等長平行線分の知覚についての実験的研究

Abstract

A number of different theories have been attempted concerning the filled-unfilled illusion. Obonai, for example, has denied previous theories based on perception of the intervening lines since he demonstrated the filled-unfilled illusion even when the interpolated lines were not seen. Among the important characteristics of the illusion, (1) the amount of illusion was found to increase and then decrease as the increase of the interpolatated lines, and (2) even though the filled distance is “overestimated”, the two end lines were found to be under the field force to be “underestimated”. In order to explain this apparent inconsistency, a “repelling force” was assumed. Related to this position are Obonai's “psycho-physiological induction”, Spiegel's “Z-Kraft”, and Wada's “diffusion-effect”.On the other hand, the same apparent inconsistent result may be explained by Yokose's theoretical formulas which deal with how two visual lines are perceptually displaced being influenced with each other. Further Yokose assumed the “enhancement of energy” which acts as a “repelling force” in the filled-unfilled illusion.The purpose of the present experiment is to test whether Yokose's formula can be applied to the perception of three parallel lines of identical size as one of the simplest cases of the filled-unfilled illusion. In addition, the experiment was designed to examine the relationship between the visual displacement of the two end lines and the amount of illusion in the filled-unfilled illusion.Main results are: (1) the finding concerning the visual displacement of each of the lines when the position of the middle line of the three parallel lines was experimentally altered, was very close to that predicted by the Yokose model, and (2) the amount of illusion increased and decreased as the increase of the number of intervening lines, and the two end lines of the filled lines were found to be under the force to be “underestimated ” as previously shown. However, the two phenomena were found to be closely related. It was concluded that the visual displacement of the lines is related to the formation of the filled-unfilled illusion.