Physics:Orbison illusion

Orbison illusion consisting of a square placed over radial lines.

The Orbison illusion (or Orbison's illusion) is an optical illusion first described by American psychologist William Orbison (1912–1952) in 1939.

The illusion consists of a two dimensional figure, such as a circle or square, superimposed over a background of radial lines or concentric circles. The result is an optical illusion in which both the figure and the rectangle which contains it appear distorted; in particular, squares appear slightly bulged, circles appear elliptical, and the containing rectangle appears tilted.

References

• Fineman, Mark (1996). The Nature of Visual Illusion. Dover Publications. pp. 152-153. ISBN 0486291057. https://archive.org/details/natureofvisualil0000fine/page/152. 
• Robinson, J.O. (1998). The Psychology of Visual Illusion. Dover Publications. pp. 72–73. ISBN 978-0486404493.