Abstract
Many languages use a single color term for colors that are distinguished as “blue” and “green” in English (Gladstone, Rivers, Berlin and Kay, and many others). Some investigators have suggested that this is due to “Linguistic Relativity”, a particular version of the Sapir-Whorf hypothesis (Davidoff), whereby language determines many aspects of perception and thought. Others have attributed it to general weakness of perception of short-wavelength and blue stimuli (Ratliff), perhaps due to especially dense macular pigment (Bornstein). We offer three lines of evidence that this cultural phenomenon may be largely due to accelerated aging of the ocular lens by high lifetime exposure to the UV-B radiation in sunlight. (1) A review of 203 world languages shows that those spoken in low UV-B localities tend to have a special word for “blue”. On the other hand, languages spoken in high UV-B localities tend to use a single word to mean “blue” and “green”, or a single word to mean “blue” and “black”. (2) Field studies show that blue-yellow color vision deficiency is rare in young subjects living in low UV-B localities. On the other hand, it is common in elderly subjects and in subjects of all ages living in high UV-B localities, a result consistent with phototoxic lens brunescence. (3) In our laboratory, we simulated the colorimetric effects of six ocular lens optical densities on 40 color samples, and collected color naming data from 15 young native English speakers. Subjects used “blue” as in English when the simulated lens was clear, but when the lens was dense, they followed the pattern of languages spoken in high UV-B localities. Thus, brunescence of the ocular lens can predict the lack of “blue” in a subject's vocabulary. Furthermore, our within-subjects experimental design precludes a cultural explanation for our results. Our review of languages and color vision test results suggests that the lack of a word for “blue” may be a physiological phenomenon, unrelated to “linguistic relativity” or other possible cultural explanations.