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Delboeuf illusion
Reference material by Wiktionary contributors. This retains its source identity and is not 411 news reporting.
English
thumb|The two circled dark discs are the same size, but the left disc seems smaller.
Etymology
Discovered in 1865 by the Belgian scientist Joseph Remi Leopold Delboeuf (1831–1896).
Noun
An optical illusion of relative size perception, usually illustrated by two discs of identical size, one of which is surrounded by a ring.
en Optical illusions
en eponyms