New York, Aug 21 (IANS): Yawning is contagious in humans we know that but selfish and manipulative people will not respond to yawning after spotting someone else yawn, an interesting study has revealed.

People with psychopathic characteristics - those with anti-social lifestyle and lacking in empathy are less likely to be affected by “contagious yawning” than those who are empathetic, according to researchers from Texas-based Baylor University.

Yawning after spotting someone else yawn is associated with empathy and bonding.

“Catching” yawns happens with many social mammals, among them humans, chimpanzees and dogs.

“You may yawn even if you do not have to,” said lead researcher Brian Rundle, doctoral student in psychology and neuroscience.

“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,” Rundle added.

The study involved 135 college student respondents. They were shown 10-second video clips of different facial movements -- a yawn, a laugh or a neutral face.

Based on the psychological test results and the frequency of yawns, the study showed 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 does not, the other person is a psychopath," Rundle cautioned.

“There is a neurological connection between psychopathy and contagious yawning and this is a good starting point to ask more questions,” the authors noted in a paper published online in the journal Personality and Individual Differences.