Müller-Lyer illusion

The Müller-Lyer illusion is an optical illusion consisting of three stylized arrows. When viewers are asked to place a mark on the figure at the midpoint, they invariably place it more towards the 'tail' end. The illusion was devised by Franz Carl Müller-Lyer (1857–1916), a German sociologist, in 1889.Although Gregory's intuition about the empirical significance of the Müller-Lyer stimulus points in the right general direction (i.e., an explanation based on past experience with the sources of such stimuli), convex and concave corners contribute little if anything to the Müller-Lyer effect. The Müller-Lyer illusion is an optical illusion consisting of three stylized arrows. When viewers are asked to place a mark on the figure at the midpoint, they invariably place it more towards the 'tail' end. The illusion was devised by Franz Carl Müller-Lyer (1857–1916), a German sociologist, in 1889.