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Classification according to ICD-10
R44 Other symptoms that affect sensory perception and perception
R44.0 Acoustic hallucinations
R44.1 Optical hallucinations
R44.2 Other hallucinations
R44.3 Hallucinations, unspecified
R44.8 Other and unspecified symptoms that affect sensory perception and perception
ICD-10 online (WHO version 2019)

Under hallucination (from latin alucinatio , dreaming ' ) refers to a perception without a detectable external stimulus base is present. Such perceptions can occur in any sense area. This means, for example, that physically undetectable objects are seen or voices are heard without someone speaking.

In the case of an illusion, on the other hand, a reality that is actually present is perceived as being changed: a stationary object that is actually present appears to be moving or faces appear to be recognizable in irregular patterns.


A hallucination has, by definition, a reality character for the hallucinating person or cannot be distinguished from reality.In contrast, with a pseudo-hallucination , the person realizes that it is not a real perception.

The delusional perception must be distinguished from the hallucination . In doing so, a real perception, i.e. one that can also be understood by others, is assigned a delusional meaning. An example of this would be someone who firmly believes that the accidental ringing of a church bell is a signal to his pursuers to seize him now.

Hallucinations can be caused by:

Causes of pseudohallucinations can be:

Types of hallucinations

In visual hallucinations it comes to the perception of non-existent objects. The most common are small and moving objects, the perception of which is then usually experienced with great fear. This occurs, for example, in the context of delirium. Sometimes entire scenes are experienced. Dual system experience describes a double perception in extreme opposites, such as light and dark.

In acoustic hallucinations , which are common in people suffering from schizophrenia , for example , those affected often hear voices that abuse the person, comment on what they are doing and / or give commands (imperative voices).

Olfactory (concerning the smell: phantosmia ) and gustatory hallucinations (concerning the taste) are often diagnosed in patients with delusional fear of intoxication, for example in the context of a schizophrenic psychosis.

Coenesthesia are hallucinations from the area of ​​body perception (body hallucinations). In a narrower sense they do not have the character of something made from outside, but in a broader sense they do.

Under hypnagogic hallucinations refers to optical and acoustic hallucinations half asleep fall asleep. They also occur in mentally healthy people, as hallucinations in general are to be regarded as normal in situations such as meditations . In the field of hypnosis , negative hallucinations are used when an external stimulus is no longer seen, heard or felt in a trance . “Negative” describes the fact that something is no longer perceived in a value-neutral manner.

Hallucinogens, despite their name, usually produce pseudo-hallucinations (see also model psychosis ) or illusions than real hallucinations.

Hallucinations in epilepsy

Hallucinations may occur in association with epilepsy . Depending on the type of hallucination and the experience of the hallucinator, it will be recognized as such or not. Hallucinations of music or voices, for example, can be recognized as such with a little experience based on the purity of the sound or the absence of interfering noises. Musical hallucinosis is a special form .

Hallucinations of this kind are usually particularly incisive memories of perceptions that were previously based on stimuli. These memories can also consist of stimuli to which one is frequently exposed every day. One hears z. E.g. your child strides through the hallway, although it is already fast asleep in its bed, or you can hear your cat eating or sharpening its claws, which is also sleeping. Such hallucinations can also occur in completely different environments where they should not reasonably occur, such as in the workplace. The brain supplements part of reality when certain key stimuli are present that usually occur together with the missing stimulus.

In addition to hallucinations that are based on memories, there are hallucinations of actions or processes that can result from a short-term failure of the stimulus base. These hallucinations extrapolate reality after failure of the stimulus base by “calculating” reality for a few seconds without stimulus base in its presumed course. They disappear as soon as the stimulus base is restored. In this way, the hallucinations help the person concerned to continue an activity they are currently performing - for example, walking on a sidewalk - without interruption. The fact that a hallucination was present can generally only be determined negatively afterwards - for example, if in the meantime an obstacle appeared on the sidewalk that was not perceived or perceived before the failure of the stimulus basis, but was interpreted as a disturbance variable and "calculated out" from the extrapolation of reality.

See also


Web links

Wiktionary: Hallucination  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ Jan Dirk Blom: A Dictionary of Hallucinations. Springer Science & Business Media, New York 2009, ISBN 9781441912237 , p. 161.
  2. Gerhard Schütz , Horst Freilang : Hypnolinguistics: Understanding and using the language of hypnosis. Junfermann Verlag, Paderborn 2013, ISBN 9783873879461 .
  3. Birk Engmann, Mike Reuter: Melody perception without external stimulus. Hallucination or epilepsy? A case report. In: Neurology. Vol. 28, No. 4, 2009, ISSN  0722-1541 , pp. 217-221, doi : 10.1055 / s-0038-1628605 .