ENVIRONMENTAL-INFLUENCES IN HAND PREFERENCE - AN AFRICAN POINT-OF-VIEW

In order to examine further the role of cultural and environmental fac tors in human manual preference, two surveys were undertaken in studen ts from Ivory Coast and Sudan. In the first study (Abidjan, Ivory Coas t) 382 secondary students, ages 12 to 22, answered a 20-item manual pr eference questionnaire. The observed frequency of left-hand preference was 7.9%, with very low left-hand use among the 18-22 age group (1%) and high among the 12-15 age group (14%). In the second study (Khartou m, Sudan) 759 undergraduates, ages 18 to 33, answered a 25-item questi onnaire. The observed frequency of left manual preference was 5%. Subj ects were also asked to indicate any pressure to change hand for writi ng, eating, or other manual activities and, in the second study, any u pper limb injury which temporarily rendered the subject unable to use his (her) preferred hand. Report of an upper Limb injury in the past w as related to mixed (or inconsistent) hand preference. In both studies , the target activity against left-hand use was eating. These results show that cultural and environmental factors could change ''natural'' hand preference in three ways: (i) by changing the hand used for only one activity (e.g., eating), with no change far other familiar unimanu al activities; (ii) by reducing the degree of hand preference; (iii) b y changing the overall preferred hand, generally reducing the prevalen ce of left-handedness. The design of handedness studies should allow t hese possibilities to be distinguished. (C) 1997 Academic Press.