AUDITORY SENSITIVITY OF THE WHITE RAT 313 



tests that are described in the earlier account. For the sake 

 of clearness, it may be well to describe these again. Figure 1 

 is the T shaped discrimination box. The rat was expected to 

 associate a turning to the left in order to secure food placed at 

 F with one stimulus, and the opposite turning with another 

 stimulus. The forks and whistles of the present tests were 

 mounted above x. Other stimuli were given just back of the 

 discrimination box where the experimenter stood. In the present 

 work, the release box was not used. The animal was placed 

 in the door at F after the stimulus had been started. Punish- 

 ment and reward were used with all the rats. Unless otherwise 

 stated in this paper, the following series of presentations (10 

 trials daily) were used: 



lrllrrrllr The present tests were carried out during the quietest 

 rlllrrlrrl part of the day under practically ideal conditions so 

 llrrllrrlr far as extraneous noises were concerned. 



rllrrrlllr 



EXPERIMENTAL RESULTS 



I 

 Four young untrained rats were tested with the tuning fork 

 896 d.v. In order to respond correctly in the present test, the 

 rat should turn through the right pathway when the fork was 

 sounded and through the left pathway when the fork was not 

 sounded. 700 trials (70 days) were given; but the rats not 

 only failed to learn the association, they never improved essen- 

 tially during the tests. Table 1 gives the number of correct 

 reactions out of each succeeding fifty of the 700 trials. 



Trials 



50. 

 100. 

 150. 

 200. 

 250. 

 300. 

 350. 

 400. 

 450. 

 500. 

 550. 

 600. 

 650. 

 700. 



