RATE OF LEARNING IN THE WHITE RAT 29 



appear. First, the breakdown in the beginning of the learning 

 period is more marked in the latter. A percentage of 45 was 

 made in this group, while in Group V an efficiency of 62 per 

 cent was maintained. Second, the learning curve rises much 

 more rapidly for Group XL The percentage of increase rose from 

 45 to 95 m f ur series of trials, while in Group V the increase 

 for the corresponding period was from 67 to 74 per cent. Seven 

 days were required for Group XI to reach the 90 per cent mark 

 of correct response. Previous training is an explanatory factor, 

 but indications are that this difference is largely due to difference 

 in the stimuli used. The data thus far gathered indicate that, 

 other things being equal, it is more difficult for white rats of the 

 type used in these experiments to associate sound with pain than 

 light with sound. 



5) Six-second Interval. Group XII learned the association 

 when light was presented six seconds before sound. In Table 

 XII is given the data for this group. The association over this 

 time interval required more trials than did that for any other 

 group, but the difference is not great enough to be of significance. 

 The curve in Fig. 7 will assist in showing the rate of learning. 

 In form it follows rather closely the curve for Group XI low 

 at first, followed by a period of rapid learning. 



TABLE XII 



Animal Trials % on Last 100 



i 160 91 



10 200 94 



11 180 92 



12 180 95 



Average 180 92.5 



The effect of stimulus difference is shown by comparing this 

 curve with that of Group VI. The curve for the former group 

 begins somewhat higher, and instead of rising higher it first 

 tends downward and later ascends, gradually reaching the 90 

 per cent mark after 180 trials; the curve for the latter exhibits a 

 very brief period of no learning, followed by very rapid progress. 



Summary : To enable the reader to see at a glance the results 



