Max Wertheimer (April 15, 1880 – October 12, 1943) was an Austro-Hungarian-born psychologist who was one of the three founders of Gestalt psychology, along with Kurt Koffka and Wolfgang Köhler. He is known for his book, Productive Thinking, and for conceiving the phi phenomenon as part of his work in Gestalt psychology.Wertheimer obtained his PhD in 1904 under Oswald Külpe, and then began his intellectual career teaching in Frankfurt.