308 ALDA GRACE BARBER 



A and then hesitated when the heavier tapping was begun 

 hh 



(A), stood up at point of hesitation (4), turned towards the 

 heavier intensity, and responded accurately to this (D13). 

 Barber was at H29. The error, which was noted in respect 

 to the first standing up and not in terms of the final decision 

 was 7. From these results it is apparent that the first taps do 

 not determine essentially the final reaction. The table further 

 makes it clear that the rats went to the loud sound although 

 headed toward the faint one. This is important when viewed 

 in the light of the curve in fig. 3 which shows that the rats tended 

 to go in the direction they were pointing. 



A test further questioning the effect of the first few taps 

 was given in control XI in which alternate tapping was made 

 the stimulus. Hunter tapped once heavily, and then Barber 

 tapped once less heavily, etc. The results show that as a whole 

 the rats chose the stimuli indifferently. However, in two cases 

 (No. 20 and No. 23) reactions to the heavier tapping predom- 

 inated. No evidence was obtained that the first tap determined 

 the point finally localized. A conclusive test of the influence 

 of the first taps was given by control XII. In this the operator 

 tapped only three times and then stopped, not continuing until 

 the rat stood up as in the standard tests. Little of interest 

 is shown in the results as tabled; however, the experiment was 

 of importance for the observations made of the rats' reactions. 

 The rats started as usual for the right point, but then showed 

 great hesitancy and confusion when the stimulus stopped. 

 Usually, however, the impetus gotten at first was great enough 

 to secure a fair accuracy of response. The indications plainly 

 were that the determination of the general direction of the stim- 

 ulus was a matter of the first taps, while the accuracy of response 

 was dependent upon the continued tapping. Evidently the rat 

 utilized the whole stimulus in making his normal reaction. 



Involved necessarily in this question of relative intensity is 

 the problem of the binaural ratio. In control IX, double stim- 

 ulus of two intensities, the rat was sideways to each of the 

 operators at the beginning of the stimulus, but after the first 

 movement, conditions were changed. Thus, no definite state- 

 ment can be made in respect to the binaural factor as a cue 

 throughout the control. A very careful effort was made to 



