Relating visual and pictorial space: Integration of binocular disparity and motion parallax

Visual perception in different contexts elicits different perceptual spaces with different perceptual geometry. While visual space emerges from perception in the physical environment, pictorial space arises when the observer looks into a picture. Although visual and pictorial space is suggested to be qualitatively different, observers can still relate the two, where binocular disparity and motion parallax affect this relation. In this study, we developed a geometrical model that describes the spatial connection between visual and pictorial space. This model demarcates the connection into 1) a relief depth scaling along the observer’s line of sight and 2) pictorial distortions that create a rotation of the entire perceptual space. The model was fitted to the behavioral results from a previous study (Wang & Troje, 2023, Vis. Cog., 31(2)) and an additional experiment. In both cases, the participants rotated a human figure to point at different targets in virtual reality. The pointer was displayed on a virtual frame that could differentially manipulate the information conveyed by binocular disparity and motion parallax. The model fitted the behavioral results well and model comparisons validated the relief scaling in the form of depth expansion and the pictorial distortions in the form of an isotropic rotation. Fitted parameters showed that binocular disparity calibrated distance but also introduced relief depth expansion to the pictorial objects, whereas motion parallax calibrated direction. We discuss the implications of the mediating effects of binocular disparity and motion parallax when connecting pictorial and visual space.