Political polarization has become one of the most intensively studied phenomena in the social sciences, blamed for everything from populism and legislative gridlock to collapsing trust in democratic institutions and the collective failure to confront existential threats such as climate change and pandemics. Yet according to a sweeping review published in Nature Communications, the scientific community’s understanding of this global problem rests on a strikingly narrow evidence base. An international team of twenty-two researchers, led by Max Falkenberg of King’s College London and Walter Quattrociocchi of Sapienza University of Rome, argues that nearly half of all studies on political polarization focus on a single country: the United States. The consequence, they warn, is a field whose most celebrated findings may be outliers rather than universal laws, and whose interventions risk being misapplied to societies for which they were never designed.
The scale of the imbalance is quantified in the review’s own analysis. Of 5,965 academic papers using the terms political, ideological, or affective polarization in their title or abstract, 2,243 referred to at least one specific country. The United States appeared in 967 of those papers, amounting to 43.1 percent of all country-focused studies. Many papers that mention no country at all are, in practice, American studies that simply do not say so. The authors attribute this skew to a combination of legitimate global interest in U.S. politics, given its disproportionate influence on world affairs, unequal research funding across nations, the difficulty of surveying hard-to-reach populations, and the assumption that studying highly polarized countries matters more than studying stable ones. The result is a literature in which American norms, measures, and assumptions quietly become the default for the entire planet.
That default is conceptually problematic. The review highlights that the familiar two-party framing of polarization, in which society splits into sharply opposed camps of Democrats and Republicans, fits an unusual Manichean political system that most of the world does not share. Merriam-Webster’s choice of polarization as its word of 2024, defined as division into two sharply distinct opposites, captures this American lens. But in multi-party democracies such as Finland or Sweden, individuals routinely hold positive feelings toward several parties at once, and it remains an open question whether concepts developed on a one-dimensional left-right spectrum translate coherently to multi-dimensional political landscapes. Key disputes include how to define affective polarization without strong in-group identification, whether animosity toward political elites differs from animosity toward ordinary voters, and whether parties in multi-party systems should be expected to collapse into two opposed blocs at all.
The empirical record itself undermines the assumption that American patterns generalize. Comparative data from 21 high-income countries show only a small but significant rise in elite ideological polarization since the 1990s, with Canada and Australia registering low levels and Spain, Italy, and Sweden particularly high ones. Crucially, at a global scale, ideological polarization has not increased among the mass public, in clear contrast to the well-documented American trend. Affective polarization, the emotional hostility partisans feel toward their opponents, tells a similar story. While U.S. researchers have described American politics as suffering from political sectarianism, with the largest increase among 12 OECD countries over four decades, estimates spanning 53 countries place Türkiye, Hungary, and Kenya at the top of the affective polarization rankings, with the Philippines, the Netherlands, Belgium, and Japan at the bottom, and the United States squarely in the middle of the pack.
The relationship between ideological and affective polarization, a central debate in American scholarship, also proves inconsistent across borders. Survey evidence from 53 countries suggests the two are broadly correlated, but the Netherlands exhibits significant ideological polarization without high out-party animosity, while Montenegro and Serbia suffer severe affective polarization despite largely moderate principal parties. Importantly, high affective polarization correlates with democratic backsliding, whereas high ideological polarization does not, suggesting that some ideological diversity may even protect against radicalism. Scholars have therefore introduced concepts such as issue-based affective polarization, visible in the United Kingdom around Brexit and immigration, and have documented that hostility between factions within a single party, such as the progressive and centrist wings of the Labour Party, can in some cases exceed hostility between parties, challenging the primacy of partisanship as a political identity.
Institutional and economic context matters enormously. Research across 20 high-income democracies finds that affective polarization is worse where income inequality and unemployment are high, and that it tends to be higher in majoritarian political systems, such as France and the United Kingdom, where power concentrates in a single party, than in consensual systems like Switzerland and the Netherlands. Yet the reverse pattern appears for ideological polarization, which is lower in more majoritarian electoral systems. New Zealand offers a striking natural experiment: when the country switched to proportional representation in 1993, measured ideological polarization doubled. The review also debunks a common assumption that ethnic and religious divisions inherently drive damaging polarization. Comparative studies show that social cleavages become politically explosive only when elites deliberately politicize them, as occurred in India and Türkiye, while countries with clear ethnic divides, such as Taiwan and Indonesia, have experienced only brief episodes of destructive polarization, whereas Thailand and the Philippines, with fewer identifiable cleavages, suffered democratic collapse.
The information age adds a further layer of complexity that traditional polarization research has often ignored. On the news media, evidence is mixed and geographically limited. Surveys across 12 developed countries find little ideological bias in news consumption, with most people favoring centrist sources, and web browsing data showing that only 3.4 percent of all URLs visited in the United States, Poland, and the Netherlands are news pages. Even on social media, news makes up less than 3 percent of the average U.S. Facebook user’s feed. Experimental evidence is contradictory: incentivizing regular Fox News viewers to watch CNN for a month moderated their attitudes, yet large-scale Facebook data show partisan news consumption having little detectable impact on polarization. Meanwhile, global trust in news is declining, with 16 of 19 surveyed countries showing falling confidence, complicating proposals that more news exposure could depolarize the public.
Social media presents an equally contested picture. Homophilous interaction patterns, sometimes called interactional polarization, have been documented across platforms and countries including the United States, Brazil, Egypt, Israel, Venezuela, Pakistan, and Japan. But critics note that most online interactions are not political, that news diets on social media tend toward the moderate, and that apparent echo chambers may actually increase the plurality of cross-cutting beliefs. The largest Facebook field experiment to date, conducted with Meta and restricted to U.S.-based researchers, found that reducing exposure to like-minded content did not measurably affect polarization. Yet a Facebook deactivation study in the United States reduced polarization, while a replication in Bosnia-Herzegovina increased it, possibly because participants lacked offline exposure to other ethnicities. Platform differences compound the problem: in Brazil, the Philippines, and India, WhatsApp dominates political messaging, while Telegram plays a similar role in Eastern Europe, and private messaging platforms pose major barriers to academic data access.
Artificial intelligence introduces new uncertainties. Recommendation algorithms curate most of what users see, with over 70 percent of YouTube views coming from recommended content, but U.S. experiments on Instagram and Facebook found that removing reshared content, removing all content rankings, or down-ranking ideologically aligned sources did not affect polarization, whereas changes to ranking on X could raise or lower affective polarization depending on how partisan animosity was treated. Bots demonstrably amplify political content, large language models show measurable ideological biases and impressive persuasive power, and concerns persist about fabricated grassroots consensus and eroded institutional trust. Yet a global survey of the 2024 elections suggests initial fears about generative AI’s democratic impact were overblown, and studies show AI can also correct misconceptions, durably reduce conspiracy beliefs, and help humans find common ground. Whether AI polarizes or heals, the authors conclude, depends on how it is used and in which cultural context, not on any intrinsic property of the technology.
The review closes with concrete prescriptions. Researchers in understudied regions face career disadvantages because their work is perceived as less visible and less impactful, and institutions, publishers, and policymakers must actively reward research that brings global balance. Journals could mandate that U.S.-only studies state this explicitly in their titles or abstracts, as is already common for research on almost any other country. The authors call for comparative research identifying both shared and unique features of polarization, for pushing back against shuttered data access from companies including Meta, X, and Reddit, and for interdisciplinary collaboration on polarization consensus statements akin to those used in medicine. Interventions, they stress, must be ethically and practically tailored to local contexts rather than exported wholesale from American laboratories. Without high-quality, contextually appropriate evidence, even well-intentioned decision makers risk drawing flawed conclusions that further erode democratic institutions, making global equity in polarization research not an academic luxury but a democratic necessity.
Subject of Research: Global inequity and U.S. dominance in interdisciplinary political polarization research
Article Title: Toward an integrated and globally equitable understanding of political polarization
Article References: Falkenberg, M., Cinelli, M., Galeazzi, A., Bail, C. A., Benito, R. M., Bruns, A., Gruzd, A., Lazer, D., Lee, J. K., McCoy, J., Nagayoshi, K., Rand, D. G., Scala, A., Siegel, A. A., van der Linden, S., Varol, O., Weber, I., Wojcieszak, M., Zollo, F., … Quattrociocchi, W. (2026). Toward an integrated and globally equitable understanding of political polarization. Nature Communications, 17(1), Article 8338. https://doi.org/10.1038/s41467-026-76110-5
Image Credits: AI Generated
DOI: 10.1038/s41467-026-76110-5
Keywords: political polarization, affective polarization, ideological polarization, social media, democracy, misinformation, artificial intelligence, recommendation algorithms, comparative politics, data access, echo chambers, global equity
Tags: affective polarizationArtificial Intelligencecomparative politicsdata accessdemocracyecho chambersglobal equityideological polarizationmisinformationpolitical polarizationrecommendation algorithmssocial media
