Figural After-Effects in Stroboscopic Motion

Abstract

The present investigation is designed to determine whether figural after-effects of the type reported by Köhler and Wallach occur in stroboscopic motion following prolonged visual fixation of a stationary pattern. The lengths of the paths of two simultaneously presented spots in stroboscopic motion were adjusted so that they appeared equal to each of the 21 subjects. Each subject then fixated a satiation pattern for two minutes, after which he reported whether the paths, unchanged by the experimenter, were equal or not, and in which direction he observed a distortion, if any. The satiation pattern was so designed that a prediction of a distortion in one direction could be made in the subject's first judgment, while a slight change in the arrangement would yield a prediction of a distortion in just the opposite direction in the second judgment. The results are taken to support the finding Köhler and Wallach that the contours of a test pattern recede from the contours of the satiation pattern, even when the test pattern is a stroboscopic one.