Research Items

Abstract

Tongan Colour-Vision DATA of colour-vision among Polynesian Tongans were collected by Ernest and Pearl Beaglehole in the course of a field trip to Tonga, employing the Ishihara test (seventh edition). Results are recorded in Man of November 1939. 135 Tongans were examined (male, 67; female, 68). Five males appeared to be red-green blind; but no case of female red-green blindness was detected. No cases of blue-yellow blindness, or of complete colour-blindness, were detected in either sex. A comparison of the percentage of red-green blindness in Tongan males (7·46) with comparable results in Whites (8·03), American Negroes (3·7), American Indians (1·7), taken in conjunction with the weight of evidence from all test results available, suggests a possible racial difference in the incidence in males of red-green colour-blindness. Of the five Tongan males with defective colour vision, two were completely green-blind. The proportion of green-blindness to red-blindness among Whites, Negroes, and American Indians as reported is also in the approximate ratio of three to one. Another peculiarity in Tongan subjects is the response of certain of them in the test to plates which can scarcely be read by normal subjects. These Tongans (10 male, 13 female) were otherwise normal. In regard to general colour discrimination a number of colour-names were collected—cream-white, skin-white, yellow or gold, yellow, red, black. There is no specific colour-name for blue, nor possibly for green either. Many descriptive colour-names are in use, as for example, colour-sea = blue; obscure, indistinct = brown; kupesi, stencil for marking bark cloth = dark brown; loujusi, banana leaf = deep green. Degree of saturation is expressed by such qualifying words as mama, light, fakapo’ opouli, dark. The absence of certain terms, for example, for blue, does not imply a poor colour discrimination, but is due to a difficulty in finding words to describe them, and arises from a cultural origin.