What is "pseudohallucination"

n. A brief but vivid visual or auditory experience that is recognised as being unreal

n. an image vivid enough to be a hallucination but recognized as unreal

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. Unlike normal hallucination, which occurs when one sees, hears, smells, tastes or feels something that is not there, with a compelling feeling or thought that it is real, pseudohallucinations are recognised by the person as unreal.

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; the term nonpsychotic hallucination is preferred. Pseudohallucinations, then, are more likely to happen with a hallucinogenic drug.

A further distinction is sometimes made between pseudohallucinations and parahallucinations, the latter being a result of damage to the peripheral nervous system.

They are considered a feature of conversion disorder, somatization disorder, and dissociative disorders. Also, pseudohallucinations can occur in people with visual/hearing loss, with the typical such type being Charles Bonnet syndrome.