Determinants of Partisan Strength and In-Party Affect: A Scoping Review

Recent years have seen a global surge in affective polarization, extending from the US to European and Asian democracies. Concurrently, empirical research proliferates, exploring factors driving this rise, with significant focus on aspects like partisan strength and in-party affective attitude. This scoping review sheds light on investigated predictors of partisan strength and in-party affect and associated mechanisms of influence on the two key outcomes to better our understanding of affective polarization and the current research in the field. Employing a standardized search protocol across seven databases, we reviewed 26,148 reports, yielding 32 eligible reports with 48 studies and 56 predictors. Notably, we found a clear positive correlation between partisan strength and in-party affect. However, the impact of political knowledge on partisan strength was inconclusive, with contrasting findings implying a critical role of the need to differentiate between parties by platform information, in reinforcing partisan strength. Our study also highlighted the role of selective exposure and biased interpretation in reinforcing partisan attitudes. Furthermore, we identified significant variations in the effects of social sorting, with objective membership and social identities such as gender or religion playing mediating and moderating roles, respectively. The salience of in-party identity was also shown to enhance partisan strength. We also identified significant limitations and opportunities in the current research landscape of affective polarization. Key findings indicate insufficient representation from Asian and African voters, and limited cross-continental collaboration. This Western-centric approach overlooks the global nature of affective polarization. Additionally, inconsistencies in the operationalization of partisan strength and a lack of empirical testing for proposed mechanisms are notable gaps. Recognizing these shortcomings, the review suggests that future research should expand geographic and cultural perspectives and refine methodological approaches to provide a more nuanced understanding of partisan behaviours and affective polarization.