Infants learn language not merely by listening to what other people say but also by lip reading, according to a recent research.

The study published in the Proceedings of the National Academy of Sciences on Monday has defied conventional belief that babies learn to speak through sound alone.

The finding could provide vital clues to understanding the condition of autism and could even lead to earlier diagnosis and intervention.

For the research, scientists from Florida Atlantic University studied a group of infants aged between four to 12 months and a group of adults for comparison.

The babies were given videos to watch in either English or Spanish, which is a language foreign to them. With the help of an eye tracker device, the researchers could establish where the infants' pupils moved when they saw and heard the video.

Making eye contact is the most powerful mode of establishing a communicative link between humans. During the early part of their lives, infants learn rapidly that looking at the eyes of the person talking conveys significant information.

Researchers discovered that at around the age of six months, babies start shifting from this intent eye gaze of early infancy to studying mouths when people talk to them.

The baby in order to imitate you has to figure out how to shape their lips to make that particular sound they're hearing, the Huffington Post quoted developmental psychologist David Lewkowicz of Florida Atlantic University, who led the study being published Monday. It's an incredibly complex process.

This data could help in understanding autism in children as well. Autistic children at age two concentrate more on the lips of the speaker than the eyes. This determines that paying attention to the mouth is the normal pattern of development at the age of one. This comparision could assist in recognizing autism at an earlier age.

Although autism diagnosis is not so easy to streamline and there is need for more study, the new research could reportedly assist in providing six months of earlier intervention for autism, which currently affects around 1 in 110 children in the United States (according to the Centers for Disease Control and Prevention).