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Blindsight Also Occurs In Monkeys

Blindsight is an eerie phenomenon. Humans with cortical blindness; that is, they have lost their primary visual cortex through brain damage or disease; can still detect objects and yet be unaware of them. Doesn't sound right, does it? The situation is this: A person, apparently totally blind, can somehow discern the location, form, and size of objects, but they will swear that they "see" nothing at all. In fact, they are blind by all tests. They have blindsight.

One explanation of blindsight maintains that the visual cortex has not been totally destroyed, and that functional remnants remain. In scientific terms, blindsight represents "suboptimal functioning of the primary visual cortex."

But now, A. Cowey and P. Stoerig report that they have totally removed the primary visual cortex from monkeys' brains. (Something one would not try with humans!) Tests with the visual cortex-less monkeys demonstrated that they possessed blindsight. Therefore, blindsight does not seem to be "suboptimal functioning" of a damaged brain -- at least in monkeys.

Blindsight thus remains a mysterious biological function. How do blindsighted humans detect objects of which they are not visually aware? Somehow information about the visual world appears in the brain.

(Cowey, Alan, and Stoerig, Petra; "Blindsight in Monkeys," Nature, 373: 247, 1995. Also: Kaas, Jon H.; "Vision without Awareness," Nature, 373:195, 1995)

Blindsight in humans is cataloged under code BHT3 in Biological Anomalies: Humans I. Ordering information here.

From Science Frontiers #98, MAR-APR 1995. 1995-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:

Quotes

  • "A sourcebook of unexplained phenomena is therefore a valuable addition to a collection of scientific literature. William R. Corliss has provided this in the past with his source books of scientific anomalies in several subjects, and now he has provided it for astronomy. He has done an excellent job of collecting and editing a large amount of material, taken in part from scientific journals and in part from scientific reporting in the popular or semi-scientific press." -- "The Mysterious Universe: A Handbook of Astronomical Anomalies", reviwed by Thomas Gold, Cornell University, in Icarus, vol.41, 1980

  • "An interesting, systematic presentation of unusual weather [..] This book is recommended for a general audience" --"Corliss, William R., Tornados, Dark Days, Anomalous Precipitation, and Related Weather Phenomena, Sourcebook Project, 1983.", revieweed in Choice, September 1983
  • "..the science is necessarily somewhat speculative, but Corliss's symthesis is based on reputable sources." -- "Corliss, William R. (Compiler). Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena" reviwed by Joseph M. Moran, Univ. of Wisconsin in Science Books and Films, Sep/Oct 1983

  • "Before opening the book, I set certain standards that a volume which treads into dangerous grounds grounds like this must meet. The author scrupulously met, or even exceeded those standards. Each phenomenon is exhaustively documented, with references to scientific journals [..] and extensive quotations" -- "Book Review: The moon and planets: a catalog of astronomical anomalies", The Sourcebook Project, 1985., Corliss, W. R., Journal of the Royal Astronomical Society of Canada, Vol. 81, no. 1 (1987), p. 24., 02/1987