We are witnessing increasing partisan polarization across the world. It is often argued that partisan “echo chambers” are one of the drivers of both policy and affective polarization. In this article, we develop and test the argument that the political homogeneity of people’s social environment shapes polarization. Using an innovative, large-scale pre-registered “lab-in-the-field” experiment in the United Kingdom, we examine how polarization is influenced by partisan group homogeneity. We recruit nationally representative partisans and assign them to discuss a salient policy issue, either with like-minded partisans (an echo chamber) or in a mixed-partisan group. This allows us to examine how group composition affects polarization. In line with our expectations, we find that partisan echo chambers increase both policy and affective polarization compared to mixed discussion groups. This has important implications for our understanding of the drivers of polarization and for how out-group animosity might be ameliorated in the mass public.

The decision by a narrow majority of British voters to leave the European Union (EU) in 2016 was a political earthquake that few had seen coming. It produced new political divisions, not only between the United Kingdom and the rest of Europe but also within the United Kingdom. In particular, the referendum campaign and the outcome generated two new political identities: “Leavers” and “Remainers.” These Brexit identities crosscut partisan identities and voters formed deep emotional attachments to them (Curtice 2018; Evans and Schaffner 2019). Moreover, this Brexit divide led to affective polarization in the form of out-group animosity and discrimination (Hobolt, Leeper, and Tilley 2021). It also shaped perceptions of the economy (Sorace and Hobolt 2021), attitudes toward immigration (Pickup et al. 2021), vote choices (Hobolt and Rodon 2020), and losers’ consent (Schaffner 2021; Tilley and Hobolt 2023a). Brexit identities have been shown to be salient and politically consequential. Yet, we know much less about whether these new identities are rooted in policy norms that go beyond preferences about the desirability of leaving the EU. In this article, we thus explore the nature of Brexit identities and how they relate to policy norms.

How much public and elite support is there for the use of a citizens’ assembly – a random selection of citizens brought together to consider a policy issue – to tackle major, deadlock-inducing disagreements in deeply divided places with consociational political institutions? We focus on Northern Ireland and use evidence from a cross-sectional attitude survey, a survey-based experiment and elite interviews. We find that the general public support decision-making by a citizens’ assembly, even when the decision reached is one they personally disagree with. However, support is lower among those with strong ideological views. We also find that elected politicians oppose delegating decision-making power to an ‘undemocratic’ citizens’ assembly, but are more supportive of recommendation-making power. These findings highlight the potential for post-conflict consociations to be amended, with the consent of the parties, to include citizens’ assemblies that make recommendations but not binding policy.

A well-functioning democracy requires a degree of mutual respect and a willingness to talk across political divides. Yet numerous studies have shown that many electorates are polarized along partisan lines, with animosity towards the partisan out-group. This article further develops the idea of affective polarization, not by partisanship, but instead by identification with opinion-based groups. Examining social identities formed during Britain's 2016 referendum on European Union membership, the study uses surveys and experiments to measure the intensity of partisan and Brexit-related affective polarization. The results show that Brexit identities are prevalent, felt to be personally important and cut across traditional party lines. These identities generate affective polarization as intense as that of partisanship in terms of stereotyping, prejudice and various evaluative biases, convincingly demonstrating that affective polarization can emerge from identities beyond partisanship.

Conjoint analysis is a common tool for studying political preferences. The method disentangles patterns in respondents’ favorability toward complex, multidimensional objects, such as candidates or policies. Most conjoints rely upon a fully randomized design to generate average marginal component effects (AMCEs). They measure the degree to which a given value of a conjoint profile feature increases, or decreases, respondents’ support for the overall profile relative to a baseline, averaging across all respondents and other features. While the AMCE has a clear causal interpretation (about the effect of features), most published conjoint analyses also use AMCEs to describe levels of favorability. This often means comparing AMCEs among respondent subgroups. We show that using conditional AMCEs to describe the degree of subgroup agreement can be misleading as regression interactions are sensitive to the reference category used in the analysis. This leads to inferences about subgroup differences in preferences that have arbitrary sign, size, and significance. We demonstrate the problem using examples drawn from published articles and provide suggestions for improved reporting and interpretation using marginal means and an omnibus F-test. Given the accelerating use of these designs in political science, we offer advice for best practice in analysis and presentation of results.

This article argues that post-conflict consociational arrangements in ethnically divided societies incentivize moderation by political parties, but not policy differentiation outside the main conflict. This results in little policy-driven voting. Analysing party manifestos and voter survey data, we examine the evolution of party policy and cleavage voting under power-sharing in Northern Ireland 1998–2016. We find a reduction in ethno-national policy differences between parties and that ethno-nationalism has become less important in predicting vote choice for Protestants, but not Catholics. We also find little party differentiation in other policy areas and show that vote choices are largely independent of people's policy stances on economic or social issues. Our findings are thus largely consistent with a ‘top-down’ interpretation of political dynamics.

This article shows that religion has been consistently important in predicting voters’ party choices in Britain over time. The relationship between religion and party preference is not primarily due to the social make-up of different religious groups, nor to ideological differences between religious groups, whether in terms of social conservatism, economic leftism or national identity. Instead, particular denominations are associated with parties that represented those denominational groups in the early twentieth century when social cleavages were ‘frozen’ within the system. The main mechanism underpinning these divisions is parental transmission of party affiliations within denominations. These findings have important implications for how we understand both the persistence of social cleavages and the precise mechanisms that maintain social cleavages.

Why has the association between class and party declined over time? Contrary to conventional wisdom that emphasizes the fracturing of social structures and blurring of class boundaries in post-industrial society, it is argued here that class divisions in party preferences are conditioned by the changing shape of the class structure and the effect of parties’ strategic ideological responses to this transformation on the choices facing voters. This thesis is tested using British survey data from 1959 to 2006. We demonstrate that increasing class heterogeneity does not account for the decline of the class–party association, which occurs primarily as a result of ideological convergence between the main parties resulting from New Labour's shift to the centre.

This article examines how voters attribute credit and blame to governments for policy success and failure, and how this affects their party support. Using panel data from Britain between 1997 and 2001 and Ireland between 2002 and 2007 to model attribution, the interaction between partisanship and evaluation of performance is shown to be crucial. Partisanship resolves incongruities between party support and policy evaluation through selective attribution: favoured parties are not blamed for policy failures and less favoured ones are not credited with policy success. Furthermore, attributions caused defections from Labour over the 1997–2001 election cycle in Britain, and defections from the Fianna Fáil/Progressive Democrat coalition over the 2002–07 election cycle in Ireland. Using models of vote switching and controlling for partisanship to minimize endogeneity problems, it is shown that attributed evaluations affect vote intention much more than unattributed evaluations. This result holds across several policy areas and both political systems.

Governing parties generally win fewer votes at European Parliament elections thanat national electionsmost common explanation for this is that European electionsare ‘second order national elections’ acting as mid-termreferendums on government performance. This article proposes an alternative,though complementary, explanation: voters defect because governing parties aregenerally far more pro-European than the typical voter. Additionally, the morethe campaign context primes Eurosceptic sentiments, the more likely voters areto turn against governing parties. A multi-level model is used to test thesepropositions and analyse the effects of individual and contextual factors at the1999 and 2004 European Parliament elections. Both European and domestic concernsmatter to voters; moreover, campaign context plays an important role in shapingvote choices.

Political cleavages are often understood as deriving from either deep-rooted social divisions or institutional incentives. Contemporary Northern Ireland provides a test of the mutability of apparently entrenched cleavages to institutional change. Research undertaken before the ceasefire in the 1990s found noticeable asymmetries in the patterns of cleavage within the unionist and nationalist blocs. Within the unionist bloc, economic ‘left–right’ issues formed the main ideological division between the two major unionist parties. This contrasted with an ethno-national source of ideological division between the two nationalist parties. However, the emergence of a consociational form of government structure since then has demonstrated the ability of institutional incentives to reform some aspects of party competition swiftly. As evidence of this, we show that between 1989 and 2004 there was little change in the sources of support for Sinn Féin relative to the SDLP, but the influence of left–right ideology within the unionist bloc was negated as the influence of ethno-nationalism dramatically increased.

This article adapts and tests the theory of enlightened preferences on two British electoral cycles: 1992–97 and 1997–2001. Using individual-level panel data, it extends previous work by explicitly incorporating the role of political knowledge. Its findings are generally very supportive of the theory. It is shown that knowledge of party platforms varies through both electoral cycles in a manner predicted by the theory; that is, it is highest immediately following election campaigns; these changes in political knowledge are closely mirrored by changes in the explanatory power of a model of party choice containing so-called ‘fundamental variables’ (i.e. socio-demographic and issue-related variables) as predictors. More specifically, fundamental variables do a much better job of accounting for party choice during election years than in mid-cycle. Finally, for all years of both panels a positive interaction is found between political knowledge and the ability of voters to match their issue preferences to party platforms.

The Classic party identification model originally derves from the work of Campbell et al. in the 1960sAngus Campbell, Phillip E. Converse, Warren E. Miller and Donald E. Stokes, The American Voter (New York: Wiley, 1960).In The American Voter Campbell et al. noted that there was a large disparity by age between, first, the number of voters claiming an Independent identification in the United States and, secondly, the numbers claiming a strong identification with one of the two parties.