They All Look the Same to Me: A Perceptual Basis of Outgroup Homogeneity

Abstract

The outgroup homogeneity effect—the phenomenon that people describe outgroup members as more similar to each other than ingroup members—has often been described using “high‐level” social psychological theories. In a contrasting approach, researchers in neuroscience and behavioral psychology have studied the differences in “learning curves” for appetitive versus aversive stimuli, showing that animals (including humans) overgeneralize stimuli that are associated with an aversive outcome. While these fields have previously been treated as distinct, we believe that outgroup homogeneity may be partially explained by the “low-level” overgeneralization principle. This experiment was designed to tie these two fields directly. Specifically, the experiment utilizes a “kind” group and an “unkind” group of people, with expectations that participants will have a more difficult time differentiating between faces in the unkind group. Because the experiment utilizes different difficulty levels (0.2, 0.4, 0.6, 0.8), we believe that this effect should be more noticeable for the most difficult trials (0.2). The data ambiguously support this hypothesis; that is, the current methodology and data analysis methods we used did not support the hypothesis. However, future research may provide clearer support.