"Seeing" shapes that are almost totally occluded: A new look at Parks's camel

Abstract

When a shape moves behind a very narrow window, or "slit," the entire shape can be recognized, although at any instant only meaningless fragments are visible. In some manner, the human visual system has the ability to piece together these sequential fragments into a coherent shape that is seen as moving across the largely occluded field. As a first step toward understanding how this feat may be accomplished, we show some minimal conditions for recovering the direction and speed of motion of an unknown shape moving behind a slit. Two important conditions are that the object be rigid and that its motion be a simple transition in the image plane. © 1986 Psychonomic Society, Inc.