Language processing across modalities: Insights from bimodal bilingualism

Recent research suggests differences between bimodal bilinguals, who are fluent in a spoken and a signed language, and unimodal bilinguals, who are fluent in two spoken languages, in regard to the architecture and processing patterns within the bilingual language system. Here we discuss ways in which sign languages are represented and processed and examine recent research on bimodal bilingualism. It is suggested that sign languages display processing characteristics similar to spoken languages, such as the existence of a sign counterpart to phonological priming and the existence of a visual-spatial loop analogous to a phonological loop in working memory. Given the similarities between spoken and signed languages, we consider how they may interact in bimodal bilinguals whose two languages differ in modality. Specifically, we consider the way in which bimodal bilingual studies may inform current knowledge about the bilingual language processing system, with a particular focus on top-down influences, and the fast integration of information from separate modalities. Research from studies looking at both production and perception suggests that bimodal bilinguals, like unimodal bilinguals, process their languages in parallel, with simultaneous access to both lexical and morphosyntactic elements. However, given the lack of overlap at the phonological level (the presumed initial locus of parallel activation in unimodal studies) in bimodal bilinguals' two languages, we conclude that there are key differences in processing patterns and architecture between unimodal and bimodal language systems. The differences and similarities between unimodal and bimodal bilinguals are placed in the context of current models of bilingual language processing, which are evaluated on the basis of their ability to explain the patterns observed in bimodal bilingual studies. We propose ways in which current models of bilingual language processing may be altered in order to accommodate results from bimodal bilingualism. We conclude that bimodal bilingualism can inform the development of models of bilingual language processing, and provide unique insights into the interactive nature of the bilingual language system in general