University of Pennsylvania psychologists say that early vocabulary improvement appears to have more to do with the "quality" of the interactions in which the words are used rather than the sheer quantity of speech directed at young children.
In previous research, John Trueswell and Lila Gleitman discovered that children learn words in what might be described as a "eureka" moment - highly informative examples of speech that clearly connect the word to the thing it refers to.
Trueswell and Gleitman suspected these highly informative examples would matter much more than the sheer amount of talk in the home when it came to which children learned more words. To determine if this was the case, they set out to track the long-term effects of these examples, seeing if children who had been exposed to them more often did better on a vocabulary test three years later.
The researchers found a surprising amount of variability: the parents who provided the highest rate of highly informative examples did so 38 percent of the time, while those who provided the lowest rate did so only 4 percent of the time. "This means that some parents are providing 10 times as much highly informative learning instances as others," Gleitman said.
The effect of this discrepancy was clear when the researchers tracked how well each of the children did on a standard vocabulary test three years later. The more frequently a child heard highly informative examples of speech, the better he or she did on these tests.
"We see that the more an environment maximizes the 'here and nowness' of speech, such as when a parent is gesturing or looking at the object in question, the more likely it is that an interaction will be highly informative," Gleitman noted.
Increasing the quantity of speech was also beneficial but only because it increased the number of chances parents had to provide highly informative examples.
"Fortunately, low-informative instances seem to be ignored," Trueswell explained. "By talking to children more, it's not as if you're giving them bad data, you're only increasing the opportunity to find those nuggets."
While the exact mechanisms that lead to a particular bit of speech being highly informative will need to be determined in future research, the Penn team's study shows how these quality examples can have an overriding and lasting effect on an important stage of a child's development.
"You can see this effect even with all the variations in their lives and personalities," Gleitman said. "Through all of that noise, the signal of a linear relationship between these highly informative examples and their children's performance on that vocabulary test three years later shines through."
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Source: University of Pennsylvania