A Timeline of Optical Illusion History

Optical illusions don't arrive on a neat schedule - some are formal scientific discoveries, some are folk images that circulated long before anyone wrote them up, and some are internet-era accidents that happened to go viral. This timeline traces the documented history as closely as the record allows, from the first well-attested 19th-century description through to the present.

19th century: the first formal descriptions

1832 - Swiss crystallographer Louis Albert Necker describes the Necker cube effect, having noticed rhomboid crystal shapes spontaneously reversing in apparent depth under a microscope.

1870 - Physiologist Ludimar Hermann describes what becomes known as the Hermann grid illusion.

1889 - German sociologist and psychiatrist Franz Carl Müller-Lyer publishes the Müller-Lyer illusion, part of a wave of German geometric-optical illusion research in this period.

1892 - The duck-rabbit illusion first appears in the German humor magazine Fliegende Blätter, later picked up by psychologists including Joseph Jastrow.

Early 20th century: psychology formalizes the field

Early 1910s (usually dated 1911) - Italian psychologist Mario Ponzo publishes the Ponzo illusion, demonstrating size-constancy distortion driven by linear perspective cues.

1915 - Danish psychologist Edgar Rubin publishes Rubin's vase; around the same period, the "My Wife and My Mother-in-Law" illusion is popularized in the United States, building on an earlier German postcard image.

1920s–30s - Gestalt psychologists Max Wertheimer, Kurt Koffka, and Wolfgang Köhler formalize the grouping principles - proximity, similarity, closure, continuity, figure-ground - that explain why ambiguous images like Rubin's vase resolve into organized wholes. See Gestalt principles of perception.

1934 - Swedish artist Oscar Reutersvärd independently draws what becomes known as the impossible (Penrose) triangle, decades before it's formally published in the psychology literature.

Mid-20th century: mathematics meets art

1955 - Italian psychologist Gaetano Kanizsa formalizes the illusory-contour effect that becomes known as the Kanizsa triangle.

1958 - Psychiatrist Lionel Penrose and his son, mathematician Roger Penrose, publish a formal paper describing the impossible triangle and Penrose stairs, unaware at the time of Reutersvärd's earlier drawings.

1959 - Vision researcher Béla Julesz, trained as an electrical engineer, develops random-dot stereograms, the technical foundation later commercialized as "Magic Eye" autostereograms.

1961 - M.C. Escher publishes his lithograph Waterfall, building directly on the Penrose stairs concept to depict a continuously flowing impossible waterfall.

1964 - Cognitive scientist Roger Shepard describes the auditory illusion now known as the Shepard tone, an auditory analogue to the same "impossible continuity" idea behind the Penrose stairs.

1976 - Psychologists Harry McGurk and John MacDonald publish the audio-visual McGurk effect.

1979 - Neuropsychologist Richard Gregory documents the café wall illusion, named after a tiled café wall in Bristol, England.

1980 - Psychologist Peter Thompson publishes the Thatcher effect, using a manipulated photograph of Margaret Thatcher to demonstrate how face processing breaks down when inverted.

Late 20th century: the cognitive turn

1995 - MIT vision scientist Edward Adelson creates the checker shadow illusion as a lightness-constancy teaching demonstration.

1997–1999 - Researchers including Ronald Rensink, Daniel Simons, and Christopher Chabris publish a string of studies on change blindness and inattentional blindness, reframing "illusion" research around attention rather than just optics.

21st century: motion, misdirection, and going viral

2003 - Psychologist Akiyoshi Kitaoka publishes the rotating snakes illusion; the same year, animator Nobuyuki Kayahara creates the spinning dancer illusion, which spreads widely online (often accompanied by an inaccurate "left-brain/right-brain" myth that the site's own page on the illusion addresses directly).

2015 - A blurry photo of a dress - photographed by a Scottish bride's mother ahead of the wedding, then reposted online by a family friend who happened to be a folk singer - becomes "the dress" - a genuinely viral color-constancy illusion that briefly divided the internet into two camps and drew serious attention from vision scientists studying individual differences in color perception.

An ongoing story

New illusions and demonstrations are still being discovered and published regularly in vision-science research - this timeline will be extended as the site's Illusion Library grows to cover them.