Pseudohallucination

A pseudohallucination (from Ancient Greek: ψευδής (pseudḗs) "false, lying" + "hallucination") is an involuntary sensory experience vivid enough to be regarded as a hallucination, but considered by the person as subjective and unreal, unlike "true" hallucinations, which are considered real by patients with psychological disorders.[1] Unlike normal hallucinations, 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.

The term "pseudohallucination" appears to have been coined by Friedrich Wilhelm Hagen.[2] Hagen published his 1868 book "Zur Theorie der Halluzination," to define them as "illusions or sensory errors".[2]

The term "pseudohallucination" was then further explored by the Russian psychiatrist Victor Kandinsky (1849–1889).[2] In his work "On Pseudohallucinations" (Russian: "О псевдогаллюцинациях" [o psevdogalliutsinatsiakh]), he described his psychotic experience defining pseudohallucinations as "subjective perceptions similar to hallucinations, with respect to its character and vividness, but that differ from those because these do not have objective reality".[3][2]

The term is not widely used in the psychiatric and medical fields, as it is considered ambiguous;[4] the term nonpsychotic hallucination is preferred.[5] Pseudohallucinations, then, are more likely to happen with a hallucinogenic drug. But "the current understanding of pseudohallucinations is mostly based on the work of Karl Jaspers".[6]

A further distinction is sometimes made between pseudohallucinations and parahallucinations, the latter being a result of damage to the peripheral nervous system.[7]

They are considered a possible symptom of conversion disorder in DSM-IV (2000).[8] In DSM-5 (2013), this definition has been removed.[2] Also, pseudohallucinations can occur in people with visual/hearing loss, with the typical such type being Charles Bonnet syndrome.