Role of Sight in Daily Life of Dancer 183 



These openings are shown in Figure 22. As the mouse ap- 

 proached the entrance to the electric-boxes, it was confronted 

 by these two equally illuminated areas, whose chief differ- 

 ence was one of form. Difference in the amount of light 

 within the boxes was excluded so far as possible. The ques- 

 tion which I asked was, can the dancer discriminate by 

 means of this difference in visual form? 



For the purpose of settling this point and of gaining ad- 

 ditional knowledge of the role of vision, two individuals were 

 tested in the discrimination box under the conditions which 

 have just been described. During the first ten days of the 

 experiment each of these mice, Nos. 420 and 425, was given 

 a series of ten tests daily. At the end of this period experi- 

 mentation with No. 425 had to be discontinued, and the 

 number of daily tests given to No. 420 was increased to 

 twenty. 



Instead of taking space for the presentation of the daily 

 records, I may state the general results of the tests. Neither 

 of the mice learned to choose the right box by means of form 

 discrimination. In fact, there was absolutely no sign of dis- 

 crimination at any time during the tests. This result is as 

 surprising as it is interesting. I could not at first believe 

 that the mice were unable to perceive the difference in the 

 lighted areas, but assumed that they were prevented from 

 getting the outlines of the areas by the blinding effect of the 

 light. However, decreasing the intensity of the illumination 

 did not alter the result. According to the indications of this 

 experiment, the dancer's ability to perceive visual form^is 

 extremely poor. 



Thus far the purpose of our experiments has been to ascer- 

 tain what the dancer is enabled to do by sight. Suppose we 

 now approach the problem of the role of this sense by try- 

 ing to find out what it can do without sight. 



