Abstract
Previous studies about the integration of binocular disparity and motion depth cues (motion parallax, and kinetic depth cues) at suprathreshold level claimed that the depth magnitude information from those cues are processed by independent modules, and that those information are integrated in a linear manner, using weighted averaging. The studies at near threshold level, however, reported that the processing of disparity is not independent of the processing of motion depth cues, and that those cues are integrated in a nonlinear manner in depth detection task. We investigated whether the way to integrate depth magnitude information from those cues at suprathreshold level differs from that at near threshold level. In the experiment, observers were instructed to report the apparent depth magnitude for the random dot display (16 × 14 deg) by the use of which a previous study found non linear combination for disparity and parallax by the use of depth detection task (Ichikawa et al., 2003, Vision Research). The stimulus specified sinusoidal undulation (0.13 cpd) in terms of disparity and parallax. The sizes of disparity and parallax ranged from depth threshold level to six times of the threshold level, which were measured for each observer in preliminary tests. We found that, at any sizes of disparity and parallax, the depth magnitude information from disparity and parallax are integrated in a linear manner (weighted averaging). Our results suggest that the manner to integrate depth information from disparity and motion cues varies with the problem that the visual system has to solve.