Detection of the Relative Depth between Surfaces with the Same or Different Features in Human Stereopsis

抄録

The visual system has the ability to distinguish depth differences between stimuli with high precision on the basis on binocular disparities. Psychophysical studies have suggested that binocular depth perception depends not only on the given disparity but also on other factors, such as surrounding stimuli, the spatiotemporal conditions, and the disparity gradient. Here, we report that the similarity between two surfaces enhances the sensitivity to the relative depth between the surfaces. Experiment 1 investigated the effect of orientation on the sensitivity to detect the relative disparity between patches filled with gratings and Experiment 2 investigated the effect of color. The results showed that the sensitivity to disparity differences was higher when the two surfaces had the same orientation (Experiment 1) or the same color (Experiment 2) than when either orientation or color was different. Using random-dot stereograms, Experiments 3 and 4 investigated the influence of luminance and color borders on the perception of relative depth. The results showed that the sensitivity to the relative disparity was higher when the disparity discontinuity borders were at different locations from the location of luminance or color borders than when they were at the same locations. These results suggest that the visual system is sensitive to relative depth within the same surface more than to the relative depth between different surfaces.