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 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.
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 an ability forinhibition 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 led by
Agnes Kovacs of 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?
Correction: March 25, 2012
The Gray
Matter column on bilingualism last Sunday misspelled the name of a university
in Spain. It is Pompeu Fabra, not Pompea Fabra.
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