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Ben J. Jennings, Jasna Martinovic; Luminance and color inputs to mid-level and high-level vision. Journal of Vision 2014;14(2):9. doi: https://doi.org/10.1167/14.2.9.
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© ARVO (1962-2015); The Authors (2016-present)
We investigated the interdependence of activity within the luminance (L + M) and opponent chromatic (L − M and S − [L + M]) postreceptoral mechanisms in mid-level and high-level vision. Mid-level processes extract contours and perform figure-background organization whereas high-level processes depend on additional semantic input, such as object knowledge. We collected mid-level (good/poor continuation) and high-level (object/nonobject) two-alternative forced-choice discrimination threshold data over a range of conditions that isolate mechanisms or simultaneously stimulate them. The L − M mechanism drove discrimination in the presence of very low luminance inputs. Contrast-dependent interactions between the luminance and L − M as well as combined L − M and S − (L + M) inputs were also found, but S − (L + M) signals, on their own, did not interact with luminance. Mean mid-level and high-level thresholds were related, with luminance providing inputs capable of sustaining performance over a broader, linearly corresponding range of contrasts when compared to L − M signals. The observed interactions are likely to be driven by L − M signals and relatively low luminance signals (approximately 0.05–0.09 L + M contrast) facilitating each other. The results are consistent with previous findings on low-level interactions between chromatic and luminance signals and demonstrate that functional interdependence between the geniculate mechanisms extends to the highest stages of the visual hierarchy.
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