Example of an irradiation illusion

The irradiation illusion is an illusion of visual perception in which a light area of the visual field looks larger than an otherwise identical dark area. It was named by Hermann von Helmholtz around 1867;[1] but the illusion was familiar to scientists long before then; Galileo mentions it in his 1632 book Dialogue Concerning the Two Chief World Systems.[2] It arises partly from scattering of light inside the eye. This has the effect of enlarging the image of a light area on the retina.

References

  1. ^ Hermann von Helmholtz, Handbook of Physiological Optics (J. P. C. Southall, Trans. 3rd ed.), New York (1910, 1962), Dover
  2. ^ Galileo Galilei, Dialogue Concerning the Two Chief World Systems (1632), Day 1.


source: http://en.wikipedia.org/wiki/Irradiation_illusion