May 25, 2007 -- So you're sitting on the floor with your 4-month-old son. You smile at him and he smiles back, that wonderful incandescent smile that babies learn around that age. You burst with love.
And you say what's truly in your heart:
If you're lucky, you'll get a confused stare. The kind that says, "Have you lost your mind?" If you're less lucky, he'll scream bloody murder. And all you did was ask him, "Are you hungry?"
Very Sharp, and Very Young
Psychologists at the University of British Columbia in Canada have found that babies -- just 4 to 6 months old -- seem already able to tell the difference between different languages. If a baby girl lives in an English-speaking household, she'll react differently to a video clip in English than, say, one in French.
Some of this has been known for years. But the Canadian researchers found that young babies could even tell the difference between languages if they couldn't hear the words. They could pick up the subtle differences in the movements of an adult's face.
Ask yourself if you'd be able to do that.
"Babies pay attention to any information they might need when they're very young," said Dr. Janet Werker, one of the leaders of the study that appears in this week's edition of the journal Science. "What happens is that they learn only to hold onto the information that's needed."
'Le Petit Prince'
Werker and her colleagues recruited babies and their parents, and sat them down in a pleasantly darkened room with a TV screen. On the screen the babies were shown silent video clips of a woman reading passages from "The Little Prince," the classic children's book by Antoine de Saint-Exupéry. The woman went back and forth between English and the original French (the book was first published in 1943 as "Le Petit Prince").
When the language switch happened, the babies perked up and watched more intently. Child psychologists take that as a cue that the child has realized there's been a change.
"We expect that if the baby has noticed the language switch," said Whitney Weikum, who conducted the research with Werker, "they're going to be like, 'Hey, this is new, this is interesting, I'm going to start watching the screen again.'"
This happened, consistently, even though the babies were not played the sound that went with the picture -- and, presumably, wouldn't have understood a word of it anyhow. All they had to go on were the facial expressions of the woman on the screen, which changed subtly when she switched between French and English.
Why does this matter, beyond being a matter of curiosity? Werker said it may provide clues about how human beings have evolved to survive. Even at the earliest stages of life, a baby is learning to prioritize.
"They stop paying attention to what they don't need. If someone's speaking to them in a foreign language, it's probably not going to be useful to them," Werker said.
In the meantime, the experiment suggests something to new parents: Watch what you say around the kids.
Todd Battis of CTV News in Vancouver, British Columbia contributed to this story.