Bilingual signed and spoken language acquisition from birth: implications for the mechanisms underlying early bilingual language acquisition

Divergent hypotheses exist concerning the types of knowledge underlying ear ly bilingualism, with some portraying a troubled course marred by language delays and confusion, and others portraying one that is largely unremarkabl e. We studied the extraordinary case of bilingual acquisition across two mo dalities to examine these hypotheses. Three children acquiring Langues des Signes Quebecoise and French, and three children acquiring French and Engli sh (ages at onset approximately 1;0, 2;6 and 3;6 per group) were videotaped regularly over one year while we empirically manipulated novel and familia r speakers of each child's two languages. The results revealed that both gr oups achieved their early linguistic milestones in each of their languages at the same time land similarly to monolinguals), produced a substantial nu mber of semantically corresponding words in each of their two languages fro m their very first words or signs (translation equivalents), and demonstrat ed sensitivity to the interlocutor's language by altering their language ch oices. Children did mix their languages to varying degrees, and some persis ted in using a language that was not the primary language of the addressee, but the propensity to do both was directly related to their parents' mixin g rates, in combination with their own developing language preference. The signing-speaking bilinguals did exploit the modality possibilities, and the y did simultaneously mix their signs and speech, but in semantically princi pled and highly constrained ways. It is concluded that the capacity to diff erentiate between two languages is well in place PRIOR to first words, and it is hypothesized that this capacity may result from biological mechanisms that permit the discovery of early phonological representations. Reasons w hy paradoxical views of bilingual acquisition have persisted are also offer ed.