Effect of Social Skills on the Asymmetry in Facial Expressions


This study investigated the effect of social skills on the facial movement asymmetry in facial expressions. Three-dimensional facial landmark data of facial expressions (neutral, happy, and angry) were obtained from Japanese participants (n = 62). After the facial expression task, each participant completed KiSS-18 (Kikuchi’s Scale of Social Skills; Kikuchi, 2007). Through a generalized Procrustes method, facial landmark coordinates and their mirror-reversed versions were represented as points on a hyperplane. The asymmetry of each face was defined as Euclidian distance on the plane. Subtraction of the asymmetry level of a neutral face of each individual from the asymmetry level of a target emotion face was defined as the index of “movement asymmetry” of each emotion. Correlation coefficients of Kiss-18 scores and movement asymmetry scores were computed for both happy and angry expressions. Significant negative correlations between Kiss-18 scores and movement asymmetries were found for both expressions. The results indicate that symmetric facial expressions are higher with higher level of social skills.

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