Contrary to popular belief, speech development is not a linear evolution. It is multidimensional and marked by a series of key stages. Since early childhood is a time when mom and dad are on the lookout for all the new exploits of their offspring, learning about the upcoming stages is a good way to fully enjoy each milestone. There are several stages to language development. Before making sounds, babies first learn to perceive those they hear. They will then start trying to communicate through means other than crying.
From about 6 weeks old to 3 or 4 months old, babies babble and experiment with different sounds, starting with vowels. Then, from 6 and 10 months old, they start trying out syllables, like ma-ma-ma, da-da-da and ba-ba-ba.
In addition to babbling, baby simultaneously develops other subtle but important skills: he or she begins to follow an adult's gaze to focus on the same object. This opens the door to a new way to communicate: if baby can be interested in what an adult is looking at, the opposite is just as true! This marks the start of the pointing stage. Then, between 9 and 12 months, they also learn other conventional signs, such as waving bye-bye, nodding or shaking their head to say yes or no, as well as reaching out to be held.
But at 6 and 10 months, they start to narrow their range. They grow oblivious to foreign phonemes while staying attuned to whatever sounds the speakers around them are using. Acquiring a set of phonemes is a first step toward language, but just a baby step. To start decoding speech, you have to recognize words. And as anyone listening to a foreign conversation quickly discovers, people don't talk one Real-life language-even the melodious "parentese" that parents use with infants--consists mainly of nonstop streams of sound.
So how do babies suss out the boundaries? Long before they recognize words, says Peter Jusczyk, a cognitive scientist at Johns Hopkins University, they get a feel for how their language uses phonemes to launch syllables. By the time they're 7 months old, American babies are well accustomed to hearing t joined with r as in tram and c with l as in clam , but they've been spared combinations like db, gd, kt, ts and ng, all of which occur in other languages.
And once they have an ear for syllables, word boundaries become less mysterious. As children start to recognize and play with syllables, they also pick up on the metrical patterns among them. French words tend to end with a stressed syllable.
The majority of English words-and virtually all of the mommy-daddy-baby-doggie diminutives that parents heap on children--have the accented syllable up front. Until they're 6 months old, American babies are no more responsive to words like bigger than they are to words like guitar.
But Jusczyk has found that 6- to month-olds develop a clear bias for words with first-syllable accents. They suck more vigorously when they hear such words, regardless of whether they're read from lists or tucked into streams of normal speech. The implication is that children less than a year old hear speech not as a blur of sound but as a series of distinct but meaningless words.
Amid their streams of sweet, melodic gibberish, they start to name things-ball, cup, bottle, doggie. And even those who don't speak for a while often gesture to show off their mastery of the nose, eyes, ears and toes.
These may seem small steps; after all, most 1-year-olds are surrounded by people who insist on pointing and naming every object in sight. But as Pinker observes, making the right connections is a complicated business.
How complicated? Imagine yourself surrounded by people speaking a strange language. A rabbit runs by, and someone shouts, "Gavagai!
Gavagai could refer to that particular creature, or it could have a range of broader meanings, from "four-legged plant eater" to "furry thing in motion. Why don't they spend their lives trying to figure out what words like "rabbit" mean?
Because, says Stanford psychologist Ellen Markman, they come to the game with innate mental biases. Markman has shown that instead of testing endless hypotheses about each word's meaning, kids start from three basic assumptions. First, they figure that labels refer to whole objects, not parts or qualities. Second, they expect labels to denote classes of things cups, balls, rabbits rather than individual items.
Third, they assume that anything with a name can have only one. These assumptions don't always lead directly to the right inference "I'm not a noying," Dennis the Menace once told Mr. Wilson, "I'm a cowboy". But they vastly simplify word learning. In keeping with the "whole object" assumption, a child won't consider a label for "handle" until she has one for "cup.
Words accrue slowly at first. But around the age of 18 months, children's abilities explode. Most start acquiring new words at the phenomenal rate of one every two hours-and for the first time, they start combining them. Children don't all reach these milestones on exactly the same schedule; their development rates can vary by a year or more, and there's no evidence that late talkers end up less fluent than early talkers.
But by their second birthdays, most kids have socked away 1, to 2, words and started tossing around two-word strings such as "no nap," "all wet" or "bottle juice. Once kids can paste two words together, it's not long before they're generating sentences.
Between 24 and 30 months, "no nap" may become "I don't want nap," and "bottle juice" may blossom into "I wnat juice. Between 30 and 36 months, most acquire rules for expressing tense walk versus walked and number house versus houses , often overextending them to produce statements like "I bringed home three mouses.
Although 18 months is a common age for this increase, it can occur in children between the ages of 15 and 24 months. In one study, researchers put five objects in front of children, and one of these objects was completely new to them a garlic press or some other strange kitchen tool.
Fast mapping, along with new skills in being able to put objects in categories, leads to this astonishing vocabulary growth. Huttenlocher, P. Early vocabulary growth: Relation to language input and gender. Developmental Psychology, 27,
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