HABIT FORMATION IN THE ALBINO RAT 45 



sidered in relation to time, the older rats appear much less active 

 than the younger ones, as is shown by the average high speed 

 attained by the young in comparison with the old. Certainly 

 the behavior of the old animals when in the maze is much more 

 deliberate than that of the young ones, and the writer believes 

 that if Slonaker had possessed some means of measuring the 

 amount of activity per unit of time he would have found the 

 young far more active than the old. 



In Table VIII is given the average speed for each group, 

 for the first, second and tenth trials, the two trials immediately 

 preceding the last six, and the last six trials. The increase 

 of speed from the first to the second trial is considerable except 

 in the two hundred day group where there is a decided decrease. 

 The gain from the second to the tenth trial is great except for 

 the three hundred day group where it is comparatively small. 

 From the tenth trial to the two preceding the last six the gain 

 for the two hundred and three hundred day groups is greater 

 than for the twenty-five or sixty-five day groups, and from 

 these two trials to the last six trials the gain is again greater 

 for the three hundred day rats. This gives a slight indication 

 as to where the most rapid learning occurs. A full set of tables 

 showing the speed for every trial of each group would be neces- 

 sary for an adequate discussion of the question, but from the 

 present incomplete data it appears that the learning in the 

 two younger groups is most rapid during the early stages, while 

 for the older groups it is more rapid during the later trials. 

 Especially is this true of the three hundred day group, the 

 increase in speed being very gradual during the first ten trials 

 then more than doubling from the tenth to the two immediately 

 preceding the last six. In general, speed, for the separate trials 

 tabulated, decreased with age, which accords with our obser- 

 vation on the average speed for each group during the entire 

 period of formation of the maze habit. 



TABLE VIII 



SPEED CENTIMETERS PER SECOND 



Two 



First Second Tenth preceding Last 

 Age trial trial trial last six six 



25 days 7.8 9.8 52.0 74.2 90.0 



65 7.2 11.1 35.0 52.0 75.0 



200 u 8.3 4.7 21.0 40.7 56.2 



300 u 3.0 4.2 9.5 20.8 40.9 



