28 ROBERT M. YERKES 



exhibit right first choices, the remaining two exhibit the method 

 described above except that the final member at the right end of 

 the group was in each case omitted. 



On the whole, Skirrl's behavior in connection with this prob- 

 lem appears to indicate a low order of intelligence. He per- 

 sisted 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 re- 

 sponses, 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 e;iperimentation 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 set- 

 tings is :^fty, as appears from the data on page 18, and as ten of 



