Abstract
Detection of between-eye differences in both hue and chromatic contrast (saturation) were measured using dichoptically superimposed colour patches. Sensitivity was found to be highest at isoluminance and decreased with the addition of task-irrelevant spatially contiguous binocular (i.e. same in both eyes) luminance contrast. However, when the members of each dichoptic pair were presented side-by-side on the screen and thus both viewed with the same eye, the luminance contrast had no effect on the detection of their differences. If the effect of the luminance contrast was simply to dilute, or ‘desaturate’ the chromatic signals we would expect thresholds to increase for the within-eye as well as the between-eye (dichoptic) conditions. We suggest that binocular luminance contrast reduces the interocular suppression between dichoptic colours, causing the dichoptic colours to blend and as a result render their differences harder to detect. Our hypothesis is that binocularly matched luminance contrast promotes the interpretation that disparate colours are nevertheless part of the same object, and we term this the “object commonality hypothesis”.
Meeting abstract presented at VSS 2015