========+===========+==============+==============+==============+==============+==============+==============+==============+==============+==============+==============+===+===+===+===+========
| No. | S.1 | S.2 | S.3 | S.4 | S.5 | S.6 | S.7 | S.8 | S.9 | S.10 | | | | | Ratio
Date | of | | | | | | | | | | | R | W | R | W | of
| trials | 1.2.3 | 8.9 | 3.4.5.6.7 | 7.8.9 | 2.3.4.5.6 | 6.7.8 | 5.6.7 | 4.5.6.7.8 | 7.8.9 | 1.2.3 | | | | | R to W
--------+-----------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+---+---+---+---+--------
| | | | | | | | | | | | | | | |
April | | | | | | | | | | | | | | | |
13 | 1- 10 | 3.1 | 8 | 4.3 | 7 | 4.2 | 7.6 | 5 | 4 | 7 | 3.1 | 5 | 5 | 5 | 5 | 1:1.00
14 | 11- 20 | 3.2.1 | 8 | 4.3 | 7 | 4.4.2 | 6 | 5 | 4 | 7 | 3.1 | 6 | 4 | 6 | 4 | 1:0.67
15 | 21- 30 | 3.2.1 | 8 | 4.3 | 7 | 4.5.5.2 | 6 | 5 | 4 | 7 | 3.1 | 6 | 4 | 6 | 4 | 1:0.67
16 | 31- 40 | 3.1 | 8 | 4.3 | 7 | 4.2 | 6 | 5 | 4 | 7 | 3.2.1 | 6 | 4 | 6 | 4 | 1:0.67
17 | 41- 50 | 3.2.1 | 8 | 4.3 | 7 | 4.2 | 6 | 5 | 4 | 7 | 3.1 | 6 | 4 | 6 | 4 | 1:0.67
19 | 51- 60 | 3.1 | 8 | 4.3 | 7 | 4.2 | 6 | 5 | 4 | 7 | 3.1 | 6 | 4 | 6 | 4 | 1:0.67
20 | 61- 70 | 2.1 | 8 | 4.3 | 7 | 5.3.2 | 6 | 5 | 4 | 7 | 3.1 | 6 | 4 | 6 | 4 | 1:0.67
21 | 71- 80 | 3.1 | 8 | 4.3 | 7 | 5.4.3.2 | 6 | 5 | 4 | 7 | 3.2.1 | 6 | 4 | 6 | 4 | 1:0.67
22 | 81- 90 | 3.1 | 8 | 5.3 | 7 | 6.3.2 | 6 | 5 | 4 | 7 | 3.2.1 | 6 | 4 | 6 | 4 | 1:0.67
23 | 91-100 | 3.2.1 | 8 | 5.3 | 7 | 4.3.2 | 6 | 5 | 5.4 | 7 | 3.2.1 | 5 | 5 | 5 | 5 | 1:1.00
24 | 101-110 | 3.2.1 | 8 | 4.3 | 7 | 4.3.2 | 6 | 5 | 4 | 7 | 3.1 | 6 | 4 | 6 | 4 | 1:0.67
26 | 111-120 | 3.1 | 8 | 4.3 | 7 | 4.3.2 | 6 | 5 | 5.4 | 7 | 3.1 | 5 | 5 | 5 | 5 | 1:1.00
27 | 121-130 | 3.2.1 | 8 | 4.3 | 7 | 4.3.2 | 6 | 6.5 | 5.8.6.4 | 7 | 3.3.3.1 | 4 | 6 | | |
" | 131-140 | 3.1 | 8 | 4.3 | 7 | 4.3.2 | 6 | 5 | 4 | 7 | 3.2.1 | 6 | 4 |10 |10 | 1:1.00
28 | 141-150 | 3.2.1 | 8 | 3 | 7 | 5.4.2 | 6 | 5 | 4 | 7 | 3.1 | 7 | 3 | | |
" | 151-160 | 3.1 | 8 | 3 | 7 | 3.2 | 6 | 5 | 4 | 7 | 3.2.1 | 7 | 3 |14 | 6 | 1:0.43
29 | 161-170 | 3.1 | 8 | 4.3 | 7 | 4.3.2 | 6 | 5 | 4 | 7 | 3.2.1 | 6 | 4 | | |
" | 171-180 | 3.2.1 | 8 | 4.3 | 7 | 4.2 | 6 | 5 | 4 | 7 | 3.2.1 | 6 | 4 |12 | 8 | 1:0.67
| | | | | | | | | | | | | | | |
30 | 181-190 | 3.1 | 8 | 4.3 | 7 | {4.5.6.4 | 6 | 5 | 4 | 7 | 3.1 | 6 | 4 | | |
| | | | | | {5.6.4.2 | | | | | | | | | |
| | | | | | | | | | | | | | | |
" | 191-200 | 3.1 | 8 | 4.5.6.7.3 | 7 | 4.5.3.2 | 6 | 5 | 4 | 7 | 3.2.1 | 6 | 4 |12 | 8 | 1:0.67
May | | | | | | | | | | | | | | | |
1 | 201-210 | 3.1 | 8 | 4.3 | 7 | 3.2 | 6 | 5 | 4 | 7 | 3.1 | 6 | 4 | | |
" | 211-220 | 3.2.1 | 8 | 4.3 | 7 | 4.2 | 6 | 5 | 4 | 7 | 3.1 | 6 | 4 |12 | 8 | 1:0.67
--------+-----------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+---+---+---+---+--------
| | | | 2.3.4.5 | | | | | | | 2.3.4.5 | | | | |
| | 1.2.3 | 3.4.5.6.7 | 6.7.8 | 1.2.3 | 3.4.5.6.7 | 4.5.6.7.8.9 | 2.3.4.5 | 1.2.3 | 4.5.6.7.8.9 | 6.7.8.9 | | | | |
--------+-----------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+---+---+---+---+--------
3 | 221-230 | 3.1 | 4.3 | 4.2 | 3.1 | 4.3 | 4 | 4.3.2 | 3.1 | 4 | 4.3.2 | 2 | 8 | 2 | 8 | 1:4.00
--------+-----------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+---+---+---+---+--------
| | | | 2.3.4.5 | 4.5.6.7 | | | | | 2.3.4.5 | | | | | |
| | 1.2.3 | 3.4.5.6.7 | 6.7.8 | 8.9 | 2.3.4.5 | 3.4.5.6 | 1.2.3 | 4.5.6.7.8 | 6.7.8.9 | 1.2.3 | | | | |
--------+-----------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+---+---+---+---+--------
4 | 231-240 | 3.2.1 | 4.3 | 4.2 | 4 | 4.3.2 | 4.3 | 3.2.1 | 4 | 3.2 | 3.2.1 | 2 | 8 | 2 | 8 | 1:4.00
5 | 241-250 | 2.1 | 3 | 3.2 | 4 | 3.2 | 4.3 | 3.2.1 | 4 | 3.2 | 3.2.1 | 3 | 7 | 3 | 7 | 1:2.33
6 | 251-260 | 2.1 | 3 | 2 | 4 | 3.2 | 3 | 2.1 | 4 | 3.2 | 2.1 | 5 | 5 | 5 | 5 | 1:1.00
7 | 261-270 | 2.1 | 3 | 3.2 | 4 | 3.2 | 3 | 2.1 | 4 | 4.2 | 2.1 | 4 | 6 | 4 | 6 | 1:1.50
8 | 271-280 | 2.1 | 4.3 | 4.3.2 | 4 | 3.2 | 4.3 | 3.1 | 4 | 3.2 | 2.1 | 2 | 8 | 2 | 8 | 1:4.00
10 | 281-290 | 1 | 4.3 | 4.2 | 4 | 3.2 | 4.3 | 2.1 | 4 | 3.2 | 2.1 | 3 | 7 | 3 | 7 | 1:2.33
11 | 291-300 | 1 | 3 | 2 | 4 | 2 | 3 | 1 | 4 | 2 | 1 |10 | 0 |10 | 0 | 1:0.00
--------+-----------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+---+---+---+---+--------
| | | | | | | | | | | | | | | |
| | 1.2.3 | 8.9 | 3.4.5.6.7 | 7.8.9 | 2.3.4.5.6 | 6.7.8 | 5.6.7 | 4.5.6.7.8 | 7.8.9 | 1.2.3 | | | | |
--------+-----------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+--------------+---+---+---+---+--------
12 | 301-310 | 1 | 8 | 3 | 7 | 2 | 6 | 5 | 4 | 7 | 1 |10 | 0 |10 | 0 | 1:0.00
========+===========+==============+==============+==============+==============+==============+==============+==============+==============+==============+==============+===+===+===+===+========
A series of correct first choices was obtained on May 11, greatly to the
surprise of the experimenter, for no indication had previously appeared
of this approaching solution of the problem. It seemed possible,
however, that the successes were accidental, and it was anticipated that
in a control series Julius would again make mistakes. But on the
following day, May 12, the presentation of the original series of ten
settings, which, of course, differed radically from the settings used
from May 4 to May 11 was responded to promptly, readily, and without a
single mistake. Julius had solved his problem suddenly and, in all
probability, ideationally.
Only three reactive tendencies or methods appeared during Julius's work
on this problem: (a) choice of the open door nearest to the starting
point (sometimes the adjacent boxes were entered); (b) a tendency to
avoid the "nearest" door and select instead one further toward the left
end of the group; (c) direct choice of the first door on the left.
The curve of learning plotted from the daily wrong choices and presented
in figure 18, had it been obtained with a human subject, would
undoubtedly be described as an ideational, and possibly even as a
rational curve; for its sudden drop from near the maximum to the base
line strongly suggests, if it does not actually prove, insight.
Never before has a curve of learning like this been obtained from an
infrahuman animal. I feel wholly justified in concluding from the
evidences at hand, which have been presented as adequately as is
possible without going into minutely detailed description, that the
orang utan solved this simple problem ideationally. As a matter of fact,
for the solution he required about four times the number of trials which
Sobke required and twice as many as were necessary for Skirrl. Were we
to measure the intelligence of these three animals by the number of
trials needed in problem 1, Sobke clearly would rank first, Skirrl
second, and Julius last of all. But other facts clearly indicate that
Julius is far superior to the monkeys in intelligence. We therefore must
conclude that _where very different methods of learning appear, the
number of trials is not a safe criterion of intelligence._ The
importance of this conclusion for comparative and genetic psychology
needs no emphasis.
_Problem 2. Second from the Right End_
Julius was given four days' rest before being presented with problem 2.
He was occasionally fed in the apparatus, but regular continuation of
training was not necessary to keep him in good form. During this rest
interval, locks were attached to the doors of the apparatus so that the
experimenter by moving a lever directly in front of him could fasten
either one or both of the doors of a given box by a single movement. On
May 13 Julius was given opportunity to obtain food from each of the
boxes in turn, and trial of the locks was made in order to familiarize
him with the new situation. He very quickly discovered that the doors
could not be raised when closed, and after two days of preliminary work,
he practically abandoned his formerly persistent efforts to open them.
The locks worked satisfactorily from a mechanical point of view as well
as from that of the adaptation of the animal to the modified situation.
Problem 2 was regularly presented for the first time on May 17, on which
day a single series was given. The period of punishment adopted was
twenty seconds, and for each successful choice a small piece of banana
was given as a reward. After the first trial in this series, in which
Julius repeatedly entered the first box at the left, that is box 7,
there was but slight tendency to reënter the first box at the left of
the group. Instead, Julius developed the method of moving box by box
toward the right end of the group. The choices were made promptly, and
their systematic character enabled the animal to obtain his reward
fairly quickly, in spite of the large number of mistakes.
In the second series, the orang utan developed the interesting trick of
quickly dodging out of the wrong box before the experimenter could lower
the door behind him. This he did only after having been punished for
many wrong choices to the point of discouragement. The trick was easily
broken up by the sudden lowering of the entrance door as soon as he had
passed under it.
There appeared on May 21 an unfavorable physical condition which
manifested itself, first of all through the eyes which appeared dull and
bloodshot. On the following day they were inflamed and the lids nearly
closed. Julius refused to eat, and experimentation was impossible. Until
June 2 careful treatment and regulation of diet was necessary. He passed
through what at the time seemed a rather startling condition, but
rapidly regained his usual good health, and on June 3, although somewhat
weak and listless, he again worked fairly steadily.
Since it was now possible to lock the doors and confine the animal for
any desired period, on June 5 the interval of punishment was made sixty
seconds, and a liberal quantity of banana, beet, or carrot was offered
as reward. No increase in the number of successful choices appeared, and
Julius showed discouragement. Sawdust had been strewn on the floor, and
in the intervals between trials as well as during confinement in wrong
boxes, he took to playing with the sawdust. He would take it up in one
hand and pour it from hand to hand until all had slipped through his
fingers, then he would scrape together another handful and go through
the same process. Often he became so intent on this form of amusement
that even when the exit door was raised, he would not immediately go to
get the food.
The reactive tendencies which appeared in the work on problem 2 will now
be presented in order, since I shall have to refer to them repeatedly,
and the list will be more useful to the reader at this point than at the
conclusion of the presentation of daily results. The following is not an
exhaustive list but includes only the most important and conspicuous
tendencies or methods together with the dates on which they were most
apparent.
(a) May 17, choice of first box at left of group or near it, then the
next in order, and so on, until the second from the right was reached.
This method with irregularities and certain definite skipping was used
at various times, sometimes over periods of several days, during the
course of the work.
(b) June 3, preference for number 3 and number 4 developed immediately
after the orang utan's illness and when he was working rather
listlessly.
On June 9 and 10, the original tendency (a) reappeared and persisted for
a number of series.
(c) June 14, a tendency to choose the box at or near the right end of a
group, and then the one next to it. In connection with this tendency,
which of course required only two choices in any given trial, interest
in playing with the sawdust on the floor developed.
Again on June 21, the animal returned to the use of tendency (a).
(d) June 29, movement to box at right end of group, hesitation before
it, and turning through a complete circle so that the second box from
the right was faced. This, the correct box, was often promptly entered.
This method, if persisted in, would obviously have yielded solution of
the problem.
(e) July 5, approach to and pretense to enter the box next to the right
end (right one), and then choice of some other box. This _feint_ is
peculiarly interesting, and its origin and persistence are difficult to
account for.
(f) In connection with the tendency to pretend that he was going to
enter the second box from the right end, Julius developed also the
tendency to turn around in front of the box at the right end, starting
sometimes to back into it, and then to enter, instead, the box second
from the end.
(g) July, 6 and 7, a fairly definite tendency to take the one next in
order or, instead, to go directly to the right box.
(h) July 10, direct first choices without approach to other boxes
appeared for the first time on this date.
For this problem, it proved impossible to establish and maintain uniform
conditions of experimentation. Instead, because of the failure of the
animal to improve and the tendency to discouragement, both punishment
and reward had to be altered from time to time, and other and more
radical changes were occasionally made in the experimental procedure.
Below for the sake of condensed and consecutive presentation, the most
important conditions from day to day are arranged in tabular form: