photically induced hallucination
   Also known as flicker-induced hallucination, hallucinatory flicker-induced experiences, and Purkinje's colours. All four terms are used to denote a type of *geometric visual hallucination induced by a flickering light, such as that produced by a stroboscope or by sunlight interrupted by the shadows of trees, as observed by an individual moving along those trees. Phenomeno-logically, photically induced hallucinations may resemble the geometric * form-constants as described by the German-American biological psychologist and philosopher Heinrich Klüver (1897-1979). Under laboratory conditions many different shapes have been reported, including *gratings, * spirals, concentric circles, and fan blades. However, contrary to the hallucinogen-induced hallucinations described by Klüver, photically induced hallucinations tend to lack an extreme saturation of colour. The mediation of the geometric forms is attributed to stripe patterns of neural activity in specialized cortical columns whose spatial orientation on the visual cortex combines with a nonlinear retinocortical mapping. Photically induced hallucinations were probably described for the first time in 1819 by the Bohemian physiologist Johannes Evangelista Purkyne (1787-1869). A special type of the photically induced hallucination is the *television-induced hallucination.
   References
   Billock, V.A., Tsou, B.H. (2007). Neural interactions between flicker-induced self-organized visual hallucinations and physical stimuli. Proceedings of the National Academy of Sciences of the United States of America, 104, 8490-8495.

Dictionary of Hallucinations. . 2010.

Look at other dictionaries:

  • television-induced hallucination —    The notion of television induced hallucination refers to a type of hallucination uniquely provoked by television viewing. This type of hallucination is believed to be extremely rare. The first case report of hallucinations co occurring with… …   Dictionary of Hallucinations

  • flicker-induced hallucination —    see photically induced hallucination …   Dictionary of Hallucinations

  • hallucinatory flicker-induced experience —    see photically induced hallucination …   Dictionary of Hallucinations

  • geometric hallucination —    Also known as geometrical hallucination, geometric visual hallucination, and optogeometric illusion. All four terms can be traced to the Greek noun geometria, which means land surveying. They are used to denote a * formed visual hallucination… …   Dictionary of Hallucinations

  • Purkinje's colour —    Also known as Purkinje phenomenon, Purkinje hallucination, flicker induced hallucination, and photically induced hallucination. The eponyms Purkinje s colour, Purkinje hallucination, and Purkinje phenomenon refer to the Bohemian physiologist… …   Dictionary of Hallucinations

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