SPEAKING
two languages rather than just one has obvious practical benefits in an
increasingly globalized world. But in recent years, scientists have begun to
show that the advantages of bilingualism are even more fundamental than being
able to converse with a wider range of people. Being bilingual, it turns out,
makes you smarter. It can have a profound effect on your brain, improving
cognitive skills not related to language and even shielding against dementia in
old age.
This view of bilingualism is remarkably
different from the understanding of bilingualism through much of the 20th
century. Researchers, educators and policy makers long considered a second
language to be an interference, cognitively speaking, that hindered a child’s
academic and intellectual development.
They were not wrong about the interference:
there is ample evidence that in a bilingual’s brain both language systems are
active even when he is using only one language, thus creating situations in
which one system obstructs the other. But this interference, researchers are
finding out, isn’t so much a handicap as a blessing in disguise. It forces the
brain to resolve internal conflict, giving the mind a workout that strengthens
its cognitive muscles.
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 colour, 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 colour. 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 wilfully from one thing to another and holding information
in mind — like remembering a sequence of directions while driving.
Why does the tussle between two simultaneously
active language systems improve these aspects of cognition? Until recently,
researchers thought the bilingual advantage stemmed primarily from ability for inhibition
that was honed by the exercise of suppressing one language system: this
suppression, it was thought, would help train the bilingual mind to ignore
distractions in other contexts. But that explanation increasingly appears to be
inadequate, since studies have shown that bilinguals perform better than
monolinguals even at tasks that do not require inhibition, like threading a
line through an ascending series of numbers scattered randomly on a page.
The
key difference between bilinguals and monolinguals may be more basic: a
heightened ability to monitor the environment. “Bilinguals have to switch
languages quite often — you may talk to your father in one language and to your
mother in another language,” says Albert Costa, a researcher at the University
of “Pompeu Fabra” in Spain. “It requires keeping track of changes around you in
the same way that we monitor our surroundings when driving.” In a study
comparing German-Italian bilinguals with Italian monolinguals on monitoring
tasks, Mr. Costa and his colleagues found that the bilingual subjects not only
performed better, but they also did so with less activity in parts of the brain
involved in monitoring, indicating that they were more efficient at it.
The bilingual experience appears to influence
the brain from infancy to old age (and there is reason to believe that it may
also apply to those who learn a second language later in life).
In a 2009 study by the International School for
Advanced Studies in Trieste, Italy, 7-month-old babies exposed to two languages
from birth were compared with peers raised with one language. In an initial set
of trials, the infants were presented with an audio cue and then shown a puppet
on one side of a screen. Both infant groups learned to look at that side of the
screen in anticipation of the puppet. But in a later set of trials, when the
puppet began appearing on the opposite side of the screen, the babies exposed
to a bilingual environment quickly learned to switch their anticipatory gaze in
the new direction while the other babies did not.
Bilingualism’s effects also extend into the
twilight years. In a recent study of 44 elderly Spanish-English bilinguals,
scientists led by the neuropsychologist Tamar Gollan of the University of
California, San Diego, found that individuals with a higher degree of bilingualism
— measured through a comparative evaluation of proficiency in each language —
were more resistant than others to the onset of dementia and other symptoms of
Alzheimer’s disease: the higher the degree of bilingualism, the later the age
of onset.
Nobody ever doubted the power of language. But
who would have imagined that the words we hear and the sentences we speak might
be leaving such a deep imprint?
Thanks to Yudhijit Bhattacharjee
