26 JOSEPH U. Y ARE ROUGH 



mals once learn to respond to light they hold a more uniformly 

 high record than when responding to sound. On the basis of 

 the number of trials necessary to make the association it was 

 easier for the animals to associate light with sound than sound 

 with pain, when the two stimuli were presented continuously. 



2) One-second interval. The animals in Group IX made the 

 light-buzzer association over a one-second interval. They had 

 just transferred the negative response from pain to buzzer, and 

 the new problem called for this response to be transferred to 

 light, the latter being presented one second before the former. 

 When the animal turned to the light, the buzzer was not sounded. 

 Failure to respond negatively to light was recorded an error. 

 Table IX gives the data for this group. No special test trials 



TABLE IX 



Animal Trials % on Last 100 



37 1 60 94 



45 140 92 



46 140 94 



47 140 93 



Average 145 93.2 



were given, the results of the regular training series being suf- 

 ficient to show the rate of learning the association. The per- 

 centage is very low at the beginning of the learning period and 

 increases rapidly, giving a positive accelerating curve. When 

 compared with the learning curve for Group III, where all con- 

 ditions are the same except the stimuli, two marked differences 

 are found : i ) The percentage of correct response in the first 20 

 trials is considerably lower for Group IX; 2) no learning is 

 indicated by Group IX until after 40 trials, while learning appears 

 to have begun immediately with the other group. Under these 

 conditions, 145 trials were necessary to transfer the negative 

 response from the sound to the light. 



3) Two-second interval. To Group X the stimuli were pre- 

 sented with an interval of two seconds between them. The 

 animals dropped low in efficiency in the first series, but when 

 learning began the curve rose as rapidly as that for Group IX. 



