Scene perception is the visual perception of the three-dimensional environment surrounding us as viewed by the visual system at any given time. Background surfaces, especially a ground surface, are the important components of high level 3-D scene perception. The role of background surfaces in determining the perceived layout of objects was a major component of Alhazen’s (c.1039/1989) theory of depth perception. Gibson (1950) also highlighted the role of ground surfaces and he proposed ground theory as an alternative to ‘‘air theories,’’ which considered only distances between the eyes and objects in empty space as an account of depth perception. In order to obtain more insight into the role background surfaces in scene perception, the current study investigated the information provided by background surfaces, especially a ground surface, in perceiving the layout of objects and the motion of objects in 3-D scenes.

The thesis is organized into four parts. In the first part, the interaction between the background surface and horizon in determining the perceived layout of objects, measured by size and distance judgments, was examined. Results showed that judgments of perceived layout for objects in a scene are affected by their locations relative to the perceptual horizon. We found that the location of the perceptual horizon appears to be based on a combination of two sources of information: (1) The implied vanishing point, derived by the horizon rule, and (2) the boundary of the visible surface. In the second part, we examined the effect of the location of the perceptual horizon on the perception of an object's motion trajectory. Results suggested that the visual system perceives a path change in the 3-D motion of objects when they travel from the ground to locations above the perceptual horizon. The height at which the path change was observed is determined by an interaction between the location of the implicit horizon extrapolated from converging lines and the location at which the surface terminates in the background scene. In the third part, we examined whether background slant and background type affects change detection performance. Results of the third part indicated that change detection is more efficient with frontal plane or near ground plane backgrounds than with planes at intermediate slants and ceiling planes. We concluded that any superiority of frontal plane backgrounds in a change detection task may be equivalent to the superiority of a near-ground plane in organizing a scene, with the lowest level of performance occurring for surfaces that are not frontal but further from a ground surface orientation. In the fourth part, we examined how surface type affects the dynamics of binocular rivalry. The superiority of ground surfaces over ceiling surfaces in determining the representation of the visual world, has been demonstrated in several studies of visual perception. Our results also indicated that ground surfaces are predominant over ceiling surfaces, with this predominance affecting both the dominance and suppression phases of binocular rivalry.

Overall, our results suggest that background surfaces are the important component of 3-D scene perception and ground surfaces are effective in various perceptions such as the determining the layout of objects, perceiving motion trajectories of objects, detecting changes in scenes and determining the dominance rates in binocular rivalry.