A previously held consensus that young infants did not comprehend words for many common objects appears to have been unseated by University of Pennsylvania psychologists Elika Bergelson and Daniel Swingley. In research focused on 6-to-9-month-old babies, the researchers demonstrated that the infants learned the meanings of words for foods and body parts through their daily experience with language. Previously, most psychologists believed word comprehension didn't emerge until closer to a child's first birthday. The findings appear in the Proceedings of the National Academy of Sciences.
There have been few attempts to determine just when infants begin understanding what is meant by specific words. The belief that infants do not comprehend language for most of the first year is easy to understand, given that infants do not often speak in words, or even gesture meaningfully, before 10 or 11 months.
The infants in Bergelson's and Swingley's study completed two different kinds of test. In the first, a child faced a screen on which there were images of one food item and one body part. The child heard a statement such as, "Look at the apple," or, "Where's the apple?" and an eye-tracking device then followed the child's gaze.
The second kind of test had the same set-up, except that, instead of the screen displaying a food item and a body part, it displayed objects in natural contexts, such as a few foods laid out on a table, or a human figure. For both kinds of test, the question was whether hearing a word for something on the screen would lead children to look at that object more, indicating that they understood the word.
As part of their analysis, Bergelson and Swingley corrected for eye movements from non-verbal cues. Bergelson pointed out that to infants some objects are more interesting than others, whatever was said. "So if you have a boring cup and a really colorful cup, they're going to look at the more interesting thing, all else being equal."
To eliminate this potential source of error, the researchers subtracted the amount of time that the babies gazed at a given object when it was not being named from the time they looked when it was named. "The idea there is that they have some sort of baseline for how much they like to look at the thing, so when you take that away, what's left is their word recognition," Bergelson explained.
In both tests, the researchers found that the 6- to 9-month-old babies fixed their gaze more on the picture that was named than on the other image or images, indicating that they understood that the word was associated with the appropriate object. "There had been a few demonstrations of understanding before, involving words like mommy and daddy," Swingley said. "Our study is different in looking at more generic words, words that refer to categories."
The study's novel results contribute to an ongoing debate about infant language acquisition and cognitive development. "I think it's surprising in the sense that the kids at this age aren't saying anything, they're not pointing, they're not walking," Bergelson said. "But actually, under the surface, they're trying to put together the things in the world with the words that go with them."
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Source: University of Pennsylvania