Abstract
Abstract: :
Purpose: To evaluate the direction and extent of the Bezold–Brücke hue shift in the peripheral retina and to determine what retinal and methodological factors influence the effect. Methods: Color–naming functions were obtained in the fovea and at 10° in the temporal retina using the 4+1 color–naming technique. Rod influence on color judgments was manipulated by varying stimulus intensity (–0.2–3.3 log td), stimulus size (0.098–5.0°), and retinal location (fovea, 10° temporal). Stimuli ranged from 440–660 nm in 10 nm steps. Hue ratios derived from the color–naming functions were used to simulate Bezold–Brücke hue shifts measured with a foveal bipartite field, a peripheral bipartite field, and an asymmetric matching procedure in which a peripheral test stimulus is compared to a foveal matching stimulus. Results: Foveal data revealed traditional Bezold–Brücke hue shifts; with increasing intensity, longer wavelengths appeared more yellow and shorter wavelengths appeared more blue. At 10° temporal eccentricity, hue shifts were similar to the fovea, though differences were observed, especially in the middle– to long–wavelength region of the spectrum. Data simulating an asymmetric matching paradigm demonstrated that the Bezold–Brücke hue shift is dependent upon the intensity relationship between the foveal and peripheral stimuli, with the greatest effect in the middle– to long–wavelength region of the visible spectrum. Conclusions: Bezold–Brücke hue shifts derived from color–naming data permit easy comparison to previous Bezold–Brücke studies using bipartite fields and asymmetric color–matching procedures. Our study shows that retinal location and stimulus features influence the degree and direction of the Bezold–Brücke hue shift. The presence of rods and a decrease in photopigment optical density in the periphery may partially explain the differences in hue shifts between the fovea and peripheral retina.
Keywords: color vision • perception