TypeSize and shape
InteractiveYes: sliders and a check
First described1908
This looks like a spiral winding into the middle. It is a set of separate circles.
Try this
- Tick Trace one ring and follow it all the way round: it closes on itself.
- Set Tilt of the stripes to 0 and the spiral vanishes.
Why it happens
Each little stripe is tilted, and your visual system adds the tilts up along each ring. The result reads as a line spiraling inward. James Fraser described it in 1908 as "a new visual illusion of direction". It is a cousin of the Zöllner illusion: local angles change the overall direction you see.
Did you know?
The original used a twisted-cord pattern on a checkered background. Many people refuse to believe it is circles until they trace one with a finger.
References
- FRASER J. (1908). A NEW VISUAL ILLUSION OF DIRECTION. British Journal of Psychology, 1904-1920, 2, 307-320. doi:10.1111/j.2044-8295.1908.tb00182.x
- Background on Wikipedia
The illusion on this page is drawn by code written for this site. Last checked 1 November 2026.
Frequently asked questions
Is the Fraser spiral a spiral?
No. It is concentric circles; trace one to check.
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