Who is the founder of Gestalt Psychology?

Concept: Gestalt psychology is a school of thought holding that the mind perceives whole patterns and configurations ("Gestalten") rather than assembling isolated sensory parts — summarised by the principle that "the whole is different from the sum of its parts." It emerged in early 20th-century Germany as a reaction against structuralism's part-by-part analysis of experience.

Application: Max Wertheimer is credited as the founder of Gestalt psychology. In 1912 he published his study of the phi phenomenon (the illusion of movement created by two alternately flashing stationary lights), which became the founding demonstration of the Gestalt approach. Together with his close collaborators Wolfgang Köhler and Kurt Koffka, Wertheimer established Gestalt psychology as a distinct school centred at the University of Frankfurt and later spread through the Berlin school of psychology.

Cross-check / Contrast: None of the other names is credited as a founder of the movement:

• Franz Brentano worked a generation earlier on act psychology and phenomenology (the study of mental acts), which influenced later psychologists but is a separate tradition from Gestalt theory.

• Edgar Rubin is known for the figure–ground concept (e.g. the Rubin's vase illusion) — an important perceptual finding that Gestalt psychologists later drew on, but he did not found the school himself.

• Kurt Lewin trained within the Gestalt tradition and later founded field theory and social/group psychology, but he is remembered as a later Gestalt-influenced theorist, not as one of the movement's original founders.

Hence, Max Wertheimer is the founder of Gestalt Psychology.