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Yeon Jin Kim, Kathy Mullen; Suprathreshold interactions between color and luminance contrast: the effect of cross-oriented luminance contrast on perceived color contrast under dichoptic, monocular and binocular viewing conditions. Journal of Vision 2016;16(12):1146. doi: https://doi.org/10.1167/16.12.1146.
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© ARVO (1962-2015); The Authors (2016-present)
Natural scenes contain both color and luminance contrast at different spatial scales and orientations that are sometimes spatially overlaid and sometimes not. Hence, the study of the interaction between color and luminance contrast is fundamental to a complete understanding of visual processing. Such interactions have been well established at the level of detection thresholds, revealing that responses to color and luminance behave independently and are attributable to separable neural processes. Here we investigate suprathreshold interactions between overlaid color and luminance contrasts presented orthogonally (cross-oriented) to reveal how luminance contrast affects the contrast normalization of perceived color contrast. Method: We tested the effects of an overlaid luminance contrast pattern on the perception of color contrast using a method of constant stimuli to determine a Point of Subjective Equality (PSE) between color-only and color plus luminance contrast for binocular, monocular and dichoptic viewing conditions across a range of spatial frequencies (0.375-1.5 cpd, at 2Hz). Results: Our results show that overlaid luminance contrast affects the perceived color contrast, and that the effect is markedly different across viewing conditions. For binocular and monocular viewing, the interaction is facilitatory, with overlaid, cross-oriented luminance contrast enhancing the saliency of perceived color contrast by up to 40-50%. For the dichoptic viewing, however, the interaction is inhibitory, with the luminance contrast suppressing color contrast interocularly. Conclusions: We propose that the underlying mechanism mediating the chromatic facilitation exists as an excitatory within-eye route that carries forward to binocular site, and that a suppressive interocular route may also modulate responses via a binocular site.
Meeting abstract presented at VSS 2016
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