When Yawning Is Catching And When It Is Not

 

If somebody yawns it is likely that half the people nearby will probably do the same - a occurrence we call contagious yawning. However, children with severe autism miss the subtle cues that elicit collective yawning, say researchers from the University of Connecticut in a study published in the medical journal Child Development. The writers say their findings may help experts determine why people with autism find it harder to form close emotional bonds with others.

The investigators also found that individuals with milder variants of ASD (autism spectrum disorder) were more likely to yawn contagiously that those with more severe autism. They also found that most children with or without autism under the age of four years are much less likely to be contagiously yawning.

Molly Helt, a doctoral student in the Department of Psychology, College of Liberal Arts and Sciences, University of Connecticut, and the study's primary author, wrote:

This lends support to the idea that the social mind develops over time through a process of mimicry and feedback. If we can identify a lack of mimicry of facial expressions early, it could be an identifier of potential neurodevelopment disorders such as autism.

Contagious yawning is a form of mimicry, something apparently unique to humans and chimpanzees - researchers believe we acquire it over time. It is different from spontaneous yawning, which all vertebrates do. Spontaneous yawning has been observed in fetuses in the womb.

Helt's study differs from previous ones in that it included live stimulis - human experimenters - as opposed to just exposing participants to videos of people yawning. The study compared children with severe autism, children diagnosed with a Pervasive Development Disorder, and kids with neither (typically developing children).

The study was divided into two parts:

The first study - including only typically developing children

120 typically developing children aged between 1 and 6 years were recruited from local daycare centers. They sat in a quiet room facing the experimenter who sat on the other side of the room. The experimenter read a story out loud, one of four stories which depended on the age of the children, for a total of 12 minutes. During the last 10 minutes of the reading the experimenter yawned four times, and recorded (discreetly) whether any child yawned within 90 seconds. About 40% of the reading sessions were randomly recorded on video and coded by two independent raters for reliability.

If a child yawned in response to one or more of the experimenter's stimulus yawns, he/she was considered a contagious yawner. The experimenter did not include in the analysis children who were not looking the experimenter most of the time.

The authors report that children under four years of age were much less likely to engage in contagious yawning, compared to the older kids.

• There were 20 children aged just 1 year - none of them yawned.
• There were 20 children aged 2 years - 1 of them yawned.
• There were 20 children aged 3 years - 2 of them yawned.
There were 20 children aged 4 years - 7 of them yawned.
• There were 20 children aged 5/6 years - 8 of them yawned