Babies understand basic words at a much earlier age than previously thought, US scientists claimed.
University of Pennsylvania researchers found that infants aged between six and nine months can grasp the meaning of common words months before they can speak them.
It was widely believed that babies can comprehend elements of the sounds of their native language but not their meaning.
In the first demonstration that babies can understand such words, the researchers tested 33 six- to nine-month-old babies in controlled conditions.
The study involved showing the babies a screen with images of two objects and tracking their eye movements when a parent asked them about one of the objects, such as "Where is the apple?"
The results, published in the journal Proceedings of the National Academy of Sciences, found that the babies were more likely to fix their gaze on the correct picture, 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," lead researcher Dr. Daniel Swingley said. "Our study is different in looking at more generic words, words that refer to categories."
Swingley added, "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. 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."