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Study
Predicts Who Is Better
At Learning A Second Language
Think you haven’t got the aptitude to learn a foreign language?
New research led by Northwestern University neuroscientists suggests
that the problem, quite literally, could be in your head.
“Our study links brain anatomy to the ability to learn a second
language in adulthood,” said neuroscientist Patrick Wong, assistant
professor of communication sciences and disorders at Northwestern
and lead author of a study appearing online in Cerebral Cortex.
Based on the size of Heschl’s Gyrus (HG), a brain structure that
typically accounts for no more than 0.2 percent of entire brain
volume, the researchers found they could predict -- even before
exposing study participants to an invented language -- which participants
would be more successful in learning 18 words in the “pseudo”
language.
Wong and his colleagues measured the size of HG, a finger-shaped
structure in both the right and left side of the brain, using
a method developed by co-authors Virginia Penhune and Robert Zatorre
(Montreal Neurological Institute). Zatorre and Penhune are well
known for research on human speech and music processing and the
brain.
“We found that the size of left HG, but not right HG, made the
difference,” said Northwestern’s Catherine Warrier, a primary
author of the article titled “Volume of Left Heschl’s Gyrus and
Linguistic Pitch.” Anil K. Roy (Northwestern), Abdulmalek Sadehh
(West Virginia University) and Todd Parish (Northwestern) also
are co-authors.
The study is the first to consider the predictive value of a
specific brain structure on linguistic learning even before training
has begun. Specifically, the researchers measured the size of
study participants’ right and left Heschl’s Gyrus on MRI brains
scans, including calculations of the volume of gray and white
matter.
Studies in the past have looked at the connection between brain
structure and a participant’s ability to identify individual speech
sounds in isolation rather than learning speech sounds in a linguistic
context. Others have looked at the connection between existing
language proficiency and brain structure.
“While our study demonstrates a link between biology and linguistics,
we do not argue that biology is destiny when it comes to learning
a second language,” Wong emphasized. Adults with smaller volumes
of left HG gray matter need not despair that they can never learn
another language.
“We are already testing different learning strategies for participants
whom we predict will be less successful to see if altering the
training paradigm results in more successful learning,” Wong added.
According to Warrier, Northwestern research professor of communication
sciences and disorders, the researchers were surprised to find
the HG important in second language learning. “The HG, which contains
the primary region of the auditory cortex, is typically associated
with handling the basic building blocks of sound -- whether the
pitch of a sound is going up or down, where sounds come from and
how loud a sound is -- and not associated with speech per se,”
she said.
The 17 research participants aged 18 to 26 who had their brain
scans taken prior to participating in the pseudo second-language
training were previously participants in two related studies published
by Wong and his research team.
The three studies have identified behavioral, neurophysiologic
and, with the current study, neuroanatomic factors which, when
combined, can better predict second- language learning success
than can each single factor alone.
In a behavioral study, Wong’s group found that musical training
started at an early age contributed to more successful spoken
foreign-language learning. The study participants with musical
experience also were found to be better at identifying pitch patterns
before training.
In a neurophysiologic study -- again with the same participants
-- Wong’s team used functional magnetic resonance imaging to observe
brain areas that were activated when participants listened to
different pitch tones. They found that the more successful second-language
learners were those who showed activation in the auditory cortex
(where HG resides).
The participants all were native American English speakers with
no knowledge of tone languages. In tone languages (spoken by half
the world’s population), the meaning of a word can change when
delivered in a different pitch tone. In Mandarin, for example,
the word “mi” in a level tone means “to squint,” in a rising tone
means “to bewilder” and in a falling and then rising tone means
“rice.”
For the study reported in “Cerebral Cortex,” Wong’s 17 participants
entered a sound booth after having their brains scanned. There
they were trained to learn six one-syllable sounds (pesh, dree,
ner, vece, nuck and fute). The sounds were originally produced
by a speaker of American English and then re-synthesized at three
different pitch tones, resulting in 18 different “pseudo” words.
The participants were repeatedly shown the 18 “pseudo” words
and a black and white picture representing each word’s meaning.
Pesh, for example, at one pitch meant “glass,” at another pitch
meant “pencil” and at a third meant “table.” Dree, depending upon
pitch, meant “arm,” “cow” or “telephone.”
As a group -- and sometimes in fewer than two or three sessions
-- the nine participants predicted on the basis of left HG size
to be “more successful learners” achieved an average of 97 percent
accuracy in identifying the pseudo words. The “less successful”
participants averaged 63 percent accuracy and sometimes required
as many as 18 training sessions to correctly identify the words.
“What’s important is that we are looking at the brain in a new
way that may allow us to understand brain functions more comprehensively
and that could help us more effectively teach foreign languages
and possibly other skills,” said Wong.
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