Psychometric Properties of the Highly Sensitive Child Scale and Its Role in Socio-Emotional and Behavioral Development: Evidence from Japanese Adolescent Samples

)-the capacity to perceive and process both supportive and adverse environmental experiences-may influence adolescent development, yet evidence in adolescence is scarce compared with that in childhood. We analyzed adolescent self-reports and maternal ratings from 2,375 Japanese adolescents across three studies. In Studies 1-2, the 21-item Highly Sensitive Child scale showed a bifactor structure (general sensitivity plus Ease of Excitation-Low Sensory Threshold and Aesthetic Sensitivity), with good internal consistency and moderate test-retest reliability; trait sensitivity correlated positively with negative emotionality, behavioral inhibition, neuroticism, and openness. The general sensitivity factor accounted for approximately half of the variance in the total score. In Study 3 adolescents were followed across three waves, testing interactions between trait sensitivity and environmental factors (i.e., parent and peer relationships). No significant interactions were detected; rather, trait sensitivity and environmental factors showed additive associations with developmental outcomes. Trait sensitivity predicted higher internalizing problems and greater prosocial behavior. In summary, the psychometric properties of the HSC-J21 were consistent with those of the original version developed by Weyn et al.