278 ADA \Y. YERKES 



with an average of 57.5 trials as against 69.5 trials for the 

 stock females. 



Consulting the time, distance and error curves for the short 

 maze (figures 2-4) we find the time records very high for the 

 inbred rats during the first five trials. In the first trial, in fact, 

 none of them finished the trip in the time allowed (900") and 

 one did not even in the third trial. Evidently because of tim- 

 idity they sat still most of the time allowed, making a low dis- 

 tance record for those trials. As they became accustomed to 

 the maze the time rapidly diminished, though remaining a little 

 higher than the stock records until the last few trials. The 

 distance, and correspondingly the error records, on the other 

 hand, increased after the first and are considerably higher than 

 for the stock rats. The inbred rats, therefore, apparently trav- 

 eled at a higher rate of speed when their timidity was once 

 overcome. The distance and error records for the inbred rats 

 also show greater irregularity from day to day. 



In both long and short mazes, the distance and error curves 

 for each set of rats are very similar, almost identical. Where 

 differences occur they may be due to the place where the error 

 occurs, i.e., in the long outer runways or the inner and shorter 

 ones. It will be noticed, however, that the disparity between 

 time and distance curves is very great, especially in the early 

 trials. 



In a discussion of the relative values of the different curves 

 of learning, Mrs. Hicks 8 refers to the distance curve as a nearly 

 ideal one but impracticable because of the difficulties of record- 

 ing the distance exactly. These difficulties have since been 

 overcome. Miss Hubbert 9 in her comparisons of time and 

 distance curves found them so similar in character " when 

 normal animals are tested that it is impossible to state which 

 is the better criterion of learning." In the present comparison 

 of behavior of stock and inbred rats, the time and distance 

 curves are not similar. If either time or distance were taken 

 alone, a true picture of the learning process would not be ob- 

 tained. The records of distance alone would make the inbred 

 rats appear the quicker, at first, in learning the correct path, 



8 Hicks, V. C. The relative values of the different curves in learning. Jour. 

 An. Behavior, 1911, 1, 138-156. 



Hubbert, H. B. Time versus distance in learning. Jour. An. Behavior, 1914, 

 4, 60-69. 



