Babies can understand many words sooner than they can actually say them, a recent study indicates.
Researchers from the University of Pennsylvania say six- to nine-month old babies learn the meaning of the words for certain foods and body parts through their daily exposure to language. The general view among most psychologists is that this type of word comprehension is not possible until a child is closer to one year.
"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," said the study's coauthor, Elika Bergelson, a doctoral student, University of Pennsylvania department of psychology. "But actually, under the surface, they're trying to put together the things in the world with the words that go with them."
How The Study Worked
In conducting the study, researchers had 33 babies between six and nine months old view a screen with a picture of a food item and a body part while sitting with their parents. The parents were given phrases to say to the child, asking them to find the apple, for instance. An eye-tracking device revealed the babies' responses to the phrases.
In a second test, the children went through the same process but saw pictures of typical food scenes and a whole person, not just body parts.
After taking into account possible reasons for errors or distraction among the babies, the researchers compared the responses of the six- to nine-month-old infants with those of 50 other babies ranging from 10 to 20 months of age.
In both tests, the researchers found the six-to-nine-month-olds looked more often at the picture that was named than any other images. The researchers argued this was a sign that they knew what the word meant.
"There had been a few demonstrations of understanding before, involving words like 'mommy' and 'daddy," said study co-author Daniel Swingley, PhD, an associate professor in the psychology department at University of Pennsylvania. "Our study is different in looking at more generic words, words that refer to categories.
Bergelson added, "We're testing things that look different every time you see them. There's some variety in apples and noses, and 'nose doesn't just mean your nose, it could mean anybody's nose. This is one of the things that makes word learning complicated: Words often refer to categories, not just individuals."
The study's authors said babies at eight and nine months performed no better than six-and seven-month-old infants. They said no significant improvement was seen until the children reached about 14 months of age. They could not explain exactly why performance did not improve for so long
Their study was published online in the Proceedings of the National Academy of Sciences.
"I think this study presents a great message to parents: You can talk to your babies and they're going to understand a bit of what you're saying." Dr. Swingley concluded. "They're not going to give us back witty repartee, but they understand some of it. And the more they know, the more they can build on what they know."