Uncertainty avoidance differentiates trait impressions

Forming first impressions from faces involves inherent uncertainty, as perceivers must make rapid personality judgments from limited information. Individuals and cultures differ in how they handle this uncertainty, with some showing greater aversion to ambiguity. We propose that higher uncertainty avoidance leads to more differentiated personality trait impressions, as a cognitive strategy for managing social ambiguity. Across three studies, we demonstrate converging evidence that uncertainty avoidance systematically shapes impression formation. Study 1 (N = 10,552) analyzed face-based trait ratings from 40 regions, revealing that individuals from cultures high in uncertainty avoidance exhibit greater differentiation between trait impressions. Study 2 (N = 105) examined individual differences and found that personal uncertainty avoidance predicts impression differentiation. This relationship was mediated by how distinctly people conceptualize personality traits. Study 3 (N = 212, preregistered) experimentally manipulated uncertainty avoidance, establishing a causal effect: participants formed more differentiated impressions from faces with an uncertainty-avoidant mindset. These findings reveal how uncertainty avoidance systematically shapes person perception across cultural and individual contexts. This work provides new insights into the mechanistic understanding of person perception and challenges the assumption of universality in face-based impressions. It demonstrates how domain-general cognitive diversity creates rich variation in social perception.