MENTAL LIFE OF MONKEYS AND APES 31 



startled by the sound from one of the sliding bars under the 

 floor, and in the sixth trial he refused to work. 



As improvement was very slow, varied modes of rewarding 

 and punishing the animal were tried in the hope of discovering 

 a means of facilitating the work. Among the former are the 

 use of banana, grapes, peanuts, and other eagerly sought foods 

 in varying quantities, and in the latter are included periods of 

 confinement ranging from ten seconds to sixty seconds. In the 

 end, confinement of about thirty seconds, combined with a small 

 quantity of food' which was much to the monkey's taste, gave 

 most favorable results. 



All this time Skirrl's attention to the task in hand was seldom 

 good. He was easily diverted and even when extremely hungry, 

 often stopped work in the middle of an early trial, yawned re- 

 peatedly and finally sat down to wait for release from the ap- 

 paratus. 



The results obtained during the long continued trials with 

 this animal in problem 2 are presented in table 2, which differs 

 from the previously described table, first, in that several of the 

 trials are followed by an asterisk to indicate that aid was given 

 by the experimenter, and second, in that two additional columns, 

 headed, respectively, R and W, are presented. These give the 

 right and wrong first choices for each day, whereas the two 

 columns preceding them give the same data for each series of 

 ten trials. Similarly, the ratio of right to wrong choices is pre- 

 sented for each day in table 2, instead of for each series of ten 

 trials as in table 1. 



From the results of table 2, several peculiarly interesting 

 facts appear. In the first place the influence of the habit of 

 choosing the first box at the left disappears with surprising 

 suddenness, and in the second place, there are remarkable con- 

 trasts in the results for different settings as they appear in their 

 respective vertical columns. Thus, in the ,case of setting 1, 

 after the first trial mistakes became relatively infrequent, whereas 

 in setting 6, which involved the same number of doors, mistakes 

 continued to be the rule until nearly a thousand trials had been 

 given. The most likely explanation of this difference is that 

 for some reason the animal avoided box 9. 



The reactive tendencies, or better, the methods of reaction which 

 manifested themselves during this long series of observations 



