PHENOMENAL CAUSALITY - IMPRESSIONS OF PULLING IN THE VISUAL-PERCEPTION OF OBJECTS IN MOTION

Subjects observed computer-generated images of five opaque rectangles arranged in a vertical column and separated by small gaps. In order fr om top to bottom, the rectangles began to move horizontally at interva ls of a fraction of a second, at constant and identical speeds. Subjec ts reported a strong impression that the top object was pulling the ot hers, despite the fact that the objects never came into contact or app roached each other, moved in different planes, and had no visible conn ection. The impression was not much affected by speed, direction of mo tion, or length of delay between successive objects beginning to move. The effect was attenuated if there was prior motion in the opposite d irection, if each object in turn rapidly decelerated to a standstill, and if all objects began to move simultaneously. It is unlikely that t his impression could be mediated by an innate visual mechanism, and it may reflect perceptual learning.