Facebook Confirms the Network’s Massive-Scale Emotional Contagion

A giant Facebook experiment found that emotions expressed by others influence our own emotions, resulting in massive-scale contagion via social networks.


A new experiment by Facebook’s data scientists confirmed the network’s massive influence on users’ positive and negative mood states.

According to the study, “emotional states can be transferred to others via emotional contagion, leading people to experience the same emotions without their awareness.”

Emotional contagion occurred without direct interaction and in the absence of nonverbal cues. Users were affected by simply being exposed to others’ status updates and posts.

Previous studies have found that using Facebook produces both positive and negative affects on users’ mental health. The current study helps us understand how that happens and in which direction.

More than 689,003 Facebook users took part in the study without their knowledge (agreeing to Facebook’s terms of service gives the network permission to use you as a test subject).

The network gave priority to an unusually high number of either positive or negative posts appearing in users’ newsfeeds; positive updates resulted in more positive posts by exposed individuals and vice versa. From the abstract:

Data from a large real-world social network, collected over a 20-y period suggests that longer-lasting moods (e.g., depression, happiness) can be transferred through networks [Fowler JH, Christakis NA (2008) BMJ 337:a2338], although the results are controversial. In an experiment with people who use Facebook, we test whether emotional contagion occurs outside of in-person interaction between individuals by reducing the amount of emotional content in the News Feed. When positive expressions were reduced, people produced fewer positive posts and more negative posts; when negative expressions were reduced, the opposite pattern occurred.

The paper, “Experimental evidence of massive-scale emotional contagion through social networks,” was published in The Proceedings Of The National Academy Of Sciences.