関係把握におけるSpence理論の検討

Abstract

Some experiments of transposition of size discrimination learning in human infants and rats were made to test whether the results were in accord with Spence's theory.In Exp. I, subjects were divided into two groups. Group I was, trained to the larger one of the two stimuli and Grgup II was trained to the smaller. Transposition tests were made in the positive direction, in the negative direction, and in the stimulus pairs which were made by combining the two stimuli which were located on both sides of the training stimuli.The results were compared with the conclusion deduced from Spence's theoretical generalization curves.1) In the group trained to the larger, both infants and rats showed high percentage of relative responses in every transposition test. From Spence's theory it was deduced that some absolute responses should be made in the tests of the positive direction. So the results did not strictly accord with this inference.2) In the group trained to the smaller both infants and rats showed very low percentage of relative responses in the tests of the positive direction. This accorded with the results of Spence's experiments in chimpanzees And with the inference from his theory. But, in the tests of stimulus pairs made by combining the two stimuli which were located on both sides of the training stimuli, infants showed chance score. Spence's theory is unable to account for this result.3) Since in infants, the low percentage of the relative responses is due to the increase of absolute responses, the consideration of these two types of responses will be sufficient. In animals, on the other hand, the position habit, which is a different type of response from the above two, should be taken into consideration. Spence's theory only predicts the low percentage of relative responses in general, hence it can not explain the difference of response-types depending upon the individual subject or species. In Exp. II, the proportion of areas of stimuli was increased and whether, in rats, the absolute response was made or not was examined.4) when subjects were trained to the larger of the stimuli they skowed very high percentage of relative responses. But, when they were trained to the smaller, most of all the animals showed the position habit. That is, in the transposition of size discrimination learning at least, rats do not make the absolute response, while the fact that infants make absolute response in such a situation is well known. Spence's theory can not explain the difference between these two species.It should be concluded that Spence's theory can not explain strictly the transposition behavior of infants and rats as dealt with in the present study. However, whether this is due to the intrinsic defect in his theory or can be settled by partial correction, is at issue in the present learning theory so that the writer would not attempt to draw any definite conclusion. As there are so many factors which affect the characteristics of his theoretical curves and which he did not consider, it is no wonder that Spence's theory is not applicable to any particular situation