Polarization and echo chambers in Reddit’s political discourse

Abstract

Online social media have become important arenas for political debate, with election periods amplifying ideological engagement. Polarization and echo chamber effects were shown to be important for platforms like Twitter or Facebook but less for others like Reddit. Here we challenge this assumption through a case study of Reddit conversations across the 2016 US presidential election. We use statistical validation techniques to extract ideologically distinct communities of subreddits, in terms of their contributing user base and news consumption, which we use to analyze the dynamics of political debate. We thus reveal clear polarization in both interaction-based and topic-based communities, with clusters of Democratic, Conservative, and Banned subreddits. Election periods intensify cross-group engagement, align Banned and Conservative content, and reduce linguistic diversity within groups. Overall, we characterize Reddit as a polarized environment marked by structural patterns consistent with echo-chamber organization, highlighting network validation as a key method for identifying relevant user interaction and information-sharing patterns in online social media.