Habit Formation : Discrimination Method 233 



at the same time I am glad that I chose that series of shifts 

 in the position of the cardboards which, as it happens, served 

 to exhibit an important aspect of quantitative measures of 

 the modinability of behavior that otherwise would not have 

 been revealed. Our mistakes in method often teach us more 

 than our successes. I have taken pains, therefore, to describe 



A B I % 3 4 6 67 8 & 1O ,11 18 13 14 



FIGURE 30. Error curve plotted from the data given by thirty dancers, of 

 different ages and under different conditions of training, in white-black discrim- 

 ination tests. 



the unsatisfactory as well as the satisfactory steps in my study 

 of the dancer. 



The form of the white-black discrimination curve of Figure 

 29 is more surprising than disappointing to me, for I had 

 anticipated many more irregularities than appear. What 

 I had expected, as the result of training five or even ten pairs 

 of mice, was the kind of curve which is presented, for con- 

 trast with the one already discussed, in Figure 30. This 

 also is an error curve, but, unlike the previous one, it is based 

 upon results which were got from individuals of different 

 ages which were trained according to the following different 

 methods. Ten of these individuals were given two or five 

 tests daily, ten were given ten tests daily, and ten were given 



