Colour envisioned: concepts of colour in the blind and sighted

Imagine you were born completely blind, what would your understanding of colour be? Here we address this question, which hitherto has had no substantive answer. We asked samples of congenitally blind, adventitiously blind, and normally sighted (trichromatic) adults to rate the dissimilarities of pairs of colour terms. We then used multidimensional scaling to generate perceptual maps based on these dissimilarity ratings. The resulting maps were strikingly similar across groups. All groups were able to organize both basic and descriptive colour terms into a pattern resembling the trichromatic colour space, with only minor differences between the maps generated by the congenitally blind group and those generated by the adventitiously blind and sighted groups. These results suggest that the semantic associates of colour can exert a profound influence on how the blind understand colour terms and relationships. Furthermore, they also suggest that colour memory is well preserved in the adventitiously blind, despite prolonged blindness.