Abstract
In conventional accounts of figure/ground organization, and in traditional Gestalt theory, figure/ground assignment is assumed to be globally consistent along the entire contour of a figure. If figure and ground reverse at one point on an object boundary, the entire boundary reverses, as in classical bistable figures such as the Rubin face/vase. Here we investigate a situation where local configural cues to figure/ground conflict with global cues: “negative parts.” We constructed displays in which a circular shape included a “bay” or cut-out region. We tested figure/ground interpretation locally by using a moving probe (a region of the contour set in “trembling” motion). We asked subjects which color (the interior or exterior color) seemed to be moving; their response reflects figure/ground assignment, as the motion is perceived to be perceptually owned by the figural side of the boundary. We manipulated the shape and size of the bay, and the position of the probe (inside the bay or elsewhere along the contour). Subjects were significantly more likely to perceive the exterior as figural (that is, to invert the normal figure/ground assignment) when the probe was inside the bay than when it was outside, suggesting that the bay was indeed perceived as a “negative part.” Moreover the shape (convexity) of the bay influenced figure/ground assignment when the probe was inside the bay, but not when it was outside; that is, the figure/ground inversion was local to the negative part itself, resulting in a globally inconsistent figure/ground interpretation. Two followup studies suggest that this phenomenon involved a local inversion of perceived depth, not mere contour ownership. The results suggest that figure/ground interpretation is a dynamic and complex process in which local and global cues combine and compete to produce an ultimate percept that may not be globally consistent.
Support was provided by NIH R01 EY15888.