KINAESTHETIC PROCESSES IN THE WHITE RAT 3 



Table 1 indicates the number of trials required by each rat to 

 master the series of alternate runs. The criterion of mastery was 

 an average of 87.5 per cent correct for four days, with no day's 

 record below 80 per cent. The data indicate that the simple 

 alternation habit is acquired in from one to eighteen days, under 

 the conditions of the present experiment. No explanation in 

 terms of external causes is available for the great variation hi 

 ability displayed by the animals. 



After the mastery of the problem, the end-stop was no longer 

 used. No confusion of the animals' responses was .produced. 

 Undoubtedly the stimulus for turning in one direction, let us say 

 to the left, was the complex of kinaesthetic, organic, cutaneous, 



TABLE 1 

 Number of trials prior to mastery of simple alternation 



and olfactory processes involved in a run through the opposite 

 side of the box and terminating in the securing of food. 



Problem 2. The acquisition of a habit of double alternation. 

 Using the same apparatus as before, with punishment and reward, 

 tests were made upon the ability of rats to master a double 

 alternation, llrrllrrll. After the preliminary acquaintance with 

 the apparatus, the rat was inserted with the end-stop in such a 

 position as to force it through the left side of the apparatus. It 

 was then fed and re-inserted and forced to come through the same 

 side of the apparatus in order to escape. The next two trials 

 were through the right side of the box. 



To the great surprise of the experimenter, this apparently sim- 

 ple problem was never mastered by any one of nineteen rats who 

 were tested on it under various conditions. The details of 



