March 17, 2014
No Empathy Link Found In Study Of Contagious Yawning
Lawrence LeBlond for redOrbit.com - Your Universe Online
It has been previously suggested that contagious yawning is a sign of empathy toward others, but a new study is finding little evidence to back up that theory.
Researchers from the Duke Center for Human Genome Variation have found that contagious yawning may actually decrease as we age and is less strongly related to variables such as empathy, tiredness and energy levels. Their paper, which has been published in the March 14 issue of PLOS ONE, is the most comprehensive look at factors relating to contagious yawning to date.
While the extensive research on why we yawn and why those around us follow in unison may seem like frivolity, the Duke team maintain that better understanding of the biology involved in contagious yawning could help scientists and doctors also better understand illnesses like autism and schizophrenia.
"The lack of association in our study between contagious yawning and empathy suggests that contagious yawning is not simply a product of one's capacity for empathy," study author Elizabeth Cirulli, PhD, assistant professor of medicine at the Center for Human Genome Variation at Duke University School of Medicine, said in a statement.
Contagious yawning has been well documented among humans and chimpanzees. Studies have shown that a yawn can be picked up after hearing or seeing another’s yawn and can even be in response to thinking about yawning.
Researchers from University of Tokyo last year also found a link between humans and their dogs, suggesting that dogs not only yawn when their owners yawn, but may be able to actually distinguish between a fake and a real yawn. The Japanese research also showed that dogs find their owners’ yawns more contagious than a strangers.
The Duke team explained that contagious yawning should not be confused with spontaneous yawning, which occurs when someone is bored or tired. Past studies have shown that spontaneous yawning occurs before we are even born and contagious yawning does not begin until early childhood.
But it has remained poorly understood why some people are more susceptible to contagious yawning than others. Empathy, or the ability to recognize another’s emotions, has been the most common variable linked to contagious yawning. However, other links have also been theorized, including a person’s intelligence and the time of day when yawning occurs.
While empathy, intelligence and time of day have previously been linked to why most people pick up a yawn, in the case of some people, such as those with schizophrenia or autism, contagious yawning seems practically non-existent, despite the fact they still spontaneously yawn. Delving deeper into this topic could shed light on these illnesses and general biological functions of humans.
In the current study, the Duke researchers aimed to better define how certain factors affect the susceptibility of someone catching a yawn. They recruited 328 healthy volunteers to partake in the research. Each participant completed cognitive testing, a demographic survey and a comprehensive questionnaire measuring variables such as empathy, sleepiness and over energy levels. The recruits then watched a three-minute video of people yawning and recorded the number of times they yawned while watching the video.
[ Watch the Video: Yawning 3.0 ]
The average for most people watching the video were between zero and 15 yawns in the three-minute period. Of the 328 people studied, 222 people yawned at least once. When testing across multiple sessions, the researchers found consistency in the numbers, demonstrating that contagious yawning is a stable trait.
However, unlike previous studies, the team did not find a correlation between contagious yawning and empathy, intelligence, or time of day. They noted that the only variable that significantly influenced contagious yawning was age – contagious yawning seemed less likely the older participants got. However, even this factor was attributable to only 8 percent of the yawn response.
"Age was the most important predictor of contagious yawning, and even age was not that important. The vast majority of variation in the contagious yawning response was just not explained," Cirulli said.
Because the mystery still remains on why we contagiously yawn, the team now want to look to see if there are genetic factors at play that could contribute to the contagious yawning conundrum. The ultimate goal of the team is to bring better understanding to diseases like autism and schizophrenia, as well as general human functioning, by identifying a genetic basis of contagious yawning.
"It is possible that if we find a genetic variant that makes people less likely to have contagious yawns, we might see that variant or variants of the same gene also associated with schizophrenia or autism," Cirulli said in the statement. "Even if no association with a disease is found, a better understanding of the biology behind contagious yawning can inform us about the pathways involved in these conditions."