B

Background Object of PrimaryIdentification

see Dream screen.

Backmasking

see Backward masking.

Backward Masking and Illusions

Backward masking is also known as backwardsmasking and backmasking. All three terms areused in the popular music industry to denote arecording technique in which an auditory mes-sage is encrypted by recording it in reverse orderonto a track. As a consequence, the encryptedmessage can only be retrieved by playing thetrack backwards. The backward masking tech-nique was popularized during the 1960 s by TheBeatles, and has since been imitated by numer-ous bands. The urge to retrieve so-called back-ward messages in popular songs has yielded anumber of ‘messages’ that do not originate fromwords or sentences recorded backwards, but fromregular words or sentences that merely soundlike intelligible language when played backwards.These ‘messages’ are attributed to a ∗cognitiveillusion called ∗auditory pareidolia. Some exam-ples of auditory pareidolia on the basis of back-

ward masking can be found in the pop songsAnother one bites the dust by Queen (where thereversed sentence “Another one bites the dust”is rendered as “I decide to smoke marihuana”),Revolution nine by the Beatles (where the reversedwords “Number nine” are rendered as “Turnme on, deadman”), and Eldorado overture bythe Electric Light Orchestra (where the chantedword “Hallelujah” remains the same when playedbackwards). The latter phenomenon, where aphoneme remains the same when it is heard inreverse order, is called a phonetic palindrome.

ReferenceAranza, J. (1983). Backward masking unmasked.

Backward Satanic messages of Rock and Rollexposed. Shreveport, LA: Vital Issues Pr.

Bagel Vision

Also known as doughnut vision and donut vision.The term bagel vision is indebted to the Yid-dish verb beigen (to bend, to twist). It is usedto denote the visual perception of a punched-outor doughnut-shaped image, caused by a central,∗bilateral scotoma. Due to a loss of central vision,and a retention of peripheral vision, faces, forinstance, may be perceived in instances of bagelvision as a ring of flesh surrounding a black holeor a void. Bagel vision has been described in rela-tively rare cases of ∗visual aura occurring in thecontext of migraine. In the literature the termsbagel vision, doughnut vision, and donut vision

J.D. Blom, A Dictionary of Hallucinations,DOI 10.1007/978-1-4419-1223-7_2, © Springer Science+Business Media, LLC 2010

59

B Bananadine and Hallucinations

Fig. 1 Bagel vision. Illustration by JDB

are also used to denote a ring-shaped ∗scotomawith intact areas of central and peripheral vision.

ReferenceSacks, O. (1992). Migraine. Revised and expanded.

New York, NY: Vintage Books.

Bananadine and Hallucinations

The neologism bananadine is indebted to thenoun banana. It was introduced in 1967 in anarticle by Max Scherr, editor of the US under-ground newspaper Berkeley Barb, to denote afictional alkaloid with hallucinogenic propertiesallegedly present in the inside of banana peels(Musa x sapientum). However, biochemical analy-ses show that banana peels contain no significantamounts of any known psychoactive substancesother than serotonin (or its precursor, trypto-phan), which is considered inactive when ingestedorally or via the lungs. During the late 1960 s thenews from the Berkeley Barb article was amplifiedthrough numerous additional publications in thepopular media, and through the attention gener-ated by the US Food and Drug Administration’sinitiative to determine whether bananas should beclassified as illicit drugs. Eventually the banana-dine story was unmasked as a hoax, but the myththat the smoking or oral ingestion of dried or

baked banana peels can produce hallucinationspersisted in certain circles, and continues to resur-face from time to time.

ReferencesDonald, L. (1967). Cool talk about hot drugs. The

New York Time Magazine, August 6, p. 188.Rätsch, Chr. (2005). The encyclopedia of psy-

choactive plants. Ethnopharmacology andits applications. Translated by Baker, J.R.Rochester, VT: Park Street Press.

Belladonna Delirium

A term used to denote an anticholinergic∗delirium due to intoxication with compounds ofthe plant Atropa belladonna. See the entry Atropabelladonna and hallucinations.

Belladonna-Induced Hallucination

see Atropa belladonna and hallucinations.

Benham’s Disk

see Benham’s top.

Benham’s Top

Also known as Benham’s disk, Benham’s wheel,and artificial spectrum top. The eponym Ben-ham’s top refers to the British amateur scien-tist and toymaker Charles Edwin Benham (1860–1929), who in 1894 published an account inNature describing a device which he called theartificial spectrum top, with the aid of whichillusory colours can be created out of flicker-ing monochromatic light. The device consists ofa disc which is half black and half white, andbears three patterns of black concentric lines ofincreasing size. When the disc is rotated at aspeed of around 5–10 revolutions/s, four con-centric rings of colour appear. When the discrevolves clockwise, the colours red, green, paleblue, and dark purple can be discerned, runningfrom the centre towards the periphery. When itrevolves counter-clockwise, the colours appear

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Benign Hallucination B

Fig. 2 Benham’s top. Sources: Benham, C.E.(1894). The artificial spectrum top. Nature, 51,113–114; and: Fechner, G.T. (1838). Ueber eineScheibe zur Erzeugung subjectiver Farben. In:Annalen der Physik und Chemie. Edited byPoggendorff, J.C. Leipzig: Verlag von JohannAmbrosius Barth

in reverse order. The resulting illusory coloursare referred to as pattern-induced flicker colours(PFICs). The underlying effect is known as thePrévost–Fechner–Benham effect. The neurophys-iological correlates of this effect are not entirelyunderstood, but it is believed that both the retina

and the primary visual cortex play an active partin its mediation. Benham’s top was marketedas a toy for children. A variant of the device,of which Benham was apparently unaware, wasdescribed in 1838 by the German psychologistGustav Theodor Fechner (1801–1887). The illu-sory colours created by the two devices aretherefore generally known as ∗Fechner’s colours.This phenomenon is classified as a ∗physiologicalillusion.

ReferencesBenham, C.E. (1894). The artificial spectrum top.

Nature, 51, 113–114.Fechner, G.T. (1838). Ueber eine Scheibe zur

Erzeugung subjectiver Farben. In: Annalen derPhysik und Chemie. Edited by Poggendorff,J.C. Leipzig: Verlag von Johann AmbrosiousBarth.

Kenyon, G.T., Hill, D., Theiler, J., George, J.S.,Marshak, D.W. (2004). A theory of the Ben-ham top based on center-surround interac-tions in the parvocellular pathway. Neural Net-works, 17, 773–786.

Benham’s Wheel

see Benham’s top.

Benign Hallucination

Also referred to as non-morbid hallucination.The term benign hallucination is indebted tothe Latin words bene (good) and gignere (toentail, to bring forth). It was introduced in1960 by the American psychiatrist Gordon For-rer to denote a hallucination occurring outsidethe context of illness or pathology. Forrer usesthe term benign hallucination in opposition tothe term ∗malignant hallucination (i.e. a hallu-cination characterized by persistence, and asso-ciated with pathology, as in individuals with aclinical diagnosis of ∗schizophrenia). As Forrermaintains, “Hallucinations are surprisingly com-monplace occurrences. They may be brief andbenign as in the mundane auditory hallucinationof ‘hearing’ one’s name when one is quite alone.Or they may be persistent and malignant as in theauditory hallucination of paranoid schizophre-nia repeatedly accusing the subject of aberrant

61

B Bentall and Slade’s Definition of Hallucinations

practices. In the benign hallucinatory experiencesof everyday life only the fact of the experi-ence is usually recalled. In the malignant hal-lucination of psychosis, preoccupation with thesubjective sensory experience becomes intense . . .Benign hallucinations terminate by more or lesscomplete repression of the experience. Malignanthallucinations, on the other hand, spawn delu-sions, oftentimes themselves ceasing to exist ina manner analogous to plants which, in sprout-ing, replace the seeds from which they grew.”In clinical practice, the term benign hallucina-tion is used to denote hallucinatory phenom-ena such as ∗bereavement hallucinations, ∗simplemisperceptions, ∗visual hallucinations occurringin the context of ∗Charles Bonnet syndrome,∗musical hallucinations occurring in the elderly,and ∗deathbed visions.

ReferenceForrer, G.R. (1960). Benign auditory and visual

hallucinations. Archives of General Psychiatry,3, 95–98.

Bentall and Slade’s Definitionof Hallucinations

In 1988 the British psychologists Richard P. Ben-tall (b. 1956) and Peter D. Slade defined halluci-nations as follows. “Any percept-like experiencewhich (a) occurs in the absence of an appropriatestimulus, (b) has the full force or impact of thecorresponding actual (real) perception, and (c) isnot amenable to direct and voluntary control bythe experiencer.”

ReferenceSlade, P.D., Bentall, R.P. (1988). Sensory decep-

tion. A scientific analysis of hallucination. Lon-don: Johns Hopkins University Press.

Benzodiazepine-Induced Hallucination

The benzodiazepines (or ‘benzos’ for short)are formally known as CNS active 1,4-benzodiazepines. These substances constitute agroup of CNS depressants whose major actionis attributed to the potentiation of the gamma

aminobutyric acid (GABA) system via thebenzodiazepine receptors present in the CNS.The name benzodiazepine refers to the benzeneand diazepine ring systems constituting the corechemical structure of classic benzodiazepinesubstances. Some examples of classic benzo-diazepines are chlordiazepoxide, diazepam,lorazepam, and oxazepam. Historically, chlor-diazepoxide was the first of the centrally acting1,4-benzodiazepine derivatives. It was devel-oped during the 1950s by the group headedby the Polish-Jewish-American chemist LeoHenryk Sternbach (1908–2005), and introducedfor clinical use in 1960. Diazepam followed in1963, with other benzodiazepines patented bySternbach (and others) following successively. Inbiomedicine the benzodiazepines are prescribedfor a wide variety of purposes, including thetreatment of insomnia, epileptic seizures, anxiety,depression, agitation, aggression, and acutealcohol withdrawal. Because of their sedativeand anxiolytic properties, the benzodiazepinesare also widely misused. Their consumption maylead to dependency, as well as to a multitude ofadverse effects. ∗Nightmares and vivid ∗dreaminghave been reported during benzodiazepine use,as well as alterations in the qualitative characterof dream images. Reports of benzodiazepine-induced hallucinations are less common. In1968 the American psychiatrist Davis S. Viscottpublished a report on seven cases of apparenthallucinatory activity following the first-timeuse of chlordiazepoxide. However, it is unclearfrom Viscott’s report whether the hallucinatoryphenomena at hand were de novo halluci-nations, or pre-existent hallucinations whichthe affected individuals had apparently nevertalked about until they came to do so under theinfluence of chlordiazepoxide. Benzodiazepinewithdrawal, on the other hand, is notoriousfor its many perceptual rebound effects. Theseinclude ∗sensory deceptions and distortionssuch as ∗hyperaesthesia, ∗metamorphopsias,∗visual hallucinations, ∗auditory hallucinations,∗formication, and ∗body schema illusions.Although the effects of benzodiazepine usein individuals with a clinical diagnosis of∗schizophrenia have been studied extensivelythroughout the years, its influence upon halluci-nations and other psychotic symptoms remainssomewhat unclear. Some studies indicate that thebenzodiazepines may have a potentiating effecton antipsychotic substances, while others fail torecord such an effect, or even report a decrease

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Bereavement Hallucination B

in the effectiveness of antipsychotic agents underbenzodiazepine co-medication.

ReferencesCosta, E., ed. (1983). The benzodiazepines. From

molecular biology to clinical practice. NewYork, NY: Raven.

Viscott, D.S. (1968). Chlordiazepoxide and hal-lucinations. Archives of General Psychiatry, 19,370–376.

Bereavement Hallucination

Also known as post-bereavement hallucinationand grief hallucination. All three terms are usedto denote a heterogeneous group of ∗sensorydeceptions occurring in the context of grief overthe loss of a spouse or other loved one. As totheir content, bereavement hallucinations typi-cally involve the deceased person’s physical char-acteristics. Due to their ∗xenopathic character,bereavement hallucinations often have a highlyrealistic appearance. However, individuals in pos-session of proper reality monitoring skills tend torecognize these quite easily as non-sensory per-cepts. The prevalence of bereavement hallucina-tions in widowed individuals has been found tolie between 30% and 60%. In a classic study bythe British physician W. Dewi Rees among 363widowed persons, almost 50% reported havinghad one or more episodes of bereavement halluci-nation. Among these, ∗sensed presence (which isusually classified as a ∗hallucinoid experience nota ∗hallucination proper) was the most prevalentsensory deception, followed by ∗visual hallucina-tions, ∗auditory hallucinations, ∗tactile hallucina-tions, and ∗compound hallucinations. Recurrenthallucinatory episodes were most prevalent dur-ing the first decade of widowhood. Their meanduration varied from several years to decades inindividuals above 40 years of age. The incidenceof bereavement hallucinations among individu-als under the age of 40 was significantly lower,as was the incidence among childless widowedpersons, and among those who reported hav-ing had an unhappy marriage. Bereavement hal-lucinations are often described as being bene-ficial in nature, hence the tendency to classifythem as ∗benign hallucinations. However, theycan also be a source of considerable distress.The term pathological grief reaction has beenproposed to denote the occurrence of halluci-

natory symptoms that have no bearing on thedeceased individual. The American psychiatristLloyd A. Wells describes two individuals with apathological grief reaction who reported visualhallucinations reminiscent of ∗autoscopic phe-nomena. As to the pathophysiology of bereave-ment hallucinations it has been suggested thatthese may fall into either the class of ∗perceptualrelease phenomena, or the class of ∗reperceptions.As a footnote to the literature on bereavementhallucinations, it is worth mentioning that theAmerican-Canadian neuropsychologist MichaelA. Persinger (b. 1945) found a positive correla-tion between corpuscular radiation from the Sun(i.e. solar wind), and the incidence of bereave-ment hallucinations. Persinger interpreted thisremarkable finding as circumstantial evidence forthe involvement of temporal magnetic-mediatedmicroseizures in their mediation. Conceptually aswell as phenomenologically (and perhaps patho-physiologically as well), bereavement hallucina-tions would seem to display some overlap withhallucinations occurring in ∗Charles Bonnet syn-drome (CBS). In parapsychology, as well as invarious religions, it is not uncommon to des-ignate bereavement hallucinations as a formof communication with deceased individuals or∗apparitions. They are therefore referred to aspost-bereavement apparitions. To suspend judge-ment on the issue of whether such apparitionsexist or not, the neutral term ∗idionecrophanyhas been proposed to denote any sensoryexperience involving an alleged contact withthe dead.

ReferencesBaethge, Chr. (2002). Grief hallucinations: True

or pseudo? Serious or not? An inquiry intopsychopathological and clinical features of acommon phenomenon. Psychopathology, 35,296–302.

Persinger, M. (1988). Increased geomagneticactivity and the occurrence of bereavementhallucinations: Evidence for melatonin-mediated microseizuring in the temporal lobe?Neuroscience Letters, 88, 271–274.

Rees, W.D. (1971). The hallucinations of widow-hood. British Medical Journal, 4, 37–41.

Wells, L.A. (1983). Hallucinations associatedwith pathologic grief reaction. Journal ofPsychiatric Treatment and Evaluation, 5,259–261.

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B Berrios’s Definition of Hallucinations

Berrios’s Definition of Hallucinations

In 2005, the British psychiatrist and historian ofpsychiatry German E. Berrios defined halluci-nations as follows. “Hallucination is the genericname for a class of utterances reporting subjec-tive experiences (putatively) perceptual in naturewhich occur in the (arguably) absence of an ade-quate external stimulus. The said reports mayimplicate all sensory modalities giving rise to so-called hallucinations of vision, audition, touch,olfaction, taste and coenesthesia.”

ReferenceBerrios, G.E. (2005). On the fantastic apparitions

of vision by Johannes Müller. History of Psy-chiatry, 16, 229–246.

Beta-Blockers and Hallucinations

Beta-blockers are also referred to as β-blockers,beta-adrenergic blockers, beta-antagonists, beta-adrenergic antagonists, beta-adrenergic blockingdrugs, and beta-adrenoceptor antagonists. Allthese names are used to denote a group of chem-ical substances that have the capacity to modu-late the activity of the sympathetic nervous sys-tem by blocking the action of endogenous cate-cholamines such as adrenaline and noradrenalineupon beta-adrenergic receptors. In biomedicine,beta-blockers are prescribed for a broad rangeof indications, including glaucoma, cardiovascu-lar conditions such as congestive heart failure,cardiac arrhythmia, and mitral valve prolapse, aswell as such CNS conditions as migraine, tremor,and akathisia. Although hallucinations have fordecades been reported as a possible adverse effectoccurring in individuals using beta-blockers –more specifically, the group of lipophilic beta-blockers – the results from empirical studiesare ambiguous in this respect. While it is truethat case reports involving ∗visual hallucina-tions, ∗formicative hallucinations, ∗verbal audi-tory hallucinations, ∗musical hallucinations, andother ∗sensory deceptions in association withthe use of beta-blockers have been published, itshould be borne in mind that propranolol, his-torically the first beta-blocker available in theUnited States, was at one time considered analternative for the use of antipsychotic agents

in the treatment of individuals with a clinicaldiagnosis of ∗schizophrenia. Beta-blocker ther-apy did not live up to this expectation, butthe claim that these substances are more thanoccasionally associated with hallucinatory activ-ity would seem to be ill founded. Insomnia, lively∗dreams, and ∗nightmares, on the other hand,have been reported quite frequently by users ofbeta-blockers.

ReferencesKo, D.T., Hebert, P.R., Coffey, Chr.S., Cur-

tis, J.P., Foody, J.A.M., Sedrakyan, A.,Krumholz, H.M. (2004). Adverse effects of β-blocker therapy for patients with heart failure.A quantitative overview of randomized trials.Archives of Internal Medicine, 164, 1389–1394.

Roberts, E., Amacher, P., eds. (1978). Propranololand schizophrenia. New York, NY: Alan R.Liss.

Bicameral Mind Theory

The expression bicameral mind is indebted tothe Latin words bi (two) and camera (room). Itrefers to the purported existence of two virtualrooms or compartments within the mind. Thebicameral mind theory was formulated duringthe 1960s, and subsequently published in bookform in 1976 by the American psychologist JulianJaynes (1920–1997). It involves the hypothesisthat ontogenetically, modern human conscious-ness might well originate from the breakdownof a primitive bicameral ‘mind-space’, and thathallucinations can therefore be interpreted as asign of regression to that prior evolutionary stage.Jaynes speculates that the pre-conscious mental-ity characteristic of individuals in ancient cultureswas consciously aware of endogenously medi-ated percepts, but not of their being mediated bythe mind’s own ‘second chamber’. In this sense,Jaynes’ theory may be seen as a conceptual pre-cursor of today’s ∗inner speech models of hallu-cinatory experience, notably the ∗defective corol-lary discharge model, which seeks to explain themisattribution of endogenous linguistic signals inindividuals with ∗verbal auditory hallucinations(VAH) in terms of a failure in corollary discharge(or ‘feedforward’) signal that normally allows thebrain’s speech perception areas to recognize anincoming signal as ‘its own’. Jaynes illustrates hisbicameral mind thesis with numerous references

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Bilateral Hallucination B

to Homer (c. 750–c. 700 BC), who depicted theheroes of the Iliad as individuals devoid of self-awareness as we know it today. As a consequence,according to Jaynes, these individuals seldomreferred to themselves, and seemed to lack the lin-guistic tools to express their own strivings andemotions. As Jaynes maintains, “In distinctionto our own subjective conscious minds, we cancall the mentality of the Myceneans a bicameralmind. Volition, planning, initiative is organizedwith no consciousness whatever and then ‘told’ tothe individual in his familiar language, sometimeswith the visual aura of a familiar friend or author-ity figure or ‘god’, or sometimes as a voice alone.The individual obeyed these hallucinated voicesbecause he could not ‘see’ what to do by him-self.” Jaynes interpretes Homer’s narrative style asa sign that the mind of the Myceneans was rad-ically different from ours, i.e. that it lacked ourpresent introspective, self-reflective nature, ren-dering it incapable of unmasking hallucinationsas phenomena from within. As Jaynes suggests,“What triggered these hallucinations? I suggest itwas even the slight stress of making a decision in anovel circumstance, whereas in ourselves in mod-ern times the stress threshold for such triggeringof a verbal hallucination is much higher. The rea-son they are so prevalent in all cultures today, inthe hospital patients and homeless. . ., in childrenand speechless quadriplegics, is because they wereonce the genetic basis of this ancient mentality,and the genes for this potentiality are still withus today. Verbal hallucinations, we think, evolvedalong with the evolution of language during thelate Pleistocene as the response part of the brainregister of all admonitory information. Its sur-vival value at first was simply to direct an individ-ual in various long-term tasks, which cued theiroccurrence. By 9000 BC, such voices were calledwhat we call gods. The bicameral mind produceda new kind of social control that allowed agri-cultural civilizations to begin.” Jaynes’ bicameralmind hypothesis has been discarded and defendedfor many different reasons, but scientific interestin his work has been re-awakened by the consis-tent findings of right-sided activation patterns inthe brain, as retrieved with the aid of neuroimag-ing studies in individuals with verbal auditoryhallucinations.

ReferencesDierks, T., Linden, D.E.J., Jandl, M.,

Formisano, E., Goebel, R., Lanfermann,

H., Singer, W. (1999). Activation of Heschl’sgyrus during auditory hallucinations. Neuron,22, 615–621.

Jaynes, J. (1976). The origin of consciousness in thebreakdown of the bicameral mind. Boston, MA:Houghton Mifflin Company.

Kuijsten, M., ed. (2006). Reflections on the dawnof consciousness: Julian Jaynes’s bicameralmind theory revisited. Henderson, NV: JulianJaynes Society.

Sher, L. (2000). Neuroimaging, auditory hallu-cinations, and the bicameral mind. Journal ofPsychiatry & Neuroscience, 25, 239–240.

Sommer, I.E.C., Aleman, A., Kahn, R.S. (2003).Left with the voices or hearing right? Later-alization of auditory verbal hallucinations inschizophrenia. Journal of Psychiatry and Neu-roscience, 28, 17–18.

Bidwell’s Ghost

Also referred to as ∗Purkinje afterimage. Theeponym Bidwell’s ghost refers to the British physi-cist Shelford Bidwell (1848–1909). It is usedto denote a ∗negative afterimage that appearssecond in a temporal sequence of ∗afterimagesresulting from exposure to a brief light stimulus.Like other negative afterimages, Bidwell’s ghosttakes on a hue complementary to that of the orig-inal optical stimulus. Bidwell’s ghost is commonlyclassified as a ∗physiological illusion.

ReferenceBrown, J.L. (1965). Afterimages. In: Vision and

visual perception. Edited by Graham, C.H.New York, NY: Wiley.

Bilateral Auditory Hallucination

see Bilateral hallucination.

Bilateral Hallucination

Also known as bilateral auditory hallucination.Both expressions are indebted to the Latin wordsbi (two) and latus (side). The term bilateral hal-lucination translates roughly as ‘two-sided hal-lucination’. The term is used mainly with refer-

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B Bilateral Scotoma

ence to hallucinations occurring in the auditorymodality. In a loose sense, it is used to denotean ∗auditory hallucination subjectively localizedas coming either from both sides of the head, orfrom an indefinite location. In a more restrictedsense, the term bilateral hallucination has beenused since the late 19th century to denote anauditory hallucination that has a different qual-ity and/or content for each side of the head.Thus the affected individual may hear pleasur-able and encouraging voices in the right ear,and abusive, threatening voices in the left ear.Or the affected individual may hear a femalevoice in the right ear, and a male voice in theleft. The French alienist Jacques Joseph-ValentinMagnan (1835–1916) considers bilateral halluci-nations in the restricted sense as indicative of thedual nature and functional independence of thecerebral hemispheres. On the basis of four indi-viduals he studied, Magnan speculates that bilat-eral hallucinations may not be dependent uponperipheral lesions of the auditory apparatus, butrather upon the involvement of “the cortical sen-sorial centres”. The term bilateral hallucinationis used in opposition to the term ∗unilateralhallucination.

ReferencesBlom, J.D., Sommer, I.E.C. (2009). Auditory hal-

lucinations. Cognitive and Behavioral Neurol-ogy (in press).

Lewis, W.B. (1885). Magnan on certain peculiarfeatures in bilateral hallucinations. Brain, 7,562–564.

Bilateral Scotoma

see Bilateral spectrum.

Bilateral Spectrum

Also known as bilateral scotoma. The termbilateral spectrum comes from the Latin wordsbi (two), latus (side), and spectrum (image,∗apparition). It is used to denote a relatively rare∗fortification spectrum (i.e. a ∗scintillating sco-toma), occurring in the context of a ∗migraineaura, whose development is exactly synchronizedin the two hemifields. As a result, the bilateralspectrum may present in the form of a single

Fig. 3 Sir William Richard Gowers

central or pericentral spectrum. Various types ofbilateral spectra (including the ∗rainbow spec-trum) were described in 1904 by the Britishneurologist Sir William Richard Gowers (1845–1915). Bilateral negative scotomata (i.e. regionsof loss of vision) occasionally develop into tran-sient ∗blindness. In those rare cases where the tac-tile cortex is affected as well, a total loss of body-sense (i.e. ∗acenesthesia) may be experienced. Asthe involvement of both hemifields in fortificationspectra is extremely rare, and cannot be explainedwith recourse to current hypotheses involving themediation of these phenomena in a single cerebralhemisphere, the British neurologist Oliver WolfSacks (b. 1933) notes that “The existence of suchscotomata poses very difficult problems to thosewho postulate a local, unilateral process as thebasis of migraine auras.”

ReferencesGowers, W.R. (1904). Subjective sensations of

sight and sound: Abiotrophy, and other lectures.Philadelphia, PA: P. Blakiston’s Son & Co.

Sacks, O. (1992). Migraine. Revised and expanded.New York, NY: Vintage Books.

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Black Patch Delirium B

Binasal Hemianopia

see Hemianopia.

Binocular Diplopia

see Diplopia.

Binocular Illusion

The term binocular illusion is indebted to theLatin words bi (twice) and oculus (eye). It isused to denote an ∗illusion that depends for itsmediation on a coordinated effort of the twoeyes. Two examples of binocular illusions arethe ∗hole-in-the-hand and the ∗floating-fingerillusion.

ReferenceGurney, R.W. (1938). A binocular illusion.

Nature, 141, 1060.

Binswanger and Siemerling’s Definition ofHallucinations

In 1907 the German psychiatrists Otto Bin-swanger (1852–1929) and Ernst Siemerling(1857–1931) defined hallucinations as follows.“We designate hallucinations as sense perceptionswhich, without stimulation of the sense organinvolved by an external object, occur as a mereconsequence of internal stimuli.”

ReferenceBinswanger, O., Siemerling, E. (1907). Lehrbuch

der Psychiatrie. Zweite vermehrte Auflage.Jena: Verlag von Gustav Fischer.

Bio-Introscopy

see Eyeless vision.

Bipartition Fantasy

see Sensed presence.

Bipolar Disorder and Hallucinations

see Mood disorder and hallucinations.

Birgitta Birgersdotter

see Bridget of Sweden.

Birgitta of Vadstena

see Bridget of Sweden.

Bistable Figure

see Ambiguous illusion.

Bitemporal Hemianopia

see Hemianopia.

Black Hemianopia

see Hemianopia.

Black Patch Delirium

Also known as black patch psychosis, black patchsyndrome, black patch disease, and cataract delir-ium. The term black patch delirium was intro-duced in 1958 by the American philosopher, psy-chiatrist, and thanatologist Avery D. Weisman(b. 1914?), and his colleague Thomas Paul Hack-ett, Jr. (1928–1988) to denote an acute confu-sional state dominated by ∗complex visual hal-lucinations in individuals wearing a bilateral eyepatch following cataract surgery. Although dif-ferent in name, similar hallucinatory and deliri-ous states occurring after cataract surgery havebeen described since around 1900. As far as thevisual hallucinations are concerned, black patchdelirium appears to display a certain phenomeno-logical overlap with ∗Charles Bonnet syndrome.

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B Black Patch Disease

However, the two syndromes would seem to dif-fer with respect to the presence of additionalpsychotic or delirious symptoms concomitant toblack patch delirium, and the absence of any suchadditional signs or symptoms in Charles Bon-net syndrome. Pathophysiologically, the halluci-nations occurring in the context of black patchdelirium tend to be regarded as ∗deafferentiationphenomena or ∗perceptual release phenomenacomparable to the hallucinations occurring inthe context of ∗sensory deprivation. Etiologically,ample attention has also been drawn to the pos-sible influence of toxic substances such as anaes-thetics, therapeutics, illicit drugs, and alcohol, toco-morbid disorders, and to psychological mech-anisms such as homesickness, feelings of distress,and feelings of vulnerability. The nosological sta-tus of black patch delirium has been contestedby some authors on the grounds that, in a phe-nomenological and pathophysiological sense, itdoes not seem to differ from ∗delirium proper orfrom senile forms of ∗psychosis. Today the termblack patch delirium is used only infrequently inthe literature. As today’s state-of-the-art postop-erative care of cataract patients is directed at theprevention of delirium, it may well be that thetrue incidence of disorders formerly designatedas black patch delirium is also somewhat on thewane.

ReferencesJackson, C.W. (1969). Clinical sensory depri-

vation: A review of hospitalized eye-surgerypatients. In: Sensory deprivation: Fifteen yearsof research. Edited by Zubek, J.P. NewYork, NY: Appleton-Century-Crofts.

Rabins, P.V. (1991). Psychosocial and manage-ment aspects of delirium. International Psy-chogeriatrics, 3, 319–324.

Weisman, A.D., Hackett, T.P. (1958). Psychosisafter eye surgery. New England Journal ofMedicine, 258, 1284–1289.

Black Patch Disease

see Black patch delirium.

Black Patch Psychosis

see Black patch delirium.

Black Patch Syndrome

see Black patch delirium.

Blake, William (1757–1827)

A British poet, painter, and printmaker whofrom childhood onwards experienced ∗dreamsand ∗visions depicting ∗apparitions and meta-physical scenes. At the age of 4, he claimed to haveseen the face of God “put his head to the win-dow”, and at the age of around 10 he saw “a treefilled with angels, bright angelic wings bespan-gling every bough like stars”. The visions recurredthroughout his life, along with ∗verbal auditoryhallucinations which he attributed to his deceasedbrother (with whom he continued to conversedaily), and to angels, Archangels, etc. who dic-tated poems to him, and infused the themes ofhis visual art. Retrospective diagnosis is a deli-

Fig. 4 William Blake. Engraving (1808) by LuigiSchiavonetti, after a portrait (1807) by ThomasPhillips. Source: Collection of G.E. Bentley, Jr

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Blake, William B

Fig. 5 Ezekiel’s Wheels (c. 1803–1805). Watercolour by William Blake. Source: Museum of Fine Arts,Boston

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B Blank Hallucination

cate issue, but it has been suggested that Blakemay have suffered from bipolar disorder or from∗ecstatic aurae occurring in the context of tempo-ral lobe epilepsy.

ReferencesBentley, Jr., G.E., (2001). The stranger from

Paradise. A biography of William Blake.London: Yale University Press.

Buckley, P.J. (2005). William Blake (1757–1827). American Journal of Psychiatry, 162,866.

Blank Hallucination

The term blank hallucination was introducedin or shortly before 1961 by the German-American psychoanalyst Max M. Stern (1895–1982) to denote a collection of simple halluci-natory phenomena such as the sense that oneis floating in space, changes in equilibrium, per-ceived changes in body size (i.e. ∗macro- and∗microsomatognosia), hazy blurrings of percep-tion, and so-called cloudlike phenomena, as wellas some types of ∗formed hallucinations. InStern’s own words, “Blank hallucinations arestereotyped sensory perceptions without appro-priate external stimuli. Lacking any contentrelated to persons, objects, or events, they areclose to elementary hallucinations as which wedesignate such unformed perceptions as sparks,lightning streaks, cloudlike phenomena, etc. Theydiffer in intensity, frequency, and duration, rang-ing from formes frustes like hazy blurring ofperception, to full hallucinations. They may lasta few seconds, or minutes, hours, or months.”In conformity with the psychoanalytic theory,Stern suggests that blank hallucinations oftenmake their first appearance in childhood, primar-ily around the oedipal phase. Moreover, he main-tains that blank hallucinations can recur through-out the individual’s life in response to stress orfrustration, either as an accompanying symp-tom of emotional states such as anger or rage,or as a ∗hypnagogic phenomenon before fallingasleep. Stern conceptualizes blank hallucinationsas a collection of early defense mechanisms thatmimic the soothing experience of suckling at thebreast. The term blank hallucination is sometimesused in a wider sense to include the ∗Isakowerphenomenon, the ∗dream screen, and abstractperceptions.

ReferencesCampbell, R.J. (1996). Psychiatric dictionary. Sev-

enth edition. Oxford: Oxford University Press.Stern, M.M. (1961). Blank hallucinations:

Remarks about trauma and perceptualdisturbances. International Journal of Psycho-Analysis, 42, 205–215.

Tarbox, R. (1967). Blank hallucinations in the fic-tion of Poe and Hemingway. American Imago,24, 312–343.

Bleuler, Paul Eugen (1857–1939)

A Swiss psychiatrist, well known for his innova-tive work in general psychiatry, and, more specifi-cally, for his conceptualization of ∗schizophrenia.Bleuler’s life-long devotion to psychiatric careand research was probably inspired in great partby his sister, who suffered from a chronic psy-chotic disorder with catatonic features, and whoresided at the Burghölzli Hospital in Zollikonwith Bleuler and his family. Bleuler himself expe-rienced ∗synaesthesias of the phoneme-colourtype (i.e. hallucinated colours in association withspoken words).

ReferenceBleuler, E., Lehmann, K. (1881). Zwangsmässige

Lichtempindungen durch Schall und verwandteErscheinungen auf dem Gebiet der anderen Sin-nesempfindungen. Leipzig: Fues’s Verlag.

Bleuler’s Definition of Hallucinations

In his classic textbook of psychiatry, the Swisspsychiatrist Paul Eugen Bleuler (1857–1939)defines hallucinations as follows. “Hallucinationsare perceptions without a corresponding stimu-lus externally: everything that one perceives canalso become a hallucination, in such a way, thatthe various elements can be combined freely; ahallucinated lion can have wings, a human figurecan be composed out of the properties of variouspersons. Moreover, pathological brain functionsevidently evoke internal perceptions that were notavailable before.”

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Blindsight B

Fig. 6 Eugen Bleuler

ReferenceBleuler, E. (1923). Lehrbuch der Psychiatrie.

Vierte Auflage. Berlin: Verlag von JuliusSpringer.

Bleuler’s Definition of Illusions

In his classic textbook of psychiatry, the Swisspsychiatrist Paul Eugen Bleuler (1857–1939)defines ∗illusions as follows. “Illusions are mor-bidly altered genuine perceptions: The striking ofthe hour is perceived as a term of abuse, or as apromise; the clutched hand is rejected as a cold‘death hand’; people are seen as standing on theirheads, instead of the white colour of a face a blackone is seen, instead of a nurse a waitress.”

ReferenceBleuler, E. (1923). Lehrbuch der Psychiatrie.

Vierte Auflage. Berlin: Verlag von JuliusSpringer.

Blindness and Hallucinations

Visual hallucinations occurring in individu-als with impaired vision have been reportedsince ancient times. Perhaps the best-knownhistorical example is the description of CharlesLullin’s ∗visual hallucinations, as rendered byhis grandson Charles Bonnet (1720–1792), andthereafter commonly referred to as the ∗CharlesBonnet syndrome. Visual hallucinations are alsoknown to occur, albeit less frequently, in partialvisual field defects such as ∗hemianopia (result-ing in so-called ∗hemianopic hallucinations),∗quadrantanopsia, central scotoma, and∗amblyopia. See also the entries Ictal blindness,Hypnotic blindness, Hysterical blindness, Changeblindness, Inattentional blindness, and Negativehallucination.

ReferenceFreiman, Th.M., Surges, R., Vougioukas, V.I.,

Hubbe, U., Talazko, J., Zentner, J., Honeg-ger, J., Schulze-Bonhage, A. (2004). Complexvisual hallucinations (Charles Bonnet syn-drome) in visual field defects following cerebralsurgery. Report of four cases. Journal of Neuro-surgery, 101, 846–853.

Blindsight

A term introduced in 1974 by the British neu-ropsychologists Lawrence Weiskrantz (b. 1926) etal. to denote residual vision in cases of corticalblindness, especially when there is a correspond-ing lack of awareness of the visual capacity on thepart of the affected individual. Cortical blindnessis attributed to lesions of the primary visual cor-tex (also referred to as V1, area 17, area OC, andstriate cortex). The resulting ∗scotomata, vary-ing in size from a relatively minor area to theentire hemifield (as in ∗hemianopia) are perceivedwithin the visual field contralateral to the CNSlesion at hand. Individuals with lesions to V1 arenot consciously aware of any visual stimuli pre-sented within the scotomatous region. However,during the 1970s Weiskrantz et al. demonstratedthat some perceptual information may neverthe-less be detected by individuals suffering from cor-tical blindness. The geniculo-striate pathway, pro-jecting from the retina towards V1, is the largest

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route into striate cortex. But it is not the onlyone. Empirical research has indicated that thereare at least six other branches of the optic nervethat take a different route into striate cortex, andthat some routes may even project into the extras-triate cortex. The residual perception of visualstimuli by individuals with blindsight is attributedto these latter pathways, i.e. the pathways pro-jecting into the extrastriate and remaining stri-ate cortex while bypassing the geniculo-striatesystem.

ReferenceWeiskrantz, L. (1986). Blindsight. A case study

and implications. Oxford: Clarendon Press.

Blind Spot

Also known as Mariotte’s spot, physiological sco-toma, physiological blind spot, and punctum cae-cum. All five terms are used to denote the phys-iological ‘hole’ existing in each monocular fieldof vision that corresponds morphologically withthe optic disc, i.e. the region of the retina wherethe optic nerve ending is located, and where, asa consequence, no photoreceptors are present.Although humans and other vertebrates are blindto objects and visual stimuli in this part of thevisual field, the missing perceptual informationis automatically compensated for by the othereye in binocular vision, and ‘filled in’ by thebrain (or mind, in a dualist reading) in monoc-ular vision. The eponym Mariotte’s spot refers tothe French physicist and priest Edme Mariotte (c.1620–1684), who in 1666 was the first to docu-ment the existence of the blind spot. In a broaderreading, the term blind spot is used to denoteany scotomatous region existing within the visualfield. The so-called ‘filling-in’ of the blind spot isclassified as a ∗fiction illusion.

ReferencesGregory, R.L. (1991). Putting illusions in their

place. Perception, 20, 1–4.Mariotte, E. (1717). Oeuvres de Mr. Mariotte,

de l’Académie Royale des Sciences; divisées endeux tomes. Seconde tome. Leide: Pierre Van-der Aa.

Blue-Field Entoptic Phenomenon

Also known as Scheerer’s phenomenon, after theGerman ophthalmologist Richard Scheerer. Bothterms refer to an ∗entoptic phenomenon charac-terized by tiny bright dots moving quickly andsemi-randomly across the visual field, especiallywhen viewed against a background of brightblue light. The blue-field entoptic phenomenonis a physiological effect attributed to the move-ment of lymphocytes (or erythrocytes, in a differ-ent reading) within the capillaries overlying theretina. The sudden acceleration of these brightdots is considered synchronous with the systole.Although the phenomenon had been described byat least a dozen authors, it was Scheerer who in1924 first drew clinical attention to it. The blue-field entoptic phenomenon should not be con-fused with ∗muscae volitantes.

ReferencesPriestly, B.S., Foree, K. (1955). Clinical signifi-

cance of some entoptic phenomena. Archivesof Ophthalmology, 53, 390–397.

Scheerer, R. (1924). Die entoptische Sichtbarkeitder Blutbewegung im Auge und ihre klinischeBedeutung. Klinisches Monatsblatt für Augen-heilkunde, 73, 67–107.

Sinclair, S.H., Azar-Cavanaugh, M., Soper, K.A.,Tuma, R.F., Mayrovitz, H.N. (1989). Investi-gation of the source of the blue field entopticphenomenon. Investigative Ophthalmology andVisual Science, 4, 668–673

Blue Vision

see Cyanopsia.

Bodily Hallucinated Smell

see Intrinsic olfactory hallucination.

Bodily Hallucination

Also known as body sensation hallucination.Both terms are used interchangeably as umbrellaterms for the notions of ∗tactile hallucination

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and ∗somatic hallucination. In other words, bothterms refer to a hallucination experienced in thesomatosensory modality that may appear to stemeither from an extracorporeal or an intracorpo-real source. The 1982 Manual for the Assessmentand Documentation of Psychopathology (AMDP)defines bodily hallucinations as “unfounded tac-tile and somatic perceptions including touch,kinesthesic, pain, pressure, and thermic phenom-ena.” As the authors of the AMDP maintain,“Many such hallucinations have the characterof being produced by external forces, e.g. thepatient has the feeling of being abused sexuallyor by electricity or ‘rays.’ ” Somewhat unusu-ally, the AMDP employs the term ∗coenesthetichallucination as a synonym for the term bodilyhallucination.

ReferenceGuy, W., Ban, T.A., eds. (1982). The AMDP-

system: Manual for the assessment and docu-mentation of psychopathology. Berlin: Springer.

Body Dysmorphic Disorder (BDD) andHallucinations

The term body dysmorphic disorder was intro-duced in 1994 in the American Psychiatric Asso-ciation’s Diagnostic and Statistical Manual ofMental Disorders, Fourth Edition (DSM-IV) todenote a disorder characterized by an imag-ined defect in appearance, or excessive concernor preoccupation with a slight physical defect.Although in clinical practice BDD can be diag-nosed in the absence of any overt illusory or hal-lucinatory symptoms, in some cases an organicsomatosensorial disturbance can be found toexist. It has been suggested that this disturbancemay arise as a consequence of aberrant neu-rophysiological activity in the parieto-occipitalregions representing the body schema. Suchsomatosensorial disturbances may entail ∗bodyschema illusions such as ∗microsomatognosia,∗macrosomatognosia, ∗kinaesthetic hallucina-tions, and ∗proprioceptive hallucinations. In diag-nostic classifications such as the DSM, BDD isclassified as a somatoform disorder. A conceptualprecursor of BDD was described in 1886 by theItalian psychiatrist Enrico Morselli (1852–1929).He called this nosological category dysmorpho-phobia.

ReferencesAmerican Psychiatric Association (1994). Diag-

nostic and statistical manual of mental disor-ders. Fourth edition. Washington, DC: Amer-ican Psychiatric Association.

Morselli, E., Jerome, L. (2001). Dysmorpho-phobia and taphephobia: Two hitherto unde-scribed forms of insanity and fixed ideas.History of Psychiatry, 12, 103–107.

Yaryura-Tobias, J.A., Neziroglu, F., Torres-Gallegos, M. (2002). Neuroanatomical cor-relates and somatosensorial disturbances inbody dysmorphic disorder. CNS Spectrum, 7,432–434.

Body Photism

A term used to denote a type of ∗photism (i.e.a hallucinated patch of light) consisting of alight emanating from one’s own body. Body pho-tism has occasionally been reported in associa-tion with ∗out-of-body experiences. It should notbe confused with the parapsychological notion ofthe ∗luminous phenomenon.

ReferenceArzy, S., Idel, M., Landis, Th., Blanke, O. (2005).

Speaking with one’s self. Autoscopic phenom-ena in writings from the Ecstatic Kabbalah.Journal of Consciousness Studies, 12, 4–30.

Body Schema Disturbance

see Body schema illusion.

Body Schema Illusion

Also known as body schema disturbance,∗somato-éidolie, ∗disorder of corporeal aware-ness, illusion of corporeal transformation, andillusion of corporeal displacement. All sixterms are used to denote an illusory change inthe size, relation, position, and/or movementof one’s own body parts. Some examples ofbody schema illusions are ∗kinaesthetic hal-lucinations, ∗proprioceptive hallucinations,∗microsomatognosia, ∗macrosomatognosia,∗splitting of the body image, ∗aschematia, the

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∗rubber hand illusion, the ∗illusory displace-ment of limbs, the ∗illusory arm extension, the∗Pinocchio illusion, ∗Aristotle’s illusion, andthe ∗floating finger illusion. In clinical prac-tice, the majority of the body schema illusionsaffect only a part (or various parts) of thebody. Rare instances where the whole body isinvolved are referred to as whole body schemaillusion. Pathophysiologically, body schemaillusions are associated primarily with lesionsaffecting those parts of the parietal lobe orparieto-occipital region involved with bodilyrepresentations and/or representations of move-ment. Etiologically, they are associated primarilywith paroxysmal neurological disorders such asmigraine and epilepsy. It has been speculatedthat the topological distribution of symptoms inbody schema illusions reflects the extension ofthe representation of body parts in the brain’ssensory maps. As noted by the British neurologistMacdonald Critchley (1900–1997), these sensorymaps would seem to extend far beyond the pari-etal lobe. As Critchley maintains, “Positive andnegative modifications of corporeal awarenessmay be met with in lesions at all levels of theneuraxis, but the parietal lobes occupy a specialand important role in this problem. More partic-ularly, the parietal region of the minor hemisphereis commonly regarded as being of special signif-icance, and there has been a tendency to speakof ’localization’ or ‘representation’ of the bodyimage within this particular region of the brain.This mode of thinking is probably a dangerousoversimplification.” In 1963, Critchley proposedthe term corporeal awareness as an alternativefor the expressions body image and body schema,arguing that these latter terms “fail to indicatethe combined properties of a concept and apercept”. As a corollary, Critchley designatesbody schema illusions as ‘disorders of corporealawareness’.

ReferencesCritchley, M. (1965). Disorders of corporeal

awareness in parietal disease. In: The body per-cept. Edited by Wapner, S., Werner, H. NewYork, NY: Random House.

Leker, R.R., Karni, A., River, Y. (1996). Micro-somatoagnosia: Whole body schema illusionas part of an epileptic aura. Acta NeurologicaScandinavica, 94, 383–385.

Podoll, K., Robinson, D. (2000). Macrosomatog-nosia and microsomatognosia in migraine

art. Acta Neurologica Scandinavica, 101,413–416.

Body Sensation Hallucination

see Bodily hallucination.

Bonnet Syndrome

see Charles Bonnet syndrome (CBS).

Border

see Corona phenomenon.

Borderline Personality Disorder (BPD)and Hallucinations

Borderline personality disorder (BPD) is alsoknown as emotional regulation disorder (ERD),emotional intensity disorder (EID), and unsta-ble personality disorder (UPD). The expressionborderline personality disorder evolved out of theterm borderline neurosis, which was introducedin 1938 by the American neurologist and psychi-atrist Adolph Stern (1878–1958), the first Ameri-can psychoanalyst who was analyzed by SigmundFreud (1856–1939) himself. Stern introduced theexpression borderline neurosis to designate adiagnostic category characterized by neuroticpersonality traits as well as psychotic symptomssuch as delusions and – infrequently occurring –hallucinations. Thus the name borderline neuro-sis used to refer to the conceptual middle groundbetween the categories neurosis and ∗psychosis.Today the name BPD refers to a personality dis-order characterized by a long-standing patternof instability in various areas, including mood,interpersonal relationships, and self-image. Clin-ically, BPD is associated with extreme distress,harmful behaviour, and social and/or occupa-tional dysfunctioning. The point prevalence ofBPD has been reported as lying around 2% inthe community population. In 1980, the diag-nostic category BPD made its debut in the thirdedition of the American Psychiatric Associa-tion’s Diagnostic and Statistical Manual of Men-

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Brainstem Auditory Hallucinosis B

tal Disorders (DSM-III). As the DSM-III states,“During periods of extreme stress transient psy-chotic symptoms of insufficient severity or dura-tion to warrant an additional diagnosis mayoccur”. As a consequence, longer-lasting hal-lucinatory states occurring in individuals witha clinical diagnosis of BPD have often beenreferred to with somewhat ambiguous termslike ∗quasi-hallucination, ∗pseudohallucination,∗dissociative phenomenon, and micropsychoticepisode. As the Australian psychiatrists LeslieYee et al. point out, this practice has for along time obscured the regular occurrence of∗hallucinations proper – as well as the occasionaloccurrence of ∗persistent hallucinosis – in indi-viduals with a clinical diagnosis of BPD. Yee etal. draw attention to the growing literature on∗auditory, ∗visual, and ∗olfactory hallucinationsin association with BPD, suggesting that a sig-nificant proportion of the individuals with BPDmay experience hallucinations that are not tran-sient but ongoing, not circumscribed but per-vasive, and phenomenologically indistinguishablefrom those in individuals diagnosed with one ofthe major psychotic disorders.

ReferencesAmerican Psychiatric Association (1980). Diag-

nostic and statistical manual of mental disor-ders. Third edition. Washington, DC: Ameri-can Psychiatric Association.

Stern, A. (1938). Psychoanalytic investigationof and therapy in the borderline group ofneuroses. Psychoanalytic Quarterly, 7, 467–489.

Yee, L., Korner, A.J., McSwiggan, S., Meares,R.A., Stevenson, J. (2005). Persistent halluci-nosis in borderline personality disorder. Com-prehensive Psychiatry, 46, 147–154.

Bottom-Up Hypothesis

A generic name for a group of hypotheses thatattribute the mediation of hallucinations primar-ily to a disorder of the data-driven processing ofperceptual information, such as may occur in thecontext of ∗deafness, ∗blindness (i.e. the ∗CharlesBonnet syndrome), ∗sensory deprivation, or dys-function of the primary sensory cortex. The termbottom-up hypothesis is used in opposition tothe term ∗top-down hypothesis. The latter termrefers to a group of hypotheses that attribute the

mediation of hallucinations primarily to a dis-order of the conceptual processing of perceptualinformation.

ReferenceAleman, A., Larøi, F. (2008). Hallucinations.

The science of idiosyncratic perception.New York, NY: American PsychologicalAssociation.

Bouguer’s Halo

see Ulloa circle.

Bouncing Vision

see Oscillopsia.

Braille Hallucination

see Hallucination in braille.

Brain-Damage-Induced Synaesthesia

A term used to denote a type of ∗synaesthesiafalling into the class of the ∗non-idiopathicsynaesthesias. Etiologically, brain-damage-induced synaesthesias are associated primarilywith lesions affecting the optic nerve, anteriorportions of the brain, or the brainstem.

ReferenceCytowic, R.E. (2002). Synesthesia. A union of the

senses. Second edition. Cambridge, MA: MITPress.

Brain Light

see Eigengrau.

Brainstem Auditory Hallucinosis

A term used to denote a hallucinatory state char-acterized by ∗auditory hallucinations which are

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B Brainstem Hallucination

attributed to aberrant neurophysiological activ-ity in the brainstem. The concept of brain-stem auditory hallucinosis is analogous to thatof ∗peduncular hallucinosis, except for the factthat peduncular hallucinations are believed tobe mainly visual in nature. Both concepts envis-age the top of the brainstem and its surround-ing structures as the primary source for cer-tain types of hallucinations. Although relativelyscarce, speculations about the involvement of thebrainstem in the mediation of auditory hallu-cinations can be found in the literature fromthe late 19th century onwards. The first empir-ical study providing empirical corroboration forthis thesis was published in 1986 by the Amer-ican neurologists George D. Cascino and Ray-mond D. Adams. Cascino and Adams reportedon three individuals suffering from ∗nonverbalauditory hallucinations in the form of buzzing,clanging, machine noises, the sound of bells chim-ing, organ tones, and so on, who showed clini-cal, radiologic (CT), and in one case pathologicsigns of lesions of the tegmentum of the ponsand lower midbrain, but no signs of structurallesions in any other part of the auditory system.In all three cases the hallucinations were contin-uous in nature, and associated with hearing lossdue to central lesions. As the authors speculate,these findings suggest that the hallucinations athand might perhaps be best regarded as ∗releasephenomena. As a nosological category, brainstemauditory hallucinosis is classified as a specific typeof ∗hallucinosic syndrome. Because of its empha-sis on the involvement of a specific brain structure(i.e. the pedunculus cerebri or one of its surround-ing midbrain structures) it can also be classified asa ∗topological model of hallucinatory activity.

ReferenceCascino, G.D., Adams, R.D. (1986). Brainstem

auditory hallucinosis. Neurology, 36, 1042–1047.

Brainstem Hallucination

A term suggested in 1991 by the American neu-rologist C. Miller Fisher (b. 1910) to replacethe older term ∗peduncular hallucination. Morespecifically, Miller proposes to use the term brain-stem hallucination as an umbrella term for a cat-egory comprising the group of peduncular hal-lucinations and hallucinations attributed to CNS

structures in the vicinity of the pedunculus cere-bri. Fisher motivates this proposal as follows.“Although peduncular hallucinations are a wellrecognized type it might be preferable to includethem in a broader category – brain stem halluci-nations that would encompass not only pedun-cular cases proper but also cases in which visualhallucinations are associated with pontine haem-orrhage, thalamic haemorrhage, and thalamicinfarction.”

ReferenceFisher, C.M. (1991). Visual hallucinations on

eye closure associated with atropine toxicity.A neurological analysis and comparison withother visual hallucinations. Canadian Journalof Neurological Sciences, 18, 18–27.

Bridget of Sweden (1303–1373)

Born as Birgitta Birgersdotter; also known asSaint Birgitta, Santa Brigida, St. Bridgid of Swe-den, and Birgitta of Vadstena. A Swedish nun,mystic, and founder of the Bridgettine Order, whofrom childhood onwards experienced ∗visions ofcelestial and purgatory scenes. When she was 7years old, Bridget had a nocturnal vision of awoman in shining clothes sitting on an altar-table,who gave her a crown. She continued to havevisions until she was 10. During her forties thevisions returned, accompanied by voices whichshe attributed to God, the devil, or specific indi-viduals. While experiencing these visions she wasunaware of herself and her surroundings, suggest-ing that she may have experienced ∗trance statesor absences. Occasionally these episodes were pre-ceded by ∗cacosmia or ∗agathosma, interpretedby some as ∗olfactory aurae. Possibly she alsoexperienced ∗abdominal aurae. While the mak-ing of a retrospective diagnosis is always a deli-cate undertaking, Bridget’s experiences may wellhave been ∗ecstatic aurae (occurring in the con-text of temporal lobe epilepsy) or ∗postictal reli-gious experiences. It has been suggested that inBridget’s case the epileptic seizures were causedby a meningioma. Circumstantial evidence forthis hypothesis stems from the presence of an inte-rior indentation, the size of a hazelnut, insidethe skull thought to have belonged to Brid-get. According to the Swedish anatomist Carl-Herman Hjortsjö (1914–1978), this indentation

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may have been caused by a tumour, possibly aconvexity meningioma.

ReferenceLandtblom, A.M. (2004). Did St Birgitta suffer

from epilepsy? A neuropathography. Seizure,13, 161–167.

Brierre de Boismont’s Definition ofHallucinations and Illusions

In 1845 the French alienist Alexandre JacquesFrançois Brierre de Boismont (1797–1881)defined hallucinations and illusions as follows.“We define a hallucination as the perception ofthe sensible signs of the idea; and an illusion asthe false appreciation of real sensations.”

ReferenceBrierre de Boismont, A. (1859). On hallucina-

tions. A history and explanation of appari-tions, visions, dreams, ecstasy, magnetism, andsomnambulism. Translated by Hulme, R.T.London: Henry Renshaw.

Brobdingnagian Hallucination

Also known in the literature in the (misspelled)variants brobdignagian hallucination and brod-nigagian hallucination. The term brobdingna-gian hallucination is indebted to Brobdingnag, thename of a fictitious country inhabited by hugepeople, featuring in the novel Gulliver’s Trav-els by the Irish poet and author Jonathan Swift(1667–1745). It is used as a synonym for the term∗gulliverian hallucination, i.e. a ∗visual hallucina-tion in which disproportionally large human fig-ures are perceived, either in isolation, or againsta background of regular proportions. For a moredetailed account of this type of hallucination, seethe entry Gulliverian hallucination.

ReferencesEy, H. (2004). Traité des hallucinations. Tome 1.

Paris: Claude Tchou pour la Bibliothèque desIntrouvables.

Swift, J. (1726). Gulliver’s travels. London:B. Motte.

Brobdingnagian Vision

Also known in the literature in the (misspelled)variants brobdignagian vision and brodniga-gian vision. The term brobdingnagian vision isindebted to Brobdingnag, the name of a fictitiouscountry inhabited by huge people, featuring inthe novel Gulliver’s Travels by the Irish poet andauthor Jonathan Swift (1667–1745). It is used asa synonym for the term ∗macropsia, i.e. a ∗visualillusion in which objects and stimuli in the extra-corporeal world are perceived as disproportion-ally large. For a more detailed account of this typeof ∗illusion, see the entry Macropsia.

ReferencesSacks, O. (1992). Migraine. Revised and expanded.

New York, NY: Vintage Books.Swift, J. (1726). Gulliver’s travels. London:

B. Motte.

Brocken Bow

The name Brocken bow refers to the Brocken,a peak in the Harz mountains in Germany.It is used as a synonym for the terms gloryand ∗Ulloa’s bow, provided that the latter phe-nomenon is accompanied by a ∗Brocken spectre.

ReferenceLynch, D.K., Livingston, W. (1995). Color and

light in nature. Cambridge: Cambridge Univer-sity Press.

Brocken Spectre

Also known as Spectre of the Brocken and moun-tain spectre. The name Brocken spectre, or Brock-engespenst in German, refers to the Brocken, apeak in the Harz mountains in Germany. It isused to denote a ∗physical illusion consistingof the observer’s disproportionally large shadowprojected upon the surfaces of clouds at the hori-zon facing the rising or setting Sun. The per-son credited with documenting the phenomenonfor the first time, in 1780, is the German the-ologist and natural scientist Johann Esaias Sil-berschlag (1721–1791). As noted by Silberschlagand numerous observers after him, both near the

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Fig. 7 Brocken spectre. Source: Flammarion, C. (1873). The Atmosphere. Translated by Pitman, C.B.Edited by Glaisher, J. London: Sampson Low, Marston, Low, & Searle

Bufotenine and Hallucinations B

Brocken peak and in other mountainous regions,Brocken spectres typically arise when a low-lyingSun projects a large shadow into a bank of mistor fog in the distance. The resulting shadow fig-ure may appear to be moving, and strike one asbeing three-dimensional in shape because of theextent to which the shadow is projected into thefog, and because of the relative movements ofseparate fog banks. Lending the phenomenon aneven more impressive appearance, Brocken spec-tres can be accompanied by coloured concentricarches or circles, called glories or ∗Brocken bows,and a pale outer arch or circle which is called awhite rainbow or ∗Ulloa circle. These ∗halo fig-ures are explained by reference to the interactionof sunlight and droplets of water suspended inthe air.

ReferencesFlammarion, C. (1873). The atmosphere. Trans-

lated by Pitman, C.B. Edited by Glaisher,J. London: Sampson Low, Marston, Low, &Searle.

Lynch, D.K., Livingston, W. (1995). Color andlight in nature. Cambridge: Cambridge Univer-sity Press.

Buddha’s Halo

Also known as Buddha’s light. Both eponymsrefer to the corona of light traditionally depictedin images of Siddharta Gautama, also known asGautama Buddha (c. 566–486 BC), the founderof Buddhism. The terms Buddha’s halo and Bud-dha’s light are used to denote a ∗physical illusionconsisting of multicoloured, concentric rings oflight that can sometimes be seen against a cloudor fog bank in mountainous regions, at a positionopposite the Sun (i.e. the antisolar point). Twolocations in China famous for the appearanceof Buddha’s halo are Kanas Lake in XinjiangProvince and Huangshan Mountain in AnhuiProvince. Buddha’s halo is typically describedas a colourful circle of light appearing over (oragainst) a sea of clouds. Because of the sunlightcoming from behind, observers can see their ownshadow, as well as the shadows of nearby objectsand persons, projected upon the cloud. Since theyalways see their own shadow in the centre of thehalo, there is a certain tendency to interpret thisas a sign of their own enlightenment. Meteorol-ogists tend to explain atmospheric phenomena

such as Buddha’s halo by reference to the interac-tion of sunlight and droplets of water suspendedin the air, having a size smaller than 25 μm radius.Because of its lack of a tangible substratum in theextracorporeal world, Buddha’s halo is also clas-sified as a ∗fiction illusion. Phenomenologicallyas well as genetically, Buddha’s halo is related tothe ∗Ulloa circle and ∗Ulloa’s bow. It should notbe confused with ∗heiligenschein and the aureoleeffect.

ReferencesLynch, D.K., Livingston, W. (1995). Color and

light in nature. Cambridge: Cambridge Univer-sity Press.

Strassberg, R.E. (1994). Inscribed landscapes:Travel writing from Imperial China. Berke-ley, CA: University of California Press.

Buddha’s Light

see Buddha’s halo.

Bufotenine and Hallucinations

Bufotenine is also known as bufotenin, dimethylserotonin, 5-OH-dimethyltryptamine (5-OH-DMT), N,N-dimethyl-5-hydroxytryptamine, andmappine. The name bufotenine was suggested in1893 by the French scientists Césaire AugustePhisalix (1852–1906) and Gabriel Bertrand(1867–1962), and officially introduced in 1920by the Austrian chemist Hans Handovsky(1888–1959) as the name of a chemical sub-stance isolated by him from toadskin. The namederives from the Bufo genus of toads, variousspecies of which secrete a complex mixture ofpsychoactive substances that includes bufotenine.Bufotenine also occurs in the eggs of toadssuch as Bufo alvarius and Bufo marinus, aswell as in the Amazonian-Antillean narcoticsnuff Anadenanthera peregrina, and in somemushrooms, higher plants, and animals. Becauseof their psychoactive excrements, animals suchas B. alvarius and B. marinus are referred to as∗psychoactive fauna. Although bufotenine wasnot isolated until 1920, toad secretion has beenused as an ∗entheogen by shamans and mysticssince ancient times. Its toxicity was recordedas early as the first century AD by the Roman

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B Bufotenine and Hallucinations

poet Decimus Junius Juvenal (AD 60–128).Today bufotenine is classified as a hallucinogenictryptamine from the group of indole alkaloids. Itschemical structure, which is related to that of the∗hallucinogens psilocin and dimethyltryptamine(DMT), as well as to that of the neurotrans-mitter serotonin, was discovered in 1934 by thegroup of the German chemist and Nobel prizelaureate Heinrich Otto Wieland (1877–1957).In 1935–1936 bufotenine was synthesized forthe first time by the Japanese chemists ToshioHoshino and Kenya Shimodaira. Because orallyingested bufotenine is rapidly inactivated by thebody’s monoamine oxidase (MAO) system, itis usually applied intranasally, intravenously,by inhalation, or in the form of an enema. Forrecreational use, bufotoxins are also ingestedby means of toad licking. For bufotenine to bebiologically effective, the latter technique requiresthe simultaneous use of a MAO-inhibitingsubstance such as tranylcypromine to prevent apremature inactivation of bufotenine. The hal-lucinations mediated by bufotenine intoxicationare described as predominantly visual in nature.

∗Simple and ∗geometric visual hallucinations, inparticular, have been reported, as well as ∗trailingphenomena and an increased intensity of colours.Intense visual and ∗auditory hallucinations havebeen reported as well, however, commencingseconds after inhaling the smoke of dried toadvenom, and lingering on for about 5 min. Tradi-tionally comparisons have been made with theeffects of other hallucinogens such as LSD andmescaline, although the effects of bufotenine arereported as being milder, and of a shorter dura-tion. Due to the presence of the other toxins inBufo toad venom and eggs, the oral ingestion ofthese substances may induce various unexpectedside effects. Occasionally it may even result inepileptic seizures, coma, and eventually death.

ReferencesHandovsky, H. (1920). Ein Alkaloid in Gifte

von Bufo vulgaris. Archiv für ExperimentellePathologie und Pharmakologie, 86, 138–158.

Rudgley, R. (1998). The encyclopaedia of psy-choactive substances. London: Little, Brownand Company.

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