Why are certain pieces of online content more viral than others? And in particular, which role emotions play in this context? Jonah Berger and Katherine L. Milkman takes a psychological approach to understanding diffusion. Focusing on a dataset of the New York Times articles published over a three month period, the authors examine how emotion shapes virality (the metric used to measure virality is the number of people who emailed the article).

Findings are clear: positive content is more viral than negative content, but the relationship between emotion and social transmission is more complex than valencealone, and is partly driven by arousal. Content that evokes either positive (awe) or negative (anger or anxiety) emotions characterized by high arousal is more viral. Content that evokes low arousal emotion (sadness) is less viral. 

So use emotions if you want your content to go viral – but avoid sadness!

References: Berger, J. A., and Milkman, K. L. Social Transmission, Emotion, and the Virality of Online Content. Social Science Research Network Working Paper Series. 2009.