Abstract
When the eye is adapted to Illuminant D65, the perceptual boundary between reddish and greenish hues coincides approximately with the caerulean line — the set of chromaticities formed by mixtures of skylight and sunlight. If chromatic discrimination is measured along lines orthogonal to the subjective boundary, thresholds are minimal near the transition between reddish and greenish categories (Danilova and Mollon, 2012). However, the subjective category boundary can be displaced by chromatic adaptation. Is the region of enhanced discrimination then concomitantly shifted? Using 2-deg bipartite foveal targets and a two-alternative spatial forced choice procedure, we measured discrimination thresholds on steady fields of three different chromaticities: (a) a field metameric to D65; (b) a pale blue field, shifted along the caerulean line from D65; (c) a field shifted orthogonally to the caerulean line in a pinkish direction. The MacLeod-Boynton chromaticity coordinates of the adapting fields were 0.6552, 0.01666, or 0.635, 0.029, or 0.675, 0.029. The luminance of each half of the target field was independently jittered, to ensure that only chromaticity could be used to solve the task. In interleaved experimental runs, we measured the chromaticity at which a uniform 2-deg field appeared neither reddish nor greenish. In the case of all three adapting fields, there were regions of enhanced discrimination and these approximately corresponded with the subjective category boundary. Thus perceptual and performance measures are concomitantly shifted by chromatic adaptation.
Meeting abstract presented at OSA Fall Vision 2012