The period of confinement, as punishment for wrong choices, was increased from thirty seconds to sixty seconds on April 26.  But there is no satisfactory evidence that this favored the solution of the problem.  Work on May 4 was interrupted by a severe storm, the noise of which so distracted the monkey that he ceased to work.  Consequently, observations were interrupted on the completion of trial 132, and on May 5, the series was begun with setting 3.  On this date, eighteen trials were given in succession, and in only one of them did a mistake occur.  Since the ten trials numbered 133 to 142 were correct, Skirrl was considered to have solved problem 1, and systematic training was discontinued.

On the following day, as a measure of the extent to which the animal had learned to select the first door at the left no matter what its position or the number of doors in the group presented, a control series was given in which the settings differed from the regular series of settings.  These supplementary settings are presented at the bottom of table 1 together with the records of reaction in ten trials.

Since in only six of these ten control settings was the first choice correct, it is scarcely fair to insist that the animal was reacting on the basis of an ideational solution of the problem.  Rather, it would seem that he had learned to react to particular settings.  A careful study of all of the data of response, together with notes on the varied behavior of the animal during the experiments, justifies the statement that Skirrl’s solution of problem 1 was incomplete and unreliable.  It was highly dependent upon the particular situation, or even the particular door at the left end of the group, and slightly if at all dependent upon anything comparable to the human idea of first at the left of the group.

This particular series of observations has been described and discussed in some detail in order to make the chief points of method clear.  It will be needless, hereafter, to refer explicitly to many of the characteristics of reaction or to the important points in the construction of tables which have been mentioned.

A graphic representation of Skirrl’s learning process in problem 1 is presented in figure 18.  The irregularities are most striking, and fairly indicate the erraticness of the animal.  The curve is based upon the data in next to the last column of table 1, that is, the column presenting the errors or wrong first choices in each series of trials.

Unquestionably, the form of such a curve of learning should be considered in connection with the method or methods of selecting the right box employed by the animal during the course of experimentation.  It appears from an analysis of the behavior of Skirrl in problem 1 that there developed a single definite and persistent method, namely, that of going to one box in the group, and in case it happened to be a wrong one, of choosing, on emergence from it, the next toward