"Luminance and color inputs to mid-level and high-level vision" published in Journal of Vision
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.
Reference
Jennings, B. J. and Martinovic, J. (2014). Luminance and color inputs to mid-level and high-level vision, Journal of Vision 14 (2): 9, doi: 10.1167/14.2.9