Yawning is contagious, and can be caused by tiredness, stress, and watching other people yawning a phenomenon known as social yawning. Autistic children, however are immune to this contagion.
Shared behaviour is a form of empathy exhibited by many social groups, researchers speculate that it strengthens the bonds between humans and animals in their social circle, grooming, being the predominant form of communication between higher mammals (monkeys).
Children with autism apparently don’t respond to social yawning, however, prompting some researchers to blame their well-chronicled struggle with empathy.
The researchers say children with Autism miss those cues because they avoid looking at people’s faces. But that may not entirely explain it. For example, a small 2009 study found that developing children yawn even when they’ve only heard another person do so, but children with autism do not.
In the new study, the researchers set up two experiments to determine whether children with autism look at others’ faces enough to catch a social yawn.
In the first test, 26 children with autism and 46 controls wore eye-tracking devices while watching video clips of people either yawning or remaining still. The researchers asked the children to count how many people in the clips were wearing glasses to make sure they looked at the people’s eyes. The video showed the person yawning only when the eye tracker verified that the children had fixed their gaze on the eyes.
In the second test, 22 children with autism and 29 controls watched video clips, this time counting how many of the people in the videos had beards. Once again, the yawning sequence played only when the children focused on the mouth area.
Overall, about 30 percent of the children with autism yawned in response to the videos of yawning people — a rate equivalent to that of controls. This suggests it’s not an inherent lack of empathy in children with autism that’s to blame for their lack of social yawning, but rather their inattention to facial cues. When they are directed to look at faces, as in these experiments, they behave just as controls do.
Researchers say this warrants further study with a larger test group, also tests on people and children diagnosed bipolar and schizophrenic.