What bilinguals do with language that changes their minds and their brains

In the last two decades, there has been an upsurge of research on bilingualism recognizing that bilinguals may be more representative language users than their monolingual peers (e.g., Kroll, Dussias, Bogulski, & Valdes Kroff, 2012). The excitement about bilinguals is related not only to their neglected status in the past literature but also to a set of twin discoveries that have catapulted research on bilingualism into central view in psycholinguistics, cognitive and developmental neuroscience, and gerontology. One of these discoveries is that both languages are active when bilinguals read, listen to speech, and plan speech in either of their two languages (for a review, see Kroll et al., 2012). The other discovery is that bilingualism appears to confer a set of consequences to domain general cognition and to the neural structures that support it (e.g., Bialystok, Craik, Green, & Gollan, 2009). Those consequences are observed across the lifespan and are particularly evident when cognitive resources are challenged because of the normal or pathological trajectory of aging (e.g., Gold, Kim, Johnson, Kriscio, & Smith, 2013). The focus of the new research is on how these two discoveries might be related. The parallel activity of the two languages and the interactions across them require that the bilingual develops skill in language selection to enable fluent performance. The hypothesis that has guided the recent flurry of research is that bilingual minds and brains change as a consequence of having to regulate the two languages. In their Keynote Article, Baum and Titone provide a comprehensive and current summary of the existing evidence on this hypothesis.