Have you ever noticed that yawning is so contagious it can spread round a room like a Mexican wave? Scientists still aren't in agreement as to why this happens but one idea is that the phenomenon depends on our capacity for empathy. This finds support in a new study showing for the first time that children with Autistic Spectrum Disorder, in whom empathy is believed to be impaired, are immune to the contagious effects of yawning.
Twenty-four children diagnosed with autism spectrum disorder - mostly boys aged between 7 and 15 years - and twenty-five age-matched non-autistic children, watched a series of 7-second videos showing people yawning. Control videos showed people opening their mouths but not yawning. Between each video, one-minute long silent cartoons kept the children's attention.
Footage of the children taken while they were watching the videos showed, as expected, that the non-autistic children yawned more during and after seeing a video of a person yawning, than after watching a control video. By contrast, the children with autism yawned no more after seeing a yawn video than after a control video – they appeared to be immune to the contagious effects of yawning. This remained true even after the researchers controlled for the effects of age and intelligence.
Past research has found that seeing the eye region of someone yawn is key to the yawn's contagious effects. So perhaps the fact that people with autism are known to focus more on the mouth region of people's faces, rather than the eyes, could partly explain the current findings.
Atsushi Senju and colleagues said their results “support the claim that contagious yawning and the capacity of empathy share common neural and cognitive mechanisms.” They added it would be interesting for future research to look at whether contagious yawning is impaired in other conditions in which empathy is compromised, such as psychopathy or frontal-temporal dementia.
Senju, A., Maeda, M., Kikuchi, Y., Hasegawa, T., Tojo, Y. & Osanai, H. (In Press). Absence of contagious yawning in children with autistic spectrum disorder. Biological Letters.
Link to full-text pdf.