Abstract

Previous studies of whether stereopsis is possible at isoluminance for red-green stimuli have been inconclusive because they did not control for chromatic aberration. A two-alternative forced choice staircase procedure was used to measure stereo (front-back) discrimination thresholds for random-dot stereograms, which had all detectable longitudinal and transverse aberrations removed by low pass filtering. Ten red to red-plus-green luminance ratios were tested. Although individual differences were apparent, the two subjects could fuse all stimuli, including those at isoluminance. Nonblurred red-green stereograms were also investigated, using the same procedure. Curiously, removing the blur enhanced the sensitivity to the isoluminant stereograms for one of the subjects but lowered sensitivity for the other subject, even though both subjects showed increased sensitivity for the unblurred mono chrome stereogram. A quantitative, ideal observer analysis was used to measure the efficiency with which color and luminance information were used in stereopsis. While one subject's visual system used color and luminance information with equal efficiency, the second subject used color in formation with less efficiency.

© 1989 Optical Society of America