ABSTRACT
Gestalt psychologists first investigated and developed a theory of object perception. They approached the problem of visual objects in terms of figure-ground segregation and grouping. Rubin (1921) studied the object formation by investigating what appears as a figure and what as a background. He discovered the following well-known figure-ground principles: surroundedness, size, orientation, contrast, symmetry, convexity, and parallelism. According to Rubin, these principles depend on three main phenomenal attributes, belonging to the figure but not to the background:
The contour belongs unilaterally to the figure (see also Pinna, 2010a, 2010b, 2012a; Spillmann and Ehrenstein, 2004), namely it is only the figure which takes on the shape traced by the contour, not the background.
The figure color/brightness shows a way of appearance (Erscheinungsweise, Katz, 1930) similar to a surface, i.e. denser than the same physical color/brightness of the background that is, instead, perceived completely transparent and empty.
The figure is always seen placed in depth, closer to the observer than the background.
