Baby Talk
Learning language, researchers are finding, is an astonishing act of brain computation--and it's performed by people too young to tie their shoes
The debate over how much of language is already vested in a child at birth is far from settled, but new linguistic research already is transforming traditional views of how the human brain works and how language evolved. "This debate has completely changed the way we view the brain," says Elissa Newport, a psycholinguist at the University of Rochester in New York. Far from being an orderly, computerlike machine that methodically calculates step by step, the brain is now seen as working more like a beehive, its swarm of interconnected neurons sending signals back and forth at lightning speed. An infant's brain, it turns out, is capable of taking in enormous amounts of information and finding the regular patterns contained within it. Geneticists and linguists recently have begun to challenge the common-sense assumption that intelligence and language are inextricably linked, through research on a rare genetic disorder called Williams syndrome, which can seriously impair cognition while leaving language nearly intact (box, Page 52). Increasingly sophisticated technologies such as magnetic resonance imaging are allowing researchers to watch the brain in action, revealing that language literally sculpts and reorganizes the connections within it as a child grows.
The path leading to language begins even before birth, when a developing fetus is bathed in the muffled sound of its mother's voice in the womb. Newborn babies prefer their mothers' voices over those of their fathers or other women, and researchers recently have found that when very young babies hear a recording of their mothers' native language, they will suck more vigorously on a pacifier than when they hear a recording of another tongue.
At first, infants respond only to the prosody--the cadence, rhythm, and pitch--of their mothers' speech, not the words. But soon enough they home in on the actual sounds that are typical of their parents' language. Every language uses a different assortment of sounds, called phonemes, which combine to make syllables. (In English, for example, the consonant sound "b" and the vowel sound "a" are both phonemes, which combine for the syllable ba, as in banana.) To an adult, simply perceiving, much less pronouncing, the phonemes of a foreign language can seem impossible. In English, the p of pat is "aspirated," or produced with a puff of air; the p of spot or tap is unaspirated. In English, the two p's are considered the same; therefore it is hard for English speakers to recognize that in many other languages the two p's are two different phonemes. Japanese speakers have trouble distinguishing between the "l" and "r" sounds of English, since in Japanese they don't count as separate sounds.
Polyglot tots. Infants can perceive the entire range of phonemes, according to Janet Werker and Richard Tees, psychologists at the University of British Columbia in Canada. Werker and Tees found that the brains of 4-month-old babies respond to every phoneme uttered in languages as diverse as Hindi and Nthlakampx, a Northwest American Indian language containing numerous consonant combinations that can sound to a nonnative speaker like a drop of water hitting an empty bucket. By the time babies are 10 months to a year old, however, they have begun to focus on the distinctions among phonemes of their native language and to ignore the differences among foreign sounds. Children don't lose the ability to distinguish the sounds of a foreign language; they simply don't pay attention to them. This allows them to learn more quickly the syllables and words of their native tongue.
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