Babies may understand more than parents realize

December 31, 1998
Web posted at: 9:54 p.m. EST (0254 GMT)

WASHINGTON (CNN) -- A new study shows that babies just 7 months old may be aware of how sentences are organized and can pick specific words out of fluent speech even before they can talk.

The findings, reported in the latest issue of the journal Science, indicate that children may be born hard-wired to learn language and could lead to earlier diagnosis of language disorders.

"Infants don't start at an arbitrary point. They come into the world in the first six months of life with some ability to perceive differences between speech sounds that occur in the world's languages," said Peter Jusczyk of the Johns Hopkins Medical School, one of the researchers.

In their study, the researchers created a series of three-word sentences with specific structures and then tested the infants to see if they could recognize changes in the sentence structure.

The words were actually an artificial language that conveyed no meaning. The study was to determine if the babies could recognize a pattern in the way the words were arranged, said Gary Marcus, a New York University psychologist who led the study.

For instance, one sentence structure would be "Li ti li" or "Wo fe wo." This is known as an ABA pattern. Another sentence structure could be "Wo fe fe" or "Li ti ti" and this would be an ABB pattern.

A baby looks at the light during a test

To test the infants, the researchers played a recording of one structure for two minutes to train the babies in that pattern. Then the babies for two minutes heard a series that mixed one pattern with another.

The recordings were played on speakers that were equipped with lights that blinked on whenever the sentences were played. The results were based on how 45 babies in the study reacted to the lights.

Sentence structures that were new tended to capture attention longer than structures that had already been heard, said Marcus. This method has been widely used to study the thinking processes of infants.

"They looked longer when the sounds came from a new grammar (or sentence structure) compared to when the old grammar was played," said Marcus. "There was a difference of about nine seconds."

Jusczyk also found that when infants were read passages with familiar words, they listened longer, indicating that they had the ability to pick those words out of fluent speech. Children also recognized that certain words seemed to occur together, such as "the" before "cat."

He used a similar experiment to show that by 18 months, children can pick out grammatically correct sentences, even though a child of that age may be able to say only two words together.

Marcus said the researchers will now seek to determine if babies who do poorly on these tests later demonstrate problems in talking or in understanding speech. He suspects . that difficulty in recognizing spoken sentence structure may be a factor for children who are late in learning to talk.

Medical Correspondent Rhonda Rowland contributed to this report.