356 K. S. LASHLEY 



It seemed advisable to use some conditions of training which 

 have been tested already in complicated mazes, and of these the 

 use of practice periods of diverse length was selected as a condition 

 whose general results are well established and whose details are 

 capable of wide variation. 



Twenty-five rats were trained in the simple maze with 10 trials 

 per day and 24 with 2 trials per day. Entering the cul de sac or 

 turning back along the true path was counted as an error and ten 

 successive trials without error were required as a criterion of 

 learning. The general precautions to secure uniformity in the 

 groups compared were those which I have described in an earlief 

 study of the circular maze (Lashley, '17b). The conditions or 

 feeding were varied somewhat within the groups: details of this 

 will be considered in the second part of this paper. 



The average number of trials required for learning by the ani- 

 mals having 2 trials per day was 21.5 0.81. The average 

 number for the animals having 10 trials per day was 57.8 4.70. 

 The difference is 36.3 4.76 trials in favor of the group practicing 

 with fewer trials per day; a saving of about 60 per cent as a result 

 of the distributed practice. This result is in accord with the 

 data obtained by Ulrich ('15) in his study with the circular maze 

 and indicates that the simple maze is as well adapted to bring 

 out group differences of this character as is the more complicated 

 apparatus. 



When the animals had learned the maze they were used in 

 operative experiments. Portions of the cerebral cortex were 

 destroyed and retention of the maze habit was tested after the 

 operation. In this type of work also the simple maze proved 

 useful (Lashley and Franz, ; 17). 



With respect to the time consumed in training, the simple maze 

 offers a great advantage over the more complicated apparatus. 

 The average time consumed by each of the 49 animals in actual 

 practice in the maze was 7.4 minutes. The average time required 

 in practice by a group of 32 normal animals trained previously in 

 the circular maze was 47.1 minutes. That is, more than six 

 times as much time must be spent in training animals in the cir- 

 cular maze as in the simple maze, yet the results of the former 

 method are in no way more reliable than those of the latter. 



