The illusion of uniformity does not depend on low-level vision: evidence from sensory adaptation

Abstract

Visual experience appears richly detailed despite the poor resolution of the majority of the visual field, thanks to foveal-peripheral integration. The recently described Uniformity Illusion (UI), in which peripheral elements of a pattern seem to take on the properties of foveal elements, may shed light on this integration. We examined the basis of UI by generating adaptation to a pattern of Gabors suitable for producing UI on orientation. After removing the pattern, participants reported the tilt of a single peripheral Gabor. The tilt after-effect (TAE) followed the physical adapting orientation rather than the global orientation perceived under UI, even when the illusion had been reported for a long time. Conversely, a control experiment replacing illusory for physical uniformity for the same durations did produce an after-effect to the global orientation. Our results indicate that the UI is not associated with changes in sensory encoding, but likely depends on high-level processes.