Fraser spiral illusion
|
|
The Fraser spiral illusion is the famous spiral after-effect optical illusion based on the "motion after-effect" illusion. This was first described as the Waterfall Effect by 19th Century theorist R Addams. This was later studied in the 1970s by Robert Sekuler and Eugene Levinson, who called it "perception of moving targets".
Correction: The Fraser spiral has nothing to do with the motion after-effect [1] (http://www.hip.atr.co.jp/departments/Dept5/MAEWWW/home.html). Rather, is belongs into the class of geometrical angle illusions -- it consists of purely circular structures and just _looks_ like a spiral. (For support, see the external links.)
External links
- Fraser's Spiral from MathWorld (http://mathworld.wolfram.com/FrasersSpiral.html)
- An interactive Fraser Spiral (http://www.michaelbach.de/ot/ang_fraser/index.html)