Abstract
Figure-ground organization (a.k.a. edge-assignment) determines the shapes that we see at edges and is widely known through experience of Rubin's reversible faces-vase image. It is thought to be affected by a host of image-based (e.g., convexity) and non-image factors (e.g., attention, familiarity). Figure-ground organization often appears alongside perceptual grouping as a topic in psychology textbooks but they are typically discussed as separate processes of perceptual organization with their own distinct phenomena and mechanisms. Here, we propose a new class of figure-ground principles based on perceptual grouping between edges and demonstrate that this inter-edge grouping (IEG) is a powerful influence on figure-ground organization. We presented participants with tri-partite images with two vertical dividing edges creating a central region and two flanking regions (e.g., Rubin's faces-vase). The two dividing edges were either grouped or ungrouped according to one of seven different grouping principles (e.g., colour similarity, common fate). We measured figure-ground organization of these tri-partite images (e.g., inner or flanking regions figural) using both subjective reports and an objective, indirect measure of figure-ground organization. Across all grouping principles and both measures, we found that figure-ground organization was affected by IEG such that the central region between the two edges was more likely to be reported as figural when the edges were grouped whereas the flanking regions were reported as figural with ungrouped edges. In addition to these new phenomena, we can also describe some classic figure-ground principles under the same coherent framework. For instance, symmetry in multi-partite displays can be reinterpreted as inter-edge symmetry and convexity effects on figure-ground may be partially due to inter-edge good continuation. Our results suggest that figure-ground organization and grouping have more than a mere association within Gestalt psychology. Instead, perceptual grouping may provide a mechanism underlying a broad class of new and extant figure-ground principles.
Meeting abstract presented at VSS 2017