Does
speaking more than one language alter your brain? The findings from a
lifetime of research are revelatory
The
Guardian
Tobias
Jones
Tue
11 Feb 2020 08.00 CET
Over
the past century, perceptions of bilingualism have swung from one
extreme to the other. For much of the immediate postwar years, it was
thought that a toddler’s brain would struggle to cope with two
languages (it would handicap school progress, experts said, and some
even believed it could lead to schizophrenia). But from the 1960s
onwards, increasingly scientific research (coupled, perhaps, with a
greater appreciation of cultural difference) pushed the pendulum a
long way in the other direction. It’s now fairly common to hear
some extraordinary claims about the benefits of bilingualism.
Albert
Costa (a
Catalan-Spanish bilingual) died in 2018, and this book is a great
testimony to his lifetime of research into the subject. Although
peppered with a few technical aspects of neuroscience, it’s very
readable: the prose is gentle, anecdotal, witty, personal and –
despite the many controversies – balanced. He doesn’t deride
monoglots (they have advantages too), but simply invites us to wonder
what happens if you double up on what is already an extraordinary
human ability – language.
The
research results are pretty astonishing. Newborns only hours old can
already detect a change of language. By four to six months they are
able to distinguish between, say, English and French, only by what
they see of the speaker’s mouth. By eight months they can
differentiate, by observing those articulatory movements of the lips,
between two languages to which they haven’t even been exposed.
Babies can “extract statistical regularities” to deduct what,
among the flow of sound, are the basic units: our words. It’s
called – the jargon is light-touch, but enjoyable – “segmentation
strategy” through the use of “transitional probability” (which
syllables are usually heard side by side). Most of these results are
the consequence of placing electronic sensors in dummies that pick up
on babies’ alertness to, and interest in, novelty.
A
newborn’s rapid accumulation of phonemes (sounds) also, however,
involves perceptual narrowing. As they’re deepening their sound
inventory in their own languages, they’re getting less adept at
doing it in others. Because it’s thought that the “language
store” is one big bucket, not separate cups, the bilingual toddler
has to be adept at code-switching, inhibiting one language and
green-lighting the other.
We’re
less instinctive and kneejerk in a foreign language, more able to be
utilitarian and cold-headed
That
means bilinguals have a “slower and less reliable access to the
lexicon than monolinguals”. There is a “change-cost” in which
bilingual speakers are – only milliseconds – slower at naming
common objects. One would have imagined that the minimal delay would
be in sourcing words from the weaker language, but it’s the
opposite: “the cost of change”, writes Costa, “is asymmetric:
its magnitude is greater for the dominant language than for the
non-dominant one (what we call ‘asymmetrical language
code-switching’).” Costa is clear about all these
micro-drawbacks: it’s a generalisation, but generally true that
“bilingual individuals have a smaller vocabulary in their two
languages than monolinguals”.
So
it’s clear that this isn’t a manifesto claiming bilinguals are
geniuses (“don’t worry about whether your opponent in a chess
match is bilingual or not,” he quips). But he lists, in detail, why
their brains are different: there’s less “egocentric bias” in
bilingual children. They are able to see puzzles more easily from
another’s point of view (the difference here is as much as 30%).
They have greater attentional control: subconsciously ignoring half
their brain’s words all their lives means they are less sidetracked
by what are called “flanker” distractions, both in experiments
and thus, perhaps, in real life. Because of a greater “cognitive
reserve”, bilinguals in many trials have reported the onset of
dementia up to four years later than their contemporaries.
For
those of us who are not bilingual, there are still advantages to
language learning. Costa quotes Goethe’s famous
line that “he who does not know foreign languages knows nothing
about his own”. But the advantages aren’t only cultural breadth
or depth, but also better decision-making: we’re less instinctive
and kneejerk in a foreign language, more able to be utilitarian and
cold-headed. (Asked whether it’s worth pushing a man in front of a
train to save five other lives, respondents are more rational than
moralistic when considering the question in a non-native language.)
There’s less “loss aversion” when we’re navigating quandaries
outside our own tongue. People are sometimes aghast that their
allegedly rigid morals are malleable according to the words we hear
and use, but all the research seems to suggest – and it’s good
news for us linguistic exiles – that we reason differently when
we’re struggling, however slightly, for the right words.
It’s
a charming book. Summarising decades of academic research without
being dull, Costa is generous to his peers and gracious where he
demurs from their findings. He hedges a lot of bets, as one must in
measuring anything inside the human head. But he leaves you in little
doubt that the brain of bilinguals is, in tiny but important ways,
provably different.
The
Bilingual Brain: And What it Tells Us About the Science of
Language by
Albert Costa, translated by John W Schwieter, is published by Allen
Lane (£20). To order a copy go to guardianbookshop.com.
Free UK p&p over £15
This
article was updated on 13 & 14 February 2020 to include the name
of the book’s translator in the footnote above; and also to correct
the year of Albert Costa’s death.
