Slant perception of asymmetric stimuli

Abstract

In this research slant perception of asymmetric stimuli was investigated. It is presumed that observers make assumptions like orthogonality and planarity to extract 3-D information from a 2-D image. When the retinal image is asymmetric this assumption leads to different slants for the different parts of the image. Interestingly, symmetric retinal images often become asymmetric when viewed obliquely, raising the question in which way this affects slant perception. Perceived slants of asymmetric retinal images were compared to computed slants. Computations were based on a vector model in which orthogonality and planarity constraints were implemented. Stimuli were projected rectangles slanted about the vertical/horizontal axis. Stimuli were either made asymmetrical on the screen (experiment 1), or made asymmetrical by slanting the screen (experiment 2). Results show that indicated slants can be predicted by local orthogonality/planarity assumptions, which leads to accurate predictions for perceived slants of obliquely viewed stimuli.