Social Media and Political Polarization: A Narrative Review of Mechanisms, Evidence, and Research Gaps
Abstract
Political polarization in democratic societies has intensified over the past two decades, coinciding with the rise of social media as a dominant channel for political information and expression. This narrative review synthesizes evidence from systematic reviews, meta-analyses, and empirical studies published between 2010 and 2025 to evaluate the role of social media in shaping political polarization. Drawing on prior systematic work, the review addresses four themes: selective exposure and media effects, the contested empirical status of echo chambers and filter bubbles, the role of algorithmic curation and recommender systems, and the distinction between affective and issue-based polarization. The synthesis indicates that while pro-attitudinal media use is consistently associated with heightened polarization, direct causal evidence that social media use produces echo chambers is weaker and more contested than popular discourse suggests. Existing research is disproportionately concentrated on Twitter/X and United States samples, constraining generalizability. The review concludes by identifying priority areas for future research, including cross-platform and cross-national designs, longitudinal causal identification strategies, and interventions capable of reducing affective polarization without suppressing legitimate political expression.