CROSS-CULTURAL DIFFERENCES IN COLOR-VISION - ACQUIRED COLOR-BLINDNESSIN 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 va rious European groups. There was a surprisingly high incidence of trit an 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., Lire or S pain, but some tritan errors were made by a sample from southern Greec e. In contrast, most of a British sample of people over sixty-five yea rs old makes tritan errors. Although tritan errors were the most frequ ent, they were often accompanied by protan and deutan errors. This mix ed pattern of errors is consistent with the condition being acquired r ather than congenital. Many languages of southern Africa categorise bl ues and greens with the same term. If the tritanopia we report has bee n endemic, it may have reduced the ''perceptual pressure'' to split th e blue-with-green categories into separate blue and green terms; a spe culation 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). (C) 1998 E lsevier Science Ltd. All rights reserved.