GENETIC TYPE AND THE ENDOCRINES 593 



head and body movements are correlated with the leg reaction, 

 indicating a wider involvement of neural processes and the 

 inability to limit excitation to the one significant reflex system. 

 The intermediates fall between the two extremes, the A-plus 

 group showing less involvement of these centers as the ex- 

 periments progress than the B-minus group. This again 

 emphasizes the difference in degree of excitation and the 

 involvement of correlated reflex systems. 



One characteristic of the motor response places it in direct 

 contrast to the salivary reflex. If food is always delayed 

 for 30 seconds during the presentation of the signal, all 

 dogs except the extremely excitable tend to delay the con- 

 ditioned reaction. Pavlov calls this inhibition of delay. In 

 the motor response, this did not occur even when the signal 

 preceded reinforcement for 5 seconds in every case. The 

 salivary and motor reactions are directly opposite in nature. 

 The food taking performance involves a basic approach ad- 

 justment to a pleasant situation, while the motor defensive 

 response is basically a withdrawal from a dangerous and 

 painful object. Since the two systems involve different 

 physiological backgrounds, and are directed toward different 

 physiological adjustments, the laws of excitation and inhibi- 

 tion determining their action are not similar. The rules of 

 conditioning refer not only to physiological drives, but to 

 the external situation, and this should be taken into con- 

 sideration in the interpretation of behavior. 



Another factor of importance in the motor experiment, and 

 one which shows the significance of the situational aspect, 

 is generalization. In our experiments, all dogs forming the 

 continued avoiding response had a tendency to give this 

 response to every signal introduced. This was especially 

 true for the highly active animals of group B. In a previous 

 report (James, '33) the greater tendency of the dogs to 

 generalize in the motor situation than in the salivary was 

 emphasized, and the difficulty in forming differential reac- 

 tions pointed out. In that report we suggested the possibility 

 that dogs may make closer differentiations in situations in- 



