IX. INDIVIDUAL DIFFEEENCES AND METHODS OF 

 HABIT FORMATION 



WE may now take up in more detail a study of the records made 

 by a few of the animals that show typical or exceptional types of 

 behavior, and also discuss the observations made on the methods of 

 habit fixation. In Figs. 6 and 7 are given samples of practise curves 

 for several mice, showing the daily records in each group of trials, in 

 the order that they were given. The arrows at the highest points on 

 the curve indicate that the mouse did not pass through the maze or 

 multiple choice test within 360 seconds. 



In Fig. 6 are given the daily record curves for two agouti mice, 

 131 Ag. J* and 132 Ag. $. Their average time records are given in 

 Table VI. They are mice from a single litter and their records show, 

 in both cases, very rapid and consistent learning in the maze test, 

 remarkably slight interference effect at the eighteenth trial, followed 

 by a complete recovery and very speedy time records from the twen- 

 ty-first to the twenty-ninth trial. No. 131, whose record is indicated 

 by the solid line, made a record in all the tasks which was consider- 

 ably better than the average. It showed a very strong retention for 

 the maze test, while the records in the multiple choice test, although 

 very good, show a more irregular performance than in the maze test. 

 This irregularity of performance in the multiple choice test appears 

 typical for the mice that have been tested in this investigation, and 

 the irregularity may be due to the factors peculiar to the test itself, 

 or, as previously discussed, to interference effects from previous 

 training. No. 132, whose record is indicated in Fig. 6 by a broken 

 line, failed to get through the multiple choice test for the first five 

 days; succeeding on the sixth day, it made fairly good records there- 

 after. These two mice were taken as examples, because they typify 

 the characteristic manner in which good time records were made by 

 the mice that were tested in these experiments. The writer refers 

 to the method of learning by rhythm of movements, which also has 

 been noted by Watson, Basset and others for white rats. It was 

 noted, for instance, that mouse 132 Ag $, in the initial learning 

 period in the maze test, never went to the closed gate in the first com- 

 partment after the first two days of training. For a week of learn- 

 ing, from the fourth trial to the tenth inclusive, this mouse passed 

 the first open gate successfully, but instead of going on to the open 

 gate in the second compartment, the animal invariably made a detour 



35 



