LOCALIZATION OF SOUND IN THE WHITE RAT 299 



which eliminated kinaesthetic, olfactory and visual cues. Then, 

 since the association still persisted, an effort was made to discover 

 the auditory factors determining the accuracy of localization. 



Several difficulties arise under the present plan of experi- 

 mentation: (1) the rat, although alert and eager to respond, 

 has to inhibit its own movements; (2) the tendency is to go in 

 the direction headed (see fig. 3, below p. 303) ; (3) a reflex recoil 

 is manifest at unwonted, unexpected noises; (4) flightiness or 

 unstable attention is present; and (5) no punishment was given 

 for incorrect responses, a condition which probably lessened 

 accuracy and quickness of learning. These factors are all of 

 importance in differentiating animal work from that done on 

 humans. In addition one should note the difference in recording 

 judgments in rats and humans, for the latter have only to indicate 

 the point localized or to respond according to a familiarized 

 chart, while the former have actually to go to the correct section. 



EXPERIMENTAL SECTION 



A. The learning of the association — The first question, i. e., 

 whether the rat could localize the noise, was quickly answered, 

 for an accuracy which was not improved in degree throughout 

 the later part of the experiment was obtained within from 40 

 to 136 trials, i. e., in from 5 to 17 days. Table 1 shows the 

 number of trials necessary for each rat to reach the standard 

 reaction, which was considered achieved when the rat did not 

 vary markedly in response for several days. 



TABLE 1 



Rat 6 20 4 21 22 23 



No. trials on learning 136 40 136 64 48 48 



An interesting observation in connection with this table is 

 that rats 6, 4 and 21 were males, while rats 20, 22 and 23 were 

 females. This difference in trials on learning may be due to 

 chance, or to the fact that rats No. 6 and No. 4 were older 

 than the others. 



Records of the average daily error for rats No. 21, No. 22, 

 and No. 23, for the first 15 days are in Table II. 



