Study examines infant learning

The Associated Press PHILADELPHIA (AP) -- Baby talk may sound like mere babble, but that doesn't mean infants aren't learning words. Research into infants and language suggests that babies begin to pick up speech and can even tell apart different languages at a very early age. By 7 1/2 months, it seems, a baby can consistently tell the difference between some sound-alike words, such as ''cut'' and ''cup.'' They are trying to separate and identify the milestones in learning speech, such as when babies can tell the cadence of one language from another, when they start to identify words in the babble of sound and when they begin to form these words into sentences. Gleitman explained that until about age 18 months, babies learn roughly one word every three days. Even then, they often are a little hazy about what they mean. The infant who gleefully yells ''Daddy!'' to every man on the street is just one potentially embarrassing example of this. However, by the time they are a-year-and-a-half, babies begin to put together their first simple two-word sentences. And Gleitman said research suggests this acquisition of grammar is the key to rapidly learning new words. From then on, Gleitman said, people typically learn 10 words a day, 3,500 or so words a year, until about age 30. After that, people continue to build their vocabularies, but the process slows, probably because most of the easy words have been learned. Folks typically level off at about 80,000 to 100,000 words. However, she said there is little point into trying to cram vocabulary into very young children. They learn the basics of speech at about the same speed, no matter what their parents do. The children of silent types pick up language just as fast as fast as non-stop talkers' babies do. ''In the first three years, you can't go wrong unless you lock the kid in a dark closet,'' she said. Peter Jusczyk, a psychology professor at Johns Hopkins University, said his research suggests that infants begin to pick out individual words from sentences between 7 and 8 months of age. Further, they seem to be storing away words in memory at this age, building up a vocabulary, even when no particular effort has been made to teach them what words mean. At this age, it also appears that infants learn to tell languages apart, even between such similar-sounding tongues as Dutch and English. For instance, they apparently begin to recognize that when words begin with ''kn,'' the ''k'' is pronounced in Dutch but is silent in English. Jusczyk and colleagues found that a 6-month-old baby will listen to lists of Dutch and English words with equal attention. But by 9 months, babies listen significantly longer to lists spoken in their parents' language.