Children with severe autism don’t take part in contagious yawning, according to a new study.
Contagious yawning is different from spontaneous yawning in that it’s a type of mimicry and only acquired once a child is capable of closely reading others’ facial expressions. Severely autistic children, however, miss these subtle cues.
The results of the study could help scientists better understand why autistic individuals have a difficult time forming close emotional bonds with others.
“This lends support to the idea that the social mind develops over time through a process of mimicry and feedback,” says Molly Helt, the study’s lead author and a doctoral student in the department of psychology at the University of Connecticut.
“If we can identify a lack of mimicry of facial expressions early, it could be an identifier of potential neurodevelopment disorders such as autism.”
Earlier studies have observed contagious yawning in children without autism as young as 2 years old (Jean Piaget) and some as late as age 5 (Anderson and Meno). But Helt’s study is novel in that it involves children directly interacting with a live stimulus (human experimenters) rather than being shown videos of people yawning.
It also compared children with both severe autism and those diagnosed with pervasive development disorder, a milder form of autism, against control groups of typically developing children.
Helt’s study, divided into two parts, recruited 120 typically developing children, ages 1 to 6, from local daycares. The children sat across from the experimenter in a quiet room. The experimenter then read aloud one to four stories (depending on the children’s age) for a total reading time of 12 minutes.
Within the last 10 minutes of reading, the experimenter stopped to yawn four times and secretly recorded whether the child yawned within 90 seconds of the yawning stimulus. About 40 percent of the reading sessions were randomly videotaped and coded by two independent raters for reliability. A child was considered to be a contagious yawner if he or she yawned in response to at least one of the experimenter’s yawns.
Children who weren’t paying attention as the experimenter yawned were excluded from analysis.
Helt discovered that children under age 4 were much less likely to respond to contagious yawning than the older children. Not a single one of the twenty 1-year-olds yawned; only one in 20 2-year-olds yawned; and only two 3-year-olds. But children 4 years old and older yawned much more often–seven out of 20 4-year-olds, and eight out of 20 for 5- and 6-year-olds).
“We saw a major jump to adult levels of contagious yawning at age 4,” Helt said. “We thought that was the most surprising thing. We thought it would be quite a bit younger.”
The second study involved 28 children between the ages of 6 and 15 with autism spectrum disorders and two control groups of typically developing children of similar age. All of the children participated in the same reading and yawning test, but this time all of the interactions were videotaped.
The results showed that children with autism spectrum disorders yawned about half as often as typically developing children, and none of the children with severe autism showed contagious yawning.
“This lack of early mimicry could also impact feelings of psychological connection and opportunities for social learning,” Helt says in her report. “These changes could thus leave children with autism unable to recognize primitive socio-emotional clues that could otherwise serve to biologically and emotionally synchronize them with people around them.”
Helt believes the findings may offer a potential identifier for children with autism and also allow experts to develop approaches that focus more on social and emotional cues.
Helt’s advisors on the study were Inge-Marie Eigsti, an assistant professor of psychology and neuroscience specialist, and Deborah Fein, Board of Trustees Distinguished Professor of Clinical Psychology, who is internationally known for her autism research. Also involved in the study was Peter J. Snyder, a senior research scientist at UConn, professor of clinical psychology at the Warren Alpert Medical School of Brown University, and vice-president for research at Lifespan Affiliated Hospitals.
The study is online in the journal Child Development.