Abstract
Previous research using behavioral techniques reveals that the sensory color continuum can be modified by category. Within-category stimuli (Green0-Green1) now look more similar and are harder to distinguish whereas between-category stimuli (Green0-Blue0) look more different and are easier to distinguish even though their distances in color space are equal. We report the first evidence for the neurophysiological architecture of color categories. We compared event-related brain potentials (ERPs) elicited by physically identical colors (Green0) in three different color contexts in an oddball paradigm while twenty participants performed an unrelated color task. Two of the contexts were different color categories (large distance: Green0-Red0 vs. small distance: Green0-Blue0) and the third context was different colors from the same category (Green0-Green1). Our results showed that deviant colors stimuli in all three different contexts elicited a positive deflection in the posterior regions - the change-related positivity - compared to standard stimuli. In addition, both magnitude of color difference and category difference reduced the latencies of the change-related positivity (34 msec and 20 msec respectively). No amplitude effect was found to correlate with either color magnitude or color category. We conclude that the change-related positivity reflects color category as well as color deviancy processing. Moreover, category effects were not lateralised and suggest that, even if color categories are derived from the color terms of a speaker's language, the changes to color appearance have been effected at a site within visual cortex.
This research was funded by EC grant No 012984 for Stages in the Evolution and Development of Sign Use (SEDSU).