PolarizationHow Shared Partisanship Leads to Social Media Connections

By Peter Dizikes

Published 24 February 2021

It is no secret that U.S. politics is polarized. An experiment conducted by MIT researchers now shows just how deeply political partisanship directly influences people’s behavior within online social networks. The Twitter experiment shows clear self-selection into social media “echo chambers” due to political preferences.

It is no secret that U.S. politics is polarized. An experiment conducted by MIT researchers now shows just how deeply political partisanship directly influences people’s behavior within online social networks.

Deploying Twitter bots to help examine the online behavior of real people, the researchers found that the likelihood that individuals will follow other accounts on Twitter triples when there appears to be a common partisan bond involved.

“When partisanship is matched, people are three times more likely to follow other accounts back,” says MIT professor David Rand, co-author of a new paper detailing the study’s results. “That’s a really big effect, and clear evidence of how important a role partisanship plays.”

The finding helps reveal how likely people are to self-select into partisan “echo chambers” online, long discussed as a basic civic problem exacerbated by social media. But methodologically, the experiment also tackles a basic challenge regarding the study of partisanship and social behavior: Do people who share partisan views associate with each other because of those views, or do they primarily associate for other reasons, with similar political preferences merely being incidental in the process?

The new experiment demonstrates the extent to which political preferences themselves can drive social connectivity.

“This pattern is not based on any preexisting relationships or any other common interests — the only thing people think they know about these accounts is that they share partisanship, and they were much more likely to want to form relationships with those accounts,” says first author Mohsen Mosleh, who is a lecturer at the University of Exeter Business School and a research affiliate at the MIT Sloan School of Management.

The paper, “Shared Partisanship Dramatically Increases Social Tie Formation in a Twitter Field Experiment,” appears this week in Proceedings of the National Academy of Sciences. In additional to Rand, who is the Erwin H. Schell Professor at the MIT Sloan School of Management and director of MIT Sloan’s Human Cooperation Laboratory and Applied Cooperation Team, the authors are Mosleh; Cameron Martel, a PhD student at MIT Sloan; and Dean Eckles, the Mitsubishi Career Development Professor and an associate professor of marketing at MIT Sloan.