Detecting Voter Understanding of Ideological Labels Using a Conjoint Experiment

Understanding voters’ conception of ideological labels is critical for political behavioral research. Conventional research designs have several limitations, such as endogeneity, insufficient responses to open-ended questions, and inseparability of composite treatment effects. To address these challenges, we propose a conjoint experiment to study the meanings ascribed to ideological labels in terms of policy positions. We also suggest using a mixture model approach to explore heterogeneity in voters’ understandings of ideological labels, as well as the average interpretation of labels. We applied these approaches to conceptions of left–right labels in Japan, where the primary issue of elite-level conflicts has been distinctive compared with other developed countries. We found that, on average, while Japanese voters understand policy-related meanings of “left” and “right,” they primarily associate these labels with security and nationalism, and, secondarily, with social issues; they do not associate these labels with economic issues. Voters’ understandings partly depend on their birth cohort, but observed patterns do not necessarily coincide with what many researchers would predict regarding generational differences in Japanese politics. Mixture model results suggest that some individuals tend to associate left–right labels with security and nationalism policies, while others link them to social policies. Over one-third of respondents seemed to barely understand the usage of left–right labels in policy positions. Our study improves upon existing methods for measuring voter understanding of ideological labels, and reconfirm the global diversity of meanings associated with left–right labels.