The Sense of Sight: Brightness Vision 107 



an animal acquires considerable familiarity with a situation 

 that it begins to vary its behavior in accordance with rela- 

 tively unimportant factors in the situation. It is this fact, 

 illustrations of which may be seen in human life, as well as 

 throughout the realm of animal behavior, that renders it im- 

 perative that an animal be thoroughly acquainted with the 

 apparatus for experimentation and with the experimenter 

 before regular experiments are begun. Any animal will do 

 things under most experimental conditions, but to discover 

 the nature and scope of its ability it is necessary to make 

 it thoroughly at home in the experimental situation. As 

 the dancer began to feel at home in the visual discrimination 

 apparatus it began to exercise its discriminating ability, the 

 first form of which was choice according to position. 



Since there appears to be a slight preference on the part 

 of most dancers for the black box in comparison with the 

 white box, white-black training tests were given to fifty mice, 

 and black-white to only four. The tests with each indi- 

 vidual were continued until it had chosen correctly in all of 

 the tests of three successive series (thirty tests). As the re- 

 production of all the record sheets of these experiments 

 would fill hundreds of pages and would provide most readers 

 with little more information than is obtainable from a simple 

 statement of the number of right and wrong choices, only 

 the brightness discrimination records of Tables 6 and 7 are 

 given in full. 



As a basis for the comparison of the results of* the white- 

 black tests with those of the black-white tests, two represent- 

 ative sets of data for each of these conditions of brightness 

 discrimination are presented (Tables 9 and 10). In these 

 tables only the number of right and wrong choices for each 

 series of ten tests appears. 



Tables 9 and 10 indicate if we grant that the precautionary 



