Research Highlight

Psychology: Moral contagion online

Proc. Natl Acad. Sci. USA (2017)

Social media has played a central role in recent political events, such as the Arab Spring, Black Lives Matter, and the US presidential election, and has come under scrutiny for its contribution to the proliferation of fake news and echo chambers. Memetics and related fields adopt the language of disease (for example, ‘contagion’, ‘viral’) to describe the spread of information, but an understanding of the factors influencing transmission rates is still in its early stages


A recent study by William J. Brady and colleagues at New York University extends work connecting emotional language to online diffusion of information by examining the propagation of morally inflected content in naturally occurring social networks on Twitter. Taking a large sample of tweets on three polarizing issues — gun control, same-sex marriage and climate change — the authors find that re-tweet rates (a measure of information spread) increased by approximately 20 percent with each moral-emotional word compared with other words. This effect was particularly salient within networks sharing a political ideology and may escalate differences between groups.

While future work will have to address the causal impact of moral-emotional language on opinion formation, these findings highlight linguistic content that can amplify digital messages or cause them to ‘go viral’, and demonstrate the importance of emotion in the transmission of moral ideas. This research is increasingly important as political and moral discourse migrates to online platforms.


  1. Search for Sara Constantino in: