People who are selfish, manipulative and lack empathy are less likely to be affected by "contagious yawning" than those who are empathetic, according to a recent study.

Researchers from Baylor University in Texas found that people with psychopathic characteristics are less likely to catch a yawn as it is associated with empathy and bonding, traits people with psychopathic traits usually don't have, Medical Daily reported.

Psychopathy is characterized by an antisocial lifestyle, including being selfish, manipulative, impulsive, fearless, domineering and, in particular, lacking in empathy, previous research has shown.

"You may yawn, even if you don't have to," Brian Rundle, lead researcher of the study, said in a statement. "We all know it and always wonder why. I thought, 'If it's true that yawning is related to empathy, I'll bet that psychopaths yawn a lot less.' So I put it to the test."

For the study, researchers recruited 135 college students. They took an standard psychological test with questions aimed at determining their degree of cold-heartedness, fearless dominance and self-centered impulsivity, The Huffington Post reported.

Next, students were shown 10-second video clips of different facial movements -- a yawn, a laugh or a neutral face -- with 10 seconds of blank screen separating 20 video snippets of those expressions.

Based on their findings, researchers concluded that the less empathy a person had, the less likely he or she was to "catch" a yawn.

"The take-home lesson is not that if you yawn and someone else doesn't, the other person is a psychopath," Rundle cautions. "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. But what we found tells us there is a neurological connection -- some overlap -- between psychopathy and contagious yawning. This is a good starting point to ask more questions."

The findings are detailed in the journal Personality and Individual Differences.