"My Baby Made Me Do It!"
Perhaps the best studied -- though not altogether understood -- parental behavior is the way we speak to infants. "Parentese" spans virtually every culture and language. Its most conspicuous traits: elevated pitch (as much as an octave higher than normal), drawn-out vowels, and a general slowing of speech to at least half the rate of normal conversation. It's a speech pattern that tends to grate on older kids and adults who aren't parents. So why do infants love it so?
For starters, babies, especially newborns, don't hear well at low frequencies. "Babies are much better at picking out higher-pitched sounds from surrounding noise than lower pitches," says John Colombo, Ph.D., a developmental psychologist at the University of Kansas.
Even when infants can hear adult conversation clearly, they still show a preference for baby talk, says neuroscientist Patricia Kuhl, Ph.D., of the University of Washington. Nineteen years ago, Kuhl set up a now-classic experiment in which she allowed infants to control whether they listened to parentese or adult-style conversation. The babies consistently preferred baby talk. Moreover, experts believe this would hold true even if the baby talker spoke a language not heard in the infant's home.
Kuhl concluded that the universal exaggeration of vowels and slowing down of speech help babies learn the phonetic elements of speech, perhaps even the particular intonations of what will become their native tongue.
Researchers at the Temple University Infant Lab, in Ambler, Pennsylvania, have noted that parents (at least, English-speaking ones) imbue their parentese with a singsong quality that emphasizes the ends of sentences, and this may further help babies parse speech into its crucial elements, says Kathy Hirsh-Pasek, Ph.D., coauthor of How Babies Talk. "Anyone who's learned a foreign language knows that the greatest challenge is simply to separate out the words, phrases, and sentences. That's exactly what baby talk does."
Still, experts agree that teaching children how to use words is unlikely to be the whole story. Given that people regularly lapse into baby talk with pets and romantic partners, something about baby talk conveys warmth and caring. "Long before babies can pick out individual words, they pick up on affect," explains Hirsh-Pasek. "You can say something not at all nice to a baby in a friendly tone and that baby will smile and gurgle. Say something nice in an angry tone, and the baby will cry."
This isn't to say that parents who somehow resist the urge to baby talk will produce language-disabled children, says American University linguist Naomi Baron, Ph.D., author of Growing Up With Language: How Children Learn to Talk. "Refusing to talk in a high voice is harmless enough," she says. "What's crucial is that parents and caregivers talk and listen to babies as much as possible, because that's how infants learn how we communicate."