Babbling babies read adults' lips: infants shift focus from eyes to mouth as they learn to talk.
As infants start babbling at around age 6 months in preparation for talking, they shift from focusing on adults' eyes to paying special attention to speakers' mouths, a new study finds.
As tots become able to blurt out words and simple statements at age 1, they go back to concentrating on adults' eyes, say psychologist David Lewkowicz and graduate student Amy Hansen-Tift, both of Florida Atlantic University in Boca Raton. Whereas babbling babies match up what adults say with how they say it, budding talkers can afford to look for communication signals in speakers' eyes, the scientists propose online January 17 in the Proceedings of the National Academy of Sciences.
"Babies start to lip-read when they learn to babble," Lewkowicz says. "At that time, infants respond to what they see and hear as a unified stimulus."
Lewkowicz and Hansen-Tift tested 179 infants from English-speaking families at age 4, 6, 8, 10 or 12 months. Special devices tracked where babies looked when shown videos of women speaking English or a foreign language--in this case, Spanish.
From age 8 months to 1 year, babbling babies read the lips of both English and Spanish speakers, the researchers say. Nascent talkers shifted to looking mainly at the eyes of an English speaker, but continued to home in on the mouth of a woman speaking the unfamiliar language of Spanish.
The researchers also report that infants' pupils increasingly dilated between ages 8 months and 1 year in response to Spanish speakers, a sign of surprise at encountering unfamiliar speech.
By 2 years of age, children with autism avoid eye contact and focus on speakers' mouths. The new findings raise the possibility of identifying kids headed for this developmental disorder even earlier, Lewkowicz says.
But it hasn't yet been demonstrated that children who continue to look at the mouths of native-language speakers after age 1 develop autism or other communication problems more frequently than those who shift to looking at speakers' eyes, cautions autism researcher Rhea Paul of the Yale Child
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|Date:||Feb 11, 2012|
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