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 Car ...

is named after him.

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 ...

Grand Duchy of Baden The Grand Duchy of Baden () was a German polity on the east bank of the Rhine. It originally existed as a sovereign state from 1806 to 1871 and later as part of the German Empire until 1918. The duchy's 12th-century origins were as a Margravia ...

. He studied medicine at the Universities of

Strasbourg Strasbourg ( , ; ; ) is the Prefectures in France, prefecture and largest city of the Grand Est Regions of France, region of Geography of France, eastern France, in the historic region of Alsace. It is the prefecture of the Bas-Rhin Departmen ...

Bonn Bonn () is a federal city in the German state of North Rhine-Westphalia, located on the banks of the Rhine. With a population exceeding 300,000, it lies about south-southeast of Cologne, in the southernmost part of the Rhine-Ruhr region. This ...

, and

Leipzig Leipzig (, ; ; Upper Saxon: ; ) is the most populous city in the States of Germany, German state of Saxony. The city has a population of 628,718 inhabitants as of 2023. It is the List of cities in Germany by population, eighth-largest city in Ge ...

. He also studied psychology and sociology at the Universities of

Berlin Berlin ( ; ) is the Capital of Germany, capital and largest city of Germany, by both area and List of cities in Germany by population, population. With 3.7 million inhabitants, it has the List of cities in the European Union by population withi ...

Vienna Vienna ( ; ; ) is the capital city, capital, List of largest cities in Austria, most populous city, and one of Federal states of Austria, nine federal states of Austria. It is Austria's primate city, with just over two million inhabitants. ...

Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...

and

London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...

. In 1888 he entered into private practice in

Munich Munich is the capital and most populous city of Bavaria, Germany. As of 30 November 2024, its population was 1,604,384, making it the third-largest city in Germany after Berlin and Hamburg. Munich is the largest city in Germany that is no ...

. Müller-Lyer's speculations on the evolution of the role of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

in human society received prominent mention in

Bertrand Russell Bertrand Arthur William Russell, 3rd Earl Russell, (18 May 1872 – 2 February 1970) was a British philosopher, logician, mathematician, and public intellectual. He had influence on mathematics, logic, set theory, and various areas of analytic ...

's 1924 essay "Styles in Ethics," which argued for the relativity and impermanence of moral standards.Egner and Denonn, eds., ''The Basic Writings of Bertrand Russell''
Ch.40, p.345

Simon & Schuster Simon & Schuster LLC (, ) is an American publishing house owned by Kohlberg Kravis Roberts since 2023. It was founded in New York City in 1924, by Richard L. Simon and M. Lincoln Schuster. Along with Penguin Random House, Hachette Book Group US ...

, 1961. The

optical illusion In 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 varie ...

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 la ...

. 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 Stella Browne (9 May 1880 – 8 May 1955) was a Canadian-born British feminist, socialist, sex radical, and birth control campaigner. She was one of the primary women in the fight for women's right to control and make decisions regarding their ...

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

External links

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