Molly Helt discovered an interesting aspect of her son's autism somewhat serendipitously, during a plane ride. When the plane descended, in an attempt to help relieve painful pressure in her son's ears, she tried to get him to yawn by yawning right in front of him.

About 45 percent of us yawn when we see someone else yawn, but Helt's yawns had no such effect on her little one.

The observation prompted Helt, a clinical psychology researcher at the University of Connecticut, to investigate the contagious yawning in children with autism.

"Yawning when you see someone else yawn requires empathy, on a certain level," Helt said.

She found that most children with autism are unlikely to copy this behavior, and the finding may help scientists better understand important aspects of human communication and social behavior that children with autism don't experience.

Helt studied 28 children diagnosed with an autism spectrum disorder — a group of disorders associated with developmental disabilities and problems with social interaction and communication — and compared them with 63 children not diagnosed with autism. The children were read a story by a researcher, who paused during the story to yawn.

While listening to the story, 23 percent of the children who were diagnosed with a mild form of autism called Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS) yawned after observing the reader yawn.

Of the children diagnosed with full autistic disorder, none yawned.

The children not diagnosed with autism yawned at a rate near what would be expected for adults – about 43 percent of the time.

"As we interact with another person, we subtly mimic their expressions and posture," Helt told MyHealthNewsDaily, and by observing small, physical changes in a conversation partner, we become emotionally synchronized with them.

This emotional synchronicity usually starts early – research has shown that babies as young as 1 day old will cry when they hear another baby cry, Helt said.

"Autistic kids could be missing out on these critical experiences. They may be quite blind to what others are feeling," she said.

Helt's findings are intriguing, said Dr. Marco Iacoboni, professor of psychiatry and biobehavioral sciences at the University of California, Los Angeles, who was not involved with the study. The results may be explained by mirror neurons, which are special brain cells that fire when you see someone else perform an action, Iacoboni said.

Research has shown that mirror neurons in people with autism do not function as they do in people without autism, and may explain social problems linked to the disorder, he said.

Research has also shown that both empathy and mimicry, both required for contagious yawning, are linked to the functions of mirror neurons, and both are impaired in people with autism.

"The good news is that the functions of mirror neurons may be able to be improved with treatments," Iacoboni said. Researchers at the University of California, Davis, have been working on developing treatments for autism that focus on teaching children how to pay attention to and mimic the actions of others.

"The mirror neurons are there, they're just not working as well as they should," he said.

This article was provided by MyHealthNewsDaily, a sister site to LiveScience.