154 STELLA B. VINCENT 



and total accuracy which is greater than normal although the 

 final accuracy, when the trail is in the cul de sacs, is less. The 

 learning time is also shortened. We should therefore say that 

 such an olfactory control distinctly favors accuracy. 



How shall we explain this increased accuracy ? Was it a 

 result of real sensory discrimination ? It can be explained, as 

 the results in the black-white maze were explained, as being 

 due to the dominance of some particular stimulus. A path, 

 out upon which an animal first runs in a maze, if not alarming, 

 becomes a familiar place — a home place. There may afterward 

 be other such places in the maze, but this is the first one. He 

 runs out from here, returns, goes a little farther, etc., but always 

 with the possibility of the home return. In Experiment 1, the 

 path was associated with a strong odor trail. Departure from 

 this was to go into the unfamiliar and strange. Thus from the 

 first the animal had more of this stimulus and it became in- 

 creasingly familiar and increasingly dominant. Dominance, as 

 a term here, may be explained in one way as the power of the 

 familiar. It may have other explanations. Rats are seemingly 

 possessed with an instinctive curiosity or tendency to explore; 

 but fighting against this is an innate tendency to keep in familiar 

 or known situations. The familiar or known situation in Exper- 

 iment 1, was near the odor trail; in Experiment II, it was away 

 from it. If we accept this view the odor stimulus would be 

 powerful enough to keep an animal in the true path if it arose 

 from this path or to keep it from the blind alleys if it lay there. 

 It would work both ways. It w r ould do so by holding the atten- 

 tion to the true path or by catching the attention and so serving 

 as a warning when the animal strayed from the path. The 

 errors would be lessened in either case. 



There were actions, however, which seemed to show that 

 this behavior was more than a mere passive affair. I take it 

 that an instant response to a stimulus, w T hen not instinctive, — 

 a response which can be learned and which can be varied, now 

 positively and now negatively — involves discrimination. There 

 was none of this seen in the black-white maze. There was 

 such behavior here. If this be the case, while the first explanation 

 may be a true and a reasonable one, the increased accuracy 

 here was partly, at least, a result of discriminative ability. 



There was an increase of errors in the middle of the learning 



