18 



K. S. LASHLEY AND L. E. WILEY 



constant direction where the experimenter has definite pre- 

 conceptions. We have tried to control such influences of the 

 personal equation as follows. The recording of errors was 

 automatic, leaving no room for personal judgment. The 

 training was done, as far as possible, in ignorance of the 

 character of the operation to which the animal had been 

 subjected, although such ignorance can be only partial, since 

 it is impossible to mistake an animal with extensive cerebral 

 lesion. In all cases the lesions were reconstructed and the re- 

 constructions checked without knowledge of the experimental 

 records of the animals. 



TABLE 3 

 Correlations between the scores of the same animals in learning two mazes 



NUMBER 



CASES 



TOTAL ERRORS 



LESS FIRST 



TRIAL 



TOTAL TRIALS 



TOTAL TRIALS 



LESS CORRECT 



RUNS 



TOTAL TIME 



LESS FIRST 



RUN 



Operated animals 



VALIDITY OF THE MAZE TECHNIQUE 



The consistency of performance of the animals and the 

 validity of the methods can best be tested by a comparison 

 of the scores made in different mazes. The scores by the 

 various criteria for the same animals on the two mazes in 

 which each was trained have been correlated and the results 

 are shown in table 3. Except for time, the correlations 

 obtained from normal animals are low. There is a tendency 

 for them to increase in magnitude with increase in the number 

 of culs de sac in the mazes, which suggests that we increase 

 the reliability of maze studies by increasing the complexity 



