The effects of local object motion and binocular disparity on collision detection

摘要

Previous research has demonstrated the advantage of binocular information for motion in depth. The current study examined the roles of binocular disparity on the detection of an impending collision when distant objects in the background had projected velocities due to observer motion. We presented observers with 3D scenes consisting of either a ground plane or a ground plane with objects in the scene that extended vertically from the ground plane. In addition, observers were shown an approaching sphere that was positioned above the ground texture. The displays simulated forward observer motion resulting in velocities adjacent to the approaching object when scene objects were present. For half of the trials the sphere was on a collision path with the observer whereas the remaining trials the sphere would pass by the observer. Before the full collision trajectory (7200ms) was shown the trial terminated and observers indicated whether or not the sphere was on a collision path. Three independent variables were manipulated: viewing condition (binocular vs. monocular), the presence of adjacent velocities (scene objects present vs. scene objects absent), and display duration (1000ms vs. 5000ms). We found that sensitivity to detect a collision (d') decreased with display duration (F(1, 6)= 28.634, p= 0.002) and with the presence of scene objects (F(1, 6)= 43.475, p0.001). There was a non-significant trend of viewing condition with improved performance observed in the binocular disparity conditions at longer display durations. However, similar performance declines occurred for both monocular and binocular viewing conditions when object motion adjacent to the approaching collision object was present. These results suggest that the addition of binocular disparity does not allow for observers to overcome the effect of local motion from objects in the scene, but it does provide a slight benefit when viewed for a longer temporal period.