Emotions Are Contagious. But you can control what spreads.

You’re at the family dinner table. Your spouse worries that a friend’s business is struggling. Then your son complains about his math homework and your inability to help, and your daughter asks when she will see her friends again. As the meal progresses, you can feel everyone becoming more and more anxious.

Emotions are contagious. We automatically mimic each other’s facial expressions, body language, and tone of voice. Next, we actually feel the emotions we mimicked and begin to act on them. Without our realizing what’s happening, feelings can escalate, as we “catch” them from other people, who catch them back from us, in an increasing spiral.

While emotions spread more easily in person, they also get transmitted through social media, phone calls, emails, and video chats. In fact, negative emotions related to isolation may make us even more susceptible.

Luckily, knowledge is a form of inoculation. Just being aware of emotional contagion can reduce its negative effects. And positive emotions transfer just as easily as negative ones. The spread of positive emotions leads to greater cooperation, less conflict, and improved performance.

That doesn’t mean you need to walk around with a smile on your face all the time. Allow yourself to be authentic, because positive emotional contagion can come from a range of feelings, including compassion.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, does an excellent job of conveying information in the face of uncertainty while remaining reassuring. You can do the same at the dinner table.

Try noticing how you are influenced by others’ moods and how their reactions influence yours. You can then reorient conversations away from catastrophizing and toward calm, showing the young people in your life that caring and hope are as easy to spread as negativity.

Sigal Barsade is the Joseph Frank Bernstein Professor of Management at Wharton. This post appeared in Tip of the Week — actionable advice about the science of character — from Character Lab, founded by Penn psychology professor Angela Duckworth. You can sign up to receive more at characterlab.org.