View source for Impossible trident

{{Short description|2D drawing of impossible 3D object}}
{{use dmy dates|date=August 2025}}
[[File:Poiuyt--opaque (rotated).svg|thumb|right|An impossible trident with backgrounds, to enhance the illusion]]
[[File:RogerHaywardUndecidable Monument.jpg|thumb|right|upright|[[Roger Hayward]]'s ''Undecidable Monument'']]
An '''impossible trident''',<ref>{{cite book |last=Colman |first=Andrew. M. |title=A Dictionary of Psychology |edition=3 |publisher=Oxford University Press |orig-year=2001 |year=2009 |isbn=978-0-19-953406-7 |url=https://archive.org/details/dictionaryofpsyc0000colm_s3f2 |access-date=24 August 2025 |url-access=registration |via=Internet Archive}}</ref> also known as an '''impossible fork''',<ref>{{MathWorld |id=ImpossibleFork |title=Impossible Fork |access-date=14 March 2016}}</ref> '''blivet''',<ref>{{cite dictionary |last=Raymond |first=Eric S. |date=29 December 2003 |entry-url=http://www.catb.org/~esr/jargon/html/B/blivet.html |entry=blivet |dictionary=The Jargon File |version=4.4.7}}<!--It lists the impossible fork among numerous meanings of the term--></ref> '''poiuyt''',<ref name="madcover" /> or '''devil's tuning fork''',<ref name=mk>{{cite journal |last1=Masterton |first1=Brooks |last2=Kennedy |first2=John M. |title=Building the Devil's Tuning Fork |journal=Perception |date=1975 |volume=4 |issue=1 |pages=107-109 |doi=10.1068/p040 |url=https://www.academia.edu/6866169/Building_the_Devils_Tuning_Fork |access-date=16 September 2025}}</ref> 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."<ref>{{cite journal |last=Schuster |first=D. H. |date=December 1964 |title=A New Ambiguous Figure: A Three-Stick Clevis |url=https://psycnet.apa.org/record/1965-11146-001 |journal=[[The American Journal of Psychology]] |volume=77 |issue=4 |page=673 |doi=10.2307/1420787 |jstor=1420787 |pmid=14251982 |access-date=16 September 2025}}</ref>
The word "poiuyt" appeared on the March 1965 cover<ref name="madcover">{{cite web |url=http://madcoversite.com/mad093.html |title=Doug Gilford's Mad Cover Site - Mad #93 |website=Madcoversite.com |access-date=2010-10-22}}</ref> of ''[[Mad (magazine)|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".<ref>{{cite journal |title=Hole Location Gauge |journal=Analog |date=June 1964 |volume=73 |issue=5 |page=27 |url=https://drive.google.com/file/d/17BGFhtyaitPRa0sf-9C1C5xRi-IacZ0w/view?pli=1 |access-date=2025-02-19}}</ref> 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.<ref>{{cite journal |last1=Tunnell |first1=James |title=Industrial Camera |journal=Analog |date=October 1964 |volume=74 |issue=2 |page=95 |url=https://drive.google.com/file/d/1hDnS4IlwuhE0jvgzqAYng5aKx0eiX0uL/view |access-date=2025-02-20}}</ref>

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.<ref>{{cite journal |last=Baldwin|first=Harold |date=December 1967 |title=Building Better Blivets |journal=[[Worm Runner's Digest]] |volume=9 |issue=2 |pages=104-106}}</ref><ref name=mk/>
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,<ref>{{cite journal |last=Hayward |first=Roger |date=December 1968 |title=Blivets—Research and Development |journal=[[Worm Runner's Digest]] |volume=10 |issue=2 |pages=89-92}}</ref><ref>{{cite book |last=Gardner |first=Martin |author-link=Martin Gardner |chapter=Optical Illusions |title=Mathematical Circus |location=Washington, D. C. |publisher=[[Mathematical Association of America]] |series=Spectrum |orig-year=1968 |year=1992 |url=https://archive.org/details/mathematical-circus |access-date=24 August 2025 |via=Internet Archive |isbn=0-88385-506-2 |page=5}}</ref> with a short sequel the following year.<ref>{{cite journal |last=Hayward |first=Roger |date=December 1969 |title=Blivet or Not |url={{GBurl|id=NWpXAAAAMAAJ|q=baldwin+blivets}} |journal=The Journal of Biological Psychology |volume=11 |issue=2 |page=52}}</ref> The article was reprinted later in an anthology; in an introduction to the article, [[James V. 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."<ref>{{cite book |last=Hayward |first=Roger|chapter=Blivets—Research and Development |page=91 |editor-last1=McConnell |editor-first1=James V. |editor-last2=Schutjer |editor-first2=Marlys |title=Science, Sex, and Sacred Cows: Spoofs on Science from the Worm Runner's Digest |location=New York |publisher=Harcourt Brace Jovanovich |year=1971 |isbn=0-15-179595-9 |url=https://archive.org/details/sciencesexsacred0000mcco |url-access=registration |access-date=24 August 2025 |via=Internet Archive}}</ref> Hayward also published another sequel,'' Blivets—the Makin's''.<ref>{{cite journal |last=Hayward |first=Roger |date=Winter 1970 |title=Blivets—the Makin's |journal=[[Worm Runner's Digest]] |volume=12 |issue=2 |pages=86-88}}</ref>

==Notes==
{{reflist}}

{{Sister bar|Blivet|wikt=blivet |commons=Category:Blivet|auto=1}}

{{Optical illusions}}
{{Authority control}}
[[Category:Optical illusions]]
[[Category:Impossible objects]]