Unmasking the myths of the bilingual brain: Surprising insights from across the bilingual lifespan

Petitto, L.

Here I report on our research that uses a revolutionary new brain scanning technology, functional Near Infrared Spectroscopy (fNIRS), as well as state-of-the-art behavioural measures. We investigate the similarities and differences in brain activity that underlie the development of early phonetic processing in bilingual and monolingual infants (birth to 16 months), reading and language processing in bilingual and monolingual children across critical periods in reading development (ages 6 to 10 years), and bilingual and monolingual adults during natural language processing.
These studies have revealed fascinating, first-time correspondences between all groups’ language performance and their brains. In bilinguals, we observed extended and more robust brain activity across each bilingual group that predicted enhanced behavioural performance differences relative to monolinguals, with a key point being this: “difference” need not be “deviance.”
Implicit in using monolinguals as the “gold standard” for bilingual language development and processing is the assumption that the human brain is neurally “set” for one language, whereupon differences from the ostensible “normal” monolingual state, would be tantamount to a “neural trauma.” Such an assumption also ignores a fundamental way that biological systems work, especially science’s eternal “biological paradox:” Neural systems can be at once functionally dedicated and powerfully plastic. As I will show, specific human brain tissue is indeed dedicated for language, yet it can change in principled ways as a result of different early language experience. Crucially, the “change” — the “difference” — is not bad: We observed brain changes as a result of bilingual language exposure that rendered fundamental linguistic processing advantages to the bilingual language user over monolinguals. Rather than focusing on the ways that bilingual brains and language processing are different from monolinguals, to our excitement, a new way of understanding comparative study of bilinguals and monolinguals is this: They provide a powerful new lens into the full neural “extent and variability” that the human brain tissue for language could have assumed, if only a language user had the good fortune of being exposed to two languages as compared to one.