VISUAL SENSITIVITIES TO CUES FOR DEPTH PERCEPTION.

Abstract

″Depth sensitivity″ defined as the ratio of viewing distance to depth discrimination threshold is introduced in order to evaluate the effectiveness of various cues for depth perception. The depth discrimination thresholds for the binocular parallax and motion parallax, and the cue from accommodation are measured, and the depth sensitivities for these cues calculated. Further, the depth sensitivities for the cues of object size and from air-perspective are also calculated by estimating the threshold values. From a comparison of the calculated depth sensitivities, the following are concluded: (1) The sensitivity for binocular parallax is highest at a distance shorter than about 10 m, (2) the motion parallax is fairly effective when the motion velocity is kept optimum (5-10 degrees in visual angle/sec), and the sensitivity for it exceeds that for binocular parallax at a distance above about 10 m, (3) the cues obtained from accommodation and covergence are effective only at a distance under about 1 m, and (4) the size of object and the air-perspective give effective cues for a long distance.