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Illusion -- from Mathworld an Illusion Object Or Drawing Which Appears to Have Properties Which Are Physically Impossible, Deceptive, Or Counterintuitive

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Illusion -- from Mathworld an Illusion Object Or Drawing Which Appears to Have Properties Which Are Physically Impossible, Deceptive, Or Counterintuitive Illusion -- From MathWorld An illusion object or drawing which appears to have properties which are physically impossible, deceptive, or counterintuitive. Kitaoka maintains a web page of beautiful optical illusions which appear to show rotation despite actually being http://mathworld.wolfram.com/Illusion.html - 21k - 2003-10-05 Young Girl-Old Woman Illusion -- From MathWorld A famous perceptual illusion in which the brain switches between seeing a young girl and an old woman (or "wife" and "mother in law"). An anonymous German postcard from 1888 (left figure) depicts the image in its earliest known form, and a rendition on an advertisement for the Anchor Buggy Company from 1 http://mathworld.wolfram.com/YoungGirl-OldWomanIllusion.html - 19k - 2002-08-18 Impossible Fork -- From MathWorld ImpossibleFork.gifThe impossible fork (Seckel 2002, p. 151), also known as the devil's pitchfork (Singmaster) or blivet, is a classic impossible figure originally due to Schuster (1964). While each prong of the fork (or, in the original work, "clevis") appears normal, attempting to determine their manner http://mathworld.wolfram.com/ImpossibleFork.html - 19k - 2004-10- 01 Penrose Stairway -- From MathWorld An impossible figure in which a stairway in the shape of a square appears to circulate indefinitely while still possessing normal steps (Penrose and Penrose 1958). The Dutch artist M. C. Escher included a Penrose stairway in his mind-bending illustration "Ascending and Descending" (Bool et al. 1982, p. 3 http://mathworld.wolfram.com/PenroseStairway.html - 20k - 2004- 02-01 Hering Illusion -- From MathWorld An optical illusion due to the physiologist Ewald Hering (1861). The two horizontal lines are both straight, but they look as if they were bowed outwards. The distortion is produced by the lined pattern on the background, that simulates a perspective design, and creates a false impression of http://mathworld.wolfram.com/HeringIllusion.html - 17k - 2002-06-06 Fraser's Spiral -- From MathWorld An optical illusion named after British psychologist James Fraser, who first studied the illusion in 1908 (Fraser 1908). The illusion is also known as the false spiral, or by its original name, the twisted cord illusion. While the image appears to be a spiral formed by a rope containing twisted strands o http://mathworld.wolfram.com/FrasersSpiral.html - 18k - 2002-04-23 Optical Illusion -- From MathWorld http://mathworld.wolfram.com/OpticalIllusion.html - 14k - 2003-10- 05 Ouchi Illusion -- From MathWorld ouchi.gifThe Ouchi illusion, illustrated above, is an illusion named after its inventor, Japanese artist Hajime Ouchi. In this illusion, the central disk seems to float above the checkered background when moving the eyes around while viewing the figure. Scrolling the image horizontally or vertically give http://mathworld.wolfram.com/OuchiIllusion.html - 19k - 2003-11-16 Continuous Line Illusion -- From MathWorld While the above figure appears to be a sequence of nested squares, it actually consists of a single square http://mathworld.wolfram.com/ContinuousLineIllusion.html - 16k - 2003-09-10 Angle Illusions -- From MathWorld Shapes such as segments or angles appear larger when placed inside a larger http://mathworld.wolfram.com/AngleIllusions.html - 16k - 2002-06-06 Square Illusions -- From MathWorld In the above figure, the identical squares A, B, C appear different in width and height, because subdividing a space makes it appear larger.A different orientation can also produce an illusion of enlargement. As illustrated above, a square whose diagonals are placed horizontally and vertically seems larg http://mathworld.wolfram.com/SquareIllusions.html - 18k - 2002-06- 06 Poggendorff Illusion -- From MathWorld The illusion that the two ends of a straight line segment passing behind an obscuring rectangle are offset when, in fact, they are aligned. The Poggendorff illusion was discovered in 1860 by physicist and scholar J. C. Poggendorff, editor of Annalen der Physik und Chemie, after receiving a letter from as http://mathworld.wolfram.com/PoggendorffIllusion.html - 19k - 2005- 07-12 Square-in-a-Circle Illusion -- From MathWorld A circle surrounded by a square looks larger than the same circle surrounding a square. http://mathworld.wolfram.com/Square-in-a-CircleIllusion.html - 16k - 2002-06-06 Benham's Wheel -- From MathWorld An optical illusion consisting of a spinnable top marked in black with the pattern shown above. When the wheel is spun (especially slowly), the black broken lines appear as green, blue, and red colored http://mathworld.wolfram.com/BenhamsWheel.html - 16k - 2005-08- 16 Ehrenstein Illusion -- From MathWorld An illusion studied by the psychologist Walter Ehrenstein in which the sides of a square placed inside a pattern of concentric circles take an apparent curved shape. The name Ehrenstein is also associated with one of the illusory contour http://mathworld.wolfram.com/EhrensteinIllusion.html - 17k - 2002- 06-06 Müller-Lyer Illusion -- From MathWorld An optical illusion in which the orientation of arrowheads makes one line segment look longer than another. In the above figure, the line segments on the left and right are of equal length in both http://mathworld.wolfram.com/Mueller-LyerIllusion.html - 16k - 2005- 07-11 Café Wall Illusion -- From MathWorld An optical illusion produced by a black and white rectangular tessellation when the tiles are shifted in a zigzag pattern, as illustrated above. While the pattern seems to diverge towards the upper and lower right corners in the upper figure, the gray lines are actually parallel. Interestingly, the illus http://mathworld.wolfram.com/CafeWallIllusion.html - 18k - 2002-04- 19 Goblet Illusion -- From MathWorld An illusion in which the eye alternately sees two black faces, or a white http://mathworld.wolfram.com/GobletIllusion.html - 17k - 2005-08-17 Rabbit-Duck Illusion -- From MathWorld rabbduck.gifAn ambiguous figure in which the brain switches between seeing a rabbit and a duck. The duck-rabbit was "originally noted" by American psychologist Joseph Jastrow (Jastrow 1899, p. 312; 1900; see also Brugger 1999). Jastrow used the figure, together with such figures as the Necker cube and Sc http://mathworld.wolfram.com/Rabbit-DuckIllusion.html - 20k - 2004- 12-10 Penrose Triangle -- From MathWorld The Penrose triangle, also called the tribar (Cerf), tri-bar (Ernst 1987), impossible tribar (Pappas 1989, p. 13), or impossible triangle, is an impossible figure published by Penrose and Penrose (1958). Penrose triangles appear prominently in the works of Escher, who not only inspired creation of this o http://mathworld.wolfram.com/PenroseTriangle.html - 20k - 2005-11- 01 Jastrow Illusion -- From MathWorld An illusion named after the psychologist Joseph Jastrow. In the above figure, the left edges of the laminas A and B are colinear, creating an illusion of different size. However, the two laminas are actually http://mathworld.wolfram.com/JastrowIllusion.html - 16k - 2002-06- 06 Freemish Crate -- From MathWorld The Freemish crate, also called Escher's cube (Elber) or Hyzer's illusion (Pappas 1989, p. 13), is an impossible figure box that can be drawn but not built. It appears in Escher's 1958 lithograph Belvedere (Gardner 1970, Ernst 1987), and was subsequently redrawn/rediscovered by Cochran (1966) in the form http://mathworld.wolfram.com/FreemishCrate.html - 19k - 2004-09- 30 Wundt Illusion -- From MathWorld An illusion invented by the German psychologist Wilhelm Wundt in the 19th century. In the figure above, the two red horizontal lines are both straight, but they look as if they are bowed inwards. The distortion is induced by the crooked lines on the background, as in Orbison's illusion.A modification of http://mathworld.wolfram.com/WundtIllusion.html - 17k - 2003-09-10 Schroeder Stairs -- From MathWorld The Schroeder stairs, also called Schouten's staircase (Bool et al. 1982, p. 147), are an ambiguous figure that depicts two different staircases at the same time: one going up from right to left, the other turned upside down. The Schroeder stairs appear in M. C. Escher's works "Relativity" (Bool 1982, p. http://mathworld.wolfram.com/SchroederStairs.html - 18k - 2003-06- 09 Morellet's Tirets Illusion -- From MathWorld In above figure, which constitutes a modified version of the painting Tirets by Francois Morellet, small circles seem to appear and disappear as the eye is moved over http://mathworld.wolfram.com/MorelletsTiretsIllusion.html - 16k - 2003-09-25 Scintillating Grid Illusion -- From MathWorld In the above illustration, black dots appear to form and vanish at the intersections of the gray horizontal and vertical lines. When focusing attention on a single white dot, some gray dots nearby and some black dots a little further away also seem to appear. More black dots seem to appear as the eye is http://mathworld.wolfram.com/ScintillatingGridIllusion.html - 18k - 2002-11-19 Three-Arc Illusion -- From MathWorld The larger an arc is, the smaller its radius appears. For example, the three arcs illustrated above belong to the same http://mathworld.wolfram.com/Three-ArcIllusion.html - 16k - 2002- 06-06 Kanizsa Triangle -- From MathWorld An optical illusion, illustrated above, in which the eye perceives a white upright equilateral triangle where none is actually http://mathworld.wolfram.com/KanizsaTriangle.html - 16k - 2005-07- 11 Irradiation Illusion -- From MathWorld The illusion shown above which was discovered by Helmholtz in the 19th century. Despite the fact that the two above figures are identical in size, the white hole looks bigger than the black one in this http://mathworld.wolfram.com/IrradiationIllusion.html - 16k - 2005- 07-11 Moiré Pattern -- From MathWorld moire.gifAn interference pattern produced by overlaying similar but slightly offset templates. A simple example is obtained by taking two identical ruled transparent sheets of plastic, superposing them, and rotating one about its center as the other is held fixed.Moiré patterns can also be created by pl http://mathworld.wolfram.com/MoirePattern.html - 20k - 2002-05-04 Anamorphic Art -- From MathWorld http://mathworld.wolfram.com/AnamorphicArt.html - 17k - 2005-11- 05 .
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