When someone yawns near us, we naturally feel an irresistible urge to yawn in response. Even dogs seem to yawn when humans do it. This contagious behavior has fascinated psychologists and behaviorists for many years, and while there are many reasons scientists have proposed for why people yawn (it’s a bit complicated, what we know for sure is that’s important and actually has a purpose), social cohesion might play an important role. The more emphatic you are, the likelier it is you’ll yawn in response. On the contrary, psychopaths barely register yawns and seem impenetrable.