A recent study was published in the Personality and Individual Differences journal, and it reports that yawning is the key to identifying a psychopath.
The research found that when we see another person yawning, we tend to yawn yourself. This mirroring of another person is a sign of being empathetic and bonding, and humans aren’t the only species to display the behaviours, it’s found among animals too.
A psychopath lacks empathy, which means they’re less likely to yawn back at you. Although, it’s worth noting that this technique may not always work, particularly if the person who sees you yawn is a complete stranger. A better indication is if someone you know well doesn’t yawn back.
Regardless, the research has identified a direct link between psychopathy and contagious yawning
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