The Language Explosion

That's not to say language requires no nurture. Children raised in complete silence grow deaf to grammar. "Chelsea," whose correctable hearing problem went untreated until she was 31, eventually learned enough words to hold a job in a vet's office. Yet her expressive powers have never surpassed those of a chimp with a signboard. She says things like "The woman is bus the going" or "I Wanda be drive come." Fortunately, Chelsea is a rare exception. Given even a few words to play with, most kids quickly take flight. "You don't need to have left the Stone Age," Pinker says. "You don't need to be middle class." All you need to be is young.

HOW TO TALK 'PARENTESE' TO YOUR CHILD

People the world over alter their way of speaking when they address infants and toddlers. The effects of "parentese" (originally called "motherese") continue to be hotly debated, but "a number of [its] features are likely to facilitate language learning," says linguist Naomi Baron of The American University. Among them:

Higher pitch captures a child's attention. Speaking more slowly, and with careful enunciation, makes it easier for the baby to distinguish individual words; emphasizing or repeating one word ("Isn't that a huuuuuuge huge doggie?") also helps.

Short utterances help the child grasp grammar more readily than Faulknerian monologues. Don't abandon complex sentences entirely, though: toddlers whose parents use many dependent clauses ("because. . ." and "which. . .") learn to do so earlier than the children of parents who do not.

Repeating a child's utterances ("That's right! It's a birdie") assures her she's been understood. Recasting what the child says ("Want cookie?" "Would you like a cookie?") expands her repertoire. The only aspect of parentese that may impede language development: substituting proper nouns for pronouns ("Does Billy want to swing?"). These are tricky to master (your "you" is my "I"), and toddlers should be exposed to them.