Effects of colour adaptation and stimulus size on the detection of chromatic deviations from achromatic as a function of eccentricity in man.

By using constant size and M-scaled stimuli (the stimulus size was magnified towards the visual field periphery in inverse proportion to the lowest local sampling density of the human retina) we measured the thresholds for perceiving the complementary colours of blue, green and red (i.e. yellow, purple or blue-green) under chromatic adaptation at the eccentricities of 0-15 degrees in the nasal visual field. The CIE 1931 (x, y) chromaticity coordinates corresponding to complementary hue perception were subtracted from the chromaticity coordinates of achromatic threshold. The difference was found to be constant irrespective of stimulus size and eccentricity. This means that the perception of chromatic deviation from achromatic under chromatic adaptation is independent of stimulus size and eccentricity.