TRANSFER OF RESPONSE IN THE WHITE RAT 55 



three false returns out of 500 trials. The number of false 

 returns recorded run from none to four per animal. Since 

 they were so few no record was kept except for a part of 

 the animals used. It must be noted, however, that prac- 

 tically all of the false returns were made after the animal 

 had learned the response to one stimulus and had been 

 transferred to the other. Practically all of them also are 

 to be found in the records where sound was the stimulus 

 being used. Some of the false returns can be accounted 

 for by extraneous sounds from outside the laboratory. 

 These false returns, to the writer's mind, indicate that the 

 response had become considerable of a reflex and any sort 

 of stimulus of a kind similar to the one which had become 

 effective was sufficient to set it off rather than a matter 

 of habitual turning at a particular place in the alley or at 

 a particular position in the series of trials; in other words, 

 the response had become generalized for stimuli of that sort. 

 Another thing which indicates that the response had 

 become generalized for all stimuli of the sound type which 

 could be " sensed " by the animal is the record of Group 

 VIII with the bell and the pipes. As indicated by the record 

 no great decrease in ability to respond was produced by 

 substituting these two sorts of stimuli for the regular sound 

 stimulus. The tests with the bell and the pipes were given 

 as preliminary tests of the rat's ability to hear tones. Elec- 

 trically driven tuning forks were also tried, but it was 

 found to be impossible to control the sound of the tuning 

 forks sufficiently well to suit the type of reaction required 

 or already learned by the animal. After being trained on 

 the light and the regular sound, the animal's reaction took 

 place so rapidly that a mere click of the sounder was suf- 

 ficient to stop the headlong course of the animal and cause 

 it to turn back into the other alley. After placing the animal 

 in the main alley, so quick was the choice that time was 

 scarcely to be had to press the key and give the sound as 

 a warning to turn back. In the case of the tuning forks 

 the time required to get the fork vibrating with sufficient 

 ntensity to make a plainly audible tone (for the human 

 ear) was so long that the animal had made the complete 

 run up the main alley and down one of the return alleys 

 before the fork had begun to give out such a tone. So the 



