When Reason Bows to Emotion: Affective Polarization and Cognitive Bias in Party Evaluation

Classic spatial models of electoral competition assume that voters accurately perceive party positions and select the party closest to their own ideological ideal point. A growing body of research, however, shows that such perceptions are systematically distorted: voters pull preferred parties closer to themselves (assimilation) and push disliked parties further away (contrast). This paper integrates these cognitive projection processes with the theory of affective polarization to explain how emotional attachments and hostilities shape voters’ mental maps of party competition in multiparty systems. Building on theories of motivated reasoning and social identity, the paper argues that affective polarization amplifies perceptual distortions in asymmetric ways. While positive affect toward in-parties fosters assimilation, rising affective polarization primarily sharpens contrast by intensifying hostility toward out-parties. As emotional divides deepen, negative partisanship becomes the dominant force shaping ideological perceptions, stretching voters’ cognitive maps of the political landscape and undermining the informational assumptions of proximity-based representation. Empirically, the study analyzes data from the 2023 Swiss Election Study (SELECTS), focusing on voters’ perceptions of the ideological positions of Switzerland’s six major parties: the Social Democratic Party, Swiss People’s Party, The Centre, The Liberals, the Green Party, and the Green Liberal Party. Switzerland constitutes a least-likely case for affective distortions. Its consensus-oriented institutions, frequent direct-democratic votes, and high-information environment should, in principle, foster accurate perceptions and limit polarization. Using a respondent–party dyadic design, the analysis estimates multilevel models linking voters’ self-placement on the left–right scale, supporter status, and individual-level affective polarization to perceived party positions. The results reveal three consistent patterns. First, supporters systematically assimilate, perceiving their preferred party as ideologically closer to their own position than non-supporters do. Second, non-supporters exhibit contrast, placing out-parties further away from their own position. Third, affective polarization amplifies these projection effects asymmetrically: as polarization increases, contrast among non-supporters grows markedly stronger, while assimilation among supporters remains comparatively stable. Moving from low to high levels of affective polarization nearly doubles the degree to which non-supporters exaggerate ideological distance to out-parties, whereas changes in supporter perceptions are modest. These findings contribute to the literature in three ways. First, they extend research on affective polarization to multiparty consensus democracies, showing that emotional divides distort ideological perceptions even in information-rich contexts. Second, they demonstrate that affective polarization operates less by strengthening in-group alignment than by intensifying out-group hostility, reshaping the geometry of party competition. Third, they highlight the normative implications of such distortions: exaggerated perceptions of ideological distance may undermine compromise, misinform electoral choice, and weaken democratic accountability. Overall, the study shows that affective polarization undermines the cognitive foundations of spatial voting not through ignorance or ambiguity alone, but through affect-driven motivated reasoning that distorts how voters perceive both allies and opponents.