Cross-cultural differences in colour vision: Acquired ‘colour-blindness’ in Africa

We report a study of the incidence of ‘colour-blindness’ in southern and central Africa, and we compare the African data with data from various European groups. There was a surprisingly high incidence of tritan errors (yellow–blue defect). The likelihood of making tritan errors increased with age, and was greater in rural areas than in towns. In Europe, no tritan errors were made by samples from the U.K., Eire or Spain, but some tritan errors were made by a sample from southern Greece. In contrast, most of a British sample of people over sixty-five years old makes tritan errors. Although tritan errors were the most frequent, they were often accompanied by protan and deutan errors. This mixed pattern of errors is consistent with the condition being acquired rather than congenital. Many languages of southern Africa categorise blues and greens with the same term. If the tritanopia we report has been endemic, it may have reduced the ‘perceptual pressure’ to split the blue-with-green categories into separate blue and green terms; a speculation consistent with Rivers, W. H. R. (1901. Introduction to A. C. Haddon (Ed.), Reports on the Cambridge Anthropological Expedition to the Torres Straits. Cambridge: Cambridge University Press) © 1998 Elsevier Science Ltd. All rights reserved..