Perceptual responses to color in the human cortex

Electrophysiological responses to color, as recorded on the scalp (electroencephalogram; EEG), were originally seen as distinctive from retinal responses, in that they related more to the perceptual experience of color. However, EEG has only been used extensively to probe high-level color responses, e.g., relating to color categories or implicit color associations, within the last couple decades. It still remains poorly understood to what extent cortical responses to color reflect activity from the first few visual areas, and to what extent they may be influenced by more anterior visual areas. Here, we explore the high-level (perceptual) vs. low-level (sensory) organization of cortical response to color with EEG in three studies, with a frequency-tagging approach. In Study 1, we test for neural correlates of perceptual blue-yellow asymmetries, and of individual differences in high-level color inferences. In Study 2, we investigate the extent to which cone-opponent mechanisms or categorical perception may explain the variance in the spatiotemporal dynamics of EEG responses to twelve different colors. Finally, in Study 3 we compare actual vs. implicit color responses to color-diagnostic grayscale objects. Overall, the results provide evidence that cortical responses to color are reflective of high-level perception, from their earliest selective onset. Throughout, I interpret these results in a theoretical framework in which the purpose of color perception may be to categorize objects within the environment