Emotion Shapes the Diffusion of Moralized Content in Social Networks

How much do the people around us online affect the information flow to us? To answer this, we study a large sample of tweets about controversial topics and find that moral or emotional words in tweets did increase their spread.

Abstract

Political debate concerning moralized issues is increasingly common in online social networks. However, moral psychology has yet to incorporate the study of social networks to investigate processes by which some moral ideas spread more rapidly or broadly than others. Here, we show that the expression of moral emotion is key for the spread of moral and political ideas in online social networks, a process we call “moral contagion.” Using a large sample of social media communications about three polarizing moral/political issues (n = 563,312), we observed that the presence of moral-emotional words in messages increased their diffusion by a factor of 20% for each additional word. Furthermore, we found that moral contagion was bounded by group membership; moral-emotional language increased diffusion more strongly within liberal and conservative networks, and less between them. Our results highlight the importance of emotion in the social transmission of moral ideas and also demonstrate the utility of social network methods for studying morality. These findings offer insights into how people are exposed to moral and political ideas through social networks, thus expanding models of social influence and group polarization as people become increasingly immersed in social media networks.

Background

Despite a broad consensus that morality is influenced by attitudes and norms transmitted by our social world, remarkably little work has examined how these social networks transmit moral attitudes and norms. Most existing research studies the social transmission of morality through behavior or communication. In society, the transmission of morality goes well beyond that. The political debate about moralized issues is becoming more common in online social networks, however, the discipline of moral psychology has not yet utilized the study of social networks to investigate how some moral ideas spread more rapidly or broadly than others. So how much does who we regularly interact with online affect the flow of information to us? 

Study

To investigate the role of moral emotion in the transmission of morality in social networks, we use a large sample of tweets about three polarizing moral/political issues: gun control, same-sex marriage, and climate change. Because language is one direct way in which people communicate emotion, we coded the language in Twitter messages to quantify morality and emotion. “Contagion” was indexed as the number of times each message was retweeted by a user for each moral/political topic. 

Results

We observe that the presence of moral-emotional words in messages increased their diffusion by a factor of 20% for each additional word. It seems likely that politicians, community leaders, and organizers of social movements express moral emotions — of either positive or negative valence — in an effort to increase message exposure and to influence perceived norms within social networks. Overall, our results highlight the importance of emotion in the social transmission of moral ideas and also prove the usefulness of social network methods for studying morality.