The Dancing Mouse 



ably has markedly different effects upon the retinal elements 

 of the eyes of unlike organisms. In a study of the sense 



of sight it is 

 extremely impor- 

 tant to discover 

 whether difference 

 in the quality, as 

 well as in the in- 

 tensity, of a visual 

 stimulus influ- 

 ences the organ- 

 ism; in other 

 words, whether 

 color sensitive- 

 ness, as well as 

 brightness sensi- 

 tiveness, is pres- 

 ent. If the dancer 

 perceives only 

 brightness or lu- 

 minosity, and not 

 color, it is evident 

 that its visual 

 world is strikingly 

 different from 

 that of the normal 

 human being. 

 The experiments now to be described were planned to show 

 what the facts really are. 



As a means of testing the ability of the dancer to distin- 

 guish differences in brightness, the experiment box repre- 

 sented by Figures 14 and 15 was devised. Figure 14 is the 

 box as seen from the position of the experimenter during the 



FIGURE 14. Discrimination box. W, electric-box 

 with white cardboards; B, electric-box with black card- 

 boards. Drawn by Mr. C. H. Toll. 



