Max WERTHEIMER was born on 15 April 1880 in Prague. His 1912 publication of "Experimental Studies on the Seeing of Motion" he identified the effect of so-called apparent motion (induced by stroboscopic presentation) as the phi phenomenon to stress the psychological reality of the experience in contrast to the older practice of describing the effect as an illusion or mis-perception. Wertheimer taught as a Privatdozent at the University of Berlin (1916-1929). He was one of the founders of Psychologische Forschung (1921) and of its editors (1916-1929). When the Nazis took over in Germany he emigrated to the United States (1933) and joined the faculty of the New School for Social Research, "The University in Exile," in New York City. Among his publications: Productive Thinking. Max Wertheimer died on 12 October 1943 in New Rochelle, New York.

Wolfgang KÖHLER was born on 21 January 1887 in Reval (today Talinn), Estonia. He laid the foundations of Gestalt psychology with Wertheimer and Koffka. He was first a Privatdozent at the University of Frankfurt, 1913-1920 director of the anthropoid research station of the Prussian Academy of Sciences on Tenerife, then professor at the University of Berlin until the Nazi regime came to power. He moved to the United States in 1935 where he was professor of psychology at Swarthmore College (1935-1955). Member of the original editorial board, Psychologische Forschung (1921). 1958-1959: president of the American Psychological Association. Among his publications: The place of value in a world of fact (1938). Wolfgang Köhler died on 11 June 1967 in Enfield, New Hampshire.

Kurt KOFFKA was born on 18 March 1886 in Berlin. In 1911 he was appointed Privatdozent at the University of Giessen, becoming ausserordentlicher professor in 1918. Member of the original editorial board, Psychologische Forschung (1921). In 1924 Koffka went to America, spending successive years as visiting professor at Cornell University and the University of Wisconsin. In 1927 he was appointed William Allen Neilson Research Professor at Smith College. In 1939 Koffka spent a year as visiting professor at Oxford University. Among his publications: The Growth of the Mind (1924), Principles of Gestalt Psychology (1935). Kurt Koffka died at Northampton, Massachusetts, on 22 November 1941.