The effect of stimulus size on the detection of chromatic deviations from white and yellow across the human visual field

Abstract

We studied how much blue had to be added to white and how much green or red light had to be added to yellow in order to obtain hue perception at various locations in the temporal visual field. The CIE 1931 (x, y) chromaticity coordinates corresponding to a veridical hue perception were subtracted from the chromaticity coordinates of the white (0.35, 0.35) and yellow (0.45, 0.54) in order to obtain the threshold differences (dx, dy) in chromaticity coordinates. When stimulus size was constant at all visual field locations, dx and dy changed with eccentricity. However, when the stimulus was M-scaled by magnifying its size with increasing eccentricity in inverse proportion to the lowest local sampling density of the human retina (cones and ganglion cells at eccentricities 0–10 and above 10 deg, respectively), dx and dy remained constant at all eccentricities. The only exception was caused by lack of functional blue cones in the central fovea.