Linguistic and cognitive development in bilingual children

A growing body of research suggests a close relationship between children's development of linguistic and cognitive skills, with language development and cognitive development mutually influencing each other. This chapter considers childhood bilingualism as a special case of language acquisition, with implications for the relationship between linguistic and cognitive processes. Specifically, during bilingual language development, language input is phonologically more complex and spans two languages instead of one. Given language input that includes phonetic inventories and vocabulary from two languages (consisting of two labels for most concepts), linguistic and cognitive implications for bilingual development are discussed. In addition, the chapter considers the consequences of simultaneous activation of two language systems and the juggling of two language codes in children. It is suggested that bilingual children may have a higher cognitive processing load during language use and learning, resulting in both linguistic and cognitive differences compared with monolingual peers. Recent research on linguistic and cognitive differences between monolingual and bilingual children is placed in the context of current theoretical models of language learning, development, and processing. In particular, we consider recent findings from monolingual and bilingual children in the context of learnability theory (with an emphasis on the influence of input complexity on linguistic / cognitive development), and in light of usage-based accounts of language acquisition (with an emphasis on the development of potentially different cognitive skills in monolinguals and bilinguals). We conclude that childhood bilingualism provides a unique context for examining the interaction between linguistic and cognitive mechanisms during development.