Have you ever wondered how babies learn to talk? As this ScienCentral News
video reports, some researchers now think it’s more than just hearing
the people around them.
It's Not Greek To Them
If you have trouble learning new languages now, maybe you should have started
when you were an infant. Babies are born "citizens of the world,"
able to distinguish among sound used in all languages, according to Patricia
Kuhl co-director of the University
of Washington Center for Mind, Brain and Learning and professor of speech
and hearing sciences. She found that nine-month-old American babies could
pick up Chinese from a live teacher in just a few hours.
Kuhl studied how babies distinguish sounds in language by exposing them to
Mandarin Chinese over a four-week period. “We were interested in how
babies are taking up information when they’re listening to parents and
caregivers talk to them," says Kuhl, who published her research in the
Proceedings of the National
Academy of Sciences. "We had live Chinese-Mandarin speakers talk
to American babies who, of course, have never heard Chinese before, to see
what they would learn about the sounds of the language just by listening to
it. We exposed the babies by having the Chinese graduate students take turns
playing with the babies, using a prescribed set of toys and a prescribed set
of books." The nine and ten-month-old babies had twelve of these sessions,
each lasting 25 minutes. There was also a control group of American babies
looking at the same books and toys, but hearing only English. The total amount
of exposure was less than five hours.
image: U. of Washington
Then, the babies were tested from two to twelve days
after their last exposure to Mandarin. They taught the babies to turn their
heads when they could discriminate the sounds of the language. "The test
involved both the American babies exposed to English and the American babies
exposed to Chinese to see which of the kids can hear this distinction,"
says Kuhl. "The answer was very clear, that the American babies exposed
to the Chinese were excellent at the sound change. Whenever the sound changed
they turned their heads. For the kids in the control group who had listened
to English, the sound changes did nothing."
So the babies exposed to Mandarin had picked up a lot within a short amount
of time. "With five hours of experience, the babies who’d been
exposed to live Mandarin speakers learned a tremendous amount," says
Kuhl. "They were as good at hearing the sound distinctions of Chinese
as babies growing up in Taiwan who had been listening for ten months. So the
first experiment convinced us that the baby brain is like a computer, calculating
information as they listen to us speak."
The results of the first experiment made Kuhl and her team wonder if the babies
would learn just as well if they were watching TV or listening to a tape.
They didn't. "In the second experiment, exposure to the DVDs, the television
films of the speakers talking—the same speakers, the same material—the
babies learned nothing," says Kuhl. "There was no effective exposure
either to the audio-visual tapes or to the audiotape alone."
Kuhl believes this difference between learning from
a person and learning from a machine indicates that social interaction plays
an important role in the learning process. "The second experiment is,
in a sense, a kind of warning to us that learning is constrained in some interesting
respects. You don’t just learn anything. You can’t just expose
children to things on DVD and audiotape and expect that their brains are automatically
taking up that information. And in evolution, that may have been a pretty
important thing. You learn from other human beings who are like yourself.
You don’t learn birdcalls and you don’t learn door slams and you
don’t learn other irrelevant things either. Perhaps the social brain
is a kind of gatekeeper to learning."
Kuhl says that one of the most significant things the research demonstrates
is how integrated our brains are. "We sometimes think of our brains as
separated into modules or pieces, one of which works on language, one of which
works on social, another works on math, and another, if you’re a physicist,
works on physics. What these studies tend to show is that the brains, particularly
of infants and young children, are very integrated. All parts of your brain
are communicating with all other parts. It demonstrates that in learning…infants
and children will use every piece of information they can glean from the environment.
And learning is very biased by the original conditions under which that learning
was forged in evolution."
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