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Hallucination
Hallucination
	My eyes at the moment of the apparitions by August Natterer, a German artist who created many drawings of his hallucinations
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A hallucination is a perception in the absence of an external stimulus that has the qualities of a real perception. Hallucinations are vivid, substantial, and are perceived to be located in external objective space. They are distinguishable from several related phenomena, such as dreaming, which does not involve wakefulness; pseudohallucination, which does not mimic real perception, and is accurately perceived as unreal; illusion, which involves distorted or misinterpreted real perception; and imagery (imagination), which does not mimic real perception, and is under voluntary control.^[1] Hallucinations also differ from "delusional perceptions", in which a correctly sensed and interpreted stimulus (i.e., a real perception) is given some additional significance. Many hallucinations happen also during sleep paralyses.^[2]

Hallucinations can occur in any sensory modality—visual, auditory, olfactory, gustatory, tactile, proprioceptive, equilibrioceptive, nociceptive, thermoceptive and chronoceptive. Hallucinations are referred to as multimodal if multiple sensory modalities occur.^[3]^[4]

A mild form of hallucination is known as a disturbance, and can occur in most of the senses above. These may be things like seeing movement in peripheral vision, or hearing faint noises or voices. Auditory hallucinations are very common in schizophrenia. They may be benevolent (telling the subject good things about themselves) or malicious, cursing the subject. 55% of auditory hallucinations are malicious in content,^[5] for example, people talking about the subject, not speaking to them directly. Like auditory hallucinations, the source of the visual counterpart can also be behind the subject. This can produce a feeling of being looked or stared at, usually with malicious intent.^{[citation needed]} Frequently, auditory hallucinations and their visual counterpart are experienced by the subject together.^[6]

Hypnagogic hallucinations and hypnopompic hallucinations are considered normal phenomena. Hypnagogic hallucinations can occur as one is falling asleep and hypnopompic hallucinations occur when one is waking up. Hallucinations can be associated with drug use (particularly deliriants), sleep deprivation, psychosis, neurological disorders, and delirium tremens.

The word "hallucination" itself was introduced into the English language by the 17th-century physician Sir Thomas Browne in 1646 from the derivation of the Latin word alucinari meaning to wander in the mind. For Browne, hallucination means a sort of vision that is "depraved and receive[s] its objects erroneously".^[7]

Classification

Hallucinations may be manifested in a variety of forms.^[8] Various forms of hallucinations affect different senses, sometimes occurring simultaneously, creating multiple sensory hallucinations for those experiencing them.

Auditory

Auditory hallucinations (also known as paracusia)^[9] are the perception of sound without outside stimulus. Auditory hallucinations can be divided into elementary and complex, along with verbal and nonverbal. These hallucinations are the most common type of hallucination, with auditory verbal hallucinations being more common than nonverbal.^[10] Elementary hallucinations are the perception of sounds such as hissing, whistling, an extended tone, and more. In many cases, tinnitus is an elementary auditory hallucination. However, some people who experience certain types of tinnitus, especially pulsatile tinnitus, are actually hearing the blood rushing through vessels near the ear. Because the auditory stimulus is present in this situation, it does not qualify it as a hallucination.

Complex hallucinations are those of voices, music, or other sounds that may or may not be clear, may or may not be familiar, and may be friendly, aggressive, or among other possibilities. A hallucination of a single individual person of one or more talking voices is particularly associated with psychotic disorders such as schizophrenia, and hold special significance in diagnosing these conditions.

Another typical disorder where auditory hallucinations are very common is dissociative identity disorder. In schizophrenia voices are normally perceived coming from outside the person but in dissociative disorders they are perceived as originating from within the person, commenting in their head instead of behind their back. Differential diagnosis between schizophrenia and dissociative disorders is challenging due to many overlapping symptoms, especially Schneiderian first rank symptoms such as hallucinations.^[11] However, many people not suffering from diagnosable mental illness may sometimes hear voices as well.^[12] One important example to consider when forming a differential diagnosis for a patient with paracusia is lateral temporal lobe epilepsy. Despite the tendency to associate hearing voices, or otherwise hallucinating, and psychosis with schizophrenia or other psychiatric illnesses, it is crucial to take into consideration that, even if a person does exhibit psychotic features, they do not necessarily suffer from a psychiatric disorder on its own. Disorders such as Wilson's disease, various endocrine diseases, numerous metabolic disturbances, multiple sclerosis, systemic lupus erythematosus, porphyria, sarcoidosis, and many others can present with psychosis.

Musical hallucinations are also relatively common in terms of complex auditory hallucinations and may be the result of a wide range of causes ranging from hearing-loss (such as in musical ear syndrome, the auditory version of Charles Bonnet syndrome), lateral temporal lobe epilepsy,^[13] arteriovenous malformation,^[14] stroke, lesion, abscess, or tumor.^[15]

The Hearing Voices Movement is a support and advocacy group for people who hallucinate voices, but do not otherwise show signs of mental illness or impairment.

High caffeine consumption has been linked to an increase in likelihood of one experiencing auditory hallucinations. A study conducted by the La Trobe University School of Psychological Sciences revealed that as few as five cups of coffee a day (approximately 500 mg of caffeine) could trigger the phenomenon.^[16]

Visual

A visual hallucination is "the perception of an external visual stimulus where none exists".^[17] A separate but related phenomenon is a visual illusion, which is a distortion of a real external stimulus. Visual hallucinations are classified as simple or complex:

Simple visual hallucinations (SVH) are also referred to as non-formed visual hallucinations and elementary visual hallucinations. These terms refer to lights, colors, geometric shapes, and indiscrete objects. These can be further subdivided into phosphenes which are SVH without structure, and photopsias which are SVH with geometric structures.
Complex visual hallucinations (CVH) are also referred to as formed visual hallucinations. CVHs are clear, lifelike images or scenes such as people, animals, objects, places, etc.

For example, one may report hallucinating a giraffe. A simple visual hallucination is an amorphous figure that may have a similar shape or color to a giraffe (looks like a giraffe), while a complex visual hallucination is a discrete, lifelike image that is, unmistakably, a giraffe.

Command

Command hallucinations are hallucinations in the form of commands; they appear to be from an external source, or can appear coming from the subject's head.^[18] The contents of the hallucinations can range from the innocuous to commands to cause harm to the self or others.^[18] Command hallucinations are often associated with schizophrenia. People experiencing command hallucinations may or may not comply with the hallucinated commands, depending on the circumstances. Compliance is more common for non-violent commands.^[19]

Command hallucinations are sometimes used to defend a crime that has been committed, often homicides.^[20] In essence, it is a voice that one hears and it tells the listener what to do. Sometimes the commands are quite benign directives such as "Stand up" or "Shut the door."^[21] Whether it is a command for something simple or something that is a threat, it is still considered a "command hallucination." Some helpful questions that can assist one in determining if they may be suffering from this includes: "What are the voices telling you to do?", "When did your voices first start telling you to do things?", "Do you recognize the person who is telling you to harm yourself (or others)?", "Do you think you can resist doing what the voices are telling you to do?"^[21]

Olfactory

Phantosmia (olfactory hallucinations), smelling an odor that is not actually there,^[22] and parosmia (olfactory illusions), inhaling a real odor but perceiving it as different scent than remembered,^[23] are distortions to the sense of smell (olfactory system), and in most cases, are not caused by anything serious and will usually go away on their own in time.^[22] It can result from a range of conditions such as nasal infections, nasal polyps, dental problems, migraines, head injuries, seizures, strokes, or brain tumors.^[22]^[24] Environmental exposures can sometimes cause it as well, such as smoking, exposure to certain types of chemicals (e.g., insecticides or solvents), or radiation treatment for head or neck cancer.^[22] It can also be a symptom of certain mental disorders such as depression, bipolar disorder, intoxication, substance withdrawal, or psychotic disorders (e.g., schizophrenia).^[24] The perceived odors are usually unpleasant and commonly described as smelling burned, foul, spoiled, or rotten.^[22]

Tactile

Tactile hallucinations are the illusion of tactile sensory input, simulating various types of pressure to the skin or other organs. One subtype of tactile hallucination, formication, is the sensation of insects crawling underneath the skin and is frequently associated with prolonged cocaine use.^[25] However, formication may also be the result of normal hormonal changes such as menopause, or disorders such as peripheral neuropathy, high fevers, Lyme disease, skin cancer, and more.^[25]

Gustatory

This type of hallucination is the perception of taste without a stimulus. These hallucinations, which are typically strange or unpleasant, are relatively common among individuals who have certain types of focal epilepsy, especially temporal lobe epilepsy. The regions of the brain responsible for gustatory hallucination in this case are the insula and the superior bank of the sylvian fissure.^[26]^[27]

General somatic sensations

General somatic sensations of a hallucinatory nature are experienced when an individual feels that their body is being mutilated, i.e. twisted, torn, or disemboweled. Other reported cases are invasion by animals in the person's internal organs, such as snakes in the stomach or frogs in the rectum. The general feeling that one's flesh is decomposing is also classified under this type of this hallucination.^[27]^{[citation needed]}

Multimodal

A hallucination involving sensory modalities is called multimodal, analogous to unimodal hallucinations which have only one sensory modality. The multiple sensory modalities can occur at the same time (simultaneously) or with a delay (serial), be related or unrelated to each other, and be consistent with reality (congruent) or not (incongruent).^[3]^[4] For example, a person talking in a hallucination would be congruent with reality, but a cat talking would not be.

Multimodal hallucinations are correlated to poorer mental health outcomes, and are often experienced as feeling more real.^[3]

Cause

Hallucinations can be caused by a number of factors.

Hypnagogic hallucination

These hallucinations occur just before falling asleep and affect a high proportion of the population: in one survey 37% of the respondents experienced them twice a week.^[28] The hallucinations can last from seconds to minutes; all the while, the subject usually remains aware of the true nature of the images. These may be associated with narcolepsy. Hypnagogic hallucinations are sometimes associated with brainstem abnormalities, but this is rare.^[29]

Peduncular hallucinosis

Peduncular means pertaining to the peduncle, which is a neural tract running to and from the pons on the brain stem. These hallucinations usually occur in the evenings, but not during drowsiness, as in the case of hypnagogic hallucination. The subject is usually fully conscious and then can interact with the hallucinatory characters for extended periods of time. As in the case of hypnagogic hallucinations, insight into the nature of the images remains intact. The false images can occur in any part of the visual field, and are rarely polymodal.^[29]

Delirium tremens

One of the more enigmatic forms of visual hallucination is the highly variable, possibly polymodal delirium tremens. Individuals suffering from delirium tremens may be agitated and confused, especially in the later stages of this disease. Insight is gradually reduced with the progression of this disorder. Sleep is disturbed and occurs for a shorter period of time, with rapid eye movement sleep.

Parkinson's disease and Lewy body dementia

Parkinson's disease is linked with Lewy body dementia for their similar hallucinatory symptoms. The symptoms strike during the evening in any part of the visual field, and are rarely polymodal. The segue into hallucination may begin with illusions^[30] where sensory perception is greatly distorted, but no novel sensory information is present. These typically last for several minutes, during which time the subject may be either conscious and normal or drowsy/inaccessible. Insight into these hallucinations is usually preserved and REM sleep is usually reduced. Parkinson's disease is usually associated with a degraded substantia nigra pars compacta, but recent evidence suggests that PD affects a number of sites in the brain. Some places of noted degradation include the median raphe nuclei, the noradrenergic parts of the locus coeruleus, and the cholinergic neurons in the parabrachial area and pedunculopontine nuclei of the tegmentum.^[29]

Migraine coma

This type of hallucination is usually experienced during the recovery from a comatose state. The migraine coma can last for up to two days, and a state of depression is sometimes comorbid. The hallucinations occur during states of full consciousness, and insight into the hallucinatory nature of the images is preserved. It has been noted that ataxic lesions accompany the migraine coma.^[29]

Charles Bonnet syndrome

Charles Bonnet syndrome is the name given to visual hallucinations experienced by a partially or severely sight impaired person. The hallucinations can occur at any time and can distress people of any age, as they may not initially be aware that they are hallucinating. They may fear for their own mental health initially, which may delay them sharing with carers until they start to understand it themselves. The hallucinations can frighten and disconcert as to what is real and what is not. The hallucinations can sometimes be dispersed by eye movements, or by reasoned logic such as, "I can see fire but there is no smoke and there is no heat from it" or perhaps, "We have an infestation of rats but they have pink ribbons with a bell tied on their necks." Over elapsed months and years, the hallucinations may become more or less frequent with changes in ability to see. The length of time that the sight impaired person can suffer from these hallucinations varies according to the underlying speed of eye deterioration. A differential diagnosis are ophthalmopathic hallucinations.^[31]

Focal epilepsy

Visual hallucinations due to focal seizures differ depending on the region of the brain where the seizure occurs. For example, visual hallucinations during occipital lobe seizures are typically visions of brightly colored, geometric shapes that may move across the visual field, multiply, or form concentric rings and generally persist from a few seconds to a few minutes. They are usually unilateral and localized to one part of the visual field on the contralateral side of the seizure focus, typically the temporal field. However, unilateral visions moving horizontally across the visual field begin on the contralateral side and move toward the ipsilateral side.^[26]^[32]

Temporal lobe seizures, on the other hand, can produce complex visual hallucinations of people, scenes, animals, and more as well as distortions of visual perception. Complex hallucinations may appear to be real or unreal, may or may not be distorted with respect to size, and may seem disturbing or affable, among other variables. One rare but notable type of hallucination is heautoscopy, a hallucination of a mirror image of one's self. These "other selves" may be perfectly still or performing complex tasks, may be an image of a younger self or the present self, and tend to be briefly present. Complex hallucinations are a relatively uncommon finding in temporal lobe epilepsy patients. Rarely, they may occur during occipital focal seizures or in parietal lobe seizures.^[26]

Distortions in visual perception during a temporal lobe seizure may include size distortion (micropsia or macropsia), distorted perception of movement (where moving objects may appear to be moving very slowly or to be perfectly still), a sense that surfaces such as ceilings and even entire horizons are moving farther away in a fashion similar to the dolly zoom effect, and other illusions.^[33] Even when consciousness is impaired, insight into the hallucination or illusion is typically preserved.

Drug-induced hallucination

Drug-induced hallucinations are caused by hallucinogens, dissociatives, and deliriants, including many drugs with anticholinergic actions and certain stimulants, which are known to cause visual and auditory hallucinations. Some psychedelics such as lysergic acid diethylamide (LSD) and psilocybin can cause hallucinations that range in the spectrum of mild to intense.

Hallucinations, pseudohallucinations, or intensification of pareidolia, particularly auditory, are known side effects of opioids to different degrees—it may be associated with the absolute degree of agonism or antagonism of especially the kappa opioid receptor, sigma receptors, delta opioid receptor and the NMDA receptors or the overall receptor activation profile as synthetic opioids like those of the pentazocine, levorphanol, fentanyl, pethidine, methadone and some other families are more associated with this side effect than natural opioids like morphine and codeine and semi-synthetics like hydromorphone, amongst which there also appears to be a stronger correlation with the relative analgesic strength. Three opioids, Cyclazocine (a benzormorphan opioid/pentazocine relative) and two levorphanol-related morphinan opioids, Cyclorphan and Dextrorphan are classified as hallucinogens, and Dextromethorphan as a dissociative.^[34]^[35]^[36] These drugs also can induce sleep (relating to hypnagogic hallucinations) and especially the pethidines have atropine-like anticholinergic activity, which was possibly also a limiting factor in the use, the psychotomimetic side effects of potentiating morphine, oxycodone, and other opioids with scopolamine (respectively in the Twilight Sleep technique and the combination drug Skophedal, which was eukodal (oxycodone), scopolamine and ephedrine, called the "wonder drug of the 1930s" after its invention in Germany in 1928, but only rarely specially compounded today) (q.q.v.).^[37]

Sensory deprivation hallucination

Hallucinations can be caused by sensory deprivation when it occurs for prolonged periods of time, and almost always occurs in the modality being deprived (visual for blindfolded/darkness, auditory for muffled conditions, etc.) ^[38]

Experimentally-induced hallucinations

Anomalous experiences, such as so-called benign hallucinations, may occur in a person in a state of good mental and physical health, even in the apparent absence of a transient trigger factor such as fatigue, intoxication or sensory deprivation.

The evidence for this statement has been accumulating for more than a century. Studies of benign hallucinatory experiences go back to 1886 and the early work of the Society for Psychical Research,^[39]^[40] which suggested approximately 10% of the population had experienced at least one hallucinatory episode in the course of their life. More recent studies have validated these findings; the precise incidence found varies with the nature of the episode and the criteria of "hallucination" adopted, but the basic finding is now well-supported.^[41]

Non-celiac gluten sensitivity

There is tentative evidence of a relationship with non-celiac gluten sensitivity, the so-called "gluten psychosis".^[42]

Pathophysiology

Dopaminergic and serotonergic hallucinations

It has been reported that in serotonergic hallucinations, the person maintains an awareness that they are hallucinating, unlike dopaminergic hallucinations.^[2]

Neuroanatomy

Hallucinations are associated with structural and functional abnormalities in primary and secondary sensory cortices. Reduced grey matter in regions of the superior temporal gyrus/middle temporal gyrus, including Broca's area, is associated with auditory hallucinations as a trait, while acute hallucinations are associated with increased activity in the same regions along with the hippocampus, parahippocampus, and the right hemispheric homologue of Broca's area in the inferior frontal gyrus.^[43] Grey and white matter abnormalities in visual regions are associated with visual hallucinations in diseases such as Alzheimer's disease, further supporting the notion of dysfunction in sensory regions underlying hallucinations.

One proposed model of hallucinations posits that over-activity in sensory regions, which is normally attributed to internal sources via feedforward networks to the inferior frontal gyrus, is interpreted as originating externally due to abnormal connectivity or functionality of the feedforward network.^[43] This is supported by cognitive studies those with hallucinations, who have demonstrated abnormal attribution of self generated stimuli.^[44]

Disruptions in thalamocortical circuitry may underlie the observed top down and bottom up dysfunction.^[45] Thalamocortical circuits, composed of projections between thalamic and cortical neurons and adjacent interneurons, underlie certain electrophysical characteristics (gamma oscillations) that are underlie sensory processing. Cortical inputs to thalamic neurons enable attentional modulation of sensory neurons. Dysfunction in sensory afferents, and abnormal cortical input may result in pre-existing expectations modulating sensory experience, potentially resulting in the generation of hallucinations. Hallucinations are associated with less accurate sensory processing, and more intense stimuli with less interference are necessary for accurate processing and the appearance of gamma oscillations (called "gamma synchrony"). Hallucinations are also associated with the absence of reduction in P50 amplitude in response to the presentation of a second stimuli after an initial stimulus; this is thought to represent failure to gate sensory stimuli, and can be exacerbated by dopamine release agents.^[46]

Abnormal assignment of salience to stimuli may be one mechanism of hallucinations. Dysfunctional dopamine signaling may lead to abnormal top down regulation of sensory processing, allowing expectations to distort sensory input.^[47]

Treatments

There are few treatments for many types of hallucinations. However, for those hallucinations caused by mental disease, a psychologist or psychiatrist should be consulted, and treatment will be based on the observations of those doctors. Antipsychotic and atypical antipsychotic medication may also be utilized to treat the illness if the symptoms are severe and cause significant distress.^{[citation needed]} For other causes of hallucinations there is no factual evidence to support any one treatment is scientifically tested and proven. However, abstaining from hallucinogenic drugs, stimulant drugs, managing stress levels, living healthily, and getting plenty of sleep can help reduce the prevalence of hallucinations. In all cases of hallucinations, medical attention should be sought out and informed of one's specific symptoms. Meta-analyses show that cognitive behavioral therapy^[48] and metacognitive training^[49] can also reduce the severity of hallucinations.

Epidemiology

Prevalence of hallucinations varies depending on underlying medical conditions,^[50]^[3] which sensory modalities are affected,^[4] age^[51]^[50] and culture.^[52] As of 2022, auditory hallucinations are the most well studied and most common sensory modality of hallucinations, with an estimated lifetime prevalence of 9.6%.^[51] Children and adolescents have been found to experience similar rates (12.7% and 12.4% respectively) which occur mostly during late childhood and adolescence. This is compared with adults and those over 60 (with rates of 5.8% and 4.8% respectively).^[51]^[50] For those with schizophrenia, the lifetime prevalence of hallucinations is 80%^[3] and the estimated prevalence of visual hallucinations is 27%, compared to 79% for auditory hallucinations.^[3] A 2019 study suggested 16.2% of adults with hearing impairment experience hallucinations, with prevalence rising to 24% in the most hearing impaired group.^[53]

A risk factor for multimodal hallucinations is prior experience of unimodal hallucinations.^[3] In 90% cases of psychosis, a visual hallucination occurs in combination with another sensory modality, most often being auditory or somatic.^[3] In schizophrenia, multimodal hallucinations are twice as common as unimodal ones.^[3]

A 2015 review of 55 publications from 1962 to 2014 found 16-28.6% of those experiencing hallucinations report at least some religious content in them,^[54]^: 415 along with 20-60% reporting some religious content in delusions.^[54]^: 415 There is some evidence for delusions being a risk factor for religious hallucinations, with and 61.7% of people having experienced any delusion and 75.9% of those having experienced a religious delusion found to also experience hallucinations.^[54]^: 421

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^ Sidgwick E, Johnson A, et al. (1894). "Report on the Census of Hallucinations". Proceedings of the Society for Psychical Research. X. London.
^ Slade PD, Bentall RP (1988). Sensory Deception: a scientific analysis of hallucination. London: Croom Helm.
^ Losurdo G, Principi M, Iannone A, Amoruso A, Ierardi E, Di Leo A, Barone M (April 2018). "Extra-intestinal manifestations of non-celiac gluten sensitivity: An expanding paradigm". World Journal of Gastroenterology (Review). 24 (14): 1521–1530. doi:10.3748/wjg.v24.i14.1521. PMC 5897856. PMID 29662290.{{cite journal}}: CS1 maint: unflagged free DOI (link)
^ ^a ^b Brown G, Thompson W. "Functional Brain Imaging in Schizophrenia: Selected Results and Methods". In Swerdlow N (ed.). Behavioral Neurobiology of Schizophrenia and its Treatment. Springer. pp. 185–189.
^ Boksa P (July 2009). "On the neurobiology of hallucinations". Journal of Psychiatry & Neuroscience. 34 (4): 260–262. PMC 2702442. PMID 19568476.
^ Kumar S, Soren S, Chaudhury S (July 2009). "Hallucinations: Etiology and clinical implications". Industrial Psychiatry Journal. 18 (2): 119–126. doi:10.4103/0972-6748.62273. PMC 2996210. PMID 21180490.{{cite journal}}: CS1 maint: unflagged free DOI (link)
^ Behrendt RP (May 2006). "Dysregulation of thalamic sensory "transmission" in schizophrenia: neurochemical vulnerability to hallucinations". Journal of Psychopharmacology. 20 (3): 356–372. doi:10.1177/0269881105057696. PMID 16174672. S2CID 17104995.
^ Aleman A, Vercammon A. "The Bottom Up and Top Down Components of Hallucinatory Phenomenon". In Jardri R, Cachia A, Pins D, Thomas P (eds.). The Neuroscience of Hallucinations. Springer.
^ Turner DT, Burger S, Smit F, Valmaggia LR, van der Gaag M (March 2020). "What Constitutes Sufficient Evidence for Case Formulation-Driven CBT for Psychosis? Cumulative Meta-analysis of the Effect on Hallucinations and Delusions". Schizophrenia Bulletin. 46 (5): 1072–1085. doi:10.1093/schbul/sbaa045. PMC 7505201. PMID 32221536.
^ Penney D, Sauvé G, Mendelson D, Thibaudeau É, Moritz S, Lepage M (March 2022). "Immediate and Sustained Outcomes and Moderators Associated With Metacognitive Training for Psychosis: A Systematic Review and Meta-analysis". JAMA Psychiatry. doi:10.1001/jamapsychiatry.2022.0277. PMC 8943641. PMID 35320347.
^ ^a ^b ^c de Leede-Smith, Saskia; Barkus, Emma (2013). "A comprehensive review of auditory verbal hallucinations: lifetime prevalence, correlates and mechanisms in healthy and clinical individuals". Frontiers in Human Neuroscience. 7. doi:10.3389/fnhum.2013.00367. ISSN 1662-5161.{{cite journal}}: CS1 maint: unflagged free DOI (link)
^ ^a ^b ^c Maijer, K.; Begemann, M. J. H.; Palmen, S. J. M. C.; Leucht, S.; Sommer, I. E. C. (2017-09-28). "Auditory hallucinations across the lifespan: a systematic review and meta-analysis". Psychological Medicine. 48 (6): 879–888. doi:10.1017/s0033291717002367. ISSN 0033-2917.
^ Palmira, Bunevičius, Robertas Stompe, Thomas Adomaitienė, Virginija Vaškelytė , Jolanta-Justina Kupčinskas, Limas Stakišaitis , Donatas Meilius , Kazimieras Liubarskienė , Zita Vincenta Bhui, Kamaldeep Kaunas University of Medicine Rudalevičienė, (2008-09-08). The impact of personal religiosity and culture on the content of delusions and hallucinations in schizophrenia. Lithuanian Academic Libraries Network (LABT). OCLC 654554799.{{cite book}}: CS1 maint: extra punctuation (link) CS1 maint: multiple names: authors list (link)
^ E., Linszen, M. M.J. van Zanten, G. A. Teunisse, R. J. Brouwer, R. M. Scheltens, P. Sommer, I. (January 2019). Auditory hallucinations in adults with hearing impairment : a large prevalence study. Cambridge University Press. OCLC 1303694862.{{cite book}}: CS1 maint: multiple names: authors list (link)
^ ^a ^b ^c Cook, Christopher CH (2015-03-12). "Religious psychopathology: The prevalence of religious content of delusions and hallucinations in mental disorder". International Journal of Social Psychiatry. 61 (4): 404–425. doi:10.1177/0020764015573089. ISSN 0020-7640.

External links

Hearing Voices Network
"Anthropology and Hallucinations; chapter from The Making of Religion". psychanalyse-paris.com. November 4, 2006. Retrieved October 4, 2016.
"The voice inside: A practical guide to coping with hearing voices"
Psychology Terms
Hallucination: A Normal Phenomenon?
Fasting-induced hallucination
Geometric visual hallucinations, Euclidean symmetry and the functional architecture of striate cortex

[Chiu-1] Chiu LP (1989). "Differential diagnosis and management of hallucinations" (PDF). Journal of the Hong Kong Medical Association. t 41 (3): 292–7.

[newrev2018-2] Jalal B (November 2018). "The neuropharmacology of sleep paralysis hallucinations: serotonin 2A activation and a novel therapeutic drug". Psychopharmacology. 235 (11): 3083–3091. doi:10.1007/s00213-018-5042-1. PMC 6208952. PMID 30288594.

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[LosurdoPrincipi2018-42] Losurdo G, Principi M, Iannone A, Amoruso A, Ierardi E, Di Leo A, Barone M (April 2018). "Extra-intestinal manifestations of non-celiac gluten sensitivity: An expanding paradigm". World Journal of Gastroenterology (Review). 24 (14): 1521–1530. doi:10.3748/wjg.v24.i14.1521. PMC 5897856. PMID 29662290.{{cite journal}}: CS1 maint: unflagged free DOI (link)

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[45] Kumar S, Soren S, Chaudhury S (July 2009). "Hallucinations: Etiology and clinical implications". Industrial Psychiatry Journal. 18 (2): 119–126. doi:10.4103/0972-6748.62273. PMC 2996210. PMID 21180490.{{cite journal}}: CS1 maint: unflagged free DOI (link)

[46] Behrendt RP (May 2006). "Dysregulation of thalamic sensory "transmission" in schizophrenia: neurochemical vulnerability to hallucinations". Journal of Psychopharmacology. 20 (3): 356–372. doi:10.1177/0269881105057696. PMID 16174672. S2CID 17104995.

[47] Aleman A, Vercammon A. "The Bottom Up and Top Down Components of Hallucinatory Phenomenon". In Jardri R, Cachia A, Pins D, Thomas P (eds.). The Neuroscience of Hallucinations. Springer.

[48] Turner DT, Burger S, Smit F, Valmaggia LR, van der Gaag M (March 2020). "What Constitutes Sufficient Evidence for Case Formulation-Driven CBT for Psychosis? Cumulative Meta-analysis of the Effect on Hallucinations and Delusions". Schizophrenia Bulletin. 46 (5): 1072–1085. doi:10.1093/schbul/sbaa045. PMC 7505201. PMID 32221536.

[49] Penney D, Sauvé G, Mendelson D, Thibaudeau É, Moritz S, Lepage M (March 2022). "Immediate and Sustained Outcomes and Moderators Associated With Metacognitive Training for Psychosis: A Systematic Review and Meta-analysis". JAMA Psychiatry. doi:10.1001/jamapsychiatry.2022.0277. PMC 8943641. PMID 35320347.

[:2-50] Leede-Smith, Saskia; Barkus, Emma (2013). "A comprehensive review of auditory verbal hallucinations: lifetime prevalence, correlates and mechanisms in healthy and clinical individuals". Frontiers in Human Neuroscience. 7. doi:10.3389/fnhum.2013.00367. ISSN 1662-5161.{{cite journal}}: CS1 maint: unflagged free DOI (link)

[:3-51] Maijer, K.; Begemann, M. J. H.; Palmen, S. J. M. C.; Leucht, S.; Sommer, I. E. C. (2017-09-28). "Auditory hallucinations across the lifespan: a systematic review and meta-analysis". Psychological Medicine. 48 (6): 879–888. doi:10.1017/s0033291717002367. ISSN 0033-2917.

[52] Palmira, Bunevičius, Robertas Stompe, Thomas Adomaitienė, Virginija Vaškelytė , Jolanta-Justina Kupčinskas, Limas Stakišaitis , Donatas Meilius , Kazimieras Liubarskienė , Zita Vincenta Bhui, Kamaldeep Kaunas University of Medicine Rudalevičienė, (2008-09-08). The impact of personal religiosity and culture on the content of delusions and hallucinations in schizophrenia. Lithuanian Academic Libraries Network (LABT). OCLC 654554799.{{cite book}}: CS1 maint: extra punctuation (link) CS1 maint: multiple names: authors list (link)

[53] E., Linszen, M. M.J. van Zanten, G. A. Teunisse, R. J. Brouwer, R. M. Scheltens, P. Sommer, I. (January 2019). Auditory hallucinations in adults with hearing impairment : a large prevalence study. Cambridge University Press. OCLC 1303694862.{{cite book}}: CS1 maint: multiple names: authors list (link)

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@@ Line 27: / Line 27: @@
 A '''hallucination''' is a perception in the absence of an external [[stimulus (physiology)|stimulus]] that has the qualities of a real perception. Hallucinations are vivid, substantial, and are perceived to be located in external objective space. They are distinguishable from several related [[phenomena]], such as dreaming, which does not involve wakefulness; [[pseudohallucination]], which does not mimic real perception, and is accurately perceived as unreal; [[illusion]], which involves distorted or misinterpreted real perception; and [[mental imagery|imagery]] (imagination), which does not mimic real perception, and is under voluntary control.<ref name="Chiu">{{cite journal| vauthors = Chiu LP |year=1989|title=Differential diagnosis and management of hallucinations|journal=Journal of the Hong Kong Medical Association|volume=t 41|issue=3|pages=292–7|url=http://hkjo.lib.hku.hk/archive/files/2c023b7934fcf5e064bfd487061eaa53.pdf}}</ref> Hallucinations also differ from "[[delusion]]al perceptions", in which a correctly sensed and interpreted stimulus (i.e., a real perception) is given some additional significance. Many hallucinations happen also during [[sleep paralyses]].<ref name="newrev2018">{{cite journal | vauthors = Jalal B | title = The neuropharmacology of sleep paralysis hallucinations: serotonin 2A activation and a novel therapeutic drug | journal = Psychopharmacology | volume = 235 | issue = 11 | pages = 3083–3091 | date = November 2018 | pmid = 30288594 | pmc = 6208952 | doi = 10.1007/s00213-018-5042-1 | doi-access = free }}</ref>
-Hallucinations can occur in any sensory modality—[[visual system|visual]], [[auditory hallucination|auditory]], [[olfaction|olfactory]], [[taste|gustatory]], [[tactition|tactile]], [[proprioception|proprioceptive]], [[equilibrioception|equilibrioceptive]], [[nociception|nociceptive]], [[thermoception|thermoceptive]] and [[time perception|chronoceptive]].
+Hallucinations can occur in any [[Stimulus modality|sensory modality]]—[[visual system|visual]], [[auditory hallucination|auditory]], [[olfaction|olfactory]], [[taste|gustatory]], [[tactition|tactile]], [[proprioception|proprioceptive]], [[equilibrioception|equilibrioceptive]], [[nociception|nociceptive]], [[thermoception|thermoceptive]] and [[time perception|chronoceptive]]. Hallucinations are referred to as multimodal if multiple sensory modalities occur.<ref name=":0">{{Cite web |last=Montagnese |first=Marcella |last2=Leptourgos |first2=Pantelis |last3=Fernyhough |first3=Charles |last4=Waters |first4=Flavie |last5=Laroi |first5=Frank |last6=Jardri |first6=Renaud |last7=McCarthy-Jones |first7=Simon |last8=Thomas |first8=Neil |last9=Dudley |first9=Rob |date=2020-02-03 |title=A Review of Multimodal Hallucinations: Categorisation, Assessment, Theoretical Perspectives And Clinical Recommendations |url=http://dx.doi.org/10.31219/osf.io/zebxv |access-date=2022-04-26 |website=dx.doi.org}}</ref><ref name=":1">{{Cite journal |last=Dudley |first=Robert |last2=Aynsworth |first2=Charlotte |last3=Cheetham |first3=Rea |last4=McCarthy-Jones |first4=Simon |last5=Collerton |first5=Daniel |date=November 2018 |title=Prevalence and characteristics of multi-modal hallucinations in people with psychosis who experience visual hallucinations |url=http://dx.doi.org/10.1016/j.psychres.2018.08.032 |journal=Psychiatry Research |volume=269 |pages=25–30 |doi=10.1016/j.psychres.2018.08.032 |issn=0165-1781}}</ref>
 A mild form of hallucination is known as a ''disturbance'', and can occur in most of the senses above. These may be things like seeing movement in [[peripheral vision]], or hearing faint noises or voices. Auditory hallucinations are very common in [[schizophrenia]]. They may be benevolent (telling the subject good things about themselves) or malicious, cursing the subject. 55% of auditory hallucinations are malicious in content,<ref>{{Cite journal|title=Auditory Hallucinations in Adult Populations|url=https://www.psychiatrictimes.com/view/auditory-hallucinations-adult-populations|access-date=2021-02-01|journal=Psychiatric Times|series=Vol 31 No 12|date=30 December 2014|volume=31|issue=12|last1=Flavie Waters|first1=MSc}}</ref> for example, people talking about the subject, not speaking to them directly. Like auditory hallucinations, the source of the visual counterpart can also be behind the subject. This can produce a feeling of being looked or stared at, usually with malicious intent.{{Citation needed|date=August 2016}} Frequently, auditory hallucinations and their visual counterpart are experienced by the subject together.<ref>{{cite journal | vauthors = Waters F, Collerton D, Ffytche DH, Jardri R, Pins D, Dudley R, Blom JD, Mosimann UP, Eperjesi F, Ford S, Larøi F | display-authors = 6 | title = Visual hallucinations in the psychosis spectrum and comparative information from neurodegenerative disorders and eye disease | journal = Schizophrenia Bulletin | volume = 40 Suppl 4 | issue = 4 | pages = S233–S245 | date = July 2014 | pmid = 24936084 | pmc = 4141306 | doi = 10.1093/schbul/sbu036 | doi-access = free }}</ref>
@@ Line 38: / Line 38: @@
 ==Classification==
 Hallucinations may be manifested in a variety of forms.<ref>{{cite journal | vauthors = Chen E, Berrios GE | title = Recognition of hallucinations: a new multidimensional model and methodology | journal = Psychopathology | volume = 29 | issue = 1 | pages = 54–63 | year = 1996 | pmid = 8711076 | doi = 10.1159/000284972 }}</ref> Various forms of hallucinations affect different senses, sometimes occurring simultaneously, creating multiple sensory hallucinations for those experiencing them.
-===Visual===
-{{see also|Visual hallucinations in psychosis|Pareidolia|Palinopsia}}
-A ''visual hallucination'' is "the perception of an external visual stimulus where none exists".<ref>{{cite web| vauthors = Pelak V |title=Approach to the patient with visual hallucinations|url=http://www.uptodate.com/contents/approach-to-the-patient-with-visual-hallucinations|website=www.uptodate.com|access-date=2014-08-25|url-status=live|archive-url=https://web.archive.org/web/20140826120056/http://www.uptodate.com/contents/approach-to-the-patient-with-visual-hallucinations|archive-date=2014-08-26}}</ref> A separate but related phenomenon is a ''visual illusion'', which is a distortion of a real external stimulus. Visual hallucinations are classified as simple or complex:
-* ''Simple visual hallucinations'' (SVH) are also referred to as non-formed visual hallucinations and elementary visual hallucinations. These terms refer to lights, colors, geometric shapes, and indiscrete objects. These can be further subdivided into [[phosphene]]s which are SVH without structure, and [[photopsia]]s which are SVH with geometric structures.
-* ''Complex visual hallucinations'' (CVH) are also referred to as formed visual hallucinations. CVHs are clear, lifelike images or scenes such as people, animals, objects, places, etc.
-For example, one may report hallucinating a giraffe. A simple visual hallucination is an amorphous figure that may have a similar shape or color to a giraffe (''looks like'' a giraffe), while a complex visual hallucination is a discrete, lifelike image that ''is'', unmistakably, a giraffe.
 ===Auditory===
 {{main|Auditory hallucination}}
-[[Sound|Auditory]] hallucinations (also known as ''paracusia'')<ref>{{cite web|url=http://medical-dictionary.thefreedictionary.com/paracusia|title=Paracusia|publisher=thefreedictionary.com}}</ref> are the perception of sound without outside stimulus. These hallucinations are the most common type of hallucination.<ref>{{cite book| vauthors = Nolen-Hoeksema S |title=Abnormal Psychology|date=2014|publisher=McGraw-Hill|page=283|edition=6e}}</ref> Auditory hallucinations can be divided into two categories: elementary and complex. Elementary hallucinations are the perception of sounds such as hissing, whistling, an extended tone, and more. In many cases, [[tinnitus]] is an elementary auditory hallucination. However, some people who experience certain types of tinnitus, especially pulsatile tinnitus, are actually hearing the blood rushing through vessels near the ear. Because the auditory stimulus is present in this situation, it does not qualify it as a hallucination.
+[[Sound|Auditory]] hallucinations (also known as ''paracusia'')<ref>{{cite web |title=Paracusia |url=http://medical-dictionary.thefreedictionary.com/paracusia |publisher=thefreedictionary.com}}</ref> are the perception of sound without outside stimulus. Auditory hallucinations can be divided into elementary and complex, along with verbal and nonverbal.  These hallucinations are the most common type of hallucination, with auditory verbal hallucinations being more common than nonverbal.<ref>{{cite book |title=Abnormal Psychology |vauthors=Nolen-Hoeksema S |date=2014 |publisher=McGraw-Hill |edition=6e |page=283}}</ref> Elementary hallucinations are the perception of sounds such as hissing, whistling, an extended tone, and more. In many cases, [[tinnitus]] is an elementary auditory hallucination. However, some people who experience certain types of tinnitus, especially pulsatile tinnitus, are actually hearing the blood rushing through vessels near the ear. Because the auditory stimulus is present in this situation, it does not qualify it as a hallucination.
 Complex hallucinations are those of voices, music, or other sounds that may or may not be clear, may or may not be familiar, and may be friendly, aggressive, or among other possibilities. A hallucination of a single individual person of one or more talking voices is particularly associated with [[psychosis|psychotic]] disorders such as [[schizophrenia]], and hold special significance in diagnosing these conditions.
-Another typical disorder where auditory hallucinations are very common is [[dissociative identity disorder]]. In schizophrenia voices are normally perceived coming from outside the person but in dissociative disorders they are perceived as originating from within the person, commenting in their head instead of behind their back. Differential diagnosis between schizophrenia and [[dissociative disorder]]s is challenging due to many overlapping symptoms, especially [[Kurt Schneider|Schneiderian first rank symptoms]] such as hallucinations.<ref>{{cite journal | vauthors = Shibayama M | title = [Differential diagnosis between dissociative disorders and schizophrenia] | journal = Seishin Shinkeigaku Zasshi = Psychiatria et Neurologia Japonica | volume = 113 | issue = 9 | pages = 906–911 | year = 2011 | pmid = 22117396 }}</ref> However, many people not suffering from diagnosable [[mental illness]] may sometimes hear voices as well.<ref>{{cite web|url=http://www.livescience.com/7177-hearing-voices-people.html|title=Hearing Voices: Some People Like It| vauthors = Thompson A |publisher=LiveScience.com|date=September 15, 2006|access-date=2006-11-25|url-status=live|archive-url=https://web.archive.org/web/20061102150621/http://www.livescience.com/humanbiology/060915_hearing_voices.html|archive-date=November 2, 2006}}</ref> One important example to consider when forming a differential diagnosis for a patient with paracusia is lateral [[temporal lobe epilepsy]]. Despite the tendency to associate hearing voices, or otherwise hallucinating, and [[psychosis]] with schizophrenia or other psychiatric illnesses, it is crucial to take into consideration that, even if a person does exhibit psychotic features, they do not necessarily suffer from a psychiatric disorder on its own. Disorders such as [[Wilson's disease]], various [[endocrine disease]]s, numerous [[metabolic disturbance]]s, [[multiple sclerosis]], [[systemic lupus erythematosus]], [[porphyria]], [[sarcoidosis]], and many others can present with psychosis.
+Another typical disorder where auditory hallucinations are very common is [[dissociative identity disorder]]. In schizophrenia voices are normally perceived coming from outside the person but in dissociative disorders they are perceived as originating from within the person, commenting in their head instead of behind their back. Differential diagnosis between schizophrenia and [[dissociative disorder]]s is challenging due to many overlapping symptoms, especially [[Kurt Schneider|Schneiderian first rank symptoms]] such as hallucinations.<ref>{{cite journal |vauthors=Shibayama M |year=2011 |title=[Differential diagnosis between dissociative disorders and schizophrenia] |journal=Seishin Shinkeigaku Zasshi = Psychiatria et Neurologia Japonica |volume=113 |issue=9 |pages=906–911 |pmid=22117396}}</ref> However, many people not suffering from diagnosable [[mental illness]] may sometimes hear voices as well.<ref>{{cite web |date=September 15, 2006 |title=Hearing Voices: Some People Like It |url=http://www.livescience.com/7177-hearing-voices-people.html |url-status=live |archive-url=https://web.archive.org/web/20061102150621/http://www.livescience.com/humanbiology/060915_hearing_voices.html |archive-date=November 2, 2006 |access-date=2006-11-25 |publisher=LiveScience.com |vauthors=Thompson A}}</ref> One important example to consider when forming a differential diagnosis for a patient with paracusia is lateral [[temporal lobe epilepsy]]. Despite the tendency to associate hearing voices, or otherwise hallucinating, and [[psychosis]] with schizophrenia or other psychiatric illnesses, it is crucial to take into consideration that, even if a person does exhibit psychotic features, they do not necessarily suffer from a psychiatric disorder on its own. Disorders such as [[Wilson's disease]], various [[endocrine disease]]s, numerous [[metabolic disturbance]]s, [[multiple sclerosis]], [[systemic lupus erythematosus]], [[porphyria]], [[sarcoidosis]], and many others can present with psychosis.
-Musical hallucinations are also relatively common in terms of complex auditory hallucinations and may be the result of a wide range of causes ranging from hearing-loss (such as in [[musical ear syndrome]], the auditory version of [[Charles Bonnet syndrome]]), lateral temporal lobe epilepsy,<ref>Engmann, Birk; Reuter, Mike: "Spontaneous perception of melodies – hallucination or epilepsy?" ''Nervenheilkunde'' 2009 Apr 28: 217-221. {{ISSN|0722-1541}}</ref> arteriovenous malformation,<ref name="pmid19682829">{{cite journal | vauthors = Ozsarac M, Aksay E, Kiyan S, Unek O, Gulec FF | title = De novo cerebral arteriovenous malformation: Pink Floyd's song "Brick in the Wall" as a warning sign | journal = The Journal of Emergency Medicine | volume = 43 | issue = 1 | pages = e17–e20 | date = July 2012 | pmid = 19682829 | doi = 10.1016/j.jemermed.2009.05.035 }}</ref> stroke, [[lesion]], [[abscess]], or tumor.<ref>{{cite web|url=https://www.sciencedaily.com/releases/2000/08/000809065249.htm|title=Rare Hallucinations Make Music In The Mind|publisher=ScienceDaily.com|date=August 9, 2000|access-date=2006-12-31|url-status=live|archive-url=https://web.archive.org/web/20061205053946/http://www.sciencedaily.com/releases/2000/08/000809065249.htm|archive-date=December 5, 2006}}</ref>
+Musical hallucinations are also relatively common in terms of complex auditory hallucinations and may be the result of a wide range of causes ranging from hearing-loss (such as in [[musical ear syndrome]], the auditory version of [[Charles Bonnet syndrome]]), lateral temporal lobe epilepsy,<ref>Engmann, Birk; Reuter, Mike: "Spontaneous perception of melodies – hallucination or epilepsy?" ''Nervenheilkunde'' 2009 Apr 28: 217-221. {{ISSN|0722-1541}}</ref> arteriovenous malformation,<ref name="pmid19682829">{{cite journal |vauthors=Ozsarac M, Aksay E, Kiyan S, Unek O, Gulec FF |date=July 2012 |title=De novo cerebral arteriovenous malformation: Pink Floyd's song "Brick in the Wall" as a warning sign |journal=The Journal of Emergency Medicine |volume=43 |issue=1 |pages=e17–e20 |doi=10.1016/j.jemermed.2009.05.035 |pmid=19682829}}</ref> stroke, [[lesion]], [[abscess]], or tumor.<ref>{{cite web |date=August 9, 2000 |title=Rare Hallucinations Make Music In The Mind |url=https://www.sciencedaily.com/releases/2000/08/000809065249.htm |url-status=live |archive-url=https://web.archive.org/web/20061205053946/http://www.sciencedaily.com/releases/2000/08/000809065249.htm |archive-date=December 5, 2006 |access-date=2006-12-31 |publisher=ScienceDaily.com}}</ref>
 The [[Hearing Voices Movement]] is a support and advocacy group for people who hallucinate voices, but do not otherwise show signs of mental illness or impairment.
-High [[caffeine]] consumption has been linked to an increase in likelihood of one experiencing auditory hallucinations. A study conducted by the [[La Trobe University]] School of Psychological Sciences revealed that as few as five cups of coffee a day (approximately 500&nbsp;mg of caffeine) could trigger the phenomenon.<ref>{{cite web | url = http://www.medicalnewstoday.com/articles/227884.php | work = Medical News Today | title = Too Much Coffee Can Make You Hear Things That Are Not There | date = 8 June 2011 | archive-url = https://web.archive.org/web/20130311185810/http://www.medicalnewstoday.com/articles/227884.php | archive-date=2013-03-11 }}</ref>
+High [[caffeine]] consumption has been linked to an increase in likelihood of one experiencing auditory hallucinations. A study conducted by the [[La Trobe University]] School of Psychological Sciences revealed that as few as five cups of coffee a day (approximately 500&nbsp;mg of caffeine) could trigger the phenomenon.<ref>{{cite web |date=8 June 2011 |title=Too Much Coffee Can Make You Hear Things That Are Not There |url=http://www.medicalnewstoday.com/articles/227884.php |archive-url=https://web.archive.org/web/20130311185810/http://www.medicalnewstoday.com/articles/227884.php |archive-date=2013-03-11 |work=Medical News Today}}</ref>
+===Visual===
+{{see also|Visual hallucinations in psychosis|Pareidolia|Palinopsia}}
+A ''visual hallucination'' is "the perception of an external visual stimulus where none exists".<ref>{{cite web| vauthors = Pelak V |title=Approach to the patient with visual hallucinations|url=http://www.uptodate.com/contents/approach-to-the-patient-with-visual-hallucinations|website=www.uptodate.com|access-date=2014-08-25|url-status=live|archive-url=https://web.archive.org/web/20140826120056/http://www.uptodate.com/contents/approach-to-the-patient-with-visual-hallucinations|archive-date=2014-08-26}}</ref> A separate but related phenomenon is a ''visual illusion'', which is a distortion of a real external stimulus. Visual hallucinations are classified as simple or complex:
+* ''Simple visual hallucinations'' (SVH) are also referred to as non-formed visual hallucinations and elementary visual hallucinations. These terms refer to lights, colors, geometric shapes, and indiscrete objects. These can be further subdivided into [[phosphene]]s which are SVH without structure, and [[photopsia]]s which are SVH with geometric structures.
+* ''Complex visual hallucinations'' (CVH) are also referred to as formed visual hallucinations. CVHs are clear, lifelike images or scenes such as people, animals, objects, places, etc.
+For example, one may report hallucinating a giraffe. A simple visual hallucination is an amorphous figure that may have a similar shape or color to a giraffe (''looks like'' a giraffe), while a complex visual hallucination is a discrete, lifelike image that ''is'', unmistakably, a giraffe.
 ===Command{{anchor|Command hallucination|Command hallucinations}}===
@@ Line 82: / Line 83: @@
 ===General somatic sensations===
 General somatic sensations of a hallucinatory nature are experienced when an individual feels that their body is being mutilated, i.e. twisted, torn, or disemboweled. Other reported cases are invasion by animals in the person's internal organs, such as snakes in the stomach or frogs in the [[rectum]]. The general feeling that one's flesh is decomposing is also classified under this type of this hallucination.<ref name="Barker_1997"/>{{Citation needed|reason=I read the page of the book that you used as a source where it was supposed to be the content posted here but what I found has nothing to do with the data provided in this paragraph, so you did not provide an appropriate source.|date=December 2017}}
+=== Multimodal ===
+A hallucination involving [[Stimulus modality|sensory modalities]] is called multimodal, analogous to unimodal hallucinations which have only one sensory modality. The multiple sensory modalities can occur at the same time (simultaneously) or with a delay (serial), be related or unrelated to each other, and be consistent with reality (congruent) or not (incongruent).<ref name=":0" /><ref name=":1" /> For example, a person talking in a hallucination would be congruent with reality, but a cat talking would not be.
+Multimodal hallucinations are correlated to poorer mental health outcomes, and are often experienced as feeling more real.<ref name=":0" />
 ==Cause==
@@ Line 154: / Line 160: @@
 ==Epidemiology==
 {{Cleanup rewrite|disjointed and makes no sense|Hallucination#Epidemiology|date=January 2019}}
-Several recent studies on the prevalence of hallucinations in the general population have appeared.,<ref>{{cite journal | vauthors = Ohayon MM | title = Prevalence of hallucinations and their pathological associations in the general population | journal = Psychiatry Research | volume = 97 | issue = 2–3 | pages = 153–164 | date = December 2000 | pmid = 11166087 | doi = 10.1016/S0165-1781(00)00227-4 | s2cid = 46717729 }}</ref>{{clarify|higher than what???? This makes no sense, and doesn't even make sense in the context of the previous section|date=January 2019}} A recent US study indicated a lifetime prevalence of 10-15% for vivid sensory hallucinations.<ref>{{cite web | vauthors = Frankel J |title=Hallucinations Are Everywhere |url=https://getpocket.com/explore/item/hallucinations-are-everywhere?utm_source=pocket-newtab |website=Pocket |publisher=Atlantic Monthly |access-date=22 May 2020}}</ref> Compared with the English Sidgewick Study of 1894, relative frequencies of sensory modalities differed in the US with fewer visual hallucinations.<ref>{{cite journal | vauthors = Tien AY | title = Distributions of hallucinations in the population | journal = Social Psychiatry and Psychiatric Epidemiology | volume = 26 | issue = 6 | pages = 287–292 | date = December 1991 | pmid = 1792560 | doi = 10.1007/BF00789221 | s2cid = 28848635 }}</ref>
+Prevalence of hallucinations varies depending on underlying medical conditions,<ref name=":2">{{Cite journal |last=de Leede-Smith |first=Saskia |last2=Barkus |first2=Emma |date=2013 |title=A comprehensive review of auditory verbal hallucinations: lifetime prevalence, correlates and mechanisms in healthy and clinical individuals |url=http://dx.doi.org/10.3389/fnhum.2013.00367 |journal=Frontiers in Human Neuroscience |volume=7 |doi=10.3389/fnhum.2013.00367 |issn=1662-5161}}</ref><ref name=":0" /> which sensory modalities are affected,<ref name=":1" /> age<ref name=":3">{{Cite journal |last=Maijer |first=K. |last2=Begemann |first2=M. J. H. |last3=Palmen |first3=S. J. M. C. |last4=Leucht |first4=S. |last5=Sommer |first5=I. E. C. |date=2017-09-28 |title=Auditory hallucinations across the lifespan: a systematic review and meta-analysis |url=http://dx.doi.org/10.1017/s0033291717002367 |journal=Psychological Medicine |volume=48 |issue=6 |pages=879–888 |doi=10.1017/s0033291717002367 |issn=0033-2917}}</ref><ref name=":2" /> and culture.<ref>{{Cite book |last=Palmira |first=Bunevičius, Robertas Stompe, Thomas Adomaitienė, Virginija Vaškelytė , Jolanta-Justina Kupčinskas, Limas Stakišaitis , Donatas Meilius , Kazimieras Liubarskienė , Zita Vincenta Bhui, Kamaldeep Kaunas University of Medicine Rudalevičienė, |url=http://worldcat.org/oclc/654554799 |title=The impact of personal religiosity and culture on the content of delusions and hallucinations in schizophrenia |date=2008-09-08 |publisher=Lithuanian Academic Libraries Network (LABT) |oclc=654554799}}</ref> As of 2022, auditory hallucinations are the most well studied and most common sensory modality of hallucinations, with an estimated lifetime prevalence of 9.6%.<ref name=":3" /> Children and adolescents have been found to experience similar rates (12.7% and 12.4% respectively) which occur mostly during late childhood and adolescence. This is compared with adults and those over 60 (with rates of 5.8% and 4.8% respectively).<ref name=":3" /><ref name=":2" /> For those with schizophrenia, the lifetime prevalence of hallucinations is 80%<ref name=":0" /> and the estimated prevalence of visual hallucinations is 27%, compared to 79% for auditory hallucinations.<ref name=":0" /> A 2019 study suggested 16.2% of adults with [[Hearing loss|hearing impairment]] experience hallucinations, with prevalence rising to 24% in the most hearing impaired group.<ref>{{Cite book |last=E. |first=Linszen, M. M.J. van Zanten, G. A. Teunisse, R. J. Brouwer, R. M. Scheltens, P. Sommer, I. |url=http://worldcat.org/oclc/1303694862 |title=Auditory hallucinations in adults with hearing impairment : a large prevalence study |date=January 2019 |publisher=Cambridge University Press |oclc=1303694862}}</ref>
+A risk factor for multimodal hallucinations is prior experience of unimodal hallucinations.<ref name=":0" /> In 90% cases of psychosis, a visual hallucination occurs in combination with another sensory modality, most often being auditory or somatic.<ref name=":0" /> In schizophrenia, multimodal hallucinations are twice as common as unimodal ones.<ref name=":0" />
+A 2015 review of 55 publications from 1962 to 2014 found 16-28.6% of those experiencing hallucinations report at least some religious content in them,<ref name=":4">{{Cite journal |last=Cook |first=Christopher CH |date=2015-03-12 |title=Religious psychopathology: The prevalence of religious content of delusions and hallucinations in mental disorder |url=http://dx.doi.org/10.1177/0020764015573089 |journal=International Journal of Social Psychiatry |volume=61 |issue=4 |pages=404–425 |doi=10.1177/0020764015573089 |issn=0020-7640}}</ref>{{Rp|page=415}} along with 20-60% reporting [[Religious delusion|some religious content in delusions]].<ref name=":4" />{{Rp|page=415}} There is some evidence for [[Delusion|delusions]] being a risk factor for religious hallucinations, with and 61.7% of people having experienced any delusion and 75.9% of those having experienced a religious delusion found to also experience hallucinations.<ref name=":4" />{{Rp|page=421}}
 == See also ==

Classification	D ICD-10: R44 ICD-9-CM: 780.1 MeSH: D006212 DiseasesDB: 19769
External resources	MedlinePlus: 003258 Patient UK: Hallucination

v t e Signs and symptoms relating to perception, emotion and behaviour
Cognition	Confusion Delirium Psychosis Delusion Amnesia Anterograde amnesia Retrograde amnesia Convulsion Dizziness Disequilibrium Presyncope/Lightheadedness Vertigo
Emotion	Anger Anxiety Depression Fear Paranoia Hostility Irritability Suicidal ideation
Behavior	Verbosity Russell's sign
Perception	Sensory processing disorder Hallucination (Auditory hallucination) Smell Anosmia Hyposmia Dysosmia Parosmia Phantosmia Hyperosmia Synesthesia Taste Ageusia Hypogeusia Dysgeusia Hypergeusia