The Delboeuf illusion is an optical illusion of relative size perception in which two identical discs, each judged in light of a surrounding ring, appear to differ in size. A disc encircled by a ring positioned close to its edge appears larger than an identical disc with no ring at all, while the same disc encircled by a ring positioned farther away appears smaller than the unringed disc. Research published in 2005 suggests the Delboeuf illusion stems from the same visual processes responsible for the related Ebbinghaus illusion. The illusion takes its name from the Belgian scholar Joseph Remi Leopold Delboeuf (1831 to 1896), a philosopher, mathematician, experimental psychologist, hypnotist and psychophysicist, who first identified the effect in 1865.
Facts
First Described YearThe illusion was named for Joseph Remi Leopold Delboeuf, who discovered it in 1865. (w-bbfill-psychology6-0926) Classification
Type of Phenomenon Sources
1. Wikipedia: Delboeuf Illusion
WikipediaWikipedia article text
The illusion was named for Joseph Remi Leopold Delboeuf, who discovered it in 1865.
lead section, phenomenon-kind classification
The Delboeuf illusion is an optical illusion of relative size perception: In the best-known version of the illusion, two discs of identical size have been placed near to each other and one is surrounded by a ring; the surrounded disc then appears larger than the non-surrounded disc if the ring is close, while appearing smaller than the non-surrounded disc if the ring is distant.
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