THE MENTAL LIFE OF THE MONKEYS; AN EXPERIMENTAL STUDY[22]
The literary form of this monograph is not at all satisfactory to its
author. Compelled by practical considerations to present the facts
in a limited space, he has found it necessary to omit explanation,
illustration and many rhetorical aids to clearness and emphasis. For the
same reason detailed accounts of the administration of the experiments
have not always been given. In many places theoretical matters are
discussed with a curtness that savors of dogmatism. In general when a
theoretical point has appeared justified by the evidence given, I have,
to economize space, withheld further evidence.
There is, however, to some extent a real fitness in the lack of
clearness, completeness and finish in the monograph. For the behavior of
the monkeys, by virtue of their inconstant attention, decided variability
of performance, and generally aimless, unforetellable conduct would be
falsely represented in any clean-cut, unambiguous, emphatic exposition.
The most striking testimony to the mental advance of the monkeys over
the dogs and cats is given by the difficulty of making clear emphatic
statements about them.
INTRODUCTION
The work to be described in this paper is a direct continuation of
the work done by the author in 1897-1898 and described in Monograph
Supplement No. 8 of the _Psychological Review_ under the heading, ‘Animal
Intelligence; an Experimental Study of the Associative Processes in
Animals.’[23] This monograph affords by far the best introduction to the
present discussion, and I shall therefore assume an acquaintance with it
on the part of my readers.
It will be remembered that evidence was there given that ordinary
mammals, barring the primates, did not infer or compare, did not imitate
in the sense of ‘learning to do an act from seeing it done,’ did not
learn various simple acts from being put through them, showed no signs
of having in connection with the bulk of their performances any mental
images. Their method of learning seemed to be the gradual selection of
certain acts in certain situations by reason of the satisfaction they
brought. Quantitative estimates of this gradualness were given for a
number of dogs and cats. Nothing has appeared since the ‘Experimental
Study’ to negate any of these conclusions in the author’s mind. The
work of Kline and Small[24] on rodents shows the same general aspect of
mammalian mentality.
Adult human beings who are not notably deficient in mental functions,
at least all such as psychologists have observed, possess a large stock
of images and memories. The sight of a chair, for example, may call up
in their minds a picture of the person who usually sits in it, or the
sound of his name. The sound of a bell may call up the idea of dinner.
The outside world also is to them in large part a multitude of definite
percepts. They feel the environment as trees, sticks, stones, chairs,
tables, letters, words, etc. I have called such definite presentations
‘free ideas’ to distinguish them from the vague presentations such as
atmospheric pressure, the feeling of malaise, of the position of one’s
body when falling, etc. It is such ‘free ideas’ which compose the
substance of thought and which lead us to perhaps the majority of the
different acts we perform, though we do, of course, react to the vaguer
sort as well. I saw definitely in writing the last sentence the words
‘majority of the different acts’ and thought ‘we perform’ and so wrote
it. I see a bill and so take check book and pen and write. I think of the
cold outside and so put on an overcoat. This mental function ‘having free
ideas,’ gives the possibility of learning to meet situations properly
by thinking about them, by being reminded of some property of the fact
before us or some element therein.
We can divide all learning into (1) _learning by trial and accidental
success_, by the strengthening of the connections between the
sense-impressions representing the situation and the acts—or impulses and
acts—representing our successful response to it and by the inhibition
of similar connections with unsuccessful responses; (2) _learning by
imitation_, where the mere performance by another of a certain act in a
certain situation leads us to do the same; and (3) _learning by ideas_,
where the situation calls up some idea (or ideas) which then arouses the
act or in some way modifies it.
The last method of learning has obviously been the means of practically
all the advances in civilization. The evidence quoted a paragraph or so
back from the Experimental Study shows the typical mammalian mind to be
one which rarely or never learns in this fashion. The present study of
the primates has been a comparative study with two main questions in
view: (1) How do the monkeys vary from the other mammals in the general
mental functions revealed by their methods of learning? (2) How do they,
on the other hand, vary from adult civilized human beings?
The experiments to be described seem, however, to be of value apart from
the possibility of settling crucial questions by means of the evidence
they give. To obtain exact accounts of what animals can learn by their
own unaided efforts, by the example of their fellows or by the tuition of
a trainer, and of how and how fast they learn in each case, seems highly
desirable. I shall present the results in the manner which fits their
consideration as arguments for or against some general hypotheses, but
the naturalist or psychologist lacking the genetic interest may find an
interest in them at their face value. I shall confine myself mainly to
questions concerning the method of learning of the primates, and will
discuss their sense-powers and unlearned reactions or instincts only in
so far as is necessary to its comprehension.
It has been impossible for the author to make helpful use of the
anecdotes and observations of naturalists and miscellaneous writers
concerning monkey intelligence. The objections to such data pointed out
in Chapter II, pp. 22-26, hold here. Moreover it is not practicable to
sift out the true from the false or to interpret these random instances
of animal behavior even if assuredly true. In the study of animal life
the part is only clear in the light of the whole, and it is wiser to
limit conclusions to such as are drawn from the constant and systematic
study of a number of animals during a fairly long time. After a large
enough body of such evidence has been accumulated we may be able to
interpret random observations.
The subjects of the experiments were three South American monkeys of the
genus _Cebus_. At the time of beginning the experiment No. 1 was about
half grown, No. 2 was about one fourth full size and No. 3 was about half
grown. No. 1 was under observation from November, 1899, to February,
1900; No. 2 and No. 3 from October, 1900, to February, 1901. No. 1 was
during the period of experimentation decidedly tame, showing no fear
whatever of my presence and little fear at being handled. He would handle
and climb over me with no hesitation. No. 2 was timid, did not allow
handling, but showed no fear of my presence and no phenomena that would
differentiate his behavior in the experiments discussed from that of No.
1, save much greater caution in all respects. No. 3 also showed no fear
at my presence. Any special individual traits that are of importance in
connection with any of the observations will be mentioned in their proper
places. No. 1 was kept until June, 1900, in my study in a cage 3 by 6 by
6 feet, and was left in the country till October, 1900. From October,
1900, all three were kept in a room 8 by 9 feet, in cages 6 feet tall by
3 long by 2.6 wide for Nos. 1 and 2, 3 feet by 3 feet by 20 inches for
No. 3. I studied their behavior in learning to get into boxes, the doors
to which could be opened by operating some mechanical contrivance, in
learning to obtain food by other simple acts, in learning to discriminate
between two signals, that is, to respond to each by a different act, and
in their general life.
Following the order of the ‘Animal Intelligence,’ I shall first recount
the observations of the way the monkeys learned, solely by their own
unaided efforts, to operate simple mechanical contrivances.
Besides a number of boxes such as were used with the dogs and cats (see
illustration on p. 30), I tried a variety of arrangements which could
be set up beside a cage, and which would, when some simple mechanism was
set in action, throw a bit of food into the cage. Figure 26 shows one of
these. See description of QQ (ff) on page 182.
[Illustration: FIG. 26. _A_, loop; _BB_, lever, pivoted at _M_. A bit of
food put in front of _C_ would be thrown down the chute _DDD_ when _A_
was released.]
APPARATUS
The different mechanisms which I used were the following:—
Box BB (O at back) was about 20 by 14 by 12 inches with a door in the
front which was held by a bolt to which was tied a string. This string
ran up the front of the box outside, over a pulley, across the top, and
over another pulley down into the box, where it ended in a loop of wire.
Box MM (bolt) was the same as BB but with no string and loop attachment
to the bolt.
Box CC (single bar) was a box of the same size as BB. The door was held
by a bar about 3 by 1 by 5 inches which swung on a nail at the left side.
Box CCC (double bar) was CC with a second similar bar on the right side
of the door.
Box NN (hook) was a box about the size of BB with its door held by an
ordinary hook on the left side which hooked through an eyelet screwed
into the door.
Box NNN was NN with the hook on the right instead of the left side.
Box NNNN was box NN with two hooks, one on each side.
Apparatus OO (string box) consisted of a square box tied to a string,
which formed a loop running over a pulley by the cage and a pulley
outside, so that pulling on the under string would bring the box to the
cage. In each experiment the box was first pulled back to a distance of 2
feet 3 inches from the cage, and a piece of banana put in it. The monkey
could, of course, secure the banana by pulling the box near enough.
Apparatus OOO was the same as OO, with the box tied to the upper string,
so that the upper string had to be pulled instead of the lower.
Box PP was about the size of BB. Its door was held by a large string
securely fastened at the right, passing across the front of the door and
ending in a loop which was put over a nail on the box at the left of the
door. By pulling the string off the nail the door could be opened.
Box RR (wood plug) was a box about the size of BB. The door was held by
a string at its top, which passed up over the front and top to the rear,
where it was fastened to a wooden plug which was inserted in a hole in
the top of the box. When the plug was pulled out of the hole, the door
would fall open.
Box SS (triple; wood-plug, hook and bar) was a box about the size of BB.
To open the door, a bar had to be pushed around, a hook unhooked and a
plug removed from a hole in the top of the box.
Box TT (nail plug) was 14 by 10 by 10 inches with a door 5.5 by 10 on
the right side of the front, the rest of the front being barred up. The
door was hinged at the bottom and fastened at its top to a wire which
was fastened to a nail 2.5 inches long, which, when inserted in a hole
0.25 inches in diameter at the back of the top of the box, held the door
closed. By drawing out this nail and pulling the door the animal could
open the door.
Box VV (plug at side) was a box about 18 by 10 by 10, the door held by
a plug passing through a hole in the side of the box. When the plug was
pulled out, the door could be pushed inward.
Box W (loop) was 17 by 10 by 10 inches with a door 5 by 9 at the left
side of its front hinged at the bottom. The door was prevented from
falling inward by a wire stretched behind it. It was prevented from
falling outward by a wire firmly fastened at the right side and held by a
loop over a nail at the left. By pulling the loop outward and to the left
it could be freed from the nail. The door could then be pulled open.
Box WW (bar inside) was 16 by 14 by 10 inches with a door 4 by 11 at the
left of its front hinged at the bottom. The door could be pushed in or
pulled out when a bar on its inside was lifted out of a latch. The bar
was accessible from the outside through an opening in the front of the
box. It had to be lifted to a height of 1.5 inches (an angle of about
30°).
Box XX (bar outside) was about 13 by 11 by 10 inches with a door 7 by
8 on the left side of the front. The door was held in place by a bar
swinging on a nail at the top, with its other end resting in a latch at
the left side of the box. By pushing this up through an angle of 45° the
door could be opened.
Box YY (push bar) was a box 16 by 8 by 12 inches with a door at the left
of its front. The door was held by a brass bar which swung down in front
of an L-shaped piece of steel fastened to the inside of the door. This
brass bar was hung on a pivot at its center and the other end attached
to a bar of wood; the other end of this bar projected through a hole at
the right side of the box. By pushing this bar in about an inch the door
could be opened.
Box LL (triple; nail plug, hook and bar) was a box 10 by 10 by 13 with a
door 3 by 8.5 at the left side. The door could be opened only after (1) a
nail plug had been removed from a hole in the back of the top of the box
as in TT, (2) a hook in the door had been unhooked, and (3) a bar on the
left side had been turned from a horizontal to a vertical position.
Box Alpha (catch at back) was 11 by 10 by 15 with the door (4 by 4) in
the left side of its front. The door was held by a bolt, which, when let
down, held in a catch on the inside of the door. A string fastened to the
bolt ran across to the back of the box and through a hole to the outside.
There it ended in a piece of wood 2.5 by 1 by .25 inches. When this piece
of wood was pulled, the bolt went up and the door fell open.
Box Beta was the same as NN except in size. It was 10 by 10 by 13 inches.
Box KK (triple; bolt, side plug, and knob) was a box 16 by 9 by 11 with
a door at the left side of the front. The door was held by a bolt on the
right side, a wooden plug stuck through a hole in the box on its left
side and a nail which held in a catch at its top. This nail was fastened
to a wooden knob (1 by 5 by .375) which lay in a depression at the top of
the box. Only when the bolt had been drawn and the plug and knob pulled,
could the door be opened.
Box Gamma (wind) was 10 by 10 by 13 inches with its door held by a wire
fastened at the top and wound three times about a screw eye in the top of
the box. By unwinding the wire the door could be opened.
Box Delta (push back) was 12 by 11 by 10 inches. Its door was held by
a wooden bar projecting from the right two inches in front of it. This
bar was so arranged that it could be pushed or pulled toward the right,
allowing the door to fall open. It could not be swung up or down.
Box Epsilon (lever or push down) was 12 by 9 by 5 inches. At the right
side of its front was a hole ½ inch broad by 1½ inches up and down.
Across this hole on the inside of the box was a strip of brass, the end
of one bar of a lever. If this strip was depressed ⅛ of an inch, the door
at the extreme left would be opened by a spring.
Box Zeta (side plug) was 12 by 11 by 10 inches. Its door was held by a
round bar of wood put through a hoop of steel at the left side of the
box. This bar was loose and could easily be pulled out, allowing the door
to be opened.
Box Theta was the same as KK except that the door could be opened as soon
as the bolt alone was pulled or pushed up.
Box Eta was like Alpha save that the object at the back of the box to be
pulled was a brass ring.
Apparatus QQ (chute) consisted of a lever mechanism so arranged that
by pushing in a bar of wood ¼ to ½ an inch, a piece of banana would be
thrown down a chute into the cage. The apparatus was placed outside the
cage in such a way that it could be easily reached by the monkey’s arm
through the wire netting.
QQ (a) was of the same general plan. By turning a handle through 270°
food could be obtained.
QQ (b) was like QQ (a) except that 2½ full revolutions of the handle in
one direction were necessary to cause the food to drop down.
QQ (c) was a chute apparatus so arranged as to work when a nail was
pulled out of a hole.
QQ (d) was arranged to work at a sharp pull upon a brass ring hanging to
it.
QQ (e) was arranged to work when a hook was unhooked.
QQ (f) was arranged to work when a loop at the end of a string was pulled
off from a nail.
QQ (ff) was QQ (f) with a stiff wire loop instead of a loop of string.
EXPERIMENTS ON THE ABILITIES OF THE MONKEYS TO LEARN WITHOUT TUITION
I will describe a few of the experiments with No. 1 as samples and then
present the rest in the form of a table. No. 1 was tried first in BB (O
at back) on January 17, 1900, being _put inside_. He opened the box by
pulling up the string just above the bolt. His times were .05, 1.38,
6.00, 1.00, .10, .05, .05. He was not easily handled at this time, so I
changed the experiment to the form adopted in future experiments. I put
the food inside and left the animal to open the door from the outside. He
pulled the string up within 10 seconds each time out of 10 trials.
I then tried him in MM (bolt). He failed in 15. I then (January 18th)
tried him in CC (single bar outside). He got in in 36.00 minutes; he did
not succeed a second time that night, but in the morning the box was
open. His times thenceforth were 20, 10, 16, 25 and on January 19th, 40,
5, 12, 8, 5, 5, 5 seconds.
I then tried him (January 21, 1900) in CCC (double bar). He did it at
first by pushing the old bar and then pulling at the door until he worked
the second bar gradually around. Later he at times pushed the second
bar. The times taken are shown in the time-curve. I then (January 25th)
tried him in NN (hook). See time-curves on page 185. I then (January
27th) tried him in NNN (hook on other side). He opened it in 6, 12 and 4
seconds in the first three trials. I then (20 minutes later) tried him
with NNNN (double hook). He opened the door in 12, 10, 6 and 6 seconds. I
then (January 27th) tried him with PP (string across). He failed in 10.
I then (February 21st) tried him with apparatus OO (string box). For his
progress as shown by the times taken see the time-curve. His progress is
also shown in the decrease of the useless pullings at the wrong string.
There were none in the 9th trial, 14th, 15th, 16th, 18th, 24th, and
following trials.
No. 1 was then (February 24th) tried with OOO (string box with box on
upper string). No. 1 succeeded in 2.20, then failed in 10.00. The rest of
the experiment will be described under imitation.
He was next tried (March 24th) with apparatus QQ (chute). He failed
in 10.00, though he played with the apparatus much of the time. Other
experiments were with box RR (wood-plug) (April 5th). He failed in 10.00.
After he had, in a manner to be described later, come to succeed with RR,
he was tried in box SS (triple; wood-plug, hook and bar) (April 18th);
see time-curve. No more experiments of this nature were tried until
October, 1900.
The rest of the experiments with No. 1 and all those with No. 2 and No.
3 may best be enumerated in the form of a table. (See Table 9 on page
187.) It will show briefly the range of performances which the unaided
efforts of the animals can cope with. It will also give the order in
which each animal experienced them. F means that the animal failed to
succeed. The figures are minutes and seconds, and represent the time
taken in the first trial or the total time taken without success where
there is an F. In cases where the animal failed in say 10 minutes, but in
a later trial succeeded, say in 2.40, the record will be 2.40 after 10 F.
There are separate columns for all three animals, headed No. 1, No. 2 and
No. 3. Im. stands for a practically immediate success.
The curves on pages 185 and 186 (Figs. 27 and 28) show the progress of
the formation of the associations in those cases where the animal was
given repeated trials, with, however, nothing to guide him but his own
unaided efforts. Each millimeter on the abscissa represents one trial
and each millimeter on the ordinate represents 10 seconds, the ordinates
representing the time taken by the animal to open the box. A break in
the curve, or an absence of the curve at the beginning of the base-line
represents cases where the animal failed in 10 minutes or took a very
long time to get out.
[Illustration: FIG. 27.]
[Illustration: FIG. 28.]
In discussing these facts we may first of all clear our way of one
popular explanation, that this learning was due to ‘reasoning.’ If
we use the word reasoning in its technical psychological meaning as
the function of reaching conclusions by the perception of relations,
comparison and inference, if we think of the mental content involved as
feelings of relation, perceptions of similarity, general and abstract
notions and judgments, we find no evidence of reasoning in the behavior
of the monkeys toward the mechanisms used. And this fact nullifies the
arguments for reasoning in their case as it did in the case of the
dogs and cats. The argument that successful dealings with mechanical
contrivances imply that the animals reasoned out the properties of the
mechanisms, is destroyed when we find mere selection from their general
instinctive activities sufficient to cause success with bars, hooks,
loops, etc. There is also in the case of the monkeys, as in that of the
other mammals, positive evidence of the absence of any general function
of reasoning. We shall find that at least very many simple acts were not
learned by the monkeys in spite of their having seen me perform them
again and again; that the same holds true of many simple acts which they
saw other monkeys do, or were put through by me. We shall find that after
having abundant opportunity to realize that one signal meant food at the
bottom of the cage and another none, a monkey would not act from the
obvious inference and consistently stay up or go down as the case might
be, but would make errors such as would be natural if he acted under
the growing influence of an association between sense-impression and
impulse or sense-impression and idea, but quite incomprehensible if he
had compared the two signals and made a definite inference. We shall find
that, after experience with several pairs of signals, the monkeys yet
failed, when a new pair was used, to do the obvious thing to a rational
mind; viz., to compare the two, think which meant food, and act on the
knowledge directly.
TABLE 9
-------------------------------+---------------------------------+
| No. 1. |
+-------------+---------+---------+
| |Min. Sec.| |
-------------------------------+-------------+---------+---------+
Box TT (nail plug) |Oct. 19, 1900| 0.40 | |
Box UU (old plug at side) |Oct. 19, 1900| | F 60.00|
Box VV (wire loop) |Oct. 20, 1900| |{ F 10.00|
| | |{ F 10.00|
| | |{ F 10.00|
Box WW (bar inside) |Oct. 20, 1900| | F 10.00|
| | | |
| | | |
| | | |
Box XX (bar outside) |Oct. 23, 1900| im. | after |
| | | [25] |
| | | F 10.00|
Box YY (push bar) |Oct. 30, 1900| 2.00[26]| |
Box Beta (single hook) | | | |
| | | |
| | | |
Box LL (triple; nail plug, |Nov. 4, 1900 |16.00[27]| |
hook and bar outside) | | | |
Box Alpha (catch at back) |Nov. 5, 1900 | .35 | |
Box KK (triple; bolt, side-plug|Nov. 7, 1900 | | F 10.00|
and knob) | | | F 10.00|
Box Theta (bolt at top) |Nov. 19, 1900| | F 10.00|
Box Eta (ring at back) |Dec. 17, 1900| im. | |
App. QQ (push chute) | | | |
Box Gamma (wind) |Jan. 3, 1901 | .20 | |
| | | |
Box Delta (push back) |Jan. 4, 1901 | | F 5.00|
| | | F 5.00|
App. QQ (a) (bar chute) |Jan. 6, 1901 | 8.00 | |
Box Zeta (new side plug) |Jan. 7, 1901 | 1.10 | after |
| | | F 5.00|
App. QQ (b) (2½ revolution | | | |
chute) |Jan. 9, 1901 | 3.00 | |
App. QQ (c) (nail-plug | | | |
chute) |Jan. 11, 1901| | F 5.00|
| | | F 5.00|
Box Epsilon (push down) |Jan. 12, 1901| | F 5.00|
| | | F 10.00|
App. QQ (d) (ring chute) |Jan. 16, 1901| | F 5.00|
| | | F 5.00|
App. QQ (e) (hook chute) | | | |
App. QQ (f) (string chute) |Jan. 17, 1901| | F 5.00|
App. QQ (ff) (string-wire |Jan. 17, 1901| .20 | |
chute) | | | |
-------------------------------+-------------+---------+---------+
-------------------------------+---------------------------------+
| No. 2. |
+-------------+---------+---------+
| |Min. Sec.| |
-------------------------------+-------------+---------+---------+
Box TT (nail plug) |Oct. 21, 1900| 14.10 | |
Box UU (old plug at side) | | | |
Box VV (wire loop) |Oct. 24, 1900| | F 10.00|
|Oct. 25, 1900| | F 10.00|
| | | |
Box WW (bar inside) |Oct. 21, 1900| 5.00 | after|
| | | F 30.00|
| | | |
| | | |
Box XX (bar outside) |Oct. 24, 1900| 3.40 | |
| | | |
| | | |
Box YY (push bar) | | | |
Box Beta (single hook) |Oct. 30, 1900| 9.00 | after|
| | | F 10.00|
| | |and 10.00|
Box LL (triple; nail plug, |Oct. 3, 1900 | 2.00 | |
hook and bar outside) | | | |
Box Alpha (catch at back) |Oct. 5, 1900 | 6.00 | |
Box KK (triple; bolt, side-plug|Oct. 7, 1900 | | F 60.00|
and knob) | | | |
Box Theta (bolt at top) | | | |
Box Eta (ring at back) | | | |
App. QQ (push chute) | | | |
Box Gamma (wind) | | | |
| | | |
Box Delta (push back) | | | |
| | | |
App. QQ (a) (bar chute) | | | |
Box Zeta (new side plug) | | | |
| | | |
App. QQ (b) (2½ revolution | | | |
chute) | | | |
App. QQ (c) (nail-plug | | | |
chute) | | | |
| | | |
Box Epsilon (push down) | | | |
| | | |
App. QQ (d) (ring chute) | | | |
| | | |
App. QQ (e) (hook chute) | | | |
App. QQ (f) (string chute) | | | |
App. QQ (ff) (string-wire | | | |
chute) | | | |
-------------------------------+-------------+---------+---------+
-------------------------------+----------------------------------
| No. 3.
+-------------+---------+----------
| |Min. Sec.|
-------------------------------+-------------+---------+----------
Box TT (nail plug) |Oct. 21, 1900| 36.00 |
Box UU (old plug at side) | | |
Box VV (wire loop) |Oct. 22, 1900| |{ F 10.00
| | |{ F 10.00
| | |{ F 10.00
Box WW (bar inside) |Oct. 22, 1900| |{ F 10.00
|Oct. 24, 1900| |{ F 5.00
| | |{ F 10.00
| | |{ F 15.00
Box XX (bar outside) |Oct. 23, 1900| .30 |
| | |
| | |
Box YY (push bar) | | |
Box Beta (single hook) |Oct. 24, 1900| im. |
| | |
| | |
Box LL (triple; nail plug, |Nov. 3, 1900 | 1.45 |
hook and bar outside) | | |
Box Alpha (catch at back) |Nov. 5, 1900 | |
Box KK (triple; bolt, side-plug|Nov. 7, 1900 | | F 10.00
and knob) | | |
Box Theta (bolt at top) |Jan. 8, 1901 | | F 10.00
Box Eta (ring at back) |Dec. 17, 1900| 4.20 |
App. QQ (push chute) |Dec. 17, 1900| | F 60.00
Box Gamma (wind) |Jan. 4, 1901 | | F 10.00
| | | F 10.00
Box Delta (push back) |Jan. 4, 1901 | 2.10 |after[28]
| | | F 10.00
App. QQ (a) (bar chute) |Jan. 7, 1901 | | F 10.00
Box Zeta (new side plug) |Jan. 8, 1901 | .50 |
| | |
App. QQ (b) (2½ revolution | | |
chute) |Jan. 8, 1901 | | F 10.00
App. QQ (c) (nail-plug | | |
chute) |Jan. 11, 1901| | F 5.00
| | | F 5.00
Box Epsilon (push down) |Jan. 12, 1901| | F 10.00
| | |
App. QQ (d) (ring chute) |Jan. 16, 1901| im. |
| | |
App. QQ (e) (hook chute) |Jan. 16, 1901| | F 5.00
App. QQ (f) (string chute) | | |
App. QQ (ff) (string-wire |Jan. 19, 1901| | F 5.00
chute) | | | F 5.00
-------------------------------+-------------+---------+----------
The methods one has to take to get them to do anything, their general
conduct in becoming tame and in the experiments throughout, confirm
these conclusions. The following particular phenomena are samples of the
many which are inconsistent with the presence of reasoning as a general
function. No. 1 had learned to open a door by pushing a bar around from
a horizontal to a vertical position. The same box was then fitted with
two bars. He turned the first bar round thirteen times before attempting
to push the other bar around. In box LL all three monkeys would in the
early trials do one or two of the acts over and over after they had once
done them. No. 1, who had learned to pull a loop of wire off from a nail,
failed thereafter to pull off a similar loop made of string. No. 1 and
No. 3 had learned to poke their left hands through the cage for me to
take and operate a chute with. It was extremely difficult to get either
of them to put his right hand through or even to let me take it and pull
it through.
A negative answer to the question “Do the monkeys reason?” thus
seems inevitable, but I do not attach to the question an importance
commensurate with the part it has played historically in animal
psychology. For I think it can be shown, and I hope in a later monograph
to show, that reasoning is probably but one secondary result of the
general function of having free ideas in great numbers, one product of a
type of brain which works in great detail, not in gross associations. The
denial of reasoning need not mean, and does not to my mind, any denial
of continuity between animal and human mentality or any denial that the
monkeys are mentally nearer relatives to man than are the other mammals.
So much for supererogatory explanation. Let us now turn to a more
definite and fruitful treatment of these records.
The difference between these records and those of the chicks, cats and
dogs given on pages 39-65 _passim_ is undeniable. Whereas the latter
were practically unanimous, save in the cases of the very easiest
performances, in showing a process of gradual learning by a gradual
elimination of unsuccessful movements, and a gradual reënforcement of
the successful one, these are unanimous, save in the very hardest, in
showing a process of sudden acquisition by a rapid, often apparently
instantaneous, abandonment of the unsuccessful movements and a selection
of the appropriate one which rivals in suddenness the selections made by
human beings in similar performances. It is natural to infer that the
monkeys who suddenly replace much general pulling and clawing by a single
definite pull at a hook or bar have an idea of the hook or bar and of the
movement they make. The rate of their progress is so different from that
of the cats and dogs that we cannot help imagining as the cause of it a
totally different mental function, namely, free ideas instead of vague
sense-impressions and impulses. But our interpretation of these results
should not be too hasty. We must first consider several other possible
explanations of the rapidity of learning by the monkeys before jumping to
the conclusion that the forces which bring about the sudden formation of
associations in human beings are present.
First of all it might be that the difference was due to the superiority
of the monkeys in clear detailed vision. It might be that in given
situations where associations were to be formed on the basis of smells,
the cats and dogs would show similar rapid learning. There might be,
that is, no general difference in type of mental functioning, but only
a special difference in the field in which the function worked. This
question can be answered by an investigation of the process of forming
associations in connection with smells by dogs and cats. Such an
investigation will, I hope, soon be carried on in the Columbia Laboratory
by Mr. Davis.[29]
Secondly, it might be that the superior mobility and more detailed
and definite movements of the monkeys’ hands might have caused the
difference. The slowness in the case of the dogs and cats might be at
least in part the result of difficulty in executing movements, not in
intending them. This difficulty in execution is a matter that cannot be
readily estimated, but the movements made by the cats and dogs would
not on their face value seem to be hard. They were mostly common to the
animals’ ordinary life. At the same time there were certain movements
(_e.g._ depressing the lever) which were much more quickly associated
with their respective situations by the cats than others were, and if
we could suppose that all the movements learned by the monkeys were
comparable to these few, it would detract from the necessity of seeking
some general mental difference as the explanation of the difference in
the results.
In the third place it may be said by some that no comparison of the
monkeys with dogs and cats is valid, since the former animals got out of
boxes while the latter got in. It may be supposed that the instinctive
response to confinement includes an agitation which precludes anything
save vague unregulated behavior. Professor Wesley Mills has made
such a suggestion in referring to the ‘Animal Intelligence’ in the
_Psychological Review_, May, 1899. In the July number of the same journal
I tried to show that there was no solid evidence of such a harmful
agitation. Nor can we be at all sure that agitation when present does not
rather quicken the wits of animals. It often seems to. However I should,
of course, allow that for purposes of comparison it would be better to
have the circumstances identical. And I should welcome any antagonist who
should, by making experiments with kittens after the fashion of these
with the monkeys, show that they did learn as suddenly as the latter.
Again we know that, whereas the times taken by a cat in a box to get
out are inversely proportional to the strength of the association,
inasmuch as they represent fairly the amount of its efforts, on the
other hand, the times taken by a monkey to get in represent the amounts
of his efforts _plus the amount of time in which he is not trying to
get in_. It may be said therefore that the time records of the monkeys
prove nothing,—that a record of four minutes may mean thirty seconds of
effort and three minutes thirty seconds of sleep,—that one minute may
really represent twice as much effort. As a matter of fact this objection
would occasionally hold against some single record. The earliest times
and the occasional long times amongst very short ones are likely to be
too long. The first fact makes the curves have too great a drop at the
start, making them seem cases of too sudden learning, but the second fact
makes the learning seem indefinite when it really is not. And in the long
run the times taken do represent fairly well the amount of effort. I
carefully recorded the amount of actual effort in a number of cases and
the story it tells concerning the mental processes involved is the same
as that told by the time-curves.
Still another explanation is this: The monkeys learn quickly, it is true,
but not quickly enough for us to suppose the presence of ideas, or the
formation of associations among them. For if there were such ideas, they
should in the complex acts do even better than they did. The explanation
then is a high degree of facility in the formation of associations of
just the same kind as we found in the chicks, dogs and cats.
Such an explanation we could hardly disapprove in any case. No one can
from objective evidence set up a standard of speed of learning below
which all shall be learning without ideas and above which all shall be
learning by ideas. We should not expect any hard and fast demarcation.
This whole matter of the rate of learning should be studied in the light
of other facts of behavior. My own judgment, if I had nothing but these
time-curves to rely on, would be that there was in them an appearance of
learning by ideas which, while possibly explicable by the finer vision
and freer movements of the monkey in connection with ordinary mammalian
mentality, made it worth while to look farther into their behavior. This
we may now do.
What leads the lay mind to attribute superior mental gifts to an animal
is not so much the rate of learning as the amount learned. The monkeys
obviously form more associations and associations in a greater variety
than do the other mammals. The improved rate assists, but another cause
of this greater number of associations is the general physical activity
of the monkeys, their constant movements of the hands, their instinctive
curiosity or tendency to fool with all sorts of objects, to enjoy having
sense-impressions, to form associations because of the resulting sound or
sight. These mental characteristics are of a high degree of importance
from the comparative point of view, but they cannot be used to prove that
the monkeys have free ideas, for a large number of associations may be
acquired after the purely animal fashion.
What is of more importance is the actual behavior of the animals in
connection with the boxes. First of all, as has been stated, all the
monkey’s movements are more definite, he seems not merely to pull, but
to pull at, not merely to poke, but to push at. He seems, even in his
general random play, to go here and there, pick up this, examine the
other, etc., more from having the idea strike him than from feeling like
doing it. He seems more like a man at the breakfast table than like a man
in a fight. Still this appearance may be quite specious, and I think it
is likely to lead us to read ideational life into his behavior if we are
not cautious. It may be simply general activity of the same sort as the
narrower activities of the cat or dog.
In the second place the monkeys often make special movements with a
directness which reminds one unavoidably of human actions guided by
ideas. For instance, No. 1 escaped from his cage one day and went
directly across the room to a table where lay a half of a banana which
was in a very inconspicuous place. It seemed as if he had observed the
banana and acted with the idea of its position fully in mind. Again, on
failing to pull a hook out, No. 1 immediately applied his teeth, though
he had before always pulled it out with his hand. So again with a plug.
It may be that there is a special inborn tendency to bite at objects
pulled unsuccessfully. If not, the act would seem to show the presence of
the idea ‘get thing out’ or ‘thing come out’ and associated with it the
impulse to use the teeth. We shall see later, however, that in certain
other circumstances where we should expect ideas to be present and result
in acts they do not.
The fact is that those features in the behavior of the monkeys in forming
associations between the sight of a box and the act needed to open it
which remind us of learning by ideas may also be possibly explained by
general activity and curiosity, the free use of the hand, and superior
quickness in forming associations of the animal sort. We must have
recourse to more crucial tests or at least seek evidence from a number of
different kinds of mental performances. The first of these will naturally
be their behavior toward these same mechanisms after a long time-interval.
THE PERMANENCE OF ASSOCIATIONS IN THE CASE OF MECHANISMS
My records are too few and in all but one case after too short an
interval to be decisive on the point of abrupt transition from failure
to success such as would characterize an animal in whose mind arose the
idea of a certain part of the mechanism as the thing to be attacked or of
a certain movement as the fit one. The animals are all under observation
in the Columbia Laboratory, however, and I trust that later satisfactory
tests may be made. No. 2 was not included in the tests because he was
either unwell or had become very shy of the boxes, entering them even
when the door was left open only after great delay. The time-curves for
the experiments performed will be found on page 186 among the others. The
figures beside each pair represent the number of days without practice.
The records show a decided superiority to those of the cats and dogs.
Although the number of trials in the original tests were in general fewer
in the case of the monkeys, the retention of the association is complete
in 6 cases out of 8 and is practically so in one case where the interval
was 8 months.
EXPERIMENTS ON THE DISCRIMINATION OF SIGNALS
My experiments on discrimination were of the following general type: I
got the animal into the habit of reacting to a certain signal (a sound,
movement, posture, visual presentation or what not) by some well-defined
act. In the cases to be described this act was to come down from his
customary positions about the top of the cage, to a place at the bottom.
I then would give him a bit of food. When this habit was wholly or
partly formed, I would begin to mix with that signal another signal
enough like it so that the animal would respond in the same manner. In
the cases where I gave this signal I would not feed him. I could then
determine whether the animal did discriminate or not, and his progress
toward perfect discrimination in case he did. If an animal responds
indiscriminately to both signals (that is, does not learn to disregard
the ‘no food’ signal) it is well to test him by using two somewhat
similar signals, after one of which you feed him at one place and after
the other of which you feed him at a different place.
If the animal profits by his training by acquiring ideas of the two
signals and associates with them ideas of ‘food’ and ‘no food,’ ‘go
down’ and ‘stay still,’ and uses these ideas to control his conduct, he
will, we have a right to expect, change suddenly from total failure to
differentiate the signals to total success. He will or won’t have the
ideas, and will behave accordingly. The same result could, of course, be
brought about by very rapid association of the new signal with the act
of keeping still, a very rapid inhibition of the act of going down in
response to it by virtue of the lack of any pleasure from doing so.
For convenience I shall call the signals after which food was given _yes_
signals and those after which food was not given _no_ signals. Signals
not described in the text are shown in Fig. 29, below. The progress of
the monkeys in discriminating is shown by Figs. 30 and 31, on pages 199
and 201. In Figs. 30 and 31 every millimeter along the horizontal or
base line represents 10 trials with the signal. The heights of the black
surface represent the percentages of _wrong_ responses, 10 mm. meaning
100 per cent of incorrect responses. Thus the first figure of the set,
Left hand, _a_, presents the following record: First 10 trials, all
wrong; of next 10, 7 wrong; of next 10, 6 wrong; of next 10, 7; of the
next, 9; of the next, 9; of the next, 4; of the next, none; of the next,
3; of the next, 2, and then 70 trials without an error.
[Illustration: FIG. 29.]
I will describe some of the experiments in detail and then discuss the
graphic presentation of them all.
EXPERIMENTS WITH NO. 1
Having developed in No. 1 the habit of coming down to the bottom of his
cage to get a bit of food when he saw me reach out and take such a bit
from my desk, I tested his ability to discriminate by beginning to use
now one hand, now the other, feeding him only when I used the left.
I also used different sets of words, namely, ‘I will give some food’
and ‘They shall not have any.’ It will be seen later that he probably
reacted only to the difference of the hands. The experiment is similar
to that described on pages 129 and 130 of Chapter II. At the beginning,
it should be remembered, No. 1 would come down whichever hand was used,
no matter what was said, except in the occasional cases where he was so
occupied with some other pursuit as to be evidently inattentive. He did
come to associate the act of going down with the one signal and the act
of staying still or continuing his ordinary movements with the other
signal. His progress in learning to do so is best seen in the curves of
his errors. To the ‘yes’ signal he responded correctly, except for the
occasional lapses which I just mentioned, from the start and throughout.
With the ‘no’ signal his errors were as shown in Fig. 30, _a_. The break
in the curve at 110 and 120 is probably not significant of an actual
retrograde as the trials concerned followed an eight days’ cessation of
the experiments.
I next tried No. 1 with an apparatus exposing sometimes a card with a
diamond-shaped piece of buff-colored paper on it and sometimes a card
with a similar black piece. The black piece was three fourths of an
inch farther behind the opening than the other. The light color was the
‘yes’ signal. The error curves for both signals are given, as No. 1 at
the beginning of the experiment did not go down always (Fig. 30, _b_ and
_b₁_).
I next tried No. 1 with the same apparatus but exposing cards with YES
and N in place of the buff and black diamonds. The record of the errors
is given in Fig. 30, _c_ and _c₁_. At the start he came down halfway very
often. This I arbitrarily scored as an error no matter which signal it
was in response to. It should not be supposed that these curves represent
two totally new associations. It seems likely that the monkey reacted to
the _position_ of the N card in the apparatus (the same as that of the
black diamond card) rather than to the shape of the letters. On putting
the black diamond in front he was much confused.
I next gave No. 1 the chance to form the habits of coming down when I
rapped my pencil against the table twice and of staying where he was when
I rapped with it once. He had 90 trials of each signal but failed to give
evidence of any different associations in the two cases.
Experiments of this sort were discontinued in the summer. In October I
tried No. 1 with the right and left hand experiment, he being in a new
room and cage, and I being seated in a different situation. He came down
at both signals and failed to make any ascertainable progress with the no
signal in 80 trials. (October 20-24.)
[Illustration: FIG. 30.]
I then tried him with the black and buff diamonds, the black being in
front (October 25-29). The reaction to the ‘yes’ signal was perfect from
the start. The progress with the ‘no’ signal is shown in Fig. 30, _d_.
I then tried him with an apparatus externally of different size, shape
and color from that so far used, showing as the ‘yes’ signal a brown
card and as the ‘no’ signal a white and gold card one half inch farther
back in the apparatus. The ‘yes’ signal was practically perfect from the
start. His progress with the ‘no’ signal is shown in Fig. 30, _e_.
I then tried a still different arrangement for exposure, to which,
however, he did not give uniform attention.
I then tried cards 1 and 101, 101 being in front and 1 in back. 1 was
the ‘yes’ signal. ‘Yes’ responses were perfect from the start. For ‘no’
responses see Fig. 30, _f_. I then put the ‘yes’ signal in front and the
‘no’ signal behind. ‘Yes’ responses perfect; for ‘no’ responses see Fig.
30, _f_, _a_.
From now on I arranged the exposures in such a way that there was no
difference between the ‘yes’ and ‘no’ signals in distance or surroundings.
The following list shows the dates, signals used, and the figures on
page 199 presenting the results. Where there is only one figure drawn,
it refers to progress with the ‘no’ signal, the ‘yes’ signal being
practically perfect from the start.
TABLE 10
==================+==============+=============+========
| ‘YES’ SIGNAL | ‘NO’ SIGNAL | FIGURE
------------------+--------------+-------------+--------
Nov. 13-15, 1900. | 2 | 102 | _g g₁_
Nov. 14-16, 1900. | 3 | 103 | _i i₁_
Nov. 16-19, 1900. | 4 | 104 | _h_
Nov. 19, 1900. | 5 | 105 | _j_
Nov. 20, 1900. | 6 | 106 | _k_
Nov. 21, 1900. | 7 | 107 | _l_
Nov. 23(?), 1900. | 8 | 108 | _m_
Nov. 27-29, 1900. | 9 | 109 | _n_
Nov. 30, 1900. | 10 | 110 | _o_
==================+==============+=============+========
Fig. 29 gives facsimiles of the different signals reduced to one sixth
their actual size. The drawing of 101 is not accurate, the outer ring
being too thick.
EXPERIMENTS WITH NO. 2
[Illustration: FIG. 31.]
I first secured the partial formation of the habit of coming down when
I took a bit of food in my hand. I then used the apparatus for exposing
cards, YES in front being the ‘yes’ signal and a circle at the back being
the ‘no’ signal. I gave No. 2 25 trials with the ‘yes’ signal and then
began a regular experiment similar to those described. After about 90
trials (November 9-12, 1900) there was no progress toward differentiation
of response, and it was evident from No. 2’s behavior that he was
reacting solely to the movements of my hand. So I abandoned the exposing
apparatus and used (November 11-13, 1900) as the ‘yes’ signal the act of
taking the food with my left hand from a pile on the front of the box and
for the ‘no’ signal the act of taking food with my right hand from a pile
4 inches behind that just mentioned. No. 2 did come to differentiate
these two signals. The record of his progress is given in Fig. 31 by _A_
and _A₁_.
I then made a second attempt with the exposing apparatus, using cards 2
and 102 (November 6, 14-21). No. 2 did react to my movements in pulling
the string but in over 100 trials made no progress in the direction of
a differential reaction to the ‘no’ signal. I then tried feeding him at
each signal, feeding him at the bottom of the cage as usual when I gave
the ‘yes’ signal and at the top when I gave the ‘no’ signal. After a
hundred trials with the ‘no’ signal there was no progress.
I then abandoned again the exposing apparatus and used as signals the
ordinary act of taking food with my left hand (yes) and the act of moving
my left arm from my right side round diagonally (swinging it on my elbow
as a center) and holding the hand, after taking the food, _palm up_ (no)
(November 26, 27, 1900). No. 2 did come to differentiate these signals.
His progress is given in the diagram in Fig. 31 entitled ‘Palm up’ (_B_).
I next used (November 27, 1900) as the ‘yes’ signal the same act as
before and for the ‘no’ signal the act of holding the food just in front
of the box about four inches below the edge. No. 2’s progress is shown in
Fig. 31 in the diagram entitled ‘low front’ (_C_ and _C₁_).
I next used (November 27-30) the same movement for both ‘yes’ and ‘no’
signals save that as the ‘yes’ signal I took the food from a brown
pasteboard box 3 by 3 by 0.5, and as the ‘no’ signal I took it from a
white crockery cover two inches in diameter and three eighths of an
inch high which was beside the box but three inches nearer me. No. 2’s
progress is shown in Fig. 31 in the diagram entitled ‘Box near’ (_D_).
I next used for the ‘yes’ signal the familiar act and for the ‘no’
signal the act of holding the food six inches above the box instead of
a quarter or a half an inch. The progress is shown in Fig. 31, _E_ and
_E₁_. I then tried taking the food from a saucer off the front of the
box for the ‘yes’ signal and from a small box at the back for the ‘no’
signal. ‘Yes’ was perfect from the start (10 trials given). ‘No’ was
right once, then wrong once, then right for the remaining eight.
EXPERIMENTS WITH NO. 3
No. 3 was kept in a cage not half so big as those of 1 and 2. Perhaps
because of the hindrance this fact offered to forming the habit of
reacting in some definite way to ‘yes’ signals, perhaps because of
the fact that I did not try hand movements as signals, there was no
successful discrimination by No. 3 of the yellow from the black diamond
or of a card with YES from a card with a circle on it. I tried climbing
up to a particular spot as the response to the ‘yes’ signal and staying
still as the response to the ‘no’ signal. I also tried instead of the
latter a different act, in which case the animal was fed after both
signals but in different places. In the latter case No. 3 made some
progress, but for practical reasons I postponed experiments with him.
Circumstances have made it necessary to postpone such experiments
indefinitely.
PERMANENCE OF THE ABILITY TO DISCRIMINATE
No. 1 and No. 2 were tried again after intervals of 33 to 48 days. The
results of these trials are shown in Fig. 32. Here every millimeter
along the base line represents _one_ trial with the ‘no’ signal (the
‘yes’ signals were practically perfect), and failure is represented by a
column 10 mm. high while success is represented by the absence of any
column. Thus the first record reads, “No. 1 with signal 104 after 40
days made 5 failures, then 2 successes, then 1 failure, then 1 success,
then 3 failures, then 1 success, then 1 failure, then 3 successes, then
1 failure, then 10 successes.” The third record (106; 40 days) reads,
“perfect success in ten trials.”
[Illustration: FIG. 32.]
DISCUSSION OF RESULTS
The results of all these discrimination experiments emphasize the
rapidity of formation of associations amongst the monkeys, which appeared
in their behavior toward the mechanisms. The suddenness of the change in
many cases is immediately suggestive of human performances. If all the
records were like c, f, h, i, j, k, l, m, B, E, and memory trials 103,
A, B, and C, one would have to credit the animals with either marvelous
rapidity in forming associations of the purely animal sort or concede
that from all the objective evidence at hand they were shown to learn as
human beings would. One would have to suppose that they had clear ideas
of the signals and clean-cut associations with those ideas. The other
records check such a conclusion.
In studying the figures we should remember that occasional mistakes, say
1 in 10 trials, are probably not significant of incomplete learning but
of inattention or of precipitate action before the shutter had fairly
exposed the card. We must not expect that a monkey who totally fails to
discriminate will _always_ respond wrongly to the ‘no’ signal, or that
a monkey who has come to discriminate perfectly will _always_ respond
rightly. A sudden drop from an average high level of error to an average
low level will signify sudden learning. Where the failure was on the
first trial of a series a few hours or a day removed from the last
series, I have generally represented the fact not by a column 1 mm. high
and 1 mm. broad, but by a single 10 mm. perpendicular. See i and A. Such
cases represent probably the failure of the animal to keep his learning
permanent rather than any general inability to discriminate.
K was to some extent a memory trial of d (after over half a year).
The experiment with 10 and 110 is noteworthy. Although, as can be seen
from the figures, the difference is obvious to one looking at the white
part of the figure, it is not so to one looking at the black part. No.
1 failed to improve appreciably in fifty trials, probably because his
previous experience had gotten him into the habit of attending to the
black lines.
Before arguing from the suddenness of the change from failure to success
we have to consider one possibility that I have not mentioned, and in
fact for the sake of clearness in presentation have rather concealed. It
is that the sudden change in the records, which report only whether the
animal did or did not go down, may represent a more gradual change in
the animal’s mind, a gradual weakening of the impulse to go down which
makes him feel less and less inclined to go down, though still doing so,
until this weakening reaches a sort of saturation point and stops the
action. There were in their behavior some phenomena which might witness
to such a process, but their interpretation is so dependent on the
subjective attitude and prepossessions of the observer that I prefer not
to draw any conclusions from them. On the other hand, records c, g, n, A
and D seem to show that gradual changes can be paralleled by changes in
the percentage of failures.
In the statement of conclusions I shall represent what would be the
effect on our theory of the matter in both cases, (1) taking the records
to be fairly perfect parallels of the process, and (2) taking them to be
the records of the summation points of a process not shown with surety in
any measurable objective facts. But I shall leave to future workers the
task of determining which case is the true one.
If we judge by the objective records themselves, we may still choose
between two views. (1) We may say that the monkeys did come to have
ideas of the acts of going down to the bottom of the cage and of staying
still, and that their learning represented the association of the
sense-impressions of the two signals, one with each of these ideas, or
possibly their association with two other ideas (of being fed and of
not being fed), and through them with the acts. Or (2) we may say that
the monkeys had no such ideas, but merely by the common animal sort of
association came to react in the profitable way to each signal.
If we take the first view, we must explain the failure of the animals
to change suddenly in some of the experiments, must explain why, for
instance, No. 1 in g should, after he had responded correctly to the
‘no’ signal for 27 trials out of 30, fail in one trial out of four for
a hundred or more trials. If the 27 successes were due to ideas, why
was there regression? If the animal came to respond by staying still on
seeing the K (card 104), because that sight was associated with the idea
of no food or the idea of staying still, why did he, in his memory trial,
act sometimes rightly, sometimes wrongly, for eleven trials after his
acting rightly twice. If he stayed still because the idea was aroused,
why did he not stay still as soon as he had a few trials to remind him of
the idea? It is easy, one may say, to see why, with a capacity to select
movements and associate them with sense-presentations very quickly, in
cases where habit provides only two movements for selection and where the
sense-presentation is very clear and simple, an animal should practically
at once be confirmed in the one act on an occasion when he does it with
the sense-impression in the focus of attention. It is easy, therefore, to
explain the sudden change in i, l, m, B, C and E. But our critic may add,
“It is very hard to suppose that an animal that learned by connecting
the sight of a card with the idea ‘stay still’ or the idea ‘no food,’
should be so long in making the connection as was the case in some of
these experiments, should take 10, 20 or 40 trials to change from a high
percentage of wrong to a high percentage of right reactions.”
If we take the second view, we have to face the fact that many of the
records are nothing like the single one we have for comparison, that of
the kitten shown in Fig. 30, and that the appeal to a capacity to form
animal associations very quickly seems like a far-fetched refuge from the
other view rather than a natural interpretation. If we take the records
to be summation points in a more gradual process, this difficulty is
relieved.
If further investigation upheld the first view, we should still not have
a demonstration that the monkeys habitually did learn by getting percepts
and images associated with sense-impressions, by having free ideas of the
acts they performed; we should only have proved that they could under
certain circumstances.
The circumstances in these experiments on discrimination were such as to
form a most favorable case. The act of going down had been performed in
all sorts of different connections and was likely to gain representation
in ideational life; the experience ‘bit of banana’ had again been
attended to as a part of very many different associations and so would be
likely to develop into a definite idea.
These results then do not settle the choice between three theories: (1
_a_) that they were due to a general capacity for having ideas, (1 _b_)
that they were due to ideas acquired by specially favoring circumstances,
(2) that they were due to the common form of association, the association
of an impulse to an act with a sense-impression rather roughly felt.
It would be of the utmost interest to duplicate these experiments with
dogs, cats and other mammals and compare the records. Moreover, since
we shall find (1 _a_) barred out by other experiments, it will be of
great interest to test the monkeys with some other type of act than
discrimination to see if, by giving the animal experience of the act and
result involved in many different connections, we can get a rate of speed
in the formation of a new association comparable to the rates in some of
these cases.
Of course here, as in our previous section, the differences in the
sense-powers of the monkeys from those of the kitten which I have tested
with a similar experiment may have caused the difference in behavior.
Focalized vision lends itself to delicate associations. Perhaps if one
used the sense of smell, or if the dogs and cats could, preserving their
same mental faculties in general, add the capacity for focalized vision,
they would do as well as the monkeys.
EXPERIMENTS ON THE INFLUENCE OF TUITION
The general aim of these experiments was to ascertain whether the
monkeys’ actions were at all determined by the presence of free ideas
and if so, to what extent. The question is, “Are the associations which
experience leads them to form, associations between (1) the idea of an
object and (2) the idea of an act or result and (3) the impulses and act
itself, or are they merely associations between the sense-impression
of the object and the impulse and act?” Can a monkey learn and does he
commonly learn to do things, not by the mere selection of the act from
amongst the acts done by him, but by getting some idea and then himself
providing the act because it is associated in his mind with that idea. If
a monkey feels an impulse to get into a box, sees his arm push a bar and
sees a door fall open immediately thereafter and goes into the box enough
times, he has every chance to form the association between the impulse to
get into the box and the idea ‘arm push bar,’ provided he can have such
an idea. If his general behavior is due to having ideas connected with
and so causing his acts, he has had chance enough to form the association
between the idea ‘push at’ and the act of pushing. If then a monkey forms
an association leading to an act by being put through the act, we may
expect that he has free ideas. And if he has free ideas in general in
connection with his actions, we may expect him to so form associations.
So also if a monkey shows a general capability to learn from seeing
another monkey or a human being do a thing. A few isolated cases of
imitation, however, might witness not to any general mental quality, but
only to certain instincts or habits differing from others only in that
the situation calling forth the act was the same act performed by another.
If the monkeys do not learn in these ways, we must, until other evidence
appears, suppose them to be in general destitute of a life of free ideas,
must regard their somewhat ambiguous behavior in learning by their
own unaided efforts as of the same type as that of the dogs and cats,
differing only in the respects mentioned on pages 190 and 191.
The general method of experimentation was to give monkeys who had failed
of their own efforts to operate some simple mechanism, a chance to see
me do it or see another monkey do it or to see and feel themselves do
it, and then note any change in their behavior. The chief question is
whether they succeed after such tuition when they have failed before
it, but the presence of ideas would also be indicated if they attacked,
though without success, the vital point in the mechanism when they had
not done so before. On the other hand, mere success would not prove that
the tuition had influenced them, for if they made a different movement
or attacked a different spot, we could not attribute their behavior to
getting ideas of the necessary act.
The results of the experiments as a whole are on their face value a
trifle ambiguous, but they surely show that the monkeys in question had
no considerable stock of ideas of the objects they dealt with or of the
movements they made and were not in general capable of acquiring, from
seeing me or one of their comrades attack a certain part of a mechanism
and make a certain movement, any ideas that were at all efficacious in
guiding their conduct. They do not acquire or use ideas in anything that
approaches the way human adults do. Whether the monkeys may not have some
few ideas corresponding to habitual classes of objects and acts is a
different question. Such may be present and function as the excitants of
acts.
It is likely that this question could have been definitely solved if it
had been possible for me to work with a larger number of animals. With
enough subjects one could use the method mentioned on page 105 of Chapter
II, of giving the animals tuition in acts which they would eventually do
themselves without it, and then leaving them to their efforts, noting any
differences in the way they learned from that in which other subjects who
had no tuition learned the same acts. The chief of such differences to
note would be differences in the time of their first trial, in the slope
of the time-curve and in the number of useless acts.
It would also be possible to extend experiments of the type of the
(on chair) experiment, where a subject is given first a certain time
(calculated by the experimenter to be somewhat less than would be needed
for the animal to hit upon the act) and if he does fail is then given
certain tuition and then a second trial. The influence of the tuition is
estimated by the presence or absence of cases where after tuition the act
is done within the time.
There is nothing necessarily insoluble in the problem. Given ten or
twenty monkeys that can be handled without any difficulty and it could be
settled in a month.
With this general preface we may turn to the more special questions
connected with the experiments on imitation of human acts and of the acts
of other monkeys and on the formation of associations apart from the
selection of impulses.
IMITATION OF HUMAN BEINGS
It has been a common opinion that monkeys learned to do things from
seeing them done by human beings. We find anecdotes to that effect in
fairly reputable authors.
Of course, such anecdotes might be true and still not prove that the
animals learned to do things because they saw them done. The animal
may have been taught in other ways to respond to the particular sights
in question by the particular acts. Or it may have been in each case a
coincidence.
If a monkey did actually form an association between a given situation
and act by seeing some one respond to that situation by that act, it
would be evidence of considerable importance concerning his general
mental status, for it would go to show that he could and often did form
associations between sense-impressions and ideas and between ideas and
acts. Seeing some one turn a key in a lock might thus give him the
idea of turning or moving the key, and this idea might arouse the act.
However, the mere fact that a monkey does something which you have just
done in his presence need not demonstrate or even render a bit more
probable such a general mental condition. For he perhaps would have acted
in just the same manner if you had offered him no model. If you put
two toothpicks on a dish, take one and put it in your mouth, a monkey
will do the same, not because he profits by your example, but because
he instinctively puts nearly all small objects in his mouth. Because of
their general activity, their instinctive impulses to grab, drop, bite,
rub, carry, move about, turn over, etc., any novel object within their
reach, their constant movement and assumption of all sorts of postures,
the monkeys perform many acts like our own and simulate imitation to a
far greater extent than other mammals.
Even if a monkey which has failed of itself to do a certain thing does it
after you have shown him the act, there need be no reason to suppose that
he is learning by imitation, forming an association between the sight of
the object and the act towards it through an idea gained from watching
you. You may have caused his act simply by attracting his attention to
the object. Perhaps if you had pointed at it or held it passively in your
hand, you would have brought to pass just the same action on his part.
There are several cases among my records where an act which an animal
failed totally to do of himself was done after I had so attracted his
attention to the object concerned.
Throughout all the time that I had my monkeys under observation I never
noticed in their general behavior any act which seemed due to genuine
imitation of me or the other persons about. I also gave them special
opportunities to show such by means of a number of experiments of the
following type: where an animal failed by himself to get into some box or
operate some mechanism, I would operate it in his presence a number of
times and then give him a chance to profit by the tuition. His failure
might be due to (1) the absence of instinctive impulses to make the
movement in that situation, (2) to lack of precision in the movement, (3)
to lack of force, or (4) to failure to notice and attack some special
part of the mechanism. An instance of (1) was the failure to push away
from them a bar which held a door; an instance of (2) was the failure to
pull a wire loop off a nail; an instance of (2) or (3) was the failure to
pull up a bolt; an instance of (4) was the failure to pull up an inside
bar. Failures due to (3) occur rarely in the case of such mechanisms as
were used in my investigations.
The general method of experiment was to make sure that the animal would
not of itself perform a certain act in a certain situation, then to make
sure that his failure could not be remedied by attracting his attention
to the object, then to perform the act for him a number of times, letting
him get each time the food which resulted, and finally to see whether,
having failed before the tuition, he would succeed after it. This sounds
very simple, but such experiments are hard to carry out satisfactorily.
If you try the animal enough times by himself to make quite sure that
he will not of himself hit upon the act, you are likely to form in him
the habit of meeting the particular situation in question with total
disregard. His efforts having failed so often may be so inhibited that
you could hardly expect any tuition to give them new life. The matter is
worse if you add further enough trials to assure you that your attracting
his attention to it has been unavailing. On the other hand, if you take
failure in five or ten minutes to mean inability, and from subsequent
success after imitation argue that imitation was efficient, you have to
face the numerous cases where animals which have failed in ten minutes
have succeeded in later unaided trials. With dogs and cats this does
not much matter, because they are steady performers, and their conduct
in one short trial tells you what to expect with some probability. But
the monkeys are much more variable and are so frequently distracted that
one feels much less confidence in his predictions. Moreover, you cannot
be at all sure of having attracted a monkey’s attention to an object
unless he does touch it. Suppose, for example, a monkey has failed to
even touch a bar though you have put a bit of food on it repeatedly. It
is quite possible that he may look at and take the food and not notice
the bar, and the fact that after such tuition he still fails to push or
pull the bar may mean simply that it has not caught his notice. I have,
therefore, preferred in most cases to give the animals only a brief
period of trial to test their ability by their own unaided efforts and
to omit the attempts to test the efficacy of attracting their attention
to the vital point in the mechanism. This makes the results appear less
elegant and definitive but really increases their value for purposes of
interpretation.
The thoughtful reader will not expect from my experiments any perfectly
rigorous demonstration of either the presence or the absence of imitation
of human acts as a means of learning. The general trend of the evidence,
it seems to me, is decidedly towards justifying the hypothesis that the
monkeys did not learn acts from seeing me do them.
I will first describe a sample experiment and then present a summary of
all those made.
On January 12th I put box Epsilon (push down) in No. 3’s cage, the door
of the box being open. I put a bit of food in the box. No. 3 reached
in and took it. This was repeated three times. I then put in a bit of
food and closed the door. No. 3 pulled and bit the box, turned it over,
fingered and bit at the hole where the lever was, but did not succeed
in getting the door open. After ten minutes I took the box out. Later I
took No. 3 out and let him sit on my knees (I sitting on the floor with
the box in front of us). I would then put my hand out toward the box and
when he was looking at it would insert my finger and depress the lever
with as evident a movement as I could. The door, of course, opened, and
No. 3 put his arm in and took the bit of food. I then put in another,
closed the door and depressed the lever as before. No. 3 watched my hand
pretty constantly, as all his experiences with me had made such watching
profitable. After ten such trials he was put back in the cage and the
box put in with a large piece of food in it and its door closed. No. 3
failed in five minutes and the box was taken out. He was shown fifteen
times more and then left to try himself. I tried him for a couple of
minutes under just the same circumstances as existed during the tuition,
_i.e._ he on the floor by me, the box in front. In this trial and in a
five-minute trial inside his cage he failed to open the door or to differ
in any essential respect from his behavior before tuition.
No. 1 saw me do 9 different acts and No. 3, 7, which they had failed
of themselves to do.[30] After from 1 to 40 chances to imitate me they
still failed to operate at all 11 of these mechanisms. In the case of
3 out of 5 that were worked the act was not the same as that taught.
No. 1, who saw me pull a nail out by taking the end of it and pulling
the nail away from the box, himself put his hand round the nail and
wriggled it out by pulling his hand back and forth. No. 3, who saw me
pull a bolt up with my fingers, succeeded by jerking and yanking the door
until he shook the bolt up. He saw me pull a hook out of an eye, but he
succeeded by pulling at a bar to which it was attached. In the case of
one of the two remaining acts (No. 3 with _nail chute_) the act was done
once and never again, though ample opportunity was given and tuition
continued. It could, therefore, hardly have been due to an idea instilled
by the tuition. The remaining case, No. 1, with loop, must, I think,
be attributed to accident, especially since No. 3 failed to profit by
precisely the same sort of tuition with precisely the same act.
Nor is there any evidence to show that although tuition failed to cause
successes where unaided effort failed, it yet caused attempts which would
not otherwise have occurred. Out of fifteen cases where such might have
appeared, there were only three where it is possible to claim that they
did. No one of these three is a sure case. With RR (wood plug) No. 1 did
seem to pull the plug more definitely after seeing me than before. With
QQ (c) (nail chute) and MM (bolt at top) he may possibly have done so.
In 5 cases I tried the influence of seeing me make the movement on
animals who had done the act of themselves, the aim being to see whether
there would be a marked shortening of the time, a change in their way of
operating the mechanism or an attempt at such change. I will give the
essential facts from the general table on pages 226-229.
(_a_) No. 1 had succeeded in pulling in the box by the upper string in
OOO (upper string box) in 2.20 and then failed in 3.00. I showed him 4
times. He failed in 10. I showed him 4 more times. He failed in 10. I
showed him 4 more times. He succeeded in .20. No change in manner of act
or objects attacked, though my manner was different from his.
(_b_) No. 1 had succeeded in QQ (a) (chute bar) in 8.00. I showed him 20
times. He failed in 10. I showed him 10 more times. He succeeded in 2.00.
I showed him 10 more times. He succeeded in 50 seconds. No change in his
manner of performance or in the object attacked, though my manner was
different from his.
(_c_) No. 1 had succeeded in 3.00, .25, .07, .25, .20, .06 and .09 with
QQ (b) (chute bar double) and then failed in 5.00. I showed him 10 times.
He then failed in 5 twice, succeeded in 3.00, and failed in 5 again. No
change in manner of performance or in the object attacked, though my
manner was different from his.
(_d_) No. 3 had the following record in box Delta:—
2.00 (pushed with head)
3.20 (pushed with head)
30 F
10 F
10 F
2.10 (pulled wire and door).
I showed him 20 times by pushing the bar to the right with my finger. He
succeeded in 8.00 and 8.00 by pulling the wire and the door. No change in
object attacked.
(_e_) No. 2 had failed twice in 5 with chute QQ (ff) (chute string wire)
and succeeded once in 2.00 by a strong pull on the wire itself, not the
loop. I showed him 5 times, pulling the loop off the nail. He then failed
in 5. There was no change in the objects attacked.
These records show no signs of any influence of the tuition that are
not more probably signs of something else. We cannot attribute the
rapid decrease in time taken in (_b_) to the tuition until we know the
time-curve for the same process without tuition.
The systematic experiments designed to detect the presence of ability to
learn from human beings are thus practically unanimous against it. So,
too, was the general behavior of the monkeys, though I do not consider
the failure of the animals to imitate common human acts as of much
importance save as a rebuke to the story-tellers and casual observers.
The following facts are samples: The door of No. 1’s cage was closed by
an iron hoop with a slit in it through which a staple passed, the door
being held by a stick of wood thrust through the staple. No. 1 saw me
open the door of his and other cages by taking out sticks hundreds of
times, but though he escaped from his cage a dozen times in other ways,
he never took the stick out and to my knowledge never tried to. I myself
and visitors smoked a good deal in the monkeys’ presence, but a cigar or
cigarette given to them was always treated like anything else.
IMITATION OF OTHER MONKEYS
It would theoretically seem far more likely that the monkeys should
learn from watching each other than from watching human beings, and
experimental determinations of such ability are more important than those
described in the last section as contributions both to genetic psychology
and to natural history. I regret that the work I have been able to do in
the study of this phase of the mental life of the monkeys has been very
limited and in many ways unsatisfactory.
We should expect to find the tendency to imitation more obvious in the
case of young and parents than elsewhere. I have had no chance to observe
such cases. We should expect closely associated animals, such as members
of a common troop or animals on friendly terms, to manifest it more
than others. Unfortunately, two of my monkeys, by the time I was ready
to make definite experiments, were on terms of war. The other had then
become so shy that I could not confidently infer inability to do a thing
from actual failure to do it. He showed no evidence of learning from his
mates. I have, therefore, little evidence of a quantitative objective
nature to present and shall have in the end to ask the reader to take
some opinions without verifiable proofs.
My reliable experiments, five in number, were of the following nature. A
monkey who had failed of himself (and often also after a chance to learn
from me or from being put through the act) would be put where he could
see another do the act and get a reward (food) for it. He would then be
given a chance to do it himself, and note would be taken of his success
or failure, and of whether his act was the same as that of his model in
case he succeeded, and of whether he tried that act more than before the
tuition in case he tried it and failed. The results are given in Table 11.
In the fourth experiment No. 1 showed further that the tuition did not
cause his successes in that after some successes further tuition did not
improve him.
There is clearly no evidence here of any imitation of No. 1 by No. 3.
There was also apparently nothing like purposive watching on the part
of No. 3. He seemed often to see No. 1 open the box or work the chute
mechanism, but without special interest.
This lack of any special curiosity about the doings of their own species
characterized the general behavior of all three of my monkeys and in
itself lessens the probability that they learn much from one another. Nor
did there appear, in the course of the three months and more the animals
were together, any signs of imitation. There were indeed certain notable
instances of the lack of it in circumstances which one would suppose
would be favorable cases for it.
For instance: No. 2 was very timid. No. 1 was perfectly tame from the
first day No. 2 was with me, and No. 3 became tame shortly after. No.
2 saw Nos. 1 and 3 come to me, be played with, fed and put through
experiments, yet he never did the same nor did he abate a jot or tittle
from his timidity save in so far as I sedulously rewarded any chance
advances of his. Conversely No. 1 and No. 3 seemed uninfluenced by the
fear and shyness of No. 2. No. 2’s cage was between No. 1’s and No. 3’s,
and they were for three weeks incessantly making hostile demonstrations
toward each other, jumping, chattering, scowling, etc. No. 2 never did
anything of the sort. Again, seeing No. 3 eat meat did not lead No. 1 to
take it; nor did seeing No. 1 retreat in fright from a bit of absorbent
cotton lead No. 3 to avoid it.
TABLE 11
Table headings:
Column A: SUBJECT, DATE, ACT
Column B: TIME TRIED ALONE, WITH RESULT
Column C: NO. OF TIMES IMITATEE DID
Column D: RESULT AFTER CHANCE FOR IMITATION
Column E: SIMILARITY OR DISSIMILARITY OF ACT
Column F: SIMILAR ACT ATTEMPTED, THOUGH UNSUCCESSFULLY IN CASES WHERE
IT HAD NOT BEEN BEFORE TRAINING
Column G: GENERAL JUDGMENT AS TO INFLUENCE OF TRAINING
======================+========+====+======+=============+=====+=======
A | B | C | D | E | F | G
----------------------+--------+----+------+-------------+-----+-------
No. 3. Dec. 17, 1900. | 50 F | 43 | 55 F | | No. | None.
VV (wire loop) | | | | | |
No. 3. Jan. 15, 1901. | 91 F | 75 | 35 F | | No. | None.
QQ (c) (nail chute) | 1.30 | | | | |
No. 3. Jan. 21, 1901. | 63 F | 43 | 5 F | Dissimilar. | No. | None.
Gamma (wind) | | | 9.00 | | |
| | | 6.00 | | |
No. 3. Jan. 21, 1901. | 20 F | 30 | 1.30 | Dissimilar. | No. | None.
QQ (ff) (string | 2.00 | | .40 | | |
chute with wire) | | | .35 | | |
| | | 5 F | | |
No. 3. Jan. 23, 1901. | 1.15 F | 40 | 10 F | | No. | None.
QQ (chute) | | | | | |
======================+========+====+======+=============+=====+=======
Nothing in my experience with these animals, then, favors the hypothesis
that they have any general ability to learn to do things from seeing
others do them. The question is still an open one, however, and a much
more extensive study of it should be made, especially of the possible
influence of imitation in the case of acts already familiar either as
wholes or in their elements.
LEARNING APART FROM MOTOR IMPULSES
The reader of my monograph, ‘Animal Intelligence,’ will recall that the
experiments there reported seemed to show that the chicks, cats and
dogs had only slight and sporadic, if any, ability to form associations
except such as contained some actual motor impulse. They failed to form
such associations between the sense-impressions and ideas of movements
as would lead them to make the movements without having themselves
previously in those situations given the motor impulses to the movements.
They could not, for instance, learn to do a thing from having been put
through it by me.
The monkeys Nos. 1 and 3 were tested in a similar way with a number of
different acts. The general conclusion from the experiments, the details
of which will be given presently, is that the monkeys are not proved to
have the power of forming associations of ideas to any greater extent
than the other mammals, that they do not demonstrably learn to do things
from seeing or feeling themselves make the movement. An adult human
being whose hand was taken and made to push in a bar or pull back a bolt
would thereby learn to do it for himself. Cats and dogs would not, and
the monkeys are not proved to do so. On the other hand, it is impossible
for me to say, as of the dogs and cats, that the monkeys are proved not
to do so. In a few cases the animals did perform acts after having been
put through them which they had failed to perform when left to their own
trial and success method. In the majority of cases they did not. And
in some of these latter cases failure seemed so improbable in case the
animal really had the power of getting an idea of the act and proceeding
from idea to execution, that one is inevitably led to some explanation
for the few successes other than the presence of ‘ideas.’
The general manner of making these experiments was like that in the case
of the cats and dogs, save that the monkey’s paw was used to open the
box from the outside instead of from the inside, and that the monkeys
were also put through the acts necessary to operate some of the chute
mechanisms. Tests parallel to that of comparing the behavior of kittens
who had themselves gone into boxes with those who were dropped in by me
were made in the following manner. I would carry a monkey from his cage
and put him in some conspicuous place (_e.g._ on the top of a chair)
and then give him a bit of food. This I would repeat a number of times.
Then I would turn him loose in the room to see whether he had acquired
an idea of being on the chair which would lead him to himself go to the
chair. I would, in order to tell whether his act, in case he did so, was
the result of random activities or was really due to his tuition, leave
him alone for 5 or 10 minutes before the tuition. If he got on the chair
afterwards when he had not before, or got on it much sooner, it would
tend to show that the idea of getting food on that chair was present and
effective. We may call these last the ‘on chair’ type of experiments.
A sample experiment with a box is the following:—
On January 4, 1901, box Delta (push back) was put in No. 1’s cage. He
failed in 5, though he was active in trying to get in for about 4 minutes
of the time and pulled and pushed the bar a great deal, though up and
down and out instead of back. In his aimless pushings and pullings he
nearly succeeded. He failed in 5 in a second trial also. I then opened
the door of the cage, sat down beside it, held out my hand, and when he
came to me took his right paw and with it (he being held in front of the
box) pushed the bar back (and pulled the door open in those cases when it
did not fall open of itself). He reached in and took the food and went
back to the top of his cage and ate it. (No. 1 generally did this, while
No. 3 generally stayed by me.) I then tried him alone; result 10 F; no
activity at all. On January 5th I put the box in; result 10 F. He was
fairly active. He pulled at the bar but mostly from a position on the top
of the box and with his left hand; no attempts like the one I had tried
to teach him. Being left alone he failed in 5. Being tried again with
the door of the cage open and me sitting as I had done while putting him
through the act, he succeeded in 7.00 by pushing the bar with his head
in the course of efforts to poke his head in at the door. I then put him
through the act 10 times and left him to himself. He failed in 5.00; no
activity. I then sat down by the cage as when teaching him. He failed in
5; little activity. Later in the day I put him through the act 10 times
and then left him to himself. He failed in 5; little activity. I sat
down as before. He failed in five; little activity. On January 6th I put
him through the act 10 times and then left him. He failed in 10. This
was repeated later in the day with the same result. Record:—By himself,
10 F. Put through 80 times. F 65 (a) [the (a) refers to a note of his
unrepeated chance success with his head]. No similar act unsuccessfully
attempted. Influence of tuition, none.
With the chute mechanisms the record would be of the same nature. With
them I put the animal through generally by taking his paw, held out
through the wire netting of the cage, and making the movement with it.
In one experiment (No. 3 with QQ chute) the first 58 trials were made by
taking the monkey outside the cage and holding him instead of having him
put his paw through the netting for me to take.
Many of the experiments were with mechanisms which had previously
been used in experiments concerning the ability to learn from seeing
me operate them. And the following Table (12) includes the results of
experiments of both sorts. The results of experiments of the ‘on chair’
type are in Table 13. In cases where the same apparatus was used for both
purposes, the sort of training which was given first is that where an A
is placed.
In the first four experiments with No. 1 there was some struggling and
agitation on his part while being held and put through the act. After
that there was none in his case except occasional playfulness, and there
was never any with No. 3 after the first third of the first experiment.
The monkeys soon formed the habit of keeping still, because it was only
when still that I put them through the act and that food resulted. After
you once get them so that they can be held and their arms taken without
their clinging to you, they quickly learn to adapt themselves to the
experiments.
With No. 1, out of 8 cases where he had of himself failed (in five of the
cases he had also failed after being shown by me), he succeeded after
being put through (13, 21, 51, 10, 7, 80, and 10 times) in two cases (QQ
(chute) and RR (wood plug). The act was unlike the one taught him in the
former case.
TABLE 12
Table headings:
Column A: SUBJECT. DATE. ACT
Column B: TIMES TRIED ALONE, WITH RESULT
Column C: NUMBER OF TIMES ATTENTION ATTRACTED
Column D: RESULT
Column E: NUMBER OF TIMES SHOWN BY ME
Column F: RESULT IN TRIALS AFTER BEING SHOWN BY ME
Column G: NUMBER OF TIMES PUT THROUGH THE ACT
Column H: RESULT IN TRIALS AFTER BEING PUT THROUGH THE ACT
Column I: COMPARISON OF ACT USED WITH ACT TAUGHT
Column J: SIMILAR ACT ATTEMPTED THOUGH UNSUCCESSFULLY
Column K: ACT DONE ONCE OR MORE, BUT NOT REPEATED IN SPITE OF
REPEATED TUITION
========================+==========+====+========+========+========+
A | B | C | D | E | F |
------------------------+----------+----+--------+--------+--------+
No. 1, Jan. 7, 1900, | 10 F | | | | |
PP (string across) | 10 F | | | | |
| | | | | |
No. 1, Jan. 17, 1900, | 15 F | | | 21 A |150 F |
MM (bolt at top) | | | | | 10 F |
| | | | | |
No. 1, Feb. 24, 1900, | 2.20 | | | 4} | 10 F |
OOO (upper string) | 3 F | | | 4} 12 | .20 |
| | | | 4} | |
| | | | 4 | .22 |
| | | | | |
No. 1, Mar. 24, 1900, | 120 F | | | 10 A | 60 F |
QQ (chute) | | | | | |
| | | | | |
No. 1, Apr. 5, 1900, | 10 F | 2 | 5 F | 1 A | 2 F |
RR (wood plug) | | | | 1 | 2 F |
| | | | 1 | 2 F |
| | | | 1 | 5 F |
| | | | | |
No. 1, Oct. 20, 1900, | 10 F | | | 4 | .22 |
VV (loop) | 10 F | | | | |
| 10 F | | | | |
| 10 F | | | | |
| | | | | |
No. 1, Nov. 19, 1900, | 10 F | | | 5 | 10 F |
Theta (new bolt) | | | | | |
| | | | | |
No. 1, Jan. 4, 1901, | 10 F | | | 15 | 10 F |
Delta (push back) | | | | | |
| | | | | |
No. 1, Jan. 6, 1901, | 8.00 | | | 40 | 10 F |
QQ (a) (single | | | | |2.00 |
wind chute) | | | | | .50 |
| | | | | |
No. 1, Jan. 7, 1901, | 5 F | | | | |
Zeta (side plug new) | | | | | |
| 1.10 | | | | |
| | | | | |
No. 1, Jan. 9, 1901, | 3.00 | | | 10 | 5 F |
QQ (b) (2½ | to .06 | | | | 5 F |
wind chute) | 5 F | | | |3.00 |
| | | | | 5 F |
| | | | | |
No. 1, Jan. 11, 1901, | 5 F | 5 | 5 F | 1[32] |2.20 |
QQ (c) (nail chute) | 5 F | | | | |
| | | | | |
No. 1, Jan. 12, 1901, | 5 F | | | 25 A | 10 F |
Epsilon (push down) | 10 F | | | | 10 F |
| | | | 15 | 10 F |
| | | | | |
No. 1, Jan. 16, 1901, | 5 F | 5 | 3.30 | | |
QQ (d) (pull chute) | 5 F | | .10 | | |
| | | | | |
No. 1, Jan. 17, 1901, | 5 F | 5 | 5 F | 15 A | 5 F |
QQ (f) (string chute) | | | | | 5 F |
| | | | | |
No. 1, Jan. 18, 1901, | 5 F | 3 | im. | | |
QQ (e) (hook chute) | | | | | |
| | | | | |
No. 3, Dec. 17, 1900, | 60 F | 3 | 60 F | 10 A | 5 F |
QQ (chute) | | | | 30 | 30 F |
| | | | | |
No. 3, Dec. 17, 1900, | 10 F | | | | |
VV (loop) | 20 F | | | | |
| | | | | |
No. 3, Jan. 4, 1901, | 10 F | | | 20 |8.00[34]|
Delta (push back) | 2.10 | | | |8.00[34]|
| (by | | | | |
| pulling | | | | |
| string) | | | | |
| | | | | |
No. 3, Jan. 4, 1901, | 10 F | | | 30 | 10 F |
Gamma (wind) | 10 F | | | | 10 F |
| | | | | |
No. 3, Jan. 8, 1901, | 10 F[36]| | | 25 | 6 F |
Theta (bolt at top) | | | | | |
| | | | | |
No. 3, Jan. 9, 1901, | 10 F | | | |3.00[37]|
QQ (a) (chute bar) | | | | | |
| | | | | |
| | | | | |
| | | | | |
No. 3, Jan. 9, 1901, | | | | | |
QQ (b) (2½ wind chute)| 10 F | | | 20 | 8 F |
| | | | | 8 F |
| | | | | |
No. 3, Jan. 11, 1901, | 5 F | 10 | 5 F | 25 A | 5 F |
QQ (c) (nail chute) | 5 F | |12 F[38]| | 5 F |
| | | | |1.30 |
| | | | | 5 F |
| | | | |10 F |
| | | | | |
No. 3, Jan. 15, 1901, | 10 F | | | 25 A | 5 F |
Epsilon (push down) | | | | | 5 F |
| | | | | |
| | | | | |
No. 3, Jan. 16, 1901, | | | | | |
QQ (e) (hook chute) | 5 F | 5 | 5 F | 5 A |2.00 |
| | | | |1.25 |
| | | | |1.20 |
| | | | | |
No. 3, Jan. 19, 1901, | 5 F | | 5 | 5 A | 5 F |
QQ (ff) (string chute | 5 F | | | | |
with wire) | 2.00[39] | | | | |
| | | | | |
| | | | | |
No. 3, Jan. 22, 1901, | 5 F | | | | |
WW (bar inside) |previously| | | | |
| some | | | | |
| 40.00 F | | | | |
========================+==========+====+========+========+========+
========================+======+========+===========+========+======
A | G | H | I | J | K
------------------------+------+--------+-----------+--------+------
No. 1, Jan. 7, 1900, | 13 | 10 F | | No. |
PP (string across) | | | | |
| | | | |
No. 1, Jan. 17, 1900, | 21 | 10 F | | (?) |
MM (bolt at top) | | | | |
| | | | |
No. 1, Feb. 24, 1900, | | | Partly | |
OOO (upper string) | | | similar. | No. |
| | | | |
| | | | |
| | | | |
No. 1, Mar. 24, 1900, | 10 | 30.00 |Dissimilar.| No. |
QQ (chute) | | | | |
| | | | |
No. 1, Apr. 5, 1900, | 7 | 2.20 | Similar. | Yes(?) |
RR (wood plug) | 2 | 2.00 | | |
| | | | |
| | | | |
| | | | |
No. 1, Oct. 20, 1900, | | | Similar. | |
VV (loop) | | | | |
| | | | |
| | | | |
| | | | |
No. 1, Nov. 19, 1900, | 51 A | 132 F | | No. |
Theta (new bolt) | | | | |
| | | | |
No. 1, Jan. 4, 1901, | 80 A |65 F[31]| | No. |
Delta (push back) | | | | |
| | | | |
No. 1, Jan. 6, 1901, | | |Dissimilar.| |
QQ (a) (single | | | | |
wind chute) | | | | |
| | | | |
No. 1, Jan. 7, 1901, | | | | |
Zeta (side plug new) | 20 | im. | ? | |
| | im. | | |
| | | | |
No. 1, Jan. 9, 1901, | | |Dissimilar.| No. |Yes.
QQ (b) (2½ | | | | |
wind chute) | | | | |
| | | | |
| | | | |
No. 1, Jan. 11, 1901, | | |Dissimilar.| |Yes.[33]
QQ (c) (nail chute) | | | | |
| | | | |
No. 1, Jan. 12, 1901, | 10 | 5 F | | No. |
Epsilon (push down) | 10 | 10 F | | |
| | | | |
| | | | |
No. 1, Jan. 16, 1901, | | | | |
QQ (d) (pull chute) | | | | |
| | | | |
No. 1, Jan. 17, 1901, | 10 | 5 F | | |
QQ (f) (string chute) | | | | |
| | | | |
No. 1, Jan. 18, 1901, | | | | |
QQ (e) (hook chute) | | | | |
| | | | |
No. 3, Dec. 17, 1900, |113 | 90 F | | (?) |
QQ (chute) | | | | |
| | | | |
No. 3, Dec. 17, 1900, | 23 | 20 F | | No. |
VV (loop) | | | | |
| | | | |
No. 3, Jan. 4, 1901, | 5 A |2.00[35]|Dissimilar.| No. |
Delta (push back) | 5 | 3.20 | | |
| 15 | 30 F | | |
| 5 | 10 F | | |
| | | | |
| | | | |
No. 3, Jan. 4, 1901, | 20 A | 5 F | | No. |
Gamma (wind) | | 8 F | | |
| | | | |
No. 3, Jan. 8, 1901, | | |Dissimilar.| |
Theta (bolt at top) | | | | |
| | | | |
No. 3, Jan. 9, 1901, | 10 | | | No |
QQ (a) (chute bar) | 10 | .40 | ? |complete|
| 10 | 1.00 | | circle.|
| 10 | 1.00 | | |
| | | | |
No. 3, Jan. 9, 1901, | | | | |
QQ (b) (2½ wind chute)| | 5 F |Dissimilar.| |Yes.
| | | | |
| | | | |
No. 3, Jan. 11, 1901, | 45 | 38 F | | No. |Yes.
QQ (c) (nail chute) | | | | |
| 10 | 10 F | | |
| | | | |
| | | | |
| | | | |
No. 3, Jan. 15, 1901, | 20 | 11.00 | | No. |Yes.
Epsilon (push down) | | 30 F | ? | |
| 15 | 10 F | | |
| | | | |
No. 3, Jan. 16, 1901, | | | | |
QQ (e) (hook chute) | 10 | .10 |Dissimilar.| No. |
| | .10 | | |
| | | | |
| | | | |
No. 3, Jan. 19, 1901, | 7 | 5 F | | |
QQ (ff) (string chute | 8 | 5 F | | |
with wire) | 12 | 3.00 |Dissimilar.| No. |
| | 5 F | | |
| | | | |
No. 3, Jan. 22, 1901, | 10 | 5 F | | |
WW (bar inside) | |6.00[40]| | |
| | | | |
| |7.00[40]|Dissimilar.| No. |
========================+======+========+===========+========+======
In only one case (bolt at top) out of eight was there possibly any
attempt at the act after he had been put through which had not been made
before. The ‘yes or?’ in the table with RR was a case occurring after the
imitation of me but before the putting No. 1 through.
Out of 6 cases where he had himself failed, No. 3 succeeded (after being
put through 113, 23, 20, 10, 10, 20 and 10 times) in 3 cases (chute bar,
push down and bar inside). The act was dissimilar in all three cases,
bearing absolutely no resemblance in one case. There was no unsuccessful
attempt at the act taught him in any of the cases. With the chute he
did finger the bar after tuition where he had not done so before, but
it was probably an accidental result of his holding his hand out toward
it for me to take as he had formed the habit of doing. In the case of
box Epsilon (push down), with which he succeeded by pushing his hand in
above the lever (an act which though unlike that taught him might be by
some considered to be due to an idea gained from the tuition), he failed
entirely after further tuition (15 times).
Like the dogs and cats, then, the monkeys seemed unable to learn to do
things from being put through them. We may now examine those which they
did do of themselves before tuition and ask whether they learned the more
rapidly thereby or modified their behavior in ways which might be due to
the tuition. There are too few cases and no chance for comparison on the
first point; on the second the records are unanimous in showing no change
in the method of operating the mechanisms due to the tuition.
As in Table 9, figures followed by F mean that in that length of time
the animal failed. Figures without an F denote the time taken by the
animal to operate the mechanism.
As a supplement to Table 12 I have made a summary of the cases where the
animals did succeed after tuition, that shows the nature of the act shown
them as compared with the act they made use of.
SUPPLEMENT TO TABLE 12
==========+=====================+===================+====================
APPARATUS | MODEL GIVEN OR ACT | ACT OF NO. 1 | ACT OF NO. 3
| PUT THROUGH | |
----------+---------------------+-------------------+--------------------
OOO |To pull upper |Pulled both strings|
| string. | alternately, but |
| | upper enough |
| | more to succeed. |
| | |
QQ |To push bar in. |Inserted fingers |
| | between bar and |
| | its slot and |
| | pulled and |
| | pushed vaguely. |
| | |
RR |To pull plug out |Pulled and bit. |
| with right hand. | |
| | |
VV |To pull loop off nail|_Similar._ |
| with right hand. | |
| | |
QQ (a) |To pull bar around |Pulled back |Pulled back
| toward him. | and forth | and forth
| | indiscriminately.| indiscriminately.
| | |
QQ (b) |To pull bar around |Pulled back |
| toward him in | and forth |
| 2½ continuous | indiscriminately.|
| revolutions. | |
| | |
QQ (c) |To take nail and pull|Pulled back and |_Similar_ or
| directly outward. | forth. | nearly so.
| | |
Delta |To push bar to right | |Did before tuition
| with right hand. | | by pulling wire;
| | | after tuition by
| | | chance movement
| | | of head.
| | |
Theta |To pull bolt up with | |Pulled door and
| right hand. | | worked bolt loose.
| | |
Epsilon |To stand in front, | |Inserted arm in
| insert fingers of | | general activity
| right hand and | | while on top of
| press lever down. | | the box.
| | |
QQ (e) |To pull hook down. | |Pulled at the lever
| | | and hook in a
| | | general attack on
| | | the apparatus.
| | |
QQ (ff) |To pull wire loop | |Pulled outward on
| off nail with | | the lever which
| right hand. | | pushed the banana
| | | down the
| | | chute so hard as
| | | to pull it off its
| | | pivot.
| | |
WW |To stand on top of | |Pulled at door until
| box, reach right | | bar worked out
| hand down and | | of its catch.
| pull bar up. | |
==========+=====================+===================+====================
I have kept the results of the tests of the ‘on chair’ type separate from
the others because they may be tests of a different thing and surely are
subject to different conditions.
They were tests of the animals’ ability to form the habit of going to a
certain place by reason of having been _carried_ there and securing food
thereby. I would leave the animal loose in the room, and if he failed
in 5 or 10 minutes to go to the place of his own accord, would put him
back in his cage; if he did go of his own accord, I would note the time.
Then I would take him, carry him to the place, and feed him. After doing
this 10 times I would turn him loose again and see whether the idea of
being fed in such and such a place was present and active in making him
go to the place. In such tests we are absolutely sure that the animal can
without any difficulty perform the necessary movements and would in case
the proper stimulus to set them off appeared, if, for instance, a bit of
food on one of the places to which he was to go caught his eye. In so far
forth the tests were favorable cases for learning. On the other hand, the
situation associated with getting food may have been in these cases not
the mere ‘being on box’ but the whole previous experience ‘being carried
while clinging and being put or let jump on a box.’ In this respect the
tests may have been less favorable than the acts where getting food was
always the direct sequent of the act of going into the box.
The experiments were:—
A. Carrying the animal and putting him on a chair.
B. Carrying the animal and putting him on a pile of boxes.
C. Carrying the animal and putting him on the top of a sewing machine.
D. Carrying the animal and putting him on the middle of a board 6 feet
long, stretched horizontally across the room, 3 feet from the floor.
E. Carrying the animal and putting him on the side of the cage, head down.
The results are given in Table 13.
The size of the room in which I worked and other practical difficulties
prevented me from extending these experiments. As they stand, no stable
judgments can be inferred from them. It should be noted that in the
successful cases there were no other signs of the presence of the idea
‘food when there’ than the mere going to a certain place. The animal did
not wait at the place more than a second or two, did not look at me or
show any signs of expecting anything.
TABLE 13
================+==========+==============+===============+===========
EXPERIMENT | |RESULTS BEFORE|NUMBER OF TIMES| RESULTS
AND DATE | ANIMAL | TRAINING | PUT THROUGH | AFTER
| | | | TRAINING
----------------+----------+--------------+---------------+-----------
A. Jan. 22, 1901| No. 1. | 5 F | 10 | 1.00
| | | | 3.00
Jan. 22, 1901| No. 1. | 5 F | 10 | im.
| | | | 3.30
Jan. 23, 1901| No. 3. | 5 F | 10 | 3.30
| | 5 F | |
B. Jan. 26, 1901| No. 1. | 10 F | 10 and 5 | 10 F 5 F
| No. 3. | 5 F | 10 | 5 F
| | | 10 | 5 F
C. Jan. 27, 1901| No. 1. | 5 F | 10 | 3.00
D. Jan. 27, 1901| No. 1. | 3.20 | 10 | 5 F
E. Jan. 26, 1901| No. 3. | 5 F | 5 | 5 F
================+==========+==============+===============+===========
Although, as I noted in the early part of this monograph, there were
occasionally phenomena in the general behavior of the monkeys which of
themselves impressed one as being suggestive of an ideational life,
the general run of their learning apart from the specific experiments
described was certainly confined to the association of impulses of their
own with certain situations. The following examples will suffice:—
In getting them so that they would let themselves be handled it was of
almost no service to _take_ them and feed them while holding them or
otherwise make that state pleasant for them. By far the best way is to
wait patiently till they do come near, then feed them; wait patiently
till they do take hold of your arm, then feed them. If you do take them
and hold them partly by force, you must feed them only when they are
comparatively still. In short, in taming them one comes unconsciously
to adopt the method of rewarding certain of their impulses rather than
certain _conditions_ which might be associated in their minds with ideas,
had they such.
After No. 1 and No. 3 had both reached a point where both could hardly
be gotten to leave me and go back into their cages or down to the floor
of the room, where they evidently enjoyed being held by me, they still
did not climb upon me. The idea of clinging to me was either absent or
impotent to cause them to act. What they did do was, in the case of
No. 1, to jump about, pawing around in the air, until I caught an arm
or leg, to which stimulus he had by dint of the typical sort of animal
association learned to react by jumping to my arm and clinging there; in
the case of No. 3, to stand still until I held my arm right in front of
him (if he were in his cage) or to come and stand on his hind legs in
front of me (if he were out on the floor). In both cases No. 3’s act was
one which had been learned by my rewarding his impulses. I often tried,
at this period of their intimacy with me, this instructive experiment.
The monkey would be clinging to me so that I could hardly tear him away.
I would do so, and he would, if dropped loose from me, make no efforts to
get back.
I have already mentioned my failure to get the animals to put out their
right hands through the netting after they had long done so with their
left hands. With No. 3 I tried putting my fingers through and poking the
arm out and then making the movement with it. He profited little if any
by this tuition. Had I somehow induced him to do it himself, a few trials
would have been sufficient to get the habit well under way.
Monkey No. 1 apparently enjoyed scratching himself. Among the stimuli
which served to set off this act of scratching was the irritation from
tobacco smoke. If any one would blow smoke in No. 1’s face, he would
blink his eyes and scratch himself, principally in the back. After a
time he got in the habit of coming to the front of his cage when any one
was smoking and making such movements and sounds as in his experience
had attracted attention and caused the smoker to blow in his face. He
was often given a lighted cigar or cigarette to test him for imitation.
He formed the habit of rubbing it on his back. After doing so he would
scratch himself with great vigor and zest. He came to do this always
when the proper object was given him. I have recounted all this to show
that the monkey enjoyed scratching himself. _Yet he apparently never
scratched himself except in response to some sensory stimulus._ He was
apparently incapable of thinking ‘scratch’ and so doing. Yet the act was
quite capable of association with circumstances with which as a matter
of hereditary organization it had no connection. For by taking a certain
well-defined position in front of his cage and feeding him whenever he
did scratch himself I got him to always scratch within a few seconds
after I took that position.
GENERAL MENTAL DEVELOPMENT OF THE MONKEYS
It is to be hoped that the growing recognition of the worth of
comparative and genetic studies will lead to investigations of the mental
make-up of other species of monkeys, and to the careful overhauling of
the work done so far, including these rather fragmentary studies of mine.
Work with three monkeys of one species, especially when no general body
of phenomena, such as one has at hand in the case of domestic animals,
can be used as a means of comparison, must necessarily be of limited
application in all its details and of insecure application even in its
general features. What I shall say concerning the advance in the mental
development of the monkeys over that of other mammals may then be in
strictness true of only my three subjects, and it may be left to the
judgment of individuals to extend my conclusions as far as seems to them
likely. To me it seems fairly likely that the very general mental traits
which the research has demonstrated hold true with little variation in
the monkeys in general.
The monkeys represent progress in mental development from the generalized
mammalian type toward man:—
1. In their sensory equipment, in the presence of focalized vision.
2. In their motor equipment, in the coördinated movements of the hand and
the eye.
3. In their instincts or inherited nervous connections, in their general
physical and mental activity.
4. In their method of learning or associative processes; in—
_a._ Quicker formation of associations,
_b._ Greater number of associations,
_c._ Greater delicacy of associations,
_d._ Greater complexity of associations,
_e._ Greater permanence of associations.
The fact of (1) is well known to comparative anatomists. Its importance
in mental development is perhaps not realized, but appears constantly to
a systematic student.
(2) is what accounts for much of the specious appearance of human ways
of thinking in the monkeys and becomes in its human extension the handy
tool for much of our intellectual life. It is in great measure the
prerequisite of 4 _c_.
(3) accounts for the rest of such specious appearances, is at the basis
of much of 4 _b_, presages the similar though extended instincts of the
human being, which I believe are the leading efficient causes of human
mental capacity, and is thus the great mental bond which would justify
the inclusion of monkeys and man in a common group if we were to classify
animals on the basis of mental characteristics.
Even the casual observer, if he has any psychological insight, will be
struck by the general, aimless, intrinsically valuable (to the animal’s
feelings) physical activities of a monkey compared with the specialized,
definitely aroused, utilitarian activities of a dog or cat. Watch the
latter and he does but few things, does them in response to obvious
sense presentations, does them with practical consequences of food,
sex-indulgence, preparation for adult battles, etc. If nothing that
appeals to his special organization comes up, he does nothing. Watch a
monkey and you cannot enumerate the things he does, cannot discover the
stimuli to which he reacts, cannot conceive the _raison d’être_ of his
pursuits. Everything appeals to him. He likes to be active for the sake
of activity.
The observer who has proper opportunities and takes proper pains will
find this intrinsic interest to hold of mental activity as well. No. 1
happened to hit a projecting wire so as to make it vibrate. He repeated
this act hundreds of times in the few days following. He did not, could
not, eat, make love to, or get preliminary practice for the serious
battles of life out of, that sound. But it did give him mental food,
mental exercise. Monkeys seem to enjoy strange places; they revel, if I
may be permitted an anthropomorphism, in novel objects. They like to have
feelings as they do to make movements. The fact of mental life is to them
its own reward.
It is beyond question rash for any one to venture hypotheses concerning
the brain parallel of mental conditions, most of all for the ignoramus
in the comparative histology of the nervous system, but one cannot help
thinking that the behavior of the monkeys points to a cerebrum that is
no longer a conservative machine for making a few well-defined sorts of
connections between sense-impressions and acts, that is not only fitted
to do more delicate work in parts, but is also alive, tender all over,
functioning throughout, set off in action by anything and everything. And
if one adds coördinations allowing a freedom and a differentiation of
action of the muscles used in speech comparable to that already present
in connection with the monkey’s hand, he may well ask, “What more of a
nervous mechanism do you need to parallel the behavior of the year-old
child?” However, this is not the place to speculate upon the importance
to human development of our instinctive aimless activity, physical and
mental, or to describe further its similarity and evident phylogenetic
relationship to the instinctive behavior of the monkeys. Elsewhere I
shall undertake that task.
4. In their method of learning, the monkeys do not advance far beyond the
generalized mammalian type, but in their proficiency in that method they
do. They seem at least to form associations very much faster, and they
form very many more. They also seem superior in the delicacy and in the
complexity of the associations formed and the connections seem to be more
permanent.
This progress may seem, and doubtless will to the thinker who looks upon
the human intellect as a collection of functions of which ideation,
judgment and reasoning are chief, to be slight. To my mind it is not
so in reality. For it seems to me highly probable that the so-called
‘higher’ intellectual processes of human beings are but secondary results
of the general function of having free ideas and that this general
function is the result of the formation after the fashion of the animals
of a very great number of associations. I should therefore say, “Let
us not wonder at the comparative absence of free ideas in the monkeys,
much less at the absence of inferences or concepts. Let us not wonder
that the only demonstrable intellectual advance of the monkeys over the
mammals in general is the change from a few, narrowly confined, practical
associations to a multitude of all sorts, for that may turn out to be at
the bottom the only _demonstrable advance of man_, an advance which in
connection with a brain acting with increased delicacy and irritability,
brings in its train the functions which mark off human mental faculty
from that of all other animals.”
The typical process of association described in Chapter II has since been
found to exist among reptiles (by Mr. R. M. Yerkes) and among fishes (by
myself). It seems fairly likely that not much more characterizes the
primates. If such work as that of Lubbock and the Peckhams holds its own
against the critical studies of Bethe, this same process exists in the
insects. Yerkes and Bosworth think they have demonstrated its presence
in the crayfish. Even if we regard the learning of the invertebrates as
problematic, still this process is the most comprehensive and important
thing in mental life. I have already hinted that we ought to turn our
views of human psychology upside down and study what is now casually
referred to in a chapter on habit or on the development of the will, as
the general psychological law, of which the commonly named processes are
derivatives. When this is done, we shall not only relieve human mentality
from its isolation and see its real relationships with other forms; we
may also come to know more about it, may even elevate our psychologies
to the explanatory level and connect mental processes with nervous
activities without arousing a sneer from the logician or a grin from the
neurologist.