SOME RESULTS OF TRAINING A WHITE MOUSE 



An albino mouse was used in these practice experi- 

 ments. The conditions were as follows: 



A drop-bridge apparatus was used which consisted of a 

 disc of pasteboard mounted on an inverted glass tumbler, on 

 the top of which the animal could walk about but from 

 which he could not descend. There was a hinged bridge which 

 could be propped up out of reach of the animal but which 

 might be lowered by pulling a string which passed above the 

 disc. The string was attached at one end to a fixed rod and 

 at the other to the prop which held up the bridge. The prop 

 was made in the form of a toggle joint, the system being 

 barely in equilibrium. This made necessary only a slight 

 pull on the string in order to cause the bridge to descend, and 

 the position of the prop was so adjusted as to require just 

 slightly more than a chance touch on the string to bring about 

 the fall. 



When the bridge had descended it formed part of an 

 incline which led to the ground, where food was provided. 

 There were two motives which might lead the animal to come 

 down from the disc; the presence of the food below, and the 

 restlessness or general diffusion of energy which caused the 

 animal to move about. 



At the first few trials, the mouse tried to descend by 

 climbing down the sides of the tumbler, but he found this 

 impossible. As a result of his random movements he finally 

 (after 165 seconds) pulled the string and the bridge fell into 

 place. To this he paid no attention, apparently not realizing 

 that it led to the ground. Twice, before he at last managed 

 to climb down the bridge, he ventured along it a few steps 

 but returned to the disc on top of the tumbler. 



The most rapid practice results were seen in the habit 

 of descending the bridge after it had been dropped, the 

 habit of pulling the string being slowly and never perfectly 

 learned, that is, the mouse always combined the characteristic 

 climbing-down movement with the string pulling. He would 

 get his nose over the string and then lean over the edge of 



NINETEEN] 



