Main Page | See live article | Alphabetical index The Fraser spiral illusion is the famous spiral after-effect 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 Sekular and Eugene Levinson, who called it "perception of moving targets". See also, Optical illusion This article is a stub. You can help Wikipedia by fixing it. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.