Orbison Illusion

The Orbison illusion is an optical illusion in which a simple two-dimensional geometric figure, such as a circle or a square, is distorted in appearance when it is superimposed over a background made up of radiating lines or concentric circles. The American psychologist William Orbison, who lived from 1912 to 1952, first documented the effect in 1939. Under the illusion, a square superimposed on such a background appears to bulge outward, a circle takes on an elliptical, egg-like shape, and even the straight-sided rectangle used to frame the figure appears to tilt, so that both the geometric figure itself and the rectangle that contains it are perceived as distorted by the radiating or concentric pattern behind them.