THE ASSOCIATION CENTERS 245 



beyond their reach. But the stick and the banana 

 must both lie within the field of view or the stick will 

 not be used. If the stick is so placed that the ape can- 

 not see it and the fruit at the same time the stick is 

 ignored. The ape may turn away from the side of the 

 cage which faces toward the fruit, see the stick, even 

 handle it, but he does not associate it with getting the 

 banana unless the stick is so placed that the fruit is 

 visible also. Older and more experienced animals were 

 advanced far beyond this simple stage of inventive- 

 ness, and would sometimes stop in the midst of a long 

 series of fruitless trials to obtain an objective, hold an 

 attitude of indecision, and then suddenly dart away 

 for a ladder or some other tool which was quite out 

 of sight at the time. 



The young chimpanzee's use of a stick which is in 

 plain view as a tool to secure a banana is typical of 

 what Lloyd Morgan in 1894 called "intelligence" as 

 distinguished from "reasoning" and what Hobhouse 

 in 1915 called "practical judgments" and what Carr 

 (1925) calls "perceptual-motor learning." This type 

 of behavior probably makes up a large part of the 

 conduct of many men. This is probably what Hunter 

 means by "sensory thought," as distinguished, on the 

 one hand, from the unconscious or obscurely con- 

 scious learning process through gradual acquisition of 

 a physiological habit by trial-and-error, and, on the 

 other hand, from reasoning processes involving sym- 

 bols, ideas, concepts, or other abstractions. 



