WEDNESDAY, Aug. 6 (HealthDay News) -- While poor eye contact has long been a suspected sign of possible autism, researchers at Yale University have used "eye-mapping technology" to prove that children with autism don't make eye contact like normally developing children do.

Published in the August issue of the Archives of General Psychiatry, the new research found that children with autism spent more time looking at an adult's mouth instead of gazing into the eyes.

"Just as the eyes are the window to the soul, the eyes are also a window into social development," said study senior author Ami Klin, director of the autism program at Yale University School of Medicine.

Klin said that by using eye-mapping technology, it's possible that a vulnerability for autism could be identified much earlier than is currently possible. And, he said, "The earlier we are able to identify children, the better it is, because early interventions make a difference in optimizing children's outcomes."

It's estimated that autism, a developmental disorder that disrupts communication and social interaction, affects about 3.4 out of every 1,000 children between the ages of 3 and 10, according to the U.S. National Institute of Mental Health (NIMH). Parents are generally the first to notice early signs of autism. The NIMH says that some known early signs that may indicate an autism spectrum disorder in a child include:

• By age 1, doesn't babble, point or gesture.
• Doesn't speak a single word by 16 months.
• By age 2, hasn't combined two words.
• Seems to lose language skills.
• Interacts poorly socially.
• Doesn't respond to his or her name.
• Doesn't smile.
• Makes poor eye contact.
• Doesn't appear to know how to play with toys and may repeatedly line up toys or other objects.

For the new study, Klin and his colleagues, including Warren Jones, compared 15 children with autism to 36 typically developing children, and to another 15 children who were developmentally delayed but not autistic. All of the children were 2 years old.

The children were shown 10 videos of adults looking directly into the camera and mimicking caregiving and playing with the child. While the videos were running, the researchers used eye tracking to assess the child's visual fixation patterns.

They found that children with autism spent significantly less time looking at the eyes than did typically developing children or the developmentally delayed group. Autistic children looked at the eyes about 30 percent of the time, compared to nearly 55 percent for both of the other groups.

Children with autism spent almost 40 percent of the time looking at the mouth area, while children in the other groups only spent about 24 percent of the time looking at this area.

Eye fixation in children with autism also appeared to predict the level of social disability. Those who had greater social disabilities spent less time looking at the eye area, according to the study.

"We've always had a sense that children with autism don't make eye contact, but this study confirms it in a higher-tech way," said Cynthia Johnson, director of the autism center at Children's Hospital of Pittsburgh.

Johnson said she'd like to see this study confirmed in a larger group of children. Klin added that he and his colleagues are currently conducting a prospective study in children at a higher risk of autism to see "if there's a derailment in the process of social engagement," and if so, when that happens.

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