INSTINCTS AND HABITS IN CHICKS 



35 



3rd day, swallowing improves rapidly, striking improves 

 slightly, and seizing suffers a reversal of form. 



In other words, from the beginning of the second day the accu- 

 racy of striking improves uninterruptedly, the accuracy of swal- 

 lowing declines temporarily on the second day, and that of 

 seizing temporarily on the third day. It is evident that the 

 rate of improvement of reaction 4 depends upon the rate of 

 decrease of the total number of errors in these reaction types. 

 In neither Group E nor Group F was improvement in all three 

 types of reaction uninterrupted. The retardation of reaction 

 4 on the third day is due specifically to a decline in the accuracy 

 of seizing on that day. 



7r/a/a 



Oey9 1 2 



9 10 11 12 U 14 15 16 17 18 19 20 21 22 23 24 2S 



Figure 6 — Curves showing the rate of improvement in pecking accuracy of two 

 chicks kept in isolation. Distances along axis of abscissae represent days; 

 distances along axis of ordinates, the number of perfect reactions]^in the daily 

 series of pecking reactions. 



In regard to the tests for social influence, the objection can 

 be made that social influence,, if it affect the accuracy of reaction 

 at all, may work as well betw^een members of the same group 

 as between members of different groups. The objection has 

 force. As a control test, chicks nos. 75, 80, and 81 were kept in 

 individual apartments and tested. The results are exhibited in 

 fig. 6. The record of no. 80 is omitted because valueless. This 

 chick soon became physically unfit. No. 75, although it did 

 not thrive under the conditions, made a good pecking record. 

 No. 81 not only pecked with unusual accuracy but was lively 

 and vigorous after the first few da^^s. The curves do not 

 furnish convincing evidence in support of the view that social 



