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 $ , 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 9 . 

 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 9 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 11525 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 bassethound-Saluki F 2 , 929 $ , 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 t\vo widely 



