Abstract: The depth perception in random-dot stereograms (RDS) was investigated under two different display conditions: equiluminance with chromaticity contrast and heteroluminance without chromaticity contrast. The main results were: (1) RDSs were found to induce depth equally well under both display modes; (2)The disparity threshold for perceiving depth in isochromatic RDSs reached its minimum and leveled off at a luminance contrast of 30%, with larger disparities, depth was perceived down to about 10% contrast;(3) When the two eyes were stimulated with chromaticity RDSs, but with different color contrast, the disparity threshold was not significantly different from that with heteroluminance RDSs; (4) Under the condition that one eye was stimulated with chromaticity RDS and the other with heteroluminance RDS, the observers could perceive depth only when contrast of the chromaticity RDS was substantially above equiluminance. The findings suggested that stereoscopic depth is mediated by both the magnocellular and parvocellular (blob and interblob) systems.

Key words: luminance contrast, color contrast, disparity threshold, stereo-depth perception, visual pathway This work was supported by the state Key Project of the National Natural Science Foundation (B9330110) and by the Laboratory of Visual Information Processing