Fraser spiral illusion

Fraser spiral illusion

The Fraser spiral illusion is an optical illusion that was first described by the British psychologist Sir James Fraser (1863 1936) in 1908.

The illusion is also known as the false spiral, or by its original name, the twisted cord illusion. The overlapping black arc segments appear to form a spiral; however, the arcs are a series of concentric circles.

The visual distortion is produced by combining a regular line pattern (the circles) with misaligned parts (the differently colored strands).[1] Zöllner's illusion and the café wall illusion are based on a similar principle, like many other visual effects, in which a sequence of tilted elements causes the eye to perceive phantom twists and deviations.

The illusion is augmented by the spiral components in the checkered background.

See also

References

  1. Cucker, Felix (2013). Manifold Mirrors: The Crossing Paths of the Arts and Mathematics. Cambridge University Press. pp. 163–166. ISBN 978-0-521-72876-8.

External links

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