Effects of the amount of monocular shape information on stereo scaling problem

The perception of a three-dimensional shape from binocular disparity depends on the estimation of viewing distance. Therefore, in the absence of good distance information, an observer misestimates the viewing distance and perceives a wrong depth for an object. While motion depth cues can theoretically overcome this problem, past studies have reported inconsistent results. We examined whether differences in the amount of monocular shape information between the stimuli used in these past studies can resolve the discrepancy. The amount of information was manipulated by changing the presence of object boundaries, dot density, and rotation angles. The results indicate the effect of the amount of monocular shape information and thus suggest its significance in accounting for the discrepancies among past studies. It should also be noted that shape factors interact with viewing distance. Motion cues cannot correct distortion at near viewing distance. This suggests that the cue that gives the larger depth dominates in determining perceived shape