Children vary in environmental sensitivity, reflecting heightened responsiveness to positive and negative environments. It is commonly measured through the temperament trait of Sensory Processing Sensitivity (SPS). Currently, no instruments exist in the German language to assess SPS in children. The present study translated the 21-item Highly Sensitive Child Scale (HSC-21) into German and evaluated its psychometric properties using caregiver reports (n = 367) and child self-reports (n = 112). Confirmatory factor analyses supported a bifactor model with a general sensitivity factor and three specific subdimensions (i.e., Ease of Excitation, Low Sensory Threshold, Aesthetic Sensitivity). The German HSC-21 demonstrated full configural, metric and scalar measurement invariance across sex and age groups and good to excellent reliability (internal consistency, test-retest reliability, interrater agreement). HSC-21 scores moderately predicted internalizing problems but not externalizing problems. Consistent with environmental sensitivity theory, Ease of Excitation and Low Sensory Threshold were linked to internalizing problems, whereas Aesthetic Sensitivity predicted better school performance, fewer peer problems, and greater prosocial behavior. The HSC-21 demonstrated meaningful correlations with temperament and personality traits, including positive associations with neuroticism, behavioral inhibition, and sensory sensitivity, and negative associations with extraversion and activity level. Thus, the German HSC-21 represents a reliable and valid measure of SPS and environmental sensitivity.

Building on Ellis et al.’s theorization for potent dimensions of environmental adversity, the present work sought to evaluate how environmental harshness and unpredictability might function directly and in interaction with child sensory processing sensitivity (SPS) to shape the development of child socioemotional functioning. Participants were 235 young children (Mage = 2.97 at the first measurement occasion) and their parents, who were followed for two consecutive annual measurement occasions. Child SPS was measured through behavioral observation across multiple tasks within the laboratory setting. Greater environmental unpredictability was significantly associated with the development of children’s externalizing problems over a year only for children with high SPS. Follow-up analyses indicated that the unpredictability-x-SPS interaction was consistent with differential susceptibility, such that high SPS children showed greater increases in externalizing problems under high unpredictability, but also lower increases/greater decreases in externalizing problems under low unpredictability. Such association did not apply to children with low SPS.