Abstract
Abstract
Color vision deficiencies affect color perception and discrimination, but their consequences for the structure and stability of color categories remain less clear. We examined how trichromats, anomalous trichromats, and dichromats assigned 450 physical Munsell color samples to eleven basic color categories and measured the stability of these assignments in a retest two hours later. In each session, participants sorted a randomly mixed set of chips by hand and selected one representative chip for each category. We quantified agreement within and between color-vision groups as well as test-retest reliability within participants.
For the 217 chips that all trichromats assigned to the same category, anomalous trichromats used the same category label for 85% of chips, and their category assignments were less stable across sessions as those of trichromats. Within anomalous trichromats poorer red-green discrimination, indexed by higher RG-CAD scores, was associated with lower sorting consistency. Dichromats showed lower agreement with trichromats and anomalous trichromats and greater prototype instability, but their color categories remained systematically organized rather than random. Information-theoretic analyses revealed a graded increase in categorical uncertainty from trichromats through anomalous trichromats to dichromats together with increasing reliance on lightness.
Thus, the principal effect of color vision deficiency was not a collapse of color categories, but a graded reduction in the precision with which different shades were assigned to otherwise recognizable categories. In a separate subset of nine anomalous trichromats, EnChroma glasses produced no measurable immediate shift toward trichromatic category structures. Overall, our findings suggest that categorical color representations in anomalous trichromats and dichromats remain remarkably robust despite substantial sensory deficits.