Cited by 288Social Media and PoliticsElectoral Systems and Political ParticipationOpinion Dynamics and Social Influence

How digital media drive affective polarization through partisan sorting

Open access
Törnberg, Petter·2022·Proceedings of the National Academy of Sciences

Abstract

Politics has in recent decades entered an era of intense polarization. Explanations have implicated digital media, with the so-called echo chamber remaining a dominant causal hypothesis despite growing challenge by empirical evidence. This paper suggests that this mounting evidence provides not only reason to reject the echo chamber hypothesis but also the foundation for an alternative causal mechanism. To propose such a mechanism, the paper draws on the literatures on affective polarization, digital media, and opinion dynamics. From the affective polarization literature, we follow the move from seeing polarization as diverging issue positions to rooted in sorting: an alignment of differences which is effectively dividing the electorate into two increasingly homogeneous megaparties. To explain the rise in sorting, the paper draws on opinion dynamics and digital media research to present a model which essentially turns the echo chamber on its head: it is not isolation from opposing views that drives polarization but precisely the fact that digital media bring us to interact outside our local bubble. When individuals interact locally, the outcome is a stable plural patchwork of cross-cutting conflicts. By encouraging nonlocal interaction, digital media drive an alignment of conflicts along partisan lines, thus effacing the counterbalancing effects of local heterogeneity. The result is polarization, even if individual interaction leads to convergence. The model thus suggests that digital media polarize through partisan sorting, creating a maelstrom in which more and more identities, beliefs, and cultural preferences become drawn into an all-encompassing societal division.

AI snapshot

Written from the paper’s full text.

TL;DR

The paper proposes a computational model in which digital media drive affective polarization not through echo chambers but through nonlocal interaction that aligns local political cultures into partisan sorting. Simulations show that increasing nonlocal interaction can sharply raise sorting when influence homophily is high, while purely local interaction keeps sorting low.

Key findings

  • In example runs with high influence homophily (h = 8; n = 10, |A| = 196, c = 4, m = 10), γ = 1 quickly reaches a high sorting value ψ; γ = 0.5 rises more slowly and settles around ψ = 0.3; γ = 0 remains near the expected ψ = 0.
  • Across 8,000 simulation runs varying γ and h, low influence homophily (h = 1) produces no partisan sorting regardless of γ; high homophily (h = 8) produces a rapid increase in sorting past a threshold of nonlocal interaction; intermediate homophily (h = 4) shows bistability between low- and high-sorting end states.
  • The same general γ–ψ relationship appears on random regular, scale-free, and connected caveman networks (1,600 runs over the parameter space), though the clique-dominated caveman network requires higher γ before sorting rises.
  • With n = 10 dynamic attributes and m = 10 possible states, the chance that two groups share at least one attribute is about 65% (1 − (9/10)^10 ≈ 0.65), which can prevent sorting from reaching 1 and affects convergence probability.

Methods

  • Agent-based opinion-dynamics model: agents on a graph (primarily a two-dimensional torus lattice with Moore neighborhood), each with n dynamic attributes taking integer values 1–m and a fixed partisan attribute S (k = 2); partisanship is weighted by c = 4. Each asynchronous update selects a random agent; interlocutors are local neighbors with fraction γ replaced by nodes sampled randomly from the entire network; influence follows an urn model based on relative similarity with homophily parameter h; sorting ψ is the fraction of shared dynamic attributes among same-party agents minus that among different-party agents.
  • Simulations: 8,000 runs varying γ and h (Fig. 2 reports h = 1, 4, 8), plus 1,600 runs on three common network structures (random regular, scale-free, connected caveman). Convergence is operationalized as no update during 10 runs across the full number of agents, or after 1,000,000 iterations.
  • Analysis: final ψ as a function of γ; PCA on the matrix of distances between agents and ridgeline plots to visualize group distributions over time; grid visualizations treating dynamic attributes as a base-m number.

Limitations

  • Stated: partisan affiliation is treated as fixed, assuming it changes on a slower timescale; the model focuses on k = 2 bipolarization (though expandable to k > 2); nonlocal interlocutors are chosen without self-similarity bias, leaving selective-exposure-like bias to future research; the torus lattice is a poor representation of real-world networks, though other network structures are tested; convergence is challenging to prove analytically, so an empirically chosen stopping metric is used.
  • Stated: the model is minimal and theoretical; it does not directly measure affective polarization but uses sorting ψ as a proxy linked in the literature; no empirical validation against real-world digital media data is presented.
  • Evident: parameter choices (c = 4, h values, n = 10, m = 10, |A| = 196 or 625) and simulation stopping rules may affect results; causal claims about digital media are model-derived, not empirically tested; the paper notes academic debate about how far political divisions dominate cultural life, and cites a study finding most lifestyle preferences remain shared across the political divide.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1073/pnas.2207159119

Cites

120 of 120 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

20 of 56 cited sources checked · 6 supported · 0 flagged · accuracy not yet measured

  • Premisecitation

    The online news audience is less ideologically segregated than in-person interactions with family, friends, coworkers, and political discussants.

    “Research using internet traffic data has even suggested that the online news audience is in fact less ideologically segregated than in-person interactions with family, friends, coworkers, and political discussants (70–72).”
    Quote in the paperNot a substantial claim2 of 3 sources checked
    • cites [70] M. Gentzkow, J. M. Shapiro, Ideological segregation online and offline. Q. J. Econ. 126, 1799– 1839 (2011). source

      Section 4.1 reports that Internet news segregation is lower than segregation in face-to-face interactions involving families, workplaces, and trusted acquaintances. Section 2.3 describes measures for friends and acquaintances, but our copy does not identify political discussants as a measured group, so that specific comparison is not established by this source. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
    • cites [71] D. C. Mutz, P. S. Martin, Facilitating communication across lines of political difference: The role of mass media. Am. Polit. Sci. Rev. 95, 97– 114 (2001). source

      The section “Sources of Exposure to Cross-Cutting Political Views” finds that newspapers and television news expose people to more differing political views than interpersonal discussants, including workplace contacts. It does not establish the claim about online news audiences or use internet traffic data; “Implications of Availability and Selectivity” instead notes that people may select political websites that share their views. Page numbers are unavailable in our copy. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites [72] D. C. Mutz, J. J. Mondak, The workplace as a context for cross-cutting political discourse. J. Polit. 68, 140– 155 (2006). source
  • Premisecitation

    Individuals exposed to opposing views on Twitter became more polarized, not less.

    “Bail et al. (75) similarly found in a field experiment on Twitter that individuals who were exposed to opposing views became more polarized, not less (see also ref. 25).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [75] C. A. Bail, Exposure to opposing views on social media can increase political polarization. Proc. Natl. Acad. Sci. U.S.A. 115, 9216– 9221 (2018). 30154168 PMC6140520 source

      The Abstract reports that Republicans expressed substantially more conservative views after following a liberal Twitter bot. Democrats became only slightly more liberal after following a conservative bot, and that effect was not statistically significant. The citing sentence overgeneralizes the increase in polarization to exposed individuals as a whole; the Discussion and Conclusion also cautions against generalizing beyond the study population. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
  • Premisecitation

    Digital media brings individuals into interaction with others outside their local network.

    “The parameter γ thus represents a simple way of capturing the empirically observed effect of digital media: digital media means that individuals are brought into interaction with others outside their local network.”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites [25] C. A. Bail, Breaking the Social Media Prism: How to Make Our Platforms Less Polarizing (Princeton University Press, 2021). source
    • cites [26] A. Guess, B. Nyhan, B. Lyons, J. Reifler, Avoiding the echo chamber about echo chambers. Knight Foundation 2, 1– 25 (2018).

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [27] P. Törnberg, J. Uitermark, Tweeting ourselves to death: The cultural logic of digital capitalism. Media Cult. Soc. 44, 1– 20 (2022). source
  • Premisecitation

    When cleavages and conflicts come to align (sorting), the effects intensify prejudice and conflict between opposing political groups.

    “Correspondingly, when cleavages and conflicts come to align—what we will refer to as sorting—the effects are synergetic in terms of intensifying prejudice and conflict between opposing political groups (18, 44).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [18] L. Mason, A cross-cutting calm: How social sorting drives affective polarization. Public Opin. Q. 80, 351– 377 (2016). source
    • cites [44] S. Roccas, M. B. Brewer, Social identity complexity. Pers. Soc. Psychol. Rev. 6, 88– 106 (2002). source
  • Premisecitation

    Partisanship is emerging as an important social identity under which many societal divisions and conflicts are coming to align.

    “Many scholars link these negative feelings to shifts in identity, with partisanship emerging as an important social identity under which many societal divisions and conflicts are coming to align (15–18).”
    Quote in the paperSubstantial claim1 of 4 sources checked
    • cites [15] S. Iyengar, G. Sood, Y. Lelkes, Affect, not ideology: A social identity perspective on polarization. Public Opin. Q. 76, 405– 431 (2012). source
    • cites [16] S. Iyengar, S. J. Westwood, Fear and loathing across party lines: New evidence on group polarization. Am. J. Pol. Sci. 59, 690– 707 (2015). source
    • cites [17] L. Mason, “I disrespectfully agree”: The differential effects of partisan sorting on social and issue polarization. Am. J. Pol. Sci. 59, 128– 145 (2015). source
    • cites [18] L. Mason, A cross-cutting calm: How social sorting drives affective polarization. Public Opin. Q. 80, 351– 377 (2016). source
  • May combine two claims. 24
  • Classified as probably not a substantial claim. 7
  • May combine two claims.

    Premisecitation

    Digital media do not isolate individuals from opposing ideas; they bring them to interact with individuals outside their local bubble and force them to take sides.

    “This literature suggests that digital media do not isolate us from opposing ideas; au contraire, they bring us to interact with individuals outside our local bubble, and they throw us into a political war, in which we are forced to take sides (25–27).”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites [25] C. A. Bail, Breaking the Social Media Prism: How to Make Our Platforms Less Polarizing (Princeton University Press, 2021). source
    • cites [26] A. Guess, B. Nyhan, B. Lyons, J. Reifler, Avoiding the echo chamber about echo chambers. Knight Foundation 2, 1– 25 (2018).

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [27] P. Törnberg, J. Uitermark, Tweeting ourselves to death: The cultural logic of digital capitalism. Media Cult. Soc. 44, 1– 20 (2022). source

      In “Political discourse as self-presentation” (page unavailable), the paper says messages from opposing groups are common on social media and can fuel outrage and strengthen group identity; it also describes a broader political culture war. But it says social media cluster users into echo chambers or filter bubbles, and it does not establish that users interact with people outside those groups or are forced to take sides. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
  • May combine two claims.

    Premisecitation

    The political divide has remained relatively stable in the United States in terms of issue positions, while many other indicators point to a significant increase in partisan polarization and animosity in the mass public.

    “While the political divide has remained relatively stable in the United States in terms of issue positions (33), many other indicators point to a significant increase in partisan polarization and animosity in the mass public (18, 34): Democrats and Republicans are growing increasingly cold to each other, coming to dislike or even disdain their partisan opponents (15).”
    Quote in the paperSubstantial claim1 of 4 sources checked
    • cites [33] M. P. Fiorina, Unstable Majorities: Polarization, Party Sorting, and Political Stalemate (Hoover Press, 2017).

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [18] L. Mason, A cross-cutting calm: How social sorting drives affective polarization. Public Opin. Q. 80, 351– 377 (2016). source
    • cites [34] Pew Research Center, Partisanship and Political Animosity in 2016: Highly Negative Views of the Opposing Party and Its Members (2016). https://www.pewresearch.org/politics/2016/06/22/partisanship-and-political-animosity-in-2016/. Accessed 17 September 2022.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [15] S. Iyengar, G. Sood, Y. Lelkes, Affect, not ideology: A social identity perspective on polarization. Public Opin. Q. 76, 405– 431 (2012). source
  • May combine two claims.

    Premisecitation

    Partisan social media users tend to interact across the ideological divide, but this interaction tends to be contentious and conflictual rather than rational deliberation.

    “Research on social media data tells a similar story: while partisan social media users do tend to interact across the ideological divide (62), this interaction is not characterized by rational arguments and deliberation but tends to be contentious and conflictual, suggesting that users may not be engaging in good faith attempts at seeing things through other perspectives (98–100).”
    Quote in the paperSubstantial claim2 of 4 sources checked
    • cites [62] P. Barberá, J. T. Jost, J. Nagler, J. A. Tucker, R. Bonneau, Tweeting from left to right: Is online political communication more than an echo chamber? Psychol. Sci. 26, 1531– 1542 (2015). 26297377 source
    • cites [98] G. Evolvi, Hate in a tweet: Exploring internet-based islamophobic discourses. Religions (Basel) 9, 307 (2018). source

      Section 3 (Brexit and Twitter Islamophobia; page unavailable) says Islamophobic Twitter groups rarely converse with Muslims and instead establish an antagonistic relationship with them. Section 5.2 describes derogatory tweets intended to upset other users. This supports the contentious-interaction portion of the citing sentence, but the paper’s post-Brexit Islamophobia findings do not establish that characterization for partisan social media users generally. The separate claim that users interact across the ideological divide is cited to another source (62). (LLM, conf=0.85)

      Experimental — accuracy not yet measured
    • cites [99] R. Moernaut, J. Mast, M. Temmerman, M. Broersma, Hot weather, hot topic. Polarization and sceptical framing in the climate debate on Twitter. Inform. Commun. Soc. 25, 1047– 1066 (2022). source

      The Conclusion reports that when interactions occurred between climate sceptics and believers on Twitter, they tended to be antagonistic and aimed at delegitimizing the other group rather than fostering constructive debate. This supports the contentious-interaction portion attributed to this source, but the study does not establish that pattern for partisan social media users generally. The separate claim that users interact across the ideological divide is cited to another source (62). (LLM, conf=0.85)

      Experimental — accuracy not yet measured
    • cites [100] A. Gruzd, J. Roy, Investigating political polarization on Twitter: A Canadian perspective. Policy Internet 6, 28– 45 (2014). source
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Social media is characterized by intense interaction across the political divide.

    “This evidence has been taken to suggest that in contrast to the assumptions of the selective exposure hypothesis, social media is in fact characterized by intense interaction across the political divide (73).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [73] A. Keuchenius, P. Törnberg, J. Uitermark, Why it is important to consider negative ties when studying polarized debates: A signed network analysis of a Dutch cultural controversy on Twitter. PLoS One 16, e0256696 (2021). 34464396 PMC8407581 source

      The Results (Coalitions and divisions in the debate; page unavailable) document antagonistic interaction between opposing groups in the Dutch Black Pete debate on Twitter. But the Conclusion and discussion says the study concerns one debate, time period, country, and platform, and leaves broader generalization to future research. It does not establish that social media generally is characterized by intense interaction across political divides. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
  • May combine two claims.

    Premisecitation

    Studies on social media have found limited evidence for homogeneous clusters on most social media platforms; users may be unlikely to rebroadcast opposing content but are often exposed to it and may respond.

    “Studies on social media have found limited evidence for the described homogeneous clusters on most social media platforms: while users may be unlikely to rebroadcast content from the opposing side, they are often exposed to it and may even respond (11, 62–69).”
    Quote in the paperSubstantial claim4 of 9 sources checked
    • cites [11] R. Karlsen, K. Steen-Johnsen, D. Wollebaek, B. Enjolras, Echo chamber and trench warfare dynamics in online debates. Eur. J. Commun. 32, 257– 273 (2017). 28690351 PMC5482382 source

      The Trench warfare dynamics section says there is little evidence that people avoid political diversity online, and the Conclusion reports that people frequently encounter opposing arguments and can interact with those holding opposite views. The paper does not establish this pattern across most social media platforms or address whether users rebroadcast opposing content; its Conclusion cautions that the dynamics may differ by platform. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
    • cites [62] P. Barberá, J. T. Jost, J. Nagler, J. A. Tucker, R. Bonneau, Tweeting from left to right: Is online political communication more than an echo chamber? Psychol. Sci. 26, 1531– 1542 (2015). 26297377 source
    • cites [63] S. Goel, W. Mason, D. J. Watts, Real and perceived attitude agreement in social networks. J. Pers. Soc. Psychol. 99, 611– 621 (2010). 20731500 source
    • cites [64] E. Bakshy, S. Messing, L. A. Adamic, Exposure to ideologically diverse news and opinion on Facebook. Science 348, 1130– 1132 (2015). 25953820 source
    • cites [65] E. Colleoni, A. Rozza, A. Arvidsson, Echo chamber or public sphere? Predicting political orientation and measuring political homophily in Twitter using big data. J. Commun. 64, 317– 332 (2014). source
    • cites [66] E. Lawrence, J. Sides, H. Farrell, Self-segregation or deliberation? Blog readership, participation, and polarization in American politics. Perspect. Polit. 8, 141– 157 (2010). source

      The Blog Authors section says cross-ideological links are infrequent, but some involve substantive argument and conversation, supporting the possibility of responses to opposing views. The Homophily and Polarization in the Blogosphere section instead finds that 94% of political blog readers read only blogs from one ideological side. The paper studies political blogs, not most social media platforms, and does not establish that users are often exposed to opposing content. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [67] C. Vaccari, Of echo chambers and contrarian clubs: Exposure to political disagreement among German and Italian users of Twitter. Soc. Media Soc. 2, 1– 24 (2016). source

      The Introduction and Conclusion report that German and Italian Twitter users encountered opposing views, even though homogeneity was the modal outcome. The paper does not establish that homogeneous clusters have limited evidence across most social media platforms, nor do the cited passages assess whether users rebroadcast or respond to opposing content. Our copy provides no page numbers for these passages. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [68] S. Yardi, D. Boyd, Dynamic debates: An analysis of group polarization over time on twitter. Bull. Sci. Technol. Soc. 30, 316– 327 (2010). source
    • cites [69] G. De Francisci Morales, C. Monti, M. Starnini, No echo in the chambers of political interactions on Reddit. Sci. Rep. 11, 2818 (2021). 33531520 PMC7854755 source

      The Introduction and Discussion (pages unavailable) report that, in Reddit discussions of the 2016 US election, opposing political groups interacted more often than expected and Clinton supporters were particularly likely to answer Trump supporters. That supports the possibility of exposure and response, but the paper does not establish limited homogeneous clustering on most social media platforms; its Discussion describes echo chambers on other platforms. It also does not establish a general pattern of users declining to rebroadcast opposing content. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
  • May combine two claims.

    Premisecitation

    Partisans consume media from across the partisan divide but do not trust what opposing media channels tell them.

    “In other words, partisans consume media from across the partisan divide but do not trust in what opposing media channels tell them.”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [96] A. M. Guess, P. Barberá, S. Munzert, J. Yang, The consequences of online partisan media. Proc. Natl. Acad. Sci. U.S.A. 118, e2013464118 (2021). 33782116 PMC8040813 source

      The Discussion (page not available) says exposure to cross-cutting information is relatively common. It also reports reduced overall trust in mainstream media and suggests people may discount challenging content. It does not establish that partisans specifically distrust what opposing media channels tell them; that conclusion is more definite and more source-specific than the paper's finding. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [97] M. Jurkowitz, A. Mitchell, E. Shearer, M. Walker, US media polarization and the 2020 election: A nation divided (Pew Research Center, 2020). https://www.pewresearch.org/journalism/2020/01/24/u-s-media-polarization-and-the-2020-election-a-nation-divided/. Accessed 17 September 2022.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    The negative influence/backfire effect is elusive, with limited relevance for politics outside the laboratory; while we may be less influenced by political opponents, we are unlikely to be negatively influenced by them.

    “This has brought researchers to conclude that negative influence effect is elusive, with limited relevance for politics outside the laboratory (88, 90, 93–95): while we may be less influenced by our political opponents, we are unlikely to be negatively influenced by them.”
    Quote in the paperNot a substantial claim2 of 5 sources checked
    • cites [88] D. M. Kahan, “The politically motivated reasoning paradigm, part 1: What politically motivated reasoning is and how to measure it” in Emerging Trends in the Social and Behavioral Sciences: An Interdisciplinary, Searchable, and Linkable Resource, R. A. Scott, S. M. Kosslyn, Eds. (John Wiley & Sons, Hoboken, NJ, 2015), pp. 1– 16. source
    • cites [90] T. Wood, E. Porter, The elusive backfire effect: Mass attitudes’ steadfast factual adherence. Polit. Behav. 41, 135– 163 (2019). source
    • cites [93] R. S. Nickerson, Confirmation bias: A ubiquitous phenomenon in many guises. Rev. Gen. Psychol. 2, 175 (1998). source
    • cites [94] D. M. Kahan, Ideology, motivated reasoning, and cognitive reflection: An experimental study. Judgm. Decis. Mak. 8, 407– 424 (2012). source

      Section 5.1 reports ideologically motivated reasoning in an experiment, and Section 3.3 discusses how biased assessment of evidence might polarize beliefs. Neither passage addresses whether messages from political opponents cause a negative influence or backfire effect, or whether such an effect is rare outside the laboratory. Searches for those terms and for opposing-message effects found no passage settling the claim. (LLM, conf=0.72)

      Experimental — accuracy not yet measured
    • cites [95] K. Takács, A. Flache, M. Mäs, Discrepancy and disliking do not induce negative opinion shifts. PLoS One 11, 1– 21 (2016). PMC4917087 27333160 source

      The Summary and Conclusion reports no support for negative opinion shifts in the authors’ controlled experiments. It does not establish that the effect has limited relevance to politics outside the laboratory: the authors explicitly say they cannot exclude negative influence in field settings, and they did not study political opponents as such. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
  • May combine two claims.

    Interpretationcitation

    Digital media are spaces for social identity formation and for symbolic displays of solidarity with allies and difference from outgroups.

    “The model thus suggests rethinking digital media as not merely arenas for rational deliberation and political debate but as spaces for social identity formation and for symbolic displays of solidarity with allies and difference from outgroups (27).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [27] P. Törnberg, J. Uitermark, Tweeting ourselves to death: The cultural logic of digital capitalism. Media Cult. Soc. 44, 1– 20 (2022). source
  • May combine two claims.

    Findingown data

    When γ is 0.5, ψ rises more slowly and settles on a lower value.

    “When γ is high, ψ quickly reaches a high level; when γ is 0.5, ψ rises more slowly and settles on a lower value; and with γ = 0, ψ remains fixed at a low level.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: Partisan affiliation is fixed throughout the model run, assuming it changes on a slower timescale than other attributes.
    • The authors state this as an assumption: Social similarity is relative to the larger social context.
    • The authors state this as an assumption: Nonlocal interlocutors are chosen without bias toward self-similarity.
  • May combine two claims.

    Findingreasoning

    The result is the crystallization of conflicting identities and the intensification of polarization, driven by a process in which sorting begets sorting and polarization begets polarization.

    “The result is the crystallization of conflicting identities and the intensification of polarization, driven by a process in which sorting begets sorting and polarization begets polarization.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationreasoning

    Digital media may drive a sorting of differences, which has been linked to a breakdown of social cohesion and rising affective polarization.

    “This paper provides a causal mechanism to explain this rise in polarization, by identifying how digital media may drive a sorting of differences, which has been linked to a breakdown of social cohesion and rising affective polarization.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: Partisan affiliation is fixed throughout the model run, assuming it changes on a slower timescale than other attributes.
    • The authors state this as an assumption: Social similarity is relative to the larger social context.
    • The authors state this as an assumption: Nonlocal interlocutors are chosen without bias toward self-similarity.
  • May combine two claims.

    Interpretationreasoning

    The mechanism is that diverse and nonlocal interactions of digital media drive plural conflicts to align along partisan lines, not that isolation drives divergence of opinions.

    “The suggested mechanism essentially turns the echo chamber on its head: it is not that isolation drives divergence of opinions but that the diverse and nonlocal interactions of digital media drive plural conflicts to align along partisan lines.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: Partisan affiliation is fixed throughout the model run, assuming it changes on a slower timescale than other attributes.
    • The authors state this as an assumption: Social similarity is relative to the larger social context.
    • The authors state this as an assumption: Nonlocal interlocutors are chosen without bias toward self-similarity.
  • May combine two claims.

    Premisenone given

    Such exposure does not seem to lead to political moderation: individuals are readily influenced by those they view as already similar to themselves, while disregarding messages from those they view as the outgroup.

    “At the same time, such exposure does not seem to lead to political moderation: individuals are readily influenced by those they view as already similar to themselves, while disregarding messages from those they view as the outgroup.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    Digital media can intensify affective polarization by contributing to a runaway process in which more and more issues become drawn into a single growing social and cultural divide, in turn driving a breakdown of social cohesion.

    “The model thus suggests that digital media can intensify affective polarization by contributing to a runaway process in which more and more issues become drawn into a single growing social and cultural divide, in turn driving a breakdown of social cohesion.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: Partisan affiliation is fixed throughout the model run, assuming it changes on a slower timescale than other attributes.
    • The authors state this as an assumption: Social similarity is relative to the larger social context.
    • The authors state this as an assumption: Nonlocal interlocutors are chosen without bias toward self-similarity.
  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationreasoning

    The two points of empirical evidence (digital media increases cross-cutting interaction; exposure does not moderate) provide the foundation for an alternative hypothesis for media polarization.

    “The suggestion of this paper is that these two points of empirical evidence may not only be reason to reject the echo chamber hypothesis (26), but they also provide the foundation for an alternative hypothesis for media polarization.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Premisecitation

    Individuals are more influenced by those similar to them.

    “Following the idea that we are more influenced by those similar to us, the node is then influenced as a function of the similarity with its interlocutors.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [104] R. Axelrod, The dissemination of culture: A model with local convergence and global polarization. J. Conflict Resolut. 41, 203– 226 (1997). source
  • May combine two claims.

    Premisecitation

    Digitalization does not appear to lead to a reduction of interaction across the political divide; it confronts us with diverse individuals, perspectives, and viewpoints, often in contentious ways.

    “In summary, the empirical literature suggests that digitalization does not appear to lead to a reduction of interaction across political divide, but quite the opposite: it confronts us with diverse individuals, perspectives, and viewpoints, often in contentious ways.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The degree to which political divisions have come to dominate cultural life remains subject to academic debate, with a recent study finding that while some lifestyle preferences are politically polarized, most remain shared across the political divide.

    “The degree to which political divisions have come to dominate cultural life, however, remains subject to academic debate, with a recent study finding that while some lifestyle preferences are politically polarized, most remain shared across the political divide (54).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [54] S. Praet, A. M. Guess, J. A. Tucker, R. Bonneau, J. Nagler, What’s not to like? Facebook page likes reveal limited polarization in lifestyle preferences. Polit. Commun. 39, 311– 338 (2022). source
  • Classified as probably not a substantial claim.

    Premisecitation

    The causal link between digital media and polarization runs not through divergence of opinions but via the dynamics of partisan sorting.

    “According to these scholars, sorting is thus central to understanding the rise in polarization and the growing sense of difference, distrust, and disdain between opposing partisans, suggesting that the causal link between digital media and polarization runs not through divergence of opinions but rather via the dynamics of partisan sorting (19).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [19] M. Levendusky, The Partisan Sort: How Liberals Became Democrats and Conservatives Became Republicans (University of Chicago Press, 2009). source
  • May combine two claims.

    Interpretationcitation

    The paper's two points of empirical evidence may be reason to reject the echo chamber hypothesis and provide the foundation for an alternative emergent causal mechanism underlying the polarizing effects of digital media.

    “The suggestion of this paper has been that these two points of empirical evidence may not only be reason to reject the echo chamber hypothesis (26), but that they also provide the foundation for an alternative emergent causal mechanism underlying the polarizing effects of digital media.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [26] A. Guess, B. Nyhan, B. Lyons, J. Reifler, Avoiding the echo chamber about echo chambers. Knight Foundation 2, 1– 25 (2018).

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    The simulations use an empirically chosen convergence metric, verified on a large number of cases and with substantial margin.

    “Unless otherwise specified, the simulations here therefore use an empirically chosen metric for when convergence has occurred, verified on a large number of cases and with substantial margin: the simulation ends either when no update has occurred during 10 runs across the full number of agents or to prevent runs becoming infinitely stuck in a dynamic equilibrium, after 1,000,000 iterations.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    Digital media intensify polarization not as echo chambers but as a sorting machine, fueling a runaway social process that destabilizes plural societies by drawing more and more issues into a single expanding social and cultural divide.

    “Digital media intensify polarization not as echo chambers but as a sorting machine, fueling a runaway social process that destabilizes plural societies by drawing more and more issues into a single expanding social and cultural divide.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationreasoning

    Sorting reduces partisans' mutual social influence, which further intensifies the process of sorting.

    “in turn reducing their mutual social influence which further intensifies the process of sorting.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationown data

    If individuals are more influenced by those who are similar to them, interaction outside of local bubbles can result in increased partisan sorting, in turn associated to affective polarization.

    “This is a striking result, showing that if individuals are more influenced by those who are similar to them, interaction outside of local bubbles can result in increased partisan sorting, in turn associated to affective polarization.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: Partisan affiliation is fixed throughout the model run, assuming it changes on a slower timescale than other attributes.
    • The authors state this as an assumption: Social similarity is relative to the larger social context.
    • The authors state this as an assumption: Nonlocal interlocutors are chosen without bias toward self-similarity.
  • May combine two claims.

    Interpretationreasoning

    It is not lack of exposure to competing ideas that leads to polarization but precisely that digital media brings us to interact outside of our local bubble.

    “it is not lack of exposure to competing ideas that lead to polarization but precisely that digital media brings us to interact outside of our local bubble.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S2 (checkable). May combine two claims.

    Interpretationreasoning

    This creates a maelstrom in which additional identities, beliefs, and cultural belonging become sucked into a growing and all-encompassing societal division, which threatens the very foundation of social cohesion.

    “creating a maelstrom in which additional identities, beliefs, and cultural belonging become sucked into a growing and all-encompassing societal division, which threatens the very foundation of social cohesion.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    Digital media throw us into a national political war, in which we are forced to take sides.

    “Digital media do not isolate us from opposing ideas; au contraire, they throw us into a national political war, in which we are forced to take sides.”
    Quote in the paperNot a substantial claim
27 of 27
  • The authors state this as an assumption.

    Partisan affiliation is fixed throughout the model run, assuming it changes on a slower timescale than other attributes.

    “Each agent i also has a single attribute, Si, corresponding to partisan affiliation, which held fixed throughout the model run (see also ref. 58).”
    “We here treat partisan affiliation as fixed, assuming that it will change on a slower timescale than the other attributes.”
  • The authors state this as an assumption.

    Social similarity is relative to the larger social context.

    “The social similarity is in other words treated as relative: that is, how similar we see ourselves to a particular individual depends on the larger social context (for instance, while the differences between Trotskyists and Stalinists may appear as a large chasm for members of the Party, they may for outsiders appear as a matter of relatively trivial detail).”
  • The authors state this as an assumption.

    Nonlocal interlocutors are chosen without bias toward self-similarity.

    “While the selective exposure hypothesis would suggest that these individuals would be selected with a bias toward self-similarity, we will here let the choice be unbiased as we are seeking to examine whether sorting can appear without such empirically questioned assumptions.”
3 of 3

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Because there is a large volume of people to connect with online, there are significantly more extreme voices to affiliate with than in prior social groups limited by geography.

    “Because there is such a large volume of people to connect with in the online context, there are significantly more extreme voices to affiliate with than there were in prior social groups that were limited by geography (Petersen et al. 2020, Törnberg 2022).”

    From Social Media and Morality. (2024) · cites this paper as Törnberg 2022

    The Discussion (page not provided) says digital media connect people outside their local social bubbles, supporting the comparison with geographically limited groups. It does not say that online networks offer significantly more extreme voices to affiliate with; the paper instead explains polarization through nonlocal interaction and partisan sorting. (LLM, conf=0.85)

    Experimental — accuracy not yet measured
  • No solo la homogeneidad polariza; la interacción intergrupal también lo hace.

    “algo que permite afirmar -de nuevo-que no solo la homogeneidad polariza, la interacción intergrupal también lo hace (Törnberg, 2022).”

    From Política, uso de medios y polarización afectiva en España (2024) · cites this paper as Törnberg, 2022

    The Results (Fig. 2; page unavailable) report that interaction outside local networks can increase partisan sorting associated with affective polarization. The claim omits a key condition: the model finds this effect when people are more influenced by similar others; with low influence homophily, it finds no partisan sorting regardless of the level of nonlocal interaction. The paper studies nonlocal interaction, which is not necessarily the same as intergroup interaction. (LLM, conf=0.86)

    Experimental — accuracy not yet measured

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Influence-homophily values disagree with Fig. 2

    Minor

    The Results text says the systematic simulations used h values of 1, 2, and 5, but the Fig. 2 caption identifies the three plotted values as 1, 4, and 8.

1 of 1

Cites

Flagged first, then by citations

Research works printed but not linked: 7

  1. C. R. Sunstein, Echo Chambers: Bush v. Gore, Impeachment, and Beyond (Princeton University Press, Princeton, NJ, 2001).
  2. A. Guess, B. Nyhan, B. Lyons, J. Reifler, Avoiding the echo chamber about echo chambers. Knight Foundation 2, 1–25 (2018).
  3. E. A. Nordlinger, Conflict Regulation in Divided Societies (Center for International Affairs, Harvard University, 1972).
  4. S. Levitsky, D. Ziblatt, How Democracies Die (Broadway Books, 2018).
  5. M. W. Macy J. A. Kitts A. Flache S. Benard "Polarization in dynamic networks: A Hopfield model of emergent structure" in Dynamic Social Network Modeling and Analysis R. Breiger K. Carley P. Pattison Eds. (National Academies Press Washington DC 2003) pp.162–173.
  6. R. P. Abelson “Mathematical models of the distribution of attitudes under controversy” in Contributions to Mathematical Psychology N. Fredericksen H. Gullicksen Eds. (Holt Rinehart and Winston New York NY 1964) pp.142–165.
  7. E. Klein, Why We’re Polarized (Simon and Schuster, 2020).

Cited by

Sorted by citations

Authors
Törnberg, P.
Affiliations
University of Neuchâtel (CH)
Corresponding author
Törnberg, Petter
Venue
Proceedings of the National Academy of Sciences
Published
2022-10-10
Volume
119
Issue
42
Pages
e2207159119-e2207159119
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
OpenAlex
W4304098849
Cited by
288
References
110
Citations by year
2026: 76 · 2025: 75 · 2024: 79 · 2023: 52 · 2022: 6
FWCI
81.17
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
  • UvA-DARE (University of Amsterdam) (acceptedVersion, cc-by-nc-nd)
  • PubMed Central (submittedVersion, cc-by-nc-nd)
  • RePEc: Research Papers in Economics (submittedVersion)
  • Data Archiving and Networked Services (DANS) (submittedVersion, other-oa)
Funders
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (VI.Veni.201S.006)
Topics
  • Social Sciences › Communication › Social Media and Politics
  • Social Sciences › Political Science and International Relations › Electoral Systems and Political Participation
  • Physical Sciences › Physics and Astronomy › Statistical and Nonlinear Physics › Opinion Dynamics and Social Influence
Keywords
affective polarization, digital media, partisan sorting, opinion dynamics, nonlocal interactions, local interactions, political polarization, social media
MeSH terms
Attitude, Humans, Politics, Internet

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-13.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-13.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

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