The concept of disordered selfhood in schizophrenia reemerged around the year 2000. In 2005, the Examination of Anomalous Self-Experience (EASE) was published as a psychometric tool. This article traces the historical background of the EASE, explains the idea of a disorder of the basic or minimal self using phenomenological philosophy, and describes the clinical signs the EASE targets. The authors share their own experience using and teaching the EASE and review the empirical evidence gathered so far. They argue that basic self-disorder is a key phenotype of schizophrenia spectrum disorders, offering a path for empirical research into causes and for psychotherapeutic treatment.
Basic self-disturbance (BSD), marked by anomalous self-experiences (ASEs), is considered central to schizophrenia spectrum disorders, including prodromal states and schizotypy, but also occurs in depersonalization disorder (DPD). Comparing two cases—one with schizotypal personality disorder (SPD) and one with DPD—revealed that both exhibited ASEs reflecting BSD dimensions and depersonalization aspects. However, only the SPD case linked ASEs to psychotic-like ideas of external influence. The SPD case had insidious early childhood onset without triggers, while the DPD case had abrupt adolescent onset triggered by cannabis use and panic. An updated model suggests schizophrenia involves early "primary" ASEs from neurodevelopmental disturbances plus later "secondary" defensive ASEs, whereas DPD may involve only secondary ASEs, offering better protection against psychosis.