In-group Favoritism or Out-group Derogation in Interethnic Marriage Choices: Evidence from Conjoint Analysis in Japan

Intermarriage serves as a key indicator of social integration and group acceptance. While structural factors and third-party influences have been extensively studied, individual partner preferences remain underexplored. This study leverages social identity theory to refine our understanding of partner choice in interethnic marriage. Employing conjoint analysis with data from a 2023 Japanese online survey, I explore how nationality influences partner selection, integrating the concepts of in-group favoritism and out-group derogation into the study of intermarriage. The findings reveal a clear preference for co-national Japanese partners, reflecting pronounced in-group favoritism and weak out-group derogation. I further identify a hierarchy of preference among immigrant candidates, with Western nationalities such as the US and France rated most favorably, while countries like China, Pakistan, and Nigeria are less preferred. This study highlights the necessity of directly measuring partner preferences to uncover the nuances of inter-group bias rather than relying solely on demographic data. By providing a nuanced view of how inter-group bias shapes preference patterns in intermarriage, I contribute to a more comprehensive understanding of partner choice in less heterogeneous societies such as Japan.