Emotional Contagion: You Catch Other People's Feelings Like a Cold

You have probably noticed that spending time with a certain person leaves you feeling energised and good, while spending time with someone else leaves you feeling drained and vaguely anxious, even when nothing particularly significant was discussed. This is not coincidence, and it is not fully in your control.

Emotional contagion is the process by which emotions and mood states spread from person to person. It operates through multiple channels simultaneously, and most of them are below conscious awareness.

The most immediate channel is facial mimicry. People unconsciously mimic the facial expressions of those they are talking to — a smile triggers micro-muscular movements toward smiling, a furrowed brow triggers similar movement in the observer. Because facial expressions are part of how emotions are generated as well as expressed, mimicking the face contributes to feeling the associated emotion. You do not just mirror the expression; you partly replicate the feeling.

Posture, tone of voice, and rhythm of speech are contagious in similar ways. We synchronise with the bodies and voices of people we are with, and those synchronisations feed back into our emotional state. Elaine Hatfield, one of the leading researchers on emotional contagion, describes this as a two-step process: afferent feedback from the physical mimicry shapes subjective emotional experience.

The effect scales to groups and organisations. Research on work teams has found that the emotional tone of a team leader is disproportionately contagious — leaders have an outsized effect on collective mood, which affects cooperation, creativity, and performance. Cheerful leaders create more positive team environments; anxious or hostile leaders create stressed, defensive ones.

In 2014, Facebook ran a controversial experiment in which it manipulated the emotional valence of content shown in users' news feeds and measured whether this affected users' own emotional expression in their posts. Users shown more negative content produced more negative posts; those shown more positive content produced more positive ones. Emotional contagion operates through text on a screen.

Knowing this gives you some agency. You can make choices about which environments and which people you spend time in, understanding that those choices shape your emotional life more than you might think. And if you are in a position of influence — as a leader, parent, or friend — your emotional state is not your private matter. It is being broadcast.