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Learning a Second Language: Is It All In the Head?
8 Aug, 2007 11:20 am
Learning a foreign language can be quite difficult for some. In a world of hundreds of languages much of it can end up sounding like Greek. Being able to predict an ability (or lack thereof) to grasp a language may help learners and instructors make sense of it all.
We investigated the existence of a link between differences in the ability to learn a tone language and a particular area in the brain, Heschlís Gyrus (HG) in an article titled ďVolume of Left Heschlís Gyrus and Linguistic Pitch LearningĒ (published online in Cerebral Cortex on July 25th). Heschlís Gyrus is a small finger-shaped brain structure which contains the primary region of the auditory cortex and accounts for no more than 0.2 percent of the entire brain volume. We examined both the left and right HG as well as volume of gray and white matter within. Our research team included Patrick Wong (Northwestern University), Catherine Warrier (Northwestern University), Virginia Penhune (Montreal Neurological Institute), Anil Roy (Northwestern University), Abdulmalek Sadehh (West Virginia University), Todd Parrish (Northwestern University) and Robert Zatorre (Montreal Neurological Institute).
We had 17 native-English speaking participants, aged 18 to 26, participate in a brain scan prior to doing a pseudo second-language training program. When learning the pseudo language, participants 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 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."
Nine of the participants -- and sometimes in fewer than two or three sessions -- were defined as "more successful learners" because they 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.
Interestingly, these learner groups could be predicted by looking at the HG from the scans taken prior to learning the pseudo language. Our data suggests that the volume of the left HG, especially in the gray matter regions, makes a difference in being able to make these predictions.
We were surprised to find that the HG played such a telling role in predicting this type of second language learning. We typically think of the HG as handling basic fundamentals aspects of sound, for example direction of pitch, sound location, volume level, but not something as complex and meaningful as speech.
The participants in this study were also involved in two other studies which examined how performance and brain activation during a particular task predict tone language learning. Together these 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.
This study is the first to consider the predictive value of a specific brain structure on linguistic learning even before training has begun; in this case we may have found a predictor of being able to learn a tone language. Further research may involve uncovering predictive links between brain areas and other types of languages. Our data does not suggest, however, that biology is destiny when it comes to learning a language. These results allow us to understand the brain in a more comprehensive manner that could help us more effectively teach foreign languages and possibly other skills.
This research is supported by grants from the National Institutes of Health awarded to Patrick Wong.
Wong, Patrick et al. Cereb Cortex, Advance Access published on July 25, 2007; doi:10.1093/cercor/bhm115
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