| Abstract: | In two experiments, multilingual Papua New Guinean subjects were tested using a divided visual field technique designed to determine hemispheric laterality for English and for Tok Pisin. Various factors including age of acquisition, proficiency, mode of instruction, and number of years that the language had been used were considered in relation to language laterality. Only age of acquisition proved to be a significant contributor to the laterality effects obtained; older acquirers of both English and Tok Pisin showed greater right hemisphere involvement than early acquirers. Although proficiency did not seem to be related to language laterality, it too was systematically affected by acquisition age. Older acquirers of English performed significantly poorer than younger acquirers on all four of the language-usage tests given. The strong influence of acquisition age on cerebral laterality for language and proficiency is interpreted as supporting a critical period for language learning. |
