Impossible trident

Common card · No. 432012

An impossible trident, also known as an impossible fork, blivet, poiuyt, or devil's tuning fork, 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." The word "poiuyt" appeared on the March 1965 cover 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...

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