Categorical encoding of color in the brain

Bird, Chris M, Berens, Samuel C, Horner, Aidan J and Franklin, Anna (2014) Categorical encoding of color in the brain. Proceedings of the National Academy of Sciences of the United States of America (PNAS) ISSN 1091-6490, 111 (12). pp. 4590-4595. ISSN 0027-8424

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Abstract

The areas of the brain that encode color categorically have not yet been reliably identified. Here, we used functional MRI adaptation to identify neuronal populations that represent color categories irrespective of metric differences in color. Two colors were successively presented within a block of trials. The two colors were either from the same or different categories (e.g., “blue 1 and blue 2” or “blue 1 and green 1”), and the size of the hue difference was varied. Participants performed a target detection task unrelated to the difference in color. In the middle frontal gyrus of both hemispheres and to a lesser extent, the cerebellum, blood-oxygen level-dependent response was greater for colors from different categories relative to colors from the same category. Importantly, activation in these regions was not modulated by the size of the hue difference, suggesting that neurons in these regions represent color categorically, regardless of metric color difference. Representational similarity analyses, which investigated the similarity of the pattern of activity across local groups of voxels, identified other regions of the brain (including the visual cortex), which responded to metric but not categorical color differences. Therefore, categorical and metric hue differences appear to be coded in qualitatively different ways and in different brain regions. These findings have implications for the long-standing debate on the origin and nature of color categories, and also further our understanding of how color is processed by the brain.

Item Type: Article
Schools and Departments: School of Psychology > Psychology
Subjects: B Philosophy. Psychology. Religion > BF Psychology > BF0311 Consciousness. Cognition
Q Science > QZ Psychology
R Medicine > RC Internal medicine > RC0321 Neurosciences. Biological psychiatry. Neuropsychiatry
Depositing User: Samuel Charles Berens
Date Deposited: 02 Jun 2014 09:31
Last Modified: 01 Jul 2019 17:30
URI: http://sro.sussex.ac.uk/id/eprint/48852

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