10 



JOHN LINCK ULRICH 



The averages for each trial for all rats, both males and females, 

 are given in Table I. These averages show that there is in 

 succeeding trials a gradual decrease in time for each trial while 

 learning is in progress. This decrease, when plotted in a curve, 

 indicates the progressive steps in learning. Curve I, of the 

 latch box, gives the individual curves of the one, three and five 

 trial groups. 



CURVE I 



LATCH BOX 



ONE TRIAL 



THREETRlAuS 



IZ TRiAl_S 



Before attempting any analysis of these curves, it is well, 

 at this stage, to describe the structure of all the curves of this 

 kind. A division of each individual curve was found necessary 

 because of the great length of all of the curves, and it was also 

 desirable to indicate the daily variations in time for the solu- 

 tion of the problem toward the end of the learning period. To 

 do this, the first part of the curves was constructed in tenths of 

 a minute and the latter part of the curve in thousandths of a 

 minute. All the curves were plotted in the same manner. The 



