RATE OF LEARNING IN THE WHITE RAT 47 



tion of the terms is reversed. Under these conditions the con- 

 nection between the terms may be explained upon the same hypo- 

 thesis as in the experiments in the forward direction. For there 

 is no reason for the assumption that, since the animal has made 

 a certain motor response to the first term, the neural excitation 

 produced by this term suddenly ceases. On the contrary, if the 

 stimulus gets sufficient attention to call out this motor response 

 its neural effect might be expected to diminish more gradually 

 than when no reaction is made to it. The assumption is made 

 here that the "akoluthic" phase diminishes at a rate proportionate 

 to the intensity of the stimulus, which, of course, we have not 

 proved. Although our data are not conclusive on this point 

 they indicate greatly increased difficulty in learning the associa- 

 tion when the terms are presented in the backward order. This 

 increase in difficulty may be explained by factors of the situation 

 other than the "akoluthic" phase factors incident to the reversal 

 of the stimuli, i) The animal had previously been thoroughly 

 trained to turn when pain was presented. As this response was 

 learned it was easy to observe a change in his behavior from a 

 careless, random run to a slower movement which resembled 

 human behavior when in a state of expectancy. This method of 

 approach made him more responsive to any stimulus presented at 

 the time. He, therefore, readily transferred the response from 

 pain to sound when the buzzer was presented before the motor 

 response. If, however, the buzzer was presented after the motor 

 response had occurred this state of "expectancy" was absent, 

 and the transfer of response was more difficult. 2) The previous 

 training had taught the animals that when once turned they must 

 retrace the maze and select the opposite side in order to secure 

 food. Without exception this was true. Hence, after they 

 turned around for pain and started on a never-failing road to the 

 food-box, it was scarcely probable that they would proceed in 

 the same state of "expectancy" as before. Daily observations 

 showed that they did not. 3) One may assume that the two 

 terms were associated, but that it was more difficult for them to 

 function in the backward direction. The conditions for learning 



