590 W. T. JAMES 



98 signals the dog- gave either a series of flexions and 

 extensions of the foreleg, a pumping reaction, or failed 

 to respond at all. Animal 1504 9 , next to 251 i , gave only 

 eight continued avoiding responses in 100 signals. These two 

 animals are low response types. In contrast to these, note 

 the high response value of the German shepherd, 1285 $ . 

 This animal made a definite continued avoiding movement to 

 every signal presented. Another excitable dog of group B, 

 Saluki 835 9 , responded to 97 of the 100 signals. 



Intermediate groups A-plus and B-minus. Table 7 and 

 text-figure 104 record the findings for the intermediate groups. 

 These dogs gave a more balanced performance than either 

 of the polar groups. They did not become hyper-excitable 

 nor completely irresponsive, and, as a rule, formed a condi- 

 tioned avoiding reaction. The frequency of the reaction varied, 

 however ; some gave a high ratio of responses to one rein- 

 forcement, and others gave a lower excitatory-inhibitory ratio. 

 For example, for 100 positive signals, animal 1152 $ gave 

 eighty reactions and failed to respond to twenty. Animal 

 246 2 responded to forty-four and failed to respond to fifty- 

 six. In the latter case, one reinforcement is about equal to 

 one avoiding reaction, while in 1152 5 the "effect" of the 

 reinforcement is much greater. 



Just as in the salivary reaction, these dogs were considered 

 the best types for these experimental purposes, especially 

 those of the B-minus group, in which the positive was formed 

 and occurred regularly, and in which a negative reaction 

 also could be developed. By contrasting food with one signal, 

 and shock with another, one animal, 1152 $ , was able to dif- 

 ferentiate between a clicker rate of 96 and one of 120 vibra- 

 tions per minute. Text-figure 102 (fig. 2) shows one of the 

 differential responses. By contrasting right and left leg- 

 reactions, a bassethouncl-Saluki F 2 , 929 5, formed a differ- 

 entiation between 60 and 120 vibrations per minute. 



Summary and discussion. In the motor reflex experiments, 

 as in the salivary, twenty-three dogs were trained, and here, 

 as in the previous experiments, the dogs gave two widely 



