Social yawning—when one person yawns and a whole group of people is launched into a round of yawning—has long been thought to be a function of empathy, possibly because yawning could strengthen the bonds of a group. Another seeming supporter of the social-yawning-through-empathy theory was that people with autism do not respond to social yawning and it is commonly accepted that people with autism spectrum disorders (ASD) lack empathy. However, research from a Japanese study published in July indicates that children with ASD miss out on social yawning not because they lack empathy, but because they fail to notice the critical facial cues that make yawning so contagious.

The study comprised two tests designed to identify the elements of the face that communicate yawning to others. The first test utilized data from 26 children with ASD and 46 control children. The children were equipped with eye-tracking devices and asked to count the number of people wearing glasses in clips that showed faces—some yawning and some not. The second test involved 22 children with ASD and 29 control children. The children were also fitted with eye-tracking devices, but they were asked to count the number of people in the clips who had beards. Asking the children to count glasses and beards ensured that they focused on the correct area of the face and would notice the relevant facial cues that could trigger a yawn.

In both tests, the ASD children yawned in response to approximately 30% of yawning clips, which is about the same rate that the control children yawned. The results suggest that empathy is not what causes (or prevents) people with ASD from yawning, but rather a lack of attention to facial information. This study demonstrates that when people with ASD focus on yawning faces, they yawn as much as anyone.

This study also found that focusing on either the eyes or the mouth results in about the same amount of yawning. The researchers had suspected that eye cues would generate more yawns than mouth cues. However, it is possible, according to the researchers, that the children were looking at eyes rather than mouths, or that there is some other aspect to social yawning that was not measured by this study.

This research is published in the journal Autism Research and Treatment.

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