Dec. 8, 2011 -- Yawns may be contagious for good reason.
A new study suggests that yawning after someone else yawns may be a sign of social empathy and emotional bonds between family and friends.
Researchers found that people are more likely to respond to a yawn with another yawn if the other person is a family member or friend. Contagious yawns are least likely among strangers.
Why Yawns Are Contagious
In the study, researchers looked at what factors were associated with contagious yawns among 109 adults from four different continents who were observed in their natural settings.
During each observation period of several hours, researchers recorded when the person yawned and if anyone who saw the yawn responded with a yawn within three minutes.
The results showed that social bonds overrode social situation and nationality differences in explaining why yawns are contagious.
The likelihood of sharing a contagious yawn was greatest among family members, followed by friends and acquaintances. People were least likely to experience a contagious yawn with strangers.
Researchers say the phenomenon of contagious yawning may also be explained by human biology.
They say seeing another person yawning activates a complex network of brain regions related to movement, imitation, social behavior, and empathy. The brain networks of the person who sees a yawn by someone they care about may then become overstimulated and lead to a yawning response.