You’ve probably experienced emotional contagion before: that thrill of excitement you feel in the stands just before a sporting event begins; the fear that courses through you as you wander with friends through a haunted house at the fair; or just knowing that if your best friend cries, you will too. 

So what is emotional contagion?

“Smile and the world smiles with you.” Emotional contagion is a physiological phenomenon, where emotion in one person transfers automatically to another without conscious intervention from either party.

How does emotional contagion work?

When I pick up a glass of water, my brain does several things automatically, including locating the glass in 3-dimensional space, as well as estimating weight, size, temperature, and other dimensions. Then the brain tells my body how to act: how to orient my hand, how far to reach out, how much pressure to exert so I can hold the glass without breaking it or dropping it, and how much...