The Benheim disc is named after the English toymaker Charles Benheim. In 1895, he sold a lid painted with this pattern. When the disc is turned, different arcs of pastel colours become visible.

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The illustration shows an illusionistic figure developed by the German psychologist Walter Ehrenstein in 1941.

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Why does the moon sometimes appear larger in the sky? The size of the moon is an optical perception that is influenced by clouds and the horizon.

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The well-known Jastrow illusion was discovered in 1889 by the American psychologist Joseph Jastrow. The two figures shown are identical, but the lower one appears larger.

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The coffee house illusion is a geometric optical illusion named after the wall pattern of a café in Bristol in the 1970s. In the pattern, the straight dividing lines between the alternating black and white rectangles appear to slope downwards or upwards.

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Babies are already familiar with certain basic social concepts at the age of less than one year. For example, they use body size as an indication of the social hierarchy in society.
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Six circles that seem to rotate in different directions, even though they are completely rigid images.
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Hippo milk is actually pink, i.e. it has a slightly pinkish hue. One cup of pink hippo milk contains about 500 calories.
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The illustration shows three black circles, from each of which a piece of cake has been cut out, through which the white background is visible. The circles are arranged in such a way that the pieces of cake appear to form a triangle.

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The diagram illustrated shows an optical illusion using false perspective. The objects do not appear to be of different sizes depending on their distance from the viewer, as would be the case with true perspective.

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