Gestalt psychology is a theory of the mind that was first developed in the Berlin School of psychology. Carl Stumpf founded the Berlin School of Experimental Psychology in 1893. Among his pupils were Max Wertheimer, Kurt Kafka, Wolfgang Köhler, and Kurt Lewin. When Köhler became director of the Berlin School in 1922, it became the center of Gestalt psychology.
Max Wertheimer first suggested that gestalt is perceptually primary, that the mind forms a global whole and conceives of things as a unified object, and that the whole is something other than the sum of its parts. Gestalt psychology is often summed up by the phrases: The whole is other than the sum of its parts, which was coined by Koffka. According to Gestalt theory, the mind understands external stimuli as whole; not the sum of parts, and these wholes are grouped by the mind.
The four key principles of a gestalt system are emergence, reification, multistability and invariance. Emergence is the process of forming complex patterns from simpler rules. Reification is when the mind perceives more explicit spatial information than the senses receive. Multistability is the perceptual experience that moves back and forth between two interpretations: for example, does one see a vase, or two human faces? Invariance is a type of perception where geometrical objects are recognized regardless of rotation, translation, or scale.