Michael Vasilyevich Matyushin (Russian: Михаил Васильевич Матюшин; 1861 in Nizhny Novgorod – 14 October 1934 in Leningrad) was a Russian painter and composer, leading member of the Russian avant-garde. In 1910–1913 Matyushin and his wife Elena Guro (1877–1913) were key members of the Union of the Youth, an association of Russian Futurists. Matyushin, a professional musician and amateur painter, studied physiology of human senses and developed his own concept of the fourth dimension connecting visual and musical arts, a theory that he put to practice in the classrooms of Leningrad Workshop of Vkhutein and INHUK (1918–1934) and summarized in his 1932 Reference of Colour (Cправочник по цвету).Matyushin conducted experiments at his Visiology Center (Zorved) to demonstrate that expanding visual sensitivity from retinian optical centers would enable the discovery of "new organic substance and rhythm in the apprehension of space." He tried to teach himself and his students to see with both eyes, each independently, and to widen the field of their vision.