MENTAL LIFE OF MONKEYS AND APES 23 



of food. The trials were given in rapid succession, and the total 

 time required for this first series of ten trials was thirty-five min- 

 utes. Skirrl worked faithfully throughout this interval and 

 exhibited no marked discouragement. When confined in a box 

 he showed uneasiness and dissatisfaction by moving about con- 

 stantly, shaking the doors, and trying to raise them in order 

 to escape. 



For the series of settings used in connection with problem 1, 

 the reader is referred to page 18. In the first setting, the doors 

 numbered 1,2, and 3, were opened. As it happened, the animal 

 when admitted to the reaction-chamber immediately chose box 



1. Having received the reward of food, he was called back to 

 D, and doors 8 and 9 having been raised in preparation for the 

 next trial, he was again admitted to the reaction-chamber. 

 This time he quickly chose box 9 and was confined therein for 

 thirty seconds. On being released, he chose after an interval of 

 four minutes, box 8, thus completing the trial. 



As it is highly important, not only in connection with the 

 present description of behavior, but also for subsequent com- 

 parison of the reactions of different types of organism in this 

 experiment, to present thg detailed records for each trial, tables 

 have been constructed which offer in brief space the essential 

 data for every trial in connection with a given problem. 



Table 1 contains the results for Skirrl in problem 1. It is 

 constructed as follows: the date of a series of trials appears in 

 the first vertical column ; the numbers (and number) of the trials 

 for the series or date appear in column 2 ; the following ten columns 

 present respectively the results of the trials for each of the ten 

 settings. Each number, in these results, designates a box en- 

 tered. At the extreme right of the table are three columns 

 which indicate, first, the number of trials in which the right box 

 was chosen first, column headed R; and second, the number of 

 trials in which at least one incorrect choice occurred, column 

 headed W. In the last column, the daily ratio of these first 

 choices appears. 



Taking the first line of table 1 below the explanatory headings, 

 we note on April 19 ten trials, numbered 1 to 10, were given to 

 Skirrl. In trial 1, with setting 1, he chose correctly the first 

 time, and the record is therefore simply 1. In trial 2, setting 



2, he incorrectly chose box 9, the first time. At his n£xt oppor- 



