FUNCTION OF VIBRISSAE IN BEHAVIOR OF WHITE RAT 61 



depended upon the contrast between the two experiences. This 

 is quite a different thing from the case where one contact ex- 

 perience became a stimulus to enter and another possessing no 

 such power was simply neglected. 



Ninth, in the end choice was clear-cut and direct, the animal 

 going from one to another pathway until he found the right 

 one and then confidently down and through. 



E. Records of Experiments of First Series— Nov. 27, 1910 to Feb. 8, 1911 



(a) Rats with vibrissae — -(3 males) : 



Average number of trials in learning, 165. 

 Average time of the last ten trials, 28.7 sec. 



(b) Rats without vibrissae — (4 males) : 



Average number of trials in learning, 195. 

 Average time of the last ten trials, 168.1 sec. 



(c) Anosmic rats: 



(i) Rats with vibrissae — (2 males) : 



Average number of trials in learning, 204. 



Average time of the last ten trials, 156.5 sec. 

 (2) Rats without vibrissae — (3 males) : 



Average number of trials in learning, 190. 



Average time of the last ten trials, 179.2 sec. 



F. Discussion of the Results of the Experiments of the First Series 



It will be seen by a comparison of these results that evidently 

 the vibrissae are an aid in the learning of such a problem. It 

 not only took the normal rat without vibrissae 30 trials longer 

 to learn the box but the average time taken per trial was five 

 times as long.. Vibrissae seem to be an aid in the discrimination 

 of inequalities of surface. It may be said that time and error 

 records do not show discrimination and this is true. But the 

 records help to establish and verify the observations of the 

 behavior reported. Of the discriminating act we will speak later. 



The anosmic rats were used simply as controls so that we might 

 be able to say that certain behavior was not due to the use of 

 the olfactory sense. The number of these animals was too small 

 to claim anything positively on the basis of their records. They 

 had been on the problem longer than the normal rats when the 

 electricity was introduced, and thus had 20 more trials to their 

 credit. In order to make the records comparable 20 should 



