112 CHARLES A. COBURN AND ROBERT M. YERKES 



to the number of mistakes. But at the same time, number 4, 

 just because of the lack of a definite inadequate reactive tendency, 

 happened upon the right compartment more frequently than 

 did number 3. For her, therefore, the ratio of correct to in- 

 correct choices is more favorable than for him. This is true 

 up to about the three hundredth trial, when it appears that 

 number 4 for some reason became more systematic in her work, 

 going most frequently to the first compartment at the left and 

 then to the second. This habit, which had appeared also in 

 the behavior of number 3, had by this time been replaced, and 

 as a result he was more often choosing correctly than she. Num- 

 ber 4 continued to exhibit this reactive tendency rather insis- 

 tently throughout the remaining trials. 



We must conclude from this analysis of the data of table 5 

 that both crows, in the five hundred trials with problem 2 

 which were given them, tried and found inadequate all of the 

 reactive tendencies which were immediately available. Toward 

 the end of the experiment, it was evident, especially in the case 

 of number 3, that the bird's only resource was to return to some 

 one of the methods previously employed. Strange as it may 

 seem to the human subject, and especially to those human 

 beings who have a high estimate of the intelligence and origi- 

 nality of the crow, these individuals proved entirely incapable 

 of learning to enter directly the second compartment from the 

 left in a series of compartments. 



Doubtless, many readers will object that longer training 

 would almost certainly have enabled our subjects to solve this 

 problem. We cannot deny this possibility, but we must insist 

 that all of the indications of our results are against it, for ordi- 

 narily the adequate solution of such a problem as this by an 

 animal of intelligence far lower than the human is achieved by 

 slow improvement. We are of the opinion that the crow is 

 incapable of perceiving and properly reacting to the relation 

 of second from the left, and we do not hesitate to admit that 

 we were very much surprised by this outcome of our experiments, 

 as we had fully expected our subjects, and especially crow number 

 3, to deal successfully with much more difficult problems than 

 this one. 



This opinion rests not solely upon the fact that no steady 

 and consistent improvement occurred as the result of five hundred 



