Koehler(1887~ 1967) German-American psychologist. One of the representatives of Gestalt psychology. Born in Tallinn on January 21, 1887, and died in Enfield, New Hampshire, USA on June 11, 1967. In 1909, he received a doctorate in philosophy from the University of Berlin. In 1921, he became a professor at the University of Berlin and director of the Institute of Psychology. In 1912, he and K. Kovka participated in the experimental study of M. Wertheimer's kinetic phenomena, which together laid the foundation of Gestalt psychology. He settled in the United States in 1935 and was elected president of the American Psychological Association in 1959. In the book "The Wisdom of the Apes" published in 1917, he described experiments on animal problem-solving and proposed the theory of epiphany learning. In terms of perception, he put forward the laws of graphic perception, which strongly supported the Gestalt theory of perception. His books include "The Place of Value in the Factual World", "Dynamics of Psychology", "Gestalt Psychology" and so on.

Gestalt psychology holds that the most fundamental characteristic of psychological phenomena is the structural or holistic nature embodied in conscious experience.