Social Media, Political Polarization, and Political Disinformation: A Review of the Scientific Literature

Authors: Joshua A. Tucker, Andrew Guess, Pablo Barberá, Cristian Vaccari, Alexandra Siegel, Sergey Sanovich, Denis Stukal, Brendan Nyhan

Publication: William & Flora Hewlett Foundation, March 2018 — PDF

TL;DR

This comprehensive literature review examines the relationships among social media usage, political polarization, and political disinformation, synthesizing research across six topic areas: online political conversations, consequences of disinformation exposure, producers of disinformation, spreading strategies, content and polarization dynamics, and effects on democracy. The authors identify key research gaps and data needs, arguing that while evidence suggests social media, polarization, and disinformation are interconnected threats to democratic quality, many fundamental questions remain unresolved due to limited data access and methodological challenges.

Key claims

• Social media, political polarization, and disinformation form a reinforcing triangle that potentially undermines democratic quality through multiple pathways: exposure to false/slanted information, increased partisan hostility, reduced exposure to opposing viewpoints, and diminished trust in institutions.
• Political conversations online occur most frequently among people with existing close ties; cross-cutting political discussions remain rare, and most political information flows through a mix of traditional media outlets and social platforms.
• Exposure to disinformation and propaganda online can influence political attitudes and behavior, though individual susceptibility varies based on prior beliefs, media literacy, and demographic factors.
• Disinformation producers range from political elites and state actors pursuing strategic goals to grassroots partisans motivated by ideology or profit; strategies include coordinated amplification, bot networks, and infiltration of organic news-sharing networks.
• Political elite behavior—including deliberate disinformation campaigns and intensified partisan rhetoric—plays a significant role in driving mass polarization and the spread of polarizing content through social media.
• Multiple unresolved research gaps prevent a complete causal picture: effects of disinformation exposure remain incompletely estimated, cross-platform and longitudinal studies are lacking, mechanisms of elite influence on mass polarization need clarification, and generalizability of U.S. findings to other democracies is uncertain.

Structure

The report synthesizes literature across six interrelated topic areas, each reviewed as a standalone document but designed to collectively address the triangle of social media, polarization, and disinformation:

A. Online Political Conversations — Reviews normative theories of deliberative democracy and empirical findings on how often people discuss politics online, whether those discussions cross partisan boundaries, and how platform design affects the quality of political discourse.

B. Consequences of Exposure to Disinformation Online — Synthesizes evidence on whether and how exposure to false or misleading political information affects attitudes, beliefs, and behavior; discusses individual differences in susceptibility and the roles of fact-checking and media literacy.

C. Producers of Disinformation — Catalogs the range of actors creating false political information: political elites, state-sponsored operatives, ideologically motivated grassroots actors, and profit-motivated producers; distinguishes intentional falsehoods from inadvertent errors.

D. Strategies and Tactics of Spreading Disinformation — Examines how disinformation propagates online through coordinated amplification, bot networks, infiltration of organic sharing networks, and exploitation of platform algorithms and affordances.

E. Online Content and Political Polarization — Reviews evidence that social media exposure correlates with or contributes to affective and ideological polarization, and explores mechanisms (algorithmic filtering, selective exposure, social influence) and boundary conditions.

F. Misinformation, Polarization, and American Democracy — Synthesizes implications of the foregoing evidence for democratic governance, policy outcomes, civic engagement, and institutional trust.

Research gaps

The authors identify eight major gaps in the literature:

1. Better estimates of the effects of exposure to information and disinformation online—current evidence is limited and correlational
2. Cross-platform and multi-platform research—most studies focus on single platforms (Twitter, Facebook)
3. Disinformation spread through images and video—heavily understudied relative to text
4. Generalizability and comparability of findings across countries and elections
5. Role of ideological asymmetries in mediating disinformation effects and polarization
6. Effects of new laws and regulations intended to limit disinformation spread
7. Strengths and weaknesses of different bot-detection and disinformation-detection methods
8. Role of political elites in spreading disinformation and driving mass polarization

Data needs

The authors organize data gaps into three categories:

• Collectible with traditional funding: Longitudinal panel surveys tracking individuals' media consumption, attitude change, and political behavior over time; experiments and quasi-experimental designs testing causal effects of exposure; qualitative studies of disinformation producers and spreading tactics.
• Requiring centralized institutional effort: Crowdsourced platforms for disinformation detection and labeling; comparable datasets across platforms and countries; sustained access to social media data for rigorous analysis.
• Privacy-constrained or proprietary: Access to social media platform data on user networks, algorithmic curation, and the spread of specific claims; data held by platforms or subject to user privacy restrictions.

Connections

• Foundational reference for the intersection of Polarization, Disinformation, and Social media and misinformation effects on democracy.
• Cites and synthesizes work on Echo Chambers, Filter Bubbles, Misinformation Effect, Bot detection, and Computational Propaganda.
• Establishes framing used in subsequent literature on Content moderation and Platform governance responses to disinformation.
• Frequently cited in policy discussions and regulatory frameworks around social media and democratic integrity.

Notes

This is a canonical literature review that synthesizes research across multiple subfields (political science, communication, computer science, social psychology) and articulates a coherent framework linking social media usage, polarization, and disinformation as co-reinforcing threats to democratic quality. Its identification of research gaps and data needs has shaped subsequent funding priorities and research agendas in the field. The report's careful distinction between types of disinformation (false news, rumors, deliberately factually incorrect information, politically slanted information, hyperpartisan news) and its acknowledgment of asymmetries in how different political actors use these tactics remains influential. A notable strength is the report's honest assessment of causality: many findings are correlational, and experimental evidence for large-scale real-world effects remains limited. This has prompted subsequent work on causal identification. The 2018 date predates the rise of large language models as disinformation tools and the major shifts in platform architectures post-2023, making some findings on specific platform affordances less current.