560 



STUDIES UN THE MENTAL LIFE OF ANIMALS. 



the entrance hole is removed. The oat w ill .still continue to open the 

 door, but if at any time she happens to notice the hole she nia^y make 

 use of it occasionally, but not invariably.' An instance of the second 

 sort is that of a chick placed in a cage, A, separated by a wire screen 

 from a box, D, in which were other chickens and food. After picking 

 and scratching at the screen, the subject finally jumps to B, and, after 

 a similar process, to C, then reaching D. After seventy -five or eighty 

 trials the wire screen is removed. The chicken could now at will 

 descend from A to D, or from B to D, or from C to D. Now, this 

 singular phenomenon appears: He goes to the edge of A, looks' down 

 upon his comrades, but does not jump down into D, although nothing- 

 prevents him, and then goes into B, where he does the same. Finally, 

 in spite of the removal of the screen, the chicken traverses the long 

 route A, B,' C, D. The instinct has been truly inhibited. The author 

 observed but one case in which, after the wire was removed, the chicken, 



after looking over nine times to see his 

 comrades, decided, after seven minutes, 

 to jvunp directlv into D. 



J) 



VIII. 



Fiii. iL'.— Inhibition of instincts liy 

 habit ( chickens). 



We can now^ attempt to make an out- 

 line of the conception of the psycholog- 

 ical life of animals as derived from these 

 investigations. 



That life is, take it altogethei', rather meager. The animal is not 

 endowed with reason; the faculties of comparison and conception of 

 similarity are wanting. He lacks ideas and tendencies which would, 

 as a whole, constitute an original and free intellectual life: he has no 

 nuMuory of the past in the sense of a superior faculty by which he can 

 recall at will i)sych()logical states that have disappeared, for the pur- 

 pose of com})aring or contrasting them with present states. The phe- 

 nomena of association that constitute his mental life, while presenting 

 a certain analogy with some human associations, remain very different 

 from what they are in man. 



The animal lacks entirely the power not only of correlating ideas 

 independent of a corporeal attitude and determinate exterior condi- 

 tions, but also of varying, of cond)ining associations originally formed 

 undei- external influences. We should not, however, conclude from 

 these investigations that the three species of animals here experimented 

 with necessarily represent the totality of animals. It is especially 

 notable that Mr. Thorndike has been unable to investigate monkeys. 

 A similar study of these animals is much to be desired. 



The experiments here cited may at least aid us in establishing a 

 criteriiun of the difference between animal and human intelligence. 

 According t(^ a widespread opinion, held especially l)y Mr. C. L. 



