Democrats and Republicans clearly dislike one another. Yet, scholars debate whether policy disagreement or partisan identity, per se, drives interparty animus. Past studies suggest the relationship between partisanship and interpersonal affect is spurious, driven by inferred policy preferences. We argue, instead, that policy preferences signal partisan identity when the parties' stances on an issue are well-known. Using a nationally representative survey and four preregistered experiments, we disentangle the effects of policy disagreement and partisan identity on interpersonal affect. Our findings suggest that partisan identity is the principal mechanism of affective polarization, and that policy preferences factor into affective polarization largely by signaling partisan identity. However, our results also affirm that policy disagreement in itself drives interpersonal affect. This provides evidence that partisanship reflects an emotional attachment to a political party, not merely a running tally of rational considerations.

Survey experiments with nearly 7,000 Americans suggest that increasing the visibility of publishers is an ineffective, and perhaps even counterproductive, way to address misinformation on social media. Our findings underscore the importance of social media platforms and civil society organizations evaluating interventions experimentally, rather than implementing them based on intuitive appeal.

The fact checking field has grown tremendously in the past decade, as has academic interest in the practice, with dozens of studies testing the effectiveness of corrections. However, research on fact checking is not yet optimised to help fact checkers address the global challenges of mis‐ and disinformation. In this paper, we review the literature on fact checking’s effects and identify two key gaps. First, we discuss the limited diversity and external validity of existing studies, which have overwhelmingly been conducted in Western countries and under artificial, experimental conditions. Second, we argue that research has narrowly focussed on the short‐term, corrective effects of individual fact checks, largely ignoring the multiple ways fact checkers conceive of their impact. Thus, research has overlooked the cultural and systemic changes that fact checkers pursue. We conclude by highlighting opportunities for further research and for improving communication between academics and fact checkers.

In the United States, a popular explanation for rising partisan animosity and declining faith in democracy is that Republicans and Democrats misperceive each other to hold extreme policy attitudes. However, other aspects of group-attitude perceptions are likely as important to democracy. In particular, partisans may underestimate the diversity of Democrats' and Republicans' attitudes to harmful effect. This paper uses surveys and pre-registered experiments with representative and convenience samples (N = 6,158) to assess how much Americans underestimate within-party attitude diversity and to what consequence. We find that American partisans underestimate — by more than a factor of two — the diversity of each party's attitudes, and these misperceptions drive partisan animosity and perceived out-party threat. Yet, contrary to existing research, we find little evidence that American partisans consistently overestimate how radical the ``average'' Republican or Democrat is. Instead, our results suggest that ``perceived polarization'' may largely be a measurement artifact.

Political interest is a key predictor of likelihood to vote. We argue that the political interest–vote intention relationship can be explained by well-established theories that predict behavior across domains (e.g., theory of reasoned action, theory of planned behavior). Relying on the integrated behavioral model, we propose a core mediation model with vote likelihood (i.e., behavioral intention) as the dependent variable. Two types of media use (conservative and liberal–moderate) are then assessed in relation to the core model. We explore the ways in which our results contribute to theory and outline a research agenda.