1 82 The Dancing Mouse 



In passing I may emphasize the importance of the fact 

 that at no time did the brightness or color discrimination 

 tests furnish evidence of attempts on the part of the dancers 

 to choose by means of slight differences in the form of the 

 cardboards or the cardboard carriers. Several times form 

 differences, which were easily perceivable by the human sub- 

 ject, were introduced in order to discover whether the mice 

 would detect them and learn to discriminate thereby instead 



FIGURE 22. Cards used for tests of form discrimination. 



of by the visual conditions of brightness or color. As these 

 experiments failed to furnish evidences of form discrimina- 

 tion, the following special test in the discrimination box was 

 devised. 



The color discrimination box of Chapter X was arranged 

 so that the light at the entrance to each electric-box had a 

 value of 20 candle meters, less the diminution caused by a 

 piece of ground glass which was placed over the end of the 

 electric-boxes to diffuse the light. The windows through 

 which the light entered the electric-boxes were covered with 

 pieces of black cardboard ; in one of these cardboards I had 

 cut a circular opening 4 cm. in diameter, and in the other 

 an opening of the same area but markedly different shape. 



