Yawns are contagious. Or at least they're supposed to be.
So here's a quick test: yawn. If the person next to you--whether a stranger of someone you've known and loved all of your life--doesn't yawn, then he might be a psychopath.
That's how I'm misinterpreting a new study by researchers at Baylor University. They found a positive correlation between people who don't yawn when other people do and scores on questionnaires for psychopathic characteristics. Shaunacy Ferro writes for Mental Floss:
The higher the participants rated on measures of cold-heartedness, the less likely they were to catch another person’s yawn. Granted, people are less likely to feel empathy with a stranger they’re watching in a video than with someone they know, and the sample size was pretty small, so Baylor University probably isn’t full of a bunch of raging psychopaths. And not yawning when others do it doesn’t mean you should run off for a psych evaluation. "But what we found tells us there is a neurological connection—some overlap—between psychopathy and contagious yawning,” study author Brian Rundle says.
-via Joe Carter