102 The Dancing Mouse 



was given a series of ten tests in succession daily. The ex- 

 periment was conducted as follows. A dancer was placed in 

 A, where it usually ran about restlessly until it happened to 

 find its way into B. Having discovered that the swing door 

 at / could be pushed open, the animal seemed to take satis- 

 faction in passing through into B as soon as it had been 

 placed in or had returned to A. In B, choice of two en- 

 trances, one of which was brighter than the other, was forced 

 by the animal's need of space for free movement. If the 

 right box happened to be chosen, the mouse returned to A 

 and was ready for another test ; if it entered the wrong box, 

 the electric shock was given, and it was compelled to retreat 

 from the box and enter the other one instead. In the early 

 tests with an individual, a series sometimes covered from 

 twenty to thirty minutes ; in later tests, provided the condi- 

 tion of discrimination was favorable, it did not occupy more 

 than ten minutes. 



To exhibit the methods of keeping the records of these 

 experiments and certain features of the results, two sample 

 record sheets are reproduced below. The first of these 

 sheets, Table 6, represents the results given by No. 5, a 

 female, 1 in her first series of white-black tests. Table 7 

 presents the results of the eleventh series of tests given to 

 the same individual. 



In the descriptions of the various visual experiments of 

 this and the following chapters, the first word of the couplet 

 which describes the condition of the experiment, for example, 

 white-black, always designates the visual condition which the 

 animal was to choose, the second that which it was to avoid 

 on penalty of an electric shock. In the case of Tables 6 and 

 7, for example, white cardboard was placed in one box, 



1 It is to be remembered that the even numbers always designate males ; 

 the odd numbers, females. 



