The Orbison illusion (or Orbison's illusion) is an
optical illusion
In visual perception, an optical illusion (also called a visual illusion) is an illusion caused by the visual system and characterized by a visual perception, percept that arguably appears to differ from reality. Illusions come in a wide varie ...
first described by American psychologist
William Orbison (1912–1952)
in 1939.
The illusion consists of a two dimensional figure, such as a
circle
A circle is a shape consisting of all point (geometry), points in a plane (mathematics), plane that are at a given distance from a given point, the Centre (geometry), centre. The distance between any point of the circle and the centre is cal ...
or
square
In geometry, a square is a regular polygon, regular quadrilateral. It has four straight sides of equal length and four equal angles. Squares are special cases of rectangles, which have four equal angles, and of rhombuses, which have four equal si ...
, superimposed over a background of
radial lines or
concentric circles. The result is an optical illusion in which both the figure and the
rectangle
In Euclidean geometry, Euclidean plane geometry, a rectangle is a Rectilinear polygon, rectilinear convex polygon or a quadrilateral with four right angles. It can also be defined as: an equiangular quadrilateral, since equiangular means that a ...
which contains it appear distorted; in particular, squares appear slightly bulged, circles appear
elliptical, and the containing rectangle appears tilted.
References
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External links
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Optical illusions
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