TRANSFER OF RESPONSE IN THE WHITE RAT 13 



uncovered excepting the heads of the alleys where the sound 

 and light stimuli were presented. The covered portions 

 are indicated in the figure by shading. 



(2) Method of Procedure, — The animals were first tamed 

 by being fed in the experiment boxes, by being handled 

 freely by the experimenters, and by being allowed free run 

 of the box until all emotional factors were removed as far as 

 possible. The regular day's work for any animal was a 

 series of twenty trials. However, when just beginning to 

 learn, the animal was given fewer trials and gradually 

 brought up to the full stint. 



The standard adopted in this series as indicating that the 

 animal had learned the problem was 95 correct responses 

 out of 100 chances. Since a daily series consisted of 20 

 trials, the standard required the completion of five successive 

 series of 20 trials each with not more than one error on the 

 average to each series of 20 trials. 



Normal records were secured first for the sake of com- 

 parision. These served to indicate how many trials and 

 series of trials were necessary for the average untrained 

 rat to learn the response to each of the various sorts of 

 stimuli used in the experiments. Then rats which had 

 learned to respond to one stimulus, say light, for example, 

 were required to learn the same response to another, sound, 

 for example. Then this ' sound ' record was compared with 

 the normal 'sound' record to see whether there was any 

 advantage or disadvantage in first learning the response to 

 the light stimulus. Also, in some cases, after the response to 

 one stimulus had been learned, this stimulus was presented 

 simultaneously with another sort to determine the effect 

 of simultaneity of presentation upon the learning of the 

 response to the second sort. 



In regard to 'controls,' the simple expedient was adopted 

 of omitting the stimulus and observing the effect upon the 

 behavior. The series of 20 trials in which the stimulus had 

 been omitted was compared with the series in which the 

 stimulus had been presented, and the effect of the presence 

 of the stimulus inferred from the comparision. 



Two sorts of stimuli were used in the positive series — light 

 and sound. The particular method of procedure with 



