Could yawning be the key to figuring out if someone is a psychopath?

If you're curious about whether a colleague, relative, romantic partner, or total stranger is a psychopath, try this simple test: Yawn, and see if they yawn back.

A new study has found that people with psychopathic personality traits don't "catch" the contagious yawn because they aren't very empathetic, lead author Brian Rundle told Today.com. Rundle says that yawning when you see someone else doing it is a primitive form of communication and bonding, but said you can't automatically label someone who doesn't yawn back at you a psychopath: You're less likely to yawn after someone else if you are older, and more likely to yawn if you know the person.

Researchers had 135 college students fill out the Psychopathic Personality Inventory, which is a standard assessment of psychopathic traits. Then, the students watched 10-second videos of people laughing, yawning, and doing nothing. They wore electrodes on their fingers, foreheads, and eyelids so they could be monitored. Rundle said those who were lower in psychopathic traits were nearly twice as likely to yawn as those who were high in those traits, but there were some students low in psychopathic traits who did not yawn, indicating more research needs to be done with a larger sample size. Rundle wants people to keep in mind that "people high in psychopathic traits may just be hard to connect with. It doesn't mean they are malicious individuals."

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