Last reviewed 01/2018
A hallucination is a false perception i.e. without an external stimulus. It has all the qualities of real perception and may occur in any modality.
Hallucinations may be elementary i.e. of simple phenomena like noises, bangs and flashing lights. They may also be complex i.e. the hearing of voices or the seeing of faces or scenes.
Hallucinations are a common occurrence in schizophrenic patients. In schizophrenia a patient may hear voices that tell them to do things or comment on their actions. A finding from the history of some schizophrenic patients is the occurence of the patient 'hearing their own thoughts aloud'.
olfactory and gustatory hallucinations