Also known as arrowhead illusion. The eponym Müller-Lyer illusion refers to the German sociologist Franz Carl Müller-Lyer (1857-1916), who described the concomitant phenomenon in or shortly before 1889. This phenomenon consists of a * geometric-optical illusion characterized by a perceived difference in length between two mathematically identical lines, one of which is bounded by a pair of arrowheads pointing towards each other and the other by a pair pointing away from each other. The line with the arrowheads pointing away from each other is consistently perceived as being shorter in length than the one with the arrowheads pointing towards each other. The Müller-Lyer illusion is considered a physiological phenomenon that arises as a consequence of the inherent properties of the visual system. As a consequence, it tends to be classified as a * physiological illusion. Following the publication of Müller-Lyer's original paper, many similar illusions have been described in relation to alternative configurations of lines.
References
Bermond, B., van Heerden, J. (1996). The Müller-Lyer illusion explained and its theoretical importance reconsidered. Biology and Philosophy, 11, 321-338.
Müller-Lyer, F.C. (1889). Optische Urteilstäuschungen. Dubois-Reymonds Archiv für Anatomie und Physiologie, Supplement Volume, 263-270.
Rutten, F.J.Th. (1929). Psychologie der waarnem-ing. Een studie over gezichtsbedrog. Thesis, University of Utrecht.
Dictionary of Hallucinations. J.D. Blom. 2010.