134 FLETCHER, COWAN AND ARLITT 



Normal No. 14's percentage of correct choices during the last 

 ten trials was 100; alcohol No. 37's was 30. Normal No. 18 

 and alcohol No. 30 were each given 75 trials. During the last 

 ten trials the normal chick's record was 100% correct choices 

 and the alcohol's record was 50% correct choices. Normal No. 

 15 and alcohol No. 34 w T ere each given 67 trials. The normal 

 chick made a record of only 70% correct choices during the 

 last ten trials whereas the alcohol chick made a record of 100%. 

 The alcohol chicks plainly formed the association more slowly 

 than did the normal chicks and there were alcohol chicks which 

 seemed unable to form the association in the time at our dis- 

 posal for training them. But as in the experiment with the 

 mazes there were individuals among the alcohols which did as 

 well as normal chicks and there were normal chicks which did 

 as badly as the alcohol chicks. 



INHIBITION OF AN INSTINCTIVE REACTION 



The apparatus used in this experiment was a large square 

 of dark grey paper over which was placed a pane of glass the 

 exact dimensions of the paper. On the paper under the glass 

 were scattered bits of egg yolk. Ten chicks of the fourth hatch- 

 ing, five normal and five alcohol, w r ere used in this experiment. 

 The group of normal chicks was placed on the glass for five 

 minutes each day and the total number of pecks of all five 

 chicks was recorded. The chicks were then replaced in the 

 box and the same procedure repeated with the group of alco- 

 hols. These tests were repeated for twenty-five days. There 

 was no appreciable difference in the behavior of the two groups. 

 The alcohol chicks learned to inhibit the reaction with approx- 

 imately the same rapidity as the normal chicks. 



The following table gives the number of pecks each group 

 made on each of the trial days. 



TABLE 11 



Day 



1 2 3 4 5 6 7 8 9 10 11 12 13 



No. of pecks made by 

 normal chicks 4662121000122 



No. of pecks made by 



alcohol chicks 4661301040001 



