VISION IN THE MOUSE 



563 



number of errors made daily in twenty choices. Successive days 

 on which sets of choices were made are represented on the axis 

 of abscissas. The horizontal line at 10 may be regarded as the 

 line of no discrimination. 



( 'heck tests: To make sure that vision was being used by the 

 animals in discriminating, rather than smell, food was placed in 

 the blue-covered box and the red box was emptied. With mouse 

 no. 1 after the training for red of 400 trials, the result was, that, 

 in the first hundred choices, the mouse selected the empty red box 

 first 59 times in preference to the blue which contained the food. 



Keeping the food in the blue, the experiment was continued in 

 order to discover how rapidly an association of one color with food, 

 formed through training, could be changed to an association invol- 

 ving a preference for the previously avoided color. The dotted 

 curve of fig. 4 represents the result of 380 trials. It is an error 

 curve in which choices of red are considered ''wrong." 



With another mouse, B M, a series of experiments was made, 

 in which the check test consisted in changing the food into the blue 

 box for from three to five choices, after each ten choices with the 

 food in the red. This was done after 190 choices in training for 

 red had already been made. The results are given in the follow- 

 ing table. The first column gives the number of the test; the 

 second gives the number of right choices out of ten with the food 

 in red ; the last two columns give the results with the food trans- 

 ferred to the blue. 



