Abstract
Investigators have focused on the visual system’s ability to exploit edge information in order to establish border-ownership and correctly perceive the motion of a surface across a background. (Layton, Mingolla, & Yazdanbakhsh, 2012). The random dot cinematogram is often used as a benchmark stimulus to explore the perception of motion when a sector of the cinematogram becomes a coherently displaced surface across frames (Braddick, 1979; Sato, 1989). The discrimination of motion direction and the shape of the displaced surface has been shown to depend on the detection of counterchange (Norman, Hock, Schöner, 2014); i.e. motion is signaled by the simultaneous decreases in local activation at one location and increases at another (Hock et al. 2002; Hock, Schöner & Gilroy, 2009; Norman, Hock, Schöner, 2014). METHOD: The current experiment separated the contribution of surface boundaries from the contribution of the information enclosed by the boundaries to the perception of motion for a random checkerboard. The central portion of a coherent moving surface was replaced with randomly arranged light and dark checks, as if a hole exposed the background, leaving only a thin coherent figure boundary. RESULTS: Observers reliably detected the direction of motion and surface shape when the central portions of the figure had not been removed, but subjects could not detect motion direction or figure shape when the central portion of the surface was made incoherent. The presence of an incoherent hole could not be detected even at the smallest displacements. The results indicate that boundary information is insufficient for direction and shape perception in short-range motion.
Meeting abstract presented at VSS 2015