Sensory Processing Sensitivity ( SPS, a personality trait, a high measure of which defines a Highly Sensitive Person or HSP), has been described as having hypersensitivity to external stimuli, a greater depth of cognitive processing, and high emotional reactivity The terms SPS and HSP were coined in the mid-1990s by psychologists Elaine Aron and husband Arthur Aron, with SPS being measured by Aron's Highly Sensitive Person Scale (HSPS) questionnaire.