A self-disorder, also called ipseity disturbance, is a psychological phenomenon of disruption or diminishing of a person's minimal self – the fundamental sense that one's experiences are truly one's own. People with self-disorder feel that their internal experiences are actually external; for example, they may experience their own thoughts as coming from outside themselves, whether in the form of true auditory hallucinations or merely as a vague sense that their thoughts do not belong to them. There is evidence that self-disorder is characteristic of schizophrenia spectrum disorders such as schizophrenia itself as well as schizotypal personality disorder. This is the true across both psychotic and non-psychotic disorders. The presence or absence of self-disorders has been used to distinguish schizophrenia spectrum disorders from other psychotic disorders, bipolar disorder, borderline personality disorder, and autism spectrum disorder. Detecting self-disorders may also be useful for early intervention in psychosis, since they occur in the prodrome of schizophrenia prior to the emergence of psychotic symptoms. The concept resembles the basic symptoms of schizophrenia, but the term itself was introduced in the early 2000s together with the Examination of Anomalous Self-Experience (EASE) scale, which is used to measure the presence and severity of self-disorder. The concept is associated with the theoretical approach to psychology known as phenomenology. The minimal (or basic) self has been likened to a "flame that enlightens its surroundings and thereby itself." The sense of minimal self refers to the very basic sense of having experiences that are one's own; it has no properties, unlike the extended self, which is composed of properties such as the person's identity, the person's narrative, their likes and dislikes, and other aspects that are the result of reflection on one's self. The minimal self, however, refers to the "mine-ness" or "given-ness" of experience, that the experiences are that of the person having them in that person's stream of consciousness.
Dimitri Nestor Alice Van De Ville, Farnaz Delavari