The Duration of Habits 



257 



each of these ten individuals a perfect white-black habit was 

 established by the use of the standard series of tests the order 

 of which is given in Table 12. At the expiration of a rest 

 interval of eight weeks precisely the same series of tests were 

 repeated as memory and re-training tests. In this repetition, 



\ 



FIGURE 32. Error curves plotted from the data given by ten dancers in white- 

 black discrimination tests. The solid line ( ) is the error curve of the origi- 

 nal learning process; the broken line ( ) is that of the re-learning process, 



after an interval of eight weeks. 



the preliminary series, A and B, served as memory tests, 

 and the subsequent training series, as re-training series. 



The striking results of this investigation of re-learning are 

 exhibited in the curves of learning and re-learning of Figure 

 32. These curves make it appear that the mice re-acquired 

 the white-black discrimination habit much more readily than 

 they had originally acquired it. But in addition to furnishing 

 the basis for some such statement as the foregoing, the curves 

 suggest a serious criticism of the experiment. 



In the original tests, the preliminary series indicated a 

 strong preference for black. In series A it was chosen on the 

 average 5.8 times in 10, and in series B, 5.7 times. This 

 preference was rapidly overcome by the training series, and 



