  by  the 
terms  "psychical  facts"  and  "physical  facts."  The  former 
are  the  directly  known  conscious  processes ;  the  latter  are 
the  facts  of  the  external  world  as  known  through  the  senses 
and  as  studied  in  the  objective  sciences.  These  remarks  on 
the  various  terms  which  are  used  in  defining  the  sphere  of 
psychology  serve  to  indicate,  in  a  sufficiently  unambiguous 
way,  the  direction  in  which  our  studies  must  turn. 


CHAPTI.R    II 

THK    I'.oDIIN    CONDITIONS  OI     I'.KHAVIOR 

AND  I. \ITKII  M  1 

The  introspective  approach.    There  are  two  lines  of  pro- 
cedure which  may  be  adopted  in  the  study  of  mental  ; 
esses.    On  the  one  hand,  we  can  begin  with  the  descri; 
of  some  personal  experience  and  from  this  central  fact  move 
outward  until  we  arrive  at  a  full  explanation  of  all  the  causes 
and  conditions  of  this  experience.    Thus,  when  I  try  to  re- 
member the  name  of  a  person  whom  I  met  some  time  ago, 
I  find  that  I  can  recall  the  vague  general  fact  that  it 
a  short  name,  beginning  with  the  letter  "  I-".,"  but  it  re(j 
time  and  effort  to  fill  in  the  rest.    The  questions  which  im- 
mediately arise  are  such  as  these  :  Where  is  the  st 
in  which  these  memories  were  locked  up  ?    Why  did  one 
part  of  the  name  drop  away  and  another  part  persist?    What 
kind  of  effort  is  necessary  to  bring  out  the  missing  j 
Kvidently  it  will  he  necessary,  before  these  questions  can 
be  answered,  to  go  outside  of  immediate  consciousm 

Indirect  method  of  approach  to  psychological  facts. 

:ul  line  of  procedure  is  the  reverse  of  that  just 
scribed.  We  can  approach  personal  experience  from  without, 
reviewing  briefly  the  conditions  which  make  such  experi- 
ence possible  and  gradually  coming  to  the  particular  facts 
which  at  this  moment  fill  the  observer's  mind.  This  mode 
of  taking  up  the  study  has  the  disadvantage  of  leaving 
the  student  with  the  impression  that  psychology  is  very 
remote  from  his  inner  experiences.  On  the  other  hand,  it 
has  the  advantage  of  supplying  him  from  the  first  with  a 

'4 


BODILY  CONDITIONS  15 

body  of  facts  which  he  is  not  able  to  contribute  out  of  his 
direct  observation  of  himself.  Some  patience  will  be  required 
in  coming  thus  indirectly  to  the  study  of  mental  processes, 
and  the  student  will  need  to  keep  in  thought,  with  very  little 
aid  from  the  text,  the  goal  toward  which  the  preliminary 
study  is  leading. 

The  indirect  method  is  the  one  with  which  we  shall  be- 
gin. We  shall  take  up,  first,  the  facts  of  animal  behavior 
and  nervous  organization  and  shall  thus  lay  the  foundations 
for  an  explanation  of  the  facts  of  personal  experience.  Later 
we  shall  review  the  facts  of  consciousness  itself  in  the  light 
of  this  preliminary  indirect  study. 

Characteristics  of  unicellular  animals.  Our  method  car- 
ries us  back  to  the  most  primitive  forms  of  animal  life. 
Here  we  find  minute  microscopic  beings  whose  whole  body 
consists  of-  a  single  cell.  This  cell  is  made  up  of  a  mass 
of  living  tissue  known  as  protoplasm.  Such  a  unicellular 
animal  is  capable  of  moving  about  by  contracting  its  tissue ; 
it  is  capable  of  reproducing  itself  by  cell  division  ;  it  is  capa- 
ble of  digesting  food  and  throwing  out  waste  matter ;  and, 
finally,  it  is  irritable  when  acted  upon  by  external  forces. 
When  the  student  examines  life  reduced  to  the  low  terms 
which  are  exhibited  in  a  unicellular  animal,  he  realizes 
more  fully  than  he  is  likely  to  realize  when  examining 
higher  forms  how  thoroughly  interdependent  are  all  the 
phases  of  an  animal's  life.  Consider  how  impossible  life 
would  be  without  the  new  supply  of  energy  which  comes 
through  digestion  ;  how  limited  in  scope  life  would  be  with- 
out movement  to  bring  the  animal  to  new  sources  ef  food 
and  carry  it  out  of  danger,  or  without  cell  division  to  in- 
crease the  number  of  members  in  the  species ;  and  how 
utterly  out  of  contact  with  the  rest  of  the  world  the  indi- 
vidual would  be  without  irritability.  The  fact  that  all  these 
functions  appear  in  the  simplest  unicellular  forms  shows 
how  fundamental  they  are. 


16 


PSYCHOLOGY 


Simplest  types  of  behavior.  The  only  facts  on  which  we 
can  base  a  judgment  with  regard  t«»  tlu-  iniu-r  processes  in 
such  an  animal  are  the  facts  of  behavi»i.  These  appear  to 
be  very  simple.  The  animal  has  three  forms  of  movement. 
It  swims  forward  and  takes  in  food.  If  it  encounters  a 
stimulus  which  is  unfavorable,  such  as  heat  or  acid,  it  darts 
backward  and  swings  around  in  a  direction  which  takes  its 
mouth  opening  away  from  the  stimulus.  Fig.  2  shows  a 

series  of  movements  as  exe- 
cuted by  such  an  animal.  The 
figure  represents  one  end  of 
a  microscope  slide  which  is 
heated  at  the  upper  edge. 
A  unicellular  organism,  Oxyt- 
richa,  in  the  position  I  is 
reached  by  the  heat  coming 
from  the  upper  part  of  the 
slide.  The  animal  reacts  by 
turning  to  the  right  (position 
2).  This  intensifies  the  i 
tation  caused  by  the  heat,  and 
the  animal  backs  to  position  3. 
It  then  turns  (position  4)  and 
swims  forward  (position  5), 
again  encountering  the  ! 
It  then  darts  back  (position  6),  turns  (position  7),  and  swims 
forward  until  it  comes  against  the  wall  of  the  trough  (posi- 
tion 8).  It  then  reacts  as  before,  by  backing  (positions  8-9), 
and  turning  to  the  right  (positions  9-10).  This  type  of 
reaction  continues  as  long  as  its  movements  carry  it  either 
against  the  wall  or  into  the  heated  region.  When  it  finally 
gets  away,  as  it  must  in  time  if  it  continues  its  reactions, 
it  swims  forward,  taking  food  as  it  did  before  disturbed. 
Thus  we  see  that  there  are  in  the  lowest  animals  very  limited 
possibilities  of  behavior. 


FIG.  2.    Movements  of  a  unicellular 
animal.    (After  Jennings) 


BODILY  CONDITIONS  17 

Consciousness  no  more  complex  than  behavior.  This 
meager  repertoire  of  behavior  betokens  a  relatively  undif- 
ferentiated  inner  life.  Yet  even  this  animal  is  influenced 
by  the  impressions  made  upon  it  by  the  outer  world.  We 
may  think  of  the  heat  as  setting  up  a  commotion  among 
the  molecules  which  make  up  the  body,  and  this  inner 
commotion  results  in  a  recoil.  We  distinguish  between  the 
irritability  of  the  animal  and  its  power  of  movement,  but  in 
reality  these  two  functions  are  one.  The  animal  recoils 
because  it  is  internally  aroused  by  the  heat.  Once  the 
extraordinary  condition  is  removed,  the  animal  begins  to 
exhibit  its  more  peaceful  form  of  behavior,  namely,  that 
of  swimming  forward,  this  evidently  being  the  natural  ex- 
pression of  its  calmer  inner  condition. 

It  is  hardly  possible  for  us  to  imagine,  in  terms  of  our 
own  consciousness,  what  must  be  the  inner  experience  of 
such  an  animal,  if,  indeed,  we  have  any  right  to  think  of 
it  as  having  experience.  Certainly  a  unicellular  animal  can 
have  discriminations  only  of  the  grossest  sort.  When  all  is 
well  and  the  animal  is  swimming  forward  and  taking  food, 
the  inner  state  must  be  one  of  well-being.  When  the  shock 
of  a  strong  stimulus  comes,  there  must  be  a  kind  of  vague 
inner  excitement.  The  two  inner  states  probably  differ  just 
in  the  degree  in  which  the  forms  of  behavior  differ. 

Behavior  more  limited  than  sensitivity.  If  we  study  such 
animals  with  respect  to  irritability,  we  find  that  they  respond 
to  various  forms  of  external  energy.  Thus,  if  light  falls  on 
the  water,  some  species  will  collect  in  the  darkness,  others 
in  the  light,  in  such  numbers  as  to  indicate  clearly  in  either 
case  that  they  are  affected  by  the  light.  Again,  pressure 
due  to  contact  with  external  objects,  as  shown  above,  and 
also  vibrations  of  the  water  are  effective  in  producing  more 
or  less  intense  movements.  Acids  or  other  strange  chemical 
substances  in  the  water  will  produce  reactions  similar  to 
those  called  out  by  heat.  In  all  these  cases  the  animal 


IS 


exhibits  only  a  few  fixed  forms  of  reaction.    Our  inft : 
is   that    the   inner   processes  aroused   by  ail    • 
forms  of  energy  u-  The  fiuther  inference  is  that  the 

animal  discriminates  between  that  which  calls  for  forward 

.  ement  and  that  u  hu  h  calls  for 
withdrawal,  but  is  not  able  to  make 
any  finer  discriminations. 

The  study  of  unicellular  organ- 
isms leaves  us,  then,  with  four 
important  general  facts  on  which 
to  base  our  study.  Irritability  is 
a  fundamental  function  of  < 
the  lowest  forms  of  protoplasm ; 
it  is  at  first  very  little  differenti- 
ated ;  it  is  the  function  which 
guides  the  animal  in  its  responses 
to  its  environment ;  and,  finally. 
the  description  of  behavior  is  a 
very  direct  means  of  arriving  at 
an  understanding  of  the  inner 
processes  of  irritability. 

Specialization  of  cell  structures 
and  functions  in  higher  animals. 
Turning  now  from  the  unicellular 


3.  The  hydra 

The  figure  shows  a  section  through 
the  body  and  exhibits  the  two  cellu- 
lar layers  with  a  neutral  layer 
between.  The  general  bcxi 
G  is  lined  by  cells  which  are 
devoted  entirely  to  the  special 
function  of  digestion  (the  mouth 

opening  is  at  .»/).  K,  K,  K,  K    animal  to  a  form  somewhat  higher 

in  the  scale,  we  find  that  structur- 
ally the  more  highly  developed 
animals  are  characterized  by  the 
fact  that  their  bodies,  instead  of 
consisting  of  a  single  cell,  consist  of  an  aggregation  of  cells  ; 
this  we  express  by  the  statement  that  they  are  multicellular  or- 
ganisms. Fig.  3  represents  a  section  of  a  simple  multicellular 
animal  which  lives  in  fresh  water  and  is  known  as  a  hydra. 
The  animal  is  sack-shaped,  with  a  mouth  opening  and  ten- 
tacles at  its  upper  end.  The  figure  shows  the  walls  of  the 


are  the  reproduction  cells.  The 
outer  wall  of  the  body  is  made 
up  of  muscle  cells  and  specialised 
sensitive  cells.  T,  T,  T  are  the 
tentacles.  (Adapted  from  Hallcr) 


.      BODILY  CONDITIONS  19 

sack-shaped  body  much  magnified.  The  inner  lining  of  this 
wall  is  made  up  of  a  layer  of  cells  which  are  specialized  to  per- 
form the  function  of  digestion.  The  outer  wall  is  specialized 
in  certain  of  its  cells  for  the  reception  and  transmission  of 
stimulations,  and  in  other  cells  for  the  performance  of  move- 
ments. The  processes  of  reproduction  are  provided  for  at 
special  points  in  the  body  wall  as  indicated  at  R,  R,  R,  R, 
in  Fig.  3.  Between  the  inner  and  outer  layers  there  is  an 
intermediate  layer  of  tissue,  in  which  cells  sometimes  appear 
from  one  of  the  primary  layers.  The  intermediate  layer  is  not 
sufficiently  developed  to  constitute  a  separate  series  of  organs. 
The  multiplication  of  cells  and  specialization  of  functions 
here  exhibited  have  advantages  familiar  to  anyone  who  has 
observed  the  analogous  fact  of  division  of  labor  in  social 
organizations.  The  cells  of  the  body  which  are  set  apart  for 
special  purposes  do  not  lose  the  general  characteristics  which 
belong  to  all  living  protoplasmic  cells.  For  example,  all  the 
cells  of  the  body  absorb  the  necessary  nutrition  to  support 
their  individual  lives,  but  the  cells  outside  of  the  digestive 
layer  do  not  take  their  nutrition  from  the  external  world ; 
they  derive  it  from  the  digestive  cells  which  alone  perform 
the  special  function  of  digesting  foreign  particles.  So  also 
with  the  function  of  irritability.  This  is  not  lost  by  the 
specialized  contractile  cells  and  digestive  cells ;  it  is  merely 
reduced  in  these  cells  to  a  very  low  point  and  is  very  highly 
developed  in  the  specialized  sensitive  or  irritable  cells,  so 
that  the  movement  cells  or  muscle  cells  and  all  other  parts 
of  the  body  come  ultimately  to  receive  their  impressions 
from  the  outer  world,  not  directly,  but  through  the  neural 
or  sensory  cells.  The  neural  cells  or  nerve  cells  are  special- 
ized cells  which  take  over  the  function  of  irritability.  They 
are  placed  in  the  outer  body  wall,  where  they  are  in  the 
most  favorable  position  to  be  acted  upon  by  external  forces 
or  stimuli,  as  forms  of  energy  which  affect  the  nervous  sysr 
tern  are  technically  called.  They  develop  a  more  complex 


-•< 


chemical  structure  than  the  other  cells  of  the  body,  so 
they  are  more  easily  set  in  action  by  external  forces.   '1 

accordingly,  highly  imjx>rtunt,  but  by  no  means  inde- 
pendent factors  in  the  organic  economy.  They  arc  developed, 
not  for  some  remote  and  separate  life  of  mere  irritability  or 
sensitivity,  but  as  essential  parts  of  the  developing  organ 
acting  as  paths  through  which  external  forces  enter  the  body 
and  cause  inner  states  which  will  adapt  the  animal  in  its  ;i 

to  the  world  in  which  it  lives. 
•n  in  the  simple  organism 
under  consideration,  the  process 
of  specialization  has  advanced  so 
far  that  there  lx-^in  to  appear 
various  classes  of  neural  or  irri- 
table cells,  each  serving  a  special 
function.  Certain  of  these  cells 
serve  the  direct  function  of  re< 
ing  impressions  from  the  outer 
world,  and  are  known  as  sensory 
cells,  while  others  serve  the  func- 
tion of  transmitting  the  impulse  to 
the  muscle  cells.  Fiij.  4  shows  a 
much-enlarged  section  of  the  outer 
body  wall  of  a  hydra.  ,17  is  a  mus- 
cle cell,  heavy  and  elongated  to 
make  more  effective  the  contractile 
function.  5  is  a  sensory  cell  which  receives  impressions. 
C,  C,  C,  Care  intermediate  transmitting  cells,  and  F,  together 
with  the  other  fibers  shown,  carry  the  impression  through  C 
from  5  to  M. 

Specialized  nervous  processes.  The  process  which  goes 
on  in  the  neural  cells  may  be  described  as  follows  :  Some 
form  of  external  energy  acts  upon  the  cells.  The  external 
energy,  as  noted  above,  is  called  a  stimulus.  This  sets  up 
a  chemical  process  in  the  cell  which  is  known  as  a  process 


FIG.  4.  Much-enlarged  section 
of  a  muscle  cell  and  a  sensory 
cell  of  a  hydra,  together  with 
the  connecting  cells  which  lie 
between  them 

Af,  muscle  cell ;  A",  sensory  cell ; 
C,  intermediate  cells;  F,  fiber 
connecting  the  sensory  cells  with 
the  central  cells.  (Adapted  from 
Mailer) 


BODILY  CONDITIONS  21 

of  excitation  or  a  stimulation.  The  process  of  excitation 
liberates  energy  which  was  stored  up  in  the  cell.  This 
liberated  energy  is  transmitted  to  other  cells  in  the  body, 
either  to  the  secondary  transmitting  neural  cells,  C,  C,  or  to 
the  active  contractile  cells  such  as  M.  This  current  of 
nervous  energy  has  been  compared  to  an  electric  current. 
It  is,  however,  much  slower  than  an  electric  current,  its  rate 
of  transmission  being  in  the  higher  animals  about  one 
hundred  meters  per  second  or  less.  We  do  not  know  its 
exact  character,  but  probably  it  is  more  like  the  succession 
of  combustions  which  takes  place  along  the  line  of  a  fuse 
of  gunpowder.  Our  ignorance  of  the  exact  nature  of  the 
nervous  current  need  not  delay  the  discussion,  however,  for 
we  shall  find  that  the  importance  of  nervous  currents 
for  our  further  study  depends  upon  their  paths  of  trans- 
mission rather  than  on  their  chemical  nature.  The  path  of 
transmission  will  be  determined  primarily  by  the  direction 
and  connections  of  the  fibers  which  unite  the  cell  in  which 
a  given  excitation  originated  with  other  parts  of  the  body ; 
secondarily,  the  path  of  transmission  will  depend  on  the 
fatigued  or  unfatigued  condition  of  the  cells  and  on  the 
other  currents  of  energy  which  are  flowing  through  the  system 
at  the  same  time.  All  these  complex  possibilities  may  be 
summed  up  in  the  statement  that  in  its  transmission  through 
the  neural  organs  every  nervous  excitation  is  directed  and 
is  combined  with  other  impulses,  and  is  ultimately  determined 
in  its  effects  by  its  path  of  transmission  to  the  muscles  or 
glands  and  by  its  relation  to  other  impulses.  Furthermore, 
as  soon  as  it  is  recognized  that  nervous  impulses  consist  in 
currents  of  energy  which  have  been  liberated  by  the  stimulus, 
it  will  be  recognized  that  every  nervous  current  must  pro- 
duce some  effect  before  it  is  dissipated ;  for  a  current  of 
energy  must  do  some  work  —  it  cannot  disappear.  The 
effects  produced  by  nervous  impulses  are  of  two  kinds. 
First,  the  energy  may  be  absorbed  in  the  course  of  its 


22 

transmission,  in  which  case  it  will  produce  changes  in  the 
i.. n. In i. >n  of   tin-   nervous  tissue,  thus  contributing  to  the 
modification  of  the  structure  of  that  tissue.    Second,  it  may 
be  carried  to  the  natural  outlet  of  all  nervous  ex 
namely,  the  active  or-  he  body,  where  it  will  produce 

some  form   of   behavior.     If   it   contributes  to  change 
structure,  these  changes  in  structure  will  ultimately  influ- 
ence new  incoming  impulses  which  are  on  the  way  to  the 
active  organs.    We   may  therefore  say  that,  directly  or  in- 
directly, all  incoming  nervous  impulses  are  transmitted  to 
the    active  organs  of   the  body  after   Ixrin^   more  or  less 
completely  redirected  or  partially  used  to  produce  stru« 
changes  in  the  nervous  organs. 

Nervous  processes  of  three  distinct  types.  The  range  of 
nervous  processes  possible  in  the  simple  structures  of  a 
hydra  is  extremely  limited  ;  for  this  very  reason  the  funda- 
mental characteristics  of  nervous  processes  are  all  the  more 
apparent.  We  can  distinguish  clearly  the  first  step  which 
is  the  reception  of  the  external  stimulus.  This  first  step 
is  commonly  described  as  a  sensory  nervous  process.  The 
cell  on  which  the  stimulus  acts  is  a  receiving  cell.  The  in- 
termediate cells  placed  between  the  receiving  cell  and  the 
muscle  are  called  transmitting  cells  or  central  cells.  The 
fibers  passing  from  the  central  cells  to  the  muscle  or  gland 
are  motor  fibers.  It  will  be  seen  that  the  sensor)-,  central, 
and  motor  processes  cannot  be  sharply  distinguished  from 
each  other ;  they  are  all  phases  of  a  single  continuous 
process,  the  end  of  which  is  always  some  active  process  in 
the  muscles ;  but  for  purposes  of  scientific  explanation  it  is 
necessary  to  distinguish  them  as  three  distinct  types. 

Behavior  varied  and  much  more  complex.  If  we  contrast 
the  hydra  with  the  unicellular  organism  studied  in  earlier  para- 
graphs, we  are  at  once  impressed  by  the  fact  that  the  hydra 
has  a  greater  varietv  of  forms  of  behavior.  To  be  sure,  all 
these  forms  of  behavior  belong  under  two  fundamental  types, 


BODILY  CONDITIONS  23 

namely,  that  of  moving  forward  to  capture  food  and  that  of 
withdrawing  from  danger.  But  each  of  these  fundamental 
forms  of  action  has  been  developed  so  that  it  is  more 
elaborate  and  varied  than  it  was  in  the  unicellular  animal. 
Thus  the  tentacles  move  in  such  a  way  as  to  sweep  food 
into  the  mouth,  and  they  contract  in  the  presence  of 
unfavorable  stimuli,  even  when  the  body  as  a  whole  is  not 
in  full  action.  The  body  moves  sideways,  now  in  one 
direction,  now  in  another.  In  short,  the  more  complex 
animal  is  characterized  by  an  increasing  variety  of  action. 

Not  only  so,  but  an  action  often  consists  of  a  series  of 
related  movements,  making  a  complex  chain  of  acts,  all 
directed  toward  a  single  end.  The  body,  for  example, 
comes  in  contact  with  a  piece  of  food.  The  animal  swings 
around,  the  tentacles  seize  the  particle,  sweep  it  into  the 
mouth,  and  the  inner  digestive  canal  closes  in  on  it  and 
begins  its  ingestion.  Such  a  chain  of  cooperating  acts 
shows  that  a  high  level  of  evolution  of  behavior  has  been 
reached  where  single  elements  of  behavior  are  :  united  into 
complex  coordinations. 

From  this  point  on  we  shall  dwell  chiefly  on  the  structural 
growth  of  the  nervous  system,  but  the  statements  made 
regarding  the  behavior  of  hydra  should  be  thought  of  as 
repeated  and  even  as  amplified  to  correspond  to  each 
progressive  complication  of  nervous  structures. 

Progressive  evolution  in  both  structure  and  behavior. 
When  we  turn  from  the  hydra  to  the  higher  forms  of  life, 
we  find  that  the  multiplication  and  specialization  of  cells  go 
on  to  the  highest  degree,  producing  in  the  animals  at  the 
upper  end  of  the  scale  a  variety  of  forms  of  sensitivity  and 
of  behavior  which  culminate  in  such  capacities  as  those 
exhibited  in  man. 

Centralized  nervous  system.  We  must  confine  our  survey 
to  a  few  of  the  major  facts  in  this  process  of  evolution.  As 
we  ascend  the  scale,  there  is  a  grouping  of  the  central  cells 


into  complex  organs  and,  second,  a  differentiation  of  the 
receptive  or  sensory  cells  resulting  in  the  production  of 
special  organs  for  the  reception  of  a  great  variety  of  stimuli 
such  as  light,  sound,  tastes,  odors,  and  other  forms  of 
energy.  These  two  types  of  development  may  advantageously 
be  considered  in  succession.  For  the  remainder  of  this 
chapter,  the  differentiation  of  the  sense  organs  will  be 

passed  over  and  the  evolu- 
tion of  the  central  organs 
will  be  briefly  sketched. 

The  nerve  cells  of  the 
hydra  are  scattered  diffusely 
throughout  the  body  wall ; 
there  is  no  special  part  of 
the  body  in  which  the  cen- 
tral cells  are  massed.  The 
higher  animals  all  have  a 
more  or  less  highly  cen- 
tralized nervous  system.  A 
simple  type  of  centralization 
is  seen  in  the  starfish. 
Fig.  5  shows  the  general 


FIG.  5.  Outline  of  a  starfish,  and  nerv- 
ous system  of  the  same 


Each  arm  of  the  starfish  is  supplied  with      outline  of  this  animal's  body 

a  series  of  nerve  cells  indicated  by  the 

lines  passing  through  the  various  arms. 

From  these  nerve  cells,  fibers  extend  to 

the  surface  and  receive  sensory  impulses 

and  send  out  motor  impulses.  ( After  Loeb) 


and  the  distribution  of  the 
central  nervous  cells, 
double  line  represents  a 
group  of  cells.  It  will  be 
seen  that  there  is  for  each  arm  a  central  group  of  cells,  to 
which  sensory  excitations  come  from  the  surface  of  the  body 
and  from  which  motor  impulses  go  out  to  the  muscles. 
There  is  also  a  central  ring  which  binds  together  the  differ- 
ent arms  and  centralizes  in  a  still  higher  degree  the  whole 
animal.  This  ring  is  in  the  neighborhood  of  the  mouth 
opening,  and  its  function  is  undoubtedly  that  of  controlling 
the  whole  animal  in  taking  food. 


BODILY  CONDITIONS 


Q 


Another  type  of  Centralization  appears  in  any  one  of  the 
segmented  animals,  such  as  an  insect.  Fig.  6  shows  such  a 
centralized  nervous  system.  Each  segment  has  its  group  of 
central  cells,  and  all  the  segmental  centers  are  related  by 
connecting  fibers  to  one  another  and  to  the  highly  developed 
group  of  cells  in  the  first  segments, 
which  are  near  the  mouth  opening. 

Coordinating  center  of  the  body. 
The  development  of  a  complex  cen- 
tral nervous  system  is  of  the  high- 
est importance  in  animal  life.  As 
we  have  seen,  the  body  cells  of 
the  higher  animals  are  specialized. 
There  must  be  some  central  con- 
trolling group  of  cells  or  the  body 
would  not  be  able  to  carry  on  its 
manifold  functions  in  a  unified  and 
harmonious  fashion.  The  central 
nervous  system  is  the  controlling 
and  unifying  organ.  The  arms  of 
the  starfish  are  made  to  serve  the 
mouth  because  the  mouth  ring  of 
nerve  cells  is  the  dominating  organ 
of  the  body.  In  the  beetle  all  the 
organs  of  locomotion  are  made  to 
serve  the  head,  which  is  both  the 
entrance  to  the  alimentary  canal  and 
the  seat  of  the  important  special 
organs  of  sense,  namely,  the  eyes  and  the  feelers.  The 
central  nervous  system  reproduces  in  outline  the  whole  body 
and  is  a  connecting  tract  through  which  stimulations  are 
carried  from  one  organ  to  the  other. 

It  is  hardly  necessary  to  reiterate  the  statement  made  above 
that  this  evolution  of  nervous  structures  is  paralleled  by  an 
evolution  in  behavior.  The  number  of  acts  of  which  an  insect 


G 


FIG.  6.  A  stag  beetle,  show- 
ing the  outline  of  the  body 
and  the  distribution  of  the 
nerve  cells  and  fibers 

Each  segment  of  the  body  has 
a  ganglion  of  cells  G,  G,  G, 
from  which  fibers  F,  F,  F  are 
distributed  to  the  surface  of 
the  body  for  the  reception  of 
stimulations  and  the  distribu- 
tion of  motor  impulses.  The 
ganglion  in  the  front  section 
of  the  body  is  double  and  of 
greater  importance  than  those 
in  the  posterior  segments 


2<>  PSYCHOLOGY 

»  capable,  the  complexity  of  its  methods  of  locomotion,  of 

protection,  and  «.f  rcpnKliu  lion,  •      all  attest  the  in: 
the  relation  U-twrcn  nervous  c  and  behavior. 

Complex  paths  within  the  nervous  system.  Not  only  so, 
but  the  central  group  of  nerve  cells  begins  to  have  certain 
internal  paths  which  take  on  the  largest  significance  for  the 
animal's  life.  The  energy  which  comes  in  at  the  sense 
organ  of  a  beetle  sets  up  through  the  central  nervous  system 
a  most  complex  chain  of  acts.  Think,  for  example,  of  such 
an  insect  aroused  by  the  smell  of  food.  It  first  flies  to  the 
spot,  guided  by  the  increasing  intensity  of  the  odor  ;  it  lights 
on  the  food  and  then  seizes  it.  In  such  a  series  of  acts 
the  nervous  system  has  acted  in  the  most  complicated  way  to 
control  and  keep  in  action  the  various  muscles  of  the  body 
in  the  interests  of  the  whole  organism  which  is  dependent 
for  its  life  on  its  ability  to  find  food  and  absorb  it. 

Such  considerations  lead  us  to  think  of  the  nervous  system 
itself  as  a  complex  organ  made  up  of  dominant  centers  and 
secondary  centers  with  paths  running  between  them.  ( )ur 
later  study  will  fully  justify  such  a  conception. 

When  the  nervous  system  reaches  this  stage  of  organiza- 
tion, many  of  its  inner  paths  and  centers  are  determined  by 
the  animal's  inheritance.  Just  as  a  starfish  inherits  arms  and 
a  mouth  from  its  race,  and  a  beetle  inherits  legs  and  wings, 
so  each  animal  inherits  certain  paths  through  its  central 
nervous  system.  These  inherited  paths  play  a  lar^e  part  in 
controlling  the  life  of  the  individual  animal.  The  insect  t 
a  certain  type  of  food  because  its  inherited  sensory  cells 
respond  in  a  certain  definite  way  to  certain  odors.  Other 
special  activities,  such  as  depositing  eggs  and  special  modes 
of  flight  designed  to  carry  the  animal  away  from  enemies, 
are  due  also  to  the  organized  tracts  which  run  through  the 
nervous  system.  Indeed,  it  appears  in  the  study  of  insects 
and  animals  at  the  lower  levels  of  evolution  that  practically  all 
their  modes  of  behavior  are  determined  through  inheritance. 


BODILY  CONDITIONS  27 

Experience  comparable  to  the  lower  forms  of  human 
experience.  If  we  try  to  guess  what  are  the  experiences  of 
such  an  animal,  we  must  not  draw  on  our  own  experiences 
of  meditation  and  deliberation.  Deliberate  casting  about  in 
thought  for  a  course  of  action  is  far  from  characteristic  of  an 
insect.  The  analogy  which  we  should  borrow  from  human 
experience  is  the  analogy  of  a  fully  organized  habit  or,  better, 
the  analogy  of  one  of  our  own  inherited  modes  of  action, 
such  as-  that  exhibited  in  the  winking  of  the  eye  or  jerking 
the  head  aside  when  an  object  moves  rapidly  toward  the  face, 
threatening  to  strike  it.  Conscious  experience  is  made  up 
in  such  cases,  not  of  clearly  defined  knowledge  of  the  thing 
which  gives  rise  to  the  experience,  but  rather  of  a  vague 
excitement,  followed  by  unrest  when  the  instinctive  winking 
or  dodging  does  not  adequately  meet  the  requirements  of 
the  situation,  and  by  satisfaction  when  the  activity  proves 
sufficient. 

Differentiation  of  vertebrate  central  nervous  system. 
Passing  by  long  steps  up  the  scale  of  life,  we  may  next 
consider  the  nervous  system  of  one  of  the  lower  vertebrates. 
Here  we  find  that  the  centralized  organization  has  gone  be- 
yond that  seen  in  the  insects,  but  it  is  yet  relatively  simple. 
Fig.  7  shows  the  general  form  of  the  frog's  nervous 
system  looked  at  from  above.  In  all  of  the  vertebrates  the 
nervous  system  is  incased  in  the  bones  of  the  vertebral 
column  and  skull,  so  that  the  view  here  presented  shows 
the  appearance  of  the  nervous  organs  after  the  bones  and 
muscles  and  skin  which  cover  these  organs  in  the  normal 
animal  have  been  removed.  The  frog's  nervous  system  may 
be  roughly  divided  into  two  main  sections.  The  first  part 
lying  behind  the  cerebellum  consists  of  the  long  cylindrical 
spinal  cord  with  the  medulla,  which  is  essentially  an  enlarge- 
ment at  the  upper  end  of  the  cord.  The  cord  and  medulla 
are  directly  connected  with  the  surface  of  the  body  by  means 
of  a  great  number  of  fibers.  The  incoming  sensory  impulses 


28 


HOLOGY 


a 


>J  (/ 


from  the  skin  arc  received  through  certain  of  these  fibers, 
and  motor  impulses  are  distributed  to  the  muscles  through 

others.  There  arc  many  cells 
in  the  cord  and  medulla,  their 
:i  being  to  form 
links  of  connection  between 
the  incoming  sensory  fibers 
and  the  outgoing  motor  fibers. 
If  the  cord  and  medulla  are 
separated  from  the  higher  cen- 
ters by  a  cut  just  below  the 
cerebellum,  the  animal  con- 
tinues to  live  and  is  capable 
rtain  simple  responses  to 
sensory  stimuli,  the  only  depar- 
ture from  the  normal  being  that 
activities  called  out  by  stimuli 
show  a  machine-like  regularity. 
Thus,  if  a  drop  of  acid  is 
applied  to  the  skin  of  the  frog's 
trunk,  the  nearest  leg  bn: 
off  the  excited  spot.  The  acid 
sets  up  a  sensory  process  ;  this 
travels  up  to  the  cord  and 
there  passes  through  certain 
central  cells  and  is  sent  back 
along  motor  fibers  to  the  mus- 
cles. The  whole  process  is 
like  that  described  a  few  pages 
back  as  taking  place  in  the 
hydra.  There  is  no  evidence 
that  a  frog  having  its  spinal 
cord  severed  from  the  higher 
centers  has  any  ability  to  carry  on  the  higher  processes  of 
discriminating  reaction  which  involve  intelligence. 


FIG.  7.   The  nervous  system  of  a 

frog  as  it  would  appear  if  the  skin 

and  muscles  and  protecting  bone 

were  removed 

A,  spinal  cord  with  some  of  the  nerve 
fibers  which  extend  from  this  organ 
to  the  surface  of  the  body  (in  the 
posterior  region  a  plexus  of  fibers 
extends  to  each  of  the  posterior  ex- 
tremities; in  the  anterior  region,  a 
plexus  extends  to  each  of  the  anterior 
extremities) ;  B,  medulla  ;  C ,  cerebel- 
lum :  I),  optic  lobes,  which  are  con- 
nected with  the  eyes  by  optic  fibers  that 
pass  underneath  the  brain ;  E,  optic 
thalami;  /'.cerebral  hemisphere.  The 
anterior  portions  of  the  hemispheres 
constitute  what  are  known  as  the  olfac- 
tory lobes.  These  lobes  are  directly 
connected  by  means  of  the  fibers  shown 
in  the  figure  with  the  olfactory  region. 
Many  of  the  nerve  fibers  which  extend 
from  the  medulla  to  the  surface  of  the 
body  are  omitted  in  this  drawing 


BODILY  CONDITIONS  29 

If  the  frog  is  normal, —  that  is,  if  the  connection  be- 
tween the  spinal  cord  and  the  higher  centers  is  intact, —  the 
impulses  received  by  the  cord,  in  addition  to  circulating 
through  the  lower  centers,  are  carried  up  to  the  higher 
centers.  Here  they  are  influenced  by  the  action  of  higher 
centers. 

Two  types  of  higher  centers :  first,  higher  sensory  centers ; 
second,  indirect  centers.  The  centers  above  the  cord  and 
medulla,  which  constitute  the  higher  group  of  structures  in 
the  frog's  central  nervous  system,  are  of  two  kinds.  First, 
there  are  certain  sensory  centers,  namely,  the  large  optic 
lobes  and  the  olfactory  lobes.  These  connect  respectively 
with  the  eyes  and  nose  of  the  frog  and  receive  sensory 
impulses  from  these  higher  senses.  The  large  size  and 
forward  position  of  these  two  centers  indicate  the  impor- 
tance of  the  functions  which  they  perform  in  the  animal's 
life.  Especially,  the  large  size  of  the  optic  lobes  is  directly 
related  to  the  fact  that  the  frog  uses  its  sense  of  sight  in 
capturing  the  insects  on  which  it  subsists.  Second,  there 
are,  as  will  be  seen  from  an  examination  of  the  figure, 
certain  parts  of  the  upper  brain  which  have  no  direct 
connection  with  the  surface  of  the  body.  Thus  there  .are 
large  masses  of  tissue  in  the  cerebrum  and  in  the  optic 
thalami  which  lie  between  the  olfactory  and  optic  centers. 
These  are  higher  centers,  where  the  processes  which 
are  received  in  the  sensory  centers  may  flow  together 
and  fuse  into  higher  and  more  complex  forms  of  nervous 
activity. 

The  meaning  of  these  higher  centers  will  be  understood 
if  we  use  an  analogy.  In  a  large  business  concern  there  are 
minor  clerks  and  managers  who  attend  to  all  the  immediate 
details.  These  lower  officers  are  in  contact  with  the  outer 
world.  Far  removed  from  such  direct  contact,  in  a  quiet, 
central  office  is  a  central  manager,  to  whom  the  minor  offi- 
cers report  when  they  need  to  bring  other  workers  in  the 


to  I>X-Y<    li 

establishment  into  cooperation  or  when  they  have  problems 
iiMjuirin^  ^r< .  and  broader  views  than  they 

can  command. 

The  indirect  nervous  centers  are  fusion  centers  or  associa- 

hich  all  the  lower  centers  refer  their  a- 
.lu-n  tlu-se  activities  need  a  higher  coordination.    There 
:s  devcl*  >|>ed  within  the  nervous  system  a  higher  1< 
which  is  of  superior  importan 

Large  indirect  centers  characteristic  of  highest  animals. 
If  we  follow  the  evolution  of  the  nervous  system  from  the 
frog  up  to  man,  the  most  impressive  fact  is  that  these  in- 
direct centers  are  the  ones  which  show  marked  enlarge- 
ment. A  study  of  l"\£.  S  will  bring  out  the  facts.  At 
in  the  upper  left-hand  corner  of  this  plate,  shows  the 
brain  of  a  codfish.  At  the  right  is  the  cord,  enlarging 
under  the  cerebellum  into  the  medulla.  The  cerebellum  is 
much  more  fully  developed  than  in  the  case  of  the  frog. 
This  is  one  of  the  indirect  centers  referred  to  in  the  open- 
ing sentence  of  this  paragraph.  The  midbrain,  which  is 
the  optical  center,  is  very  large,  and  at  the  extreme  left 
the  ol factor)'  region  can  be  seen.  The  cerebrum  consists 
in  this  case  solely  of  the  corpus  striatum,  an  organ  which 
in  the  higher  brains  is  subordinated  to  the  cortex  of  the 
cerebrum. 

/•',  in  the  plate,  needs  no  special  discussion.  The  in- 
crease in  relative  importance  of  the  cerebrum  is  unmistak- 
able. In  C  the  preponderance  of  the  indirect  centers  is 
even  more  evident.  The  surface  of  the  cerebellum  is  folded 
so  as  to  make  more  room  at  the  surface  of  this  organ  for 
the  nerve  cells. 

Finally,  D  shows  the  final  type  of  brain  which  is  char- 
acteristic of  the  highest  animals.  The  cerebrum  literally 
covers  all  the  forward  organs.  It  is  folded  or  convoluted  on 
its  surface  for  the  same  reason  as  the  cerebellum.  The 
cord,  medulla,  and  other  lower  organs  are  present  and, 


BODILY  CONDITIONS 


considering  the  size  of  the  animal's  body,  are  organs  of  about 
the  same  importance  as  in  the  frog  or  codfish.  The  cerebrum 
and,  to  a  less  extent,  the  cerebellum  are  the  organs  which 
attract  attention.  The  higher  functions  of  the  dog  both  in 
behavior  and  in  the  realm  of  intelligence  must  be  related  to 


32 

the  enormous  development  of  his  cerebrum.    It   is  in  tin- 
indirect  centers  of  the  cerebrum  that  those  nervous  processes 
;.i.ur  which  condition  intelli  1  the  correspond* 

ing  types  of  behavior.  In  the  lower  animals  a  sensor)'  im- 
pulse passes  very  directly  through  a  relatively  small  amount 
of  central  tissue  to  the  organs  of  action.  In  these  lower 
animals,  also,  most  of  the  paths  of  transmission  an 
herited.  In  the  higher  forms,  on  the  other  hand,  there  is  a 
amount  of  tissue,  and  the  sensor)'  impulse  may  be  greatly 
modified  by  traveling  along  a  complicated  route  before 
discharged  into  the  muscles.  In  the  course  of  this  long 
journey  it  may  be  united  with  many  sensory  impulses  from 
other  sources,  so  that  the  final  action  is  the  resultant  of 
many  cooperating  impulses. 

Traces  of  past  impressions  also  present.    N«t  only  so, 
but  this  complex  tissue  becomes  a  storehouse  for  a  : 
variety  of  changes  in  structure  which  result  from  the  r< 
tion  of  sensory  impressions  and  the  sending  out  of  n 
impulses.    The  phrase  "tablets  of  memory"  begins  to  take 
on  a  very  vivid  meaning  to  the  student  of  brain  anatomy. 
Here  in  the  central  masses  of  tissue  to  which  the  rest  of 
the  nervous  system  reports  are  the  real  seats  of  organized 
personal   life,   the  records  of   which  are  deposited   in  the 
course  of  experience. 

Meaning  of  evolution  of  complex  organisms.  The  pro- 
found significance  of  this  increasing  inner  complexity  of  the 
nervous  system  can  be  understood  only  when  we  recognize 
that  increased  inner  complexity  has  always  been  the  outcome 
of  animal  evolution  in  every  organ  and  every  function. 

I^et  us  study,  for  example,  the  evolution  of  those  organs 
of  the  body  that  produce  the  temperature  which  is  charac- 
teristic of  the  higher,  so-called  warm-blooded,  animals.  The 
simple  organism  is  without  the  power  of  generating  a  con- 
stant inner  temperature  and  is  therefore  utterly  dependent 
for  its  body  temperature  on  the  environment.  As  a  result, 


BODILY  CONDITIONS  33 

such  an  animal  cannot  carry  on  vigorous  life  in  the  cold. 
The  complex  organism,  on  the  other  hand,  has  purchased 
self-sufficiency  in  matters  of  temperature  by  the  evolution 
of  a  complex  set  of  temperature-producing  organs.  The 
range  of  such  an  organism's  life  is  consequently  enormously 
increased. 

Another  striking  example  of  increasing  self-sufficiency  is 
furnished  by  studies  of  the  reproductive  processes.  In  the 
simple  forms  of  life  the  offspring  is  exposed  very  early  to 
the  mercies  of  the  environment.  The  parent  organism  has 
no  adequate  means  of  protecting  the  young.  Gradually  the 
parent  grows  more  complex  and  in  the  same  degree  better 
able  to  protect  the  offspring.  There  is  an  increase  in  the 
food  supply  deposited  with  the  egg  and  an  increase  in  pro- 
tective devices.  The  goal  of  this  line  of  evolution  is  reached 
when  the  parent  becomes  sufficiently  complex  in  structure 
to  provide  for  the  elaborate  development  of  the  offspring 
within  the  parent  organism.  The  whole  process  of  evolution 
is  here  seen  to  lead  in  the  direction  of  self-sufficiency  on 
the  part  of  the  organism.  Instead  of  depending  on  the 
chances  of  environmental  conditions,  the  organism  builds 
up  an  environment  of  its  own  within  which  its  reproductive 
processes  may  be  brought  to  a  high  degree  of  completion 
before  exposing  the  product  to  the  external  world. 

Every  organ  of  the  complex  animal  bears  witness  to  the 
truth  that  inner  self-sufficiency  is  the  end  toward  which 
organic  evolution  has  been  progressing.  There  are  organs 
for  the  storing  of  energy,  so  that  the  individual  shall  be 
relatively  free  from  the  necessity  of  securing  immediate 
nutrition.  There  are  organs  for  the  secretions  of  chemical 
reagents  which  shall  convert  the  raw  material  used  as  food 
into  proper  ingredients  for  the  building  up  of  body  tissues. 
Organisms  have  always  exhibited  in  their  higher  forms 
organs  of  mobility,  which  make  them  free  to  move  at  their 
own  initiative. 


34  PSYCHOLOGY 

In  all  these  cases  the  obvious  significance  of  increasing 
complexity  is  increasing  autonomy  of  the  individual.  The 
process  of  evolution  has  resulted  in  a  more  stable  set  of 
inner  conditions,  which  nuke  it  possible  for  the  vital  proc- 
esses to  go  on  without  interruption  or  hazard  from  flu 
tions  in  the  outer  world. 

Inner  organization  essential  to  highest  forms  of  personal 
behavior.  The  meaning  of  a  complex  nervous  system  thus 
nes  clear.  Nature  is  evolving  an  organism  in  which 
inner  processes  are  to  be  of  prime  importance.  Impressions 
must  be  received  from  the  outer  world,  but  the  important 
question  now  is.  What  will  be  done  with  these  impres 
in  the  inner  nervous  system,  where  the  impression  is  distrib- 
uted and  combined  with  other  impressions  and  with  traces 
of  past  impressions  ? 

We  are  thus  brought  to  the  point  where  we  realize  the 
meaning  of  the  sharp  antithesis  between  inner  personality 
and  sensory  impressions.  Two  men  receive  the  same  im- 
pression ;  to  one  it  means  much,  to  the  other  little.  The 
reason  for  the  difference  is  that  in  one  case  there  is  a  highly 
organized  central  response,  in  the  other  there  is  no  such 
response. 

Our  later  chapters  will  have  much  to  say  about  the  inner 
organization  of  the  nervous  system.  In  the  meantime,  it 
should  be  kept  in  mind  that  behavior  runs  parallel  with  this 
highest  evolution.  Man  is  not  only  complex  in  his  inner 
nervous  life,  but  he  is  complex  in  his  acts.  When  one 
thinks  of  the  complexity  of  speech  or  of  the  forms  of  skill 
exhibited  in  the  arts,  one  realizes  that  behavior  and  nervous 
organization  go  hand  in  hand  at  the  highest  levels  of  life 
as  well  as  at  the  lower  levels,  which  were  studied  in  the 
opening  paragraphs  of  this  chapter. 

Characteristics  of  behavior  of  higher  animals.  The  pur- 
poses of  our  present  discussion  will  be  best  served,  there- 
fore, by  reviewing  briefly  some  of  the  characteristics  of  the 


BODILY  CONDITIONS  35 

behavior  of  the  higher  animals.  First,  the  variety  of  move- 
ments is  vastly  increased.  Up  to  a  certain  point  in  animal 
evolution  the  number  of  organs  of  movement,  of  limbs  and 
oral  muscles  for  example,  increases  to  meet  the  increasing 
needs  of  the  animal ;  but  ultimately  a  point  is  reached  where 
development  of  movement  goes  forward  without  any  corre- 
sponding development  of  new  limbs  or  muscles.  This  later 
stage  is  characterized  by  the  development  of  nervous  struc- 
tures which  make  it  possible  to  use  the  given  muscles  in  a 
greater  variety  of  combinations.  Thus  a  skilled  artisan  de- 
pends for  his  perfected  movements,  not  on  the  development 
of  new  arm  muscles  or  finger  muscles,  but  on  the  develop- 
ment of  finer  coordinations  of  those  muscles  which  all  human 
beings  possess. 

A  second  striking  fact  of  behavior  which  parallels  the 
development  of  complex  nervous  centers  is  that  slight  stim- 
uli may  set  up  the  most  elaborate  processes.  The  value  of 
the  stimulus  in  such  a  case  is  determined  not  by  the  in- 
tensity or  quality  which  it  has  in  itself  but  by  the  complex 
organization  which  it  arouses  to  action.  Conversely,  a  strong 
stimulus  may  be  absorbed  in  the  elaborate  organization  and 
produce  no  immediate  effect.  These  statements  can  be  illus- 
trated by  the  behavior  of  a  frog  under  the  two  kinds  of 
conditions  discussed  above,  namely,  when  the  animal  has 
been  deprived  of  its  higher  centers  and  when  its  nervous 
system  is  intact.  If  a  stimulus  is  applied  under  the  former 
and  simpler  conditions,  a  response  will  follow  immediately 
with  mechanical  regularity.  This  response  will  be  of  a  very 
simple  and  direct  type,  usually  consisting  in  a  movement  of 
one  of  the  legs  up  to  the  point  of  irritation.  In  a  second 
case  we  may  apply  the  same  stimulus  to  a  frog  in  which  the 
cord  and  medulla  are  connected  with  the  higher  centers. 
The  reaction  in  this  case  will  be  of  an  entirely  different 
character.  It  will  usually  not  come  immediately,  and  its 
form  will  depend  on  a  great  variety  of  complex  conditions. 


Thus,  the  frog  may  jump  .may.  it  ma\  .  there  maybe 

a  complete  absence  of  apparci  .>  h  results  as 

these  appear  in  so  simple  an  animal  as  a  frog,  the  compl 
of  possible  organization  in  a  human  being  can  be  imagined. 
Third,  as  perhaps  the  most  important  result  of  the  de- 
velopment of  indirect  nervous  centers,  is  the  fact  that  the 
impressions  and  aaivitirs  which  appear  in  the  course  of 
individual  life  are  stored  up  and  enter  very  largely  into 
the  determination  of  nervous  organization.  As  pointed  out 
above,  the  lower  direct  centers  are  in  the  main  determined 
in  structure  by  heredity ;  the  higher  centers,  on  the  other 
hand,  are  found  to  be  undeveloped  at  birth,  so  that  the 
stimuli  which  act  upon  the  individual  find  at  the  beginning 
of  life  a  mass  of  undeveloped  tracts  through  which  they 
may  be  transmitted.  It  has  long  been  recognized  that  the 
infancy  of  all  the  higher  animals,  especially  human  infancy, 
is  very  much  longer  than  the  infancy  of  the  lower  forms. 
The  reason  for  this  appears  as  soon  as  we  recognize  that 
the  higher  centers  of  the  nervous  system  are  not  mapped 
out  by  heredity  and  require  time  to  mature. 

SUMMARY 

The  statements  which  have  been  made  throughout  the  chapter 
may  be  summarized  in  a  table.  This  table  shows  the  steady  growth 
in  the  complexity  of  animal  structure  and  animal  behavior  and 
opens  the  way  for  an  understanding  of  the  place  of  consciousness 
in  the  economy  of  life. 


LOWEST  FORMS 

HTDBA 

INTCRMBDIATB 
FORMS 

HIGHEST  FOBM* 

Body 

Unicellular 

Very  simple 
multicellular 

Increasingly 
complex 

Most  complex 

Nervous 
System 

None 

Specialized 
cells  diffused 
through  wall 
of  body 

Organized 
and  central- 
ized 

Characterized 
by  the  great 
development 
of  indirect 
centers 

BODILY  CONDITIONS 


37 


I,O\VI-:ST  FOK.MS 

HYDRA 

INTERMEDIATE 
FORMS 

HIGHEST  FORMS 

Organs 

Very  little,  if 

Increasingly 

Further  dif- 

of Sense 

None 

indeed  at  all, 

differentiated 

ferentiated, 

differentiated 

reaching  com- 

plete differen- 

tiation (see 

later  chapter) 

Behavior 

Simplest 

Simple 

Grows  more 

Most  complex 

and  more 

complex 

a,  limited  in 

a,  increasing 

a,  shows  va- 

a, specialized 

variety 

in  variety 

riety  of  in- 

movements of 

as  compared 

stinctive  acts 

great  variety 

with  unicellu- 

lar forms 

l>,  made  up  of 

&,  made  up  of 

b,  made  up  of 

6,  long  coordi- 

single acts 

simple  series 

combinations 

nated  trains 

of  factors 

c,  very  little 

f,  very  little 

c,  somewhat 

<•,  guided 

modified  by 

modified  by 

modified  by 

chiefly  by 

experience 

experience 

experience 

experience 

d,  follows 

d,  direct,  as  in 

of,  for  the 

d,  chiefly  indi- 

very directly 

unicellular 

most  part 

rect,  as  shown 

on  stimulus 

forms 

direct,  but  in 

in  man  in  such 

higher  forms 

activity  as 

includes  indi- 

speech 

rect  or  mem- 

ory factors 

Type  of 

Something 

Vague  feel- 

Possibly vague 

Instinctive 

Experi- 

like vague 

ings 

recognition  of 

recognitions 

ence 

feelings 

those  objects 

and  feelings 

which  call  for 

present,  but 

instinctive  re- 

overlaid by 

actions,  but 

intelligent 

chiefly  affec- 

consideration 

tive  ;  that  is, 

made  up  of 

feeling 

CHAPTKR    III 


THE  HUMAN  NERVOUS  SYS'I 

External  plan  like  that  of  all  vertebrates.  The-  structural 
plan  of  the  human  nervous  system  is  the  same  as  that  of  all 
vertebrau-s.  Fig.  9  shows  the  out- 
lines of  the  whole  system.  Through 
tin-  vertebral  column  runs  the  cord. 
This  enlarges  at  the  upper  end  into 
the  medulla.  These  two  organs  are, 
in  proportion  to  the  size  of  the  body, 
about  the  same  in  all  vertebrates. 
Above  the  medulla  can  be  seen  only 
the  cerebellum  and  the  cerebrum. 
The  parts  corresponding  to  the  optic 
lobes  and  other  minor  centers  of  the 
upper  brain  are  wholly  covered  by 
the  enormous  cerebrum.  The  sig- 
nificance of  this  development  of  the 
cerebrum  and  cerebellum  has  been 
indicated  in  the  foregoing  chapter. 
General  plan  of  the  minute  nerv- 
ous structure  as  related  to  conscious- 
ness. The  inner  structure  of  this 
nervous  system  is  of  importance  to 
the  student  of  conscious  processes. 
It  is,  to  be  sure,  impossible  to  trace 
with  the  microscope  the  inner  struc- 
tures which  are  set  in  action  when 
any  given  mental  process  takes  place. 
For  example,  when  one  sees  the  letters  of  a  printed  page,  there 

38 


FIG.  9.   General  form  and 

position  of  central  nervous 

organs 


THE  HUMAN  NERVOUS  SYSTEM 


39 


must  be  parts  of  the  nervous  system  which  are  aroused,  but  we 

cannot  trace  the  exact  paths  along  which  travels  the  nervous 

energy.   We  can  trace  the  general  plan  of  inner  organization. 

We  can  see   the  broad  avenues,   but 

must  infer  most  of  the  details.    The 

problem  presented  to  the  student  of 

psychology  is  not  unlike  the  problem 

of  planning  a   journey  with  a  map. 

One  sees  where  there  is  a  passage  and 

where  one  cannot  go.    Sometimes  the 

map  is  not  complete.     But  in  many 

cases  the  map  gives  a  general  view 

of  the  journey  and  some  idea  of  its 

probable  details. 

The  nerve  cell  and  its  parts.  The 
study  of  inner  organization  must  begin 
with  a  description  of  the  elements  out 
of  which  the  nervous  system  is  made. 
The  elements  are  cells  of  a  highly 
specialized  structure.  These  cells  are 
called  neurones.  Each  one  is  made 
up  of  a  nucleus,  a  cell  body  of  proto- 
plasmic tissue  surrounding  the  nucleus, 
and  a  series  of  processes  extending 
from  the  cell  body.  The  processes 
are  of  two  kinds ;  namely,  dendrites, 
or  branching  arms,  which  usually  con- 
duct impulses  toward  the  cell  body, 
and  a  single  long  nerve  fiber  which 
carries  the  impulse  outward  from  the 
cell  body.  Fig.  10  shows  two  neurones  with  all  their  charac- 
teristic parts.  It  will  be  noted  that  the  long  fiber  is  made  up 
of  several  parts.  There  is  a  sheath  around  most  of  the  long 
fibers  of  the  nervous  system.  This  is  not  an  essential  part 
of  the  nervous  structure,  but  an  external  protecting  structure. 


FIG.  10.   Two  nerve  cells 

Two  nerve  cells,  A  and  B, 
are  here  represented  with 
their  axones  C  and  D.  C  ex- 
tends from  the  cell  to  a  mus- 
cle ;  shortly  after  leaving  the 
cell  the  axone  is  surrounded 
by  a  heavy  protecting  sheath, 
as  indicated  in  the  figure, 
and  known  as  the  medullary 
sheath.  At  XX  there  ap- 
pears an  outer  sheath,  known 
as  the  Sheath  of  Schwann. 
The  medullary  sheath  ends 
at  the  point  where  the  fiber 
divides  into  a  fine  network 
and  passes  into  the  muscle. 
The  axone  D  communicates 
with  another  cell.  (After 
Testute) 


PSYCH" 


The  neurones  are  organized  into  chains.     An   impulse 
acting  on  one  cell  is  transmitted  to  other  connected  neurones 

until,  finally,  the  impulse 
reaches  a  cell  connected 
with  a  muscle  fiber.  The 
contact  between  neurones 
in  the  higher  nervous  sys- 
tems is  indirect,  as  shown 
ii;  that  is,  the  fiber 
from  one  cell  does  not  pass 
directly  into  another  cell,  but 
breaks  up  into  a  fine  net- 
work of  fibrils  and  inter- 
bees  with  the  dendrites  from 
other  cells.  The  conm- 
of  a  single  cell  may  be  very 
numerous  by  virtue  of  the 
branching  of  the  dendrites 
and  because  of  the  indirect 
relations  between  neu: 
The  point  of  relation  be- 
tween two  neurones  is  known 
as  a  synapse.  At  the 
apses,  impulses  are  redistrib- 
uted in  the  greatest  possible 
variety  of  directions. 

Complexity  of  structure 
related  to  forms  of  action. 
An  examination  of  neurones 
in  various  animals  and  at 
different  stages  of  individual 
development  shows  clearly 
that  the  number  of  branches 


FIG.  n.    A  number  of  different  types 

of  connection  between  nerve  fibers 

and  cells 

A  and  A'  represent  incoming  sensory 
fibers  which  bring  stimulations  from 
different  directions  to  the  cell  B.  All  of 
the  stimulations  acting  upon  B  are  trans- 
mitted along  the  fiber  C,  and  at  the  end 
of  this  fiber  may  affect  various  cells,  such 
as  D  .and  F..  From  the  cells  D  and  f. 
the  stimulations  may  pas*  in  different 
directions,  as  indicated  by  the  arrows. 
The  stimulations  from  A  and  A'  fuse  in 
the  cell  B.  The  stimulation  from  the  cell 
B  is  subdivided  and  redistributed  from 
D  and  E.  All  connections  are  indirect 
i.  r  -'.Tip' 


of  the  cell  is  an  important  factor  in  determining  the  com- 
plexity of  the  nervous  organization  into  which  the  neurones 


THE  HUMAN  NERVOUS  SYSTEM 


may  enter.  Fig.  12  shows  the  increasing  complexity  of 
neurones  as  we  ascend  the  scale  of  animal  life,  and  also 
the  increasing  complexity  of  neurones  of  a  single  human 
being  as  the  nervous  structures  mature.  The  lesson  to  be 
learned  from  these  two  series 
of  figures  is  clear.  The  com- 
plexity of  a  cell  and  the  number 
of  systems  of  connections  into 
which  the  cell  may  enter  in- 
crease in  direct  proportion  to 
each  other. 

Synapses  as  paths  of  organi- 
zation. Whether  they  are  units 
in  one  of  the  lower  centers 
of  the  nervous  system  or 
in  a  higher  center,  the  cells 
are  always  connected  through 
synapses  and  always  transmit 
impulses  indirectly,  thus  com- 
bining them  and  distributing 
and  redistributing  them.  The 
nervous  system  has  been  com- 
pared to  a  telephone  switch- 
board. The  senses  send  in 
excitations  and  the  central 
cells  send  these  to  the  various 
muscles  of  the  body.  On  the 
way  to  the  muscles  one  set 
of  sensory  excitations  unites 

with  another  set  from  some  second  organ  of  sense.  The 
combinations  and  distributions  are  somewhat  like  those  of 
the  switchboard,  only  infinitely  more  complex.  How  com- 
plex they  are,  one  can  imagine  from  the  statement  that 
the  total  number  of  cells  in  the  human  nervous  system 
has  been  estimated  as  somewhat  more  than  1 2,ooo,cxx)Jooo. 


FIG.  12.  The  development  in  com- 
plexity of  nerve  cells  in  the  course 
of  animal  evolution  and  in  the 
course  of  the  development  of  a 
single  individual 

A  is  the  nerve  cell  of  a  frog;  B,  a 
lizard  ;  C,  a  rat ;  D,  man.  The  possi- 
bility of  developing  definite  paths 
between  various  neurones  increases 
in  proportion  to  the  increase  in  the 
number  and  complexity  of  the  den- 
drites from  the  cells,  a  is  a  neuroblast 
without  dendrites,  from  the  earlier 
embryonic  development  of  a  human 
brain,  b  shows  the  beginnings  of  den- 
drites at  the  upper  end  of  the  cell. 
In  c,  in  </,  and  in  e  the  dendrites 
increase.  The  form  of  the  mature  cell 
can  be  seen  by  referring  to  D  in  the 
upper  series.  (After  Cajal) 


42 

Paths  in  spinal  cord.    1  sensory  impulse 

through  the-  l<>\\rr  paths  of  connection  in  the  spinal 
i  ;  shows  a  magnified  section  across  the  cord. 
left  side  of  the  figure  shows  the  apj>enr.mce  of  the  s* 
as  seen  under  the  microscope,  while  the  right  side  is  dia- 
.;  matic  and   allows   one  to  trace   some  of  the   paths 
through   the   tissue.    The   figure   shows   that   the   coi 
bilateral ;  that  is,   made  up  of  two  similar  parts,  one  for 
each  side  of  the  body.    The  nervous  system  throughout  is 


Fir..  13.    Transverse  section  across  the  spinal  cord 

bilateral,  just  as  are  the  nostrils  and  eyes  and  arms.  In  the 
middle  of  the  cord  is  a  mass  of  cells.  They  have  a  gray 
color  and  are  called,  collectively,  gray  matter.  Around  the 
mass  of  cells  are  bundles  of  fibers  which,  because  of  their 
glistening  white  color,  are  clearly  distinguishable  from  the 
cells.  Some  fibers  are  seen  running  into  the  cord  and  out 
of  it  at  the  level  of  the  section ;  some  arc  running  back 
and  forth  within  the  cord  ;  the  majority  appear  as  mere 
spots  because  they  run  in  a  direction  perpendicular  to  the 
plane  of  this  section  and  are  cut  squarely  across  in  making 
the  section. 


THE  HUMAN  NERVOUS   SYSTEM  43 

On  the  right  side  of  the  figure  at  A  is  seen  a  nerve 
trunk,  or  cable-like  bundle  made  up  of  many  nerve  fibers. 
This  bundle  of  fibers  breaks  up  into  two  roots ;  the  root  P 
is  a  sensory  root  along  which  sensory  impulses  enter  the 
cord ;  the  root  M  is  a  motor  root  along  which  impulses 
leave  the  cord  on  their  way  to  the  muscles.  At  G  is  a 
group  of  cells  outside  the  cord,  constituting  an  independent 
ganglion.  These  are  the  cells  which  send  their  fibers  to  the 
skin  and  receive  the  impression  of  touch.  If  one  has  the 
patience  to  trace  the  fibers  i,  2,  3,  and  4,  one  will  find 
typical  paths  across  the  cord.  This  diagram  alone  is  not 
adequate,  however,  for  many  of  the  fibers  must  be  shown  in 
a  flat  section  of  this  kind  as  abruptly  broken  off.  They 
pass  in  reality  out  of  the  level  of  this  section.  Fig.  14  is 
therefore  added  to  give  an  idea  of  the  way  in  which  the 
various  levels  of  the  cord  are  related  to  each  other  and 
to  the  cerebrum.  B  represents  a  section  of  the  spinal 
cord ;  A,  a  portion  of  the  cerebral  cortex.  Dl  represents 
a  region  of  the  skin  in  which  the  sensory  ending  of  a 
tactual  fiber  from  the  cell  D  is  distributed.  A  pressure 
stimulation  acting  upon  Dl  will  excite  the  nerve  cell  and 
send  a  stimulation  inward,  as  indicated  by  the  arrows. 
This  stimulation  will  pass  upward  and  downward  to  various 
levels  of  the  cord,  as  indicated  by  the  branching  of  the 
incoming  fiber  at  e.  Certain  portions  of  this  incoming  stim- 
ulation will  be  distributed  through  the  spinal  cord  at  differ- 
ent levels,  as  indicated  by  the  small  collateral  branches 
passing  horizontally  out  of  the  branches  of  the  sensory 
fiber  (see  also  Fig.  13).  At /the  incoming  fiber  communi- 
cates with  a  nerve  cell  which,  in  turn,  connects  with  the 
cerebrum.  This  diagram  is  much  too  simple,  more  than 
one  cell  being  necessary  for  the  transmission  of  this  stimu- 
lation to  the  higher  centers.  When  the  stimulus  reaches  g 
in  the  cerebral  cortex,  it  acts  upon  the  large  cell  there  shown, 
and  is  transformed  into  a  motor  impulse.  It  then  passes 


44 


r»SY(  II-  H 


downward    along   the    fiber    ,;,    which   gives   off   horu< 
collaterals  at  different  levels  of  the  cord.    Through  one  of 
these  collaterals  or  through  tin-  termination  of  the  centrif- 
ugal fiber,  as  indicated  at  bt  the  stimulus  is  transmitted  to 

a  motor  cell  in  the 
spinal  i 

from  this  cell  is 
carried  outward  to 
the  muscles  indi- 
cated at  C. 

Reflex  tracts. 
When  a  sensory 
stimulation  passes 
through  the  cord 
and  comes  out  in 
an  immediate  reac- 
tion, the  process 
is  called  a  reflex. 
Thus,  when  one 
touches  a  hot  iron 
and  jerks  back  the 
hand,  such  a  proc- 
ess is  exhibited. 
The  nerve  cells  in 
the  cord  are  in  this 
fashion  in  control 
of  many  of  the 
simplest  fortns  of 
behavior,  such  as 
the  organic  processes  involved  in  digestion,  and  the  simpler 
protective  movements,  such  as  the  withdrawing  of  the 
hand  above  referred  to.  The  nerve  cells  of  the  cord  are 
larger  than  in  other  parts  of  the  system,  hence  do  not 
fatigue  as  readily;  they  watch  over  the  body  when  the  cells 
in  the  higher  centers  are  asleep. 


1-11.14.    A  diagram  to  illustrate  the  course  of  the 

sensory  stimulation  when  it  passes  upward  from 

the  level  of  the  spinal  cord  at  which  it  is  received. 

(After  Cajal) 


THE  HUMAN  NERVOUS   SYSTEM 


45 


Transmission  to  higher  centers.  In  addition  to  serving 
as  a  seat  for  the  reflex  centers,  the  cord  is  a  communicating 
cable,  as  was  shown  in  Fig.  14,  carrying  up  to  the  brain 
messages  from  the  surface  of  the  body  and  carrying  back 
messages  to  the  muscles. 

All  nervous  organs  in  part  inde- 
pendent centers.  The  higher  nervous 
centers  above  the  cord  are  more 
elaborate  organs,  but  they  are  in 
essential  structure  the  same  as  the 
cord.  Below  the  cerebrum  every 
organ  of  the  nervous  system  may  be 
said  to  consist,  like  the  cord,  of  a 
combination  of  relatively  independent 
cell  centers  and  transmitting  tracts. 
In  the  cerebrum  the  whole  surface 
of  the  organ  is  made  up  of  inde- 
pendent cell  centers. 

Cerebellum.  In  the  cerebellum  the 
central  function  predominates.  This 
can  be  shown  by  examining  a  section 
of  this  organ.  Fig.  15  shows  one  of 

?  ,  .  -  the  descending  fiber,    d  also 

the   lamellae,    or   folds    of   the   cere-    shows  the  termination  of  an 

bellum,     much     enlarged.       It    Will     be      incoming  fiber.   The  organs 
.  .  here  figured  serve  to  redis- 

seen  from  this  section  that  the  cells  tribute  impulses  from  other 
lie,  not  in  the  center  of  the  organ  as  Parts  of  the  nervous  system. 

(After  Cajal) 

m  the  spinal  cord,  but  at  the  outer 

surface.  Fibers  enter  the  cerebellum  in  bundles  and  termi- 
nate in  a  fine  network  of  fibrils  about  the  cells  which  are 
situated  on  the  surface.  The  surface,  which  is  technically 
known  as  the  cortex,  is  increased  very  greatly  in  extent  by 
the  folding,  which  can  be  seen  in  any  figure  representing 
this  organ.  The  result  of  the  folding  is  that  provision  is 
made  for  an  enormous  number  of  cells  in  a  relatively 
small  cubical  space.  Through  the  action  of  the  cells  in 


FIG.  15.    A  diagrammatic 

section  through  a  part  of 

one  of  the  folds  in  the 

cerebellum 

A  fiber,  a,  entering  from 
some  other  part  of  the  cen- 
tral nervous  system,  distrib- 
utes its  impulse  to  the  small 
cells  c  and  to  the  larger 
cell  l>.  From  6,  the  stimu- 
lus is  carried  outward  along 


46 


the   crrrlx-lL  imjniK<-  comes   into   the 

K-lluin    :is    a  t    the    hi 

urn,  may  be  sub- 
into  .1  ^n-.it   numk-r  of  currents  so  as  to  arouse, 

'••••/••'•' 


Fn;.  1 6.    The  brain  seen  from  below  and  cut  open  to  show  the  paths  of 
fibers  from  the  cortex  of  the  cerebrum  to  the  lower  organs 

In  the  lower  part  of  the  figure  near  the  middle  is  the  medulla.  One  side  of  the 
cerebellum  is  shown  on  the  left.  Sections  of  the  cerebral  cortex  constitute  the  chief 
part  of  the  figure,  especially  at  the  left  above  and  below.  From  the  cortex  peduncular 
fibers  pass  downward.  Near  the  top  of  the  figure  the  heavy  band  of  fibers  constituting 
the  corpus  callosum  crosses  from  one  hemisphere  to  the  other.  (After  Kdingcr) 

• 

when  distributed  to  the  active  organs,  a  whole  system  of 
muscles.     Indeed,  there  is  evidence  that  the  cells  of  the 
:>ellum    contribute   in    the    way    indicated    to   muscular 
coordinations   in   all   parts  of  the  body. 


THE  HUMAN  NERVOUS  SYSTEM 


47 


Cerebrum  and  its  systems  of  fibers.  From  the  cord  and 
cerebellum  and  the  other  minor  centers  of  the  nervous  sys- 
tem we  turn  to  the  cerebrum.  Our  study  of  the  evolution 
of  the  nervous  system  showed  the  dominating  importance 
of  this  organ  in  all  of  the  higher  animals.  The  cerebrum 
is  a  complex  organ  to  which  sensory  impulses  come  from 
all  parts  of  the  body  and  from  which  motor  impulses  are 
sent  out  to  all  the  voluntary  muscles.  It  is  not  directly 


FIG.  17.    Sketch  showing  some  of  the  association  fibers  connecting  various 
parts  of  the  cortex  of  the  cerebrum  with  one  another.    (After  Edinger) 

connected  with  the  surface  of  the  body,  but  is  indirectly 
the  organ  in  control  of  all  parts  of  the  body.  It  is  a  cen- 
tral clearing  house  for  the  organism.  It  is  the  part  of  the 
body  most  intimately  related  to  consciousness. 

In  structure  the  cerebrum  consists  of  an  external  folded 
or  convoluted  layer  of  cells  known  as  the  cortex.  This  cor- 
tex is  from  one  eighth  to  one  twelfth  of  an  inch  in  thick- 
ness and  shows  many  variations  in  structure  in  its  different 
parts.  To  these  variations  in  the  structure  of  the  cortex 


PSYCHOLOGY 


further  reference  will  be  made  later.  The  central  mass  of 
the  cerebrum  is  composed  of  fibers  which  provide  for  the 
connection  of  each  point  of  the  cerebral  cortex  with  every 
other  part  of  the  ner\  The  general  structure  of 

the  cerebrum  may,  perhaps,  be  comprehended  most  easily 
by  refer:  :ns  of  cerebral  fibers.  There  are 

three  types  or  systems  of 
fibers. 

First,  there  are  great 
bundles  of  fibers  connect- 
ing the  cerebrum  with  the 
r  centers  and  constitut- 
ing the  paths  along  which 
motor  impulses  descend. 
These  constitute  the  pe- 
duncular tract.  Some  of 
these  fibers  were  shown 
in  the  diagram  illustrating 


the  paths  in  the  spinal 
cord  (Fig.  14) ;  the  whole 
system  is  shown  m  Fig.  16. 
Second,  there  are  fibers,  as 


FIG.  1  8.  A  transverse  section  across  the 

two  hemispheres  in  a  plane  passing  verti- 

cally  through  the  cheek  bones  parallel 

to  a  line  connecting  4hc  two  ears 

This  section  shows  the  fibers  which  establish 

communication  between  the  two  hemispheres,      shown    in    Fig.    \J,    which 

When  the  fiber,  in  this  figure  are  supple-  connect  the  different  points 
mented  by  those  represented  in  the  two 
preceding  figures,  it  will  be  seen  that  every 
point  on  the  cortex  of  the  cerebrum  is  in 
communication  with  all  other  parts  of  the 
nervous  system.  (After  Edinger) 


of  the  cortex  of  one  hemi- 
sphere with  other  points 
in  the  same  hemisphere. 
These  fibers  are  techni- 
cally known  as  association  fibers.  The  third  bundle  of  fibers 
extends  from  one  hemisphere  of  the  cerebrum  to  the  other 
hemisphere.  The  fibers  of  this  group  are  known  as  the 
commissural  fibers,  and  go  to  make  up  the  corpus  callosum, 
or  bridge  of  fibers,  conspicuous  in  any  median  section  of 
the  cerebrum  and  shown  in  Fig.  18.  This  bridge  was  also 
shown  in  Fig.  16. 


THE  HUMAN  NERVOUS  SYSTEM 


49 


Structure  of  cerebrum  as  indicating  way  in  which  impulses 
are  organized.  No  clearer  evidence  of  the  function  of  the 
cerebrum  can  be  found  than  that  which  is  given  in  the 
structure  of  its  systems  of  fibers.  An  impulse  which  reaches 
the  cells  of  the  cerebral  cortex  through  the  sensory,  or 
incoming,  fibers  of  the  peduncular  tract  is  brought  to  the 
cortex  for  the  purposes  of  redistribution  and  combination 
with  other  impulses.  The  elaborate  system  of  interconnect- 
ing tracts  provides  for  infinite  recombinations  of  nervous 


FIG.  19.   Two  sections  representing  portions  of  the  cerebral  cortex  from 
two  areas  of  the  human  brain 

On  the  left  there  are  shown  the  sixth  and  seventh  layers  of  the  visual  center.  The 
horizontal  distribution  of  the  dendrites  of  the  large  pyramidal  cells  is  characteristic 
of  this  region.  On  the  right  is  a  part  of  the  motor  center,  showing  giant  pyramidal 
cells  which  in  size  and  distribution  of  dendrites  differ  from  those  in  other  centers. 

(After  Cajal) 

impulses.  We  shall  refer  in  all  of  our  later  discussions  to 
the  organization  of  nervous  processes  which  goes  on  in  the 
cerebrum.  The  term  "  organization,"  so  used,  refers  to  the 
fact  that  a  nervous  impulse,  when  it  reaches  the  cerebrum, 
is  united  with  other  impulses  and  is  carried  along  complex 
series  of  paths,  until  finally  it  is  discharged  into  the  motor 
channels  which  pass  outward  to  the  muscles.  No  impulse 
which  reaches  the  cerebrum  can  escape  combination  with 
other  impulses ;  the  purpose  of  the  whole  structure  is  to 
provide  channels  for  the  most  complete  interrelating  of  all 
the  higher  nervous  processes. 


iloLOGY 


•:-r-; 


Cerebral   cortex  complex.    The  cortex  of  the  cerebrum 
has  a  structure  of  such  complexity  that  it  has  been  impos- 
sible, until  very  recently,  to  define  with 
anything  like-  .  its  various  parts. 

I-'ijj.  i  two  typically  dift< 

An  examination  of  these  dia- 
grams shows  that  the  cells  are  of  differ- 
ent types  and  the  mode  of  interlacing 
of  their  dendrites  is  different.  Fig.  20 
shows  a  diagrammatic  representation  of 
some  of  the  different  elements  v. 

;.u;uuri.stk  of  the  cerebrum.  By 
means  of  this  figure  the  cells  and  fibers 
which  in  reality  are  interlaced  can  be 
distinguished  from  each  other. 

Localization  of  functions.  Though  we 
an-  ignorant  of  the  meaning  of  many  of 
the  details  of  cortical  structure,  we  are 
well  informed  as  to  the  functions  of 
many  areas  of  the  cortex.  The  cortex 
diagram-  may  be  divided  into  three  kinds  of  areas 
or  centers .  these  are  sensory  areas, 
motor  areas,  and  association  areas.  The 
sensory  areas  are  those  which  have  the 
most  direct  relations  to  the  various 
organs  of  sense ;  the  motor  areas  are 
those  which  stand  in  most  direct  rela- 
tions to  the  active  organs.  There  is  no 
part  of  the  cerebrum  which  has  simple 
and  immediate  relations  to  the  surface 
of  the  body,  so  that  the  terms  "  sensory" 
*nd  "  ™*or"  are  merely  relative  terms, 
the  sensory  centers  being  those  points 
at  which  the  stimulations  from  the  organs 
of  sense  are  first  received  in  the  cerebrum,  the  motor  areas 


Fir.  20.  A 
matic  section  showing 
the  structure  of  the 
cortex  of  the  cerebrum 

On  the  left-hand  side  of 
the  figure  the  cells  alone 
are  shown.  On  the  right- 
hand  side  of  the  figure 
the  fiber  systems  alone 
are  indicated.  The  figure 
does  not  represent  ade- 
quately the  comp!< 
the  structure.  Many  small 
cells  are  not  here  repre- 
sented. A  general  impres- 


the  complexity  of  the  cor- 
tex.   (After  Edinger) 


THE  HUMAN  NERVOUS   SYSTEM  51 

being  those  points  from  which  the  stimulations  pass  out  of 
the  cerebrum  on  their  way  to  the  muscles.  The  association 
areas,  as  the  name  indicates,  are  areas  of  a  still  more  indi- 
rect character,  in  which  sensory  impulses,  after  being  received 
in  the  sensory  areas,  are  recombined  and  redistributed.  In  a 
very  proper  sense  of  the  term,  all  cerebral  areas  are  Associ- 
ative areas,  for  they  all  serve  the  function  of  indirect  com- 
bination and  distribution  of  nervous  impulses.  Those  which 
are  specifically  designated  as  associative  have  claim  to  the 
specific  name  because  they  perform  a  function  of  even  higher 
combination  than  do  the  others.  Figs.  21  and  22  show  the 
centers  of  these  types  which  appear  on  the  surfaces  of  the 
human  cerebrum. 

Stimulation  the  first  method  of  discovering  cerebral  locali- 
zation. It  may  be  interesting  to  digress  for  a  moment  from 
the  structure  of  the  cortical  centers  for  a  discussion  of  the 
methods  by  which  these  centers  have  been  located.  A  great 
number  of  experiments  have  been  tried  on  the  higher 
animals.  Certain  of  the  areas  have  been  artificially  stimulated, 
and  when  muscles  in  different  parts  of  the  body  have 
responded  promptly  and  regularly  to  these  stimulations,  the 
connection  between  the  areas  stimulated  and  the  muscles 
thrown  into  action  has  been  recorded.  Evidently,  artificial 
stimulations  of  this  kind  would  be  of  little  value  in  locating 
sensory  or  association  areas,  for  there  are  no  clearly  marked 
muscular  effects  when  the  stimulus  is  applied  to  areas  other 
than  those  directly  related  to  the  muscles.  For  example, 
the  stimulation  of  the  visual  center  would  show  only  the 
motor  effects  of  such  stimulation  and  would  not  give  any 
clear  indication  of  the  sensory  character  of  the  area. 

Extirpation  and  comparison  of  pathological  cases.  A  sec- 
ond type  of  experiment  which  has  been  productive  of  results 
depends  upon  extirpation  of  the  tissues.  Certain  areas  of  the 
cerebral  cortex  of  animals  are  cut  or  burned  out,  and  the  loss 
in  function  resulting:  from  this  removal  of  the  nervous  tissue 


52  PSYCHOLOGY 

is  carefully  studied.  This  method  can  be  used  in  locating 
both  sensory  and  motor  centers.  There  are  cases  of  disease 
of  the  human  nervous  system  analogous  to  these  cases  of 


Fie.  21.   The  outline  of  the  lateral  surface  of  the  cerebrum  with  the  typical 
convolutions,  as  given  by  Flechsig 

The  shaded  portion!  indicating  the  sensory  and  motor  centers,  and  the  small  circle* 
indicating  certain  well-defined  association  areas,  are  given  according  to  Tschennak 
in  Sagel's  "  Handbuch  der  Physiologic  des  Menchen."  Vertical  lines  in  the  shaded 
areas  indicate  motor  areas;  horizontal  lines  indicate  sensory  areas;  oblique  lines 
indicate  sensory-motor  areas.  /,  /,  /,  /.  /  are  the  motor  areas  for  the  toes  and 
foot ;  2,  a,  r  are  the  motor  areas  for  the  shoulder,  elbow,  and  wrist ;  j,  jt  j,  j  are 
the  areas  for  the  fingers  and  thumbs ;  4,  4,  4,  4  are  the  motor  areas  for  the  eye 
and  other  parts  of  the  face ;  j  is  the  center  for  the  vocal  cords ;  6,  for  the  tongue ; 
7  is  the  sensory  area  for  the  head ;  8,  8,  8,  8  are  the  sensory  areas  for  the  regions 
to  which  motor  stimulations  are  distributed  by  the  areas  /-6 ;  p.  q  are  the  sensory- 
motor  areas  of  the  trunk ;  //,  visual  area  and  occipital  area  for  the  eye  movements ; 
12,  auditory  area  and  temporal  center  for  visual  fixation :  /.,-.  olfactory  bulb :  //. 
probably  olfactory  area.  The  area  where  vertical  and  horizontal  lines  cross  between 
the  motor  areas  1-6  and  the  sensory  areas  7,  8  is  probably  connected  with  the 
muscle  sense.  A,  motor  writing  center;  /?,  Broca's  motor  speech  center:  C,  prob- 
ably memory-motor  speech  center ;  D,  sensory  music  center ;  F..  Wcmicke's  sensory 
speech  center ;  /•',  memory-sensory  speech  center ;  G,  memory  reading  center ;  ff, 
sensory  reading  center.  All  of  these  lettered  areas  are  associational  centers 

extirpation  in  animals,  and  careful  study  of  the  loss  of 
human  functions  shows  that  the  human  cortex  is  subdivided 
in  much  the  same  way  as  that  of  the  higher  mammals. 


THE  HUMAN  NERVOUS  SYSTEM 


53 


Embryological  methods.  There  are  other  methods  of 
investigating  cerebral  areas  which  deal  with  the.  internal 
structures.  One  of  the  most  productive  of  these  methods 
depends  upon  the  fact  that  the  different  areas  of  the  cere- 
brum do  not  develop  at  exactly  the  same  period  in  the 
embryological  or  infant  life  of  a  human  being.  The  human 


13 


16 


FIG.  22.  The  median  surface  of  the  human  cerebrum  showing,  as  in  Fig.  21, 
the  various  areas 

8,  sensory  area  for  the  lower  extremities ;  9,  9,  sensory-motor  areas  for  the  trunk ; 
10,  motor  area  of  the  lower  extremities ;  //,  visual  area  and  occipital  motor  area  for 
visual  fixation  ;  /j,  olfactory  bulb  ;  14,  probably  olfactory  area ;  75,  75,  /j,  /j,  olfactory 
areas  ;  /6,  /6,  probably  gustatory  areas.  (For  reference  to  authorities  for  this  figure, 

see  Fig.  21) 

embryo  exhibits  in  its  early  stages  a  development  of  the 
nervous  system  about  the  central  fold  or  fissure,  known  as 
the  fissure  of  Rolando.  This  area  of  earliest  development 
is  in  the  region  marked  in  Fig.  21  as  the  motor  area  and 
the  area  of  tactual  sensitivity.  Later,  the  nervous  system 
matures  in  the  remaining  sensory  centers  in  such  sequence 
that  it  is  possible,  by  the  study  of  the  microscopic  anatomy, 
to  secure  a  fairly  complete  chronological  account  of  the 


54  HOLOGY 

development  of  the  different  regions.  The  association  areas 
are  the  latest  to  develop.  Indeed,  in  the  ass<  ircas 

the  development  can  be  traced  for  a  period  after  birth,  and 
indirect  evidence  seems  to  make  it  clear  that  the  development 
goes  forward  well  on  into  mature  life. 

Association  areas.   The  visual  area  in  the  occipital  rcj.: 
as  indicated  in  I  -.rough  which 

impulses  resulting  from  retinal  stimulation  are  first  intro- 
duced into  the  cerebrum.  A  similar  area  for  the  reception 
of  auditory  impulses  appears,  as  indicated  in  i  just 

below  the  Sylvian  fissure.  Without  entering  further  into  a 
discussion  of  the  various  centers,  it  will  be  enough  to  call 
attention  to  the  relation  between  the  visual  and  auditory 
areas  and  the  association  area  lying  between  them.  The 
association  area  in  question,  known  as  the  parietal  associa- 
tion area,  has  developed  in  the  course  of  the  evolution  of 
the  cerebrum  between  the  visual  and  the  auditory  centers  as 
the  area  in  which  the  stimulations  from  these  two  centers 
may  be  brought  together  and  combined.  There  are  many 
evidences  that  the  combinations  of  visual  and  auditory  im- 
pulses do,  as  a  matter  of  fact,  go  on  in  the  parietal  associa- 
tion center.  For  example,  there  is  in  this  parietal  region 
one  area  which  is  of  great  importance  in  the  function  of 
speech.  If  this  association  area  involved  in  speech  is  dis- 
turbed, the  individual  may  remain  quite  capable  of  receiving 
visual  impressions  through  his  eyes  and  of  receiving  audi- 
tory impressions  through  his  ears.  He  may  even  be  capable 
of  articulation,  which  is  a  motor  function,  but  he  will  lack 
the  ability  to  interpret  the  impressions  which  he 
when  he  hears  or  sees  words  or  to  give-  expression 
coherent  series  of  ideas.  The  area  in  question  has  there- 
fore been  designated  as  the  ideational  area.  It  is  ideational 
rather  than  sensory,  because  it  is  the  seat  of  a  series  of 
functions  more  elaborate  than  those  which  are  involved  in 
the  mere  reception  of  impressions.  It  is  the  center  for  the 


THE  HUMAN  NERVOUS   SYSTEM  55 

combination  of  visual  or  auditory  impressions.  More  than 
this,  the  association  area  is  a  center  which  becomes  more 
and  more  highly  organized  in  its  inner  structures  through 
use,  so  that  its  influence  on  any  present  impulses  is,  doubt- 
less, such  that  we  are  justified  in  saying  that  it  adds  to 
these  impulses  the  effects  of  past  experience.  In  an  im- 
portant sense  it  associates  present  impressions  with  past 
impressions,  as  well  as  combines  present  impressions  from 
different  senses.  It  thus  serves  in  a  large  way  the  function 
of  a  reorganizing  center  for  visual  and  auditory  impressions. 
Significance  of  the  central  position  of  the  general  motor 
area.  Another  important  fact,  which  will  be  observed  im- 
mediately on  the  inspection  of  Figs.  21  and  22,  is  that  the 
general  motor  area  occupies  a  relatively  central  position  in 
the  cerebrum.  Around  the  motor  area  are  a  group  of  asso- 
ciation areas  where  impulses  are  united  on  their  way  to 
motor  discharge.  The  area  of  touch  and  of  general  sensi- 
bility seems  to  offer  an  exception  to  the  general  rule  of 
distribution  of  sensory  and  association  centers  around  the 
motor  area.  This  sensory  area  is  not  separated  from  the 
motor  area  by  an  association  area,  as  are  the  other  sensory 
centers.  We  see  in  this  relation  of  the  cerebral  centers  for 
touch  and  movement  the  structural  fact  which  corresponds 
to  the  functional  fact  that  the  skin  and  other  tissues  which 
give  rise  to  tactual  sensations  would  naturally,  as  the  earliest 
organs,  stand  in  so  intimate  a  relation  to  the  muscles  that 
the  later  and  more  highly  developed  organs  of  sense  could 
not  be  expected  to  duplicate  this  relation.  As  the  primitive 
tactual  sensory  surfaces  came  to  be  supplemented  by  newer 
and  more  highly  specialized  organs  of  sense,  the  nervous 
centers  for  the  newer  senses  were  forced  to  take  up  more 
remote  and  complex  relations  to  the  motor  area,  while  the 
original  senses  did  not  lose  the  intimate  relation  which 
they  bore  from  the  first.  The  development  of  the  higher 
senses  furnished  also  opportunity  for  greater  variety  in  the 


56  >'  ROLOGY 

combination  impulses  ;  consequently  the  assrx 

functions  and  the  areas  corresponding  to  th  ascd 

with  tin-  developmen1  in  the  sensory  fund 

The  association  c<  hich  are  the  structural  areas  j. 

up  to  the  function  of  working  over  sensor)'  impulses,  natu- 
rally developed  between  the  centers  which  performed  func- 
tions of  reception,  or  the  sensory  functions,  and  those  which 
performed  the  functions  of  motor  discharge.  The  topogra- 
phy of  the  cerebral  centers  thus  reflects  directly  the  gradual 
evolution  of  more  and  more  elaborate  systems  of  nervous 
organizations. 

Speech  centers.  Another  group  of  facts  which  will  serve 
to  make  clear  the  character  of  the  association  areas  is  to  be 
found  by  examining  that  portion  of  the  cerebrum  which  is 
known  as  the  speech  area.  This  region  of  the  brain 
first  recognized  by  the  anthropologist  Broca  as  intimately 
related  to  the  functions  of  speech.  He  found  that  disease 
in  this  area  resulted  in  impairment  of  the  patient's  ability 
to  use  or  understand  language.  Later  studies  of  aphasia,  as 
the  pathological  loss  of  speech  is  called,  have  increased  our 
knowledge  of  this  area,  especially  since  it  has  become  pos- 
sible through  the  examination  of  a  large  number  of  cases 
to  distinguish  a  variety  of  forms  of  partial  aphasia.  Thus, 
a  person  may  be  able  to  understand  words  which  he  hears, 
but  be  quite  unable  to  understand  words  which  he  sees  on 
a  printed  page.  This  form  of  so-called  visual  aphasia  is 
paralleled  by  forms  of  auditory  aphasia,  in  which  the  subject 
is  able  to  read,  but  cannot  understand  words  which  he  hears 
spoken.  These  two  forms  of  partial  aphasia  indicate  that 
the  connection  between  the  speech  center  and  either  the 
auditory  or  visual  center  may  be  interrupted  without  destroy- 
ing the  connection  between  the  speech  center  and  the  other 
sensory  area.  If  the  disease  of  the  speech  center  is  strictly 
localized  so  as  to  interrupt  only  its  connection  with  the 
visual  center,  the  other  functions  may  remain  -intact,  while 


THE  HUMAN  NERVOUS   SYSTEM  57 

the  visual  forms  of  recognition  of  language  are  interrupted. 
Conversely,  if  the  connections  with  the  auditory  centers 
alone  are  interrupted,  visual  recognition  may  continue. 

Turning  now  to  the  various  forms  of  motor  aphasia,  or 
forms  affecting  the  power  of  expression  as  distinguished 
from  the  forms  of  sensory  aphasia  mentioned,  we  find  that 
an  individual  may  lose  the  power  of  articulation  without  los- 
ing the  ability  to  write,  or  he  may  lose  the  ability  to  write 
without  losing  the  ability  to  articulate.  In  either  one  of 
these  forms  of  motor  aphasia,  the  subject  may  be  compara- 
tively free  from  sensory  deficiencies.  The  lack  of  ability  to 
articulate,  when  all  of  the  other  phases  of  the  function  of 
speech  are  present,  shows  that  the  connection  with  the  visual 
and  auditory  centers  may  be  complete,  as  well  as  the  con- 
nection with  the  motor  area  for  the  hand  movement  involved 
in  writing,  while  the  motor  connection  with  the  center  which 
sends  impulses  to  the  muscles  of  the  vocal  cords  may  be 
temporarily  or  permanently  interrupted. 

Broca's  convolution  an  association  center.  Broca's  con- 
volution thus  turns  out  to  be  an  association  area  in  which 
a  great  variety  of  lines  of  connection  converge.  It  is  not  a 
part  of  the  nervous  system  which  acts  independently  in  the 
control  of  a  separate  faculty  of  speech ;  it  gains  its  signifi- 
cance in  the  individual's  life  as  a  center  for  the  organization 
of  stimulations  received  in  other  parts  of  the  cortex  and 
transmitted  through  the  cells  and  fibers  of  this  area  on  the 
way  to  the  motor  area. 

Phrenology  not  in  accord  with  clearly  known  facts.  It 
may  be  well  to  call  attention  at  this  point  to  the  fundamental 
distinction  between  the  teachings  of  phrenology  and  the  dis- 
coveries of  modern  brain  physiology.  Phrenology  maintained 
that  different  parts  of  the  brain  are  given  over  to  different 
faculties.  For  example,  phrenology  believed  in  a  certain  area 
for  the  recognition  of  form,  another  area  for  the  recognition 
of  number,  an  area  for  the  function  of  parental  love,  and  one 


58  PSYCHOLOGY 

for  the  general  trait  of  combat  ivcness.  There  is  no  justifica- 
tion for  a  theory  of  localization  based  upon  a  subdivision  of 
consciousness  into  such  mythological  :  The  cortex 

can  be  subdivided  into  areas  concerned  first  with  sensory 
impulses,  second  with  motor  impulses,  and  third  with  or. 

;>.  Conscious  processes  must  be  considered  as  having 
their  physiological  conditions,  not  in  separate  points  assigned 
to  imaginary  faculties,  hut  rather  in  the  organized  activity 
of  sensory,  motor,  and  association  areas.  For  example,  the 
recognition  of  form  naturally  includes  certain  sensory  func- 
tions and  certain  associative  processes.  The  general  neural 
basis  for  such  sensory  and  associative  processes  we  know, 
as  has  been  shown  in  the  foregoing  paragraphs.  To  be  sure. 
we  do  not  know  at  the  present  time  all  the  details  of  the 
cerebral  map,  but  the  broader  outlines  are  too  clearly  defined 
to  leave  any  room  for  mistaken  notions  with  regard  to  the 
kind  of  functions  which  are  provided  for  in  the  different 
areas  of  the  cerebrum. 

Frontal  association  area.  One  area  of  the  cerebrum  which 
has  been  the  subject  of  much  speculative  discussion  is  the 
frontal  area,  or  that  portion  of  the  cerebrum  which  lies  in 
front  of  the  motor  area.  In  certain  cases  large  portions  of 
this  area  have  been  destroyed  without  apparent  interference 
with  the  individual's  normal  functions.  There  is  a  famous 
case  known  as  the  American  Crowbar  Case,  in  which  a 
common  laborer,  through  an  accident  in  blasting,  had  a  very 
large  portion  of  this  frontal  lobe  removed  by  a  crowbar  pass- 
ing through  the  roof  of  his  mouth  and  out  through  the  top 
of  his  skull.  The  individual  in  question  continued  to  live 
with  no  serious  interruption  of  his  regular  nervous  or  phys- 
ical functions.  Such  cases  as  this  may  possibly  indicate 
that  the  association  areas  are  not  fully  developed  in  some 
individuals.  In  general,  it  is  doubtless  true  that  association 
areas,  more  than  other  parts  of  the  nervous  system,  are  left 
open  for  development  through  individual  experience.  If  this 


THE  HUMAN  NERVOUS  SYSTEM  59 

conception  is  accepted,  it  is  not  surprising  that  an  individual 
might  be  deprived,  as  in  the  case  cited,  of  the  possibility  of 
further  development,  or  even  of  some  of  his  higher  forms 
of  association  without  the  loss  being  obvious  to  himself  or 
to  those  who  observe  him.  Recent  experiments,  which  have 
been  tried  in  the  extirpation  of  the  small  frontal  area  in  cats 
and  monkeys,  show  clearly  that  the  frontal  area  is  the  part 
of  the  nervous  system  involved  in  newly  acquired  habits. 
The  fact  that  man,  who  alone  of  all  the  animals  has  a  large 
frontal  lobe,  is  the  learning  animal  par  excellence  further 
confirms  the  general  view  derived  from  these  experiments. 

General  principles  of  nervous  action.  It  remains  to  call 
attention  to  a  few  of  the  general  facts  which  are  known 
with  regard  to  action  within  the  nervous  organs. 

Active  organs  as  termini  of  all  nervous  impulses.  Nerve 
impulses  under  normal  conditions  always  travel  forward  in 
the  single  direction  from  the  sensory  centers  toward  the 
motor  centers.  There  is  no  reversing  of  a  nervous  current. 
If  it  were  otherwise,  a  central  nervous  process  might  travel 
down  a  sensory  fiber  and  arouse  the  sense  organ.  We 
should  see  colors  and  hear  sounds  whenever  the  central 
system  was  excited.  Under  normal  conditions  this  does  not 
happen.  The  sensory  impulses  come  only  from  the  sense 
organs  and  always  move,  even  though  the  path  be  complex, 
in  the  direction  of  the  motor  centers. 

Principle  of  facilitation.  When  currents  pass  through 
the  nervous  tissue  they  leave  behind  paths  or  tracts  which 
facilitate  the  later  transmission  of  like  impulses  over  like 
paths.  Indeed,  it  seems  that  in  many  cases  this  facilita- 
tion of  transmission  goes  far  enough  to  reduce  the  length 
of  the  path.  Where  the  first  transmission  was  over  a  long 
complex  path,  later  transmissions  reach  the  same  end  by 
a  more  direct  route. 

Principle  of  association  of  centers  of  high  tension.  When 
two  centers  in  the  cerebrum  are  in  simultaneous  action, 


60  PSYCHOLOGY 

there  is  a  tendency  for  a  path  or  connection  to  be  set  up 
between  the  :  crs  may  be  thought  of  as 

points  of  high  tension  and  th<  they  send  out 

tend  to  flow  together. 

Diffusion  as  opposed  to  organization.    Impulses  can  ti 
through  the  tissue  not  merely  along  the  paths  which  are 
defined  by  the  branches  of  the  cells  but  also  from  cell  body 
to  cell  body.    This  is  especially  true  in  the  early  stages  of 
the  life  of  an  individual  when   tracts  are  not  fully  d 
oped,  and  it  is  true  at  all  sfcu  ^dividual  development 

for  very  strong  stimulations.  The  result  of  such  indefinite 
transmission  is  a  diffuse  condition  of  excitement.  Such  dif- 
fusion is  often  the  first  stage  of  organization.  After  a  period 
of  diffusion,  paths  are  worked  out  to  carry  by  definite  chan- 
nels impulses  which  at  first  were  spread  vaguely  through  the 
nervous  tissue. 

Principle  of  progressive  organization.  Under  the  forego- 
ing principles  the  nervous  system  is  continually  becoming 
more  and  more  highly  organized.  The  effect  of  experience 
is  to  be  found  not  merely  in  the  fact  that  certain  paths  are 
recorded  in  the  nerve  cells,  but  also  in  the  fact  that  in  their 
totality  these  parts  develop  into  increasingly  complex  series 
of  interconnections.  This  is  the  essential  fact  which  must 
be  kept  in  mind  if  we  would  understand  the  progress  of  the 
individual  from  infancy  to  mature  mental  life.  Kach  day's 
experience  builds  up  new  systems  of  tracts  in  the  nervous 
tissues  and  thus  leads  to  higher  and  higher  levels  of  behavior 
and  experience. 

If  we  keep  this  formula  in  mind,  we  shall  be  able  to 
understand  the  higher  levels  of  consciousness.  Such  higher 
levels  are  always  due  to  the  interrelating  of  lower  forms  of 
experience.  Ideas  are  made  up  of  related  present  impres- 
sions and  the  results  of  past  impressions.  Thoughts  are 
made  up  of  interrelated  ideas.  The  formula  in  every  case 
is  one  of  more  and  more  complex  interrelations. 


CHAPTER   IV 

CLASSIFICATION  OF  CONSCIOUS   PROCESSES 

Classification  derived  from  study  of  nervous  organs.    The 

study  of  consciousness  has  often  been  taken  up  without  the 
preliminary  discussion  of  the  nervous  system  through  which 
the  foregoing  chapters  have  carried  us.  It  would  be  entirely 
legitimate,  as  remarked  in  an  earlier  chapter,  -to  begin  the 
study  of  mental  processes  by  looking  inward  on  one's  own 
experiences  and  describing  the  various  facts  which  intro- 
spection there  discovers.  The  array  of  facts  which  would 
thus  come  to  light  would,  however,  be  confusing  in  their 
variety  and  complexity.  It  is  much  simpler  to  approach  the 
facts  of  mental  life  with  the  type  of  classification  suggested 
by  the  knowledge  that  sensory  processes  enter  the  central 
organs  and  are  there  redistributed  and  organized  on  the  way 
to  the  motor  organs.  With  this  classification  to  guide  us, 
the  facts  of  experience  fall  into  order  and  lend  themselves 
to  orderly  scientific  treatment. 

Classification  from  observation  superficial.  An  analogy 
will  help  to  make  clear  the  difficulty  of  classifying  facts  on 
the  basis  of  unguided  observations.  If  an  ordinary  man  were 
asked  to  classify  the  organs  of  the  body,  he  would  begin  by 
pointing  out  the  arms  and  legs  as  important  subdivisions. 
Then  he  would  point  out  the  trunk  and  head,  and  so  on. 
The  student  of  physiology  realizes  that  these  gross  external 
subdivisions  are,  indeed,  important^  but  they  furnish  for 
science  an  inadequate  basis  of  study  as  contrasted  with  such 
fundamental  distinctions  as  those  between  muscles  and  bones, 
between  organs  of  respiration  and  organs  of  circulation,  and 

61 


62 

so  on.    The  moment  we  diude  up  tin-  U*ly  <»n  thesr 
mentioned  lines  oi  functional  differential 
<>ur   science    i.s    toll,,,,  ductive  trains  of  dcscn 

and   explanation. 

In   much  the  same  way  popular  distinctions  of  the  dif- 
ferent phases  of  exjx-rience  must  be  revised  before  tin 
be  used  by  science.    A  striking  illustration  of  this  is  to  be 
seen  in  the  fact  that  in  jxjpular  thought  pleasure  and  |>ain 
art-  usually  ta-atcd  as  facts  of  the  same  order,  though 
trasted  in  quality.     A   momei:  ;ion  will  make  it 

clear  that  pain  ordinarily  arises  from  some  definite  point  in 
the  body.    It  is  a  type  of  exjjcrience  which  v  :\   in 

science  along  with  those  experiences  which  come  from  the 
stimulations  of  the  skin  or  the  inner  surfaces  of  the  body 
and  are  technically  known  as  sensations.  Pleasure,  on  the 
other  hand,  has  a  totally  different  kind  of  origin.  It  is  not 
a  phase  of  sensation  ;  it  does  not  come  from  particular  points 
of  stimulation.  It  must  be  treated  as  a  type  of  experience 
which  grows  out  of  general  organic 'excitations  of  a  much 
more  central  character  than  those  which  are  involved  in  the 
production  of  pain.  Again,  such  a  term  as  "  attention,"  which 
has  a  large  practical  use  in  ordinary  life,  is  one  of  the  most 
confusing  terms  when  it  is  carried  over  into  scientific  study. 
If  one  recognizes,  as  he  must  in  psychology,  that  attention 
is  capable  of  a  great  variety  of  different  degrees,  he  will  find 
it  possible  to  extend  this  term  over  every  possible  experience. 
There  are  forms  of  intense  and  vivid  consciousness  for  which 
some  term,  such  as  "vividness"  or  "attention,"  is  undoubtedly 
required  in  science.  There  are  other  forms  of  consciousness 
which  are  relatively  vague  and  indistinct,  yet  when  dealing 
with  these  cases  we  cannot  fail  to  recognize  the  necessity  of 
>rd  "  attention  "  or  some  such  phrase  as  "  low 
degree  of  attention."  if  we  have  adopted  the  word  into  our 
scientific  vocabulary.  These  illustrations  make  clear  the 
problem  which  confronts  psychology  when  the  attempt  is 


CLASSIFICATION  OF  CONSCIOUS  PROCESSES    63 

made  to  secure  an  analysis  which  is  at  once  satisfactory 
for  purposes  of  scientific  treatment  and  explanation  and  in 
keeping  with  ordinary  introspective  observations. 

Historical  threefold  classification.  In  the  history  of  psy- 
chology many  efforts  have  been  made  to  develop  an  appro- 
priate scientific  classification  of  mental  processes.  One  of 
the  classifications  which  was  for  a  long  time  generally  ac- 
cepted is  that  which  grouped  all  forms  of  experience  under 
the  three  general  heads  of  knowledge,  feeling,  and  volition. 
There  can  be  no  doubt  that  such  a  threefold  classification 
describes  certain  fundamental  differences  in  conscious  ex- 
perience. The  man  who  is  engaged  in  thinking  out  some 
problem  of  science  is  certainly  not  at  that  moment  absorbed 
in  an  intense  feeling  or  emotion.  On  the  other  hand,  the 
man  who  is  thoroughly  angry  over  some  situation  which  has 
arisen  is  by  no  means  in  a  condition  to  consider  logically 
and  judiciously  the  facts  which  appeal  to  his  thoughtful 
neighbor  who  is  free  from  emotional  excitement.  It  is  some- 
what more  difficult  to  justify  the  classification  of  volition  as 
different  from  knowledge  and  feeling,  for  no  serious  thought 
is  possible  without  some  voluntary  effort,  and  no  emotion 
ever  arises  without  inducing  some  form  of  action.  Yet, 
even  though  volition  is  intimately  interwoven  in  all  forms 
of  knowledge  and  feeling,  there  are  certain  cases  of  decision 
which  are  not  to  be  regarded  as  typical  processes  of  know- 
ing, or  processes  of  feeling;  hence  the  term  "volition"  is 
needed  for  a  full  description  of  mental  activities. 

Historical  twofold  classification.  Another  somewhat  dif- 
ferent type  of  classification  has  been  used  by  certain  writers ; 
according  to  this,  only  two  different  types  of  experience 
are  distinguished ;  namely,  knowledge  on  the  one  hand,  and 
active  processes  on  the  other.  This  twofold  classification 
offers  less  difficulty  to  explanatory  science  than  the  three- 
fold classification,  because  it  is  more  general.  In  bringing 
together  a  great  variety  of  facts  under  the  active  processes 


'•4  I'M<  HOLOGY 

so  called,  we  arc  freed  from  the  necessity  of  making  any 
sharp  distinction  between  the  feelings,  which  are  undoubtedly 
active  aspects  of  consciousness,  and  decisions,  which  from 
any  point  of  view  must  be  regarded  as  active. 

Without  ignoring  jn  our  later  discussions  the  historic  dis- 
tinctions Ix/tween  knowledge,  feeling,  and  volition,  it  will  be 
possible  to  draw  from  our  study  of  the  nervous  system  a 
more  productive  classification. 

Classification  according  to  nervous  processes.  The  most 
fundamental  fact  discovered  with  regard  to  nervous  struc- 
tures was  that  they  couple  the  sense  organs  with  the  organs 
of  behavior.  Consciousness  arises  during  the  translation  of 
a  sensory  impression  into  a  motor  response.  Every  conscious 
process  will,  first  of  all,  have  certain  aspects  which  are  due 
to  the  sensory  impression  and,  second,  certain  other  aspects 
which  are  related  to  the  motor  response. 

Third,  every  nervous  process  in  its  passage  from  the  sense 
organ  to  the  point  of  discharge  encounters  certain  other 
nervous  processes  and  is  fused  with  them.  Consciousness 
is  in  an  important  sense  the  result  of  fusions  of  many 
impressions.  Whoever  would  understand  the  facts  of  experi- 
ence must  ask  how  they  are  built  up  out  of  the  combin, 
of  many  elements.  We  must  study,  therefore,  the  fusions 
which  condition  conscious  phenomena. 

Fourth,  every  sense  impression  on  its  way  to  the  motor 
discharge  is  modified  in  character  by  past  processes  in  the 
nervous  system.  The  past  is  brought  over  into  the  present 
by  the  structural  changes  which  are  recorded  in  the  nervous 
system  and  influence  every  new  impression  in  its  passage 
through  this  system. 

Fifth,  the  most  impressive  lesson  which  was  drawn  from 
the  study  of  the  evolution  of  animal  forms  was  that  in  the 
highest  nervous  systems  great  areas  are  set  aside  for  a  type 
of  indirect  recombinations  which  are  of  such  importance 
that  they  must  be  distinguished  from  the  fusions  referred  to 


CLASSIFICATION  OF  CONSCIOUS  PROCESSES    65 

under  third,  above.  The  recombinations  due  to  the  action 
of  the  association  areas  are  of  a  higher  order  and  are  to  be 
distinguished  as  indirect  or  abstract  processes. 

Example  of  scientific  analysis  and  classification.  The 
classification  of  facts  here  outlined  will,  perhaps,  be  better 
understood  if  an  example  is  used.  Let  one  look  at  a  printed 
word.  The  experience  which  results  may  seem  to  the  un- 
thinking observer  to  be  a  single  simple  process  of  recog- 
nition. A  moment's  consideration  will  bring  out  endless 
complexities.  In  the  first  place,  the  experience  breaks  up 
into  impression  and  interpretation.  There  is  a  part  of  the 
word-consciousness  which  comes  from  the  page,  a  part  which 
comes  from  past  experience.  The  part  of  the  experience 
which  comes  from  the  page  proves  on  closer  examination 
to  be  complex.  There  are  black  and  white  impressions  in 
sharp  contrast  with  each  other  which  fuse  into  the  complex 
image  of  letters  and  unite  into  a  single  image  of  a  word. 
There  are  motor  tendencies  which  often  are  vivid,  —  one 
tends  to  say  the  word,  or  there  is  an  incipient  impulse  to 
obey  its  dictates  as  one  realizes  in  one's  own  experience 
when  the  word  "  down  "  is  contrasted  with  the  word  "  up." 
Finally,  the  meaning  calls  up  elaborate  thought-processes 
which  carry  one  far  beyond  the  present  word  and  arouse 
associations  of  indefinite  complexity. 

This  example  serves  to  show  how  even  superficial  study 
of  a  single  experience  demonstrates  the  necessity  of  some 
plan  of  classification  under  which  the  various  aspects  of  a 
mental  process  may  be  described  and  explained.  Further- 
more, the  example  is  a  fortunate  one  with  which  to  demon- 
strate the  importance  of  those  indirect  elements  of  experience 
not  derived  from  sensation.  The  impression  is  the  least 
important  part  of  the  word-consciousness.  Our  scheme  of 
classification  is  important  not  merely  as  a  means  of  securing 
a  complete  description  but  also  as  clue  to  the  scientific  ex- 
planation of  mental  processes.  The  student  of  psychology 


66  PSYCHOLOGY 

must  constantly  keep  in  mind  the  necessity  of  standing 
outside  himself  and  getting  a  true  perspective  of  his  mental 
processes.  One  is  likely  to  ou-remphasizc  the  impression 
which  comes  from  without  and  to  overlook  one's  own  con- 
tribution ;  it  is  accordingly  the  business  of  scientific  psy- 
chology to  restore  the-  Ixnlance  and  give  a  true  emphasis  to 
that  which  comes  out  of  ;  .md  that  whi 

due  to  "the  central  and  motor  processes  which  attach  to  the 
impression. 

Relation  of  classification  to  introspection.  The  classifica- 
tion of  psychological  problems  is  therefore  frankly  borr- 
from  the  clue  furnished  by  the  study  of  the  nervou 
rather  than  left  to  the  accidents  of  introspection.  Intro- 
spection will  not  be  ignored,  but  the  facts  derived  by  looking 
into  experience  will  l>e  ordered  according  to  the  formula 
derived  from  objective  studies.  Perhaps  a  more  fortunate 
method  of  expression  will  be  to  say  that  the  classification 
having  been  determined  through  a  study  of  nervous  struc- 
tures, introspection  will  be  used  to  reveal  the  classes  of  facts 
which  the  study  of  the  nervous  system  teaches  are  important. 

Sensations.  First  we  shall  seek  facts  of  sensation.  Im- 
pressions come  to  us  from  the  outer  world  through  each 
of  the  senses.  Red,  green,  a  shrill  sound,  a  musical  tone, 
an  odor,  a  taste,  a  pressure  against  the  skin  are  typical 
cases  of  this  class.  There  is  no  difficulty  in  justifying  an 
examination  of  sensations. 

Reactions  and  attitudes.  Then  there  arc  reactions  to 
sensations.  In  some  cases  these  reactions  arc  very  direct; 
this  is  true  where  the  whole  process  is  simple.  Most  ex- 
periences have  grown  very  complex  and  the  reaction  to  the 
impression  comes  only  after  an  interval  during  which  the 
sensation  has  been  coupled  with  many  other  factors  of 
experience.  It  is  sometimes  extraordinarily  difficult  to  de- 
termine how  reactions  are  related  to  impressions.  The 
psychologist  finds  it  better  in  such  cases  to  postpone  the 


CLASSIFICATION  OF  CONSCIOUS   PROCESSES    67 

full  discussion  of  reaction  until  after  he  studies  the  complex 
of  facts  added  to  sensory  impressions.  A  complete  post- 
ponement of  the  study  of  reactions  would,  however,  make 
difficult  the  explanation  of  those  simple  processes  in  which 
the  reaction  follows  directly  on  the  impression.  The  reac- 
tions will  therefore  be  taken  up  first  in  an  introductory 
way  in  chapters  immediately  following  the  treatment  of 
sensations,  and  later  the  topic  will  be  amplified  by  a  study  of 
the  more  remote  and  complex  forms  of  organized  reaction. 

The  conscious  fact  which  parallels  a  reaction  deserves 
a  name.  The  word  "  attitude  "  serves  very  well  this  pur- 
pose. We  say  in  common  parlance  that  we  feel  an  attitude 
of  interest  or  disgust.  Our  study  will  show  us  that  all  atti- 
tudes of  mind  are  aspects  of  consciousness  related  to  reac- 
tions. We  have  attitudes  of  belief  and  incredulity,  attitudes 
of  sympathy  and  aloofness.  All  these  are  as  distinct  from 
sensations  as  facts  of  consciousness  can  be  from  each 
other.  We  shall  attempt  a  classification  of  some  of  the 
more  fundamental  attitudes. 

Fusion  and  perception.  The  term  "  fusion  "  suggests  cer- 
tain simple  combinations  of  sensory  facts  such  as  the  recog- 
nition of  an  orange  as  the  source  of  a  certain  color,  a 
certain  odor,  a  taste,  and  a  sensation  of  roughness  to  the 
touch.  In  experience  all  these  qualities  fuse.  They  are 
located  together  in  front  of  us  or  at  the  side.  They  make 
up  our  experience  of  an  object.  We  speak  of  the  expe- 
rience as  a  sense  percept. 

Memory.  The  term  "memory"  includes  a  great  many 
factors  of  which  we  make  use,  but  which  we  seldom  unravel 
from  the  complex  of  present  experience.  One  meets  a 
friend,  and  past  experience,  unnoticed  as  a  separate  aspect 
of  mental  life,  determines  one's  whole  recognition.  One 
reads  into  the  present  all  the  pleasant  associations  of  earlier 
days.  On  other  occasions  one  labors  to  call  up  some  for- 
gotten or  half-forgotten  fact.  The  effort  to  recall  noakes 


68 

one  actually  aware  of  the  distinction  between  the  present  and 
the  past.  Here  is  an  opportunity  in  treating  of  memory  to 
draw  productive  distim -tions  between  many  different  kinds 
of  memory. 

The  process  of  ideation.  There  are  ideas  and  combina- 
tions of  ideas  which  constitute  the  highest  forms  of  men- 
tal activity.  The  idea  which  one  has  when  he  thinks  of 
honesty  is  something  more  than  sensation  or  attitude  or 
memory ;  it  is  the  understanding  of  a  whole  series  of  rela- 
tions. We  speak  of  this  as  an  abstract  idea,  meaning  by 
that  term  that  we  have  cut  loose  from  impressions  and  are 
in  a  world  of  our  own  making.  The  processes  of  abstrac- 
tion exhibit  the  creative  power  of  a  highly  developed  indi- 
vidual as  no  other  mental  process  can.  The  animals  do  not 
have,  so  far  as  we  can  judge,  abstract  ideas.  They  have 
sensations,  attitudes,  percepts,  and  memories,  but  their 
powers  of  organization  stop  short  of  abstract  ideas. 

How  one  forms  an  abstraction  is  extremely  difficult  to 
observe  through  mere  introspection.  A  mind  absorbed  in 
studying  geometry  cannot  observe  itself  at  work.  That 
is  why  abstract  geometrical  ideas  are  difficult  to  explain. 
Obviously,  however,  the  system  of  psychology  which  omitted 
these  would  be  altogether  deficient. 

Higher  forms  of  action.  After  dealing  with  the  processes 
of  ideation  we  may  very  properly  come  back  to  a  reexam- 
ination  of  behavior.  Those  forms  of  behavior  which  are 
characteristic  of  mature  intelligence  are  commonly  grouped 
together  under  the  caption  "  voluntary  choice."  The  discus- 
sion of  voluntary  choice  will  not  duplicate  the  treatment  of 
reactions  and  attitudes  as  indicated  on  page  66. 

Relation  to  historic  classification.  The  foregoing  classi- 
fication is  to  be  followed  in  the  following  chapters.  For  the 
sake  of  keeping  it  in  some  relation  with  the  historic  classi- 
fications, it  may  be  said  that  the  term  "  knowledge  "  is  in 
a  measure  synonymous  with  sensation,  perception,  memory, 


CLASSIFICATION  OF  CONSCIOUS  PROCESSES    69 

and  ideation.  Feeling  and  volition  are,  roughly  speaking, 
synonymous  with  attitudes,  while  the  higher  forms  of  be- 
havior classified  under  voluntary  choice  are  quite  synony- 
mous with  the  higher  phases  of  volition.  The  effort  should 
not  be  made,  however,  to  push  this  reconciliation  of  the 
two  classifications  too  far.  There  is  a  large  element  of 
effort  and  hence  of  volition  in  every  fusion  and  every 
formation  of  an  abstraction.  There  is  a  large  element  of 
feeling  in  most  perceptions.  The  adoption  of  a  classifi- 
cation of  psychological  facts  based  on  studies  of  nervous 
processes  is  a  frank  abandonment  of  the  historic  threefold 
classification. 

Practical  applications.  Following  the  study  of  the  various 
classes  of  psychological  facts  will  be  certain  studies  of  a 
practical  type  which  may  be  termed  applications  of  psy- 
chology. A  part  of  these  applications  will  be  formulated 
with  a  view  to  helping  the  student  to  see  his  own  mental 
processes  from  a  psychological  point  of  view.  A  part  will 
deal  with  some  of  the  larger  social  problems,  with  a  view  to 
showing  that  community  life  is  capable  of  proper  organiza- 
tion only  through  a  complete  understanding  of  the  nature  of 
human  consciousness. 


SUMMARY 

The  following  summary  of  the  foregoing  discussion  will  serve 
as  a  guide  to  the  subsequent  chapters : 

I.  Sensations 

This  will  require  a  description  of  the  sense  organs  and  their 
action  and  a  description  of  those  aspects  of  consciousness  which 
come  as  impressions  from  the  outer  world. 
II.  Attitudes 

This  will  require  an  explanation  of  the  relation  of  consciousness 
to  bodily  activity  and  a  classification  of  forms  of  conscious  ex- 
periences which  arise  as  a  result  of  the  individual's  reactions  to 
impressions. 


70  PSYCHOLOGY 

III.  Fusions  of  Sensations 

As  sensations  become  motives  or  sources  of  reactions  they  are 
united  into  complexes.  These  complexes  are  called  percepts  and 
are  always  present  where  an  individual  distinguishes  objects  in 
the  world  about  him 

IV.  Memories 

j>cricnces  are  retained  in  structural  changes  in  the 
nervous  system  and  either  in  explicitly  distinguishable  form  or  in 
less  obvious  character  enter  into  present  experience.  Psychology 
must  include  under  this  head  many  facts  which  escape  introspec- 
tion. Here  as  elsewhere  throughout  the  discussion  the  largest 
regard  must  be  had  for  the  fact  that  the  explanatory  prin- 
ciples of  psychology  depend  on  a  clear  understanding  of  motor 


V.    Ideas  and  Ideational  l-'orms  «.|  Thought 

These  include  all  the  higher  forms  of  organized  experience. 
They  are  conditioned  by  the  higher  complexes  which  are  de- 
veloped in  the  cerebral  association  areas. 

VI.  Voluntary  choice  is  the  phrase  employed  to  mark  off  the  highest 
forms  of   behavior   from   the   lower  forms.     The  concept  of 
personality  enters  into  this  discussion. 
VII.  Applications  to  individual  experience  and  to  social  organizations. 


CHAPTER  V 

SENSATIONS 

Sensations  not  copies  of  external  forces.  For  the  ordinary 
man  there  is  no  problem  for  psychology  presented  by  a 
sensation.  A  sensation  is  for  his  thinking  an  inner  reflec- 
tion or  copy  of  an  external  fact.  He  dismisses  as  curious 
speculation  any  statement  which  would  tend  to  impair  his 
confidence  in  the  directness  of  the  relation  between  sensa- 
tions and  external  or  objective  facts.  Yet,  as  was  pointed 
out  in  an  earlier  chapter,  the  progress  of  science  has  forced 
upon  us  a  distinction  between  objective  colors  and  sounds, 
on  the  one  hand,  and  subjective  or  experienced  sensations 
of  color  and  sound,  on  the  other  hand.  For  example,  color 
as  we  see  it  in  our  individual  experiences  is  not  a  form  of 
vibration,  while  color  as  the  physicist  finds  that  he  must 
describe  it  in  order  to  explain  its  physical  nature  is  a  form 
of  wave  motion  easily  convertible  into  other  wave  motions, 
such  as  those  of  heat,  which  in  turn  give  us  sensations  of 
a  sort  quite  different  from  colors. 

Laws  of  sensation  as  one  of  the  first  problems  in  psychol- 
ogy. The  moment  we  admit  a  distinction  between  subjec- 
tive color  and  external  light  vibrations,  certain  important 
scientific  questions  immediately  suggest  themselves.  Thus, 
we  are  led  to  inquire  what  are  the  laws  of  subjective  color 
as  distinguished  from  the  physical  laws  of  objective  light  ? 
For  example,  in  passing  from  one  color  in  the  subjective 
series  to  the  next  color,  as  from  red  through  orange  and 
yellow  to  green,  we  find  ourselves  taking  a  series  of  steps 
and  reaching  qualitative  differences  so  marked  that  we 

71 


72 

speak  of  the  sensations  as  opposite  or  as  sharj  xted. 

This  marked  difference  in  qualities  is  related  to  animal 
interests  of  a  practical  sort.  Red  fruits  and  green  arc  to  be 
distinguished;  the  color  of  the  foliage  and  of  the  blossom 
are  to  be  discriminated.  In  p!  tion  from  the 

red  vibration  to  the  <^recn  is  one  continuous  series  of  changes 
in  rate  of  vibration.  All  the  vibrations  arc  qualitatively  alike  ; 
there  is  nocontrast.  So  far  as  li^ht  vibrations.!:  med, 

they  are  utterly  heedless  of  animal  interests. 

\ample  of   the   difference   l>et\vecn    the  su! 
tive"Series  and  the  physical  se;  .  be  found  in  the  fact 

that  sensations  arise  only  from  the  middle  of  certain  j  >': 
cal  series.    Thus  the  physicist  knows  that  there  arc  rays  of 
light  made  up  of  vibrations  slower  than  those  which  give 
us  sensations  of  red,  and  that  other  rays  are  more  rapid  in 
vibration  than  those  which  give  sensations  of  violet.     The 
range  of  sensations  of  sound,  in  like  fashion,  is  short, 
trasted  with  the  series  of  sound  vibrations   known  to  the 
physicist. 

Relation  of  sensations  to  sensory  nervous  processes.  The 
relation  between  sensations  in  consciousness  and  ph 
logical  processes  in  the  organs  of  sense  is  much  closer 
than  is  the  relation  between  sensations  and  the  physical 
facts  above  discussed.  Thus,  to  take  a  striking  illustration, 
it  is  because  we  have  an  organ  of  sense  which  is  affected 
by  light  and  no  special  organ  affected  by  weak  currents  of 
electricity  that  men  overlooked  for  so  long  a  period  both 
the  prevalence  of  forms  of  electrical  energy  and  the  close 
relation  between  light  and  electricity.  Such  an  illustration 
calls  attention  to  the  fact  that  experience  differs  in  certain 
of  its  aspects  from  the  physical  world,  because  experience 
is  related  to  the  physical  world  only  indirectly,  through  the 
organs  of  sense. 

Other  examples  are  abundant.    When  the  ear  is  aroused 
by  the  complex  sound  coming  from  a  drum  and  a  trumpet, 


SENSATIONS  73 

there  are  sensations  corresponding  to  each  element  of  the 
complex  because  the  sensory  cells  receive  the  vibrations 
from  one  instrument  at  one  point  and  the  vibrations  from 
the  other  at  another  point.  The  two  elements  of  sound 
do  not  obliterate  each  other  or  cause  a  blur  in  conscious- 
ness. They  do  not  give  rise  to  a  single  sensation,  even 
though  the  sound  wave  which  strikes  the  ear  is  a  single 
complex  air  vibration.  The  further  details  of  this  matter 
will  come  out  in  later  sections  of  this  chapter. 

Sensations  as  elements.  Our  first  problem,  then,  is  to 
study  sensations  as  related  to  the  facts  of  physics  and  to 
the  facts  of  physiology  of  the  sense  organs.  Later,  we 
shall  study  sensations  in  their  relation  to  one  another  and 
to  the  higher  forms  of  experience.  It  will  then  be  pointed 
out  that  sensations  as  they  appear  in  consciousness  are 
always  elements  of  complex  forms  of  knowledge.  There  i§ 
no  such  experience  as  an  isolated  sensation  of  red  or  of 
green  or  of  sound.  All  sensations  are  referred  to  some 
point  in  space ;  they  are  associated  with  certain  interpreta- 
tions and  otherwise  brought  into  the  stream  of  personal 
experiences.  But  in  all  these  later  combinations,  sensations 
retain  their  qualitative  independence  to  an  extent  which 
justifies  us  in  recognizing  them  for  the  purposes  of  science 
as  elements,  or  separate  and  distinct  aspects  of  conscious- 
ness. The  problems  of  fusion  of  sensations  with  each  other 
and  the  laws  of  these  fusions  may  therefore  properly  be 
postponed  ;  for  the  present,  we  turn  to  a  discussion  of  sen- 
sations as  elements  of  consciousness  related  to  certain  facts 
of  physics  and  to  the  processes  in  the  organs  of  sense  which 
lie  between  the  physical  world  and  consciousness. 

Psycho-physics  as  a  division  of  psychology.  The  field  of 
study  which  we  here  enter  has  sometimes  been  called 
psycho-physics.  This  name  originated  as  the  name  of  one 
branch  of  the  study  of  sensations  to  which  our  introductory 
examples  have  not  -referred.  Psycho-physics  in  its  earlier 


74  I'SM  ii 

days  studied  especially  the  facts  of  intensity  of  sen&r 

1  sound  becomes  stronger,  it  does  not  follow 
that  the  ivlutcd  sensations  will  become  stronger  in  a  corre- 
sponding degree.  The  facts  of  intensity  will  be  r-ferrcd  to 
briefly  in  our  later  discussions. 

In  taking  up  the  problems  of  psycho-physics,  we  shall 
begin  \\ith  one  of  the  most  highly  developed  and  highly 
differentiated  groups  of  sensory  processes;  namely,  those  of 
vision.  \\  e  nii^ht  have  taken  first  the  simpler  sensations, 
sikh  as  those  of  touch,  but  the  facts  regarding  color  are  so 
much  more  complex  and  significant  that  it  will  be  advanta- 
geous to  encounter  at  once  all  the  major  principles  involved 
in  such  a  study. 

A.   VISUAL  SENSATIONS 

Meaning  of  term  "  quality."  Visual  sensations,  like  all 
sensations,  can  be  described  only  to  a  person  who  has 
experienced  them.  Red  and  blue  and  yellow  and  black  are 
names  of  visual  sensations.  If  the  reader  has  had  experi- 
ences corresponding  to  these  words,  he  will  recognize  that 
each  of  the  experiences  referred  to  is  a  unique  fact  in  his 
mental  life.  Red  may  be  like  orange  or  yellow;  it  may  be 
soft  and  pleasing,  or  glaring  and  unpleasant ;  but  its  essence 
is  its  redness,  and  this  essence,  which  is  called  the  quality 
of  the  sensation,  can  be  illustrated  but  cannot  be  defined  in 
terms  of  any  other  experience. 

Chromatic  (or  color)  series  and  achromatic  (or  gray)  series. 
If  we  consider  all  possible  visual  sensations,  we  notice  at 
once  that  there  are  two  general  groups,  —  those  which 
belong  in  the  series  of  colors  and  those  which  belong  in  the 
black-gray-white  series.  The  latter  series  is  in  some  respects 
the  simpler.  Beginning  with  the  darkest  black,  one  may 
arrange  various  shades  of  gray  in  an  unbroken  series  up  to 
the  brightest  white.  The  color  series  is  more  complex.  It 
is  made  up  of  sensation  qualities  which,  to  be  sure,  shade 


SENSATIONS  75 

into  each  other  through  intermediate  colors  ;  but  the  members 
of  the  series  have  a  marked  individuality  which  leads  us  to 
designate  them  by  a  variety  of  entirely  different  names 
rather  than  by  a  common  term,  such  as  is  used  in  referring 
to  the  gray  series.  Thus,  red  and  yellow  are  different  quali- 
ties, though  they  shade  into  each  other  through  orange ; 
when  we  pass  from  one  to  the  other,  the  transition  is  so 
marked  that  we  are  compelled  to  describe  red  and  yellow  as 
different  qualities. 

Fundamental  color  names.  The  question  of  how  many 
fundamental  visual  qualities  there  are,  is  one  that  has  often 
been  discussed.  Popular  language  has  clearly  marked  out 
at  least  four  color  qualities  besides  the  blacks,  grays,  and 
whites.  These  four  colors  are  red,  yellow,  green,  and  blue. 
The  names  of  these  colors  are,  as  their  form  clearly  indi- 
cates, older  than  such  derived  names  as  orange,  indigo, 
violet,  or  any  of  the  compound  names,  such  as  green-blue 
and  yellow-green.  The  loose  use  of  the  four  older  color 
names  makes  it  clear,  however,  that  there  is  no  particular 
red  or  green  which  can  be  selected  as  having  exclusive  right 
to  the  name.  In  making  up  a  system  of  color  terminology 
for  such  works  of  reference  as  a  dictionary,  this  fact  comes 
out  very  clearly.  The  best  that  can  be  done  is  to  take  the 
average  of  a  large  number  of  usages  and  exhibit  a  sample 
of  the  color  chosen.  Color  names,  therefore,  while  suggest- 
ing something  of  the  popular  discrimination  of  colors,  supply 
no  final  evidence  as  to  the  number  of  primary  sensation 
qualities. 

The  various  scientific  studies  on  this  subject  of  the  number 
of  color  qualities  may  be  divided  into  three  groups.  One 
group  regards  red,  green,  and  blue  as  the  only  primary 
colors,  all  others  being  looked  upon  as  derived  forms.  A 
second  group  adds  yellow,  while  a  third  group  considers  that 
there  are  an  indefinitely  large  number,  certainly  more  than 
four.  The  solution  of  the  question,  since  it  does  not  depend 


I'SY<  II«  •! 


'  >r,i  ,.,;«• 


f/r.rn 


merely  upon  introspective  obs<  fa  u\x>n  the  com- 

plete formulation  of  certain  facts  discussed  later. 

The  color  spectrum  and  circle.  More  important  than  the 
determination  of  the  exact  number  of  primary  color  qualities 
is  the  presentation  of  a  complete  description  of  the  series 
of  color  experiences.  The  most  complete  single  series  of 
colors  known  to  physics  is  produced  by  passing  a  pencil 
of  white  light  through  a  prism.  The  different  colors  which 

compose  this  ray  of 
white  light  will  be 
refracted  to  different 
positions,  and  the 
whole  will  be  spread 
out  into  a  colored 
band  with  red  at  one 
end  and  violet  at 
the  other.  Between 
these  lie  orange,  yel- 
low, green,  blue,  in 
Bive  the  order  given. 

FIG.  23.  Color  circle  This  whole  series  of 

The  center  of  the  circle  represents  white.  All  colors  colors  produced  from 
placed  at  opposite  ends  of  diameters  of  the  circle  .  .  ... 

are  complementary  color,  ^^    ^t    IS    Called 

the  spectrum.  M 

colors  are  not  present  in  the  spectrum,  notably  purple,  which 
consists  of  a  mixture  of  red  and  blue.  When  purple  is  intro- 
duced, the  series  of  colors  seems  to  return  upon  itself.  For 
this  reason,  the  colors  of  the  spectrum  plus  purple  may  con- 
veniently be  represented  by  a  closed  figure,  either  a  triangle 
or  a  circle.  The  color  circle  is  given  in  Fig.  23.  Four,  or 
better  nine,  color  names  are  used  to  indicate  some  of  the 
chief  qualities  of  the  series,  the  exact  number  of  such  quali- 
ties being  left  somewhat  indefinite,  for  reasons  indicated 
above.  Between  the  colors  explicitly  named  in  this  circle 
there  are  transitional  forms  of  sensations. 


SENSATIONS 


77 


Saturation,  brightness,  and  mixtures.  There  are  also 
transitional  forms  of  sensation  from  this  color  series  to  the 
gray  series.  Thus,  from  any  color  there  is  a  series  of  sen- 
sations in  which  the  color  quality  gradually  fades  into  a 
colorless  gray  of  the  same  intensity  as  the  original  color. 
Such  a  series  is  called  a  saturation  series.  The  full  color 
is  said  to  be  a  saturated  quality ;  the  more  the  quality  ap- 
proaches gray,  the  less  saturation  it  is  said  to  have.  Each 
color  is  also  capable  of  variations  in  brightness.  A  red  of 


FIG.  24.    Wave  forms 

great  light  intensity  is  said  to  have  a  high  degree  of  bright- 
ness. A  color  of  small  light  intensity  is  said  to  have  a  low 
degree  of  brightness.  The  relation  of  brightness  to  satura- 
tion is  such  that  when  a  color  becomes  very  bright  or  very 
dim  its  characteristic  quality  tends  to  disappear.  Finally, 
color  qualities  may  be  compounded  so  as  to  produce  a  great 
variety  of  intermediate  qualities,  such  as  orange-yellow  and 
blue-green,  which  are  sometimes  thought  of  as  intermediate 
qualities,  sometimes  as  equally  primary  with  the  others. 


;8  l'>\« 

External  light.    Turning  now  from  the  series  of  visual 
sensations,  let  us  re,  the  characteristics  of 

external   physical  light.    The  ph\  cognizes  physical 

light  as  a  form  of  vibration  in  the  luminifcrous  ethct 
ctlu-r  vibrations  have  three  i  iui.u  u-nstics ;  namely,  rate  of 
vibration,  amplitude  of  vibration,  and  complexity  of  vibr.r 

purposes  of  exposition  we  may  compare  light  waves  to 
simple   water    \\aves,   which   arc  represented   in   outlin 
Fig.  24.    In  waves  of  this  type  a  single  panicle  of  water 
oscillates  up  and  down  in  straight  lines,  while  the  wave  as 
a  whole  travels  in  the  horizontal  direction. 

The  rapidity  with  which  each  particle  oscillates  is  called 
the  rate  of  vibration.  The  rate  determines  the  length  of 
the  waves  from  crest  to  crest,  so  that  we  may  refer  to  v. 
as  having  different  lengths  :  rapid  vibrations  corresponding 
to  short  wave  lengths,  and  the  slow  vibrations  corresponding 
to  greater  wave  lengths.  The  amplitude  of  a  wave  is  de- 
termined by  the  extent  of  the  oscillations  of  each  particle. 
The  complexity  of  a  wave  depends  on  the  mode  of  the 
movement  of  the  particles ;  a  complex  movement  results 
from  the  action  of  a  number  of  wave  impulses  acting  on  the 
same  particle  at  the  same  time. 

The  wave  forms  represented  in  A,  Fig.  24,  have  like 
amplitude  —  that  is,  like  range  of  movement  above  and  be-low 
the  horizontal  line  —  but  differences  in  rate,  one  wave  being 
twice  as  rapid  as  the  other.  The  waves  in  />  arc  alike  in 
rate  but  different  in  amplitude.  The  lines  I,  2,  3,  4,  5,  6 
show  the  paths  of  six  single  particles  which  participate  in 
the  larger  wave  motion.  When  a  particle  is  in  its  original 
position,  it  lies  at  some  point  along  the  horizontal  lir. 
at  O.  At  successive  periods  it  moves  to  the  height  i.  _\ 
or  3  or  to  the  low  level  4,  5,  or  6.  C  represents  a  complex 
wave  form.  The  two  regular  waves,  indicated  in  dotted  lines, 
acting  upon  the  particles  together,  result  in  the  complex 
form  of  vibration  represented  in  the  full-drawn  line. 


SENSATIONS 


79 


Comparison  of  physical  and  mental  series.  In  the  follow- 
ing table  a  comparison  is  exhibited  between  the  physical  facts 
and  the  corresponding  facts  of  sensory  experience  : 


PHYSICAL  FACTS 


FACTS  OF  SENSORY  EXPERIENCE 


Simple  light  vibrations  of  medium 
amplitude 

These  simple  vibrations  appear  in 
every  possible  rate,  thus  forming 
a  single  continuous  series  of  varia- 
tions in  rate 

These  rates  vary  from  less  than 
435  million  million  vibrations  per 
second 

(435  million  million  vibrations  per 

second) 
through  all  possible  rates 

to  769  million  million  vibrations 

per  second 
and  beyond 

Compound  vibrations 

The  compound  sometimes  consists 
of  vibrations  of  about  435  to  500 
million  million  per  second,  com- 
bined with  those  of  about  660-769 
million  million  per  second 

In  some  cases  widely  different  rates 
are  combined,  sometimes  in  special 
pairs,  sometimes  in  more  complex 
groups 

In  some  cases  various  rates  other 
than  those  above  mentioned  are 
combined 

Amplitude  variations 

Increase  in  amplitude  to  the  highest 

Decrease  in  amplitude  to  the  lowest 


Color  sensations 

The  sensations  differ  in  certain  well- 
marked  stages,  forming  a  series 
of  distinct  color  qualities,  limited 
in  number 

No  color  experience  (sometimes 
experience  of  warmth) 

Red 

Successive  qualities  (yellow,  green, 

blue) 
Violet 

No  color  experience 

Either  whites,  grays,  less  saturated 

colors,  or  purples 
Purple 


White  or  gray 


Various  grays  and  unsaturated  colors 


Changes  in  intensity  and  saturation 
Increase  in  intensity  and  decrease 

in  saturation  toward  white 
Decrease  in  intensity  and  in  satura- 
tion toward  black 


8O  fCHOD 

Relation  between  the  physical  and  the  psychical  facts 
dependent  in  part  on  the  organs  of  sense.  The  differences 
between  the  phys  <-s  and  the  sensation  scries  are  so 

striking  that  much  scientific  investigation  has  been  devoted 
to  the  effort  to  bridgt  he  differences,  as  far  as  possi- 

ble, by  setting  between  the  two  groups  of  processes  described 
in  the  above  table  a  third  group  of  processes ;  namely,  the 
physiological  processes  in  the  eve  and  central  nervous  sys- 
tem. Not  infrequently  it  has  been  impossible,  with  the 
means  of  scientific  investigation  in  our  possession,  to  dis- 
:  by  direct  observation  all  the  physiological  links  be- 
tween certain  physical  facts  and  certain  facts  of  expert 
In  such  cases,  theories  have  been  developed  by  science  to 
fill  the  gap.  These  theories  go  beyond  direct  observation 
in  their  statements,  but  do  so  with  definite  regard  to  such 
facts  as  can  be  observed.  We  turn,  therefore,  to  a  con- 
sideration of  some  of  the  physiological  facts  and  theories, 
taking  up,  as  a  necessary  introduction  to  the  physiological 
facts,  a  study  of  the  structure  of  the  eye. 

Evolution  of  organ  of  vision.    The  human  eye  is  a  \ 
complex  and  highly  sensitive  organ.    It  will  be  well  for  us 
in  attempting  to  understand  the  eye,  to  go  back  to  an  earlier 
point  in  the  evolutionary  series  and  begin  our  study  with 
more  primitive  visual  organs.    The  line  of  evolution  bet v 
the  simplest  eyes  and  the  human  eye  is  not  direct,  for  the 
human  eye  is  in  its  sensitive  parts  a  division  of  the  brain 
brought  to  the  surface  of  the  body.    The  eyes  of  inverte- 
brates show,  however,  how  sensitivity  to  light  first  became 
a  specialized  function  of  animal  tissue. 

Even  in  the  lowest  forms  of  plant  and  animal  life  there 
is  a  certain  sensitiveness  to  light.  A  flower  is  affected  by 
light,  in  some  cases  enough  to  produce  movement  on  its 
stem,  in  all  cases  in  its  inner  growth  conditions.  So  also  the 
unicellular  animal  forms  are  stimulated  by  light  to  vigorous 
action.  In  the  simpler  multicellular  animals,  in  addition  to 


SENSATIONS  81 

the  differentiation  between  neural  cells  and  muscular  cells 
which  was  described  in  an  earlier  chapter,  there  is  a  further 
differentiation  among  the  neural  cells.  In  the  jellyfish,  for 
example,  it  is  found  that  at  certain  points  on  the  surface  of 
the  body  the  cells  of  the  nervous  system  are  grouped  into 
small  spots  of  pigmented  cells  (see  Fig.  25,  A).  The  pig- 
ment is  not  a  part  of  the  nervous  system,  but  it  serves  to 
absorb  the  light  which  falls  upon  this  part  of  the  animal's 
body  more  than  do  the  unpigmented  regions.  The  result 
is  that  the  influence  of  the  light  is  enhanced  by  the  pres- 
ence of  the  pigment,  and  the  growth  of  larger  and  more 
sensitive  sensory  cells  in  the  immediate  neighborhood  of 
these  spots  brings  about  a  condition  which  is  favorable  to  the 
reception  of  light.  We  may,  for  convenience,  refer  to  the 
pigment,  since  it  is  not  true  nervous  tissue,  as  an  accessory 
organ.  We  shall  find  in  the  study  of  later  developments  of 
the  eye  that  the  accessory  parts  of  the  eye  are  quite  as  im- 
portant as  the  nervous  organs  themselves,  the  evolution  of 
the  two  groups  of  structures  going  on  in  parallel  lines. 

Higher  forms  of  visual  organs  are  represented  in  Fig.  25, 
B  and  C.  Thus  we  find  a  larger  group  of  cells  sensitive  to 
light  stimulations.  The  pigment  is  present  as  in  the  most 
primitive  eyes,  and  the  whole  organ  is  placed  in  a  depression 
in  the  surface  of  the  body.  This  depression  serves  to  protect 
the  delicate  cells  more  effectively,  than  they  could  be  pro- 
tected on  the  general  body  surface,  as  in  the  case  of  the 
jellyfish.  This  protection  of  the  cells  undoubtedly  works  to 
the  advantage  of  the  cells,  furnishing  them  the  conditions 
necessary  for  becoming  more  sensitive,  while  at  the  same 
time  the  wall  of  the  depression  furnishes  them  the  space  in 
which  they  become  more  numerous.  In  later  stages  of  de- 
velopment, as  indicated  in  Fig.  25,  D  and  E,  the  depression 
in  the  body  wall  is  filled  with  a  protecting  fluid.  This  fluid 
is  of  a  thick,  gelatinous  consistency,  and  in  the  most  primitive 
forms  translucent,  not  transparent.  The  light  stimulation 


FIG.  25.  A  series  of  eyes  which  have  reached  various  levels  of  development* 

82 


SENSATIONS  83 

which  acts  upon  the  sensory  cells  of  such  an  eye  as  this 
will  obviously  not  be  very  intense  or  definite.  Something 
has  been  sacrificed  to  protection  in  the  fluid,  which  obstructs 
the  light.  This  disadvantage  is,  however,  more  than  offset 
by  the  fact  that  the  fluid  furnishes  favorable  conditions  for 
increase  in  the  number  and  sensitiveness  of  the  cells.  Such 
an  eye  as  this  cannot  distinguish  more  than  vague  changes 
in  illumination.  An  opaque  object  passing  before  the  animal 
might,  by  its  shadow,  be  recognized  as  something  standing 
between  the  animal  and  the  light,  but  the  form  or  distance  of 
the  object  certainly  could  not  be  recognized  except  through 
the  intensity  of  the  shadow  and  the  period  of  its  duration. 
A  bright  object  would  give  a  somewhat  more  definite  im- 
pression, but  nothing  comparable  to  the  impression  received 
by  the  eyes  of  the  higher  animals. 

Later  stages  of  development  of  the  eye  are  represented 
in  the  figure.  In  Fig.  25,  D,  E,  and  F,  it  will  be  seen  that 
the  outer  covering  of  the  eyes  begins  to  develop  a  lens.  In  the 
earliest  forms,  this  lens  is  spherical  in  shape.  Such  a  shape 
is  mechanically  simple,  but  optically  very  imperfect.  The 
image  which  it  throws  on  the  sensory  surface  is  distorted, 
and  the  different  rays  of  light  are  focused  at  different  points, 
causing  the  hazy  colored  fringes  technically  known  as  chro- 
matic aberrations. 

Organ  of  sense  as  selective  organ.  Such  an  evolutionary 
series  as  that  just  described  could  be  made  the  basis  of  a 
chapter  on  the  relations  of  the  animal's  inner  life  and 

*  Fig.  25,  A,  shows  a  simple  pigment  spot.  The  ordinary  epithelial  cells  which  con- 
stitute the  surface  of  the  body  are  represented  at  a.  The  pigment  particles  repre- 
sented at  pa  make  this  portion  of  the  surface  of  the  body  more  susceptible  to  the 
action  of  light.  Fig.  25,  B,  shows  a  somewhat  more  highly  developed  organ.  The 
surface  of  the  body  is  here  depressed  so  as  to  protect  the  sensory  cells.  These 
specialized  cells  are  notably  larger  than  the  epithelial  cells  at  aa.  This  is  the  eye 
of  Patella.  Fig.  25,  C,  represents  the  eye  of  Nautilus.  The  central  cavity  is  filled 
with  water.  Fig.  25,  D,  is  a  camera  eye  with  a  large  lens  filling  its  cavity  ;  op  repre- 
sents the  lens.  Fig.  25,  />,  is  the  camera  eye  of  Murex  with  the  cornea,  c,  covering 
the  lens.  Fig.  2;,  F,  is  the  complete  eye  of  cuttlefish  with  the  lens,  /;  cornea,  c; 
iris,  /',  and  other  portions  as  before.  (From  Conn's  ''  Method  of  Evolution") 


M  PSYCHOLOGY 

development  to  the  outer  world  of  nature.    1      :     • 
greatly  to  the  animal's  advantage  to  be  so i  to  changes 

in  light  and  thus  also  to  gain  indirectly  impressions  from  all 
objects  which  reflect  or  absorb  light.  The  inner  life  processes 
are  very  dependent  on  these  impressions ;  the:  part 

of  the  organism  is  set  aside  to  keep  watch  and  guide  the 
organ  I:  <:  .nism  is  thus  enabled  to  select  from 

the  world  in  which  it  lives  those  impressions  which  ha 
do  with  its  own  existence.  Furthermore,  as  we  shall  find 
when  we  come  to  study  other  organs  of  sense,  other  parts 
of  the  body  surface  are  specialized  to  keep  the  animal  in 
contact  with  aspects  of  the  outer  world  other  than  light. 
The  organs  of  sense  are  accordingly  to  be  defined  as  special- 
ized avenues  through  which  forces  of  the  external  world 
that  are  important  to  the  animal's  life  affect  the  organism. 

The  human  eye  —  its  muscles.  We  pass  over  the  varying 
forms  of  visual  organs  exhibited  in  the  animal  world  and 
take  up  briefly  the  human  eye.  The  human  eye  is  an  inde- 
pendent organ  separated  from  the  body  wall  and  placed  in 
a  protecting  bony  cavity  or  eye  socket.  Before  taking  up 
the  internal  structure  of  the  eyeball  it  may  be  well  to  refer 
to  the  external  muscles  which  hold  it  in  place  and  move  it 
about  independently  of  the  head.  These  arc  important  acces- 
sory organs  and  increase  the  range  of  vision  greatly  by  mak- 
ing it  possible  to  move  the  eyes  easily  without  moving  the 
head.  The  human  eye  is  supplied  with  six  such  muscles. 
By  means  of  these  muscles  the  eye  is  capable  of  rotation, 
with  the  nicest  adjustments  in  any  direction  whatsoever. 
In  ordinary  life  the  behavior  of  one  eye  is  closely  related 
to  the  behavior  of  the  other  eye,  so  that  the  muscles  coop- 
erate in  producing  certain  joint  movements,  or  binocular 
movements  as  they  are  called. 

Many  of  the  facts  of  human  vision  are  closely  related  to 
the  fact  that  the  eyes  are  themselves  very  active  organs. 
Looking  at  an  object  involves  a  great  deal  of  muscular 


SENSATIONS  85 

adjustment.  Looking  to  the  left  involves  a  different  type  of 
muscular  adjustment  from  that  involved  in  looking  straight 
ahead.  These  facts  should  be  borne  in  mind  as  important 
for 'much  of  our  later  study. 

The  outer  wall  and  the  lens.  A  sectional  view  showing 
the  internal  structure  of  the  eyeball  is  given  in  Fig.  26. 
It  will  be  noted  immediately  that  this  organ  is  in  many 


FIG.  26.    Diagrammatic  section  of  the  human  eye 

O,  optic  nerve ;  S,  sclerotic ;  C,  cornea;  ^4,chorojd  coat;  7,  iris;  /?,  retina  ;  T"",  vitreous 

humor ;  hf,  aqueous  humor ;  L,  crystalline  lens  ;  X,  optic  center  of  the  lens  ;  6,  blind 

spot ;  /,  fovea  centralis ;  /,  pupil ;  J/,  ciliary  muscles,  which  control  the  curvature 

of  the  lens  ;  O6,  object  outside  of  eye  ;  />»,  image  on  the  retina.    (After  Wundt) 

respects  more  highly  developed  than  any  of  the  eyes  repre- 
sented in  Fig.  25.  By  the  development  of  an  independent 
outer  wall  of  cartilage  the  eyeball  has  been  made  a  free 
portion  of  the  body,  as  noted  in  the  last  paragraph.  In  the 
second  place,  it  will  be  observed  that  the  lens,  which  we 
saw  in  some  of  the  lower  forms  as  a  spherical  organ,  has 
been  elaborated  in  the  course  of  animal  evolution,  so  that  it 
now  has  the  very  much  more  advantageous  form  of  a  double 
convex  lens,  indicated  in  the  figure  at  L.  This  lens  has 
certain  other  complexities  in  structure  which  tend  to  free  it 


from  optical  defects.     It   is   not  homogeneous  throughout; 
furthermore,  by  means  of  tin  idjustable  diaphragm, 

i  is  placed  in  front  of  it,  only  the  center,  which  is  the 
most   efficient   |*>rtion   of   the  lens,    is   utilized    in  ordinary 

:\.  By  means  of  certain  muscles  which  form  a  t 
around  the  lens  and  control  a  transparent  capsule  v 
surrounds  it,  tin-  lens  can  be  modified  in  form  so  that 
made  more  or  less  convex  according  as  light  which  is  to  be 
focused  upon  the  sensor)'  surface  comes  from  a  source  near 
at  hand  or  far  away.  The  details  of  this  adjustment  of  the 
lens  need  not  be  discussd  here ;  it  is  enough  to  caU  atten- 
tion to  the  fact  that  when  the  eye  is  to  look  at  an  object  far 
away,  the  lens  is  relatively  less  convex  than  when  the  eye 
is  looking  at  an  object  near  at  hand.  The  adjustment  is 
carried  out  reflexly.  There  are  limits  beyond  which  it  is 
impossible  for  the  lens  to  adjust  itself ;  the  near  limit  for 
the  normal  eye  is  about  eight  inches  from  the  eye,  the  re- 
mote limit  for  the  normal  eye  is  at  an  infinite  distance. 
Individual  imperfections  in  adjustment  appear.  For  example, 
the  lens  in  old  age  becomes  somewhat  less  elastic  than  in 
early  life  and,  because  of  this  lack  of  elasticity,  it  is  incapable 
of  taking  on  a  high  degree  of  convexity.  Other  abnormali- 
ties appear,  in  that  the  far  limit  of  certain  eyes  is  at  a  rela- 
tively short  distance  in  front  of  the  eye ;  a  person  whose 
limit  of  remote  vision  is  thus  nearer  than  a  point  infinitely 
far  away  is  described  as  near-sighted.  Most  of  the  defects 
in  the  functioning  of  the  lens  can  be  relieved  more  or  less 
completely  by  the  use  of  an  artificial  lens  outside  of  the 
The  function  of  the  artificial  lens  is  exactly  that  of  the  lens 
in  the  eye,  and  the  possibility  of  correcting  defects  in  the 
lens  of  the  eye  by  various  combinations  of  glass  lenses  is 
limited  only  by  the  possibilities  of  physical  optics.  This 
makes  it  perfectly  clear  that  the  lens  is  not  to  be  treated 
as  a  part  of  the  nervous  system  but  rather  as  an  accessory 
organ  developed  for  the  purpose  of  applying  the  stimulus 


SENSATIONS  87 

to  the  organ  of  sense  in  such  a  way  as  to  produce  a  clearly 
defined  image  on  the  retina. 

Transparent  media.  In  the  human  eye  all  of  the  media 
through  which  the  light  must  pass  are  highly  transparent. 
A  certain  portion  of  the  outside  coat  of  the  eye  —  namely, 
that  portion  which  lies  directly  in  front  of  the  lens  —  is  trans- 
parent. Between  this  transparent  wall,  or  so-called  cornea, 
and  the  lens  of  the  eye  there  is  a  chamber  filled  with  trans- 
parent fluid  known  as  the  aqueous  humor.  The  lens  itself 
is  of  a  very  high  degree  of  transparency.  Back  of  the  lens 
is  a  mass  of  gelatinous  matter  known  as  the  vitreous  humor, 
which  fills  the  whole  eyeball  and  maintains  the  proper 
spherical  form  of  the  eyeball.  These  transparent  media  are 
products  of  evolution  and  show  an  important  advance  over 
the  translucent  gelatinous  substances  which  we  find  in  the 
more  primitive  eye. 

Choroid  coat.  The  pigment  layer  which  was  seen  in  the 
most  primitive  eyes  is  present  in  the  human  eye  in  the  so- 
called  choroid  coat.  It  covers  the  whole  inner  surface  of 
the  eyeball.  It  serves  the  same  purpose  as  does  the  black 
lining  of  a  camera ;  that  is,  it  prevents  the  rays  of  light 
which  have  acted  upon  the  sensory  surface  from  being 
reflected  back  so  as  to  interfere  with  other  entering  rays. 
It  is  richly  supplied  with  blood  vessels,  which  provide  for 
the  nutrition  of  the  sensory  cells. 

The  retina.  We  have,  up  to  this  point,  referred  only  to 
the  accessory  organs  of  the  eye.  We  turn  now  to  the  exam- 
ination of  the  retinal  surface,  which  is  the  true  sensory 
organ.  It  is  made  up  of  a  series  of  layers  of  cells  dis- 
tributed over  the  inner  surface  of  the  eyeball  and  placed 
between  the  choroid  coat  and  the  vitreous  humor.  The 
retinal  layer  is  represented  in  section  in  Fig.  27.  The  rods 
and  cones,  which  constitute  the  inner  layer  lying  next  to 
the  choroid  coat,  are  undoubtedly  the  organs  which  are 
most  immediately  affected  by  the  rays  of  light.  The  rods 


PSYCHOLOGY 


and  cones  are  highly  devel<>j>cd  cells  which  are  specialized 

for  the  n  of  light  stimulations.  1  h<-v  may  be 

thought  of  as  small  ves- 
sels containing  chemical 
substances  which  are 
especially  susceptible  to 
changes  under  the  action 
of  light.  The  clu-mical 
activity  set  up  in  the  rods 
and  cor.  :hc  light 

which  enters  the  eye 
liberates  energy,  which 
is  transmitted  through 
the  successive  layers  of 
cells  represented  in  the 
figure  until,  finally,  it 
reaches  the  large  nerve 
cells  of  the  retina,  indi- 
d  at  the  level  VIII  in 
the  figure.  The  energy 
which  originally  entered 
the  eye  in  the  form  of 
vibration  in  the  luminif- 
erous  ether  is  thus  trans- 
formed into  chemical 
action  in  nerve  cells,  and 
the  chemical  action  in  the 
nerve  cells  is  transmitted 
to  the  fibers  which  pass 
out  of  the  eyeball  and 
communicate  with  the 
central  nervous  system. 
Rods  and  cones  and  their  functions.  The  rods  and  cones 

undoubtedly  represent  different  types  of  receiving  organs. 

The  central  part  of  the  retina,  which  is  more  important  for 


FIG.  27.    A  diagrammatic  section  of  the 
retina 

/  is  the  pigment  epithelium,  //  is  the  layer  of 
rods  and  cones.  The  rods  are  the  small,  slender 
organs.  In  the  retina  the  rods  and  cones  are, 
throughout  the  larger  pan  of  the  organ,  mixed 
together ;  in  the  fovea  only  cones  appear.  ///, 
IV,  V,  VI,  VII  show  various  intermediate  struc- 
tures between  the  rods  and  cones  and  the  nerve 
cells  which  are  situated  at  J7/7.  From  the  nerve 
cells  at  /'///  the  optic  fibers  pass  out,  as  indi- 
cated at  IX,  toward  the  blind  spot,  where  they 
leave  the  eyeball.  X  represents  the  limiting 
membrane  of  the  retina.  A  ray  of  light  entering 
the  eye  passes  through  the  retina  in  the  direc- 
tion from  X  to  //.  The  light  does  not  produce 
any  effect  upon  the  cells  or  fibers  until  it  reaches 
the  layer  of  rods  and  cones.  (After  Greeff) 


SENSATIONS  89 

clear  vision  than  other  portions,  is  made  up  of  cones  exclu- 
sively. Passing  from  this  limited  central  region  of  clear 
vision,  known  as  the  fovea  centralis,  toward  the  outer  areas, 
or  periphery,  of  the  retina,  the  rods  become  more  and  more 
numerous.  The  functional  differences  which  correspond  to 
these  structural  facts  can  be  easily  observed.  Let  a  colored 
light  of  moderate  size  and  intensity  be  brought  into  the 
outer  part  of  an  observer's  field  of  vision.  This  light  will 
cast  its  image  on  the  periphery  of  the  retina  where  the  rods 
predominate,  and  the  observer  will  not  experience  a  color 
sensation  but  rather  a  sensation  of  colorless  light.  If,  now, 
the  colored  light  is  gradually  made  to  approach  the  center 
of  clear  vision  where  the  cones  predominate,  its  color  quality 
will  become  more  and  more  obvious,  until,  finally,  at  the 
center  of  clear  vision  it  will  be  clearly  seen.  We  may  state 
this  result  in  general  form  by  saying  that  the  center  of  clear 
vision  is  also  the  center  of  color  vision,  while  the  areas  at 
the  extreme  periphery  of  the  retina  are  totally  color  blind. 
The  areas  intermediate  between  the  extreme  periphery  of 
the  retina  and  the  center  of  clear  vision  are  partially  color 
blind  ;  that  is,  they  respond  to  a  limited  number  of  colors. 
This  limitation  of  ability  to  respond  to  colors  is  offset  in 
the  rods  by  a  distinct  advantage  on  the  side  of  susceptibility 
to  slight  changes  in  colorless  light.  An  observer  very  fre- 
quently has  the  experience  early  in  the  evening  of  seeing  a 
faint  star  in  the  outer  edge  of  the  'field  of  vision,  and  finds 
the  moment  he  turns  to  look  directly  at  the  star  that  it  is 
impossible  to  see  it.  The  periphery  of  the  retina  was  suffi- 
ciently sensitive  to  the  slight  illumination  to  make  possible 
a  sensation  from  the  faint  star,  whereas  the  center  of  the 
retina  was  incapable  of  responding  to  this  slight  illumina- 
tion. The  significance  of  this  differentiation  of  the  retina  in 
the  development  of  the  animal  kingdom  is  evident.  The 
periphery  of  the  retina  and  the  extreme  edges  of  the  field 
of  vision  do  not  have  the  same  significance  for  the  animal 


90  !>\<  HOLOGY 

as  the  center.  It  is  more  advantageous  that  the  animal  should 
be  able  to  concentrate  its  highest  forms  of  nervous  ait 
upon  a  limited  area.  <  in  the  other  hand,  it  is  inijxutant  that 
the  outer  regions  of  the  retina  should  be  sensitive  in  such 
a  way  as  to  give  immediate  warning  of  any  changes  in  illu- 
mination, for  changes  in  illumination  mean  movement,  pos- 
sibly the  approach  of  danger,  and  this  should  be  recognized 
sufficiently  to  warn  the  observer.  If,  then,  it  is  desirable  to 
•;ive  the  object  stiictcr  attention,  the  eye  can  be  turned  so  as 
to  bring  the  image  upon  the  center  of  clear  vision. 

Color  blindness.  The  differentiation  between  the  different 
parts  of  the  retina,  which  has  just  been  described  as  charac- 
teristic of  the  normal  retina,  does  not  always  appear.  There 
are  certain  persons  who-  are  not  fully  responsive 

to  colors ;  these  persons  have  at  the  center  of  the  retina  a 
condition  similar,  at  least  so  far  as  color  processes  are  con- 
cerned, to  that  which  appears  toward  the  j>eriphcry  of  the 
normal  retina.  This  inability  to  respond  to  different  color 
stimulations  may  in  some  cases  be  complete,  so  that  the 
individual  sees  the  world  as  a  normal  individual  sees  an 
engraving ;  that  is,  as  if  it  were  made  up  only  of  differences 
in  light  and  shade  without  the  qualitative  differences  which 
we  describe  as  color  differences.  A  much  larger  number 
of  individuals  have  a  partial  deficiency,  analogous  to  that 
which  appears  in  the  intermediate  zones  of  the  normal 
retina.  The  various  forms  of  partial  color  blindness  are 
extremely  difficult  to  define  with  precision,  for  the  simple 
reason  that  the  color  sensations  of  the  partially  color-blind 
individual  constitute  his  world  of  color  sensations.  He 
usually  has  no  means  of  comparing  his  experiences  with 
those  of  the  normal  individual.  His  efforts  to  describe  his 
own  experiences  to  a  normal  individual  are  complicated 
by  the  necessity  of  using  terms  devised  for  the  normal 
individual  rather  than  for  his  own  peculiar  experiences. 
Fortunately  for  science,  there  have  been  a  few  cases  in 


SENSATIONS 


which  the  same  person  has  been  able  to  observe  directly 
both  the  normal  color  sensations  and  the  partially  color- 
blind series.  The  defect  in  such  individuals  appears  only 
in  one  eye,  while  the  other  eye  is  of  the  normal  type.  It 
has,  furthermore,  been  possible  by  certain  methods  of  com- 
paring color  mixtures  to  make  an  analysis  of  other  cases  of 
color  blindness.  The  net  result  of  these  investigations  has 
been  to  show  that  the  color  series  of  a  partially  color-blind 
individual  is  of  a  simpler  type  than  that  of  the  normal  in- 
dividual with  a  fully  developed  retina.  One  very  common 
form  of  partial  color  blindness,  known  as  "  red-green  blind- 
ness," has  been  thoroughly  investigated.  The  following 
table  shows  the  comparison  between  the  normal  color  system 
and  the  two  types  of  red-green  blindness,  which  have  been 
worked  out : 


NORMAL 

TYPE  I 

TYPE  II 

Red 

The  red  end  of  the  spec- 

Yellow 

trum  short  ;  what  is  seen 

is    gray,    or   unsaturated 

yellow 

Orange 

Unsaturated  yellow 

Unsaturated  yellow 

Yellow 

Unsaturated  yellow 

Unsaturated  yellow 

Green 

Yellow 

Gray,  or  unsaturated  yellow 

Blue 

Blue 

Blue 

Violet 

Violet 

Violet 

Such  facts  as  are  shown  in  this  table  and  in  the  cases 
of  total  color  blindness  emphasize  the  intimacy  of  the  rela- 
tion between  retinal  development  and  the  development  of 
experience.  They  make  it  clear  that  the  number  of  sensa- 
tion qualities  which  an  observer  can  distinguish  depends 
not  on  the  number  of  physical  processes  in  the  outer 
world  but  on  the  number  of  physiological  processes  which 
are  aroused  in  the  nervous  system  by  the  various  kinds  of 
physical  energy. 


92  VCHOLOGV 

Color-mixing.  Another  group  of  facts  closely  related  to 
those  discussed  above  arc  the  facts  of  color-mixing.  If  a 
given  point  on  the  retina  is  stimulated  at  the  same  time  by 
two  or  more  rays  of  differently  colored  light,  the  chemical 
process  set  up  cannot  be  the  process  which  is  appropriate 
.then  color  acting  alone.  Experience  shous  that  the 
process  is  a  comprom;  ren  the  processes  which  \\ 

have  resulted  if  each  ray  had  acted  alone.  Thus,  if  at  the 
same  moment  a  ray  of  red  light  and  a  ray  of  yellow  light 
fall  ti|x>n  a  single  cone,  the  result  is  that  the  observer  sees 
orange,  which  corresponds  in  quality  to  the  color  lying  in 
the  spectral  series  intermediate  between  red  and  yellow.  If 
instead  of  merely  using  red  and  yellow  we  use  red,  yellow, 
and  blue  at  the  same  time,  we  find,  by  observing  the  r< 
ant  sensation,  that  a  compromise  between  the  three  chemical 
tendencies  in  the  cone  is  very  different  from  any  one  of  the 
processes  taken  alone.  Indeed,  in  such  a  case  the  retina 
is  not  capable  of  giving  a  compromise  color  process,  but 
falls  back  into  the  process  which  the  study  of  color  blindness 
shows  to  be  the  most  primitive  form  of  chemical  activity ; 
namely,  the  chemical  process  corresponding  to  gray,  which 
we  found  as  the  only  process  in  the  eye  of  the  totally  color- 
blind person  and  in  the  periphery  of  the  normal  retina. 
When  all  the  colors  of  the  spectrum  fall  at  one  time  on  a 
cone,  as  in  full  daylight,  the  result  is  a  sensation  of  pure 
brightness  or  white. 

If  a  red  ray  is  mixed  with  a  blue  ray,  a  unique  compromise 
process  results,  which  is  not  directly  related  to  any  of  the 
simple  colors  of  nature ;  namely,  the  process  which  gives 
rise  to  a  purple  sensation.  Purple  is  a  color  quality  which 
can  be  explained  only  in  terms  of  the  retinal  process.  Red 
and  blue,  which  are  the  physical  facts  conditioning  the  ex- 
perience of  purple,  are  at  the  extreme  ends  of  the  physical 
spectral  series,  yet  they  cause  in  the  retina  a  single  process 
which  gives  the  sensation  quality  purple.  This  goes  to  show 


SENSATIONS  93 

that  the  retinal  processes  for  red  and  blue  are  closely  related 
in  character,  in  spite  of  the  great  difference  in  the  respective 
rates  of  vibration  in  the  physical  processes  which  excite 
these  retinal  processes.  The  color  circle,  which  was  described 
in  an  earlier  paragraph,  is  therefore  not  to  be  explained  as 
a  physical  circle  but  as  a  circle  of  retinal  processes  and 
corresponding  experiences.  Indeed,  it  may  be  said  in  gen- 
eral that  the  laws  of  color-mixing  are  primarily  laws  of  retinal 
behavior  rather  than  laws  of  the  physical  world.  The  fact 
that  all  the  colors  of  the  spectrum  when  mixed  together 
produce  gray  is,  as  has  been  pointed  out  a  number  of  times, 
a  physiological  fact  and  a  fact  of  experience  rather  than  a 
fact  of  physical  vibrations. 

The  principles  of  color  mixtures  were  worked  out  first  by 
physicists  and  have  furnished  a  basis  for  most  of  the  theories 
of  color  vision.  Briefly  stated,  the  general  principles  of 
color-mixing  are  as  follows  :  When  two  colors  near  each 
other  in  the  spectral  series  enter  the  eye  at  the  same  time, 
there  results  a  sensation  and  a  retinal  process  which  is  inter- 
mediate to  those  demanded  by  the  two  colors  when  they  act 
alone  upon  the  retina.  This  intermediate  process  is  not  the 
same  as  that  which  would  result  from  stimulation  of  the 
retina  by  the  intermediate  pure  color,  for  the  sensation  is 
not  as  fully  saturated  as  it  would  be  if  it  had  resulted  from 
the  action  of  a  pure  color.  As  the  distance  between  the  two 
colors  of  the  mixture  is  gradually  increased,  the  chromatic 
quality  of  the  resultant  grows  less  and  less  marked,  until 
finally  the  sensation  is  of  .the  simplest  possible  type  ;  namely, 
the  sensation  gray.  This  shows  that  the  retina  is  forced 
by  certain  mixtures  of  very  different  colors  to  return  to  the 
simple  undifferentiated  form  of  activity  which  characterized 
it  before  the  differentiation  into  chromatic  qualities  began. 
Two  colors  which  are  opposed  to  each  other  in  such  a  way 
that  they  give  when  mixed  no  color  whatsoever,  but  merely 
the  sensation  gray,  are  known  as  complementary  colors. 


.,4  ''    M»  >I  ' 

It  the  distance  in  the  color  circle  between  two  colon  win.  h 
mixture  is  greater  than  that  required  for  the 
complementary  effect,  the  resulting  color  will  be  some  shade 
of  purple.  If  purple  is  introduced  in  the  color  circle,  there 
is  no  shade  of  color  which  does  not  have  its  complement. 
The  color  circle  shown  in  Fig.  23  may  be  made,  therefore, 
the  basis  for  discussion  of  complementary  pairs,  provided  the 
arrangements  of  the  colors  opposite  each  other  are  made 
with  this  end  in  view.  If  more  than  two  colors  arc  mixed, 
the  total  result  will  be  the  sum  of  the  partial  effects  and 
can  be  foreseen  by  considering  the  partial  processes  as  if 
they  occurred  successively. 

Pigment-mixing  subject  to  physical  law.  It  may  be  well 
to  call  explicit  attention  to  the  fact  that  the  statements  here 
made  regarding  color  mixtures  do  not  apply  to  mixtures 
of  pigments.  The  mixture  of  pigments  is  a  physical  fact, 
v  not  a  physiological  process.  The  action  of  pigment  on  light 
is  to  absorb  certain  rays  and  reflect  others.  Mixtures  of 
pigments  affect  light  in  a  complex  way,  and  hence  produce 
results  which  cannot  be  explained  by  merely  inspecting  the 
separate  pigments. 

A  single  case  of  pigment-mixing  may  be  taken  as  an  ex- 
ample. Thus,  if  yellow  and  blue  pigments  are  mixed,  they 
produce  an  impression  of  green.  This  result  is  due  to  the 
fact  that  the  yellow  pigment  absorbs  a  good  deal  of  light 
and  reflects  only  those  colors  which  are  near  it  in  the  spectral 
series.  Blue  does  the  same.  The  only  color  which  sur 
the  joint  absorptions  of  yellow  and  blue  pigment  particles  is 
green,  for  green  is  reflected  in  a  measure  by  both  yellow 
pigment  particles  and  by  blue.  The  fact  that  green  results 
in  this  case  calls  for  an  explanation  absolutely  different 
from  that  which  applies  to  the  gray  which  results  from  the 
mixture  of  yellow  and  blue  light. 

After-images.    The  consideration  of  certain  other  facts  is 
necessary  to  complete  the  discussion  of  visual  sensations. 


SENSATIONS  95 

If  light  acts  upon  a  retinal  element  for  a  given  period,  the 
effect  will  continue  for  a  time  after  the  external  light  ceases 
to  act.  The  observer  will  notice  what  is  known  as  an  after- 
image of  the  light  at  which  he  has  been  looking.  Every- 
one has  doubtless  observed  the  vivid  after-images  which 
result  from  looking  at  the  sun  or  other  very  bright  objects. 
Most  of  the  after-images  which  we  receive  from  ordinary 
objects  are  so  faint  that  they  are  overlooked,  unless  special 
effort  is  made  to  notice  them  and  to  retain  them.  In  gen- 
eral, the  experience  which  continues  after  the  withdrawal  of 
the  external  light  resembles  only  for  a  very  brief  interval  the 
sensation  originally  produced  by  the  external  light.  So  long 
as  the  original  impression  and  after-image  are  of  the  same 
quality,  the  observer  is  said  to  have  a  positive  after-image. 
An  example  of  such  a  positive  after-image  can  easily  be 
secured  by  rapidly  rotating  a  burning  stick  in  a  circle,  when 
the  observer  will  see  an  uninterrupted  circle  of  light,  because 
the  stimulus  returns  to  each  of  the  points  of  the  retina 
before  the  original  process  has  had  time  to  change.  Very 
soon  after  the  external  stimulus  is  withdrawn,  experience 
undergoes  a  radical  change.  The  general  principle  of  this 
change  may  be  described  by  saying  that  every  black  changes 
to  white,  every  white  to  black,  and  every  color  to  its  comple- 
ment. Since  these  changes  are  known  from  the  conditions 
to  be  due  to  physiological  processes  rather  than  to  external 
light,  we  describe  the  conditions  for  these  after-images  in 
the  following  terms  :  The  retina  tends  to  set  up  as  soon  as 
possible  a  process  opposite  to  that  which  was  produced  by 
the  original  stimulus.  This  chemical  process,  opposite  in 
character  to  that  produced  by  the  external  stfmulus,  is  due 
to  the  tendency  of  the  physiological  organism  to  restore  the 
chemical  substances  which  have  been  used  up  in  the  first 
process  of  stimulation.  The  experience  of  the  observer  fol- 
lows, during  this  process  of  recuperation,  the  retinal  activity 
rather  than  the  external  physical  fact.  Thus,  after  looking 


96  l'>\«  HOLOGY 

for  a  time  at  a  brilliant  red  light,  the  observer  sees  very 
soon  after  the  light  is  withdrawn  a  colored  area  of  like 
spatial  form  and  extent  as  the  original  but  of  a  quality  ex- 
actly complementary  to  the  red  ;  namely,  blue-green.  In  like 
fashion,  the  negative  alter  -linage  of  a  blue  surface  is  yellow. 
If  the  stimulating  surface  is  black  and  white  or  gray  rather 
than  colored,  the  negative  after-image  will  be  of  such  a 
charaeter  that  what  was  bright  in  the  original  image  will  ap- 
pear dark  in  the  after-image,  and,  conversely,  what  was  dark 
in  the  original  image  will  appear  white  in  the  after-image. 

Contrasts.  After-effects  in  the  retina  very  frequently 
operate  to  modify  the  retinal  processes  produced  by  subse- 
quent light  stimulations.  For  example,  let  an  observer  who 
has  been  looking  steadily  at  a  bright  red  light  for  a  time 
and  has  a  strong  tendency  toward  a  green  after-image  look 
at  a  blue  surface  ;  the  blue  surface  will  not  be  seen  in  its 
normal  color,  but  will  be  seen  as  a  mixture  of  blue  and 
green,  the  green  being  contributed  in  this  case  by  the  after- 
image process  in  the  retina.  The  mixtures  between  after- 
effects and  color  stimulations  here  under  discussion  give 
rise  to  many  forms  of  color  contrast.  In  view  of  the  con- 
tinual movement  of  the  eye  from  point  to  point  in  the 
field  of  vision,  the  observer  is  always  carrying  more  or 
less  marked  after-effects  from  a  given  part  of  the  field  of 
vision  to  the  neighboring  parts.  If,  for  example,  a  red  and 
a  green  field  are  placed  in  close  juxtaposition,  and  the  eye 
after  looking  at  the  red  surface  tends  to  move  in  such  a 
way  as  to  bring  a  portion  of  the  retina  which  has  been 
stimulated  by  the  red  into  a  position  such  that  it  will 
be  stimulated  by  the  green  light,  the  green  sensation  re- 
ceived from  the  summation  of  the  external  stimulation  and 
the  after-image  will  be  more  intense  than  a  green  sensation 
received  without  the  preliminary  stimulation  from  a  red. 
The  result  is  that  green  seems  to  be  more  saturated  when 
it  lies  near  red.  In  general,  every  color  is  emphasized  by 


SENSATIONS  97 

being  brought  into  close  relation  with  its  complementary, 
and  grays  tend  to  take  on  colors  complementary  to  sur- 
rounding fields.  This  effect  appears  even  when  no  eye 
movements  can  be  detected.  There  is  probably  a  diffusion 
of  contrast  effects  through  the  retina  even  when  the  eye 
fixates  steadily  a  single  point. 

The  tendency  of  grays  to  take  on  colors  may  be  well 
illustrated  by  shadows.  If  a  field  which  is  illuminated  by  a 
yellow  light  is  interrupted  by  a  shadow  which  is,  in  reality, 
gray,  this  gray  shadow  will  take  on  a  bluish  tinge  by  con- 
trast with  the  yellow  field.  This  fact  has  long  been  observed 
by  those  who  reproduce  the  colors  of  nature  in  painting,  and 
the  shadows  in  painting  will  usually  be  found  to  be,  not 
reproductions  of  the  physical  facts,  but  rather  reproductions 
of  the  impression  made  upon  the  observer. 

Theories  of  color  vision.  Jt  remains  to  add  a  few  remarks 
concerning  the  less  certain  conclusions  regarding  the  rela- 
tion between  light  sensations  and  external  ether  vibrations. 
The  effort  has  frequently  been  made  to  describe  the  physi- 
ological processes  in  a  single  comprehensive  formula  or 
theory,  which  shall  include  all  the  facts.  No  attempt  will 
here  be  made  to  review  all  of  those  theories.  It  will  be 
enough  to  present  one  of  the  simplest  and  most  sug- 
gestive, and  leave  it  to  the  student  to  criticize  and  recon- 
struct it  in  the  light  of  the  facts  discussed  above  and 
reviewed  in  the  tables  given  below. 

Mrs.  Franklin's  genetic  theory  of  processes  in  the  retina. 
The  theory  which  was  formulated  by  Mrs.  Franklin  is  as 
follows  :  The  primitive  retina  of  the  lower  animals  and  the 
periphery  of  the  human  retina  have  only  one  chemical 
process  with  which  to  respond  to  all  light  stimuli.  This 
single  chemical  process,  when  set  up  through  the  action 
of  light,  arouses  in  the  central  nervous  system  a  process 
which  is  the  condition  of  a  gray  sensation.  This  is  the 
original  undifferentiated  type  of  retinal  activity.  As  the 


..s  PSYCHOLOGY 

evolution  of  the  retina  goes  forward,  this  original  chemical 
process,  which  may  be  called  the  gray  process,  is  so  subdi- 
vided that  colors  produce  certain  partial  phases  of  tin- 
original  chemical  activity.  The  partial  chemical 
produce  each  a  specialized  form  of  nervous  process  and 
a  specialized  form  of  sensory  experience.  The  breaking  up 
of  the  gray  process  into  special  color  processes  begins  with 
a  development,  first,  of  tin-  partial  processes  which  < 
spond  on  the  one  hand  to  blue,  and  on  the  other  hand  to 
orange  or  yellow,  sensations.  This  first  differentiation 
responds  to  the  wide  difference  between  the  extrerm-  ends 
of  the  spectral  series.  The  original  ^ray  pn» 
disapjK'ar  with  the  rise  of  the  blue  and  yellow  processes, 
but  remains  as .  the  neutral  and  more  general  form  of 
response.  At  this  stage  the  yellow  and  blue  processes  are 
each  called  out  by  a  great  variety  of  stimulations.  Thus, 
the  yellow  process  is  aroused  by  red  light,  orange  light,  and 
tureen  li^ht.  as  well  as  by  yellow  light.  As  the  development 
goes  on,  the  yellow  chemical  process  is  subdivided  into 
more  highly  specialized  processes,  corresponding  to  red 
and  green.  The  result  of  this  succc.-si\e  differentiation  of 
process  is  that  the  highly  organized  retina  may,  when 
stimulated  by  the  appropriate  form  of  light  vibration 
spond  with  specialized  chemical  processes  to  red,  green, 
yellow,  or  blue.  If  yellow  and  blue,  which  were  the  first 
forms  of  light  to  arouse  differentiated  processes,  act  at  the 
same  time  upon  the  retina,  the  partial  processes  which  are 
differentiated  out  of  the  gray  cannot  both  be  in  action  at 
once  without  being  swallowed  up  in  the  original  funda- 
mental process  of  gray.  If  red  and  green  act  together  upon 
the  retina,  the  yellow  process  appears  as  the  more  funda- 
mental form  of  chemical  process.  The  facts  of  color  blind- 
ness can  be  explained  by  stating  that  the  differentiation  of 
chemical  processes  is  not  complete  in  the  color-blind  eye. 
Negative  and  complementary  after-images  are  due  to  the 


SENSATIONS 


99 


physiological  instability  of  the  partial  chemical  substances 
left  in  the  retina  after  a  process  in  which  a  colored  light 
has  partially  disintegrated  the  retinal  substance.  Contrast 
has  been  included  by  earlier  discussions  under  the  same  head 
as  after-images,  though  by  a  spread  of  stimulation  effects  con- 
trasts appear  where  there  are  no  immediate  after-images. 

The  student  will  see  at  once  that  many  of  these  statements 
are  hypothetical.  They  serve,  however,  to  gather  together  the 
facts,  and  they  give  a  genetic  account  of  primitive  as  well 
as  of  present  retinal  conditions.  The  theory  or  hypothesis 
should  be  clearly  distinguished  from  the  facts,  and  yet  it  is 
evident  that  the  facts  justify  us  in  attempting  to  explain  the 
relation  between  physical  processes  and  conscious  processes 
by  something  which  goes  on  in  the  retina.  In  order  to  keep 
the  facts  clearly  in  the  foreground,  it  may  be  well  to  re- 
turn to  a  general  summary  of  the  different  groups  of  facts 
discussed  in  this  section. 


SUMMARY  TABLES 
TABLE  A.    COLOR  BLINDNESS 


PHYSICAL  FACTS 


PHYSIOLOGICAL  PROCESSES 


SENSATIONS 


I.  Full     series     of 
simple  vibrations 


II.  Full     series     of 
simple  vibrations 


III.  Full     series     of 
simple  vibrations 


Highly  developed  retina 
with,  however,  a  limited 
number  of  modes  of  re- 
sponse to  external  light 

Partially  developed  retina 
with  a  number  of  possibili- 
ties of  response  to  exter- 
nal stimulation  which  is 
more  limited  than  in  the 
normal  retina 

Retina  so  little  developed 
as  to  have  only  one  mode 
of  response 


A  differentiated  group 
of«  sensation  quali- 
ties including  all 
colors 

Partial  color  blindness 


Total  color  blindness 


I , ,  I 


PSYCHOLOGY 


Pm 


<•«  of  simple 
\  -.orations 


II.  Two  simple 
waves,  closely  re- 
lated in  number 
<>f  vibrations,  en- 
tering the  eye 
together.  thus 
making  a  com- 
pound wave 

HI.  Two  simple 
waves,  very  dif- 
ferent in  number 
•  if  vibrations,  en- 
tering the  eye 
together,  thus 
making  a  com- 
pound wave 

IV.  I.arge  numbers 
of  waves  en- 
tering the  eye 
together,  thus 
making  a  most 
complex  wave 


Highly     developed 
with  a  limited  number  of 
distinct  modes  of  response 

•  I  response  which 
compromises  between  the 
two  responses  which 
would  have  resulted  had 
the  two  vibrations  acted 
separately 


Kctmal  response  which 
tends  to  take  the  simplest 
and  most  general  form  of 
retinal  behavior 


Simple  response  of  the  rudi- 
mentary type 


Umitcd    numbr 
sensation  qu.< 
constituting  a  senc» 
of  distinct  qualities 

••     color    sensa- 
somewhat  less 
saturated    than    in 
the  simple  series 


A  color  very  little 
saturated.  or  a 
single  purple  or 


Gray 


TABU    '       UTTER-IMAGES  AND  O 


PHYSICAL  FACT 

l'ir.  -IUUK-.ICAI.  Paocns 

•••Mill    •• 

I.  Strong  light  vibra- 
tion followed  by 
the  withdrawal  of 
physical  light 

Response  followed  by  a 
continued  action  of  the 
retina  and  a  final  reversal 
of  the  retinal  process  to 
restore  the  tissue  to  its 
normal  condition 

Color  sensation  con- 
tinuing after  exter- 
nal light  and  then 
changing  into  com- 
plementary color 
quality 

SENSATIONS  101 

B.    AUDITORY  SENSATIONS 

The  task  of  defining  sound  sensations  and  of  describing 
their  conditions  will  be  a  comparatively  simple  one  on  the 
basis  of  the  elaborate  study  already  made  of  visual  sensations. 

Physical  sound.  The  physical  stimulus  which  causes  the 
nervous  processes,  which,  in  turn,  condition  auditory  sensa- 
tions, consists  of  longitudinal  air  vibrations.  When  a  vibrat- 
ing body  strikes  the  air  particles  about  it  as  it  vibrates 
backward  and  forward,  the  air  particles  are  alternately  driven 
together  and  rebound  from  one  another.  Successive  waves 
of  condensation  and  rarefaction  result,  and  these  waves  are 
carried  forward  in  all  directions  until  they  strike  some  re- 
ceiving surface,  such  as  the  ear.  These  air  vibrations  can 
be  defined  in  the  same  terms  of  rate,  amplitude,  and  com- 
plexity as  were  used  for  the  light  vibrations  in  the  preceding 
section  (p.  77),  although  it  should  be  noted  that  the  form  of 
vibrations  is  different  in  the  two  cases. 

Pitch,  or  tonal  quality.  With  regard  to  the  relation 
between  sensation  and  external  sound  vibration,  it  is  to 
be  said,  first,  that  when  the  objective  waves  are  regular, 
they  give  rise  to  experiences  of  tone ;  when  the  vibrations 
are  irregular,  the  resulting  sensation  is  one  of  noise.  The 
rates  of  the  regular  vibrations  which  are  recognized  as  tones 
are  directly  related  to  differences  of  pitch.  Middle  C  on  the 
piano  scale  has  a  rate  of  vibration  of  two  hundred  and  fifty- 
six  double  vibrations  per  second.  Toward  the  bass  end  of 
the  scale  the  vibrations  decrease  in  rapidity,  while  toward 
the  treble  they  increase.  The  lowest  rate  which  is  ordinarily 
heard  by  the  normal  ear  is  about  thirty-two  vibrations  per 
second,  although  rates  of  sixteen,  or  even  ten,  per  second 
have  been  described  by  some  observers  as  audible.  At  the 
upper  end  of  the  scale  one  can  hear  vibrations  of  thirty 
thousand  to  forty  thousand  per  second.  Sounds  produced 
by  insects  are  of  this  order. 


102 

Intensity,  or  loudness.    In;  tone  varies  according 

as  the  amplitude  of  vibration  of  the  single  air  particles  is 
great  or  small. 

Complexity  of  a  regular  type  the  source  of  differences  in 
timbre.  Ordinary  sensations  of  tone  are  produced  by  com- 
plex waves.  If  two  or  more  forms  of  vibration  arc  transmitted 
to  a  given  particle  of  air  at  the  same  moment,  the  particle 
will  move  in  a  path  which  is  the  resultant  of  all  of  the  dif- 
ferent paths  through  which  it  would  have  moved  ha<! 
various  impulses  of  vibration  acted  upon  it  success! 
When  one  compares  a  given  tone  from  the  piano  with  the 
tone  of  the  same  pitch  from  a  violin,  he  will  recognize  that 
the  characteristics  of  the  tones  are  different,  though  they 
are  of  the  same  pitch.  The  violin  string  vibrates  not  only 
as  a  whole  but  also  in  certain  sections,  and  the  piano  wire 
vibrates  as  a  whole  and  at  the  same  time  in  sections.  The 
rates  of  vibration  of  the  string  and  wire  as  \\  holes  may  be 
exactly  the  same.  The  sections  in  the  two  cases  and  the 
rates  of  their  vibration  will  nearly  always  be  different.  The 
result  is  that  any  particle  of  air  set  in  motion  by  either 
piano  wire  or  violin  string  will  have  its  main  path  <i 
mined  by  the  vibration  of  the  whole  wire  or  string,  while 
the  minor  details  of  vibration  will  be  determined  by  the 
vibrations  of  the  sections  of  the  wire  or  string.  The  phase 
of  tonal  quality  thus  determined  by  the  complex  of  minor 
vibrations  is  known  as  timbre.  The  main,  or  fundamental, 
tone  is  modified  by  the  minor  higher  tones,  or  overtones  as 
they  are  called.  Tones  of  the  same  pitch  derived  from  vari- 
ous instruments  have  various  timbres,  just  in  so  far  as  they 
have  different  overtones. 

Noise  due  to  irregular  vibrations.  The  experience  of 
noise  is  dependent  upon  a  form  of  vibration  which  is  so 
complex  as  to  be  highly  irregular.  A  vague  regularity  ap- 
pears in  most  noises.  We  speak,  accordingly,  of  certain 
noises  as  low  and  rumbling,  and  of  others  as  high  and  shrill, 


SENSATIONS  103 

but  for  the  most  part  the  tendency  toward  regularity  of 
vibrations  gives  way  in  noises  to  a  confusion  of  irregular 
oscillations  in  the  air  particles. 

Evolution  of  the  ear.  Turning  from  the  physical  stimulus 
to  the  auditory  organ,  we  find  here,  as  in  the  case  of  the 
eye,  that  by  a  long  process  of  evolution  there  has  been  pro- 
duced a  sensory  organ  which  has  a  variety  of  accessory  parts 
and  a  delicate  sensory  surface,  which  latter  transforms  the 
air  vibrations  into  nervous  processes.  The  most  primitive 
ear,  such  as  is  found  in  the  ccelenterates,  consists  in  a  sack- 
shaped  opening  in  the  side  of  the  body.  This  sack-shaped 
depression,  or  vesicle,  contains  hard  calcareous  particles,  and 
is  lined  by  sensitive  cells  which  are  similar  in  their  general 
appearance  to  the  cells  in  the  primitive  eye.  The  whole 
organ  can  be  easily  explained  by  comparing  it  to  a  child's 
ordinary  rattle-box.  If  the  animal  is  shaken,  or  if  any 
sound  vibrations  strike  against  the  wall  of  the  vesicle,  the 
calcareous  particles,  or  otoliths  as  they  are  called,  are  set 
in  motion  and  tend  to  strike  against  the  sensitive  cells.  The 
result  is  that  the  cells  will  be  stimulated  by  each  movement 
of  the  animal's  body  or  by  the  vibrations  which  enter  the 
vesicle.  As  the  ear  develops  through  the  animal  series 
there  appear  a  number  of  accessory  organs  which  serve  to 
facilitate  the  reception  of  vibrations,  and  there  comes  to  be 
a  division  between  the  two  original  functions  of  the  ear ; 
namely,  that  of  sensory  response  to  the  movements  of 
the  body  as  a  whole,  and  that  of  response  to  vibrations 
from  the  water  or  air. 

The  human  ear,  pinna,  and  meatus.  After  this  brief 
reference  to  the  primitive  ear  we  may  turn  immediately  to 
a  description  of  the  human  ear.  The  outer  cartilaginous 
organ,  known  as  the  pinna,  has  in  man  very  little  function. 
It  serves  in  a  rudimentary  way  to  concentrate  the  sound 
waves  and  direct  them  toward  the  inner  ear.  The  long 
funnel-shaped  pinna  of  a  horse's  ear  serves  a  function  which 


104 


PSYCHOLOGY 


has  been  lost  in  the  process  of  evolution.    By  moving  its 
ear  the  horse  collects  sounds  from  different  directions,  and 
becomes  very  acutely  s<  1  and  at  the 

same  time  recogni/es  the  direction  from  which  the  sound 
comes.    Hut  the  horse  loses  fine  qualitative  shades  of  sound 


ET 

FIG.  28.    Diagrammatic  section  showing  the  structure  of  the  ear 

P,  external  pinna ;  EAf,  external  meatus ;  T,  tympanic  membrane ;  /,  internal 
meatus,  or  tympanic  cavity.  Extending  from  the  tympanic  membrane  to  the  inner 
ear  there  are  three  bones  constituting  the  chain  of  ossicles:  malleus,  incus,  and 
stapes.  ET,  Eustachian  tube,  passing  from  the  internal  meatus  to  the  cavity  of 
the  throat:  SC,  one  of  the  three  semicircular  canals:  A\,  the  auditory  nerve, 
which  divides  into  four  pans  as  indicated  in  the  figure,  one  branch  connecting  with 
the  semicircular  canals,  two  with  the  parts  of  the  vestibule,  and  the  fourth  with  the 
core  of  the  cochlea,  C.  The  canals  of  the  cochlea  are  indicated  in  general  outline : 
for  details  see  Fig.  30.  The  vestibule  is  the  general  region  lying  between  the  canals 
and  the  cochlea.  (Modified  from  Czermak) 

because  the  funnel  modifies  in  some  measure  the  form  of 
the  air  vibrations.  The  human  ear  has  so  evolved  that  it 
interferes  little  with  quality.  This  shows  that  the  sense  of 
hearing  in  man  is  not  a  locating  sense  but  a  sense  devoted 
to  the  finest  discriminations  in  quality.  The  evolution  of  the 
ear  is  undoubtedly  related  to  the  evolution  of  speech. 


SENSATIONS  105 

The  cylindrical  canal  which  connects  the  surface  of  the 
body  with  the  inner  cavities  of  the  ear  is  known  as  the  ex- 
ternal meatus.  This  canal  is  liberally  supplied  with  protective 
bristles,  and  with  secretory  glands  which  tend  to  protect  the 
ear  from  all  foreign  particles,  and  it  is  curved  in  shape  so 
that  nothing  but  very  small,  slender  objects  can  penetrate 
to  the  inner  parts  of  the  ear. 

Nature  has  a  relatively  easy  problem  of  protection  of  deli- 
cate organs  in  the  case  of  the  ear  because  air  vibrations  can 
be  conducted  along  a  narrow  passage.  In  the  case  of  the 
eye,  the  organ  must  lie  exposed  on  the  surface  of  the  body. 
Nature  has  put  a  ring  of  bony  structures  around  the  eye, 
but  the  protection  of  the  ear  is  much  more  complete. 

The  tympanic  membrane.  The  inner  end  of  the  external 
meatus  is  closed  by  means  of  a  circular  membrane,  known 
as  the  tympanic  membrane.  This  tympanic  membrane  is  a 
composite  membrane  made  up  of  circular  and  radial  fibers. 
It  is  slightly  depressed  in  the  middle  so  as  to  be  somewhat 
funnel-shaped  and  is  loaded  by  being  connected  on  its  inner 
surface  with  a  small  bone,  known  because  of  its  shape  as 
the  malleus,  or  hammer.  The  malleus  is  controlled  by  a 
small  muscle,  known  as  the  tensor  tympani.  When  this 
muscle  is  contracted  it  draws  the  malleus  inward,  and  with 
the  malleus  the  tympanic  membrane,  thus  increasing  the 
tension  of  the  membrane  and  emphasizing  its  funnel-shaped 
form.  The  adjustments  of  the  tympanic  membrane,  as  well 
as  its  shape,  are  of  importance  in  giving  the  ear  the  largest 
possible  range  of  ability  to  receive  sound  vibrations.  No 
artificially  constructed  diaphragm,  such  as  those  employed 
in  the  phonograph  or  telephone,  is  capable  of  as  wide  a 
range  of  response  to  tones  as  is  the  adjustable,  complex 
diaphragm  in  the  ear. 

Air  chamber  on  inner  side  of  the  tympanic  membrane. 
In  the  functioning  of  the  tympanic  membrane  a  difficult 
mechanical  problem  arises,  because  the  air  pressure  in  the 


106  P8Y(  I!-  -i  • 

nal  world  is  constantly  undergoing  changes.  With  « 
change  in  the  Ixi:  ...uld  lx- 

fcrence  with  the  ait  ion  of  the  tympanic  membrane,  if  the 
spaces  behind  this  membrane  were  air-tight.  Nature  has, 
accordingly,  provided  on  the  inner  side  of  the  tympanic 
membrane  an  air  chamber  communicating  with  the  atmos- 
phere so  that  any  change  in  atmospheric  pressure  will  result 
in  an  equal  change  in  the  pressure  on  both  sides  of  the 
tympanic  membrane.  This  air  chamber  on  the  inner  side 
of  the  tympanic  membrane  is  known  as  the  internal  mcatus, 
or  tympanic  cavity.  It  consists  of  an  irregular  cavity  in  the 
bone,  which  is  in  communication  with  the  throat  by  means 
of  a  small  canal,  known  as  the  Kustachian  tube.  The  wall 
of  the  Kustachian  tube  is  flexible,  so  that  it  collapses  except 
when  a  current  of  air  is  forced  through  it  by  a  chan^, 
pressure,  either  in  the  internal  meatus  or  in  the  external 
atmosphere.  For  this  reason,  the  ordinary  voice  vibrations 
which  arise  in  the  throat  are  not  communicated  directly  to 
the  internal  meatus. 

Chain  of  ossicles.  Since  there  is  an  air  chamber  on  the 
inner  side  of  the  tympanic  membrane,  there  must  be  some 
means  of  carrying  the  sound  vibrations  received  on  the  tym- 
panic membrane  across  this  cavity  to  the  inner  ear.  '1  he- 
means  for  transmitting  the  vibrations  received  by  the  tym- 
panic membrane  consist  of  a  chain  of  three  small  r> 
known  as  the  chain  of  ossicles.  The  first  of  these  ossicles 
has  been  mentioned ;  it  is  the  malleus,  or  hammer,  which 
is  attached  by  its  long  arm  to  the  middle  of  the  tympanic 
membrane.  The  head  of  the  malleus  articulates  with  the 
surface  of  the  second  bone,  which  is  known  as  the  incus 
because  of  its  anvil-shaped  appearance.  One  of  the  branches 
of  the  incus  articulates  in  turn  with  the  third  bone,  known 
as  the  stapes,  or  stirrup.  Any  vibration  received  by  the  tym- 
panic membrane  is  thus  communicated  to  the  stirrup.  The 
stirrup  fits  into  an  oval  opening,  known  as  the  fenestra 


SENSATIONS  107 

ovalis,  which  leads  into  the  inner  ear.  The  stapes  is  con- 
nected with  the  walls  of  this  fenestra  ovalis  by  means  of 
a  membrane,  so  that  it  constitutes  a  tight-fitting  piston 
which  can  move  backward  and  forward  in  the  fenestra 
ovalis.  Beyond  the  oval  window  the  inner  ear  is  filled  in 
all  of  its  parts  with  lymphatic  fluid.  Sound  vibrations, 
which  are  originally  vibrations  of  air  particles,  are  thus 
transformed  by  the  mechanism  described  into  vibrations  in 
the  lymphatic  fluid  which  fills  the  inner  ear. 

The  inner  ear.  The  inner  ear  is  divided  into  three  prin- 
cipal parts  :  vestibule,  semicircular  canals,  and  cochlea.  The 
vestibule  is  an  irregular  ovoid  cavity  about  one  fifth  of  an 
inch  in  diameter,  which  opens  on  the  one  side  into  the  snail- 
shell-shaped  cavity,  known  as  the  cochlea,  and  on  the  other 
into  a  system  of  slender  canals,  known  as  the  semicircular 
canals.  The  vestibule  itself  is  divided  into  two  parts,  known 
as  the  saccule  and  utricle. 

The  semicircular  canals.  The  semicircular  canals  are  not 
organs  of  hearing.  They  are  organs  which  have  taken  up 
in  the  process  of  evolution  that  function  of  the  primitive 
ear  which  was  concerned  with  response  to  the  grosser  move- 
ments of  the  animal's  whole  body.  There  are  three  of  these 
canals,  and  they  lie  in  such  positions  that  each  one  occupies 
a  different  plane  in  space.  Any  change  in  the  position  of 
the  head,  or  of  the  body  as  a  whole,  will  cause  a  redistri- 
bution of  the  pressure  within  the  system  of  canals,  and  this 
change  in  pressure  affects  the  nerve  cells  which  are  distrib- 
uted in  the  wall  of  the  enlarged  portion,  or  ampulla,  of 
each  canal.  The  whole  system  of  canals  serves  as  an  organ 
of  equilibration.  The  sensory  stimulations  which  come  from 
this  organ  do  not  give  rise  in  developed  human  beings  to 
clearly  differentiated  sensations.  The  result  is  that  the  ordi- 
nary observer  does  not  know  that  he  has  a  special  sense 
organ  of  equilibration.  The  stimulations  are  for  the  most 
part  taken  up  by  the  lower  centers  of -the  nervous  system, 


108 


PSYCHOLOGY 


FIG.  29.    Diagrammatic 

section  of  the  sensory 

cells  in  the  vestibule 

The  receiving  cells  are 
situated  on  the  surface,  as 
represented  by  5.  These 
receiving  cells  are  sur- 
rounded by  supporting 
cells,  as  indicated  at  A. 
The  nerve  fiber  is  distrib- 
uted among  the  receiving 
cells.  The  true  sensory  ceU 
at  G  is  in  the  ganglion, 
rather  than  directly  at  the 
surface.  This  sensory  cell 
sends  its  second  fiber  in- 
ward to  the  central  nervous 
system,  represented  by  C. 
(After  Hcrrick) 


\\|KTC  they  arc  distributed  to  the  mun- 
cles  \\hii  h  keep  the  body  erect ;  they 
probably  never  reach  the  higher  regions 
except  in  company  with  a  great  mass 
of  other  MS,  such  as  touch  sen- 

us  from  the  soles  of  the  feet  and 
muscle  sensations  from  the  neck  and 
trunk.  When  they  become  excessively 
intense  they  give  rise  to  the  experience 
of  dizziness.  In  some  cases  the  indirect 
effects  of  their  action  come  into  con- 
sciousness. When  the  reflex  muscular 
adjustment  carried  out  by  the  lower 
centers  is  unusual,  as  when  one  de- 
scends suddenly  in  an  elevator,  the 
muscular  reactions,  rather  than  the  pri- 
mary sensory  stimulation,  give  rise  to 
a  clearly  recognizable  experience.  The 
observer  feels  an  unusual  tension  in 
his  abdominal  muscles  or  muscles  of 
some  other  part  of  the  body. 

The  cochlea  and  sensory  areas  in  the 
vestibule.  Turning  from  the  semicir- 
cular canals  to  the  other -canal  leading 
out  of  the  vestibule,  namely  the  coch- 
lea, we  find  here  the  organs  which 
are  concerned  in  the  reception  of  tonal 
stimulations.  It  is  not  clearly  known 
whether  noise  stimulations  are  received 
in  the  cochlea  or  not.  The  probabili- 
ties are  that  noise  stimulations  affect 
certain  cells  constituting  sensory  areas 
in  the  wall  of  the  vestibule.  At  all 
events,  it  is  true  that  there  are  cells 
situated  in  the  wall  of  the  vestibule 


SENSATIONS 


109 


which  seem  to  be  suited  to  the  reception  of  simple  stimuli 
(see  Fig.  29).  The  vestibule  is  the  direct  descendant  of 
the  primitive  vesicle.  This  fact  would  seem  to  argue  in 
favor  of  the  view  that  noise  stimulations,  which  are  undif- 
ferentiated  and  probably  earlier  than  tonal  stimulations, 
affect  these  cells  in  the  vestibule.  Whatever  may  be  true 
of  noise,  it  is  certain  that  the  tonal 
excitations  are  received  through  the 
complicated  structures  which  have 
been  developed,  and  appear  in  the 
cochlea.  The  cochlea  is  a  highly 
developed  organ,  richly  supplied 
with  cells  and  fibers  for  the  recep- 
tion of  a  great  number  of  different 
stimulations.  It  consists  of  a  double 
spiral  canal,  which  winds  around 
two  and  a  half  times.  The  winding 
of  this  canal  is  merely  an  anatomi- 
cal device  for  compressing  the 
whole  organ  into  as  small  a  space 
as  possible.  The  canal,  which  is 
cylindrical  in  form,  is  divided  into 
three  parts,  —  the  scala  vestibuli, 
the  scala  tympani,  and  the  ductus 
cochlearis.  This  division  can  best 
be  seen  by  making  a  section  across 
the  cylindrical  passage.  Fig.  30 
shows  such  a  section  with  the  division.  The  scala  tympani 
is  partially  separated  from  the  rest  of  the  cochlea  by  a  bony 
shelf  which  extends  for  some  distance  into  the  canal.  The 
division  is  completed  by  an  important  membrane.  This 
membrane,  known  as  the  basilar  membrane,  is  made  up  of 
a  series  of  fibers  which  differ  in  length  as  the  membrane 
passes  from  the  lower  to  the  upper  extremity  of  the  canal. 
At  its  lower  extremity  the  fibers  are  short,  and  at  the 


FIG.  30.  The  structure  in  the 
cochlea  as  seen  when  a  trans- 
verse section  is  made  across 
the  canal 

The  parts  are  clearly  marked  in 
the  figure.  Special  attention 
should  be  given  to  the  basilar 
membrane  and  the  organ  of 
Cord  situated  upon  it.  The 
nerve  fibers  are  distributed 
among  the  cells  of  the  organ 
of  Cord  from  the  ganglion  in' 
a  manner  similar  to  that  repre- 
sented for  the  vestibular  cells  in 
Fig.  29.  (After  Herrick) 


I  io  P8V<  HOLOGY 

upper  end  of  the  canal  they  are  about  mes  as  long. 

Helmholt/.    the   :  :>t,  called   at: 

the  striking   similarity  Ix-tween   the-  structure  of  the  basilar 
membrane  and  tl;  i  of  strings  of  a  musical  instrunu-nt 

capable  of  pvin-  i  tones.    He  also  ad- 

d  the  h\|X'!.  a  the  fibers  of  the  membrane  are 

so  related   to   external    tones   th.it  n   fiber  is  s< 

tion  by  each  particular  rate  of  vibration.     It  is  a  well- 
known   principle  of   phyv  Mint  any  filx •: 
will  vibrate  sympathetically  with  a  tone  which  '. 
rate  as  it  would  assume  itself,  if  it  were  set  in  vibration  In- 
some  other  cause.    This  principle  is  known  as  the  principle 
of  sympathetic  resonance.    The  basilar  membrane  is  so  situ- 
ated that  the  vibrations  which  enter  the  inner  ear  thr< 
the  t                -valis  reach  it  by  passing  up  the  scala  vestibuli 
and   the  ductus  cochlearis.     The  scala  tympani  is  a  canal 
which  carries  back  the  vibrations  after  they  1  <.\  on 
the  basilar  membrane.    It  is  connected  at  the  upper  end  of 
the  cochlea  with  the  scala  vestibuli  and  serves  to  conduct 
away  the  vibrations  rather  than  allow  them  to  be  reflected 
back  into  the  vestibule ;  for  its  lower  end  does  not  open  into 
the  vestibule,  but  communicates  through  an  opening,  kr 
as   the   fenestra    rotunda,   with   the   internal    meatus.    The 
basilar  membrane  thus  stands  in  the  direct  path  of  the  vibra- 
tions, and  it  is,   probably,  the  organ  which   takes  up  the 
vibrations  through  sympathetic  resonance  and  makes  them 
effective  in  exciting  the  sensory  cells. 

Sensory  cells  in  the  cochlea.  A  system  of  recei 
cells,  analogous  to  the  rods  and  cones  in  the  eye,  is  placed 
directly  on  the  basilar  membrane.  At  any  given  point  they 
form  an  arch  extending  across  the  membrane,  and,  there- 
fore, are  capable  of  taking  up  any  vibration  which  sets  the 
fibers  of  the  membrane  in  motion.  The  arch  of  cells  is 
shown  in  Fig.  30  and  is  known,  from  the  physiologist  who 
first  described  it,  as  the  organ  of  Corti.  Among  the  cells 


SENSATIONS  TIT 

that  constitute  the  organ  of  Corti  there  are  distributed  nerve 
fibers  which  come  from  auditory  ganglion  or  true  sensory 
nerve  cells  situated  in  a  cavity  in  the  bony  core  of  the  coch- 
lea. Whenever  the  cells  of  Corti  are  set  in  vibration,  they 
excite  the  fibers.  The  external  air  wave  is  thus  transformed 
in  the  organ  of  Corti  into  a  nervous  process. 

Contrast  between  auditory  and  visual  processes.  It  is  to 
be  noted  that  the  transformation  is  of  a  distinctly  different 
type  from  that  which  takes  place  in  the  eye.  In  the  eye 
the  physical  stimulus  produces  a  chemical  activity  in  the 
rods  and  cones.  In  the  case  of  the  ear  the  stimulus  con- 
tinues in  the  form  of  vibrations  until  it  produces  its  final 
effect  upon  the  nerve  cells.  There  is  a  less  fundamental 
change  in  the  character  of  the  stimulus  as  we  pass  from  the 
external  world  to  the  nervous  process  in  the  ear  than  there 
is  in  the  corresponding  transition  in  the  eye.  This  fact 
shows  itself  most  clearly  when  we  come  to  deal  with  com- 
pound sound  vibrations.  It  makes  no  difference  how  many 
tones  are  sounded  before  the  tympanic  membrane,  the  com- 
plex vibration  will  be  faithfully  transmitted  by  the  chain  of 
ossicles  and  the  other  accessory  organs  and  will,  at  all 
points  in  its  transmission,  be  a  detailed  reproduction  of  the 
total  complex  of  sound  impulses  which  gave  rise  to  it. 
Furthermore,  it  is  shown  by  an  examination  of  sensory 
experience  that  there  must  be  a  separate  sensory  process 
for  each  component  of  the  tonal  complex.  If  an  observer 
listens  to  a  tonal  complex,  such  as  an  orchestra,  the  sensory 
excitations  do  not  fuse  as  do  the  chemical  processes  result- 
ing from  a  number  of  colors  which  act  upon  the  retina 
together.  Each  tone  in  the  complex  retains  its  independent 
value  for  experience.  It  was  this  fact,  together  with  the 
form  of  the  basilar  membrane,  which  led  Helmholtz  to  sug- 
gest his  hypothesis.  Whether  that  particular  hypothesis  is 
true  or  not,  we  may  confidently  assert  that  the  different 
parts  of  the  organ  of  Corti  are  specialized  in  some  way  or 


i->y<  ii<>i.< 

.  so  that  each  rate  of  external  vibration,  whcth- 
reaches  the  cochlea  alone  or  as  part  of  a  complex  of  vibra- 
tions, a  particular  part  of  the  sensory  organ  and  so 
gives  rise  to  a  distinct  sensory  process.  The  car  is  thus 
seen  to  be  an  analyzing  sense  capable  of  carrying  to  con- 
sciousness at  one  and  the  same  moment  a  vast  complex  of 
sound.  There  is  nothing  in  auditor)'  sensation  to  corre- 
spond to  white  amon£  the  retinal  sensations  unless  it  be 
mere  noise.  Hut  even  here  there  is  a  fundamental  differ- 
ence, because  the  various  elements  of  a  noise  can  be  heard 
separately,  especially  if  some  of  the  elements  have  a  tonal 
character.  For  example,  the  ear  has  no  difficulty  in  hearing 
at  the  same  time  the  noise  produced  by  a  train  and  the 
sounds  produced  by  the  human  voice. 

Beats,  difference  tones.  There  are  certain  special  cases  of 
complex  air  vibration  which  should  be  mentioned  in  this 
discussion  of  sensations.  If  two  closely  related  tones  are 
sounded  together,  they  will  reenforce  the  vibration  of  the 
air  particles  which  they  affect  so  long  as  their  phases  are 
alike,  but  the  moment  their  phases  come  into  such  a  relation 
that  one  tends,  to  set  the  air  particle  vibrating  in  a  j: 
direction  and  the  other  tends  to  set  the  same  air  particle 
vibrating  in  the  opposite  direction,  they  will  partially  counter- 
act each  other  in  such  a  way  as  to  keep  the  air  particle  for 
a  moment  in  a  state  of  equilibrium.  Fig.  31  reprev 
in  the  form  of  a  water  wave,  two  vibrations  which  at  the 
outset  cooperate  in  giving  a  larger  wave.  As  one  lags 
slightly  behind  the  other,  they  come  later  to  counteract  each 
other  in  such  a  way  that  no  vibration  takes  place,  as  shown 
at  J/.  The  result  of  such  a  combination  of  tones,  which  is 
a  purely  physical  affair,  is  that  the  observer  receives  not 
only  the  two  primary  vibrations  but  also  a  series  of  rapid 
variations  in  intensity,  which  succession  of  intensities  fuses 
into  a  new  impression.  The  observer  therefore  hears,  in 
addition  to  the  two  fundamental  tones,  an  alternate  rising 


SENSATIONS  1 1 3 

and  falling  in  the  loudness  of  the  sound,  which  fluctuation 
gives  rise  to  experiences  known  as  beats.  If  these  beats 
are  slow  enough  to  be  distinguishable,  they  will  be  recog- 
nized as  quite  distinct  from  the  tones.  If,  on  the  other 
hand,  they  become  too  numerous  to  be  separately  apprehended, 
they  may  sometimes  be  heard  as  an  additional  tone,  when 
they  are  designated  as  difference  tones.  For  example,  if 
two  tones,  c  and  g,  are  sounded  together,  these  tones  having 
vibrations  at  the  rates  of  256  and  384  vibrations  per  second, 
the  result  will  be  a  complex  in  which  both  c  and  g  will  be  dis- 
tinctly heard ;  but  there  will  also  be  heard  a  third  tone,  the 


FIG.  31.    Diagram  to  represent  the  formation  of  beats 

The  two  curves  represented  by  the  light  line  and  the  dotted  line  begin  together, 
showing  the  same  phase  at  the  same  time.  The  wave  motion  represented  by  the 
dotted  line  is  somewhat  more  rapid  than  that  represented  by  the  full  line  ;  conse- 
quently, the  relation  of  the  two  waves  changes  so  that  in  the  region  M  the  two  are 
in  opposite  phases.  The  heavy  line  indicates  the  results  of  the  combination  of  the 
two  waves,  a,  b,  c,  d,  e,  f,  g,  h  indicate  the  strong  curve  which  results  from  the 
reenforcing  influence  of  the  two  wave  motions.  M  indicates  the  result  of  the  coun- 
teracting influence  of  the  two.  (After  Ebbinghaus) 

number  of  vibrations  of  which  equals  the  difference  between 
the  number  of  vibrations  of  c  and  g.  That  is,  the  difference 
tone -in  this  case  will  be  a  tone  of  128  vibrations  per  second. 
Summation  tones.  Again,  there  are  complexities  in  the 
tonal  experience  such  that  often  tones  are  heard  in  a  tonal 
complex  which,  in  number  of  vibrations,  are  equal  to  the 
sum  of  the  two  fundamentals.  Such  tones  are  known  as 
summation  tones.  They  do  not  seem  to  be  purely  physical 
facts,  explicable  in  terms  of  the  physical  effect  upon  the  air 
particles,  for  they  cannot,  in  all  cases,  be  reenforced  by  physi- 
cal resonators  (the  apparatus  which  is  commonly  used  in  the 
detection  of  single  tones  in  tonal  complexes).  Summation 


ii4  SVHOI.OGY 

tones  seem  rather  to  be  due  to  certain  physiological  proc- 
esses, perhaps  to  in:  s  of  the  vibration  processes 
in  the  basilar  membrane  or  to  secondary  .  the 
bony  walls  of  the  cochlea.  In  ordinary  experiences  d. 
ence  tones  and  summation  tones  play  no  important  part, 
but  the  result  of  these  tones  upon  harmonies  and  discords 
in  music  is  a  matter  of  some  importance  and  one  which 
has  K-en  made  the  subject  of  careful  examination. 

Harmony  not  a  matter  of  sensation.  By  these  discuss 
of  tonal  sensations  and  their  combinations  we  have  been 
led  to  the  point  where  it  would  be  appropriate  to  take  up 
the  matter  of  harmony.  Certain  tones,  when  sounded  to- 
gether, give  the  observer  an  experience  which  is  not  n:< 
that  of  tones  sounding  together,  but  is  also  an  experience 
of  the  smooth  fitting  together  of  these  tones,  while  other 
combinations  give  the  observer  a  distinct  impression  of  jar 
or  discord.  The  effort  has  often  been  made  to  explain 
harmony  and  discord  as  due  to  beats  and  like  facts ;  that  is, 
to  certain  simple  processes  in  the  organ  of  sense.  \Ve  shall 
dismiss  the  matter  in  a  somewhat  dogmatic  fashion  by  say- 
ing that  such  explanations  of  harmony,  by  processes  of  a 
purely  sensor)'  type,  are  not  satisfactory.  There  is  probably 
a  close  relation  between  recognition  of  harmony  and  motor 
processes,  such  as  those  of  the  vocal  cords  and  those  of  the 
inner  organs  which,  as  will  be  seen  later,  are  aroused  during 
emotional  experiences. 

Absence  of  after-images  in  auditory  sensations.  Before 
closing  the  discussion  of  tonal  sensations  it  should  be  noted 
that  the  nature  of  the  auditory  sensory  process  is  such  that 
contrast  and  after-effects  do  not  appear  to  any  great  extent 
in  tonal  or  noise  sensations.  The  process  in  the  nerve  cells 
terminates  as  soon  as  the  external  vibration  ceases.  This 
characteristic  of  sound  sensations  explains  why  it  is  that 
these  sensations  can  be  used  in  musical  compositions.  A 
succession  of  colors,  given  in  anything  like  the  same 


SENSATIONS 


relation  as  a  succession  of  tones  in  music,  would  produce  a 
hazy  blur  of  after-effects. 

Tone  deafness.  Cases  of  tonal  deafness,  or  inability  to 
receive  certain  tones,  have  been  described.  A  person  capable 
of  the  usual  tonal  discriminations  in  many  parts  of  the 
scale  is  quite  unable  to  distinguish  tones  in  a  certain  limited 
part  of  the  scale  or  at  one  end  of  the  scale.  This  deficiency 
is  undoubtedly  related  to  some  lack  of  normal  functioning 
in  a  given  region  of  the  basilar  membrane,  or  organ  of 
Corti.  In  old  age  a  person  may  also  show  increasing 
deficiency  in  ability  to  hear  very  high  tones. 

SUMMARY 

Without  attempting  to  summarize  all  that  has  been  said  in  the 
discussions  of  tonal  sensations,  it  may  be  advantageous  to  prepare 
a  table  which  may  be  used  for  the  purposes  of  comparison  with 
the  earlier  tables  referring  to  visual  sensations. 


PHYSICAL  VIBRATION 

PHYSIOLOGICAL  PROCESS 

SENSATION 

Series  of  air  vibrations 

No  physiological  excitation 

No  sensation 

below  10  per  second 

Continuous  series  of 

A  very  large  number  of  dif- 

Large number  of  sen- 

changes in  rate  of 

ferent    processes    in    the 

sations    ranging  in 

air   vibration    from 

basilar      membrane      and 

series  from  lowest 

32    per   second    to 

organ  of  Corti  ;  the  num- 

to highest  pitch 

30,000     or     40,000 

ber   being,    however,  less 

% 

per  second 

than  the  number  of  phys- 

ical processes 

Same  as  above 

More  limited  number  of  phys- 

Partial tone  deafness 

iological  processes  because 

of  incomplete  development 

of  the  organ  of  Corti 

Complex  vibrations 

Separate  physiological  proc- 

Recognizable      com- 

ess  for   each    component 

plex   of   tonal  sen- 

of the  complex 

sations 

Complex  vibrations 

Interference  of  vibration  in 

Summation  tones  not 

the  physiological  organs 

paralleled  by  objec- 

tive vibrations 

n6 


iioLOGY 


C.   SEN 

Taste  and  smell  differentiations  of  a  primitive  chemical 
sense.    Sensations  of  taste  and  smell  may  be  con  sic 
together.     Indeed,   in   the   primitive   forms  of  animal   life, 
taste  and  smell  constitute  a  single  chemical  sense.    Of  the 
two  the  -  im-11  is  distinctly  later  in  its  development, 

appearing  as  an  important  sep;t  with  t!  .ince 

of  the  air-breathing  animals. 

Position  of  olfactory  organ  in 
the  nasal  cavity.  It  is  unneces- 
sary here  for  us  to  consic: 
any  great  length  the  nasal  cavities 
in  which  the  olfactory  cells  are 
situated.  These  cavities  are  not 
true  accessories  to  the  organ  of 
sense,  as  were  the  cavities  in  the 
ear.  The  organ  of  sense  is  rather 
accessory  to  the  general  organ  of 
respiration.  The  position  of  the 
senson  cells  is  such  that  they  are 
not  in  the  direct  path  of  the  great 
volume  of  air  which  is  used  in 
the  process  of  respiration.  Fig.  32 
shows  the  area  within  the  nasal 

cavity  which  is  covered  by  olfactory  cells.  The  arrow  A  in 
the  figure  indicates  the  path  of  the  air  current  in  ordinary 
respiration.  It  will  be  noted  that  in  such  ordinary  respira- 
tion very  little  of  the  air  is  carried  up  into  the  upper  part 
of  the  nasal  cavity  and  thus  brought  into  contact  with  the 
sensitive  cells.  If  for  any  reason  it  is  desirable  that  the 
sensitive  cells  should  receive  the  full  current  of  air  which 
enters  the  nose,  the  animal  must  sniff  the  air  forcibly  into 
the  nasal  cavity,  in  which  case  it  will  follow  the  direction  of 
the  arrow  B  in  the  figure. 


Fie.  32.    The  inner  cavity  of 
the  nose      . 

The  arrow  A  indicates  the  path  of 
the  air  in  ordinary  respiration ;  It 
indicates  the  path  of  the  air  when 
the  animal  sniffs.  The  olfactory  re- 
gion is  indicated  by  the  black  area 
in  the  upper  pan  of  the  cavity 


SENSATIONS 


117 


Structure  and  function  of   the   olfactory  surface.     The 

olfactory  surface  itself  is  made  up  of  two  kinds  of  cells, 
as  shown  in  Figs.  33  and  34.  There  are,  first,  certain 
supporting  cells  which  line  the  nasal 
cavity  ;  and  second,  there  are  distributed 
among  the  supporting  cells  true  sensory 
cells,  from  which  fibers  pass  inward  to 
the  central  nervous  system.  The  nerve 
cells  in  this  organ  are  immediately  on  the 
surface,  in  such  a  position  that  particles 
brought  in  through  the  air  currents  come 
into  direct  contact  with  the  cell  body 
proper.  This  direct  exposure  of  the  nerve 
cells  to  stimulation  is  undoubtedly  related 
to  the  fact  that  these  cells  are  very  easily 
fatigued.  It  is  a  well-recognized  fact 
that  an  odor  which  is  very  striking  at 
first  soon  grows  less  and  less  impressive, 
even  though  the  stimulus  may  continue 
in  its  original  intensity.  Furthermore, 
the  olfactory  cells  do  not  seem  to  be  very 
definitely  specialized,  and  there  are  no 
selective  organs  between  the  external 
stimulus  and  the  sensory  organs  which 
determine  the  effect  of  the  stimulus  on 
the  nervous  organs.  There  is,  accord- 
ingly, no  clearly  defined  limit  to  the 
number  and  variety  of  olfactory  sensa- 
tions. By  way  of  contrast  with  the  visual 
organ,  for  example,  there  is,  in  the  case 
of  the  olfactory  sense,  nothing  which  corresponds  to  the  rods 
or  cones  and  operates  to  reduce  all  external  stimulations  to 
a  limited  number  of  sensory  processes.  Consequently,  the 
number  of  olfactory  sensations  is  very  large,  and  the  effort 
to  classify  them  is  defeated  by  their  variety. 


FIG.  33.  Section  show- 
ing the  different  cells 
which  compose  the 
mucous  lining  of  the 
nose  in  the  olfactory 
region 

By  the  staining  process, 
the  special  sensory  cells 
are  clearly  distinguished 
from  the  other  cells  as 
black.  In  one  of  these 
cells  the  nerve  fiber  will 
be  seen  passing  directly 
out  of  the  cell  toward  the 
•  central  organ 


ilnLOGY 


Olfactory  stimuli.    With  regard  to  the  character  of  the 
uil  stimuli  which  affect  the  cells  of  the  olfactory  sur- 
face, our  knowledge  is  somewhat  limited.    Minute  particles 
probably  detach  themselves  from  external  objects  and  are 
carried  by  the  air  currents  during  inspiration  into  the  nasal 
v.   These  panicles,  or  effluvia,  produce  a  chemical  effect 
upon  the  olfactory  cells.     In  ^en<  eems  to  be  true 

^^  that    those  substances   which   are   most 

quently  brought  into  contact  with  the  olfai 
fc(;     \          surface  produce  the-  least  effect,  whereas  new 
m\    l\        anc*  un^am'''ar  substances  produce  a  strong 
m   jjl  1       effect.     The    relation    between    the    external 
•  Jl      V     effluvia  and  the  olfactory  processes  is  pro! 
I  ^||     j     the  outgrowth  of  the  long  evolutionary  proc- 
/\    ^11    J     ess,  in  which  the  sense  has  developed  ;i 
I     I  I          chief  function  the  ability  to  warn  animal 

the  presence  of  unfamiliar  substances  in  the 
atmosphere.  Noxious  gases  are,  from  the 
nature  of  the  case,  relatively  uncommon,  and 
the  olfactory  sense,  in  serving  to  warn  us  of 
their  presence,  not  only  sh  tdaptation 

to  the  stimuli  which  are  unusual  but  shows, 
also,  the  significance  of  the  whole  develoj)- 
ment  as  aimed  at  the  preservation  of  the 
organism. 

Smell  a  rudimentary  sense  in  man.  Ani- 
mals make  much  larger  use  of  the  sense  of  smell  than  do 
human  beings.  They  often  take  advantage  of  the  presence 
of  strange  effluvia  in  the  atmosphere  and  react  positively 
to  these  odors,  seeking  the  source  of  the  odor,  if  it  1 
them,  for  example,  to  food.  It  is  to  be  said  in  this  con- 
nection that  the  human  sense  of  smell  can  be  much  more 
highly  cultivated  than  is  commonly  the  case,  if  attention  is 
directed  to  these  sensations  in  early  life.  Such  attention  aids 
discrimination,  but  does  not  change  the  organ  itself. 


Fi<:.  34.  Olfac- 
tory cells  and 
supporting  cells 
(much  magni- 
fied) 

The  supporting 
cells  are  here 
shown  to  be  larger 
than  the  true 
sensory  cell  and 
somewhat  differ- 
ent in  form 


SENSATIONS 


119 


Taste  qualities  and  taste  organs  specialized.  Turning  from 
smell  to  taste,  we  notice  first  that  the  qualities  of  taste  sen- 
sation are  more  easily  reduced  to  a  classified  list.  The  quali- 
ties most  constantly  recurring  are  bitter,  sweet,  sour,  and 
saline.  If  we  add  to  the  list  al- 
kaline and  metallic,  which  may 
be  compounds,  it  is  possible  to 
classify  all  taste  experiences  as 
belonging  under  the  one  or  the 
other  of  the  six  classes,  or  as 
compounds  of  these.  This  re- 
duction of  all  tastes  to  a  few 
qualities  leads  one  to  look  for 
structures  in  the  organ  of  taste 
which  shall  explain  the  reduc- 
tion of  the  physical  manifold 
to  a  small  number  of  sensory 
qualities.  The  study  of  the 
organs  of  taste  shows  that  they 
are  specialized  structures,  prob- 
ably of  a  selective  character. 

Organs  of  taste.  The  taste 
organs  are  distributed  through- 
out the  mouth  and  throat.  They 
appear  in  greatest  abundance 
on  the  papillae  of  the  tongue. 
Fig.  35  shows  a  magnified  sec-  Liquids  may  pass  down  into  this  open. 

tion  through   the  Side  Of  One  Of     ing-   On  its  sides  are  taste  bulbs.  Their 

the  large  papillae.  At  certain 
points  in  the  walls  of  the  papilla 
there  can  be  distinguished  groups  of  cells  clustered  in  bulb- 
shaped  organs.  These  are  known  as  the  taste  bulbs.  Each 
bulb  is  made  up  of  a  number  of  cells  grouped  about  its  wall 
and  constituting  a  minute  pear-shaped  organ  (Fig.  36). 
Among  these  cells  in  the  bulb  are  distributed  tactual  nerve 


FIG.  35.    The  depression  between 

the   sides   of  two   papillae  on  the 

surface  of  the  tongue 


number  and  distribution  are  indicated 
in  the  figure 


I2O 


fibers  and  special  taste  fibers  (Fig.  37),  which  come  from 
nerve  cells  located  in  the  imn  iulla. 

The  cells  of  the  taste  bulb  arc  chemically  affected  by  certain 
fluids  which  act  upon  them,  and  the  chemical  processes  set 
up  within  the  peripheral  cells  arc  transmitted  first  to  the  nerve 
fibers,  and  through  these  to  tl.  .  and,  finally,  from 

to  the  central  nervous  sys- 
tem. Probably  not  all  the 
cells  in  the  taste  bulbs  act 
equally  in  receiving  taste 
stimulations.  Some  of  the 
cells  in  the  bulbs  seem  to 
be  specialized  for  the  taste 
function,  while  others  play 
the  part  of  supporting 
cells.  The  peripheral  or- 
gans are  not  true  n< 
cells,  as  were  the  rci 
ing  cells  in  the  olfat 
organs;  they  are  interme- 
diate between  the  sen 
fibers  and  the  outer  world. 
Their  function  is,  un- 
doubtedly, selective.  This 
accounts  for  the  more 
definite  and  independent 
character  of  the  taste  quali- 
ties as  compared  with  odors.  The  selective  character  of  the 
taste  cells  is  strikingly  shown  by  the  fact  that  not  all  taste 
bulbs  receive  with  equal  facility  the  various  taste  stimula- 
tions. Thus,  the  cells  in  the  back  part  of  the  tongue  are 
much  more  sensitive  to  stimulation  from  bitter  substances. 
Cells  in  the  front  part  of  the  tongue  respond  more  readily 
to  sweet  solutions.  On  the  sides  of  the  tongue  the  areas 


FIG.  36.    A   diagrammatic  section  of  a 

single  taste  bulb  showing  the  character 

of  the  different  cells 

The  cells  marked  n  arc  the  special  sensory 
cells.  The  cells  rr&rked  u  are  supporting 
cells.  It  will  be  noticed  that  the  cells  consti- 
tuting the  bulb  are  somewhat  larger  than  those 
which  form  the  general  surrounding  tissue 


SENSATIONS 


121 


are  especially  sensitive  to  sour  and  saline  stimulations.  To 
be  sure,  the  localization  is  not  absolute,  especially  for  sour 
and  saline,  but  it  is  very  far  in  advance  of  anything  found 
in  the  olfactory  surface. 

Gustatory  stimuli.  The  substances  which  act  upon  these 
taste  bulbs  must  be  in  liquid  form.  If  one  dries  the  tongue 
thoroughly,  the  substances 
which  would  otherwise  pro- 
duce taste  impressions  can 
be  pressed  against  the 
tongue  without  producing 
any  effect.  For  example, 
a  piece  of  dry  salt  placed 
upon  the  dry  surface  of 
the  tongue  will  not  give 
rise  to  any  taste  sensation. 

rb 


FIG.  37.   A  diagrammatic  sketch  show- 
ing two  neighboring  taste  bulbs 

The  supporting  cells  have  been  removed  in 
the  two  bulbs.  The  bulb  on  the  right  has 
four  specialized  gustatory  cells.  The  network 
of  fibers  at  the  base  of  these  cells  shows  the 
mode  of  distribution  of  the  gustatory  nerve 
fibers.  In  the  bulb  on  the  left  and  in  the 
intermediate  tissue  between  the  bulbs,  the 
terminations  of  the  tactile  nerve  fiber  are 
shown.  The  tongue  is  thus  seen  to  be  an 
organ  of  touch  as  well  as  of  taste 


D.  SENSATIONS  OF  TOUCH 

Organs  of  touch.  The 
group  of  sensations  popu- 
larly classified  under  the 
sense  of  touch  might  very 
properly  have  been  con- 
sidered at  the  beginning 
of  this  chapter,  for  touch 
is  the  human  sense  which 

is  most  closely  allied  in  character  and  in  the  structure  of  its 
organs  to  the  primitive  senses  of  the  lower  animals.  Indeed, 
the  surface  of  the  body  is  a  relatively  undifferentiated  mass 
of  protective  and  sensory  cells,  which  are  open  to  stimula- 
tions of  all  kinds  and  capable  of  responding  in  some  degree 
to  almost  any  form  of  external  energy.  The  true  nerve  cells 
for  the  sense  of  touch  are  situated  in  the  immediate  neigh- 
borhood of  the  spinal  cord.  They  are  primitive  bipolar  cells, 


122  PSYCHOLOGY 

as  shown  outside  the  cord  in  Figs.  13  and  14.  The  branch 
which  passes  out  of  one  of  these  bipolar  cells  toward  the 

AC  of  the  body  is  the  receiving  sensory  fiber.    \Vh 
reaches  the  skin,  it  breaks  up  into  a  fine  network  of  fibrils. 
Tin-so   fibrils  arc  distributed  among  the  cells  of  the  skin. 
The  nerve  fil>er  which  travels  inward  from  the  receiving  cell 

•;ils  into  the  spinal  o>rd.     Such  a  fiber  was  described 
in  the  di  <>f  the  spinal  cord.    It  will  be  recalled  that 

this  central  fiber  branches  so  as  to  extend  upward  and 
downward  through  a  large  section  of  the  spinal  cord,  send- 
ing out  at  various  levels  collateral  branches  which  transmit 
the  stimulation  to  the  motor  cells  at  the  different  levels  of 
the  cord  or  transmit  the  stimulation  to  the  higher  nervous 
centers.  . 

Differentiation  of  the  tactual  fibers ;  temperature  spots. 
The  sensory  fibers  which  pass  to  various  parts  of  the  surface 
of  the  body  seem  to  be  differentiated  in  their  functions  to 
some  extent  in  spite  of  the  uniformity  of  their  structure. 
For,  while  it  is  probably  true  that  there  is  no  region  on  the 
surface  of  the  body  which  is  not  susceptible  to  stimulation 
in  some  degree  by  all  forms  of  external  energy,  provided 
the  energy  is  strong  enough,  yet  it  is  certain  that  there  are 
regions  capable  of  responding  easily  to  slight  changes  in 
pressure  and  temperature.  Indeed,  there  are  areas  which 
show  special  susceptibility  to  pressure,  and  others  which  are 
especially  sensitive  to  temperature.  The  specialized  areas  are 
usually  points  or,  at  most,  limited  areas.  The  most  striking 
demonstration  of  this  differentiation  of  the  skin  can  be  se- 
cured by  taking  a  metallic  point  which  has  been  reduced  some- 
what in  temperature  and  passing  this  point  slowly  across  the 
skin.  At  intervals  the  point  will  be  recognized  as  distinctly 
cold,  while  on  other  parts  of  the  skin  it  will  be  recognized 
merely  as  an  external  pressure  without  temperature  quality. 
Those  areas  where  the  point  is  recognized  as  distinctly  cold 
have  been  designated  cold  spots. 


SENSATIONS  123 

Pressure  spots.  A  second  type  of  specialized  points  on  the 
surface  of  the  skin  includes  those  points  which  are  specially 
susceptible  to  stimulations  of  pressure.  If  one  applies  a  fine 
hair  to  points  on  the  skin,  it  will  be  found  that  there  are  cer- 
tain points  at  which  the  pressure  will  be  recognized,  while 
there  are  other  points  from  which  no  sensation  will  arise. 
Those  points  which  respond  to  the  slightest  stimulation  are 
called  pressure  spots.  The  number  of  pressure  spots  discov- 
ered in  any  special  region  will  depend,  of  course,  upon  the 
intensity  of  the  pressure  exerted  by  the  hair,  so  that  the  term 
"pressure  spot"  is  a  relative  term  and  depends  for  its  exact 
definition  upon  the  intensity  of  the  stimulus  applied  to  the  skin. 

A  part  of  this  differentiation  of  sensory  excitations  is  due 
to  the  structures  which  surround  the  tactual  sensory  fibers, 
but  beyond  this  there  is  a  demonstrated  difference  in  the 
receiving  fibers  themselves. 

Other  "  spots."  Heat  spots  and  pain  spots  can  also  be 
found.  The  heat  spots  are  much  more  diffuse  and  difficult 
to  locate  than  the  cold  spots,  but  they  are  analogous  to  the 
cold  spots  in  their  response  to  changes  in  temperature  stimu- 
lation. Pain  spots  appear  in  certain-  parts  of  the  body  and 
may,  perhaps,  be  defined  as  specially  sensitive  pressure  spots. 
Whole  areas  of  the  body  surface,  as,  for  example,  the  cornea 
of  the  eye,  are  so  sensitive  that  any  stimulation  which  is  rec- 
ognized at  all  will  be  recognized  with  the  quality  of  pain  rather 
than  that  of  simple  pressure.  There  are  certain  reasons  for 
treating  pain  as  distinct  from  pressure.  Thus,  when  a  sen- 
sory nerve  fiber  has  been  injured  and  is  gradually  recovering 
its  functions,  pain  sensibility  and  pressure  •  sensibility  are 
restored  at  different  stages  of  the  recovery. 

Relativity  of  temperature  sense ;  chemical  and  mechanical 
senses.  One  characteristic  of  the  temperature  spots  is  their 
change  in  sensitivity  when  stimulated  for  a  period  of  time  by 
any  given  temperature.  For  example,  the  hand  which  has 
grown  cold  from  a  long  exposure  to  cold  air  will  react  to  water 


IIOLOGY 


such  a  way  as  to  give 

rise. to  the  scnsalion  oi  \\ainith,  while  the  same  liaiul, 

it  lias  been  exposed  to 
warm  air,  will  give  s- 
sations  of  cold  from  the 
san:  '.         lela- 

tivity.  as  it  is  called, 
the  temperature  sense  is 

-___/  —    due  to  the  fact  that  the 

^Jr —     — V      \  yC  -    f   — 

nervous  processes  in- 
volved arc  chemical  proc- 
esses which,  when  once 
established,  change  the 
tf  A.  Tactual  end  organ*  condition  of  the  sensory 

A  section  of  the  cornea  of  the  eye  much  magni-  Organs  SO  that  the  reCCp- 
fied.  The  small  cells  in  the  upper  part  of  the  tjon  of  later  Stimulations 
figure  show  that  the  tissue  is  made  up  of  a  num-  .  . 

ber  of  small,  compactly  arran^  depends    Upon    both    the 

fiber  is  seen  distributing  its  branches  among  present  Stimulation  and 
these  cells.  This  is  a  tvpical  form  of  distribution  ,  .  .  ,  , 

of  the  tactual  fiber,  which  ends  freely  in  the     the  Condition  induced  by 
surface  of  the  body.   (After  Testute)  past  Stimulations.     Simi- 

lar facts  have  been  noted 
in  the  discussion  of  color 
contrasts  and  olfactory 
fatigue.  There  is  no 
marked  relativity  in  the 
case  of  sensory  proc- 
esses of  hearing  or  of 
.ire.  There  is  a 
basis  in  these  differ- 
ences with  regard  to  rel- 
Fi<-..  38  B.  A  Pa-  <  ativity  for  a  distinction 

cinian  corpuscle.  senian    corpuscle,     ^tween      the     chemical 

(After  Testute)  (After  Testute) 

serises  on  the  one  hand, 

including  the  temperature  sense,  the  senses  of  smell,  taste, 
and  vision,  and  the  mechanical  senses  on  the  other  hand, 


SENSATIONS 


125 


including  those  which  depend  upon  direct  excitation  of  the 
nerve  fibers  ;  namely,  pressure  and  hearing.  The  chemical 
senses  show  greater  relativity  and  more  striking  after-effects 
than  do  the  mechanical  senses. 

Organs  of  touch  at  the  periphery.  The  peripheral  endings 
of  tactual  fibers  are  in  some  cases  surrounded  by  special  struc- 
tures ;  in  other  cases  the  fibers  end  freely  among  the  cells  of 
the  skin.  A  number  of  typical  end  organs  arc  shown  in 
Figs.  38-41.  Some  evidence  has  been  accumulated  to  show 
that  the  differentiated  qualities  of 
tactual  sensation  are  related  to  these 
specialized  structures.  Thus,  there 
are  certain  organs  which  appear  in 
the  conjunctiva  where  there  is  no 
sensitivity  for  pressure,  but  where 
there  is  sensitivity  for  cold.  This 
leads  to  the  inference  that  they  are 
special  organs  for  cold.  Again,  cer- 
tain tactual  cells  seem  to  be  espe- 
cially numerous  in  regions  sensitive 
to  pain.  Pain,  however,  is  the  only 
type  of  sensation  from  certain  other 
regions  where  the  fibers  end  freely 
among  the  epithelial  cells.  The  evidence  is,  therefore,  not 
conclusive  that  the  end  organs  in  the  skin  are  specialized ; 
they  may  be  primarily  protective  organs. 

Muscle  sensations  and  organic  sensations.  Sensations  from 
the  inner  organs  of  the  body  have  sometimes  been  classified 
under  the  tactual  sense  ;  sometimes  they  have  been  regarded 
as  constituting  separate  classes.  All  the  inner  organs  of  the 
body  have  sensory  nerve  fibers  similar  to  the  tactual  fibers 
which  end  in  the  skin.  Thus,  the  muscles,  joints,  linings  of 
the  organs  of  the  thoracic,  and  especially  of  the  abdominal, 
regions  are  all  supplied  with  sensory  nerves.  In  discussing 
the  experiences  received  from  the  limbs,  it  is  sometimes 


FIG.  39.  Two  Golgi-Mazzoni 
corpuscles  of  the  type  found 
by  Ruffini  in  the  cutaneous 
connective  tissue  of  the  tip 
of  the  human  finger 


convenient   to  :er   the   name    "  HHIM  le   seiua- 

s  resulting  from  tin  :  the 

sensory  fibers  ending  in  the  muscles.  In  like  manner, 
sensations  from  the  abdominal  organs 
are  sometimes  classified  as  organic 
sensations.  The  motives  for  minute 

s  of  these  sensations  from 
inner  organs  arc  n<  •:  because 

•i!   th  MS    an-    ;  un- 

differentiated.    In  tin-  normal  o 
of    life   ti  into    exjx: 

with  a  great  mass  of  skin  sensations, 
and  they  never  are  intense  except 
when  they  arc  abnormal. 

/-..   SI.NS.U: 

Intensity  a  general  characteristic. 
FIG.  40.    Shows  the  com-    \vhile  it  has  been  necessary  to  dis- 

plex  distribution  of  a  tactual  ....  , 

nerve  fiber  in  the  immcd,ate  cuss  sensation  qualities  in  terms  of 
the  relation  of  these  qualities  to  vari- 
ous organs  of  sense  and  various  forms 

in  region  A  directly  under  the     Qf  external   energy,    it    is   possible  tO 

epidermis  are  to  be  compared 

with    the   freely  ending    nerve     treat  the  matter  of  Sensation   ill!' 

fibers shq^T,  i  hoc    tjcs  jn  a  SOmcwhat  more  general 

fibers  before  their  distribution     , 

in  the  area  .-/form  a  network  in  I  he  relation  of  changes  in  the  in- 
tensity of  objective  sounds  to  changes 
in  the  intensity  of  sound  sensations 
is  of  essentially  the  same  type  as  the 
relation  between  the  intensity  of  pres- 
sure stimuli  and  pressure  sensations. 
Indeed,  it  is  in  this  sphere  of  se 
tion  intensities  that  the  general  methods  of  modern  experi- 
mental investigation  were  first  most  fully  developed.  The 
early  experimental  investigators  had  the  largest  confidence 


vicinity  of  a  hair 
The  freely  ending  nerve  fibers 


the  cut  is  in  the  area  />'.  Around 
the  shaft  of  the  hair  are  certain 
glandular  tissues  marked  G  in 
the  figure.  Branches  from  the 
general  nerve  trunk  are  distrib- 
uted, as  indicated  at  X,  about 
the  hair  and  its  surrounding  tis- 
sues. (After  Kclzius) 


SENSATIONS 


127 


that  they  would  be  able  to  develop  general  mathematical 
formulas  which  would  define  the  relations  between  external 
stimuli  and  sensation  intensity  with  a  degree  of  comprehen- 
siveness and  precision  comparable  to  that  which  is  attained 
in  the  physical  sciences.  As  a  result,  they  performed  the  most 
laborious  experiments  and  collected  a  mass  of  data  which  is 
not  equaled  in  quantity  by  the  data  relating  to  any  other  single 
sphere  of  psychological  phenomena. 

Weber's  Law.  The  general  principle 
which  was  established  by  these  investiga- 
tors is  commonly  known  as  Weber's  Law. 
This  law  states  that  the  increase  in  sen- 
sation intensity  does  not  follow  directly 
the  increase  in  the  physical  stimulus. 
While  the  physical  stimulus  is  increasing 
either  continuously  or  by  additions  of 
small  increments,  the  sensation  increases 
in  recognizable  intensity  only  after  there 
has  been  a  certain  percentage  of  increase 
in  the  intensity  of  the  external  stimulus. 
To  make  the  matter  concrete,  if  a  certain 
intensity  of  light  is  continuously  increased 
or  is  increased  step  by  step  by  small  ad- 
ditional amounts  of  energy,  there  may 
result  in  subjective  experience  no  appreciable  increase  what- 
soever. Before  a  change  in  the  intensity  of  the  sensation  can 
arise,  the  external  light  must  be  increased  by  about  T-J7  of 
its  original  intensity.  Various  investigators  have  found  some- 
what different  fractions  ranging  from  ^^  or  T^Y  to  ^T,  but 
in  any  case  when  the  fraction  is  determined  for  a  given  in- 
tensity of  light,  say  one  hundred  candlemeters,  the  same 
fraction  holds,  at  least  approximately,  for  all  other  medium 
intensities.  The  meaning  of  Weber's  Law  can  be  made 
clear  by  considering  the  following  negative  illustration.  If  we 
add  to  a  single  candle  the  small  quantity  of  light  necessary 


FIG.  41.     Tooth   of 

Gobinus  showing  dis- 
tribution of  nerve 
fiber  throughout  the 
canal  of  the  tooth. 
(After  Retzius) 


128  PSYCHOU 

to  increase  it  by  j^B,  an  observer  will  be  able  to  recognize 
the  change.  i  to  a  light  of  one  . 

candle-powers   the  same  1  ^  of  a  single  candlcpowt r.  the 
effect  will  be  absolutely  unappreciable ;  that  is.  the  senv 
in  consciousness  will  not  be  modified  at  all.  -Ten  candle- 
powi  be  adik-il  t<>  one  thousand  before  an  appreciable 

chan-  ;>l.ur  in  the  observer's  experience. 

General  statement  of  the  law.  The  law  holds  in  general 
for  all  spheres  of  sensation  intensity.  The  ratio  of  increase 
in  the  different  spheres  of  sensation  differs.  Thus,  while 
it  is  f£0  for  light,  it  is  given  by  \Vundt  as  ^fa  for  pressure. 
Other  fractions  are  reported  for  other  spheres  of  sensation. 
In  general,  however,  the  relation  is  always  of  the  same  type. 
It  has  been  expressed  briefly  in  the  statement,  if  the  sen- 
sation is  to  increase  in  an  arithmetical  ratio,  the  stimulus 
must  increase  in  a  geometrical  ratio.  The  range  of  applica- 
bility of  this  general  principle  is  limited  in  each  case  to 
stimuli  of  moderate  intensities. 

Mechanical  explanation  of  Weber's  Law.  After  the  law 
has  been  established  as  a  statement  of  an  empirical  fact,  it 
is  by  no  means  easy  to  determine  its  value  for  the  explana- 
tion of  mental  life.  It  probably  expresses  a  law  of  nervous 
behavior  which  is  a  special  case  under  the  general  mechanical 
principle,  that  any  increase  in  any  form  of  physical  activity 
becomes  more  and  more  difficult  as  this  activity  reaches  a 
higher  level  of  intensity.  For  example,  it  is  extremely 
difficult  to  add  to  the  speed  of  a  locomotive  beyond  a  certain 
point.  If  the  locomotive  is  moving  at  the  rate  of  fifteen 
miles  an  hour,  a  moderate  increase  in  the  amount  of  energy 
applied  to  the  machinery  will  increase  the  speed  by  a  mile 
an  hour.  If,  however,  the  engine  is  moving  at  the  rate  of 
sixty  miles  an  hour,  the  amount  of  energy  which  must  be 
expended  to  add  one  mile  to  its  speed  is  very  much  greater 
than  the  amount  which  was  necessary  to  add  this  same  in- 
crement of  speed  when  the  engine  was  moving  at  the  rate 


SENSATIONS  129 

of  fifteen  miles.  This  mechanical  principle  is  applicable  to 
the  action  of  the  nervous  system.  If  the  external  stimulus 
acting  upon  the  sense  organs  is  producing  a  certain  mod- 
erate degree  of  chemical  activity,  that  chemical  activity  can 
be  intensified  by  a  small  .addition  to  the  external  stimulus. 
If,  however,  the  stimulus  acting  upon  the  nerve  cells  is  so 
strong  that  it  demands  nearly  all  of  the  energy  that  the  cell 
is  capable  of  giving  out,  then  the  small  addition  to  the 
stimulus  will  produce  no  effect.  Since  this  is  a  general 
principle  of  all  nervous  behavior,  it  is  a  principle  which 
appears  alike  in  all  the  different  spheres  of  sensation. 

Other  views  regarding  Weber's  Law.  Other  interpreta- 
tions of  Weber's  Law  have  been  given  in  the  history  of 
psychology.  One  such  interpretation,  given  by  Fechner, 
was  of  a  most  ambitious  type  and  was  intended  by  its  author 
to  express  in  exact  mathematical  terms  the  general  relation 
between  mind  and  matter.  The  significant  fact  which 
Fechner  was  emphasizing,  that  the  relation  between  con- 
sciousness and  the  physical  world  is  not  direct,  is  abundantly 
established  by  considerations  of  a  more  general  character 
than  those  which  Fechner  took  up.  We  have  seen  in  our 
earlier  discussions  of  sensation  qualities  that  there  are  many 
other  phases  of  experience  which  do  not  parallel  the  physical 
facts  with  which  they  are  related.  The  importance  of  Weber's 
Law  as  a  demonstration  of  the  indirectness  of  the  relation 
in  question  is,  therefore,  relatively  less  now  than  it  was  in 
the  time  of  Fechner,  and  his  definite  mathematical  formulas 
are  of  no  value.  The  whole  stu/iy  of  sensation  intensities 
was,  indeed,  more  productive  for  general  psychology  in  the 
experimental  methods  which  it  served  to  cultivate  than  in 
the  contribution  which  it  made  to  the  content  of  psychology. 
The  discussion  of  sensation  intensities  may,  accordingly,  be 
dismissed  without  further  detail. 


CHAPTER  VI 

EXPERIENCE  AND  BEHAVIOR 

All  consciousness  complex  and  selective.  A  man  comes 
into  a  room  and  sees  a  piece  of  paper  on  the  tablr.  H< 
walks  to  the  table,  picks  up  the  paper,  and  after  liking  at 
it  throws  it  down  again.  If  we  try  to  give  a  psychological 
explanation  of  these  acts,  we  find  ourselves  adopting  some 
such  formula  as  this.  The  act  of  going  to  the  table  and 
picking  up  the  paper  is  due  to  curiosity  and  an  inner  desire. 
Curiosity  and  desire  are  aroused  by  the  sensory  impression 
which  the  paper  made  on  the  man's  eye.  After  the  first 
act  of  picking  up  the  paper,  a  new  series  of  visual  im- 
pressions fell  on  the  retina ;  these  new  impressions  aroused 
a  new  series  of  inner  processes  and  the  act  of  throwing 
down  the  paper  followed.  Experience  is  thought  of  under 
this  formula  as  a  series  of  cycles,  each  beginning  in  a  sen- 
sation and  ending  in  an  act. 

The  formula  is  much  too  simple.  When  we  consider 
carefully  the  first  statement  "  sees  a  piece  of  paper,"  we  find 
at  once  that  we  are  dealing  not  with  a  sense  impression 
alone ;  we  are  dealing  with  a  vigorous  form  of  behavior. 
The  act  of  looking  at  an  object  involves  the  turning  of  the 
two  eyes  in  a  very  complicated  way  on  the  object  and  in- 
volves also  the  focusing  of  the  lenses  inside  the  eyes.  N"t 
only  so,  but  looking  at  an  object  is  a  highly  selective  per- 
formance. The  room  into  which  the  man  came  offered  to 
his  vision  a  hundred  shades  of  color  and  a  hundred  varieties 
of  brightness.  Out  of  all  these  he  fastened  on  one  small 
patch.  The  walls  of  the  room  were  quite  as  bright  as  the 

130 


EXPERIENCE  AND  BEHAVIOR  131 

paper  and  very  much  more  extensive  ;  they  offered  sensa- 
tions which  in  their  quality  and  intensity  would  overwhelm 
the  piece  of  paper  if  sense  impressions  alone  determined 
the  flow  of  mental  life.  The  fact  that  the  man  looked 
at  the  paper  rather  than  at  the  walls  is  the  first  and  most 
essential  fact  which  the  psychologist  must  take  into  account 
if  he  would  give  an  adequate  explanation  of  the  later  act  of 
picking  up  the  paper. 

The  selective  character  of  conscious  processes  related  to 
sensory  impressions.  Our  common  descriptions  emphasize 
the  active  character  of  the  processes  of  recognition  here 
under  discussion."  We  say  the  man  is  interested  in  pieces 
of  paper,  while  he  has  no  special  interest  in  walls.  Or  we 
say  that  the  man  is  trained  to  give  attention  to  what  is  on 
the  table,  but  is  indifferent  to  the  walls  of  the  room.  Some- 
times we  go  further  and  give  the  explanation  of  the  man's 
interests  and  his  attention  by  saying  that  he  has  cultivated 
certain  associations  or  certain  modes  of  thinking  which 
determine  the  directions  in  which  his  mind  turns. 

Such  statements  make  it  clear  that  psychology  cannot  rest 
content  with  the  explanation  that  each  cycle  of  experience 
begins  with  a  sensory  impression.  By  the  time  the  mind 
receives  a  sensory  impression  the  selective  process  has  gone 
a  long  way ;  the  selective  process  which  is  involved  in  at- 
tending to  a  sense  impression  is  itself  a  preliminary  stage 
of  no  small  importance. 

It  will  not  be  amiss  to  recall  at  this  point  one  of  the 
important  lessons  drawn  from  our  study  of  the  evolution  of 
the  organs  of  sense.  Our  organs  of  sense  are  by  their  very 
structure  selective  organs.  The  eye  cannot  respond  to  rays 
of  light  below  the  red  or  beyond  the  violet.  The  ear  does 
not  record  sounds  of  the  slowest  rates  of  vibration  or  those 
of  the  highest  pitch.  Evidently  the  organism  has  been 
determined  in  its  evolution  by  causes  which  are  more  funda- 
mental than  those  of  mere  sensation,  for  there  has  been  no 


132  PSYCH- 

.;ion  of  universal  sense  organs,  but  only  evolution  <>f 
organs  capable  o:  :n   impressions  \\hii-h  tiu 

organism  can  use  in  promoting  its  own  1; 

Selective  consciousness  related  to  behavior.    The  key  to 
this  whole  mattrr  is  found  in  a  study  of  bodily  . 
Every  animal  is  a  reacting  being.    All  its  functions  r 
to  what  it  can  do.     I •••:     \amplc,  there  is  a  certain  range  of 
objects  which  are  of  such  size  that  they  can  be  picked  up 
by  the  human  hand  or  moved  by  human  fingers.     It  i 
impressive  fact  of  biology  that  the  range  of  human  v: 
corresponds  to  this  range  of  action.     \Vc  do  not  ha 
scopic  eyes  like  the  fly.     Nor,  on  the  other  hand,  do  we 
have  distance   vision   like   the  eagle's.    With   our   present 
organs  of  behavior  we  could  not  react  to  the  minute  objects 
which  the  fly  sees,  nor  could  we  use  far-sighted  eyes  to  ad- 
vantage from  our  position  near  the  ground,  for  even  if  we 
could  sec  at  great  distances,  we  could  not  move  fast  en- 
to  take  advantage  of  our  superior  sight.    The  range  of  human 
vision  has  been  determined  by  the  range  of  possible  human 
reactions.    The  impressions  of  the  eye  are  of  importance 
only  when  there  is  a  corresponding  power  of  action. 

Common  interests  and  their  relation  to  behavior.  That 
action  is  a  determining  consideration  in  mental  life  will  be 
clearly  seen  when  one  begins  to  look  at  ordinary  experience 
with  a  view  to  finding  what  is  back  of  sensations.  One  who 
is  not  interested  in  doing  something  with  trees  will  pass 
them  a  thousand  times  and  never  really  see  them.  The 
maple  tree  has  a  shape  wholly  different  from  that  of  the 
elm.  The  barks  of  the  two  are  quite  different.  The  casual 
observer  passes  these  trees  day  after  day  and  his  retina 
receives  the  appropriate  sensory  impressions  with  their  van- 
ing  characteristics,  but  the  impressions  go  to  waste.  Let 
this  observer  be  induced  to  try  to  draw  the  trees,  and  his 
experiences  undergo  a  vast  change.  The  impressions  begin 
to  be  vivid ;  they  have  not  undergone  any  modification  in 


^  EXPERIENCE  AND   BEHAVIOR  133 

their  character  as  sensory  excitations,  but  they  have  taken 
on  new  importance  in  the  psychological  world.  The  psycho- 
logical character  of  the  impression  can  be  described  only 
by  saying  that  the  impression  has  been  selected  for  attention 
or  has  been  made  vivid  and  distinct  by  virtue  of  the  effort 
to  use  it. 

Another  example  is  found  in  the  familiar  experience  of 
not  hearing  a  clock  tick  so  long  as  one  is  absorbed  in  read- 
ing. When  the  reading  is  over  and  there  are  no  dominating 
ideas  in  the  mind,  the  ticking  begins  to  be  heard.  The  fact 
is,  of  course,  that  the  ear  recorded  the  ticking  in  both  cases. 
While  one  was  reading,  the  nervous  system  was  pouring  its 
energy  into  the  eyes  which  were  looking  along  the  printed 
lines.  There  was,  furthermore,  the  general  muscular  reaction 
characteristic  of  purely  visual  attention,  the  tense  breathless 
interest  in  the  story  on  the  printed  page.  The  auditory  im- 
pressions were  absorbed  into  this  stream  of  active  processes 
and  were  lost.  When  the  activity  of  reading  is  over  and  the 
body  and  the  nervous  system  fall  back  into  the  miscellaneous 
activities  characteristic  of  partial  relaxation,  there  may  be  a 
turning  of  the  head  to  listen  and  then  the  ticking  may 
occupy  the  center  of  attention. 

One  might  multiply  examples  indefinitely.  On  the  street 
we  pay  little  or  no  attention  to  the  people  whom  we  are 
passing.  Our  one  purpose  in  most  cases  is  to  avoid  collision, 
and  our  attention  to  sensory  experience  is  just  enough  to 
serve  this  end.  The  skilled  cabinetmaker  sees  in  a  piece 
of  furniture  elements  which  the  untrained  layman  would  not 
notice.  The  hunter  observes  what  the  stranger  in  the  woods 
overlooks.  Everywhere  it  is  behavior  that  determines  the 
emphasis  on  sensory  impressions. 

Study  of  evolution  of  organs  of  action  as  important  as 
study  of  senses.  The  relation  of  bodily  activity  to  mental 
processes  will  be  more  fully  understood  if  we  trace  the  evo- 
lution of  the  muscular  system  and  its  operations  much  as  we 


134  PSYCHOLOGY 

(1  the  evolution  of  tin-  organs  of  sense.  In  an  earlier 
i  hapter  the  primitive  muscle  cells  in  the  body  wall  of  the 
hydra  were  shown  in  ind  the  contrast  in  both  form 

and  function  In-tween  tlu-  muscle  cells  and  the  neural  cells 
was  pointed  out.     The  muscle  cell  is  lar^e  and  elongated. 
It   is  l.ir^e  so  that  it  can  store  up  more  energy  than  • 
be  stored  in  a  small  cell,  and  its  elongated  form  fa 
traction.  |  single  muscle  cell  of  one  of  the 

higher  animals.     A  HIUM  lc  is  made  up  of  a  mass  of  such 
cells,     F.vcry   mu-.  ipplied  with  a  nerve  the  ends  of 

which  are  distributed  t<>  the  cells  and  prodiu< 
of  the  muscle  In  discharging  motor  impulses  into  the  > 
The    phenomena   of  contraction  are   illustrated   in    Fig.  43. 
This   process  of  contraction  consists   in   an   inner  chemical 
change  which  uses  up  a  part  of  the  energy  stored  up  in  the 

cell  body.    The  ; 

may    be   com- 

,         ,  pared  to  combustion. 

FIG.  42.    A  highly  developed  muscle  cell 

When     a     piece     of 

wood  burns,  it  gives  off  a  part  of  the  energy  stored  up  in 
its  complex  chemical  substances.  So  it  is  with  the  muscles ; 
they  give  out  energy  and  have  left  behind  certain  waste 
products  which  may  be  described  as  the  ash  of  combustion. 
Evolution  from  gross,  muscles  to  highly  differentiated 
muscles.  The  highly  specialized  muscle  cells  of  the  type 
sh  >wn  in  Fig.  42  have  been  evolved  from  the  cells  which 
m  ike  up  the  surface  of  the  body  in  such  simple  animals  as 
the  hydra.  Furthermore,  the  muscles  of  the  higher  animals 
have  in  the  course  of  evolution  become  differentiated  into  a 
large  number  of  highly  specialized  groups  of  muscle  cells.  A 
single  illustration  will  make  clear  the  type  of  evolution  which 
has  gone  on  in  all  parts  of  the  body.  The  mouth  of  one  of 
the  lower  animals,  such  as  a  fish,  is  opened  and  closed  by 
very  simple  muscles.  In  the  higher  animal  forms  the  differ- 
entiation of  muscles  goes  much  further.  The  opening  and 


EXPERIENCE  AND  BEHAVIOR 


shutting  of  the  human  mouth,  for  example,  is  not  a  single 
gross  performance  as  in  the  fish.  The  muscles  of  the  lips 
have  been  evolved  and  so  highly  differentiated  that  one  side 
of  the  mouth  can  be  moved,  as  it  is  in  many  forms  of  facial 
expression,  quite  independently  of  the  gross  opening  and 
closing  of  the  jaw,  which  is  the  only  form  of  movement  of 
which  the  fish  is  capable. 

In  like  manner  the 
hand  exhibits  a  high 
differentiation  of  the 
muscles.  When  we 
study  the  ability  of  a 
human  being  to  move 
one  finger  apart  from 
the  rest  of  the  hand, 
we  realize  how  far  dif- 
ferentiation of  the  mus- 
cles has  gone. 

Behavior  dependent 
on  nervous  control.  The 
highly  differentiated 
muscular  system  of  the 
human  body  takes  on  a 
greater  significance  for 
the  student  of  psychol- 
ogy when  it  is  kept  in 
mind  that  the  muscles 
are  always  connected 
with  the  nervous  system  and  are  absolutely  dependent  on 
the  nervous  system  for  the  impulses  which  cause  their  con- 
traction. In  the  lowest  animal  forms  the  muscle  cells  had  a 
general  irritability,  but  in  the  process  of  evolution  the  muscle 
cells  have  been  specialized  to  store  up  great  quantities  of 
energy.  They  do  not  in  their  later  specialized  stage  receive 
impressions  directly  from  the  outer  world.  They  contract 


FIG.  43.    The  contracted  and  relaxed  state 
of  a  muscle 

The  dotted  lines  within  the  muscle  show  the 
distribution  of  the  nerve  fiber 


136  PSYCHOLOGY 

only  when  they  are  excited  i>\.  nervous  impulses.    Tt 
the  animal,  the  more  its  muscles  have  become  der* 
the  nervous  system.    The  result  is  that  \\hrn  the  muscular 
system  becomes  highly  differentiated  then-  must  be  a  pot 
evolution  of  the  nervous  centers  related  t«.  these  muscles. 
There  has  been,  accordingly,  a  steady  evolution  of  the  con- 
trolling nervous  organs.    When  we  study  the  human  hand 
and   its   complex   possibilities   of   adjustment   or  when   we 
study  the  delicate  movements  of  the  human  f  must 

always  have  in  mind  the  fact  that  there  are  corresponding 
differentiations  of  the  nervous  system. 

Coordination  as  necessary  counterpart  of  differentiation. 
There  is  another  consequence  of  this  differentiation  of 
the  motor  organs  which  is  of  importance  for  our  study. 
The  highly  differentiated  muscles  may,  indeed,  contract 
each  by  itself  in  the  performance  of  some  special  function 
for  which  it  was  evolved,  but  for  the  most  part  the  special 
muscles  act  in  systems.  The  individual  muscle  becomes 
for  the  purpose  of  the  moment  not  a  separate  organ,  but 
a  part  of  a  system  of  cooperating  muscles.  For  example, 
the  single  finger  may  move  by  itself,  but  in  many  of  the 
activities  of  life  the  single  finger  contributes  its  strength 
to  a  grasping  movement  which  enlists  all  the  other  fingers 
and  the  whole  hand.  In  a  grasping  movement  the  finger  is 
not  a  separate  organ.  Here,  then,  we  have  a  complex  situ- 
ation ;  the  differentiated  muscles  which  move  the  finger 
must  sometimes  act  separately,  sometimes  as  parts  of  a 
combination  of  many  muscles.  In  the  same  way  the 
nervous  centers  must  be  both  specialized  and  capable  of 
entering  into  combination. 

Individual  development  in  behavior.  The  history  of  indi- 
vidual development  of  muscular  control  shows  how  compli- 
cated is  this  matter  of  muscular  action.  There  is  a  natural 
tendency  on  the  part  of  the  infant  to  contract  certain  of  the 
muscles  of  the  body  in  a  primitive  gross  combination.  Thus, 


EXPERIENCE  AND  BEHAVIOR  137 

the  infant  can  close  the  hand  on  any  small  object  like  a 
pencil  which  is  laid  across  the  palm.  The  fingers  all  enter 
into  this  act,  and  the  muscular  system  of  the  hand  and  arm 
cooperate  in  a  single  performance.  This  primitive  act  is 
very  like  that  exhibited  by  the  animals  lower  in  the  scale 
than  man.  In  the  course  of  later  life  the  child  will  have  to 
acquire  by  practice  the  ability  to  move  his  individual  fingers 
without  including  the  others.  Thus,  if  he  learns  to  play  on 
the  piano,  he- must  not  move  all  the  fingers  together.  In 
such  a  case  he  must  learn  to  differentiate  the  fingers  from 
each  other. 

.  Conversely,  there  arises  even  in  infant  life  the  necessity 
of  developing  a  careful  cooperation  between  the  different 
parts  of  the  body.  The  two  hands  must  work  together  in 
grasping  an  object.  The  head  and  eyes  must  turn  toward 
an  object  which  the  hand  is  to  grasp.  Later  in  life  the 
fingers  which  have  become  skilled  in  striking  the  piano 
keys  separately  must  cooperate  in  striking  the  chord. 

In  these  examples  the  body  is  seen  to  be  a  highly  evolved 
system  of  reacting  organs  constantly  developing,  on  the  one 
hand,  in  the  direction  of  finer  and  more  delicately  adjusted 
movements  and,  on  the  other  hand,  in  the  direction  of 
more  complex  combinations  of  these  differentiated  forms 
of  behavior. 

In  terms  of  our  description  we  may  distinguish  three 
stages  of  muscular  activity,  always  recalling  that  there  are 
corresponding  stages  in  the  development  of  processes  in 
the  nervous  system.  First,  there  are  gross  adjustments ; 
second,  differentiated  forms  of  movement ;  and  third,  coor- 
dinated forms  of  action.  The  term  "  coordination "  here 
introduced  will  recur  frequently  in  later  discussions.  Its 
meaning  will  be  clear  from  the  foregoing  discussions.  A 
coordinated  movement  is  one  in  which  groups  of  differen- 
tiated muscles  cooperate  under  the  control  of  nerve  centers, 
thus  producing  complex  but  completely  unified  acts. 


138  PSY<  I; 

Inherited  coordinations  or  instincts.  There  is  one  impor- 
tant fact  of  heredity  \\huh  must  be  included  in  the  pre- 
liminary 'ii  of  bodily  movement  before  we  are  in  a 
position  to  understand  fully  the  relation  of  behavior  to  con- 
1  iu-  higher  animals  come  into  the  world  with 
many  coordinated  forms  of  behavior  fully  provided  for  in 
the  inherited  structure  of  their  nervous  systems.  For  ex- 
ample, a  human  infant  is  able  at  the  beginning  of  life  to 
use  the  lips  and  tongue  in  the  complex  act  of*  sucking  and 
lu-  is  able  also  to  swallow  through  the  cooperation  of  the 
musiles  of  the  throat.  )  Such  an  inherited  complex  of  coor- 
dinated acts  is  called  an  instinct.  The  nervous  centers  in 
control  of  the  lips  and  tongue  are  evidently  coupled  by 
lines  of  connection  which  the  long  experience  of  the  race 
has  laid  down,  and  the  infant  is  equipped  from  the  first 
not  only  with  differentiated  muscles  and  controlling  centers 
but  with  a  fully  developed  organization  in  his  nervous  system 
which  results  in  the  cooperation  of  the  differentiated  centers. 

Glands  as  active  organs.  To  this  discussion  of  the  devel- 
opment of  the  muscles  and  their  contraction  should  be  added 
the  comment  that  there  is  another  group  of  active  organs ; 
namely,  the  glands.  These  secrete  under  the  stimulus  of 
the  nervous  system,  and  their  behavior  can  for  purposes  of 
our  discussion  be  regarded  as  like  that  of  the  muscles. 

A  constant  tension  of  active  organs  as  background  of  all 
behavior.  In  order  to  understand  the  relation  of  the  be- 
havior of  the  muscles  and  glands  to  consciousness,  one 
general  fact  which  is  very  commonly  overlooked  must  be 
kept  clearly  in  view.  The  active  organs  of  the  body  are 
at  all  times  during  life  in  a  state  of  tension.  There  are 
constantly  pouring  out  of  the  nervous  system  streams  of 
motor  excitations.  These  are  distributed  to  different  parts 
of  the  body  in  currents  of  varying  intensity,  but  there 
is  always  a  stream  of  motor  impulses  going  to  the  active 
organs. 


EXPERIENCE  AND  BEHAVIOR  139 

One  reason  why  this  fact  is  not  clearly  recognized  is  that 
we  ordinarily  think  of  the  nervous  system  as  in  action  only 
when  some  part  of  the  body  is  actually  moving.  Thus,  if 
the  hand  moves  from  near  the  body  to  a  distant  point  in 
order  to  pick  up  some  object,  we  realize  that  the  muscles 
of  the  arm  are  contracting.  But  if  the  individual  sits 
rigidly  in  his  seat,  resisting  the  impulse  to  reach  for  the 
object,  we  overlook  the  fact  that  his  muscles  are  on  the 
stretch,  often  to  an  extent  involving  much  greater  effort 
than  would  be  required  to  grasp  the  object. 

Evidences  without  end  could  be  adduced  to  show  that 
the  muscles  are  in  constant  action.  The  neck  muscles 
are  constantly  in  action  holding  up  the  head  of  a  waking 
man.  Let  the  neck  muscles  relax  for  a  moment,  as  they 
do  when  the  man  begins  to  get  drowsy,  and  gravity  will 
pull  the  head  fonvard,  giving  a  striking  exhibition  of  the 
work  which  the  neck  muscles  are  doing  most  of  the  time. 

Again,  consider  what  happens  at  all  times  by  way  of  brac- 
ing the  body  for  movements.  The  trunk  muscles  tighten 
when  the  hand  begins  to  reach  out  because  the  trunk  must 
balance  the  new  weight  which  is  taken  up  in  the  hand. 

Not  alone  the  trunk  muscles  but  the  whole  inner  mech- 
anism of  the  body  is  drawn  into  action  even  by  the  most 
trivial  movement.  The  blood  circulation  accommodates  it- 
self to  every  act.  This  means  that  the  contraction  of  an 
arm  muscle  calls  for  more  blood  to  the  arm.  The  call 
affects  the  heartbeat  and  the  contraction  of  the  muscles 
in  the  arteries  which  control  the  pressure  of  the  blood  in 
all  parts  of  the  body.  The  adjustment  of  blood  circulation 
affects  respiration  and  digestion  and  the  inner  glandular 
action,  until  finally  the  whole  body  is  involved  in  the1  effort 
to  move  the  arm. 

Meaning  of  sensory  impressions  dependent  upon  inner 
conditions.  We  are  now  in  a  position  to  understand  the  facts 
which  were  taken  up  in  the  early  paragraphs  of  this  chapter. 


140 

A  sensor)'  impression  does  not  co  rvous  system 

th.a  ^  to  be  aroused  to  ai 

sory  impression  is  not  the  first  or  primary  step  in  a  scries 
of  nervous  processes.  The  sensory  impression  comes 

an  inruT  world    full  of  ;c  new  impression  may 

change  the  modi-  it  may  be  absorbed  into  the 

processes  under  way.    A  Bother  figure,  we  may 

•h.it   the  inner  \\<nld  -iV'»K  its  ma: 

into  a  pattern.  The  new  sensory  impression  is  new  raw 
material.  It  may  be  v  to  shut  down  the  machinery 

and  recast  the  pattern  in  order  to  deal  with  this  new  mate- 
rial. Ordinarily  it  is  not  mve.Nsary  to  shut  down.  Ordinarily 
the  new  raw  material  is  perfectly  familiar  and  with  very  little 
disturbance  of  the  routine  is  absorbed  into  the  existing  pat- 
tern, and  the  machinery  goes  on  as  it  was  working. 

ier  analogies  could  be  drawn  on  to  help  in  describing 
the  situation  ;  the  best  arc  always  those  which  are  closest  to 
mental  life  itself.  Thus  a  social  group  receives  a  newcomer. 
I'he  arrival  is  not  the  beginning  of  the  group's  social  ; 
ity.  The  arrival  may  make  no  striking  impression  on  the 
conversation.  On  the  other  hand,  the  new  arrival  may  turn 
all  currents  of  thought  and  social  life  into  new  channels. 
The  new  social  situation  in  any  case  will  be  the  result  of 
what  was,  plus  the  modifying  influence  of  what  now  is. 

Sensory  processes  and  the  equilibrium  of  action.    So  it  is 
in  the  action   of  the  nervous  system.     Ik-fore  a  particular 
•ry  impression  comes,  the  nervous  system  is  in  a  st;; 

ition.  Continuous  streams  of  incoming  sensory 
impulses  and  streams  of  outgoing  motor  processes  constitute 
a  complex  of  nervous  life.  The  character  of  this  complex  is 
determined  primarily  by  those  inner  paths  of  combination 
which  have  been  developed  in  the  organism's  history  and 
in  its  past  struggles  with  the  world.  Into  this  inner  world 
with  its  stresses  and  strains  comes  a  new  sensory  impulse. 
In  the  great  majority  of  cases  the  new  impulse  does  not 


EXPERIENCE  AND  BEHAVIOR  141 

work  any  radical  effect.  The  central  processes  are  under 
way  and  they  go  on  as  before,  absorbing  into  their  main 
current  the  little  stream  of  new  sensory  energy.  Every  now 
and  then  the  new  impulse  is  so  strong  or  it  fits  into  the 
workings  of  the  central  nervous  system 'with  such  a  power 
to  change  the  equilibrium  of  action  that  a  radical  change 
takes  place.  One  is  reading  and  hears  his  name  called 
from  the  next  room.  The  name  arouses  action  because  it  is 
imperative  in  its  command  over  one's  action.  The  call  need 
not  be  strong,  but  it  is  one  of  the  keys  to  a  vigorous  form 
of  behavior  entirely  opposed  to  reading.  In  such  a  case  the 
action  is  abruptly  changed  in  its  direction  of  operation. 

Importance  of  sensations  dependent  on  organization.  Even 
when  one  of  the  abrupt  and  impressive  changes  in  central 
nervous  action  comes,  it  is  not  the  sensory  impulse  as  such 
which  explains  the  change.  The  ability  of  the  individual  to 
react  is  here  the  chief  consideration.  An  impression  can 
never'  be  strong  unless  the  organization  of  the  individual  is 
prepared  to  receive  it.  Indeed,  as  pointed  out  earlier  in  the 
chapter,  the  whole  evolution  of  the  animal  world  indicates 
that  the  sense  organs  themselves  evolve  in  the  direction 
dictated  by  the  demands  for  action. 

Sensations  unduly  emphasized  through  introspection.  The 
discussion  of  activity  as  taken  up  thus  far  in  this  chapter 
has  made  very  few  appeals  to  the  reader's  conscious  analysis 
of  his  own  experiences.  The  reason  is  that  the  view  of  con- 
sciousness here  presented  is  not  the  one  suggested  by  intro- 
spection. Introspection  tends  to  bring  into  overemphatic 
relief  new  sensory  impressions.  It  is  not  difficult  to  note 
what  goes  on  in  consciousness  when  a  color  is  seen  or  a 
sound  is  heard,  for  the  points  in  consciousness  where  a  color 
or  a  sound  becomes  vivid  are  relatively  easy  to  distinguish 
'from  the  main  current  of  mental  life.  Consciousness  pauses 
for  a  moment  and  gives  emphasis  to  the  arrival  of  the  new- 
comer. It  is  much  more  difficult  to  look  at  the  main  current 


1 4  -  I '  >  \  »   I  i  • 

\periencc  because  a  person  is  in  the  midst  of  the  cur- 
absorbed  in  its  movement  and  thus  without  any 
trusts  by  means  of  which  to  make  himself  vividly  aware  of 
that  which  fills  his  whole  mind.  Just  as  the  social  group 
which  was  referred  to  a  few  paragraphs  back  is  not  aware 
of  its  own  atmosphere  and  of  its  own  appearance  but  is 
clearly  conscious  of  the  new  member,  so  personal  conscious* 
ness  must  adopt  new  scientific  methods  of  recognizing  its 
own  characteristics. 

Attitudes.  Perhaps  the  use  of  a  special  term  will  help  in 
bringing  out  what  is  here  being  emphasized.  There  i^  in 
every  mental  act  an  aspect  which  comes  from  the  individual's 
reactions  on  his  impressions.  We  may  call  this  aspect  of 
experience  an  attitude.  Thus  there  are  attitudes  of  liking 
and  disliking.  If  the  attitude  is  vivid,  one  may  readily  ana- 
lyze it  out  of  the  complex  and  say,  "  I  like  the  color  or  the 
sound  or  the  taste,"  or  "  I  dislike  the  impression."  If  the 
attitude  is  not  so  vivid  or  so  distinctive  in  character,  it  may 
be  more  difficult  to  separate  it  for  purpose  of  study  from 
the  impression.  A  color  may  receive  the  attention  of  an 
observer,  thus  arousing  a  very  definite  and  positive  attitude 
called  attention,  but  it  is  difficult  to  describe  what  one 
means  by  the  word  "  attention."  It  is  also  difficult  to  dis- 
entangle attention  from  the  color  experience  itself.  Yet  a 
moment's  scientific  consideration  of  the  matter  will  make 
it  quite  evident  that  the  conditions  of  attention  are  to  be 
found  in  the  individual's  organization  and  active  processes. 
No  sensory  impression  carries  in  itself  the  qualities  which 
command  attention.  Attention  is  a  contribution  of  the  inner 
world  ;  it  is  an  attitude  of  the  individual. 

Attitudes  not  related  to  sensations  but  to  behavior.  Our 
attitudes  are  as  manifold  as  our  modes  of  response  to  im- 
pressions and  ideas.  In  the  next  chapter  we  shall  select  for 
treatment  some  of  the  chief  attitudes  of  ordinary  life.  In 
the  meantime,  it  is  the  purpose  of  this  chapter  to  reiterate 


EXPERIENCE  AND  BEHAVIOR 


143 


the  fact  that  all  attitudes  are  phases  of  behavior.  The  psy- 
chology of  the  individual  must  study  modes  of  behavior 
quite  as  much  as  sensations.  Indeed,  if  one  is  to  be  empha- 
sized more  than  the  other,  it  is  the  business  of  science  to 
bring  out  the  significance  of  behavior,  since  this  is  likely  to 
be  overlooked  by  the  superficial  observer. 


SUMMARY 

Relation  of  sensation  to  reaction.    It  may  be  well  to  summarize 
the  conclusions  reached  up  to  this  point  by  means  of  a  diagram. 


Object 


Individual 
FIG.  44.    Diagram  showing  relation  of  sensory  impressions  to  reactions 

Let  the  rectangle  at  the  left  of  Fig.  44  represent  some  object 
in  the  physical  world  —  a  book  or  a  piece  of  machinery.  The  ob- 
ject has  many  physical  characteristics  which  are  represented  by  the 
subdivisions  i  to  9.  Some  of  these  impress  a  human  being  ;  others 
do  not.  For  example,  the  machine  may  send  out  waves  of  electric 
energy  for  which  we  have  no  organ  of  sense ;  the  book  may  send 
out  ultraviolet  rays  of  light  which  lie  beyond  the  range  of  vision. 
Subdivision  7  represents  the  power  of  emitting  electric  energy ; 
subdivision  8,  the  power  of  giving  out  ultraviolet  rays.  When 
energy  from  7  and  8  reaches  the  surface  of  the  human  body  there 
is  no  organ  for  the  reception  of  the  stimulation.  Subdivision  i ,  on 


144  ('^ 

the  other  hand,  represents  the  power  to  reflect  red  light,  and 
subdivision  2  represents  solidity  or  resistance  to  touch.  These  do 
impress  the  human  body  if  they  strike  the  right  points,  as  indicated 
by  the  dotted  1  muing  lines  i  a  and  a.  Line  i  b  represents 

a  ray  of  light  which  does  not  strike  the  eye,  but  strikes  some  part 
«f  the  skin  and  produces  no  effect 

Let  us  follow  the  dotted  lines  which  represent  currents  of  sen- 
sory excitation  entering  the  central  nervous  system  from  the  eye 
and  finger.  It  is  not  usual  for  the  central  nervous  system  to  receive 
only  two  sensor)'  impressions  at  any  given  moment,  but  for  .the 
sake  of  simplicity  the  others  are  omitted. 

soon  as  these  sensory  processes  enter  the  central  nervous 
;n  they  begin  to  flow  toward  the  muscles  which  constitute  the 
second  surface  of  the  body  represented  by  the  right-hand  boundary 
of  the  rectangle  standing  for  the  individual.    In  the  muscular  sys- 
tem there  are  certain  contractions  —  m,  n,  /,  r,  s,  t,  «,  and  v,  which 
an-  the  results  of  motor  impulses  flowing  out  from  the  nervous 
m. 

In  the  central  nervous  system  the  two  incoming  currents  are 
brought  together  by  the  organized  paths  in  this  system.  They  then 
pass  through  the  motor  centers  and  are  distributed  in  such  a  way 
as  to  reenforce  s ;  that  is,  one  of  the  muscular  tensions  which  was 
present  from  the  first. 

We  commonly  say  that  the  sensor)'  impressions  caused  the 
reaction  s.  What  really  happened  is  that  certain  attributes  of  the 
object  aroused  the  sensor)'  impulses  which  in  turn  were  fused  by 
the  individual's  inner  nervous  organization  in  such  a  way  that  the 
reaction  s  of  which  the  individual  was  all  along  capable  was  brought 
into  emphatic  play. 

Consciousness  does  not  reflect  merely  the  entrance  of  sensor)* 
impressions  into  the  nervous  system ;  if  it  did,  vision  and  touch 
from  the  same  object  would  remain  as  unrelated  facts  in  expe- 
rience. Consciousness  includes  the  incoming  impressions,  but  em- 
phasizes th'e  fact  that  they  are  combined  on  the  way  to  a  common 
center  of  motor  discharge.  Consciousness  is  related  to  the  central 
organization  and  thus  to  the  reactions  of  the  individual  quite  as 
much  as  to  the  incoming  sensory  impressions. 

We  find  ourselves,  accordingly,  in  harmony  with  the  conclusion 
to  which  our  general  study  of  the  nervous  system  led  us.  We 


EXPERIENCE  AND   BEHAVIOR  145 

found,  it  will  be  remembered,  that  the  indirect  centers  of  the  cere- 
brum —  that  is,  the  organizing  areas  of  the  brain  —  are  the  parts  of 
greatest  importance  to  the  student  of  conscious  life.  We  now  see 
that  this  means  that  the  fusion  of  sensory  impressions  on  the  way 
to  their  discharge  as  motor  processes  is  the  physical  fact  most 
closely  related  to  consciousness.  Consciousness  does  not  depend 
primarily  on  the  character  of  sensory  impressions  or  of  muscular 
contractions,  but  is  determined  largely  by  the  organizing  processes 
which  follow  the  reception  of  sense  impressions  and  their  discharge 
into  motor  channels. 


CHAPTER  VII 

CERTAIN  KfM>  \\n\T\L  ATTITUDES 

Reactions  toward  objects  and  reactions  away  from  objects. 
I  f  we  consider  the  simplest  forms  of  animal  behavioi 
find  that  they  divide  into  two  classes  ;  there  are,  on  the  one 
side,  activities  in  which  the  animal  seeks  those  ends  whit  h 
gratify,  such  as  food,  warmth,  and  contact  with  its  own 
kind  ;  and  there  are,  on  the  other  side,  activities  in  whirh 
the  animal  seeks  to  escape  from  harm.  The  simplest 
animal  forms  show  these  two  types  of  behavior,  as  has 
been  pointed  out  in  an  earlier  chapter  (Fig.  2,  and  p. 
The  human  infant  shows  the  same  fundamental  forms  of 
behavior. 

Pleasure  and  displeasure.  There  are  in  conscious  life 
fundamental  attitudes  corresponding  to  these  two  types  of 
behavior.  We  like  what  we  seek,  and  our  attitude  toward 
impressions  arousing  this  type  of  reaction  is  described  by 
the  common  word  "  pleasure."  What  we  try  to  avoid 
arouses  within  us  the  opposite  attitude,  or  one  of  dis- 
pleasure. In  popular  language  the  antithesis  commonly  ex- 
pressed is  between  pleasure  and  pain.  Pain  is,  in  reality, 
a  very  intense  form  of  tactual  sensation  which  comes  from 
the  injury  of  bodily  tissues.  Such  sensations  stir  up  the 
most  violent  efforts  on  the  part  of  the  organism  to  throw 
off  the  offending  object ;  hence  the  common  failure  to  dis- 
tinguish between  the  sensory  part  of  the  experience  and  the 
attitude  of  displeasure. 

Pleasure  and  displeasure  appear  in  a  great  variety  of 
particular  forms.  Thus,  when  the  body  is  taking  in  food, 

146 


CERTAIN  FUNDAMENTAL  ATTITUDES         147 

there  is  a  series  of  activities  which  are  among  the  most 
gratifying  that  the  individual  can  experience.  The  nervous 
system  is  prepared  to  respond  positively  to  the  stream  of 
sensory  stimulations  which  come  to  the  organs  of  taste  and 
smell  from  objects  suited  to  the  organism.  The  organism 
is  coordinated  in  its  internal  behavior  to  receive  the  objects 
that  gratify,  and  the  nervous  activity  accompanying  the 
whole  process  is  of  the  most  favorable  type.  Again,  the 
comfort  of  sitting  in  a  warm,  bright  room  is  different  from 
that  of  taking  food ;  but  here,  as  in  taking  food,  all  the 
body's  reactions  are  harmonious  and  favorable,  and  in  a 
general  way  the  attitude  of  the  individual  is  of  the  same 
quality  as  that  which  appears  in  the  act  of  taking  food. 

Displeasure  exhibits  in  like  manner  different  forms.  The 
odor  of  some  object  may  be  disgusting  because  it  throws 
the  body  into  violent  activities  aimed  at  rejection.  In  the 
same  general  way,  one  tries  to  get  away  from  a  glaring 
light.  In  both  cases  the  action  is  one  of  self-protection, 
and  the  mental  attitude  is  one  of  displeasure. 

There  are  negative  conditions  as  well  as  positive  which 
produce  the  typical  attitudes  of  pleasure  and  displeasure. 
Thus  the  organism  which  is  deprived  of  food  or  of  waVmth 
will  make  strenuous  efforts  to  correct  the  deficiency,  and 
the  attitude  which  accompanies  these  efforts  may  be  of  the 
most  intense  displeasure.  In  like  manner  the  relief  which 
comes  with  the  escape  from  impending  danger  may  give 
the  highest  satisfaction. 

Cultivated  feelings.  In  general,  it  may  be  said  that  what- 
ever impression  promotes  the  normal  reaction  of  the  organ- 
ism is  accompanied  by  pleasure  ;  whatever  defeats  normal 
behavior  or  arouses  protective  recoil  is  unpleasant. 

The  history  of  psychology  is  full  of  efforts  to  classify 
pleasures  and  displeasures  and  to  show  the  exact  relations 
of  these  phases  of  experience  to  sensations.  The  difficulty 
in  reaching  any  final  classification  is  that  with  the  progress 


148 

of  individual  development  new   types  of  pleasure  and  dis- 
pleasure arise  just  in  the  degree  in  which  one  learns  to  seek 
or  reject  objects.    Each  human  being  starts  with  an  in- 
.  to  seek  certain  ends  and  reject  others, 
these  fundamental  likes  and  dislikes  he  adds  others  con- 
nected with  his  mature  cxpct:  Thus  each  of  us  sets 
up  certain  property  rights.    One  likes  to  have  at  hand,  sub- 
ject to  his  instant  command,  certain  conveniences.    If  one 
cannot  find  his  pen  or  his  tennis  racket,  he  is  sometimes 
thrown  into  a  state  of  distress  hardly  less  violent  than  that 
exhibited  by  the  infant  who  cannot  find  food.   The  tasu 
pens  and  tennis  rackets  are  acquired  by  the  use  of  • 
instruments,  they  are  in  no  sense  of  the  word  in- 
but  once  the  habits  of  use  are  organized  they  demand  the 
opportunity  for  expression,  and  satisfaction  or  its  opj 
will  attach  to  their  presence  or  absence. 

Fear  as  a  typical  emotion.  One  of  the  significant  exam- 
ples of  a  strong  negative  attitude  appears  in  the  experience 
which  we  call  fear.  \Ve  sometimes  speak  of  the  instir 
fear.  There  is,  indeed,  in  every  animal  a  strong  tendency 
to  run  away  from  everything  that  is  strange  or  large  or 
overstimulating.  So  delicately  is  the  nervous  system  poised 
to  protect  the  individual  that  when  a  strange  or  violent 
stimulation  comes  to  the  organs  of  sense  there  follows  an 
overstimulation  of  all  the  active  organs.  This  overstimula- 
tion  is  accompanied  by  an  inner  state  of  agitation.  The 
inner  agitation  confuses  all  thought  and  is  a  source  of 
displeasure  just  because  the  inner  chaos  is  ineffective  and 
incapable  of  arousing  any  coordinated  forms  of  expression. 
The  frightened  man  is  proverbially  not  intelligent.  The  fact 
is  that  the  frightened  man  is  internally  in  a  commotion,  and 
his  mind  is  blurred  because  he  cannot  cope  with  the  situa- 
tion. His  motor  processes  are  stalled  or  incobrdinated,  and 
his  attitude  is  disagreeable  and  increasingly  so  the  longer 
his  inability  to  deal  with  the  situation  continues. 


CERTAIN  FUNDAMENTAL  ATTITUDES         149 

Fear  is  a  form  of  displeasure,  but  unique  as  contrasted 
with  the  displeasure  of  rejecting  an  unacceptable  taste  or 
color.  Yet  so  general  in  character  is  fear  that  it  may  attach 
to  any  violent  form  of  excitement.  Fear,  which  has  been 
described  as  the  most  primitive  form  of  human  displeasure, 
does  not  disappear  with  modern  life,  but  tends,  rather,  to 
become  more  general  and  more  intense.  To  be  sure,  it 
attaches  to  new  objects  as  man  overcomes  his  first  enemies, 
but  it  is  one  of  the  most  common  attitudes  of  life.  Primi- 
tive man  was  afraid  of  an  eclipse ;  modern  man  is  not. 
Modern  man  is,  however,  thrown  into  a  panic  by  an  earth- 
quake because  it  runs  counter  to  all  his  established  forms 
of  behavior  to  have  the  solid  earth  under  his  feet  begin  to 
rock.  The  earth  has  been  the  base  of  all  behavior,  and 
one  is  at  a  loss  to  control  behavior  when  this  base  of  action 
changes.  Not  only  so,  but  modern  life  contains  new  terrors 
which  were  not  known  in  earlier  stages  of  civilization.  The 
embarrassment  of  appearing  in  public  is  one  of  the  new 
inventions  of  civilization.  That  there  is  much  superfluous 
excitement  in  this  case  is  realized  by  everyone  whose  knees 
have  trembled  and  whose  pulse  has  gone  to  one  hundred 
and  thirty.  The  mental  distress  of  the  situation  comes 
from  the  fact  that  these  forms  of  reaction  are  ineffective, 
indeed  are  quite  absurdly  in  the  wrong  direction. 

How  to  change  the  attitude  of  fear.  The  common  advice 
given  to  children  to  go  directly  and  investigate  any  object 
of  which  they  are  afraid  is  in  general  good.  The  going 
and  the  handling  of  an  object  give  the  individual  a  form  of 
reaction  which  is  coordinated  and  normal  as  a  substitute  for 
the  agitation  and  for  the  ineffective  inner  agitation. 

Fear  an  emotion  of  complex  beings.  Kipling  has  made  a 
tale  out  of  the  evolution  of  fear.  The  stupid,  slow-going 
bullocks  in  a  night  stampede  in  the  camp  tell  how  they 
fight  and  criticize  the  elephant  as  a  coward.  The  bullocks 
tell  how  they  draw  the  guns. 


150  I'SY<    IK  'I  OOV 

"Then  we  tug  the  big  gun  all  together  —  Hey*  —  Hullak I 

;h .'   //////•;// .'   //'<-  d<>  m»t  climb  like  c-ats  nor  run  like  calves. 
We  go  across  the  level  plain,  twenty  y«»kc  of  us,  till  we  ar< 
yoked  again,  and  we  graze  while  the  big  guns  talk  across  the  pl.un 
to  some  town  with  mud  walls,  and  pieces  of  the  wall  fall  out,  and 
the  dust  goes  up  as  though  many  cattle  were  coming  home." 

'h  !   Ami  you  choose  that  time  for  grazing  do  you  ?  "  said  the 
young  mule. 

That  time  or  any  other.    Hating  is  always  good    We  eat  till 
kcd  up  again  and  tug  the  gun  back  to  wl  Tails 

iiting  for  it.    Sometimes  there  are  big  guns  in  the  city  that 

speak  back,  and  some  of  us  arc  killed,  and  then  there  is  all  the 

more  grazing  for  those  that  are  left.    Thi-  -nothing  but 

None  the  less,  Two  Tails  is  a  great  coward.    That  is  the 

proper  way  to  fight.    We  are  brothers  from  Hapur.    Our  father 

i  sacred  bull  of  Shiva.    We  have  spoken."  .  .  . 

Whereupon  the  elephant  who  has  heard  himself  accused 
of  being  a  coward  replies  as  follows : 

"  Well,"  said  Two  Tails,  rubbing  one  hind  leg  against  the  other, 
exactly  like  a  little  boy  saying  a  piece,  "  I  don't  quite  know  whether 
you  'd  understand." 

"  We  don't,  but  we  have  to  pull  the  guns,"  said  the  bullocks. 

"  I  know  it,  and  I  know  you  are  a  good  deal  braver  than  you 
think  you  are.  Hut  it 's  different  with  me.  My  batten  captain 
called  me  a  Pachydermatous  Anachronism  the  other  day." 

"  That 's  another  way  of  fighting,  I  suppose  ?  "  said  Hilly,  who 
was  recovering  his  spirits. 

"  }',>u  don't  know  what  that  means,  of  course,  but  I  do.  It 
means  betwixt  and  between,  and  that  is  just  where  I  am.  I  can 
see  inside  my  head  what  will  happen  when  a  shell  bursts ;  and  you 
bullocks  can't." 

"  I  can,"  said  the  troop-horse.  "  At  least  a  little  bit.  I  try  not 
to  think  about  it." 

"  I  can  see  more  than  you,  and  I  do  think  about  it.  I  know 
there  's  a  <;reat  deal  of  me  to  take  care  of.  and  I  know  that  nobody 
knows  how  to  cure  me  when  I'm  sick.  All  they  can  do  is  to  stop 
my  driver's  pay  till  I  get  well,  and  I  can't  trust  my  driver." 


CERTAIN  FUNDAMENTAL  ATTITUDES         151 

Two  Tails  stamped  his  foot  till  the  iron  ring  on  it  jingled. 
"Oh,  I'm  not  talking  to  you.  You  can't  see  inside  your  heads." 

"  No.  We  see  out  of  our  four  eyes,"  said  the  bullocks.  "  We 
see  straight  in  front  of  us." 

"  If  I  could  do  that  and  nothing  else  you  would  n't  be  needed 
to  pull  the  big  guns  at  all.  If  I  was  like  my  captain  —  he  can  see 
things  inside  his  head  before  the  firing  begins,  and  he  shakes  all 
over,  but  he  knows  too  much  to  run  away  —  if  I  was  like  him  I 
could  pull  the  guns.  But  if  I  were  as  wise  as  all  that  I  should  never 
be  here.  I  should  be  a  king  in  the  forest,  as  I  used  to  be,  sleeping 
half  the  day  and  bathing  when  I  liked.  I  have  n't  had  a  good  bath 
for  a  month."1 

Fear  and  pathology.  The  physicians  who  deal  with  mental 
pathology  report  fear  as  the  most  common  form  of  modern 
mental  breakdown.  The  fears  of  our  present-day  lives  are 
not  the  fears  of  the  forest,  but  they  are  subtle  and  disorgan- 
izing. They  cannot  be  classified  merely  as  unpleasurable 
agitations  ;  they  arise  from  violent  and  disorganizing  forms 
of  disrupted  nervous  activity. 

Parental  love  and  altruism.  Parental  love  for  offspring 
has  been  described  as  an  instinct.  Here  again  we  have  to  do 
with  a  complex  attitude  which  can  be  understood  only  when 
one  studies  the  forms  of  behavior  which  the  parent  culti- 
vates. Nature  has  so  organized  the  higher  animals  that  they 
protect  their  young.  Gradually  the  compass  of  these  protec- 
tive activities  widens  until  a  mother  may  be  wholly  absorbed 
in  the  care  of  her  offspring.  The  evolution  of  many  of  the 
complex  forms  of  social  life  is  directly  traceable  to  the 
efforts  of  parents  to  care  for  their  young.  Fiske,  in  a.  very 
interesting  essay  on  the  evolution  of  altruism,  has  shown 
how  the  care  of  the  child  has  brought  into  the  world  a 
mental  attitude  wholly  beyond  animal  instinct.  Among  primi- 
tive animals  behavior  was  at  first  aimed  at  self-preservation, 
With  the  growth  of  parental  solicitude  has  come  a  form  of 

1  Rudyard  Kipling,  The  Jungle  Book,  pp.  284,  287-289.  The  Century 
Company,  1914. 


152  PSYCHOLo 

behavior   which    is  at   times  so  strong  that  a  mother  will 

uid  with  supreme  w  :\  under;; 

kinds  of   hardships   in  doin-   l'..r   her  child   th;it  which   will 
protect  him  and  prom  ;        in  turn,  as  1 

points  out.   leads  to  other  altruistic  acts  and  attitudes  cm- 
a^   companions   and   acquaintances.    Cultivated    modes 
of  hehavior  may,  as  in  th  tC  mental  values  which 

are   entirely    unintelligible  if  we  think  only  of   individual 
protection. 

Anger.  Anger  is  a  mental  attitude  which  accompanies  an 
effort  to  throw  off  restraint.  There  may  be  blind  ra^ 
which  the  angry  man  beats  aimlessly  at  everything  which 
is  within  reach,  or  there  may  lx-  the  subtle  studied  anger 
which  step  by  step  proceeds  to  the  final  attack.  Watson  has 
called  attention  in  his  experiments  with  infants  to  the  fact 
that  a  new-born  infant  will  be  thrown  into  a  rage  if  its  move- 
ments are  restricted.  Hold  an  infant's  head  perfectly  still 
and  anger  will  appear. 

Other  emotions.  The  list  of  attitudes  cou!3  be  indefinitely 
amplified.  Jealousy,  shame,  bashfulness,  surprise,  awe,  rever- 
ence are  all  names  of  special  attitudes  which  grow  out  of  the 
efforts  of  the  individual  to  deal  in  some  active  way  with  the 
world  about  him.  They  all  reduce  in  the  last  broad  analysis 
to  pleasurable  and  unpleasurable  experiences,  but  this  gen- 
eral classification  obliterates  the  distinctions  which  can  be 
productively  retained  if,  instead  of  merely  trying  to  classify 
attitudes,  one  develops  the  formula  of  explanation  which  in- 
cludes all  the  rich  variety  of  human  reactions  to  a  complex 
environment. 

Emotions  as  fundamental  forms  of  experience.  The  fore- 
going paragraphs  will  be  recognized  by  every  reader  as  deal- 
ing with  that  aspect  of  experience  which  has  always  been 
referred  to  under  the  terms  "  feeling  "  and  "  emotion."  The 
importance  of  the  feelings  must  not  be  underestimated  by 
the  student  of  human  life.  Sensory  impressions  are  of 


CERTAIN  FUNDAMENTAL  ATTITUDES         153 

significance  only  as  they  arouse  attitudes.  It  is  the  attitude 
which  reveals  the  individual ;  and  the  attitude  in  turn  is 
the  result  of  organized  modes  of  response.  The  paths  in 
the  nervous  system  along,  which  sensory  impressions  travel 
to  their  motor  discharge,  the  central  agitations  which  arise 
in  the  nervous  system  as  the  sensory  impressions  are  com- 
bined and  recombined,  condition  experience  in  a  way  that 
cannot  be  overlooked  by  one  who  is  interested  in  human 
nature.  Human  nature  is  what  it  is,  not  because  of  the 
impressions  which  come  to  the  eye  and  ear,  but  because  of 
the  responses  which  are  worked  out  through  the  central 
nervous  system. 

Higher  forms  of  experience  as  related  to  behavior.  Thus 
far  we  have  been  showing  in  a  general  way  that  attitudes  are 
related  to  reactions.  The  full  significance  of  reactions  for 
individual  mental  life  will  become  increasingly  apparent  as 
the  subsequent  discussions  canvass  the  different  types  of 
organized  behavior  of  human  beings.  We  shall  discover  that 
there  are  lower  forms  of  behavior  and  lower  types  of  mental 
attitude,  and  that  the  development  of  higher  forms  of  expe- 
rience involves  the  development  of  higher  and  more  complex 
forms  of  reaction.  Indeed,  the  rest  of  our  study  will  be  a 
study  of  human  reactions  and  accompanying  experiences. 
The  remainder  of  this  chapter  will  be  devoted  to  a  study  of 
some  of  the  more  primitive  and  more  fundamental  attitudes. 

Feelings  of  organic  type.  Many  of  the  most  primitive 
adjustments  of  the  motor  organs  of  the  body  are  internal 
adjustments  and  have  to  do  with  the  well-being  of  the  body 
itself.  Accompanying  these  there  is  at  all  times  a  background 
of  feeling  which  colors  all  experience.  There  is  the  buoyant 
feeling  which  one  enjoys  when  he  begins  life  on  a  bright, 
clear  day  and  the  feeling  of  utter  depression  of  a  foggy  day. 
The  reasons  for  such  feelings  can  be  understood  from  such 
experiments  as  the  following.  The  muscles  of  a  waking 
person  are  always  under  tension.  Let  the  tension  be  tested 


154  I  >VCHOL( 

under  conditions  of  varying  stimulation.  The  individual  can 
be  asked  t«.  show  his  muscular  strength  by  means  of  a 
dynamometer  or  simple  apjwra  measuring  the  strength 

of  the  grip.  If  such  a  test  is  made-  in  a  dark,  silent  room, 
and  a  second  test  with  the  same  jx-rson  is  subsequently  made 
in  a  room  which  is  well  lighted  and  full  of  sound,  it  will  be 
found  th.it  more  work  can  be  done  in  the  latter  case  than 
in  the  former.  The  additional  light  and  sound  have  rojscd 
the  nervous  and  muscular  tone  to  a  higher  level,  so  that 
when  the  movement  is  undertaken,  the  motor  impulses  to 
the  muscles  have  the  advantage  of  the  higher  initial  tension. 
It  need  hardly  be  pointed  out  that  the  conscious  experience 
of  the  reactor  is  different  in  the  two  cases  descriln-d. 

Flexor  and  extensor  movements  related  to  characteristic 
attitudes.  A  second  exjx-rimcnt  is  as  follov.  a  person 

be  trained  to  make  an  outward  swing  of  the  arm  with  his 
eyes  closed.  If  a  number  of  measurements  are  made,  it  is 
possible  to  determine  with  great  accuracy  the  range  of  error 
of  these  movements.  If  the  movements  are  made  when  the 
senses  are*  in  a  quiet  condition  without  special  stimulation, 
they  will  not  be  of  exactly  the  same  length  in  successive 
trials,  but  they  will  not  differ  widely  from  each  other.  After 
these  preliminary  tests,  let  the  reactor  be  given  a  strong 
bitter  or  sweet  taste  sensation.  The  result  will  be  that  the 
arm,  in  common  with  the  other  muscular  organs  of  the  body, 
will  take  on  a  different  tension.  The  tension  in  the  case  of 
a  sweet  stimulus  will  tend  to  favor  outward  expansive  move- 
ments ;  the  tension  in  the  case  of  a  bitter  stimulus  will  tend 
to  favor  inward  contracting  movements.  The  result  will  be 
increased  movements  in  these  directions,  even  when  tin- 
person  tries  to  move  as  before.  In  short,  bitter  tastes  and 
sweet  tastes  result  in  inner  muscular  tensions. 

Changes  in  circulatory  movements  as  parallels  of  con- 
scious changes.  One  of  the  systems  of  muscles  which  is 
most  noticeably  affected  by  any  change  in  stimulation  is  the 


CERTAIN  FUNDAMENTAL  ATTITUDES         155 

system  in  control  of  the  circulatory  activities.  If  a  recording 
apparatus  is  so  adjusted  as  to  give  a  record  of  the  rate  and 
intensity  of  the  heartbeat,  it  will  be  found  that  there  is  a 
constant  rise  and  fall  in  the  rate  and  intensity  of  circulatory 
activity.  The  rise  and  fall  can  be  shown  in  striking  degree 
by  using  in  the  course  of  the  experiment  some  marked 
stimulus,  but  even  when  no  special  stimulus  is  applied  to 
the  organs  of  sense,  there  is  a  continuous  flux  and  change 
in  the  circulatory  activities.  Here,  again,  it  is  unnecessary 
to  point  out  that  consciousness  is  constantly  changing,  and 
that  it  changes  most  noticeably  with  the  application  of  an 
external  stimulus.  Indeed,  so  close  is  the  relation  between 
activity  and  sensation  in  this  latter  case  that  it  may  safely 
be  said  that  there  is  never  a  change  in  sensory  excitation 
without  a  parallel  change  in  circulatory  activity. 

Disappointment  as  negative  emotion.  Another  case  of  this 
internal  type  of  reaction  is  to  be  found  in  the  fact  that  the 
body  is  from  time  to  time  thrown  back  on  itself.  For  ex- 
ample, one  starts  to  go  about  some  ordinary  task  and  finds 
that  the  energy  he  had  mustered  up  for  the  work  cannot 
be  used  because  he  cannot  find  the  tools  for  his  work.  The 
energy  which  was  to  be  expended  in  doing  the  work  is 
thrown  back  into  the  body,  and  the  inner  agitation  is -accom- 
panied by  what  we  call  in  ordinary  life  disappointment. 
Here  the  nervous  agitation  is  in  the  nature  of  a  disagree- 
able stopping  of  movements  which  were  originally  directed 
outward  but  have  suddenly  been  thrown  inward. 

External  attitudes.  There  are  many  forms  of  reaction 
with  an  outward  turn  which  are  less  emotional  in  character 
because  the  content  of  experience  is  less  personal.  We  use 
in  such  cases  terms  like  "  satisfaction  "  or  "  interest."  The 
man  who  makes  a  good  stroke  in  golf  enjoys  it  and  gets 
satisfaction  out  of  it,  but  he  does  not  have  so  intense  a  per- 
sonal experience  as  he  has  when  he  makes  a  bad  stroke. 
The  successful  performance  issues  in  a  series  of  impressions 


156 

and  ideas  rich  in  content ;  the  unsuccessful  act  arouses  vio 
Irru  internal  circulatory  reactions  and  unpleasant  tensions  of 
all  the  muscles  of  the  body. 

Attention  as  an  attitude.    There  is  one  very  general 
with  regard  to  reactions  to  external  ol  1  he  individual 

either  turns  toward  an  object,  looking  toward   it,  reaching 
out  for  it,  and  bracing  himself  to  deal  with  it,  or  els« 
individual  turns  away  from  an  impression,  neglecting 
actually  rejecting  it.    The  attitude  side  of  these  various  f 
of  response  is  described  by  a  general  term,  —  the  term 
tention."    One  attends  to  an  object  «>r  is  interested  in  it,  or 
in  the  other  case  he  neglects  it  or  exhibits  a  lack  of  interest 
or  concentration  on  it. 

Experiment  to  demonstrate  tension.  Attention  is  the  atti- 
tude of  reacting  to  an  impression.  The  physical  symptoms 
of  attention  are  well  known  ;  there  is  the  strained  muscle, 
the  fixed  gaze,  the  leaning  forward  to  catch  the  new  im- 
pression which  will  in  turn  arouse  more  action.  Much  of 
the  reaction  exhibited  in  a  state  of  attention  is  for  the  pur- 
pose of  focusing  the  organs  of  sense  on  the  source  of  the 
sensations.  The  infant  is  constantly  trying  to  get  into  contact 
with  everything  for  the  purpose  of  getting  more  impressions. 

All  through  life  there  is  a  tendency  to  move  in  the  direc- 
tion of  an  object  which  is  in  the  center  of  attention.  This 
is  shown  experimentally  as  follows :  Let  the  person  to  be 
tested  rest  his  hand  on  some  recording  apparatus  which 
moves  with  very  little  friction.  A  board  suspended  by  a 
long  string  and  carrying  a  tracer  at  one  end  is  a  very  good 
apparatus  with  which  to  make  this  experiment.  Now  let  the 
subject  close  his  eyes  and  think  intently  of  his  hand.  The 
recording  point  will  make  short  excursions  back  and  forth, 
for  there  is  no  such  condition  as  one  of  absolute  rest  of  the 
hand  muscles,  and  under  the  conditions  arranged  very  slight 
movements  are  sufficient  to  produce  a  record.  After  noting 
the  range  and  kind  of  movement  which  will  be  made  when 


CERTAIN  FUNDAMENTAL  ATTITUDES          157 


one  thinks  as  steadily  as  he  can  of  the  hand,  let  the  reactor 
think  intently  of  some  object  at  his  right  or  left.  Let  him 
make  an  imaginary  journey  or  draw  in  imagination  some 
simple  geometrical  figure.  The  result  will  be  that  the  move- 
ments of  the  recorder  will  be  radically  changed.  There  will 
often  be  a  tendency  for  the 
new  movement  to  take  on 
a  form  directly  related  to 
the  new  subject  of  thought, 
but  in  any  case  there  will 
be  a  change  from  the  type 
of  movement  which  appears 
when  attention  is  concen- 
trated on  the  hand,  even  if 
the  form  of  the  new  move- 
ment is  not  directly  trace- 
able to  the  new  experience. 
Fig.  45  shows  the  records 
of  involuntary  hand  move- 
ments of  the  type  described. 

Various  forms  of  atten- 
tion. Such  an  experiment 
reveals  the  reason  for  the 
use  of  words  like  "atten- 
tion," "concentration,  "and 
"  interest  "  as  partial  syno- 
nyms. The  focusing  of  ac- 
tivity on  an  object  arouses 
an  emotional  attitude;  hence  we  are  justified  in  treating 
attention  and  feeling  as  closely  related. 

The  explanation  of  attention  will  perhaps  be  understood 
most  readily  through  consideration  of  those  negative  cases 
where  the  individual  neglects  the  objects  about  him,  as 
when  we  do  not  count  the  number  of  windows  in  a  room. 
Here  the  impression  goes  into  the  nervous  system,  but 


FIG.  45.    Involuntary  hand  movements 
made  by  the  right  and  left  hands  of 
an  observer  who  is  thinking  of  a  build- 
ing situated  in  front  of  him 

The  hands  begin  at  the  two  points  A,  A  ; 
the  building  lies  in  the  direction  of  the 
movement  which  is  here  represented  by 
the  downward  extension  of  the  two  lines. 
(After  Jastrow) 


158  P>\»  HOLOG1 

is  not  made  a  center  «l  any  direct  reaction.  The  impres- 
sion is  lost  in  the  mass  «»f  rraitions;  it  is  not  individual- 
ized. We  say  that  it  does  not  receive  attention  or  arouse 
interest. 

Sympathy  with  fellow  beings.  Such  general  comments 
on  attention  lead  to  the  treatment  of  special  cases.  When- 
ever we  see  a  fellow  being  trying  to  do  something,  we 
to  share  in  the  activity.  The  man  who  is  lifting  a  weight 
arouses  all  who  see  him  to  like  effort.  The  singer  who  is 
taking  a  high  note  will  be  followed  by  his  audience  with 
sympathetic  muscular  efforts.  Attention  in  these  cases 

issues  in  sympathetic 
action. 

Sympathy  involved 
in  all  recognition  of 
objects.  Sympath 
tends  far  beyond  one's 
fellow    beings.      All 


Fir,  46.    Uruesthetical  balance 

The  two  black  .pou  are  evident*  not  well  ,up-      ^  WC  ™}U<*C  untk'r 
ported  by  the  fulcrum  shown  in  the  figure.    There       the    term        :csthetical 


"  '  "•*"  IJSX1'3±r  """"  *     appreciation"  belong, 

under  the  same  head- 

ing. For  example,  let  an  observer  look  at  an  unsymmetrical 
drawing,  such  as  that  shown  in  Fig.  46.  The  long  horizon- 
tal line  with  the  black  figures  at  its  ends  is  not  well  sup- 
ported at  the  fulcrum  given  in  the  figure.  The  feeling  of 
lack  of  balance  in  this  figure  is  directly  related  to  an  active 
tendency  on  the  part  of  the  observer  to  offer  his  support 
to  the  line  as  it  carries  the  larger  figure,  and  this  tendency 
to  action  which  is  inspired  by  the  figures  is  accompanied  by 
a  distinctly  disagreeable  experience,  because  it  is  continually 
ineffective  in  producing  its  purpose.  Examples  of  the  feel- 
ing of  pleasure  which  comes  from  harmonious  complexes 
can  be  derived  from  the  study  of  Greek  architectural  forms. 
The  Greeks  recognized  the  fact  that  a  column  with  perfectly 


CERTAIN  FUNDAMENTAL  ATTITUDES         159 

straight  lines  is  not  an  aesthetic  object.  Such  a  column  always 
seems  to  be  weaker  in  the  center  than  at  the  extremities, 
where  there  are  larger  masses  of  matter.  There  is  therefore 
a  feeling  of  unrest  inspired  in  the  observer  lest  the  column 
should  give  way  in  the  center,  where  the  tension  is  great 
and  the  material  relatively  reduced.  The  Greeks,  accord- 
ingly, made  their  columns  larger  in  the  middle  than  at  the 
extremities,  and  the  result  was  that  the  observer,  seeing  the 
reinforcement  at  the  critical  part  of  the  column,  has  a  feel- 
ing of  satisfaction  rather  than  of  unrest  in  looking  at  the 
lines.  The  term  "sympathy"  is  not  used  here  as  a  figure 
of  speech.  There  is  a  real  muscular  tension  involved  in 
observing  a  column  lifting  a  weight,  and  through  this 
tension  the  observer  enters  into  the  situation  as  an  active 
participator. 

Illusion  due  to  muscular  tension.  The  presence  of  mus- 
cular tensions  related  to  perception  of  weight  can  be  demon- 
strated in  certain  special  cases.  If  one  prepares  two  blocks  of 
exactly  the  same  objective  weight  but  of  very  different  sizes, 
so  that  one  is,  for  example,  about  a  foot  cube  and  the  other 
three  inches  cube,  the  observer  will  find  when  he  comes  to 
lift  these  two  blocks  that  the  smaller  block  seems  decidedly 
heavier  than  the  larger  one.  The  explanation  of  this  fact 
is  to  be  found  in  the  muscular  preparation  of  the  observer 
when  he  first  looks  at  the  two  blocks.  The  visual  expe- 
rience from  the  small  block  leads  him  to  prepare  to  do  a 
small  amount  of  work  in  lifting  it,  while  the  visual  impres- 
sion of  the  larger  block  is  recognized  in  terms  of  a  totally 
different  kind  of  muscular  organization,  which  may  be  de- 
scribed by  saying  that  the  observer  prepares  to  do  more 
work  in  lifting  the  large  block  than  he  prepares  to  do  in 
lifting  the  smaller  one.  When,  with  these  differences  of 
preparation,  the  observer  lifts  the  two  blocks,  he  finds  that 
his  preparation  does  not  coincide  with  the  demands  forced 
upon  him  through  his  direct  contact  with  the  blocks.  There 


160  IM<  liOLOGY 

hereforc,  a   sharp  disagreement   between    the  oiigina! 
preparation  based  <>n  vision  and  the  subsequent  cxpen 
dependent  on  touch.    This  disagreement  expresses  itself  in 
the  form  of  an  illusion  with  regard  to  weight.    This  ilh 
•I    due   t«»   sensations    merely,   but    involves  also    pi 
ration  for  active   resjx>nse.    There  can   be  no   doubt   that 
whenever  one  looks  at  any  ordinary  object  of  manageable 
he  prepares  to  lift  it.     The  preparation  i  ;n  an 

incipient  act,  and  thi  the  physiological   parallel  of 

an    important   phase  of  the  observer's    mental    process   of 
recognition. 

Such  muscular  tensions  common  to  many  experiences. 
This  illusion  of  weight  and  similar  facts  from  practical  life 
throw  much  light  on  the  nature  of  the  organization  which 
was  referred  to  when  it  was  stated,  in  discussing  the  aesthetic- 
attitude  toward  a  column,  that  one  sympathizes  with  the 
column  in  the  work  which  it  does  in  supporting  the  mate- 
rials placed  upon  it.  There  is  a  certain  direct  perceptual 
estimation  of  the  fitness  of  the  column  to  do  its  work. 
That  estimation  expresses  itself  immediately  in  the  mus- 
cular tension  which  is  aroused  in  the  observer  as  an  inte- 
gral part  of  the  process  of  recognition.  If  the  column  is 
inadequate,  the  observer  is  Ted  to  a  strained  attitude  of 
assisting  it ;  if  the  column  is  adequate  to  its  task,  the: 
an  attitude  of  satisfied  recognition. 

All  consciousness  a  form  of  sympathetic  attention.  Thus 
we  find  that  as  human  attitudes  become  more  complex  they 
are  something  more  than  feelings  or  emotions ;  they  include 
also  sympathies  and  discriminations  which  become  parts  of 
higher  intellectual  recognitions.  When  one  sympathises  with 
a  column,  it  is  not  a  mere  vague,  general  response  ;  it  is  a 
discriminating  response,  bringing  one  into  personal  relations 
to  the  outer  world.  In  all  the  higher  stages  of  mental 
development  one  knows  objects  through  one's  sympathies 
with  them. 


CERTAIN  FUNDAMENTAL  ATTITUDES         161 

The  discussion  of  attitudes  leads  us  thus  to  broad  con- 
clusions about  the  nature  of  consciousness.  Consciousness 
is  a  function  through  which  the  individual  attempts  to  put 
himself  in  harmony  with  the  outer  world.  He  translates 
the  world  into  terms  of  his  own  responses  and  thus  makes 
the  objects  outside  of  himself  a  part  of  his  own  inner  life. 
After  he  has  thus  taken  the  outer  world  into  his  mental 
life,  a  new  possibility  arises  —  that  of  carrying  back  into 
the  external  world  some  of  the  rearrangements  which  are 
first  worked  out  in  the  purely  subjective  sphere.  The  indi- 
vidual, by  first  fitting  himself  to  the  outer  world,  learns  how 
to  mold  the  outer  world  to  meet  his  inner  needs  and  desires. 

Attitudes  as  related  to  higher  processes  of  recognition. 
Psychology  must  study,  then,  those  attitudes  of  feeling  and 
sympathy  by  which  the  inner  world  absorbs  impressions  and 
makes  them  into  personal  experiences.  It  must  then  take 
up  the  higher  processes  through  which  inner  experience 
is  made  effective  in  controlling  the  world  from  which 
impressions  first  came. 


'  H AM  I-:R  vin 

COMBINATION  AND  ARRANGEMENT  OF 

\>\II<  '• 

Sensory  experience  always  complex.  The  arrival  of  a 
sense  impression  in  the  central  nervous  system  has  been 
shown  in  earlier  chapters  to  be  only  the  first  step  in  a 
series  of  processes  in  which  this  impression  is  combined 
with  other  sensor\f  impressions  and  carried  forward  to  a 
motor  discharge.  It  is  literally  true  that  no  sense  impres- 
sion ever  comes  into  the  central  nervous  system  alone. 
Kven  if  we  think  of  only  a  single  sense  organ,  we  realize 
that  it  sends  to  the  central  nervous  system  at  every 
moment  a  series  of  impressions  rather  than  a  single  sen- 
sation. Thus,  when  the  eye  is  stimulated  by  a  colored 
surface,  it  is  not  a  single  sensation  which  arrives  in  con- 
sciousness, but  a  whole  mass  of  sensations.  The  different 
parts  of  the  field  would  yield  various  shades  and  intensi- 
ties even  if  the  receiving  cells  in  the  eye  were  all  alike 
and  all  prepared  to  respond  with  absolute  uniformity  to 
the  stimulus.  But,  as  was  shown  in  the  chapter  on  sen- 
sation, various  parts  of  the  retina  are  different  in  their 
ability  to  receive  impressions.  The  result  is  that  a  colored 
surface  is  the  source  of  a  most  complex  series  of  sensations. 

The  matter  is  further  complicated  by  the  simultaneous 
arrival  of  impressions  through  different  senses.  Thus  we 
not  only  see  a  surface,  we  also  touch  it  and  may  smell 
it  or  hear  it  vibrate.  At  any  given  moment  there  are 
impressions  reaching  the  senses  not  from  a  single  object 
alone  but  from  various  objects.  As  we  look  at  a  colored 

i6a 


COMBINATIONS  OF  SENSATIONS  163 

surface  we  receive  touch  sensations  from  contact  with  our 
clothing  and  from  the  floor  on  which  we  stand  ;  we  hear 
sounds  from  the  next  room  and  breathe  in  odors  which 
have  no  relation  to  the  colored  surface. 

Sensation  combinations  or  fusions.  In  the  midst  of  all 
this  world  of  sensations  there  must  be  selection  and  com- 
bination. The  individual  works  out,  in  the  interests  of 
practical  life,  certain  units  of  experience  in  which  sensa- 
tions are  fused  with  each  other  and  distinguished  from 
the  rest  of  the  world.  For  example,  one  sees  an  orange. 
What  he  really  sees  is  a  complex  background  in  the  midst 
of  which  there  is  a  little  patch  of  orange  shade.  He  gets 
a  mass  of  odors,  but  attaches  a  particular  aroma  to  the 
particular  patch  of  color.  He  is  able,  in  the  course  of 
this  attention  to  his  experience,  to  recognize  that  the  color 
and  the  aroma  are  nearer  his  right  hand  than  his  left. 
What  he  has  done  in  thus  fusing  a  group  of  sensations 
and  locating  the  fused  group  on  the  right  is  designated 
in  technical  psychological  language  by  the  term  "  percep- 
tion." One  perceives  objects ;  that  is,  one  recognizes  cer- 
tain groups  of  sensations  as  belonging  together  and  as 
different  from  the  rest  of  the  world. 

Space  not  a  sensation,  but  a  product  of  fusion.  In  the 
process  of  perceiving  the  world  the  individual  develops 
certain  types  of  conscious  experience  which  must  be  dis- 
tinguished from  sensations.  Space  is  such  a  product  of 
organized  experience.  Space  results  from  the  fact  that 
sensations  take  on  what  we  may  call  "  togetherness."  To- 
getherness is  a  product  of  fusion.  The  counterpart  of 
togetherness  is  separateness.  The  perceived  orange  is  dis- 
tinguished from  other  objects.  The  whole  complex  of 
togetherness  and  separateness  ultimately  gets  arranged  into 
a  general  map  or  system.  In  this  system  there  ultimately 
comes  ^o  be  a  right  and  left,  an  up  and  down.  The  world 
is  now  recognized  as  arranged  in  order. 


!'>Y<    1 

Tactual  space  as  a  simple  example  of  fusion.    One  of 

UK-  e.irln  :  iuuMU.il  MOM   dealt 

with    the    spatial    arran-i-ment   of   tactual  In 

hU   effort    to   find   som;-    method   of   :  -ivity 

of   the-   skin.    Weber    measured    tin-    distances   which    must 
lie  bv-tween  two  stimulated  jxiints  <MI   tin-  skin  in  diff* 
the  lx>d\  the  jxtints  may  be  recognize 

He    found   that    in   much-used  regions,   such  as 
the  ends  of  the  fip.  .  and  the  tongue,  the  di -lances 

which  are  necessary  lx.-tween  |x>ints,  in  order  that  tliey  may 
be  distinguished,   are   u-ry  small,  often  less  than  a  single 
millimeter;  while  on  the  upper  arm  or  the  middle  of  the 
back  the  points   must   IK-  separated  by  three  to  six  ccnti 
meters  in  order  to  IK-  recognized  as  two.     Furthermo: 
has  been  abundantly  shown  since  the  time  of  \Ve!> 
is  the  greatest  uncertainty  in   the  estimation   of 
and  directions  in  the  regions  where  discrimination  of  points 
i^  difficult. 

Subjective  and  objective  space.    On  the  basis  of  ti 
facts  we  may  emphasize   the   difference    between    external 
space  and  our   recognition   of  space.     Two   millimeti 

ision  on  the  middle  of  the  back  are  for  the  geometri- 
cian equivalent  in  all  respects  to  the  same  distance  on  the 
finger.  For  the  observer  who  perceives  these  two  regions 
through  the  sense  of  touch,  the  recognition  of  the  two  dis- 
tances is  not  a  geometrical  fact,  uniform  for  all  parts  of  the 
body,  but  a  complex  of  varying  experiem 

Perception  and  training.  Experiments  of  the  kind  which 
Weber  tried  can  be  carried  farther.  Thus,  it  has  lx-cn 
shown  that  after  a  little  training  regions  of  the  skin  where 
the  discrimination  was  relatively  difficult  can  be  developed 
s  to  permit  of  very  much  finer  discrimination  than 
that  which  was  exhibited  at  first.  In  other  words,  without 
any  radical  change  in  the  sensory  conditions,  practice  will 
rapidly  refine  space  perception.  Again,  if  any  region  of  the 


COMBINATIONS  OF  SENSATIONS  165 

skin  is  stimulated  by  means  of  a  continuous  line  rather  than 
by  two  separate  points,  it  will  be  found  that  the  greater 
mass  of  sensations  received  from  the  line  facilitates  dis- 
crimination. A  line  can  be  recognized  as  having  exten- 
sion when  it  is  about  one  third  as  long  as  the  distance 
between  two  points  which  are  just  discriminated  as  sepa- 
rate from  each  other.  The  difficulty  of  discriminating  two 
points  when  they  are  presented  alone  is  not  due  to  the 
character  of  the  sensations  from  the  points,  but  rather  to 
the  difficulty  of  discriminating  them  without  the  aid  of  a 
more  complete  sensory  series  derived  from  the  stimulation 
of  points  between. 

Development  of  spatial  arrangements  in  the  course  of 
individual  experience.  In  our  search  for  an  explanation 
of  the  facts  of  tactual  perception  of  space,  let  us  ask 
what  is  the  course  of  individual  development.  Anyone 
who  observes  an  infant  recognizes  that  early  in  life  there 
is  the  greatest  uncertainty  in  locating  stimulations  on  the 
skin.  If  the  skin  of  .an  infant  is  vigorously  stimulated 
either  by  some  accident  or  by  the  efforts  of  someone  who 
is  interested  in  making  an  experimental  investigation,  it 
will  be  found  that  the  infant  moves  its  hands  about  in  the 
most  indefinite  fashion,  often  failing  entirely  to  reach  the 
irritated  spot.  We  can  understand  the  infant's  difficulty 
if  we  try  to  locate  with  precision  some  point  which  has 
been  stimulated  on  the  skin  of  the  upper  arm.  The  infant 
has  sensation  enough,  just  as  we  have  when  stimulated  in 
an  undeveloped  region,  but  the  sensation  is  not  properly 
related  to  other  sensations.  It  has  no  recognized  relations 
which  give  it  a  definite  place  in  a  well-ordered  sequence 
of  tactual  or  visual  qualities,  because  the  well-ordered 
sequence  has  not  yet  been  built  up.  An  established  series 
of  relations  of  some  definite  kind  is  necessary  before  the 
sensation  can  enter  into  distinct  spatially-ordered  percepts. 
Until  a  definite  series  of  space  notions  is  developed,  the 


166  PSYCH 

sensation  will  enter  only  into  vague  fusions,  and  localiza- 
tion will  be  aUogrtlu-r  ituompU-u-.  The  change  from  vague 
to  definite  localization  requires  much  experience  and  ;<• 

Indeed,  it  easily  \vrificd  that  no  sensation 

becomes  definite  in  its  relations  until  the  practical  needs 
of  life  demand  such  definiteness.  The  reason  why  an 
adult  discriminates  points  on  the  end  of  the  finger  and 
not  those  on  his  back  is  that  in  the  course  of  life  he 
has  been  obliged  to  use  his  ringer  sensations.  Use  has 
led  to  an  arrangement  of  points,  to  the  development  of 
what  may  figuratively  be  called  a  map.  This  map  is  <1< 
oped  by  recognizing  again  and  again  the  relation  of  a 
finger  to  the  palm  of  the  hand  and  of  the  palm  of  the 
hand  to  the  elbow,  and  so  on,  until  the  various  parts  of 
the  body  are  thought  of  as  in  a  fixed  relation.  The  map 
then  takes  on  a  kind  of  independence  and  remains  in 
the  mind  as  distinct  from  any  particular  sensations.  The 
adult  knows  the  parts  of  his  body  even  when  they  are 
not  actually  stimulated  at  the  moment. 

Vision  and  movement  as  aids  to  touch.  This  process  of 
developing  definiteness  in  tactual  localization  has  undoubtedly 
been  very  greatly  facilitated  by  the  presence  of  vision.  Even 
in  adult  life  one  can  often  find  himself  making  his  experience 
of  a  tactual  stimulation  more  exact  and  complete  by  looking 
at  the  point  irritated,  thus  relating  the  tactual  sensation  to 
visual  sensations.  The  process  of  localization  of  tactual  sen- 
sations is  also  very  largely  dependent  on  movement.  It  is  an 
empirical  fact  that  the  perceptual  arrangement  of  skin  sensa- 
tions is  most  complete  in  the  most  mobile  parts  of  the  body. 
A  number  of  careful  experimental  observers  at  one  time  ex- 
plored the  whole  surface  of  the  skin  and  showed  that  in  any 
given  region  that  part  which  is  most  mobile  is  the  part  on 
which  points  are  most  easily  discriminated.  Thus  the  hand 
is  the  most  highly  developed  part  of  the  arm  ;  the  foot  is  the 
most  highly  developed  part  of  the  leg. 


COMBINATIONS  OF  SENSATIONS  167 

Tactual  percepts  of  the  blind.  In  some  respects  the  tactual 
perception  of  blind  persons  is  more  highly  developed  than 
that  of  persons  who  have  vision.  The  blind  are  not  supplied 
with  better  organs  of  touch,  but  they  make  more  discriminat- 
ing use  of  such  experiences  as  they  receive  through  the  skin. 
They  also  make  more  use  of  movements  than  do  normal  per- 
sons, as  may  be  observed  in  the  fact  that  they  restlessly 
explore  every  object  which  comes  within  their  reach.  The 
limitations  of  the  space  perception  of  the  blind  appear  when 
complex  objects  are  presented  for  recognition.  When  the 
mass  of  sensory  impressions  is  great,  the  discrimination  and 
fusion  of  these  sensations  become  very  difficult.  This  fact  is 
strikingly  illustrated  by  the  history  of  the  raised  letters  used 
in  books  for  the  blind.  The  most  natural  way  of  producing 
such  books,  and  the  way  which  was  followed  at  first,  was  to 
print  in  raised  lines  the  same  letter  forms  as  were  used  for 
persons  who  read  visually.  For  vision  the  complex  lines  of 
ordinary  printed  letters  offer  no  difficulties,  because  vision  is 
so  highly  organized  that  it  discriminates  easily  the  ordinary 
printed  forms.  No  one  realized  that  touch  being  so  much 
coarser  than  vision  would  discriminate  forms  less  easily. 
Such  proved,  however,  to  be  the  case.  The  letters  for  the 
blind  have,  accordingly,  been  simplified  until  in  one  of  the 
best  and  most  recent  systems  the  letters  are  made  up  entirely 
of  points.  These  points  are  easy  to  distinguish  and,  being 
placed  near  one  another,  are  also  easy  to  recognize  in  groups. 

Wtmdt  on  the  tactual  perception  of  the  blind.  The  char- 
acter of  tactual  perception  in  the  case  of  the  blind  is  thus 
illustrated  and  discussed  by  Wundt : 

The  way  in  which  the  blind  alphabet  is  read  shows  clearly 
how  the  space  ideas  of  the  blind  have  developed.  As  a  rule,  the 
index  fingers  of  both  hands  are  used  in  blind  reading.  The  right 
finger  precedes  and  apprehends  a  group  of  points  simultaneously 
(synthetic  touch),  the  left  finger  follows  somewhat  more  slowly 
and  apprehends  the  single  points  successively  (analytic  touch). 


168  i  UOLOGY 

Both  the  v,  ntlu-tu  and  analytic  impressions  are  united  and  referred 
to  the  sa  thod  of  procedure  snows  dearly  that 

the  spatial  discrimination  <>i  nprcssions  is  no  more  immc- 

n  this  case  than  in  the  case  where  vision  was  present, 
but  that  in  the  case  of  the  blind  the  movements  by  means  of  \ 
the  tm^-r  that  is  used  r  touch  passes  from  point  to  point 

pl.i\  tlu-  same  part  as  did  the  accompanying  visual  ideas  in  the 
normal  cases  with  vision. 

Lotze's  local  signs.  Another  method  of  describing  the  tac- 
tual perception  of  space  is  that  adopted  by  Lotee,  one  of  the 
earliest  of  the  writers  on  physiological  psycho!'  .  I 
point  on  the  surface  of  the  body  gives  rise,  said  Ixrtze,  to  a 
tactual  sensation  which  in  addition  to  its  general  quality  and 
intensity  as  a  tactual  sensation  has  a  peculiar  and  character- 
istic shading  due  to  the  structure  of  the  skin  at  the  particular 
point  where  the  stimulus  is  applied.  Thus,  if  the  same  pres- 
sure is  applied  to  the  lips  and  the  forehead,  the  resulting  sen- 
sations will,  in  spite  of  general  likeness,  be  slightly  different 
in  the  two  cases,  because  there  is  soft  muscular  tissue  under 
the  skin  of  the  lips  and  hard  bom  under  the  skin  of 

the  forehead.  These  slight  differences  lx-tween  tactual  sen- 
sations which  are  due  to  locality  lead  th  er  to  arrange 
his  tactual  sensations  in  certain  systems  or  series.  The  quali- 
tative shadings  are  thus  transformed  into  spatial  series.  The 
qualitative  differences  come  to  signify  position  and  are  con- 
sequently designated  as  local  signs.  Their  character  as  local 
signs  is  derived  from  the  spatial  system  to  which  they  are 
referred  ;  they  are  individually  merely  qualitative  differences. 

Inner  tactual  factors.  The  factors  which  enter  into  tactual 
space  percepts  are  probably  derived  in  part  from  the  inner 
organs,  such  as  the  semicircular  canals,  the  joints,  and  the 
muscles.  From  the  semicircular  canals,  as  pointed  out  in 
an  earlier  chapter,  there  is  a  constant  stream  of  excitations 
reaching  the  central  nervous  system  with  every  change  in 
the  position  of  the  body.  The  limbs  in  their  movements 


COMBINATIONS  OF  SENSATIONS  169 

give  rise  to  sensations  in  the  joints  and  muscles.  While  the 
child  is  exploring  the  surface  of  his  body  and  attaining  the 
degree  of  ability  to  discriminate  points  which  is  shown  by 
Weber's  experiments,  he  is  also  learning  through  muscle 
sensations  to  recognize  distances  away  from  the  surface  of 
his  body  by  reaching  for  things  about  him.  He  is  learning 
through  the  sensations  from  his  semicircular  canals  that 
there  is  a  fundamental  distinction  between  "  right  side  up  " 
and  oblique  or  inverted  positions.  He  is  learning  through 
joint  sensations  to  recognize  how  many  steps  must  be  taken 
to  cross  certain  stretches  of  space. 

Space  not  attached  to  any  single  sense.  The  striking 
fact  is  that  ultimately  all  these  different  sensory  factors  are 
arranged  into  the  same  space  form.  There  is  not  one  tactual 
space,  and  another  space  for  muscle  sensations,  and  another 
for  joint  sensations.  All  are  fused  into  a  single  system. 
The  spatial  order  is  a  relational  fact ;  that  is,  it  is  a  product 
of  the  fusion  or  putting  together  of  sensations.  Whenever 
sensations  are  fused  into  the  spatial  relation  they  take  on  a 
character  different  from  that  which  can  be  assigned  to  them 
when  they  are  considered  alone. 

General  conclusions  regarding  tactual  space.  From  this 
survey  of  the  facts  of  tactual  space  we  have  derived  several 
important  conclusions.  Space  is  a  complex.  Space  is  not  a 
sensation  quality,  but  a  relational  form  of  experience.  Tactual 
space  is  not  explicable  without  reference  to  the  general  for- 
mula of  organization  which  includes  other  sensations  also. 

We  are,  accordingly,  justified  in  postponing  the  general 
explanation  of  space  perception  until  we  have  taken  up  the 
facts  regarding  the  arrangement  of  auditory  and  visual  sen- 
sations in  the  spatial  form. 

Auditory  recognition  of  location.  Experiments  on  the 
localization  of  sounds  may  be  made  as  follows  :  Let  a  sound 
be  produced  in  the  median  plane,  which  passes  vertically 
through  the  head  from  in  front  backward,  midway  between 


170  I'^M  II'  'I  <>GY 

tin-  t\v<»  cars.  If  the  sound  is  simple  in  quality,  as,  for  ex- 
amp:  of  some  kind,  and  the  observer's  eyes 
are  closed  so  as  to  elimu,  >n  and  make  him  entirely 
dependent  on  hearing,  the  localization  of  the  sound  will  in 
the  majority  of  cases  be  erroneous.  The  sound  will  always 
be  localized  somewhere  in  the  median  plane,  but  its  exact 
position  in  this  plane  cannot  be  recognized.  If,  on  the  other 
hand,  the  sound  is  m  htly  to  the  right  or  left  of  the 
median  plane,  it  will  be  found  that  the  observer  can  local- 
ize the  sound  with  great  accuracy.  The  explanation  of  the 
observer's  ability  to  locate  sounds  coming  from  the  side  is 
simple  and  depends  chiefly  upon  the  fact  that  the  observer 
receives  from  such  a  sound  different  intensities  of  sensation 
in  the  two  ears.  From  all  positions  in  the  median  plane  the 
two  groups  of  sensations  received  in  the  two  ears  have  equal 
intensities,  whereas  the  intensities  of  sounds  received  in  the 
two  ears  from  any  position  outside  of  the  median  plane  are 
unequal. 

Influence  of  movements  in  auditory  experience  of  position. 
Undoubtedly  here,  as  in  the  case  of  tactual  space,  the  facts 
of  movement  are  of  great  significance  in  organizing  sensory 
experience.  If  a  sound  on  one  side  of  the  head  is  more 
intense  than  the  sound  on  the  other,  there  will  be  a  strong 
tendency  to  readjust  the  head  in  such  a  way  that  the  stronger 
sound  shall  be  made  even  more  intense  and  the  weaker 
group  of  sensations  shall  be  made  still  fainter  by  the  move- 
ment of  the  head.  If  a  sound  is  in  the  median  plane  and 
there  is  difficulty  in  getting  at  its  precise  localization,  there 
is  frequently  a  noticeable  effort  on  the  part  of  the  observer 
to  bring  the  head  into  such  a  position  that  a  more  satisfac- 
tory determination  of  position  shall  be  possible  through  a 
modification  of  the  intensities  of  the  sensations  from  th< 
ears.  Often  auditory  perception  issues  in  a  movement  which 
tends  to  bring  the  eyes  toward  the  source  of  the  sound. 
The  same  tendency  which  was  noted  in  the  discussion  of 


COMBINATIONS  OF  SENSATIONS  171 

tactual  sensations  to  fuse  various  kinds  of  sensations  into  a 
single  spatial  system  is  obvious  in  this  effort  to  supplement 
hearing  by  vision. 

Qualitative  differences  and  localization.  The  explanation 
which  has  been  presented  can  be  made  more  elaborate  by 
giving  attention  to  qualitative  differences  as  well  as  to  differ- 
ences in  intensity  in  the  two  groups  of  sensations  received 
by  the  two  ears.  There  can  be  no  doubt  that  the  external 
pinna  of  the  ear  modifies  somewhat  the  character  of  the 
sound  as  it  enters  the  auditory  canals.  If  a  complex  sound 
strikes  the  pinna  from  in  front,  its  quality  will  be  different 
from  that  which  would  result  if  the  same  sound  is  carried 
into  the  ear  from  behind.  As  a  result  of  these  qualitative 
modifications  produced  by  the  external  ear,  we  are  able  to 
localize  sounds  even  in  the  median  plane,  provided  they 
are  of  complex  quality.  The  human  voice,  for  example,  in 
the  median  plane  of  the  head,  can  usually  be  recognized 
with  great  precision  as  coming  from  a  point  in  front  or 
behind.  This  is  due  to  the  fact  that  the  voice  is  complex 
in  quality. 

Distance  of  sounds  recognized  only  indirectly.  The  dis- 
cussion of  the  recognition  of  the  direction  from  which 
sounds  come  may  be  supplemented  by  reference  to  the  fact 
that  the  recognition  of  the  distance  of  sounds  also  involves 
a  large  body  of  organized  experiences.  If  one  hears  the 
human  voice  sounding  very  faintly  in  his  ears,  his  frequent 
experience  with  voices  and  their  normal  intensity  when  the 
speakers  are  near  at  hand  will  lead  him  to  recognize  that 
the  person  speaking  is  far  away.  Furthermore,  the  qualita- 
tive character  of  the  sound  as  well  as  its  intensity  is  modi- 
fied by  the  remoteness  of  its  source,  the  elements  of  the 
sound  being  less  distinct  when  it  is  transmitted  from  a 
great  distance  to  the  ear.  The  intensity  and  quality  are, 
accordingly,  both  utilized  in  interpretations  of  distance  so 
long  as  the  sound  is  familiar. 


172 

Unfamiliar  sounds  difficult  to  locate.    In  contrast  to  the 
ion  of  ti>  e  of  a  familiar  sound, 

it  is  <  the-  distance  of  the  source 

of  an  unfamiliar  sound.    An  exp<  be  tried  by 

producing  an  unfamiliar  sound,  such  as  that  which  n 
from  snapping  a  card  in  the  neighborhood  of  an  observer's 
head.    Until  this  sound  has  become  familiar  the  errors  in 
estin.  distance  will  be  very  noticeable. 

Visual  space  and  optical  illusions.    If  we  turn  from  audi- 
tor)- space  perception  t<>  visual  exjx-n-  find  a 
variety  of  examples  which  show  how  complex  is  the  process 


Fir,.  47.    Mullcr-I.ycr  illusion 

The  length  of  the  horizontal  line  A  is  equal  to  the  length  of  the  horuonul  line  B. 
lurther  discussion  of  the  figure  see  text) 

of  arranging  sensations  in  a  spatial  order.  There  are  certain 
cases  of  incorrect  perception  of  length  and  direction  of 
figures  in  plane  surfaces,  constituting  what  are  known  as 
geometrical  optical  illusions.  These  are  especially  clear 
examples  of  complex  perception.  Take,  for  example,  the 
illusion  represented  in  Fig.  47.  The  two  lines  A  and  B  are 
in  reality  equal  to  each  other,  but  the  observer  will  recog- 
nize at  once  that  they  seem  to  be  of  different  lengths.  The 
retinal  image  of  each  line  is  distinct  and  clear ;  the  apparent 
inequality  cannot,  therefore,  be  attributed  to  any  confusion 
.  in.  the  retinal  processes ;  it  must  be  attributed  to  some  kind 
of  perceptual  complexity.  The  explanation  of  the  source  of 


COMBINATIONS  OF  SENSATIONS  173 

this  illusion  has  been  the  subject  of  much  discussion,  and 
it  is  probably  true  that  no  single  statement  will  account  for 
the  apparent  inequality  of  A  and  B.  In  a  general  way  it 
may  be  said  that  one  cannot  look  at  A  and  B  without 
including  in  his  field  of  vision  the  oblique  lines,  and  the 
oblique  lines  are  such  striking  and  unfamiliar  additions  to 
the  horizontal  lines  that  they  are  not  neglected  as  they 
should  be  in  perceiving  the  length  of  the  horizontals.  If, 
in  addition  to  this  general  statement,  we  attempt  to  show 
in  detail  how  the  oblique  lines  affect  the  horizontals,  there 
are  a  number  of  facts  which  may  be  noted.  The  oblique 
lines  produce  less  of  an  effect  upon  some  observers  than 
upon  others.  This  can  be  shown  by  making  quantitative 
determinations  of  the  intensity  of  the  illusion.  For  this 
purpose  one  of  the  figures  of  the  pair  under  discussion  is 
made  adjustable,  and  the  observer  sets  it  until  it  seems  to 
him  equal  to  the  other  figure.  When  the  two  seem  equal 
they  will  be  in  reality  different.  The  amount  of  difference 
can  now  be  readily  measured,  and  the  results  from  various 
observers  compared.  Not  only  are  the  results  of  such  meas- 
urements different  for  different  observers,  but  the  same  indi- 
vidual will  at  various  times  give  different  results. 

Effects  of  practice.  One  especially  significant  case  of  in- 
dividual variation  is  that  in  which  the  observer  deliberately 
sets  about  comparing  the  figures  a  great  number  of  times 
for  the  purpose  of  becoming  familiar  with  them.  Three 
stages  of  change  in  interpretation  show  themselves  in  such 
a  practice  series.  First,  the  observer  takes  a  general  view 
of  the  whole  figure,  as  does  the  ordinary  observer  who 
looks  casually  at  the  illusion ;  he  gets  in  this  case  a  strong 
illusion.  Second,  the  observer  tries  to  look  at  the  long  lines 
and  neglect  the  obliques ;  that  is,  he  makes  an  effort  to 
overcome  the  disturbing  influence  in  a  negative  way.  During 
this  period  of  conscious  neglect  of  the  obliques  the  illusion 
grows  somewhat  weaker,  but  it  does  not  disappear.  Finally, 


174  I'SV<  HOLOGY 

in  the  third  stage,  the  observer  reaches  the  point  where 
there  is  no  need  of  an  effort  to  neglect  the  obliques.  In- 
terpretation may  be  said  to  be  so  completely  worked  out  in 
this  stage  that  the  obliques  and  the  long  lines  fall  into  their 
proper  relations  without  interfering  with  one  anoth 
is  included  in  the  percept,  but  in  its  true  significance.  At 

the  illusion  is  entirely  overcome. 
Percepts  always  complex.    Such  facts  as  these  mak 
clear  that  a  visual  percept  includes  all  the  factors  in   the 
field  of  vision.    If  these  factors  are  conflicting,  they  may 
result   in    grotesque    misinterpretations.    If,   on   the  other 
hand,  they  are  thoroughly  assimilated  into  the  percept,  they 


1-  it..  48.    Illusion  of  contrast 

The  middle  portion  of  the  short  horizontal  line  marked  off  by  the  verticals  teems 
longer  than  the  equal  distance  marked  off  in  the  long  horizontal  line 

take  their  appropriate  relations  and  no  longer  disturb  the 
total  process  of  perception. 

Contrast.  A  great  many  other  illustrations  could  be 
brought  forward  to  show  the  relation  of  one  part  of  the 
visual  field  to  all  other  parts.  Thus,  one  cannot  look  at  a 
line  on  a  large  blackboard  and  fail  to  be  influenced  in  his 
estimation  of  the  length  of  the  line  by  the  large  surround- 
ing space.  Conversely,  a  line  drawn  on  a  small  sheet  of 
paper  is  always  interpreted  in  terms  of  the  paper  as  either 
relatively  long  or  relatively  short.  Objects  seem  very  differ- 
ent in  size  when  seen  outdoors  and  again  in  a  small  room. 
Fig.  48  illustrates  this  principle  by  showing  a  short  central 
line  as  part  of  a  long  line  in  one  case  and  as  part  of  a 
short  line  in  a  second  case,  with  the  result  that  the  central 
line  seems  to  be  of  different  lengths  in  the  two  cases. 


COMBINATIONS  OF  SENSATIONS  175 

Common  facts  showing  size  to  be  a  matter  of  relations. 
Other  complications  than  those  from  the  surrounding  visual 
field  also  influence  one's  perception  of  size.  The  natural 
standards  of  size  which  depend  upon  familiarity  and  upon 
the  relations  of  objects  to  one's  own  body  are  constantly 
influencing  perception.  Time  and  again  descriptions  have 
been  given  by  observers  of  the  fact  that  a  road  seems 
longer  the  first  time  one  passes  over  it,  when  all  the 
sights  are  unfamiliar ;  and  many  have  also  referred  to  the 
fact  that  places  known  in  childhood  always  seem  small  when 
revisited  in  mature  life. 

Physiological  conditions  of  visual  perception.  The  signifi- 
cance of  all  these  facts  for  our  understanding  of  visual  space 
is  not  hard  to  find.  Putting  the  matter  in  physiological 
terms,  we  may  say  that  when  series  of  visual  stimulations 
from  a  given  line  or  figure  reach  the  visual  center,  they  find 
there  a  larger  series  of  excitations  from  other  points  on  the 
retina  and  a  series  of  organized  modes  of  response  derived 
from  past  experience.  Each  excitation  takes  its  place  in 
this  complex. 

Psychological  statement.  Putting  the  same  matter  in  psy- 
chological terms,  we  may  say  that  every  sensation  becomes 
part  of  a  fixed  order.  This  order  or  spatial  arrangement  is 
something  other  than  the  sensations  ;  it  is  a  product  of 
perceptual  fusion. 

Photographic  records  of  percepted  movements.  A  clearer 
understanding  of  the  matter  will  be  reached  by  considering 
the  results  of  photographic  investigations,  in  which  the  path 
of  the  eye  movement  in  looking  over  certain  illusory  figures 
has  been  determined.  In  Fig.  49  there  is  presented  one  of 
the  most  striking  of  the  illusions  of  direction.  The  long  lines 
are  in  reality  parallel  with  each  other,  but  the  obliques  are 
far  too  distracting  to  permit  the  ordinary  observer  to  recog- 
nize the  true  relations  between  the  parallel  lines.  Fig.  50 
shows  another  illusion  of  direction.  The  oblique  lines  are 


I76 


PSYCHOLOGY 


parts  of  a  single  line,  but  seem  to  extend  in  slightly  different 
directions  because  of  the  interrupting  space  between  the 


FIG.  49.   Zollner  illusion 
The  long  lines  are  parallel  with  each  other 

parallels.  Fig.  5 1  shows  the  paths  in  which  photographs  indi- 
cate that  the  eye  of  an  observer  moved  in  attempting  to  look 
at  the  illusions  discussed.  In  Fig.  5 1,  A,  the  movement  over 
the  Zollner  pattern  is  shown.  It  is  evident  from  the  move- 
ments indicated  in  the  photographs  that  the  sensation  factors 
are  not  fully  mastered  so  as  to  permit  coordinated  move- 
ments along  the  parallel  lines.  The  result  is  that  though 
these  lines  give  perfectly  clear  retinal  images,  they  do  not 
stand  in  their  true  relations  in  experience. 
The  photographs  show  that  often  there 
is  sufficient  fusion  of  the  sensory  factors 
to  permit  a  single  movement  in  follow- 
ing a  line,  and  this  single  movement  is 
in  the  general  part  of  the  field  of  vision 
in  which  the  line  lies,  but  it  is  only  a 
gross  general  approximation  to  the  line. 
This  corresponds  exactly  to  the  fact  that 
the  experience  of  the  figure  consists  of 
a  gross  general  perception  of  the  long 
line  and  its  obliques.  One  observer,  after  these  preliminary 
photographs  of  his  eye  movements  in  looking  at  the  Zollner 


FIG.  50.    Poggendorff 
illusion 

A,  B  are  parts  of  the  same 
straight  line 


COMBINATIONS  OF  SENSATIONS 


177 


\ 


6        B 


FIG.  51.    These  figures  show  the  path  followed  by  the  eye  of  an  observer 
in  examining  certain  of  the  foregoing  illusions 

In  each  of  the  figures  the  path  of  the  eye  movement  is  indicated  by  a  supplemen- 
tary line.  The  numbers  placed  along  these  supplementary  lines  indicate  the  points 
at  which  a  pause  was  made  in  the  course  of  the  eye  movement.  In  Fig.  51,  A,  the 
observer  was  attempting  to  follow  the  long  line  of  the  illusion.  It  will  be  noticed 
that  he  departs  from  the  long  line,  and  at  the  extreme  end  of  the  movement,  as  at 
2  and  5,  makes  a  short  corrective  movement  by  which  he  again  fixates  the  long 
line.  In  Fig.  51,  B,  the  distracting  influence  of  the  vertical  lines  is  obvious,  as  is  also 
the  difficulty  of  moving  the  eye  across  the  open  space  in  any  such  way  as  to  reach 
the  point  of  interconnection  between  the  vertical  and  oblique  lines.  In  Fig.  51,  C, 
it  will  be  noted  that  the  eye  movement  is  very  free  in  that  part  of  the  figure  which 
is  overestimated,  and  much  restricted  whenever  the  eye  approaches  one  of  the 
acute  angles.  This  is  indicated  by  the  frequent  pause  in  3,  4,  6,  7,  8,  9.  In  8  it 
will  be  noted  that  the  eye  is  deflected  from  the  horizontal  line  by  the  oblique 


f(  IK  'I . 

pattern,  put  himself  through  a  series  of  quantitative  tests 
with  the  figure.  In  this  practice  series  he  gradually  over- 
came th  ting  effects  of  the  oblique  lines,  and  the 
illusion  disappeared.  A  secoiv  <>f  photographs  taken 
after  the  practice  series  showed  that  his  eye  followed  the 
long  line  with  great  precision.  Photographs  with  other 
illusions  show  clearly  the  distracting  effects  of  the  additional 
lines  as  indicated  in  full  in  Fig.  46. 

Relation  between  size  and  distance.  When  we  study  the 
relation  of  size  to  distance  from  the  observer,  we  find  a 
series  of  complexities  even  greater  than  those  which  have 
appeared  thus  far.  In  order  to  demonstrate  this  experi- 
mentally an  observer  should  first  secure  an  after-image 
through  the  steady  fixation  of  some  bright  object.  The 
after-image  covers  a  certain  number  of  retinal  elements  and 
may  be  considered  as  giving,  as  long  as  it  lasts,  a  constant 
group  of  sensations.  When  the  observer  is  looking  at  the 
object  this  mass  of  sensations  will  be  interpreted  as  having 
a  certain  definite  size  and  distance.  When  the  same  mass 
of  impressions  comes  from  the  after-image,  it  can  easily  be 
related  to  different  distances,  and  with  each  change  in  ap- 
parent distance  it  will  take  on  a  different  apparent 
The  change  in  distance  can  easily  be  produced  by  looking 
at  various  surfaces  which  are  at  different  distances.  The 
after-image  will  seem  in  each  case  to  be  on  the  surface  at 
which  the  observer  is  looking  at  the  moment,  whatever  the 
distance  of  that  surface.  The  after-image  will  seem  smaller 
when  the  surface  on  which  it  is  projected  is  nearer  than  the 
original  object  from  which  the  image  was  derived,  and  larger 
when  the  surface  is  farther  away. 

Definite  optical  relation  between  the  distance  and  the  size 
of  an  object  and  the  size  of  the  retinal  image  from  this 
object.  This  series  of  observations  makes  it  clear  that  the 
size  of  a  retinal  image  does  not  determine  the  interpretiti*  n 
of  the  size  of  an  object  without  reference  to  the  addii 


COMBINATIONS  OF  SENSATIONS 


179 


fact  of  distance.  A  given  retinal  image,  for  the  after-image 
on  the  retina  remained  the  same  throughout  the  series  of 
observations,  may  be  interpreted  as  a  large  object  far  away 
or  as  a  small  object  near  at  hand.  The  optical  principle 
which  underlies  this  series  of  observations  is  illustrated  in 
Fig.  52.  In  this  figure  the  retinal  image  is  represented  by 
the  inverted  arrow  AB,  and  the  lines  from  the  extremities 
of  this  image  passing  through  the  optical  center  of  the  lens 
determine  the  positions  of  various  external  objects,  any  one 
of  which  satisfies  the  image.  It  will  be  seen  from  this 


FIG.  52.    The  retinal  image  AB  may  be  equally  well  related  to  any  one  of 
the  objects  ab,  a'b',  a"b" 

drawing  that  a  succession  of  arrows  outside  of  the  eye,  differ- 
ing in  length  from  each  other,  may  all  cast  the  same  retinal 
image.  This  general  principle  is  doubtless  familiar  to  every- 
one when  stated  in  the  following  simple  terms :  A  small 
object  such  as  the  finger  held  near  the  eye  can  shut  out  the 
image  of  a  large  remote  object,  such  as  a  tree  or  a  building. 
When,  now,  the  after-image  in  the  experiment  is  projected 
to  distances  near  and  far  away,  its  significance  and  perceptual 
interpretation  are  immediately  modified,  even  though  the 
retinal  sensations  are  uniform  in  volume  and  distribution  on 
the  sensory  surface  of  the  eye. 

Berkeley's  statement  of  the  problem  of  visual  depth  per- 
ception. These  observations  lead  us  to  a  problem  which  was 
so  clearly  stated  by  one  of  the  early  writers  in  the  modern 


IS,, 

period  of  psychology  that  we  may  quote  his  statement  in 
full.    In  a  treatise  published  in  1709  Bishop  Berkeley  said: 

It  is,  I  think,  agreed  by  all  that  distance  of  itself,  and  irnmcdi- 
not  be  seen.    For  distance  being  a  line  directed  endwise 
to  t!  projects  only  one  point  on  the  fund  of  the  eye  — 

which  |X'int  remains  invariably  the  same,  whether  the  distance  be 
er  Of  shorter.    I  find  it  also  acknowledged  that  the  estimate  we 
make  of  the  distance  of  objects  considerably  remote  is  rather  an 
act  of  judgment  grounded  on  experience  than  of  sense. 

Berkeley  goes  forward  in  the  remainder  of  the  "  Essay  toward 
a  New  Theory  of  Vision  "  to  account  for  this  process,  which 
he  calls  a  process  of  judgment.  He  draws  attention  to  the 
fact  that  whenever  one  looks  at  an  object  near  at  hand  he 
rotates  his  two  eyes  toward  the  nose  so  that  the  points  of 
view  from  which  he  observes  the  object  are  different  in  the 
two  eyes.  He  asserts  that  the  convergence  of  the  two  < 
as  their  inward  rotation  is  called,  gives  rise  to  certain  experi- 
ences of  movement,  which  are  utilized  as  interpreting  fat 

Experiments  on  binocular  vision.  The  researches  of 
modern  experimental  psychology  have  confirmed,  in  general, 
Berkeley's  explanation,  though  they  emphasize  more  than 
he  did  the  differences  between  the  two  sets  of  retinal  im- 
pressions received  in  the  two  eyes.  The  fact  that  tht 
eyes  contribute  a  complex  of  sensations  through  which  we 
perceive  distance  has  been  abundantly  confirmed.  The 
reasoning  involved  is  as  follows  :  If  distance  is  recognized 
as  a  result  of  a  complex  of  sensations  coming  from  the  two 
.  then  it  should  be  possible  to  show  that  the  recognition 
of  depth  is  seriously  interfered  with  by  the  withdrawal  of 
any  of  the  factors  contributed  by  the  two  eyes.  It  is  not 
possible  to  remove  altogether  the  influence  of  both  eyes, 
even  when  one  is  closed  ;  hence,  vision  can  never  be  reduced 
to  strictly  monocular  vision,  but  the  following  simple  experi- 
ment may  be  tried  to  show  the  dependence  of  the  clear 


COMBINATIONS  OF  SENSATIONS  181 

recognition  of  depth  upon  vision  with  two  eyes.  If  an  ob- 
server covers  one  eye  and  then  attempts  to  bring  his  finger 
directly  over  some  object  which  stands  in  front  of  the  open 
eye,  he  will  find  that  the  ability  to  bring  the  finger  directly 
over  the  object  in  question  is  very  much  less  than  his  ability 
to  do  so  under  the  ordinary  conditions  of  binocular  vision. 
A  direct  observation  of  the  same  general  fact  can  be  made 
if  the  observer  will  note  carefully  the  difference  in  the  ap- 
parent solidity  and  remoteness  of  objects  when  he  observes 
them  first  with  a  single  eye  and  immediately  afterward  with 
both  eyes  open.  These  observations  show  that  the  complete 
recognition  of  distance  and  depth  involves  all  the  sensory 
factors  from  the  two  eyes ;  whenever  there  is  any  disturbance 
of  the  normal  conditions  the  result  appears  in  incomplete 
perception,  for  the  relational  or  perceptual  process  does  not 
in  such  cases  have  its  normal  complex  of  content  with  which 
to  deal. 

Difference  between  the  images  in  the  two  eyes.  The  con- 
tributions made  to  experience  by  the  two  eyes  are  different, 
as  can  be  clearly  seen  if  an  observer  will  hold  some  solid 
object  near  the  face  and  look  at  it,  first  with  one  eye  open 
and  then  with  the  other.  The  difference  between  the  two 
views  in  the  two  eyes  can  be  briefly  defined  by  saying  that 
with  the  right  eye  one  sees  more  of  the  right  side  of  a  solid 
object  and  less  of  the  left  side,  while  with  the  left  eye  one 
sees  more  of  the  left  side  of  a  solid  object  and  less  of  the 
right  side.  These  relations  are  made  clear  in  Fig.  53. 
When  the  two  retinal  images  from  the  solid  object  are 
received  by  an  observer,  they  are  immediately  fused  with 
each  other  into  a  single  perceptual  complex,  as  were  the 
two  groups  of  auditory  sensations  discussed  in  an  earlier 
section  of  this  chapter. 

Stereoscopic  figures  and  appearance  of  solidity.  There  is 
an  apparatus  often  used  for  purposes  of  amusement,  in  which 
the  principle  that  the  appearance  of  solidity  depends  upon 


I8J 


PSYCHOLOGY 


disparity  of  the  two  retinal  images  is  utilized  to  produce  the 
appearance  of  solidity  even  when  no  solid  object  is  present. 
The  apparatus  in  question  is  the  stereoscope.  Photographs 
are  taken  or  drawings  are  made,  corresponding  iji  form  to 

the  retinal  images  which 

:d  be  obtained  by  • 
eyes  if  they  were  look- 
ing at  a  solid  figure  or 
series  of  figures  at  differ- 
ent depths.  The 
drawings  or  photographs 
are  then  projected  by 
means  of  the  stereoscope 
into  the  two  eyes  of  an 
observer  in  such  a  way 
that  the  right  retina  is 
stimulated  by  the  image 
appropriate  to  the  right 
eye,  and  the  left  retina 
is  stimulated  by  the  fig- 
ure appropriate  to  the 
left  eye.  The  obser 
who  thus  receives  the 
sensory  impressions  ap- 
propriate to  solidity,  will 
naturally  fuse  the  two 
images  and  will  see  in 
space  before  him  a  solid 
object  which,  in  reality. 


B  c 

FIG.  53.    Showing  binocular  parallax 

The  cube  BDAC  a  held  near  the  two  eyes 
with  the  result  that  the  right  eye  sees  the 
surface  DA  and  the  right  side  of  the  cube, 
while  the  left  eye  sees  the  surface  DA  and 
the  left  side  of  the  cube.  If  a  plane  is  passed 
through  the  rays  of  light  which  enter  the  eye 
from  the  cube,  as  indicated  by  the  dotted  line 
in  the  figure,  it  will  be  seen  that  the  retinal 
images  of  the  two  eyes  contain  each  a  distinct 
element.  The  eye  on  the  left-hand  side  of  the 
figure  has  a  retinal  image  corresponding  to 
BD,  which  is  absent  in  the  other  eye.  Further 
details  will  be  obvious  from  the  figure 

is  not  there,  but  which 

is  adequately  represented  by  the  two  flat  drawings  projected 
into  his  eyes.  A  great  many  experiments  can  be  tried  with 
the  stereoscope  which  make  clear  the  significance  of  the 
two  retinal  images  for  the  recognition  of  solidity  and  depth. 
It  can  thus  be  shown  that  the  fused  resultant,  that  is,  the 


COMBINATIONS  OF  SENSATIONS  183 

percept  of  a  solid  object,  does  not  derive  its  characteristics 
from  either  one  of  the  retinal  impressions  considered  in 
itself,  for  each  image  so  considered  is  deficient  in  solidity. 
The  fusion  is,  in  a  very  proper  sense  of  the  word,  a  compro- 
mise between  the  two  different  images,  and  there  appears  as 
a  result  of  fusion  at  least  one  characteristic  which  neither 
figure  had  in  itself ;  namely,  the  characteristic  of  clearly 
defined  solidity. 

Retinal  rivalry.  When  the  binocular  images  are  totally 
different,  as  in  certain  experiments  which  may  be  arranged 
with  the  stereoscope,  the  observer  finds  that  it  is  impossible 
for  him  to  fuse  the  two  groups  of  impressions.  Thus,  if  he 
looks  with  one  eye  at  a  series  of  horizontal  lines,  and  with 
the  other  at  a  series  of  vertical  lines,  he  will  see  the  fields 
in  succession.  The  'group  of  sensations  coming  from  one 
retina  will  first  be  recognized  in  clear  consciousness  and 
will  then  fade  out  and  give  place  to  the  sensations  derived 
from  the  second  retina.  There  is  thus  an  oscillation  in 
experience  which  is  vividly  described  by  the  term  "  retinal 
rivalry."  In  retinal  rivalry  there  is  obviously  a  lack  of  fusion 
of  the  sensations.  The  artificial  differences  in  binocular 
images  here  produced  are  so  foreign  to  the  experiences 
which  present  themselves  in  ordinary  life  that  the  observer 
is  unable  to  fuse  them  into  a  single  conscious  process.  If 
such  strange  combinations  of  sensations  are  to  be  in  any 
way  related,  it  must  be  in  a  temporal  succession  of  mental 
activities  rather  than  in  a  single  spatial  form. 

Factors  other  than  those  contributed  by  the  two  eyes. 
The  recognition  of  depth  through  the  fusion  of  two  groups 
of  retinal  sensations  is  not  the  only  form  of  visual  recogni- 
tion of  depth.  Other  factors  of  experience  and  other  types 
of  relation  may  enter  into  the  complex.  In  every  case,  how- 
ever, the  factors  or  relations  which  contribute  to  the  inter- 
pretation of  solidity  are,  like  the  differences  in  binocular 
vision  just  discussed,  complexes  which  get  their  significance 


1 84  PSYCHOLOGY 

and  value  not  because  of  their  sensation  qualities  but  by 
virtue  of  the  relations  into  which  the  sensations  are  brought. 

Aerial  perspective.  The  first  facts  to  which  reference  may 
be  made  are  the  differences  in  colors  and  sharpness  of  out- 
line which  appear  when  objects  are  seen  through  different 
thicknesses  of  atmosphere.  Remote  colors  are  always  dull 
and  darker  in  shade  than  colors  near  at  hand,  and  the  out- 
I  of  remote  objects  are  ill-defined.  We  are  so  trained 
in  the  interpretation  of  these  general  facts  that  in  looking 
at  a  landscape  we  pay  very  little  attention  to  color  quality  or 
to  the  lack  of  clearness  in  outline,  but  utilize  these  immedi- 
ately for  purposes  of  depth  perception ;  that  is,  the  sensa- 
tions are  not  recognized  as  distinct  facts  in  experience,  but 
are  allowed  to  serve  their  function,  which  is  to  indicate  the 
position  of  the  object  from  which  they  come.  Let  the  ob- 
server carefully  compare  his  experience  of  distant  fields  in 
the  landscape  with  fields  near  at  hand.  He  will  find  that 
the  remoter  greens  arc  blue  in  cast,  even  though  under 
ordinary  circumstances  his  attention  is  not  directed  to  these 
differences  in  color  shades.  The  same  truth  is  well  illus- 
trated by  the  fact  that  persons  who  have  been  accustomed 
to  living  in  a  moist  atmosphere  always  misinterpret  distances 
when  they  go  to  regions  where  the  air  is  clear  and  free  from 
moisture.  Great  distances  seen  through  clear  air  are  under- 
estimated because  of  the  small  effect  which  the  air  produces 
in  modifying  the  colors  and  outlines  of  objects. 

Geometrical  perspective  and  familiarity.  Another  impor- 
tant means  of  recognizing  depth  is  through  the  familiarity 
which  we  have  acquired  with  certain  common  objects.  If  a 
given  object  is  carried  farther  and  farther  away  from  the 
eye,  it  will  cast  upon  the  retina  a  smaller  and  smaller  image. 
If  a  man  first  observed  at  a  distance  of  ten  feet  moves  to 
a  distance  of  twenty  feet,  the  size  of  the  retinal  image  and, 
consequently,  the  mass  of  sensations  derived  from  this  man 
will  decrease  one  half.  We  seldom  interpret  such  changes 


COMBINATIONS  OF  SENSATIONS  185 

in  the  size  of  a  retinal  image  of  a  familiar  object  as  changes 
in  the  size  of  the  object  itself ;  thus,  we  never  say  that  a 
receding  man  has  dwarfed  to  half  his  original  size.  We 
have  learned  by  long  experience  that  most  of  the  objects  of 
our  environment  are  permanent  in  size  and  that  the  changes 
in  our  sensations  merely  indicate  changes  in  the  position  of 
these  objects.  In  this  way  we  build  up  an  elaborate  series 
of  recognitions  of  differences  in  depth.  How  completely  we 
depend  upon  this  recognition  of  familiar  objects  for  our 
interpretation  of  unfamiliar  or  undefined  experiences  will  be 
recognized  if  it  is  remembered  that  the  interpretation  of  the 
size  and  distance  of  objects  in  photographs  is  always  uncer- 
tain unless  some  familiar  figure,  such  as  that  of  a  human 
being,  appears  as  a  scale  by  which  to  gauge  the  sizes  of  the 
other  objects. 

Shadows.  Another  factor  which  is  sometimes  significant 
in  giving  rise  to  the  interpretation  of  depth  is  found  in  the 
shadows  cast  by  objects.  The  apparent  solidity  of  a  bank  of 
clouds  in  the  sky  cannot  depend  upon  binocular  differences, 
because  the  clouds  are  too  remote.  They  are  also  quite  un- 
familiar, and  may  be  without  color ;  therefore  the  methods 
of  interpretation  which  we  have  described  up  to  this  point 
are  quite  inadequate  to  explain  their  apparent  solidity.  The 
shadows  which  they  cast  upon  each  other  are,  however,  so 
clear  in  their  indication  of  differences  of  position  with  refer- 
ence to  the  sun  that  we  immediately  recognize  a  bank  of 
shaded  clouds  as  made  up  of  parts  differing  in  distance  from 
us.  The  same  principle  of  recognition  of  solidity  is  utilized 
in  all  flat  drawings  intended  to  represent  solid  objects.  Such 
flat  drawings  can  always  be  made  to  suggest  solidity  with 
vividness  when  they  are  shaded  in  a  way  corresponding  to 
the  objects  themselves. 

Intervening  objects.  Finally,  we  make  use  of  the  fact  that 
near  objects  very  frequently  cut  off  our  vision  of  remote  ob- 
jects. Thus,  if  a  tree  which  can  be  seen  in  all  of  its  parts 


1 86  PSV<  I! 

cuts  off  a  portion  of  a  house  or  other  object,  we  perceive 
the  house  not  as  divided  by  the  tree  but  as  standing  behind 
it.  Mere  again  we  interpret  our  sensations  as  indicating  dif- 
L-CS  in  position  rather  than  differences  in  the  objects 
themselves. 

Depth  a  matter  of  complex  perception.  One  cannot  re- 
view this  series  of  facts  with  regard  to  the  visual  interpreta- 
tion of  depth  without  being  confirmed  in  his  view  that  space 
perception  is  a  process  in  which  sensory  factors  arc  related 
to  each  other  in  the  most  complex  manner.  No  retinal  im- 
pression has  its  value  for  mental  life  fully  determined  until 
it  is  brought  into  relation  with  other  sensations. 

Relation  to  movements.  As  in  the  case  of  tactual  percepts, 
so  here  there  is  a  close  relation  between  visual  space  and 
movements.  In  the  first  place,  movements  of  the  eyes  are 
intimately  related  in  their  development  to  visual  recognition 
of  space.  When  an  infant  attempts  to  turn  his  two  eyes  on 
the  same  point  of  fixation,  his  movements  are  frequently  so 
slow  and  irregular  that  they  have  the  appearance,  especially 
in  photographs,  of  cross-eyed  movements.  Kvc-n  in  adult 
life  it  is  shown  by  rapid  photographs  that  the  two  eyes  often 
move  to  a  point  of  fixation  in  such  a  way  that  while  one  eye 
moves  rapidly,  the  other  comes  up  in  an  irregular,  relatively 
slow  movement.  The  development  of  a  coordinated  move- 
ment is  thus  seen  to  be  the  product  of  effort  and  concentra- 
tion. That  a  coordinated  movement  has  been  developed  at 
all  shows  how  significant  it  is  for  the  individual  that  he 
should  acquire  a  unitary  motor  response  to  the  complex  of 
retinal  sensations.  The  unity  of  response  stands,  indeed,  in 
sharpest  contrast  to  the  complexity  of  the  sensory  factors. 
The  organized  ability  to  coordinate  the  two  eyes  depends  on 
the  development  of  a  system  in  which  each  phase  of  experi- 
ence, without  losing  its  individual  reality,  is  taken  up  in  the 
single  unitary  system.  Space  and  the  coordinated  system 
of  ocular  movements  are  thus  seen  to  be  very  intimately 


COMBINATIONS  OF  SENSATIONS  187 

related.  The  complex  of  movements  has  a  unity  which  re- 
sults from  the  union  of  all  of  the  different  phases  of  binocular 
movement  into  a  single  coordinated  act.  Space  is  also  a 
system  in  which  every  point  has  a  certain  character  of  its 
own  and  at  the  same  time  has  characteristics  which  attach 
to  it  as  part  of  the  general  system. 

General  movements  as  conditions  of  fusion  of  retinal  sen- 
sations. In  the  second  place,  the  relation  of  visual  space 
perception  to  organized  behavior  becomes  clearer  when  it 
is  noticed  that  the  unity  of  visual  percepts  is  demanded  not 
only  in  the  coordinations  of  eye  movements  but  also  in  the 
coordinations  of  all  forms  of  behavior  which  are  guided  by 
vision.  If  one  reaches  out  his  hand  to  grasp  an  object,  his 
sensory  impressions  of  the  object  will  be  derived  from  two 
eyes,  but  the  reaction  to  be  effective  must  be  to  all  the 
sensations  at  once. 

Space  a  system  of  relations  developed  through  fusion. 
Our  treatments  of  space  perception  in  the  sphere  of  touch, 
hearing,  and  vision  bring  us  to  a  general  conclusion  that 
space  is  a  closed  system  built  up  through  the  fusion  of 
sensations  and,  further,  that  this  system  is  closely  related 
to  bodily  movements. 

Movement  and  mechanical  laws.  The  evidence  that 
there  is  a  close  relation  between  space  and  bodily  move- 
ment appears  in  the  fact  that  space  as  we  perceive  it  ex- 
presses those  mechanical  laws  which  govern  all  bodily 
movements.  Human  central  nervous  organization  and  re- 
lated muscular  movements  are,  from  the  very  nature  of 
mechanical  law  with  which  the  movements  must  comply, 
capable  of  only  a  very  definite  system  of  developments. 
One  cannot  move  his  hand  at  the  same  time  toward  the  left 
and  the  right.  Left  and  right  come  to  be,  therefore,  clearly 
distinguished  directions  in  the  organization  of  human  re- 
sponses to  sensations.  One  cannot  move  his  hand  back- 
ward and  forward  in  the  same  movement.  As  a  result,  all 


1 88  PSYCHOLOGY 

sensations  which  arc  to  be  related  to  movements  are  ulti- 
mately assigned  to  places  cither  in  front  or  behind,  i. 
in  both  positions  at  the  same  time.  The  child  begins  life 
without  a  thorough  organization  of  his  movements  and, 
correspondingly,  without  any  definite  spatial  forms  of  per- 
ception. The  two  develop  together  as  he  actively  adjusts 
himself  to  the  world  about  him.  Finally,  as  he  becomes 
master  of  his  movements  he  finds  that  his  perceptual  world 
also  has  taken  on  certain  definite  sequences  of  arrangement 
which  are  so  stable  and  systematic  and  so  harmonious  with 
what  he  comes  to  know  theoretically  of  mechanical  law  that 
he  can  study  the  spatial  system  as  he  finds  it  in  his  per- 
ceptual consciousness  and  relate  this  spatial  form  of  percep- 
tion to  his  science  of  mechanics  without  the  slightest  fear 
of  finding  any  incongruity  in  the  two  groups  of  facts.  It 
should  be  noted  here  again  that  such  a  complete  system  of 
space  is  much  more  than  a  series  of  sensations.  Sensation 
qualities  are  necessary  as  the  factors  with  which  the  indi- 
vidual must  deal ;  they  constitute  the  material  or  content  of 
experience,  but  the  spatial  form  of  perception  is  a  product 
of  perceptual  fusion.  Every  sensation  is  related  to  every 
other  not  because  of  its  quality  or  intensity  but  because 
every  sensation  must,  in  the  organization  of  impressions, 
take  its  place  in  a  serial  system  before  it  can  serve  any  defi- 
nite function  in  individual  life  or  have  any  clearly  marked 
place  in  consciousness. 

Perception  of  individual  objects.  There  are  many  forms 
of  perceptual  fusion  which  supplement  the  fusions  entering 
into  the  closed  system  of  space.  To  the  ordinary  observer 
an  object  recognized  through  the  two  senses  of  taste  and 
smell  is  so  unitary  in  character  that  he  does  not  realize  that 
any  fusion  of  discrete  sensations  has  taken  place.  By  a 
simple  experiment  one  can  easily  show  that  the  perception 
of  any  article  of  food  involves  a  number  of  distinct  sensa- 
tions. Let  the  observer  taste  of  some  familiar  substance, 


COMBINATIONS  OF  SENSATIONS  189 

such  as  coffee,  and  at  the  same  time,  by  holding  the  nose, 
prevent  the  air  from  coming  into  contact  with  the  olfactory 
organ,  and  coffee  becomes  a  sweet  liquid  with  little  or  no 
flavor ;  even  castor  oil  becomes  an  inoffensive  thick  oil 
under  like  conditions.  Why  is  it  that  in  ordinary  expe- 
rience tastes  and  odors  are  united  ?  It  is  because,  in  spite 
of  the  separation  of  the  gustatory  and  olfactory  organs,  there 
is  a  constant  demand  in  life  that  tastes  and  odors  shall  be 
used  together  in  guiding  conduct.  The  whole  inner  organi- 
zation of  the  individual  is  such  that  these  different  sensory 
qualities  have  a  joint  significance  for  perception  and  for 
behavior.  There  is  a  distinction  on  the  qualitative  side 
between  tastes  on  the  one  hand,  and  odors  on  the  other, 
because  the  sensory  organs  for  the  two  qualities  are  differ- 
ent ;  but  there  is  the  most  intimate  perceptual  fusion  to 
serve  as  a  guide  to  conduct. 

There  are  perceptual  fusions  in  every  sphere  of  sensa- 
tion quite  as  compact  as  those  of  taste  and  smell  and  as 
various  in  character  as  the  objects  in  the  world  about  us. 

Mere  coexistence  of  sensations  no  explanation  of  unity 
in  the  percepts  of  objects.  The  physiological  condition  of 
this  unity  in  the  perception  of  single  objects  is  not  to  be 
found  in  the  sensory  processes  themselves,  any  more  than 
was  the  physiological  condition  for  the  perception  of  space. 
The  sensory  processes  derived  from  things  are  very  differ- 
ent in  type  and  in  the  points  at  which  they  are  received 
into  the  central  nervous  system.  The  unity  of  perception 
is  not  to  be  accounted  for  by  the  fact  that  all  the  sensory 
excitations  are  in  the  brain  together,  for  not  all  of  the  sen- 
sations that  are  in  consciousness  at  the  same  time  fuse  into 
a  single  percept.  When  we  recognize  a  single  object  we 
do  so  by  distinguishing  it  from  its  surroundings  as  well  as 
by  fusing  its  various  attributes  into  a  single  percept.  Thus, 
one  recognizes  the  book  he  is  reading  by  distinguishing  it 
from  his  hands  and  from  the  bookcase  in  the  background. 


190  rs\( 

Range  of  fusion  determined  by  practical  considerations. 

Again.  as    in   tin-  treatment  of  the   fusion   which   leads  to 
space  perception,  we  must  appeal  to  the  central  coordina- 

which   arc-  worked  out  under  the  stress  of  pra« 
demands.    ( >nc  fuses  sensory  factors  into  the  percept  of  a 
thing  Ixrcausc  he  can  adjust  himself  to  certain  aspects  of 
experience  in  a  single  act.     Thus,  one  speaks  of  a  book- 
ami   its  contents  as  a  single  object  when  he  rn< 
wishes  t«>  name  over  the  articles  of  furniture  in  his  room. 
He    distinguishes   the  separate  books  as  objects  when   he 
wishes  to  take  them  out  and  use  them.    The  range 
experience  of  a  thing  is  thus  seen  to  depend  not  on  sen- 
sory processes  but  on  the  practical  motives  which  lead  to 
the   synthesis   of    more   or   less   comprehensive   groups  of 
these  sensations  into  single  phases  of  experience. 

Changes  in  percepts  through  repetition.  The  fusion  of 
factors  into  single  groups  becomes  easier  after  repetition. 
Thus  the  expert  rifleman  comes  to  recognize  at  once  the 
movement  of  his  game,  the  distance  of  the  game  from 
himself,  and  the  wind  which  will  influence  his  shot,  factors 
which  might  have  coexisted  indefinitely  without  being  fused. 
All  this  he  has  acquired  as  the  result  of  repeated  efforts  to 
shape  his  conduct  in  accordance  with  the  demands  of  his 
total  environment.  Indeed,  such  a  case  of  acquired  fusion  of 
widely  divergent  sensory  factors  may  very  frequently  involve 
in  its  earliest  stages  conscious  effort  to  adapt  action  to  whole- 
groups  of  sensations.  The  unity  is  made  more  and  more 
compact  as  repeated  efforts  are  undertaken  to  recognize  the 
factors  together,  so  that  ultimately  the  perceptual  unity,  which 
began  in  a  conscious  relating  of  factors,  becomes  a  synthetic 
unity  of  the  ordinary  type  ;  thus,  we  learn  to  see  pen  and 
hand  and  paper  together  when  we  learn  to  write,  until  all 
the  factors  which  enter  into  the  act  of  writing  and  its  con- 
scious control  are  unified,  and  the  final  consciousness  seems 
very  simple,  although  it  is  a  complex  of  many  factors. 


COMBINATIONS  OF  SENSATIONS  191 

Parallel  development  of  perception  and  habit.  Discus- 
sions of  perceptual  fusion  might  be  carried  over  directly  into 
the  discussion  of  habits  so  as  to  show  that  the  development 
of  organized  perception  and  the  development  of  organized 
activity  always  go  hand  in  hand.  The  training  of  eye  and 
hand  in  any  technical  art,  of  ear  and  vocal  cords  in  singing 
or  speaking,  of  ear  and  hand  in  playing  a  musical  instru- 
ment, go  together  in  practical  experience.  The  expert  in 
every  line  not  only  acts  more  skillfully  but  he  sees  or  hears 
more  skillfully  and  comprehensively.  Perception  is  discrimi- 
native and  complete  just  in  so  far  as  the  factors  of  experi- 
ence are  organized  into  wholes  appropriate  for  individual 
reaction.  Our  present  purposes,  however,  can  be  fully  satis- 
fied without  a  complete  study  of  habits.  The  perceptual 
fusion  involved  in  the  recognition  of  an  object  is  one  phase 
of  organization  ;  habit  is  an  expression  of  this  organization 
and  will  be  taken  up  in  a  separate,  later  chapter. 

Time  as  a  general  form  of  experience.  Before  leaving 
the  subject  of  perception  it  is  important  that  we  consider 
briefly  a  form  of  arrangement  which  has  often  been  re- 
garded as  similar  in  character  to  the  space  form  ;  namely, 
time.  Time,  like  space,  involves  a  relation  between  several 
factors  of  experience.  Like  space,  it  is  not  a  sensation 
quality.  It  is  even  more  general  in  character  than  space, 
for  it  is  not  merely  a  form  of  perception  ;  it  is  also,  and 
indeed  chiefly,  a  form  of  the  indirect,  or  memory,  experi- 
ences. A  percept  is  always  in  the  time  series,  but  it  is 
always  in  that  portion  of  the  time  series  which  we  call 
"  the  present."  It  will,  accordingly,  be  appropriate  for  us 
to  discuss  in  this  connection  some  of  the  attributes  of  "  the 
present,"  leaving  the  other  phases  of  time  consciousness  to 
be  taken  up  in  connection  with  memory. 

Experimental  determination  of  the  scope  of  "  the 
present."  "  The  present "  is  not  a  single  point  of  experi- 
ence ;  it  is  a  group  of  experiences.  Some  experimental 


192  PSYCHOLOGY 

evidence  as  to  the  possible  length  of  "the  present "  may 
be  gained  as  follows:  Tap  rapidly  on  the  table  at  ; 
vals  of  half  a  second  or  less,  producing  a  series  of  sounds, 
and  find  how  many  taps  of  this  kind  can  be  grouped  into 
a  single  easily  apprehended  unity.  The  observer  will  have 
little  difficulty  in  determining  the  limit  of  such  a  scries  if 
he  will  simply  listen  to  the  taps  and  refrain  from  counting. 
A  short  series  of  five  or  six  taps  will  leave  behind  in 
consciousness  a  feeling  of  perfect  definitcncss  and  ease  of 
apprehension.  If  such  a  series  is  exactly  repeated,  or 
second  slightly  different  series  is  sounded,  the  observer 
will  be  in  no  doubt  as  to  the  likeness  or  unlikeness  of 
the  two  series.  If,  on  the  other  hand,  a  series  of  twenty 
or  thirty  taps  is  sounded,  the  observer  will  recognize  that 
at  a  certain  point  in  the  series  a  state  of  confusion  sets  in. 
The  scries  is  no  longer  apprehended  as  a  unity,  but  has 
a  vaguely  defined  massiveness  which  seems  to  elude  the 
mental  grasp. 

Scope  of  "  the  present  "  and  its  varying  conditions.  The 
ability  of  the  observer  to  group  together  a  series  of  experi- 
ences is  radically  modified  when  the  series  itself  is  changed. 
Thus,  if  every  third  tap  is  made  stronger  than  the  others, 
or  if  it  is  given  a  slightly  different  quality,  as  in  a  series 
of  musical  notes,  the  scope  of  the  immediately  recognized 
group  will  be  much  increased.  If  the  taps  come  irregu- 
larly, either  in  point  of  interval  or  in  point  of  intensity  or 
quality,  the  scope  of  the  unitary  group  will  be  decreased. 

Time  relations  in  verse  and  related  systems  of  experience. 
All  these  facts  appear  in  such  practical  forms  of  time  per- 
ception as  those  which  are  utilized  in  making  up  English 
verse.  The  recognition  of  the  successive  feet  in  poetry  is 
facilitated  by  grouping  the  sounds  into  simple  compact 
groups.  The  character  of  each  group  is  determined  by 
variations  in  intensity,  quality,  and  content  in  such  a 
large  number  of  ways  as  to  satisfy  the  demand  for  novelty 


COMBINATIONS  OF  SENSATIONS  193 

in  experience,  while  at  the  same  time  retaining  very  fully 
the  characteristics  necessary  for  temporal  uniformity  in  the 
successive  groups  of  factors. 

Time  arrangement  as  conditioned  by  the  rhythmical 
changes  in  nervous  processes.  To  find  a  precise  physio- 
logical basis  for  the  time  grouping  of  experience  will 
require  the  discovery  of  processes  which  are,  much  more 
general  than  those  which  constitute  the  physiological  basis 
for  space  perception  and  for  general  perceptual  unity  as 
exhibited  in  the  recognition  of  objects.  Indeed,  we  must 
go  far  enough,  as  indicated  above,  to  recognize  that  the 
conditions  of  temporal  discrimination  are  involved  in  indi- 
rect memory  processes  even  more  than  in  perception. 
Such  a  general  characteristic  is  to  be  found  in  the  fact 
that  all  nervous  processes  are  constantly  fluctuating  .  in 
intensity  because  the  inner  nervous  condition  is  never 
in  equilibrium.  The  nervous  condition  is  a  living  process, 
now  rising  to  a  higher  intensity,  now  declining  to  a  low 
intensity.  This  can  be  seen  if  an  observer  will  pick  out 
in  the  constellation  Pleiades  a  faint  star  which  is  just 
visible,  and  watch  it  for  a  time.  He  will  find  that  it  disap- 
pears and  then  reappears  for  an  interval,  only  to  disappear 
again.  The  rhythmical  change  is  here  so  complete  that 
it  is  perceived  as  a  change  in  the  object.  A  like  fluctu- 
ation of  intensity  is  present  in  all  sensory  impressions, 
even  if  the  sensation  is  so  strong  that  its  decrease  in 
intensity  does  not  cause  it  to  disappear  entirely. 

Perception  more  than  the  flux  of  sensations.  In  addition 
to  the  fluctuations  in  experience  which  result  from  the  con- 
ditions in  the  nervous  system,  there  are  changes  which  arise 
from  the  relation  of  the  observer  to  the  object.  For  example, 
as  one  makes  his  way  down  the  street  he  sees  some  object 
for  a  moment  and  then  loses  sight  of  it  until  he  comes 
once  more  to  a  point  from  which  he  can  observe  it.  In  all 
this  flux  of  experience  action  must  be  based  on  a  recognition 


194  PSYCHOLOGY 

of   the   pern.  of  objects   which    transcends   present 

sensations.    We  project  our  fluctuating  sensations   into  a 
series   which    provides   for   time   changes   whuh    arc    not 
changes  in  the  thirfgs  themselves.    Thus  we  find  nc\\ 
dence  that  experience  is  organized  out  of  s<  I  but 

goes  far   beyond   sensory  qualities   and   intensities   in  the 
attributes  which    it  exhibits.     Time   is  not  a  i  ;   it 

is  a  form  in  which  sensations  ;ire  held  because  the  mind 
recognizes  in  objeofs  a  permanency  which  extends  beyond 
present  personal  <j»periencc. 
f 

SUMMARY 

Discussions  of  perception.  The  discussion  of  perception  may 
be  dosed  with  a  brief  summary.  Perception  involves,  first,  a 
spatial  order;  second,  the  compact  fusion  of  sensations  into 
percepts  of  separate  objects  in  the  world ;  and  third,  the  begin- 
ning of  a  temporal  order.  The  spatial  arrangement  is  intimately 
connected  with  movement,  being  the  arrangement  given  to  sen- 
sory factors  under  the  mechanical  demands  for  characteristically 
different  reactions  to  different  sensory  factprs  in  the  total  mass 
of  experience.  Fusion  of  sensations  into  separate  recognitions  of 
objects  is,  like  spatial  arrangement,  related  to  activity,  for  all 
those  phases  of  sensory  experience  will  be  fused  together  which 
require  one  and  the  same  response.  Finally,  time  recognition 
depends  on  the  flux  in  experience  which  comes  to  be  recognized 
as  a  flux  not  interfering  with  the  permanency  of  objects. 


CHAPTER  IX 

HABITS 

Organic  retentiveness.  Up  to  this  point  only  casual  ref- 
erence has  been  made  to  the  fact  that  the  nervous  system 
is  constantly  undergoing  structural  changes  as  a  result  of 
use.  When  an  impulse  passes  from  cell  to  cell,  it  leaves 
behind  a  path  which  makes  it  easier  for  some  new  impulse 
at  a  later  period  to  pass  along  the  same  course.  In  this  way 
it  is  also  made  easier  for  later  impulses  to  be  brought 
together.  Very  soon  the  effects  of  past  experience  become 
so  complicated  that  it  is  impossible  to  picture  them  in 
detail.  Thus,  when  one  learns  the  name  of  an  object, 
there  must  be  traced  through  the  nervous  system  a  series 
of  paths  which  make  it  possible  in  all  later  experience  for 
the  percept  of  that  object  to  arouse  the  tendency  to  articu- 
late the  name.  Or,  to  take  another  type  of  example,  when 
one  has  thought  of  Europe  and  Asia  as  parts  of  a  great 
continental  mass,  it  becomes  easier  in  all  future  experience 
to  couple  these  two  ideas  in  thought. 

The  facts  referred  to  in  the  last  paragraph  are  grouped 
together  under  such  general  terms  as  "  organic  memory  "  or 
"  retentiveness."  It  is  one  of  the  most  important  facts  about 
the  nervous  system  that  it  is  highly  retentive.  As  a  result 
of  this  retentiveness,  present  action  of  any  part  of  the 
nervous  system  is  explicable  only  in  small  measure  by 
the  impressions  of  the  moment.  The  present  impression 
is  received  into  a  network  of  paths  which  carry  the  im- 
pulse here  and  there  in  accordance  with  past  experiences 
through  traces  left  behind  by  such  experiences. 

195 


196  PSYCHOLOGY 

Remoter  conditions  of  retention.  Considered  in  a  large 
way,  all  structures  of  the  nervous  system  are  the  results  of 
past  development.  The  coordinations  which  the  child  in- 
herits result  from  racial  experiences,  and  no  individual  can 
the  world  without  reflecting  in  all  of  his  instinctive 
attitudes  the  fundamental  experiences  of  his  ancestors. 

Ordinarily  we  do  not  think  of  these  remoter  effects  of 
experience.    We  use  the  terms  "  memory  "  and  "  retention  " 
to  refer  to  those  phases  of  personal  experience  which  we 
sciously  connect  with  our  own  past  contact  with  things 
people.    When  the  ordinary  man  uses  the  term  "  memory," 
he  thinks  of  a  reinstatement  as  nearly  as  possible  of  some 
situation  experienced  at  an  earlier  date.     One   remembers 
what  he  saw  and  did  yesterday.    For  the  psychologist  this 
is  only  one  case  of  retention  and  revival.    From  the  d« 
of  yesterday  there  come  over  into  to-day  many  influt 
which  are  difficult  to  observe  directly.    There  is  skill  of 
hand  which  is  the  product  of  a  slow  and  systematic  learn- 
ing process ;  there  is  accuracy  of  spatial  reference  which 
makes  it  possible  for  the  individual  to  put  his  hand  with 
precision  on  the  object  before  him  or  at  the  right  or  left. 
There  are  modes  of  attention  ;  there  are  attitudes  of  fear 
and  anger,  all  of  which  come  out  of  the  past  development 
of  the  individual  but  are  ordinarily  not  recognized  as  due 
to  nervous  retention. 

Before  taking  up  the  cases  of  memory  which  are  usually 
recognized  as  coming  under  that  name,  it  will  be  well  to 
study  those  less  noticed  forms  of  organization  which  bring 
the  past  into  the  present  and  affect  the  present  without 
being  recognized  through  introspection. 

Instincts.  The  simplest  cases  of  this  type  are  the  instincts. 
As  was  pointed  out  in  an  earlier  chapter,  even-  individual 
is  born  with  certain  main  outlines  of  his  nervous  structure 
provided  through  inheritance,  exactly  as  the  other  structures  of 
his  body  are  provided  through  inheritance.  If  an  individual 


HABITS  197 

has  arms  and  legs,  he  will  also  have  the  nerve  fibers  to 
connect  the  muscles  of  these  extremities  with  the  spinal 
cord.  The  structure  of  the  sense  organs  is  also  provided 
through  inheritance,  and,  as  has  been  made  clear  in  earlier, 
discussions,  there  is  little  or  no  change  in  the  character  of 
these  organs  in  the  course  of  individual  experience.  Inherit- 
ance, however,  goes  even  further  than  to  provide  these  main 
structures.  The  central  organs  themselves  are,  to  some  ex- 
tent, mapped  out  at  the  beginning  of  individual  life.  The 
result  of  this  central  organization  is  that  at  the  time  of  birth 
the  muscles  of  the  body  are  not  merely  under  the  general 
control  of  the  nervous  system,  they  are  under  the  control 
of  organized  centers  which  are  able,  to  a  certain  extent,  to 
coordinate  the  activities  of  different  parts  of  the  body. 

Protective  instincts.  Illustrations  of  instincts  occur  in 
the  life  of  any  animal  and  in  the  early  life  of  human  infants. 
For  example,  if  a  young  bird  hears  a  loud  sound,  this  sound 
not  only  discharges  itself  through  the  nervous  system,  but 
because  of  the  internal  organization  of  the  nervous  system 
the  sound  will  discharge  itself  into  the  muscles  of  the  whole 
body  in  that  form  of  behavior  commonly  described  as  feign- 
ing death.  The  individual  bird  does  not  recognize  the 
significance  or  value  of  its  behavior,  at  least  the  first  time 
it  executes  it.  The  act  can  therefore  not  be  explained  as 
due  in  any  way  to  individual  intelligence.  Furthermore,  the 
same  form  of  action  appears  in  all  members  of  the  species. 
The  organization  which  controls  the  activity  has  been  worked 
out  in  the  course  of  the  experience  of  the  bird's  ancestors 
as  a  form  of  protective  movement  to  be  put  into  operation 
whenever  the  animal  is  threatened  by  an  approaching  enemy. 
To  say  that  the  young  bird  which  performs  this  movement 
is  cognizant  of  danger  and  assumes  an  appropriate  attitude 
would  be  to  invert  the  true  relations  exhibited  in  the  situa- 
tion. The  mode  of  behavior  is  immediate  and  depends 
directly  upon  the  external  stimulation  plus  the  inherited 


PSY<  ll«  'I  <)GY 

organization.  The  attitude  •  I  feat  results  from  the  :i 
which  takes  place  without  the  animal's  control  or  ch 
1  In-  inner  expcn  ]ust  as  much  determined 

through  heredity  as  is  the  ability  to  hear  the  sound  through 
tin-  ear  or  the  ability  to  resjxind  to  the  sound  with  the 
iiuisi  U-x  ,.f  the  body. 

Food-taking  instinct.    <  uhcr  upical  illustrations  • 

instinctive  niodi-s  of  U-havior  ma\  IK-  drawn  from  a 
study  of  the  human  infant.  One  of  the  most  fundamental 
instincts  of  the  infant  is  th*  instinct  of  sucking.  Any  \min^ 
mammal  resjxuuls  to  a  small  object  placed  lx-twcen  its 
lips  by  a  complex  form  of  reaction  which  nature  has  pro- 
vided as  the  only  possible  means  of  supj>orting  the  animal's 
life  during  a  period  when  individual  cxjx-iicncc  is  not 
sufficiently  mature  to  guide  it  in  securing  its  own  food.  The 
form  of  consciousness  which  accompanies  this  instin 
behavior  is,  of  course,  a  matter  of  speculation,  but  it  • 
highly  probable  that  the  exjx-rience  of  the  infant  is  one  of 
emotional  excitement  and  of  satisfaction  when  the  act  finds 
some  appropriate  object  on  which  to  express  itself. 

Instincts  established  through  selection.  The  process  by 
which  the  instincts  have  been  evolved  is  most  elaborate.  In 
the  later  stages  of  animal  evolution  those  members  of  a 
species  which  do  not  exhibit  the  highly  organized  instincts 
of  protection  and  food-taking  perish.  It  is  easy  to  see  how 
the  instincts  are  perpetuated  through  natural  selection.  In 
somewhat  the  same  fashion  we  can  imagine  how,  through 
a  long  regressive  scries,  those  nervous  systems  were  gradu- 
ally selected  which  provided  the  forms  of  reaction  most 
favorable  to  the  preservation  of  life. 

Delayed  instincts  common.  In  treating  of  human  instincts 
the  matter  is  somewhat  complicated  by  the  fact  that  a  great 
many  instincts  are  present  only  in  incipient  forms  at  the 
beginning  of  life  and  are  fully  matured  at  a  relatively  late 
period.  A  good  illustration  of  such  a  delayed  instinct  is 


HABITS  199 

found  in  the  tendency  of  the  young  child  to  walk.  That 
this  tendency  is  inherited  is  shown  by  the  fact  that  it  will 
mature,  even  if  there  is  little  or  no  individual  practice.  The 
common  development  of  the  young  child  is  a  mixture  of 
maturing  instincts  and  ambitious  efforts  on  the  part  of 
the  child  himself  and  of  those  surrounding  him  to  hasten 
the  development  which  would  naturally  come,  even  if  no 
exertions  were  made  in  that  direction.  Certain  interesting 
cases  are  on  record  which  show  that  children  who  for  one 
reason  or  another  had  never  made  any  individual  effort  to 
mature  this  mode  of  activity  suddenly  exhibited  it  under 
suitable  conditions  in  a  fully  developed  form.  Young  animals 
have  frequently  been  experimented  upon  in  a  way  to  show 
that  their  modes  of  locomotion  are  wholly  instinctive,  even 
though  locomotion  develops  only  at  a  relatively  late  period 
in  life.  Thus  young  birds  which  have  been  incubated  in 
isolation  and  have  been  caged  until  they  reached  full 
maturity  will  fly  with  the  natural  mode  of  flight  of  their 
species  as  soon  as  they  are  liberated. 

Impossibility  of  distinguishing  instincts  from  later-acquired 
forms  of  behavior.  As  there  are  instinctive  modes  of  be- 
havior which  develop  somewhat  slowly  during  the  early  years 
of  life,  it  is  impossible  to  draw  a  line  and  say  that  every 
form  of  activity  which  matures  after  a  certain  period  is  in- 
dependent of  direct  hereditary  organizations.  It  is  equally 
impossible  to  say,  on  the  other  hand,  that  the  inherited 
tracts  in  the  nervous  system  are  in  no  wise  modified  in  the 
course  of  individual  experience.  Indeed,  it  is  always  true 
that  on  the  foundation  of  inherited  coordinations  there  is 
built  up  a  system  of  refinements  and  modifications  which 
constitute  the  characteristic  mark  of  the  individual. 

Habits  from  instincts  and  from  independent  conditions. 
Instincts  are  sometimes  simplified  in  the  course  of  use ;  at 
other  times  they  are  united  into  larger  systems  of  action  or 
are  broken  up  into  their  elements  and  recombined  into  new 


200  PSYCHOLOGY 

<>f  0'inposite  activity.     \\V  turn,  then,  to  the  co: 
cration  of  these  processes  of  activity  which  arc  i 
instincts  merely  as  outgrowths  and  may  therefore  be  treated 
as  the  products  of  individual  Those  modes  of 

behavior  which  depend  upon  individual  experience  arc  ( 
habits.    In  order  to  make  clear  the  relation  of  habit  t 
si  i  net,  it  should  be  pointed  out  that  not  all   habits  grow 
directly  out  of  single  well-defined  instincts.     For  the  pur- 
poses of  our  discussion  two  classes  of  habits  may  be  dis- 
tinguished :   first,  there  are   habits   which   develop   out  of 
instincts ;    second,    there   are    habits  which    develop   by  a 
process  of  selection  from  among  the  diffuse  activities  which 
appear  whenever  there  is  no  definite  mode  of  instir. 
behavior  which  se:  i  foundation  for  development.    \Ve 

may  refer  to  these  two  types  of  habits  as  habits  developed 
from  instincts  and  habits  developed  from  diffusion. 

Development  of  habit  through  conflict  of  instincts.  An 
illustration  of  a  habit  developed  from  instincts  is  found  in 
the  case  in  which  a  child  develops  a  certain  definite  attitude 
toward  certain  animals.  This  attitude  of  the  child  can  in 
many  cases  be  shown  to  have  originated  out  of  a  conflict  be- 
tween two  tendencies.  There  are  two  fundamental  instinc- 
tive tendencies  in  every  child,  indeed  in  every  young  animal. 
Every  young  animal  tends,  on  the  one  hand,  to  run  away 
from  any  strange  or  unusually  intense  stimulation.  A  large 
object  moving  toward  the  eyes,  a  loud  sound  attacking  the 
auditory  organs,  or  a  strange  odor  or  taste  will  stir  up  in  a 
young  animal  a  mode  of  action  of  the  protective  type.  Then- 
is,  on  the  other  hand,  among  all  of  the  higher  animals  an 
instinct  toward  contact  with  members  of  the  same  sp< 
and  with  related  forms  of  animal  life.  Thus,  young  birds 
naturally  tend  to  keep  close  to  any  member  of  their  spi 
and  to  other  objects  which  are  in  any  way  similar  to  mem- 
bers of  their  own  species.  So  also  do  young  mammals. 
Young  puppies  and  young  kittens  are  extremely  fond  of 


HABITS  201 

companionship,  and  even  certain  of  the  more  solitary  ani- 
mals naturally  herd  in  packs  or  in  small  groups,  especially 
when  young.  The  human  infant  exhibits  both  of  the  two 
fundamental  instinctive  tendencies  which  have  just  been 
described.  When,  accordingly,  the  child  is  for  the  first  time 
confronted  by  an  animal,  its  reaction  may  be  one  of  with- 
drawal or  one  of  friendly  contact.  Which  of  the  two  natural 
tendencies  is  actually  selected  will  depend  upon  a  variety  of 
circumstances.  If  the  instinct  of  flight  or  protective  activity 
is  strong,  either  because  the  individual  child  is  disposed  to 
react  in  this  way  more  emphatically  than  in  the  direction  of 
social  contact  or  if  the  instinct  of  protection  is  rendered 
especially  pronounced  by  some  accident  of  excessive  external 
stimulation  at  the  particular  moment,  then  the  instinct  of 
fear  will  dominate  and  the  social  instinct  will  be  suppressed. 
In  such  a  case  the  specialized  habit  will  begin  to  form  in 
the  general  direction  of  fear.  Sometimes  the  attitude  is  so 
thoroughly  determined  by  the  first  contact  with  the  animal 
that  all  through  life  the  individual  tends  to  follow  the  initial 
impulse  received  at  the  first  experience.  There  are  persons 
who  have  a  very  strong  attitude  .of  fear  for  cats  and  dogs, 
which  attitude  has  become  a  fixed  individual  habit  after 
being  selected  from  among  the  various  possible  instinctive 
modes  of  response  which  existed  through  inheritance  at  the 
beginning  of  life. 

Nervous  development  concerned  in  the  selection  of  in- 
stincts. The  nervous  mechanism  involved  in  a  habit  which 
has  resulted  from  selection  among  instincts  is  relatively  easy 
to  explain.  We  need  only  to  assume  that  the  stimulation 
which  is  given  at  the  first  experience  has  two  possible  lines 
of  discharge,  either  one  of  which  would  be  through  a  well- 
defined  instinctive  tract.  The  conditions  of  the  first  en- 
counter carry  the  stimulation  in  question  into  one  of  the 
two  instinctive  channels,  and  thereafter  this  selected  channel 
becomes  the  natural  and  easy  path  of  discharge  for  the 


202  PSYCHOLOGY 

stimulus  whenever  it  recurs.  The  habit  is.  accordingly,  de- 
pendent upon  individual  experience  only  in  the  one  respect 
that  individual  experience  determines  which  of  the  possible 
instincts  shall  be  selected. 

Habit  as  a  modified  instinct.  A  second  somewhat  differ- 
ent type  of  derivation  of  habit  from  instinct  is  found  in  cases 
in  which  the  final  mode  of  ai  not  along  the  line  of 

any  single  instinct,  but  is  a  compromise  in  which  one  instinct 
is  modified  by  conflict  with  other  instinctive  tendencies. 
Suppose,  for  example,  that  the  human  infant  who  naturally 
tends  to  be  afraid  of  an  animal  is  encouraged  by  circum- 
stances to  assume  a  friendly  attitude  toward  the  animal  of 
which  he  is  naturally  afraid.  His  attitude  and  mode  of  re- 
action may  be  modified  to  a  greater  or  less  extent,  so  that 
instead  of  expressing  the  full  tendency  of  his  instinct  to  run 
Y.  he  may  have  merely  a  suppressed  internal  recoil  from 
the  animal,  while  all  of  his  grosser  protective  movements 
are  modified.  Many  of  the  human  instincts  are  probably 
thus  somewhat  reduced  in  intensity  and  in  their  form  of  ex- 
pression. Darwin  argued  at  length  that  the  expressions  of 
human  and  animal  emotions  are  in  many  cases  simply 
reduced  instinctive  forms  of  behavior.  Many  of  the  facial 
expressions  in  human  beings  are,  according  to  his  view, 
remains  of  early  forms  of  activity  in  the  jaw  and  mouth 
muscles,  which  once  accompanied  real  combat.  The  changes 
in  circulation  and  respiration  which  come  with  fear  and 
embarrassment  are  to  be  regarded  as  partial  expressions  of 
certain  fundamental  instincts.  For  example,  when  we  are 
frightened  there  is  for  an  instant  a  pause  in  all  the  internal 
activities  preparatory  to  the  violent  activities  necessary  to 
flight,  and  after  this  first  pause  there  comes  a  rapid  beating 
of  the  heart  which  originally  accompanied  flight.  When  in 
mature  life  one  refuses  to  indulge  in  flight,  he  may,  never- 
theless, have  all  the  internal  activities.  If,  however,  he 
persists  in  refusing  to  run,  the  inherited  tendency  may, 


HABITS  203 

through  this  fact,  be  gradually  overcome  even  to  the  point 
of  disappearance. 

Importance  of  heredity  in  explaining  consciousness.  Such 
examples  as  these  tend  to  emphasize  heredity.  The  indi- 
vidual is  seen  to  begin-  life  with  a  large  stock  of  possible 
habits  and  instinctive  attitudes.  His  final  attitudes  are  deter- 
mined in  kind  and  degree  by  the  circumstances  of  individual 
life,  but  a  great  number  of  the  fundamental  possibilities  in 
human  nature  are  given  at  the  beginning  of  life.  We  may 
say,  therefore,  that  an  individual  is  born  with  a  large  stock 
of  attitudes  quite  as  much  as  with  a  large  supply  of  organs 
of  sense  -  and  forms  of  possible  sensory  experience.  The  in- 
herited attitudes  are  not  specific  in  their  application  until 
after  individual  experience  has  worked  out  the  application, 
but  they  are  native  and  explicable  only  in  terms  that  recog- 
nize their  fundamentally  hereditary  character. 

Diffusion  a  mark  of  lack  of  organization.  Turning  now 
from  the  habits  which  are  developed  through  the  selection 
and  modification  of  instincts,  we  come  to  the  habits  which 
cannot  properly  be  traced  to  any  single  instinct  or  group  of 
instincts.  Let  us  suppose  that  a  stimulus  or  a  combination 
of  stimulations  is  introduced  into  the  nervous  system  of  the 
child  but  finds  no  specific  channel  of  discharge  open  to  it 
through  inherited  organization.  This  stimulation  will  pro- 
duce an  excitation  which  will  be  very  widely  distributed 
throughout  the  whole  nervous  system,  because  it  has  no 
specific  channel  of  discharge  and  because,  as  free  energy, 
it  must  be  transmitted  through  the  nervous  system  until  it 
finds  a  discharge  into  the  active  organs.  The  stimulation 
will  ultimately  issue  through  the  avenues  of  motor  dis- 
charge into  the  active  organs  o<:  the  body,  but  instead  of 
issuing  in  a  well-coordinated  series  it  will  be  distributed 
diffusely  and  irregularly  and  will  affect  a  great  number  of 
muscles.  An  example  of  the  diffuse  distribution  of  stimula- 
tion in  mature  life  is  seen  when  one  is  suddenly  startled  by 


204  (  HOLQGY 

an  unexpected  loud  noise,  and  there  follows  a  general 

traction  uf  the  muscles  throughout  t!.  ..i  h  a 

strong  stimulus  I  rr  all  of  the  bounds  of  organization 

in  the  central  nervous  s>fstem  and  is  distributed  dil: 
throughout  the  body.  A  diffuse  distribution  of  the  stimula- 
tion is  clearly  a  disadvantage  to  the  individual.  The  state 
of  the  organism  after  the  stimulation  is  such  that  the  indi- 
vidual is  not  \\rll  adapted  to  his  environment,  his  acti 
are  not  concentrated  in  any  single  direction,  and  he  is  alto 
^i-ther  unprepared  to  meet  the  future  demands  which  the 
stimulation  may  impose  upon  him.  Furthermore,  it  can 
easily  be  observed  that  the  mental  attitude  which  accom- 
panies such  diffuse  activity  is  quite  as  unorganized  as  the 
bodily  attitude,  and  this,  also,  is  an  intolerable  condition  for 
any  individual.  The  process  of  modifying  such  a  diffuse 
tion,  of  developing  definite  and  precise  attitudes  on  the 
mental  side  and  well-coordinated  movements  on  the  physical 
side,  is  a  long,  complex  process,  carried  out  by  the  organism 
and  by  consciousness  with  the  delays  and  complications 
which  appear  in  every  process  of  natural  development. 
Development  of  habit  from  diffusion.  If  we  take  a  1 
of  activity  which  has  little  or  no  instinctive  background,  such 
as  the  activity  involved  in  writing,  and  observe  the  early 
stages  of  the  effort  to  develop  this  type  of  activity  into  a 
habit,  we  discover  the  characteristics  of  a  diffuse  activity. 
It  will  be  found,  first,  that  movement  is  excessive  in  both 
extent  and  intensity.  The  child  who  is  learning  to  write 
moves  not  only  the  necessary  muscles  of  the  fingers  and 
hand  directly  engaged  in  writing,  but  the  muscles  of  the 
other  hand  as  well.  He  also  moves  the  muscles  of  the  face. 
The  diffusion  of  the  excitation  throughout  the  whole  organ- 
ism is  one  of  the  most  obvious  facts  tc  be  observed  in  such 
a  case.  In  the  secona  place,  the  elements  of  movement 
which  are  present  are  not  coordinated  into  harmonious 
wholes.  The  various  muscular  contractions  involved  in  the 


HABITS  205 

earliest  attempts  at  writing  seldom  enter  into  such  relations 
that  there  is  economy  in  their  several  activities.  This  will 
be  apparent  if  one  observes  the  way  in  which  the  fingers 
and  the  hand  act  during  the  child's  formation  of  series  of 
letters.  There  must  always  be  a  movement  of  the  hand 
during  writing  to  carry  the  fingers  across  the  page.  In  the 
child's  writing  the  fingers  are  used  as  long  as  they  can  be 
used  without  any  cooperating  hand  movement.  The  hand 
is  brought  into  play  only  after  the  fingers  have  become  so 
cramped  that  they  can  no  longer  make  lines.  When  this 
cramping  of  the  fingers  reaches  such  a  point  that  it  can  go 
no  farther,  the  finger  movement  is  altogether  suspended  for 
a  moment  and  the  hand  is  moved  forward  in  a  distinct  and 
relatively  separate  act.  The  writing  then  proceeds  as  before, 
the  fingers  being  used  quite  to  the  exclusion  of  the  hand. 
This  obvious  lack  of  combined  activity  of  the  hand  and 
fingers  illustrates  a  general  fact  which  is  also  exhibited  by 
the  incoordination  of  the  learner's  several  fingers  in  relation 
to  one  another.  The  thumb  and  first  finger  do  not  at  the 
outset  cooperate  with  each  other  in  the  harmonious  way  in 
which  they  should.  For  example,  at  the  beginning  of  an 
upward  stroke,  as  in  the  written  letter  /,  the  first  finger 
presses  downward  against  the  pencil  or  pen  more  vigorously 
than  is  necessary  and,  as  a  result,  the  thumb  is  called  upon 
to  do  an  excess  of  work  in  order  to  overcome  the  unneces- 
sary downward  pressure  of  the  first  finger.  There  is  thus  a 
lack  of  harmony  and  even  a  certain  degree  of  interference 
in  the  organs  which  are  directly  involved  in  the  activity. 
The  explanation  of  diffusion  and  incoordination  at  the  be- 
ginning of  development  is  similar  to  the  explanation  of  the 
general  diffusion  of  the  activity  throughout  the  whole  muscu- 
lar system  in  the  case  of  a  sudden  loud  noise.  In  both  cases 
the  nervous  impulses  which  excite  the  muscles  do  not  follow 
definite  channels.  In  the  case  now  under  consideration  the 
channels  are  not  yet  developed,  while  in  the  case  of  the  loud 


206 

sound  they  are  not  able  to  confine  the  strong  discharge  to 
definite  p. 

Undeveloped  movements.  Another  characteristic  \>i  an 
undeveloped  movement  is  one  which  is  closely  related  to  its 
incourdi nation,  and  consists  in  the  fact  that  the  various  phases 
of  movement  are  all  of  brief  duration,  not  being  united 
each  other  into  a  continuous  series.  If  one  examines  the 
writing  of  a  child,  he  finds  that  the  lines,  instead  of  being 
continuous,  fluent  lines,  are  made  up  of  short,  irregular  parts. 
The  direction  of  the  movement  in  these  short,  irregular  parts 
is  very  frequently  away  from  the  general  direction  which  the 
movement  should  follow.  \Ve  may  say  that  the  movement 
is  a  succession  of  efforts  to  produce  the  line  rather  than  a 
sequence  of  coordinated  muscular  contractions  appropriate 
to  the  general  movement.  When  the  movement  develops, 
as  it  does  after  practice,  the  different  elements  are  bound 
together  in  such  a  way  that  their  sequence  cannot  be  detected  ; 
they  are  no  longer  separate  factors.  The  adult  who  begins 
to  write  the  letter  /  does  not  make  a  series  of  separate  rr. 
ments  as  the  pencil  is  carried  along  the  upward  stroke.  I  le 
does,  however,  make  a  series  of  muscular  contractions.  The 
transition  from  the  irregular  succession  of  separate  move- 
ments to  a  series  of  contractions  constituting  phases  of  a 
single  complex  activity,  which,  however,  is  thoroughly  uni- 
fied, results  from  the  coupling  together  of  a  series  of  ner 
tracts  which  provide  for  the  proper  temporal  distribution  of 
the  motor  excitation. 

Diffusion  analogous  to  all  forms  of  overproduction.  It  is 
clear  from  the  foregoing  study  of  the  characteristics  of  an 
undeveloped  activity  that  nature  approaches  this  problem  of 
development  in  the  same  way  in  which  all  the  problems  of 
development  are  approached  ;  namely,  through  excessive  pro- 
ductions and  selection  of  the  proper  elements.  Since  the  child 
does  not  have  the  proper  nervous  organization  to  control 
his  movements,  nature  has  provided  that  he  shall  make  a 


HABITS  207 

superabundance  of  movements  involving  all  of  the  different 
parts  of  the  body,  even  those  which  are  not  directly  con- 
cerned in  the  final  activity.  If,  in  this  excess  of  movement, 
certain  factors  accomplish  the  end  toward  which  the  indi- 
vidual is  working,  these  successful  constituents  of  movement 
will  gradually  be  emphasized  and  the  unsuccessful  constitu- 
ents will  gradually  be  eliminated,  until  finally  diffusion  gives 
way  to  a  limited  number  of  precise  and  well-defined  combina- 
tions of  activity.  If  the  selected  factors  are  repeated  together 
a  sufficient  number  of  times,  the  nervous  activities  involved 
in  each  particular  phase  of  the  movement  gradually  become 
connected  with  each  other. 

Conscious  correlates  of  habit.  The  conscious  accompani- 
ments of  action  which  has  grown  habitual  are  easily  described. 
There  is  a  feeling  of  familiarity  when  one  is  trained  to  respond 
to  sensations ;  there  is  a  definiteness  of  discrimination  which 
makes  one's  percepts  sure  and  clear.  Too  often  the  psychology 
of  habit  has  been  guilty  of  the  statement  that  habituation  leads 
to  unconsciousness.  This  is  not  the  case.  When  we  can  deal 
skillfully  with  any  situation,  we  have  an  attitude  of  attention 
and  of  assurance  wholly  different  from  the  attitude  of  indefi- 
nite excitement  which  accompanies  diffusion.  The  skillful 
man  is  the  discerning  man  ;  his  discernments  may  disregard 
certain  factors  and  emphasize  others,  but,  on  the  whole, 
he  will  give  attention  to  that  which  is  most  important  in 
guiding  action. 

Instinct,  habit,  and  mental  attitudes.  The  reader  will  be 
able  without  detailed  discussion  to  see  the  relation  of  this 
chapter  to  the  earlier  chapter  which  deals  with  mental  atti- 
tudes. All  mental  life  exhibits  natural  likes  and  dislikes, 
acquired  sympathies  and  antipathies,  forms  of  attention  and 
interest.  These  are  related,  as  was  shown  before,  to  modes 
of  reaction.  We  now  see  how  these  tastes  and  interests  are 
developed  as  a  part  of  the  individual's  adjustment  of  himself 
to  the  world.  Some  tastes  are  traceable  to  inherited  instincts, 


208  YCHOLOGY 

others  to  acquired  habits,  and  so  on  through  the  list  The 
important  fact  for  psychology  is  that  past  experience  comes 
over  into  the  present  in  the  form  of  fundamental  attitudes 
and  tendencies.  The  introspective  observer  is  likely  to  make 
the  mistake  of  thinking  that  his  likes  and  dislikes  arc  the 
products  of  his  present  thinking,  when  in  reality  they  come 
to  him  from  a  remote  past,  even  in  some  cases  from  his 
racial  inheritances. 

Applications  of  the  doctrine  of  attitudes  to  social  science. 
What  is  shown  by  these  few  examples  is  of  the  greatest  im- 
portance for  the  social  sciences.  Social  life  has  developed 
innumerable  habits  in  the  individual.  We  pass  each  other 
on  the  right ;  we  accost  our  friends  on  the  street ;  we  gather 
about  the  table  and  take  our  food  in  an  orderly  way.  In  these 
and  a  thousand  of  the  customs  of  social  life  we  record  the 
experience  of  the  past.  At  the  moment  we  find  ourselves  in 
sympathy  with  our  surroundings.  Indeed,  we  should  be  most 
uncomfortable  if  our  surroundings  did  not  call  for  those  forms 
of  behavior  which  are  laid  down  by  habit  in  our  nervous  sys- 
tems. Personal  habits  and  social  customs  have  thus  come  to 
be  two  aspects  of  a  single  line  of  development.  Mere  again 
we  are  often  too  much  in  the  midst  of  the  experience  itself 
to  see  how  our  social  attitudes  came  into  being  and  what  is 
their  real  character. 


CHAPTER  X 

SPEECH  AS  A  FORM  OF  BEHAVIOR 

Speech  as  a  highly  important  special  habit.  Among  the 
habits  developed  by  human  beings  none  is  so  elaborate  as 
speech  ;  none  is  so  intimately  related  to  the  higher  levels 
to  which  human  experience  attains.  Speech  is  evidently  a 
form  of  muscular  behavior,  as  can  be  readily  observed  if  one 
notes  the  movements  in  the  thorax,  larynx,  and  mouth  dur- 
ing articulation.  So  complex,  however,  are  the  mental  proc- 
esses related  to  the  movements  involved  in  speech  that  we 
ordinarily  overlook  entirely  the  physical  side  of  the  process 
and  think  of  speech  only  as  one  of  the  higher  forms  of 
mental  activity. 

Speech  and  ideas  closely  interrelated.  There  would  be 
logical  justification  for  a  postponement  of  the  discussion  of 
speech  until  after  the  description  and  classification  of  ideas 
and  of  those  thought  processes  which  develop  with  the 
evolution  of  language.  Speech  would  then  be  treated,  as  it 
is  in  the  thinking  of  most  people,  as  a  product  or  expression 
of  higher  intelligence.  But  speech  is  more  than  a  product 
of  thought ;  it  is  the  instrument  which  makes  thought  pos- 
sible ;  or,  "differently  expressed,  it  is  the  kind  of  reaction 
which  is  essential  to  the  higher  attitudes  of  discrimination 
and  comparison.  Just  as  the  processes  of  perception  are 
not  merely  receptive  but  involve  reactions,  so  the  higher 
thought  processes  are  active  and  depend  for  their  character 
on  those  forms  of  behavior  which  make  up  the  speech  habit. 
We  are  justified,  therefore,  in  discussing  speech  before  treat- 
ing of  ideas,  even  though  we  shall  have  frequent  occasion  in 

209 


JIO  I'SY<    I! 

this  chapter  to  rcfrr  to  tin-  higher  mental  processes  before 
we  have  described  them  in  detail. 

Speculations  regarding  the  nature  and  origin  of  speech. 
Speech  has  from  the  cnrli  ,  tx.-i-n  recognized  by  man 

as  a  unique  power.    It  is  the  distinguishing  characteristic 
U'tween  Greek  and  barbarian,  betuvi-n  I  It-brew  and  gc: 
In  more  emphatic  degree,  it  is  the  mark  of  distinction  bc- 
.  man  and  his  nearest  relatives  in  the  animal  kingdom. 

Long  before  there  was  a  science  of  human  nature,  i 
speculated  curiously  as  to  the  source  from  which  language 
came.    His  first  answer  was  that  the  Deity  gave  it  to  him 
by  a  special  act  of  creation. 

The  special  creation  theory.  The  special  creation  theory 
of  the  origin  of  language  ignores,  however,  certain  facts 
which  are  too  obvious  to  be  set  aside.  It  ignores  the  fact 
that  animals  have  the  ability  to  make  certain  vocal  sounds 
which  they  utilize  for  purposes  of  communication  with  one  an- 
other. We  cannot  explain  how  it  is  that  animals  have  modes 
of  expression  so  closely  related  to  human  language  without, 
at  the  same  time,  recognizing  the  natural  origin  of  language 
itself.  Furthermore,  the  processes  of  human  expression  are 
constantly  undergoing  changes  and  developments  which  are 
so  natural  and  so  definite  in  their  character  that  it  s< 
probable  that  language  has  always  been  evolving  just  as  it 
is  at  the  present  time.  If  the  principles  under  which  lan- 
guage as  we  know  it  is  developing  can  be  ascertained,  it  is 
reasonable  to  project  these  laws  back  of  the  historical  period 
and  to  assume  that  the  beginnings  of  language  were  also 
under  the  regular  laws  of  development.  The  creation  theory 
has  therefore  gradually  given  way  to  various  theories  which 
attempt  to  give  a  naturalistic  explanation  of  language. 

The  imitation  theory.    It  has  sometimes  been  held  in  later 
speculation  that  language  originated  from  the  tender 
imitate  sounds.    This  theory-,  while  it  would  explain  certain 
of  the  special   forms  of  words,  cannot  give  any  adequate 


SPEECH  AS  A  FORM  OF  BEHAVIOR  211 

account  of  the  way  in  which  an  individual  develops  the  power 
of  turning  imitation  to  the  special  ends  of  speech.  There 
are  a  number  of  different  animals  that  are  capable  of  a  wide 
range  of  imitation,  but  they  have  never  developed  a  lan- 
guage, as  has  man.  This  is  clear  evidence  that  the  essence 
of  language  is  not  to  be  found  in  imitation,  but  rather  in  the 
use  to  which  the  imitative  power  is  put. 

The  interjection  theory.  It  has  also  been  suggested  that 
language  developed  out  of  the  interjections  which  man  natu- 
rally used  in  his  most  primitive  stage  of  development.  If 
he  was  astonished  by  any  sudden  stimulation,  he  naturally 
gave  forth  ejaculations  in  response  to  the  sudden  excitation. 
These  ejaculations,  it  is  said,  came  gradually  to  have  the 
power  of  calling  to  mind  the  situations  to  which  they  be- 
longed and  ultimately  became  the  means  of  communication. 
Here  again  the  objection  to  the  theory  is  not  that  it  seems 
improbable  that  man  began  with  simple  forms  of  expres- 
sion, but  that  the  theory  does  not  explain  how  these  simple 
forms  of  expression  acquired  a  meaning  and  importance 
which  they  did  not  have  at  the  beginning.  What  is  needed, 
rather  than  a  formal  description  of  the  first  expressions  used 
by  primitive  man,  is  a  consistent  psychological  explanation  of 
how  the  ejaculations  came  to  have  significance  for  mental  life 
and  to  serve  as  the  vehicles  for  elaborate  thought  processes. 

Roots  of  language  in  natural  emotional  expressions  and 
their  imitation.  The  psychological  explanation  of  language 
begins  with  a  general  reference  to  the  statements  made  in 
earlier  chapters.  Every  sensory  stimulation  arouses  some 
form  of  bodily  activity.  The  muscles  of  the  organs  of  cir- 
culation and  the  muscles  of  the  limbs,  as  well  as  other 
internal  and  external  muscles,  are  constantly  engaged  in 
making  responses  to  external  stimuli.  Among  the  muscles 
of  the  body  which  with  the  others  are  involved  in  expres- 
sive activities  are  the  muscles  which  control  the  organs  of 
respiration.  There  can  be  no  stimulation  of  any  kind  which 


212  VCHOLOGY 

does  not  affect  more  or  less  the  character  of  t!  icnts 

of  inspiration  and  expiration.   In  making  these  general  state- 
ments, we  find  no  necessity  for  distinguishing  between  the 
animals  and  man ;  so  far  as  the  general  facts  of  n •!. 
between  sensations  and  expression  arc  concerned,  they 
like  characteristics.   That  an  air-breathing  animal  should 
duce  sounds  through  irregularities  in  its  respiratory  n 
ments  when  it  is  excited  by  an  external  stimulus,  cspc> 
if  that  stimulus  is  violent,  is  quite  as  natural  as  that  its  hair 
should  rise  when   it  is  afraid  or  that  its  muscles  should 
tremble  when  it  is  aroused  to  anger  or  to  flight. 

Imitation.  The  important  step  in  the  development  of  lan- 
guage is  the  acquirement  of  the  ability  to  use  the  movements 
of  the  vocal  cords  for  purposes  other  than  those  of  individ- 
ual emotional  expression.  The  acquirement  of  this  ability  is 
a  matter  of  long  evolution  and  depends  in  its  first  stages 
upon  social  imitation.  The  importance  of  imitation  in  affect- 
ing the  character  of  animal  behavior  appears  as  soon  as  ani- 
mals begin  to  live  in  packs  or  herds  or  other  social  groups. 

Other  imitative  communications  of  animals  and  man.  So 
far  as  communication  through  imitation  is  concerned,  there- 
is  no  reason  why  attention  should  be  confined  exclusively  u» 
the  forms  of  activity  which  result  in  sounds.  All  animals 
imitate  the  activities  of  other  members  of  their  species  on  a 
very  large  scale.  The  stampede  of  a  herd  of  cattle  is  a: 
cellent  illustration  of  the  importance  of  the  tendency'  toward 
imitation.  The  frightened  animal  which  starts  the  stampede 
does  not  consciously  purpose  to  communicate  its  fright  to 
the  other  members  of  the  herd ;  it  is  performing  a  natural 
act  of  its  individual  life.  Incidentally,  it  affects  all  those 
about  it  by  arousing  in  them  a  violent  form  of  imitative 
activity.  The  stampeding  herd  may  have  no  consciousness 
whatever  of  the  original  cause  of  fear  in  one  of  its  mem- 
bers ;  the  real  cause  of  the  stampede  and  of  the  resulting 
excitement  in  the  herd  is  the  example  of  the  one  frightened 


SPEECH  AS  A  FORM  OF  BEHAVIOR  213 

animal.  Thus  we  see  that  the  activity  of  an  animal  takes  on, 
because  of  the  reaction  of  its  social  environment,  a  signifi- 
cance which  the  original  act  never  could  have  had  unless  it 
had  been  imitated. 

Value  of  sounds  as  means  of  social  communication.  What 
is  true  of  activity  in  general  is  true  of  activities  which  result 
in  sounds.  The  sound  produced  by  the  activities  of  the  vocal 
cords  can  impress  itself  readily  upon  the  ears  of  some  other 
animal,  more  readily  by  far  than  the  visual  impression  of 
trembling  or  of  general  muscular  tension.  If,  now,  the  ani- 
mal which  hears  the  sound  has  itself  produced  this  sound 
or  one  closely  resembling  it  in  quality  and  intensity,  there 
will  be  a  natural  tendency  for  the  sound  stimulation  to  arouse 
in  the  second  animal  a  sympathetic  response.  Witness  the 
tendency  of  all  the  dogs  in  a  c6mmunity  to  bark  together 
or  of  all  the  roosters  to  begin  crowing  together  when  one 
gives  the  signal.  The  result  of  imitating  the  sound  will  be 
to  throw  the  imitating  animal  into  an  emotional  state  very 
similar  to  that  of  the  animal  which  first  made  the  noise. 
This  result  will  be  more  likely  to  follow  if  the  two  animals 
are  closely  related  in  their  organization  and  types  of  activity. 
There  will  be  relatively  less  tendency  to  sympathize  with  an 
animal  of  entirely  different  organization  and  habits,  for  the 
activity  aroused  through  imitation  in  the  listening  animal 
will  not  agree  in  character  with  the  activity  of  the  animal 
which  sets  the  example.  Thus,  one  can  judge  from  his  own 
experience  that  there  is  very  little  possibility  of  arousing  in 
a  human  being  the  mental  state  which  appears  in  dogs  or 
cats  through  imitation  of  the  sounds  which  they  produce. 
In  general,  imitation  of  sound  is  valuable  as  a  means  of 
arousing  sympathy  only  between  animals  sufficiently  related 
to  each  other  to  have  similar  modes  of  producing  sound. 

Limitation  of  forms  of  animal  communication.  Given  the 
similarity  of  organization  which  makes  imitated  sounds  sig- 
nificant, we  have  a  type  of  communication  provided  which 


»M 

Icly  utili/cd  in  the  animal  world.    The  food  calls  and 
the  danger  signals  of  birds  are  sL  ibenr 

of  the  fit-  h  calls  have  definite  natural  i  >the 

organized  responses  of  all  members  of  the  species.    It 
be  noted  that  these  calls  do  not  const  it  'guage  in  the 

sense  in  which  human  sounds  constitute  a  language,  for  the 
bird  calls  are  incapable  of  conveying  definite  ideas, 
ideas  of  the  kind  of  food  or  the  particular  kind  of  danger  dis- 
covered by  the  animal  which  makes  the  sound.    The  sounds 
serve  merely  to  arouse  certain  attitudes.     An  animal  can 
induce  in  its  fellows  a  tendency  to  fear  and  flight  by  nv 
of  cries  which  in  the  history  of  each  member  of  the  flock  have 
been  associated  with  fear,  but  the  animal  can  go  no  fart! 
its  communications  than  to  arouse  emotional  attitud 

The  first  stages  of  human  articulation  like  animal  cries. 
There  are  stages  of  human  infancy  which  are  closeh 
lated  to  the  stages  of  animal  life  thus  far  described.  The 
human  infant  does  not  at  first  make  sounds  as  the  result  of 
any  conscious  desire  to  communicate  its  feelings  to  those 
about  it,  much  less  does  it  use  its  sounds  for  verbal  dis- 
cussion of  the  details  of  its  conscious  experiences.  The 
infant  makes  noises  exactly  as  it  swings  its  arms  and  legs, 
because  the  muscular  contractions  which  produce  these 
noises  are  instinctive  motor  expressions  related  through 
heredity  to  the  stimuli  which  arouse  them.  I^ter  there 
appears  a  strong  tendency  to  imitate  others  of  its  own  kind, 
and  this  imitation  may  serve  to  put  the  infant  in  some  con- 
tact with  its  social  environment  and  give  it  a  medium  of 
communication  comparable  in  character  to  that  which  we 
find  in  animals.  This  is  not  language,  however,  for  imitation 
alone  is  not  enough  to  develop  language.  Further  processes 
must  take  place  before  the  full  development  is  effected. 

Articulations  selected  from  the  sum  of  possible  activities. 
While  imitation  applies  to  many  different  forms  of  activity, 
such  as  those  of  the  limbs  or  face,  a  moment's  consideration 


SPEECH  AS  A  FORM  OF  BEHAVIOR  215 

will  make  it  clear  that  the  activities  which  produce  sounds 
have  a  number  of  unique  advantages  as  vehicles  of  imitative 
communication.  The  ability  to  produce  sounds  depends 
largely  upon  the  animal  itself  and  very  little  upon  external 
conditions.  Contrast  sound  with  visual  impressions.  Visual 
impressions  are  cut  off  in  the  dark ;  they  are  cut  off  by 
intervening  objects  and  by  a  turning  of  the  head  of  the 
observer.  Sounds  travel  wherever  there  is  air ;  they  are  as 
easy  to  produce  in  the  darkness  as  in  daylight ;  they  can 
easily  be  varied  in  intensity.  For  these  reasons  they  come 
to  be  the  chief  means  of  social  communication,  even  among 
the  animals.  The  result  is  that  the  vocal  cords  and  the 
ability  to  discriminate  sounds  are  highly  developed  long 
before  the  development  of  language  proper. 

Evolution  of  ideas  and  speech.  The  advance  which  human 
language  makes  beyond  animal  communication  consists  in 
the  fact  that  human  language  relates  sounds  to  ideas  as 
well  as  to  emotional  attitudes.  This  step  cannot  be  taken 
until  ideas  are  present  in  the  minds  of  both  parties  to  the 
communication.  We  find  ourselves,  therefore,  at  this  point 
involved  in  a  perplexing  circle.  Human  mental  processes 
as  we  know  them  are  intimately  related  to  language.  Even 
when  we  think  about  our  own  most  direct  experiences,  we 
use  words.  Yet  these  words  are  not  explicable  except  when 
we  assume  complex  ideational  processes  as  the  necessary 
conditions  for  their  development  and  interpretation.  Did 
human  mental  advance  result  from  the  development  of 
language,  or  did  language  result  from  the  development  of 
ideas  ?  The  only  answer  to  this  question  is  that  language  and 
ideational  processes  developed  together  and  are  necessary  to 
each  other. 

In  describing  the  first  stages  of  the  development  of  true 
language  we  may  assume,  therefore,  that  both  speaker  and 
auditor  have  reached  a  stage  of  development  where  it  is 
possible  to  have  higher  nervous  and  conscious  processes. 


216  PSYCHOU 

Such  higher  processes  are  to  be  contrasted  with  mere  emo- 
tional attitudes.    For  example,  if  one  sees  his  fellow  being 
pointing  in  a  certain  direction,  there  is  a  strong  tcn<: 
to  turn  and  look  in  the  same  direction.    There  will  i 
in  this  case  not  an  emotion  but  a  common  attention  to  some 
object.    The  gesture  of  point;  cordingly,  a  mode  of 

communication  which  a  higher  level  than  docs  the 

cry  of  fear  or  the  food  call.    Its  development  opens  the 
for  a  higher  system  of  communication. 

Gestures  and  broad  scope  of  attention.  Still  higher  is 
the  gesture  that  depicts  some  elaborate  act.  Thus,  when  a 
man  is  hungry  he  will  point  to  his  mouth  and  make  the 

:re  of  taking  up  food  and  carrying  it  to  his  m 
This  simple  gesture  will  not  be  made  by  an  animal,  because 
the  animal  has  only  a  limited  range  of  attention.  If  the 
animal  thinks  of  food,  it  cannot  entertain  any  other  ideas. 
It  spends  all  its  mental  energy  seeking  food  rather  than 
trying  to  communicate  with  some  other  animal.  In  human 
life  there  is  breadth  of  attention  exhibited  in  a  gesture. 
The  person  who  makes  a  gesture  includes  in  his  experience 
the  person  with  whom  he  wishes  to  communicate,  plus  the 
idea  which  is  to  be  communicated.  The  animal  may  have 
a  simple  idea  but  not  the  complex  of  ideas  invol- 
in  gesture. 

This  ability  of  man  to  have  two  centers  of  attention  can 
be  explained  anatomically  by  recalling  that  man  has  great 
masses  of  cerebral  tissue  within  which  impulses  can  be 
worked  over.  The  animal  has  only  a  little  brain  tissue,  and 
any  impulse  received  in  the  brain  must  be  discharged 
soon  in  the  form  of  a  motor  impulse.  The  hungry  animal 
must  act  at  once  in  the  effort  to  remove  hunger.  Man,  on 
the  other  hand,  has  enough  brain  tissue  to  hold  the  impulse 
in  suspense,  unite  it  with  impressions  from  his  fellow  beings, 
and  act  in  a  complex  way  with  full  regard  both  to  his  fellow 
beings  and  to  his  hunger. 


SPEECH  AS  A  FORM  OF  BEHAVIOR  217 

Gesture,  or  gesture  language  as  it  is  called,  is  thus  seen 
to  be  not  merely  a  complex  form  of  behavior  but  one  which 
expresses  a  new  type  of  relationship  between  the  reactor 
and  his  environment.  Gesture  is  a  social  form  of  behavior 
involving  attention  to  persons  as  well  as  to  objects.  Indeed, 
gesture  supersedes  the  more  direct  forms  of  attack  on  objects. 

Evolution  of  gestures  in  direction  of  simplification.  The 
earliest  forms  of  social  communications  undoubtedly  included 
much  gesture  if,  indeed,  they  were  not  limited  altogether 
to  gesture.  The  term  "  natural  sign "  has  been  used  in 
describing  these  early  gestures.  The  gesture  was  so  full 
and  pantomimic  in  character  that  the  interpretation  was 
almost  as  direct  as  in  the  case  of  an  emotional  expression. 
The  gesture  could  be  interpreted  by  anyone  who  had  passed 
through  an  experience  at  all  like  that  of  the  person  making 
the  gesture.  All  that  we  need  to  assume  by  way  of  explanation 
of  gesture  is  the  law  of  social  imitation  which  was  stated  in 
earlier  paragraphs  and  the  higher  power  of  reviving  ideas. 

The  later  development  of  gesture  language  brought  with 
it  a  reduction  of  the  gesture  so  that  it  became  a  mere  rem- 
nant of  the  earlier  act.  This  reduction  to  a  simpler  act  was 
possible  within  the  group  of  those  who  had  learned  to  com- 
municate with  each  other.  Thus,  instead  of  requiring  the 
full  pantomime  to  communicate  the  fact  that  one  was  hungry, 
it  came  to  be  enough  that  one  pointed  in  the  direction  of  the 
mouth.  A  mere  clue  served  to  arouse  the  idea.  This  stage 
is  reached  when  both  the  parties  to  the  communication  have 
developed  the  power  of  supplying  the  ideas  needed  for 
interpretation  to  such  a  high  level  that  it  is  very  easy  to 
call  out  the  idea  by  the  slightest  hint. 

Speech  a  highly  specialized  mode  of  behavior.  This  de- 
velopment, which  made  it  less  and  less  important  that  the 
gesture  be  a  full  pantomime,  opened  the  way  for  a  selection 
of  certain  particular  forms  of  activity  which  became  the 
vehicles  of  communication  and  were  wholly  set  aside  for 


218  , 

that  purpose.    The  vocal  cord  not  available  as  organs 

for  communication  of  ideas  so  long  as  the  ideas  had  to  be 
depicted  in  full  by  means  of  dai  mitablc  gestures. 

Hut  as  the  need  of  gestures  diminished  and  the  power  of 
supplying  ideas  increased,  the  vocal  cords  proved  increas- 
ingly useful  as  special  organs  of  social  communication  just 
because  they  were  not  otherwise  used.  The  hands  \\ 
\\vre  used  for  communication  during  the  period  when  ges- 
ture '.vim;  \\ere  in  demand  for  the  direct  prai 
activities  of  life.  When  two  individuals  wi>h  t<>  communi- 
cate with  each  other,  it  is  often  extremely  inconvenient  to 
suspend  all  other  activity,  to  lay  down  what  one  may  be 
carrying,  to  come  where  one  may  be  clearly  seen,  for  the 
purpose  of  holding  a  parley.  The  vocal  cords,  on  the  other 
hand,  are  not  required  for  the  practical  purposes  of  life. 
They  are  easily  disconnected  in  their  action  from  the  gen- 
eral mass  of  the  muscles  and,  therefor<  naturally 
became  the  organs  for  a  system  of  social  activities. 

One  of  the  most  primitive  forms  of  vocal  art  is  the 
work  song.  This  illustrates  strikingly  the  relation  of  vocal 
reactions  to  handwork.  The  workers  secured  social  coopera- 
tion through  the  song,  their  hands  in  the  meantime  being 
occupied  in  practical  work. 

Consequences  of  specialization.  The  fact  that  speech  thus 
separates  itself  from  other  forms  of  bodily  activity  and  be- 
comes a  highly  specialized  system  of  behavior  brings  with 
it  a  number  of  important  consequences.  First,  it  is  possible 
for  speech  to  develop  to  a  high  level  without  involving 
the  corresponding  development  of  any  of  the  practical  arts. 
\Yhat  is  sometimes  called  pure  verbalism  may  result.  Thus 
a  student  may  acquire  mere  words  and  not  have  any  power 
of  applying  the  words  which  he  repeats  to  other  forms  of 
behavior. 

Second,  the  specialized  character  of  speech  results  in 
the  sharp  differentiation  of  one  local  language  from  that 


SPEECH  AS  A  FORM  OF  BEHAVIOR  219 

of  other  sections.  Ultimately  each  language  grows  so  far 
from  the  parent  root  that  it  is  wholly  unintelligible .  except 
to  those  who  are  trained  in  its  special  forms. 

Third,  there  is  a  possibility  that  ideas  will  be  attached 
to  sounds  so  loosely  and  ambiguously  that  the  two  parties 
to  communication  will  drift  far  apart  in  their  interpretations 
while  using  one  and  the  same  sounds. 

Speech  an  indirect  form  of  behavior.  Speech  as  a  form 
of  behavior  thus  lacks  that  direct  relation  to  the  outer 
world  which  most  habits  exhibit.  It  takes  on  a  highly 
artificial  character.  Its  uses  are  controlled  by  social  con- 
vention rather  than  by  natural  necessity.  We  may  therefore 
very  properly  describe  speech  as  an  indirect,  conventional 
form  of  behavior. 

Evolution  of  writing.  The  stages  of  evolution  of  speech 
which  have  been  described  in  the  foregoing  paragraphs 
are  exemplified  in  essentially  the  same  sequence,  though  in 
slightly  different  form,  in  the  evolution  of  the  art  of  writing. 

Writing  at  first  direct  in  form.  The  earliest  stages  of 
writing  were  those  in  which  pictographic  forms  were  used  ; 
that  is,  a  direct  picture  was  drawn  upon  the  writing  surface, 
reproducing  as  nearly  as  possible  the  kind  of  impression 
made  upon  the  observer  by  the  object  itself  (see  Fig.  54). 
To  be  sure,  the  drawing  used  to  represent  the  object  was 
not  an  exact  reproduction  or  full  copy  of  the  object,  but  it 
was  a  fairly  direct  image.  The  visual  image  was  thus 
aroused  by  a  direct  appeal  to  the  eye.  Anyone  could  read 
a  document  written  in  this  pictographic  form  if  he  had 
ever  seen  the  objects  to  which  the  pictures  referred.  There 
was  no  special  relation  between  the  pictures  or  visual  forms 
at  this  stage  of  development  and  the  sounds  used  in  articu- 
late language.  Concrete  examples  of  such  writing  are  seen 
in  early  monuments,  where  the  moon  is  represented  by 
the  crescent,  a  king  by  the  drawing  of  a  man  wearing  a 
crown.  An  example  of  this  stage  of  writing  is  also  supplied 


220  PSYCH 

he  ancient  Chinese  forms  shown   in   the  upper  line 

'g-  55- 

Images  reduced  to  lowest  terms  as  powers  of  reader 
increase.  The  next  stage  of  development  in  writing  began 
\\hen  the  pictographic  forms  were  n  ;n  compl< 

to  the  simplest  possible  lines.    The  reduction  of  the  p; 
to  a  few  sketchy  lines  depended  upon  the  growing  ability  of 
the  reader  to  contribute  the  necessary  interpretation.    All 
that  was  needed  in  the  figure  was  something  which  would 

f  tr 


Fiu.  54.  An  Ojibwa  love  letter,  recorded  and  explained  by  Garrick  Mallery 
in  the  Annual  Report  of  the  Bureau  of  Ethnology,  1888-1889.  p.  363 

The  writer,  a  girl  of  the  Bear  totem,  />.  summons  her  lover,  who  belongs  to  the 
Mud  Puppy  totem,  </,  along  the  various  trails  indicated,  to  the  lodge,  f,  from  which 
the  beckoning  hand  protrudes.  The  inclosed  figures  at  /,  /,  and  k  are  lakes.  The 
crosses  indicate  that  the  girl  and  her  companions  are  Christians.  "  The  clear  indi- 
cations of  locality,"  writes  Mallery, "  serve  as  well  as  if  in  a  city  a  young  woman  had 
sent  an  invitation  to  her  young  man  to  call  at  a  certain  street  and  number  " 

suggest  the  idea  to  the  reader's  mind.  The  simplification 
of  the  written  forms  is  attained  very  early,  as  is  seen  even 
in  the  figures  which  are  used  by  savage  tribes.  Thus,  to 
represent  the  number  of  an  enemy's  army,  it  is  not  neces- 
sary to  draw  full  figures  of  the  forms  of  the  enemy ;  it  is 
enough  if  single  straight  lines  are  drawn  with  some  brief 
indication,  perhaps  at  the  beginning  of  the  series  of  lines, 
to  show  that  these  stand  each  for  an  individual  enemy. 
This  simplification  of  the  drawing  leaves  the  written  sym- 
bol with  very  much  larger  possibilities  of  entering  into 


SPEECH  AS  A  FORM  OF  BEHAVIOR  221 

new  relations  in  the  mind  of  the  reader.  Instead,  now,  of 
being  a  specific  drawing  related  to  a  specific  object,  it 
invites  by  its  simple  character  a  number  of  different  inter- 
pretations. A  straight  line,  for  example,  can  represent 
not  only  the  number  of  an  enemy's  army,  but  it  can  rep- 
resent also  the  number  of  sheep  in  a  flock,  or  the  number 
of  tents  in  a  village,  or  anything  else  which  is  capable  of 
enumeration.  The  use  of  a  straight  line  for  these  various 
purposes  stimulates  new  mental  developments.  This  is 
shown  by  the  fact  that  the  development  of  the  idea  of  the 


o 

H 


Tfc 


FIG.  55.    Ancient  and  modern  Chinese  writing 


The  upper  line  shows  ancient  forms  of  Chinese  writing  ;  the  lower  line  shows  the 

derived  modern  forms.    Reading  from  left  to  right,  the  characters  signify  "sun," 

.  "moon,"  "mountain,"  "tree"  (or  "wood"),  "dog" 


number  relation,  as  distinguished  from  the  mass  of  possible 
relations  in  which  an  object  may  stand,  is  greatly  facilitated 
by  this  general  written  symbol  for  numbers.  The  intimate 
relation  between  the  development  of  ideas  on  the  one  hand 
and  the  development  of  symbols  on  the  other  is  here  very 
strikingly  illustrated.  The  drawing  becomes  more  useful 
because  it  is  associated  with  more  elaborate  ideas,  while  the 
ideas  develop  because  they  find  in  the  drawing  a  definite 
content  which  helps  to  mark  and  give  separate  character  to 
the  idea.  Striking  examples  of  the  simplification  of  form 
in  order  to  facilitate  the  writing  of  symbols  are  shown  in 
-  55  and  S^. 


»2fl  I'M.   i 

Written  symbols  and  their  relation  to  sounds.    As  soon 
as  the-  drawing  began  to  lose  its  significance  as  a  c 
perceptual  reproduction   of   the   object   and   took   on   new 

and   broader   meanings   through  the  asso< 

;itten    torm   became  a  symbol    rather 

than  a  direct   apjx-al   t(»   visual   memory.     As  a  symbol   it 

1  for  something  which,  in  itself,  it  was  not.    The  way 


AA   M 


FIG.  56.    Derivation  of  the  Roman  letter  M  from  the  ancient  Egyptian 
hieroglyphic  owl 

The  four  forms  in  the  upper  part  of  the  figure  are  Egyptian  forms.  The  first  on  the 

left  is  the  usual  hieroglyphic  picture  of  the  owl,  or,  as  it  was  called  in  the  Egyptian 

language,  mulak.  The  three  remaining  upper  forms  are  found  in  the  writings  of  the 

.in  priests.  The  first  form  on  the  left  of  the  lower  series  is  an  ancient  Semitic 

form.     Then  follow  in  order  an  ancient  Greek  form  and  two  later  Greek  forms. 

(From  I.  Taylor's  "The  Alphabet,"  pp.  9,  10) 

was  thus  opened  for  the  written  symbol  to  enter  into  rela- 
tion with  oral  speech,  which  is  also  a  form  of  symbolism 
(see  Fig.  56).  Articulate  sounds  are  simplified  forms  of 
experience  capable  through  association  with  ideas  ot 

-ing  meanings  not  directly  related  to  the  sounds  them- 
selves. \\  hen  the  written  symbol  began  to  be  related  to  the 
sound  s\  mlx)l.  there  was  at  first  a  loose  and  irregular  relation 
between  them.  The  Egyptians  seem  to  have  established 


SPEECH  AS  A  FORM  OF  BEHAVIOR  223 

such  relations  to  some  extent.  They  wrote  at  times  with 
pictures  standing  for  sounds  as  we  now  write  in  rebus  puz- 
zles. In  such  puzzles  the  picture  of  an  object  is  intended  to 
call  up  in  the  mind  of  the  reader  not  the  special  group  of 
ideas  appropriate  to  the  object  represented  in  the  picture 
but  rather  the  sound  which  serves  as  the  name  of  this  object. 
When  the  sound  is  once  suggested  to  the  reader,  he  is  sup- 
posed to  attend  to  that  and  to  connect  with  it  certain  other 
associations  appropriate  to  the  sound.  To  take  a  modern 
illustration,  we  may,  for  example,  use  the  picture  of  the  eye 
to  stand  for  the  first  personal  pronoun.  The  relationship 
between  the  picture  and  the  idea  for  which  it  is  used  is 
in  this  case  through  the  sound  of  the  name  of  the  object 
depicted.  That  the  early  alphabets  are  of  this  type  of 
rebus  pictures  appears  in  their  names.  The  first  three 
letters  of  the  Hebrew  alphabet,  for  example,  are  named, 
respectively,  aleph,  which  means  "ox,"  beth,  which  means 
"house,"  and  gimmel,  which  means  "camel." 

The  alphabet.  The  complete  development  of  a  sound 
alphabet  from  this  type  of  rebus  writing  required,  doubt- 
less, much  experimentation  on  the  part  of  the  nations 
which  succeeded  in  establishing  the  association.  The  Phoe- 
nicians have  generally  been  credited  with  the  invention  of 
the  forms  and  relations  which  we  now  use.  Their  contri- 
bution to  civilization  cannot  be  overestimated.  It  consisted 
not  in  the  presentation  of  new  material  or  content  to  con- 
scious experience  but  rather  in  bringing  together  by  asso- 
ciation groups  of  contents  which,  in  their  new  relation, 
transformed  the  whole  process  of  thought  and  expression. 
They  associated  visual  and  auditory  content  and  gave  to 
the  visual  factors  a  meaning  which  originally  attached  to 
the  sound.  Pictures  thus  came  to  mean  sounds  rather  than 
objects  (see  Fig.  56). 

Social  motives  essential  to  the  development  of  language. 
The  ideational  interpretations  which  appear  in  developed 


224 

language  could  never  have  reached  the  elaborate  form 
which  they  have  at  present  if  there  had  not  been  social 
cooperation.  dency  of  th<  n  left  to 

himself  is  to  drop  back  into  the  direct  adjustments  which 
are  appropriate  to  his  own  life.  He  might  possibly  develop 
articulation  to  a  certain  extent  for  his  own  sake,  but  the 
chief  impulse  to  the  development  of  language  comes 
through  intercourse  with  others.  As  we  have  seen,  the 
opmcnt  of  the  simplest  forms  of  communication;  as 
in  animals,  is  a  matter  of  social  imitation.  Writing  is  also 
an  outgrowth  of  social  relations.  It  is  extremely  doubtful 
whether  even  the  child  of  civilized  parents  would  ever  have 
any  sufficient  motive  for  the  development  of  writing  if  it 
were  not  for  the  social  encouragement  which  he  receives. 

Social  system  as  source  of  the  form  of  words.  Further- 
more, we  depend  upon  our  social  relations  not  merely  for 
the  incentives  to  the  development  of  language  but  also  for 
the  particular  forms  which  oral  and  written  language  shall 
take.  It  is  much  more  convenient  for  a  child  born  into  a 
civilized  community  to  adapt  himself  to  the  complex  symbol- 
ism which  he  finds  in  the  possession  of  his  elders  than  to 
develop  anything  of  the  sort  for  himself.  It  is  true  that 
tendencies  exist  early  in  life  toward  the  development  of 
individual  forms  of  expression.  A  child  frequently  uses  a 
certain  sound  in  a  connection  which  cannot  be  explained 
by  reference  to  social  usage.  It  may  be  a  purely  individual 
combination,  or  a  crude  effort  to  adopt  something  which 
has  been  suggested  by  the  environment.  This  tendency  to 
give  sounds  a  meaning  might  prove  sufficient  to  work  out 
a  kind  of  language,  even  if  the  individual  were  entirely 
isolated  from  his  fellows ;  but  the  natural  tendencies  are 
very  early  superseded  by  the  stronger  tendencies  of  social 
imitation,  and  in  the  end  the  social  system  completely 
dominates  individual  development,  dictating  in  all  cases  the 
forms  of  words. 


SPEECH  AS  A  FORM  OF  BEHAVIOR  225 

Social  usage  and  the  domination  of  individual  thought. 

In  adopting  the  forms  of  expression  used  by  those  about 
us,  we  are  led  to  take  up  certain  general  social  forms  of 
thought  which  ultimately  control  the  whole  mental  life.  The 
effect  of  this  social  influence  is  so  far-reaching  that  it  is 
quite  proper  to  say  that  an  individual  is,  in  a  very  large 
measure,  the  creation  of  his  social  relations,  at  least  in  the 
higher  phases  of  his  mental  life.  The  fundamental  forms 
of  direct  activity,  which  constitute  the  personal  habits  by 
which  we  have  succeeded  in  adapting  ourselves  to  the 
demands  of  the  physical  world,  are  to  a  certain  extent 
unsocial.  They  are,  to  be  sure,  alike  in  different  individuals 
because  they  have  grown  up,  as  was  shown  in  our  earlier 
discussion,  under  the  demands  of  a  common  physical 
environment.  Our  forms  of  space  perception,  for  example, 
are  not  the  creations  of  our  own  individual  caprice  but 
rather  the  arrangement  which  we  have  given  our  sensory 
experiences  in  our  effort  to  fit  ourselves  to  a  world  which 
dictates  these  space  relations  to  us.  Since  we  have  all  grown 
up  in  the  same  space  world,  our  space  ideas  are  alike. 
The  community  of  social  ideas  expressed  in  language  is  of 
a  different  type.  Even  the  direct,  relatively  unsocial  forms 
of  perception  are  influenced  by  these  higher  social  forms 
of  thought.  If,  for  example,  there  is  no  word  in  a  certain 
social  environment  for  long  spatial  distances  except  a  word 
which  refers  to  a  certain  number  of  days'  journeys,  it  is  not 
likely  that  the  individual  will  feel  any  tendency  to  discrimi- 
nate fifteen  miles  from  seventeen.  His  attitude  in  this 
matter  will  be  determined  by  the  attitude  of  his  social 
environment,  and  he  will  neglect  in  his  thought,  as  do 
those  about  him,  the  finer  details  of  distance.  Similarly,  if 
there  are  no  names  for  certain  forms  of  property  rights,  it 
is  not  likely  that  the  individual  will,  of  his  own  initiative, 
recognize  these  forms  of  right  as  belonging  to  those  who 
constitute  the  social  group  with  him. 


226  PSYCHOLOGY 

Social  ideas  dominate  individual  life.  The  history  of 
thought  has  been,  in  large  measure,  the  history  of  the 
development  ideas  which  could  be  marked 

with  definite  names  and  made  subjects  of  thought,  because 
they  were  so  marked.  i  moment  the  difficul- 

ties which   would  IK-  experienced  in  conducting  any 
of  thought  with  regard  to  the  forces  of  physical  nature  if 
there  were  no  names  for  the  different  forces  and  no  fully 
developed  definitions  to  give  each  name  clearly  recognized 

If  it  is  true  in  a  general  way  that  general 
dencies  of  thought  have  been  dependent  upon  the  develop- 
ment of  words  t<  still  more  true  in  the 
case  of  the  individual  that  his  mental  tendencies 
largely  determined  by  the  forms  of  social  thought  expressed 
in  words.  A  child  who  has  had  his  attention  called  to 
certain  colors  and  who  is,  at  the  same  time,  given  a  name 
for  these  colors  is  more  likely  to  identify  them  in  later 
experience  than  if  no  name  had  been  given.  The  name 
serves  as  an  incentive  to  the  concentration  of  attention 
upon  a  particular  phase  of  experience  which  would  otherwise 
be  lost  in  the  general  mass  of  sensations.  Without  the 
word  the  possibility  of  dwelling  upon  the  single  phase  of 
experience  in  thought  would  be  small.  This  is  the  reason 
why  the  retention  of  facts  in  memory  is  so  closely  related 
to  the  naming  of  obj< 

Experimental  evidence  of  importance  of  words.  Some 
experimental  evidence  can  be  adduced  to  show  that  names 
are  of  great  importance  in  this  respect.  If  one  is  confronted 
with  a  large  number  of  pieces  of  gray  paper  ranging  from 
black  to  white,  and  is  asked  to  discriminate  as  many  of 
these  different  grays  as  he  is  able  to  recognize  with  certainty, 
it  will  be  found  that  he  can  distinguish  ordinarily  about  five 
classes  of  gray  shades.  He  can  distinguish  the  very  dark 
from  those  which  are  medium  dark,  the  very  light  from 
those  that  are  medium  light,  and  he  can  place  between  the 


SPEECH  AS  A  FORM  OF  BEHAVIOR  227 

dark  and  the  light  grays  a  middle  shade  which  he  is  not 
disposed  to  classify  as  either  light  or  dark.  Beyond  this 
fivefold  discrimination  he  will  find  that  he  is  very  uncertain. 
If,  now,  after  making  this  test  under  ordinary  conditions, 
the  individual  is  allowed  to  examine  the  various  shades  of 
gray  and  to  adopt  a  series  of  names  or  numbers  for  them, 
it  will  be  found  that  he  can  notably  increase  the  range 
and  certainty  of  his  discrimination.  The  names  furnish,  as 
stated  above,  definite  means  of  concentrating  attention  upon 
slight  differences  which  existed  from  the  first  but  were  not 
noted  in  experience.  Furthermore,  when  these  slight  differ- 
ences have  been  discriminated  and  marked  by  the  attachment 
to  them  of  definite  names,  they  become  permanent  additions 
to  the  individual's  equipment  and  can  be  retained  more  easily 
than  they  could  be  as  mere  unnamed  sensation  qualities. 

Number  terminology  as  a  device  for  recording  posses- 
sions. One  of  the  best  illustrations  of  the  significance  for 
mental  life  of  the  creation  of  a  terminology  is  found  in  the 
ease  with  which  a  developed  individual  uses  numbers.  In 
general,  it  may  be  said  that  primitive  languages  have  only 
a  very  meager  number  terminology.  Savage  tribes  have 
frequently  been  known  to  have  no  number  terminology 
reaching  above  ten,  and  in  some  cases  tribes  have  been 
reported  with  a  number  terminology  not  reaching  beyond 
three.  There  are  certain  forms  of  direct  perceptual  experi- 
ence which  can  be  utilized  up  to  a  certain  point  instead  of 
the  developed  number  system  which  we  now  have.  If  a 
herdsman  has  a  herd  of  cattle  for  a  period  long  enough  to 
become  acquainted  with  its  individual  members,  he  can 
recognize  the  size  of  the  herd  by  recalling  the  individuals 
which  make  it  up.  If  one  has  material  possessions  which 
can  be  heaped  together,  he  will  come  to  estimate  his  wealth 
directly  through  the  general  impression  made  upon  him  by 
collecting  all  of  his  wealth  at  a  single  point.  As  soon  as 
the  direct  recollection  of  each  individual  possession  came, 


228  PSYCHOLOGY 

in  the  development  of  human  wealth,  to  be  too  cumbersome 
a  form  of  representation,  and  the  *.<•.  mage  became 

too  vague  to  be  relied  upon,  man  natural.  ivored  to 

devise  a  method  of  recording  his  property  and  retaining  it 
in  consciousness  in  some  simplified  form.  Instead  of  trying 
to  remember  every  one  of  his  possessions,  he  adopted  some 
system  of  tally.  At  first  he  began  counting  off  on  his 
fingers  each  different  article  which  he  wished  later  to  be 
able  to  recognize,  or  he  adopted  in  some  cases  one  of  the 
more  elaborate  methods  found  among  savages  who  use 
pebbles  or  shells.  The  Latin  root  which  appears  in  our 
word  "  calculate  "  and  all  related  words  is  the  word  for 
pebble,  and  indicates  that  the  early  forms  of  computation 
among  the  Romans  consisted  in  the  use  of  pebbles. 

Symbols  for  groups  of  tallies.  As  soon  as  the  system  of 
enumeration  became  complex,  there  naturally  arose  the 
necessity  for  grouping  the  tallies  so  that  they  could  be 
easily  surveyed.  The  method  of  grouping  the  tally  marks 
in  a  system  convenient  for  recognition  is  cl  by  the 

five  fingers  on  the  hand,  and  this  is  often  adopted,  even  by 
savage  peoples.  A  clear  indication  that  this  grouping  ap- 
peared in  the  natural  tally  systems  can  be  seen  in  the  symbols 
used  by  the  Romans  to  indicate  numbers,  for  in  this  system 
the  number  five  and  the  number  ten  are  crucial  points  in 
the  notation,  and  show  the  adoption  of  a  new  group  symbol 
to  include  many  individual  symbols  in  a  more  compact  form. 

Parallel  growth  of  number  names  and  system  of  ideas. 
As  the  number  system  was  worked  out  into  a  system  of 
major  and  minor  groups  there  was  a  tendency  to  develop 
a  system  of  articulation  directly  related  to  the  tally  system. 
Number  of  the  primitive  tally  form  probably  developed  just 
as  did  writing,  without  reference  to  speech.  The  creation 
of  words  which  should  express  number  was  slow,  as  indi- 
cated by  reference  to  savage  language,  because  in  this  case 
the  symbolical  system  needed  to  develop  to  a  high  degree 


SPEECH  AS  A  FORM  OF  BEHAVIOR  229 

before  the  demand  for  corresponding  articulation  was  felt. 
As  soon  as  the  demand  for  articulation  became  sufficiently 
pressing,  the  words  appeared,  and  they  show  distinctly  in 
their  character  the  tendency  toward  groups.  Further  than 
this,  the  names  for  successive  tallies  came  to  be  the  means, 
not  only  of  referring  to  individual  marks  but  also  of  refer- 
ring to  the  serial  arrangement  of  these  marks.  Thus,  the 
names  "one,"  "two,"  "three,"  etc.  are  not  significant 
merely  as  names  of  tally  marks  ;  they  have  also  each  its 
special  significance  as  the  name  of  a  special  position  in 
the  total  series. 

Development  of  arithmetic  depends  on  an  appropriate 
system  of  numerals.  The  advantage  to  the  child  who  finds 
a  complete  number  terminology  developed  is  very  great. 
The  more  perfect  this  terminology  for  purposes  of  express- 
ing quantitative  relations,  the  more  complete  and  rapid  will 
be  his  initiation  into  the  forms  of  thought  which  the 
terminology  expresses.  The  historical  illustration  of  this 
fact  is  to  be  found  in  the  acceptance  by  European  nations 
of  a  system  of  notation  which  was  imported  from  the  East 
in  the  Renaissance  period.  The  written  number  symbols 
which  had  been  used  by  the  Romans  were  crude  and 
rendered  any  forms  of  arithmetical  manipulation  extremely 
difficult.  The  Arabic  system  was  so  much  more  complete 
and  economical  that  it  immediately  took  the  place  of  the 
older  and  cruder  symbolism.  How  long  it  would  take  an 
individual  child  to  acquire  independently  anything  like  the 
mathematical  ability  which,  with  the  aid  of  his  social  en- 
vironment, he  acquires  through  the  adoption  of  the  developed 
Arabic  number  system  can  hardly  be  imagined.  Certain  it 
is  that  his  forms  of  thought  are  now  dominated  by  the 
social  system  into  which  he  is  born,  and  this  system  was 
in  turn  borrowed  in  toto  from  non-European  nations. 

Social  world  unified  through  common  forms  of  thought. 
There  is  in  this  acceptance  of  the  social  system  not  only  an 


230  PSY(  !i 

economy  which  operates  to  the  advantage  of  the  indiv: 
but  t  1  fact  thai  the  individual  becomes 

thereby  a  part  of  the  social  whole  in  a  fashion  which  is  sig- 
nificant for  society  as  well  as  for  himself.  We  are  bound 
together  as  intelligent  beings  by  the  common  systems  of 
tradition  and  language  to  a  degree  which  makes  us  no  longer 
centers  of  merely  individual  adaptation,  but  rather  parts  of 
a  general  organization  which  has  a  certain  unity  and  exer- 
cises a  dominating  influence  over  many  individuals.  This 
social  unity  perpetuates  customs  and  practices  so  that  we 
have,  in  addition  to  the  bodily  structures  which  we  in: 
a  social  heredity  which  guides  us  in  the  activities  of  per- 
sonal life.  Language  is  the  chief  medium  for  this  social 
heredity. 

Changes  in  words  as  indications  of  changes  in  individual 
thought  and  social  relations.  It  is  in  connection  with  the 
development  of  social  institutions  that  we  find  the  most  radical 
changes  in  human  language.  If  an  individual  comes  upon  a 
new  idea  and  coins  a  new  word  for  its  expression,  the  new 
word  gains  standing  and  comes  to  be  a  part  of  the  perma- 
nent language  of  the  community  only  when  others  feel  the 
same  necessity  as  the  inventor  of  the  word  for  this  new 
means  of  expression.  When,  therefore,  we  have  a  long  his- 
tory of  variations  in  any  word  we  may  depend  upon  it  that 
there  has  been  a  corresponding  series  of  social  as  well  as 
of  individual  experiences  related  to  the  word.  The  detailed 
history  of  words  is  a  detailed  history  of  individual  mental 
attitudes  toward  the  world,  and  at  the  same  time  a  detailed 
history  of  the  social  relations  in  which  individuals  have  joined. 

Illustration  of  change  in  words.  It  will  not  be  in  place  in 
this  connection  to  enter  into  any  elaborate  linguistic  studies, 
but  one  illustration  may  be  used  to  indicate  something  of 
the  character  of  the  psychological  and  social  study  which 
grows  out  of  the  history  of  words.  In  his  "  English  Past 
and  Present,"  Trench  gives  an  account  of  the  development 


SPEECH  AS  A  FORM  OF  BEHAVIOR  231 

of  the  word  "gossip."  This  word  was  originally  used  at  bap- 
tismal ceremonies  and  referred  to  the  sponsor  who  stood  for 
the  child  in  a  way  analogous  to  that  in  which  to-day  the  god- 
parent stands  as  sponsor  for  the  child.  The  first  three  letters 
of  the  word  "  gossip  "  are  derived  directly  from  the  word 
"  God,"  and  the  second  part  of  the  word,  namely  "  sip,"  is 
a  modification  of  the  word  "  sib,"  which  is  even  now  used 
in  Scotland  to  indicate  a  relative.  When  the  social  institu- 
tion of  baptism  was  a  matter  of  larger  community  signifi- 
cance than  it  is  to-day,  the  word  was  needed  to  express  the 
relationship  of  the  individuals  involved  in  the  ceremony ; 
but  being  a  general  form  of  expression  rather  than  an  image 
of  a  particular  individual,  it  came  easily  to  refer  to  other 
phases  of  social  contact  than  that  which  was  primarily  thought 
of  in  connection  with  the  baptismal  ceremony  itself.  The 
worthy  sponsors  of  the  child  unquestionably  indulged,  even 
in  the  early  days  of  the  ceremony,  in  certain  exchanges  of 
information  with  regard  to  other  members  of  the  community, 
and  this  social  function  which  the  individual  served  was  very 
readily  connected  with  the  word  coined  to  refer  primarily  to 
the  religious  function.  As  the  religious  ceremony  came  to  be 
less  and  less  elaborate,  and  there  was  a  decreasing  demand 
for  reference  to  the  religious  function,  the  word  gradually 
drifted  over  to  the  second  phase  of  meaning.  It  is  probably 
true  that  the  aberration  of  form,  which  appears  in  softening 
the  d  in  "  God  "  to  an  s,  made  this  transfer  of  meaning  easier. 
Indeed,  as  we  have  seen  at  various  points  in  our  discussions, 
words  become  true  symbols  only  because  they  are  simplified 
so  as  to  take  on  easily  new  types  of  relation.  Thus,  the 
word  "gossip"  ultimately  lost  its  original  meaning  and  came 
to  signify  something  which  it  signified  only  very  vaguely  to 
the  minds  of  those  who  first  used  it.  Furthermore,  it  is 
clear  that  this  transfer  of  meaning  is  directly  related  to  the 
development  of  the  social  institution  with  which  the  word 
was  connected.  The  mental  attitude  of  the  individual  who 


232  PSYCHOLOGY 

uses  the  word  to-day  and  the  social  character  of  the  insti- 
tution arc  both  entirely  different  from  the-  attitude  and 
institution  of  earlier  times* 

Words  as  instruments  of  thought  beyond  immediate  ex- 
perience.  (  Mher  illustrations  of  the  developments  which  take 
place  in  language  can  be  found  in  the  introduction  of  new 
words  with  new  inventions  and  new  disco. 
(  hue  the  habit  of  using  v  thoroughly  established  in 

a  community  or  individual,  it  furnishes  an  easy  method  of 
marking  any  experience  which  it  is  desired  to  consider  apart 
from  the  general  setting  in  which  that  experience  appears. 
If  today  a  civilized  individual  wishes  to  think  of  certain 
relations  such  as  the  physical  force  of  gravity,  or  the  eco- 
nomic facts  of  value,  and  to  consider  the  bearings  of  the 
factors  which  enter  into  these  relations,  he  will  devise  some 
word  or  phrase  by  which  to  mark  the  relations  and  hold 
them  clearly  before  his  thought  while  he  considers  all  of  the 
facts.  There  comes  to  be  thus  a  system  of  experiences  which 
we  are  justified  in  describing  as  constructed  in  consciousness 
for  the  purpose  of  guiding  attention  ;  these  constructs  ! 
as  contrasted  with  ordinary  mental  images,  very  little 
tent.  Indeed,  the  reduction  of  the  content  of  thought  to  the 
lowest  possible  minimum  is  the  tendency  of  all  mental  evo- 
lution. The  child  has  undoubtedly  a  more  concrete  imagery 
than  the  adult.  The  adult  finds  as  he  learns  to  use  words 
fluently  that  the  imagery  which  at  first  was  necessary  to  ex- 
plain them  falls  away.  The  result  is  that  great  ranges  of 
thought  can  be  much  condensed ;  as,  for  example,  when  all 
the  cases  of  falling  bodies  are  thought  of  at  once  under  the 
single  term  "  gravity."  In  the  discussion  of  habits  it 
shown  that  as  experience  becomes  more  completely  organ- 
ized into  habits,  the  memory  content  and  even  the  sensory 
contents  receive  less  attention.  An  organized  attitude  is  sub- 
stituted for  a  complex  of  content  factors.  In  somewhat 
analogous  manner,  words  may  be  regarded  as  means  of 


SPEECH  AS  A  FORM  OF  BEHAVIOR  233 

epitomizing  consciousness,  while  they  permit  the  highest 
type  of  ideational  elaboration  of  experience.  The  widest 
variety  of  content  factors  may  be  related  to  words ;  that  is, 
the  use  of  a  word  is  often  cultivated  under  the  guiding  in- 
fluences of  concrete  content,  as  when  the  child  builds  up 
the  idea  of  animal  through  direct  perceptual  contact  with 
dogs  and  horses.  After  a  time  the  concrete  memory  images 
attached  to  the  word  fade  out  and  leave  the  word  as  a 
substitute,  as  a  minimum  content  to  which  (as  when  the 
man  condenses  his  whole  attitude  towards  all  kinds  of  ani- 
mals into  a  single  compact  experience)  an  elaborately  organ- 
ized meaning  may  attach. 

Images  and  verbal  ideas.  When,  therefore,  we  ask  what 
it  is  that  a  person  thinks  of  in  his  use  of  a  word,  we  shall 
certainly  go  astray  if  we  attempt  to  answer  that  the  word 
calls  up  all  of  the  concrete  experiences  with  which  it  has 
been  connected  and  with  which  it  may  be  connected.  For 
example,  let  the  reader  ask  himself  what  presents  itself  in 
consciousness  when  he  sees  the  word  "  animal."  It  would 
be  still  better  if,  instead  of  choosing  some  word  thrown  into 
the  text  as  an  isolated  illustration,  we  should  ask  the  reader 
to  give  an  account  of  the  mental  experiences  through  which 
he  passed  when  he  observed  one  of  the  words  that  came 
in  the  course  of  the  general  discussion.  For  example,  what 
was  called  up  a  moment  ago  when  the  eye  passed  the  very 
definite  word  "  text "  ?  The  answer  to  these  questions  with 
regard  to  the  content  of  consciousness  at  the  moment  of 
recognition  of  words  will  certainly  not  be  that  the  mind  is 
filled  with  trains  of  concrete  images. 

Mental  attitudes  as  characteristic  phases  of  verbal  ideas. 
The  consciousness  of  a  word  has  sometimes  been  described 
as  a  feeling  or  an  attitude,  and  such  a  description  as  this 
unquestionably  comes  nearer  to  the  truth  than  does  the 
explanation  of  meaning  through  images,  which  has  some-- 
times appeared  in  psychological  discussions  of  this  matter. 


234  '   HOLQGY 

A  general  term  such  as  "  animal  "  or  "  text  the 

thought  of  the  reader  in  one  direction  or  the  other  wr 
filling  the  mind  with  definite  contei . 

ence  arises  rather  from  the  total  phrase  or  sentence;  tin- 
single  word  indicates  only  the  direction  in  which  this  content 
is  to  be  sought,  or  in  which  it  is  to  be  applied  in  some  future 
stage  of  mental  activity,  lor  example,  if  I  say  that  all  ani- 
mals are  subject  to  man's  dominion,  there  is  much  more  of 
attitude  in  the  whole  experience  than  there  is  content.  \Ye 
look  down  upon  the  animals;  we  feel  their  inferiority;  we 
recognize  ourselves  as  above  them.  The  attitude  of  mind 
experienced  is  the  all-important  fact.  There  is  an  exjx  ri- 
ence  of  personal  elation,  which  may  perhaps  I*  i  out 

into  imagery,  if  one  contemplates  it  long  enough.  '1 
one  may  turn  the  thought  into  images  by  thinking  of  him- 
self for  the  moment  as  the  representative  man  looking  r 
upon  the  animals  gathered  as  he  saw  them  in  childhood  in 
some  picture  of  Adam  naming  the  animals.  But  all  this 
concreteness  in  one's  description  of  the  animals  and  of  him- 
self is  recognized  as  too  picturesque  to  be  true  to  ordinary 
experience.  We  can  stop  and  fill  out  the  attitude  with  ap- 
propriate imagery  if  we  like,  but  we  do  not  ordinarily  do 
so.  The  truer  statement  is  that  the  idea  comes  as  a  single 
simple  attitude  and  prepares  one  to  go  on  from  a  position 
of  superiority  to  some  appropriate  sequent  relation.  The 
value  of  the  words  lies  in  the  fact  that  they  carry  experi- 
ence forward,  furnishing  only  so  much  content  as  is  neces- 
sary to  support  thought  without  overloading  experience  with 
all  the  detail. 

Other  illustrations  of  thought  relations.  Again,  take 
another  illustration  which  shows  that  there  may  be  nicety  of 
shading  in  our  thought  relations  without  much  content.  If 
we  use  such  a  word  as  "  savage,"  we  are  likely  to  take  an 
attitude  of  superiority  somewhat  analogous  to  that  taken 
toward  the  animals,  but  flavored  more  than  the  former  idea 


SPEECH  AS  A  FORM  OF  BEHAVIOR  235 

with  a  concession  of  equality.  If  we  speak  of  higher  beings, 
such  as  angels,  we  assume  an  entirely  different  attitude, 
without  necessarily  giving  ourselves  the  trouble  to  fill  in 
any  definite  content.  Indeed,  the  content  of  any  thought 
referring  to  the  higher  beings  is  recognized  everywhere  as 
more  or  less  of  a  makeshift,  in  that  we  fill  in  the  unknown 
with  such  images  as  we  can  borrow  from  ordinary  life,  the 
images  being  symbols,  not  true  representations. 

Concrete  words.  All  this  has  been  expressed  by  certain 
psychologists  in  the  statement  that  general  ideas  are  in  es- 
sence nothing  but  dispositions  toward  activity.  Here  we  have 
a  formula  which  is  very  closely  related  to  the  formula  which 
we  derived  in  our  discussion  of  the  development  of  percepts. 
There  are,  undoubtedly,  direct  motor  habits  and  consequent 
attitudes  in  connection  with  many  concrete  words.  It  is,  on 
the  other  hand,  probably  not  true  that  the  bodily  attitude  as- 
sumed when  we  think  of  the  word  "animal"  is  anything  like 
a  complete  bodily  attitude  such  as  would  be  assumed  in  the 
presence  of  animals  in  concrete  experience.  The  mental 
attitude  aroused  by  the  word  probably  has  as  its  direct  physi- 
ological parallel  a  bodily  movement  which  is  a  much-reduced 
resultant  of  earlier  direct  attitudes.  It  is  in  its  present  form 
merely  a  faint  reverberation,  significant  not  for  direct  adap- 
tation but  merely  as  a  step  in  the  development  of  a  general 
and  perhaps  very  remote  form  of  activity.  The  present  atti- 
tude is  one  of  those  indirect  forms  of  human  adjustment 
which  render  the  experience  of  man  freer  and  more  idea- 
tional  than  the  experience  of  the  animals.  The  bodily  move- 
ment in  such  cases  is  symbolical  and  transient,  assumed 
merely  for  the  sake  of  carrying  the  individual  forward  into 
a  more  complete  state  which  lies  beyond. 

Examples  of  words  arousing  tendencies  toward  action.  The 
matter  may  be  made  clear  by  considering  what  happens  when 
by  means  of  words  one  is  told  that  he  is  to  go  first  to  the 
right  until  he  reaches  a  certain  place,  and  is  then  to  turn 


236  ,<  HOLO 

toward  the  left  and  go  straight  ahead.  There  are  clearly 

I  direct  bodily  movements  aroused  by 
the  words  "  right  "  and  "  left  "  and  1  hese 

tend.  .vard  movement,  it  U  true,  .ire  not  significant  as 

present  adapt  .ronment ;  they  are  significant 

merely  because  they  give  the  thinking  individual  a  certain 
tendency,  which  may,  indeed,  work  itself  out  lat  :;mch 

more  fully  developed  and  concrete  form,  1>  present  a 

kind  of  suppressed,  incipient  form  of  action.  If  one  has 
thought  out  a  series  of  movements  toward  the  right  and  left, 
he  will  have  developed  within  himself  a  form  of  behavior 
which,  on  the  presentation  of  the  appropriate  stimulation  in 
the  form  of  the  signpost  or  building  at  which  he  is  to  turn, 
will  serve  as  a  sufficient  preliminary  organization  to  arouse  a 
significant  and  concrete  form  of  behavior.  The  preliminary 
thought  attitude  and  faint  bodily  expression  serve,  therefore, 
in  a  tentative  way  to  aid  subsequent  direct  adaptati< 

Abstract  words.  If,  now,  we  choose  as  our  illustration 
not  words  of  direction  but  abstract  phrases,  such  as  the 
phrases  by  which  men  are  exhorted  to  patriotism,  obviously 
the  emotional  stirring  which  one  feels  as  the  result  of  these 
exhortations  is  by  no  means  adequate  to  explain  the  true  sig- 
nificance of  the  word  "  patriotism."  A  man  cannot  become 
truly  patriotic  by  going  through  the  inner  stirrings  which  this 
word  arouses.  Indeed,  in  not  a  few  cases  vague  emotional 
responses  check  rather  than  promote  the  development  of  true 
interpretations  because  the  vague  response  satisfies  the  need 
of  the  mind  for  experience  but  gives  no  complete  or  adequate 
content.  The  trouble  with  the  emotional  response  lies  not 
in  the  fact  that  it  is  emotional  but  in  the  impossibility  of  its 
expressing  fully  the  whole  significance  which  the  word  must 
carry.  Such  an  abstract  term  as  that  under  discussion  can  be 
made  potent  for  direct  bodily  organization  only  when  it  is 
supplied  through  proper  settings  with  some  definite  and  final 
purpose  of  an  active  kind.  To  be  truly  patriotic  one  must  be 


SPEECH  AS  A  FORM  OF  BEHAVIOR  237 

aroused  to  some  definite  form  of  public  service.  The  final 
purpose  will  then  be  like  the  concrete  words  "  left  "  and 
"  right."  The  abstract  word  taken  alone  is  the  expression  of 
a  relation.  If  it  is  treated  as  a  final  factor  of  experience,  it 
will  dissipate  itself  in  vague  emotional  reactions. 

To  take  still  another  illustration  :  If  in  the  course  of  a 
scientific  discussion  one  is  told  that  a  certain  problem  needs 
very  much  to  be  investigated,  the  word  "  problem  "  will  arouse 
within  the  individual  some  kind  of  a  responsive  attitude  which 
can  be  described  in  a  general  way  as  an  attitude  of  hesitation, 
of  turning  hither  and  thither  in  the  search  fora  solution.  But 
the  conscious  process  will  be  more  than  the  attitude  of  hesi- 
tation and  turning,  for  it  will  have  a  form  and  significance 
determined  by  the  whole  train  of  ideas  into  the  midst  of  which 
this  attitude  of  hesitation  and  turning  is  injected.  Thus,  if 
the  problem  is  in  geology,  the  attitude  of  inquiry  will  be  very 
different  from  that  which  would  be  assumed  if  the  train  of 
thought  related  to  astronomy.  We  may  therefore  speak  of 
the  attitude  aroused  by  the  word  "problem"  as  wholly  rela- 
tional in  its  character.  Another  way  of  expressing  the  matter 
is  to  say  that  the  attitude  is  in  the  world  of  ideas  for  the  time 
being  rather  than  in  the  world  of  practical  adjustments.  We 
mean  by  such  statements  as  these  that  the  attitude  is  merely 
a  temporary  step  in  the  process  of  ideational  organization  ;  it 
is  not  an  immediate  reaction  on  any  object.  It  is  an  indirect 
and  elaborate  phase  of  adaptation  ;  it  has  value  and  signifi- 
cance because  of  the  turn  which  it  gives  to  the  ideational 
process  rather  than  because  of  the  concrete  imagery  or 
reaction  to  the  world  of  things. 

Contrast  between  concrete  images  and  abstract  ideas.  The 
indirectness  of  verbal  forms  of  consciousness  and  of  the  re- 
lated nervous  processes  involves,  as  has  often  been  noted  in 
discussions  of  language,  certain  dangers  of  possible  malad- 
justment. Concrete  images  and  direct  forms  of  experience 
cannot,  because  of  their  limited  nature,  be  turned  in  very 


238 

many  directions.  Verbal  ideas,  on  the  other  hand,  espe- 
cially if  they  are  abstract,  are  capable  of  a  great  variety  of 
connections  because  they  are  so  meager  and  schemat. 

individual  content. 

Besides  this,  there  is  a  disadvantage  in  the  use  of  ab- 
stract terms  in  that  two  individuals,  while  they  may  start 
with  the  same  general  tendency  of  attention,  may,  in  the 
course  of  the  use  of  the  words,  drift  apart,  without  U-ing  as 
clearly  conscious  of  their  divergence  from  each  other  as  they 
would  l>e  if  they  dealt  constantly  with  concrete  percepts.  It 
is  a  much  more  definite  method  .of  interchanging  ideas  to 
demonstrate  the  objects  themselves,  or  to  demonstrate  some 
concrete  representations  of  the  objects,  such  as  pictures  or 
models.  If  one  does  not  have  pictures  or  models,  he  natu- 
rally tries  to  correct  the  errors  which  are  likely  to  creep  in 
when  he  is  using  words,  by  calling  up  from  time  to  time  as 
concrete  an  image  in  the  mind  of  his  listener  as  it  is  possi- 
ble to  evoke  by  the  use  of  words.  We  all  of  us  feel  the  relief 
in  any  continued  discourse  when  a  figure  of  speech,  or  an 
illustration,  is  used.  The  figure  of  speech  gives  us  a  fairly 
concrete  image  with  which  to  deal.  The  image  in  this  case 
may  be  remote  from  the  immediate  subject  of  thought,  it  may 
be  related  to  the  present  discussion  only  as  a  kind  of  rough 
analogy,  but  the  presence  of  some  characteristic  which  illus- 
trates and  renders  concrete  the  abstract  discussion  is  a  relief 
in  the  midst  of  abstract  relational  terms  and  furnishes  the 
means  of  correcting  possible  tendencies  toward  divergence 
of  thought  between  the  speaker  and  the  listener.  An  illus- 
tration is  even  more  definite  in  its  character,  and  so  long  as 
it  calls  up  in  the  minds  of  the  speaker  and  listener  the  same 
kind  of  concrete  images,  it  is  a  direct  corrective  of  the  possible 
looseness  of  verbal  thought  and  verbal  communication. 

Particular  images  as  obstructions  to  thought.  How  far 
one  should  be  picturesque  in  his  language,  and  how  far  one 
should,  on  the  other  hand,  use  terms  which  are  not  related 


SPEECH  AS  A  FORM  OF  BEHAVIOR  239 

to  definite  mental  pictures,  is  a  matter  which  must  be  deter- 
mined by  the  demands  of  the  particular  situation  at  hand.  It 
would  be  quite  impossible  in  any  generalized  science  like 
physics  continually  to  deal  with  concrete  illustrations.  If  the 
scientist  speaks,  for  example,  of  the  general  law  of  gravity, 
he  cannot  be  dealing  with  all  of  the  specific  cases  of  gravity 
known  to  his  experience,  nor  can  he  feel  himself  bound  to  a 
single  illustration.  He  may  come  back  to  the  single  illustra- 
tion in  order  to  hold  his  verbal  idea  true  to  the  concrete  facts, 
but  he  should  cultivate  the  ability  to  get  away  from  the  con- 
crete cases  into  the  wider  sweep  of  thought  which  is  covered 
by  the  general  word. 

Ideas  or  indirect  forms  of  experience  characteristic  of  man. 
In  concluding  this  discussion  of  language  it  will  be  well  to 
reiterate  that  human  life  has  taken  on,  through  the  develop- 
ment of  indirect  modes  of  consciousness  and  behavior,  an 
aspect  which  differentiates  it  altogether  from  the  life  of  ani- 
mals. The  consequences  for  human  nature  of  the  evolution 
of  a  mode  of  reaction  such  as  speech  is,  are  unlimited  in  im- 
portance. The  full  significance  of  this  unique  mode  of  be- 
havior will  become  increasingly  apparent  as  we  canvass  in 
detail  the  problems  of  ideation  and  abstraction. 


CHAPTKK    XI 

Mi  M<  >\-\      \ND    IDEAS 

The  problem  of  describing  ideas.  Throughout  the  last  chap- 
ter reference  was  made  to  ideas  without  any  effort  to  describe 
in  full  these  important  phases  of  experience.  It  now  becomes 
necessary  for  us  to  take  up  the  treatment  of  ideas  and  of  the 
complex  processes  of  thought  which  are  made  up  of  ideas. 

The  way  has  been  prepared  for  this  discussion  by  the  con- 
clusions reached  in  all  earlier  chapters.  Let  us  review  briefly 
the  essentials  of  our  earlier  studies.  First,  animals  develop 
inner  states  in  their  efforts  to  respond  to  sensory  stimuli. 
Second,  the  higher  animals  become  increasingly  able  to  carry 
on  elaborate  internal  readjustments.  Corresponding  to  these 
elaborate  readjustments  are  certain  complexes  of  sensations 
and  certain  attitudes  which  gradually  grow  more  and  more 
highly  differentiated.  Third,  the  inner  organization  of  man 
and  his  closest  relatives  in  the  animal  world  is  such  that  ex- 
perience is  progressively  recorded  in  the  form  of  habits  of 
reaction  and  corresponding  mental  states. 

We  are  now  ready  to  ask  what  is  the  form  of  this  inner 
enriched  mental  life  which  man  develops  in  the  course  of 
experience.  Our  popular  language  is  well  supplied  with  words 
referring  to  these  products  of  experience.  We  say  that  man 
stores  up  in  memory  ideas  and  thoughts.  We  speak  of  re- 
calling the  past,  of  images  in  the  mind,  of  an  inner  world 
of  thoughts  and  thought  relations. 

Ideas  not  derived  from  present  impressions.  In  all  such 
phrases  as  the  above  there  is  a  sharp  contrast  between 
present  sensory  impressions  and  the  experiences  which  are 


MEMORY  AND  IDEAS  241 

brought  over  from  the  past.  There  is  also  a  recognition  of 
the  overwhelming  volume  of  past  experiences.  The  indi- 
vidual faces  the  world  of  the  present  moment  with  a  mind 
set  and  prepared  through  long  training.  What  we  call 
intelligence  is  not  the  impression  of  the  moment  but  a 
body  of  experiences  drawn  out  of  the  past. 

Ideas  as  revivals.  Let  us  consider  some  of  the  simplest 
types  of  ideas.  If  one  closes  his  eyes  and  thinks  of  the 
scene  which  a  moment  before  impressed  itself  upon  his 
vision,  he  will  recognize  that  his  consciousness  is  filled  with 
a  substitute  for  direct  visual  sensations  and  percepts ;  this 
substitute  is  called  a  memory  image.  When  one  thinks  of 
an  absent  acquaintance,  the  memory  image  may  contain 
factors  which  are  substitutes  for  direct  auditory  impressions 
of  the  voice.  When  one  thinks  of  a  rough  surface  without 
touching  it,  the  image  contains  substitutes  for  tactual  factors 
and  their  perceptual  organization.  These  illustrations  serve 
to  emphasize  the  scope  of  the  word  "  image,"  which  it  will 
be  seen  is  used  not  merely  for  vision  but:  also  for  all  spheres 
of  experience. 

Advantages  of  relative  independence  of  sensory  impres- 
sions. Before  taking  up  any  of  the  details  regarding  the 
character  and  laws  of  memory  images,  it  will  be  well  to 
dwell  briefly  upon  the  great  advantage  to  the  individual  of 
possessing  these  substitutes  for  direct  impressions.  The 
mind  supplied  with  memory  images  is  relatively  independent 
of  contact  with  objects ;  the  images  may  serve  as  the  basis 
for  attitudes  and  for  reconstructive  organizations  which  may 
be  of  the  highest  significance  in  individual  life.  A  common- 
place illustration  of  this  advantage  is  seen  whenever  one 
runs  over  in  his  mind  the  various  places  in  which  he  has 
been  and  where  he  might  have  left  a  lost  object.  More 
complex  illustrations  may  be  drawn  from  the  mental  activi- 
ties of  an  inventor  who  thinks  out  many  combinations,  thus 
using  the  images  in  consciousness  as  substitutes  for  real 


242  PSYCHOLOGY 

objects.  To  be  sure,  there  are  certain  disadvantages  which 
connect  themselves  with  these  advantages.  The  inventor  can 
make  more  mistakes  in  this  imagery  than  he  could  if  he 
tried  to  fit  together  real  things,  and  one's  false  memory  of 
where  he  left  his  property  may  lead  him  far  astray.  But 
taken  in  the  large,  the  freedom  from  the  necessity  of  always 
waiting  for  direct  impressions  is  one  of  the  great  superiorities 
of  the  higher  forms  of  mental  life. 

Individual  variations  in  imagery.  One  of  the  most  im- 
portant statements  to  be  made  in  the  description  of  memory 
images  is  that  different  individuals  show  great  differences  in 
the  character  and  vividness  of  their  memory  images.  Some 
years  ago  Gallon  asked  a  number  of  individuals  to  test  their 
mental  imagery  by  calling  up  as  definitely  and  fully  as  possi- 
ble the  familiar  objects  of  the  breakfast  table.  After  the 
memory  image  had  been  called  up,  the  observer  was  requested 
to  state  how  clear  the  mental  image  was  in  color  and  form 
and  other  characteristics.  Some  of  the  observers  said  that 
they  recalled  objects  with  a  vividness  and  detail  altogether 
comparable  to  their  perceptual  experience.  These  Gallon 
called  good  visualizers.  Others  described  their  memory 
images  as  extremely  vague  and  hazy.  Still  others,  who  were 
between  the  extreme  classes,  stated  that  their  mental  images 
were  restricted  in  extent  and  were  relatively  fainter  than  the 
percepts  themselves  but,  nevertheless,  fairly  comparable  in 
general  character  to  direct  sensory  experiences.  Gallon's 
tests  have  frequently  been  repeated,  and  his  results  have 
been  fully  corroborated.  Furthermore,  it  has  been  found 
that  persons  who  have  faint  visual  images  have,  in  some 
cases,  vivid  auditory  images.  Some  persons  have  vivid  tac- 
tual imagery  or  vivid  memory  of  movements.  The  blind, 
for  example,  can  have  no  visual  memories ;  their  memory 
consciousness  must  therefore  be  filled  by  a  totally  different 
type  of  contenl  from  that  which  exists  in  the  mind  of  the 
normal  individual. 


MEMORY  AND  IDEAS  243 

The  accidents  of  individual  experience  and  mental  imagery. 

Not  only  is  the  type  of  memory  very  different  in  different 
individuals,  but  the  special  contents  differ  according  to  the 
accidents  of  individual  experience.  Thus,  if  two  persons 
have  looked  at  the  same  scene  from  two  different  points  of 
view,  their  imagery  will  be  different ;  certain  near  and  vivid 
factors  for  one  person  will  be  vague  and  remote  for  the 
other.  Then,  too,  individual  attitudes  react  upon  the  con- 
tents of  experience  to  determine  the  character  of  imagery. 
If  an  especially  pleasing  or  disagreeable  color  has  been  pre- 
sented to  a  given  individual,  it  may  continue  in  his  memory 
for  a  long  time,  while  a  second  individual  looking  at  the 
same  color,  but  not  greatly  pleased  or  displeased  by  it,  may 
very  soon  forget  it  altogether. 

Dependence  on  vividness  and  recency.  In  spite  of  indi- 
vidual differences  in  mental  imagery,  there  are  certain  gen- 
eral statements  which  apply  to  all  persons  and  all  types  of 
memory.  All  other  conditions  being  equal,  memory  de- 
pends upon  the  vividness  and  recency  of  the  sensory  im- 
pression. It  should  be  noticed  that  memory  does  not  depend 
on  intensity  but  on  vividness.  If  intensity  results  in  the  con- 
centration of  attention  upon  the  impression,  then  intensity 
may  indirectly  help  to  fix  the  impression ;  but  a  faint 
impression  upon  which  attention  has  been  centered  will 
continue  in  memory  long  after  the  disappearance  of  an  im- 
pression which  passes  without  attention.  The  recency  of  an 
impression  is  also  a  matter  of  importance.  Careful  quanti- 
tative tests  show  that  impressions  fade  with  relative  rapidity 
at  first  and  at  a  very  gradual  rate  later.  We  forget  many 
impressions  entirely  in  the  first  few  moments  after  they  are 
received.  What  we  retain  beyond  the  first  brief  period  is 
more  likely  to  continue  as  a  relatively  permanent  addition 
to  the  content  of  consciousness. 

The  training  of  memory.  Much  may  be  said  with  regard 
to  the  scope  of  memory  and  with  regard  to  the  possibility 


?.\.\  PSY(  IIOLOGY 

of  increasing  the  scope  of  memory  by  training.    It  is  doubt- 
less true  th.it  tin-  ability  to  retain  impressions  differs  gi 
with  different  individuals  ;  some  retaining  many  impressions 
and  cam- ing   them   forward   through   long  periods,  or 
having  little  or  no  ability  to  retain.     So  clear  1  1  arc 

these  natural  characteristics  of  different  individuals  that  the 
changes  produced  through  practice  are  relatively  small.  In- 
deed, Professor  James  asserts  that  tin  jxtssibility  of 
changing  the  degree  of  natural  relent ivencss  through  train- 
ing. This  statement  has  been  shown  to  be  out  of  harmony 
with  the  facts,  for  there  are  evidences  of  increase  in  the 
scope  of  memory  through  training.  Nevertheless,  Pro- 
fessor James's  statement  is  probably  much  nearer  the  truth 
than  the  popular  assumption  that  memory  can  be  radically 
changed  through  practice. 

Retention  as  distinguished  from  recall.  Another  general 
fact  regarding  memory  is  that  experiences  arc  not  actively 
recalled  without  some  present  impression  or  related  memory 
which  serves  as  the  motive  or  occasion  for  the  exercise  of 
memory.  The  mere  retention  of  an  impression  is  not  the 
whole  of  memory.  For  example,  at  this  moment  there  must 
be  retained  by  every  reader  of  these  words  hundreds  of 
proper  names.  There  is  no  motive  for  the  recall  of  most 
of  them.  If  one  should  find  in  the  text,  however,  such  a 
phrase  as  "  author  of  the  Iliad,"  one  of  the  proper  names 
would  be  recalled  and  memory  would  become  active  for  that 
one  name.  This  name  might  in  turn  suggest  other  memories. 
The  fact  that  memories  are  thus  linked  together  and  that 
active  recall  is  always  a  matter  of  a  train  or  sequence  of 
processes  was  noticed  long  ago  by  Aristotle.  He  described 
the  principles  of  memory,  or,  as  they  were  later  designated, 
the  laws  of  association.  There  are  two  general  principles 
of  association  which  we  may  note :  first,  the  principle  of 
association  by  contiguity ;  and,  second,  the  principle  of 
association  by  similarity  or  contrast. 


MEMORY  AND  IDEAS 


245 


Association  by  contiguity.  When  one  thinks  of  the  letter 
A  he  is  very  likely  to  recall  also  the  letter  B,  because  the 
two4"  have  so  often  followed  each  other  in  experience.  The 
first  line  of  a  poem  suggests  the  second ;  the  sight  of  one 
of  two  intimate  friends  suggests  the  other.  In  general, 
when  two  experiences  have  been  intimately  related  in  earlier 
experience,  the  appearance  of  one  is  likely  to  serve  as  a 
sufficient  motive  for  the  recall  of  the 
second. 

Association  by  similarity.  When 
one  sees  a  face  which  has  eyes,  or 
nose,  or  mouth  like  those  of  another 
person,  the  like  feature  is  in  many 
cases  enough  to  recall  the  absent 
person.  In  such  a  case  as  this  the 
two  faces  now  associated  need  never 
have  appeared  together  in  the  past ; 
it  is  enough  that  they  contain  the 
same  feature.  This  relation  between 
two  experiences  having  a  common 
factor  is  evidently  a  more  complex 
fact  than  association  by  contiguity, 
for  it  involves  a  sufficient  analysis 
or  concentration  of  attention  upon  a 
single  feature  to  separate  it  from  its 
present  surroundings  and  make  it  the  link  of  connection  with 
a  group  of  experiences  not  now  present.  The  diagram  in 
Fig.  57  represents  the  situation.  The  circle  A  represents  a 
single  feature  of  the  face  now  seen  ;  b,  b,  b  are  the  other 
features.  In  a  past  experience,  A  has  been  part  of  a  system 
of  features  of  which  c,  c,  c,  were  the  others.  If  A  becomes 
the  subject  of  special  attention,  it  can  revive  the  elements 
c,  c,  c,  and  thus  detach  itself  from  b,  b,  b  the  features  of 
the  present  complex  in  which  it  stands.  In  general,  then, 
whenever  a  factor  of  experience  now  present  has  appeared 


FIG.  57.     Association   by 
similarity 

The  full-drawn  circles  repre- 
sent the  elements  of  the  pres- 
ent experience.  Of  these  ele- 
ments A  attaches  itself  also 
to  the  system  of  elements  rep- 
resented by  the  dotted  line 
circles.  A,  when  taken  with 
the  circles  b,  b,  b,  constitutes 
the  present  experience ;  A, 
when  taken  with  the  circles 
c ,  c,  c,  constitutes  the  recalled 
experience.  A  is  obviously 
the  center  of  relations  be- 
tween the  two  systems 


246  PSY<  HMI.<H;Y 

in  earlier  experiences  in  a  different  combination,  the  earlier 
combination  may  be  recalled  through  association  by  simil. 

Association  by  contrast.  Association  by  contrast  will  be 
clear  after  the  foregoing  discussion  of  association  by  simi- 
larity, for  no  contrast  can  exist  without  like  elements.  • 
may  contrast  a  candle  and  the  sun  because  they  both  give 
light,  or  the  moon  and  a  coin  because  they  are  both  round, 
but  in  each  of  these  cases  the  basis  of  the  contrast  is  a 
common  factor. 

New  products  evolved  in  ideation.  Thus  it  is  seen  that 
memory  images  do  not  represent  merely  the  traces  of  earlier 
experiences,  but  by  continual  association  and  readjustments 
memory  images  change  their  character  and  in  the  later 
stages  show  quite  as  much  the  effects  of  readjustments  in 
mental  life  as  the  results  of  initial  impression.  When  tuo 
ideas  have  been  associated  by  contrast,  there  is  an  analysis 
which  tends  to  break  up  the  original  memory  images  and 
bring  to  clear  consciousness  one  element  of  the  associated 
ideas  together  with  what  we  may  properly  call  the  new  idea 
of  contrast.  When  the  idea  of  contrast  arises,  the  descrip- 
tive term  "image"  becomes  less  appropriate  than  it  was 
for  the  simple  ideas  with  which  the  discussion  began. 

Ideas  not  all  images.  The  idea  of  contrast  is  an  idea  of 
a  higher  type.  It  is  very  difficult  to  state  what  is  the  con- 
tent of  such  an  idea.  It  is  a  kind  of  shock  of  difference, 
a  feeling  of  intellectual  opposition.  Indeed,  there  are  many 
psychologists  who  insist  on  the  use  of  the  term  "  imageless 
thought "  in  describing  such  an  idea.  They  mean  by  this 
term  to  draw  attention  to  the  fact  that  the  mind  deals  at 
these  higher  levels  not  with  definite  revivals  of  sensory  con- 
tent but  with  certain  tendencies  of  consciousness  which  are 
to  be  sharply  distinguished  from  memory  images.  Perhaps 
the  best  description  which  can  be  given  will  be  by  the  use 
of  an  analogy.  The  mind  is  calling  up  a  series  of  images 
when  suddenly  it  turns  in  a  new  direction.  The  abrupt 


MEMORY  AND  IDEAS  247 

turning  is  a  real  experience,  often  very  vivid  and  important 
for  all  later  thinking.  Just  at  the  moment  of  turning  there 
must  have  been  an  experience.  What  was  the  experience 
of  turning  ?  It  was  an  experience  which  linked  together 
two  images,  but  it  was  not  in  itself  an  image. 

Tendency  to  revert  to  imagery  type.  The  more  complex 
ideational  experience  becomes,  the  more  elements  there  are 
which  must  thus  be  described  as  imageless.  On  the  other 
hand,  it  is  to  be  noted  that  there  is  a  tendency  to  develop 
devices  by  which  the  mind  can  mark  and  hold  steadily 
before  it  these  imageless  ideas.  When  one  has  had  the 
experience  of  contrast,  one  tends  to  mark  the  experience 
by  a  word  which  will  give  it  enough  content  to  make  it 
a  stable  unit  in  thought. 

Advantages  of  indirect  forms  of  experience.  All  these 
statements  draw  attention  to  the  fact  that  ideas  are,  more 
than  any  other  phase  of  experience,  flexible  and  subject  to 
inner  readjustment.  Thus,  even  when  dealing  with  revivals 
of  perceptual  experiences  every  person  has  his  own  peculiar 
image  depending  on  his  point  of  observation  and  his  per- 
sonal powers  of  retention.  Courts  of  law  are  familiar  with 
this  fact  and  attempt  to  eliminate  by  comparison  of  much 
testimony  the  purely  personal  elements  which  always  attach 
to  a  memory  image. 

The  flexibility  of  ideas,  as  has  already  been  pointed  out, 
may  be  of  great  advantage  because  it  puts  the  individual  in 
possession  of  a  device  for  thinking  out  changes  in  the  per- 
ceptual world.  When  men  put  together  ideas,  they  do  so 
because  ideas  are  flexible.  If  they  get  them  put  together 
in  a  productive  way,  they  often  make  up  a  model  to  which 
later  the  hard  material  world  may  be  made  to  conform. 

We  are  brought  by  this  statement,  as  we  have  been  sev- 
eral times  before,  to  a  recognition  of  the  distinction  between 
direct  and  indirect  modes  of  adjustment  to  the  world.  The 
physiological  conditions  necessary  to  the  formation  of  ideas 


24«  PSYCHOLOGY 

are  undoubtedly  provided  for  in  the  nervous  processes  \\ 
go  on  in  the  association  areas  of  the  cerebrum.  In  the* 
lower  animals,  where  the  association  areas  are  small  or 
lacking,  there  is  little  evidence  of  ideas.  In  these  animals 
sensory  processes  pass  to  motor  discharge  with  greater 
directness  than  in  man.  In  like  manner  the  infant  seems 
to  be  wholly  absorbed  in  percepts.  This  is  related  to  the 
fact  that  the  tracts  in  the  association  areas  are  the  latest  to 
develop,  the  process  of  development  being,  as  noted  in  an 
earlier  chapter,  distinctly  traceable  for  a  period  after  birth. 
Animal  behavior  direct  and  perceptual,  human  behavior 
indirect  and  ideational.  The  significance  of  the  evolution 
of  the  association  areas  can  be  seen  by  contrasting  the 
modes  of  human  behavior  with  the  modes  of  behavior 
hibited  lower  in  the  scale  of  life.  If  an  animal  is  aroused 
to  anger  by  some  stimulation,  it  responds  by  directly  attack- 
ing the  source  of  the  stimulation.  If  an  animal  is  pleased 
by  some  form  of  agreeable .  excitation,  it  makes  clear  its 
pleasure  in  an  immediate  reaction.  There  is  in  animal  life 
very  little  delay  or  indirection  in  response.  When  we  con- 
trast all  this  with  human  life,  we  are  impressed  by  the  fact 
that  man's  activities  are  most  of  them  indirect.  They  re- 
quire more  time  to  mature.  Thus,  if  a  man  sees  an  object 
passing  before  him,  he  may  be  thrown  into  a  long  train  of 
thought  rather  than  into  a  direct  series  of  activities.  The 
long  train  of  thought  is  possible  because  man  has  a  com- 
plex central  nervous  system  through  which  the  impression 
may  circulate  before  it  passes  out  as  a  motor  impulse.  <  >r 
man's  action  may  be  indirect  in  another  sense,  as  was  shown 
in  the  chapter  on  speech.  Instead  of  attacking  the  object 
directly,  he  may  call  his  neighbor  and  talk  the  matter  over 
with  him,  ultimately  arriving  at  a  mode  of  action  only  after 
a  long  series  of  verbal  preparations  and  plans  which  are 
indirect  and  related  onlv  in  the  most  remote  fashion  to  'the 

4 

object  which  yielded  the  original  impression. 


MEMORY  AND  IDEAS  249 

The  world  of  ideas  comes  ultimately  to  be  a  world  of 
superior  importance.  Its  laws  of  association  are  free  and 
independent  of  the  world  of  things.  One  can  think  of  the 
cities  of  the  country  as  belonging  together  because  in  the 
mind  cities  are  associated,  while  in  reality  they  are  held 
apart  by  great  stretches  •  of  territory. 

Influence  of  ideas  on  things.  The  result  of  the  evolution 
of  this  inner  world  of  ideas  is  that  man  ultimately  puts 
together  not  only  in  his  mind  but  in  his  actual  conduct 
elements  of  the  world  which  would  never  have  been  put 
together  except  for  the  laws  of  mental  association.  The 
laws  of  association  are  thus  made  to  dominate  the  world 
of  things. 

Tool-consciousness.  Take,  for  example,  the  invention  of 
tools.  Primitive  man  was  cut  by  a  stone  or  torn  by  a 
thorn.  Did  he  merely  cry  out  with  pain  as  an  unintelli- 
gent animal  might  ?  Not  at  all.  He  saw  that  the  sharp 
edge  which  had  injured  him  might  be  of  great  use  to  him 
if  it  could  be  brought  into  new  relations.  So  he  picked 
up  the  stone  and  plucked  the  thorn  and  put  them  to  the 
uses  which  he  saw  first  in  his  own  mind  and  afterward 
realized  in  material  readjustments. 

Knowledge  of  nervous  process  limited.  It  must  be 
frankly  admitted  that  this  discussion  has  carried  us  beyond 
our  knowledge  of  the  conditions  in  the  nervous  system. 
We  know  in  a  general  way  what  association  areas  are, 
but  we  do  not  know  the  details  of  their  organization.  We 
know  ideas  introspectively  more  intimately  than  we  know 
their  objective  conditions. 

Traditionally,  psychology  has  begun  with  ideas  and  given 
less  attention  to  those  lower  and  simpler  forms  of  experi- 
ence with  which  we  dealt  in  earlier  chapters.  For  this 
reason  the  science  of  psychology  has  suffered  in  its  rela- 
tions to  the  biological  sciences.  Either  ideas  have  been 
thought  of  as  facts  wholly  apart  from  bodily  life  or  they 


250  reV  HOLOGY 

have  been  declared  in  a  vague  way  to  be  dependent  on 
laws  of  physical  being.  Psychology  has  oscillated  between 
a  purely  theoretical  spiritualism  and  a  crass  materialism. 
The  mind  has  been  regarded  either  as  wholly  distinct  or 
as  part  of  the  bodily  phenomena. 

Consciousness  as  product  of  evolution.  The  view  to  which 
our  study  has  led  us  can  be  expressed  in  evolutionary  terms. 
Gradually  the  animal  world,  in  working  out  its  reactions  to 
the  environment,  has  evolved  an  inner  world  conditioned 
by  indirect  and  tentative  reactions.  This  inner  world  is 
social  in  many  of  its  chanu  teristics ;  that  is,  it  is  a  world 
through  which  individuals  of  the  same  type  are  drawn  into 
sympathetic  communication.  The  inner  world  is  on- 
which  ideas  as  substitutes  for  things  are  rearranged.  The 
inner  world  is  thus  distinct  from  the  lower  levels  of  bodily 
adjustment,  but  is  at  the  same  time  a  part  of  the  economy 
of  individual  relation  to  the  world  and  is  directly  evolved 
out  of  the  efforts  at  direct  adjustment. 

Such  an  explanation  of  the  place  of  consciousness  in 
evolution  gives  us  the  fullest  justification  for  our  emphasis 
on  those  aspects  of  ideas  which  are  not  copies  or  reproduc- 
tions of  sensory  impressions  but  new  modes  of  rearranging 
experiences. 

\Ve  shall  continue  our  discussion,  accordingly,  with  a 
treatment  of  the  changes  produced  in  experience  through 
the  most  elaborate  rearrangements  in  ideas. 


CHAPTER  XII 

IMAGINATION  AND  THE  FORMATION  OF 
CONCEPTS 

Adaptation  through  ideas.  The  animal  adapts  itself  to 
its  environment  by  cultivating  better  modes  of  direct  reac- 
tion, such  as  greater  speed  of  running  or  greater  skill  in 
the  use  of  its  teeth  or  claws.  Gradually  there  appears 
in  the  highest  animals  a  new  mode  of  adjustment  in  the 
tendency  to  organize  into  social  groups.  The  social  group 
is  a  protective  device  which  gives  the  individual  greater 
strength  than  he  can  cultivate  in  his  own  individual  organ- 
ism. As  soon  as  the  social  group  evolves  there  must  grow 
up,  and  there  do  grow  up,  types  of  activity  designed  to 
hold  the  group  together.  In  man  this  latter  phase  of  evo- 
lution culminates,  and  social  cooperation  becomes  one  of  the 
dominant  facts  in  life.  No  longer  does  man  compete  with 
his  enemies  by  cultivating  greater  and  stronger  muscles ; 
he  meets  the  struggle  for  existence  by  social  cooperation. 
His  reactions  on  the  world  are  in  large  measure  indirect. 
He  invents  a  world  of  social  forms  which  can  be  described 
only  by  saying  that  it  is  an  artificial  environment  of  human 
making. 

In  a  very  real  sense  this  means  the  evolution  of  a  new 
type  of  adaptation.  The  competitions  of  human  life  are  at 
a  new  level,  wholly  different  from  those  of  animal  life. 
The  character  of  this  new  type  of  adaptation  can  be  studied 
through  an  analysis  of  one  system  of  human  behavior  such 
as  commerce,  which  has  no  parallel  whatsoever  in  the 
animal  world. 

2S1 


PSYCHOLOGY 

Early  stages  of  barter.    In  the  earliest  stages  of  exchange 

the  {uincs  t<>  the  transaction  demanded  direct  contact 
the  objects  bartered.  Even  at  this  primitive  stage  much 
self-control  and  much  regard  for  social  relations  are  ex- 
hibited. The  fact  that  men  will  barter  at  all  proves 
they  have  cultivated  ideas  to  the  extent  of  refraining  from 
mere  brutal  seizure  of  that  which  they  desire  and  to  the 
extent  of  realizing  the  possibility  of  giving  up  one  thing 
for  another.  Barter  involves  in  its  crudest  form  some 
powers  of  thought  and  some  attention  to  social  relations. 
But  barter  is  always  perceptual  in  its  demand  that  the 
commodities  to  be  exchanged  be  directly  accessible  in 
tangible  and  visible  form. 

Barter  perceptual.  The  stories  of  primitive  barter  which 
show  the  savage  duped  by  the  gaudy  color  of  cheap  wares 
bear  eloquent  testimony  to  the  fact  that  perception  is  at 
this  early  stage  not  yet  replaced  by  ideas. 

Standard  values.  After  barter  began  to  be  understood 
and  widely  practiced,  there  was  cultivated  a  desire  for  uni- 
formity ;  that  is,  for  standard  methods  of  exchange.  Some 
commodity  more  durable  in  its  qualities  than  the  rest  began 
to  serve  as  a  common  standard  to  which  all  transactions 
were  referred.  Among  hunting  tribes  all  barter  is  standard- 
ized in  terms  of  furs.  In  grazing  communities  sheep  and 
cattle  become  the  standards.  Through  the  use  of  such 
standards,  ideas  of  uniform  value  were  developed,  and  the 
mere  showy  perceptual  characteristics  of  objects  receded 
into  the  background. 

Symbolic  values.  The  next  step  in  exchange  comes 
when  some  very  permanent  commodity  takes  on  symbolic 
value.  Wampum  is  prized  not  alone  because  it  is  a  beau- 
tiful string  of  shells  but  because  it  serves  as  a  counter  and 
may  be  passed  around  as  a  promissory  note  for  future 
delivery  of  a  stipulated  number  of  pelts  or  tents  or  arrows. 
By  the  time  this  stage  is  reached  we  must  assume  high 


IMAGINATION  AND  CONCEPTS  253 

powers  of  association.  Wampum  has  value  now  because 
it  calls  up  ideas  and  because  the  social  group  in  increasing 
measure  guarantees  the  ideas  connected  with  the  symbol. 

As  with  wampum,  so  with  the  metals.  The  ideational 
values  are  finally  marked  on  the  metal.  Then  comes  the 
paper  substitute  for  the  metal  and  finally  the  various  forms 
of  commercial  credit  of  modern  commerce.  One  has  only 
to  represent  to  himself  the  scene  which  would  follow  if  a 
bank  note  were  offered  to  a  savage  hunter  in  exchange  for 
game  to  realize  how  far  from  direct  perceptual  experience 
modern  commerce  has  gone. 

Evolution  from  perception  to  ideas.  This  sketch  of  the 
evolution  of  barter  into  commercial  exchange  could  be  par- 
alleled in  every  field  of  human  action.  Manufacturing  with 
machinery  has  replaced  the  simpler  direct  contacts  of  primi- 
tive life.  Travel  by  borrowed  power  of  animals  and  finally 
by  mechanical  forces  has  largely  replaced  migration  of  the 
savage  type.  Sanitary  regulations  and  settled  modes  of  urban 
life  have  replaced  the  life  of  the  forest  and  the  wilderness. 

How  has  all  this  evolution  come  about  ?  There  is  one  and 
only  one  answer.  Man  has  learned  to  combine  and  recom- 
bine  ideas,  to  call  on  his  neighbor  for  cooperation  and  for 
the  further  comparison  of  ideas,  and  to  meet  the  needs  of 
life  indirectly  rather  than  by  direct  perceptual  responses. 

Higher  controls  of  conduct.  The  transformation  of  life 
thus  outlined  has  not  gone  on  without  bringing  about  the 
most  radical  internal  changes  in  the  mind  of  man.  To 
the  direct  and  vivid  emotions  which  accompany  instinctive 
reaction  have  been  added  trains  of  ideas  which  lead  to 
deliberate  forms  of  behavior.  Human  nature  has  become 
complex.  There  is  an  element  of  animal  life  and  of  primi- 
tive devotion  to  perceptions  in  every  man.  We  shall  never 
outgrow  instincts  or  our  native  impulses  to  seize  the  things 
about  us.  But  above  and  beyond  these  direct  modes  of 
adaptation  there  is  the  higher  world  of  ideas.  In  dealing 


254  PSYCHOLOGY 

with  this  hi-  tyj*-  nf  rxjxrricnce  has  been 

i-d.    There  . 

together  of  ideas.    There  arc  new  forms  of  displeasure 
which  come  from  the  clash  of  ideas. 

Ideational  attitudes.  For  example,  there  is  a  shock  when 
one  hears  a  profane  word  which  is  little  less  than  the  shock 
from  a  physical  blow.  The  name  of  the  Deity  has  associated 
itself  in  all  experience  with  the  attitude  of  reverence,  and 
when  this  name  is  taken  out  of  its  proper  associations  and 
used  in  a  reckless  fashion,  the  emotional  recoil  is  violent. 

Other  examples  can  be  drawn  from  the  cultivated  demands 
for  the  use  of  proper  grammatical  forms.  The  child  gradu- 
ally learns  that  a  plural  noun  demands  a  plural  verb.  The 
shock  which  comes  from  hearing  a  violation  of  this  rule  is 
quite  as  unpleasant  as  the  shock  from  a  sharp,  cold  breeze 
striking  the  skin.  Furthermore,  the  inner  muscular  recoils 
in  the  two  cases  are  not  unlike.  Both  involve,  among  other 
factors,  an  interruption  of  respiration  and  a  change  in  the 
rate  of  the  heartbeat. 

Ideas  as  substitutes  for  impressions.  When  we  speak  of 
the  world  of  ideas  as  a  real  world,  all  the  foregoing  con- 
siderations must  be  kept  in  mind.  Ideas  are  real  in  prompting 
behavior  and  in  giving  directions  to  our  acts.  Ideas  may 
be  followed  by  habitual  reactions  until  they  come  to  demand 
these  reactions  quite  as  much  as  do  things  seen  through 
the  eye  or  heard  through  the  ear.  Ideas  may  influence  the 
train  of  attention  quite  as  much  as  percepts.  For  example, 
the  man  who  is  lost  in  thought  does  not  attend  to  the  ob- 
ject coming  toward  his  eyes.  In  short,  ideas  have  values 
comparable  in  all  respects  to  percepts  and  in  some  respects 
quite  superior. 

Imagination  as  reorganization  of  ideas.  In  this  chapter 
we  shall  discuss  some  of  the  changes  which  take  place  in 
this  world  of  ideas,  for  it  is  important  if  we  are  to  under- 
stand the  world  in  which  man  lives  that  we  shall  know  the 


IMAGINATION  AND  CONCEPTS  255 

laws  of  change  in  his  world  of  ideas.  In  an  earlier  connec- 
tion the  laws  of  memory  were  discussed.  It  was  there 
shown  that  in  some  measure  the  mind  holds  its  ideas  fixed 
and  brings  them  back  under  proper  conditions  so  that  past 
experiences  may  operate  in  present  surroundings.  When 
ideas  are  thus  carried  forward,  they  are  called  memories  in 
the  strict  sense,  or  sometimes  they  are  called  images.  It 
was  pointed  out  in  that  earlier  treatment  of  the  matter  that 
memories  undergo  a  change  in  experience.  We  now  turn 
to  the  more  elaborate  types  of  such  change.  For  these 
types  of  change  there  are  a  number  of  names.  Sometimes 
ideas  are  described  as  imaginations.  This  term  is  used  to 
indicate  that  a  mere  rearrangement  of  elements  of  memories 
has  been  made.  One  imagines  a  horse  with  wings.  The 
source  of  the  idea  "  horse  "  is  memory,  likewise  of  the  idea 
"wings,"  but  the  union  of  these  two  sets  of  ideas  is  an  act 
of  the  imagination.  When  the  combinations  which  go  on 
in  consciousness  are  purely  capricious,  we  speak  of  fanciful 
imaginations.  When,  on  the  other  hand,  recombinations  of 
mental  processes  are  worked  out  systematically  and  coher- 
ently, we  speak  of  scientific  imagination.  Thus  a  dragon  is  a 
fancy ;  the  imagination  of  a  Columbus  or  a  Watt  is  scientific 
and  constructive. 

Personifying  imagination.  One  of  the  most  primitive 
forms  of  imagination  is  that  exhibited  by  savages  when 
they  attribute  to  inanimate  objects  the  personal  character- 
istics which  they  find  in  themselves.  The  savage  never 
thinks  of  thunder  or  of  the  wind  without  putting  back  of  it 
in  his  imagination  some  personal  agency.  This  form  of  con- 
structive thought  is  the  simplest  which  could  originate  in 
a  personal  consciousness.  An  emotion  of  anger  is  a  more 
direct  explanation  for  a  natural  catastrophe  than  is  some 
abstract  statement  referring  to  physical  force.  To  modern 
thought  the  myths  of  early  peoples  seem  like  the  play  of 
the  most  capricious  imagination  ;  to  the  mind  untrained  in 


256  <  HOLOGY 

the  forms  of  critical  scientific  imagination  nothing  could 
be  more  natural  than  a  myth.  Even  the  trained  mind 
derives  pleasure  from  the  personification  of  objects,  because 
it  is  easy  to  use  the  factors  from  personal  experience  in  all 
manner  of  combinations. 

Imaginations  occasions  of  useless  activities.  Karlv  man 
was  led  by  his  imaginations  to  undertake  many  useless 
forms  of  activity.  Thus,  he  attempted  to  propitiate  the 
personalities  which  his  own  mind  had  put  into  streams  and 
mountains  and  trees.  There  was  no  direct  evidence  that 
his  imaginations  were  not  in  conformity  with  the  facts,  and 
hence  the  imaginations  went  on  increasing  in  complexity 
until  they  broke  down  by  their  own  incoherency. 

Critical  tests  of  imaginations.  This  reference  to  the  fanci- 
ful imaginations  of  primitive  man  introduces  us  to  the 
discussion  of  the  more  productive  forms  of  imagination  in 
which  the  mind  does  not  weave  together  factors  of  experi- 
ence capriciously,  but  under  the  guidance  of  conditions 
which  limit  the  freedom  of  the  constructive  process.  When 
imagination  is  used  for  purposes  of  practical  construction, 
or  for  the  later  purposes  of  science,  its  products  must  be 
subjected  to  critical  examination  by  the  individual  who 
develops  them.  A  first  principle  of  criticism  of  imagination 
may  be  described  as  the  principle  of  empirical  test  through 
application.  The  constructs  of  imagination  may  be  used  to 
guide  activities,  and  if  the  activities  are  not  successful,  it 
will  obviously  be  necessary  to  go  over  again  the  combinations 
which  were  worked  out  in  consciousness  and  to  revise  these 
combinations  with  a  view  to  making  them  more  suitable 
bases  for  action.  We  may  speak  of  this  form  of  criticism 
as  the  practical  or  empirical  test  of  imagination.  If,  for 
example,  a  given  individual  finds  that  he  must  get  across 
a  certain  stream,  he  is  likely,  if  he  has  time  and  the  neces- 
sary mental  development,  to  consider  first  in  imagination 
the  means  by  which  he  can  get  across.  He  determines  in 


IMAGINATION  AND  CONCEPTS  257 

thought  that  it  would  be  possible  by  bringing  together 
certain  appliances  to  make  the  passage  easy.  If,  on  trying 
the  expedients  which  have  suggested  themselves  in  his 
thought  process,  he  finds  that  the  idea  is  a  good  one, 
his  imagination  receives  the  confirmation  which  comes  from 
practical  utility.  If,  on  the  other  hand,  his  imagined  device 
breaks  down  when  put  to  the  practical  test,  he  will  be  led 
to  further  considerations  of  a  more  elaborate  character,  in 
order  to  correct  the  deficiences  which  have  been  shown  by 
the  practical  test  to  exist  in  his  imagination. 

Empirical  test  often  inapplicable.  There  are  many  ideal 
constructions  which  cannot  be  subjected  directly  to  practical 
tests.  For  example,  in  the  course  of  human  history  man  has 
constantly  been  trying  to  reconstruct  in  imagination  the  process 
of  the  development  of  the  earth  on  which  he  lives.  Our  modern 
science  of  geology  is  an  elaborate  effort  to  reconstruct  the 
history  of  the  earth.  Obviously,  the  ideas  reached  by  geology 
cannot  be  tested  by  any  single  practical  act.  Man  has  de- 
veloped, accordingly,  a  system  of  criteria  by  which  he  tests 
the  validity  of  his  ideal  constructions,  even  when  these  ideal 
constructions  are  not  directly  intended  for  the  practical  uses 
of  life.  These  theoretical  criteria,  as  we  may  call  them,  can 
be  shown  to  grow  out  of  the  nature  of  experience  itself. 

The  test  of  internal  agreement.  It  is  demanded  by  every 
human  consciousness  that  the  elements  of  any  given  idea 
shall  be  harmonious.  We  have  seen  that  it  is  true  of  per- 
ceptual processes  that  they  have  unity  and  arrangement,  such 
that  all  of  the  conflicting  qualitative  factors  are  provided  for 
in  a  single  experience  through  the  arrangement  of  the  ele- 
ments of  experience  in  spatial  and  temporal  series.  Thus, 
even  in  perceptual  consciousness,  a  certain  coherency  and 
harmony  are  required  of  the  elements  before  they  can  enter 
into  the  percept.  Still  more  when  we  come  to  the  constructs 
of  imagination  is  there  a  demand  for  harmony  of  relations 
among  the  factors  which  are  presented.  Thus  it  would  be 


258  PSYCHOLOGY 

difficult  t<>  think  of  one  physical  substance  as  subject  to  gravity 
and  another  as  not.  If  any  factor  or  relation  is  recognizably 
incongruous  with  the  system  of  experiences  into  which  it  is 
introdua-d,  then  that  system  of  experience  will  have  to  be 
rearranged  until  the  whole  organization  is  adapted  to  the  re- 
ception of  thr  dement  which  was  out  of  harmony  with  the 
other  elements,  or  else  the  incongruous  element  will  have  to 
be  rejected.  Thus,  if  all  substances  fall  toward  the  earth  and 
smoke  rises,  we  must  devise  an  explanation.  Scientific  imagi- 
nation, when  not  susceptible  to  practical  tests,  is  thus  nothing 
more  nor  less  than  the  effort  to  develop  an  elaborate  system 
of  congruous  ideas. 

The  criterion  of  coherency  a  product  of  development. 
Primitive  man  does  not  have  this  criterion  of  the  harmony 
of  all  of  the  elements  of  thought  as  fully  developed  as 
does  modern  science.  This  is  in  part  due  to  the  limitations 
of  primitive  exjx'rience  :  as  when  a  savage  believes  thunder 
to  be  a  voice  because  he  knows  little  of  either  the  thunder 
or  of  the  mechanism  which  produces  the  voice.  It  is  in 
part  due  to  a  general  uncritical  attitude :  as  when  in  Greek 
mythology  the  earth  is  borne  upon  the  shoulders  of  Atlas 
because  attention  was  not  ordinarily  concentrated  on  the 
necessity  of  supporting  Atlas. 

The  demand  for  coherency  as  exhibited  in  constructive 
scientific  ideas.  It  cannot  be  asserted  that  the  criterion  of 
harmony  among  the  elements  of  imagination  is  applied  with 
full  success  even  in  modern  science,  but  examples  can  be 
given  without  limit  of  its  application.  Thus,  it  is  quite  im- 
possible for  us  to  think  of  the  earth  and  the  sun  as  related 
to  each  other  without,  at  the  same  time,  conceiving  of  some 
kind  of  bridge  between  the  earth  and  the  sun.  Science  has 
therefore  developed  the  notion  of  the  ether  as  a  continuous 
substance  between  the  earth  and  all  other  points  in  the  uni- 
verse. The  ether  is  not  a  factor  of  direct  experience  in  any 
form.  It  is  demanded  in  scientific  considerations  in  order  to 


IMAGINATION  AND  CONCEPTS  259 

make  the  idea  of  the  solar  system  and  of  the  universe  a  co- 
herent thinkable  idea.  Ether  may,  accordingly,  be  called  a 
product  of  imagination.  This  statement  does  not  deal  with 
the  question  of  its  objective  reality ;  it  merely  asserts  that 
ether  comes  into  scientific  experience  in  response  to  a  demand 
for  harmony  in  the  ideational  system,  not  through  perception. 
Uncritical  imaginations.  The  extent  to  which  imaginations 
are  criticized  depends  upon  the  development  of  the  individ- 
ual who  possesses  them  and  upon  the  type  of  ideas  under 
examination.  A  good  illustration  of  the  dependence  of  criti- 
cism on  individual  development  was  given  above  in  discuss- 
ing the  myths  of  primitive  peoples.  Another  may  be  found 
in  the  imaginations  of  children.  It  has  frequently  been  said 
that  children  are  more  imaginative  than  adults.  This  state- 
ment is  based  on  the  observation  that  a  child  will  imagine 
many  things  in  connection  with  its  toys  and  derive  a  great 
deal  of  satisfaction  from  these  imaginations,  when  an  adult 
would  be  so  clearly  conscious  of  the  falsity  of  the  imagina- 
tions that  he  would  derive  little  pleasure  from  them.  This 
observation  does  not  show  that  the  child  is  more  imaginative 
than  the  adult,  but  it  shows  that  the  imaginations  in  early  life 
are  not  subjected  to  any  careful  criticism.  Almost  any  men- 
tal combination  is  accepted  by  the  child  and  enjoyed  for  the 
moment  without  serious  criticism.  Indeed,  the  child's  experi- 
ence is  often  like  the  savage's,  too  meager  to  make  it  possi- 
ble for  him  to  construct  any  systems  of  thought  that  shall 
constitute  the  basis  for  the  criticism  of  his  particular  imagi- 
nation. Furthermore,  many  of  the  child's  activities  are  not 
sufficiently  serious  to  constitute  practical  tests  for  his  imagi- 
native constructs.  As  life  goes  on  and  the  systems  of  thought 
become  more  and  more  closely  united  with  each  other,  and 
the  practical  demands  of  individual  existence  come  to  be 
more  strenuous,  the  indulgence  in  fanciful  imaginations  un- 
checked by  criticism  becomes  less  common  than  it  was  in 
early  childhood. 


260  PSYCHOLc  N 

Literary  imagination  and  the  canon  of  coherency.  An  illus- 
tration of  the  way  in  whii  h  the  products  of  ;ion  may 
be  subjected  to  different  kinds  of  rniiiixm  is  to  be  found  in 
the  case  of  literary  forms.  Literature  is  an  effort  to  construct 
through  the  of  imagination  a  system  of  thought 
which  deals  with  human  interests  and  human  activities.  If 
this  constructive  process  purports  to  be  held  closely  in  agree- 
ment with  certain  rci  call  it  historical  in  character, 
and  we  demand  that  it  shall  conform  to  the  canons  of  con- 
gruity  with  all  the  legitimate  records  of  the  period  in  question. 
If  the  construction  is,  on  the  other  hand,  confessedly  free 
from  any  particular  reference  to  definite  situations,  we  call  it 
imaginative  literature  and  recognize  its  product  as  fir 

i  in  this  case  we  demand  of  literature  that  it  shall  have 
relation  to  experience.  A  wholly  unnatural  creation  has  no 
justification,  even  in  fiction.  The  particular  circumstances 
which  are  grouped  together  may  be  circumstances  which 
never  were  brought  together  in  the  course  of  human  history 
or  individual  life,  but  the  principles  of  combination  must 
be  recognizable  as  principles  in  harmony  with  the  general 
nature  of  human  experience. 

The  canons  of  criticism  in  literature  are  by  no  means  as 
clearly  definable  as  are  the  canons  of  criticism  in  scientific 
thought.  The  reason  for  this  is  that  literature  includes  wide 
variations  in  types  of  individual  experience  and  consequently 
permits  laxness  in  the  demand  that  the  imagined  experiences 
shall  conform  to  the  particular  type  of  any  individual's  life. 
It  is  not  difficult  for  us  to  accept  certain  rather  grotesque  and 
unusual  combinations,  provided  these  combinations  of  experi- 
ence are  referred  to  periods  in  time  or  points  in  space  remote 
from  those  with  which  we  are  ordinarily  in  contact. 

The  uncritical  forms  of  thought  which  preceded  science. 
The  beginnings  of  what  we  call  scientific  thought  are  obscure, 
because  the  careful  comparison  of  scientific  ideas  is  preceded, 
at  times  by  much  practical  adjustment  of  activity  to  the 


IMAGINATION  AND  CONCEPTS  261 

environment  and,  at  other  times,  by  much  uncritical  specula- 
tion. The  practical  effort  to  adjust  one's  activities  to  the 
world  leads  to  certain  systems  of  ideas.  Thus,  the  child 
always  looks  for  the  causes  of  the  happenings  which  come 
into  his  experience  long  before  he  formulates  in  clear,  explicit 
thought  the  statement  that  every  event  has  a  cause.  When 
he  hears  a  noise,  he  has-a  vague  notion  of  something  back  of 
the  noise.  In  the  same  way  men  must  have  sought  causes  in 
practical  life  long  before  there  was  any  science.  They  also 
had  ideas  which  they  used  in  the  constructive  activities  of 
life,  such  as  ideas  regarding  the  strength  and  durability  of 
certain  building  materials.  In  addition  to  these  practical 
ideas  there  were  speculative  ideas.  Superstitions  of  all  kinds 
flourished  in  the  uncritical  thought  of  primitive  man.  If  a 
bird  flew  across  his  path,  he  thought  of  infinite  varieties  of 
good  or  ill.  There  is  a  certain  sense  in  which  all  these 
superstitious  and  practical  ideas  constitute  the  beginnings 
of  science.  They  furnished  the  thought  material  which, 
when  sifted  and  organized  into  systematic  form,  constitutes 
science.  The  methods  for  sifting  and  organizing  this  thought 
material  are  the  essential  additions  to  mental  life  which  came 
with  science. 

First  sciences  limited  to  facts  remote  from  life.  When 
the  systems  of  coherent  ideas  began  to  emerge  from  the 
original  chaos  of  practical  and  superstitious  constructs,  it  is 
striking  that  the  facts  remote  from  individual  control  were 
the  earliest  to  yield  to  the  organizing  endeavors  of  thought. 
It  was  possible  to  construct  a  system  of  consistent  scientific 
ideas  regarding  celestial  movements,  because  these  remoter 
facts  were  far  enough  from  individual  life  to  be  observed 
without  perplexing  minor  incongruities.  The  nearer  facts  of 
any  situation  are  too  full  of  variations  to  fall  into  anything 
like  an  harmonious  system  without  the  most  elaborate  idea- 
tional  reconstruction.  Thus,  a  science  of  social  relations  and 
a  science  of  mental  processes  could  develop  only  after  man 


262  VCHOLOGY 

had  become  so  thoroughly  devoted  to  the  forms  of  scientific 
thought   that  he  could  follow  facts  in  long  series,  could 
deliberately  assume  some  attitude  other  than  that  of  direct 
personal    relationship,  and,    consequently,    could    tract 
certain   attract    ;  in    the   midst  of   the  compl* 

lements. 

Scientific  concepts.     Let  us  consider  one  of  the  I 

:  i  nets  built  up  in  the  <  :  the  development  of  ; 

ic.il  science.    Surh  a  construct  is  called  .1 
An  example  of  such  a  concept  is  that  of  the  atom, 
found,  as  he  examined   tin-   bodies  about   him,  that  these 
bodies  underwent  certain  changes  which  were  indicative  of 
unperceived  characteristics.     It  was  important  to  understand 
these  characteristics  in  dealing  with  the  bodies  for  pnu 
purposes.    For  example,  water  Atones  crumble,  n. 

expand  and  contract  \\ith  changes  in  temperature.  Man  must 
have  noted  many  of  these  changes  and  many  of  their  condi- 
tions very  early  in  his  dealings  with  such  substances,  but  he 
had  no  direct  means  of  observing  what  went  on  in  the  mass 
of  the  matter  itself.  He  therefore  set  about,  at  least  as  far 
back  as  the  early  Greeks,  trying  to  form  some  idea  of  the 
changes  which  must  take  place  within  the  substance,  in  order 
to  explain  the  changes  which  he  observed.  Certain  of  the 
Greek  thinkers  drew  upon  the  forms  of  experience  with 
which  they  were  familiar — namely,  their  experience  of  com- 
posite matter  made  of  separate  parts  —  and  formulated  the 
concept  that  all  substances  are  made  up  of  particles  which 
are  separated  by  intervals  of  space.  They  concluded,  further, 
that  the  particles  which  they  assumed  as  the  elements  of  the 
substance  must  be  capable  of  greater  and  less  separation 
from  one  another,  as  in  expansion  and  contraction,  and  also 
that  they  must  be  capable  of  rearrangements,  such  that  the 
appearance  of  the  whole  substance  is  modified  without  de- 
stroying the  particles.  Through  such  considerations  as  these, 
some  of  the  early  scientists  came  ultimately  to  refer  to  the 


IMAGINATION  AND  CONCEPTS  263 

smallest  particles  of  any  given  substance  as  atoms,  and  to 
describe  these  atoms  as  separated  from  one  another  by  space, 
and  as  constituting  by  their  composition  the  observed  body. 
The  physicist  or  chemist  to-day  uses  this  very  valuable  con- 
cept in  his  thought  about  substances ;  he  constantly  refers 
to  atoms,  although  he  never  expects  that  he  will  be  able  to 
see  an  atom,  or  to  test  the  validity  of  his  mental  construct 
by  the  sense  of  touch.  Indeed,  the  atom  is  an  idea  needed 
by  science  just  because  science  has  to  bring  together  into 
an  harmonious  ideal  system  more  than  can  be  discovered  in 
any  single  inspection  or  handling  of  an  object. 

Validity  of  concepts.  When  such  statements  as  these  are 
made,  some  persons  think  that  the  validity  of  the  scientific 
concept  is  seriously  called  in  question.  On  the  contrary, 
there  is  no  higher  guarantee  for  any  form  of  knowledge 
than  that  it  is  demanded  in  order  to  render  congruous  the 
whole  system  of  experience.  As  we  have  seen,  in  all  of  the 
earlier  discussions  of  perception  and  ideation,  experience  has 
many  higher  phases  which  cannot  be  resolved  into  direct 
sensory  elements.  The  validity  of  space  as  a  form  of  ex- 
perience cannot  be  called  in  question  because  it  is  a  relational 
rather  than  a  sensational  phase  of  experience.  For  similar 
reasons,  the  construction  of  a  concept  is  justified  as  a  result 
of  a  higher  organization  of  experience.  The  method  of  arriv- 
ing at  such  an  ideal  construct  is  indeed  indirect ;  but  the 
concept  has  all  of  the  validity  which  belongs  to  experience 
as  an  organized  system. 

Abstraction.  When  ideas  are  completely  under  the  con- 
trol of  the  individual,  they  may  be  arranged  according  to 
principles  which  are  set  up  by  thought  itself.  Thus,  one 
may  decide  that  it  is  desirable  to  group  together  all  round 
objects  or  all  hollow  objects.  There  then  arises  an  idea  of 
roundness  or  of  hollowness  which  is  called  an  abstract  idea. 
The  term  "  abstract "  means  thr.t  something  has  been  "  cut 
off."  When  we  think  of  roundness  alone,  we  neglect  color 


PSYCHOU 

and  position  and  weight.    \Vc  can  cut  off  the  one  quality 
and  inaki-   it  a  subject  of  attention  because  the  \ 
thought  has  been  developed  to  the  point  where  inner  motives 
are  stronger  than  external  motives. 

Generalization.    Furthermore,  whem  :nind  reaches 

the  stage  where  it  can  select  and  concentrate  on  single  as- 
pects or  attributes  of  experience,  it  can  at  the  same 
group  together  under  each  selected  attribute  many  individual 
cases.  This  is  called  the  power  of  generalization.  Thus, 
once  the  mind  has  fixed  on  roundness  as  a  selected  attribute 
of  objects,  it  can  bring  together  and  group  in  one  class  the 
earth,  a  ball,  an  apple,  etc. 

Abstraction  and  generalization  are  valuable  not  merely  as 
feats  of  inner  control ;  they  make  possible  highly  developed 
forms  of  conduct.  If  one  can  select  and  hold  steadily  be- 
fore the  mind  one  aspect  of  an  object,  conduct  can  be  made 
more  effective  through  concentration  than  when  the  observer 
is  distracted  and  confused  by  an  effort  to  deal  with  unanalyzed 
complexity. 

We  shall  find  ourselves  coming  back  to  this  topic  later 
when  we  take  up  volition  as  the  highest  form  of  behavior. 
The  more  fully  ideas  are  abstracted  and  generalized,  the 
more  conduct  will  be  guided  by  inner  motives.  The  man 
who  sees  values  in  objects  and  decides  to  be  thrifty  is  guided 
by  an  abstraction  and  is  so  far  forth  acting  in  response  to 
an  inner  motive. 

Judgments  and  reasoning.  After  a  concept  has  been  for- 
mulated, it  may  become  part  of  a  still  more  complex  mental 
process  which  includes  several  ideas.  Thus,  when  two  con- 
cepts are  related  as  in  the  statement  "  The  sun  is  the  center 
of  the  solar  system,"  the  whole  process  is  termed  a  judgment. 
When  two  or  more  judgments  are  united  for  the  purpose 
of  setting  up  an  even  more  complex  combination,  the  whole 
process  is  called  reasoning.  An  example  of  reasoning  is  as 
follows:  The  sun  is  the  center  of  the  solar  system:  any 


IMAGINATION  AND  CONCEPTS  265 

central  body  in  a  system  of  this  type  must  have  a  control- 
ling influence  over  the  other  members  of  the  system  ;  hence 
we  should  look  for  the  control  of  the  sun  over  the  earth  and 
the  other  planets. 

Logic.  It  is  not  in  place  here  to  give  an  account  of  the 
various  types  of  judgment  and  reasoning.  It  is  the  function 
of  the  science  of  logic  to  study  the  complex  processes  of 
'thought  and  to  develop  the  rules  under  which  the  validity 
of  these  processes  may  be  tested.  We  must  content  our- 
selves in  an  introductory  treatment  such  as  this  with  certain 
comments  which  will  serve  to  call  attention  to  the  psycho- 
logical character  of  these  complex  forms  of  ideational  experi- 
ence. Perhaps  the  best  single  topic  with  which  to  introduce 
a  psychology  of  logic  is  the  topic  of  belief.  Let  us  consider, 
therefore,  what  is  meant  by  the  statement  "  I  believe  a 
certain  conclusion  to  be  true." 

Primitive  belief.  The  first  and  most  direct  case  of  belief 
is  that  in  which  I  assent  to  any  combination  of  ideas  be- 
cause my  natural  tendency  is  to  accept  combinations  of  ideas 
when  there  is  no  reason  to  deny  what  is  presented.  The 
psychological  fact  is  that  ideas  which  stand  together  in  the 
mind  unchallenged  by  other  experiences  are  accepted  as 
coherent  and  acceptable.  Thus,  when  I  was  a  child  I  be- 
lieved in  Jack  the  Giant  Killer  and  Jack  and  the  Bean  Stalk 
because  my  experience  was  too  limited  to  deny  these  stories. 

Belief  after  hesitation.  A  higher  form  of  belief  comes 
after  one  has  hesitated.  In  such  cases  the  statements  are 
not  immediately  accepted.  This  means  that  they  arouse 
series  of  associations  which  suggest  various  conflicting  forms 
of  statement.  At  this  stage  there  is  a  restlessness,  and  other 
forms  of  statement  are  tried  ;  other  authorities  are  cited.  It 
may  be  that  one  goes  out  and  tests  the  conclusion  by  practi- 
cal behavior.  If  the  first  opposition  is  broken  down  by  one 
or  the  other  of  these  influences,  there  results  in  the  end  a 
waning  of  the  suggested  contradictions. 


v',  IIOLOGY 

Belief  a  positive  psychological  fact.  There  can  be  no 
doubt  that  belief  in  all  these  cases  is  something  more  than 
the  nun  hearing  of  certain  sounds  or  the  mere  coupling 
together  of  certain  ideas.  When  we  say  that  the  idea  is 
accepted,  we  undoubtedly  refer  to  some  positive  physiolog- 
ical process.  Belief  is  related  to  the  fact  that  a  sensory 
impression  goes  through  the  nervous  system  to  some  form 
of  positive  expression  without  being  opposed.  If  it  were 
checked  by  encountering  some  current  opposing  it,  we 
should  l>  s  and  the  feeling  would  be  one  of  hesita- 

tion. Assent  is  a  genuine  process  of  a  positive  type.  Such 
a  positive  process  will  usually  issue  in  a  definite  motor  re- 
sponse. It  may  be  that  the  motor  process  is  a  mere  nod 
of  the  head  or  an  inner  emotional  twinge.  The  important 
fact  is  that  the  nervous  process  issues  in  a  positive  dis- 
charge. The  motor  discharge  may  be  in  itself  insignificant, 
but  the  fact  .that  it  occurs  and  the  fact  that  it  is  positive 
in  character  give  to  experience  that  special  turn  or  coloring 
which  we  designate  by  the  term  "  belief." 

Spurious  verbal  belief.  Such  considerations  lead  to  brief 
comment  on  what  is  called  mere  verbal  assent.  It  is  possi- 
ble for  one  to  give  assent  carelessly  by  merely  repeating 
what  he  hears.  Many  students  accept  what  they  find  in 
books  in  this  way.  The  motor  paths  leading  to  the  speech 
centers  seem  to  be  stimulated  directly  by  the  eyes  as  they 
read,  or  by  the  ears  as  they  hear.  Reaction  is  of  little  value 
in  such  cases.  It  is  a  kind  of  shunt  circuit.  The  impres- 
sion does  not  get  mixed  in  the  association  areas  with  any 
forms  of  ideation  which  confuse  or  interrupt  the  direct 
transmission  to  the  speech  center.  The  result  is  a  specious 
belief  and  a  useless  form  of  nervous  and  mental  reaction. 
There  is  nothing  more  fatal  to  true  mental  organization 
than  this  short-circuiting  of  the  eyes  and  ears  to  the  vocal 
centers.  It  is  one  of  the  penalties  which  man  pays  for  the 
development  of  an  indirect  mode  of  behavior. 


IMAGINATION  AND  CONCEPTS  267 

Habitual  belief.  Another  highly  developed  form  of  belief 
is  that  which  comes  from  the  organization  in  individual  life 
of  certain  habitual  modes  of  response.  Thus  the  physicist 
learns,  in  spite  of  sensory  testimony  to  the  contrary,  to 
think  of  every  substance  as  porous.  He  finds  that  his  be- 
liefs are  all  conditioned  by  conformity  to  this  cultivated 
idea.  If  any  remark  is  made  or  any  fact  turns  up  which 
runs  counter  to  this  accepted  principle,  the  new  proposal 
will  be  rejected.  Beliefs  are  thus  not  unlike  the  funda- 
mental emotional  attitudes.  They  are  very  real  factors  in 
thought,  though  they  are  not  made  up  of  memory  images. 

Religious  belief  not  instinctive.  Certain  writers,  im- 
pressed with  the  similarity  of  beliefs  to  emotional  attitudes, 
have  regarded  certain  well-established  beliefs,  such  as  reli- 
gious beliefs,  as  instinctive.  The  belief  in  the  Deity,  in  im- 
mortality, in  the  certainty  of  moral  categories,  is  held  by 
these  authors  to  be  no  less  primitive  in  human  nature  than 
the  fundamental  desire  for  food,  for  physical  comfort,  and  for 
companionship.  On  the  other  hand,  it  is  held  by  others  that 
such  beliefs  are  the  results  of  developed  systems  of  ideas. 

Sentiments  not  instinctive.  The  latter  formula,  which  is 
the  more  defensible,  suggests  the  explanation  of  many  of 
the  so-called  sentiments  and  tastes  of  later  life.  They  are 
connected  with  acquired  modes  of  behavior.  Certainly,  if 
one  studies  the  life  and  practices  of  savages,  he  finds  a 
striking  parallelism  between  behavior  and  tribal  belief.  The 
savage  practices  certain  customs,  and  they  come  to  have  for 
him  the  sanction  of  the  highest  religious  demands.  So  in 
civilized  life  as  well.  The  sanctions  of  society  are  bred  into 
our  very  beings  until  we  believe  in  the  necessity  of  social 
conformity. 

Social  life  and  the  higher  mental  processes.  Efforts  have 
been  made  in  the  recent  literature  of  sociology  and  psychol- 
ogy to  explain  social  institutions  as  the  products  of  instinc- 
tive tendencies.  The  argument  of  this  chapter  is  that  belief 


I'N\<  II 

li  grows  out  of  .\  thinking,  while  it  may  have 

the  appearance  of  an  instinctive  emotion,  is  in  realit. 
product  of  the  highest  types  of  mental  activity.  Social 
sanctions  are  evolved  through  association  and  comparisons 
of  ideas  and  through  the  evolution  of  modes  of  social  be- 
havior. Society  may  rest  on  instinctive  tendencies,  but  its 
forms  and  operations  are  all  worked  out  through  the  use  of 
language.  1  :  .,•.;.<•:<•  m  social  life  one  finds  abstract 

of  a  higher  type,  now  of  a  lower.   Social  life  is  a  prou 
uct  of  thought  and  ideation,  not  of  blind  instinct. 

Fields  for  the  application  of  psychology  of  ideas.  This 
chapter  must  close  with  these  mere  outlines  of  discus 
of  the  higher  mental  life.  That  there  is  a  field  for  a  psy- 
chological study  of  all  the  higher  forms  of  appreciation  is 
indicated  by  what  has  been  said.  This  matter  will  be 
touched  on  again  in  a  later  chapter  dealing  with  the  appli- 
cations of  psychology. 

There   :  chology  of  invention  in  which  the  indi- 

vidual is  studied  at  those  critical  moments  when  a  new  set 
of  associations  is  being  evolved  within  him.  There  is  a 
psychology  of  education  which  must  distinguish  betv 
learning  of  a  true  type  and  learning  to  repeat  words  out  of 
books.  There  is  a  psychology  of  social  theory  and  social 
conduct.  The  formula  for  all  of  these  is  a  formula  of  organ- 
ized mental  processes  leading  to  various  forms  of  expres- 
sion. If  the  student  has  grasped  the  import  of  this  general 
formula,  he  will  be  able  to  unravel  the  particular  types  of 
organization  which  appear  in  each  of  these  sphc: 


CHAPTER  XIII 
THE  IDEA  OF  THE  SELF 

The  idea  of  self  sometimes  regarded  as  matter  of  direct 
knowledge.  Among  the  ideas  which  are  built  up  in  practical 
life  and  refined  by  scientific  study,  there  is  one  which  is  of 
special  significance  to  the  student  of  psychology.  It  is  the 
idea  which  each  person  has  of  himself.  So  significant  is 
this  idea  for  our  ordinary  thought  that  it  has  sometimes 
been  described  in  terms  which  imply  that  one  knows  one- 
self directly  as  though  through  some  kind  of  immediate  per- 
ception. One  is  supposed  to  look  within  and  there  find  an 
inner  reality  which  is  known  and  recognized  without  any  of 
the  ordinary  steps  that  enter  into  the  process  of  knowing 
reality. 

Idea  of  self  a  concept.  That  the  self  is  a  being  which 
can  be  directly  perceived  is,  however,  contradicted -by  all  the 
facts  of  development.  The  child  does  not  know  himself 
until  after  he  has  had  a  series  of  experiences.  Even  the 
adult  has  something  to  learn  about  himself  with  each  new 
turn  of  conscious  life.  The  idea  of  self  must  therefore  be 
described  as  a  concept  which  matures  in  the  course  of  ex- 
perience just  as  does  any  other  scientific  or  practical  idea. 

First  stages  of  personal  development  not  self-conscious. 
Let  us  attempt  to  formulate  what  we  know  of  the  most 
primitive  stages  of  experience,  in  order  that  we  may  arrive 
at  some  notion  of  what  consciousness  is  like  before  there  is 
any  recognition  of  the  self.  The  simplest  forms  of  animal 
behavior,  as  has  been  repeatedly  pointed  out,  do  not  indicate 
any  clear  marking  off  of  impression  from  expression.  The 


.'  H«>KM;Y 

•  v  which  follows  upon  impression  is  so  direct  that  there 
is  no  time  for  the  interpolation  of  any  factor,  either  in  the 
nervous  system  or  in  consciousness,  between  impression  and 
expression.   Much  the  same  kind  of  situation  appears  v 
we  examine  the  human  infant.    Tf.  :ed  mech- 

anism in  the  instincts  which  supplies  appropriate  responses 
to  stimuli,  and  as  a  result  there  is  little  or  no  consciousness 
of  any  kind  involved  in  reacting  to  the  impression  — 
tainly  no  recognition  of  one's  own  personality.  Sensation 
and  response  blend  in  an  experience  which  is  overwhelm- 
ingly emotional  in  character  and  not  at  all  capable  of  dis- 
tinguishing one  factor  of  the  situation  from  another.  Such 
experience  includes  no  separate  idea  of  oneself. 

Gradual  discrimination  of  self  from  things.  The  develop- 
ment from  this  point  is  toward  the  discrimination  of  phases 
of  experience.  Probably  there  is  a  gradual  differentiation  of 
the  sensory  elements  from  one  another  and  of  the  sensory 
elements  from  the  individual's  attitudes  and  responses, 
soon  as  things  begin  to  be  recognized,  there  must  be  a 
tendency  to  formulate  all  one's  feelings  and  attitudes  into 
a  kind  of  personal  unity  or  self.  The  construction  of  such 
a  personal  core  or  self  in  contrast  with  things  is  a  slow  and 
complex  process. 

Child's  early  notion  of  self  largely  objective.  Undoubt- 
edly, a  child's  contact  with  his  own  body  is  very  important 
in  building  up  some  early  crude  distinctions  between  im- 
pressions and  attitudes.  When  the  child  handles  his 
feet,  he  finds  that  the  impression  he  receives,  and  the  atti- 
tudes into  which  he  is  thrown  by  the  double  stimulation  of 
two  parts  of  his  body,  are  entirely  different  from  the  impres- 
sions which  he  receives  and  the  simpler  attitudes  into  which 
he  is  thrown  by  the  stimulation  of  one  of  his  members 
through  some  external  object.  He  thus  comes  to  distinguish 
between  his  body  and  the  external  world.  The  body  is  a 
part  of  the  world  with  characteristics  different  from  the 


THE  IDEA  OF  THE  SELF  271 

other  factors  which  he  recognizes  through  his  senses.  There 
is  probably  some  ground  in  this  fact  for  the  statement  that 
the  child's  earliest  recognition  of  himself  is  of  the  nature  of 
a  percept  and  relates  to  his  physical  organism.  The  rela- 
tively objective  character  of  the  experience  of  self  at  this 
stage  is  shown  by  the  fact  that,  in  addition  to  his  own  body, 
the  child  attaches  to  himself,  as  a  part  of  what  he  calls  him- 
self, the  possessions  which  he  comes  to  recognize  as  his 
individual  property.  The  external  world  is  broken  up  into  the 
meum  and  tuum,  and  the  general  notion  of  that  which  belongs 
to  the  individual  himself  is  gradually  distinguished  from  that 
which  belongs  to  others,  but  the  meum  is  not  primarily  a  sub- 
jective fact.  It  is  looked  at  through  consciousness,  but  that 
consciousness  is  very  little  self-consciousness  in  the  purely 
subjective  sense  in  which  we  use  that  term  in  mature  life. 

The  idea  of  self  as  related  to  discrimination  between  the 
objective  and  subjective.  Such  considerations  as  these  tend 
to  show  that  the  idea  of  self  is  a  product  of  discrimina- 
tive analysis  rather  than  a  fact  of  immediate  perceptual 
consciousness.  So  far  as  we  understand  immediate  con- 
sciousness in  its  early  stages,  there  appears  to  be  little  or 
no  ground  for  assuming  that  there  is  present  any  complete 
discrimination  of  the  self  on  the  one  hand  and  things  on 
the  other.  Even  in  mature  life  the  distinction  between  the 
self  and  nonself  is  not  always  drawn.  The  man  who  is 
hurrying  to  catch  a  street  car  has  a  vivid  experience,  but 
it  is  not  nicely  analyzed.  The  hungry  man  with  food  before 
him  is  little  more  self-conscious,  if,  indeed,  any  more  self- 
conscious,  than  the  animal  which  spends  all  of  its  time  and 
energy  in  the  eager  pursuit  of  food. 

The  self  discovered  by  contrast  with  not-self.  What 
brings  any  individual  to  a  clear  recognition  of  himself  will 
probably  depend  upon  the  accidents  of  individual  fortune. 
The  struggle  of  personal  interests  with  some  unyielding 
objective  fact  may  accomplish  it.  The  development  of  an 


272  PSYCHOLOGY 

idea  of  some  other  self,  opposed  in  interest  to  the  self,  is 
often  a  powerful  incentive  to  the  recognition  of  one's  own 
self.  Historically,  it  has  repeatedly  been  pointed  out  that 
the  national  spirit,  which  is  analogous  to  personal  self- 
consciousness,  often  grows  out  of  some  contest.  In  like 
fashion,  the  clear  idea  of  the  self  undoubtedly  rises  out  of 
some  contest  of  opposing  interests. 

Social  consciousness  and  self -consciousness.  The  conflict 
of  interests  may  take  a  purely  social  form,  as  in  the  use  of 
language.  One  sees  that  all  the  words  referring  to  spatial 
directions,  for  example,  center  about  one's  own  body.  One 
finds  that  active  or  passive  verbs  have  reference  to  some 
person.  One  finds,  in  short,  that  one's  own  expressions  are 
arranged  and  organized  around  a  different  center  than  are 
the  expressions  of  every  other  human  being.  So  imprt  ^ 
does  this  contrast  between  individual  attitudes  become  that 
ultimately,  when  we  find  ourselves  in  agreement  with  others, 
we  are  impressed  with  the  agreement,  as  in  earlier  cases  we 
were  impressed  by  the  differences,  in  mental  attitude.  The 
result  is  that  our  contact  with  the  social  world  is  a  constant 
stimulus  to  the  development  of  a  more  and  more  clearly 
defined  recognition  of  the  self.  The  child  undoubtedly 
comes  to  self-consciousness  through  his  use  of  language 
more  than  through  any  other  means. 

The  self  at  first  not  a  scientific  concept,  but  a  practical 
concept.  Some  idea  of  the  self,  based  upon  discrimination 
of  one's  own  attitudes  from  the  attitudes  of  other  persons, 
is  developed  in  a  wholly  unscientific  way  by  every  individual, 
just  as  the  discrimination  of  the  individual  body  and  of 
one's  personal  possessions  from  the  rest  of  the  physical 
world  arises  naturally  in  the  course  of  personal  life  without 
any  effort  at  systematic  definition.  Beyond  this  natural  dis- 
crimination one  may  attempt  to  cultivate  a  more  highly 
refined  formulation  of  his  personal  attitudes  and  personal 
characteristics,  and  yet  not  pass  directly  into  science. 


THE  IDEA  OF  THE  SELF  273 

Cultivated  self-consciousness.  To  illustrate  certain  cases 
in  which  self-consciousness  takes  a  form  other  than  the 
scientific,  we  may  refer  first  to  literary  criticism.  If  a 
reader  begins  the  criticism  of  any  piece  of  literature,  he 
will  constantly  be  contrasting  the  impression  which  the 
author  intended  to  produce  with  the  personal  attitude 
aroused  in  himself  through  the  statements  which  he  reads. 
There  will  thus  be  a  certain  social  contrast  between  the 
individual  and  the  author,  and  this  is  deliberately  cultivated 
for  the  purpose  of  refining  and  critically  elaborating  one's 
own  taste.  In  some  cases  this  may  take  the  form  of  an 
effort  to  conform  personal  tastes  or  attitudes  to  the  stand- 
ards which  have  evidently  been  adopted  by  great  masters. 
There  is  here  an  unquestionable  tendency  to  refine  self- 
consciousness  at  the  same  time  that  one  cultivates  attitudes 
toward  the  objective  facts. 

The  religious  motive  for  self-consciousness.  Another 
illustration  of  the  nonscientific  cultivation  of  the  concept 
of  the  self  will  appear  if  we  refer  to  the  attitude  which  is 
assumed  by  many  individuals  in  the  contemplation  of  their 
own  origin  and  destiny.  The  religious  attitude  has  un- 
doubtedly contributed  more  to  the  definition  of  self  in  the 
minds  of  unscientific  individuals  than  any  other  system  of 
thought  or  activity  in  the  world's  history.  One  here  asks 
himself  how  fully  his  own  personal  attitudes  conform  to 
what  he  understands  to  be  the  demands  of  the  laws  gov- 
erning his  destiny.  The  system  of  laws,  which  he  accepts 
as  a  system  of  higher  law,  may  be  derived  from  very  dif- 
ferent sources ;  but  in  any  case,  whether  it  be  the  religious 
faith  of  the  savage  or  the  systematized  theology  of  the 
most  highly  cultivated  devotee  of  an  elaborate  religious 
system,  there  is  always  in  religious  thought  and  aspiration  a 
comparison  between  the  demands  of  the  religious  system  and 
the  demands  of  individual  interest  and  feeling.  The  notion 
of  the  self  comes  to  have  a  compactness  and  importance 


274  PSYCHOLOGY 

under  this  system   of   religious  self-examination  which   it 
could  never  attain  by  mere  social  contrast  with  the  e\ 

I  «>f  other  individuals  or  in  the  presence  of  physical 
objects.  Questions  of  ultimate  destiny  arise,  and  these 
are  answered  in  terms  of  a  self  which  is  much  more 
highly  elaborated  than  the  bodily  or  material  self  upon 
which  man  concentrates  his  attention  in  the  early  stages 
of  individual  life  or  the  primi:  es  of  mental  de\ 

ment.  We  find,  however,  many  indications,  as  we  look 
into  savage  customs,  of  a  curious  mixture  of  the  primitive 
bodily  self  and  the  religious  self.  The  savage  always  pro- 
tects with  great  care  the  bodily  remains  of  those  whom  he 
would  serve,  and  he  mutilates  and  destroys  the  body  < 
enemy.  The  bodily  self  is  here  recognized  as  the  tangible 
aspect  of  personality. 

Scientific  idea  of  personality.  As  contrasted  with  these 
unsystematic  efforts  at  self-realization,  the  science  of 
chology  aims  to  build  up  a  thorough  idea  of  the  nature 
and  relations  of  the  self.  The  self  becomes  for  our  science 
a  being  whose  laws  of  organized  life  must  be  discovered 
and  explained. 

The  self  can  be  fully  described  and  understood  only 
through  studies  of  the  type  which  have  been  outlined  in 
the  foregoing  chapters.  The  self  is  a  being  which  per- 
ceives and  forms  concepts ;  it  remembers  and  expresses 
itself  in  regular  habits.  It  is  characterized  by  emotions 
and  by  elaborate  ideational  forms  of  thought.  The  self  is, 
however,  not  merely  a  chance  collection  of  percepts  and 
habits  and  ideas.  There  is  one  attribute  of  the  conscious 
self  which  stands  out  as  of  paramount  importance.  The 
self  is  a  unity.  It  expresses  itself  now  in  one  direction, 
now  in  another,  but  in  all  its  various  manifestations  it  is 
an  organized  unit.  Whatever  conscious  states  the  self  pos- 
sesses are  modified  by  virtue  of  the  fact  that  all  as; 
of  individual  consciousness  are  united  in  the  one  being. 


THE  IDEA  OF  THE  SELF  275 

The  only  analogy  which  can  be  used  in  expounding  this 
type  of  being  is  the  analogy  of  life.  The  living  being  is 
an  organized  unity. 

The  chief  item  in  the  concept  of  life  the  abstract  idea 
of  organization.  Such  statements  as  the  foregoing  are  con- 
fusing to  certain  students  of  science.  They  profess  to 
know  what  an  atom  or  an  object  is,  but  they  say  of  life 
that  it  is  not  a  scientific  entity  because  it  is  not  simple, 
and  they  say  of  conscious  selves  that  they  are  not  entities 
in  any  such  scientific  sense  as  are  atoms  and  physical 
forces.  Some  chemists,  for  example,  would  reduce  life  to 
mere  coexistence  of  atoms  in  a  complex  molecule  of  pro- 
toplasm. It  is,  indeed,  true  that  there  is  a  chemistry  of 
protoplasm.  The  significant  fact,  however,  is  that  once 
the  molecule  of  protoplasm  became  organized  it  began  to 
exercise  functions  which  were  absolutely  new.  It  began 
to  reproduce,  to  contract,  to  show  irritability,  and  to  take 
in  foreign  particles  and  transform  them  into  new  molecules 
of  protoplasm.  The  world  began  to  take  on  a  new  aspect 
when  protoplasm  came  into  it.  One  cannot  continually 
look  backward  to  chemical  elements  in  treating  of  pro- 
toplasm ;  he  must  look  forward  to  the  effects  produced 
by  protoplasm. 

Unity  of  self.  So  it  is  with  a  conscious  being.  Such 
a  being  is  conditioned  by  sense  organs  and  central  nervous 
processes,  but  a  description  of  these  conditions  does  not 
exhaust  the  account.  The  self  has  become  through  organi- 
zation a  unit  in  the  world,  capable  of  affecting  in  some 
measure  the  doings  of  this  world. 

The  self  as  an  efficient  cause.  A  conscious  being  is,  ac- 
cordingly, different  from  a  being  not  endowed  with  mind  just 
in  the  degree  in  which  the  conscious  being  can  produce 
effects  which  depend  on  consciousness.  To  deny  the  reality 
of  the  conscious  self  is  to  repudiate  a  scientific  concept  which 
is  as  fully  justified  as  the  concept  solar  system. 


276  PSYCHOLOGY 

Self  as  a  valid  scientific  concept.  Yet  certain  writers 
deny  the  right  of  science  to  deal  with  the  idea  of  self. 
They  say  that  the  self  is  never  seen  as  is  the  object  which 
gives  us  a  visual  impression.  They  say  that  physical  reality 
can  be  known,  but  the  knowing  self  is  something  intangible 
and  unapproachable  by  scientific  methods.  The  difficulty  in 
the  whole  situation  is  that  the  individual  who  is  trying  to 
explain  and  understand  himself  sometimes  loses  sight  of 
the  central  fact  of  his  own  mental  life,  as  he  explores  tin- 
conditions  which  surround  this  central  personality.  The 
central  personality  is  taken  so  much  for  granted  that  sci- 
entific description  tends  to  deal  with  all  that  leads  up  to 
personality,  and  there  it  stops,  finding  its  chief  subjects 
of  thought  in  these  surrounding  facts  rather  than  in  the 
central  result  of  all  the  organized  conditions.  Some  day 
the  historian  of  thought  will  write  it  down  as  one  of  tin- 
curious  fallacies  of  immature  science  that  certain  physiol- 
ogists, biologists,  and  even  psychologists,  were  satisfied  to 
call  their  own  personalities  mere  by-products,  without  es- 
sential significance  in  the  world,  just  because  they  did  not 
find  consciousness  capable  of  description  in  the  regular  scien- 
tific formulas  adopted  for  the  discussion  and  explanation  of 
external  reality. 

One  hardly  knows  how  to  find  phrases  in  which  to 
answer  those  who  hold  consciousness  to  be  less  real  and 
potent  than  physical  forces.  Certainly,  nature  has  protected 
and  conserved  consciousness  throughout  the  whole  develop- 
ment of  the  animal  kingdom.  Certainly,  the  world  is  dif- 
ferent because  consciousness  has  been  evolved.  Certainly, 
consciousness  is  no  less  real  than  are  its  conditions ;  and, 
finally,  consciousness  is  certainly  much  more  directly 
approachable  to  the  student  of  science  than  is  matter. 

Concept  of  unity.  These  are  the  statements  which  de- 
scribe the  psychologist's  concept  of  the  self.  Such  a  con- 
cept is  no  less  clear  and  well  established  than  the  concepts 


THE  IDEA  OF  THE  SELF  277 

of  all  science.  Indeed,  it  is  from  one's  own  ideas  of  him- 
self that  the  notion  of  external  unities  is  derived.  When 
one  comes  back  time  and  time  again  to  the  same  object  and 
recognizes  it  as  familiar  and  attributes  to  it  a  continuity 
which  goes  far  beyond  anything  he  can  observe  through  his 
senses,  he  is  projecting  a  concept  of  unity  derived  from  his 
own  experience  into  the  world  of  outer  realities.  When  sci- 
ence thinks  of  the  earth  as  a  unity,  or  of  the  universe  as  a 
unity,  this  is  a  concept,  not  a  percept.  The  same  kind  of 
comprehensive  generalization  appears  in  the  practical  and 
scientific  study  of  self.  It  is  probably  not  true  that  animals 
recognize  their  own  unity.  Experience  with  them  is,  as  it 
is  with  us,  a  succession  of  interrelated  events,  but  the  sur- 
vey of  the  total  succession  is  not  possible  in  the  undeveloped 
animal  consciousness.  It  is  probably  not  true  that  children 
have  any  broad  view  of  the  unity  of  their  personalities.  The 
ability  to  remember  is  one  of  the  most  significant  special 
experiences  from  which  we  derive  the  content  with  which  to 
construct  a  broader  self.  The  ultimate  recognition  of  the  most 
comprehensive  unity  is  a  conceptual  rather  than  perceptual 
fact,  even  after  memory  has  made  its  full  contribution. 

The  self  a  concept.  One  must  be  satisfied  with  a  scien- 
tific description  of  the  self.  One  can  never  see  the  self 
directly.  To  demand  that  the  details  of  the  total  unity  be 
filled  in  with  a  concrete  image  or  illustration  is  to  demand 
even  more  than  natural  science  would  demand,  if  it  required 
a  direct  perceptual  representation  of  its  ultimate  substances, 
such  as  the  atoms. 


CHAPI  I-K    XIV 
DI3S4  "  IATION 

Disorganized  personality  in  contrast  with  normal  self. 
The  discussions  of  the  last  chapter,  as  well  as  the  dot. 
description  of  mental  processes  of  various  types,  show  how 
essential  is  the  concept  of  self  unity.  This  lesson  is  power- 
fully reenforced  by  considering  certain  abnormal  states  in 
which  the  unitary  self  gives  way  to  disintegrating  forces  and 
leaves  the  self  broken  down  and  unable  to  play  its  part  in 
the  world. 

Illusions  and  hallucinations.  Kvcry  form  of  mental  pa- 
thology or  abnormality  is  in  some  sense  a  case  of  malorgani- 
zation  or  disintegration.  There  are  certain  mild  cases  of 
irregularity  which  may  be  classed  as  forms  of  maladaptation, 
rather  than  distinctly  pathological  cases.  Such  are,  for  ex 
ample,  our  geometrical  illusions.  A^  ire  saw  in  our  earlier 
discussions,  an  illusion  is  always  an  incomplete  organization 
of  the  sensations  presented  to  the  observer.  Defects  in  or- 
ganization may  be  carried  very  much  further  in  the  case  of 
a  person  who  has  what  are  known  as  hallucinations.  An 
individual  may,  for  example,  have  an  irritation  upon  some 
part  of  the  skin  which,  under  normal  conditions,  would  be 
neglected  or,  at  most,  treated  as  an  inconvenient  excitation 
of  the  part ;  but  if  the  organizations  of  mental  life  are  un- 
stable because  of  some  general  diseased  condition  of  the 
individual,  this  excitation  in  a  certain  part  of  the  skin  may 
become  the  center  for  a  most  abnormal  combination  of  ex- 
periences and  may  lead  to  the  development  of  a  distinctly 
abnormal  type  of  interpretation.  Everything  that  suggests 

278 


DISSOCIATION  279 

itself  to  the  mind  may  be  made  subservient  to  this  stimula- 
tion, until  finally  the  person  constructs  an  imaginary  world, 
giving  the  abnormal  excitation  a  value  and  importance  which, 
in  normal  life,  it  could  never  have  had.  He  may  come  to 
believe  that  he  is  made  of  glass  or  stone,  or  he  may  think 
that  someone  is  attacking  him  with  poisons  or  acids.  These 
illustrations  will  serve  to  make  clear  what  is  meant  by  the 
statement  that  abnormal  mental  experiences  are  always  ex- 
periences which  result  from  irregularities  in  organization, 
and  commonly  involve  more  or  less  disorganization  or  dis- 
sociation of  the  elements  which  should  be  combined. 

Sleep,  the  influence  of  drugs,  hypnosis,  and  insanity  as 
forms  of  disorganization.  We  may  examine  three  distinct 
cases  of  dissociation  in  order  to  make  clear  in  detail  what 
is  meant  by  mental  disorganization.  First,  there  is  in  sleep 
a  form  of  normal  suspension  of  central  nervous  activity  which 
has  been  provided  by  nature  for  the  purpose  of  recuperating 
the  individual.  This  nervous  condition  is  accompanied  by  a 
temporary  interruption  of  normal  conscious  processes.  Sec- 
ond, there  are  certain  forms  of  dissociation  and  partial  re- 
construction which  are  very  similar  in  character  to  sleep,  but 
do  not  serve  the  purposes  of  recuperation  as  does  normal 
sleep.  The  conditions  here  referred  to  may  be  induced  by 
the  use  of  drugs  or  by  certain  other  devices,  conspicuous 
among  which  are  the  methods  of  inducing  hypnosis.  Finally, 
the  dissociations  and  partial  reconstructions,  which  are  tem- 
porary in  hypnosis  and  after  the  use  of  certain  drugs,  may 
appear  in  a  great  variety  of  relatively  permanent  forms  in 
the  different  types  of  insanity.  One  or  two  of  these  typical 
forms  of  insanity  will  be  referred  to  later,  in  order  to 
exemplify  the  conditions  which  result  from  permanent 
disorganization. 

The  physiological  conditions  of  sleep.  The  physiological 
conditions  which  present  themselves  in  the  nervous  system 
during  sleep  are  not  fully  understood,  but  their  general 


i8o 


PSYCHOLOGY 


character  can  be  described  with  sufficient  clearness  for  our 
purposes.  In  the  first  place,  the  condition  of  fatigue  in  the 
nerve  cell  has  been  found  to  be  a  condition  of  somewhat 
depleted  tissue  in  the  cell  body.  There  are  also  certain 
chemical  changes  resulting  from  fatigue.  These  are  de: 

stratcd  by  the  different  degrees 
to  which  fatigued  and  normal 
cells  respectively  take  on  the 
coloring  substances  which  are 
used  in  staining  microscopic 
sections  of  the  tissue.  The 
protoplasm  of  the  fatigued 
cells,  as  seen  from  Fig.  58,  is 
in  part  exhausted  as  a  result 
of  the  processes  of  stimulation 
through  which  they  have  passed. 
Sleep  must  be  a  condition  in 
which  these  cells  are  supplied 
with  nutrition  and  return  to 
their  normal  state  of  energy 
and  activity.  During  the  period 
of  sleep,  each  cell  seems  to  be 
capable  of  insulating  itself  from 
the  neighboring  parts  of  the 
nervous  system.  There  are 
some  extreme  conditions,  prob- 
ably pathological  in  character, 
in  which  the  dendrites  of  the 
nerve  cells  curl  up  and  form, 
instead  of  extending  branches,  little  knotty  balls  across 
which  stimulations  cannot  easily  pass.  This  curling  up  of 
the  dendrites  is  probably  a  very  much  more  radical  change 
than  occurs  under  the  ordinary  conditions  of  sleep.  The 
synapses,  or  interlacing  of  fibers,  which  connect  a  cell 
with  other  cells  or  incoming  fibers,  are  interrupted  in  most 


FIG.  58.    Fatigued  cells 

Two  sections  A  and  B  from  the  first 
thoracic  spinal  ganglion  of  a  cat  B  is 
from  the  ganglion  which  has  been  elec- 
trically stimulated  through  its  nerve 
for  five  hours.  A  is  from  a  correspond- 
ing resting  ganglion.  The  nuclei  .V  of 
the  fatigued  cells  are  seen  to  take  a 
darker  stain  and  to  be  very  irregular 
in  outline.  The  general  protoplasm  of 
the  cell  bodies  is  also  less  uniform  in 
density  in  the  fatigued  cells.  (After 
Hodge) 


DISSOCIATION  281 

cases,  not  by  any  gross  movement  of  the  dendrites  but  rather 
by  some  chemical  change  in  the  tissue  which  makes  it 
difficult  for  the  stimulation  to  pass  across  from  one  cell  to 
another.  There  are  known  chemical  substances  which  affect 
primarily  the  synapses  and  prevent  stimulations  from  being 
transmitted  from  cell  to  cell.  All  of  these  indications  go  to 
show  that  the  nerve  cell,  when  it  enters  on  the  process  of 
recuperation,  tends  to  give  up  its  normal  transmitting  func- 
tion, and  devotes  itself  for  the  time  being  to  the  processes 
of  building  up  tissue. 

The  closing  of  avenues  of  stimulation  in  sleep.  The  ex- 
ternal characteristics  of  a  sleeping  individual  are  clearly 
intelligible  in  terms  of  the  physiological  changes  which  have 
been  described.  In  the  first  place,  the  individual  becomes 
less  and  less  susceptible  to  stimulations  from  the  outside 
world.  This  means  that  when  any  form  of  external  energy 
acts  on  the  nervous  system,  it  finds  the  nervous  system  rela- 
tively inert.  The  receiving  organs  are  closed  and  their  cells 
are  probably  in  a  chemical  condition  unfavorable  to  any  vig- 
orous activity.  Even  when  stimulations  are  received  at  the 
periphery  and  are  transmitted  to  the  central  nervous  system, 
they  make  headway  through  the  tissues  with  the  greatest 
difficulty.  They  do  not  follow  the  well-defined  paths  which 
are  used  in  normal  life,  but  are  diffused  throughout  the 
whole  organ. 

Various  degrees  of  dissociation.  The  condition  of  the 
individual  need  not  be  a  condition  of  complete  sleep  in 
order  to  show  this  inertness  of  the  nervous  system.  There 
are  many  conditions  of  fatigue  in  which  the  nervous  system 
shows,  before  sleep  sets  in,  more  or  less  of  a  tendency  to 
resist  external  stimulation.  Furthermore,  the  different  stages 
of  sleep  are  by  no  means  equal  in  their  degree  of  dissocia- 
tion. This  has  been  shown  by  experiments  in  which  the 
amount  of  noise  necessary  to  arouse  a  sleeping  individual 
has  been  made  the  measure  of  the  intensity  of  sleep.  The 


IS  a 


PSY<  HOLOOV 


result  of  such  experiments  is  to  show  that  a  person  goes  to 
sleep  rapidly  and  profoundly  during  the  early  part  of  the 
night,  and  from  this  time  on  gradually  comes  back  to  a  con- 
dition of  susceptibility  to  stimulation.  Fig.  59  shows  a  sleep 
curve  of  the  kind  which  results  from  these  experiments. 


i.o   1.5  20   -j.5   .10   35   4.0  4.3  Sot   LA 


;>).    Curve  showing  the  intensity  of  sound  necessary  to  awaken  a 
sleeper  at  different  periods  of  sleep 

Along  the  horizontal  line  are  represented  the  hours  of  sleep ;  along  the  vertical,  the 
relative  intensities  of  sound.  Thus,  at  the  end  of  the  first  half  hour  an  intensity  of 
sound  somewhat  over  six  hundred  is  necessary  to  awaken  the  sleeper.  At  the  end 
of  two  hours  the  intensity  of  sound  is  approximately  one  hundred.  The  curve  indi- 
cates that  the  sleeper  falls  rapidly  into  a  profound  sleep  and  then  gradually  comes 
into  a  condition  of  very  light  slumber  preceding  for  a  long  time  the  waking. 

Kohlschuttcr) 

The  curve  rises  rapidly,  indicating,  as  stated,  that  the  amount 
of  stimulation  necessary  to  arouse  the  nervous  system  in- 
creases rapidly  in  the  early  hours  of  sleep;  it  falls  off 
gradually  toward  the  end,  indicating  a  gradual  waking  of 
the  subject. 

Dissociation  in  the  central  processes.  Not  only  are  the 
cells  of  the  sleeper's  nervous  system  impervious  to  external 
stimulation,  but  they  are  uncoupled  in  such  a  way  that  the 
stimulations  which  succeed  in  entering  the  nervous  system 


DISSOCIATION  283 

do  not  follow  the  ordinary  paths  of  discharge.  This  uncoup- 
ling of  the  central  nerve  cells  does  not  take  place  in  equal 
degree  in  all  parts  of  the  nervous  system.  The  large  cells 
of  the  spinal  cord  are  able  to  resist  the  effects  of  fatigue, 
and  the  spinal  cord  may  be  said  never  to  sleep  under  normal 
conditions.  For  this  reason,  stimulations  which  reach  the 
spinal  cord  from  the  surface  of  the  body  are  always  trans- 
formed into  reflex  impulses  and  sent  to  the  muscles  of  the 
trunk  and  limbs.  The  spinal  cord  is  in  this  case  uncoupled, 
not  within  itself,  but  only  with  reference  to  the  higher  centers. 
The  reflexes  are  very  much  simpler  in  form  and  more  likely 
to  appear  under  these  conditions  than  when  the  stimulus  has 
an  open  path  to  the  higher  centers.  Thus  a  cold  or  uncom- 
fortable hand  will  always  be  moved  reflexly  in  sleep.  The 
medulla,  like  the  cord,  seems  to  be  able  to  resist,  to  a  great 
extent,  the  tendencies  toward  fatigue,  for  many  of  the  organic 
processes,  such  as  circulation  and  respiration,  are  maintained 
through  the  nerve  centers  in  the  medulla,  while  the  rest  of 
the  nervous  system  is  closed  to  external  stimulation  and  to 
any  well-ordered  activities. 

Dreams  as  dissociated  groups  of  ideas.  One  effect  of  the 
uncoupling  of  the  various  nerve  tracts  in  the  organs  of  the 
central  nervous  system  above  the  medulla  is  that  any  proc- 
esses which  take  place  in  these  higher  organs  because  of 
strong  stimulations,  or  because  of  some  abnormal  excita- 
bility in  the  nervous  system,  are  fleeting  and  irregular.  The 
higher  centers  probably  do  not  all  of  them  sink  into  the 
same  degree  of  inactivity  even  in  a  normal  individual,  and 
the  slightest  abnormality  may  result  in  a  heightened  activity 
in  certain  parts.  The  facts  of  consciousness  which  corre- 
spond to  these  irregular,  detached  activities  in  the  central 
nervous  system  during  sleep  are  easily  understood  when  it 
is  recognized  that  the  nervous  system  is  acting  not  as  a 
single  organized  system  but  as  a  disorganized  group  of 
centers.  To  put  the  matter  in  terms  of  experience,  one  may 


284 

say  that  an  idea  which  presents  itself  during  sleep  is  not 
related  to  the  genera]  body  of  ideas  by  which  the  cxpcri- 
s  of  ordinary  life  are  checked  and  held  under  criticism. 
If,  in  ordinary  life,  the  idea  suggests  itself  to  some  indi- 
vidual that  he  has  enormous  possessions,  he  is  immediately 
reminded  by  the  evidences  of  his  senses  and  by  the  familiar 
surroundings  and  limitations  of  his  sphere  of  action  that  tin- 
idea  is  merely  a  subjei  live-  imagination.  If,  on  the  other 
hand,  one  should  have  this  idea  in  his  dreams,  under 
ditions  which  would  remove  it  from  all  restricting 
it  would  obviously  be  compelling  in  its  force  and  would  be 
accepted  by  consciousness  as  an  unqualified  and  unlimited 
truth.  It  would  be  dissociated  from  the  other  ideas  which 
fill  normal  consciousness,  and  this  dissociation  would  <: 
mine  its  character  in  such  a  way  as  to  make  it  distinctly 
different  from  the  processes  of  coherent  thought  built  up  in 
normal  life. 

Dreams  impressive  only  because  they  are  uncriticized. 
It  will  be  seen  from  such  considerations  as  these  that  a 
mature  individual  is  brought  in  his  sleep  into  a  condition 
somewhat  similar  to  that  exhibited  in  the  irregular  and  un- 
restrained imaginings  of  children.  The  young  child  con- 
structs imaginations  and  is  quite  unable  to  criticize  them 
because  of  his  lack  of  experience  and  because  of  the  lack  of 
organization  within  his  experience.  The  lines  of  organiza- 
tion are  not  laid  down  in  the  child;  in  the  dreaming  adult, 
though  systems  of  ideas  have  been  built  up,  they  are  for 
the  time  being  interrupted,  and  the  processes  of  mental  life 
lapse  into  unsystematic  and  uncritical  forms.  There  is,  for 
this  reason,  a  certain  freedom  from  all  kinds  of  restraint, 
which  accounts  for  the  highly  erratic  character  of  dreams. 

Motor  processes  suspended  by  dissociations  in  sleep.  The 
third  characteristic  of  sleep  follows  naturally  from  these 
which  we  have  been  discussing.  Muscular  movements  are 
almost  completely  suspended  in  normal  sleep.  The  muscles 


DISSOCIATION  285 

relax  more  than  they  do  in  any  condition  of  waking  life,  just 
because  the  nervous  system  sends  only  very  much  reduced 
stimulations  to  the  muscles,  and,  as  we  have  repeatedly 
seen,  the  muscles  are  quite  unable  to  perform  their  work 
when  they  are  not  stimulated  by  the  nerves.  The  few 
straggling  stimulations  which  succeed  in  getting  through 
the  nervous  system  to  the  muscles  are  lower  reflexes  or  they 
are  irregular  and  without  coordination.  The  movements 
which  appear  are,  therefore,  often  more  incoherent  than  the 
fleeting  dream  experiences  which  accompany  the  activities 
in  the  central  nervous  organs.  Indeed,  in  most  cases,  any 
intense  movements  of  the  muscles  during  sleep  indicate  a 
distinctly  abnormal  condition  and  are  closely  related  in  char- 
acter to  the  irregular  coordinations  which  appear  in  certain 
forms  of  drug  poisoning. 

Narcotic  drugs  dissociative  in  their  effects.  The  discus- 
sion of  the  phenomena  which  attend  the  use  of  drugs  will 
aid  in  the  understanding  of  what  has  been  said  about  sleep. 
It  is  a  familiar  fact  that  certain  narcotics  produce  a  condi- 
tion very  closely  related  to  sleep.  The  narcotic  drug  closes 
the  avenues  of  sensory  reception,  reduces  central  activity  or 
renders  its  processes  irregular  and  incoherent,  and  suspends 
muscular  contraction.  If  the  drug  is  taken  in  a  relatively 
small  dose,  so  that  its  effect  upon  the  nervous  system  is 
slight,  these  various  effects  may  be  produced  in  slight 
degree  only.  The  effect  in  this  case  will  be  most  marked 
in  the  irregularity  of  ideas  and  in  the  incoordination  of 
the  movements. 

Effect  of  alcohol  on  the  nervous  system.  A  familiar  effect 
of  a  drug  is  the  intoxication  which  is  produced  by  alcohol. 
The  chemical  condition  of  nerve  cells  and  consequently  the 
relations  between  them  are  in  some  way  affected  by  alcohol, 
and  the  stimulations  are  interrupted  or  become  irregular 
in  their  transmission  through  the  tissues.  The  fact  that  a 
man  under  the  influence  of  alcohol  sees  things  moving 


286  PSYCHOLOGY 

irregularly,  or  sees  them  double,  depends  upon  the  incoordina- 
>f  the  muscles  of  the  eyes.    The  fact  that  he  is  unable 
to  walk  steadily  shows  the  incoodination  of  the  muscles  of 
the  legs.    There  is  a  corresponding  irregularity  in  the  fl< 

leas  ;  and  his  crcdulousness  for  the  ideas  which  suggest 
themselves  to  him  is  analogous  to  the  ordinary  credulous- 
ness  of  a  dreaming  sleeper.  The  imperviousness  of  such  an 
individual  to  the  stimulations  of  the  outside  world  is  also 
a  well  known  fact. 

Overexcitation  is  also  dissociative.  In  the  case  of  any 
one  of  the  drugs  which  produces  dissociative  conditions  in 
the  nervous  system,  the  condition  may  be  overcome  by  the 
ordinary  processes  of  recuperation  by  which  the  organism 
throws  out  the  drug.  In  some  cases  the  effort  of  the  organ- 
ism to  restore  the  normal  condition  leads  to  a  reaction  which 
is  abnormally  intense.  \Ve  may  then  have  for  a  time,  as  a 
result  «>f  reaction  to  the  drug,  a  state  of  hypersensitivity  and 
a  more  vigorous  activity  within  the  central  nervou- 
and  in  the  muscles.  The  dissociating  effects  of  such  intense 
activity  in  the  nervous  system  may  be,  so  far  as  consciousness 
and  muscular  coordination  are  concerned,  quite  as  abnormal  ( 
as  the  depressing  effects  of  fatigue  or  complete  suspension 
of  nervous  activity.  Thus,  if  the  stimulations  coming  to  the 
central  nervous  system  are  much  increased  in  their  intensity 
because  the  nervous  tissue  has  been  thrown  into  a  condition 
of  heightened  activity,  there  may  be  an  irregularity  in  the 
central  nervous  processes  due  to  the  abnormally  strong  cur- 
rents of  excitation  and  to  the  impossibility  of  restraining 
these  currents  of  stimulation  within  the  ordinary  channels 
of  connection  and  discharge.  The  disorganization  here  is 
like  the  disorganized  behavior  of  a  stream  that  overflows 
its  banks. 

Toxic  effects  of  certain  diseases.  There  are  certain  condi- 
tions produced  in  nature  which  are  quite  analogous  to  those 
which  are  produced  by  drugs.  Such  conditions  appear  in 


DISSOCIATION  287 

fevers  when  the  organism  is  under  the  influence  of  certain 
toxic  substances  produced  by  the  organism  itself  or  by 
bacteria  lodged  in  the  body ;  under  such  conditions  the 
nervous  systern  is  rendered  hypersensitive  through  the 
chemical  action  of  these  foreign  substances  on  the  tissues. 
The  delirium  of  the  fever  patient  presents  clearly  the  picture 
of  too  intense  activity  in  the  central  nervous  system,  and  the 
muscular  activity  of  such  an  individual  is  directly  related  to 
his  irregular  and  excessive  central  processes.  Such  a  person 
may  also  be  excessively  sensitive  to  slight  sounds  or  other 
irritations  of  the  organs  of  sense. 

These  negative  cases  as  evidences  of  the  relation  between 
normal  consciousness  and  organization.  These  different 
cases  show  the  relation  between  nervous  organization  and 
mental  organization,  and  by  their  negative  characteristics  con- 
firm the  discussions  of  the  preceding  chapters,  in  which  it 
has  been  maintained  that  normal  mental  life  is  a  continuous 
process  of  integration  and  organization. 

Hypnosis  a  form  of  dissociation  closely  allied  to  sleep. 
The  condition  known  as  hypnosis  has  long  been  the  source 
of  superstitious  wonder,  and  much  has  been  said  and  written 
in  regard  to  it  which  would  tend  to  increase  the  mystery 
which  attaches  to  it.  In  many  respects  it  is  a  condition 
closely  related  to  normal  sleep.  On  the  other  hand,  it  has 
certain  peculiar  characteristics  which  differentiate  it  from 
ordinary  sleep.  These  peculiarities  can,  however,  be  fully 
understood  under  the  formula  adopted  in  explanation  of 
normal  sleep,  provided  that  formula  is  slightly  modified  to 
include  certain  specialized  forms  of  dissociation. 

Hypnosis  as  partial  dissociation.  While  normal  sleep  in- 
volves the  uncoupling  or  dissociation  of  the  nervous  ele- 
ments, especially  of  the  type  which  suspends  activity  in 
the  higher  centers,  hypnosis  involves  a  dissociation  which 
is  partial  and  leaves  a  part  of  the  higher  centers  in  action. 
To  put  the  matter  in  simple  terms,  we  may  say  that  in 


288 

normal  sleep  the  cerebrum   is  dissociated  from  the  lower 
centers,  and  all  the  centers  in  the  cerebrum  arc  dissociated 
from  each  other ;   whereas,  in  hypnosis  only  a  part  of  the 
cerebrum    is    dissociated    from    the    lower    centers.    The 
remaining  part  of  the  cerebrum  continues  'to  carry  on   its 
activities  and,   indeed,  profits   by  the   cessation  of  an 
in  the  dormant  portion,  for  the  active  part  of  the  nervous 
in  is,  in  such  a  case  as  this,  supplied  with  an  unusually 
amount  of  blood,  and  its  activity  may  reach  a  much 
higher  level  of  intensity,  because  of  this  superior  nut: 
supply  and  because  of  the  concentration  of  all  of  the  : 
ous  activity  in  one  region.    Such  a  crude  statement  as  this 
is  undoubtedly  too  simple  in  its  terms,  and  yet  it  represents 
the  situation  in  principle. 

Methods  of  inducing  hypnosis.  The  way  in  which  the  con- 
dition of  partial  or  hypnotic  dissociation  is  produced  in  the 
nervous  system  differs  with  the  practice  of  different  hypno- 
tizers.  One  of  the  characteristic  methods  of  producing 
hypnosis  is  to  require  the  subject  to  gaze  at  some  bright 
object  until  a  kind  of  partial  stupor  comes  over  him.  He 
may  then  be  aroused  to  activity  through  the  sense  of  hear- 
ing. The  ideas  which  he  receives  and  the  activities  which 
he  performs  have,  under  these  conditions,  many  of  the 
characteristics  of  dissociation.  Another  way  of  producing 
hypnosis  is  to  soothe  the  subject  into  a  sleeplike  condition. 
Stroking  the  forehead  or  the  face  is  very  commonly  prac- 
ticed by  hypnotizers.  Here  again,  the  appeal  to  the  subject, 
after  the  dormant  condition  has  set  in,  is  through  the  sense 
of  hearing  or  even  through  the  sense  of  vision. 

Hypnosis  more  readily  induced  after  it  has  once  been  estab- 
lished in  a  subject.  When  a  subject  has  been  frequently 
hypnotized,  it  is  possible  to  reproduce  the  hypnotic  condi- 
tion without  elaborate  preliminaries.  The  subject  acquires 
what  may  be  called  a  habit  of  dissociation.  A  simple  order 
from  the  hypnotizer  is  enough  to  throw  the  subject  into  the 


DISSOCIATION  289 

condition.  Sometimes  the  habit  is  carried  to  such  an  ex- 
tent that  the  subject  is  able  to  throw  himself  into  the  hyp- 
notic condition.  Such  self-induced  hypnosis  is  known  as 
auto-hypnosis.  The  ability  to  produce  the  hypnotic  state 
in  the  subject  does  not  depend  upon  any  peculiar  powers 
on  the  part  of  the  hypnotizer ;  it  depends  rather  upon  his 
ability  so  to  influence  his  subject  that  the  condition  of  par- 
tial sleep  described  shall  be  induced.  The  essential  condi- 
tion with  which  the  subject  himself  must  comply,  in  order 
to  come  under  the  influence  of  a  hypnotizer,  is  that  he  con- 
centrate his  attention.  The  only  persons  who  cannot  be 
hypnotized  are  young  children,  idiots,  and  insane  persons, 
all  of  whom  are  unable  to  concentrate  attention.  This  state- 
ment effectually  disposes  of  the  popular  belief  that  only 
weak-minded  persons  can  be  hypnotized.  The  most  effec- 
tive method  of  avoiding  hypnosis  is  to  scatter  attention  as 
much  as  possible  over  a  great  variety  of  objects.  Concen- 
tration of  attention  is  always  favorable  to  hypnosis  and 
allied  conditions.  The  audience  which  gives  close  attention 
to  a  speaker  or  performer  is  susceptible  to  a  species  of 
hypnosis  ;  while,  on  the  other  hand,  there  is  no  danger  of 
hypnosis  in  a  distracted  audience.  The  methods  of  induc- 
ing hypnosis  have  been  accidentally  discovered  from  time 
to  time  by  performers  who  are  then  able  to  give  striking 
exhibitions  of  their  discovery.  Many  oriental  jugglers  be- 
gin their  performance,  the  success  of  which  undoubtedly 
depends  upon  their  hypnotic  influence  over  their  audiences, 
with  a  dance  in  which  the  body  of  the  performer  is  moved 
with  a  gradually  increasing  speed,  which  inevitably  induces 
a  gradually  increased  concentration  of  attention  on  the  part 
of  the  observer.  When  this  dance  grows  mpre  and  more 
rapid  and  more  and  more  engaging  to  the  attention,  the 
observer  is  completely  mastered  and  the  main  performance 
may  be  undertaken.  The  hypnotic  influence  of  such  a  dance 
is  very  frequently  augmented  by  the  burning  of  incense, 


290 

which  has  more  or  less  of  a  narcotic  effect  upon  the  ob- 
servers.    In    like    m.mr.  n    animals    are    probably 

talc  by  the  movement  of  snakes. 
This  has  frequently  been  reported  in  the  case  of  birds  and 

monk 

Various  characteristics  of  the  hypnotized  subject.    When 
tin-  hypnotic  state  has  been  produced,  the  ph 
hibited  arc  of  two  distinct  types.     I-'irst,  there  is  a  sus 
sion  of  certain  activities,  and.  second,  there  is  an  abnormal 
heightening   of    other   activities.     This    may   be    seen    with 
reference  to  tin-  -  >ry  stimulations.     (  ertain 

stimulations  are  no  longe:  1  by  the  hypnotized  sul>- 

ject.  1  or  this  reason  the  condition  has  sometimes  been 
used  by  savage  tribes  for  surgical  purposes,  exactly  as  in 
modern  life  \ve  use  drugs  which  will  produce  a  dissoci. 
of  the  nervous  system  and  thus  prevent  pain  from  exces- 
sive external  stimulation.  On  the  other  hand,  certain  other 
senses  may  be  opened  to  stimulation.  A  hypnotized  subject 
may  be  wholly  ana*sthetic  in  his  skin,  while  still  retaining 
the  ability  to  receive  impressions  through  certain  of  his 
other  senses.  Indeed,  the  concentration  of  nervous  activity 
in  certain  particular  senses  results  in  such  a  heightening 
of  their  ability  to  receive  impressions  that  the  subject  may 
perform  most  astonishing  feats  of  sensor)'  receptivity.  He 
may  hear  very  faint  sounds  or  he  may  see  remote  visual 
objects.  It  is  to  be  noted  that  this  hyperaesthesia  of  the 
senses  is  not  so  extraordinary  as  it  would  at  first  sight  seem 
to  be.  \Ye  all  become  hyperaesthetic  when  we  concentrate 
attention  in  any  direction.  If  one  is  listening  for  an  im- 
portant signal  or  watching  for  some  object  which  is  of 
great  importapce  to  him,  he  will  be  using  his  nervous 
energy  in  the  emphasized  direction  and  will  be  correspond- 
ingly impervious  to  impressions  from  other  sources.  The 
conditions  in  hypnosis  are  merely  exaggerations  of  those 
which  appear  in  ordinary  life. 


DISSOCIATION  291 

Ideas  not  subjected  to  criticism  in  hypnosis.  Turning 
from  the  sensory  processes  to  the  central  processes,  we 
find  again  that  certain  activities  are  entirely  in  abeyance, 
while  others  are  much  intensified.  If,  for  example,  it  is 
suggested  to  a  hypnotized  subject  that  he  is  an  animal 
instead  of  a  human  being,  the  suggested  idea  may  take  such 
large  possession  of  him  as  to  command  his  whole  attention 
and  guide  his  activity.  If  a  normal  individual  is  told  that 
he  is  an  animal,  he  immediately  brings  to  bear  upon  the 
suggested  idea  a  great*  variety  of  incompatible  experiences, 
which  make  it  clear  that  the  statement  is  false  and  unaccept- 
able. In  the  case  of  the  hypnotized  subject,  very  much  as 
in  the  case  of  the  dreamer,  the  corrective  ideas,  which  con- 
stitute the  fabric  of  normal  life,  are  .  absent,  so  that  the 
single  idea  takes  full  possession  of  the  mind  and  commands 
belief  as  the  accepted  content  of  consciousness.  This  credu- 
lousness  of  the  hypnotic  consciousness  is  described  by  say- 
ing that  the  subject  is  very  open  to  suggestion.  Anything 
that  is  said  to  him  will  be  accepted,  and  any  form  of  inter- 
pretation of  experience  which  is  offered  to  him  will  be 
taken  up  without  serious  question  and  without  any  effort 
on  his  part  to  criticize  the  ideas  which  have  been  given  him 
by  the  hypnotizer.  Suggestibility  has  very  frequently  been 
emphasized  to  the  exclusion  of  the  converse  fact  that  the 
hypnotized  subject  is  quite  incapable  of  subjecting  any  ideas 
to  critical  comparison.  So  also  the  positive  increase  in 
sensitivity  has  been  the  impressive  fact ;  the  diminution  of 
sensibility  has  often  been  overlooked.  The  negative  con- 
siderations are,  however,  essential  to  a  complete  under- 
standing of  the  case,  just  as  the  negative  considerations 
are  of  importance  if  we  would  understand  the  credulousness 
exhibited  in  dreams. 

Dual  personalities  in  hypnosis.  The  central  nervous  con- 
ditions which  are  induced  in  hypnosis  are  sometimes  suffi- 
ciently unstable  to  produce  the  most  complex  phenomena. 


292  PSYCHOLOGY 

sometimes  found  that  the  dissociated  parts  of  the  cere- 
brum are  not  only  dissociated  from  e.u  h  other,  but  they 
are  also,  to  a  cert  nt,  capable  of  independent  at1 

Thus,  while  one  part  of  the  cerebrum  seems  to  be  dealing 
with    impressions  1   through   the  sense  of  hearing. 

another  part  may  be  engaged  in  responding  to  tactual  im- 
pressions. Or,  the  case  may  be  rendered  even  more  com- 
plicated by  the  fact  that  the  impressions  coming  from  pnc 
ear  seem  to  serve  as  stimulations  for  certain  activities,  while 
auditory  impressions  received  on  the  opposite  side  of  the 
body  are  effective  in  producing  an  entirely  different  set  of 
experiences  and  responses.  There  result  in  such  cases 
what  are  known  as  dual  and  multiple  personalities.  By 
personality,  as  the  term  is  used  in  such  cases,  is  meant 
any  organized  group  or  system  of  ideas  and  a 
The  various  groups  of  systematized  activities  and  ideas 
which  exist  side  by  side  in  a  hypnotized  subject  owe 
their  separation  to  nervous  and  mental  dissociation  ;  each 
personality  is,  therefore,  a  relatively  less  complex  system 
than  that  which  exists  when  the  whole  cerebrum  is  acting 
as  a  single  organ.  The  division  of  an  individual  into  a 
number  of  systems  of  organization  appears  in  other  states 
than  the  hypnotic  state,  and  it  may  result  in  certain  per- 
manent or  certain  temporary  disruptions  of  personality, 
which  have  been  noted  in  such  stories  as  that  of  Dr.  Jekyll 
and  Mr.  Hyde. 

Dual  personalities  in  other  than  hypnotic  conditions. 
From  time  to  time  one  reads  of  a  case  of  lapse  in  memory 
which  amounts  to  a  dissociation  of  personality.  A  man  for 
gets  who  he  is  or  what  business  he  has  been  following.  I  It- 
is  sufficiently  normal  in  his  general  organization  to  respond 
to  a  great  variety  of  impressions  in  a  regular  fashion,  but 
the  complex  structure  of  mental  life  breaks  down  and 
the  man  is  only  partly  reconstructed  in  the  second  self. 
Tertiary  and  quaternary  personalities  may  appear  in  all 


DISSOCIATION  293 

possible  combinations.  The  secondary  or  tertiary  personality 
may  know  its  fellows,  but  may  be  itself  quite  forgotten. 
Several  cases  have  been  described  in  which  personality  B 
knows  not  only  its  own  acts  and  emotions  but  also  the  acts 
and  emotions  of  the  other  personality  A.  Sometimes  B  not 
only  knows  but  heartily  dislikes  A.  Sometimes  two  per- 
sonalities exist  simultaneously  within  the  same  body  and 
seem  to  have  separate  lives  and  characters.  The  writer 
knew  of  a  case  of  a  young  man  who  was  the  object  of 
superstitious  wonder  in  the  village  in  which  he  lived,  be- 
cause he  had  two  personalities.  These  two  personalities 
knew  each  other  and  held  long  discussions  with  each  other. 
Often,  when  they  came  to  a  turn  in  the  road,  they  dis- 
agreed with  each  other  as  to  the  direction  in  which  their 
body  should  move,  and  the  passer-by  could  see  the  abnormal 
man  mumbling  an  argument  between  his  two  selves. 

Dual  and  multiple  personalities  analogous  to  the  various 
selves  of  normal  life.  The  details  of  such  cases  are  baffling 
in  the  extreme,  but  nothing  can  be  clearer  from  our  earlier 
studies  than  the  general  formula  of  dissociation,  with  the 
added  fact  of  partial  organization  around  different  centers. 
The  matter  becomes  more  intelligible  if  we  remember  that 
even  in  ordinary  life  there  is  a  subdivision  of  experience 
into  different  systems.  We  distinguish,  even  in  common 
parlance,  between  the  business  self,  the  social  self,  and  so 
on.  Each  one  of  these  selves  is  only  partially  related  to  the 
other  systems  of  experience  and  forms  of  behavior.  The 
man  who  is  buried  in  the  details  of  a  business  transaction 
is  just  as  oblivious  to  considerations  of  a  literary  sort  as  the 
hypnotized  subject  is  oblivious  to  a  certain  group  of  possible 
experiences.  We  do  not  call  the  ordinary  absorption  of  the 
self  in  business  a  case  of  multiple  personality,  because 
the  neglected  personality  in  the  case  of  the  business  man 
is  not  so  remote  but  that  it  can  be  immediately  called  out, 
if  he  turns  his  attention  to  some  literary  considerations. 


294  fCHOU 

The  normal  individual  is  capable  of  transferring  his  K 
tion  and   interest   from  center  t<>  center  according  as   the 
external  environment  demands,  while  the  hypnotized  subject 
or  abnormal  person  is,  through  dissociation,  quite  incapable 

:ajml  transfer  <>f  attention  or  of  correlating  the  diff- 
phases  of  his 

Hypnosis  a  transient  condition,  insanity  permanent.    \\  <• 
shall  return  to  the  discussion  of  multiple  personality  under 
the  general  head  of  insanity,  for  the  fundamental  distil 
between  insanity  and  hypnosis  is  to  be  found  in  the  degree 
of  permanency  which  is  attained   in   the   former 
contrasted  with  the  more  transient  character  of  the  hypnotic 
condition. 

Movements  sometimes  normal  in  hypnosis,  because  the 
lower  centers  are  not  dissociated.  In  the  meantime,  it  is 
necessary  to  add  a  few  comments  on  the  motor  activities  of 
hypnotized  subjects.  These  motor  activities  frequent  1 
hibit  little  or  no  departure  from  the  ordinary  coordinations 
of  normal  life.  The  hypnotized  subject  is  capable  of  walk- 
ing, often  of  writing  or  producing  certain  other  complex 
forms  of  movement.  Such  continuation  of  the  bodily  coordi- 
nations is  explicable  on  the  ground  that  the  lower  centers  of 
the  nervous  system  are  not  dissociated  by  the  changes  that 
take  place  in  the  higher  centers.  Whenever  the  higher 
centers  are  able  to  send  stimulations  to  the  lower  centers, 
these  lower  centers  are  capable  of  responding  with  their 
usual  degree  of  coordination.  The  lack  of  organization  is 
exhibited  rather  in  the  inability  to  maintain  a  normal  bal- 
ance between  the  various  centers  which  call  the  lower  centers 
into  play.  It  is  to  be  noted,  however,  that  the  movements 
of  hypnotized  subjects  sometimes  indicate  by  their  clumsi- 
ness and  lack  of  precision  that  the  disintegrating  force  has 
affected  certain  of  the  motor  channels  as  well  as  the  central 
organizations.  This  is  especially  true  when  the  attempted 
act  involves  a  complicated  coordination. 


DISSOCIATION  295 

The  after-effects  of  hypnosis  tend  to  become  permanent. 

There  is  one  group  of  facts  in  hypnosis  which  should 
perhaps  be  made  the  subject  of  special  comments.  The 
suggestions  received  by  the  hypnotized  subject  may,  in 
some  cases,  be  carried  over  so  as  to  become  operative  in  a 
later  period,  after  the  subject  has  apparently  recovered  from 
the  hypnotic  trance.  Such  after-effects  are  known  as  post- 
hypnotic  effects,  and  the  suggestions  are  described  as 
post-hypnotic  suggestions.  Even  more  significant  is  the  fact 
that  after-effects  of  the  hypnotic  trance  are  of  a  general 
kind.  It  is  a  fact  that  the^  effect  of  the  hypnotic  state  is  in 
the  direction  of  a  perpetuation  of  dissociative  tendencies. 
Sleep  is  transient  and  leads  to  a  more  vigorous  form  of 
activity  after  it  is  over.  Hypnosis,  on  the  other  hand,  tends 
not  to  restore  the  nervous  system  to  a  more  vigorous  condi- 
tion but  to  perpetuate  dissociation.  This  is  due  to  the  fact 
that  sleep  is  negative,  while  hypnosis  is  positive  in  certain 
of  its  phases,  in  that  it  trains  certain  centers  to  act  without 
reference  to  others.  It  therefore  operates  by  virtue  of  its 
positive  phases  toward  permanent  disorganization.  It  is  for 
such  reasons  as  these  that  the  use  of  hypnosis  is  in  general 
to  be  avoided.  The  disorganizing  effects  of  hypnosis  are  of 
the  same  general  type  as  the  disrupting  tendencies  of  certain 
drugs.  The  individual,  who  with  sufficient  frequency  comes 
under  the  influence  of  these  drugs  or  of  hypnosis,  will 
ultimately  settle  into  a  state  of  nervous  disorganization  from 
which  it  will  be  quite  impossible  for  him  to  recover,  even 
when  recovery  is  demanded  for  the  purposes  of  normal 
life.  Hypnosis  is  not  utilized  by  reputable  practitioners, 
because  its  ultimate  effects  are  not  as  readily  controllable 
as  are  the  effects  even  of  the  narcotic  drugs ;  and  there  is 
no  justification  whatever  for  the  use  of  hypnosis  as  a  means 
of  amusement,  any  more  than  there  would  be  for  using  a 
strong  narcotic  drug  to  bring  an  individual  into  a  condition 
which  would  make  him  a  source  of  entertainment. 


igfl 

Insanity   a   permanent    form  of   disorganization,   intro- 
duced in  many  cases  by  dissociation  and  settling  into  an 
abnormal  reorganization.     As    has   been   indicated    it 
earlier  paragraphs,  insanity  i^  a  form  of  relatively  perm.; 
dissociation.    Certain  forms  of  delirium,  which  have  been 
referred  to  before,  furnish  the  best  introduction  to  the  study 
of  insanity.     In  delirium  the  subject  is  so  highly  excitable 
that  the  normal  avenues  of  stimulation  and  discharge  are 
for  the  time  being  completely  disrupted,  and  the  currents 
of  nervous  activity  and  the  corresponding  facts  of  experience 
are  dissociated.    As  delirium  disappears  and  gives  ph< 
the  usual   in:  •  activity  the  individual  may 

return  to  the  earlier  normal  condition  or,  on  the  other 
hand,  there  may  be  left  behind  a  permanent  abnormal  state, 
because  the  earlier  forms  of  organization  arc  not  fully 
restored.  One  of  the  most  characteristic  symptoms  of  all 
forms  of  insanity  is  found  to  be  the  existence  of  certain 
hallucinations  or  fundamental  abnormalities  in  the  subject's 
world  of  ideas.  The  insane  person  believes  himself  to  be 
Julius  Caesar  or  some  Biblical  character,  or  even  some 
divinity.  There  is  no  difficulty  in  recognizing  the  fact  that 
the  idea  of  transferred  identity  may  come  into  the  mind  of 
any  normal  individual.  It  is,  however,  in  the  case  of  a 
normal  individual  immediately  criticized  and  abandoned, 
because  of  its  incompatibility  with  the  person's  general 
knowledge  of  the  world  and  his  place  in  it.  When  the 
compact  organization  which  has  been  built  up  in  normal 
experiences  has  once  given  way,  and  the  idea  that  one  is 
Julius  Caesar  or  some  other  character  has  presented  itself 
as  a  center  of  reconstruction  in  the  midst  of  the  resulting 
chaos,  there  is  a  possibility  of  an  abnormal  reorganization 
of  experience.  The  individual  is  no  longer  restrained  by 
that  system  of  ideas  which  has  been  laboriously  built  up 
through  contact  with  the  world  ;  the  result  is  that  the  whole 
later  ideational  life  of  the  individual  loses  its  adaptation  to 


DISSOCIATION  297 

the  real  world.  The  characteristic  fact  in  certain  cases 
of  insanity  is,  accordingly,  not  desCribable  in  simple  terms 
of  dissociation  ;  it  is  rather  to  be  defined  in  terms  of  disso- 
ciation with  an  abnormal  association  or  integration  following 
upon  the  breaking  down  of  the  normal  system.  In  other 
cases,  disintegration  is  the  more  obvious  fact.  The  individual 
simply  loses  control  of  his  ideas,  and  his  mind  seems  to  be 
flooded  with  an  incoherent  mass  of  experience.  His  words 
reflect  this  incoherency  of  ideas,  and  his  behavior  indicates 
an  absence  of  self-control.  Such  disintegrated  forms  of 
consciousness  and  behavior  commonly  appear  in  the  last 
stages  of  almost  every  kind  of  insanity,  even  where  there 
has  been  for  a  time  reorganization  about  an  abnormal  center. 
Melancholia  as  a  typical  form  of  dissociation.  One  of 
the  very  general  forms  of  dissociative  abnormality  is  that 
which  appears  in  so-called  melancholia.  In  melancholia 
there  is  a  general  reduction  of  all  the  bodily  activities, 
including  the  activities  in  the  nervous  system.  The  subject 
becomes  phlegmatic  and  depressed  in  all  his  functions. 
The  whole  feeling  tone  of  experience  takes  on  a  marked 
disagreeable  character,  which  can  be  explained  in  terms  of 
our  earlier  discussion  of  feeling  by  saying  that  the  individual 
does  not  arouse  himself  easily  to  respond  to  any  form  of 
stimulation,  and  when  his  nervous  system  is  in  any  way 
aroused  by  powerful  external  excitation,  the  reaction  upon 
the  stimulus  is  so  laborious  and  contrary  to  his  tendencies 
and  mood  that  he  has  a  strong  feeling  tone  of  a  disagree- 
able type.  The  ideas  which  such  a  subject  has  are  often 
organized  about  each  other  in  a  way  that  furnishes  a  kind 
of  false  explanation  of  the  subject's  mood.  The  melancholic 
subject  has  certain  grievances  against  the  world.  Sometimes 
these  grievances  are  of  a  trivial  character  and  make  it  clear 
that  the  grievance  could  not  have  been  the  exciting  cause  of 
the  subject's  condition.  Sometimes  the  grievance  is  more 
real  and  furnishes  an  apparent  ground  for  the  condition. 


298  PSYCHOLOGY 

i  in  such  a  case  it  is  to  be  said  that  the  person's 
u-al  condition  must  luu-  developed  into  one  of  general 
debility  before  the  apparent  cause  <>f  his  mental  cond; 
could  have  become  tin-  source  of  abnormal  melancl. 
The  distinction  U-tween  a  passing  case  of  depression  in 
normal  life  and  melancholia  is  that  passing  depression  is 
temporary,  and  nature  rebounds  from  it  in  such  a  way  as 
t«.  produce  normal  conditions  after  the  depressing  circunv. 
stances  are  past.  In  the  case  of  melancholia  the  depressing 
tendencies  become  permanent,  and  it  is  this  perman 
rather  than  the  fact  of  depression  or  its  corresponding 
nervous  conditions  which  constitutes  the  characteristic  fact 
in  insanity.  Indeed,  one  can  find  almost  every  possible 
grade  of  transition  from  normal  life  to  extreme  abnormality. 
The  result  is  that  those  who  have  made  a  special  study  of 
these  transitions,  and  those  whose  attention  is  for  the  first 
time  called  to  the  possibility  of  such  transition,  are  likely 
to  indulge  in  the  extravagant  statement  that  all  persons  are 
at  times  or  on  certain  subjects  more  or  less  insane.  It  is 
undoubtedly  true  that  all  persons  do  depart  at  times  from 
the  type  of  mental  and  bodily  organization  which  constitutes 
normal  life,  but  unless  these  states  become  fixed  and  lead 
to  distorted  and  unadapted  forms  of  behavior,  they  should 
not  be  classified  as  cases  of  insanity. 

Excessive  excitation  as  a  second  typical  case  of  insanity. 
The  opposite  tendency  to  the  melancholic  condition  just 
described  appears  in  certain  cases  of  excessive  excitation. 
A  person  when  abnormally  excited  is  very  frequently  pos- 
sessed of  excessive  bodily  strength.  This  is  not  due  to  any 
change  in  the  structure  of  his  muscles,  but  rather  to  the 
fact  that  the  nervous  system  which  is  in  control  of  the  mus- 
cles is  sending  to  the  active  organs  stimulations  of  exce 
intensity.  There  are  numerous  cases  in  normal  life  which 
will  help  us  to  understand  this  fact.  If  an  individual  is 
fatigued,  encouragement  and  stimulation  from  the  outside 


DISSOCIATION  299 

world  will  appreciably  increase  his  ability  to  execute  muscular 
movements.  In  the  same  way  an  individual  may  be  so 
stimulated  by  abnormal  substances  in  the  blood  that  his 
whole  nervous  behavior  is  raised  to  a  high  level  of  activity 
and  the  motor  discharges  are  abnormally  intense.  The 
muscular  activity  of  such  a  person  is  typical  of  his  whole 
condition.  His  ideas  come  in  an  overwhelming  flood  and 
lead  him  into  the  most  extravagant  excesses  of  imagination 
and  lack  of  self-control. 

Fundamental  disturbances  of  instinctive  and  emotional 
life.  Qf  late  much  attention  has  been  given  to  the  fact  that 
in  all  cases  of  dissociation  the  fundamental  instincts  assert 
themselves  and  play  a  leading  part  in  the  behavior  and 
ideation  of  the  abnormal  individual.  For  example,  there 
are  types  of  fear  which  haunt  a  patient  and  distract  him 
from  all  normal  modes  of  thought  and  life.  Or  the  sex 
instinct  becomes  dominant,  or  the  food  instinct  leads  to 
irregular  or  irrational  behavior.  The  mode  of  treatment 
which  is  adopted  in  such  cases  aims  in  part  to  restore 
normal  nutritive  conditions  and  then  proceeds  on  the  as- 
sumption that  the  individual  must  be  started  on  the  road  to 
a  reconstruction  of  his  mental  world.  Often  the  shortest 
route  to  this  latter  goal  is  to  bring  out  in  explicit  detail  some 
of  the  deep-seated  dissociations.  Thus,  the  person  who  is 
suffering  from  terror  is  made  aware  of  the  sources  of  his 
terror  and  is  encouraged  to  reorganize  his  thinking  and  his 
attitudes  toward  the  object  of  his  dissociation.  The  abnormal 
state  can  be  compared  to  physical  clumsiness.  The  indi- 
vidual whose  muscles  will  not  coordinate  must  develop 
physical  cooperation  of  the  organs  of  his  body  by  using 
them  in  a  well-ordered,  systematic  fashion.  So  with  the 
person  suffering  from  mental  incoordination,  there  must  be 
a  well-directed  effort  at  mental  recoordination. 

Relation  of  psychiatry  to  psychology.  These  illustrations 
must  suffice  for  our  present  purposes.  There  are  all  possible 


300  ,<  HOI  i 

combin.it i<>ns  of  disintegration  and  reorganization  exhibited 
in  insanity.    There  is  a  s>  nown  as  psychiatry  which 

deals  with  these  forms  of  dissociation  and  abnormal  associ- 
ation, and  tht  e  field  of  practical  observation  and 
study  open  he-re  to  the  trained  scientist.  The  chief  lesson 
for  our  general  science  is  that  the  normal  processes  are 
processes  of  integration  leading  to  forms  of  ass« 
contribute  to  adaptation.  There  are  frequently  illustrations 
which  throw  light  upon  important  principles  of  normal  asso- 
ciation, to  be  found  by  making  a  careful  study  of  the  facts 
of  dissociation,  but  in  general  the  explanation  of  abnormal 
s  is  made  easier  by  a  careful  examination  of  normal 
processes  rather  than  the  reverse.  It  does  not  follow  that 
dissociation  will  be  along  the  same  lines  as  association,  and 
the  effort  to  work  out  the  details  of  one  by  the  other  - 
leads  to  fallacies.  The  general  tendency  of  normal  life  is, 
however,  obviously  in  the  direction  of  adaptive  organiza; 
the  tendency  of  sleep,  hypnosis,  and  insanity,  on  the  other 
hand,  is  in  the  opposite  direction.  The  particular  path  fol- 
lowed in  each  case  can  be  defined  only  through  empirical 
examination  ot  the  case. 


CHAPTER  XV 
VOLUNTARY  ACTION  AND  VOLUNTARY  ATTENTION 

Voluntary  action  a  special  form  of  behavior.  Though  the 
preceding  chapters  have  discussed  at  length  many  of  the 
relations  between  bodily  activity  and  mental  processes,  they 
have  not  dealt  specifically  with  that  form  of  behavior  which 
is  described  by  the  term  "voluntary  choice."  One  may 
reach  out  and  pick  up  the  book  before  him,  or  one  may 
decide  not  to  touch  the  book.  One  may  take  the  pen  and 
sign  a  contract,  or  one  may  refuse  to  sign.  The  whole  per- 
sonality enters  into  such  a  decision,  and  we  recognize  both 
in  ordinary  thought  and  in  scientific  consideration  of  the 
matter  that  the  ability  to  choose,  especially  the  ability  to 
choose  wisely  and  consistently,  is  the  supreme  power  culti- 
vated in  the  development  of  the  individual.  Our  penal  code 
recognizes  the  fact  that  an  immature  child  is  not  responsible 
for  his  actions  in  the  measure  in  which  a  full-grown  man  is 
responsible.  Those  who  are  mentally  defective  are  exempt 
from  the  penalties  of  the  law  just  in  the  degree  in  which 
they  fall  short  of  normal  development.  These  and  other 
illustrations  of  common  practice  show  that  voluntary  choice 
is  the  fullest  expression  of  the  developed  normal  self. 

Instinctive  behavior  different  from  voluntary  action.  The 
explanation  of  voluntary  action  depends  on  a  series  of  dis- 
tinctions which  have  been  implied  in  earlier  chapters.  Thus 
instinctive  acts  are  not  forms  of  voluntary  behavior.  For 
example,  the  infant  swallows  not  from  deliberate  choice  but 
because  nature  has  provided  a  nervous  and  muscular  mecha- 
nism which  responds  promptly  to  the  proper  sensory  stimulus. 

301 


iOLOGY 

One  has  only  to  think  of  the  cases  in  adult  experience  where 

the  swallowing  reflex  nits  when  the  swallower  would  gladly 
•re,  most  people  do  not  know  that  they 
cannot  carry  out  the  act  of  swallowing  without  a  proper  sen- 
sory stimulus.    Let  one  try  the  experiment  of  swallo. 
li\e  times  in  succession.     All  the  saliva  in  the  mouth 
have  IK-I-II  swallowed  the  second  or  third  time  the  eflf< 
made,  and  after  that  the  mechanism  refuses  to  work  until 
more  sensory  stimulation   is  supplied.     Ii: 
then-tori-  different  from  volitions.    Sometimes  we  can  volun- 
tarily check  one  of  these  acts,  although  here  our  powers  are 
limited,  and  we  can  in  some  measure  decide  when  an  act 
provided    by    the    inherited    nervous    mechanism   shall    be 
allowed  to  take  place,  but  here  again  our  control  is  lii: 
as  shown  in  the  example  given  above. 

Impulsive  acts  distinct  from  higher  forms  of  voluntary 
action.  If  we  follow  the  development  of  an  individual  from 
infancy,  we  find  that  there  are  other  forms  of  behavior  which 
resemble  the  instincts  in  that  they  are  not  fully  under  con- 
trol. For  this  general  class  of  acts  we  commonly  use  the 
term  "  impul-  ."  It  is  almost  impossible  not  to  imi- 

tate a  yawn  ;  it  is  very  difficult  not  to  look  around  when  one 
hears  an  unfamiliar  noise.  The  impulse  to  take  food  when 
one  is  hungry  is  very  strong;  the  impulse  to  strike  back 
when  one  is  struck  is  so  strong  that  the  interpretation  of  re- 
sponsibility is  always  based  on  an  examination  of  provocation. 

Impulsive  acts  as  phases  of  general  muscular  tension. 
Impulsive  acts  can  be  explained  by  formulas  which  have 
been  discussed  at  length  in  earlier  chapters.  It  was  there- 
pointed  out  that  the  whole  organism  is  constantly  at  a  hi 
or  lower  level  of  tension.  The  muscles  of  a  waking  person 
are  always  on  the  stretch.  There  are  internal  activities  of 
respiration  and  circulation  and  digestion  which  are  not  only 
in  a  state  of  tension  but  are  in  an  actual  state  of  continuous 
operation.  The  eyes  are  usually  focused  on  some  object ; 


VOLUNTARY  ACTION  AND  ATTENTION       303 

the  hand  is  seldom  at  rest  and  still  more  seldom  in  a  state 
of  relaxation.  This  state  of  muscular  tension  and  internal 
action  is  due  to  the  continuous  stream  of  nervous  impulses 
which  flow  out  to  the  active  organs.  The  outgoing  motor 
impulses  are  in  turn  the  results  of  the  sensory  stimulations 
of  the  moment  and  the  reverberations  of  sensory  impressions 
which  are  circulating  through  the  massive  cerebrum. 

Impulsive  acts  explicable  through  nervous  organization. 
An  impulsive  act  exhibits  in  its  particular  form  the  past 
experience  and  training  of  the  individual.  We  often  judge 
of  a  person's  character  and  education  by  his  impulsive  acts. 
The  spy  who  was  betrayed  by  his  impulsive  and  wholly 
uncontrolled  response  to  a  sudden  military  order  to  stand 
to  attention  exhibited  his  training  by  his  very  lack  of  vol- 
untary control.  One  may  guide  his  impulses  in  some 
measure  by  the  slow  process  of  changing  his  habits.  If 
one  tends  to  look  up  from  his  work  every  time  a  shadow 
passes  over  his  desk,  one  may  overcome  this  tendency  by  self- 
discipline  ;  but  in  that  case  the  inadvertent  lapses  into  the 
old  mode  of  looking  up  will  furnish  the  strongest  evidence 
of  the  difference  between  impulse  and  voluntary  control. 

Impulse  comparable  to  involuntary  attention.  The  term 
"impulse"  as  applied  to  behavior  finds  a  parallel  in  certain 
terms  which  are  used  in  describing  strictly  mental  processes. 
One  tends  to  look  at  any  object  that  moves  through  the 
edge  of  the  field  of  vision.  This  is  an  impulsive  tendency. 
On  the  psychical  side  we  describe  this  fact  by  saying  that 
moving  objects  in  the  edge  of  the  field  of  vision  attract 
involuntary  attention.  Attention  of  the  involuntary  type  is 
then  contrasted  with  certain  higher  types  of  attention 
which  are  designated  as  voluntary.  Thus,  when  one  keeps 
his  eyes  fixed  steadily  on  the  signal  which  he  is  set  to 
watch  in  spite  of  distracting  appeals  to  his  involuntary 
attention,  we  speak  of  his  effort  as  an  exhibition  of  volun- 
tary choice  or  self-control. 


304  '  IIOLOGY 

Impulse  and  involuntary  attention  related  to  perception 
and  habit.  It  is  hardly  necessary  to  elaborate  here  the 
nutter  of  the  relation  <>f  impulsive  activity  to  perct-| 
and  habit.  Our  earlier  chapters  have  abundantly  illustrated 
this  nlation  and  shown  its  importance.  \Ve  have,  however, 
reached  the  point  where  we  must  face  the  problem  of  the 
distinction  In  Attention  and  all  lower  fon 

perception  and  thought,  and  the  problem  of  the  distin 
Ix-tween  voluntary  action  and  impulse. 

Simple  case  of  choice.  Perhaps  the  best  method  of 
making  progress  toward  the  solution  of  our  problem  is  to 
analyze  one  of  the  simpler  cases  of  volition.  Fur  this  pur- 
pose let  us  consider  choice  in  the  presence  of  t\\ 
apprehended  alternatives.  There  lies  before  the  man  who 
is  out  on  a  walk  a  fork  in  the  road.  Sometimes  he  will 
thoughtlessly  strike  out  on  that  path  which  he  has  often 
followed,  or  because  he  is  absorbed '  in  thought  he  will  be 
guided  by  mere  accident.  But  in  the  case  in  which  we  are 
interested  he  sees  the  two  roads  clearly;  each  is  imv 
and  in  terms  of  his  experience  and  training,  equally  acces- 
sible ;  he  may  even  pause  a  moment  and  then  he  turns  to 
the  left  or  right.  We  can  explain  this  turning  in  a  broad, 
loose  way  by  using  such  phrases  as  "he  decided,"  "  he 
chose,"  "  he  selected."  The  impressive  fact  about  each 
of  these  phrases  is  that  it  brings  out  the  truth  that  we  are 
in  the  presence  of  an  explanation  which  includes  and  in- 
volves personality.  We  may  speak  of  impulse  in  an  imper- 
sonal way.  One  is  led  to  do  something  when  he  acts  under 
the  spell  of  impulse,  but  one  makes  the  decision  himself 
when  he  chooses  his  road. 

Behavior  of  the  higher  types  dependent  on  ideas.  The 
broad  terms  of  our  explanation  do  not  satisfy  the  demand 
for  a  scientific  account  of  the  process  of  choice.  We 
must  go  into  greater  detail.  We  can  do  this  in  some 
measure  by  pointing  out  that  bodily  activity  is  related  to 


VOLUNTARY  ACTION  AND  ATTENTION       305 

ideas  no  less  than  it  is  to  percepts.  One  thinks  of  a  tall 
object  and,  as  we  have  seen  in  an  earlier  chapter,  he  tends 
to  move  his  eye  and  his  hand  upward.  One  thinks  over 
an  offense  which  has  been  committed  against  him  and  he 
grows  red  with  rage  and  tense  for  an  attack.  Ideas  are 
related  to  actions  because  the  nervous  processes  involved 
in  the  formation  of  ideas  are,  like  all  nervous  processes, 
parts  of  a  succession  of  processes  leading  to  a  motor  dis- 
charge. In  the  association  areas  of  the  cerebrum  there 
are  complex  nervous  combinations  and  deposits  of  earlier 
excitations  which  are  the  immediate  conditions  of  ideation 
and  at  the  same  time  links  in  the  chain  of  processes 
connecting  the  sense  organs  with  the  motor  centers. 

When  as  a  result  of  experience  an  individual  becomes 
mature  enough  so  that  his  sensory  impulses  are  taken  up 
into  a  highly  developed  train  of  cerebral  processes  before 
they  are  allowed  to  go  to  the  motor  centers,  we  say  of  the 
individual  that  he  acts  on  the  basis  of  ideas.  We  mean  by 
this  statement  that  the  instinctive  tracts  are  relatively  less 
and  less  important  in  this  individual's  life.  We  mean  that 
the  inner  organization  is  more  and  more  important.  The 
inner  organization  of  the  cerebrum  is,  as  we  have  seen, 
relatively  remote  from  mere  sensation.  Hence,  when  the 
inner  processes  come  more  into  control  we  find  the  expla- 
nation of  individual  conduct  not  in  present  impressions 
but  in  past  experience.  The  first  and  most  evident  con- 
clusion about  voluntary  choice  is  therefore  that  it  depends 
on  a  high  development  of  central  paths  and  is  related  to 
the  higher  conscious  processes. 

Voluntary  action  and  its  complex  background  as  contrasted 
with  lower  forms  of  behavior.  The  significance  of  the  fore- 
going conclusion  will  be  fully  grasped  only  when  it  is  re- 
called that  the  central  or  ideational  conscious  processes  are 
complex  as  contrasted  with  mere  perceptions  and  other 
conscious  processes  which  involve  only  the  lower  elements 


.<  H"i.< 

of  the  nervous  system  and  the  lower  phases  of  experience. 

An  idea  is  a  compos  c.    The  general  fact 

about  ideational  consciousness  is  that  it  brings  into  a  single 

a  \a.st  I   elements.     Conduct 

:i  is  based  on  ideation  is,  accordingly,  conduct  which 

sprin  '>ut  of  some  simple  single  impression,  but  out 

combination  of  manifold  impressions. 

We  have  commented  in  earlier  chapters  on  the  advantage 
which  comes  to  the  individual  from  the  possession  of  a 
\\orld  of  ideas  in  which  the  whole  of  experience  can  be 
compactly  represented  and  readily  rearranged.  We  see  now 
the  adv.;:  conduct  of  ideational  powers.  The  indi- 

vidual who  has  ideas  can  act  on  a  broader  basis  than  can 
the  victim  of  mere  impulse,  or  the  undeveloped  individual 
who  has  only  the  most  immediate  sensory  motives  for  his 
comings  and  goings. 

Decision  a  process  of  balancing  ideas.  Let  us  consider 
once  more  our  individual  who  must  choose  at  the  fork  of  the 
road  which  branch  he  will  follow.  No  outsider  can  fathom 
his  choice.  The  inner  world  is  the  scene  of  a  balancing 
and  comparing,  and  out  of  this  inner  world  comes  a  dec; 
which  turns  the  scale  of  muscular  tension  and  results  in  a 
movement.  If  at  the  moment  before  decision  an  outsider 
would  influence  choice,  he  must  appeal  to  the  inner  world ; 
he  must  reach  the  thought  process  of  the  individual  who 
is  deciding. 

Decision  largely  influenced  by  organization  built  out  of  past 
experiences.  When  we  trace  decision  back  into  the  inner 
world,  we  find  justification  for  a  second  general  conclusion. 
Volition  is  determined  in  very  large  measure  by  past  experi- 
ences. All  ideas,  as  we  know,  are  explicable  only  in  terms  of 
organizations  of  experience  which  have  been  set  up  in  the  past. 
The  choice  which  an  individual  makes  to-day  has  its  roots  in 
the  experiences  of  yesterday  and  of  the  earlier  education  be- 
fore yesterday.  To  be  sure,  the  present  may  bring  into  the 


VOLUNTARY  ACTION  AND  ATTENTION       307 

mind  a  manifold  of  experiences  out  of  which  choice  must 
issue,  but  this  manifold  will  be  arranged  and  organized  in 
terms  which  comport  with  the  past  as  well  as  with  the  present. 
We  know  in  ordinary  life  that  it  is  safe  to  assume  that  an 
individual  who  has  made  his  decisions  thus  and  so  in  the  past 
will  in  the  future  exhibit  like  tendencies  of  choice. 

The  relation  of  choice  to  past  experience  is  impressively 
illustrated  by  the  fact  that  voluntary  attention  is  controlled 
by  what  one  has  learned  to  think  about.  If  one  puts  oneself 
through  a  series  of  experiences  in  which  assthetical  objects 
are  agam  and  again  examined  and  recorded  in  thought,  it  is 
safe  to  predict  that  aesthetic  objects  will  in  the  future  be  centers 
of  long  concentrated  attention.  If  one  gives  heed  for  years 
to  matters  of  business  to  the  exclusion  of  all  other  objects  of 
thought,  it  is  sure  to  be  a  great  deal  easier  to  fix  attention  on 
matters  of  this  type  in  all  future  experience. 

We  come  back  to  the  formula  with  which  our  explanation 
began.  Whatever  enters  into  the  personality  of  a  man  enters 
into  his  voluntary  choice.  When  a  man  chooses,  he  expresses 
his  personality.  This  is  the  essential  fact  about  volition  ;  choice 
is  not  an  arbitrary,  sudden  mode  of  thought  or  action  ;  it  is, 
rather,  the  consummate  expression  of  all  that  has  entered 
into  individual  life. 

The  meaning  of  prevision.  While  emphasizing  the  impor- 
tance of  past  experience  in  the  development  of  voluntary  con- 
trol it  is  important  that  we  should  understand  also  the  fact 
that  volition  looks  by  means  of  imagination  into  the  future. 
One  recombines  ideas  and  foresees  in  this  world  of  ideas 
certain  consequences  of  this  or  that  combination.  Behavior 
is  then  dominated,  not  by  present  impressions  or  by  habits 
alone,  it  is  guided  by  the  products  of  imagination.  The  thinker 
has  tried  out  consequences  in  the  world  of  thought  and  has 
the  advantage  in  conduct  of  these  purely  mental  trials.  The 
power  of  imagination  thus  comes  to  be  more  important  for 
human  conduct  than  even  habit  or  instinct. 


v  fl  'GY 

For  example,  the  general  plans  his  movements  with  a  map 
before  him  and  with  a  thousand  items  of  information  in  mind 
about  the  enemy  and  his  own  fora  rial  orders  arc  the 

:s  of  his  comparisons  and  mental  experiments. 

The  power  becomes  thus  a  matter  of  the  rela 

of  compl<  "nal  processes  to  behavior.   Conduit 

lated  •  1  any  elaborate  process  of  combining  ideas 

which  results  in  a  new  idea  will  influence  beha\ 

The  problem  of  the  freedom  of  the  will.  We  are  now  in 
a  position  to  consider  one  of  the  problems  which  has  long 
been  a  subject  of  hot  debate  among  students  of  human  life 
and  conduct ;  namely,  the  problem  of  the  freedom  of  the  will. 
It  has  been  argued  on  the  one  side  that  in  a  given  emergency 
an  individual  can  follow  any  one  of  the  various  courses  which 
lie  before  him.  The  five  or  six  paths  which  he  might  follow 
all  attract  him,  but  he  is  free  to  follow  the  one  which  he 
chooses.  So  far  we  must  agree.  Hut  the  extremists  seem  to 
argue  at  times  that  the  chooser  is  in  no  wise  bound  even  by 
his  own  earlier  experiences  and  training.  The  individi: 
free  in  the  absolute  sense,  we  arc  sometimes  told.  He  may 
at  this  given  moment  strike  out  without  reference  to  his  past 
or  to  any  other  cause.  His  action  is  without  determining 
cause.  He  is  a  wholly  independent  being,  unguided  by  any 
outer  or  inner  considerations  except  as  he  is  willing  in  his 
sovereign  independence  to  give  heed  to  these  considerations. 
This  last  statement  of  the  doctrine  has  sometimes  been  called 
the  doctrine  of  libertarianism.  For  this  view  there  is  no  evi- 
dence. Personality  is  never  free  from  its  own  past,  even  when 
it  is  producing  new  combinations  of  ideas  through  imagination. 
Personality  is  a  product  of  organization.  Personality  is  the 
name  of  that  individual  nature  which  has  been  developed  out 
of  the  play  and  interplay  of  impressions  and  instincts  and 
conscious  comparisons  and  imaginations.  Personality  is  never 
free  from  itself.  Voluntary  choice  is  an  expression  of  per- 
sonality, not  of  sheer  caprice. 


VOLUNTARY  ACTION  AND  ATTENTION       309 

Voluntary  choice  guided  by  purposes.  The  conclusion 
to  which  we  are  thus  led  gives  the  largest  emphasis  to  those 
reorganizations  of  experience  which  were  discussed  in  the 
chapter  on  concepts.  We  saw  in  that  chapter  how  a  dominant 
inner  purpose  may  control  the  organization  of  all  thought. 
I  may  resolve  to  think  about  a  geometrical  proposition,  and 
all  my  ideational  processes  will  be  rearranged  and  worked  out 
in  conformity  with  this  central  purpose.  The  rise  in  the  mind 
of  a  dominant  idea  is  therefore  an  important  event,  not  merely 
in  a  vague,  abstract  sense,  but  in  a  practical  sense  as  well. 
When  some  personality  takes  up  with  fixed  purpose  a  definite 
line  of  thought,  his  own  conduct  and  ultimately  that  of  his 
social  environment  will  be  affected.  This  is  what  was  meant 
by  the  statement  that  consciousness  is  a  cause  and  a  very 
potent  cause  in  the  world  of  affairs. 

Behavior  of  a  higher  type  is  related  to  education.  A  text- 
book on  the  science  of  human  mental  processes  is  not  the 
place  for  a  homily  on  conduct,  but  it  is  so  obvious  an  in- 
ference from  what  has  been  said  that  one  can  hardly  refrain 
from  recording  the  principle  that  all  choice  and  all  signifi- 
cant human  influence  in  the  world  are  dependent  for  their 
character  on  the  growth  of  ideas.  He  who  would  influence 
his  own  conduct  or  that  of  others  must  therefore  look  to 
the  roots  of  conduct  in  organized  processes  of  ideation  and 
thought. 

It  will  be  proper,  therefore,  for  us  to  follow  the  study  of 
voluntary  behavior  by  a  discussion  of  some  of  the  more 
obvious  devices  by  which  human  choices  may  be  turned  in 
the  direction  of  fruitful  and  efficient  developments. 

Early  scientific  studies  of  behavior  purely  external.  Before 
we  apply  the  lessons  we  have  learned,  we  owe  it  to  the  his- 
tory of  scientific  method  to  comment  briefly  on  the  develop- 
ment of  scientific  studies  of  human  behavior.  The  earliest 
scientific  investigations  of  bodily  activities  were  undertaken 
from  a  wholly  external  point  of  view.  The  specific  method 


310  P8Y<  inn.oGY 

h  was  used  for  such  investigations  was  devised  by  the 
astronomers  who  were  interested  in  understanding  the  defi- 
ciencies of  human  m<  tl  when  attempts  were  made  to 
use  these  mo\  m  recording  the  transit  of  stars  through 
the  field  of  the  telescope.  The  astronomers  found  that  tin- 
hand  cannot  be  moved  as  soon  as  the  eye  sees  a  light. 
They  therefore  measured  the  interval  whirh  elapsed  between 
visual  impression  and  hand  movement.  They  found  further 
that  different  individuals  have  different  personal  equal 
or  periods  of  reaction.  Evidently  the  observations  of  the  as- 
tronomers arc  ver.  •  ivc  as  foundations  for  psychological 
investigations.  The  early  psychological  investigators, 
ever,  did  not  transform  the  method  into  a  psychological 
method  ;  they  took  it  over  unmodified.  Their  investigations 
of  the  active  process*  not  based  upon  any  elaborate 
analysis.  Certain  simple  movements  were  measured  with 
reference  to  the  time  which  elapsed  between  the  stimulus 
and  the  muscular  contraction,  exactly  as  this  time  had  been 
measured  by  the  astronomers.  The  investigation  of  this  time 
of  reaction  was  treated  as  an  indirect  means  of  getting  at  the 
complexity  of  the  nervous  and  conscious  processes  preceding 
the  reaction.  It  was  found,  for  example,  that  the  length  of 
time  required  for  a  simple  reaction  was  appreciably  shorter 
than  the  length  of  time  required  for  a  reaction  which  involved 
the  discrimination  of  two  simple  colors  from  each  other.  Thus, 
if  the  reactor  were  required  to  move  his  finger  as  soon  as 
possible  after  being  stimulated  by  a  flash  of  light,  the  meas- 
urement of  this  interval  gave  what  was  called  a  simple  reac- 
tion time  of  about  -|VoV  °^  a  second,  or  iSoer,  the  letter  a 
being  used  as  the  symbol  for  a  thousandth  of  a  second.  If, 
on  the  other  hand,  the  experiment  was  arranged  in  such  a 
way  that  a  number  of  different  colors  could  be  presented  to 
the  subject,  and  it  was  prescribed  that  he  should  react  only 
after  a  clear  recognition  of  one  of  these  colors,  then  the  clear 
recognition  or  discrimination  added  appreciably  to  the  time 


VOLUNTARY  ACTION  AND  ATTENTION       311 

which  elapsed  between  the  giving  of  the  stimulus  and  the 
movement,  sometimes  as  much  as  60  cr.  This  longer  period 
of  time  was  known  as  discrimination  time.  Again,  if  instead 
of  reacting  always  with  the  same  hand  or  finger  the  reactor 
was  instructed  to  respond  to  one  kind  of  stimulation  with  one 
movement  and  to  another  kind  of  stimulation  with  a  second 
movement,  the  process  involved  not  merely  discrimination 
but  also  a  simple  choice  of  the  organ  to  be  moved.  The 
reaction  time  in  this  case  was  called  choice  time. 

Purely  external  investigations  not  productive.  The  earlier 
experimenters  on  reaction  were  satisfied  to  seek  exact  defi- 
nitions of  the  lengths  of  these  various  kinds  of  reaction 
time.  They  paid  little  or  no  attention  to  introspection  on 
the  part  of  the  reactor.  The  results  of  a  large  number  of 
reactions  were  averaged,  and  the  comparison  between  differ- 
ent simple  mental  processes  was  made  in  terms  of  these 
general  averages.  The  outcome  for  psychology  of  these  ex- 
ternal studies  was  by  no  means  large.  There  is  very  little 
contribution  to  the  knowledge  of  human  nature  in  the  details 
of  reaction  times. 

Recent  investigations  and  their  stress  on  introspection  and 
analysis  of  movement.  Recent  investigations  of  reactions 
differ  from  the  earlier  external  measurements  in  two  re- 
spects. First,  the  effort  has  been  made  to  find  out,  as  far 
as  possible,  what  are  the  conditions  in  the  experience  of 
the  reactor  during  the  reaction  process.  Attention  has  been 
called,  for  example,  to  the  fact  that  if  the  reactor's  atten- 
tion is  turned  toward  his  hand,  rather  than  toward  the  organ 
of  sense  which  is  to  be  stimulated,  the  time  of  reaction  will 
for  most  individuals  be  shorter.  A  distinction  may  therefore 
be  drawn  between  so-called  muscular  reactions  and  sensory 
reactions.  The  average  difference  in  time  corresponding  to 
this  introspective  difference  is  often  as  great  as  zoocr.  Again, 
the  different  types  of  discrimination  and  choice  have  been 
introspectively  examined.  The  question  of  whether  the 


r>\<  HI 

content  of  consciousness  before  a  choice  reaction  is  an  image 
of  the  movement  to  be  executed,  or  a  concentration  of  ;<• 
tion  upon  the  sensation  received,  has  been  introspect 
studied.  The  results  of  these  introspective  studies  have  done 
much  t<>  clear  up  the  psychological  doctrin<  Fur- 

thermore, the  general  on;  :  a  more  careful  examina- 

tion of  conscious  correlates  of  reaction  has  shown  how  ut 
formal  \\as  the  gross  averaging  of  all  kinds  of  cases  in  the 
earlier  investigations.     It  may  be  said  that  no  introspc 
differences  ever  occur  without  some  modification  in  the  dura- 
tion of  the  reaction  process;  hence,  differences  in  dur. 
are  highly  significant  when  supported  by  introspective  ob- 
servation  and   should    not   be   eliminated   by   an   arbitrary 
method  of  mathematical  averaging. 

Analysis  of  the  form  of  movement.  The  second  way  in 
which  recent  reaction  experiments  have  been  elaborate 
by  analyzing  the  forms  of  the  reaction  movement  It  was 
formerly  assumed  that  the  act  of  lifting  the  hand  from  a 
reaction  key  was  so  simple  a  process  that  it  could  hi 
garded  as  uniform  in  character  throughout  a  long  series  of 
experiments.  Recent  investigations  show  that  there  is  no 
such  thing  as  an  absolutely  uniform  series  of  movement  proc- 
esses. There  are  certain  reactors,  for  example,  who,  when 
they  make  an  effort  to  lift  the  hand  as  rapidly  as  possible, 
frequently  go  through  a  preliminary  downward  movement 
before  beginning  the  upward  movement.  There  are  other 
preliminary  phases  of  movement  which  prepare  the  way  for 
the  final  reaction,  and  the  relation  between  these  preliminary 
movements  and  the  final  movement  of  the  hand  may  be  so 
complicated  as  to  influence  measurably  the  duration  of  the 
reaction  period.  The  relation  of  these  complexities  of  move- 
ment to  nervous  organization  is  most  intimate.  The  studies 
in  earlier  chapters  of  the  relation  of  perception  and  feeling 
to  reaction  have  indicated  the  significance  for  psychology 
of  the  analysis  of  reactions.  By  way  of  criticism  of  the 


VOLUNTARY  ACTION  AND  ATTENTION       313 

earlier  studies,  it  may  be  said  that  they  treated  reactions  as  if 
they  were  merely  uniform  mechanical  processes.  The  recent 
investigations  have  made  it  clear  that  the  study  of  muscular 
behavior  is  productive  only  when  it  is  related  to  a  complete 
account  of  the  introspective  processes  and  the  antecedent  or- 
ganizations which  condition  the  particular  form  of  movement. 
Concept  of  organization  as  fundamental  in  all  psychologi- 
cal studies.  The  study  of  movement  has  therefore  brought 
us  back  to  the  consideration  of  principles  of  organization. 
Volition  and  impulse  are  merely  the  active  correlates  of  or- 
ganized forms  of  ideational  and  perceptual  experience.  The 
earlier  studies  of  mental  activity  and  the  present  study  of 
behavior  are  mutually  supplementary.  We  do  not  require 
any  unique  formulas  or  the  recognition  of  any  new  factors. 
Behavior  is  a  necessary  and  ever-present  physical  correlate 
of  experience  and,  at  the  same  time,  a  product  of  all  those 
organizations  which  lie  back  of  experience  itself. 


CHAPTER  XVI 

Ml. MA  I.    HY<;iKNE 

Hygiene  a  suggestive  term  for  psychology.  Just  as  there 
is  a  way  of  keeping  one's  physical  organs  in  good  condition 
through  the  adoption  of  rational  principles  of  nutrition  and 
ise  and  sleep,  so  there  is  a  way  of  organizing  one's 
mental  processes  with  a  view  to  meeting  most  efficiently  the 
demands  of  life. 

Relation  of  psychological  hygiene  to  physiological.  The 
first  maxim  of  mental  hygiene  is  that  the  nervous  s\ 
must  be  kept  in  a  healthy  condition.  Indeed,  physical  hy- 
giene here  becomes  an  essential  part  of  the  application  of 
psychology.  If  the  nutrition  of  the  body  is  defective,  the 
nervous  system  suffers  with  the  other  organs,  and  the  mental 
processes  become  abnormal.  The  same  is  true  of  sleep  and 
the  excretory  processes.  The  body  must  be  in  good  condition 
if  the  mind  is  to  do  its  work. 

Coordination  of  bodily  activities.  Assuming  for  the  pur- 
poses of  our  discussion  that  the  general  physiological  condi- 
tion is  favorable,  the  next  maxim  of  mental  hygiene  is  that 
all  one's  activities  must  be  brought  into  harmonious  coopera- 
tion, for  the  first  function  of  the  central  nervous  system  is 
to  control  and  coordinate  the  parts  of  the  body.  Thus,  when 
muscles  are  contracting  vigorously,  there  is  a  call  for  blood 
in  the  particular  part  of  the  body  which  is  in  action.  The 
nervous  system  must  distribute  the  blood  supply  of  the  body 
in  such  a  way  as  to  meet  the  strenuous  local  demand  and  at 
the  same  time  keep  all  of  the  supporting  organs  properly 
supplied.  The  young  child  has  to  acquire  the  ability  to  do 

3'4 


MENTAL  HYGIENE  315 

this.  At  first  his  organic  activities  are  subject  to  all  kinds 
of  distractions  and  incoordinations.  He  is  unprepared  for  any 
sustained  effort  because  his  body  is  not  yet  a  well-coordinated 
system. 

Perhaps  the  most  striking  illustration  of  the  incoordina- 
tion  of  a  child's  body  is  seen  in  the  fact  that  excitement  of 
any  kind  interferes  with  digestion.  Digestion  is  in  very 
large  measure  an  active  process.  The  glands  are  active  in 
secretion,  and  the  muscles  of  the  digestive  organs  contract 
in  rhythmical  movements  that  are  necessary  in  carrying  the 
food  through  the  alimentary  tract.  The  elaborate  system  of 
organs  thus  involved  in  digestion  must  cooperate  or  the  whole 
process  will  be  disturbed.  Suppose  that  all  is  going  well, 
when  suddenly  a  shock  of  violent  stimulation  comes  to  the 
nervous  system.  The  flood  of  uncontrolled  excitement  will 
be  discharged  by  the  motor  fibers  into  the  inner  muscular 
system,  and  digestion  and  circulation  and  respiration  will 
be  violently  disturbed.  It  is  one  of  the  important  results 
of  training  that  disturbances  of  this  type  are  overcome  in 
increasing  measure.  The  mature  nervous  system  tends  to 
check  and  distribute  excitements  so  that  the  organism  may 
not  be  disturbed  in  its  fundamental  activities. 

Little  children  are  very  often  disturbed  by  mere  social 
excitements  to  an  extent  which  seriously  interferes  with 
life.  An  adult,  on  the  other  hand,  can  receive  the  same 
kind  and  amount  of  stimulation  and  not  be  distracted  from 
the  inner  activities  of  organic  life.  The  training  of  one- 
self to  receive  all  sorts  of  external  stimulations  without  dis- 
locating the  inner  machinery  is  one  of  the  important  lines 
of  personal  training. 

Control  of  excessive  stimulations.  The  formulas  which 
can  be  adopted  for  such  training  are  apparently  contradic- 
tory. First,  one  should  have  regular  habits  of  life.  This 
will  set  up  wholesome  and  balanced  forms  of  action. 
Second,  one  should  expose  himself  from  time  to  time  to 


316  .•  M»'i .. 

irregular  and  a  ions.    <  )r,  perhaps  better  put,  one 

:i    he   lives   in   tin-  \\orld  with  ;>ius  kinds  of 

experience,  to  be  drawn  out  of  mere  routine  by  forms  of 
•i-ment  which  tend  to  break  up  his  simple  habits  of  life. 
1'hen  one  should  ain.  inner 

life  by  dclilx  ontrolling  the  excitement  in  ord< 

the   organic   habits  an  opportunity  to  reassert    t 
selves.    Control   often    m  luxation.     Ixrt   an   excited 

person  take  two  or  three  long  breaths;  let  him  relax  the 
jaw  muscles  or  the  m  the  han<  vment  which 

tightens  up  the  muscles  can  often  be  overcome  by  these 
sheer  physical  devices.  If  the  physical  devices  do  not 
suffice,  let  there  be  an  appeal  to  voluntary  effort.  If  the 
excitement  is  om  r,  let  th<  1  person  face  the 

problem  and  explore  the  source  of  the  fear.    Let  one  reason 
himself,  if  he  can,  into  a  less  tense  attitude.    The  i.. 
that  every  experienced  adult  has  in  the  course  of  his  life 
come  to  the  point  where  he  can  deal  more  or  less  success- 
fully with  excitement.    Ability  to  master  excitement  si 
an  internal  state  of  coordination  of  a  high  type.   The  organ-' 
ism  has  acquired  ability  to  undertake  several  kinds  of  action 
at  once  without  interfering  with  its  own  life. 

While  emphasizing  the  importance  of  internal  harmony, 
it  may  be  well  to  refer  once  more  to  the  disintegr;: 
effects  which  follow  chronic  incoordination.  All  the  disso- 
ciations which  were  discussed  in  an  earlier  chapter  have  in 
them  elements  of  internal  discord.  The  individual  whose 
nervous  system  is  sending  out  conflicting  and  discordant 
impulses  is  an  unhappy  individual  in  his  conscious  experi- 
ence and  an  incoordinated  individual  in  his  active  life. 

Perceptual  analysis.  A  third  maxim  of  mental  hygiene  is 
one  which  relates  to  perception.  All  progress  in  perception 
and  in  muscular  coordination  results  from  particularization 
or  concentration  of  attention  on  definite  items  of  experience. 
It  is  worth  the  effort  for  everyone  to  learn  to  analyze  the 


MENTAL  HYGIENE  317 

objects  in  his  environment.  Even  if  one  is  not  going  to  use 
the  details  of  information  at  the  moment,  it  is  valuable  from 
the  point  of  view  of  future  adaptation  to  be  able  to  concen- 
trate attention  and  action  on  particular  aspects  of  a  situa- 
tion. Most  games  illustrate  this  kind  of  demand.  If  a  boy 
learns  to  catch  a  ball,  he  trains  himself  in  concentration  of 
attention  and  control  of  his  muscles.  In  the  animal  world 
nature  provides  young  animals  with  a  play  impulse  through 
which  the  untrained  individual  is  led  into  exploratory  forms 
of  behavior  which  in  later  life  will  be  of  use  in  nosing  out 
real  enemies  and  real  prey. 

As  a  practical  measure  of  self-training,  it  may  be  urged 
that  everyone  ought  always  to  analyze  what  he  encounters. 
He  should  notice  the  details  of  behavior  of  those  whom  he 
meets ;  he  should  note  the  contour  of  the  objects  he  sees. 
If  he  gets  a  hint  that  there  are  details  which  he  has  over- 
looked, let  him  train  himself  to  go  back  and  find  these 
details.  The  value  of  such  self-control  is  not  merely  in  the 
results  gained  at  the  moment,  but  in  the  conscious  tendency 
to  analyze.  It  was  pointed  out  in  an  earlier  chapter  that 
perception  is  an  active  process  initiated  by  the  individual. 
The  application  of  that  lesson  is  that  the  individual  must 
be  active  if  he  would  perceive  completely. 

Perceptual  synthesis.  The  counterpart  of  the  foregoing 
demand  for  analysis  is  the  demand  that  one  cultivate  the 
power  of  grasping  many  impressions  at  the  same  tune.  The 
observer  should  train  himself  to  recognize  at  a  glance  as 
much  as  possible.  It  is  said  that  the  schools  which  train 
performers  to  give  exhibitions  of  ability  to  recall  a  whole 
box  full  of  trinkets  after  a  single  glance  begin  in  childhood 
by  exposing  to  the  prospective  performer  for  recognition, 
after  a  very  brief  exposure,  three  objects,  then  four,  then 
five,  and  so  on.  The  scope  of  attention  is  thus  broadened. 

All  forms  of  expert  observation  involve  this  breadth  of 
apprehension.  The  expertness  cultivated  in  reading  involves 


{(    lid.' 

tin-  IXHUT  <>f  recognizing  at  a  glance  a  series  of  words.   The 

child  is  limited  in  his  abilit)  to  grasp  words  and  only  gradu- 
ally reaches  the  stage  where  he  can  take  in  many  at  once. 
The  poor  n  found  to  be  one  who  has  made  little 

progress  in  the  cultivation  of  a  broad  range  of  alter 
Many  an  adult  is  seriously  handicapped  because  he  can 
recognize  at  a  glance  only  one  word.  The  individual  who 
finds  himself  thus  limited  should  train  himself  by  going 
rapidly  over  familiar  material.  The  familiarity  will  give  the 
necessary  ck-anu-ss  to  details,  for  familiarity  is  likely  to  im- 
ply some  earlier  analysis.  The  rapid  view  of  the  familiar 
material  will  help  to  synthesize  many  elements  into  a  single 
experience.  The  limits  to  which  skill  may  be  cultivated  in 
this  matter  are  described  by  saying  that  an  expert  reader 
can  very  often  surpass  by  two  or  three  hundred  per  cent 
an  ordinary  reader. 

What  is  true  of  reading  is  true  of  other  situations  in 
which  cxpertness  can  be  cultivated.  The  person  who  draws 
learns  not  only  to  sec  minutely  but  to  take  in  the  totality 
of  a  situation.  The  architect  sees  many  features  of  a  build- 
ing and  shows  a  grasp  of  both  detail  and  general  appear- 
ance which  the  untrained  individual  can  hardly  compre- 
hend. The  skilled  artisan  sees  more  in  every  piece  of 
work  of  the  type  which  he  knows  than  can  an  inexpert 
observer. 

Dangers  of  specialization.  There  appears  at  this  point 
one  of  the  crucial  difficulties  in  education.  Perception  is  a 
process  in  which  individual  development  is  often  highly 
specialized.  For  example,  the  skilled  artisan  may  see  much 
in  the  kind  of  materials  with  which  he  is  used  to  dealing 
and  be  quite  oblivious  to  other  perceptual  facts ;  the  shoe- 
maker sees  the  shoes  which  a  passerby  wears,  but  has  no 
interest  in  his  tailoring.  The  fact  is  that  perception  is  closely 
related,  as  was  shown  in  an  earlier  chapter,  to  special  train- 
ing in  direct  manipulation.  The  extension  of  experience  to 


MENTAL  HYGIENE  319 

include  many  different  kinds  of  percepts  will  therefore  re- 
quire deliberate  effort  on  the  part  of  the  observer ;  other- 
wise he  will  fall  into  narrow  modes  of  seeing  only  a  small 
part  of  the  world. 

Control  of  perceptual  attitudes.  Not  only  so,  but  the 
limited  range  of  ordinary  perceptual  experience  is  exhibited 
in  the  fact  that  our  attitudes  toward  the  objects  about  us 
are  very  often  quite  irrational.  One  dislikes  a  person  whom 
one  meets,  for  no  better  reason  than  that  the  stranger  re- 
sembles an  acquaintance  whom  the  observer  does  not  like. 
The  child  likes  a  color  because  he  saw  it  first  in  an  agree- 
able setting.  If  experience  takes  its  course  without  super- 
vision, these  attitudes  become  fixed  and  the  narrowness  of 
perceptual  interpretation  passes  into  a  lifelong  habit. 

Practical  study  of  one's  own  attitudes  ought  to  raise  one 
above  the  level  of  accidental  attitudes.  It  often  requires 
time  and  effort  to  set  aside  one  of  the  ready-made  reactions 
which  so  easily  attach  to  percepts.  The  person  who  is  afraid 
of  thunder  and  lightning  may  have  to  drill  himself  for  years 
to  overcome  this  attitude  which  has  become  second  nature, 
but  a  new  attitude  can  be  cultivated  by  anyone  who  will  set 
himself  to  the  task. 

Control  of  attitudes  as  a  case  of  volition.  In  general,  the 
types  of  training  which  have  been  advocated  in  the  last  two 
paragraphs  are  types  which  can  be  accomplished  only  through 
the  domination  of  experience  by  higher  mental  processes. 
A  man  must  know  something  of  himself  in  an  ideational  way 
if  he  is  deliberately  to  cultivate  new  ranges  of  perception  and 
new  attitudes.  What  he  accomplishes  through  self-control 
will  ultimately  reach  back  into  his  perceptual  life  and  will 
make  him  alert  about  many  new  opportunities  to  see  and 
hear;  it  will  also  make  his  personal  attitudes  more  rational. 
The  result  will  be  a  richer  perceptual  life  and  a  more  whole- 
some series  of  attitudes.  Perception  will  thus  grow  and 
overcome  the  inherent  tendency  toward  specialization. 


320  ,<    IK'I., 

Rules    of    wholesome    ideation.     When    one    comes 
memory  and  1  abstract 

of  applications  in  jx.-rsonal  life  is  unbounded.  A  few  par- 
ticular in.i\ir.  .  ntal  hygiene  in  these  fields  may  be 
selected,  hut  the  student  will  have  to  supph  own  case 
the  rules  which  will  insure  success  of  his  mental 
processes. 

Economy  of  mental  effort.     <  >ne  of  the  social  problems 
of  memory  is  the  problem  of  economy  of  effort.     If  one  has 
a  passage  of  prose  to  learn  by  heart,  how  should  1 
by   learning  a   line  at  a   time  or  by  taking   in   lar  _ 
The  answer  supplied  by  careful  exj>crimentation  is  that  he 
should  learn  by  large  units.     The  reason  why  learning  by 

advantageous  is  not  far  to  seek.  If  one  i 
to  the  end  of  a  line  and  then  goes  back  to  the  beginnii 
the  line,  he  sets  up  an  association  between  the  two  en 
the  same  line,  whereas  he  ought  to  set  up  an  associ 

een   the  end  of   the  first  line  and  the  beginning  of 
the   next. 

The  maxim  that  one  should  learn  by  large  units  can  be 
amplified  to  include  many  cognate  cases.  The  student  trans- 
lating a  foreign  word  looks  up  the  word  in  the  vocabulary 
and  glances  through  a  long  list  of  meanings,  most  of  which 
he  rejects.  It  would  be  economy  of  mental  effort  in  the 
long  run  if  he  would  master  all  the  meanings,  rejecting  none 
but  including  all  in  a  complete  view  of  the  word.  The  failure 
of  the  student  to  see  this  is  due  to  the  apparent  ease  of 
accomplishing  the  limited  immediate  purpose,  whereas  he 
ou.nht  to  cultivate  a  broad,  though  more  remote,  purpose. 

Preparation  as  aid  to  memory.  Another  general  principle 
of  memory  is  that  even  a  very  abstract  scheme  which  pre- 
pares the  mind  in  advance  to  retain  experiences  will  make 
it  possible  to  hold  more  in  memory  than  can  be  taken  in 
if  the  material  is  not  arranged.  This  is  illustrated  by  the 
man  who  prepared  himself  to  remember  long  arbitrary  lists 


MENTAL  HYGIENE  321 

of  words  by  setting  up  in  his  mind  a  series  of  a  hundred 
rooms,  arranged  in  fixed  order,  in  each  of  which  was  hung 
a  single  mental  picture ;  then  when  the  words  to  be  re- 
membered were  given,  he  associated  one  with  each  succes- 
sive mental  room  and  picture.  Later,  by  going  through  the 
rooms  in  order,  he  could  recall  the  series  of  associated 
ideas.  The  prearranged  mental  scheme  was  the  key  to  his 
power  to  retain. 

Still  better  is  a  rational  scheme.  The  student  of  science 
gets  ultimately  an  outline  of  his  subject  in  mind,  and  every 
new  author  whom  he  reads  falls  into  this  scheme  and  is 
classified  in  detail.  A  trained  student  thus  cultivates  a 
method  of  remembering  a  great  body  of  opinion  by  classi- 
fying it. 

If  one  wants  to  learn  to  remember  what  cards  have  been 
played  in  a  card  game,  let  him  have  a  plan  of  arranging 
his  own  hand,  and  then  the  accidents  of  the  game  will  be 
forced  into  an  orderly  scheme. 

Organization  the  key  to  all  correct  thought.  The  general 
formula  which  emerges  from  all  these  examples  is  the 
formula  of  organization.  Ideas  should  be  arranged.  When 
ideas  are  arranged,  they  can  be  carried  in  greater  bulk 
than  when  they  are  isolated.  Indeed,  they  can  never  be 
isolated  in  any  absolute  sense  because  some  kind  of  asso- 
ciation will  always  couple  them  together.  Arrangement 
means,  therefore,  an  association  which  is  dominated  by 
some  clear  purpose  or  plan. 

The  domination  of  thought  by  some  leading  idea.  This 
general  formula  can  be  employed  also  in  treating  briefly 
some  of  the  phases  of  abstraction.  The  world  is  for  each 
individual  rearranged  in  terms  of  personal  interests  and 
personal  modes  of  abstraction.  The  man  whose  ambition 
is  wealth  selects  out  of  everything  that  comes  into  his 
experience  those  elements  which  have  to  do  with  money. 
He  comes  ultimately  to  see  the  world  from  the  one  point 


322  PSYCHOLOGY 

of  view.    The  man  whose  ambition  is  power  sees  men  and 

things  from  an  entirely  different  point  of  view.    The  man 
without  ambition  drifts  about,  looking  at  his  world  to-day 
from  one  point  of  view,  to-morrow  from  another.    Ah- 
ti»n  is  the  most  subtle  and  pervasive  fact  in  individual 
We  all  transform  the  worlds  in  which  we  live  by  the  pur- 
poses which  control  us  in  life.    So  absorbed  do  we  become 
in  our  personal  points  of  view  that  it  requires  a  serious  jolt 
to  bring  us  back  to  the  point  where  we  are  willing  to  make 
revisions. 

Language  of  great  importance  in  furnishing  central  ideas. 
UK-  importance  of  language  as  an  instrument  of  social  ab- 
straction will  be  instantly  recognized  in  the  light  of  what 
has"  gone  before.  There  are  phrases  current  in  language 
which  dominate  personal  thought  and  make  our  thinking 
like  that  of  our  neighbors.  Take  such  a  word  as  "  effi- 
ciency "  ;  the  world  is  different  to  a  man  after  he  acquires 
that  word  as  a  part  of  his  working  vocabulary. 

The  ineffectiveness  of  a  detached  verbal  idea.  The  mean- 
ing of  these  statements  for  individual  development  can 
hardly  be  misunderstood.  The  practices  of  the  schools  in 
making  language  subjects  the  center  of  the  course  of  study 
can  be  defended  in  the  light  of  a  psychological  study  of 
language.  To  be  sure  there  is  danger  in  mere  verbal 
reactions.  Language  subjects  in  the  schools  need  to  be 
brought  back  into  relation  with  the  practical  activities  of 
life  in  order  to  insure  the  use  of  words  as  instruments 
of  real  abstraction  and  social  intercourse.  Mere  words  may 
be  trivial,  but  words  as  guides  to  thought  and  as  instru- 
ments for  the  determination  of  abstractions  are  powerful 
factors  in  controlling  personal  thought  and  action. 

To  the  student  who  spends  most  of  his  time  dealing 
with  books  perhaps  the  warning  in  the  last  paragraph 
should  be  made  somewhat  clearer.  The  cerebrum  is  so 
complex  in  its  structure  that  a  tract  may  be  established 


MENTAL  HYGIENE       ,  323 

through  its  tissue,  leading  from  the  visual  center  directly 
to  the  speech  center.  Words  read  will  be  repeated,  but  if 
this  short  circuit  alone  is  set  in  action,  the  process  will 
have  to  be  described  as  one  of  mere  repetition. 

Higher  organization  as  a  cure  for  verbalism.  The  remedy 
for  mere  verbalism  is  the  development  of  larger  systems  of 
behavior.  The  eye  may  see  a  long  stick  and  the  hand 
may  use  this  stick  under  the  guidance  of  organized  experi- 
ence to  pry  up  a  weight.  This  reaction  with  the  stick  may 
not  arouse  at  all  the  speech  tract  above  described,  even 
though  the  speech  tract  has  been  aroused  by  a  textbook 
in  physics  to  repeat  a  passage  about  a  lever.  The  indi- 
vidual thus  contains  within  his  complex  life  one  series 
which  is  a  series  of  reactions  with  a  real  lever  and  another 
series  which  tells  about  levers.  There  is  a  possibility  that 
these  two  tracts  existing  side  by  side  will  not  affect  each 
other  in  any  way.  The  individual  who  is  aware  of  this 
dangerous  type  of  separation  of  relatable  activities  within 
himself  will  make  a  conscious  effort  to  unite  verbal  reac- 
tions with  practical  reactions.  He  will  aim  to  set  up  a 
higher  internal  organization  including  both  speech  and 
hand  adjustment. 

A  neglect  of  this  demand  for  complete  internal  develop- 
ment is  one  of  the  most  serious  dangers  of  our  present-day 
education.  The  real  trouble  is  not  that  words  in  themselves 
are  bad  or  that  handwork  in  itself  is  limited,  but  in  the 
rush  of  modern  life  the  two  are  cultivated  side  by  side  and 
neither  gets  the  benefit  of  the  other.  What  is  needed  is 
a  higher  type  of  organization  which  will  include  the  ver- 
bal or  theoretical  discussion  of  levers  and  the  illuminating 
experiences  that  come  from  having  levers  in  the  hand. 
This  higher  form  of  experience  will  bring  to  practical  life 
all  the  advantages  of  abstraction  and  to  abstract  life  all 
the  advantages  of  concrete  application.  Both  ends  can  be 
reached  in  one  and  the  same  individual. 


324  PSYCHOLOGY 

Self-directed  organization  as  the  goal  of  the  higher  mental 
life.  Again  we  find  ourselves  speaking  in  terms  of  I 
forms  of  organization.  Wherever  the  individual  can  compre- 
hend in  a  single  system  of  nervous  or  mental  organization 
more  elements,  there  the  adaptations  of  life  and  experience 
will  be  broader  and  better.  The  lesson  is  clear.  The  indi- 
vidual must  seek  of  his  own  initiative  those  higher  forms 
of  organization  which  will  realize  most  fully  the  possibilities 
of  his  life. 

The  highest  level  of  individual  organization  is  reached 
when  mental  development  becomes  a  matter  of  voluntary 
control.  Under  the  definition  of  volition  which  was  worked 
out  in  the  last  chapter  it  was  seen  that  volition  consists  in 
a  control  of  action  through  intellectual  prevision  of  results. 
So  it  is  also  in  the  mental  world.  When  the  mind  by  self- 
study  sees  the  goal  which  self-development  should  reach, 
it  is  possible  by  voluntary  effort  to  move  toward  this  goal. 
Thus  we  have  seen  how  knowledge  of  the  nature  of  per- 
ceptual attitudes  may  guide  one  in  modifying  these  atti- 
tudes. In  like  fashion,  knowledge  of  the  limitations  of 
study  of  theory  may  guide  one  in  cultivating  applications. 
Knowledge  of  one's  own  limitations  may  lead  to  a  per- 
sistent attack  upon  these  limitations.  In  short,  voluntary 
self-development  means  the  cultivation  of  the  broadest 
possible  systems  of  behavior. 


CHAPTER  XVII 
APPLICATIONS  OF  PSYCHOLOGY 

Psychology  a  basis  of  scientific  thinking  about  human 
conduct.  There  are  many  phases  of  practical  and  scientific 
thought  regarding  human  activity  which  are  illuminated  by 
the  study  of  psychology.  Indeed,  wherever  human  nature  is 
a  factor  in  any  set  of  phenomena,  there  is  need  of  a  clear 
understanding  of  the  human  contribution  to  the  situation, 
and  this  can  be  supplied  in  scientific  form  only  by  a  study 
of  psychology.  The  complete  demonstration  of  the  useful- 
ness of  psychology  would  require  a  series  of  supplementary 
chapters.  It  will  be  enough  for  our  present  purposes  if  the 
general  outlines  of  some  of  these  discussions  are  presented. 

Design  in  art  as  a  psychological  fact.  Our  first  illustration 
can  be  drawn  from  the  field  of  the  fine  arts.  This  is  a  sphere 
in  which  the  relations  of  the  individual  to  his  external  en- 
vironment are  relatively  free.  When  the  artist  paints  a  pic- 
ture, he  is  guided,  so  far  as  the  design  of  his  production  is 
concerned,  by  the  laws  of  his  own  taste.  Art  grows  out  of 
the  demand  for  subjective  satisfactions,  not  out  of  any  com- 
pulsion imposed  by  the  physical  world.  It  is  for  this  reason 
that  psychology  draws  many  of  its  best  illustrations  from  the 
sphere  of  art.  If  we  find  a  general  principle  running  through 
art,  we  are  led  at  once  to  the  conclusion  that  there  is  a  cor- 
responding tendency  in  human  nature.  Certain  simple  illus- 
trations may  be  offered.  Thus,  there  is  a  certain  proportion 
between  the  long  and  short  sides  of  rectangular  figures  which 
is  pleasant  to  look  at.  The  proportion  can  be  expressed  mathe- 
matically by  saying  that  the  long  side  is  to  the  short  side  as 

325 


326  PSYCHOLOGY 

the  sum  of  both  is  to  the  long  side.    If  we  examine  those 
objects  \\liu  h  have  been  freely  constructed  without  special 
external  limitations.  uc  shall  find  that  a  great  many  of  them 
take-  on   this   proportion.     For  example-,  when   an  < 
series  of  measurements  was  made  of  the  two  legs  of  orna- 
mental cross.  they  maintain  the  propor- 
tion descril>ed.    This  •                have  no  objective  explai; 
and  must  have  lx-cii  dictated  by  human  subjective  attitudes. 

Freedom  in  art.     A.  tin,    certain   of    the    types  of   s 
mctry    in   architecture  are   efforts   to   meet   the  demands  of 
human  nature  rather  than  of  external  requirements.    If  we 

:;ne  the  forms  of  architecture  which  grew  up  in  a  p< 
when  men  \u  :  nal  environment 

concerned,  to  construct  buildings  of  any  size  which  they 
pleased,  rather  than  to  fit  their  constructions  to  the  require- 
ments of  a  city  building  lot,  we  find  that  the  size  and  form 
of  these  free  buildings  assumed  certain  general  proportions 
which  were  determined,  not  by  the  external  conditions,  but 
rather  by  the  demands  of  taste.  Indeed,  one  of  the  funda- 
mental distinctions  between  ancient  and  modern  architecture 
is  a  distinction  which  can  be  described  by  saying  that  the 
early  builders  followed  their  sense  of  proportion,  while  modern 
builders  follow  certain  definite  laws  of  mechanical  construc- 
tion. A  Gothic  cathedral  of  the  pure  type  very  commonly 
exhibits  certain  irregularities  in  the  position  and  size  of  its 
columns,  which  yield  in  the  mass  an  impression  of  solidity 
and  symmetry  that  could  not  be  obtained  if  every  part  of  the 
building  had  been  made  to  conform  to  exact  mechanical  rules. 
A  modern  building  is  constructed  with  definite  reference  to 
mathematical  regularity  of  dimensions  and  with  reference 
also  to  the  strain  which  is  to  be  placed  upon  every  given 
part  of  its  floors  and  walls.  There  is  little  tendency  to 
use  the  material  freely ;  there  is  much  greater  tendency  to  do 
only  what  is  necessary  to  meet  the  simpler  mechanical  re- 
quirements. A  column  made  of  steel  is  designed  to  support 


APPLICATIONS  OF  PSYCHOLOGY  327 

a  certain  weight,  and  the  size  of  the  column  used  in  a  build- 
ing is  usually  determined  by  the  weight  which  it  is  to  carry 
rather  than  by  its  appearance.  The  immediate  effect  of  at- 
tention to  such  mechanical  requirements  is  that  we  have 
many  ugly  buildings. 

Architectural  harmony  analogous  to  musical  rhythm  and 
harmony.  There  are  many  indications  in  the  earlier,  freer 
architecture  of  the  Greeks  that  they  followed  certain  broad 
principles  of  rhythmical  proportion  which  correspond  so  closely 
to  what  we  find  to  be  the  principles  of  musical  rhythm  and 
harmony,  that  there  is  a  suggestion  of  a  common  type  of 
human  organization  lying  back  of  both  spheres  of  art.  It  has 
been  pointed  out,  for  example,  that  the  height  of  a  Greek 
column  is  an  exact  multiple  of  its  diameter.  Furthermore,  the 
space  between  the  columns  always  stands  in  definite  relation 
to  the  diameter  of  the  column.  In  details  of  construction 
also,  as,  for  example,  in  the  various  portions  of  the  decora- 
tions in  the  Ionic  capital,  the  parts  are  related  to  each  other 
in  definite  unit  ratios,  so  that  a  constructive  symmetry  runs 
through  the  whole  and  gives  the  observer  a  feeling  of  com- 
posure and  unity. 

Literary  art  and  psychological  laws.  What  is  true  of 
architecture  is  much  more  obvious  with  reference  to  literary 
art.  It  is  clear  that  the  laws  of  literary  composition  must  be 
laws  of  human  nature,  and  the  great  artists  have  unquestion- 
ably followed  with  sufficient  closeness  the  demands  of  human 
nature  to  leave  their  works  as  standards  for  future  develop- 
ment and  as  expressions  of  the  direction  in  which  all  individual 
development  must  tend. 

Prose  rhythms  as  related  to  the  personal  organization  of 
writers.  Some  purely  formal  indications  of  the  complete- 
ness with  which  great  literature  conforms  to  the  demands  of 
human  nature  may  be  found  in  the  fact  that  there  are  even 
in  prose  compositions  certain  typical  rhythms  which  give  to 
these  compositions  a  regular  symmetry  of  character,  which 


Vs 

undoubtedly  constitutes  one  of  its  cha  is  a  striking 

example  of  t  iiat  art  may  outstrip  science,  tli.it 

tiy  complete  theoretical  accou 

the  prose  rhythms  of  tin-  U-st  \\ri:  :dently  those 

have  contributed  the  great  works  to  literature  have  succeeded 
in  utilizing  the  language  in  which  they  wrote  in  such  a  way 
as  to  express  an  internal  organization  of  their  own  which  was 
altogether  approp  'heir  theme  and  to  the  vernacular, 

and  this  they  have  done  spontaneously  and  very  often  without 
complete  theoret  ^nition  of  what  they  were  <1- 

When  the  student  of  such  prose  arrives  by  laborious  ana 
at  some  knowledge  of  the  rhythms  which  it  contains,  he  is 
not  creating  rhythms,  but  rather  rediscovering  by  the  tardy 
methods  of  scientific   analysis  a  formula   which   has   ! 
achieved  by  the  great  writer  through  intuition. 

Verse  another  example  of  the  same  type.    If   the    f« 
of  prose  composition  have  exhibited  "complexity  of  structure, 
together  with  a  fundamental  regularity  of  form,  i1 
more  true  of  verse  that  its  masters  have  never  followed  rigid 
mechanical  principles  in  their  work.  And  yet  they  have  ade- 
quately met  the  demands  of  human  nature.   Their  conformity 
to  a  limited  group  of  principles  is  seen  in  their  adherer 
certain  regular  forms  which  are  sufficiently  obvious  to  be  imi- 
tated in  gross  outline  by  writers  of  less  taste  and  power ;  hut 
the  full  and  effective  use  of  verse  forms  has  always  inv- 
a  certain  freedom  of  manipulation  which  has  defied  any  com- 
plete theoretical  account.    Psychology  must  frankly  admit  in 
such  a  case  as  this  that  it  follows  in  the  steps  of  a  complete 
adaptation,  very  far  behind  the  adaptation  itself.    Neverthe- 
less, the  psychological  problem  is  clear,  and  a  general  sug- 
gestion as  to  the  explanation  of  these  facts  may  be  found  in 
what  has  been  said  in  an  earlier  connection  regarding  the 
nature  of  rhythm.    Whatever  the  unknown  details,  rhythm 
is  certainly  in  keeping  with  the  natural  demands  of  the  nerv- 
ous system.    Because  the  nervous  system  is  rhythmical  in  a 


APPLICATIONS  OF  PSYCHOLOGY  329 

complex  way  in  its  own  functioning,  it  responds  favorably  to 
rhythms  of  impressions. 

Literary  content  controlled  by  psychological  laws.  It  is 
not  alone  in  its  form  that  literature  expresses  the  demands 
of  human  nature  ;  the  content  may  be  studied  from  the  same 
point  of  view.  It  is  possible  by  a  psychological  analysis  to 
throw  much  light  on  one  case  which  has  been  the  subject  of 
much  mystical  speculation.  It  has  often  been  suggested  that 
human  intuitions  and  vague  feelings  frequently  bring  us  much 
nearer  to  that  which  afterward  proves  to  be  the  truth  than  do 
our  most  elaborate  processes  of  reasoning.  The  poet  has 
always  claimed  for  himself  a  higher  position  than  he  would 
allow  to  the  scientist  who  is  bound  by  the  demands  of  rigid 
evidence.  We  often  speak  of  the  insights  of  the  artist,  and 
mean  by  this  phrase  that  the  artist  sees  beyond  the  ordinary 
facts  of  definite  observation  and  clear  vision  to  ranges  of  facts 
which  are  of  importance,  but  are  not  open  to  our  inspection. 

Feeling  and  intuition.  What  has  been  said  in  an  earlier 
chapter  with  regard  to  the  nature  of  feelings  will  be  of  some 
assistance  in  clearing  up  the  paradox  which  here  -appears. 
When  explaining  the  feelings,  we  discovered  that  whatever 
runs  counter  to  the  organized  nature  of  the  individual  will 
arouse  a  disagreeable  feeling.  Whatever  is  in  fundamental 
agreement  with  nature  will  give  pleasure.  If  now  the  ex- 
periences of  life  are  in  subtle  agreement  or  disagreement 
with  the  organization  of  the  individual,  it  does  not  follow 
that  the  individual  will  become  clearly  conscious  of  this  fact 
in  ideational  or  abstract  terms,  and  yet  he  may  be  vividly 
aware  of  the  disagreeable  feeling  imposed  upon  him  by  a 
certain  experience.  For  example,  as  we  have  seen  in  earlier 
discussions,  the  organization  of  an  animal  may  be  such  that 
certain  color  stimulations  are  fundamentally  opposed  to  its 
natural  organization.  Feeling  is,  therefore,  a  kind  of  spon- 
taneous adjustment  with  a  practical  value  which  often  sur- 
passes that  of  incomplete  theoretical  judgments.  Feeling 


330  OLOGY 

be  relied  upon  in  those  situations  where  the  organ  iza 
le  enough  or  the  response  direct  enough  to 
give  an  unbiased  reflection  of  the  individual's  relation  to  the 
impression.  On  the  other  hand,  when  life  becomes  complex, 
as  it  is  in  human  beings,  native  instincts  and  native  feelings 
are  often  overlaid  by  a  series  of  developments  so  indirect 
that  there  comes  to  be  a  certain  rivalry  between  the  author- 
ity of  feeling  and  the  authority  of  abstract  knowledge. 
There  can  be  no  doubt,  for  example,  that  the  social  selec- 
tions by  which  one  determines  who  shall  be  his  friends  are 
dependent  in  large  measure  on  intuitions,  but  one  does  not 
need  to  be  very  old  or  worldly-wise  to  recognize  that  the 
complexities  of  social  life  are  such  that  the  instinctive  feel- 
ings which  we  have  in  making  the  acquaintance  of  new 
individuals  are  not  always  safe  guides  in  the  development 
of  social  relations.  What  is  true  of  social  relations  is  true, 
undoubtedly,  of  artistic  intuitions  and  of  larger  intuitions  of 
universal  truth.  It  is  quite  impossible  to  persuade  one  who 
regards  a  line  of  poetry  as  beautiful  that  it  is  not  beautiful 
because  it  violates  some  rigid  law  of  versification.  It  is 
quite  impossible  to  convince  one  who  enjoys  a  certain  pic- 
ture that  the  picture  is  deficient  because  it  does  not  comply 
with  certain  canons  of  a  certain  school  of  art.  On  the  other 
hand,  it  is  frequently  possible,  by  a  series  of  educative  con- 
tacts with  better  artistic  and  literary  forms,  gradual! 
modify  an  individual's  organized  feelings  so  that  he  shall 
completely  change  the  character  of  his  judgment.  Intuition 
is,  therefore,  not  a  separate  and  distinct  faculty  of  life ;  it  is 
rather  an  expression  of  that  immediate  form  of  recognition 
of  congruity  or  incongruity  which  characterizes  the  feelings 
as  distinguished  from  abstract  theoretical  knowledge.  The 
statement  made  by  the  poet  may  express  an  attitude  which 
is  true  to  the  facts  and  will  later  be  fully  explicated  by  the 
clearer  ideational  view  cultivated  in  abstract  thought.  There 
is  no  ultimate  opposition  between  feeling  and  thought. 


APPLICATIONS  OF  PSYCHOLOGY  331 

Many  of  the  social  sciences  predominantly  objective  in 
their  methods.  When  we  turn  from  the  discussion  of  art 
and  feeling  to  certain  more  practical  spheres  of  investigation 
involving  human  nature,  —  namely,  those  taken  up  in  the 
social  sciences  and  anthropology,  —  we  find  that  the  study  of 
psychology  is  very  direct  in  its  application  to  these  spheres 
of  study  and  explanation.  It  has  not  always  been  fully 
recognized  that  psychology  has  a  relation  to  the  social 
sciences.  Certain  schools  of  social  scientists  have  treated 
the  institutions  which  they  study  merely  as  objective  facts. 
To  show  this,  we  may  take  as  an  illustration  one  of  the 
oldest  of  social  sciences ;  namely,  the  science  which  deals 
with  language.  Language  is  a  product  of  human  activity 
which  has  a  sufficiently  independent  existence  to  make  it 
an  easy  subject  for  examination  and  analysis.  To  trace  the 
history  of  a  word  is  to  undertake  an  investigation  which 
calls  for  little  reference  to  the  individuals  who  may  have 
made  use  of  this  word.  In  like  fashion,  the  study  of  a  sys- 
tem of  sounds  and  written  symbols  may  result  in  the  dis- 
covery of  certain  regularities  and  laws  of  phonetics  without 
reference  to  the  human  beings  who  used  this  language  and 
who  were  the  ultimate  sources  of  regularities  in  the  lan- 
guage itself.  The  same  historical  and  objective  methods 
have  been  applied  to  the  study  of  other  institutions.  For 
example,  religious  systems  have  been  described  and  their 
uniformities  and  divergencies  have  been  ascertained  without 
more  than  a  passing  reference  to  the  individuals  who 
developed  these  systems  or  adhered  to  them. 

Introspective  psychology  and  its  limited  support  to  social 
science.  The  tendency  to  confine  attention  to  an  objective 
study  of  human  institutions  has  been  strengthened  by  the 
attitude  which  for  a  long  time  prevailed  in  psychology,  when 
the  chief  method  of  investigation  was  the  introspective 
method,  according  to  which  the  individual  attempted  to  dis- 
cover the  laws  of  mental  life  through  an  examination  of 


332  1>\<  HOLOGY 

his  own  immediate  experience,  and  with  very  little  refer- 
ence to  the  modifying  influence  of  hi  Ixrings  or  the 
secondary  factors  of  his  environment.  When  the  problem 
of  psychology  is  more  broadh  .ed,  so  that  it  is  seen 

th.it  the  i  h.i:  human  mental  life  can  be  defined 

by  a  more  elaborate  study  of  numerous  examples  and 
tcrnal   relations,   the   spheres   of    institutional   study  and  of 
iiolo^ical   investigation  are  gradually  brought  nearer  to 
each  other. 

Interrelation  of  psychology  and  social  science.     In 
course  of   recent   psychological   study,   much   valuable    illus- 
trative material  has  l>een  borrowed  from  the  sciences  which 
deal  with  language  and  from  anthropology.     Psychology  has 
thus  expanded   under   the    influence  of  the   new  bod 
material  which  has  been  adopted  into  it.    The  methods  of 
psychology    have    Ixvoine    more    objective,    and   the   re 
of  individual  inti  :>  have  been  broadened.     On  the 

other  hand,  the  scientific  study  of  all  other  human  beings 
must  be  based  upon  one's  own  personal  experiences.  One 
naturally  thinks  of  primitive  man  in  terms  of  his  own  men- 
tal experiences.  If  there  is  no  scientific  study  of  the  matter, 
the  student  is  likely  to  carry  over  analogies  and  apply  them 
to  cases  where  they  do  not  illustrate,  but  rather  obs 
the  truth.  Thus,  as  has  been  pointed  out  by  a  recent  writer, 
there  is  a  widespread  tendency  to  describe  the  mental  abili- 
ties of  savages  by  means  of  a  succession  of  negatives.  Savages 
do  not  count,  they  do  not  have  a  full  series  of  color  te: 
the\-  do  not  paint  pictures  or  write.  All  these  negatives 
are  mere  expressions  of  the  natural  tendency  to  accept  our- 
selves as  standards.  We  should  become  sufficiently  imper- 
sonal in  our  studies  to  recognize  that  savages  probably  have 
a  nicety  of  space  perception  which  is  very  much  gr« 
than  ours.  They  may  not  select  color  qualities  and  name 
them,  but  for  the  finer  grades  of  variation  in  plant  and 
animal  life  as  indicated  by  color  they  have  the  most  highly 


APPLICATIONS  OF  PSYCHOLOGY  333 

developed  discrimination.  Not  only  the  savage,  but  even 
our  contemporaries  in  different  civilizations  from  our  own, 
are  exceedingly  baffling  unless  we  make  some  study  of  their 
types  of  mental  development.  The  institutions  of  Tibet, 
China,  and  Japan  are  obviously  different  from  our  own,  but 
the  character  of  the  mental  processes  back  of  these  insti- 
tutions has  been  little  thought  of  and  little  studied.  The 
careful  scientific  study  of  the  mental  characteristics  of 
different  peoples  is  one  of  the  most  promising  lines  of 
extension  of  psychological  study. 

Human  evolution  psychical.  So  intimately  is  social 
organization  bound  up  with  the  mental  development  of  the 
individual  that  we  are  justified  in  the  statement  that  psychol- 
ogy is  the  basis  of  any  explanatory  account  of  social  insti- 
tutions. There  is  one  particular  anthropological  problem 
where  the.  significance  of  psychological  analysis  can  be 
made  very  clear.  Anthropology  has  never  succeeded  in 
finding  structural  modifications  in  the  human  body  which 
would  at  all  adequately  account  for  the  great  superiority  of 
highly  developed  races  over  the  more  primitive  tribes  of 
mankind.  Even  the  explanation  of  the  crucial  development 
by  which  man  became  differentiated  from  the  animals  is 
one  of  the  obscure  chapters  in  anthropology.  It  cannot  be 
denied  that  the  explanation  of  all  these  matters  must  be 
sought  in  terms  which  refer  to  the  development  of  intelli- 
gence, especially  the  development  of  language  and  the  use 
of  tools,  as  has  been  indicated  in  an  earlier  discussion. 
The  problem  of  anthropology  is  thus  distinguished  from 
the  purely  biological  problem,  where  intelligence  is  not  rec- 
ognized as  playing  any  part.  How  could  a  certain  group  of 
animals  suddenly  break  away  from  the  established  type  of 
evolution  in  which  changes  in  structures  played  a  large  part 
and  become  animals  characterized  by  intelligence,  meet- 
ing the  emergencies  of  their  lives  by  a  mental  adaptation 
of  themselves  rather  than  by  a  purely  physical  adaptation  ? 


334  >GY 

Why  should  this  group  of  animals  turn  to  the  develop. 
iiu-nt  of  all  the  instruments  of  civilization  ?    The  problem 
stated  in  this  form  becomes  a  problem  of  functional 
velopment  rather  than  a  problem  of  physical  development. 
This  animal  must  have  been  driven  at  some  time  into  a 
situation  where   his   development   turned   upon  his  ability 
to  adopt  a  new  type  of  behavior  and  a  new  mode  of 
There  can  be  no  doubt  that  the  scientific  explanati« 
the  breach   between   man  and  the  animals  depends  upon 
the  recognition  of  a  transformation  in  the  mode  of  behavior 
and  mental  life  rather  than  upon  any  fact  of  gross  bodily 
change.    Put  in  another  way,  the  statement  may  be  i 
that  we  need   no  animal    form  to  serve   as  a  connc 
link  between  man  and  the  animals.    The  common  struc- 
ture, the  common  physical  needs  of  man  and  the  animals, 
are  now  made  out  so  fully  that  what  science  requires  is  an 
explanation  of  the  gap,  rather  than  the  link,  between  man 
and  the  animals.    The  doctrine  of  biological  evolution  has 
successfully  established  the  principle  of  continuity.     It  re- 
mains for  genetic  psychology  to  explain  the  discontinuity 
which  appears  when  intelligence  begins  to  dominate,  when 
sensory-motor  adjustments  of  the  reflex  and  instinctive  type 
give  place  to  habit  acquired  through  individual  intelligence 
and  to  the  more  elaborate  forms  of  thought. 

A  hypothesis  to  explain  the  break  between  man  and 
the  animals.  An  interesting  hypothesis  has  been  suggested 
which  illustrates  the  possibility  of  assuming  a  distinctly  func- 
tional attitude  toward  the  question  of  the  evolution  of  man. 
This  hypothesis  suggests  that  the  gradual  changes  in  physi- 
cal organization  which  characterize  all  of  the  different  species 
of  primates  lead  up  to  the  appearance  of  man  only  because 
at  one  time  a  number  of  these  primates  were  forced,  prob- 
ably by  the  emergencies  of  a  glacial  climate  in  certain  quar- 
ters in  which  they  were  confined,  to  adopt  a  mode  of  lif 
which  brought  them  down  out  of  the  trees  and  forced  uj 


APPLICATIONS  OF  PSYCHOLOGY  335 

them  types  of  activity  which  led  to  their  construction  of  arti- 
ficial shelters  and  to  the  preparation  of  forms  of  food  which 
had  not  been  previously  utilized  by  their  race.  The  change 
here  assumed  depends  on  the  rise  of  a  powerful  motive  for 
new  ways  of  behavior.  Whatever  change  there  was  in  the 
individual  consisted  in  the  opening  of  new  paths  in  the  cen- 
tral nervous  system.  This  change  in  the  trend  of  evolution, 
when  once  it  appeared,  was  so  important  that  the  further 
history  of  the  group  of  animals  which  succeeded  in  effecting 
it  was  in  the  direction  of  adaptation  through  intelligence 
and  nervous  organization  rather  than  through  gross  changes 
in  bodily  structures.  Whether  we  give  any  credence  to  this 
hypothesis  or  not,  it  expresses  admirably  the  functional  atti- 
tude in  the  explanation  of  human  evolution.  It  expresses 
clearly  the  fact  that  the  nature  of  mental  and  functional 
adaptation  is  the  significant  problem  for  anthropology  rather 
than  the  mere  search  for  changes  in  physical  organization ; 
it  gives  to  anthropology  a  definite  impetus  in  the  direction 
of  the  study  of  mental  organization,  as  distinguished  from 
the  study  of  bodily  structures. 

Spencer's  application  of  psychology  to  sociology.  Another 
illustration  from  a  later  period  of  human  development  which 
will  also  emphasize  the  significance  of  psychological  study 
for  anthropology  is  to  be  found  in  Spencer's  discussions,  in 
which  he  calls  attention  to  the  fact  that  the  growth  of  civili- 
zation depends  upon  the  broadening  of  the  individual's  men- 
tal horizon.  He  points  out  the  fact  that  the  savage  who  had 
interest  in  only  a  small  range  of  territory  and  the  present 
enjoyment  of  objects  immediately  about  him  gradually  de- 
veloped into  the  semicivilized  man  interested  in  a  larger 
territory,  a  larger  number  of  individuals,  and  a  longer  period 
of  time.  The  planting  of  crops  and  the  erection  of  perma- 
nent buildings  cannot  be  explained  by  objective  conditions 
as  has  sometimes  been  attempted  in  the  history  of  civiliza- 
tion. There  must  be  ideas  and  imaginations  in  the  mind  of 


336  PSYCHOLc 

some  active  being  before  the  future  can  be  anticipated  suffi- 
ciently to  lead  to  the  planting  of  the  crop  or  the  erection 
of  the  building. 

Relation  of  educational  practices  to  scientific  psychology. 
Conspicuous  among  the  social  institutions  to  which  psy 
ogy  may  be  applied  in  a  direct  and  pr  >.  the 

institution  of  education.    Here  again  is  a  type  of  adapt. 
which  has  grown  in  an  unscientific  way  to  a  high  degree  of 
maturity.    This  statement  implies  no  disposition  to  den 

of  many  of  the  practices  of  educational  institu- 
tions. They  may  be  effective  without  being  scientific.  They 
are  the  outgrowth  of  a  need  which  has  been  felt  by  < 
^eiK-ration,  and  the  educational  institutions  which  have  been 
loped  in  response  to  this  general  need  have  been  refined 
and  modified  in  view  of  experience,  until  finally  they  express 
with  a  high  degree  of  perfection  the  final  judgment  of  many 
,mnerations  upon  important  questions  connected  with  the 
training  of  the  younger  generation.  Yet  there  are  obvious 
reasons  why  these  historical  institutions  should  be  reexam- 
ined.  Some  of  the  uncritical  methods  of  education  are  found 
to  be  wasteful ;  again,  the  educational  practices  of  diff< 
peoples  or  different  sections  of  the  same  nation  are  found 
to  be  inharmonious.  There  arises,  therefore,  a  demand  for 
a  careful  analysis  of  the  whole  situation  and  the  establish- 
ment of  those  practices  which  scientific  analysis  can  ju 
It  is  true  that  many  hold  the  same  attitude  with  regard  to 
education  that  they  do  with  regard  to  art ;  namely,  that  it  is 
safer  to  rely  upon  the  intuitions  of  human  feeling  than  to 
attempt  to  formulate  an  abstract  system  of  education.  Those 
who  adopt  this  position  with  regard  to  the  advantages  of  in- 
tuition in  education  have  justification  for  their  position,  in 
so  far  as  educational  practices  are  refined  to  a  point  beyond 
our  knowledge  of  the  laws  of  human  development.  The 
most  acceptable  plea  for  a  scientific  study  of  education  which 
could  be  presented  to  such  persons  would  consist  in  a  plea 


APPLICATIONS  OF  PSYCHOLOGY  337 

for  a  more  complete  knowledge  of  the  same  sort  which  they 
have  in  their  native  intuitions.  It  might  be  said,  for  exam- 
ple, that  the  study  of  educational  methods  involves  nothing 
more  than  the  bringing  together  of  the  individual  experi- 
ences and  practices  of  all  those  who  have  become  skilled  in 
educational  practice.  A  comparative  study  would  help  to 
eliminate  those  individual  intuitions  which  are  incorrect, 
because  they  are  based  upon  too  narrow  experience. 

Psychology  as  a  preparation  for  the  intelligent  diagnosis 
of  particular  situations  which  arise  in  educational  practice. 
The  final  examination  of  educational  practices  must  go  much 
further,  however,  than  is  implied  in  this  appeal  for  a  com- 
parative study  of  intuitions.  Attention  must  be  called  to  the 
fact  that  much  of  our  devotion  to  traditional  educational  prac- 
tices is  nothing  more  or  less  than  a  deliberate  confession  of 
our  ignorance  of  the  way  in  which  the  human  mind  develops. 
When  a  teacher  is  confronted  by  children  who  are  unable 
to  comprehend  the  lesson  which  has  been  set,  he  very  com- 
monly can  make  no  analysis  of  the  child's  difficulty.  He 
then  covers  up  his  ignorance  of  the  step  which  should  be 
taken  by  requiring  repeated  efforts  on  the  child's  part,  until 
in  some  unknown  fashion  the  difficulties  are  mastered.  It 
does  not  follow  that  the  particular  difficulty  encountered  in 
any  given  case  would  have  been  recognizable  if  the  teacher 
had  made  a  study  of  human  development  in  other  individ- 
uals, but  the  probability  that  the  trained  teacher  will  be  able 
to  make  a  scientific  analysis  of  the  difficult  situation  at  hand 
is  increased  if  he  becomes  acquainted  with  the  principles 
and  results  of  scientific  psychology.  Intuition  should  there- 
fore be  supplemented  by  as  full  an  account  as  can  be  given 
of  the  way  in  which  mental  processes  go  on  and  of  the 
methods  by  which  these  processes  may  be  examined. 

A  few  illustrations  may  serve  to  make  clear  the  place 
and  value  of  the  psychological  study  of  educational  prob- 
lems. First,  a  number  of  investigations  have  recently  been 


338 


IK'LOGY 


undertaken  with  a  view  to  defining  in  detail  the  course  of 
development  of  certain  h  i-roadly  stated,  the  conclu- 

sions of  A  that  no  habit  develops  in  all  of 

uniform  rate.    There  is  at  the  outset  a  p< 
during  which  improvement  is  relatively  very  rapid  ;  this  is 
followed   by  a  period  of  slow   development,   which   in  turn 
gives  way  to  successive  periods  of  rapid  and  slow  growth. 


140 

130 

•  ia° 

•3110 


16 


» 


JU 


•MMf  .V-I.'N  I.inf  7.M.V 


FIG.  60.   Curves  for  sending  and  receiving  telegraphic  messages 

The  curve  is  published  by  Bryan  and  Harter.   The  number  of  weeks  of  practice  is 

indicated  in  the  upper  pan  of  the  figure.    The  number  of  letter*  which  can  be 

received  and  sent  in  a  minute  is  represented  in  the  vertical.   The  figure  is  divided 

by  a  horizontal  line,  which  shows  the  standard  rate 

A  curve  illustrating  the  process  of  learning.  One  of  the 
earliest  investigations  of  the  way  in  which  an  individual 
learns  may  be  described  in  detail.  This  investigation 
undertaken  to  determine  the  rate  at  which  a  learner  acquired 
the  ability  to  send  and  receive  telegraphic  messages.  The 
selection  of  this  particular  case  for  the  test  was  due  to  the 
ease  with  which  measurements  of  proficiency  could  be  made 
and  to  the  maturity  of  the  persons  investigated,  which  made 
it  easy  to  subject  them  to  a  series  of  tests.  In  Fig.  60  the 


APPLICATIONS  OF  PSYCHOLOGY  339 

results  of  the  investigation  are  represented  in  a  curve.  Along 
the  top  of  the  figure  are  marked  the  successive  weeks  during 
which  the  investigation  was  carried  on ;  along  the  vertical 
line  at  the  left  the  number  of  letters  which  could  be  received 
or  sent  in  a  minute.  A  single  point  on  the  curve  repre- 
sents, accordingly,  both  a  stage  in  the  practice  series  and 
the  number  of  letters  which  could  be  received  or  sent  dur- 
ing a  minute  at  this  stage  of  development.  The  curves  taken 
in  their  entirety  represent  the  gradual  increase  in  the  ability 
of  the  subject.  It  will  be  noticed,  in  the  first  place,  that  the 
improvement  in  sending  and  in  receiving  messages  followed 
an  entirely  different  course,  both  with  reference  to  rate  of 
improvement  and  also  with  reference  to  the  successive  stages 
of  development.  Concentrating  attention  for  the  moment 
upon  the  curve  which  records  improvement  in  receiving, 
we  see  that  the  development  is  at  first  rapid  and  then  for  a 
long  time  practically  stationary.  After  the  stationary  period, 
or  plateau  as  the  authors  called  this  part  of  the  figure,  came 
a  second  rapid  rise  in  the  curve. 

Significance  of  a  "plateau"  in  development.  In  Fig.  61  - 
a  second  curve  of  the  same  sort  is  shown,  which  makes  it 
possible  to  explain  the  pause,  or  plateau,  in  development. 
The  lowest  curve  in  this  second  diagram  represents  the 
development  of  proficiency  in  recognizing  isolated  letters. 
The  second  curve  represents  the  development  of  proficiency 
in  receiving  isolated  words  which  did  not  unite  into  sentences, 
and  the  full  curve  represents,  as  before,  the  development  of 
efficiency  in  receiving  words  which  constituted  sentences.  It 
will  be  noticed  that  the  ability  to  receive  isolated  letters  and 
the  ability  to  receive  isolated  words  developed  rapidly  for  a 
time,  until  they  reached  their  maxima,  and  then  they  con- 
tinued indefinitely  at  the  same  level.  This  level  is  so  related 
to  the  plateau  in  the  total  curve  that  the  plateau  can  safely 
be  defined  as  the  period  during  which  the  subject  was  in 
the  word  stage  of  development,  rather  than  in  the  sentence 


340 


PSYCHOLOGY 


stage.    Only  after  the  ability  t«>  receive  single  words  had 
been  thoroughly  matured  was  a  new  type  of  develop: 
possible. 

Other  examples  of  the  same  type  of  development 
an  analysis  as  this  of  a  case  of  learning  shows  much  with 
regard  to  the  psychological  character  of  the  process.    It  also 


106 
W 


:: 


i ..,.  .<  n  MAM 


Slowtt  Main  I.inf  Rale 


''•i.    Analysis  of  the  receiving  curve 
This  figure  is  similar  to  Fig.  60.   For  further  discussion,  see  text  (p.  339) 

suggests  the  possibility  of  including  the  process  of  mental 
lopment  under  certain  broad  laws  of  development. 
There  are  many  analogous  cases  in  general  evolution  where 
it  has  been  noted  again  and  again  that  periods  of  rapid 
lopment  are  followed  by  long  periods  of  assimilation. 
It  is  a  well-known  fact  of  bodily  growth  that  the  enl 
ment  of  the  body  is  most  marked  at  certain  periods  in  the 
year  and  at  certain  well-defined  periods  in  the  child's  life. 
After  one  of  the  sudden  enlargements  of  the  body,  there 
follows  a  period  of  gradual  assimilation  of  the  new  develop- 
ments, during  which  the  body  remains  stationary  in  its  size 


APPLICATIONS  OF  PSYCHOLOGY  341 

for  a  considerable  time.  The  facts  of  organic  evolution  on 
a  larger  scale  are  of  the  same  type.  During  certain  periods 
the  animal  kingdom  has  advanced  rapidly  by  the  production 
of  new  forms,  after  which  long  stationary  periods  appear, 
during  which  these  new  forms  are  more  completely  adjusted 
to  their  environment  without  being  in  any  important  sense 
modified.  Such  statements  as  these  make  clear  the  distinc- 
tion between  assimilation  and  acquisition  in  both  the  physical 
and  mental  worlds. 

The  fact  that  certain  forms  of  mental  development  are 
periodic  rather  than  continuous  is  illustrated  in  many  cases 
where  quantitative  tests  have  not  been  made.  It  has  often 
been  casually  observed  that  a  mature  subject  learns  a  foreign 
language,  not  with  uniform  rapidity,  but  in  a  way  analogous 
to  that  shown  in  the  curves  given  above.  At  first  there  is 
rapid  acquisition  of  the  words  and  grammatical  constructions 
of  the  new  language,  but  after  a  time  the  power  to  acquire 
new  phases  of  the  language  seems  to  be  brought  to  a  stand- 
still, and  the  period  of  discouragement  which  follows  is 
often  felt  by  the  learner  to  be  a  period  of  no  development, 
while  in  reality  it  is  a  period  of  assimilation  and  preparation 
for  the  later  stages  of  growth.  When  the  later  development 
into  the  full  use  of  the  language  comes,  it  is  so  sudden  and 
striking  in  its  character  that  it  has  been  noted  time  and  time 
again  as  a  period  of  astonishing  mental  achievement. 

Motor  habits  intermittent.  Many  habits  of  action  exhibit 
the  same  type  of  intermittent  development.  If  one  learns 
some  manual  art,  he  finds  that  the  incoordinations  with 
which  he  begins  are  only  gradually  eliminated  ;  but  finally  he 
learns  the  combination  which  is  advantageous,  and  from  that 
point  on  the  improvement  seems  for  a  time  to  be  very  rapid. 
It  is  sometimes  advantageous  in  a  course  of  training  to  give 
up  practice  for  a  time  in  order  that  the  various  elements  of 
the  coordination  may  have  an  opportunity  to  readjust  them- 
selves and  in  order  that  the  new  efforts  at  development  may 


34- 

begin  at  a  new  level.    1'rofcssor  James  has  made  the  striking 

:  k  that  we  Irani  to  skate  during  the  summer  and  to  swim 
during  the  winter.    The  significance  of  this  observation  is 
that  it  recognizes  the  intermittent  character  of  the  develop- 
nient  t>f  habit  and  the  advantage  of  a  period  of  assinul. 
sometimt  <>f  a  period  of  complete  cessation  of  the 

activity  in  question. 

School  training  in  its  relation  to  the  stage  of  development 
attained  by  the  mind.  From  the  point  of  view  of  practical 
education,  it  is  obvious  that  the  types  of  training  which 
should  be  given  at  the  different  periods  in  mental  develop- 
ment are  by  no  means  the  same.  During  a  period  of  rapid 
acquirement  of  new  material,  one  sort  of  training  is  appro- 
priate ;  during  a  period  of  delayed  assimilation,  that  form 
of  training  is  most  appropriate  which  is  technically  known 
in  the  schools  as  drill.  The  ordinary  unscientific  education 
has  recognized  vaguely  that  there  is  a  difference  in  the 
kinds  of  training  demanded  at  different  times ;  but  the  ad- 
justment of  these  different  types  of  training  to  the  demands 
of  individual  mental  development  is  an  intricate  problem 
which  can  be  worked  out  satisfactorily  only  when  a  careful 
study  is  made  of  educational  practice. 

Significance  of  scientific  studies  often  indirect.  The  value 
of  scientific  studies  of  habits  and  of  forms  of  training  is 
shown  by  such  considerations  as  the  foregoing.  It  also 
becomes  evident  that  such  studies  do  not  necessarily  change 
the  subjects  of  instruction  nor  even  the  general  methods 
established  by  tradition,  but  serve  rather  to  refine  our  knowl- 
edge of  the  process  of  mental  growth  and  make  it  possible 
for  us  to  deal  with  different  stages  of  the  educational  process 
with  much  greater  precision.  To  justify  scientific  investiga- 
tions which  seem  at  first  sight  remote  from  school  problems, 
it  may  be  well  to  point  out  that  the  solution  of  one  problem 
in  mental  development  makes  it  possible  to  attack  all  other 
problems  of  a  similar  kind  more  intelligently.  If  one  knows 


APPLICATIONS  OF  PSYCHOLOGY  343 

with  scientific  precision  that  a  period  of  assimilation  occurs 
in  one  case  of  mental  development,  he  will  be  better  pre- 
pared to  discover  and  understand  a  similar  period  in  other 
cases  where  it  may  be  less  easy  to  make  an  exact  scientific 
study.  For  example,  we  get  useful  suggestions  to  guide  us 
in  understanding  children's  reading  from  the  study  reported 
above  on  learning  telegraphy.  The  mastery  of  the  word  ele- 
ments in  ordinary  reading  is  similar  to  the  mastery  of  these 
same  elements  in  the  case  of  the  telegrapher. 

Expression  as  an  essential  condition  of  mental  life.  An- 
other concrete  illustration  of  educational  progress  may  be 
found  in  the  fact  that  there  is  a  general  disposition  among 
educators  to-day  to  recognize  the  importance  and  value  of 
expressive  activities  in  all  educational  processes.  The  early 
type  of  education  was  that  in  which  sensation  processes  were 
emphasized  almost  to  the  exclusion  of  activities.  Whether 
the  educational  practice  which  emphasized  impressions  can 
be  attributed  to  the  sensation  psychology  which  was  contem- 
porary with  it,  or  whether  the  sensation  psychology  was  the 
outgrowth  of  a  false  educational  theory,  is  a  question  which 
need  not  be  discussed  here.  Certain  it  is  that  the  limited 
view  of  mental  life  and  the  false  principle  of  education,  both 
of  which  emphasized  impressions  rather  than  expression, 
existed  for  a  long  period  side  by  side.  It  may  have  been 
the  growing  experience  of  practical  teachers  which  led  to 
the  discovery  of  the  fallacy  in  the  doctrine  that  mind  is 
conditioned  primarily  by  impressions.  It  may  have  been 
the  insight  of  scientific  students  which  gradually  made  it 
clear  that  human  activity  must  always  be  recognized  in  dis- 
cussing the  processes  of  mental  development ;  or  it  may  be 
that  the  two  lines  of  thought  and  practice  grew  up  together. 
In  any  case,  it  is  certain  that  a  transformation  of  educational 
practice  and  a  corresponding  transformation  of  psychology 
have  been  going  on  for  a  generation,  until  now  we  have 
in  both  an  emphasis  on  bodily  activities. 


344  <  HOLOGY 

Psychology  historically  a  part  of  philosophy.  Turning 
from  these  practical  apph<  iogy  to  educr 

r  us  to  discuss  one  of  the  applications  of  psy- 
chology which  has  always  been  recognized  in  the  historical 
development  of  this  s<  u-ncc ;  namely,  the  relation  of  psy- 
chology to  the  philosophical  disciplines.  Indeed,  it  may  be 
said  that  psychology  was  not  only  applied  to  the  problems 
of  philosophy  ;  it  was  originally  devoted  to  the  discussion  of 
these  problems  to  such  an  extent  that  it  was  regarded  as  an 
;ral  part  of  philosophy,  not  as  an  independent  science. 
Philosophy  deals  with  the  ultimate  nature  of  matter  and 
mind,  with  the  fundamental  laws  of  reality  and  the  relation 
of  reality  to  human  experience,  with  the  ultimate  nature  of 
truth,  goodness,  and  beauty.  There  have  been  times, 
example  during  the  medieval  period,  when  the  interest  in 
such  ultimate  problems  ran  so  high  that  there  was  litt! 
no  attention  given  to  the  special  problems  of  science.  The 
time  came,  however,  with  the  development  of  modern 
thought  when  these  larger  problems  receded  into  the  back- 
ground and  men  began  to  concern  themselves  with  the 
phenomena  in  the  world  rather  than  with  the  ultimate  reali- 
ties underlying  these  phenomena.  It  is  characteristic  of  the 
present  scientific  period  that  the  special  sciences  neglect 
to  as  great  an  extent  as  possible  the  questions  of  ultimate 
reality.  The  student  of  psychology  participates  to  a  very 
large  extent  in  this  tendency  to  omit  from  his  discussion 
questions  relating  to  the  ultimate  nature  of  mind.  He 
cannot,  however,  accept  as  final  this  aloofness  from  the 
broader  questions,  for  he  finds  himself,  more  than  his 
neighbor  who  deals  exclusively  with  the  natural  sciences, 
led  to  ultimate  problems. 

Relation  of  psychology  to  philosophy  closer  than  that  of 
any  of  the  special  sciences.  When,  for  example,  one  points 
out  that  a  sensation  is  related  to  a  fact  of  external  energy 
indirectly  through  the  organs  of  sense,  or  when  one  points 


APPLICATIONS  OF  PSYCHOLOGY  345 

out  that  space  is  a  definite  form  of  perception  on  the  one 
hand,  and  of  arrangement  of  objects  on  the  other,  the 
psychologist  is  driven  to  consider  the  relation  between  con- 
sciousness and  the  external  world  more  than  the  student  of 
the  other  particular  sciences.  The  student  of  natural  science 
uses  in  every  act  of  observation  the  relation  between  subjec- 
tive experience  and  the  physical  world ;  he  exercises  his 
mind  in  trying  to  know  the  world,  but  his  interests  are 
always  centered  on  the  relations  between  things,  never  on 
the  relation  between  things  and  consciousness.  Hence  the 
student  of  natural  science  easily  avoids  questions  relating 
to  the  ultimate  interaction  between  himself  and  the  physical 
world.  The  student  of  psychology  cannot  escape  these 
questions.  His  study  of  sensation  pushes  him  in  the  direc- 
tion of  an  examination  of  this  relation.  Furthermore,  when 
the  student  of  psychology  finds  that  the  construction  of 
concepts  is  an  elaborate  mental  activity,  he  is  immediately 
led  to  ask  not  only  what  are  the  laws  which  control  such 
conceptual  activity,  but  also  what  are  the  relations  of  scien- 
tific ideas  to  external  reality,  and  what  are  the  laws  which 
determine  the  validity  or  lack  of  validity  of  these  concepts. 
It  is  true  that  psychology  cannot  answer  all  of  these  ques- 
tions, and  it  has  been  our  purpose  in  the  foregoing  discus- 
sions to  adhere  as  closely  as  possible  to  the  sphere  of  strict 
psychological  inquiry,  postponing  these  ultimate  questions 
or  entirely  omitting  them.  It  is,  therefore,  very  appropriate 
that  we  should  call  attention  at  the  end  of  our  inquiry  to 
the  disciplines  which  deal  with  these  more  elaborate  inquiries, 
and  that  we  should  define  their  relation  to  psychology. 

Psychology  and  logic.  Logic  attempts  to  formulate  the 
laws  of  valid  reasoning.  To  be  sure,  logical  principles  can 
be  worked  out  without  the  aid  of  psychology,  through 
repeated  efforts  to  reason  correctly,  but  the  clear  definition 
of  logical  relations  waits  on  the  psychological  descriptions 
of  the  mental  processes  involved  in  reasoning. 


vt'  <  HOLOGY 

Psychology  and  aesthetics.    The  second  branch  "f  phi- 
losophy   is  aesthetics.     In   earlier  chapters   reference   has 
been  made  repeatedly  to  the  underlying  principles  v. 
control  the  recognition  of  symmetry  and  regularity  of  t 
and  it  was  pointed  out  in  earlier  paragraphs  of  this  chapter 
that  the  canons  of  architecture-  and  jwinting  are  directly  re- 
lated to  certain  fundamental  principles  of  hurrut:  •  and 
recognition.    Then:  still  remain  a  large  number  of  special 
analyses  and  special  considerations  which  must  be  worked 
out  in  order  to  define  fully  the  canons  of  taste  in  each  field 
of  art  and  the  general  canons  of  taste  which  underlr 
forms  of  art.     Such  considerations  of  the  canons  of  art 
constitute  a  legitimate  development  of  the  general  ps . 
logical  studies  which  have  been  suggested,  and  constitute 
the  special  discipline  of  aesthetics. 

Psychology  and  ethics.     When  we  turn  to  the  third  of 
the  special  philosophical  disciplines,  namely  et  find 

again  a  natural  relation  to  psychology,  though  it  is  perhaps 
proper  to  emphasize  here  more  than  in  the  case  of  logic  or 
aesthetics  the  independence  of  ethical  canons  from  purely 
subjective  organizations.  The  lightness  or  wrongness  of 
human  behavior  is  not  understood  primarily  through  an 
analysis  of  the  processes  of  behavior  themselves.  The 
Tightness  or  wrongness  of  behavior  depends  upon  certain 
broad  considerations  involving  the  social  interrelationships 
of  the  active  individual.  It  is  necessary,  therefore,  to  make 
a  study  of  the  extra-mental  or  social  relations  of  the  indi- 
vidual in  order  to  establish  the  canons  of  ethical  conduct. 
One  does  not  need  to  discuss  the  extra-mental  relations  to 
anything  like  the  same  extent  when  he  attempts  to  define 
the  laws  of  reasoning  in  logic  or  the  laws  of  appreciation 
in  aesthetics.  It  is  true  that  the  individual's  modes  of  be- 
havior, as  they  have  been  worked  out  in  the  course  of 
social  life,  come  to  embody  much  of  the  social  interrelation- 
ship which  determines  their  ethical  validity.  The  individual 


APPLICATIONS  OF  PSYCHOLOGY  347 

who  has  grown  up  in  a  social  group  ultimately  conforms 
in  his  modes  of  thought  and  internal  organization  to  those 
social  demands  which  are  imposed  upon  him  by  the  com- 
munity in  which  he  lives.  It  is  probably  true,  therefore, 
that  in  the  last  analysis  the  fundamental  truths  of  ethics 
are  expressed  in  the  internal  organization  of  the  individual 
as  well  as  in  the  forms  which  are  approved  under  the 
canons  of  social  life,  but  the  development  of  ethical  laws 
lies  somewhat  beyond  the  application  of  psychology.  We 
come  to  ethics  chiefly  through  the  study  of  the  applications 
of  psychology  to  the  sciences  of  social  institutions. 

Psychology  and  metaphysics.  When  we  turn  from  the 
special  philosophical  disciplines  to  the  broader  field  of  meta- 
physics, or  the  general  theory  of  reality,  we  find  that  the 
relation  of  psychology  to  these  broader  types  of  considera- 
tion is  relatively  indirect.  Metaphysics  takes  up  the  results 
of  natural  science  which  deals  with  matter  and  of  psycho- 
logical science  which  deals  with  consciousness,  and  attempts 
to  formulate  some  general  principles  of  the  relations  between 
all  forms  of  reality.  To  this  general  discussion  psychology 
cannot  contribute  final  answers  any  more  than  could  the 
special  sciences  of  physics  or  chemistry.  Psychology  can 
only  present  its  conclusions  after  it  has  carried  out  as  com- 
plete an  ,  analysis  of  consciousness  as  possible,  and  must 
leave  it  for  metaphysics  to  make  an  ultimate  comparison  of 
these  facts  with  the  physical  facts.  The  student  who  finds 
that  an  empirical  analysis  of  consciousness  conflicts  with 
any  of  the  established  views  which  constitute  a  part  of  his 
general  theory  of  the  world  should  recognize  that  it  is  not 
the  function  of  any  single  science  to  reconstruct  his  total 
theory  of  the  world.  He  will  have  to  accept  the  results  of 
empirical  analysis  in  all  the  different  spheres  of  exact 
research  and  work  out  a  general  view  which  will  include  all 
of  these  results.  The  conclusions  of  psychology  need  to  be 
generalized  exactly  as  do  the  conclusions  of  physics  and 


348  <  HOLOGY 

chemistry.    No  general!/  11   be   finally  valid  \\ 

does  not  comprehend  the  empirical  analysis  of  each  one  of 
these  sciences.  Furthermore,  it  should  not  be  forgotten 
that  there  are  many  types  of  c<>:  h  forced 

themselves  upon  human  attention  long  before  the  various 
form-  ntific  analysis  could  be  worked  out,  and  these 

considerations  must  also  be  recognized  in  the  constn. 
of  a  broad  philosophy  of  life.  The  generalizations  which 
were  reached  before  the  development  of  the  special  sciences 
require  revision  in  order  to  include  the  results  of  these 
sciences.  This  fact  should  not  disturb  the  mind  of  any 
student  and  need  not  lead  him  to  ignore  many  nonscientific 
s  of  experience.  The  training  in  scientific  inference 
which  he  has  received  in  the  study  of  empirical  psychology 
should  lead  him  to  recognize  that  all  generalizations  are 
subjective  constructs  built  up  from  a  great  variety  of  experi- 
ences, many  of  which  are  superficially  in  disagreement  with 
each  other.  The  subjective  construct  is  not  to  be  discarded 
as  invalid,  because  it  changes  with  the  acquisition  of  new 
knowledge ;  one's  theory  of  the  world  must  change  in  order 
to  fulfill  its  function  as  a  complete,  organized  expression  of 
the  manifold  experiences  which  enter  into  life.  Psychology, 
more  than  any  other  science,  should  lead  to  a  recognition 
of  this  demand  for  a  constantly  progressing  enlargement  of 
philosophic  view.  While,  therefore,  modern  psychology  as  a 
science  has  freed  itself  from  the  obligation  of  dealing  with 
the  broad  philosophical  questions,  it  continues,  when  rightly 
understood,  not  only  to  contribute  material  for  philosophic 
thought,  but  also  to  urge  the  student  to  the  rational  recon- 
struction of  his  general  abstract  views.  It  is  therefore  intro- 
ductory, not  merely  to  the  special  philosophical  disciplines 
but  also  to  the  more  remote  discussions  of  metaphysics  itself. 


INDEX 


Abnormals,  psychology  of,  II 
Abstract  words,  236 
Abstraction,  232,  263 
Accommodation,  86 
Achromatic  sensations,  74 
Action,  voluntary,  301 

and  words.  235 
Active  organs,  glands  as,  138 

muscles  as,  134 
Adaptation,  conscious,  4 

human,  and  ideas,  251 
Aerial  perspective,  184 
Esthetics,  346 

After-effects  of  hypnosis,  295 
After-images,  auditory,  114 

table  of,  100 

visual,  94 

Agreement,  internal,  as  test  of  im- 
agination, 257 
Alcohol,  285 

Alligator,  nervous  system  of,  31 
Alphabet,  blind,  167 

evolution  of,  222 
Altruism,  151 

American  Crowbar  Case,  58 
Amplitude,  78 

of  vibrations,  78 
Anaesthesia  in  hypnosis,  290 
Analysis,  perceptual,  316 

scientific,  of  consciousness,  65 
Analytical  psychology,  v 
Anger,  152 
Angier,  R.  P.,  vii 
Animal  language,  212 
Animal  psychology,  10 
Animals,  unicellular,  15 
Anthropology  and  psychology,  333 
Aphasia,  56 

Apparatus  in  experiments,  8 
Application  and  verbalism,  323 
Applications  of  psychology,  69,  325 
Aqueous  humor,  85 
Arabic  numerals,  229 
Architectural  harmony,  327 


Arithmetic,  development  of,  229 
Armstrong,  A.  C.,  vi 
Art,  325 

freedom  in,  326 
Articulation,  selection  of,  214 
Association,  245 

principle  of,  59 
Association  area,  Broca's,  57 
Association    areas,    in    cortex,    50, 

52,  S3 

frontal,  58 

in  human  cerebrum,  54 
Association  centers,  29 
Atom,  concept  of,  262 
Attention,  62,  156,  160 

and  gesture,  216 

involuntary,  303 

voluntary,  301 
Attitudes,  66,  69,  142,  233 

control  of,  319 

external,  155 

fundamental,  146 

ideational,  254 

mental,  207 

Auditory  area  in  cerebrum,  52,  53,  54 
Auditory  organ,  109 
Auditory  sensations,  100 
Auditory  sensory  processes,  in 
Auditory  space,  169 
Axis  cylinder,  39 
Axone,  39 

Barter,  252 

Basilar  membrane,  109 
Beats,  auditory,  112 
Behavior,  5 

animal,  248 

and  attitudes,  142 

and  belief,  266 

and  consciousness,  17 

and  education,  343 

and  experience,  130 

fundamental  forms  of,  23 

of  higher  animals,  34 


349 


350 


Behavior,  higher  forms  of.  34,  68. 

153 

rs  of.  and  ideas,  304 

idration.il.  248 

and  imagination.  256 

individual,  136 

inherited,  138 

and  instincts,  199 

of  multiccllular  animals.  22 

nerve  crl. 

and  organization,  313 

organization  of.  140 

scientific  studies  of,  309 

selective  consciousness,  132 

and  sensitivity,  17 

simplest  types  of,  16 

speech,  a  form  of,  209,  217 

of  unicellular  animals,  16 

voluntary,  301 

and  words,  235 
Behaviorism,  iii 
Belief,  265 
Berkeley,  i 
Binocular  vision.  180 
Biological  evolution.  334 
Biology  and  psychology,  3 
Blind  spot,  9 

Blind,  the,  tactual  percepts  of,  167 
Brightne.^. 
Broca.  56 
Bryan,  338,  340 

Cajal,  41,  44,  45,  49 
Cameron,  K.  II.,  vii 
Canals,  semicircular,  107 
Cause,  idea  of,  and  self,  275 
.  gustatory,  120,  121 

muscle.  134 

nerve,  39 

olfactory,  117,  118 
Centers,  in  cerebrum,  50,  52,  53 

higher,  29 

nervous,  29 
Central  nerve  cells,  22 
Central  nervous  system,  25 
Cerebellum,  28,  45 

evolution  of,  31 

human,  38 

Cerebral  processes  and  choice,  305 
Cerebrum. 

cortex  of.  50 

evolution  of,  31 

human,  38,  47 


rhemical  senses.  113 
(  hild  psychology.  10 
:'»  idea  of  self,  270 
%  imagination,  259 
c  writing.  221 
c.  simple.  304 
voluntary,  68 

Choroid  coat  of  eye,  85,  87 
Chromatic  sensations,  74 
Circulatory  activities,  1 54 
Circulatory  movements,  154 
Classification,    of    conscious    proc- 
esses, 61 
threefold,  63 
Cochlea,  auditory,  108 
Codfish,  nervous  system  of.  31 
Coherency,  criterion  of,  258 
Cold  spots,  1 22 

•  74 
Color  blindness,  90 

of  periphery  of  retina,  89 

table  of.  99 
Color  circle,  76 
Color-mixing,  92 

table  of,  too 
Color  names,  75 
Colors,  complementary,  93 
Combinations  of  sensations,  163 
Communication,  animal,  2 1 3 

systems  of,  212 
Complementary  colors,  93 
Concept  of  self,  269,  272 
Concepts,  251 

scientific,  262 

validity  of,  263 
Concrete  words,  235 
Conduct,  control  of,  253 
Cones  of  retina,  87,  88 
Conflict  of  instincts,  200 
Conn.  83 
Consciousness,  and  behavior,  17 

definition  of,  12 

and  evolution,  3.  250 

and  heredity,  203 

nervous  conditions  of,  5 

and  nervous  structures,  38 

and  physical  facts. 

selective,  130 

and  sympathy.  1 60 
Content,  literary,  329 
Contiguity,  association  by,  245 
Contractile  cells,  19 
Contractility,  15 


INDEX 


351 


Contrast,  association  by,  246 

of  self  and  not-self,  271 

space,  174 

visual,  96 

visual,  table  of,  100 
Control,  of  behavior,  13$ 

in  mental  hygiene,  315 
Coordinating   center,   nervous  sys- 
tem as,  25 
Coordination,  136 

of  activities,  314 
Cord,  human,  38,  42,  44 

spinal,  28 
Cornea  of  eye,  87 
Cortex,  of  cerebellum,  45 

cerebral,  44,  49,  50 
Corti,  arch  of,  1 10 
Creation  theory  of  language,  210 
Criticism,    of   ideas   in    hypnotism, 
291 

of  imagination,  256 

literary,  260 
Crowbar  Case,  58 
Current,  nervous,  21 
Czermak,  104 

Darwin,  202 

Deafness,  tone,  115 

Decision,  306 

Definition  of  psychology,  12 

Delayed  instincts,  198 

Delirium,  287 

Dendrites,  39 

Depth,  visual,  179,  186 

Design  in  art,  324 

Development,  plateau  in,  339 

of  self-consciousness,  269 

of  space,  165 

Diagnosis,  psychological,  337 
Difference  tones,  112 
Differences,  individual,  2 
Diffusion,  203,  204,  206 

nervous,  60 
Digestion,  1 5 

in  higher  forms,  19 
Direct  behavior,  248 
Disappointment,  155 
Discord,  114 

Discrimination  and  words,  227 
Diseases,  toxic  effects  of,  286 
Displeasure,  147 
Dissociation,  278 

degrees  of,  281 


Distance,  of  sounds,  171 

visual,  178 

Dog,  nervous  system  of,  31 
Dove,  nervous  system  of,  31 
Dreams,  283 
Drugs,  279,  285 
Dual  personality,  292 

in  hypnosis,  291 

Ear,  evolution  of,  103 

structure  of,  104 
Ebbinghaus,  113 
Economy  of  mental  effort,  320 
Edinger,  46,  47,  48 
Education,  336 

and  choice,  309 
Efficient  cause  and  self,  275 
Elements  of  consciousness,  73 
Embryological  methods  of  localiza- 
tion, 53 
Emotional  expression  and  speech, 

211 

Emotional  life,  disturbance  of,  299 
Emotional  reactions,  253 
Emotions,  147 

in  experiments,  8 

higher  experiences,  153 
Empirical  tests  of  imagination,  257 
Equilibration,  organ  of,  107 
"  Essay  toward   a  New  Theory  of 

Vision,"  180 
Ether,  concept  of,  258 
Ethics,  346 
Eustachian  tube,  106 
Evolution,  and  behavior,  133 

of  belief,  265 

of  complex  organisms,  -32 

and  consciousness,  3,  250 

of  ear,  103 

of  eye,  80 

of  gestures,  217 

human,  333 

of  ideas,  253 

of  instincts,  198 

of  muscles,  134 

of  nervous  system,  31 

parallel  of  behavior  and  structure, 

23 

Excessive  excitation,  298 
Excitation,  process  of,  21 
Experience,  and  behavior,  130 

definition  of,  12 

and  emotions,  152 


of  lower  animals,  17 
ordinary,  I 
and  physical  fact*.  * 
and  time. 

I,  classifications  of,  63 
iH-iu.  auditory  space,  170 
psychology,  7 

:>tal  psychology,  1 1 
ucnu.  on  the  present,  191 
reaction,  310 

-Mun  and  mental  life,  343 
lavements,  154 

as  method  of  localization.  51 

volution  of,  So 
hum. 

ition,  principle  of,  59 
Familiarity,  visual  perception,  184 

-.  280 
icd  nerve  cells,  280 

149,  150,  201 
Fechner,  129 
Feeling,  63 
and  intuition,  329 
organic,  153 
Feelings,  cultivated,  147 
Fibers,  in  cerebrum,  47 
nerve,  39 

systems  of,  in  cerebrum,  47 
Figures : 

Association  fibers,  47 
Association  by  similarity,  245 
Balance,  158 
Binocular  parallax,  182 
Hlind  spot,  9 
Cerebellum,  human,  45 
Cerebral  centers,  52,  53 
Cerebral  cortex,  49,  50 
Cerebrum,  human,  46 
Chinese  writing.  221 
Cochlea,  auditory,  109 
r  circle,  76 
«1,  human.  44 
MS  callosum,  48 
( 'urve  of  sleep,  282 

lopment  of  telegraphic  lan- 
guage, 338,  340 
104 

ition  of  eye,  82 
Evolution  of  letter  M. 
Eye,  human,  85 
Fatigued  nerve  cells,  280 


tern.  38 

n!>    during 

'57 

Localization  ot  functions.  52,  53 
Movement*    of    unicellular    ani- 
mals, 16 

Muller  f.yer  illusion,  172 
Muscle  cell,  134 
Muscle  cells,  primitive,  20 
'ilar  contraction,  135 
Nasal  cavity,  116 

ve  cells.  20,  39,  40 

•>n  of.  41 

Nervous  system  of  alligai 
.  ou*  system  of  codfish,  31 

•us  system  of  dog.  31 
Nervous  system  of  dove,  31 
rvous  system  of  frog,  28 
•>wa  love  letter.  220 
Olfactory  cells.  1 17,  118 
Peduncular  fibers,  46 
Photographs  of  eye  movements, 

177 

PoggendorfT  illusion,  176 
Relation  of  retinal  image  to  sue 

of  object,  179 
Retina.  88 
Sensory  cells  in  vestibule  of  ear, 

1 08 
Sensory  processes  and  reactions, 

U3 

Sound  waves  in  beats,  1 13 
Space- contrast  illusion. 
Spinal  cord,  human.  42.  44 
Stag  beetle,  nervous  system  of,  25 
Starfish  and  nervous  system,  24 
ucture  of  hydra,  18 
.ipses.  40 

Taste  bulbs,  119,  120.  i :  i 
Touch  organs,  124,  125.  126,  127 
Wave  forms,  77 
/.ollruT  illusion.  176 
Figures  of  speech,  238 

.  lohn.  151,  152 
Flechsig,  52 
Flexor  movements,  154 
Food  instincts,  198 
Form,  recognition  of,  132 

:  t  entralis,  89 
Franklin.  M  97 

Freedom  of  will,  308 
Frog,  behavior  of,  35 
nervous  system  of,  28 


INDEX 


353 


Fusion,  64,  67,  70 
of  sensations,  163 
and  space,  187 
and  use,  190 

Galton,  242 

General  ideas  and  words,  234 

Generalization,  264 

Geometrical  perspective,  184 

Gesture  language,  216 

Glands,  active  organs,  138 

Golgi-Mazzoni  corpuscle,  125 

Gossip,  evolution  of  word,  231 

Gravity,  concept  of,  232 

Gray,  sensations  of,  74 

Gray  matter,  nervous,  42 

Greeff,  88 

Greek  column,  1 58 

Greek  philosophy  and  psychology,  2 

Habit,  304 

and  consciousness,  207 

and  diffusion,  203 

and  instinct,  202 

and  perception,  191 
Habits,  195 

derived  from  instincts,  199 

motor,  341 

Hair,  nerves  around,  126 
Haller,  18,  20 
Hallucinations,  278 
Handwriting,  habit  of,  204 
Harmony,  musical,  114 
Harter,  338,  340 
Heat  spots,  123 
Hebrew  alphabet,  223 
Helmholtz,  no,  in 
Herrick,  108,  109 
Higher  animals,  behavior  of,  34 
Hodge,  280 
Hydra,  18 

Hygiene,  mental,  314 
Hyperaesthesia  in  hypnosis,  290 
Hypnosis,  279,  287,  288 

Idea  of  self,  269 
Ideas,  70 

abstract,  263 

balancing  of,  306 

characteristic  of  man,  239 

dominant,  321 

in  dreams,  283 

flexibility  of,  247 


general,  264 

higher  behavior,  304 

and  higher  social  life,  268 

and  impressions,  240,  241,  254 

influence  of,  249 

and  memory,  240 

scientific,  258 

and  speech,  209,  215 

verbal,  233 
Ideation,  68 

wholesome,  320 
Ideational  attitudes,  254 
Ideational  behavior,  248 
Illusion  of  weights,  1 59 
Illusions,  278 

optical,  172 
Imageless  ideas,  232 
Imageless  thought,  246 
Imagery,  and  ideas,  246 

individual  variations  in,  242 

and  words,  232,  233 
Images,  and  ideas,  237 

memory,  6 

as  obstructions  to  thought,  238 
Imagination,  251,  254 

child's,  259 

literary,  260,  330 

personifying,  255 

uncritical,  259 
Imitation,  and  speech,  212 

theory  of  speech,  210 
Impressions,  and  ideas,  254 

not  ideas,  240 

sensory,  66 
Impulse,  302 
Incus,  106 

Indirect  behavior,  219,  248 
Indirect  nervous  centers,  30 
Individual,    higher,   self-sufficiency 

of,  33 

Infant  expression,  214 
Infant  recognition  of  space,  165 
Inheritance  of  nervous  structures, 

26 

Insanity,  279,  294,  296 
Instinctive  behavior,  301 
Instinctive  life,  disturbance  of,  299 
Instincts,  26,  138,  196,  198,  207 

and  religion,  267 

and  sentiments,  267 
Intensities,  sensation,  126 
Intensity  of  sounds,  102 
Interest  and  behavior  132 


354 


Interjection  theory  of  spr. 
Intervening     objects     and     visual 
sp.' 

' 

and  class  it 
def< 

sensations.  141 

sychology,  331 

Intuition  .mi!  tccling.  329 
Involunt.irv  .itu-ntion,  303 

Irritable  cells  in  higher  forms. 

James,  William,  vi,  342 
Jastrow,  157 
Jealousy.  152 
Jennings. 
Judgment,  264 

Kipling,  149,  150,  151 

Ktlowledp 

Kohlschuttor,  282 

language.  209 

and  idea- 
Law,  Weber's,  i 
learning  curve.  338,  340 
Learning  handwriting,  205 

•  ning,  units  of,  320 
I-ens,  evolution  of,  83 

of  eye,  85 

Letters,  evolution  of. 
Libertarianism,  308 
Life,  concept  of,  275 
Light,  analysis  of,  3 

external,  78 
Literary  content. 

ttion,  260 
Local  signs.  i6S 

Localization  of  brain  functions,  50, 58 
Location,  auditor}-,  169 
Locke,  John,  i 
Locomotion,  instinct  of,  199 
Loeb,  24 
Logic,  265,  345 
Lotze,  168 

Loudness  of  sounds,  102 
Love,  parental,  151 

M.  letter,  evolution  of,  222 
Mailer)-.  220 
Malleus,  105 


Meatus,  external.  104 

internal.  106 

UIWB  and  space,  187 
lanical  senses,  123 
Medul 

human.  38 
Melancholia,  297 
Memory.  14.  64.  67,  70,  196,  320 

experiments  in,  7 

and  ideas.  240 

physiological  conditions  of,  32 

and  words,  220 
Mental  hygiene,  314 
Metaphysics,  347 
Method,  indirect,  in  pcycholop 

in  psycholog, 
Methods  <if  drain  localization.  50 

and  evolution,  333 
Missenian  corpuscle,  124 
Mixed  colors,  77 
Motive  for  psychology 
Motor  area,  cerebral,  55 
Motor  areas  in  cerebral  cortex,  50, 

5^.53 

Motor  nervous  process,  22 
r  processes,  59,  64 

in  sleep,  284 
Motor  reactions,  3 1 1 
Movements,  analysis  of,  311 

and  attitudes,  1 54 

eye,  175.  176 

in  reactions,  312 

undeveloped,  206 

and  visual  perception,  186 
Miillcr-Lycr  illusion. 
Multiccllular  animals,  18 
Multiple  personality,  293 
Muscle  cell,  134 
Muscle,  sense  organs  in,  125 
Muscles  of  eye,  84 

ilar  tension,  general,  302 
Mythology,  259 

Nagel,  52 
Narcotics,  285 
Nasal  cavity,  116 
Negative  after-images,  95 
Nerve  cells,  39 

evolution  of,  41 

fatigued,  280 

types  of.  22 
Nervous  centers,  higher,  31 


INDEX 


355 


Nervous   conditions,   of   conscious- 
ness, 5 

and  drugs,  285 
Nervous  current,  21 
Nervous  processes  and  sensations,  7  2 
Nervous  structures  and  conscious- 
ness, 38 

Nervous  system,  as  basis  of  psycho- 
logical classification,  61 

and  behavior,  35 

centralized,  23 

of  frog,  28 

human,  38 

stag  beetle,  25 

starfish,  24 

vertebrate,  27  et  seq. 
Neurones,  39 

evolution  and  development  of,  41 
Newton,  Isaac,  3 
Noise,  102 
Number  names,  228 
Number  terminology,  227 
Numerals,  systems  of,  229 

Objective,  13,  271 

Objects  and  perception,  188 

Observation,  and  classification,  61 

in  psychology,  8 

self-,  4 

Occult  in  psychology,  2 
Ojibwa  writing,  220 
Olfactory  lobes,  28 
Olfactory  organ,  116 
Optic  lobes,  28 
Optical  illusions,  172 
Organ  of  Corti,  109,  no,  in 
Organic  activities,  315 
Organic  feelings,  153 
Organic  retentiveness,  195 
Organic  sensations,  125 
Organization,  64 

for  behavior,  34 

of  behavior,  141 

concept  of,  in  psychology,  313 

and  decision,  306 

and  diffusion,  60 

idea  of,  275 

of  ideas,  254 

normal  consciousness,  287 

principle  of,  60 

self-directed,  324 

and  thought,  320 
Ossicles,  chain  of,  106 


Overexcitation,  286 
Overtones,  102 

Pacinian  corpuscles,  124 
Pain,  62 
Pain  spots,  123 
Parental  love,  151 
Paths,  nervous,  26 

nervous,  in  cord,  42 
Peduncular  fibers,  46 
Perception,  67,  164,  174,  304 

of  objects,  1 88 

summary  of,  194 
Percepts,  of  blind,  167 

and  habits,  191 

and  repetition,  190 
Perceptual  analysis,  316 
Perceptual  behavior,  248 
Perceptual  process,  example  of,  252 
Perceptual  synthesis,  317 
Personality,  disorganized,  278 

dual,  292 

dual,  in  hypnosis,  291 

multiple,  293 

scientific  idea  of,  274 

and  volition,  308 
Personifying  imagination,  255 
Perspective,  aerial,  184 

geometrical,  184 
Philosophy,  344 

Photographic  records  of  eye  move- 
ments, 175 
Phrenology,  57 
Physical  facts,  and  consciousness, 

72,  79 

and  experience,  2 

Physiological    conditions,    of    con- 
scious processes,  249 

of  experience,  14 

of  habit,  20 1 

of  sleep,  279 

Physiological  psychology,  v,  1 1 
Physiology,  visual  perception,  175 
Pictographic  writing,  219 
Pigment-mixing,  94 
Pinna  of  ear,  103 
Pitch,  loi 

Plateau  in  learning,  339 
Play,  137 
Pleasure,  62,  146 
Poggendorff,  176 
Positive  after-images,  95 
Post-hypnotic  effects,  295 


356 


PSYCHOLOGY 


Practice,  effects  on  illusion 

and  illusion* 
Preface,  first  edition,  v 

Mcoad  <••!•.<  ;i.  in 
Present.  th> 
Pressure  spots,  1 23 
Prevision,  307 
Primary  colors,  7$ 
Problem,  meaning  of  term,  237 
Protective  instincts,  197 
Protoplasm,  15 

-99 
Psychology,  abnormal,  278 

and  aesthetics,  346 

animal.  10 

and  its  applications,  268,  325 

and  biology,  3 

child,  10 

definition  of.  12 

and  ethics,  346 

experimental.  S.  1 1 

forms  of,  10.  ii 

functional,  v 

Greek.  2 

and  logic.  345 

and  metaphysics,  347 

and  philosophy,  344 

and  physics,  3 

physiological,  v,  5,  1 1 

scope  of,  12,  69,  70 

social,  1 1 

structural,  v 

subdivisions  of.  10 

rio-physics,  73 
Purple,  76 
Purpose  and  choice,  309 

Quality,  tonal,  101 

Reaction  experiments,  310 
Reaction  times,  310 
Reactions,  66 

motor,  311 

sensory.  311 
Reading  of  blind,  167 
Reasoning.  264 
Rebus  and  alphabet,  223 
Recall  and  memory,  244 
Recency  and  memory,  243 
Recognition  and  attention,  161 
Reflex,  44 

Relativity  of  temperature  sense,  123 
Religion  and  self-consciousness,  273 


—  A  — 

Jv/ 

Reproduction.  15 

evolution  of,  33 

in  higher  forms,  19 
Retention  and  memor 

1.87 
Retinal  image,  size  of.  178 

rial  rivalry,  183 
Retzius,  12< 
Rhythm,  prose,  327 

and  time,  193 
Rivalry,  retinal.  183 
Rods  of  retina,  87,  88 
Rolando,  fissure  of.  53 
Roman  numerals. 
Ruffini.  125 

Saturation,  color,  77 
Scala,  tympani.  109 

vestibuli.  109 
Science,  development  of,  261 

•;ftc  ideas,  258 

Scientific  studies  of  learning,  342 
Self,  idea  of.  269 

as  scientific  concept,  272 

unity  of,  275 
Self-consciousness,  273 

development  of,  269 
Self-directed  organization.  324 
Self -observation,  4,  13 
Semicircular  canals,  107 
Sensation  intensities,  126 
Sensations,  66,  69,  71 

auditory,  101 

combination  and  arrangement  of, 
162 

introspective,  141 

muscle,  125 

organic,  125 

of  smell,  117 

of  taste,  1 19 

of  touch,  1 2 1 

visual,  74 
Sense  organ  and  visual  sensations, 

80 
Senses,  chemical  and  mechanical, 

Sensitive  cells.  19 

Sensitivity,  17 

Sensory  area,  cerebral.  55 

Sensory  areas  in  cerebral  cortex. 


INDEX 


357 


Sensory  cells,  20 
Sensory  centers,  29 
Sensory  impressions,  34 

meaning  of,  139 
Sensory  nervous  centers,  29 
Sensory  processes,  22,  64 
Sensory  reactions,  311 
Sentiments,  267 
Shadows,  185 
Shame,  152 

Sheath  of  Schwann,  39 
Signs,  local,  168 
Similarity,  association  by,  245 
Size,  perception  of,  175 

visual,  178 
Sleep,  279,  281 

curve,  282 

and  motor  processes,  284 
Smell,  116 

rudimentary  sense,  1 18 
Smith,  C.  H.,  vii 

Social  consciousness  and  self,  272 
Social  influence  and  thought  of  in- 
dividual, 225 

Social  life  and  higher  mental  proc- 
esses, 267 

Social  motives  and  language,  223 
Social  psychology,  n 
Social  sciences,  208,  331 
Sociology,  335 
Solidity,  visual,  181 
Sound,  localization  of,  171 

physical,  101 

Sounds  and  communication,  213 
Space,  auditory,  169 

many  senses,  169 

and  movement,  187 

product  of  fusion,  163 

tactual,  164 

visual,  172 
Specialization,  318 

of  functions,  18 
Spectrum,  76 
Speech,  209 

and  ideas,  215 

origin  of,  210 

Speech  center  in  cerebrum,  56 
Speech  centers,  54 
Spencer,  335 
Spinal  cord,  frog's,  28 
Stapes,  106 

Starfish,  nervous  system  of,  24 
Stereoscope,  rei 


Stimulation,  21 

as  method  of  localization,  51 
Stimuli,  gustatory,  121 

olfactory,  118 
Stimulus,  20 

physical,  127 
Structural  psychology,  v 
Subdivisions  of  psychology,  10 
Subjective,  13,  271 
Suggestions,  289,  291 
Summation  tones,  113 
Sylvian  fissure,  54 
Symbolic  value,  252 
Symbols,  number,  228 

writing,  221 
Sympathy,  158 

and  consciousness,  160 
Synapses,  40,  41 

in  sleep,  280 
Synthesis,  perceptual,  317 

Tables : 

After-images,  100 

Auditory  processes,  115 

Color  blindness,  99 

Color  contrasts,  100 

Color-mixing,  100 

Experiences,  37 

Forms  of  behavior,  36,  37 

Nervous  structures,  36,  37 

Physical  light  and  sensations,  79 

Red-green  color  blindness,  91 
Tallies,  228 

and  number,  228 
Taste,  sensations  of,  116,  119 
Taste  bulbs,  1 19 
Taylor,  I.,  222 
Telegraphic  language,  338 
Temperature,  production  of,  in  ani- 
mals, 32 

Temperature  spots,  122 
Tension,     constant,     in     muscles, 
138 

experiments  on,  156 
Tensor  tympani,  105 
Tests  of  imagination,  256 
Testute,  39,  124 
Theories,  of  color  vision,  97 

of  origin  of  language,  211 
Thought  relations,  234 
Timbre,  102 
Time,  191 
Tone  deafness,  115 


Tones,  different  • 

•ummation.  1 1  \ 
Tool  consciousness,  249 
Tooth,  nerve  m. 
Touch,  inner,  168 

organs  of. 

sensation 

space,  164 

Toxic  substances,  286 
Tracts,  nervous,  59 
Trench,  230 
T-i  hrtmA,   ;.• 
Tympanic  membrane.  105 

Uncritical  imagination  in  dreams, 284 
Unicellular  animals,  15 

behavior  of,  16 
Unity,  concept  of,  276 

of  objects,  189 

of  self,  275 

Value,  ideas  of,  252 
iism.  266,  322 
Verse,  328 

and  time,  192 
Vesicle,  auditory,  103 

ihule,  auditory,  107 
Vibrations,  light,  78 

sound, 101 
Vision,  adaptation  of,  to  behavior,  1 32 

and  touch,  166 


Visual  area  in  cerebrum,  52,  53,  54 
Visual  space,  172 

r,  85 
iness,  62 

and  memory,  243 
Volition,  63,  70,  301 
and  attitudes,  319 
Voluntary  choice,  68 

\V .ilking  as  instinct,  199 
Wave  forms,  77 
Weber,  127.  164 
Weber's  Law,  127 

interpretations  of,  128 
White,  sensations  of,  74 
Will.  63 

freedom  of,  308 

Wonder,  motive  for  psychology,  I 
Words,  abstract.  236 

evolution  of,  230 

experiments.  226 

and  general  ideas,  234 

interpretation  of,  6 

recognition  of.  318 

social  values  ot 
\Vurk  song  and  language,  218 
Writing,  evolution  <>!. 
Wundt.  Wilhelm,  vi,  167 

Zdllner.  176 


ANNOUNCEMENTS 


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