The café wall illusion (also known as the Münsterberg illusion or the kindergarten illusion) is a
geometrical-optical illusion in which the
parallel straight dividing lines between staggered rows with alternating dark and light rectangles (such as bricks or tiles) appear to be sloped, not parallel as they really are.
The phenomenon has been rediscovered several times. A version of the illusion was first described by
Hugo Münsterberg
Hugo Münsterberg (; ; June 1, 1863 – December 16, 1916) was a German-American psychologist. He was one of the pioneers in applied psychology, extending his research and theories to Industrial organization, industrial/organizational (I/O), legal ...
in 1894,
then described as the 'kindergarten illusion' in 1898 by A. H. Pierce, and under its current name in 1973 by
Richard Gregory
Richard Langton Gregory, (24 July 1923 – 17 May 2010) was a British psychologist and Professor of Neuropsychology at the University of Bristol.
Life and career
Richard Gregory was born in London. He was the son of Christopher Clive Lan ...
. According to Gregory, this effect was observed by a member of his laboratory, Steve Simpson, in the tiles of the wall of a café at the bottom of St Michael's Hill,
Bristol
Bristol () is a City status in the United Kingdom, cathedral city, unitary authority area and ceremonial county in South West England, the most populous city in the region. Built around the River Avon, Bristol, River Avon, it is bordered by t ...
.
In the construction of the illusion often each "brick" is surrounded by a layer of "mortar" intermediate between the dark and light colours of the "bricks".
In attempts at its deconstruction, the illusion was ascribed largely to the
irradiation illusion (apparent greater size of a white area than of a black one),
and the image disappears when black and white are replaced by different colours of the same brightness. But a component of the illusion remains even when all optical and retinal components are factored out. Contrast polarities seem to be the determining factor in the tilt's direction.
See also
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Visual illusions
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Geometrical-optical illusions
Geometrical–optical are visual illusions, also optical illusions, in which the geometrical properties of what is seen differ from those of the corresponding objects in the visual field.
Geometrical properties
In studying geometry one concentra ...
References
External links
An interactive version of the Café wall illusion that allows for adjusting the offset and turning the black boxes into white boxesAn animated proof that the horizontal lines are parallel and straightThe original café in Bristol on Google Maps Street View
Optical illusions
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