Capturing the variation in language experience to understand language processing and learning

A goal of early research on language processing was to characterize what is universal about language. Much of the past research focused on native speakers because the native language has been considered as providing privileged truths about acquisition, comprehension, and production. Populations or circumstances that deviated from these idealized norms were of interest but not regarded as essential to our understanding of language. In the past two decades, there has been a marked change in our understanding of how variation in language experience may inform the central and enduring questions about language. There is now evidence for significant plasticity in language learning beyond early childhood, and variation in language experience has been shown to influence both language learning and processing. In this paper, we feature what we take to be the most exciting recent new discoveries suggesting that variation in language experience provides a lens into the linguistic, cognitive, and neural mechanisms that enable language processing.