232 



The Animal Mind 



85. Dropping off Useless Movements: the Puzzle-box 



Method 



The dropping off of useless movements is further illustrated 

 in those experiments where animals are required to work some 

 kind of mechanism. This may be called briefly the puzzle- 

 box method. It is obviously an advance in difficulty over the 

 labyrinth method in that it requires the formation of a new 



FIG. 1 6. Puzzle box used in Porter's work on birds. A B, one method of attach- 

 ing string to latch; C, a second method. In the first, the loop at B had to 

 be pulled; in the second, the string had to be pushed in. 



impulse rather than the mere guidance of an old one; it does 

 not merely direct the animal in the performance of something 

 that he would do anyway, but causes him to do something 

 that he otherwise would not do. Yet the distinction is not 

 so fundamental as it seems. 



The puzzle-box method has been tried with birds, rats, cats, 

 dogs, raccoons, and monkeys. Thorndike, its originator, 

 made some experiments of this type on chicks ; the animals 

 were confined in pens, from which they could be released by 



