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THE LIBRARY

The Ontario Institute

for Studies in Education

Toronto, Canada

Digitized by the Internet Archive
in 2008 with funding from
Microsoft Corporation

http://www.archive.org/details/animalintelligenOOthoruoft

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THE

Psychological Review

EDITED BY
J. MCKEEN CATTELL J. MARK BALDWIN

AND
CoLUMBIA UNIVERSITY PRINCETON UNIVERSITY

WITH THE CO-OPERATION OF

ALFRED BINET, EcoLe pes Haures-EtupEs, PARIs; JOHN DEWEY, UNIVERSITY OF
Cuicaco; H. H. DONALDSON, UNIversiry oF CuHiIcaco; G. S. FULLERTON,
UNIVERSITY OF PENNSYLVANIA; JOSEPH JASTROW, UNIvVERsITy oF WISs-
consin; G. T. LADD, YALE UNiversiry; HUGO MUNSTERBERG,
HARVARD UNIVERSITY; M. ALLEN STARR, COLLEGE or PHy-

SICIANS AND SURGEONS, NEW YorK; CARL STUMPF, UNI-

VERSITY, BERLIN; JAMES SULLY, UNIVERSITY
COLLEGE, LONDON.

Series of Monograph Supplements,
Vol. II., No. 4 (Whole No. 8), June, 1898.

Animal Intelligence

An Experimental Study of the Associative Processes in res

BY
eA?
EDWARD L. THORNDIKE A.M., ee
ise ae

Unwersity Fellow in Psychology, Columbia University.

THE MACMILLAN COMPANY,

4x N. QUEEN ST., LANCASTER, PA.
66 FIFTH AVENUE, NEW YORK; AND LONDON. Yd &

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TABLE OF CONTENTS.

Introduction, rs
Description of Apparatus,
Experiments with Cats,
ae “© Dogs,
ee ‘© Chicks,
Reasoning or Inference,
Imitation, ge be
se in Chicks,
es ¢¢. Cats;
a ‘¢ Dogs, ee
The Mental Fact in Association,
Association by Similarity and the Formation of Concepts,
Criticism of Previous Theories,
Deltexey Ole ASSOCIALONy G1 ou Si \ ah im) tne) et eas
Complexity of Associations, .
Number of Associations,
Permanence of Associations, . :
Intibition, of Instincts by, Efabit, 9 a) antes Se Oe oe A
PR ETORELOT Oy 5 ake Sel Cath at! Wak ant dso hain SE eee rem ae
The Social Consciousness of Animals,
TER EME Mga el iaeieatian aac SAM
Applications to Pedagogy, Anthropology, etc.,

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ANIMAL INTELLIGENCE; AN EXPERIMENTAL
STUDY OF THE ASSOCIATIVE PRO-
CESSES IN ANIMALS.

This monograph is an attempt at an explanation of the na-
ture of the process of association in the animal mind. In-
asmuch as there have been no extended researches of a char-
acter similar to the present one either in subject-matter or
experimental method, it is necessary to explain briefly its stand-
point.

Our knowledge of the mental life of animals equals in the
main our knowledge of their sense-powers, of their instincts
or reactions performed without experience, and of their reac-
tions which are built up by experience. Confining our attention
to the latter we find it the opinion of the better observers and
analysts that these reactions can all be explained by the ordi-
nary associative processes without aid from abstract, conceptual,
inferential thinking. These associative processes then, as
present in animals’ minds and as displayed in their acts, are my
subject-matter. Any one familiar in even a general way with
the literature of comparative psychology will recall that this
part of the field has received faulty and unsuccessful treatment.
The careful, minute, and solid knowledge of the sense-organs
of animals finds no counterpart in the realm of associations and
habits. We do not know how delicate or how complex or
how permanent are the possible associations of any given group
of animals. And although one would be rash who said that
our present equipment of facts about instincts was sufficient or that
our theories about it were surely sound, yet our notion of what oc-
curs when a chick grabs a worm are luminous and infallible com-
pared to our notion of what happens when a kitten runs into the
house at the familiar call. The reason that they have satisfied us
as well as they have is just that they are so vague. We say that
the kitter. associates the sound ‘ kitty kitty’ with the experience

E. L. THORNDIKE.

>
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of nice milk to drink, which does very well for a common-
sense answer. It also suffices as a rebuke to those who would
have the kitten ratiocinate about the matter, but it fails to tell
what real mental content is present. Does the kitten feel
‘« sound of call, memory-image of milk in a saucer in the kitchen,
thought of running into the house, a feeling, finally, of * I will
yun in’2” Does he perhaps feel only the sound of the bell
and an impulse to run in, similar in quality to the impulses
which make a tennis player run to and fro when playing? The
word association may cover a multitude of essentially different
processes, and when a writer attributes anything that an animal
may do to association his statement has only the negative value
of eliminating reasoning on the one hand and instinct on the
other. His position is like that of a zodlogist who should to-
day class an animal among the ‘worms.’ To give to the word
a positive value and several definite possibilities of meaning is
one aim of this investigation.

The importance to comparative psychology in general of a
more scientific account of the association-process in animals
is evident. Apart from the desirability of knowing all the facts
we can, of whatever sort, there is the especial consideration that
these associations and consequent habits have an immediate im-
port for biological science. In the higher animals the bodily
life and preservative acts are largely directed by these associa-
tions. They, and not instinct, make the animal use the best
feeding grounds, sleep in the same lair, avoid new dangers and
profit by new changes in nature. Their higher development in
mammals is a chief factor in the supremacy of that group.
This, however, is a minor consideration. The main purpose of —
the study of the animal mind is to learn the developme
mental life down throug to trace articular t
origin of human aculty. In relation to this chief purpose of
comparative psychology the associative processes assume a role
predominant over that of sense-powers or instinct, for in a study
of the associative processes lies the solution of the problem.
Sense-powers and instincts have changed by addition and
supersedence, but the cognitive side of consciousness has
changed not only in quantity but also in quality. Somehow

ANIMAL INTELLIGENCE. 3

out of these associative processes have arisen human conscious-
nesses with their sciences and arts and religions. The associa-
tion of ideas proper, imagination, memory, abstraction, general-
ization, judgment, inference, have here their source. And in
the metamorphosis the instincts, impulses, emotions and sense-
impressions have been transformed out of their old natures.
For the origin and development ee ert we must look
to these processes of association in animals. Not only
then does this department need treatment more, but promises to
repay the worker better.

Although no work done in this field is enough like the
present investigation to require an account of its results, the
method hitherto in use invites comparison by its contrast and,
as I believe, by its faults. In the first place, most of the books
do not give us a psychology, but rather a ew/ogy, of animals.
They have all been about animal zztelligence, never about
animal stupzdity. Though a writer derides the notion that
animals have reason, he hastens to add that they have marvel-
lous capacity of forming associations, and is likely to refer to
the fact that human beings only rarely reason anything out,
that their trains of ideas are ruled mostly by association, as if,
in this latter, animals were on a par with them. The history
of books on animals’ minds thus furnishes an illustration of the
well-nigh universal tendency in human nature to find the mar-
velous wherever itcan. We wonder that the stars are so big
and so far apart, that the microbes are so small and so thick
together, and for much the same reason wonder at the things
animals do. They used to be wonderful because of the
mysterious, God-given faculty of instinct, which could almost
remove mountains. More lately they have been wondered at
because of their marvellous mental powers in profiting by ex-
perience. Now imagine an astronomer tremendously eager to
prove the stars as big as possible, or a bacteriologist whose
great scientific desire is to demonstrate the microbes to be very,
very little! Yet there has been a similar eagerness on the part
of many recent writers on animal psychology to praise the
abilities of animals. It cannot help leading to partiality in de-
ductions from facts and more especially in the choice of facts

4 E. L. THORNDIKE.

for investigation. How can scientists who write like lawyers,
defending animals against the charge of having no power of
rationality, be at the same time impartial judges on the bench?
Unfortunately the real work in this field has been done in this
spirit. The level-headed thinkers who might have won valuable
results have contented themselves with arguing against the
theories of the eulogists. They have not made investigations
of their own.

In the second place the facts have generally been derived
from anecdotes. Now quite apart from such pedantry as insists
that a man’s word about a scientific fact is worthless unless he
is a trained scientist, there are really in this field special ob-
jections to the acceptance of the testimony about animals’ intelli-
gent acts which one gets from anecdotes. Such testimony is
by no means on a par with testimony about the size of a fish or
the migration of birds, etc. For here one has to deal not
merely with ignorant or inaccurate testimony, but also with
prejudiced testimony. Human folk are as a matter of fact
eager to find intelligence in animals. They like to. And
when the animal observed is a pet belonging to them or their
friends, or when the story is one that has been told as a story to
entertain, further complications are introduced. Nor is this
all. Besides commonly misstating what fact sthey report, they
report only such facts as show the animal at his best. Dogs
get lost hundreds of times and no one ever notices it or sends
an account of it to a scientific magazine. But let one find his
way from Brooklyn to Yonkers and the fact immediately be-
comes a circulating anecdote. Thousands of cats on thousands
of occasions sit helplessly yowling, and no one,takes thought of
it or writes to his friend, the professor; but let one cat claw at
the knob of a door supposedly as a signal to be let out, and
straightway this cat becomes the representative of the cat-mind
in all the books. The unconscious distortion of the facts is
almost harmless compared to the unconscious neglect of an
animal’s mental life until it verges on the unusual and marvel-
ous. It is as if some denizen of a planet where communication
was by thought-transference, who was surveying humankind
and reporting their psychology, should be oblivious to all our

ANIMAL INTELLIGENCE. 5

inter-communication save such as the psychical-research society
has noted. If he should further misinterpret the cases of mere
coincidence of thoughts as facts comparable to telepathic com-
munication, he would not be more wrong than some of the ani-
mal psychologists. In short, the anecdotes give really the
abnormal or super-normal psychology of animals.

Further, it must be confessed that these vices have been
only ameliorated, not obliterated, when the observation is first-
hand, is made by the psychologist himself. For as men of the
utmost scientific skill have failed to prove good observers in the
field of spiritualistic phenomena,’ so biologists and psycholo-
gists before the pet terrier or hunted fox often become like Sam-
son shorn. They, too, have looked for the intelligent and
unusual and neglected the stupid and normal.

Finally, in all cases, whether of direct observation or report
by good observers or bad, there have been three other defects.
Only a single case is studied, and so the results are not neces-
sarily true of the type; the observation is not repeated, nor are
the conditions perfectly regulated; the previous history of the
animal in question is not known. Such observations may tell
us, if the observer is perfectly reliable, that a certain thing
takes place, but they cannot assure us that it will take place
universally among the animals of that species, or universally with
the same animal. Nor can the influence of previous experience be
estimated. All this refers to means of getting knowledge about
what animals do. The next question is, ‘*‘ What do they feed 2”
Previous work has not furnished an answer or the material for
an answer to this more important question. Nothing but care-
fully designed, crucial experiments can. In abandoning the
old method one ought to seek above all to replace it by one
which will not only tell more accurately what they do, and give
the much-needed information how they do zt, but also inform us
what they feel while they act.

To remedy these defects experiment must be substituted for

1T do not mean that scientists have been too credulous with regard to spirit-
ualism, but am referring to the cases where ten or twenty scientists have been
sent to observe some trick-performance by a spiritualistic ‘medium,’ and have

all been absolutely confident that they understood the secret of its performance,
each of them giving a totally different explanation.

6 E. L. THORNDIKE.

observation and the collection of anecdotes. Thus you immedi-
ately get rid of several of them. You can repeat the conditions
at will, so as to see whether or not the animal’s behavior is due
to mere coincidence. A number of animals can be subjected to
the same test, so as to attain typical results. The animal may be
put in situations where its conduct is especially instructive.
After considerable preliminary observation of animals’ behavior
under various conditions, I chose for my general method one
which, simple as it is, possesses several other marked advantages
besides those which accompany experiment of any sort. It was
merely to put animals when hungry in enclosures from which
they could escape by some simple act, such as pulling at a loop
of cord, pressing a lever, or stepping on a platform. (A de-
tailed description of these boxes and pens will be given later.)
The animal was put in the enclosure, food was left outside in
sight, and his actions observed. Besides recording his general
behavior, special notice was taken of how he succeeded in doing
the necessary act (in case he did succeed), and a record was
kept of the time that he was in the box before performing the
successful pull, or clawing, or bite. This was repeated until
the animal had formed a perfect association between the sense-
impression of the interior of that box and the impulse leading to
the successfnl movement. When the association was thus per-
fect, the time taken to escape was, of course, practically con
stant and very short.

If, on the other hand, after a certain time the animal did not
succeed, he was taken out, but not fed. If, after a sufficient
number of trials, he failed to get out, the case was recorded as
one of complete failure. Enough different sorts of methods of
escape were tried to make it fairly sure that association in gene-
ral, not association of a particular sort of impulse, was being
studied. Enough animals were taken with each box or pen to
make it sure that the results were not due to individual peculiar-
ities. None of the animals used had any previous acquaintance
with any of the mechanical contrivances by which the doors
were opened. So far as possible the animals were kept ina
uniform state of hunger, which was practically utter hunger.
That is, no cat or dog was experimented on when the experi-

ANIMAL INTELLIGENCE. ff

ment involved any important question of fact or theory, unless
I was sure that his motive was of the standard strength. With
chicks this is not practicable, on account of their delicacy. But
with them dislike of loneliness acts as a uniform motive to get
back to the other chicks. Cats(or rather kittens) , dogs and chicks
were the subjects of the experiments. All were apparently in
excellent health, save an occasional chick.

By this method of experimentation the animals are put in
situations which call into activity their mental functions and
permit them to be carefully observed. One may, by following
it, observe personally more intelligent acts than are included in
any anecdotal collection. And this actual vision of animals in
the act of using their minds is far more fruitful than any amount
of histories of what animals have done without the history of
how they did it. But besides affording this opportunity for
purposeful and systematic observation, our method is valuable
because it frees the animal from any influence of the observer.
The animal’s behavior is quite independent of any factors save
its own hunger, the mechanism of the box it is in, the food out-
side, and such general matters as fatigue, indisposition, etc.
Therefore the work done by one investigator may be repeated
and verified or modified by another. No personal factor is pres-
ent save in the observation and interpretation. Again, our
method gives some very important results which are quite unin-
fluenced by azy personal factor in any way. Thecurves show-
ing the progress of the formation of associations, which are
obtained from the records of the times taken by the animal in
successive trials, are facts which may be obtained by any ob-
server who can tell time. They are absolute, and whatever can
be deduced from them is sure. Soalso the question of whether
an animal does or does not form a certain association requires
for an answer no higher qualification in the observer than a pair
of eyes. The literature of animal psychology shows so uni-
formly and often so sadly the influence of the personal equation
that any method which can partially eliminate it deserves a trial.

Furthermore, although the associations formed are such as
could not have been previously experienced or provided for by
heredity, they are still not too remote from the animal’s ordinary

5 E. L. THORNDIKE.

course of life. They mean simply the connection of a certain act
with a certain situation and resultant pleasure, and this general
type of association is found throughout the animal’s life normally.
The muscular movements required are all such as might often be
required of the animal. And yet it will be noted that the acts re-
quired are nearly enough like the acts of the anecdotes to enable
one to compare the results of experiment by this method with
the work of the anecdote school. Finally, it may be noticed
that the method lends itself readily to experiments on imitation.

We may now start in with the description of the apparatus
and of the behavior of the animals.’

DESCRIPTION OF APPARATUS.

The shape and general apparatus of the boxes which were
used for the cats is shown by the accompaning drawing of box
K. Unless special figures are given, it should be understood

that each box is approximately 20 inches long by 15 broad by
12 high. Except where mention is made to the contrary, the
door was pulled open by a weight attached to a string which ran
over a pulley and was fastened to the door, just as soon as the

‘The experiments now to be described were for the most part made in the
Psychological Laboratory of Columbia University during the year ’97—98, but a
few of them were made in connection with a general preliminary investigation
of animal psychology undertaken at Harvard University in the previous year.

ANIMAL INTELLIGENCE. 9

animal loosened the bolt or bar which held it. Especial care
was taken not to have the widest openings between the bars at
all near the lever, or wire-loop, or what not, which governed
the bolt on the door. For the animal instinctively attacks the
large openings first, and if the mechanism which governs the
opening of the door is situated near one of them the animal’s
task is rendered easier. You do not then get the association
process so free from the helping hand of instinct as you do if
you make the box without reference to the position of the mech-
anism to be set up within it. These various mechanisms are
so simple that a verbal description will suffice in most cases.
The facts which the reader should note are the nature of the
movement which the cat had to make, the nature of the object
at which the movement was directed, and the position of the object
in the box. In some special cases attention will also be called
to the force required. In general, however, that was very
slight (20 to 100 grams if applied directly). The various boxes
will be designated by capital letters.

A. A string attached to the bolt which held the door ran
up over a pulley on the front edge of the box, and was tied to
a wire loop (2% inches diameter) hanging 6 inches above the
floor in front center of box. Clawing or biting it, or rubbing
against it even, if in a certain way, opened the door. We may
call this box A ‘O at front.’

B. A string attached to the bolt ran up over a pulley on
the front edge of the door, then across the box to another pul-
ley screwed into the inside of the back of the box 1% inches
below the top, and passing over it ended in a wire loop (3
inches in diameter) 6 inches above the floor in back center of
box. Force applied to the loop or éo the string as it ran across
the top of the box between two bars would open the door. We
may call B ‘O at back.’

Br. In Br the string ran outside the box, coming down
through a hole at the back, and was therefore inaccessible and
invisible from within. Only by pulling the loop could the door
be opened. Br may be called ‘O at back 2nd.’

C. A door of the usual position and size (as in Fig. 1) was
kept closed by a wooden button 3% inches long, 7 inch wide,

10 E. L. THORNDIKE.

¥% inch thick. This turned on a nail driven into the box %
‘nch above the middle of the top edge of the door. The door
would fall inward as soon as the button was turned from its
vertical to a horizontal position. A pullof 125 grams would
do this if applied sideways at the lowest point of the button 2%
inches below its pivot. The cats usually clawed the button
round by downward pressure on its top edge, which was 1%
inches above the nail. Then, of course, more force was neces-
sary. C may be called ‘Button.’

D. The door was in the extreme right of the front. A
string fastened to the bolt which held it ran up over a pulley
on the top edge and back to the top edge of the back side of
the box (3 inches in from the right side) and was there firmly
fastened. The top of the box was of wire screening and
arched over the string 34 inch above it along its entire length.
A slight pull on the string anywhere opened the door. This
box was 20 x 16, but a space 7 x 16 was partitioned off at the
left by a wire screen. D may be called ‘ String.’

D1 was the same box as B, but had the string fastened
firmly at the back instead of running over a pulley and ending
in a wire loop. We may call it ‘ Strzng 2nd.’

E. A string ran from the bolt holding the door up over a
pulley and down to the floor outside the box, where it was
fastened 2 inches in front of the box and 1¥% inches to the left
of the door (looking from the inside). By poking a paw out
between the bars and pulling this string inward the door would
be opened. We may call E ‘Streng outside.’

In F the string was not fastened to the floor but ended in a
loop 2% inches in diameter which could be clawed down so as
to open the door. Unless the pull was in just the right direc-
tion, the string was likely to catch on the pulley. This loop
hung 3 inches above the floor, and 134 inches in front of the
box. We may call F ‘Strzng outside unfastened.’

G was a box 29x 20% x 22%, with a door 29x 12 hinged on
the left side of the box (looking from within), and kept closed
by an ordinary thumb-latch placed 15 inches from the floor.
The remainder of the front of the box was closed in by wooden
bars. The door was a wooden frame covered with screening.

ANIMAL INTELLIGENCE. II

It was no¢ arranged so as to open as soon as the latch was
lifted, but required a force of 400 grams, even when applied to
the best advantage. The bar of the thumb-latch, moreover,
would fall back into place again unless the door were pushed
out at least a little. The top of this box was not of bars or
screening, but solid. We may call G ‘ Thumé-latch.’

H was, except for the opening where the door was situated,
a perfectly solid and dark box. In the front was cut an open-
ing about 9 x 7 inches. A wooden frame covered with wire
netting hung in front of this. It was fastened to the box only
by a screw through the middle of the frame’s top piece, and
could therefore be pushed to either side so as to permit escape
from the box if it were prevented from swinging back into
place.

I was a box 12 x 14 x 23. The door was 8 inches wide, 4
high, and hinged at the left side. It was held closed by a
wooden bar which moved easily on a pivot and which could be
pushed up by another bar which projected 5 inches into the box.
This second bar was pivoted so that downward pressure on it
pushed the first bar up and let the door swing open. The
second bar entered the box at a point 4 inches above the floor
and 2% inches in from the right side of the box. In its normal
position its inner end was 5% inches above the floor. A de-
pression of 2 inches at that end was necessary to open the door.
Of course, nearer the pivot a shorter depression would do. The
front of the box was closed by bars, but the rest by solid boards.
We may call I ‘Lever.’

J was the same as B except that the door was not opened by
a weight as soon as the bolt was pulled up. On the contrary,
the door was held closed by a small piece of board (4 x 3% x 3%
thick) placed against it outside. After pulling the loop at the
back the cat had to knock down this support and push the door
open. We may call J ‘Double.’

K was a box arranged so that three separate acts were re-
quired to open the door, which was held by two bolts at the top
and two bars outside. One of the bolts was connected witha
platform in the back center of the box so that depressing the
platform raised the bolt. The other was raised by a string

12 E. L. THORNDIKE.

which ran up over a pulley in the front, across the box 1 inch
above the bars, over a pulley near the corner of the box, and
down to the floor, where it was fastened. Pulling on this string,
either by clawing at it where it was running vertically from the
last pulley to the floor, or by putting the paw out between the
bars which covered the top of the box, and clawing the string
downwards, would raise the bolt. If both bolts were raised and
cither bar was pushed up or down far enough to be out of the
way, the cat could escape. K, or ‘ Triple,’ as it may be called,
is the box reproduced in Figure 1.

L was a box that also required three acts to open the door.
It was a combination of A (O at front), D (string), I (lever).
The lever or bar to be depressed was 2 inches to the right of
the door, which was in the front center. The string to be
clawed or bitten ran from front center to back center I inch
below the top of the box.

Z was a box with back and sides entirely closed, with front
and top closed by bars and screening, with a small opening in
the left front corner. A box was held in front of this and
drawn away when the cats happened to lick themselves. ‘Thus
escape and food followed always upon the impulse to lick them-
selves, and they soon would immediately start doing so as soon
as pushed into the box. The same box was used with the im-
pulse changed to that for scratching themselves. The size of
this box was I5 x 10x 16.

EXPERIMENTS WITH CATs.

In these various boxes were put cats from among the follow-
ing. I give approximately their ages while under experiment.

No. 1. 8-10 months.

No. 2. 5-7 months.

No. 3. 5-11 months.

No. 4. 5-8 months.

No. 5. 5-7 months.

No. 6. 3-5 months.

No. 7. 3-5 months.

No. 8. 6-6% months.

No. 10. 4-8 months.

ANIMAL INTELLIGENCE. 13

No. 11. 7-8 months.

No. 12. 4-6 months.

No. 13. 18-19 months.

The behavior of all but 11 and 13 was practically the same.
When put into the box the cat would show evident signs of dis-
comfort and of an impulse to escape from confinement. It
tries to squeeze through any opening; it claws and bites at the
bars or wire; it thrusts its paws out through any opening and
claws at everything it reaches; it continues its efforts when it
strikes anything loose and shaky; it may claw at things within
the box. It does not pay very much attention to the food out-
side, but seems simply to strive instinctively to escape from con-
finement. The vigor with which it struggles is extraordinary.
For eight or ten minutes it will claw and bite and squeeze in-
cessantly. With 13, an old cat, and 11, an uncommonly slug-
gish cat, the behavior was different. They did not struggle
vigorously or continually. On some occasions they did not
even struggle at all. It was therefore necessary to let them out
of some box a few times, feeding them each time. After they
thus associate climbing out of the box with getting food, they
will try to get out whenever put in. They do not, even then,
struggle so vigorously or get so excited as the rest. In either
case, whether the impulse to struggle be due to an instinctive
reaction to confinement or to an association, it is likely to suc-
ceed in letting the cat out of the box. The cat that is claw-
ing all’ over the box in her impulsive struggle will probably
claw the string or loop or button so as to open the door. And
gradually all the other non-successful impulses will be stamped
out and the particular impulse leading to the successful act will
be stamped in by the resulting pleasure, until, after many trials,
the cat will, when put in the box, immediately claw the button
or loop in a definite way.

The starting point for the formation of any association
in these cases, then, is the set of instinctive activities which are
aroused when a cat feels discomfort in the box either because
of confinement or a desire for food. This discomfort, plus the
sense-impression of a surrounding, confining wall, expresses it-
self prior to any experience, in squeezings, clawings, bitings,

14 E. L. THORNDIKE.

etc. From among these movements one is selected by success.
But this is the starting point only in the case of the first box ex-
perienced. After that the cat has associated with the feeling
of confinement certain impulses which have led to success more
than others and are thereby strengthened. A cat that has
learned to escape from A by clawing has when put into C or
G a greater tendency to claw at things than it instinctively had
at the start, and a less tendency to squeeze through holes. A
very pleasant form of this decrease in instinctive impulses was
noticed in the gradual cessation of howling and mewing.
However, the useless instinctive impulses die out slowly, and
often play an important part even after the cat has had ex-
perience with six or eight boxes. And what is important in our
previous statement, namely, that the activity of an animal when
first put into a new box is not directed by any appreciation of
that box’s character, but by certain general impulses to acts, is
not affected by this modification. Most of this activity is deter-
mined by heredity ; some of it, by previous experience.

My use of the words zzstenctive and zmpulse may cause some
misunderstanding unless explained here. Let us, throughout
this book, understand by instinct any reaction which an animal
makes to a situation wethout experience. It thus includes un-
conscious as well as conscious acts. Any reaction, then, to totally
new phenomena, when first experienced, will be called instinc-
tive. Any impulse then felt will be called an instinctive im-
pulse. Instincts include whatever the nervous system of an
animal, as far as inherited, is capable of. My use of the word
will, I hope, everywhere make clear what fact I mean. If the
reader gets the fact meant in mind it does not in the least matter
whether he would himself call such a fact instinct or not. Any
one who objects to the word may substitute ‘ hocus-pocus’ for
it wherever it occurs. The definition here made will not be used
to prove or disprove any theory, but simply as a signal for the
reader to imagine a certain sort of fact.

The word cmpudse is used against the writer’s will, but there
is no better. Its meaning will probably become clear as the
reader finds it in actual use, but to avoid misconception at any
time I will state now that zmpulse means the consciousness ac-

ANIMAL INTELLIGENCE. [5

companying a muscular innervation apart from that feeling of the
act which comes from seeing oneself move, from feeling one’s
body in a different position, etc. It is the direct feeling of the
doing as distinguished from the zdea of the act done gained
through eye, etc. For this reason I say ‘impulse avd act’ in-
stead of simply ‘act.’ Above all, it must be borne in mind that
by impulse I never mean the mo/¢zve to the act. In popular speech
you may say that hunger is the impulse which makes the cat claw.
That will never be the use here. The word moécve will always
denote that sort of consciousness. Any one who thinks that the
act ought not to be thus subdivided into impulse and deed may
feel free to use the word act for zmpulse or impulse and act
throughout, if he will remember that the act in this aspect of
being felt as to be done or as doing is in animals the important
thing, is the thing which gets associated, while the act as done,
as viewed from outside, is a secondary affair. I prefer to have
a separate word, impulse, for the former, and keep the word act
for the latter, which it commonly means.

Starting, then, with its store of instinctive impulses, the cat
hits upon the successful movement, and gradually associates it
with the sense-impression of the interior of the box until the
connection is perfect, so that it performs the act as soon as con-
fronted with the sense-impression. The formation of each asso-
ciation may be represented graphically by a time-curve. In
these curves lengths of one millimeter along the abscissa repre-
sent successive experiences in the box, and heights of one milli-
meter above it each represent ten seconds of time. The curve is
formed by joining the tops of perpendiculars erected along the
abscissa I mm. apart (the first perpendicular coinciding with
the y line), each perpendicular representing the time the cat
was in the box before escaping. Thus, in Fig. 2 on page 18
the curve marked 12 in A shows that, in 24 experiences or trials
in box A, cat 12 took the following times to perform the act,
160 sec., 30 sec., 90 sec., 60, 15, 28, 20, 30, 22, 11, I5, 20,
Z2, 10, 14, 10, 8, 8,5, 10, 8,6, 6, 7. A short vertical line
below the abscissa denotes that an interval of approximately 24
hours elapsed before the next trial. Where the interval was
longer it is designated by a figure 2 for two days, 3 for three

16 E. L. THORNDIKE.

days, etc. If the interval was shorter the number of hours is
specified by hr.,2 hrs.,etc. In many cases the animal failed in
some trial to perform the act in ten or fifteen minutes and was
then taken out by me. Such failures are denoted by a break in
the curve either at its start or along its course. In some cases
there are short curves after the main ones. These, as shown
by the figures beneath, represent the animal’s mastery of the
association after a very long interval of time, and may be called
memory curves. A discussion of them will come in the last
part of the book.

The time-curve is obviously a fair representation of the
progress of the formation of the association, for the two essential
factors in the latter are the disappearance of all activity save the
particular sort which brings success with it, and perfection of
that particular sort of act so that it is done precisely and at will.
Of these the second is, on deeper analysis, found to be a part
of the first; any clawing at a loop except the particular claw
which depresses it is theoretically a useless activity. If we
stick to the looser phraseology, however, no harm will be done.
The combination of these two factors is inversely proportional
to the time taken, provided the animal surely wants to get out
at once. This was rendered almost certain by the degree of
hunger. Theoretically a perfect association is formed when
both factors are perfect,—when the animal, for example, does
nothing but claw at the loop, and claws at it in the most useful
way for the purpose. In some cases (e. g., 2 in K on page
26) neither factor ever gets perfected in a great many trials.
In some cases the first factor does but the second does not, and the
cat goes at the thing not always in the desirable way. In all
cases there is a fraction of the time which represents getting
oneself together after being dropped in the box, and realizing
where one is. But for our purpose all these matters count little,
and we may take the general slope of the curve as representing
very fairly the progress of the association. The slope of any
particular part of it may be due to accident. Thus, very often
the second experience may have a higher time-point than the
first, because the first few successes may all be entirely due to
accidentally hitting the loop, or whatever it is, and whether the

ANIMAL INTELLIGENCE. 17

/

accident will happen sooner in one trial than another is then a
matter of chance. Considering the general slope, it is, of
course, apparent that a gradual descent—say, from initial times
of 300 sec. to a constant time of 6 or 8 sec. in the course of 20
to 30 trials—represents a difficult association, while an abrupt de-
scent, say in 5 trials, from a similar initial height, represents a
very easy association. Thus, 2 in Z, on page 23, is a hard,
and 1 in I, on page 22, an easy association.

In boxes A, C, D, E, I, 100 % of the cats given a chance
to do so hit upon the movement and formed the association.
The following table shows the results where some cats failed.

No. catstried. No. cats failed.

| ae

7

Aw & @ Fy
nN Mm wo mo wo
te

LS)

The time-curves follow. By referring to the description
of apparatus they will be easily understood. Each mm. along
the abscissa represents one trial. Each mm. above it repre-
sents 10 seconds.

These time-curves show, in the first place, what associations
are easy for an animal to form, and what are hard. The act
must be one which the animal will perform in the course of the
- activity which its inherited equipment incites or its previous ex-
perience has connected with the sense-impression of a box’s
interior. The oftener the act naturally occurs in the course of
such activity, the sooner it will be performed in the first trial or
so, and this is one condition, sometimes, of the ease of forming
the association. For if the first few successes are five minutes
apart the influence of one may nearly wear off before the next,
while if they are forty seconds apart the influences may get
summated. But this is not the only or the main condition of the
celerity with which an association may be formed. It depends
also on the amount of attention given to the act. An act of

No.l] wA.

Average WA.

No.3 mA.

Be LET ORIVD TIE

No.i2 mD.

a

Avt rag e-D.

Nel 3 um A.

ANIMAL INTELLIGENCE.

NolOw C. a 4 .

Nolivte. 7

Prsthine'C. No.4 mC.
No3uC. |, No.|3ma6

a6 40

THORNDIKE.

L

E.

“shov TL

WATT ON = ‘HOLTON

78

aged hoN ‘arousal

ha

= Qo}

HIE 0
4g 7 N

Ae eCI IN

H MTW
1%, Wy

“AM TON

ANIMAL INTELLIGENCE.

Nod) tw G.
a

fae 30.
Nod in G, memory,

E. L. THORNDIKE.

Fic 6

ANIMAL INTELLIGENCE

No 6wZ.

No.2 mw Z.

No. wma.

E. L. THORNDIKE.

No.3 Ww. is

Fic. 8.

ANIMAL INTELLIGENCE.

r

E. L. THORNDIKE.

Nod wk.

No+t wk.

Ih.

Vth,

ah

l2imL.

Sh:

th,

Ni.

\

th.

yas ke

inl. {0 inl. LOMEmory:

Die, We

ANIMAL INTELLIGENCE. 27

the sort likely to be well attended to will be learned more
quickly: Here, too, accident may play a part, for a cat may
merely happen to be attending to its paw when it claws. The
kinds of acts which insure attention are those where the move-
ment which works the mechanism is one which the catemakes
definitely to getout. Thus A (O at front) is easier to learn than
C (button), because the cat does A in trying to claw down the
front of the box and so is attending to what it does, whereas it
does C generally in a vague scrabble along the front or while
trying to claw outside with the other paw, and so does not attend
to the little unimportant part of its act which turns the button
round. Above all, sempliczty and definiteness in the act make
the association easy. G (thumb-latch), J (doubley and K and
L (triples) are hard, because complex. E is easy, because
directly in the line of the instinctive impulse to try to pull one-
self out of the box by clawing at anything outside. It is thus
very closely attended to. The extreme of ease is reached when
a single experience stamps the association in so completely that
ever after the act is done at once. This is approached in I and
E. In these experiments the sense-impressions offered no diffi-
culty one more than the other.

Vigor, abundance of movements, was observed to make dit-
ferences between individuals in the same association. It works
by shortening the first times, the times when the cat still does
the act largely by accident. Nos. 3 and 4 show this through-
out. Attention, often correlated with lack of vigor, makes a
cat form an association quicker after he gets started. No. 13
shows this somewhat. The absence of a fury of activity let
him be more conscious of what he did do.

The curves on pages 22 and 23 showing the history of cats
I, 5, 13 and 3, which were let out of the box Z when they licked
themselves, and of cats 6, 2, and 4, which were let out when they
scratched themselves, are interesting because they show asso-
ciations where there is no congruity (no more to a cat than to a
man) between the act and the result. One chick, too, was
thus freed whenever he pecked at his feathers to dress them.
He formed the association, and would whirl his head round and
poke it into the feathers as soon as dropped in the box. There

ae) E. L. THORNDIKE.

‘< in all these cases a noticeable tendency, of the cause of which
[ am ignorant, to diminish the act until it becomes a mere ves-
tige of a lick or scratch. After the cat gets so that it performs
the act soon after being put in, it begins to do it less and less
vigorously. The licking degenerates into a mere quick turn of
the head with one or two motions up and down with tongue ex-
tended. Instead of a hearty scratch, the cat waves its paw up
and down rapidly for aninstant. Moreover, if sometimes you do
not let the cat out after this feeble reaction, it does not at once
repeat the movement, as it would do if it depressed a thumb-
piece, for instance, without success in getting the door open. Of
the reason for this difference I am again ignorant.

Previous experience makes a difference in the quickness
with which the cat forms the associations. After getting out of
six or eight boxes by different sorts of acts the cat’s general
tendency to claw at loose objects within the box is strengthened
and its tendency to squeeze through holes and bite bars is weak-
ened; accordingly it will learn associations along the general
line of the old more quickly. Further, its tendency to pay
attention to what it is doing gets strengthened, and this is some-
thing which may properly be called a change in degree of in-
telligence. A test was made of the influence of experience in
this latter way by putting two groups of cats through I (lever),
one group (I, 2, 3, 4,5) after considerable experience, the
other (10, II, 12) after experience with only one box. As the
act in I was not along the line of the acts in previous boxes, and
as a decrease in the squeezings and bitings would be of little
use in the box as arranged, the influence of experience in the
former way was of little account. The curves of all are shown
on page 22.

If the whole set of curves are examined in connection with
the following table, which gives the general order in which
each animal took up the different associations which he eventu-
ally formed, many suggestions of the influence of experience
will be met with. The results are not exhaustive enough to
justify more than the general conclusion that there is such an
influence. By taking more individuals and thus eliminating all
other factors besides experience, one can easily show just how
and how far experience facilitates association.

ANIMAL INTELLIGENCE. 29

When in this table the letters designating the boxes are
in italics it means that, though the cat formed the association.
it was in connection with other experiments and so is not re-
corded in the curves.

Cat 1 Ae 6D. De FZ -3
«2 COPE Zu oT 1k
Mi WAG) HG Hy. Z 1K
4 Weir GoD 7 wa xk
re CBZ a I
“6 } A Caan Ta

| eae a7 AMG

| * 10 Col A’ wD tL
ig eGwl “AY HW DE
CO sige) aCe Ay ED) 1.
nate) DEG DH iGe Z

The advantage due to experience in our experiments is not,
however, the same as ordinarily in the case of trained animals.
With them the associations are with the acts or voice of man or
with sense impressions to which they naturally do not attend (ce. ¢.,
figures on a blackboard, ringing of a bell, some act of another
animal). Here the advantage of experience is mainly due to
the fact that by such experience the animals gain the habit of at-
tending to the master’s face and voice and acts and to sense im-
pressions in general.

I made no attempt to find the differences in ability to acquire
associations due to age or sex or fatigue or circumstances of
any sort. By simply finding the average slope in the different
cases to be compared, one can easily demonstrate any such
differences that exist. So far as this discovery is profitable,
investigation along this line ought now to go on without delay,
the method being made clear. Of differences due to difference
in the species, genus, etc. Of the animals I will speak after
reviewing the time-curves of dogs and chicks.

In the present state of animal psychology there is another

30 E. L. THORNDIKE.

me |

value to these results which was especially aimed at by the
investigator from the start. They furnish a quantitative esti-
mate of what the average cat can do, so that if any one has an
animal which he thinks has shown superior intelligence or per-
haps reasoning power, he may test his observations and opinion
by taking the time-curves of the animal in such boxes as I
have described.'

If his animal in a number of cases forms the associations

very much more quickly, or deals with the situation in a more
intelligent fashion than my cats did, then he may have ground
for claiming in his individual a variation toward greater intelli-
gence and possibly intelligence of a different order. /On the
other hand, if the animal fails to rise above the type in his deal-
ings with the boxes, the observer should confess that his opinion
of the animal’s intelligence may have been at fault and should
look for a correction of it.

We have in these time-curves a fairly adequate measure of
what the ordinary cat can do, and how it does it, and in similar
curves soon to be presented a less adequate measure of what a
dog may do. If other investigators, if especially all amateurs
who are interested in animal intelligence, will take other cats
and dogs, especially those supposed by owners to be extraordi-
narily intelligent, and experiment with them in this way, we
shall soon get a notion of how much variation there is among
animals in the direction of more or superior intelligence. The
beginning here made is meager but solid. The knowledge it
gives needs to be much extended. The variations found in in-
dividuals should be correlated not merely with supposed superi-
ority in intelligence, a factor too vague to be very serviceable,
but with observed differences in vigor, attention, memory and
muscular skill. No phenomena are more capable of exact and
thorough investigation by experiment than the associations of
animal consciousness. Never will you get a better psycholog-
ical subject than a hungry cat. When the crude beginnings of
this research have been improved and replaced by more ingen-

‘To any such person who may chance to read this monograph I may say
that I will gladly furnish him photographs of the boxes, so that he may work
with exact duplicates of them.

a a

ANIMAL INTELLIGENCE. 31

ious and adroit experimenters, the results ought to be very valu-
able.

Surely every one must agree that no man now has a right to
advance theories about what is in animals’ minds or to deny
previous theories unless he supports his thesis by systematic and
extended experiments. My own theories, soon to be _ pro-
claimed, will doubtless be opposed by many. I sincerely hope
they will, provided the denial is accompanied by actual experi-
mental work. In fact I shall be tempted again and again in the
course of this book to defend some theory, dubious enough to
my own mind, in the hope of thereby inducing some one to
oppose me and in opposing me to make the experiments I have
myself had no opportunity to make yet. Probably there will
be enough opposition if I confine myself to the theories I feel
sure of.

EXPERIMENTS WITH DoGs.

The boxes used were as follows:

AA was similar to A (O at front), except that the loop was
of stiff cord 3g inch in diameter and was larger (3% inches
diameter); also it was hung a foot from the floor and 8 inches
to the right of the door. The box itself was 41 x 20 x 23.

BB was similar to B, the loop being the same as in AA,
and being hung a foot from the floor. The box was of the same
size and shape as AA.

BB was like BB, but the loop was hung 18 inches from the
floor.

CC was similar to C (Button), but the button was 6 inches
long, and the box was 36% x 22 x 23.

II was similar to I, but the box was 30 x 20 x 25 inches;
the door (11 inches wide, 6 high) was in the left front corner,
and the lever was 6 inches long and entered the box at a point
2 inches to the right of the door and 4 inches above the floor.

In M the same box as in II was used, but instead of a lever
projecting inside the box, a lever running outside parallel to
the plane of the front of the box and 18 inches long was used.
This lay close against the bars composing the front of the box,
and could be pawed down by sticking the paw out an inch or

E. L. THORNDIKE.

»”>
er has

so between two bars, at a point about 15 inches high and 6
inches in from the right edge of the front. We may call M
« Lever outside.’

N was a pens x3 feet made of wire netting 46 inches high.
The door, 31 x 20, was in the right half of the front. A string
from the bolt passed up over a pulley and back to the back
center, where it was fastened 33 inches above the floor. Biting
or pawing this string opened the door.

O was like K, except that there was only one bar, that the
string ran inside the box, so that it was easily accessible, and
that the bolt raised in K by depression of the platform could be
raised in O (and was by the dog experimented on) by sticking
the muzzle out between two bars just above the bolt and by bit-
ing the string, at the same time jerking it upward. O was 30
x 20X 25 in size.

The box G was used for both dogs and cats, without any
variation save that for dogs the resistance of the door to pres-
sure outwards was doubled.

In these boxes were put in the course of the experiments
dog 1 (about 8 months old), and dogs 2 and 3, adults, all of
small size.

A dog who, when hungry, is shut up in one of these boxes
is not nearly so vigorous in his struggles to get out as is the
young cat. And even after he has experienced the pleasure of
eating on escape many times he does not try to get out so hard
as acat, young or old. He does try to a certain extent. He
paws or bites the bars or screening, and tries to squeeze out

in a tame sort of way. He gives up his attempts sooner than ~

the cat, if they prove unsuccessful. Furthermore his attention
is taken by the food, not the confinement. He wants to get
to the food, not out of the box. So, unlike the cat, he con-
fines his efforts to the front of the box. It was also a practical
necessity that the dogs should be kept from howling in the
evening, and for this reason I could not use as a motive the
utter hunger which the cats were made to suffer. In the morn-
ing, when the experiments were made, the dogs were surely
hungry, and no experiment is recorded in which the dog was
not in a state to be willing to make a great effort for a bit of

ANIMAL INTELLIGENCE. 33

meat, but the motive may not have been even and equal
throughout, as it was with the cats.

The curves which follow are to be interpreted in the same
way as those for the cats, and are on the same scale. The
order in which No. 1 took up the various associations was AA,

mes bor, G,.N, CC, II, O.

LmwAR.

Nod, m IT. No. ium AA.

Nod im TL. Not uw M. NoliwN. '5 NalimGG, “3%

34 E. L. THORNDIKE.

30

The percentage of dogs succeeding in the various boxes is
given below, but is of no consequence, because so few were
tried, and because the motive, hunger, was not perhaps strong
enough, or equal in all cases.

In AA 3 out of 3.

« BB o “© ‘ 2 (that is, without previous experience of

Nolen Oal

EKG.) 2.

AA).
In CC i ontof 2.
ce J] 2 66 66 2.
c M I 66 6 Q,
co ON I sé 6s ae
cw G IT sé 6 25

EXPERIMENTS WITH CHICKS.

The apparatus was as follows:

P was simply a small pen arranged with two exits, one lead-
ing to the enclosure where were the other chicks and food, one
leading to another pen with no exit. The drawing (Fig. 13
on page 35) explains itself. A chick was placed at A and left
to find its way out. The walls were made of books stuck up
on end. ;

Q was a similar pen arranged so that the real exit was
harder to find. (See Fig. 14.)

ANIMAL INTELLIGENCE. 35

R was still another pen similarly constructed, with four
possible avenues to be taken. (See Fig. 15.)

A A A

Fre. 13: Fic. 14. Fic. 15,

S was a pen with walls 11 inches high. On the right side
an inclined plane of wire screening led from the floor of the pen
to the top of its front wall. Thence the chick could jump down
to where its fellows and the food and drink were. S was
17 X 14 In size.

T was a pen of the same size as S, with a block of wood 3
inches by 3 and 2 inches high in the right back corner. From
this an inclined plane led to the top of the front wall (on the
right side of the box). Buta partition was placed along the
left edge of this plane, so that a chick could reach it only via
the wooden block, not by a direct jump.

U was a pen 16x14 x 10inches. Along the back to-
ward the right corner were placed a series of steps 1% inches
wide, the first 1, the second 2, and the third 3 inches high. In
the corner was a platform 4 x 4, and 4 high, from which access
to the top of the front wall of the pen could be gained by
scrambling up inside a stovepipe 11 inches long, inclined
upward at an angle of about 30°. From the edge of the wall
the chick could of course jump down to food and society. The
top of the pen was covered so that the chick could not from the
platform jump onto the edge of the stovepipe or the top of the
pen wall. The only means of exit was to go up the steps to
the platform, up through the stovepipe to the front wall, and
then jump down.

The time-curves for chicks 90, 91, 92, 93, 94 and 95, all
2-8 days old when experimented on, follow on page 37. The
scale is the same as that in the curves of the cats and dogs.

36 E. L. THORNDIKE.

Besides these simple acts, which any average chick will acci-
dentally hit upon and associate, there are, in the records of my
preliminary study of animal intelligence, a multitude of all sorts
of associations which some chicks have happened to form.
Chicks have escaped from confinement by stepping on a little
platform in the back of the box, by jumping up and pulling a
string like that in D, by pecking at a door, by climbing up a
spiral staircase and out through a hole in the wall, by doing
this and then in addition walking across a ladder for a foot to
another wall from which they could jump down, etc., etc. Not
every chick will happen upon the right way in these cases, but
the chicks who did happen upon it all formed the associations
perfectly after enough trials.

The behavior of the chicks shows the same general charac-
ter as that of the cat, conditioned, of course, by the different
nature of the instinctive impulses. Take a chick put in T (in-
clined plane) for an example. When taken from the food and
other chicks and dropped into the pen he shows evident signs
of discomfort; he runs back and forth, peeping loudly, trying
to squeeze through any openings there may be, jumping up to
get over the wall, and pecking at the bars or screen, if such
separate him from the other chicks. Finally, in his general run-
ning around he goes up the inclined plane away. He may come
down again, or he may go on up far enough to see over the top of
the wall. If he does, he will probably go running up the rest of
the way and jump down. With further trials he gains more
and more of an impulse to walk up an inclined plane when he
sees it, while the vain running and pecking, etc., are stamped out
by the absence of any sequent pleasure. Finally, the chick
goes up the plane as soon as put in. In scientific terms this his-
tory means that the chick, when confronted by loneliness and.
confining walls, responds by those acts which in similar condi-
tions in nature would be likely to free him. Some one of these
acts leads him to the successful act, and the resulting pleasure:
stamps itin. Absence of pleasure stamps all others out. The
case is just the same as with dogs and cats. The time-curves
are shown in Fig. 16. .

Coming now to the question of differences in intelligence:

ANIMAL INTELLIGENCE.

o>)
oe |

ah
No 40 mwP.
3h ‘in
No.42mwWR
No.43 wS.
No.2 Ww S.

3h.

No.94 re We No. 42a”

2h

Fic. 16:

between the different animals, it is clear that such differences
are hard to estimate accurately. The chicks are surely very

E. L. THORNDIKE.

~

oO
much slower in forming associations and less able to tackle hard
ones, but the biggest part of the difference between what they
do and what the dogs and cats do is not referable so much to
any difference in intelligence as to a difference in their bodily
organs and instinctive impulses. As between dogs and cats,
the influence of the difference in quantity of activity, in the
direction of the instinctive impulses, in the versatility of the
fore-limb, is hard to separate from the influence of intelligence
proper. The best practical tests to judge such differences in
general would be differences in memory, which are very easily
got at, differences in the delicacy and complexity attainable,
and of course differences in the slope of the curves for the
same association. If all these tests agreed, we should have a
right to rank one animal above the other in a scale of intelli-
gence. But this whole question of grading is, after all, not so
important for comparative psychology as its popularity would
lead one to think. Comparative psychology wants first of all to
trace human intellection back through the phylum to its origin,
and in this aim is helped little by knowing that dogs are brighter
than cats, or whales than seals, or horses than cows. Further,
the whole question of ‘ intelligence’ should be resolved into par-
ticular inquiries into the development of attention, activity,
memory, etc.

So far as concerns dogs and cats, I should decide that the
former were more generally intelligent. The main reason, how-
ever, why dogs seem to us so intelligent is not a good reason
for the belief. It is because, more than any other domestic
animal, they direct their attention to ws, to what we do, and so
form associations connected with acts of ours.

Having finished our attempt to give a true description of the
facts of association, so far as observed from the outside, we may
now progress to discuss its inner nature. A little preface about
certain verbal usages is necessary before doing so. Through-
out I shall use the word ‘ animal’ or « animals,’ and the reader
might fancy that I took it for granted that the associative pro-
cesses were the same in all animals as in these cats and dogs of
mine. Really, I claim for my animal psychology only that it
is the psychology of just these particular animals. What this

ANIMAL INTELLIGENCE. 39

warrants about animals in general may be left largely to the
discretion of the reader. As I shall later say, it is probable
that in regard to imitation and the power of forming associations
from a lot of free ideas, the anthropoid primates are essentially
different from the cats and dogs.

The reasons why I say ‘ animals’ instead of ‘ dogs and cats
of certain ages’ are two. Ido think that the probability that
the other mammals, barring the primates, offer no objections to
the theories here advanced about dogs and cats, is a very strong
probability, strong enough to force the burden of proof upon
any one who should, for instance, say that horse-goat psychology
was not like cat-dog psychology in these general matters. I
should claim that, till the contrary was shown in any case, my
statements should stand for the mammalian mind in general,
barring the primates. My second reason is that I hate to burden
the reader with the disgusting rhetoric which would result if
I had to insert particularizations and reservations at every step.
The word ‘ animal’ is too useful, rhetorically, to be sacrificed.
Finally, inasmuch as most of my theorizing will be in the line
of denying certain relatively high functions to animals, the evi-
dence from cats and dogs is sufficient, for they are from among
the most intelligent animals, and functions of the kind to be
discussed, if absent in their case, are probably absent from the
others.

REASONING OR INFERENCE.

The first great question is whether or not animals are ever
led to do any of their acts by reasoning. Do they ever con-
clude from inference that a certain act will produce a certain
desired result, and so do it? The best opinion has been that
they do not. The best interpretation of even the most extraor-
dinary performances of animals has been that they were the re-
sult of accident and association or imitation. But it has after
all been only opinion and interpretation, and the opposite theory
persistently reappears in the literature of the subject. So, al-
though it is in a way superfluous to give the coup de grace to
the despised theory that animals reason, I think it is worth while
to settle this question once for all.

40 E. L. THORNDIEE.

The great support of those who do claim for animals the
ability to infer has been their wonderful performances which
resemble our own. These could not, they claim, have hap-
pened by accident. No animal could learn to open a latched
gate by accident. The whole substance of the argument van-
hee if, as a matter of fact, animals do learn those things by
accident. Zhey certainly do. In this investigation choice was
made of the intelligent performances described by Romanes in
the following passages. I shall quote at some length because
these passages give an admirable illustration of an attitude of
investigation which this research will, I hope, render impossible
for any scientist in the future. Speaking of the general intelli-
Bee of aad Romanes lay

‘ & instances oO
Meedarent- ence aa = TERE These instances are all
such precise repetitions of one another that I conclude the fact to be
one of tolerably ordinary occurrence among cats, while it is certainly
very rare among dogs. I may add that my own coachman once had
a cat which, certainly without tuition, learnt thus to open a door that
led into the stables from a yard into which looked some of the win-
dows of the house. Standing at these windows when the cat did not
see me, I have many times witnessed her modus operandi. Walking
up to the door with a most matter-of-course kind of air, she used
to spring at the half hoop handle just below the thumb-latch.
Holding on to the bottom of this half-hoop with one fore paw, she
then raised the other to the thumb-piece, and while depressing the
latter finally with her hind legs scratched and pushed the door-posts
so as to open the door * * *,

‘*Of course in all such cases the cats must have previously ob-
served that the doors are opened by persons placing their hands upon
the AE and, ssLavIne eieace this, the animals act by what may

strictly termed rational imitat But it should be observed that
the process : as a whole is something more than imitative. For not
only would observation alone be scar cely enough (within any limits of
thoughtful reflection that it would be reasonable to ascribe to an
animal) to enable a cat upon the ground to distinguish that the essen-
tial part of the process consists not in grasping the handle, but in

ANIMAL INTELLIGENCE. 41

depressing the latch; but the cat certainly never saw any one, after
having depressed the latch, pushing the door-posts with his legs; and
that this pushing action is due to an originally deliberate intention of
opening the door, and not to having accidentally found this action to
assist the process, is shown by one of the cases communicated to me;
for in this case, my correspondent says, ‘ the door was not a loose-
fitting one, by any means, and I was surprised that by the force of one
hind leg she should have been able to push it open after unlatching
it... Hence we can only conclude that the cats in such cases have
a very definite idea as to the mechanical properties of a door: they
know that to make it open, even when unlatched, it requires to be
pushed—a very different thing from trying to imitate any particular
action which they may see to be performed for the same purpose by
man. The whole psychological process, therefore, implied by the
fact of a cat opening a door in this way is really most complex.
First the animal must have observed that the door is opened by the
hand grasping the handle and moving the latch. Next she must
reason, by ‘ the logic of feelings’—‘ If a hand can do it, why not a
paw? Then strongly moved by this idea she makes the first trial.
The steps which follow have not been observed, so we cannot cer-
tainly say whether she learns by a succession of trials that depression
of the thumb-piece constitutes the essential part of the process, or,
perhaps more probably, that her initial observations supplied her with
the idea of clicking the thumb-piece. But, however this may be, it
is certain that the pushing with the hind feet after depressing the latch
must be due to adaptive reasoning unassisted by observation; and
only by the concerted action of all her limbs in the performance of a
highly complex and most unnatural movement is her final purpose
attained.” (Animal Intelligence, pp. 420-422.

A page or two later we find a less ponderous account of a
cat’s success in turning aside a button and so opening a window:

‘¢ At Parara, the residence of Parker Bowman, Esq., a full-grown
cat was one day accidentally locked up in a room without any other
outlet than a small window, moving on hinges, and kept shut by
means of a swivel. Not long afterwards the window was found open
and the cat gone. This having happened several times, it was
at last found that the cat jumped upon the window-sill, placed her
fore-paws as high as she could reach against the side, deliberately
reached with one over to the swivel, moved it from its horizontal to
a vertical position, and then, leaning with her whole weight against

42 E. L. THORNDIKE.

the window, swung it open and escaped.” (Animal Intelligence,
P+ 425.)

A description has already been given on page 9 of the
small box (C), whose door fell open when that button was
turned, and also of a large box (CC) for the dogs, with a similar
door. The thumb-latch experiment was carried on with the
same box (G) for both cats and dogs, but the door was arranged
so that a greater force (1.3 kilograms) was required in the case
of the dogs. It will be remembered that the latch was so fixed
that if the thumb-piece were pressed down, without contempo-
raneous outward pressure of the door, the latch bar would merely
drop back into its catch as soon as the paw was taken off the
door. If, however, the door were pushed outward the latch
bar, being pressed closely against the outer edge of its catch,
would, if lifted, be likely to fall outside it and so permit the door
to open if then or later sufficient pressure were exerted. Eight
cats (Nos. 1, 2, 3, 4, 5, 6, 7 and 13) were, one at a time, left
in this thumb-latch box. All exhibited the customary instinc-
tive clawings and squeezings and bitings. Out of the eight all
succeeded in the course of their vigorous struggles in pressing
down the thumb-piece, so that if the door had been free to swing
open they could have escaped. Six succeeded in pushing both
thumb-piece down and door out, so that the bar did not fall back
into its place. Of these five succeeded in also later pushing
the door open, so that they escaped and got the fish outside.
Of these, three, after repeated trials, associated the complicated
movements required with the sight of the interior of the box so
firmly that they attacked the thumb-latch the moment they were
putin. The history of the formation of the association in the
case of 3 and of 4 is shown in the curves on page 21. In
the case of 13 the exact times were not taken. The combination
of accidents required was enough to make it take No. 1 and No.
6 a long time to get out. Consequently, weariness and failure
inhibited their impulses to claw, climb, etc., more than the rare
pleasure from getting out strengthened them, and they failed to
form the association. Like the cats who utterly failed to get
voc they finally ceased to try when put in. The history of

eir efforts is as follows: The figures in the columns represent

ANIMAL INTELLIGENCE. 43

the time (in minutes and seconds) the animal was in the box
before escaping or before being taken out if he failed to escape.
Cases of failure are designated by an F after the figures.
Double lines represent an interval of twenty-four hours.

No. 1. | No. 6. |

SS
13.00 F 17.50
9-30 3.30
I.40 9.00
50 2.10
15-00 1.45
6.00 F 1.55
14.00 13.00
20.00 F 5.00
4-30 2.30

15.00 F 5-00

It should be noted that, although cats 3 and 4 had had some
experience in getting out of boxes by clawing at loops and turn-
ing buttons, they had never had anything at all like a thumb-
latch to claw at, nor had they ever seen the door opened by its
use, nor did they even have any experience of the fact that the
part of the box where the thumb-piece was was the door. And
we may insert here, what will be stated more fully later, that
there was displayed no observation of the surroundings or de-
liberation upon them. It was just a mad scramble to get out.

Three dogs (1, 2 and 3) were given a chance to liberate
themselves from this same box. 2 and 3, who were rather in-
active, failed to even push the thumb-piece down. No. 1, who
was very active, did push it down at the same time that she hap-

44 E. L. THORNDIKE.

pened to be pushing against the door. She repeated this and
formed the association as shown in the curve on page 34. She
had had experience only of escaping by pulling a loop of string.

Out of 6 cats who were put in the box whose door opened
by a button, not one failed, in the course of its impulsive activity,
to push the button around. Sometimes it was clawed one side
from below; sometimes vigorous pressure on the top turned it
around ; sometimes it was pushed up by the nose. No cat who was
given repeated trials failed to form a perfect association between
the sight of the interior of that box and the proper movements.
Some of these cats had been in other boxes where pulling a
loop of string liberated them, 3 and 4 had had considerable ex-
perience with the boxes and probably had acquired a general
tendency to claw at loose objects. 10, 11 and 12 had never
been in azy box before. The curves are on page 19.

Of two dogs, one, when placed in a similar but larger box,
succeeded in hitting the button in such a way as to let the door
open, and formed a permanent association, as shown by the
curves on page 33. No one who had seen the behavior of these
animals when trying to escape could doubt that their actions
were directed by instinctive impulses, not by rational observa-
tion. Itis then absolutely sure that a dog or cat can open a
door closed by a thumb-latch or button, merely by the acci-
dental success of its natural impulses. If @// cats, when hun-
gry and in a small box, will accidentally push the button that
holds the door, an occastonal cat in a large room may very
well do the same. If three cats out of eight will accidentally
press down a thumb-piece and push open a small door, three
cats out of a thousand may very well open doors or gates in
the same way.

But besides thus depriving of their value the facts which
these theorizers offer as evidence, we may, by a careful exami-
nation of the method of formation of these associations as it is
shown in the time-curves, gain positive evidence that no power of
inference was present in the subjects of the experiments. Surely
if 1 and 6 had possessed any power of inference they would not
have failed to get out after having done so several times. Yet
they did (see p- 43). If they had once even, much less if they

ANIMAL INTELLIGENCE. 45

had six or eight times, inferred what was to be done, they
should have made the inference the seventh or ninthtime. And
if there were in these animals any power of inference, however
rudimentary, however sporadic, however dim, there should have
appeared among the multitude some cases where an animal,
seeing through the situation, knows the proper act, does it, and
from then on does it immediately upon being confronted with the
situation. ‘There ought, that is, to be a sudden vertical descent
in the time-curve. Of course, where the act resulting from the
impulse is very simple, very obvious, and very clearly defined,
a simple experience may make the association perfect, and we
may have an abrupt descent in the time-curve without needing
to supposeinference. But if in a complex act, a series of acts
or an ill-defined act, one found such a sudden consummation in
the associative process, one might very well claim that reason
was atwork. Now, the scores of cases recorded show no such
phenomena. The cat does not look over the situation, much less
think it over, and then decide what to do. It bursts out at once
into the activities which instinct and experience have settled on
as suitable reactions to the situation ‘ confinement when hungry
with food outside.’ It does not ever in the course of its suc-
cesses realize that such an act brings food and therefore decide
to do it and thenceforth do it immediately from deczs¢on instead
of from impulse. The one impulse, out of many accidental
ones, which leads to pleasure, becomes strengthened and
stamped in thereby, and more and more firmly associated with
the sense-impression of that box’s interior. Accordingly it is
sooner and sooner fulfilled. Futile impulses are gradually
stamped out. The gradual slope of the time-curve, then, shows
the absence of reasoning. They represent the wearing smooth
of a path in the brain, not the decisions of a rational con-
sciousness.

In a later discussion of imitation further evidence that ani-
mals do not reason will appear. For the present, suffice it to
say, that a dog, or cat, or chick, who does not in his own im-
pulsive activity learn to escape from a box by pulling the proper
loop, or stepping on a platform, or pecking at a door, will not
learn it from seeing his fellows do so. They are incapable of

46 E. L. THORNDIKE.

even the inference (if the process may be dignified by that
name) that what gives another food will give it to them also.
So, also, it will be later seen that an animal cannot learn an act
by being put through it. For instance, a cat who fails to push
down a thumb-piece and push out the door cannot be taught by
having one take its paw and press the thumb-piece down with
it. This cow/d be learned by a certain type of associative pro-
cess without inference. Were there inference it surely would be
learned.

Finally, attention may be called to the curves which show
the way that the animal mind deals with a series of acts (e. g.,
curves for G, J, K, L and O, found on pages 21 to 26 and 34).
Were there any reasoning the animals ought early to master the
method of escape in these cases (see descriptions on pages 10
to 12 and 32) so as to do the several acts in order, and not to
repeat one after doing it once, or else ought utterly to fail to
master the thing. But, in all these experiments, where there
was every motive for the use of any reasoning faculty, if such
existed, where the animals literally lived by their intellectual
powers, one finds no sign of abstraction, or inference, or judg-
ment.

So far I have only given facts which are quite uninflenced by
any possible incompetence or prejudice of the observer. These
alone seem to disprove the existence of any rational faculty in
the subjects experimented on. I may add that my observations
of all the conduct of all these animals during the months spent
with them, failed to find any act that even seemed due to reason-
ing. I should claim that this quarrel ought now to be dropped
for good and all, that investigation ought to be directed along
more sensible and profitable lines. I should claim that the
psychologist who studies dogs and cats in order to defend this
‘reason’ theory is on a level with a zodlogist who should study
fishes with a view to supporting the thesis that they possessed
clawed digits. The rest of this account will deal with more
promising problems, of which the first, and not the least im-
portant, concerns the facts and theories of zmtation.

ANIMAL INTELLIGENCE. 47

IMITATION.

To the question, ‘Do animals imitate?’ science has uni-
formly answered, ‘ Yes.’ But so long as the question is left in
this general form, no correct answer to it is possible. It will be
seen, from the results of numerous experiments soon to be de-
scribed, that imitation of a certain sort is not possible for ani-
mals, and before entering upon that description it will be helpful
to differentiate this matter of imitation into several varieties or
aspects. The presence of some sorts of imitation does not im-
ply that of other sorts.

There are, to begin with, the well-known phenomena pre-
sented by the imitative birds. The power is extended widely,
ranging from the parrot who knows a hundred or more articu-
late sounds to the sparrow whom a patient shoemaker taught to
get through a tune. Now, if abird really gets a sound in his
mind from hearing it and sets out forthwith to imitate it, as
mocking-birds are said at times to do, it is a mystery and de-
serves closest study. If a bird, out of a lot of random noises
that it makes, chooses those for repetition which are like sounds
that he has heard, it is again a mystery wy, though not as in
the previous case a mystery how, he does it. The important
fact for our purpose is that, though the imitation of sounds is so
habitual, there does not appear to be any marked general imita-
tive tendency in these birds. There is no proof that parrots do
muscular.acts from having seen other parrots do them. But
this should be studied. At any rate, until we know what sort
of sounds birds imitate, what circumstances or emotional atti-
tudes these are connected with, how they learn them and,
above all, whether there is in birds which repeat sounds any
tendency to imitate in other lines, we cannot, it seems to me,
connect these phenomena with anything found in the mammals
or use them to advantage in a discussion of animal imitation as
the forerunner of human. In what follows they will be left
out of account, will be regarded as a specialization removed
from the general course of mental development, just as the feath-
ers or right aortic arch of birds are particular specializations of
no consequence for the physical development of mammals. For

48 BE. L. THORNDIKE.

us, henceforth, imitation will mean imitation minus the phenom-
ena of imitative birds.

There are also certain pseudo-imitative or semi-imitative
phenomena which ought to be considered by themselves. For
example, the rapid loss of the fear of railroad trains or tele-
graph wires among birds, the rapid acquisition of arboreal
habits among Australian rodents, the use of proper feeding
grounds, etc., may be held to be due to imitation. The young
animal stays with or follows its mother from a specific instinct
to keep near that particular object, to wit, its mother. It may
thus learn to stay near trains, or scrabble up trees, or feed at
certain places and on certain plants. Actions due to following
pure and simple may thus simulate imitation. Other groups of
acts which now seem truly imitative may be indirect fruits of
some one instinct. This must be kept in mind when one esti-
mates the supposed imitation of parents by young. Further, it
is certain that in the case of the chick, where early animal life
has been carefully observed, instinct and individual experience
between them rob imitation of practically all its supposed in-
fluence. Chicks get along without a mother very well. Yet
no mother takes more care of her childrenthanthe hen. Care in
other cases, then, need not mean instruction through imitation.

These considerations may prevent an unreserved acceptance
of the common view that young animals get a great number of
their useful habits from imitation, but I do not expect or desire
them to lead to its summary rejection. I should not now myself
reject it, though I think it quite possible that more investigation
and experiment may finally reduce all the phenomena of so-
called imitation of parents by young to the level of indirect
results of instinctive acts.

Another special department of imitation may be at least
vaguely marked off: namely, apparent imitation of certain
limited sorts of acts which are somewhat frequent inthe animal’s
life. An example will do better than further definition.

Some sheep were being driven on board ship one at a time.
In the course of their progress they had to jump over a hurdle.
On this being removed before all had passed it, the next sheep
was seen to jump as if to get over a hurdle, and so on for five

ANIMAL INTELLIGENCE. 49

or six, apparently sure evidence that they imitated the action,
each of the one in front. Now, it is again possible that among
gregarious animals there may be elaborate connections in the
nervous system which allow the sight of certain particular acts
in another animal to arouse the innervation leading to those
acts, but that these connections are /émzted. The reactions on
this view are specific responses to definite signals, comparable
to any other instinctive or associational reaction. The sheep
jumps when he sees the other sheep jump, not because of a
general ability to do what he sees done, but because he is fur-
nished with the instinct to jump at such a sight, or because his
experience of following the flock over boulders and brooks and
walls has got him into the habit of jumping at the spot where
he sees one ahead of him jump; and so he jumps even though
no obstacle be in his way. If due to instinct the only peculiar-
ity of such a reaction would be that the sense-impression calling
forth the act would be the same act as done by another. If due
to experience there would be an exact correspondence to the
frequent acts called forth orzginally by several elements in a
sense-impression, one of which is essential, and done @/ter-
wards when only the non-essentials are present. These two
possibilities have not been sufficiently realized, yet they may
contain the truth. On the other hand, these limited acts may be
the primitive, sporadic beginnings of the general imitative
faculty which we find in man. To this general faculty we may
now turn, having cleared away some of the more doubttul
phenomena which have shared its name.

It should be kept in mind that an imitative act may be per-
formed quite unthinkingly, as when a man in the mob shouts
what the others shout or claps when the others clap; may be
done from an inference that since A by doing X makes pleasure
for himself, I by doing X may get pleasure for myself; may,
lastly, be done from what may be called a transferred associa-
tion. This process is the one of interest in connection with our
general topic, and most of my experiments on imitation were
directed to the investigation of it. Its nature is simple. One
sees the following sequence: ‘A turning a faucet, A getting a
drink.’ If one can free this association from its narrow con-

12) E. L. THORNDIKE.

finement to A, so as to get from it the association, ‘impulse to
turn faucet, me getting a drink,’ one will surely, if thirsty, turn
the faucet, though he had never done so before. If one can
from an act witnessed learn to do the act, he in some way
makes use of the sequence seen, transfers the process to him-
self; in the common human sense of the word, he zz¢ates.
This kind of imitation is surely common in human life. It may
be apparent in ontogeny before any power of inference is
shown. After that power does appear, it still retains a wide
scope, and teaches us a majority, perhaps, of the ordinary
accomplishments of our practical life.

Now, as the writers of books about animal intelligence have
not differentiated this meaning from the other possible ones, it is
impossible to say surely that they have uniformly credited it to
animals, and it is profitless to catalogue here their vague state-
ments. Many opposers of the ‘reason’ theory have presup-
posed such a process and used it to replace reason as the cause
of some intelligent performances. The upholders of the
reason theory have customarily recognized such a process and
claimed to have discounted it in their explanations of the vari-
ous anecdotes. So we found Mr. Romanes, in the passage
quoted, discussing the possibility that such an imitative process,
without reason, could account for the facts. In his chapter on
Imitation in ‘ Habit and Instinct,’ Principal C. Lloyd Morgan,
the sanest writer on comparative psychology, seems to accept
imitation of this sort as a fact, though he could, if attacked,
explain most of his illustrations by the simple forms. The
fact is, as was said before, that no one has analyzed or system-
atized the phenomena, and so one cannot find clear, decisive
statements to quote.

At any rate, whether previous authorities have agreed that
such a process is present or not, it is worth while to tackle the
question; and the formation of associations by imitation, if it
occurs, is an important division of the formation of associations

in general. The experiments and their results may now be
described.

ee

ANIMAL INTELLIGENCE. 5!

IMITATION IN CHICKS.

No. 64 learned to get out of a certain pen (16 x 10 inches)
by crawling under the wire screening at a certain spot. There
was also a chance to get out by walking up an inclined plane
and then jumping down. No. 66 was put in with 64. After 9
minutes, 20 seconds, 66 went out by the inclined plane, although
64 had in the mean time crawled out under the screen 9 times.
(As soon as he got out and ate a little he was put back.) It
was impossible to judge how many of these times 66 really saw
64 do this. He was looking in that direction 5 of the times.
So also, in three more trials, 66 used the inclined plane, though
64 crawled under each time. 67 was then tried. In 4 minutes,
ro seconds, he crawled under, 64 having done so twice. Being
then put in @/one, he, without the chance to imitate, still crawled
under. So probably he went under when with 64 not by imi-
tation but by accident, just as 64 had learned the thing himself.

>

FIG. 17. Fic. 18.

The accompanying figure (17) shows the apparatus used in
the next experiment. A represents the top of a box (5 x 4
inches), 13 inches above the level of the floor, C. On the floor
C were the chicks and food. B is the top of a box 10 inches
high. Around the edges of A except the one next B a wire
screen was placed, and 65 was repeatedly put upon A until he
learned to go quickly back to C va B. Then the screen was
bent outward at X so that a chick could barely squeeze through
and down (A to C). Eleven chicks were then one at a time
placed on A with 65. In every case but one they went A-C.
In the case of the chick (75) who went A-B-C, there could
have been no imitation, for he went down defore 65 did. One
other went through the hole before 65 went to b. The remain-

BE. L. THORNDIKE.

co
oo”

ing nine all had a chance to imitate 65 and to save the uncom-
fortable struggle to get through the hole, 65 going A-B-C 8
times before 68 went A-C, 2 times when with 66 and 76, once
in the case of each of the others.

In still another experiment the apparatus was (as shown in
figure 18) a pen 14 inches square, 10 inches high, with a wire
screen in front and a hole 3% inches square in the back. This
hole opened into a passage-way (B) leading around to C, where
were the other chicks and food. Chicks who had failed, when
put in alone, to find the way out, were put in with other chicks
who had learned the way, to see if by seeing them go out they
would learn the way. Chick 70 was given 4 trials alone, being
left in the box 76 minutes all told. He was then given g trials
(165 minutes) with another chick who went out vza B 36 times.
ro failed to follow him on any occasion. ‘The trials were all
given in the course of two days. Chick 73 failed in 1 trial
(12 minutes) to get out of himself, and was, then given 4 trials
(94 minutes) with another chick who went out va B 33 times.
In this experiment, as in all others reported, sure evidence that
the animals wanted to get out, was afforded by their persistent
peckings and jumpings at the screen or bars that stood between
them and C. Chick 72, after 8 unsuccessful trials alone (41
minutes), was given 8 trials with a chance to imitate. After the
other chick had gone out 44 times, 72 d¢d go out. Ue did not
follow the other but went 20 seconds later. It depends upon
one’s general opinion whether one shall attribute this one case
out of three to accident or imitation. :

I also took two chicks, one of whom learned to escape from
A (in figure 17) by going to B and jumping down the side to
the v7ght of A, the other of whom learned to jump down the
side to the /ef/, and placed them together upon A. Each took
his own course uninfluenced by the other in 10 trials.

Chicks were also tried in several pens where there was only
one possible way of escape to see if they would learn it more
quickly when another chick did the thing several times before
their eyes. The method was to give some chicks their first trial
with an imitation possibility and their second without, while
others were given their first trial without and their second with.

ANIMAL INTELLIGENCE. 53

If the ratio of the average time of the first trial to the average
time of the second is smaller in the first class than it is in the
second class, we may find evidence of this sort of influence by
imitation. Though imitation may not be able to make an ani-
mal do what he would otherwise zo¢ do, it may make him do
quicker a thing he would have done sooner or later any way.
As a fact the ratio is much larger. This is due to the fact that
a chick, when in a pen with another chick, is not afflicted by
the discomfort of loneliness, and so does not try so hard to get
out. So the other chick, who is continually being put ‘in
with him to teach him the way out, really prolongs his stay in.
This factor destroys the value of these quantitative experiments,
and I do not insist upon them as evidence against imitation,
though they certainly offer none for it. I do not give descrip-
tions of the apparatus used in these experiments or a detailed
enumeration of the results, because in this discussion we are
not dealing primarily with imitation as a slight general factor in
forming experience, but as a definite associational process in
the mind. The utter absence of imitation in this limited sense
is apparently demonstrated by the results of the following
experiments.

V was a box 16x 12 x 8%, with the front made of wire
screening and at the left end a little door held by a bolt but in
such a way that a sharp peck at the top of the door would force
it open.

W was a box of similar size, with a door in the same place
fixed so that it was opened by raising a bolt. To this bolt was
tied a string which went up over the top of the edge of the box
and back across the box, as in D. By jumping up and coming
down with the head over this thread, the bolt would be pulled
up. The thread was 8% inches above the floor.

X was a box of similar size, with door, bolt and string
likewise. But here the string continued round a pulley at the
back down to a platform in the corner of the box. By stepping
on the platform the door was opened.

Y was a box 12 x 8 x 8%, with a door in the middle of the
front, which I myself opened when a chick pecked at a tack
which hung against the front of the box 114 inches above the
top of the door.

54 BE. L. THORNDIKE.

These different acts, pecking at a door, jumping up and
with the neck pulling down a string, stepping on a platform,
and pecking at a tack, were the ones which various chicks were
given a chance to imitate. The chicks used were from 16 to 30
days old. The method of experiment was to puta chick in,
leave him 60 to So seconds, then put in another who knew the
act, and on his performing it, to let both escape. No cases were
counted unless the imitator apparently saw the other do the
thing. After about every ten such chances to learn the act,
the imitator was left in alone for ten minutes. The following
table gives the results. The imitators of course had previously
failed to form the association of themselves. F denotes failure
to perform the act:

ae : A Times in ; Laka
Chick. Act. No. Times Saw. | Which Failed. Final Time.

|
84 Vv 38 45.00 F 15.00 F
85 V 30 30.00 F 10.00 F
86 Vv 44 55.00 F 15.00 F
87 V 26 35.00 F 15.00 F
80 WwW 54 60.00 F 15.00 F
81 W 40 45.00 F 15.00 F
87 W 2 30.00 F 10.00 F
81 xX 18 20.00 F 10.00 F
82 x 21 20.00 F 8.40 Did
83 x 33 35.00 F 15-00 F
84 x 46 55-00 F 15.00 F
84 Xe 45 55-co F 15.00 F
83 Me 29 35.00 F 15.00 F

Thus out of all these cases only one did the act in spite of
the ample chance for imitation. I have no hesitation in declar-
ing 82’s act in stepping on the platform the result of mere acci-
dent, and am sure that any one who had watched the experi-
ments would agree.

IMITATION IN Cats.

By reference to the previous descriptions of apparatus, it
will be seen that box D was arranged with two compartments,
separated by a wire screen. The larger of these had a front
of wooden bars with a door which fell open when a string
stretched across the top was bitten or clawed down. The
smaller was closed by boards on three sides and by the wire

ANIMAL INTELLIGENCE. 55

screen on the fourth. Through the screen a cat within could
see the one to be imitated pull the string, go out through the
door thus opened and eat the fish outside. When put in this
compartment, the top being covered by a large box, a cat soon
gave up efforts to claw through the screen, quieted down and
watched more or less the proceedings going on in the other
compartment. Thus this apparatus could be used to test the
power of imitation. A cat who had no experience with the
means of escape from the large compartment was put in the
closed one; another cat, who would do it readily, was allowed
to go through the performance of pulling the string, going out,
and eating the fish. Record was made of the number of times
he did so and of the number of times the imitator had his eyes
clearly fixed on him. These were called ‘times seen.’ Cases
where the imitator was looking in the general direction of the
‘imitatee’ and might very well have seen him and probably did,
were marked ‘ doubtful.’ Inthe remaining cases the cat did
not see what was done by his instructor. After the imitatee
had done the thing a number of times, the other was put in the
big compartment alone, and the time it took him before pulling
the string was noted and his general behavior closely observed.
If he failed in 5 or 10 or 15 minutes to do so, he was released
and not fed. This entire experiment was repeated a number
of times. From the times taken by the imitator to escape and
from observation of the way that he did it, we can decide
whether ‘imitation played any part. The history of several
cases are given in the following tables. In the first column are
given the lengths of time that the imitator was shut up in the
box watching the imitatee. In the second column is the num-
ber of times that the latter did the trick. In the third and fourth
are the times that the imitator surely and possibly saw it done,
while in the last is given the time that, when tried alone, the
imitator took to pull the string, or if he failed, the time he was
in the box trying to get out. Times are in minutes and sec-
onds, failures denoted by F:

7 saw.

56 E. L. THORNDIKE.
Time No.of times
Watching. 2 did.
ay 10.00 II
After 48 Hours 11.00 Io
12.00 20
After 24 Hours 8.00 20
13.00 25
After 24 Hours g.00 20
After 24 Hours 12.00 35
After 2 Hours 10.00 25
After 24 Hours 15.00 25
After 24 Hours 6.00 20

Total times surely and possibly seen,

COWARD HA PAW

aN
WwW

No. 7 Imitating No. 2.

Doubtful.

\No.of iment NOlOE times| Time of 7

when alone.

10.00 F
1.001
3.30

10.00 F

20.00 F

10.00 F

30.00 F

25.00 F

20.00 F

10.00 F

| No. 5 Imitating No. 2.

Time |No.of times}
Watching. 2 did.
12.00 15
After 2 Hours 10.00 8
After 24 Hours 5-00 5
After 1 Hour 14.00 Io
After 1 Hour 13.00 22
After 24 Hours 7.00 15
After 48 Hours 18.00 20
After 24 Hours 14.00 20
After 24 Hours 10.00 20

Total times surely and possibly seen,

No.of times
5 saw.

Se WN NwaTn OF W

Time
Watching.

No.of times} Time of 5

Doubtful.

8

WOW DHWOWSE

No. 6 Imitating No. 2.

No. of times
2 did.

After 48 Hours
After 72 Hours
After 72 Hours
After 24 Hours
After 24 Hours
After 24 Hours

12.00
11.00
I0.00

6.00

9.00
10.00
10.00

Total times surely and possibly seen,

|

when alone.

5.00 F

10.00 F
10.00 F
5.00 F
20.00 F
30.00 F
20.00 F

No. of times|No. of times| Time of 6
Doubtful. }when alone.

6 saw.

re)

HOAHW OO

= Il

19
It
15

4
13

82

1.102

_'No. 7 hit the string in his general struggling, apparently utterly without
design. He did not realize that the door was open ullvewe seconds after it had
fallen, he happened to look that way.

* No. 6, in trying to crawl out at the top of the box, put its paw in above
the string. It fell down and thus pulled the string. It did not claw az it, and it
was 16 seconds before it noticed that the door was open. In all the other times
that it escaped the movement was made in the course of promiscuous scrabbling,
never in anything like the same way that No. 2 made it.

te
bi
ul

ANIMAL INTELLIGENCE.

A
“i

: aus ,
No. 3 Imitating No. 2.

| 8.00 | 30 2 19 | 3.30!
3-39
After 48 Hours 10.00 | 30 2 14 20
' 20
After 72 Hours | 10.00 | 30 2 S =
oO
Total time surely and possibly seen, - 6 4!

Before entering upon a discussion of the facts shown by
these tables, we must describe the behavior of the imitators, when,
after seeing 2 pull the string, they were put in alone. Inthe
opinion of the present observer there was not the slightest dif-
ference between their behavior and that of cats 4, 10, II, 12
and 13, who were put into the same position without ever having
seen 2 escape from it. 6, 7, 5 and 3 paid no more attention to
the string than they did, but struggled in just the same way.
No one, I am sure, who had seen them, would have claimed
that their conduct was at all influenced by what they had seen.
When they did hit the string the act looked just like the acci-
dental success of the ordinary association experiment. But, be-
sides these personal observations, we have in the impersonal
time-records sufficient proofs of the absence of imitation. If the
animals pulled the string from having seen 2 do so, they ought to
pull it in each individual case at an approximately regular length
of time after they were put in, and presumably pretty soon there-
after. That is, if an association between the sight of that string in
that total situation and a certain impulse and consequent freedom
and food had been formed in their minds by the observation of
the acts of 2, they ought to pull it on seecng zz, and if any dis-
turbing factor required that a certain time should elapse before
the imitative faculty got in working order, that time ought to be
somewhere near constant. The times were, as a fact, long and
irregular in the extreme. Furthermore, if the successful cases
were even in part due to imitation, the times ought to decrease
the more they saw 2 do the thing. Except with 3, they increase
or give place to failures. Whereas 6 and 7, if they had been
put in again immediately after their first successful trial and

1No. 3 did not go out until 12 seconds had elapsed after it had pulled the
string.

E. L. THORNDIKE.

1o/)

5

from then on repeatedly, would have unquestionably formed
the association, they did not, when put in after a further chance
to increase their knowledge by imitation, do the thing as soon
as before. The case of 3 is not here comparable to the rest be-
cause he was given three trials in immediate succession. He
was a more active cat and quicker to learn, as may be seen by
comparing his time curves with those of 7,6 and 5. That the
mere speed with which he mastered this association is no sign
that imitation was present may be seen by reference to the time
curves of 4 and 13 (on page 18).

Some cats were also experimented with in the following
manner. They were put into a box [No. 7 into box A (0 at
front), No. 5 into B (0 at back)] and left for from 45 to 75
seconds. Then a cat who knew the way to get out was put in,
and, of course, pulled at the loop and opened the door. Both
cats then went out and both were fed. After the cat had been
given a number of such chances to learn by imitation, he was
put in and left until he did the thing, or until 5 or 10 minutes
elapsed. Asin the preceding experiments, no change in their
behavior which might signify imitation was observed. No. 7
acted exactly like 3, or 10, or 11, when put in the box, ap-
parently forming the association by accident in just the same
way. Good evidence that he did not imitate is the fact that,
whereas 1 (whom he saw) pulled the loop with his teeth, 7
pulled it with his paw. 5 failed to form the association, though
he saw 3 do it 8 times and probably saw him 18 times more.
He did get out twice by clawing the s¢v7mg in the front of the
box, not the Joop in the Jack, as 3 did. These successes took
place early in the experiment. After that he failed when left
alone to get out at all.

Another/experiment was made by a still different method. My
cats were kept in a large box about 4 ft. high, the front of which
was covered with poultry-yard netting. Its top was a board
which could be removed. To save opening the door and letting
them all loose, I was in the habit of taking them out by the top
when I wanted to experiment with them. Of course the one
who happened to climb up (perhaps attracted by the smell of
fish on my fingers) was most likely to be taken out and experi-

ANIMAL INTELLIGENCE 59

mented with and fed. Thus they formed the habit of climbing
up the front of the box whenever I approached. Of three cats
which I obtained at the same time, one did not after 8 or 10
days acquire this habit. Even though I held out a piece of fish
through the netting, he would not climb after it. It was reason-
able to suppose that imitation might overcome this sluggishness,
if there were any imitation. I therefore put two cats with him
and had them climb up 80 times before his eyes and get fish.
He never followed or tried to follow them.

4 and 3 had been subjected to the following experiment. I
would make a certain sound and after 10 seconds would go up
to the cage and hold the fish out to them through the netting at
the top. They would then, of course, climb up and eat it.
After a while, they began to climb up upon hearing the signal
(4) or before the ro seconds were up. I then took 12 and 10,
who were accustomed to going up when they saw me approach,
but who had no knowledge of the fact that the signal meant
anything, and gave them each a chance to imitate 3. That is
one of them would be left in the box with 3, the signal would
be given, and after from 5 to 10 seconds 3 would climb up. At
10 seconds I would come up with food, and then of course 12
would climb up. This was repeated again and again. The
question was whether imitation would lead them to form the as-
sociation more quickly than they would have done alone. It
did not. That when at last they did climb up before ro seconds
was past, that is before I approached with food, it was not due
to imitation, is shown by the fact that on about half of such
occasions they climbed up Jefore 3 did. That is they re-
acted to the ségnal by association, not to his movements by imi-
tation.

IMITATION IN Docs.

Here the method was not to see if imitation could arouse
more quickly an act which accident was fairly likely to bring
forth sooner or later, but to see if, where accident failed, imita-
tion would succeed.

3 was found to be unable of himself to escape from box BB,
and was then given a chance to learn from watching tf. The

60 E. L. THORNDIKE.

back of box BBx was torn off and wire netting substituted for it.
Another box with open front was placed directly behind and
against box BB1. No. 3, who was put in this second box, could
thus see whatever took place in and in front of box BB1 (0 at
back, high). The record follows:

Dog 3 Imitating Dog I.

Times Times Times prob- Times
1 did. 3 saw. ably saw. in alone.

30 7 14 3.00

After1 Hour. - - 35 9 14 3.00 F

After1 Hour - - 10 3 2 5.00 F
After 24 Hours - = 20 6 8

30 8 13 6.00 F

After 48 Hours - - 25 8 II 8.co F

2 6 12 6.00 F

25 9 if 10.00 F

After 24 Hours - - 30 10 II 40.00 F
Total times surely and possibly seen, - 66 93

A similar failure to imitate was observed in the case of
another simple act. No. 1, as may be seen on page 33, had
learned to escape from a pen about 8 by 5 feet by jumping
up and biting a cord which ran from one end of the pen to
the other and at the front end was tied to the bolt which
held the door. Dogs 2 and 3 had failed in their accidental
jumping and pawing to hit this cord, and were then given a
chance to learn by seeing 1 do so, escape, and of course be fed.
1 always jumped in the same way, biting the cord at the same
place, namely where a loose end from a knot in it hung down 4
or 5 inches. 2 and 3 would either be tied up in the pen or left
in a pen at one side. They had a perfect chance to see 1 per-
form his successful act. After every twenty or thirty perform-
ances by 1, 2 and 3 would be put in alone. It should be
remembered that here, as also in the previous experiment and
all others, the imitators certainly wanted to get out when thus
left in alone. They struggled and jumped and pawed and bit,
but they never jumped az the cord. Their records follow.

ANIMAL INTELLIGENCE. 61

Dog 2 Imitating Dog 1.
Times | Times | Times Time 2 was
1 did. 2 saw. Doubtful. in alone
30 | 9 II 10.00 F
After 1 Hour, - - 30 10 9 10.00 F
After 48 Hours, - + 25 8 8
After 1 Hour, - 2 10 3 4 9.00 F!
After 24 Hours, - - 30 8 12 15.00 F
After 1 Hour, - - 30 9 12 | 15.00 F
After 48 Hours,- — - 20 7 6 | 10.00 F
20 8 7
After 48 Hours, - - 30 6 8 | 15.00 F
After 24 Hours, - - 15 2 4 | 10.00 F
Total times surely and possibly seen, - 70 81

Dog 3 Imitating Dog 1.
Time Times Times | Time 3 was
1 did. 3saw. | Doubtful. in alone.
30 10 fe) 10.00 F
After1 Hour, - - 30 9 10 | 10.00 F
After1 Hour, - - 15 6 4
After 24 Hours, - - 30 9 II 15.00 F
After 24. Hours, - - 30 10 12 15.00 F
After 1 Hour, - - 30 8 9 10.00 F
After 48 Hours, - . 20 6 7 40.00 F
After 1 Hour, - - 20 6 5
After 48 Hours, - - 30 8 9 15.00 F
After 24 Hours, - - 15 3 | 4 20.00 F
Total times surely and possibly seen, - 75 81

Another corroborative, though not very valuable, experiment
was the following: Dog 3 had been taught for the purpose of
another experiment to jump up on a box and beg when I helda
piece of meat above the box. I then caused him to do this 110
times (within two days) in the presence of 1. Although 1 saw
him at least 20 % of the times (3 was always fed each time he
jumped on the box), he never tried to imitate him.

It seems sure from these experiments that the animals were
unable to form an association leading to an act from having
seen the other animal, or animals, perform the act ina certain

1The back of the pen adjoined the elevator shaft, being separated from it
by a partition 33 inches high. No. 2 heard the elevator coming up and put his
paws up on the top of this partition so as to look over. In so doing he knocked

the fastening of the cord at that end and opened the door. He did not turn to
come out, andI shut the door again.

62 E. L. THORNDIKE.

situation. Thus we have further restricted the association pro-
cess. Not only do animals not have associations accompanied,
more or less permeated and altered, by inference and judg-
ment; they do not have associations of the sort which may be
acquired from other animals by imitation. What this implies
concerning the actual mental content accompanying their acts
will be seen later on. It also seems sure that we should give
up imitation as an @ frzov7 explanation of any novel intelligent
performance. To say that a dog who opens a gate, for in-
stance, need not have reasoned it out 7/ he had seen another dog
do the same thing, is to offer instead of one false explanation
another equally false. Imitation in any form is too doubtful a
factor to be presupposed without evidence. And if a general
imitative faculty is not sufficiently developed to succeed with
such simple acts as those of the experiments quoted, it must be
confessed that the faculty is in these higher mammals still rudi-
mentary and capable of influencing to only the most simple and
habitual acts, or else that for some reason its sphere of influence
is limited to a certain class of acts, possessed of some guadita-
tive difference, other than mere simplicity, which renders them
imitable. The latter view seems a hard one to reconcile with
a sound psychology of imitation or association at present, with-
out resorting to instinct. Unless a certain class of acts are by
the innate mental make-up especially tender to the influence of
imitation, the theory fails to find good psychological ground to
stand on. The former view may very well be true. But in
any case the burden of proof would now seem to rest upon the
adherents to imitation; the promising attitude would seem to be
one which went without imitation as long as it could, and that
is, of course, until it surely found it present.

Returning to imitation considered in its human aspect, to
imitation as a transferred association in particular, we find that
here our analytical study of the animal mind promises important
contributions to general comparative psychology. I it is true,
and there has been no disagreement about it, that the primates
do imitate acts of such novelty and complexity that only this out-
and-out kind of imitation can explain the fact, we have located
one great advance in mental development. Till the primates

ANIMAL INTELLIGENCE. 63

we get practically nothing but instincts and individual acquire-
ment through impulsive trial and error. Among the primates
we get also acquisition by imitation, one form of the increase of
mental equipment by tradition. The child may learn from the
parent quickly without the tiresome process of seeing for him-
self. The less active and less curious may share the progress
of their superiors. The brain whose impulses hitherto could
only be dislodged by specific sense-impressions may now have
any impulse set agoing by the sight of the movement to which
it corresponds.

All this on the common supposition that the primates do
imitate, that a monkey in the place of these cats and dogs would
have pulled the string. My apology for leaving the matter in
this way without experiments of my own is that the monkey
which I procured for just this purpose failed in two months to
become tame enough to be thus experimented on. Accurate in-
formation about the nature and extent of imitation among the
primates should be the first aim of further work in comparative
psychology, and will be sought by the present writer as soon as
he can get subjects fit for experiments.

In a questionnaire which was sent to fifteen animal-trainers, the following
questions were asked :

1. ‘‘ If one dog was in the habit of ‘ begging’ to get food and another dog
saw him do it ten or twenty times, would the second dog then beg himself?”

2. ‘*In general is it easier for you to teach a cat or dog a trick if he has
seen another do it?”

3. ‘*In‘general do cats imitate each other? Do dogs? Do monkeys?

4. ‘*Give reasons for your opinion, and please write all the reasons you
have.”

Five gentlemen (Messrs. R. C. Carlisle, C. L. Edwards, V. P. Wormwood,
H. S. Maguire and W. E. Burke) courteously responded to my questionnaire.
All are trainers of acknowledged reputation. To these questions on imitation
four replied.

To the first question we find the following answers: (@) ‘‘ Most dogs
would.” (4) ‘‘ Yes; he will very likely do it. He will try and imitate the other
dog generally.’”’ (c) ‘If a young dog with the mother, it would be very apt to

. With older dogs, it would depend very much upon circumstances.” (¢@)
** He would not.”

To 2 the answers were: (a) ‘‘ Very much easier.” (4) ‘It is always easier
if they see another one do it often.’’ (c) ‘‘ This would also depend on certain
conditions. In teaching to jump out of a box and in again, seeing another
might help, but in teaching something very difficult, Ido not think it would
Peithe' case.” (d) “It is not.”

64 E. L. THORNDIKE.

To 3 the answers were: (a) ‘‘ Yes. Some. More than either dogs or cats.”
(5) “Yes. Yes. Yes.” (c) ‘‘In certain things, yes; mostly in those things
which are in compliance to the laws of their own nature.” (d) ‘*No. No.
Yes, they are born imitators.”

The only definite answer to question 4 was: “ Take a dog or cat and close
them up in a room and go in and out several times, and you will find that they
will go to the door and stand up on their hind legs with front paws on the door
knob and try to open the door to get out. I could also give you a hundred more
such reasons.” This was given by (4).

The replies to a test question, however, go to show that
these opinions regarding imitation may be mistaken. Question
8 was: ‘If you wanted to teach a cat to get out of a cage by
opening an ordinary thumb-latch and then pushing the door,
would you take the cat’s paw and push down the thumb-piece
with it and then push the door open with the paw, or would you
just leave the cat inside until it learned the trick itself?” The sec-
ondis certainly the better way, as will be seen ina later part of this
paper, and pushing the latch with the cat’s paw has absolutely no
beneficial influence on the formation of the association, yet (a)
and (0) both chose the first way, and (c) answered ambiguously.
Further, the only reason given is, of course, no reason at all. It
proves too much, for if there were such imitation as that, my
cats and dogs would surely have done the far simpler things re-
quired of them. I cannot find that trainers make any practical
use of imitation in teaching animals tricks, and on the whole I
think these replies leave the matter just where it was before.
They are mere opinions—not records of observed facts. It
seems arrogant and may seem to some unjustifiable thus to dis-
card testimony, to stick to a theory based on one’s own experi-
ments in the face of these opinions. If I had wished to gain
applause and avoid adverse criticism, I would have abstained
from upholding the radical view of the preceding pages. At
times it seems incredible to me that the results of my experi-
ments should embody the truth of the matter, that there should
be no imitation. The theory based on them seems, even to me,
too radical, too novel. It seems highly improbable that I should
be right and all the others wrong. But I cannot avoid the
responsibility of giving what seems to my judgment the most
probable explanation of the results of the experiments; and that
is the radical explanation already given.

;
;

ANIMAL INTELLIGENCE. 65

Tue MENTAL Fact In ASSOCIATION.

It is now time to put the question as to just what is in an
animal’s mind when, having profited by numerous experiences,
he has formed the association and does the proper act when put
in a certain box. The commonly accepted view of the mental
fact then present is that the sight of the inside of the box re-
minds the animal of his previous pleasant exp rience after ¢s-

) ‘which he made which were imm edi-
soc ated with that escape. alls

1 that 2f the animal rememb hered the p
and remembered the movement, he would
/ It has been assumed that the association was an
association of zdeas; that when one of the ideas was of a move-
ment the animal was capable of making the movement. So,
for example, Morgan says, in the ‘ Introduction to Comparative
Psychology’: ‘‘If a chick takes a lady-bird in its beak forty
times and each time finds it nasty, this is of no practical value to
the bird unless the sight of the bird suggests ¢he nasty taste,”
p- 90.

Again, on page 92, Morgan says, ‘‘ A race after the ball had
been suggested through the channel of olfactory sensations.”
Also on page 86 ‘ * * * the visual impression suggested the idea
or representation of unpleasant gustatory experience.” The atti-
tude is brought out more completely in a longer passage on page
118: ‘Qn one of our first ascents one of them put up a young
coney, and they both gave chase. Subsequently they always hur-
ried on to this spot, and, though they never saw another coney
there, reiterated disappointment did not efface ¢he memory of that
jrrst chase, or so it seemed.” That is, according to Morgan, the
dogs thought of the chase and its pleasure, on nearing the spot
where it had occurred, and so hurried on. On page 148 of
‘Habit and Instinct,’ we read, ‘‘ Ducklings so thoroughly asso-
ciated water with the sight of their tin that they tried to drink
from it and wash in it when it was empty, nor did they desist
for some minutes,” and this with other similar phenomena is
attributed to the ‘association by contiguity’ of human psy-
chology.

66 E. L. THORNDIKE.

From these quotations it seems fairly sure that if we should
ask Mr. Morgan, who is our best comparative psychologist,
what took place in the mind of one of these cats of our experi-
ments during the performance of one of the ‘tricks,’ he would
reply: ‘* The cat performs the act because of the association of
ideas. He is reminded by the sight of the box and loop of his
experience of pulling that loop and of eating fish outside. So
he goes and pulls it again.” ‘This view has stood unchallenged,
but its implication is false. It implies that an animal, whenever
it thinks of an act, can supply an zmpulse to do the act. It takes
for granted that the performance of a cat who gets out of a box
is mentally like that of a man who thinks of going down street
or of writing a letter and then does it. The mental process is
not alike in the two cases, for animals can zo¢ provide the im-
pulse to do whatever act they think of. Vo cat can form an
association leading to an act unless there ts tncluded in the asso-
ciation an impulse of tts own which leads to the act. ‘There is
no general storehouse from which the impulse may be supplied
after the association is formed.

Before describing the experiments which justify these state-
ments, it will be worth while to recall the somewhat obvious
facts about the composition of one of these associations. There
might be in an association, such as is formed after experience
with one of our boxes, the following elements :

. Sense-impression of the interior of the box, etc.

(az) Discomfort and (6) desire to get out.

Representation of oneself pulling the loop.

Fiat comparable to the human ‘I'll do it.”

The impulse which actually does it.

. Sense-impression of oneself pulling the loop, seeing one’s
paw in a certain place, feeling one’s body in a certain way, etc.

7. Sense impression of going outside.

8. Sense-impression of eating, and the included pleasure.

Also between 1 and 4 we may have g, representations of one’s
experience in going out, 10, of the taste of the food, etc.

6, 7 and 8 come after the act and do not influence it, Ox
course, except in so far as they are the basis of the future 3’s,
g’s and 10’s. About 2 we are not at present disputing. Our

(nat 2S CS) fey

Se ee

4

ANIMAL INTELLIGENCE. 67

question is asto whether 3 or 5 is the essentialthing. In human
associations 3 certainly often is, and the animals have been
credited with the same kind. Whatever he /Ainks, Professor
Morgan surely /a/ks as if 1 aroused 9 and 10 and 3 and leaves
5 to be supplied at will. We have affirmed that 5 is the essen-
tial thing, that no association without a specific 5 belonging to
it and acquired by it can lead to an act. Let us look at the
reasons.

A cat has been made to go into a box through the door,
which is then closed. She pulls a loop and comes out and gets
fish. She is made to go in by the door again, and again lets
herself out. After this has happened enough times, the cat
will of her own accord go into the box after eating the fish. It
will be hard to keep her out. The old explanation of this
would be that the cat associated the memory of being in the
box with the subsequent pleasure, and therefore performed the
equivalent of saying to herself, ‘‘Goto! I will goin.” The
thought of dezng zm, they say, makes her go in. The thought
of being in will not make her goin. For if, instead of push-
ing the cat toward the doorway or holding it there, and thus
allowing it to itself give the impulse, to innervate the mus-
cles, to walk in, you shut the door first and drop the cat in
through a hole in the top of the box, she will, after escaping
as many times as in the previous case, zot go into the box of
her own accord. She has had exactly the same opportunity of
connecting the idea of being in the box with the subsequent
pleasure. Either a cat cannot connect ideas, representations, at
all, or she has not the power of progressing from the thought
of being in to the act of goingin. The only difference between
the first cat and the second cat is that the first cat, in the course
of the experience, has the impulse to crawl through that door,
while the second has not the impulse to crawl through the door
or to drop through that hole. So, though you put the second
cat on the box beside the hole, she doesn’t try to get into the
box through it. The impulse is the séze gua non of the asso-
ciation. The second cat has everything else, but cannot sup-
ply that. These phenomena were observed in six cats, three of
which were tried by the first method, three by the second. Of

68 BL. THORNDIEE:

the first three, one went in himself on the 26th time and fre-
quently thereafter, one on the 18th and the other on the 37th;
the two last as well as the first did that frequently in later trials.
The other three all failed to go in themselves after 50, 60 and
75 trials, respectively.

The case of No. 7 was especially instructive, though not
among these six. No. 7 had had some trials in which it was
put in through the door, but ordinarily in this particular experi-
ment was dropped in. After about 80 trials it would frequently
exhibit the following phenomena: It would, after eating the
fish, go up to the doorway and, rushing from it, search for fish.
The kitten was very small and would go up into the doorway,
whirl round and dash out, all in one quick movement. The
best description of its behavior is the paradoxical one that it
went out without going in. The association evidently con-
cerned what it had done, what it had an impulse for, namely,
coming out through that door to get fish, not what it remem-
bered, had a representation of.

Still more noteworthy evidence is found in the behavior of
cats and dogs who were put in these boxes, left one or two
minutes, and then put through the proper movement. For
example, a cat would be put in B (0 at back) and left two
minutes. I would then put my hand in through the top of the
box, take the cat’s paw and with it pull down the loop. The
cat would then go out and eat the fish. This would be done
over and over again, and after every ten or fifteen such trials
the cat would be left in alone. If in ten or twenty minutes he
did not escape, he would be taken out through the top and not
fed. In one series of experiments animals were taken and thus
treated in boxes from which their own impulsive activity had
failed to liberate them. The results, given in the table below,
show that no animal who fails to perform an act in the course of
his own impulsive activity will learn it by being put through it.

In these experiments some of the cats and all of the dogs
but No. 1 showed no agitation or displeasure at my handling
from the very start. Nor was there any in Dog 1 or the other
cats after a few trials. It may also be remarked that in the
trials alone which took place during and at the end of the ex-

ANIMAL INTELLIGENCE. 69

periment the animals without exception showed that they did
not fail to perform the act from lack of a desire to get out.
They all tried hard enough to get out and would surely have
used the association if they had formed it. ;

a2 jam | 33
| 2 26 25 ~
s Fea yt eee =
c Ole Tas os "Ow “a
5 Apparatus. ape (nae | sda oF
= rao | ope | FSs] 8”
Len) Price ON Tio ee S co =
ov + Ae °F ome oY a
Soe 3 Eos
EE a Oy, a
Cat 1 F (String outside unfastened) 55-00 "7 120.00 | 20.00
Cat 5 G (Thumb-latch) . - | 57.00 59 55-00 | 10.00
Cat 7 G (Thumb-latch) -~— - 50.00 30 35-00 | 10-00
Cat 2 G (Thumb-latch) - . 54.00 141 110.00 | 20.00
Dog 2 BB1 ‘3 at back, high) - | 48.00 | 30 80.00 | 60.00
Dog 3 BBr (0 at back, high) - 20.00 85 55.00 | 10.00
Dog 2 | M (Lever outside) - - | 15.00 95 140.00 30.00
Dog I BBS - - - - | 30.00 | 110 135.00 | 60.00
Chick 89} X (See page 53). 20.00 30 60.00 | 30.00
Cat 13 ekeke2 5 2 = = - - 40.00 65 60.00 10.00

Now, the only difference between the experiences of the ani-
mals in these experiments and their experiences in those where
they let themselves out, is that here they only saw and felt them-
selves making the movement, whereas in the other case they also
felt the impulse, gave the innervation. That, then, is the essen-
tial. It may be objected that the animals failed because they did
not attend to the process of being put through the movement,
that, had they attended to it, they would later themselves have
made the movement. It is, however, improbable that out of fifty
times an animal should not have attended to what was going on
at least two or three times. But if seeing himself do it was on a
par with feeling an impulse to and so doing it, even two or three
times would suffice to start the habit. And it is even more im-

1 FF was a box 40 X 21 X 24 inches, the door of which could be opened by
putting the paw out between the bars to its right and pulling a loop which hung
16 inches above the floor, 4 inches out from the box and six inches to the right
of the door.

2KKK was box K with both bolts removed. All that had to be done was to
poke the paw out at one side of the door and press down a little bar of wood.

3'The cats and chick were left in for two minutes at each trial, the dogs for
from one to one and a half minutes.

70 E. L. THORNDIKE.

probable that an experience should be followed by keen pleasure
fifty times and not be attended to with might and main, unless
animals attend only to their own impulses and the excitements
thereof. But if the latter be true, it simply affirms our view
from a more fundamental standpoint.

In another set of experiments animals were put in boxes
with whose mechanism they had had no experience, and from
which they might or might not be able to escape by their own
impulsive acts. The object was to see whether the time taken
to form the association could be altered by my instruction. The
results turned out to give a better proof of the inability to form
an association by being put through the act than any failure to
change the time-curve. For it happened in all but one of the
cases that the movement which the animal made to open the
door was different from the movement which I had put him
through. Thus, several cats were put through (in Box C [But-
ton]) the following movement: I took the right paw and, put-
ting it against the lower right-hand side of the button, pushed
it round to a horizontal position. The cats’ ways were as fol-
lows: No. 1 turned it by clawing vigorously at its top; No. 6,
by pushing it round with his nose; No. 7, in the course of an
indiscriminate scrabble at first, in later trials either by pushing
with his nose or clawing at the top, settling down finally to the
last method. Nos. 2 and 5 did itas No. 1 did. Cat 2 was
tried in B (o at back). Itook his paw and pressed the loop
with it, but he formed the habit of clawing and biting the string
at the top of the box near the front. No. 1 was tried in A. I
pressed the loop with his paw, but he formed the habit of bit-
ing at it.

In every case I kept on putting the animal through the act
every time, if at the end of two minutes (one in several cases)
it had not done it, even after it had shown, by using a different
way, that my instruction had no influence. I never succeeded
in getting the animal to change its way for mine. Moreover,
if any one should fancy that the animal really profited by my
instruction so as to learn what result to attain, namely, the turn-
ing of a certain button, but chose a way of his own to turn it,
he would be deluding himself. The time taken to learn the act
with instruction was no shorter than without.

ANIMAL INTELLIGENCE. 7%

If, then, an animal happens to learn an act by being put
through it, it is just happening, nothing more. Of course, you
may d@rect the animal’s efforts so that he will perform the act
himself the sooner. For instance, you may hold him so that his
accidental pawing will be sure to hit the vital point of the con-
trivance. But the animal can not form an association leading
to an act unless the particular impulse to that act is present as
an element of the association; he cannot supply it from a gen-
eral stock. The groundwork of animal associations is not the
association of zdeas, but the association of idea or sense-impres-
sion with zmpulse.

In the questionnaire mentioned elsewhere, some questions
were asked with a view to obtaining corroboration or refuta-
tion of this theory that an impulse or innervation is a necessary
element in every association formed if that association leads to
an act. The questions and answers were:

Question 1: ‘* If you wanted to teach a horse to tap seven times
with his hoof when you asked him, ‘‘ How many days are there
in a week?,” would you teach him by taking his leg and mak-
ing him go through the motions?”

A answered, ‘* Yes! at first.”

B answered, ‘‘ No! I would not.”

C answered, ‘ At first, yes!”

D answered, ‘‘ No!”

Question 2: **Do you think you couw/d teach him that way,
even if naturally you would take some other way?”

A answered, ‘‘In time, yes!”

B answered, ‘I think it would be a very hard way.”

C answered, ‘‘ Certainly I do.”

D answered, ‘‘I do not think I could.”

F answered, ‘‘ Yes.”

Question 3: ‘* How would you teach him?”

A answered, ‘I should tap his foot with a whip, so that
he would raise it, and reward him each time.”

B answered, ‘‘I should teach him by the motion of the
whip.”

C answered, ‘First teach him by pricking his leg the
number of times you wanted his foot lifted.”

72 E. L. THORNDIKE.

D answered, ‘‘ You put figure 2 on blackboard and touch
him on leg twice with cane, and so on.”

£ answered ambiguously.

It is noteworthy that even those who think they cou/d teach
an animal by putting him through the trick do not use that
method, except at first. And what they really do then is
probably to stimulate the animal to the reflex act of raising his
hoof. The hand simply replaces the cane or whip as the
means of stimulus. The answers are especially instructive, be-
cause the numerous counting tricks done by trained horses
seem, at first, to be incomprehensible, unless the trainer can
teach the horse by putting it through the movement the proper
number of times. The counting tricks performed by Mascot,
Professor Maguire’s horse, were quoted to me by a friend as
incomprehensible on my theory. The answers given above show
how simple the thing really is. All the counting-tricks of all the
intelligent horses depend on the fact that a horse raises his hoof
when a certain stimulus is given. One simple reaction gives
the basis for a multitude of tricks. In the same way other
tricks, which at first sight seem to require that the animal should
learn by being put through the movement, may depend on some
simple reflex or natural impulse.

Another question was, ‘* How would you teach a cat to get
out of a box, the door of which was closed with a thumb-latch ?”

A answered, ‘‘I should use a puff-ball as a plaything for
the cat to claw at.” This means, I suppose, that he would get
the cat to claw at the puff-ball and thus direct its clawings to
the vicinity of the thumb-piece.

B answered, ‘‘I would put the cat in and get it good and
hungry and then open the door by lifting the latch with my
finger. Then put some food that the cat likes outside, and she
will soon try to imitate you and so learn the trick.”

C answered, ‘‘I would first adjust all things in connection
with the surroundings of the cat so they would be applicable
to the laws of its nature, and then proceed to teach the trick.”

I suppose this last means that he would fix the box so that
some of the cat’s instinctive acts would lead it to perform the
trick. The answer given by B means apparently that he would

ANIMAL INTELLIGENCE. 73

simply leave the thing to accident, for any such imitation as he
supposes is out of the question. At all events, none of these
would naturally start to teach the trick by putting the animal
through the motions, which, were it a possible way, would
probably be a traditional one among trainers. On the whole, I
see in these data no reason for modifying our dogma that ani-
mals cannot learn acts without the impulse.

Presumably the reader has already seen budding out of this
dogma a new possibility, a further simplification of our theories
about animal consciousness. The possibility is that animals
may have xo zmages or memortes at all, no ideas to associate.
Perhaps the entire fact of association in animals is the presence of
sense-impressions with which are associated, by resultant pleas-
ure, certain impulses, and that therefore, and therefore only,
a certain situation brings forth a certain act. Returning to our
analysis of the association, this theory would say that there was
no (9g) or (10) orf(3) or (4), that the sense-impression gave
rise, when accompanied by the feeling of discomfort, to the im-
pulse (5) directly, without the intervention of any representa-
tions of the taste of the food, or the experience of being outside,
or the sight of oneself doing the act. This theory might be
modified so as to allow that the representations could be there,
but to deny that they were necessary, were inevitably present,
that the impulse was connected to the sense-impression through
them. It would then claim that the effective part of the associa-
tion was a direct bond between the situation and the impulse,
but would not cut off the possibility of there being an aura of
memories along with the process. It then becomes a minor
question of interpretation which will doubtless sooner or later
demand an answer. I shall not try to answer it now. The
more radical question, the question of the utter exclusion of
representative trains of thought, of any genuine association of
zdeas from the mental life of animals, is worth serious consider-
ation. I confess that, although certain authentic anecdotes and
certain experiments to be described soon, lead me to reject this
exclusion, there are many qualities in animals’ behavior which
seem to back it up. If one takes his stand by a rigid applica-
tion of the law of parsimony, he will find justification for this
view which no experiments of mine can overthrow.

"4 E. L. THORNDIKE.

Of one thing I am sure, and that is that it is worth while to
state the question and how to solve it, for although the point of
view involved is far removed from that of our leading psycholo-
gists to-day, it cannot long remain so. I am sorry that I can-
not pretend to give a final decision.

The view seems preposterous because, if an animal has sense-
impressions when his brain is excited by currents starting in the
end-organs, it seems incredible that he should not be conscious
in imagination and memory by having similar excitations caused
from within. We are accustomed to think of memory as the
companion of sensation. But, after all, it is a question of fact
whether the connections in the cat-brain include connections be-
tween present sensation-neuroses and past sensation-neuroses.
The only connections may be those between the former and im-
pulse-neuroses, and there is no authori itative reason why we
should suppose any others unless they are demonstrated by the
cat’s behavior. This is just the point at issue. Such evidence
as the phenomena of animals’ dreams does not at all prove the
presence of memory or imagination. A dog may very well
growl in his sleep without any idea of a hostile dog. ‘The im-
pulse to growl may be caused by chance excitement of its own
neurosis without any sensation-neurosis being concerned. Ac¢s of
recognition may have no feelings of recognition going with or
causing them. A sense-impression of me gets associated in my
dog’s mind with the impulses to jump on me, lick my hand,
wag his tail, etc. If, after a year, the connection between the
two has lasted, he will surely jump on me, lick my hand and
wag his tail, though he has not and never had any representa-
tion of me.

The only logical way to go at this question and settle it
is, I think, to find some association the formation of which re-
quires the presence of images, of ideas. You have to give an
animal a chance to associate sense-impression A with sense-
impression B and then to associate B with some act C so that
the presence of B in the mind will lead to the performance of
C. Presumably the representation of B, if present, will lead to
C just as the sense-impression B did. Now, if the chance to
associate B with A has been improved, you ought, when the

cee be el atl

ANIMAL INTELLIGENCE. 75

animal is confronted with the sense-impression A, to get a re-
vival of B and so the act C. Such a result would, if all chance
to associate C with A had been eliminated, demonstrate the
presence of representations and their associations. I performed
such an experiment in a form modified so as to make it prac-
ticable with my animals and resources. Unfortunately, this
modification spoils the crucial nature of the experiment and
robs it of much of its authority. The experiment was as
follows :

A cat was in the big box where they were kept (see page
58) very hungry. As I had been for a long time the source of
all food, the cats had grown to watch me very carefully. I sat,
during the experiment, about eight feet from the box, and would
at intervals of two minutes clap my hands four times and say,
‘¢T must feed those cats.” Of course the cat would at first feel
no impulse except perhaps to watch me more closely when this
signal was given. After ten seconds had elapsed I would take
a piece of fish, go up to the cage and hold it through the wire
netting, three feet from the floor. The cat would then, of course,
feel the impulse to climb up the front of the cage. In fact,
experience had previously established the habit of climbing up
whenever I moved toward the cage, so that in the experiment
the cat did not ordinarily wait until I arrived there with the
fish. In this experiment :

A=The sense-impression of my movements and voice when
giving the signal.

B=The sense-impression of my movements in taking fish,
rising, walking to box, etc.

C=The act of climbing up, with the impulse leading there-
unto.

The question was whether after a while A would remind the
cat of B, and cause him to do C before he got the sense-
impression of B, that is, before the ten seconds were up. If A
leads to C through a memory of B, animals surely cam have as-
sociation of ideas proper, and probably often do. Now, as a
fact, after from thirty to sixty trials, the cat does perform C im-
mediately on being confronted by A or some seconds later, at
all events before B is presented. And it is my present opinion

76 EE. L. THORNDIKE.

that their action is to be explained by the presence, through
association, of the idea B. But it is not impossible that
A was associated dzrectly with the impulse to C, although that
impulse was removed from it by ten seconds of time. Such
an association is, it seems to me, highly improbable, unless the
neurosis of A, and with it the psychosis, continues until the im-
pulse to C appears. But if it does so continue during the ten
seconds, and thus get directly linked to C, we have exactly a
representation, an image, a memory, in the mind for eight of
those ten seconds. It does not help the deniers of images to
substitute an image of A for animage of B. Yet, unless they
do this they have to suppose that A comes and goes, and that
after ten seconds C comes, and, passing over the intervening
blank, willfully choses out A and associates itself with it. There
are some other considerations regarding the behavior of the
cats from the time the signal was given till they climbed up,
which may be omitted in the hope that it will soon be possible
to perform a decisive experiment. If an observer can make
sure of the animal’s attention to a sequence A B, where B
does not arouse any impulse to an act, and then later get the
animal to associate B with C, leaving A out this time, he may
then, if A, when presented anew, arouses C, bid the deniers of
representations to forever hold their peace.

Another reason for allowing animals representations and
images is found in the longer time taken to form the association
between the act of licking or scratching and the consequent
escape. If the associations in general were simply between
situation and impulse and act, one would suppose that the situa-
tion would be associated with the impulse to lick or scratch as
readily as with the impulse to turn a button or claw a string,
Such is not the case. By comparing the curves for Z on pages
22, 23 with the others one sees that for so simple an act it takes
a long time to form the association. This is not a final reason,
for lack of attention, a slight increase in the time taken to open
the door after the act was done, or an absence of preparation in
the nervous system for connections between these particular acts
and definite sense-impressions, may very well have been the
cause of the difficulty in forming the associations. Nor is it

ea £8 AS

ANIMAL INTELLIGENCE 77

certain that zdeas of clawing loops would be easier to form

than ideas of scratching or licking oneself. The matter is
still open to question. But, as said before, my opinion would
be that animals do have representations and that such are the
beginning of the rich life of ideas in man. For the most part,
however, such are confined to specific and narrow practical
lines. ‘There was no evidence that my animals habitually did
form associations of ideas from their experience throughout, or
that such were constantly revived without the spur of immediate
practical advantage.

Before leaving the topic an account may be given of experi-
ments similar to the one described above as performed on cats
3 and 4, which were undertaken with Cat 13 and Dogs 1, 2
and 3.

Cat 13 was fed with pieces of fish at the top of the wire
netting 45 times, to accustom it to climbing up when it saw me
come with fish. I then went through the same process as with
3 and 4, but at intervals of 60 to go seconds instead of 120.
After 90 such trials it occasionally climbed up a little way, but
though 135 trials in all were given it never made the uniform
and definite reaction which 3 and 4 did. It reacted, when it
reacted at all, at from 5 to 9 seconds after the signal. Whether
age, weight, lack of previous habitual climbing when I ap-
proached, or a slowness in forming the association made the
difference, is uncertain.

Dog i was experimented on in the following manner: I
would put him in a big pen, 20-10 feet, and sit outside facing it,
he watching me as was his habit. I would pound with a stick
and say, ‘‘Go over to the corner.” After an interval (10 seconds
for 35 trials, 5 seconds for 60 trials) I would go over to the
corner (12 feet off) and drop a piece of meat there. He, of
course, followed and secured it. On the 6th, 7th, 16th, 17th,
18th and roth trials he did perform the act before the 1o sec-
onds were up, then for several times went during the two-minute
intervals without regarding the signal, and finally abandoned
the habit altogether, although he showed by his behavior when
the signal was given that he was not indifferent to it.

Dogs 1, 2 and 3 were also given 95, 135 and 95 trials, re-

78 E. L. THORNDIKE.

spectively, the acts done being (1) standing up against the wire
netting inclosing the pen, (2) placing the paws on top of a keg,
and (3) jumping up onto a box. The time intervals were 5
seconds in each case. No dog of these ever performed the act
before I started to take the meat to feed them, but they did
show, by getting up if they were lying down, when the signal
was given, or by coming to meif they were in some other part of
the pen, that something was suggested to them by it. Why these
cases differ from the cases of Cats 3 and 4 (10 and 12 also pre-
sented phenomena like those reported in the cases of 3 and 4) is
an interesting though not very important question. The dogs
were not kept so hungry as were the cats, and experience had cer-
tainly not rendered the particular impulses involved so sensitive,
so ready to discharge. Dogs 2 and 3 were older. There is
no reason to invoke any qualitative difference in the mental
make-up of the animals until more illuminating experiments are
made.

ASSOCIATION BY SIMILARITY AND THE FORMATION OF
CoNncEPTS.

What there is to say on this subject from the standpoint of
my experiments will be best introduced by an account of the
experiments themselves.

Dog 1 had escaped from AA (0 at front) 26 times. He was
then put in BB (0 at back). Now, whereas 2 and 3, who were
put in without previous experience with AA, failed to paw the
loop in BB, No. 1 succeeded. His times were 7.00, .35, 2.05,
-40, .32, .10, I.10, .38, .10, .05, and from then on he pawed
the loop as soon as put in the box. After a day or so he was
put inBBr (0 at back high). Although the loop was in a new
position, his times were only .20, .10, .10, etc. After nine
days he was put in a box arranged with a little wooden plat-
form 2% inches square, hung where the loop was in BBr.
Although the platform resembled the loop not the least save in
position, his times were only .10, .07, .05, etc.

From the curves given in Figure 19, which tell the history
Gi 40, hie anid 12s ane (o at back) after each had pre-
viously been familiarized with A (0 at front), we see this same

ANIMAL INTELLIGENCE. 79

influence of practice in reacting to one mechanism upon the
time taken to react to a mechanism at all similar. It naturally
takes a cat a longer time to accidentally claw a loop in the
back than in the front, yet a comparison of these curves with
those on page 18, Figure 2, shows the opposite to have been
the case with 10, 11 and 12. The same remarkable quickness
was noted in Cats 1 and 3 when put into B (o at back) after
learning A (o at front). Moreover, the loops were not alike.
The loop in A was of smaller wire, covered with a bluish
thread, while the loop in B was covered with a black rubber
compound, the diameter of the loop being three times that of
A’s loop.

10 wR. =

12 w Bi.

tlw Bi.

FIG. 19.

If any advocate of reason in animals has read so far, I doubt
not that ‘his heart has leaped with joy at these two preceding
paragraphs. <‘‘ How,” he will say, ‘*can you explain these
facts without that prime factor in human reason, association by
similarity? Surely they show the animal perceiving likenesses
and acting from general ideas.” Ths zs the very last thing
that they show. Let us see why they do not show this and what
they do show. He who thinks that these animals had a general
notion of a loop-like thing as the thing to be clawed, that they
felt the loop in B, different as it was in size, color and position,
to be still a loop, to have the essential quality of the other, must
needs presuppose that the cat has a clear, accurate sensation
and representation of both. Only if the cat discriminates can
it later associate by noticing similarities. This is what such

So E. L. THORNDIKE.

thinkers do presuppose. A bird, for instance, dives in the same
manner into a river of yellow water, a pond or an ocean. It
has a general notion, they say, of water. It knows that river
water is one thing and pond-water another thing, but it knows
that both are water, evgo, fit to dive into. The cat who reacts
to a loop of small wire of a blue color knows just what that loop
is, and when it sees a different loop knows its differences, but
knows also its likeness, and reacts to the essential. Thus
crediting the cat with our differentiation and perception of indi-
viduality, they credit it with our conceptions and perceptions of
similarity. Unless the animal has the first there is no reason
to suppose the last. Now, the anzmal does not have either. Mt
does not in the first place react to that particular loop in A,
with recognition of its qualities. It reacts toa vague, ill-defined
sense-impression, undiscriminated and even unperceived in the
technical sense of the word. Morgan’s phrase, ‘‘ a bit of pure
experience,” is perhaps as good as any. ‘The loop 1s to the cat
what the ocean is to a man, when thrown inio it when half-
asleep. Thus the cat who climbed up the front of the cage
whenever I said, ‘‘I must feed those cats,” would climb up just
as inevitably when I said, ‘*‘ My name is Thorndike,” or ‘* To-
day is Tuesday.” So cats would claw at the loop or button
when the door was cpen. So cats would paw at the place
where a loop had been, though none was there. The reaction
is not to a well-discriminated object, but to a vague situation, and
any element of the situation may arouse the reaction. The
whole situation in the case of man is speedily resolved into ele-
ments; the particular elements are held in focus, and the non-
essential is systematically kept out of mind. In the animal the
whole situation sets loose the impulse; all of its elements, in-
cluding the non-essentials, get yoked with the impulse, and the
situation may be added to or subtracted from without destroying
the association, provided you leave something which will set off
the impulse. The animal does not think one is like the other,
nor does it, as is so often said, mistake one for the other. It
does not think adow? it at all; it just thinks 7¢, and the 7¢ is the
kind of ‘pure experience” we have been describing. In
human mental life we have accurate, discriminated sensa-

ANIMAL INTELLIGENCE. Si

tions and perceptions, realized as such, and general notions,
also realized as such. Now, what the phenomena in ani-
mals which we have been considering show is that they
have neither. Far from showing an advanced stage of men-
tality, they show a very primitive and unspecialized stage.
They are to be explained not by the presence of general notions,
but by the absence of notions of particulars. The idea that
animals react to a particular and absolutely defined and realized
sense-impression, and that a similar reaction to a sense-impres-
sion which varies from the first proves an association by simi-
larity, is a myth. We shall see later how an animal does come
in certain cases to discriminate, in one sense of the word, witha
great degree of delicacy, but we shall also see then what must
be emphasized now, that naturally the animal’s brain reacts very
coarsely to sense-impressions, and that the animal does not think
about his thoughts at all.

- This puts a new face upon the question of the origin and
development of human abstractions and consequent general
ideas. It has been commonly supposed that animals had ‘ re-
cepts’ or such semi-abstractions as Morgan’s ‘ predominants,’
and that by associating with these arbitrary and permanent
signs, such as articulate sounds, one turned them into genuine
ideas of qualities. Professor James has made the simple but
brilliant criticism that all a recept really means is @ tendency ¢o
react in a certain way. But I have tried to show that the fact
that an animal reacts alike to a lot of things gives no reason to
believe that it is conscious of their common quality and reacts
to that consciousness, because the things it reacts to in the first
place are not the hard-and-fast, well-defined ‘things’ of human
life. What a ‘recept’ or ‘ predominant’ really stands for is no
thing which can be transformed into a notion of a quality by
being labelled with a name. This easy solution of the problem
of abstraction is impossible. A true idea of the problem itself
is better than such a solution.

My statement of what has been the course of development
along this line is derived from observations of animals’ behavior
and Professor James’ theory of the nature of and presumable
brain processes going with the abstractions and conceptions of

82 EWE. LHORNDITE:

human consciousness, but it is justified chiefly by its harmony
with the view that conception, the faculty of having general
notions, has been naturally selected by reason of its utility.
The first thing is for an animal to learn to react alike only to
things which resemble each other in the essentza/ qualities. On
an artificial, analytic basis, feelings of abstract qualities might
grow out of reacting alike to objects similar in such a respect
that the reaction would be useless or harmful. But in the actual
struggle for existence, starting with the mammalian mind as we
have found it, you will tend to get reactions to the denefczal
similarities by selection from among these so-called mistakes,
before you get any general faculty of noticing similarities. In
order that this faculty of indifferent reaction to different things
shall grow into the useful faculty of indifferent reaction to dif-
ferent things whzch have all some quality that makes the reaction
a fit one, there must be a tremendous range of associations.
For a lot of the similarities which are non-essential have to be
stamped out, not by a power of feeling likeness, but by their
failure to lead to pleasure. With such a wide range of asso-
ciations we may get reactions on the one hand where impulses
have been connected with one particular sense-impression be-
cause when connected with all others they had failed to give
pleasure, and on the other hand reactions where an impulse has
been connected with numerous different impressions possessing
one common quality, and disconnected with all impressions,
otherwise like these, which fail to have that one quality.
Combined with this multiplication of associations, there is,
I think, an equally important factor, the loosening of the ele-
ments of an association from one another and from it as a
whole. Probably the idea of the look of the loop or lever or
thumb-latch never entered the mind of any one of my cats
during the months that they were with me, except when the
front end of the association containing it was excited by putting
the cat into the box. In general, the unit of their consciousness,
apart from impulses and emotions, is a whole association-series.
Such soil cannot grow general ideas, for the ideas, so long as
they never show themselves except for a particular practical
business, will not be thought about or realized in their nature

-“—-". 6

ANIMAL INTELLIGENCE 83

or connections. If enough associations are provided by a
general curiosity, such as is seen among the monkeys, if the
mental elements of the association are freed, isolated, felt by
themselves, ¢en a realization of the ideas, feelings of their
similarity by transition from one to the other, feelings of qual-
ities and of meanings, may gradually emerge. Language will
be a factor in the isolation of the ideas and a help to their
realization. But when anyone says that language has been the
cause of the change from brute to man, when one talks as if not/-
ing but ct were needed turn animal consciousness into human,
he is speaking as foolishly as one who should say that a pro-
boscis added to a cow would make it an elephant.

This is all I have to say, in this connection, about associa-
tion by similarity and conception, and with it is concluded our
analysis of the nature of the association-process in animals.
Before proceeding to treat of the delicacy, complexity, number
and permanence of these associations, it seems worth while to
attempt to describe graphically, not by analysis, the mental fact
we have been studying, and also to connect our results with the
previous theories of association.

One who has seen the phenomena so far described, who has

watched the life of a cat or dog for a month or more under test

conditions, gets, or fancies he gets, a fairly definite idea of what
the intellectual life of a cat or dog feels like. It is most like
what we feel when consciousness contains little thought about
anything, when we feel the sense-impressions in their first
intention, so to speak, when we feel our own body, and the
impulses we give to it. Sometimes one gets this animal con-
sciousness while in swimming, for example. One feels the
water, the sky, the birds above, but with no thoughts adou/ them
or memories of how they looked at other times, or «esthetic
judgments about their beauty; one feels no ¢deas about what
movements he will make, but feels himself make them, feels
his body throughout. Self-consciousness dies away. Social
consciousness dies away. The meanings, and values, and con-
nections of things die away. One feels sense-impressions, has
impulses, feels the movements he makes ; that is all.

This pictorial description may be supplemented by an ac-

$4 E. EE. THORNDIKE.

count of some associations in human life which are learned in
the same way as are animal associations; associations, there-
fore, where the process of formation is possibly homologous
with that in animals. Whena man learns to swim, to play tennis
or billiards, or to juggle, the process is something like what
happens when the cat learns to pull the string to get out of the
box, provided, of course, we remove, in the man’s case, all the
accompanying mentality which is not directly concerned in
learning the feat.'. Like the latter, the former contains de-
sire, sense-impression, impulse, act and possible representations.
Like it, the former is learned gradually. Moreover, the asso-
ciations concerned cannot be formed by imitation. One does
not know how to dive just by seeing another man dive. You
cannot form them from being put through them, though, of
course, this helps indirectly, in a way that it does not with ani-
mals. One makes use of no feelings of a common element, no
perceptions of similarity. The tennis player does not feel,
*« This ball coming at this angle and with this speed is similar in
angle, though not in speed, to that other ball of an hour ago,
therefore I will hit it in a similar way.” He simply feels an
impulse from the sense-impression. Finally, the elements of
the associations are not isolated. No tennis-player’s stream of
thought is filled with free-floating representations of any of the
tens of thousands of sense-impressions or movements he has
seen and made on the tennis-court. Yet there is consciousness
enough at the time, keen consciousness of the sense-impressions,
impulses, feelings of one’s bodily acts. So with the animals.
There is consciousness enough, but of this kind.

1 A man may learn to swim from the general feeling, ‘‘ I want to be able to ©
swim.” While learning, he may think of this desire, of the difficulties of the mo-
tion, of the instruction given him, or of anything which may turn up in his
mind. This is all extraneous and is not concerned in the acquisition of the as-
sociation. Nothing like it, of course, goes on in the animal’s mind. Imagine a
man thrown into the water repeatedly, and gradually floundering to the shore in
better and better style until finally, when thrown in, he swims off perfectly, and
deprive the man of all extraneous feelings, and you have an approximate homo-
logue of the process in animals. He feels discomfort, certain impules to floun-
der around, some of which are the right ones to move his body to the shore.
The pleasure which follows stamps in these and gradually the proper move-

ments are made immediately on feeling the sense-impression of surrounding
water.

ANIMAL INTELLIGENCE. 5

Thus, the associations in human life, which compare with
the simple connections learned by animals, are associations in-
volving connections between novel, complex, and often incon-
stant sense-impressions and impulses to acts similarly novel,
complex and often inconstant. Man has the elements of most
of his associations in isolated form, attended to separately, pos-
sessed as a permanent fund, recallable at will, and multi-
fariously connected among themselves, but with these associa-
tions which we have mentioned, and with others like them, he
deals as the animals deal with theirs. The process, in the
man’s mind, leaving out extraneous mental stuff, may be homo-
logous to the association-process in animals. Of course, by
assiduous attention to the elements of these associations, a man
may isolate them, may thus get these associations to the same
plane as the rest. But they pass through the stage we have
described, even then, and with most men, stay there. The
abstraction, the naming, etc., generally come from observers of
the game or action, and concern things as felt by them, not by
the participant.

CRITICISM OF PREvi0oUS THEORIES.

We may now look for a moment at what previous writers
have said about the nature of association in animals. ‘The com-
plaint was made early in this book that all the statements had
been exceedingly vague and of no value, except as retorts to
the ‘reason’ school. In the course of the discussion I have
tried to extricate from this vagueness definite statements about
imitation, association of ideas, association by ideas. There Is
one more theory, more or less hidden in the vagueness; the
theory that association in animals is the same as association in
man, that the animal mind differs from the human mind only
by the absence of reason and what it implies. Presumably,
silence about what association is, means that it is the associa-
tion which human psychology discusses. When the silence is
broken, we get such utterances of this theory as the following :

‘© ] think we may say then that the higher animals are able
to proceed a long way in the formation and definition of highly
complex constructs, analogous to but probably differing some-

86 E. L. THORNDIKE.

what from those which we form ourselves. These constructs,
moreover, through association with reconstructs or representa-
tions, link themselves in trains so that a sensation, or group of
sensations, may suggest a series of reconstructs, or a series of
remembered phenomena.” (C. L. Morgan, ‘ Animal Life and
Intelligence,’ p. 341.)

‘¢ Lastly, before taking leave of the subject of the chapter, I
am most anxious that it should not be thought that, in contend-
ing that intelligence is not reason, I wish in any way to dis-
parage intelligence. Nine-tenths at least of the actions of aver-
age men are intelligent and not rational. Do we not all of us
know hundreds of practical men who are in the highest degree
intelligent, but in whom the rational, analytic faculty is but little
developed ? Is it any injustice to the brutes to contend that
their inferences are of the same order as those of these excellent
practical folk? In any case, no such injustice is intended; and
if I deny them self-consciousness and reason I grant to the
higher animals perceptions of marvellous acuteness and intelli-
gent inferences of wonderful accuracy and precision—intelligent
inferences in some cases, no doubt, more perfect even than those
of man, who is often disturbed by many thoughts” (ibid., p.
376-377).

‘* Language and the analytic faculty it renders possible, dif-
ferentiate man from the brute” (ibid., p. 374).

Here, as elsewhere, it should be remembered that Lloyd
Morgan is not quoted because he is the worst offender or be-
cause he represents the opposite in general of what the present
writer takes to be the truth. On the contrary, Morgan is
quoted because he is the least offender, because he has taken
the most advanced stand along the line of the present investi-
gation, because my differences from him are in the line of his
differences from other writers. With the theory of the passages
just quoted, however, which attribute extensive association of
ideas and general powers comparable to those of men minus
reason, to the brutes, and which repeat the time-honored dis-
tinction by language, I do not, in the least, agree. Associa-
tion in animals does not equal association in man. The latter
is built over and permeated and transformed by inference and

ANIMAL INTELLIGENCE. >7

judgment and comparison; it includes imitation in our narrow
sense of transferred association ; it obtains where no impulse is
included; it thus takes frequently the form of long trains of
thought ending in no pleasure-giving act; its elements are often
loose, existing independently of the particular association; the
association is not only thought, but at the same time thought
about. None of these statements may be truthfully made of
animal association. Only a small part of human association is
at all comparable to it. My opinion of what that small part is
has already been given. Moreover, further differences will be
found as we consider the data relating to the delicacy, com-
plexity, number, and permanence of associations in animals.
I said a while ago that man was no more an animal with lan-
guage than an elephant was a cow with a proboscis. We may
safely broaden the statement and say that man zs not an animal
plus reason. It has been one great purpose of this investiga-
tion to show that even after leaving reason out of account, there
are tremendous differences between man and the higher ani-
mals. The problem of comparative psychology is not only to
get human reason from some lower faculties, but to get human
association from animal association.

Our analysis, necessarily imperfect because the first at-
tempted, of the nature of the association-process in animals is
finished and we have now to speak of its limitations in respect
to delicacy, complexity, number and permanence.

DELICACY OF ASSOCIATIONS.

It goes without saying that the possible delicacy of asso-
ciations is conditioned by the delicacy of sense-powers. If an
animal doesn’t feel differently at seeing two objects, it cannot
associate one with one reaction, the other with another. An
equally obvious factor is attention; what is not attended to will
not be associated. Beyond this there is no @ Prior? reason why
an animal should not react differently to things varying only
by the most delicate difference, and I am inclined to think an
animal could; that any two objects with a difference appreciable
by sensation which are also able to win attention may be re-
acted to differently. Experiments to show this are very tedious

88 EE THORN DIE.

and the practical question is, ‘‘ What will the animal naturally
attend to?” The difficulty, as all trainers say, is to get the
animal’s attention to your signal somehow. ‘Then he will in
time surely react differently, if you give him the chance, to a
figure 7 on the blackboard from the way he does to a figure 8,
to your question, ‘‘ How many days are there in a week?”
and to your question, ‘*‘ How many legs have your” The chim-
panzee in London that handed out 3, 4, 5, 6 or 7 straws at
command was not thereby proved of remarkable intelligence or
of remarkably delicate associative power. Any reputable ani-
mal trainer would be ashamed to exhibit a horse who could not
do as much ‘ counting’ as that. The maximum of delicacy in
associating exhibited by any animal, to my knowledge, is dis-
played in the performance of the dog ‘ Dodgerfield,’ exhibited
by a Mr. Davis, who brings from four cards, numbered 1, 2, 3
and 4, whichever one his master shall ¢hznk of. That is, you
write outian- arbitrary list,.e. @.5 452,06 3sae aera nee
etc., and hand it to Mr. Davis, who looks at the list, thinks of
the first number, says ‘* Attention! Dodger !” and then, ‘* Bring
it.” This the dog does and so on through the list. Mr. Davis
makes no signals which anyone sitting even right beside or in
front of him can detect. Thus the dog exceeds the human
observers in delicacy and associates each with a separate act
four attitudes of his master, which to human observers seem all
alike. Mr. Davis says he thinks the dog is a mind-reader. I
think it quite possible that whatever signs the dog goes by are
given unconsciously and consist only of some very delicate
general differences in facial expression or the manner of saying
the words, ‘‘ Bring it,” or slight sounds made by Mr. Davis in
thinking to himself the words one or two or three or four. Mr.
Davis keeps his eyes shut and his hands behind a newspaper.
The dog looks directly at his face.

To such a height possible delicacy may attain, but possible
delicacy is quite another thing from actual untrained and un-
stimulated delicacy. The difference in reaction has to be
brought about by associating with pleasure the reaction to the
different sense-impression when it itself differs and associating
with pain tendencies to confuse the reactions. The animal does

ANIMAL INTELLIGENCE. 89

not naturally asa function of sense-powers discriminate at all
delicately. Thus the cat who climbed up the wire netting when
I said, ‘‘ I must feed those cats !”’ did not have a delicate associa-
tion of just that act with just those words. For after I had
dropped the clapping part of the signal and simply used those
words it would react just as vigorously to the words, ‘* To-mor-
row is Tuesday ” or ‘‘ My name is Thorndike.” The reaction
naturally was to a very vague stimulus. Taking cat 10 when just
beginning to learn to climb up at the signal, ‘* I must feed those
cats !”’ I started in to improve the delicacy, by opposing to this
formula the formula, ‘‘ I will not feed them,” after saying which,
I kept my word. That is, I gave sometimes the former signal
and fed the cat, sometimes the latter and did not. The object
was to see how long the cat would be in learning always to go
up when I gave the first, never to do so when I gave the second
signal. I said the words in both cases as I naturally would do,
so that there was a difference in emphasis and tone as well as
in the mere nature of the syllables. The two signals were given
in all sorts of combinations so that there was no regularity in
the recurrence of either which might aid the animal. The cat
at first did not always climb up at the first signal and often did
climb up at the wrong one. The change from this condition to
one of perfect discrimination is shown in the accompanying
curves, one showing the decrease in failures to respond to the
right signal, the other showing the decrease in responses to the
wrong signal. The first curve is formed by a line joining the
tops of perpendiculars erected at intervals of 1 mm. along the
abscissa. The height of a perpendicular represents the number
of times the cat failed to respond to the food-signal in 20 trials,
a height of 1 mm. being the representative of one failure.
Thus, the entire curve stands for 280 trials, there being no
failures after 60 trials, and only 1 after the goth.

In the other curve, also, each r. mm. along the abscissa
stands for 20 trials, and the perpendiculars whose tops the
curve unites represent the number of times the cat in each 20
did climb up at the signal which meant no food. It will be
seen that 380 experiences were necessary before the animal
learned that the second signal was different from the first. The

go E. L. THORNDIKE.

experiment shows beautifully the animal method of acquisition.
If at any stage the animal could have isolated the two ideas of
the two sense-impressions, and felt them together in comparison,
this long and tedious process would have been unnecessary.

i Ee

(1) (2.)

FIG. 20.

It might be stated here that the animals also acquired asso-
ciations of moderate delicacy in discriminating between the
different boxes. No cat tried to get out of A or B by licking
herself, for instance.

The question may naturally be raised that if naturally asso-
ciations are thus vague, the common phenomenon of a dog
obeying his master’s commands, and no one else’s, is inexplica-
ble. The difference between one man and another, one voice
and another, it may be said, is not much of a difference, yet is
here uniformly discriminated, although we cannot suppose any
such systematic training to reject the other slightly differing
commands. My cats did not so discriminate. If anyone else
sat in my chair and called out, ‘‘I must feed the cats,” they
reacted, and probably very many animals would, if untroubled
by emotions of curiosity or fear at the new individual, go
through their tricks as well at another’s voice as at that of their
master. The other cases exemplify the influence of attention.
Repeated attention to these sense-impressions has rendered
them clear-cut and detailed, and the new impression conse-
quently does not equal them in calling forth the reaction.

The main thing to carry away from this discyssion is the
assurance that the delicacy of the animal in associating acts
with impressions is nothing like the delicacy of the man who
feels that a certain tone is higher, or weight is heavier, than
another, but zs like the delicacy of the man who runs to a cer-
tain spot to hit one tennis ball and to a different spot to hit one
coming with a slightly different speed.

ANIMAL INTELLIGENCE gt

CoMPLEXITY OF ASSOCIATIONS.

An important question, especially if one wishes to rate an
animal in a scale of intelligence, is the question of how complex
an association it can form. A man can learn that to open a
door he has to put the key in its hole, turn it, turn the knob,
and pullthe door. Here, then, is a complex act connected with
the simple sense-impression. Or, conversely, aman knows that
when the ringing of a bell is followed by a whistle and that by
a red light he is to do a certain thing, while if any of the three
happen alone he is not to. How far, then, we ask, can animals
go along the line of increased complexity in the associations?

We must not mistake for a complex association a series of
associations, where one sense-impression leads to an act such as
to present a new sense-impression which leads to another act
which in its turn leads to a new sense-impression. Of the for-
mation of such serzes animals are capable to a very high degree.
Chicks from 10 to 25 days old learned to go directly through
a sort of big labyrinth requiring a series of 23 distinct and in
some cases fairly difficult associations, of which 11 involved
choices between two paths. By this power of acquiring a long
series animals find their way to distant feeding grounds and
back again. But all such cases are examples of the numdéer,
not of the complexity, of animal associations.

Some of my boxes were suchas did give a chance for a com-
plex association to be formed. Such were G (¢humb-latch), J
(double), K and L (triples) for the cats, and O (triple) for the
dogs. It would be possible for a cat, after stepping on the
platform in K, to notice that the platform was in a different po-
sition, and so feel then a different sense-impression from before,
and thus turn the thing into a serial association. The cat would
then be like a man who on seeing a door should feel only the
impulse to stick the key in the hole, but then, seeing the door
plus a key in the hole, should feel the impulse to turn the key
and so on through. My cats did not give any signs of this,

-so that with them it was either a complex association or an ir

regular happening of the proper impulses. Probably the same
was the case with dog 1. Cats 10, 11, 12 in L knew all the
movements separately before being experimented on with the

92 E. L. THORNDIKE.

combination. Cats 2, 3, 4, had had some experience of D,
which worked by a string something like the string part of K.
The string in K was, however, quite differently situated and re-
quired an altogether different movement to pull it. Since fur-
ther No. 2, who had had ten times as much experience in D as
3 or 4, succeeded no better with the string element of K than
they, it is probable that the experience did not help very much.
All else in all these compound associations was new. At the
same time the history of these animals’ dealings with these boxes
would not fairly represent that of animals without general ex-
perience of clawing at all sorts of loose or shaky things in the
inside of a box. ‘These cats had learned to claw at all sorts of
things. The time curves were taken as in the formation of the
other associations, and, in addition, the order in which the ani-
mal did the several things required was recorded in every trial.

In the case of all the curves, except the latter part of 3 in G,
one notices a very gradual slope and an excessive irregularity
in the curve throughout. Within the limits of the trials given
the animals are unable to form a perfect association and what
advancement they make is very slow. The case of 3 in Gis
not an exception to this, but a proof of it. For 3 succeeded in
making a perfect association, by accidentally hitting on a way
to turn the compound association into a simple one. He hap-
pened one time to paw down the thumb-piece at the same time
that his other fore-limb, with which he was holding on between
the door and the top of the box, was pressing against the door.
This giving him success he repeated it in later trials and in a
short time had it fixed as an element in a perfect association.
The marked change in his curve from an irregular and gradual
slope at such a height as displayed a very imperfect association
to a constant and very slight height shows precisely the change
from a compound to a simple association.

Compound associations are formed slowly and not at all well.
Further observation shows that they were really not formed at
all. For the animals did not, except 3 in K for a certain period,
do the several things in a constant order, nor did they do them
only once apiece. On the contrary, an animal would pull the
string several times after the bolt had gone up with its custom-

}
J

ANIMAL INTELLIGENCE. 93

ary click, and would do sometimes one thing first, sometimes
another. It may also be noted here, in advance of its proper
place, that these compound associations are far below the simple
in point of permanence. The conduct of the animals is clearly
not that of minds having associated with a certain box’s interior
the idea of a succession of three movements. The animal does
not feel, ‘*I did this and that and that and got out,” or, more
simply still, ‘‘this and that and that means getting out.” If it
did we should soon see it doing what was necessary without
repetition and in a fairly constant time.

I imagine, however, that an animal could learn to associ-
ate with one sense-impression a compound act so as to per-
form its elements in a regular order. By arranging the box
so that the second and third elements of the act could be
performed only after the first had been, and the third only
after the first and second, 1 am inclined to think you could
get a very vigorous cat to learn the elements in order and
form the association perfectly. The case is comparable to that
of delicacy. The cat does not tend to know what he is doing
or to depart from the hit-or-miss method of learning, but by
associating the other combinations of elements with failure to
get pleasure, as in delicacy experiments we associated the re-
actions to all but the one signal, you could probably stamp out
all but the 1, 2, 3-order.

The fact that you have to thus maneuvre to get the animals
to have ‘the three impulses in a regular order shows that even
when they are so there is no idea of the three as in an order, no
thinking about them. Representations do not get beyond their
first intention. They are not carried up into a free life which
works them over anew. A complex ac¢ does not imply a com-
plex thought, or, more exactly, a performance of a series does
not imply the thought of a series. Consequently, since the
complexity of the act depends on the power which failure has
to stamp out all other combinations, it is far more limited than
in man.

NuMBER OF ASSOCIATIONS.

The patent and important fact is that there are so few in

animals compared to the human stock. Even after taking into

94 E. L. THORNDIKE.

account the various acts associated with various smells, and ex-
aggerating the possibility of getting an equipment of associations
in this field which man lacks, one must recognize how far below
man any animal is in respect to mere quantity of asssociations.
The associations with words alone of an average American
child of ten years far outnumber those of any dog. A good
billiard-player probably has more associations in connection
with this single pastime than a dog with his whole life’s business.
In the associations which are homologous with those of animals
man outdoes them and adds an infinity of associations of a dif-
ferent sort. The primates would seem, by virtue of their in-
cessant curiosity and addition to experience not for any practical
purpose but merely for love of mental life, to represent an ad-
vanced stage toward this tremendous quantity of associations.
In man not only this activity and curiosity, but also edu-
cation, increases the number of associations. Associations
are formed more quickly, and the absence of need for self-
support during a long infancy gives time. Associations
thus formed work back upon practical life, and by showing
better ways decrease the need of work, and so again increase
the chance to form associations. The result in the case of a
human mind to-day is the possession of a thesaurus of valuable
associations, if the time has been wisely spent. The free life
of ideas, imitation, all the methods of communication, and the
original accomplishments which we may include under the head
of invention, make the process of acquisition in many cases quite
a different one from the trial and error method of the animals,
and in general much shorten it.

Small as it is, however, the number of associations which
an animal may acquire is probably much larger than popularly
supposed.

My cats and dogs did not mix up their acts with the wrong
sense-impressions. The chicks that learned the series of twenty-
three associations did not find it a task beyond their powers to
retain them. Several three-day-old chicks, which I caused to
learn ten simple associations in the same day, kept the things
apart and on the next morning went through each act at the
proper stimulus. In the hands of animal trainers some animals

Sa Ye \e

ANIMAL INTELLIGENCE. 5

95

get a large number of associatious perfectly in hand. The
horse Mascot is claimed to know the meaning of fifteen hundred
signals! He certainly knows a great many, and such as are
naturally difficult of acquisition. It would be an enlightening
investigation if some one could find out just how many associa-
tions a cat or dog could form, if he were carefully ‘and con-
stantly given an opportunity. The result would probably show
that the number was limited only by the amount of motive avail-
able and the time taken to acquire each. For there is probably
nothing in their brain structure which limits the number of con-
nections that can be formed, or would cause such connections,
as they grew numerous, to become confused.

In their anxiety to credit animals with human powers, the
psychologists have disregarded or belittled, perhaps, the pos-
sibilities of the strictly animal sort of association. They would
think it more wonderful that a horse should respond differently
to a lot of different numbers on the black-board than that he
should infer a consequence from premises. But if it be made
a direct question of pleasure or pain to an animal, he can asso-
ciate any number of acts with different stimuli. Only he does
not form any association until he has to, until the direct benefit
is apparent, and, for his ordinary life, comparatively few are
needed.

On the whole our judgment from a comparison of man’s as-
sociations with the brutes’ must be that man’s are naturally far
more delicate, complex and numerous, and that in as far as the
animals attain delicacy, complexity, or a great number of as-
sociations, they do it by methods which man uses only in a very
limited part of the field.

PERMANENCE OF ASSOCIATIONS.

Once formed, the connections by which, when an animal
feels a certain sense-impression, he does a certain thing, persist
over considerable intervals of time. With the curves on pages
18 to 26 and 33 to 34 are given in many instances’ additional

1See 10 in A, 3 in A, 10in D; 10in C, gin C, 3in C; 6,2, 5,4 in E; 4in

F; 10 in H, 3 in H; 3, 4, 5, in I; 4 in G, 3 in G; 3 in K; 10 in L; dog 1 in N
and CC; dog 1 in G and O.

96 E. L. THORNDIKE.

curves showing the animal’s proficiency after an interval with-
out experience. To these data may be added the following:
The three chicks that had learned to escape through the long
labyrinth (involving twenty-three associations) succeeded in
repeating the performance after ten days’ interval. Similarly
the chicks used as imitators in V, W, X and Y, did not fail to
perform the proper act after an interval of twenty days. Cat 6,
who had had about a hundred experiences in C ( Button), had
the association as perfect after twenty days as when it left off.
Cat 2, who had had 36 experiences with C and had attained a
constant time of 8 sec., escaped fourteen days later in 3, 9 and
8 secs. respectively, in three trials. Cat 1, after an interval of
twenty days, failed in 10 minutes to escape from C. The signal
for climbing up the front of the cage was reacted to by No. 3
after an interval of twenty-four days. No. 10, who had learned
to discriminate between ‘I must feed those cats’ and ‘I will not
feed them,’ was tried after ezehty days. It was given 50 trials
with the second signal mingled indiscriminately with 25 trials
with the first. I give the full record of these, ‘ yes’ equalling a
trial in which she ‘ forgot’ and climbed up, ‘no’ equalling a trial
in which she wisely stayed down. Dashes represent interven-
ing trials with the first signal, to whzch she always reacted. It
will be observed that 50 trials put the cat in the same position
that 350 had done in her first experience, although in that first
experience she had had only about a hundred trials after the
association had been perfected. The association between the
first signal and climbing up was perfect after the eighty days.

Trials 1-7. Trials 8-17. Trials 18-27. Trials 28-35. Trials 36-42, Trials 43-50.

yes no

eS yes yes _—_—_- no es
yes yes no er no ey
yes no no aa an
no yes —= no no =

ae yes yes no no
yes no yes no no no
yes yes yes — yes
no no yes no — no
yo) == yes yes no no

rar = no no no no

= yes no no no

ee

eS a ae

eS Pe am

;

ANIMAL INTELLIGENCE. 97

All these data show that traces of the connections once
formed are very slow in being lost. If we allow that part of
the time in the first trial in all these cases is due to the time
taken to realize the situation (time not needed in the trials when
the association is forming and the animal is constantly being
dropped into boxes) we may say that the association is as firm
as ever for a considerable time after practice at it is stopped.
How long a time would be required to annul the influence of
any given quantity of experience, say of an association which
had been gone through with ten times, I cannot say. It could,
if profitable, easily be determined in any case. The only case
of total loss of the association (No. 1 in C) is so exceptional
that I fancy something other than lapse of time was its cause.
The main interest of these data, considered as quantitative esti-
mates, is not psychological, but biological. They show what a
tremendous advantage the well-developed association-process is
to an animal. The ways to different feeding grounds, the
actions of enemies, the appearance of noxious foods, are all
connected permanently with the proper reaction by.a few ex-
periences which need be reinforced only very rarely. Of course,
associations without any permanence would be useless, but
the usefulness increases immensely with such a degree of per-
manence as these results witness. An interesting experiment
from the biological point of view would be to see how infre-
quently an experience could occur and yet lead eventually to a
perfect association. An experiment approximating this is re-
corded in the time-curves for Box H in Fig. 4, on page 20.
Three trials at a time were given, the trials being two or three
days apart. As may be seen from the curves, the association
was readily formed.

The chief psychological interest of these data is that they
show that permanence of associations 7s not memory. The fact
that a cat, when after aninterval she is put into box G, pro-
ceeds to immediately press the thumb-piece and push the door,
does not at all mean that the cat feels the box to be the same
from which she weeks ago freed herself by pushing down that
thumb-piece, or thinks about ever having felt or done anything
in that box. She does not refer the present situation to a situation

98 E. L. THORNDIKE.

of the past and realize that itis the same, but simply feels on being
confronted with that situation the same impulse which she felt be-
fore. She does the thing now for just the same reason that she
did it before, namely, because pleasure has connected that act
above all others with that sense-impression, so that it is the one
she feels like doing. Her condition is that of the swimmer who
starts his summer season after a winter’s deprivation. When he
jumps off the pier and hits the water he swims, not because
he remembers that this is the way he dealt with water last sum-
mer and so applies his remembrance to present use, but just be-
cause experience has taught him to feel like swimming when he
hits the water. All talk about recognition and memory in ani-
mals, if it asserts the presence of anything more than this, is a
gross mistake. For real memory is an absolute thing, including
everything but forgetfulness. If the cat had real memory it
would, when after an interval dropped into a box, remember
that from this box it escaped by doing this or that and conse-
quently, either immediately or after a time of recollection, go do
it, or else it would not remember and would fail utterly to do
it. On the contrary, we have all grades of partzal < forgettul-
ness,’ just like the grades of swimming one might find if he
dropped a dozen college professors into the mill-ponds of their
boyhood, just like the grades of forgetfulness of the associations
once acquired on the ball-field which are manifested when on the
Fourth of July the ‘solid men’ of a town get out to amuse
their fellow citizens. The animal makes attacks on a spot
around the vital one, or claws at the thing—but not so precisely
as before, or goes at ita while and then resorts to instinctive
methods of getting out. Its actions are exactly what would be
expected of an animal in whom the sense-impression aroused
the impulse imperfectly, or weakly, or intermittently, but are
not at all like the actions of one who felt, ‘‘I used to get out of
this box by pulling that loop down.” In fact, the record of No.
10 given on page 96 seems to be final on this point. If at any
time in the course of the 50 trials it had remembered that ‘1 will
not feed them’ meant ‘ no fish,’ it would thenceforth have failed
to react. It would have stopped short in the ‘yes’ reactions,
instead of gradually decreasing their percentage. ‘Memory’

ee

ANIMAL INTELLIGENCE. 99

in animals, if one still chooses to use the word, is permanence of
associations, not the presence of an idea of an experience at-
tributed to the past.

To this proposition two corollaries may be added. First,
these phenomena of incomplete forgetfulness extend the evi-
dence that animals do not have a stock of independent ideas,
the return of which plus past associates equals memory. Second,
there is, properly speaking, no continuity in their mental streams.
The present thought does not clutch the past to its bosom or
hold the future in its womb. The animal’s self is not a being
‘looking before and after,’ but a direct practical association of
feelings and impulses. So far as experiences come continu-
ously they may be said to form a continuous mental life, but
there is no continuity imposed from within. The feelings of its
own body are always present and impresssions from outside
may come as they come to us. When the habit of attending
to the elements of its associations and raising them up into the
life of free ideas is acquired, these permanent bodily associa-
tions may become the basis of a feeling of self-hood and the
trains of ideas may be felt as a continuous life.

INHIBITION OF INSTINCTS BY HABIT.

One very important result of association remains to be con-
sidered, its inhibition of instincts and previous associations.
An animal who has become habituated to getting out of a box
by pulling a loop and opening the door will do so even though
the hole in the top of the box be uncovered, whereas, if, in early
trials, you had left any such hole, he would have taken the
instinctive way and crawled through it. Instances of this sort
of thing are well-nigh ubiquitous. It is a tremendous factor in
animal life, and the strongest instincts may thus be annulled.
The phenomenon has been already recognized in the literature
of the subject, a convenient account being found in James’
Psychology, Vol. I., pages 394-397- In addition to such ac-
counts, one may note that the influence of association is exerted
in two ways. The instinct may wane by not being used, be-
cause the animal forms the habit of meeting the situation in
a different way, or it may be actually inhibited. An instance

100 E. L. THORNDIKE.

of the former sort is found in the history of a cat which learns to
pull a loop and so escape from a box whose top is covered by
a board nailed over it. If, after enough trials, you remove a
piece of the board covering the box, the cat, when put in, will
still pull the loop instead of crawling out through the open-
ing thus made. But, at any time, if she happens to notice the
hole, she may make use of it. An instance of the second sort
is that of a chick which has been put ona box with a wire screen
at its edge, preventing her from jumping directly down, as she
would instinctively do, and forcing her to jump to another box
on one side of it and thence down. In the experiments which
I made, the chick was prevented by a second screen from jump-
ing directly from the second box also. That is, if in the accom-
panying figure, A is a box 34 inches high, B a box 25 inches

high, C a box 16 inches high, and D the pen with the food and
other chicks, the subject had to go A—-B-C-D. The chick
tried at first to get through the screen, pecked at it and ran up
and down along it, looking at the chicks below and seeking for
a hole to get through. Finally it jumped to B and, after a
similar process, to C. After enough trials it forms the habit
and when put on A goes immediately to B, then to C and down.
Now if, after 75 or 80 trials, you take away the screens, giving
the chick a free chance to go to D from either A or B, and then
put it on A, the following phenomenon appears. The chick
goes up to the edge, looks over, walks up and down it for a
while, still looking down at the chicks below, and then goes
and jumps to B as habit has taught it to do. The same actions
take place on B. No matter how clearly the chick sees the

ANIMAL INTELLIGENCE. IO!

chance to jump to D, it does not do so. The impulse has been
truly inhibited. It is not the mere habit of going the other
way, but the impossibility of going ¢hat way. In one case I
observed a chick in whom the instinct was all but, yet not quite
inhibited. When tried without the screen, it went up to the
edge to look over zune times, and at last, after seven minutes, did
jump straight down.

ATTENTION.

I have presupposed throughout one function which it will be
well to now recognize explicitly—attention. As usual, atten-
tion emphasizes and facilitates the process which it accompa-
nies. Unless the sense-impression is focussed by attention, it
will not be associated with the act which comes later. Unless
two differing boxes are attended to, there will be no difference
in the reactions to them. The really effective part of animal
consciousness, then, as of human, is the part which is attended
to; attention is the ruler of animal as well as human mind.

But in giving attention its deserts we need not forget that it
is not here comparable to the whole of human attention. Our
attention to the other player and the ball in a game of tennis 7s
like the animal’s attention, but our attention to a passage in
Hegel, or the memory which flits through our mind, or the
song we hear, or the player we idly watch, is mot. There
ought, I think, to be a separate name for attention when work-
ing for immediate practical associations. It is a different spe-
cies from that which holds objects so that we may define them,
think about them, remember them, etc., and the difference is, as
our previous sentence shows, not that between voluntary and
involuntary attention. The cat watching me for signs of my
walking to the cage with fish is not in the condition of the man
watching a ball game, but in that of the player watching the ball
speeding toward him. There is a notable difference in the
permanence of the impression. The man watching the game
can remember just how that fly was hit and how the fielder ran
for it, though he bestowed only a slight quantity of attention
on the matter, while the fielder may attend to the utmost to the
ball and yet not remember at all how it came or how he ran for

102 E. L. THORNDIKE.

it. The one sort of attention leads you to ¢himk about a thing,
the other to act with reference to it. We must be careful to
remember that when we say that the cat attended to what was
said, we do not mean that he thereby established an idea of it.
Animals are not proved to form separate ideas of sense-impres-
sions because they attend to them, for the kind of attention they
give is the kind which when given by men results in practical
associations, not in establishing ideas of objects. If attention
rendered clear the idea, we should not have the phenomena of
incomplete forgetfulness lately mentioned. The animal would
get a definite idea of just the exact thing done and would do it
or nothing. The human development of attention is in closest
connection with the acquisition of a stock of free ideas.

Soc1iAL CONSCIOUSNESS.

Besides attention there is another topic somewhat apart from
our general one, which yet deserves a few words. It concerns
animals’ social consciousness, their consciousnes of the feelings
of their fellows. Do animals, for example, when they see
others feeding, feel that the others are feeling pleasure? Do
they, when they fight, feel that the other feels pain? So level-
headed a thinker as Lloyd Morgan has said that they do, but
the conduct of my animals would seem to show that they did
not. For it has given us good reason to suppose that they do
not possess any stock of isolated ideas, much less any abstracted,
inferred or transferred ideas. These ideas of others’ feelings
imply a power to transfer states felt in oneself to another and
realize them as there. Now it seems that any ability to thus
transfer and realize an idea ought to carry with it an ability to
form a transferred association, to imitate. Ifthe animal realizes
the mental states of the other animal who before his eyes pulls
the string, goes out through the door and eats fish, he ought to
form the association, ‘impulse to pull string, pleasure of eating
fish.’ This we saw the animal could not do.

In fact, pleasure in another, pain in another, is not a sense-
presentation or a representation or feeling of an object of any
sort, but rather a ‘meaning,’ a feeling ‘ of the fact that.’ It can
exist only as something thought adou¢. It is never ‘a bit of

ANIMAL INTELLIGENCE. 103

direct experience,’ but an abstraction from our own life referred
to that of another.

I fancy that these feelings of others’ feelings may be connected
pretty closely with imitation, and for that reason may begin to
appear in the monkeys. There we have some fair evidence for
their presence in the tricks which monkeys play on each other.
Such feelings seem the natural explanation of the apparently
useless tail-pullings and such like which make up the attractions
of the monkey-cage. These may, however, be instinctive
forms of play-activity or merely examples of the general ten-
dency of the monkeys to fool with everything.

INTERACTION.

I hope it will not be thought impertinent if from the stand-
point of this research I add a word about a general psycholog-
ical problem, the problem of interaction. I have spoken all
along of the connection between the situation and a certain im-
pulse and act being stamped in when pleasure results from the
act and stamped out when it doesn’t. In this fact, which is un-
deniable, lies a problem which Lloyd Morgan has frequently em-
phasized. How are pleasurable results able to burn in and render
predominant the association which led to them? ‘This is per-
haps the greatest problem of both human and animal psychol-
ogy. Unfortunately in human psychology it has been all
tangled up with the problems of free will, mental activity,
voluntary attention, the creation of novel acts, and almost every-
thing else. In our experiments we get the data which give rise
to the problem, in a very elementary form.

It should first be noted about the fac¢ that the pleasure does
not burnin an impulse and act themselves, but an impulse
and act as connected with that particular situation. No cat
ever goes around clawing, clawing, clawing all the time,
because clawing in these boxes has resulted in pleasure.
Secondly, the connection thus stamped in is not contempora-
neous, but prior to the pleasure. So much for the fact;
now for the explanation. Ido not wish to rehearse or add to
the arguments with which so many pages have been already
filled by scientists and philosophers both. What we need most

104. E. L. THORNDIKE.

is not argument, but accurate accounts of the mental fact and
of the brain-process. But I do wish to say to the parallelist,
what has not to my knowledge been said, that if he presupposes,
to account for this fact, a ‘ physical analogue of the hedonic
consciousness,’ it is his bounden duty to first show how any
motion in any neuron or group of neurons in the nervous system
can possess this power of stamping in any current which causes
it. For no one would, from our present knowledge of the brain,
judge @ prvor7 that any motion in any part of it could be con-
ceived which should be thus regnant over all the others. And
next he must show the possibility of the current which repre-
sents the association being the excitant of this regnant motion
in a manner direct enough for the purpose.

I wish also to say that whoever thinks that, going along with
the current which parallels the association, there is an accompany-
ing minor current, which parallels the pleasure and which stamps
in the first current when present with it, flies directly in the
face of the facts. There zs no pleasure along with the associa-
tion. The pleasure does not come until after the association 7s
done and gone. Itis caused by no such minor current, but by
the excitation of peripheral sense-organs when freedom from
confinement is realized or food is secured. Of course, the no-
tion of such a secondary sub-current is mythology, any way.

To the interactionist I would say: ‘* Do not any more repeat
in tiresome fashion that consciousness does alter movement, but
get to work and show when, where, in what forms and to what
degrees it does so. Then, even if it turns out to have been a
physical parallel that did the work, you will, at least, have the
credit of attaining the best knowledge about the results and
their conditions, even though you misnamed the factor.”’

Besides this contribution to general psychology, I think we
may safely offer one to pedagogical science. At least some of
our results possess considerable pedagogical interest. The fun-
damental form of intellection, the association-process in animals,
is one, we decided, which requires the personal experience of
the animal in all its elements. The association cannot be taught
by putting the animal through it or giving it a chance to imitate.
Now every observant teacher realizes how often the cleverest

ANIMAL INTELLIGENCE 105

explanation and the best models for imitation fail. Yet often,
in such cases, a pupil, if somehow enticed to do the thing, even
without comprehension of what it means, even without any real
knowledge of what he is doing, will finally get hold of it. So,
also, in very many kinds of knowledge, the pupil who does any-
thing from imitation, or who does anything from being put
through it, fails to get a real and permanent mastery of the thing.
I am sure that with a certain type of mind the only way to teach
fractions in algebra, for example, is to get the pupil to do, do,
do. I am inclined to think that in many individuals certain
things cannot be learned save by actual performance. And I]
think it is often a fair question when explanation, imitation and
actual performance are all possible methods, which is the best.
We are here alongside the foundations of mental life, and this
hitherto unsuspected law of animal mind may prevail in human
mind to an extent hitherto unknown. The best way with chil-
dren may often be in the pompous words of an animal trainer,
‘to arrange everything in connection with the trick so that the
animal will be compelled by the laws of his own nature to per-
form it.’

This does not at all imply that I think, as a present school
of scientists seem to, that because a certain thing Aas deen in
phylogeny we ought to repeat it in ontogeny. Heaven knows
that Dame Nature herself in ontogeny abbreviates and skips and
distorts the order of the appearance of organs and functions, and
for the'best of reasons. We ought to make an effort, as she
does, to omit the useless and antiquated and get to the best and
most useful as soon as possible; we ought to change what #s to
what ought to be, as far as we can. And I would not advocate
this animal-like method of learning in place of the later ones
unless it does the same work better. I simply suggest that in
many cases where at present its use is never dreamed of, it may
be a good method. As the fundamental form of intellection
every student of ¢heoretical pedagogy ought to take it into
account.

There is one more contribution, this time to anthropology.
If the method of trial and error, with accidental success, be the
method of acquiring associations among the animals, the slow

106 EES TEL OLIN DD LEG:

progress of primitive man, the long time between stone age and
iron age, for instance, becomes suggestive. Primitive man
probably acquired knowledge by just this process, aided pos-
sibly by imitation. At any rate, progress was not by seeing
through things, but by accidentally hitting upon them. Very
possibly an investigation of the history of primitive man and of
the present life of savages in the light of the results of this re-
search might bring out old facts in a new and profitable way.

Comparative psychology has, in the light of this research,
two tasks of prime importance. One is to study the passage
of the child-mind from a life of immediately practical associa-
tions to the life of free ideas; the other is to find out how far
the anthropoid primates advance toward a similar passage, and
to ascertain accurately what faint beginnings or preparations
for such an advance the early mammalian stock may be sup-
posed to have had. In this latter connection I think it will be
of the utmost importance to bear in mind the possibility that ¢he
present anthropord primates may be mentally degenerate. Their
present aimless activity and incessant, but largely useless,
curiosity may be the degenerated vestiges of such a well-directed
activity and useful curiosity as led homo sapiens to important
practical discoveries, such as the use of tools, the art of making
fire, etc. It is even a remote possibility that their chattering is
a relic of something like language, not a degznning of such.
Comparative psychology should use the phenomena of the
monkey-mind of to-day to find out what the primitive mind from
which man’s sprung off was like. That is the important thing
to get at, and the question whether the present monkey-mind
has not gone back instead of ahead is an all-important question.
A natural and perhaps sufficient cause of degeneracy would be
arboreal habits. The animal that found a means of survival in
his muscles might well lose the means before furnished by his
brain.

To these disconnected remarks still another must be added,
addressed this time to the anecdote school. Some member of it
who has chanced to read this may feel like saying: ‘‘ This ex-
perimental work is all very well. Your cats and dogs repre-
sent, it is true, specimens from the top stratum of animal intelli-

ANIMAL INTELLIGENCE. 107

gence, and your negations, based on their conduct, may be
authoritative so far as concerns the average, typical mammalian
mind. But our anecdotes do not claim to be stories of the conduct
of the average or type, but of those exceptional individuals who
have begun to attain higher powers. And, if evena few dogs and
cats have these higher powers, our contention is, in a modified
form, upheld.” To all this I agree, provided the anecdote
school now realize just what sort of a position they hold. They
are clearly in pretty much the same position as spiritualists.
Their anecdotes are on pretty much the same level as the anec-
dotes of thought-transference, materializations of spirits, super-
normal knowledge, etc. Not in quite the same position, for far
greater care has been-given by the Psychical Research Society
to establishing the criteria of authenticity, to insuring good
observation, to explaining by normal psychology all that can be
so explained, in the case of the latter than the anecdote school
has done in the case of the former. The off-hand explanation of
certain anecdotes by invoking reason, or imitation, or recogni-
tion, or feelings of qualities, is on a par with the explanation of
trance-phenomena and such like by invoking the spirits of dead
people. I donot deny that we may get lawfully a super-normal
psychology, or that the super-normal acts it finds may turn out to
be explained by these functions which I have denied to the nor-
mal animal mind. But I must soberly declare that I think there
is less likelihood that such functions are the explanation of ani-
mal acts than that the existence of the spirits of dead people is the
true explanation of the automatisms of spiritualistic phenomena.
So much for the anecdote school, if it calls itself by its right name
and pretends only to give an abnormal animal psychology.
The sad fact has been that it has always pushed forward these
exceptions as the essential phenomena of animal mind. It has
built up a general psychology from abnormal data. It is like
an anatomy written from observations on dime-museum freaks.

CONCLUSION.
I do not think it is advisable here, at the close of this paper,
to give a summary of its results. The paper itself is really only
such a summary with the most important evidence, for the ex-

108 E. L. THORNDIKE.

‘tent of territory covered and the need of brevity have prevented
completeness in explanation or illustration. If the reader cares
here, at the end, to have the broadest possible statement of our
conclusions and will take the pains to supply the right meaning,
we might say that our work has described a method, crude but
promising, and has made the beginning of an exact estimate of
just what associations, simple and compound, an animal can
form, how quickly he forms them, and how long he retains
them. It has described the method of formation, and, on the
condition that our subjects were representative, has rejected rea-
son, comparison or inference, perception of similarity, and
imitation. It has denied the existence in animal consciousness
of any important stock of free ideas or impulses, and so has de-
nied that animal association is homologous with the association
of human psychology. It has homologized it with a certain lim-
ited form of human association. It has proposed, as necessary
steps in the evolution of human faculty, a vast increase in the
number of associations, signs of which appear in the primates,
and a freeing of the elements thereof into independent existence.
It has given us an increased insight into various mental pro-
cesses. It has convinced the writer, if not the reader, that the
old speculations about what an animal could do, what it thought,
and how what it thought grew into what human beings think,
were a long way from the truth, and zot on the road to tt.
Finally, I wish to say that, although the changes proposed in
the conception of mental development have been suggested
somewhat fragmentarily and in various connections, that has
not been done because I think them unimportant. On the con-
trary, I think them of the utmost importance. I believe that
our best service has been to show that animal intellection is
made up of a lot of specific connections, whose elements are re-
stricted to them, and which subserve practical ends dzrectly, and
to homologize it with the intellection involved in such human
associations as regulate the conduct of a man playing tennis.
The fundamental phenomenon which I find presented in animal
consciousness is one which can harden into inherited connections
and reflexes, on the one hand, and thus connect naturally with a
host of the phenomena of animal life; on the other hand, it

ANIMAL INTELLIGENCE I

“~

emphasizes the fact that our mental life has grown up as a
mediation between stimulus and reaction. The old view of
human consciousness is that it is built up out of elementary sen-
sations, that very minute bits of consciousness come first and
gradually get built up into the complex web. It looks for the
beginnings of consciousness to //¢é/e feelings. This our view
abolishes and declares that the progress is not from little and
simple to big and complicated, but from direct connections to
indirect connections in which a stock of isolated elements plays
a part, is from ‘ pure experience’ or undifferentiated feelings,
to discrimination, on the one hand, to generalizations, abstrac-
tions, on the other. If, as seems probable, the primates display
a vast increase of associations, and a stock of free-swimming
ideas, our view gives to the line of descent a meaning which it
never could have so long as the question was the vague one
of more or less ‘intelligence.’ It will, I hope, when supported
by an investigation of the mental life of the primates and of the
period in child life when these directly practical associations be-
come overgrown by a rapid luxuriance of free ideas, show us
the real history of the origin of human faculty. It turns out
apparently that a modest study of the facts of association in
animals has given us a working hypothesis for a comparative

psychology.

156.39
T499A

Thorndike
Animal intelligence

Date Due

“156.39 T499A cl
Thorndike / Animal

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°o

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