Concurrent language and motor performance in bilinguals: a test of the age of acquisition hypothesis.

The objective of the present study was to test the hypothesis that the age at which a second language is acquired influences the pattern of cerebral lateralization associated with that language. Subjects who differed in terms of the age at which they had acquired their second language (English or French) were tested on a concurrent task paradigm involving motor and language performance. Hemispheric processing was inferred from the pattern of lateralized and generalized interference between the tasks. No support was found for the age-of-acquisition hypothesis. Instead, the data indicated a language-specific effect. Regardless of age of acquisition and of whether the first language was English or French, bilingual subjects showed lateralized interference effects consistent with left-hemisphere processing when reading in English and translating from French into English, but no lateralized interference when reading in French and translating from English into French. Whether this effect reflects characteristics of the two languages or the influence of social factors in subject-experimenter interaction is considered.