Max Wertheimer

Max Wertheimer (Prague, 15 April 1880 – New Rochelle, New York, 12 October 1943) was a psychologist who was one of the three founders of Gestalt psychology, with Kurt Koffka and Wolfgang Köhler.
From 1929 to 1933, Wertheimer was a professor at the University of Frankfurt. When Adolf Hitler became Chancellor of the Third Reich in 1933, it became apparent to Wertheimer that he must leave Germany. In the end, he accepted an offer to teach at The New School in New York.
In New York he continued to investigate problem-solving, or what he preferred to call “productive thinking". The relationship between the book and his earlier work was this: all the problems in the book except one could be solved by considering geometric diagrams. In other words, they were partly visual in essence, and could be represented and partly solved visually. That thread ran through much of the gestalt work.
Wertheimer completed the book (his only book) in late September 1943, and died just three weeks later of a heart attack. Wertheimer was buried in Beechwood Cemetery in New Rochelle, New York.
Phi phenomenon.
The phi phenomenon is an optical illusion described by Wertheimer in 1912, in which the persistence of vision was exploited by the cinema film, applied by Hugo Münsterberg in 1916. This optical illusion is based in the principle that the human eye is capable of perceiving movement from pieces of information, for example, a succession of images. In other words, from a slideshow of a group of frozen images at a certain speed of images per second, we observe constant movement.