Neuropsychological approaches to bilingualism: A critical review

Abstract

Clinical and experimental studies which have examined the neuropsychological bases of language processing in bilinguals are reviewed and evaluated. Evidence from case studies of polyglot aphasics suggests that the neuropsychological organization of their languages is the same for most bilinguals but that cases of dissociation do occur. Two main factors — language specific and language acquisitional — which might account for dissociation are defined and empirical evidence relevant to each is considered. It is argued that while clinical case studies of bilinguals suffering language disruption following brain damage have been significant in isolating these factors, they have failed to establish their explanatory power, due in part to inadequate data bases and in part to weak hypothesis-testing procedures.A review of the experimental studies provides preliminary evidence that such factors may influence the pattern of hemispheric involvement in the language processing of bilinguals.The variables of age, stage and manner of second language acquisition are discussed in some detail. A theoretical framework integrating the available evidence is proposed and guidelines for further research are suggested.