In the first study, normally developing 9-month-olds were exposed to Mandarin during a dozen 25-minutes sessions spaced out over four weeks. During these sessions, native Mandarin speakers read from children's books and played with toys while speaking Mandarin. Four different speakers, two men and two women, conducted the sessions, so the babies were exposed to a variety of speaking styles. A control group of infants was exposed to the same procedure in English.
Both groups then were tested for their ability to distinguish between the two Mandarin sounds using a head-turn conditioning procedure that is frequently used in tests of infant speech perception. The infants exposed to Mandarin were significantly better at distinguishing the two target sounds than were infants who only heard English. In fact, the performance of the American infants exposed to Mandarin for the first time between 9 and 10 months was statistically equivalent to infants in Taiwan who had listened to Mandarin for 10 months, according to Kuhl. The results show that the decline in foreign-language speech perception can be reversed with short-term exposure, she said.
In addition, the phonetic learning of Mandarin appears to be long lasting. The American infants were tested from two to 12 days after their last exposure to Mandarin and the researchers found there were no significant differences in their ability to discriminate between the sounds.
"In previous learning studies babies were exposed to artificial languages for a few minutes and no one expected that kind of exposure to produce long-lasting effects," said Kuhl "We predicted that learning in this natural situation would produce a longer lasting eff
Contact: Joel Schwarz
University of Washington