58 BRAINS OF RATS AND MEN 



salivatory path which is already activated, as well 

 as through its natural motor path to the spinal cord. 



This explanation, of course, applies only in cases 

 where the two stimuli are simultaneously acting, and 

 conditioned responses occur under many other cir- 

 cumstances. These cannot be reviewed here, and the 

 instance cited must be taken as illustrative of the 

 type of situation presented in conditioned responses 

 rather than as an adequate analysis of any of them. 



By the conditions of the experiment cited the 

 saHvatory reflex is a satisfying reaction; that is, it is 

 adaptive as defined by Carr (1925, p. 72) in that it 

 alters the situation in a way that satisfies the motivat- 

 ing conditions. It is part of the feeding reaction. The 

 head-turning reflex in some cases may also be adap- 

 tive, but under the conditions of this experiment it is 

 not satisfying; no significant motivating stimulus is 

 involved, for dogs do not naturally respond to dinner 

 bells. 



Upon many repetitions the salivatory reaction is 

 therefore perpetuated and strengthened by use and 

 the head-turning reaction, which has no "adaptive" 

 significance, is gradually eliminated. The salivatory 

 response is dominant over the head-turning response. 

 By simultaneous excitation of the gustatory and 

 auditory systems the satisfying or adaptive salivatory 

 reflex is facilitated, for the salivatory path from the 

 correlation center receives a part of its activating 

 energy from the auditory stimulus which is simultane- 



