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Contagious Yawning: Evidence of Empathy?

By Jason G. Goldman | May 17, 2012

When is a yawn just a yawn? When is a yawn more than a yawn? Contagious yawning

the increase in likelihood that you will yawn after watching or hearing someone else yawn

has been of particular interest to researchers in fields as varied as primatology, developmental psychology, and psychopathology.

At first, scientists thought thatyawningwas a mechanism designed to keep the brain cool. However, it turns out that there is a

correlation between the susceptibility for contagious yawning and self-reported empathy. Humans who performed better at theory of

mind tasks (a cognitive building block required for empathy) also yawn contagiously more often (PDF). And two conditions that havebeen associated with poorer performance on theory of mind tasks are also associated with reduced or absent contagious yawning:

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schizotypyand autism.

In 2008, psychologist Ramiro Joly-Mascheroni and colleagues from the University of Londonshowed, for the first time, that human

yawns are contagious for domestic dogs. Dogs unique social skills in interacting with humans is probably the result of selectionpressures during the domestication process. Therefore, they reasoned, it is possible that as a result of that process, dogs may have

developed the capacity of empathy towards humans. And if so, it is further possible that they may yawn when they see and hear

humans yawn.

In one condition, the experimenter, who was a stranger to the dogs, attracted the dogs attention and then initiated a genuine yawn. The

yawn was repeated for five minutes after re-establishing eye contact with the dog, which meant that the number of yawns variedbetween ten and nineteen per individual. In the control condition, the experimenter displayed a fake yawn, which mimicked the mouth

opening and closing actions, but not the vocalization or other subtle muscular changes.

In (a) the dog observes the human yawning, in (b) the dog starts yawning as the human finishes (reflected in themirror behind the dog), and in (c) the dog completes the yawn.

The yawning condition made 21 out of 29 dogs, seventy-two percent, yawn in response. None of the dogs yawned in the control

condition. Amazingly, this is even higher than rates of contagious yawning that have been reported for humans, which range from

45-60%. With this experiment, membership in the group of species that exhibit contagious yawning became slightly less exclusive: dogs

were added to a small list that had contained humans, chimpanzees, stumptail macaques, and gelada baboons. Despite this new

evidence, however, there was still no consensus on the function of contagious yawning. Even if correlated with empathy, why would

empathy lead to yawning?

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Chimps Yawn When Their Friends Yawn

Then, in 2011, Matthew Campbell and Frans de Waal ofYerkes National Primate Research Centerat Emory University proposed a more

nuanced view of contagious yawning. They wondered if social group membership could affect the transmission of a contagious yawn.After all, if empathy is indeed the thing underlying contagious yawning, then contagious yawning should show many of the same

behavioral signatures that empathy itself does. For example, it is known that certain parts of the brain (the anterior cingulate and the

anterior insula) activate both when people experience pain as well as when another person experiences pain (other parts of the brain

only activate in response to personal pain, not to others pain). From this data, researchers suggested that humans are able to share the

emotional aspects of pain, but not the physical aspects of pain, with others. This, of course, is the basis for empathy.

And additional fMRI studieshave further refined these findings: activity in the anterior cingulate is greater in response to watching an

in-group member experience pain than in response to the pain of an out-group member. So if contagious yawning reflects empathy,

and empathy varies on the basis of social status, then it is possible that contagious yawning will vary on the basis of social status as well.

Since chimpanzees are highly territorial and overtly aggressive towards other groups, it is certain that members of the same social

group are considered part of the in-group, and strangers are automatically outsiders.

Campbell and de Waal recorded videos of chimpanzees while they were yawning to use as experimental stimuli. The videos were edited

down to just nine seconds each and were shown to the chimps on an iPod touch. It was expected that they would yawn more when

shown videos of group members yawning than when shown videos of strangers yawning. They were also shown videos of chimpanzees

doing other things, as a control condition. In this video, Tara, an adult female, yawns while watching a video of another chimp from her

social group yawning on the iPod touch.

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The chimpanzees did yawn more often after watching videos of a familiar chimp yawning compared with the videos of ingroup

members doing other things. Consistent with the researchers expectations, they yawned more after watching a familiar chimp yawning

than after watching an unfamiliar chimp yawning. And there were no gender differences: males yawned in response to ingroup yawn

videos as often as the females did. Importantly, these results could not have been due to differences in attention, since the chimps

actually paid moreattention when viewing videos of unfamiliar chimpanzees than familiar ones.

Taken together, this provided strong evidence that empathy indeed underlies contagious yawning, and that contagious yawning is

dependent on social group membership. Given that, it is therefore unclear why humans doyawn after watching strangers or outgroup

members yawn. Since all members of a chimpanzee community know eachother, not only are they members of the same group, but

they are all familiar with eachother.

Campbell and de Waal speculated that humans, at some point in our evolution, may have evolved the ability to consider strangers,

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oon, J., & Tennie, C. (2010). Contagious yawning: a reflection of empathy, mimicry, or contagion? A n i m a l

B eh a v i o u r , 79 (5) DOI: 10.1016/j.anbehav.2010.02.011

Silva, K., Bessa, J., & de Sousa, L. (2012). Auditory contagious yawning in domestic dogs (Canis familiaris): firstevidence for social modulation A n im a l Co g n i t i o n DOI: 10.1007/s10071-012-0473-2

Chimp yawn viaFlickr/Pelican; Baby yawning viaFlickr/fumanch00. Dog photo copyright the author.

About the Author:Dr. Jason G. Goldman received his Ph.D. in Developmental Psychology at the University of Southern California, where he studied the evolutionary

and developmental origins of the mind in humans and non-human animals. Jason is also an editor at ScienceSeekerand Editor of Open Lab 2010. He lives in Los

Angeles, CA. Follow on Google+. Follow on Twitter @jgold85.

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