A cognitive model of hallucinations.

Hallucinations occur in a wide variety of altered states of consciousnes and are an important symptom in various psychiatric syndromes. Several psychological and biological theories of their origin have offered, ranging from the concept of wish fulfillment, to the hypothesis of an electorchemical release of the perceptual system, to denials that hallucinatory phenomena exist. No explanation has completely satisfied clinicans, probably because the word "hallucination" labels a complex set of phenomena. The author accepts this complexity and offers a conceptual analysis of four key dimensions of the halucinatory experience in an attempt to clarify the gamut of experiences that may be called hallucinations.