246 F. M. GREGG AND C. A. McPHEETERS 



all premature responses. Fifteen days were necessary to incul- 

 cate this habit so that 80% of correctness was secured. (5), 

 In the final stage the negative series (R-R-R) was introduced 

 and two weeks was allowed to learn the discrimination between 

 the two series. At first the positive series was presented the 

 more frequently. As the learning progressed, the two series 

 were presented an equal number of times. The two series were 

 alternated in a definite complicated order. The number of 

 trials per day varied from 30-50 according, to the condition of 

 the animals. Typical records at the beginning and at the end 

 of the learning period are : — 



Jack Jill 



Trials Accuracy Trials Accuracy 



Positive series 27 89% 31 84% 



Negative series 14 29% 17 24% 



Positive series 19 95% 22 91% 



Negative series 20 0% 22 91% 



There was no discrimination at first. Both animals reacted to 

 the negative series almost as frequently as to the positive series. 

 Jack's training had simply perfected his reaction to any com- 

 pleted series. Further training might have developed discrimi- 

 native reactions in his case, but time did not permit a contin- 

 uance of the tests. Jill, on the other hand, easily mastered the 

 problem and discriminated between the two series on some 

 basis. 



Several peculiarities of behavior were evident during the 

 learning. (1), During the fourth stage, the animals began to 

 seek cues' from the experimenters. This was particularly true 

 of Jack. He seemed to watch the peep hole, although possibly 

 he was merely listening for some sound upon which to base 

 his reactions. The slightest rustle or movement on the part 

 of the operator was sufficient to initiate a response. This con- 

 duct was most evident during the interval between stimuli, or 

 immediately after the presentation of the third card. In order 

 to eliminate this extraneous cue, a metronome was kept beat- 

 ing at a rate of 80 vibrations per minute during the tests. This 

 noise was sufficient to render inaudible the slight sounds made 

 by the operator as we had no further difficulty from this source. 

 (2), The behavior which Cole emphasizes so strongly occurred 

 very frequently. The animal reacts prematurely, hesitates, 



