DAMAGE BOOK
THE TEXT IS
LIGHT IN
THE BOOK
/5V.3
Keep Your Bard In tills Pocket
Boob will be issued only on presentation
of proper library cards.
Unless labeled otherwise, books may be
retained for four weeks. Borrowers finding
books marked, defaced or mutilated are ex-
pected to report same at library desk; other-
wise the last borrower will be held responsible
for all imperf ections* discovered.
The card holder is responsible for all books
drawn on bis card.
No boob issued unless penalties are paid.
Lost cards and change of residence must
be reported promptly.
Kansas City, Mo.
Keep Your Card in this Pocket
BEHAVIOR
An Introduction" td* Comparative
Psychology
BY
JOHN B. WATSON
Professor of Psychology m The Johns Hopkins University
NEW YOEK
HENEY HOLT AND COMPANY
COPYRIGHT, 1914,
BY
HENRY HOLT AND COMPANY
2
THE QU1NN & BODEN 00 PRESS
RAHWAY, N
To my Friends and Teachers
JAMES R. ANGELL AND HENRY H. DONALDSON
this Book is Gratefully
Dedicated.
PREFACE
This volume on behavior is an elaboration of the eight
lectures given at Columbia University during the winter
of 1913. It has been written with the hope that it
may be found serviceable in classroom work in psychol-
ogy and biology. Needless technicalities and detailed
references have been omitted. For this reason the general
reader may find something of interest in its pages. The
book must not be looked upon as a reference book or
treatise. The treatment of the research material has not
been exhaustive. For the most part no attempt has been
made to give investigators detailed credit for their work.
I have not, however, been able to carry out consistently the
plan of omitting references. In most sciences which have
existed for any length of time a general body of data be-
comes common property, and it is unnecessary to mention
the original discoverers of the universally accepted facts
Some parts of the study of behavior are so involved in con-
troversy that no results can be said as yet to be universally
accepted by specialists in the subject. In dealing with
these facts, especially in the chapters on the sense organs,
it has been necessary to enter with some detail into the
discussion of the investigations and theories of individual
writers. It is hoped that the volume will contribute some-
thing towards the introduction of more careful methods in
the study of behavior, and serve to mark off the study from
the other sciences.
An endeavor has been made to adapt the book to the
needs of various classes of readers. Where only a short
time can be devoted to a classroom course In behavior, I
suggest that chapters I, II, III, V, VII, and IX be omitted.
In the preparation of the manuscript my heaviest obliga-
tion is to Dr. K. S Lashley, Bruce Fellow in Biology, the
Johns Hopkins University. He has given unsparingly of
vi PEEPACE
Ms time In helping In the actual p viv.ra^on of the chap-
ters on the origin of instincts and the fixation of arcs in
habits. Dr. H. M Johnson has assisted me greatly by fur-
nishing the drawing and description of the Helmholtz
method of tandem-driven forks.
I owe a heavy debt of gratitude to my colleagues Profes-
sors Arthur 0. Lovejoy and Knight Dunlap for kindly criti-
cisms and helpful suggestions during the preparation both
of the Columbia lectures and of the manuscript of the book
My long and intimate association with Kobert M. Yerkes
and with Harvey Carr has been of great benefit to me. I
owe them much more than can be gathered from a mere
reading of the following pages.
Finally I wish to express my indebtedness to my secre-
tary, Miss Clarice Shoemaker, who has been untiring in her
work upon the manuscript.
J. B W.
THE JOHNS HOPKINS UNIVERSITY,
May, 1914*
CONTENTS
CHAPTER I
PAGE
PSYCHOLOGY AND BEHAVIOR 1
^Unsatisfactory nature of present i^vcliolo^H.j.! piemises.
The nature of the behdvioi - - ^ ^ ,p The image as
an implicit form of beha\ioi \ n - ,s a form of in-
stinctive behavior Summary
CHAPTEE II
SOME PROBLEMS ENUMERATED 29
No lack of unity m behavior |-, V- -. - - "T...M versus
laboratory studies Grouping of piouiems. i &eiihe organ
processes. Introduction 1 Vision Necessity for con-
sidering anatomical structure Reflex responses to light.
General division of problems in vision (a) White light
vision. (6) Response to monochromatic light. 2. Audi-
tion. Grouping of problems (1) Response to pendular
vibrations ( a ) Range of sensitivity ( ft ) Localization
(c) Response to clangs (2) Response to a-periodic vibra-
tions (a) Stimulus threshold (5) Difference threshold.
(3) Response to ordinary sounds in the environment.
(a) Instinctive repertoire of sounds (b) Modification of
vocal sounds through social influences (c) Influence of
such sound- upon in.ito-* -3. Olfaction and gustation
Lack of definite kovlt(lre about smell functions "Prob-
lems m olhidion Him (ion of olfaction in habit forma-
tion Problems in gustation. 4 Cutaneous, proprio- and
entero-eeptive systems Difficulties in the way of making
satisfactory tests. Proprio-ceptive system Cutaneous
system as a distance receptor. II Instinctive functions
Introduction Some types of instinctive response The
animal's instinctive mode of attack on problems
Instinct and habit. III. Learning Introduction Group-
ing of problems ( 1 ) Perseverance method ( 2 ) Efficiency
of training methods (3) Complex forms of learning.
IV Correlations Introduction. Lack of behavior data
handicaps the neurologist General aim of behavior,
Summary.
vii
viii CONTENTS
CHAPTER III PAGE
APPARATUS AND METHODS .56
Introduction. I. Stimulus to general activity: stimuli
to locomotion (a) General stimuli positively responded
to. (6) General stimuli negatively responded to II.
Methods of studying the receptors of animals* forcing the
formation of sensory habits Control box Pawlow's
method. Methods dependent upon instinctive response.
Control and auxiliary methods. Criticisms of the methods
for determining the sensitivity of receptors. III. Appa-
ratus for obtaining specific stimuli: apparatus for obtain-
ing monochromatic light. Use of apparatus The selenium
cell. Device for securing a purified spectrum Apparatus
for testing response to white light, form,, and size Ap-
paratus for producing auditory stimulation apparatus
for obtaining constant air supply. The Helmholtz system
of tandem-driven forks Animal control box for work on
audition. Yerkes* apparatus for testing hearing in frogs.
Apparatus for obtaining olfactory and cutaneous stimuli.
Yoakum's temperature apparatus IV Methods of studying
motor habits: introduction The problem box method
Description of boxes. Description of maze experiment.
Apparatus for the study of the delayed reaction.
CHAPTER IV
OBSERVATIONAL AND EXPERIMENTAL STUDIES UPON
INSTINCT ......... 106
Use of term Broader definition of term reflex de-
manded. Content of term reflex as used in behavior
General types of instinct Methods of studying instinct.
Various results obtained by the method of field observa-
tion Instinctive activity of birds: the noddy tern.
Instinctive activity of reptiles. Instinctive activity
of fish. Special forms of instinctive activity in fish
Results of the experimental study of instincts. I. The
initial performance of some instinctive acts II Serial un-
folding of instinctive acts of young captive animals: (a)
Guinea pig, (6) Rat; (c) Monkey; (d) Sooty tern. Ill
Quantitative study of improvement of instinctive function
IV. Modification of instinct through social influences V.
Hereditary character of certain instinctive acts and traits.
VI. Waning of instinct: loss through disuse, etc
CHAPTER V
CONCERNING THE ORIGIN OF INSTINCTS .... 148
Introduction. Early differentiation of parts. I. Hered-
ity: the concept of unit characters. Unit characters, -
CONTENTS ix
PAGE
Mendel's experiments. II Origin of diversities in organ-
isms.. Introduction Darwin's conception of variations.
Continuous variation due to direct action of the environ-
ment upon the developing organism. The non-inheritance
of continuous variation, Discrete variations or mutations.
Frequency of mutations. Cause of mutations The Dar-
winian conception of selection. Changes in the concept of
natural selection Effect of natural selection upon muta-
tions. Ability to form habits enables the animal to supple-
ment a faulty inheritance Some special forms of adap-
tations, (a) Protective resemblance. (6) Warning colo-
ration, (c) Sexual dimorphism III. Inheritance of ac-
quired characters. Lamarck's laws Recent experiments
upon the inheritanc " , ' "laracters.- The experi-
ments of Kammerer - * v . , , negative in character.
The direct adaptation theory. Summary
CHAPTER VI
THE EXPERIMENTAL STUDY OF HABIT FORMATION . 184
I Content of term habit. Restatement II Types of habit.
Motor habits; mammals. Motor habits; birds. Motor
habits; fish. Motor habits; reptiles. Habits of manipu-
lation; mammals. Habits of manipulation; birds Sen-
sory habits. III. Curves of learning; motor habits
Curves of learning; sensory habits. Motor habits in human
beings. Comparative " . if ^ A" T i' .-f different animals.
IV. The rise of habits A * i" . , .-,". controlled Habits
formed without the use of punishment. With punishment
as the sole incentive With punishment for wrong response
and food for right response. V. Analysis of reflexes in-
volved in habit. Normal and operative methods of elimi-
nating sensory impulses. Some results of experimental
analysis of motor habits in mammals Analysis of motor
habits in birds Analysis of sensory habits in mammals.
Analysis of the delayed reaction in mammals Summary.
VI. Efficiency of training methods: motor habits Sensory
habits The delayed reaction. VII. Other conditions which
affect learning (1) Age. (2) Sex. (3) Certain bodily
conditions. (4) Learning in animals with less than nor-
mal brain weights. Motor habits in animals with parts
of nervous system removed. VIII. Effect of previous
habits upon the formation of new habits motor habits.
IX. Retention. Mammals Birds Amphibia and rep-
tiles.
CHAPTER VII
FIXATION OF ARCS IN HABIT 251
Introduction Historical outline. Misconceptions and
illogical presuppositions Enumeration of some of the
x CONTENTS
PAGE
problems. Factors involved in fixation Application of
the principle of ft equency in motor habits Justification
for the use of the p 1 r M^ -A,), ^t . J Vi of the pimeiple
of recency in motor ' , i ., - NHI-, \ \,,\ 1L g Substitution.
Repetition of movement in absence of original stimulus.
Conclusions.
CHAPTER VIII
THE ABRIDGMENT OP THE LEARNING PROCESS . . 277
Introduction Lloyd Morgan's classification of imitation.
Localizing and enhancing the stimulus Putting the ani-
mal through the act. Presentation of experimental results :
Introduction. A. Primates. B. Cats. C. Dogs D. Rac-
coons. E. Rodents. F. Birds Summary.
CHAPTER IX
THE LIMITS OF TRAINING IN ANIMALS .... 297
Introduction Some gifted animals (1) Clever Hans
( 2 ) The horses of Elberfeld Claparede's examination ;
results of the first set of observations Later tests by
Claparede Tests on morning of the 26th of March
Afternoon of March 26th March 28th, morning and after-
noon. Tables of results. (3) Peter. (4) Don. (5)
Jasper. Summary
CHAPTER X
MAN i AND BEAST 317
Introduction Man and animal The lack of language
habits differentiates brute from, man Instinctive basis of
language The nature of language habits. Early predomi-
nance of language habits. Forms of language habits.
Futility of the search for reasoning, imagery, and the like
in animals Division of labor between human and animal
behaviorists.
CHAPTER XI
VISION 335
Introduction I Limits of spectral sensitivity and rela-
tive* stimulating effect of different regions of the spectrum.
Mammals Birds with day vision. Birds with twi-
light vision Hess' absorption theory. In fish In rep-
CONTENTS xi
PAGE
tiles and amphibia II Darkness-adaptation; white light.
Introduction Darkness-adaptation in birds with day-
light vision In birds \\ith twilight vision. In fish
In reptiles and in amphibia. III. Darkness-adaptation
monochromatic light In birds In reptiles and in am-
phibia IV Sensitivity to \ \ -. In mammals
In birds Demonstration of , ' * effect. Results
from a physiological method of testing for color sen^ithitv.
Mimicry or adaptation to Ih'cixir .miu 1 no test of coloi
sensitivity In reptiles and in amphibia Delicacy of the
problem in color sensitivity V. Response to white light,
Mammals Birds. Fish Amphibia and reptiles VI.
Response to form and size In mammals In birds In
reptiles and in amphibia
CHAPTER XII
AUDITORY AND RELATED FUNCTIONS .... 370
Introduction Some structural differences in the audi-
tory oipri- -- \uditory responses in mammals (a) The
dog K!iiM ",< i -, experiments Rothman's experiments
Further expeiiments by Kahscher Johnson's experiments.
Experiments made by the Pawlow method. Experiments
of Syzmanski on localization. (b) The cat response of
cats to tones, noises, and to articulate sounds. (c) Rac-
coons reactions of raccoons to tones and articulate sounds.
Tests upon mice and rats Incidental tests upon other
mammals' (a) Monkeys, (b) Horses (c) Bats Audi-
tory response in birds. In pigeons and parrots Audi-
tory response in amphibia Frogs Auditory response
in fishes. Sonic in\<-iij>aioi*' \\lio report lack of auditory
sensitivity in li-lic- ln\i i -iiriioi> ii|i->uii.l -innuli m water
Summary The lateral line organs.
CHAPTER XIII
SMELL, TASTE, AND THE " COMMON CHEMICAL SENSE " 399
I Smell Olfactory reactions in mammals Romanes*
test of the hunting dog Difficulties m the way of explain-
ing the hunting behavior of dogs. Experiments on the
olfactory sensitivity of birds The sense of smell in fishes
Experiments by Parker and Sheldon. II Taste Loca-
tion of gustatory organs TTeirick'-, experiments upon the
functional significance of the taste buds Parker's experi-
ments upon the gustatory responses of fishes. III The
" common chemical sense* 3 ' Introduction Sheldon's ex-
periments upon the smooth dogfish. The " common chemi-
cal sense" m amphibia. Summary
xil CONTENTS
CHAPTER XIV
PAGE
CUTANEOUS, ORGANIC, AND KINJESTHETIC SENSES . 421
I. Cutaneous. Cutaneous sensitivity in mammals.
Halm's experiments upon the bat The " sense of support "
in mammals Yoakum's experiments upon the temperature
sense in mammals. Contact sensitivity in fish. Contact
and temperature sensitivity in amphibia. II. The organic
system. III. The kinsesthetic system.
INDEX 433
BEHAVIOR
An Introduction to Comparative
Psychology
BEHAVIOR
CHAPTER I
PSYCHOLOGY AND BEHAVIOR*
Unsatisfactory ns . " psychological premises. T&e na-
ture of the )srram r lhe image as a form of
implicit behavior \ MI ion ,1 - ,[ i n m of instinctive behavior.
Summary.
Unsatisfactory nature of present psychological prem-
ises. Psychology as the behaviorist views it is a purely
objective experimental branch of natural science. Its theo-
retical goal is the prediction and control of behavior. In-
trospection forms no essential part of its methods, nor is the
scientific value of its data dependent upon the readiness
with which they lend themselves to interpretation in terms
of consciousness. The behaviorist attempts to get a unitary
scheme of animal response. He recognizes no dividing line
between man and brute. The behavior of man, with all of
its refinement and complexity, forms only a part of his total
field of investigation.
It has been maintained by its followers generally that
psychology is a study of the science of the phenomena of
consciousness. It has taken as its problem, on the one
hand, the analysis of complex mental states (or processes)
into simple elementary constituents, and on the other the
construction of complex states when the elementary con-
stituents are given. The world of physical objects (stimuli,
including here anything which may excite activity in a
receptor) , which forms the total phenomenon of the natural
scientist, is looked upon merely as means to an end. The
1 A few new terms have been used in this discussion of behavior
such as behaviorist, ftehavioristoc, "behaviorism While it is admitted
that these words sound somewhat barbaric on a first hearing, they
at least have the merit of being expressive and natural ^ Indulgence
is also asked for the use of " perseverance method " in place of
" trial and error " method in the description of th experiments on
learning
2 PSYCHOLOGY AND BEHAVIOR
end is the production of mental states that may be " in-
spected " or " observed/' The psychological object of
observation in the ease of an emotion, e g , is the mental
state itself. The problem in emotion Is the determination
of the number and kind of elementary constituents present,
their loci, intensity, order of appearance, etc. It is agreed
that Introspection is the method par excellence by means
of which mental states may be manipulated for purposes of
psychology. On this assumption, behavior data (Including
under this term everything which goes under the name
of comparative psychology) have no value per se. They
possess significance only in so far as they may throw light
upon conscious states 2 Such data must have at least an
analogical or indirect reference to belong to the realm of
psychology.
Indeed, one finds at times psychologists who are skeptical
of even this analogical reference. Such skepticism is often
shown by the question which is put to the student of
behavior, " what is the bearing of animal work upon
human psychology 1 ? " With psychology based upon its
present premises such a question is necessarily i i-i]),irni^*r>
for the reason that no answer is open to the man who
uses animals for subjects. The behaviorist has found it
convenient in the past to cultivate a repressed attitude
when talking of his work before orthodox psychologists.
He is interested in this work and believes firmly in its
intrinsic value, albeit he is unable to trace Its bearing upon
psychological theory. Such a confession it is hoped will
clear the atmosphere to such an extent that the behaviorist
will no longer have to work under false pretenses. We
in turn must frankly admit that the facts which we have
been able to glean from extended work upon the senses
of Animals by behavior methods have contributed only in a
fragmentary way to the general theory of human sense
organ processes : and that they have not even suggested new
ways of making experimental attacks upon the problems of
human psychology. The enormous number of experiments
2 I.e., either directly upon the conscious state of the observer or
indirectly upon the conscious state of the experimenter,
PSYCHOLOGICAL PREMISES 3
which we have carried out upon learning has likewise
contributed little to human psychology. It seems reason-
ably clear that some kind of compromise must be effected ;
either psychology must change its viewpoint so as to take
in facts of behavior, whether or not they have bearing upon
the problems of * ' consciousness ; J ' or else behavior must
stand alone as a wholly separate and independent science.
Should human psychologists fail to look with favor upon
our overtures and refuse to modify their position^ the be-
haviorists will be driven to use human beings as subjects
and to employ methods of investigation which are exactly
comparable to those now employed in the animal work.
Any other hypothesis than that which admits the independ-
ent value of the behavior material will inevitably force
us to the absurd position of attempting to construct the
conscious content of the animal whose behavior we have
been studying. On this theory, after having determined
our animal's ability to learn, the simplicity or complexity of
its methods of learning, the effect of past habit upon pres-
ent response, the range of stimuli to which it ordinarily re-
sponds, the widened range to which it can respond under
experimental conditions, in more general terms, its va-
rious problems and its various ways of solving them, we
should still feel that the task is unfinished and that the
results are worthless, until we can interpret them by
analogy in the light of consciousness. Although we have
solved our problem we feel uneasy and unrestful because
of our definition of psychology: we feel forced to say
something about the possible mental processes of our ani-
mal. We say that, having no eyes, its stream of conscious-
ness cannot contain brightness and color sensations as we
know them, having no taste buds this stream cannot
contain sensations of sweet, sour, salt, and bitter. But
on the other hand, since it does respond to thermal, tactual,
and organic stimuli, its conscious content must be made
up largely of these sensations; and we usually add, to
protect ourselves against the reproach of being anthropo-
morphic, " If it has any consciousness " Surely this
doctrine which calls for an analogical interpretation of all
4 PSYCHOLOGY AND BEHAVIOR
behavior data must be shown to be false: the position that
the value of an observation upon behavior is determined
by its fruitfulness in yielding results which are interpret-
able only under the concept of consciousness.
This emphasis upon analogy in psychology has led the
behaviorist somewhat afield. Not being willing to throw
off the yoke of consciousness he feels impelled to make a
place in the scheme of behavior where the rise of conscious-
ness can be determined. This point has been a shifting one.
A few years ago certain animals were supposed to possess
" associative memory,' 3 while certain others were supposed
to lack it. One meets this search for the origin of con-
sciousness under a good many disguises. Some of our
texts state that consciousness arises at the moment when
reflex and instinctive activities fail properly to conserve the
organism. A perfectly adjusted organism would be lack-
ing in consciousness. On the other hand, whenever we find
the presence of diffuse activity which results in habit
formation, we are justified in assuming consciousness.
Such arguments have weight with the neophyte, but as
time goes on and the horizon of animal work broadens, he
becomes less and less convinced of their weight. Many of
us are still viewing behavior problems with something like
this in mind, as is evidenced by the fact that more than one
student of behavior has attempted to frame criteria of the
psychic to devise a set of objective, structural, and func-
tional criteria which, when applied to the particular
instance, will enable him to decide whether such and such
responses are positively conscious, merely indicative of
consciousness, or whether they are purely * * physiological. ' 9
Such problems as these can no longer satisfy behavior men
It would be better to give up the province altogether and
admit frankly that the study of the behavior of animals
has no justification, than to admit that the search is of
such a " will o ? the wisp " character. One can Assume
either the presence or the absence of consciousness any-
where in the phylogenetic scale without affecting the
problems of behavior by one jot or one tittle ; and without
influencing in any way the mode of experimental attack
PSYCHOLOGICAL PREMISES 5
upon them. On the other hand, one cannot for a moment
assume that the Parameeium responds to light; that the
rat learns a problem more quickly by working at the task
five times a day than once a day, or that the human child
exhibits plateaux in his learning curves. These are ques-
tions which vitally concern behavior and which must be
decided by direct observation under experimental condi-
tions.
This attempt to reascn by analogy from human conscious
processes to the conscious processes in animals, atid 'vice
versa, to make consciousness, as the human being knows it,
the center of reference of all behavior, forces us into a posi-
tion similar to that which existed in biology in Darwin's
time. The whole Darwinian movement was judged by the
bearing it had upon the origin and development of the
human race. Expeditions were undertaken to collect
material which would establish the position that the rise
of the human race was a perfectly natural phenomenon
and not an act of special creation. Variations were care-
fully noted and along with them the evidence that they
might be heaped up along lines which would be of service
to the animal j for in this and the other Darwinian mechan-
isms were to be found factors sufficiently complex to
account for the origin and race differentiation of man.
The wealth of material collected at this time was considered
valuable largely in so far as it tended to develop the concept
of evolution in man. It is strange that this situation
should have remained the dominant one in biology for so
many years. The moment zoology undertook the experi-
mental study of evolution and descent, the situation im-
mediately changed. Man ceased to be the center of
reference. It is doubtful if any experimental biologist
today, unless actually engaged in the problem of heredity
in man, tries to interpret his findings in terms of human
evolution, or ever refers to it in his thinking. He gathers
his data from the study of many species of plants and
animals and tries to work out the laws of inheritance in
the particular type upon which lie is conducting experi-
ments. Naturally he follows the progress of the work upon
6 PSYCHOLOGY AND BEHAVIOR
race differentiation In man and the descent of man, but he
looks upon these as special topics, equal in importance
with his own yet ones in which his interests will never be
vitally engaged. It is not fair to say that all of his work
is directed toward human evolution or that it must be
interpreted in terms of human evolution. He does not
have to dismiss certain of his facts on the inheritance of
coat color in mice because, forsooth, they have little bearing
upon the differentiation of the genus Homo into separate
races, or upon the descent of the genus Homo from some
more primitive stock.
In psychology we are still in that stage of development
where we feel that we must select our material. "We have
a general place of discard for processes, which we anathe-
matize so far as their value for psychology is concerned by
saying, " this is a reflex;" " that is a purely physiological
fact which has nothing to do with psychology." We are
not interested (as psychologists) in studying all of the
processes of adjustment which the animal as a whole em-
ploys, and in finding how these various responses are con-
nected, and how they fall apart, thus working out a system-
atic scheme for the prediction and control of response in
general. Unless our observed facts are indicative of con-
sciousness, we have no use for them, and unless our ap-
paratus and method are designed to throw such facts
into relief, they are thought of m just as disparaging a
way.
Psvchology has failed signally during the fifty odd years
of its existence as an experimental discipline to make its
place in the world as an undisputed natural science.
Psychology, as it is generally thought of, has something
esoteric in its methods. If you fail to reproduce my find-
ings it is not due to some fault in your apparatus or the
control of your stimuli, but it is due to the fact that your
introspection is untrained. 3 The attack is made upon the
s In this connection Attention is called to the controversy now
on between the adherents and the opposers of imageless thought The
"types of reactors" (sensory and motor) was also a matter of bitter
dispute The complication experiment was likewise the source of a
war of words concerning the accuracy of the opponent's introspection
PSYCHOLOGY UNSCIENTIFIC 7
observer and not upon the experimental setting In physics
and in chemistry the attack is made upon the experimental
conditions. The apparatus was not sensitive enough, im-
pure chemicals were used, etc. In these sciences a better
technique will give reproducible results. Psychology is
otherwise. If you can't observe 39 states of clearness in
attention, your introspection is poor. If, on the other
hand, a feeling seems reasonably clear to yon, your in-
trospection is again faulty. You are experiencing too
much.
The time seems to have come when -; ,- T ^ -^y must
discard all reference to consciousness, when it need no
longer delude itself into thinking that it is making mental
states the object of observation. We have become so en-
meshed in speculative questions coiUM-i'Mlii^ the elements of
mind, the nature of conscious content (e g., imageless
thought, attitudes, and Bewusstseinslage, etc.), that experi-
mental students are beginning to feel that something is
wrong with the premises and the types of problem which
develop from them. There is no longer any guarantee that
all mean the same thing when the terms now current In
psychology are used. Take the case of sensation. A
sensation is defined in terms of its attributes. One p^r-
chologist will state with readiness that the attributes of a
visual sensation are quality, extension, duration, and in-
tensity. Another will add clearness. Still another that of
order. It is questionable whether any one psychologist
3an draw up a set of statements clc^c ribhig what he means
by sensation which will be agreed to by three other psy-
chologists of different training. Turn for a moment to
the question relating to the number of isolahle sensations.
Is there an extremely large number of color sensations,
or only four, red, green, yellow, and blue? Again, yellow,
while psychologically simple, can be obtained by super-
imposing red and green spectral rays upon the same dif-
fusing surface ! If, on the other hand, we say that every
just noticeable difference in the spectrum is a simple
sensation, and that every just noticeable increase in the
white value pf a given color gives simple sensations, we
8 PSYCHOLOGY AND BEHAVIOR
are forced to admit that the number is so large and the
conditions for obtaining them so complex that the concept
of sensation is unusable, either for the purpose of analysis
or that of synthesis. T^itchener, who has fought the most
valiant fight in this country for a psychology based upon
introspection, feels that these differences of opinion as to
the number of sensations and their attributes ; as to whether
there are relations (in the sense of elements) and on the
many others which seem to be fundamental in every at-
tempt at analysis, are perfectly natural in the present
undeveloped state of psychology. "While it is admitted that
every growing science is full of unanswered questions,
surely only those who are wedded to the system as we now
have it, who have fought and suffered for it, can confidently
believe that there will ever be any greater uniformity than
there is now in the answers we have to such questions.
One must believe that two hundred years from now, unless
the introspection method is discarded, j^yrhol^iry will
still be divided on the question as to whether auditory-
sensations have the quality of " extension,'' whether in-
tensity is an attribute which can be applied to color,
whether there is a difference in " texture " between image
and sensation ; and upon many hundreds of others of like
character.
Our psychological quarrel is not with the systematic and
structural psychologist alone. The last fifteen years have
seen the growth of what is called functional psychology.
This type of psychology decries the use of elements in the
static sense of the structuralists. It is stated in words
which seem to throw emphasis upon the biological signifi-
cance of conscious processes rather than upon the analysis
of conscious states into introspectively isolable elements.
The difference between functional psychology and struc-
tural psychology, as the functionalists have so far stated
the case, is unintelligible. The terms sensation, perception,
affection, emotion, volition are used as much by the func-
tionalist as by the structuralist. The addition of the word
" process " (" mental act as a whole " and like terms are
frequently met) after each serves in some way to remote
PSYCHOLOGY UNSCIENTIFIC 9
the corpse of " content J? and to leave " function " in its
stead Surely if these concepts are elusive when looked at
from a content standpoint, they are still more deceptive
when viewed from the angle of function, and espe-
cially so when function is obtained by the introspective
method.
One of the difficulties in the way of a consistent func-
tional psychology is the parallehstic hypothesis If the
functionalist attempts to express his formulation in terms
which make mental states really appear to function, to
play some active role in the world of adjustment, he almost
inevitably lapses into terms which are connotative of
interaction. When taxed with this he replies that it is more
convenient to do so and that he does it to avoid the cir-
cumlocutions and the clumsiness of statement which are
inherent in any thoroughgoing parallelism. As a matter
of fact the functionalist probably thinks in terms of inter-
action and resorts to parallelism only when forced to give
expression to his views. We advance the view that
behaviorism is the only consistent and logical functional-
ism. In it one avoids both the Scylla of parallelism and
the Charybdis of interaction. Those time-honored relics of
philosophical speculation need trouble the student of be-
havior as little as they trouble the student of physics. The
consideration of the mind-body problem affects neither
the type of problem selected nor the formulation of the
solution of that problem
The nature of the behaviorist's program. This leads
us to the point where argument should be made construc-
tive. It is possible to write a psychology, to define it as
Pillsbury does (as the " science of behavior JJ ), and never
go back upon the definition: never to use the terms con-
sciousness, mental states, mind, content, will, imagery, and
the like. It can be done naturally and conveniently in a
few years from now without running into the absurd
terminology of Beer, Bethe, Von Uexkull, Nuel, and that of
the so-called objective school generally. It can be done in
terms of stimulus and response, in terms of habit formation,
habit integration, and the like. Furthermore it i worth
10 PSYCHOLOGY AND BEHAVIOR
while to make tins attempt so far as animal psychology is
concerned at the present tune.
A psychology of interest to all scientific men would take
as its starting point, first, the observable fact that organ-
isms, man and animal alike, do adjust themselves to their
environment fay means of hereditary and habit equipments.
These adjustments may be very adequate or they may be
so inadequate that the organism barely maintains its
existence, secondly, certain stimuli lead the organisms to
make the responses. In a system of psychology completely
worked out, given the responses the stimuli can be pre-
dicted; given the stimuli the responses can be predicted.
Such a set of statements is crass and raw in the extreme,
as all such generalizations must be. Yet they are hardly
more raw and less realizable ttyan the ones which appear
in the psychology texts of the day. The point might better
be illustrated by choosing an everyday problem which
any one is likely to meet in the course of his work. Some
time ago the author was called upon to make a study of
certain species of birds Until he went to Tortugas he
had never seen these birds alive. On reaching this island
he found the animals doing certain things: some of the
acts seemed to work peculiarly well in such an environment,
while others seemed to be unsuited to their type of life.
The responses of the group as a whole were first studied
and later those of individuals In order to understand
more thoroughly the relation between what was habit and
what was hereditary in these responses, the young birds
were captured and reared In this way it was possible to
study the order of appearance of hereditary adjustments
and their complexity, and later the beginnings of habit
formation. The attempts to determine the stirmlli which
called forth such adjustments were crude indeed. Conse-
quently the attempts to control behavior and to produce
responses at will did not meet with much success: food
and water, sex and other social relations, light and
temperature conditions were all beyond control in a field
study. It was found possible to control their reactions in
& measure by using the nest aud egg (or young) as stimuli,
A. BBHAVIOBISTIC PROGRAM 11
It is not necessary here to develop further how such a
study should be carried out and how work of this kind needs
to be -.t>p\i i( Me / by carefully controlled laboratory
expoi^r.u.'-nts. Were the task to examine the behavior of
some of the Australian tribes the method adopted would
have been much the same, but the problem would have
been more difficult: the types of responses called forth by
physical stimuli would have been more varied, and the
number of effective stimuli larger. The social setting of
their lives would have had to be examined in a far more
careful way. These savages would nal^i-ally be far more
influenced by the responses of each other than was the
case with the birds. Furthermore, habits would have been
more complex and the influence of past habits upon present
responses would have appeared more clearly. Similar
but more complex problems would arise in working out the
psychology of a cosmopolitan race, but the method of at-
tacking them would be the same. In the main, the desire
m all such work is to gain an accurate knowledge of ad-
justments and the stimuli calling them forth. The reason
for this is to learn general and particular methods by
which behavior may be controlled. The goal is not * c the
description and explanation of states of consciousness as
such," nor that of obtaining such proficiency in mental
gymnastics that one can immediately lay hold of a state
of consciousness and say, " this, as a whole, consists of gray
sensation number 350, of such and such extent, occurring
in conjunction with the sensation of cold of a certain
intensity; one of pressure of a certain intensity and ex-
tent, 77 and so on ad infinitum. If psychology would follow
the plan suggested, the educator, the physician, the jurist,
and the ^business man could utilize the data in a practical
way, as'soon as it could be experimentally obtained. Those
who have occasion to apply psychological principles prac-
tically would find no need to complain as they do at the
present time. Ask any physician or jurist today whether
scientific psychology plays a practical part in his daily
routine and you will hear him deny that the psychology of
the laboratories finds a place in his scheme of work,
12 PSYCHOLOGY AND BEHAVIOR
The criticism is extremely just One of the principal
reasons which makes psychology an unattractive sub-
ject is the fact that there is no realm of application for
the principles which, are being" worked out in content
terms.
What makes us hopeful that the behaviorist's position is
a defensible one is the fact that those branches of psy-
chology which have already partially withdrawn from the
parent, experimental psychology, and which are conse-
quently less dependent upon introspection, are today in a
most flourishing condition. Experimental pedagogy, the
psychology of drugs, the psychology of advertising, legal
psychology, the psychology of tests, and psychopathology
are all vigorous growths. These are sometimes wrongly
called * * practical " or ' ' applied ' ' psychology. Surely there
was never a worse misnomer. In the future there may
grow up vocational bureaus which really apply psychology.
At present these fields are truly scientific and are in search
of broad generalizations which will lead to the control of
human behavior. E g , we find out by experimentation
whether a series of stanzas may be acquired more readily
if the whole is learned at once, or whether it is more ad-
vantageous to learn each stanza separately and then pass
to the succeeding. We do not attempt to apply our find-
ings. The application of this principle is purely voluntary
on the part of the teacher. In the psychology of drugs we
may show the effect on behavior of certain doses of caf-
feine. We may reach the conclusion that caffeine has a
good effect upon the speed and accuracy of work. But
these are general principles We leave it to the individual
as to whether the results of our tests shall be applied or
not. Again, in legal testimony, we test the effects of
recency upon the reliability of a witness's report. We
test the accuracy of the report with respect to moving
objects, stationary objects, color, etc It depends upon the
judicial machinery of the country whether these facts are
ever to be applied. For a " pure " psychologist to say that
he is not interested in the questions raised in these divi-
sions of the science because they relate indirectly to the
A BEHAVIORISTIC PROGRAM 13
application of psychology shows, in the first place, that lie
fails to understand the scientific aim in such problems,
and secondly, that he is not interested in a psychology
which concerns itself with human life. The only fault to be
found with these disciplines is that much of their material
is now stated in terms of introspection, whereas a state-
ment in terms of objective results would be far more valu-
able. There is no reason why appeal should ever be made
to consciousness in any of them. Or why introspective
data should ever be sought during the experimentation, or
published in the results. In experimental pedagogy es-
pecially we can see the desirability of keeping all of the
results on a purely objective plane If this is done, work
there on the human being will be comparable directly with
the work on animals.
We are more interested at the present moment in trying
to show the necessity for maintaining uniformity in ex-
[xruni IM.J] pnm diiM- and in the method of stating results
in both human and animal work than in enlarging upon the
changes which are certain to come in the scope of human
psychology. We shall examine for a moment the subject of
the range of stimuli to which animals respond. Let us
first consider the work upon vision in animals. We put
our animal in a situation where he will respond (or learn
to respond) positively to one of two monochromatic lights.
We feed him at the one (positive) and punish him at the
other (negative). In a short time the animal learns to go
to the light at which he is fed. At this point questions
arise which may be phrased in two ways :, one may choose
the psychological way and say, " does the animal see these
two lights as the human being does, i e., as two distinct
colors, or does it see them as two grays differing in bright-
ness, as do the totally color blind! " Phrased by the
behaviorist it would read as follows : ' c Is my animal re-
sponding upon the basis of the difference in intensity be-
tween the two stimuli, or upon the difference in
wave-lengths ^ " He nowhere thinks of the animal's re-
sponse in terms of his own experiences of colors and fijray*
He wishes to establish the fact whether wave-length is a
14 PSYCHOLOGY AND BEHAVIOR
factor In that animal's adjustment. 4 If so, what wave-
lengths are effective and what differences In wave-length
must be maintained in the different spectral regions in
order to afford bases for differential responses? If wave-
length is not a factor in adjustment he wishes to know what
difference in intensity will serve as a basis for response, and
whether the difference obtained at any one point in the
spectrum will suffice throughout the spectrum. Further-
more, he wishes to test whether the animal can respond to
wave-lengths which do not affect the human eye. He is
as much interested in comparing the rat's spectral sensi-
bility curve with that of the chick as in comparing it with
man's. The point of view when the various sets of com-
parisons are made does not change in the slightest.
However we phrase the question to ourselves, we take
our animal after the association has been formed and
introduce certain control experiments which enable us to
return answers to the questions just raised. But there is
just as keen a desire on our part to test man under the
same conditions, and to state the results in both cases in
common terms.
The man and the animal should be placed as nearly as
possible under the same experimental conditions. Instead
of feeding or punishing the human subject, we should ask
him to respond by setting a second apparatus until stand-
ard and control offered no basis for a differential response
Do we lay ourselves open to the charge here that we are
using introspection? The reply is, Not at all; while we
might very well feed the human subject for a right choice
and punish him for a ,wrong one, and thus produce the re-
sponse if the subject could give it, there is no need of going
to extremes even on the platform we suggest. But it should
be understood that we are merely using this second method
as an abridged behavior method. 5 We can go just as far
4 He would have exactly the same attitude if he were conducting
an experiment to show whether an ant would crawl over a pencil laid
across the trail or go around it
5 We should prefer to look upon this abbreviated method, where
the human subject is told in words, eg, to equate two stimuli, or to
in words whether a given stimulus is present or absent^ etc., aj
A BEIIAVIORISTIC PROGRAM 15
and reach just as dependable results by the longer method
as by the abridged. In many cases the direct and typically
human method cannot be safely used Suppose that
we doubt the accuracy of the setting of the control instru-
ment, in the above experiment, as we very likely do if a
defect in vision is susmttct! It is hopeless for us to get
his introspective report. He will say: "There is no
difference in sensation, both are reds, identical in quality ? '
But suppose we confront him with the standard and the
control and so arrange the conditions that he is piujslied
if he responds to the control but not if to the standard.
We then interchange the positions of the standard and the
control at will and force him to attempt to respond to the
one and not to the other. If he can learn to make the
adjustment even after a large number of trials it is evident
that the two stimuli do afford the basis for a differential
response. Such a method may sound nonsensical, but It is
believed that we shall have to resort increasingly to just
such methods where we have reason to distrust the language
method.
There is hardly a problem in human vision which is not
also a problem in animal vision mention may be made of
the limits of the spectrum., threshold values, absolute and
relative, flicker, Talbot's law, Weber's law, field of vision,
the Purkinje phenomenon etc. Every one can be worked
out by behavior methods. Many of them are being worked
out at the present time.
All of the work upon the senses can be consistently car-
ried forward along the lines we have suggested for vision.
Our results will, in the end, give an excellent picture of
what each organ stands for in the way of function. The
the language method in behavior. It in no way changes the status
of experimentation. The method heoomes possible merely by virtue
of the fact that in the particular case the experimenter and his
animal have systems of abbreviated or shorthand behavior signs
(language) , any one of which may stand for a habit belonging to the
repertoire both of the experimenter and his subject To make the
da In obtained by the language method virtually the whole of behavior
or to attempt to mold all of the data obtained by other methods
in terms of the one which has by all odds the most limited range
is putting the cart before the horse with a vengeance.
16 PSYCHOLOGY AND BEHAVIOR
anatomist and the physiologist may take our data and
show, on the one hand, the structures which are responsible
for these responses, and, on the other, the physico-chemical
relations which are necessarily involved (physiological
chemistry of nerve and muscle) in these and other reac-
tions.
To the behaviorist's position thus briefly outlined some
serious objections are sure to be raised. It may be argued
that one might, if he were sufficiently foolhardy, hold such
a view if the study of sensory responses were all that is
demanded of the -. " ' *- But, alas, since imagery
and affection are also fundamental elements (or processes?)
of consciousness, the behaviorist, it is to be regretted, must
be handed his passports Before accepting them let us
examine the nature of the supposed mental existences
which refuse to listen to the siren voices of the behaviorists.
The image as a form of implicit behavior. The most
serious obstacle in the way of a free passage from struc-
turalism to behaviorism is the " centrally aroused sensa-
tion " or " image." If thoughts go on in terms of centrally
aroused sensations, as is maintained by the majority of
both structural and functional psychologists, we should
have to admit that there is a serious limitation on the side
of method in behaviorism. Imagery from Galton on has
been the inner stronghold of a psychology based upon
introspection. All of the outer defenses might be given
over to the enemy, but the cause could never wholly be
lost so long as the pass (introspection) to this stronghold
(image) could be maintained.
So well guarded is the image that it would seem almost
foolhardy for us to make an attack upon it. If we did not
perceive certain signs of weakening on the part of the
garrison it would seem best to agree with Professoj^Oattell
that the position of the behaviorist is too radical, and that
we should better admit the claims of imagery and try to
work out a scheme for behaviorism which will embrace the
image. Suppose we consider this aspect of the question
first- does the inclusion of the image weaken the claims
of the behaviorist? It must be admitted that it does.
IMPLICIT BEHAVIOR 17
Take a case like that ordinarily urged. Some one suggests
m words that you borrow one thousand dollars and go
abroad for a year. You think over the situation the
present condition of your research problems, your debts,
whether you can leave your family, etc. You are in a
brown study for days trying to make up your mind. Now
the train of thoughts going on in your mind, according to
the upholders of the image, has no adequate behavior
counterpart while it is in transit. The behaviorist, ob-
serving you, might note that your appetite had departed,
that you were smok'u^ and drinking more than usual, and
that you were distrait Finally, experimental tests might
show that your ability to make fine coordinations had been
seriously interfered with, and that your dynamometric
threshold was lowered, and so on ad infinitum. The intro-
spectionists would say that all of these tests failed to give
anything like a complete record of your ' * mental content ? '
or of the " totality of conscious processes." Indeed, they
would urge that such tests have only an analogical refer-
ence. Only direct observation of the mental states them-
selves by the method of introspection will ever tell whether
you are grieving over past sins or are really trying to reach
a decision about going abroad ! If we grant this, and such
an impulse is very strong, the behaviorist must content
himself with this reflection : ' * -I care not what goes on in
his so-called mind; the important thing is that, given the
stimulation (in this case a series of spoken words), it must
produce response, or else modify responses which have been
already initiated. This is the all-important thing, and I
will be content with it." I e., he contents himself with
observing the initial object (stimulation) and the end
object (the reaction). Possibly the old saying, " half
a loaf is better than no bread at all," expresses the atti-
tude the behaviorist ought to take; and yet we dislike to
admit anything which may be construed as an admission of
even partial defeat
Peeling so, it seems wisest, even at the cost of exposing
the weakness of our position, to attack rather than to re-
main upon the defensive. We spoke above of certain signs
18 PSYCHOLOGY AND BEHAVIOR
of disaffection and mutiny among the ranks of the faithful.
These signs manifest themselves in three different ways:
(1) The attempt on the part of Woodworth, Thorndike,
and others to question the dogma of the image and to show
that thought processes may go on independently of imagery
or, indeed, even independently of peripherally initiated
processes. To this last contention we do not accede, as
we shall undertake later to show. (2) The failure on the
part of the most earnest upholders of the doctrine of the
centrally aroused sensation to obtain any objective experi-
mental evidence of the presence of different image-types.
Reference here is made to the researches of Angell and of
Fernald. Although these ivnters in no way suggest such a
conclusion, it seems to us that the way is paved, by reason
of their findings, for the complete dismissal of the image
from psychology. Furthermore, most psychologists them-
selves are willing to admit that introspection furnishes no
guide for the determination of one's own image-type In
this field, above all others, introspection, if it is a legitimate
method at all, ought to yield its best results. It is just here
that it has failed, except in the case of a few fortunate men
who seem to have become " adept " in the use of it. "We
who are less happy in its use must forever do without this
wonderful Aladdin's lamp, which, upon demand, illumines
the dark places of the human mind. (3) The attempts even
of the structuralists to reduce the so-called higher thought
processes to groups of obscure organic processes We have
in mind the recent work on recognition, abstraction, etc.
All of these tendencies, initiated by the psychologists
themselves, lead directly over to our principal contention,
viz , that there are no centrally initiated processes 6
The environment in the widest sense forces the forma-
There are probably in most cases kinsesthetic substitutes for
imagery. Concurrently with the faintly articulated word apple there
arise associated kmaesthetic impulses m eye muscles. If these latter
are strong one can see how the fiction of visual imagery might arise.
Mead has already spoken for the existence of a strong tactual and
kinsesthetic element (grasping, handling, etc ) m all forms of per-
ception and in imagery. Dunlap has rejected the centrally aroused
content in the image.
IMPLICIT BEHAVIOR 19
tion of habits These are exhibited first in the organs
which are most mobile : the arms, hands, fingers, legs, etc.
By this we do not mean to imply that there is any fixed
order in their formation. After such general bodily habits
are well under way, speech habits begin All of the recent
work shows that these reach enormous complexity In a com-
paratively short time Furthermore, as language habits
become more and more complex behavior takes on refine-
ment: short cuts are formed, and finally words come to be ?
on occasion, substituted for acts. That is, a stimulus which,
in early stages, would produce an act (and which will
always do so under appropriate conditions) now produces
merely a spoken word or a mere movement of the larynx
(or of some other expressive organ) 7
When the stimulus produces either an immediate overt
response (as, eg, when John is told to go to the side-
board and get an apple taking it for granted that he goes) ,
or a delayed overt response (as, e.g., when an engineer is
asked to think out and make an apparatus for the conver-
sion of salt water into sweet, which may consume years
before overt action begins), we have examples of what we
may call explicit behavior. In contrast to behavior of
this type, which involves the larger musculature in a way
plainly apparent to direct observation, we have behavior
involving only the speech mechanisms (or the larger
musculature in a minimal way ; e g., bodily attitudes or
sets). This form of behavior, for lack of a better name,
we may call implicit behavior. 8 Where explicit behavior
is delayed (ie., where deliberation ensues), the interven-
ing time between stimulus and response is given over to
implicit behavior (to " thought processes").
Now it is this type of implicit behavior that the intro-
spectionist claims as his own and denies to us because Its
neural seat is cortical and because it goes on without ade-
quate bodily portrayal. Why in psychology the stage for
7 These substitutes are discussed in detail on p 332
^t may be said in passing that the explicit and implicit forms
of behavior referred to throughout this book are acquired and not
congenital.
20 PSYCHOLOGY AND BEHAVIOE
the neural drama was ever transferred from periphery to
cortex must remain somewhat of a mystery. The old Idea
of strict localization of brain function is in part responsible.
Religious convictions are even more largely responsible for
it. It is not meant by this that the men originally making
the transfer were aware of this religious tendency at all
"When the psychologist threw away the soul he compromised
with his conscience by setting up a " mind " which was to
remain always hidden and difficult of access 9 The transfer
from periphery to cortex has been the incentive for driving
psychology into vain and fruitless searches for the unknown
and unknowable. Had the idea of the image not taken
such firm hold upon us we would never have originated
the notion that we are seeking to explain consciousness.
We would have been content to study the very tangible
phenomena of the growth and control of explicit and
implicit habits,
It is implied in these words that there exists or ought to
exist a method of observing implicit behavior. There is
none at present The larynx and tongue, we believe, are the
loci of most of the phenomena. If their movements could
be adequately portrayed we should obtain a record similar
to that of the phonogram. Certainly nothing so definite
as this could be obtained, but we should get a record, at
least, which would largely reveal the subject's word-habits,
which, if we are not mistaken, make up the bulk of the
implicit forms of behavior. 10
9 The tendency to make the brain itself something more than a
mechanism for coordinating incoming and outgoing impulses has been
very strong among psychologists and even among psychologically in-
clined neurologists. A still wilder hypothesis is held in regard to the
neural impulse. According to many psychologists we are taught that
an incoming impulse may be held in statu quo for long periods of
time, or at least that it may ramble around in the nervous system
for an indefinite period of time until it can "obtain possession of
the motor field," at which time it exerts its effect. So far as we know
no such thing occurs. The nervous system functions in complete arcs
An incoming impulse exerts its effect relatively immediately upon, one
system of effectors or another, as shown by inhibition, reinforcement,
summation, phenomena in the muscle in operation, or by inciting
wholly new effectors to activity.
10 See the recent work of Anna VTvc/oikowska, Psycfoologieal Re-
view, November, 1913, p, 448. See summary, p. 326.
AFFECTION AS BEHAVIOR 21
Now it is admitted by all of us that words spoken or
faintly articulated belong really in the realm of behavior
as do movements of the arms and legs. If implicit be-
havior can be shown to consist of nothing but word move-
ments (or expressive movements of the word-type) the
behavior of the human being as a whole is as open to
objective control as the behavior of the lowest organism.
Affection as a form of instinctive behavior. Affection
is the other stumbling-block in the way of our main thesis.
It is needless for us to enter into a lengthy discussion of
the various views of affection It is sufficient to call at-
tention to the generally accepted position that affection
is a mental process distinct from cognition. Both Angell
and Titchener in this country admit the independence of
the two. In Germany likewise, with the exception of the
followers of Stumpf, the independence is admitted In-
deed, as it is well known, Wundt and his pupils are at-
tempting to introduce into affection the same wealth of
detail they have already succeeded in bringing into cogni-
tion. We refer to the addition to the elementary processes of
pleasure-pain, those of strain-relaxation, excitement-calm.
In maintaining his position as to the independence of the
two processes, Titchener states that affection and sensation
are closely similar in the following respects. Both possess
certain common attributes, viz , quality, intensity, duration,
Sensation possesses the additional attribute of clearness,
which affection lacks. " The lack of the attribute of clear-
ness is sufficient in itself to differentiate affection from
sensation; a process that cannot be made the object of
attention is radically different, and must play a radically
different part in consciousness, from a process which is
held and enhanced by attention." Furthermore, the lack
of clearness distinguishes affection from organic sensation
the cognitive processes with which it is most closely allied.
On the whole, while sensation and affection are closely
allied, " the difference is so great that we have no choice
but to rank affection in human psychology as a second type
of mental element, distinct from sensation."
Adherents of the view that affection is merely an attri-
22 PSYCHOLOGY AND BEHAVIOR
bnte of sensation have not been lacking Kulpe has been
given credit for <1 . o^-Vi 1 '.: this assumption.
There remains the view in contrast to the one first out-
lined, advanced principally by Stumpf and accepted and
amended by Helen Thompson Woolley, viz , that affection
is really organic sensation. The theory as advanced by
Stumpf is all but unintelligible in view of the fact that the
simplification that he obtains by his reduction is more than
offset by the complexity he introduces when he states that
the emotions, in addition to the complex of sensations, eon-
tain a mysterious " kernel/' Mrs. Woolley, while rejecting
the " kernel " hypothesis, insists that affection can be
identified with sensation. She gives 210 clear reason for
the solidarity and distinctness of the two groups, nor for
the rather constant presence of the one or the other of these
two groups. Stumpf no more than she meets these two
points.
The Stumpf- Woolley view may be modified and stated
in more definite terms. Every stimulus which calls out
either overt or delayed response arouses concomitantly
(reflexly) a definite and complex group of afferent impulses
from tissue not specified definitely by the authors. We
assume that the tissue in question belongs to the reproduc-
tive organs and to the related erogenous zones. The area
involved in sex functions embraces a much wider zone
than that of the sex organs proper. The erogenous zones
are in infancy widely distributed throughout the body sur-
faces. Only gradually does the sex organ come to be looked
upon as the focus of sex experience. Even in the case of
most adults certain of these primitive zones remain func-
tional, as, e.g., the nipples, etc.
This area as a whole may be looked upon as initiating
impulses of two fundamental kinds: (1) a group connected
with tumescence and rhythmical contractions of other
muscular tissue and with increases in the quantity of the
various secretions. This group, if functioning alone, as it
does in cases of sex response, would lead to the expansive
or seeking movements, and nVt- , ]\ to the unfolding of
the instinctive mechanism of the act of reproduction (end-
AFFECTION AS BEHAVIOR 23
ing in the orgasm). (2) A group connected with the
shrinkage of the sex organs, relaxation of other muscular
tissue, and with inhibition of secretion. These impulses,
gaining the motor centers, would, if no others inhibitory in
character were present, release movements of avoidance.
In order to bring this conception of the sensory character
of affection in line with our general scheme, it is necessary
to suppose that the impulses from the erotic tissues func-
tion as do the impulses arising from other receptors, i e ,
looking at it from a neurological standpoint, there is a
definite system of reflex arcs running from these regions
(both enteroceptive and proprioceptive impulses are in-
volved) to the muscles. This, as far as we know, is thor-
oughly established In order to illustrate the point, let
us take the neurophysiological situation at the moment of
sex excitement.
"When a definite sex object (female) appeals to any one
receptor, the eye, the ear, or the nose of the animal, grant-
ing a certain physiological condition of the animal (i.e.,
the proper season of the year, period of sex excitement,
etc, : in general, since seasonal rhythms are not so marked
in the male, the animal must be in a receptive condition for
such stimuli), several sets of arcs begin to function: (a)
one leading from the distance receptor (aroused by the sex
object) to the striped muscles, tending to produce a
heightened tonus in the skeletal muscles. Movements in
the striped muscles do not become overt until definite im-
pulses are sent in from the sex zones. When these are
present with sufficient intensity, overt seeking movements
begin. The impulses from the sex zones are aroused by
the second set of arcs: the initial impulse aroused by the
sex object while arousing tonus in the striped muscle (ft)
passes out (via the white rami) also to the appropriate
sympathetic ganglia. When these neurones are stimulated,
changes are produced in the circulatory, glandular,
secretory and muscular mechanisms, possibly of the char-
acter described in (1) above, p. 22. As soon as these
effectors are thrown into activity they set up a character-
istic group of afferent impulses (they represent % definite
24 PSYCHOLOGY AND BEHAVIOE
set of bodily reverberations, to use William James 7 term,
and hence m current ;>\ J.i/louitj] terminology they are
the bodily substrata of the emotion of pleasantness), which
upon reaching the motor centers, produce the actual seek-
ing movements in the striped muscles, "When the situation
is prolonged, i.e., when definite receptors other than the
initial one become stimulated by the sex object by reason
of the seeking movements, the complete act of reproduction
follows. On. the other hand, if the general ' ; - , ' ," *
condition is different (organism not receptive to sex
stimuli) there again arise (a) an increased tonus in the
striped muscles and (&) activity in the sympathetic
mechanisms, cheeking of secretion, lack of tonicity in the
muscles, etc., which arouse, in turn, a definite group of
afferent impulses (" bodily substrata of unpleasantness ")
that tends definitely to set free the avoiding reaction Since
the mechanisms involved in sex are fundamental, it seems
reasonable to suppose that every object, either instinctively
or through habit, tends to throw them into the one or the
other form of action, of which we have just spoken. 11
Certainly many objects (non-affective stimuli, stimuli
11 In fact we see no escape from such a conclusion, if the Stumpf-
Woolley hypothesis is adopted. By its own admission, this theory
must be able to account for several so-called observed facts We state
them from the standpoint of current psychology.
1. That there should be two well-marked and opposite groups
2. That they always accompany perceptions or images.
3. That they are evanescent and hard to observe (Titchener says
they cannot be " observed " )
4. That the image carries its own tone which need not be, and
often is not, the same as that given in the original perception
5. That there should at times be neutral perceptions and images,
and that tone tends to disappear with frequency of appearance
of the f miniating obiect
Were we interested in arguing for a structural psychology, we
could readily show how 1, 2, 4, and 5 follow immediately from our
premises In regard to 3, it could be said ( 1 ) that evanescence would
be the character expected in all cases except that of direct sex stimula-
tion, since these arcs are functioning onlv eliprhllv nlong with the arcs
from distance receptors to voluntary mii'-clo* uludi are functioning
at high intensity Titchener's statement that they cannot be attended
to is a pure assumption in the interests of a structural criterion.
Pathological cases tend to support the view that at certain times
affective' proops-i"- 01, on this view, affective sensations, are often th$
onlv sensations \\hich are attended to-
" AFFECTION " OPEN TO EXPERIMENTATION 25
distantly or not at all connected with sex stimuli) do not,
in the beginning, arouse these groups, but through the
ordinary mechanism of habit come later to arouse faintly
the one or the other (substitution, p. 272) There is
evidence in sexual pathology to show not only that such
habit connections are formed, but also that they can be-
come more fundamental than the primal instinctive path-
ways, as is shown in the use of phallic symbols, fetishes, etc
We thus seem to be able to connect so-ealled affective
processes definitely with general processes of adjustment.
Behavior, while possibly not immediately interested in such
processes, need not escape its share of work m their study
On the one hand, the student of behavior, when some of the
more passing problems are solved, will be interested in the
types of stimuli which jointly arouse movements in the
striped muscles and in the unstriped muscles and glandular
tissues in the sex zones, and in the finer analysis of the
movements themselves. He will try to determine whether
such stimuli arouse these movements by means of inherent
connections or through habit Furthermore, he will try to
determine whether the movements of the glands, etc , actu-
ally set up sensory impulses in the sexual zones, and whether
they have the effect called for upon his theory. This can be
attacked in two ways: (1) probably by actual plethysmo-
graphic and galvanometric studies upon the sex organs
themselves; (2) by the elimination of the sensory avenues
which lead from these zones to the central system. His
primary interest, however, will be engaged in determining
the effect of these impulses upon overt movement, since it
is highly probable that they are responsible for so-called
preferences, which play sueh an enormous role in the
daily life of the human being 1 , and for the many forms of
artistic, aesthetic, and religious modes of response. To
those who have inherent objections to admitting that the
aesthetic, artistic, and religions sides of life are at bottom
sexual, this view will not sound convincing. Fortunately,
thanks to the. work of the scientific students of social
phenomena we are fast losing our prejudices against admit-
ting the sex reference Q| all
26 PSYCHOLOGY AND BEHAVIOR
It must be confessed that wholly new methods will have
to be devised for the pursuit of studies in this field. There
is still hope, as was suggested above, for galvanomctrie
and ; " '\\ - -<.;'* experimentation. You may object
that expressive methods have already failed to show any
constant physiologie.il processes occurring In conjunction
with the examination of " pleasant 7> and " unpleasant "
objects. We have worked for years upon the expressive
methods and no one is more ready to admit their failure
in the past. Our present feeling is that we have taken our
plethysmograms from the wrong organs. Whether there
are too many technical difficulties in the way of the objec-
tive registration of the many delicate changes in the sex
organs (circulation, secretion, etc.) remains for the future
to decide.
The result of our examination into the nature of both
image and affection seems to indicate that after all the be-
haviorist can bring them into his general scheme of work
without in any way \\ earning his position. It would thus
seem that there is no field which an introspective psy-
chology legitimately can call its own.
Will there be left over in psychology a world of pure
psychics, to use Yerkes' term 1 ? The plans which we most
favor for psychology lead practically to the ignoring of
consciousness in the sense In which that term is used by
psychologists today. We have virtually denied that this
realm of psychics is open to experimental investigation.
We do not wish to go further into the problem because its
future rests with the metaphysician. If you will grant the
behaviorist the right to use consciousness in the same way
that other natural scientists employ it i e., without making
consciousness a special object of observation you have
granted all that our thesis requires.
Summary. 1 Human psychology has failed to make
good its claim as a natural science. Due to a mistaken
notion that its fields of facts are conscious phenomena and
that introspection is the only direct method of ascertaining
these facts, it has enmeshed itself in a series* of speculative
questions which, while fundamental to its present tenets,
SUMMARY 27
are not open to experimental treatment In the pursuit of
answers to these questions, it has become further and fur-
ther divorced from contact with problems which vitally
concern human interest
2. Psychology, as the behaviorist views it, is a purely
objective, experimental branch of natural science which
needs introspection as little as do the sciences of chemistry
and physics. It is granted that the behavior of animals
can be investigated without appeal to consciousness.
Heretofore the viewpoint has been that such data have value
only in so far as they can be interpreted by analogy in
terms of consciousness. The position is taken here that the
behavior of man and the behavior of animals must be
considered on the same plane ; as being equally essential to
a general understanding of behavior. It can dispense with
consciousness in a ^\ ' 1 . * sense. The separate ob-
servation of " states of consciousness " is, on this assump-
tion, no more a part of the task of the psychologist than of
the physicist. We might call this the return to a non-re-
flective and naive use of consciousness. In this sense
consciousness may be said to be the instrument or tool with
which all scientists work. Whether or not the tool is
properly used at present by scientists is a problem for
philosophy and not for psychology.
3. From the viewpoint here suggested the facts on the
behavior of amoebae have value in and for themselves
without reference to the behavior of man. In biology
studies on race differentiation and inheritance in amoebae
form a separate division of study which must be evaluated
in terms of the laws found there. The conclusions so
reached may not hold in any other form. Regardless of
the possible lack of generality, such studies must be made
if evolution as a whole is ever to be regulated and con-
trolled. Similarly the laws of behavior in amoebae, the
range of responses, and the determination of effective
stimuli, of habit formation, persistency of habits, inter-
ference and reinforcement of habits, must be determined
and evaluated in and for themselves, regardless of their
generality, or of their bearing upon such laws in other
28 PSYCHOLOGY AND BEHAVIOR
forms, If the phenomena of behavior are ever to be brought
within the sphere of scientific control.
4. This suggested elimination of states of consciousness
as proper objects of investigation in themselves will remove
the barrier which exists between psychology and the other
sciences. The findings of psychology become the func-
tional correlates of structure and lend themselves to ex-
planation in physico-chemical terms.
5 I\v* o"< ^- as behavior will, after all, have to neglect
but few of the really essential problems with which psy-
chology as an introspective science now concerns itself. In
all probability even this residue of problems may be
phrased in such a way that refined methods in behavior
(which certainly must come) will lead to their solution.
BIBLIOGRAPHY
ANGELL, JAMES B., " Behavior as a Category of Psychology /' Psych,
Rev, 1913, XX, 255
BODE B H., "Psychology as a Science of Behavior," Psvcli Rev,,
1914, XXI, 46.
DUNLAP, K , A System of Psychology. New York, Scribner's, 1912,
"The Case Against Introspection," Psych. Rev., 1912,
IX, 404.
" Images and Ideas/' The Johns Hopkins University
Circular, 1914, No 3, 25.
LOVEJOY, A O, "On the Existence of Ideas,*' The Johns Hopkins
University Circular, 1914, No. 3, 42
MARSHALL, H. R., "Is Psychology Evaporating?" Jour. Philos., 1913,
J\.y 710.
MEAD, G. H, "Concerning Animal Perception/' Psych. Rev, 1907,
XIV, 383.
TITCHENEE, E. B , " Prolegomena to a Study of Introspection," Am.
Jour. Psych , 1912, XXIII, 427.
" The Schema of Introspection," ibid , 485,
" A Text-Book of Psychology " New York, Macmillan,
1910.
WARREN, H C , " The Mental and the Physical/' Psych. Rev., 1914,
XXI, 79
WATSON, J. B, "Image and Affection in Behavior," Jour Philos.?
Psych, and Set MetK., 1913, X, 421
"Psychology as the Behaviorist Views It," Psych Rev..
1913, XX, 158
WOOLLEY, HELEN T., " Sensory Affection and Emotion," Psych Rev ,
1907 XIV, 329
B, K. M., Introduction to Psychology. New York, Henry Holt,
1911*
CHAPTER II
SOME PROBLEMS ENUMERATED
No lack of "' * behavior problems, Field versus laboratory
studies ' of problems. I. Sense organ processes. In-
troduction. 1. Vision Necessity for considering anatomical
structure. Reflex responses to light General division of prob-
lems in vision (a) White 1 i e jUt vision (6) Response to
monochromatic light. 2 Audiiior. Grouping of problems
(1) Response to pendular vibrations (a) Range of sensitivity.
(6) Localization. (c) Response to clangs (2) Response to
a-periodic vibrations (a) Stimulus threshold ( 6 ) Difference
threshold. (3) Response to ordinary sounds in the environment.
(a) Instinctive repertoire of sounds, (6) Modification of
vocal sounds through social influences (c) Influence of such
sounds upon mates 3 Olf action and gustation. Lack of defi-
r f< V * " T * ,t smell functions Problems in olfaction.
] i. u i ''<.<,.' "'in habit formation Problems In ,j" -\'.\ iu* 1
. Cutaneous, proprio- and entero-eeptive systems. 1\- ITU i u ^
in the way of making satisfactory tests. Proprio-ceptive system.
Cutaneous system as a distance receptor II. Instinctive func-
tions Introduction Some types of instinctive response The
animal's instinctive mode of attack on problems Instinct and
habit III. Learning TntrodiHrlon Grouping of problems.
(1) Perseveimco method \2) I iKitnov <>: training methods.
(3) Complex forms of learning IV. Correlations Introduc-
tion. Lack of behavior data handicaps the neurologist. Gen-
eral aim of behavior. Summary.
No lack of unity in the problems of behavior. In the
preceding discussion of the relation of behavior to psy-
chology several problems which face the behaviorist were
touched upon. In the present chapter the attempt is made
to develop them in such a way that their unity may be
traced. At the present time behavior appears to the casual
observer to consist of a large number of rather isolated bits
of research which may be classified here and there under
sciences already well recognized. This is a serious mistake
and one which will handicap advance in this subject in the
years to come. The sketch of the problems given below
may be looked upon as a program for unified and sys-
29
30 SOME PROBLEMS ENUMERATED
tematic work rather than as a complete expression of the
scope and aim of behavior. Even such an immature and
hasty sketch of the problems confronting us will, it is hoped,
offer convincing evidence that the work of the behaviorist,
while closely related to that of the zoologist and the physi-
ologist, is, nevertheless, independent.
Field versus laboratory studies. Before presenting the
special groups of problems of behavior, it is necessary to
face one criticism often urged against the young science,
viz., that of the narrowness of its problems In the last
few years behavior has become mainly a laboratory science.
This has led a large number of men who have devoted their
lives to the field activity of animals, such as "^uivouc:^
Wesley Mills, and a wide group of naturalists, to say that
the laboratory is not a suitable place in which to study
behavior. According to them only highly sporinlizal prob-
lems can be attacked in the laboratories. True and un-
trammeled expressions of habit and instinct and of the
uses of the senses must be sought for in the field activity
of animals. Unquestionably it is a mistake to neglect field
work. It requires no lengthy argument to show that gen-
eral orientation with respect to the daily routine of
adjustments of animals and an accurate knowledge of the
environmental conditions under which animals live can
come only through field observation. No one who has ever
used monkeys as subjects can help feeling how handicapped
we are at the present time in our laboratory studies of
simian life through lack of systematic knowledge of their
life in the open. What is true in the case of the primates
is true with respect to nearly every other animal form. It
is highly improbable that any of us could describe in a
really helpful way the daily routine of the domestic fowl
or the dog. We are even less familiar with the seasonal
routine of animals, such as hibernation, migration, etc. On
the other hand, it can hardly be claimed that mere observa-
tion of field activity, even when made by competent
students, can ever hope to answer in any scientific way the
basal questions which must be asked about the mechanics
of stimulus and response. Even the most superficial ob-
FIELD OIWEEVATIONf 31
servation of field activity by the trained student raises at
once a host of questions, the answers to which must be
sought in the laboratory is the cat visually stimulated
by a moving object in steadily decreasing intensity of light
for a longer time than the human being, or does this animal
stalk its prey after it is lost to sight through a highly de-
veloped sense of smell? Do the birds which feed upon
decaying animal matter sense it through smell or sight ! A
few minutes' observation will show that while many of our
problems are raised in the field, the scientific answers to
them come through the laboratories. But granting the in-
dispensableness of the laboratory, it is well, after finishing
with our animal, to observe him yet again in the field.
One can readily conceive of some such situation as the
following: after years of analytical study upon the tem-
perature, visual, olfactory, and auditory senses of a given
species of bird, one might predict the utter absurdity of
that bird's being able to get back to its home when carried
out to sea for a distance of one thousand miles. Yet on
specific test we find the bird able to do this. Of course our
laboratory study was incomplete, or we should have been
able to predict what actually happened. Yet the incom-
pleteness of the laboratory study would be discovered only
when we, so to speak, began to put the bird together again!
Without developing the subject further, it would seem
obvious that there is no conflict between field work and
laboratory work. The field is both the source of problems
and the place where the laboratory solutions of these prob-
lems are tested.
Grouping of problems. The vast majority of the prob-
lems in both human and animal behavior may be grouped
under one or another of three divisions: I. Sense organ
functions II. Instinctive function. III. Habit forma-
tion. In addition to these large divisions in which the
subjects for research lie, there remains the work of, IV.
Correlation: first, among behavior data giving both an
ontogeny and a phylogeny of behavior ; second, of behavior
with structure ; and finally the correlation of behavior and
structure with physico-chemical processes. We shall take
32 SOME PROBLEMS ENUMERATED
up these divisions separately and attempt to show in some
detail what special questions gather around them. Later
we shall discuss the apparatus and methods which are
employed in attempting to return answers to them.
I. SENSE-ORGAN PROCESSES
Introduction. The study of sense functions should come
prior, logically, to the study of either instinct or learning,
since neither instinctive action nor learning can be thor-
oughly understood until we have definite knowledge about
the sense processes of the animal under experimentation.
In actual practice, work upon instinct, learning, and the
sense organs has been, carried forward simultaneously. It
is very difficult to study any one of these subjects by itself.
Jn the learning of mazes and puzzle boxes both by animals
and human beings, many facts appear which are of impor-
tance to a study of instincts and senses. On the other
hand, our knowledge of sense-organ processes is obtained
in two ways: (1) by forcing the animal to form sensory
habits (p. 187) ; and (2) by noting the inherited modes of
response to controlled stimuli. In the study of the speciral
sensibility of the chick (limits) one finds that the chick is
positive to light, i.e , will go towards a lighted compart-
ment from the first, without learning. The relations among
these three divisions seem at first sight to be too f com plicated
for analytical work. It will be seen from the chapters that
follow that the difficulties are more apparent than real.
1. Vision
Necessity for consideration of anatomical structure.
Before making an extensive study of vision in any par-
ticular animal form, it is essential to study carefully the
structure of its eye and the visual conduction systems;
and to have at least some knowledge of the animal's general
anatomy. Questions as to the presence or absence of a
fovea ; whether both rods and cones are present, and their
distribution j whether the animal has the essential structure
PROBLEMS IN VISION 33
for binocular vision, whether there are accommodation,
convergence, and divergence are met at every turn in
our work Not to have orientation with respect to them
means a lack of thoroughness in the setting of problems
for the study of vision. It is equally essential (where
possible) to make a study of the animal's visual environ-
ment and of the field habits and instincts which seem to
depend upon visual stimuli.
Reflex responses to light. In the observations of the
movements of lower forms of plants and animals, one is
often struck by the remarkable sensitivity of some of the
oi'Lvi M i* Tiiirl' *! Stentor, and by the equally notice-
able lack of sensitivity in other forms, e g , Paramecium.
The general responsiveness to light is equally observable
in the higher animals as well. The tern remains absolutely
quiescent in total darkness. The chick's behavior on the
sudden elimination of light is equally remarkable It re-
mains at first quite still, as though stunned, and then be-
gins aimless movements, pecking, turning, running
against objects, etc. The rats, and probably other rodents
as well, require separate laboratory work in order to tell
whether vision is functional at all. Vision seems to func-
tion in some animals (nocturnal animals) only in very
weakened intensity of light, strong light producing cessa-
tion of activity equally as well as absolute darkness
General divisions of problems in vision. The problems
in vision proper may be considered under (a) white light
vision, (&) monochromatic light vision, (c) the role
of vision in daily life (mutual relations among the
senses).
White light vision. (a) One of the first problems in
white light vision is the determination of the delicacy of
the mechanism. "What absolute intensity of light can the
animal respond to with dark adapted eye, and with light
adapted eye? What difference in intensity between two
lights is it necessary to maintain in order to give a basis
for a differential response! (Weber's law.) Are re-
sponses to light positive or negative 1 ? Under what condi-
tions may a positive tendency be changed to a negative?
34 SOME PROBLEMS ENUMERATED
Can it be so changed in any of the vertebrates without in-
volving habit formation! We are led over almost at once
into a consideration of darkness and light adaptation in
animals with cone retinas and in those possessing rod
retinas, the difference in the response to white light be-
tween animals with image forming eyes and those with eye
structures too undeveloped to form images. Another for-
ward step in the work on vision is the determination of the
animal's behavior with respect to form and size, vertical
and horizontal lines, moving and stationary stimuli, pat-
terns, etc.
Response to monochromatic light. The difficulty of
gaining accurate knowledge of animals' monochromatic
light responses is very great. Heretofore the work has
been carried out by methods and apparatus which can
never yield accurate results. The first step in the study of
any animal's color responses should be the determination
of the limits of its spectral sensitivity The second step
should be the determination of the energy of stimulus
necessary to yield threshold responses at various points
in the spectrum* Enough places should be chosen to
enable the experimenter to plot the sensitivity curve
tlirouirhoui the spectrum. This threshold curve will serve
in several connections. In the first place it enables us
to say immediately whether both lights used in the work
on sensory habits lie above the animal 's threshold, and con-
sequently whether both are effective stimuli. We have
learned the necessity for this after the loss of several
months' work. In the second place it will largely increase
our knowledge of the variations of intensity which it is nec-
essary to make the monochromatic lights undergo in order to
test for sensitivity to u,Hc-l< i MLZ::s ENUMERATED
mon activities by the voice of the mate, parent or com-
panion (sex activity, feeding, flight, etc). While these
problems possibly may have the flavor of the tl manufac-
tured " or laboratory variety, a little field observation will
quickly show that they are really fundamental. Hodge
would have us believe that the deer has an almost unbeliev-
ably acute sense of hearing. How can we dispute it or
confirm it in the deer or any other animal until we have
made threshold tests under standard conditions f Kaliseher
tells us of the absolute pitch memory of dogs. Who can
prove it or disprove it except by the laboratory type of
test! Until these exact and rigorous tests are made and
repeatedly confirmed by several L-ixi^t'-j.r v^ it is impos-
sible to carry forward research upon the localization of
pitch centers, experimentation upon the functions of the
cochlea, and the like.
3. Olfaction and Gustation
Lack of definite knowledge of smell functions. It is
singular that the functions of the organ of smell have
never been investigated in any complete way in any ver-
tebrate. Several investigations have been carried out upon
smell in birds and in fishes. These tests have had as their
object the determination of the fact whether those animals
use that receptor. Of the range and complexity of its
uses we have nothing. That enormous differences exist
among the smell functions of different animals there Is
little room for doubt. In addition to the problems con-
nected with the general functioning of the organ of smell 7
there are many concerning the instinctive life of the animal
which have never been explored. "We have in mind here
the positive reactions made to certain " nauseous ?? smell
stimuli, and to the apparent lack of sensitivity to the odor of
flowers and perfumes generally, etc. The human being
seems to be the only animal which responds negatively to
the class of odors which Zwaardemaker calls nauseous. 1
1 K. S Lashley finds that an Amazon parrot in his possession will
vomit at the smell of an old pipe (Class VI).
OLF ACTION AND GUSTATION 39
How much of this is due to social training and how much
to fundamental biological tendencies is not known. From
the study of j: /... I: -\v Australian tribes and from bio-
logical studies generally the conclusions seem to follow that
social conventions and training are responsible for the
negative tendencies which are so apparent in man. Still,
the evidence is not completely decisive. Certain smells in
the cultivated European are connected with definite re-
flexes: nausea and even vomiting being produced. That
our ignorance of smell functions in general is almost colossal
comes out clearly when we try to compare even in thought
the delicacy of the average human being's sense of smell
with that of certain varieties of dogs. Hunting dogs, blood-
hounds, etc., must have an almost unbelievably delicate
sense of smell. Yet when defective human beings have been
forced to depend upon this sense, they have surprised us
by the delicacy with which they use this organ. It is diffi-
cult even in field work to detect the actual uses to which
smell is put by animals. In the case of the monkey it is
quite clear that objects are rejected by this sense long before
they reach the mouth. That olfactory stimuli start seeking
movements in many vertebrate forms is also clear. The spe-
cific problems in smell are much like those in the other sense
fields. There is need of field observations to guide us in
setting problems for determining the interrelations of smell
with other sense functions, and the role smell plays in the
daily life of the animal. As in vision and in audition we
need to test the animal's range of sensitivity. For this
problem the best plan of attack would probably be that
of taking several odors from each of Zwaardemaker's nine
classes and testing in order whether the animal is positive
or negative to them Either form of response, provided
proper controls were introduced, would show that that
odor was an effective stimulus. If no such simple inherited
mode of response were present we should attempt to force
the formation of a sensory habit which would enable us to
determine whether the odor lies within the animal's range.
Extended experiments would be necessary for the determi-
nation of threshold intensities of
