30 FREDERICK S. BREED 



them. On this same date, when the individuals of Group D 

 were eight days old, they had an efficiency of 16.5. Very little 

 change occurred in the accuracy of pecking of Group D after 

 the commingling, nor indeed could a heightening of their curve 

 after the eighth day be well expected, for they had by that 

 time practically attained the maximum. 



Nothing very conclusive having accrued here, it was deemed 

 desirable to arrange a test so that younger chicks could be 

 enclosed with older ones immediately after hatching. Thus, it 

 was thought, the influence might be measured, if the effect of 

 social influence be such as to affect the rate of improvement of 

 the pecking reaction. The most active opponents of inferential, 

 ideational, or voluntary imitation seem agreed that the presence 

 of one animal, under the proper conditions, may have the effect 

 of stimulating another of its kind to greater activity. There is 

 no difficulty whatever in establishing this fact. My observations 

 have proved it to my satisfaction many times. It may be that 

 the change in the mode of functioning of the organism due to 

 the presence of others is in the direction of increasing the inten- 

 sity and rapidity of the reactions, 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. But 

 such a speculation does no more for us than open up wider 

 vistas of experimental research in which exact quantitative 

 studies can no doubt be made. 



Mention has previously been made of the rapidity with which 

 reaction 4 improves. The curves all show very rapid improve- 

 ment on the second day. To make a special measurement of 

 the rate of this change, the pecking of six chicks in Group C 

 was tested twice on the second day. The first record was taken 

 from 10-12 a. m. and the second from 2-4 p. m. In the interim 

 the chicks were committed to the brooder and allowed the 

 freedom of the litter of the cage for the first time. From fore- 

 noon to afternoon, v^ithin the limits just stated, the improve- 

 ment was 82%, assuming, as we have, that the development of 

 reaction 4 is an index of the improvement of the chicks' peck- 

 ing efficiency. ■ ■■ 



The sudden drop in Curve IV-C, fig. 13, 'on the fifth day is 

 due mostly to the unusually poor records of no. 57 and no. 58 



