Over the past decade, we have learned how our brains are hardwired for emotional contagion. Emotions spread via a wireless network of mirror neurons, which are tiny parts of the brain that allow us to empathize with others and understand what they’re feeling. When you see someone yawn, mirror neurons can activate, making you yawn, in turn. Your brain picks up the fatigue response of someone sitting on the other side of the room. But it’s not just smiles and yawns that spread. We can pick up negativity, stress, and uncertainty like secondhand smoke. Researchers Howard Friedman and Ronald Riggio from the University of California, Riverside found that if someone in your visual field is anxious and highly expressive — either verbally or non-verbally — there’s a high likelihood you’ll experience those emotions as well, negatively impacting your brain’s performance.