AUDITORY SENSITIVITY OF THE 'WHITE RAT 343 



the American Psychological Association (2), when a verbal 

 report of the present finding was made. 



The apparatus used was the T-shaped discrimination box of 

 the earlier experiments, figured above. A hole about 1 inch in 

 diameter was cut in the box at the point marked in the figure. 

 Outside of the apparatus and directly in front of this hole was 

 placed a 10 candle power light enclosed in a covered box. This 

 light could be turned off and on as desired. The hole in the box 

 was closed with a square of clear glass over which a layer of bond 

 typewriter paper was placed. The result was a diffused light of 

 good intensity (somewhat less than 10 candle power) . 



The first rats used were rats 46 and 47 of the 1915 paper. 

 These rats were about six months old at the time of the present 

 observations. They had been trained to discriminate a piston 

 whistle tone of 3906.17 d.v. from silence by running to the right 

 when the tone was given and to the left for silence. Controls 

 had been used which indicated that the rats would substitute for 

 the whistle either: "rush of air" sound made by the whistle with- 

 out the tone; a "rush of air" sound made with the experimenter's 

 lips; or handclapping of medium intensity. In other words, the 

 rat would run to the right when either of the above stimuli were 

 given, and to the left for silence. On the other hand when the 

 following tonal stimuli were substituted for the whistle the rat 

 failed to discriminate them from silence: one 1280 d.v. fork; a 

 1152 d.v. and a 1280 d.v. fork sounding simultaneously; and the 

 normal whistle when it was removed to a distance, thus eliminat- 

 ing the usual noise accompaniment. Transfer was therefore 

 possible without training from one noise (that of the whistle) to 

 various others; but not possible from the noise in question to 

 tonal stimuli. 



It was at this point that the suggestion derived from Wylie's 

 work was applied. The rat was placed in the apparatus and 

 stimulated with a light in place of the whistle in order to see if 

 a transfer would be made between the two sense fields in spite of 

 the fact that the previous transfer within the auditory sense field 

 had not occurred. The results for the two animals are given in 

 table 2. The rats were given the regular whistle test in a dark 



