Every winter, like clockwork, we prepare to avoid catching the flu or seasonal cold. However, there is an epidemic we’re all infected with without a cure: emotional contagion. In BrainCraft’s latest video, “Are Your Emotions Contagious?” writer and host Vanessa Hill suggests we tend to subconsciously catch each other’s feelings through a mirror neurons system that reflects behavior.

The mirror neurons theory suggests neurons might be involved in feelings of empathy, while others think these brain cells play critical roles in human abilities like speech. A 1992 study published in the journal Experimental Brain Research found certain groups of neurons in the brains of macaque monkeys fired not only when a monkey performed an action, such as grabbing an apple out of a box, but also when the monkey watched someone else performing that action. This brain activity was seen even when the monkey heard someone performing the action in another room.

A 2000 study published in the journal Psychological Science found this behavior is reflected in humans. Participants were shown a face with either a happy, angry, or neutral expression, but only for 30 milliseconds. The expressive faces weren’t on the screen long enough for the participants to notice, so they had no idea that they were being subconsciously exposed to them. Still, the participants who were shown the happy face displayed increased electrical activity in the muscles needed to smile and mimic that face, and vice versa with the angry face.

“It’s thought that we mirror behaviors and facial expressions to help us understand the emotional states of others and learn by imitation,” Hill says in the video. We tend to mimic and match moods, facial expressions, and behavior as empathy. This is why if we see someone is smiling and we’re upset, chances are we still match our feelings to our emotional environment as a way to empathize.

Whether emotions are as contagious as the common cold is still up for debate, but recently a study published in the journal PLOS One found the physical sensation of feeling cold is actually contagious. Participants were shown videos of a hand in either visibly cold or visibly warm water and found the participants’ hands dropped in temperature. This was more noticeable in participants who reported having higher levels of empathy.

Although it is not clear whether mirror neurons are responsible for emotional and temperature contagion, it does seem we are primed to mimic what we observe.

It really is monkey see, monkey do.