LOCALIZATION OF SOUND IN THE WHITE RAT 297 



distance from the opened to the closed end or half way between 

 the open end and the fork. The intensity of the resulting sound 

 was approximately the same as that made by the pencil (6 1/2 

 gr. weight) when dropped from the height of three inches upon 

 the resonator at the same point used in the tapping. Here, 

 as in the giving of the stimulus, the resonator was held in the 

 hand. The intensity of the sound of the chisel was roughly 

 the same, while the intensity of the tapping on the stimulus 

 board with the lead pencil rubber was approximately equal to 

 that caused by dropping the pencil above used 'on the resonator 

 box from a height of one inch only. 



The interrupted tone on the organ pipe was given for com- 

 parison with the interrupted noise produced by tapping. The 

 stimulus from the fork and the hissing were comparable in that 

 both were continuous in character. To the experimenter, the 

 sound of the 256 d. v. fork seemed lower (undoubtedly due to 

 the absence of overtones) than the tapping upon the 256 d. v. 

 resonator box although both resounded to the Ut 3 Helmholtz 

 resonator. The former was also decidedly more characterless. 



B. Description of Method — The problem which the present 

 experiment set the rat was the establishment of an association 

 between the location of a sound (normally the tapping upon 

 the stimulus board) and food. The experiment fell into three 

 periods, which may be characterized as follows: (1) a period 

 in which the rat was fed inside the box in order to accustom him 

 to the apparatus and the experimenter; (2) a period of learning 

 the association between tapping and getting food at the point 

 of tapping; and (3) a control period in which the determining 

 cues for the behavior were sought. 



The procedure of each trial of the regular tests was as follows: 



(1) The position of the rat was noted at the moment of tapping. 

 This included the direction of his head in respect to the section 

 tapped as well as the absolute position of his body in the box. 



(2) The tapping signal was given on the stimulus board at 

 the middle of a certain section. This tapping was continued 

 until the rat stood up at some section on the side of the box. (3) 

 The path of the rat from his starting point to the standing up 

 point was noted. (4) Finally, the rat was fed at the section 

 tapped to which he had to come if he had incorrectly localized 

 elsewhere. No punishment was given if the rat did not react 



