Camilla Simoncelli¹, Fatemeh, Charkhtab Basim¹, Erin Goddard², Michael, A. Webster¹; ¹University of Nevada, Department of Psychology and Center for Integrative Neuroscience, ²University of New South Wales Sydney, School of Psychology

Individual differences in color appearance (e.g. the stimulus that “looks” pure red) and color naming (e.g. the stimuli labelled “red”) are well-established, but the extent to which these differences are related remains uncertain. We examined this relationship by comparing focal colors and color categories in 18 English-speaking color-normal observers, to ask whether differences in how colors are described or communicated can partly be predicted from how colors are perceived. Stimuli were defined in the LvsM and SvsLM cone-opponent plane and shown in a uniform field on a gray background. In the focal task, hue angle was varied at a fixed chromatic contrast to select the unique hues (pure red, green, blue, or yellow) or balanced binary hues (orange, purple, blue-green, yellow-green). In the naming task, stimuli spanning a wide range of hue angles and contrasts were each labelled with the same 8 terms plus gray. Variations across observers were significantly larger than within-observer variability for both tasks. However, with one exception (yellow), correlations between the focal hues and category boundaries were weak. Consistent with this, an algorithm designed to warp the color space to align appearance judgments (Simoncelli and Webster Color Res App 2024) did not result in increased consensus in color naming. These results suggest that inter-observer differences in appearance and naming reflect different underlying processes or criteria. Previous studies have emphasized the importance of correcting for both sensitivity and appearance differences to increase consensus in color rendering. However, the present analyses suggest that such corrections are unlikely to improve consistency across viewers in color naming, and thus point to the need to directly assess and include categorical variability as a third factor for predicting individual differences in color experience.

Acknowledgements: Funding: EY0108334 and ICC Danny Rich Memorial Scholarship Fund 2024