About 45% of humans experience contagious yawning. Even seeing an animal yawn can trigger the same in a human.

Mid-descent during a plane ride, Molly Helt, a clinical psychology researcher at the University of Connecticut, tried to encourage her autistic son to relieve the pressure change by yawning in front of him; however, he did not yawn.

This led Helt to conduct a comparison study between 28 children with autism and 63 children without.

The experiment involved observation of their reactions when observing someone read them a story and pausing to yawn.

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

She found that yawning requires empathy, or an understanding of someone else’s feelings, and most autistic children will not copy this behavior.

Full story at MSN.com.