From last weekend’s New York Times:
Bilinguals, for instance, seem to be more adept than monolinguals at solving certain kinds of mental puzzles. In a 2004 study by the psychologists Ellen Bialystok and Michelle Martin-Rhee, bilingual and monolingual preschoolers were asked to sort blue circles and red squares presented on a computer screen into two digital bins — one marked with a blue square and the other marked with a red circle.
In the first task, the children had to sort the shapes by color, placing blue circles in the bin marked with the blue square and red squares in the bin marked with the red circle. Both groups did this with comparable ease. Next, the children were asked to sort by shape, which was more challenging because it required placing the images in a bin marked with a conflicting color. The bilinguals were quicker at performing this task.
The collective evidence from a number of such studies suggests that the bilingual experience improves the brain’s so-called executive function — a command system that directs the attention processes that we use for planning, solving problems and performing various other mentally demanding tasks. These processes include ignoring distractions to stay focused, switching attention willfully from one thing to another and holding information in mind — like remembering a sequence of directions while driving.
Over the last couple of years I have seen quite a few such articles, discussing the cognitive advantages that the bilingual brain has over monolingual speakers, in addition to the obvious practical benefits of simply knowing more than one language. However, all of the studies mentioned in this article and all of the ones I can recall study native bilinguals, rather than those who became fluent in a second language as a late adolescent or adult.
This raises the obvious question: how much of the ancillary benefits of bilingualism, i.e. increased cognitive flexibility and prophylactic protection against Alzheimer’s and similar degenerative neural diseases, are seen by mature learners of a foreign language, compared with native bilinguals?
I strongly suspect that such studies have been done, but it is also possible that the entire field is still so new that they have yet to get that far. Does anyone recall seeing anything on this?