236 



THE INTELLIGENCE OF MAMMALS 



led to adopt an extreme position which has not been justi- 

 fied by future experiments and which was not consistent 

 with many of his own results. Though extreme, the reac- 

 tion against the method of writers who based their deduc- 

 tions concerning animal intelligence on stories and casual 

 observations was none the less wholesome, as it succeeded 

 in stimulating the study of animal intelligence by more 

 careful and critical methods than those formerly employed. 



FIG. 15. Puzzle box used in the experiments of Thorndike on cats. 

 (After Thorndike.) 



In most of Thorndike's experiments boxes were employed 

 from which animals could escape by raising a lever, pulling 

 a cord, or by some such simple device. In some cases vari- 

 ous combinations of these devices were used. A hungry 

 cat or dog was confined in the box and food was placed on 

 the outside so that it could be seen. The animal in its 

 efforts to get out and obtain the food would usually begin 

 by biting and clawing the bars of the box. Sooner or later 

 a lucky movement would raise a lever or pull a cord so that 

 the door of the box would open and allow the animal to get 

 the food. After this the animal would be put into the box 



