Professor Katarzyna
Dziwirek
Honors 211 C
13 March 2013
Questioning
Bilingual Advantage: A Neurolinguistic Review
Almost
exactly on year ago today, an article unambiguously
titled “Why Bilinguals Are Smarter” was published in the New York Times by Science writer Yudhijit
Bhattacharjee. The content of the piece matched its
confident title: Bhattcharjee wrote “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.” Normally, one could reject such a extreme and
reductive sounding article as a piece of pop science journalism written to to
sell magazines and pay no mind to the science (or pseudo-science) presented. However,
this was in America’s most prestigious newspaper by a man who writes for
America’s most prestigious scientific journal. It had at least some credence,
with me and probably readers worldwide.
Here is the key story
put forward by the article: educators used to think that bilingualism
impeded development because of cognitive interference. We now know that
interference exists: there is evidence that both language systems are always
active, even when one language is in use. But this interference isn’t bad, it’s
good, because it trains the brain to resolve conflict and learn to ignore
information. According to Ellen Bialystok (2004), bilingual children are better
at resolving conflicting information, as shown by certain task switching
paradigms where subjects needed to ignore information about a previous task to
perform the next task. From this experiment, and some of its follow ups, it was
thought that the “bilingual advantage” arose via inhibition and the ability to
suppress irrelevant information, but researchers now see that bilinguals are also
better at other cognitive tasks that don’t require inhibition, such monitoring
ability. This bilingual advantage has been shown in both babies and adults, and
has the possibility of shielding the brain from Alzheimer’s.
I read the article
especially closely, both because I was slightly dubious of the magnitude of its
claims and because I was looking for an explanation to a mystery I didn’t
understand. My lab had been doing the same sort of bilingual research, and
searching for the bilingual advantage through inhibitory tasks, but we had come
up with nothing significant, no trends, nothing. We had accepted the bilingual
advantage via inhibition as if it were a bonafide truth, and then we had to ask ourselves why our
data wasn’t supporting us. Perhaps the secret was, as Bhattcharjee said, that the advantage wasn’t necessarily inhibitory? In this paper, I want
to review the studies he puts forth as evidence for his claims as well as
expand on the exciting bilingualism research that has occurred since the
article was written.
First, a bit of
description about the terms that cognitive scientists like to use in experiments. Executive
function, or executive control, is vaguely described as tasks of higher level
thinking- planning, organizing, making decisions, and other complex stuff. There are various tests of executive
function, and some of them test for specific components of executive function- the
most mentioned is inhibition.
Inhibition
is the most often tested because of Ellen Bialystok’s early success with inhibitory
tasks. The tasks themselves are laborious to describe and demand their own
vernacular, but perhaps the simplest example is the Stroop
task. The stimulus is a color word, printed in a different colored ink (eg. the word “blue” written in red). The subject is
instructed to say the color of the ink aloud, and the time from the
presentation of the stimulus to the subject’s spoken response in recorded.
Because reading is an automatic process for literate humans, it is harder to
name the ink
color than it is to read the word, and in order to do so it is supposed that we
inhibit the primary response and replace it
a different response. That’s the core of most inhibition tasks: a test
is set up to have a natural, non conflicting response, but gives the participant
instructions that override, or inhibit, that response. The faster a participant
can respond to a inhibitory task, the better they are
said to be at resolving conflicting information.
Perhaps
understanding why bilinguals are better at inhibition than monolinguals is
intuitive, but Marian and Shook describe the theory behind testing inhibitory
control in the two groups well:
Because both of a bilingual person’s
language systems are always active and competing, that person uses these
control mechanisms every time she or he speaks or listens. This constant
practice strengthens the control mechanisms and changes the associated brain
regions. . . . .Bilingual people often perform better than
monolingual people at tasks that tap into inhibitory control ability. Bilingual
people are also better than monolingual people at switching between two tasks;
for example, when bilinguals have to switch from categorizing objects by color
(red or green) to categorizing them by shape (circle or triangle), they do so
more rapidly than monolingual people, reflecting better cognitive control when
changing strategies on the fly (Marian & Shook, 2012).
Ellen
Bialystok, of York University, is the leading researcher on the neural basis of
bilingualism, and puts out about four articles or reviews a year on the topic. Her
seminal research was mentioned in “Why Bilinguals Are Smarter”: when presented
with a complex card sorting task where cards were sorted twice using multiple
dimensions (color and shape), bilingual children outperformed monolingual
children, presumably because they were able to ignore irrelevant information.
However, the researchers also found that bilingual children were better at
monolinguals at ignoring perceptual information on the cards, but both groups
were the same at sorting based on semantic details, which was not mentioned in the article
(Bialystok & Martin, 2004).
However,
although a large portion of her own research has been on inhibitory control,
Bialystok recently wrote a review of the consequences of bilingualism for the
brain in which she echoed the sentiments of the article.
Early studies showing bilingual
differences in performance focused
primarily on inhibition, tracing the bilingual advantage in executive
control to the need to inhibit the irrelevant but jointly activated language. . . Subsequent research, however, has
challenged that interpretation; bilingual advantages have been found in
preverbal infants long before any inhibition could be relevant, some types of
inhibition have been implicated in these effects and others have not, and
conditions that involved no inhibition appear to be equally affected. Therefore,
the precise nature of how executive control is involved in bilingual
performance is not clear (Bialystok et al., 2012)
Most
recently, Bialystok has narrowed her focus in on a different type of executive
functioning, working memory. She paired groups of bilingual and monolingual
children in tasks that involved holding different rules in the mind while
manipulating a series of numbers. Bilinguals performed better than
monolinguals, indicating indeed that the bilingual advantage is more widespread
than just inhibition. However, in the discussion, Bialystok and her team
brought up that these children performed equally well on a general intelligence
test, and that the monolinguals, in keeping with other findings, had better
English vocabularies and were faster at word naming (Morales, Calvo, & Bialystok, 2012) . It seems that the bilingual advantage is not
so much an advantage as a redirection of resources in one direction, as there
is a cost to bilinguals in comparison to monolinguals.
Now we
return to focus on the issues with inhibitory control and an increase in
intelligence. Even if bilingualism is truly associated with an increase in
inhibitory control, is inhibitory control always beneficial to cognition? In 2012, Anat Prior found
that bilingualism was correlated with inhibition, but not necessarily in a good
way. The participants were presented with a cue, either for color, shape, or
size, and then presented with a stimulus (either red/green,
small/large, circle/triangle) and would respond via keyboard. The questions
were either asked in an order so that there were no repeats between conditions,
or there were repeats. The theory is that in order to do multiple tasks, you
have to continually inhibit the task you just did to focus on the task at hand,
much like a bilingual might inhibit a language. Bilinguals took longer on the
conflicting trials, which the author took to mean that they inhibited too much,
or at least more than their monolingual counterparts. This effect is certainly related
to executive control, but not in a way that makes the bilingual smarter.
Finally, the
most exciting recent news for the bilingual advantage comes from Gold et al.,
2013. The researches compared monolinguals and
bilinguals at two ages, 30s and 60s.
The subjects did an inhibitory shape/color response test in an fMRI scanner,
in order to capture information about their brain activation during a test. Both
bilingual groups were faster at the inhibition tasks than their monolingual counterparts.
However, the older group showed something especially interesting in the fMRI data: even though they were performing better than the
monolingual group, they had less neural activation. Such results were taken to
mean that the older bilinguals’ brains were more efficient and that
they needed less neural resources to complete the same task as a monolingual.
Recruiting multiple brain areas and more neural resources is common with aging,
as the brain gets less efficient, so for bilingualism to potentially attenuate
this decay is hugely important.
Does
bilingualism make you smarter? I think the article overstates its case,
especially since I think most researchers are careful to stay away from making
conclusions about general intelligence, and seek to find ways in which language
exposure augments and changes thought subtly. Certainly, all research indicates
that there are processing differences in executive function between
monolinguals and bilinguals, with bilinguals tending to have the advantage.
However, the brain has limited resources, and a gain in one area is often
associate with loss in another- for bilinguals, word production and
recognition, naming tasks, and vocabulary have been found to be lower
than matched groups of monolinguals. However, the bilingual bias towards better
executive control may have tremendous implications for the brain as we age, and
forthcoming research is sure to further elucidate the relationship between
bilingualism and protecting the brain.
Works Cited
Bhattcharjee, Yudhijit. Why
Bilinguals Are Smarter. The
New York Times. 17 March
2012. http://www.nytimes.com/2012/03/18/opinion/sunday/the-benefits-of-bilingualism.html
Bialystok, E., Craik,
F. & Luk, G. Bilingualism: consequences for mind
and brain. Trends in cognitive sciences 16,
240–50 (2012).
Bialystok, E. & Martin, M.
Attention and inhibition in bilingual children: evidence from the dimensional
change card sort task.Developmental science 7,
325–39 (2004).
Gold, B., Kim, C., Johnson, N., Kryscio, R. & Smith, C. Lifelong bilingualism maintains
neural efficiency for cognitive control in aging. The
Journal of neuroscience : the official journal of the Society for
Neuroscience 33, 387–96 (2013).
Marian, V. & Shook, A. The Cognitive
Benefits of Being Bilingual. Cerebrum : the Dana forum on
brain science 2012, 13 (2012).
Morales, J., Calvo,
A. & Bialystok, E. Working memory development in monolingual and bilingual
children. Journal of experimental child
psychology 114, 187–202 (2013)
Prior, A. Too much of a good thing:
stronger bilingual inhibition leads to larger lag-2 task repetition
costs. Cognition 125, 1–12 (2012).