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Patrick Monnier, Steven K Shevell; Color shifts from patterned backgrounds: Spatial frequency selectivity and contrast sensitivity. Journal of Vision 2003;3(9):701. doi: 10.1167/3.9.701.
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© ARVO (1962-2015); The Authors (2016-present)
BACKGROUND & PURPOSE: Background patterns composed of concentric circles alternating between 2 levels of S-cone stimulation (e.g., concentric circles that appear purple or green) can induce larger shifts in color appearance than a uniform background at either chromaticity. A model based on a neural unit with an antagonistic +s/−s center-surround receptive field, like those found in V1 (Conway, 2001), can account for these color shifts. The neural model makes two further and heretofore untested predictions: 1) the color shifts should reveal spatial-frequency selectivity, and 2) the magnitude of the color shifts should increase with S-cone contrast within the background. Experiments tested both predictions. METHODS: Color appearance of a test field was measured using asymmetric matching. Spatial frequency: With a test-ring fixed in width at 9 min (3.3 cpd), the spatial frequency within the inducing background was varied from 1 to 10 cpd. S-cone contrast: S-cone contrast within the background was varied between 0.10–0.86 Michelson contrast. RESULTS: Spatial frequency: The largest color shift was observed when the test-ring and the concentric circles within the background were equal in width (i.e., equal in spatial frequency). Color shifts were smaller with either an increase or decrease in the spatial frequency within the inducing background. S-cone contrast: Increasing S-cone contrast within the inducing background directly increased the induced color shifts. CONCLUSIONS: The measurements demonstrate the predicted band-pass characteristic with respect to inducing background spatial-frequency, and the monotonicity with respect to background S-cone contrast. Both properties are as predicted by the +s/−s receptive-field of the kind found in cortical area V1.
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