Quantifying Environmental Sensitivity Using Morphing Facial Expression Videos

Abstract

This study focuses on the environmental sensitivity of individuals, which measures the perception and processing of both positive and negative environments and stimuli. Individuals with high sensory processing sensitivity, a component of environmental sensitivity, are more prone to depression and stress. Although genetic testing and psychological indices measure environmental sensitivity, this study focused on behavioral indices. Previous studies have suggested that brain regions related to vision and attention are activated in people with high scores on the Highly Sensitive Person Scale (HSPS), and that they are more sensitive to subtle changes in facial expressions of happiness and sadness. Therefore, we measured facial reaction time to stimuli that changed expressions from neutral to happy or sad, and the percentage of gaze fixation in the face region. We compared these results with the HSPS, HSPS-J19, and the Japanese version of the Interpersonal Reactivity Index (IRI-J). Results showed a negative correlation between HSPS-J19 scores and responses to happiness (happiness: r = −0.24) and sadness (sadness: r = −0.25). A negative correlation was also found between HSPS scores, HSPS-J19 scores, and the percentage of nasal fixation in sadness (HSPS: r = −0.24), (HSPS-J19: r = −0.24). A negative correlation was also found between the HSPS scores and the percentage of left eye fixation in sadness (r = −0.30). Thus, people with higher environmental sensitivity may be more sensitive because they respond more quickly to happiness and sadness and see their nose and left eye less often in sadness.