26 HARRY H. WYLIE 



experimenter behind the screen would rattle the seeds in the 

 dish at the head of the open return alley. Punishment was 

 given for wrong choice. Rat number 52 in group VII was 

 given 280 trials under such conditions. The record by 

 series runs: 60, 80, 75, 65, 50, 75, 70, 65, 55, 70, 75, 50, 75, 

 65. Since no signs of improvement were appearing the 

 work was dropped. 



Because of the above considerations the conviction was 

 reached that the failure to learn the positive response to the 

 sound stimulus was not due to the animals' being negative 

 to the sounds presented. 



The fourth possible explanation for the failure that sug- 

 gested itself was that the rat could not localize the sounds 

 well enough under the circumstances to enable it to guide its 

 responses by them. This does not mean that the rat can 

 not localize sounds, but that, if it can, the conditions under 

 which the experiments were conducted were not suited to 

 call localization into play. When the experiments began it 

 was assumed that the rat could localize sufficiently well 

 under the conditions presented to enable it to guide its 

 response by the sound after a certain period of training. 



The records for Groups VI and VII contain some signi- 

 ficant things that require some comment and explanation. 

 It will be recalled that pain for a wrong choice was given in 

 these two groups. The records show that Numbers 42, 46, 

 47, 48, and 50 gave considerable evidence that they were 

 actually learning the response. The fact is. Numbers 42, 

 47 and 50 actually met the standard required, that is, 95 

 correct responses out of 100 chances. Why was it that 

 these records were not accepted as indicating that those 

 animals had learned the sound? The fact was that their 

 general behavior did not indicate definitely enough that 

 they were actually responding to the sound stimuli when 

 they were making enough correct responses to come close 

 to meeting the standard required. The experimenter 

 became convinced that some other factor was present in 

 these cases as the determining factor. To make plain the 

 basis for this conviction let us notice again the method of 

 procedure. The keys which closed the circuit containing 

 the induction coil and controlled the electric current used 



