290 The Animal Mind 



even repeatedly, the performances of a cat that knew how 

 to get out (704). With monkeys, Thorndike's most ex- 

 tensive tests were made to find whether the animal would 

 learn to open a box from seeing the experimenter himself 

 do it, and his results were again, on the whole, negative 

 (708). Small's white rats also showed no ability to profit 

 by each other's experience in this way. One of each of the 

 pairs first experimented on solved the problems presented ; 

 the other, instead of either attacking them for itself or learn- 

 ing by watching the successful one, contented itself with 

 stealing the food secured by the latter (685). Imitation, 

 according to Yerkes, plays no considerable role in the 

 learning processes of the dancing mouse (820). Where 

 an animal is not at all helped to the solution of a problem 

 by watching another animal solve it, we are justified in 

 concluding that if it can recall memory ideas at all, it does 

 not make use of them in a situation where a human being 

 would certainly do so. 



The lack of ability on an animal's part to postpone reacting 

 to a stimulus is another evidence of inability to make use 

 of memory ideas. The very ingenious method by which 

 such ability may be studied was the device of Hunter 

 (350). It has been termed the Delayed Reaction Method, 

 and its general plan is as follows. A light is shown for 

 a few seconds in any one of three directions from the 

 animal, which is restrained from reacting. After the light 

 is turned off and a certain time interval has elapsed, the 

 animal is released, and if it goes in the direction in which 

 the light appeared, it receives food. Now white rats could 

 succeed in running in the proper direction when the delay 

 between the disappearance of the light and their release 

 was not more than ten seconds, but only in case they 

 pointed their noses at the light when it appeared and 



