Speaking Two or More Languages Changes Your Mind and Brain

You are walking on a busy street or sitting at a café and suddenly become aware that you are eavesdropping on a conversation that is taking place in two languages at once. Sentences may start in English and then switch to Spanish and then back to English again.  If you are a bilingual speaker of Spanish and English this may come as no surprise but if you are a monolingual speaker of one of these languages alone, you may wonder how the speakers are able to move so easily from one language to the other. Not only can these bilingual speakers switch from one language to the other but they can understand each other and they rarely make errors of speaking the wrong language.

Although proficient bilinguals are impressively skilled, many adults find it difficult to acquire a second language past early childhood. In the last decade there has been a upsurge of research on each of these topics. How do bilinguals juggle the two languages without making errors? What enables adult learners to acquire a second language successfully? And what are the consequences of acquiring and using two or more languages? What we have learned is that even skilled bilinguals cannot easily turn off one of the two languages. Instead, both languages are active and the exchange between them changes not only the second language, but also the native language.

Far from the concern that the use of two languages might impose excessive demands on the minds and brains of bilinguals or create problems for young learners, recent studies reveal the remarkable ways in which bilingualism changes the brain networks that enable skilled cognition, support fluent language performance, and facilitate new learning. The new research also shows that these changes to the mind and the brain are not simple.  Bilingualism takes different forms that depend on an individual’s learning history, on the two languages themselves, and on the contexts in which the two languages are used. The consequences that result reflect that complexity. In this talk I illustrate the new findings on how bilinguals learn and use language in ways that change their minds and brains.