Impossible trident

Last updated

An impossible trident with backgrounds, to enhance the illusion Poiuyt--opaque.svg
An impossible trident with backgrounds, to enhance the illusion
Roger Hayward's Undecidable Monument RogerHaywardUndecidable Monument.jpg
Roger Hayward's Undecidable Monument

An impossible trident, [1] also known as an impossible fork, [2] blivet, [3] poiuyt, or devil's tuning fork, [4] is a drawing of an impossible object (undecipherable figure), a kind of an optical illusion. It appears to have three cylindrical prongs at one end which then mysteriously transform into two rectangular prongs at the other end.

In 1964, D. H. Schuster reported that he noticed an ambiguous figure of a new kind in the advertising section of an aviation journal. He dubbed it a "three-stick clevis". He described the novelty as follows: "Unlike other ambiguous drawings, an actual shift in visual fixation is involved in its perception and resolution." [5] The word "poiuyt" appeared on the March 1965 cover [6] of Mad magazine bearing the four-eyed Alfred E. Neuman balancing the impossible fork on his finger with caption "Introducing 'The Mad Poiuyt'" (the last six letters on the top row of QWERTY typewriters, right to left). An anonymously contributed version described as a "hole location gauge" was printed in the June 1964 issue of Analog Science Fiction and Fact , with the comment that "this outrageous piece of draftsmanship evidently escaped from the Finagle & Diddle Engineering Works". [7] Subsequently, a correspondent revealed that he had encountered the type of figure about twenty years previously, and had used it as a business logo since 1952. [8]

The term "blivet" for the impossible fork was popularized by Worm Runner's Digest magazine. In 1967, Harold Baldwin published there an article, "Building better blivets", in which he described the rules for the construction of drawings based on the impossible fork. [9] [4] In December 1968, American optical designer and artist Roger Hayward wrote a humorous submission "Blivets—Research and Development" for The Worm Runner's Digest in which he presented various drawings based on the blivet. [10] [11] , with a short sequel the following year. [12] The article was reprinted later in an anthology; in an introduction to the article, James McConnell "explained" the term as follows: "The blivet was first discovered in 1892 in Pfulingen, Germany, by a cross-eyed dwarf named Erasmus Wolfgang Blivet." [13] Hayward also published another sequel, Blivets—the Makin's. [14]

Notes

  1. Colman, Andrew. M. (2009) [2001]. A Dictionary of Psychology (3 ed.). Oxford University Press. ISBN   978-0-19-953406-7 . Retrieved 24 August 2025 via Internet Archive.
  2. Weisstein, Eric W. "Impossible Fork". MathWorld . Retrieved 14 March 2016.
  3. Raymond, Eric S. (29 December 2003). "blivet". The Jargon File. 4.4.7.
  4. 1 2 Masterton, Brooks; Kennedy, John M. (1975). "Building the Devil's Tuning Fork". Perception. 4 (1): 107–109. doi:10.1068/p040 . Retrieved 16 September 2025.
  5. Schuster, D. H. (December 1964). "A New Ambiguous Figure: A Three-Stick Clevis". The American Journal of Psychology. 77 (4): 673. doi:10.2307/1420787. JSTOR   1420787. PMID   14251982 . Retrieved 16 September 2025.
  6. "Doug Gilford's Mad Cover Site - Mad #93". Madcoversite.com. Retrieved 22 October 2010.
  7. "Hole Location Gauge". Analog. 73 (5): 27. June 1964. Retrieved 19 February 2025.
  8. Tunnell, James (October 1964). "Industrial Camera". Analog. 74 (2): 95. Retrieved 20 February 2025.
  9. Baldwin, Harold (December 1967). "Building Better Blivets". Worm Runner's Digest . 9 (2): 104–106.
  10. Hayward, Roger (December 1968). "Blivets—Research and Development". Worm Runner's Digest. 10 (2): 89–92.
  11. Gardner, Martin (1992) [1968]. "Optical Illusions". Mathematical Circus. Spectrum. Washington, D. C.: Mathematical Association of America. p. 5. ISBN   0-88385-506-2 . Retrieved 24 August 2025 via Internet Archive.
  12. Hayward, Roger (December 1969). "Blivet or Not". The Journal of Biological Psychology. 11 (2): 52.
  13. Hayward, Roger (1971). "Blivets—Research and Development". In McConnell, James V.; Schutjer, Marlys (eds.). Science, Sex, and Sacred Cows: Spoofs on Science from the Worm Runner's Digest . New York: Harcourt Brace Jovanovich. p. 91. ISBN   0-15-179595-9 . Retrieved 24 August 2025 via Internet Archive.
  14. Hayward, Roger (Winter 1970). "Blivets—the Makin's". Worm Runner's Digest. 12 (2): 86–88.