of the group was in each case omitted.

[Illustration: FIGURE 18.--Error curves of learning for the solution of
problem 1 (first box at left end).]

On the whole, Skirrl's behavior in connection with this problem appears
to indicate a low order of intelligence. He persisted in such stupid
acts as that of turning, after emergence from the right box, toward the
right and passing into the blind alley I, instead of toward the left,
through G and H, to D. In contrast with the other animals, he spent much
time before the closed doors of the boxes, instead of going directly to
the open doors, some one of which marked the box in which the reward of
food could be obtained. It is, moreover, obvious that his responses, as
they appear in table 1, are extremely different from those of a human
being who is capable of bringing the idea of first at the left end to
bear upon the problem in question.

_Problem 2. Second from the Right End_

Following the series of control trials of problem 1 given to Skirrl on
May 6, a period of four days was allowed during which the animal was
merely fed in the boxes each day. This was done in order that he should
partially lose the effects of his previous training to choose the first
box at the left before being presented with the second problem, the
second box from the right.

On May 11 regular experimentation was begun with problem 2. Naturally
the situation presented unusual difficulties to the monkey because of
his previously acquired habit, and on the first day it was possible to
give only five trials, in all except the first of which Skirrl had to be
aided by the experimenter to find the right box. He persistently, as
appears in the first line of records of table 2, entered the first box
at the left. The series was continued on May 13, but with very
unsatisfactory results, since he apparently had been greatly discouraged
by the unusual difficulties previously met. Only four trials could be
given, and in these the showing made was very poor. It is noteworthy,
however, that in trials 6, 7, and 8, May 13, there was no marked
tendency to choose the first box at the left. Thus quickly had the force
of the previous habit been broken.

For problem 2, the total number of open doors in the ten settings is
fifty, as appears from the data on page 18, and as ten of these fifty
open doors may be defined as right ones, the expected ratio of right to
wrong first choices in the absence of previous train