The aperture capture illusion: Misperceived forms in dynamic occlusion displays

Abstract

Visual illusions can reveal unconscious representations and processes at work in perception. Here we report a robust illusion that involves the misperception of moving, partially occluded objects. When a dynamically occluded object is seen through 2 misaligned apertures, the object appears misaligned in the direction of the apertures, creating the Aperture Capture Illusion. Specifically, when part of a dynamically occluded object disappears behind an occluding surface and then another part of the object comes into view immediately afterward, the 2 parts appear misaligned in the direction of the offset of the apertures through which they were seen. This illusion can be nulled: Separating the 2 object parts to increase the time interval between their appearance produced the percept of alignment. The ability to null the illusion in this manner demonstrates that dynamically occluded regions of moving objects continue to persist in perceptual awareness but, we argue, are perceived to move at a slower velocity than visible regions. We report 7 experiments establishing the existence of the illusion and ruling out several classes of explanation for it. We interpret the illusion and the ability to nullify it within the context of Palmer, Kellman, and Shipley's (2006) theory of spatiotemporal object formation.