Effortful Bias Regulation in Social Evaluations: A Drift Diffusion Approach to Race–Gender Judgements

How do race and gender jointly shape rapid competence judgments, and what cognitive mechanisms govern the regulation of social bias expression? Across two studies (total N = 298), we examined competence evaluations from faces for White men, White women, Black men, and Black women, integrating individual-difference measures of cognitive control and motivation to be unprejudiced. Replicating prior work, participants evaluated White women and Black men more positively than White men, but this counter-stereotypical advantage did not extend to Black women. Drift Diffusion Modeling (DDM) revealed that this intersectional disadvantage arose exclusively from drift-rate differences, indicating that group effects reflected biased evidence accumulation rather than pre-decisional bias, response caution, or non-decision processes. Internal and external motivations exerted dissociable effects: internal motivation enhanced the efficiency with which participants accumulated competence-supporting evidence for Black targets, reducing the penalty for Black women; in contrast, external motivation decreased drift, producing a backfire effect that amplified negative evaluations. Measures of domain-general cognitive-control (Stroop) and time-on-task provided mixed evidence, suggesting that regulation in this task is driven primarily by motivational rather than domain-general cognitive factors. By linking intersectional bias to specific decision parameters, this work clarifies how motivation reshapes the computational dynamics of first impressions and highlights the unique psychological representation of intersectional targets, underscoring the difficulty of regulating biases toward multiply marginalized individuals.