All the Same?

Outgroup homogeneity, a well-known concept in psychology, refers to the tendency to perceive members of other social groups as more similar to one another and as representatives of their group, rather than unique individuals. This phenomenon has relevance to modern political science, particularly in the context of affective polarization, which, characterized by strong emotional divides between political groups, is rooted in group identity and stereotype formation. Therefore unsurprisingly, the perception of outgroup homogeneity is linked to negative feelings toward opposing groups. However, also populist rhetoric, with its oversimplified categorizations of “the elites”, "politicians" or "the media" serves as another example of this dynamic. This paper investigates whether rising negative sentiment toward political parties and groups correlates with growing perceptions of outgroup homogeneity. A key factor explored is the differentiation of parties during electoral campaigns. The increasing professionalization of political campaigning has led to a shift toward highly personified advertising. This study employs text and image classification to examine whether the presence of substantive political information in campaign materials has diminished over time. Through experimental design and analysis of historical panel data, I aim to determine whether richer campaign information reduces homogeneity perception by highlighting party differences. The findings may suggest that short-term electoral gains achieved through personified, low-information campaigning could have long-term drawbacks, increasing outgroup homogeneity perception and affective polarization. Enhancing substantial differentiation between parties could strengthen the electorate’s belief in democracy and shift political opposition from blanket rejection of entire groups to issue-based disagreement with specific parties.