1248 



HORMONAL REGULATION OF BEHAVIOR 



4 5- 



40 



35- 





25 



a. 20- 



5- 



14 



NORMAL CONTROLS 



INJECTED CONTROLS 



ASSEMBLED 31st DAY 



^ X ASSEMBLED 41st DAY 



ASSEMBLED 51st DAY 



42/45 



53 /55 



I 

 28 



35 



42 



— I — 

 49 



56 



DAYS OF AGE 



Fig. 20.2. The total number of peck-rights established at various ages among males reared 

 as a group and others reared in partial isolation and assembled at different ages. The isolated 

 chicks and one group, reared together, were injected with an androgen (Guhl, 1958). 



in a certain sequence; sexual behavior usu- 

 ally follows agonistic behavior. However, 

 the typical behavior of this group was 

 sexual. Attempts to mount were frequent 

 and the birds showed strong avoiding re- 

 actions. The indications were that at this 

 age there was a conflict between aggressive 

 behavior and the newly developed sexual 

 behavior, which had not yet been sub- 

 jected to any adjustment. The group as- 

 sembled on day 51 showed both aggressive 

 and sexual behavior, but with somewhat 

 better adjustment to the conflicting drives. 

 Untreated females (not shown in Fig. 20.2) 

 assembled from isolation did not show this 

 complication, because sexual behavior pat- 



terns appear much later in the female. The 

 significant point is that hormonal treat- 

 ment may shorten the time between the 

 appearance of sequential behavior patterns 

 to the point where psychologic adjustments 

 cannot be made and an imbalance of drives 

 occurs. Endogenous hormones rise more 

 slowly in concentration and allow more 

 time for experience, or learning the adaptive 

 process. In large groups the variability of 

 individuals in development is also a com- 

 plicating factor. 



In the same series of experiments an at- 

 tempt was made to demonstrate the in- 

 fluence of social inertia on the development 

 of social behavior bv normal male chicks. 



