What exists in the research
The best-supported notion is sensory processing sensitivity: variation, present across the whole population, in the threshold at which a stimulus is perceived and the depth at which it is processed.
It is measurable by questionnaire, correlated with certain traits — notably neuroticism and openness — and associated with observable differences in brain activity. It is continuous: there are not two kinds of people.
What it is not
It is not a diagnosis. It is not a recognised clinical category, and no online test can establish it.
Nor is it autism, an anxiety disorder, or a sensory integration disorder — three distinct things that share some manifestations. The confusion is frequent and problematic: it leads people to explain by temperament what would warrant assessment.
High sensitivity is neither a superiority nor a disability. It is a difference in threshold, costly in some environments and useful in others. Accounts that make it a gift are as unfounded as those that make it a frailty.
What it changes in practice
The choice of a home, tolerance of an open-plan office, the kind of holiday that rests rather than drains, the type of therapist with whom work becomes possible. These are ordinary decisions, and that is where the information is useful.
Measuring it differently
Questionnaires meet a particular obstacle here: people describe their own thresholds badly, for want of comparison. Someone who has always perceived noise this way has no idea what others perceive.
RÉSONANCE records several registers — relationship to light, tolerance for noise, search for silence, relationship to material — without asking, from movement alone. our piece on personality tests explains why self-report is structurally limited.
This page is informational and is not medical advice or a diagnosis.