Cited by 629Social Media and PoliticsMisinformation and Its ImpactsComplex Network Analysis Techniques

Political Polarization on Twitter

Open access
Conover, Michael, Ratkiewicz, Jacob, Francisco, Matthew, Goncalves, Bruno, Menczer, Filippo, Flammini, Alessandro·2021·Proceedings of the International AAAI Conference on Web and Social Media

Abstract

In this study we investigate how social media shape the networked public sphere and facilitate communication between communities with different political orientations. We examine two networks of political communication on Twitter, comprised of more than 250,000 tweets from the six weeks leading up to the 2010 U.S. congressional midterm elections. Using a combination of network clustering algorithms and manually-annotated data we demonstrate that the network of political retweets exhibits a highly segregated partisan structure, with extremely limited connectivity between left- and right-leaning users. Surprisingly this is not the case for the user-to-user mention network, which is dominated by a single politically heterogeneous cluster of users in which ideologically-opposed individuals interact at a much higher rate compared to the network of retweets. To explain the distinct topologies of the retweet and mention networks we conjecture that politically motivated individuals provoke interaction by injecting partisan content into information streams whose primary audience consists of ideologically-opposed users. We conclude with statistical evidence in support of this hypothesis.

AI snapshot

Written from the paper’s full text.

TL;DR

Conover et al. analyze political communication on Twitter during the six weeks before the 2010 U.S. midterm elections, using retweet and mention networks built from 252,300 politically relevant tweets. They find that the retweet network is highly segregated along partisan lines, while the mention network is dominated by a single politically heterogeneous cluster, with cross-ideological interaction linked to hashtag content injection.

Key findings

  • The retweet network is highly polarized: its modularity is 0.48 versus 0.17 for the mention network, and its modularity z-score against degree-preserving shuffled graphs is 11.02 versus 2.06 for mentions. In the retweet network, cluster A is 93.4% right-leaning and cluster B is 80.1% left-leaning.
  • The mention network is politically heterogeneous: it is dominated by a single cluster accounting for more than 97% of users, and cross-ideological links are much more common than in retweets. Observed/expected link ratios for cross-ideological interaction are 0.68 (Left→Right) and 0.77 (Right→Left) in mentions, versus 0.05 and 0.03 in retweets.
  • Manual annotation found most politically active users express a political identity: both annotators could not determine identity for only 8% of users, and more than 75% had unambiguous political valences when requiring both annotators to agree. Cohen’s Kappa was 0.80 for left and 0.82 for right, but only 0.42 for undecidable.
  • Hashtag content injection helps explain the difference: users with neutral or mixed-valence hashtags receive and produce more inter-ideological mentions, and nearly 30% of tweets in the #p2 search feed originated from right-leaning users. Example valences include #tcot = 0.384 and #p2 = -0.605.

Methods

  • Data were collected from Twitter’s gardenhose API between September 14 and November 1, 2010, observing approximately 355 million tweets. Political content was identified using seed hashtags #p2 and #tcot, a Jaccard similarity threshold of 0.005, 66 unique hashtags, and exclusion of 11 ambiguous hashtags, yielding 252,300 politically relevant tweets from more than 45,000 users.
  • The authors constructed retweet and mention networks. The retweet network had 23,766 non-isolated nodes out of 45,365 total, with an 18,470-node largest connected component; the mention network had 10,142 non-isolated nodes out of 17,752 total, with a 7,175-node largest component. Analyses focused on the largest connected components.
  • Community detection used label propagation seeded by leading-eigenvector modularity maximization for two communities, run 100 times and compared with Adjusted Rand Index. The authors compared observed modularity to 1,000 degree-preserving shuffled graphs, manually annotated 1,000 random users with a non-author judge on 200, and analyzed observed versus expected cross-ideological links and hashtag valence.

Limitations

  • The paper states that direct modularity comparison is problematic because the retweet and mention networks differ in size and connectivity, so it uses shuffled graphs as a baseline; it also notes that the normality assumption for modularity values is false and uses Chebyshev’s inequality instead. It further states that cross-ideological interactions are “almost certainly not a panacea” and may reinforce polarization, and calls for further sentiment analysis and follower-network studies.
  • Evident from the text: the sample is limited to six weeks before the 2010 U.S. midterm elections and to tweets containing a discovered set of political hashtags, so findings may not generalize to other periods, elections, or political contexts.
  • Evident from the text: manual political alignment was based on 1,000 users, the undecidable category had only fair-to-moderate inter-annotator agreement (κ = 0.42), and the mention network is smaller than the retweet network, which may affect comparisons.

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

Integrity signals

Registry

Crossref · 10.1609/icwsm.v5i1.14126

Cites

22 of 22 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 10 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    In the mention network, users placed in the same cluster are not likely to be much more similar to each other than users in different clusters.

    “Figure 2 shows that in the mention network, users placed in the same cluster are not likely to be much more similar to each other than users in different clusters.”
    Quote in the paperSubstantial claim
  • Findingown data

    The community structure found in the retweet network is significantly more segregated than that found in the mention network.

    “We conclude that the community structure found in the retweet network is significantly more segregated than that found in the mention network.”
    Quote in the paperSubstantial claim
  • Findingown data

    In both mention and retweet networks, one of the clusters is more cohesive than the other, meaning tag usage within one community is more homogeneous.

    “Further, we note that in both mention and retweet networks, one of the clusters is more cohesive than the other -meaning the tag usage within one community is more homogeneous.”
    Quote in the paperNot a substantial claim
  • Findingown data

    All differences in average similarities between same-cluster and different-cluster user pairs in the retweet and mention networks are significant at the 95% confidence level.

    “All differences are significant at the 95% confidence level.”
    Quote in the paperSubstantial claim
  • Findingown data

    A majority of politically active users on Twitter express a political identity in their tweets.

    “Based on this analysis it is clear that a majority of politically active users on Twitter express a political identity in their tweets.”
    Quote in the paperSubstantial claim
  • May combine two claims. 18
  • Classified as probably not a substantial claim. 10
  • May combine two claims.

    Findingown data

    The retweet and mention networks exhibit very similar scale-free topology (power-law degree distribution), with a number of users receiving or spreading a huge amount of information.

    “We observe that the retweet and mention networks exhibit very similar scale-free topology (power-law degree distribution not shown), with a number of users receiving or spreading a huge amount of information.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    The retweet network of political communication on Twitter in the six weeks before the 2010 U.S. midterm elections exhibited a highly modular, segregated partisan structure, with two homogenous communities corresponding to the political left and right and extremely limited connectivity between left- and right-leaning users.

    “Using a combination of network clustering algorithms and manually-annotated data we demonstrate that the network of political retweets exhibits a highly segregated partisan structure, with extremely limited connectivity between left-and right-leaning users.”
    • Also stated in: § 1 Introduction · boosted
      “We demonstrate that the retweet network exhibits a highly modular structure, segregating users into two homogenous communities corresponding to the political left and right.”
    • Also stated in: § 3.1 Community Structure · plain
      “In summary, the retweet network contains two clusters of users who preferentially propagate content within their own communities.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    In the retweet network, users in cluster A are more likely to have very similar profiles than users in cluster B, and users in different clusters are the least similar to each other.

    “On the other hand, in the retweet network, users in cluster A are more likely to have very similar profiles than users in cluster B, and users in different clusters are the least similar to each other.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    The retweet network exhibits two distinct communities of users, while the mention network is dominated by a single massive cluster of interconnected users.

    “The retweet network exhibits two distinct communities of users, while the mention network is dominated by a single massive cluster of interconnected users.”
    • Also stated in: § 3.1 Community Structure · plain
      “Figure 1 shows the retweet and mention networks, laid out using a force-directed layout algorithm (Fruchterman and Reingold 1991), with node colors determined by the assigned communities.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    The user-to-user mention network on Twitter in the same period did not exhibit political segregation; it was dominated by a single politically heterogeneous cluster in which ideologically opposed individuals interacted at a much higher rate than in the retweet network.

    “Surprisingly this is not the case for the user-to-user mention network, which is dominated by a single politically heterogeneous cluster of users in which ideologically-opposed individuals interact at a much higher rate compared to the network of retweets.”
    • Also stated in: § 1 Introduction · plain
      “In contrast, we find that the mention network does not exhibit this kind of political segregation, resulting in users being exposed to individuals and information they would not have been likely to choose in advance.”
    • Also stated in: § 1 Introduction · plain
      “These data also show the mention network to be politically heterogeneous, with users of opposing political views interacting at a much higher rate than in the retweet network”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    The retweet network clusters correspond to groups of users of similar political alignment, showing the retweet network is polarized on a partisan basis.

    “Manual classification of Twitter users by political alignment, demonstrating that the retweet network clusters correspond to the political left and right.”
    • Also stated in: § 3 Cluster Analysis · boosted
      “by manually annotating users, we show that the retweet network is polarized on a partisan basis, while the mention network is much more politically heterogeneous.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    The modularity induced by the communities in the retweet and mention networks was 0.48 and 0.17, respectively.

    “The modularity induced by the communities in the retweet and mention networks have values of 0.48 and 0.17, respectively.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Findingreasoning

    Nearly 30% of the tweets in the #p2 search feed originate from right-leaning users.

    “nearly 30% of the tweets in the #p2 search feed would originate from right-leaning users.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    Increasing the number of target communities in the mention network does not reveal a more fine-grained ideological structure, but instead results in smaller yet politically heterogeneous clusters.

    “Increasing the number of target communities in the mention network does not reveal a more fine-grained ideological structure, but instead results in smaller yet politically heterogeneous clusters.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingnone given

    Ideologically-opposed users interact with one another, either through mentions or content injection, but they very rarely share information from across the divide with other members of their community.

    “While we know for certain that ideologically-opposed users interact with one another, either through mentions or content injection, they very rarely share information from across the divide with other members of their community.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisereasoning

    Retweets and mentions serve distinct and complementary purposes, together acting as the primary mechanisms for explicit, public user-user interaction on Twitter.

    “These two means of communication -retweets and mentions-serve distinct and complementary purposes, together acting as the primary mechanisms for explicit, public user-user interaction on Twitter.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Mentions function differently from retweets, allowing someone to address a specific user directly through the public feed, or, to a lesser extent, refer to an individual in the third person.

    “Mentions function differently, allowing someone to address a specific user directly through the public feed, or, to a lesser extent, refer to an individual in the third person (Honeycutt and Herring 2008).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Honeycutt and Herring 2008

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

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    A non-author judge with broad knowledge of politics annotated 200 random users from the set of 1,000 to establish reproducibility of the annotation scheme.

    “In line with the standards of the field, we had a non-author judge with a broad knowledge of politics annotate 200 random users from the set of 1,000 to establish the reproducibility of this annotation scheme.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Study design and conductcitation

    Inter-annotator agreement between the 'left' and 'right' categories was κ = 0.80 and κ = 0.82, respectively, falling in the 'nearly perfect agreement' range.

    “For agreement between the 'left' and 'right' categories we report κ = 0.80 and κ = 0.82 respectively, both of which fall in the "nearly perfect agreement" range (Landis and Koch 1977).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Landis and Koch 1977 source
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Retweets act as a form of endorsement, allowing individuals to rebroadcast content generated by other users, thereby raising the content's visibility.

    “Retweets act as a form of endorsement, allowing individuals to rebroadcast content generated by other users, thereby raising the content's visibility (boyd, Golder, and Lotan 2008).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites boyd, Golder, and Lotan 2008

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

  • May combine two claims.

    Study design and conductown data

    The high agreement across runs suggests the clusters are consistent, so consensus clustering was avoided.

    “Such a high agreement suggests that the clusters are consistent, and therefore we avoid resorting to consensus clustering for simplicity.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationreasoning

    The injection of partisan content into ideologically opposed hashtag streams results in users being exposed to content they are not likely to rebroadcast, but to which they may respond using mentions.

    “We argue that this process results in users being exposed to content they are not likely to rebroadcast, but to which they may respond using mentions, and provide statistical evidence in support of this hypothesis.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Each hashtag identifies a stream of content, with users' tag choices denoting participation in different information channels.
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Political blogs preferentially link to other blogs of the same political ideology.

    “Adamic and Glance (2005) famously demonstrated that political blogs preferentially link to other blogs of the same political ideology, a finding supported by the work of Hargittai, Gallo, and Kane (2007).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Adamic and Glance (2005) source
    • cites Hargittai, Gallo, and Kane (2007) source
  • May combine two claims.

    Premisecitation

    Consumers of online political information tend to choose to read blogs that share their political beliefs, with 26% more users doing so in 2008 than 2004.

    “Consumers of online political information tend to behave similarly, choosing to read blogs that share their political beliefs, with 26% more users doing so in 2008than 2004(Pew Internet and American Life Project 2008).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Pew Internet and American Life Project 2008

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

  • Classified as probably not a substantial claim.

    Premisecitation

    Politically active web users tend to organize into insular, homogenous communities segregated along partisan lines.

    “Despite this, some empirical evidence suggests that politically active web users tend to organize into insular, homogenous communities segregated along partisan lines.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Adamic and Glance (2005) source
    • cites Hargittai, Gallo, and Kane (2007) source
  • May combine two claims.

    Study design and conductown data

    Inter-annotator agreement for the undecidable category was fair to moderate (κ = 0.42), indicating that there are users for whom a political identity might be discernible in the context of specific domain knowledge.

    “For the undecidable category we found "fair to moderate" agreement (κ = 0.42), indicating that there are users for whom a political identity might be discernible in the context of specific domain knowledge.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationown data

    Many messages contain sentiments more extreme than you would expect to encounter in face-to-face interactions.

    “Many messages contain sentiments more extreme than you would expect to encounter in face-to-face interactions”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationnone given

    When a user is exposed to ideologically opposed content, she will be unlikely to rebroadcast it, but may choose to respond directly to the originator in the form of a mention.

    “We propose that when a user is exposed to ideologically opposed content in this way, she will be unlikely to rebroadcast it, but may choose to respond directly to the originator in the form of a mention.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Any Twitter user can select arbitrary hashtags to annotate his or her tweets.
  • Classified as probably not a substantial claim.

    Interpretationreasoning

    #p21 ostensibly serves as a place where progressives can be exposed only to content aligned with their views.

    “and ostensibly serves as a place where progressives can once again be exposed only to content aligned with their views.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Any Twitter user can select arbitrary hashtags to annotate his or her tweets.
24 of 24
  • The paper relies on this without support.

    When politically active individuals can avoid people and information they would not have chosen in advance, their opinions are likely to become increasingly extreme as a result of being exposed to more homogeneous viewpoints and fewer credible opposing opinions.

    “The concern is that when politically active individuals can avoid people and information they would not have chosen in advance, their opinions are likely to become increasingly extreme as a result of being exposed to more homogeneous viewpoints and fewer credible opposing opinions.”
  • The paper relies on this without support.

    A deliberative democracy relies on a broadly informed public and a healthy ecosystem of competing ideas.

    “A deliberative democracy relies on a broadly informed public and a healthy ecosystem of competing ideas.”
  • The paper relies on this without support.

    Each hashtag identifies a stream of content, with users' tag choices denoting participation in different information channels.

    “Each hashtag identifies a stream of content, with users' tag choices denoting participation in different information channels.”
  • The authors state this as an assumption.

    The modularities of shuffled graph cluster assignments are normally distributed.

    “This discussion assumes that the modularities of the shuffled graph cluster assignments are distributed normally, which is not true in general.”
  • The paper relies on this without support.

    The partisan nature of U.S. political discourse makes two a natural number of clusters.

    “While the partisan nature of U.S. political discourse makes two a natural number of clusters”
  • The paper relies on this without support.

    Any Twitter user can select arbitrary hashtags to annotate his or her tweets.

    “Any Twitter user can select arbitrary hashtags to annotate his or her tweets.”
6 of 6

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.

  • Collection dates span about seven weeks, not six

    Minor

    September 14 to November 1 spans 48 days, or 49 days if both endpoints are included. Neither is six weeks.

1 of 1

Cites

Flagged first, then by citations

Research works printed but not linked: 1

  1. Sunstein, C. R. 2007. Republic.com 2.0. Princeton Univer- sity Press.

Cited by

Sorted by citations

Authors
Conover, M., Ratkiewicz, J., Francisco, M., Goncalves, B., Menczer, F., & Flammini, A.
Affiliations
Indiana University (US)
Venue
Proceedings of the International AAAI Conference on Web and Social Media
Published
2021-08-03
Volume
5
Issue
1
Pages
89-96
ISSN
  • 2162-3449 (ISSN-L)
  • 2334-0770
OpenAlex
W4312820073
Cited by
626
References
21
Citations by year
2026: 34 · 2025: 66 · 2024: 86 · 2023: 82 · 2022: 65 · 2021: 62 · 2020: 45 · 2019: 33 · 2018: 40 · 2017: 26 · 2016: 22 · 2015: 25 · 2014: 21 · 2013: 10 · 2012: 7
FWCI
107.66
Type
conference paper
Language
en
Open access
Locations
  • Proceedings of the International AAAI Conference on Web and Social Media (publishedVersion)
  • AAAI Publications (The Association for the Advancement of Artificial Intelligence (AAAI)) (submittedVersion)
Topics
  • Social Sciences › Communication › Social Media and Politics
  • Social Sciences › Sociology and Political Science › Misinformation and Its Impacts
  • Physical Sciences › Physics and Astronomy › Statistical and Nonlinear Physics › Complex Network Analysis Techniques
Keywords
political polarization, Twitter, retweets, mentions, social network topology, 2010 midterm elections, political communication, information dissemination, network clustering

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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.

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

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