March 26, 2010 -- Words may have special meaning for babies long before they are able to speak.
A new study suggests talking to babies as young as 3 months old influences their cognitive development and helps the brain learn to form categories.
Researchers found infants who learned to associate words rather than sounds with pictures of objects were better able to perform a simple categorization task.
"These findings offer the earliest evidence to date for a link between words and object categories," says researcher Susan Hespos, associate professor of psychology at Northwestern University, in a news release.
Researchers say the results add to growing evidence that it's important to talk to babies from an early age to foster infant development and cognition.
In the study, published in Child Development, researchers compared the effect of words vs. sounds on infant cognition skills in a group of 46 3- to 4-month old infants.
All of the infants were shown a series of pictures, such as a fish, that were paired with either words or beeps. Infants in the word group were told things like, "Look at the toma!" --a made-up word for fish -- while they viewed each picture. Infants in the other group heard a series of beeps carefully matched to the word phrases for tone and duration.
Both groups were then tested on their categorization skills by being shown a picture of a new fish and a dinosaur side by side while researchers measured how long they looked at each image. If the infants had formed a familiar category in their brain with the fish from the previous exercise, they would look at one picture longer than the other.
The results showed infants who heard words had formed the category for fish, and those who heard sounds did not.
"We suspect that human speech, and perhaps especially infant-directed speech, engenders in young infants a kind of attention to the surrounding objects that promotes categorization," says researcher Sandra Waxman, professor of psychology at Northwestern University, in the news release. "We proposed that over time, this general attentional effect would become more refined, as infants begin to cull individual words from fluent speech, to distinguish among individual words and kinds of words, and to map those words to meaning."