Franz Carl Müller-Lyer, born Francis Xavier Hermann Müller (5 February 1857 - 29 October 1916) was a German psychologist and sociologist.
''Deutsche Biographie'' The

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 tend to place it more towards the "tail" end. The illusion was devised by Franz Carl ...

is named after him.Müller-Lyer, FC (1894), "Über Kontrast und Konfluxion", ''Zeitschrift für Psychologie'', IX p 1 / X p 421.

Life

Müller-Lyer was born in

Baden-Baden Baden-Baden () is a spa town in the states of Germany, state of Baden-Württemberg, south-western Germany, at the north-western border of the Black Forest mountain range on the small river Oos (river), Oos, ten kilometres (six miles) east of the ...

. He studied medicine at the Universities of

Strasbourg Strasbourg (, , ; german: Straßburg ; gsw, label=Bas Rhin Alsatian, Strossburi , gsw, label=Haut Rhin Alsatian, Strossburig ) is the prefecture and largest city of the Grand Est region of eastern France and the official seat of the Eu ...

Bonn The federal city of Bonn ( lat, Bonna) is a city on the banks of the Rhine in the German state of North Rhine-Westphalia, with a population of over 300,000. About south-southeast of Cologne, Bonn is in the southernmost part of the Rhine-Ruhr r ...

, and

Leipzig Leipzig ( , ; Upper Saxon: ) is the most populous city in the German state of Saxony. Leipzig's population of 605,407 inhabitants (1.1 million in the larger urban zone) as of 2021 places the city as Germany's eighth most populous, as wel ...

. He also studied psychology and sociology at the Universities of

Berlin Berlin ( , ) is the capital and largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's most populous city, according to population within city limits. One of Germany's sixteen constitue ...

Vienna en, Viennese , iso_code = AT-9 , registration_plate = W , postal_code_type = Postal code , postal_code = , timezone = CET , utc_offset = +1 , timezone_DST ...

Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...

and

London London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has been a majo ...

. In 1888 he entered into private practice in

Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the States of Germany, German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the List of cities in Germany by popu ...

. The

optical illusion Within visual perception, an optical illusion (also called a visual illusion) is an illusion caused by the visual system and characterized by a visual perception, percept that arguably appears to differ from reality. Illusions come in a wide v ...

he described in 1889 involves the perception of the length of a line when the ends are capped by

chevrons Chevron (often relating to V-shaped patterns) may refer to: Science and technology * Chevron (aerospace), sawtooth patterns on some jet engines * Chevron (anatomy), a bone * '' Eulithis testata'', a moth * Chevron (geology), a fold in rock l ...

. Diverging chevrons seem to make the line longer when compared with converging chevrons. There are numerous similar geometrical illusions known now.

Works

* ''Phasen der Kultur und Richtungslinien des Fortschritts'', 1908. Translated by Elizabeth Coote Lake & Hilda Amelia Lake as ''The history of social development'', London: G. Allen & Unwin Ltd, 1920. * ''Der sinn des lebens und die wissenschaft. Grundlinien einer volksphilosophie'', München: Lehman, 1910. * ''Die Familie'', München: J.F. Lehmann, 1911. Translated by Stella Browne as ''The family'', London: G. Allen & Unwin, 1931. * ''Formen der Ehe, der Familie und der Verwandstschaft'', Müchen: J.F. Lehman, 1911. * ''Phasen der Liebe : eine Soziologie des Verhältnisses der Geschlechter'', München: A. Langen, 1913. Translated by Isabella Wigglesworth as ''The evolution of modern marriage: a sociology of sexual relations'', London: George Allen & Unwin Ltd., 1929. * ''Soziologie der leiden'', München: A. Langen, 1914. * ''Die Zähmung der Nornen'', 2 vols., München: Albert Langen, 1918-1924. Edited by Betty Müller-Lyer.

References

{{DEFAULTSORT:Muller-Lyer, Franz Carl 1857 births People from Baden-Baden 1916 deaths German psychologists German sociologists German male writers