If you've ever happened to yawn in front of a group of people, you've likely noticed that others will pick up the gesture and succumb to yawning themselves. Researchers believe this contagious reaction has less to do with a sleepy populace and more a primitive form of communication and bonding between humans. According to a new study, it may also reveal who amongst us is a coldhearted psychopath.


Researchers at Baylor University invited 135 participants to take what's called the Psychopathic Personality Inventory, a test designed to gauge traits such as cruelty, selfishness, impulsivity, aggression and empathy. The volunteers were placed in a dimly lit room with noise-canceling headphones and exposed to a series of videos meant to evoke an emotional response –– from smiling to laughing to yawning. Those who scored low on the psychopathic traits were twice as likely to yawn as those who score higher.

Now before you test this out and yawn in front of your current boyfriend/girlfriend/husband/wife to see if they're hiding some dark secret, understand that being a psychopath doesn't necessarily mean being prone to hiding bodies in basements. Instead, it's defined as an individual with "a dearth of social emotion," the study shares. "That is, it is an inconsideration of the emotional state of others." The study also found that some people who scored high in empathy didn't yawn at all, a reaction that may be due to a mistrust of the people seen on screen.

"The take-home lesson is not that if you yawn and someone else doesn't, the other person is a psychopath," lead researcher Brian Rundle said in a statement. "A lot of people didn't yawn, and we know that we're not very likely to yawn in response to a stranger we don't have empathetic connections with."

In 2011, a study by researchers at the University of Pisa found that the closer the relationship between people, the more contagious the yawn. "So, the time delay between yawns can potentially tell a lot about the closeness of a relationship," reported MNN's Bryan Nelson. "Are you BFFs, or just friends? Intimate lovers, or just friends with benefits?"

Because the connections between yawning and empathy continue to grow, Rundle says research with an even larger group of participants will be undertaken in the future.

Want to see how long you'll last before falling victim to a contagious yawn? Check out the below video. Don't worry if you don't start yawning right away. I lasted until about eight yawns in (and I cry easily at television commercials.)

Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Coldhearted people are immune to contagious yawning, study finds
Researchers discover that a person's level of psychopathic traits matters when it comes to catching a yawn.