For most native English-speakers, learning the Mandarin Chinese language from scratch is no easy task.
Learning it in a class that essentially compresses a one-semester
college course into a single month of intensive instruction — and
agreeing to have your brain scanned before and after—might seem even
more daunting.
But the 24 Americans who did just that have enabled University of
Delaware cognitive neuroscientist Zhenghan Qi and her colleagues to make
new discoveries about how adults learn a foreign language.
The study, published in May in the journal NeuroImage, focused on the
roles of the brain’s left and right hemispheres in language
acquisition. The findings could lead to instructional methods that
potentially improve students’ success in learning a new language.
“The left hemisphere is known as the language-learning part of the
brain, but we found that it was the right hemisphere that determined the
eventual success” in learning Mandarin, said Qi, assistant professor of
linguistics and cognitive science.
“This was new,” she said. “For decades, everyone has focused on the
left hemisphere, and the right hemisphere has been largely overlooked.”
The left hemisphere is undoubtedly important in language learning, Qi
said, noting that clinical research on individuals with speech
disorders has indicated that the left side of the brain is in many ways
the hub of language processing.
But, she said, before any individuals — infants learning their native
language or adults learning a second language — begin processing such
aspects of the new language as vocabulary and grammar, they must first
learn to identify its basic sounds or phonological elements.
It’s during that process of distinguishing “acoustic details” of
sounds where the right side of the brain is key, according to the new
findings.
Researchers began by exposing the 24 participants in the study to
pairs of sounds that were similar but began with different consonants,
such as “bah” and “nah,” and having them describe the tones, Qi said.
“We asked: Were the tones of those two sounds similar or different?”
she said. “We used the brain activation patterns during this task to
predict who would be the most successful learners” of the new language.
The study continued by teaching the participants in a setting
designed to replicate a college language class, although the usual
semester was condensed into four weeks of instruction. Students attended
class for three and a half hours a day, five days a week, completed
homework assignments and took tests.
“Our research is the first to look at attainment and long-term
retention of real-world language learned in a classroom setting, which
is how most people learn a new language,” Qi said.
By scanning each participant’s brain with functional MRI (magnetic
resonance imaging) at the beginning and end of the project, the
scientists were able to see which part of the brain was most engaged
while processing basic sound elements in Mandarin. To their surprise,
they found that — although, as expected, the left hemisphere showed a
substantial increase of activation later in the learning process — the
right hemisphere in the most successful learners was most active in the
early, sound-recognition stage.
“It turns out that the right hemisphere is very important in
processing foreign speech sounds at the beginning of learning,” Qi said.
She added that the right hemisphere’s role then seems to diminish in
those successful learners as they continue learning the language.
Additional research will investigate whether the findings apply to
those learning other languages, not just Mandarin. The eventual goal is
to explore whether someone can practice sound recognition early in the
process of learning a new language to potentially improve their success.
“We found that the more active the right hemisphere is, the more
sensitive the listener is to acoustic differences in sound,” Qi said.
“Everyone has different levels of activation, but even if you don’t have
that sensitivity to begin with, you can still learn successfully if
your brain is plastic enough.”
Researchers can’t say for certain how to apply these findings to
real-life learning, but when it comes down to it, “Adults are
trainable,” Qi said. “They can train themselves to become more sensitive
to foreign speech sounds.”
More about the research
The research was done at Massachusetts Institute of Technology (MIT),
where Qi conducted postdoctoral training at the McGovern Institute for
Brain Research before joining the UD faculty in 2017.
She is an assistant professor in the Department of Linguistics and Cognitive Science and has joint appointments in the Department of Psychological and Brain Sciences and the Communication Sciences and Disorders Program.
The NeuroImage paper
was co-authored with colleagues at MIT and at Northeastern and Boston
universities, and the research was supported by the Defense Advanced
Research Projects Agency.
Article by Ann Manser; photo by Evan Krape
