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Müller-Lyer illusion
Müller-Lyer illusion The Müller-Lyer illusion is a classic geometric illusion in which a line appears to have a different length depending on whether its ends are marked like arrow tails or arrowheads.
The Müller-Lyer illusion is a classic geometric illusion in which a line appears to have a different length depending on whether its ends are marked like arrow tails or arrowheads. In other words, the perceived length changes even though the physical line itself does not.