60 STELLA BURNHAM VINCENT 



frequent choice of the right path with, however, no ' sensible 

 evidence of discrimination. 



Second, some rats found it exceedingly difficult to inhibit the 

 first impulse to run and for many trials had to be punished 

 before they would stop to discriminate, yet the first choice 

 after such punishment was almost invariably right. One normal 

 rat, a very active fellcw, never could get farther than this. He 

 was the only one of the 33 rats used that failed to learn the 

 problem with the exception of those with the nerve to nose 

 and vibrissae cut. 



Third, so far as anyone could see every sense the animal pos- 

 sessed was used in the box but at first in a very random and 

 exploratory way. Every bit of the box, every corner, side and 

 edge was "nosed" over and over again. From this activity, 

 thermal, tactual and olfactory experiences were obtained. There 

 was every opportunity to use the eyes so far as a limited 

 vision permitted. 



Fourth, there was great individuality in the way in which the 

 roughness of the surface was sensed. Some animals touched 

 the sides lightly with the vibrissae at the entrance or all the 

 way down as the case might be, some used noses in addition 

 to the vibrissae, and some pressed the whole body closely against 

 the walls of the passage as they ran. 



Fifth, positive preferences, repeated series and the effect of 

 the preceding right choice upon the succeeding ones were com- 

 mon observations with all. 



Sixth, it became more and more noticeable that the sense 

 experience described was being actively sought, more imme- 

 diately in connection with the plate, but also down the entire 

 passage and at^the entrance, and finally was carried back entirely 

 to the latter place. 



Seventh, with some individuals the roughness of the sides 

 became an immediate stimulus to enter a path whether this 

 right pathway was the first, second or third attempted. 



Eighth, others, e.g., rat "A," group (e), always tried at least 

 two pathways. If they reached the wTong alley first, they re- 

 jected it, and went on until they came to the right one; but if 

 they came to the right one first, after testing it, they went on 

 to another and then back to the right. There were several rats 

 of which this was true ; rats in which the discrimination evidently 



