Müller-Lyer illusion

American  

[muhl-er-lahy-er, myoo-ler-, mil-er-, myl-uhr-lee-uhr] / ˈmʌl ərˈlaɪ ər, ˈmyu lər-, ˈmɪl ər-, ˈmül ərˈli ər /

noun

1. a geometric illusion in which two lines of equal length appear unequal depending on whether angular lines forming arrowheads at each end point toward or away from each other.

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Müller-Lyer illusion British  

/ ˈmuːləˈlaɪə /

noun

1. an optical illusion in which a line with inward pointing arrowheads is seen as longer than an equal line with outward pointing arrowheads

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Etymology

Origin of Müller-Lyer illusion

After Franz-Karl Müller-Lyer (1857–1916), German sociologist, who described the illusion in 1889

Example Sentences

Contemporary anthropologists have further popularized this view, arguing that “the Müller-Lyer illusion is a kind of culturally evolved by-product.”

From Slate • Aug. 24, 2025

Tucked into each of their suitcases was a booklet of drawings, including 12 examples of a prominent figure called the Müller-Lyer illusion.

From Slate • Aug. 24, 2025

There are versions of the Müller-Lyer illusion composed entirely out of curves, or just groups of dots; there’s even a version that uses people’s faces.

From Slate • Aug. 24, 2025

For one thing, lots of other animals see the Müller-Lyer illusion.

From Slate • Aug. 24, 2025

These figures are related to the well-known Müller-Lyer illusion illustrated in Fig.

From Visual Illusions Their Causes, Characteristics and Applications by Luckiesh, Matthew