Définir ou détecter des pathologies ? Utilisation et interprétation des scores seuils à la lumière du débat dimensions/catégories

Abstract

A number of psychometric tests are aimed at locating the performance of an individual along a continuous range that goes from normal to worrying. In a different paradigm, there are tests whose goal is to assess whether or not an individual is healthy with respect to a psychological, psychiatric or neurological pathology that is defined independently from the test itself. The former rely on a dimensional concept of psychopathologies; the latter imply a categorical concept. The former require to compare the performance of the individual to a standard sample that is representative of the general population; the latter involve a standard sample representative of the healthy population only. The former might imply the use of a cut-off score to indicate that a certain degree of rarity of the performance has been reached, while the latter must involve a cut-off score to make a decision (whether the individual belongs to the “healthy” or “pathological” category), a score that is most often set so as to control the false-positive rate in making this decision. In the former paradigm, the cut-off score defines or contributes to define the pathology. In the latter, it only helps detecting it. This article aims at making clear the difference between these two realms and highlight their practical as well as theoretical impact on psychological practice.