Trait judgments of medieval Japanese illustrated portraits

Psychological studies have revealed that people can easily draw inferences regarding others' personal traits from their faces, which has a considerable impact on social decisions. Impressions from faces can be summarized into two orthogonal dimensions: valence and dominance. Owing to their prominence in social relationships, faces appear in paintings across all ages and cultures. These observations lead to the question of whether the structure of trait impressions from illustrated portraits is similar to that of real faces. To examine this issue, we collected trait ratings of illustrated portraits of historical individuals from old Japanese artwork. In the Study 1 section, we applied a principal component analysis to 13 traits by Japanese raters and observed two orthogonal dimensions consistent with the valence and dominance model; the first component was correlated with trustworthiness but not with dominance, while the second component was correlated with dominance but not with trustworthiness. In the Study 2 section, we collected the trait ratings of real faces by Japanese raters and directly assessed the similarity between the two components. Highly similar structures were observed for the illustrated and real faces. Our findings provide evidence that portraits of historical individuals were painted to convey distinctive impressions of trustworthiness and dominance. This suggests that these traits were fundamental dimensions of people's perception in medieval Japan similar to today's society.