A pseudohallucination is an involuntary sensory experience vivid enough to be regarded as a hallucination, but recognised by the patient not to be the result of external stimuli. In other words, it is a hallucination that is recognized as a hallucination, as opposed to a "normal" hallucination which would be perceived as real. An example used in psychiatry is the hearing of voices which are inside the head according to the patient; in contrast, a hallucination would be indistinguishable to the patient from a real external stimulus, e.g. people were talking about me.
The term is not widely used in the psychiatric and medical fields, as it is considered ambiguous.[1] The term "nonpsychotic hallucination" is more preferred.[2] Pseudohallucinations, then, are more likely to happen with a hallucinogenic drug. Thus, when one speaks of hallucinating when under the influence of such a drug (excluding deliriants), they are probably referring to pseudohallucinations.
They are considered a feature of conversion disorder, somatization disorder, and dissociative disorders.[3]