| The motion of an object may be perceived based on a change in location of either its surface or edges. By isolating the luminance changes produced by a moving object from the physical displacement of its surface and edges, it was found that a static object appears to move when the luminance changes are restricted to a narrow area adjacent to it. Therefore, changes in the luminance contrast of edges are sufficient for the perception of object motion. However, the existence of different motion signals based on luminance changes of edges and surfaces was confirmed by the occurrence of different motion percepts for the same stimulus configuration. As the width of the region which changed in luminance was increased, edge-based motion percepts were replaced by a surface-based motion percept. This study was primarily concerned with the interaction between the mechanisms that signal edge-based motion and surface-based motion. It was found that surface-based motion mechanisms inhibit edge-based motion mechanisms, even when the different motion patterns were in the same direction. Modulating the effects of this inhibition was facilitation between edge-based motion mechanisms when two sliding-edge motions were possible in the same direction. Less facilitation, and possibly inhibition, occurred when the sliding-edge motions were in the opposite compared with the same direction. Finally, there was even greater inhibition from surface-based motion mechanisms ado edge-based motion mechanisms when the different motion patterns were specified in the opposite compared with the same direction. It is concluded that much of the observed inhibition results from high-level perceptual processes that distinguish between whether particular luminance changes are caused by the disappearance and reappearance of one object or by the local movement of multiple objects. Assuming that jumping-object motion is perceived naturally when there is an interruption in the visual processing of a moving object, such as with blinking, the nature of the inhibition would serve to, reduce the inappropriate perception of motion for ether objects adjacent to the previously and newly occupied locations of the moving object. |
