Gestalt laws enhance the representation of figures over backgrounds in the visual cortex and influence contrast perception

The Gestalt laws of perceptual organization determine which image regions in a visual scene are perceived as figures or background. Convex, enclosed, and symmetric regions are more likely to be perceived as figures, but the underlying neural mechanisms are not well understood. Here, we studied the influence of Gestalt cues on visual perception and on neuronal activity in early visual cortex. We found that, in both humans and macaques, the perceived contrast of Gabor probes was generally higher when placed on Gestalt-defined figures than on background regions, although individuals differed. Neural activity in areas V1 and V4 of the visual cortex of monkeys performing a contrast discrimination task was higher for image elements belonging to Gestalt-defined figures than image-elements of the background, except for symmetry-defined figures. We observed this figure-background modulation in both V1 and V4 even when the distinction between figure and background was irrelevant for the task of the animal. The influence of Gestalt cues on neural activity was stronger in V4 than in V1, suggesting that Gestalt organization arises through modulation of neural activity in higher visual areas, which then modulates neural activity in early visual areas through feedback.