12 K. S. LASHLEY AND L. E. WILEY 



counted as a complete trip from starting box to food box. 3 

 One trial was given on the first day and five trials per day 

 thereafter. After each trial the animal was allowed to eat a 

 bite of food. At the termination of each day's training it 

 was fed to repletion. 



A rigid control of the incentive cannot be employed with 

 operated animals, since those with larger lesions require con- 

 stant care and special feeding to keep them in good condi- 

 tion. We must therefore recognize the possibility of unequal 

 motivation in different animals. The only test of the ex- 

 istence of such differences that we have is the apparent eager- 

 ness of the animals for food, and on this basis the operated 

 animals must be judged more strongly motivated than 

 normals. There is significant evidence from other sources 

 that the differences between operated and normal animals 

 in learning cannot be ascribed to differences in motivation. 

 In two types of experiment (light-darkness discrimination, 

 Lashley, '29, and delayed alternation, Loucks, '31) the in- 

 feriority of operated animals has appeared only in post- 

 operative relearning, although the motivation used was always 

 the same. In studies employing the double platform 

 (Lashley, '20) the same incentive (hunger) was used as in 

 the maze studies with no evidence of inferiority on the part 

 of the operated animals. 



Criteria of learning 



With mazes I to IV training, after one trial on the first day, 

 was continued with 5 trials per day until the animal made a 

 record of 10 consecutive errorless runs, or for 150 trials (100 

 trials with maze V), in case the criterion of 10 errorless trials 

 was not reached earlier. Time and errors per trial and total 

 trials to reach the criterion were recorded. Of these, errors 

 are probably the most reliable criterion of progress in maze 



•It is not always possible to obtain a complete trial in one day because of 

 limitations of the experimenter's time. In such cases the animals were removed 

 from the maze, fed a limited amount, and returned to the maze on the following 

 day, the accumulated time and errors being counted as a single trial. 



