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Neil R. A. Parry, Declan J. McKeefry, Ian J. Murray; Perceived chromaticity shifts with retinal eccentricity. Journal of Vision 2004;4(11):10. doi: 10.1167/4.11.10.
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© ARVO (1962-2015); The Authors (2016-present)
It has been shown that human colour perception changes as a function of retinal eccentricity. Some argue that, if factors such as stimulus size, macular pigment and the contribution of rods are taken into consideration, then peripheral colour vision is found to be qualitatively similar to that experienced in the fovea.
We examined this issue using an asymmetric colour matching technique(1). Perceived shifts in chromaticity of test stimuli presented on a CRT at different nasal eccentricities up to 24 deg were measured by comparing them with a probe of eccentricity 1deg. Photometrically isoluminant probe and test pairs were flashed for 380ms on a 12.5cd/sqm white background. Twelve to 24 probe chromaticities were equally spaced around a hue circle in MBDKL colour space. They included “red-green” (L vs M) and “blue-yellow” (S vs L and M) cardinal axes. Perceived hue shift was measured as an orientation change in this colour space using a same-different paradigm to generate psychometric functions. In a second experiment, hue, saturation and brightness matches were made by method of adjustment.
Consistent with previous studies, perceived hue changed with increasing retinal eccentricity. The magnitude of these shifts was not uniform as a function of chromatic axis. Whilst some hues showed large perceptual shifts with increasing eccentricity, others exhibited negligible shifts. These invariant hues were found to be located close to previously identified unique hue loci(2). Perceived saturation changed with chromatic axis, but this did not correspond to the hue shifts described above. This lack of correspondence might be attributable to the differential contribution of receptoral and post-receptoral mechanisms.
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