INSTINCTS AND HABITS IN CHICKS 77 



ponents separately, was measured. Records were taken up to 

 the twenty-fifth day. The pecking improved in accuracy very 

 rapidly during the first two days, reaching by the beginning of 

 the third day an efificiency numerically represented by 29.29 

 on a scale of 50; by the beginning of the eleventh day an effi- 

 ciency of 40.10 was attained; and during the rest of the period 

 of measurement the degree of accuracy ran no higher than 

 42.57. The improvement was retarded more by errors in seiz- 

 ing than by errors in swallowing, and more by errors in swal- 

 lowing than by errors in striking. After the third day the 

 imperfection of seizure remained greater than that of the other 

 two reactions combined. The striking reaction, seldom widely 

 erroneous, improved rapidly and without relapse, closely approx- 

 imating perfection by the fifth day, — a degree of accuracy that 

 might easily have inspired belief in the perfection of the peck- 

 ing instinct. 



It did not appear that the effect of social influence was such 

 as to increase the rate of improvement in accuracy of the peck- 

 ing reaction. It may be that the change in the mode of func- 

 tioning of the organism due to the presence of others was in 

 the direction of increasing the intensity and rapidity of the re- 

 actions, without increasing their rate of improvement in accuracy. 

 Such a variation would have selective value, inasmuch as the 

 animal would get more food in a given time, even though the 

 pecking were no more accurate. 



The important exception to the general rule for brightness 

 training, namely, that when the color which the chick was 

 trained to avoid was presented in combination with a color 

 other than that used in the original training, the chick con- 

 tinued its specific avoiding reaction regardless of the relative 

 brightness values of the stimuli, demands, I believe, that color 

 quality as well as intensity be assumed as a determining factor 

 in the reactions of the chicks. 



The chicks, without much doubt, responded selectively to 

 one of two objects of different size. 



The results of the form tests reported were purely nega- 

 tive. 



There was no conclusive evidence that previous formation of 

 the black-blue habit facilitated the formation of the small-large 

 habit. 



