_Box Stacking Experiment_
In addition to the multiple-choice experiments which have been described
in detail in the previous section, it was possible to conduct certain
less systematic tests of ideational behavior in the monkeys and the
orang utan. From the technical standpoint these tests were relatively
unsatisfactory because only inexactly describable. But their results are
in many respects more interesting, if not also more important, in the
light which they throw on ideation than are those previously presented.
First, in order of time, comes a test which may be designated as the box
stacking experiment. The method will now be described in connection with
an account of the behavior of Julius as contrasted with that of a child
of three years and four months of age.
In the large central cage labelled Z, figure 12, which was twenty-four
feet long, ten feet wide, and ten to twelve feet deep, the following
situation was arranged. From the center of the wire covering of the
cage, a banana was suspended on a string so that it was approximately
six feet from the floor, five feet from either side of the cage, and
twelve feet from either end. From all approaches it was far beyond the
reach of Julius, since it was impossible for him to climb along the wire
roof and thus reach the string. Two boxes were placed on the floor of
the cage several feet from the point directly under the banana. The one
of these boxes was heavy and irregular in shape, as is shown in figures
21, 23 and 24 of plate V. Its greatest height was twenty-one inches; its
least height, eighteen inches; its other dimensions, twelve and sixteen
inches respectively. The smaller and lighter box measured twenty-two by
twelve by ten inches. According to the experimenter's calculations, the
only way in which Julius could obtain the banana was by placing the
smaller box upon the larger and then climbing upon them.
At 10 a.m. on March 5, Julius was admitted to the large cage, and the
banana was pointed out to him by the experimenter. He immediately set
about trying to get it, and worked diligently during the whole of the
period of observation, which, because of the unfinished condition of
some of the cages, was limited to slightly over ten minutes. Within this
period he made upward of a dozen fairly well directed attempts to obtain
the food. Chief among them were three attempts to reach the banana from
different positions on the left wall of the cage (as the experimenter
faced the laboratory); two attempts to reach it from different positions
on the right wall; two from the large box in positions nearly under the
banana; two from the large box with the aid of the experimenter's hand;
and one from the distant end of the cage(?). There occurred, also, less
definite and easily describable efforts to get at the reward.
On account of the unfinished condition of the cages, the experimenter
had to remain in the large cage with Julius during the test. This
interfered with the experiment because the animal tended both to try to
escape and to get the experimenter to help him with his task.
Particularly interesting is the latter sort of behavior. After the orang
utan had made two or three futile attempts to obtain the food he came to
the experimenter, who was standing in one corner of the cage, took him
by the hand, and led him to a point directly under the banana. He then
looked up toward the banana, grasped the experimenter's arm, raised it,
and then tried to pull himself up. He was not allowed to get the food by
climbing up on the experimenter. A few minutes later, he again led the
experimenter toward the banana, but receiving discouragement in this
activity, he proceeded to devote himself to other methods.
Apart from the distractions which have been mentioned above, Julius's
attention to the food was surprisingly constant. Whatever his position
with respect to it, he seemed not for an instant to lose his motive, and
to whatever part of the cage he went and whatever he did during the
interval of observation was evidently guided by the strong desire to
obtain the banana. Frequently he would look directly at it for a few
seconds and then try some new method of reaching it. His gaze was
deliberate and in the handling of the boxes he accurately gauged
distances. Several times he succeeded in placing the larger box almost
directly under the banana, and repeatedly he located that portion of the
side wall from which he could most nearly reach the coveted prize.