Abstract
In this study we investigated the conditions under which the visual system treats negative parts as objects. A negative part is a background region mostly surrounded by a region of negative curvature along a figure’s contour. Previous work has shown that negative parts can take on a “quasi-figural” status, inducing globally inconsistent judgments of border ownership (Kim & Feldman, 2009). The degree to which a negative part is treated as figural depends on its geometry, including its depth and the narrowness of its opening. We studied apparent motion of negative parts, focusing on whether variation in a region's figural status could modulate the degree to which it could participate in apparent motion with closed figures. We employed a variant of the Ternus display, containing a sequence of motion frames in which the correspondence between frames can be solved in two distinct ways: "group motion," in which a group of elements in the display appear to translate, and "element motion," in which one object translates while the others do not. Displays were constructed so that group motion percept involved motion between a closed figure and a negative part, while element motion did not, so the proportion of group motion percepts reveals the degree to which the negative part had taken on quasi-object status and thus could be placed in motion correspondence with an ordinary closed object. Critically, we manipulated the geometric factors determining the strength of the negative part. We found that the rate of group motion responses varied with negative part strength, i.e., that stronger negative parts are more likely than weaker ones to be treated as distinct objects. This finding sheds light on the mechanisms by which image regions come to be treated as distinct objects on an equal footing with closed figures.
Meeting abstract presented at VSS 2015