The Fraser spiral illusion is an optical illusion that was developed by the British psychologist James Fraser in 1908. The spiral illusion consists of overlapping black and white sheets that appear to form a spiral.

In reality, however, it is a series of concentric circles.
The visual distortion is created by combining regular shapes, in this case circles, with offset elements, namely the different coloured stripes. The effect is intensified by the chequerboard-like background pattern.

Another form of Fraser illusion consists of straight, horizontal lines composed of diagonally positioned black and white lines. As a result, the horizontal lines also appear to be orientated upwards or downwards.