The Duration of Habits 253 



that only the first test of the memory series would be of value 

 as an indication of the existence of a previously acquired 

 habit. Even under the conditions of no shock and no stop 

 or hindrance the first test of each memory series is of pre- 

 eminent importance, for the mouse tends to persist in choos- 

 ing either the side or the visual condition (sometimes one, 

 sometimes the other) which it chooses in the first test. If 

 the wrong box is chosen to begin with, mistakes are likely to 

 continue because of the lack of punishment ; in this case the 

 animal discriminates, but there is no evidence that it re- 

 members the right box. Likewise, if the right electric-box 

 is chosen in the first test, correct choices may continue 

 simply because the animal has discovered that it can safely 

 enter that particular box; again, the animal discriminates 

 without depending necessarily upon its earlier experience. I 

 have occasionally observed a series of ten correct choices, 

 made on the basis of an accidental right start, followed by 

 another series in which almost every choice was wrong, be- 

 cause the animal happened to start wrong. 



As the results of my tests of memory are of such a nature 

 that they cannot advantageously be averaged, I have arranged 

 in Table 48 a number of typical measurements of the duration 

 of visual discrimination habits. In this table I have indi- 

 cated the number and age of the individual tested, the habit 

 of discrimination which had been acquired, the length of 

 the rest interval, the result of the first test (right or wrong), 

 and the number of errors made in each series of ten memory 

 tests. 



This quantitative study of the duration of simple habits of 

 choice showed that in the majority of cases a perfectly ac- 

 quired habit persists for at least two weeks'. To be perfectly 

 fair to the animal I must restrict this statement to visual 

 conditions other than colors, for the dancer exhibited little 



