- illusory visual spread
- Also known as illusory visual perseveration. Both terms were introduced in or shortly before 1949 by the British neurologist Macdonald Critchley (1900-1997) to denote a type of "visual perse-veration characterized by the visual extension, expansion, or prolongation of a stimulus-object, "in other words, a kind of spatial persevera-tion of objects seen". In illusory visual spread, objects within the visual field are often perceived as multiple copies, and neighbouring objects may appear to take on the colours and texture of these objects. Critchley illustrates the latter phenomenon as follows: "The pattern of a striped or chequered garment would seem to extend over the face of the wearer. The pattern of cretonne curtains would often seem to extend along the adjacent wall." As to the pathophysiology of illusory visual spread, it has been suggested that the visual parietal regions may be involved in its mediation. In an etiological sense the phenomenon is associated primarily with " aurae occurring in the context of paroxysmal neurological disorders such as migraine and epilepsy, and with the use of " hallucinogens such as LSD and mescaline. Illusory visual spread is classified by Critchley as a type of visual perseveration, which is in turn classified as a "reduplicative phenomenon or a type of " metamorphopsia.ReferencesCritchley, M. (1949). Metamorphopsia of central origin. Transactions of the Ophthalmologic Society of the UK, 69, 111-121.Critchley, M. (1953). The parietal lobes. London: Edward Arnold & Co.ffytche, D.H., Howard, R.J. (1999). The perceptual consequences of visual loss: 'positive' pathologies of vision. Brain, 122, 1247-1260.Santhouse, A., Howard, R., ffytche, D. (2000). Visual hallucinatory syndromes and the anatomy of the visual brain. Brain, 123, 2055-2064.
Dictionary of Hallucinations. J.D. Blom. 2010.
Look at other dictionaries:
illusory visual perseveration — see illusory visual spread … Dictionary of Hallucinations
visual perseveration — Also known as perseveration. Both terms are indebted to the Latin verb perseverare,which means to maintain or to keep on stating. The term visual perseveration was introduced in or shortly before 1949 by the British neurologist Macdonald… … Dictionary of Hallucinations
metamorphopsia — The term metamorphopsia comes from the Greek words metamorphoun (to change the form) and opsis (seeing). It translates roughly as seeing an altered form . It is not clear who introduced the term, but it appears in a medical lexicon as early as … Dictionary of Hallucinations
palinopsia — Also referred to as pseudodiplopia. The term palinopsia comes from the Greek words palin (again) and opsis (seeing). It translates as seeing again or seeing multiple identical copies . The original term for this group of visual phenomena was * … Dictionary of Hallucinations
reduplicative phenomenon — The term reduplicative phenomenon is indebted to the Latin noun reduplicare, which means to double. It is used as an umbrella term for a group of illusory perceptual phenomena characterized by the perseveration, reduplication, or reoccurrence… … Dictionary of Hallucinations
Posterior cerebral artery — Artery: Posterior cerebral artery Outer surface of cerebral hemisphere, showing areas supplied by cerebral arteries. (Yellow is region supplied by posterior cerebral artery.) … Wikipedia
paliopsia — A term coined in or shortly before 1949 by the British neurologist Macdonald Critchley (19001997) to denote the phenomenon known today as * palinopsia (i.e. a visual image that persists or recurs paroxysmally after the original object or… … Dictionary of Hallucinations
United States — a republic in the N Western Hemisphere comprising 48 conterminous states, the District of Columbia, and Alaska in North America, and Hawaii in the N Pacific. 267,954,767; conterminous United States, 3,022,387 sq. mi. (7,827,982 sq. km); with… … Universalium
Buddhism — Buddhist, n., adj. Buddhistic, Buddhistical, adj. Buddhistically, adv. /booh diz euhm, bood iz /, n. a religion, originated in India by Buddha (Gautama) and later spreading to China, Burma, Japan, Tibet, and parts of southeast Asia, holding that… … Universalium
painting, Western — ▪ art Introduction history of Western painting from its beginnings in prehistoric times to the present. Painting, the execution of forms and shapes on a surface by means of pigment (but see also drawing for discussion of depictions in … Universalium