VISION IN THE MOUSE 



561 



1 All the white mice are albinos. 



2 The ages are approximate. An adult mouse is over 2 mont lis old. Age given 

 is age at the time experiment was begun. 



Marked individual differences in the animals made it possible 

 to get a much greater number of choices with some than with 

 others. The ease with which a motor habit may be formed makes 

 all the difference between a good subject and a poor one. Mouse 

 no. 1 early formed the habit of running directly to one of the tin 

 boxes, taking a piece of food (if he happened to select the box 

 which contained food) and running back with the morsel to box 

 N. He would be eating the last piece of food while I was changing 

 the boxes and switching the current to the other board. Thus he 

 saved me much time. He always made his full assignment of 

 twenty choices per day. Some of the other mice would follow 

 along the edge of the experiment box, pause a long time in the 

 corners and wash their faces, or they would take the food in such 

 a way as to give no satisfactor}^ evidence of choice. Throughout 

 these red-blue discrimination tests the food was kept in the red 

 box. At frequent intervals the papers were removed and fresh 

 ones pasted on, in order to obviate the influence of odor. The ex- 

 periment box was so adjusted with reference to the windows of 

 the room, that the two halves were equally illuminated. 



Results: The following table gives a summary of the results 

 of the red-blue discrimination tests: 



