Abstract
The paper examines the notion, widespread in the contemporary color science, that there are certain hues, specifically focal red, yellow, green and blue (RYGB), that are unique or privileged in human prelinguistic color perception, all other chromatic hues being perceptually composed of these. I successively consider and reject all motivations that have been provided for this opinion; namely the linguistic (unique hues as referents of necessary and sufficient color descriptors), "phenomenological" (unique hues as phenomenologically pure color experiences), and some minor or historical motivations.
I conclude that, contrary to the standard opinion, there is no solid reason to claim that the RYGB hues are unique among colors in a sense that would allow for direct neurophysiological explanation. The notion also has no relevance for the construction of perceptual color spaces and is not defensible as an explanatory principle with respect to the existing crosslinguistic patterns of color categorization.