Evaluation of the affective values of neutral faces in the context of expression attenuation

This study aimed to quantify the affective values of neutral faces in the context of attenuation of the six basic facial expressions (i.e., anger, disgust, sadness, happiness, fear, and surprise) via the affect grid method and verify whether overshoot perceptual bias was visible. In Experiment 1, still images of faces displaying six facial expressions and of an expressionless neutral face were evaluated on a two-dimensional affect grid scale consisting of hedonic valence (i.e., pleasure-displeasure) and arousal (i.e., high arousal-low arousal), and their affective values were confirmed. In Experiment 2, the final neutral faces shown at the end of the moving images - in which one of six expressions gradually disappeared - were evaluated using the same methods as those described for Experiment 1. As a result, the evaluation of a neutral face with expression attenuation differed from evaluations without context in many cases and shifted depending on the initial context expression on any one of or both the hedonic valence and arousal dimension. Given the affective values of context expression confirmed in Experiment 1, this shift can be considered a forward shift in line with the expression attenuation context in the specific dimension defining emotion.