With origins in psychology research, the study of sensory processing sensitivity (SPS) is aimed at better understanding the estimated 20% of individuals classified as Highly Sensitive Persons (HSPs) according to the HSP Scale, a 27-item questionnaire developed by Elaine and Arthur Aron in the 1990s. SPS is hypothesized to be an innate, cross-species variation in temperament associated with increased responsivity to environmental stimuli. This includes, in humans, (1) strong emotional reactions, (2) deep processing of sensory information, (3) high awareness of environmental subtleties, and (4) susceptibility to overstimulation. Although SPS is thought to have an inherited, biological basis, no such basis has yet been identified. Limited findings published to date suggest that heritable variations in the serotonergic and dopaminergic systems, and exposure to stressful life events, may each contribute to an ‘HSP’ phenotype. Today, the researchers whose psychology studies gave rise to the SPS construct 25 years ago have been joined by colleagues across disciplines in calling for clarification of the ways that SPS relates to other concepts in psychology research, the biological basis of SPS, and how these insights might be applied to the development of targeted interventions. This narrative review covers research on the genetic and neurological bases of SPS proposed since the 1990s, while offering a concise introduction to the interdisciplinary origins of a concept that has sparked broad popular interest in recent years, and limited but growing interest within the scientific community.
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