Mere labeling of groups induces perceived intergroup differences even for neutral stimuli

Evidence

One famous piece of evidence for the biasing impact of categorization on perception comes from a study by Tajfel and Wilkes (1963). Like Allport, Tajfel and Wilkes conceived categorization (and stereotyping) to result in the overestimation of intergroup differences and intragroup resemblances. Participants estimated the length of a series of lines that varied from each other by regular increments. When shorter lines (As) were systematically given a different label than longer lines (Bs), participants overestimated the differences between the categories. This basic categorization effect applies to estimates about attitudes, traits, or even physical values (e.g., Krueger & Clement, 1994) and points to the biasing influence of categorization. However, it seems most pronounced when the judgment is uncertain, such as when participants communicate their estimates in an unfamiliar measurement unit (Corneille, Klein, Lambert, & Judd, 2002). — , Rudman, Laurie A - On the Nature of…, 1155

Categorization

• XREF: The Tajfel-Wilkes line study is direct empirical bedrock confirming the vault’s categorization-bias claims and the rationale for contact-theory interventions.
• SHARE: The finding that category-labeling bias is strongest under measurement uncertainty could be sent to anyone doing survey design or behavioral research.
• QUESTION: The unfamiliar-measurement-unit moderator (Corneille et al. 2002) suggests ambiguity amplifies categorization — worth chasing whether this also modulates intergroup contact effects.