548 



STUDIES Oisr THE MENTAL LIFE OF ANIMALS. 



of food for some time — twenty-four hours, for example — the animal 

 which was to be the subject of the experiment; then lie shut it in a cage 

 having- a grating front; near by, on the outside, food for the animal 

 was placed. The door of the cage, set into the grating, was moyed 

 by a mechanism which the animal had to operate in order to get out; 

 once free, he could satisfy his hunger. In general, the animal was 

 put into the box through a hole either in the back oi* the top. This 

 hole was then covered over by a board. The door in th(> various 

 cages could be opened either by a latch, a button, In' pulling a cord, 

 or by stepping on a platform. Sometimes it was fastened b}- two or 

 three means, which had to l)e operated l)y the animal ])efore its release 

 was effected. When our author used chickens he sometimes modified 

 his pi'ocedure. In place of having to open a door, the sul)ject was 

 placed in a small inclosure and had to surmount successively a certain 

 luunber of obstacles — walk up steps, for example — to find its food 



and companions. 

 The basis of the 

 principle remains 

 the same; the ani- 

 mal has, in all cases, 

 to form an associa- 

 tion between the 

 representation of 

 the interior of the 

 box presented by 

 his senses and the 

 series of movements 

 which release it, 

 hunger being the 



Fi<;. 1.— General model of a box (Box K). eX('itant. 



After the animal was shut up, its conduct was carefully observed. 

 A dou})le precaution was taken: first, to note if the subject of the 

 experiment had or had not previously been subjected to the same or 

 some similar experience; finally, which was quite easy with the 

 arrangements adopted, to })e quite sure that the animal was free from 

 any influence of the observer; the ''personal equation" connected 

 with the latter being entirely eliminated. It was only manifest in the 

 theoretical interpretation of the experiment. The animal's behavior 

 was quite independent of any factors save its own hunger, the mechan- 

 ism of the box it was in, the food outside, and such general matters as 

 fatigue, indisposition, etc. Animals in doubtful health were not con- 

 sidered. In order to be sure as to the psychological motive involved, 

 the author, in the case of dogs and cats, did not experiment with them 

 until they were in a uniform state of absolute hunger. As a general 

 rule, if the animal placed in the cage did not, after a certain time, 



