Wertheimer's (1923, Psychologische Forschung 4 301–350) idea that the perceptual world is articulated according to factors of organisation is widely acknowledged as one of the most original contributions of Gestalt psychology and stands as a milestone in the history of vision research. An inquiry focused on the forerunners of some of Wertheimer's factors of perceptual organisation is documented here. In fact, in 1900 Schumann described grouping by proximity and by vertical symmetry, and in 1903 G E Müller identified the factors of sameness/similarity and contour. Other authors contributed to the early description of these factors, such as Rubin, who in 1922 originally illustrated grouping by similarity. Even though Wertheimer himself granted these authors due recognition, later psychologists have paid little attention to their contributions. Some possible reasons for this negligence are briefly discussed.
Goethe and Gestalt Psychology: A Commonplace Revisited
