AUDITORY SENSITIVITY OF THE WHITE RAT 



315 



harmonized a priori with such an hypothesis. As soon as a 

 rat had chosen the proper pathway, the end-stop on that side 

 was quickly and noiselessly removed 'so that by the time the 

 rat reached the alley on the side of the box a free exit was offered 

 him. 3, no end-stops; no punishment; no chord sounded. 

 Reactions right when they fit the series of presentations. If 

 the rat chose wrongly, he was confronted by an open pathway 

 to the food. In this control, even the punishment due to a 

 blocked pathway was removed. This and the following control 

 were used to test the role" of kinaesthetic factors or position 

 habits. Control 3 sought the character of these habits when 

 uninfluenced by punishment. 4, conditions the same as in con- 

 trol 3, save that the electric shock was used when errors occurred 

 A quick interposition of the end-stop prevented the animal 

 from reaching, food when it chose the wrong alley. It was 

 thought that the introduction of such punishments might lead 

 to changes in the position habit as revealed in control 3. 5, no 

 end-stops; everything else normal (as in standard learning series.) 

 The results attending the introduction of the controls are 



Nature 



of 



test 



TABLE 3 



Number Rats 



of 



trials 31 32 



Con. 1 20 



Normal 20 



Con. 1 20 



Con. 2 20 



Con. 3 30 



Normal 20 



Con. 1 20 



Con. 2 20 



Con. 2 30 



Con. 3 20 



Normal 40 



Con. 1 10 



Con. 4 20 



Con. 1 20 



Con. 2 40 



Normal 50 



Con. 1 30 



Normal 50 



Con. 5 10 



Con. 3 20 



Con. 1 30 



Normal 60 



Con. 2.... 20 



Records are given in their chronological 

 in per cents. Rat 37 was not tested. 



65% 



70% 



75% 

 50% 



70% 



45% 



72% 



65% 

 65% 

 65% 

 60% 



60% 



65% 



40% 

 60% 



38 



oo7 

 60% 

 65% 



53% 



60% 



46% 



40% o 



52% 

 68% 

 63% 

 74% 

 80% 

 65% 

 66% 

 70% 

 60% 

 order. Correct responses are given 



