552 



KARL T. WAUGH 



mouse would enter the experiment box and make a choice of X or 

 Y, and after receiving a morsel of food or a shock, as the case 

 might be, it would run or be driven back into box N. The boxes 

 X and Y would then be interchanged and the current switched into 

 the wires on the other side. When all was in readiness, a door 

 between N and the main box was raised and the mouse was per- 

 mitted to seek the food again. 



It was considered a choice if the mouse touched the edge of 

 either food-box. If he approached the wrong side first and received 

 a shock and then ran over to the other side to get food, it was 

 recorded as a wrong choice and the animal was forced to return 

 to box N before making the next choice. Twenty trials were made 

 each day with each mouse, and each choice was recorded as right 

 or wrong according as the mouse obtained the food or the shock 

 on first running out. 



Results: The following tables give the number of trials and 

 the number of right and wrong choices: 



Experiment (a) Black and white. 



Black and white papers were pasted on the food-boxes. 



Experiment (6) Light and dark varieties of a color. 



Idght mul dark violet papers were substituted for the black mid whitt . 



( 'heck Experiment: In order to make sure that the animals 

 were using the visual sense in discriminating one paper from 



