Figure–ground organization is a type of perceptual grouping that is a vital necessity for recognizing objects through vision. In Gestalt psychology it is known as identifying a figure from the background. For example, black words on a printed paper are seen as the "figure", and the white sheet as the "background". Gestalt psychology The Gestalt theory was founded in the 20th century in Austria and Germany as a reaction against the associationist and structural schools’ atomistic orientation. In 1912, the Gestalt school was formed by Max Wertheimer, Wolfgang Köhler, and Kurt Koffka. The word "gestalt" is a German word translated to English as "pattern" or "configuration." Gestalt concepts can also be referred to as "holism." Gestalt Psychologists were attempting to humanize what was considered a sterile approach. Gestalt psychology establishes that the whole of anything is greater than its parts. The concepts explored by Wertheimer, Köhler, and Koffka in the 20th century established the foundation for the modern study of perception. "The Gestalt concept is that "not only movement, or process as such, but also the direction and distribution of process is determined dynamically by interaction." Sensory organization is not dependent upon isolated stimuli and local stimulation, but upon the relative properties of stimulation and the dynamical context." Wertheimer described holism as the “fundamental formula” of Gestalt psychology: “There are wholes, the behavior of which is not determined by that of their individual elements, but where the part-processes are themselves determined by the intrinsic nature of the whole." Examples The Rubin vase faces–vase drawing that Danish psychologist Edgar Rubin described exemplifies one of the key aspects of figure–ground organization, edge-assignment and its effect on shape perception. In the faces–vase drawing, the perceived shape depends critically on the direction in which the border (edge) between the black and white regions is assigned. If the edges between the black and white regions are assigned inward, then the central white region is seen as a vase shape in front of a black background. No faces are perceived in this case. On the other hand, if the edges are assigned outward, then the two black profile faces are perceived on a white background, and no vase shape is perceived. The human visual system will settle on either of the interpretations of the Rubin vase and alternate between them, a phenomenon known as multistable perception. Functional brain imaging shows that, when people see the Rubin