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In this work it is suggested that color induces phenomenal wholeness, part-whole organization and fragmentation. The phenomenal wholeness subsumes the set of its main attributes: homogeneity, continuity, univocality, belongingness, and oneness. If color induces wholeness, it can also induce fragmentation. Therefore, in order to understand the role played by color within the process of part-whole organization, color is used both as a wholeness and as a fragmentation tool, thus operating synergistically or antagonistically with other wholeness processes. Therefore, color is expected to influence figure-ground segregation, grouping, shape formation and other visual processes that are related to the phenomenal wholeness. The purpose of this study is to rate the influence of color in inducing whole and part-whole organization and, consequently, in determining the perception of figure-ground segregation, grouping, shape formation, numerousness evaluation and time reading. We manipulated experimental conditions by using equiluminant colors to favor or break (parcel-out) the wholeness of objects like geometrical composite figures and words. The results demonstrated that color is aimed, among other psychological and biological purposes, at: (1) relating each chromatic component of an object, thus favoring the emergence of the whole object; (2) eliciting a part-whole organization, whose components are interdependent; (3) eliciting fragments and then breaking up the whole and favoring the emergence of single components. Wholeness, part-whole organization and fragmentation can be considered as three further purposes of color., (© 2010 The Authors, Ophthalmic and Physiological Optics © 2010 The College of Optometrists.)

The purpose of this work is to study how the brain solves perceptual antinomies, induced by the watercolor illusion in the color and in the figure-ground segregation domain, when they are present in different parts of the same object. The watercolor illusion shows two main effects: a long-range coloration and an object-hole effect across large enclosed areas (Pinna, 1987, 2005, 2008a, b; Pinna and Grossberg, 2005; Pinna et al., 2001). This illusion strongly enhances the unilateral belongingness of the boundaries (Rubin, 1915) determining grouping and figure-ground segregation more strongly than the well-known Gestalt principles. Due to the watercolor illusion, both the figure and the background assume new properties becoming, respectively, a bulging object and a hole both with a 3-D volumetric appearance (object-hole effect). When the coloration and the object-hole effects induced by the watercolor illusion are opposite (antinomic) within different portions of the same shape, some questions emerge: Do the antinomies split the shape in two parts (a half shape appears as an object and the other half as a hole) or are they solved through a new emergent perceptual result beyond the single effects? Is there a predominance of one component over the other that is less visible or totally invisible? What is perceptible and what is invisible? Is there a wholeness process under conditions where perceptual antinomies coexist? By imparting motion to a watercolored object that gradually should become a hole while overlapping another object placed behind, is the wholeness of the watercolor object weakened or reorganized in a new way? The results of phenomenological experiments suggested that the antinomies tend to be solved through two complement processes of phenomenal wholeness and partialness. These processes are explained in the light of the FACADE neural model of 3-D vision and figure-ground separation (Grossberg, 1994, 2003), notably of how complementary cortical boundary and surface representations interact with spatial attention to generate conscious percepts of 3-D form and motion.

The watercolor illusion is a long-range color assimilation (coloration effect) imparting a figure-ground segregation (figural effect) across large enclosed areas (B. Pinna, 1987; B. Pinna, G. Brelstaff, & L. Spillmann, 2001; B. Pinna, L. Spillmann, & J. S. Werner, 2003; B. Pinna, J. S. Werner, & L. Spillmann, 2003). The watercolored figure has a very poorly reversible or univocal figure-ground segregation and strongly enhances the unilateral belongingness of the boundaries (E. Rubin, 1915), a principle stating that the boundaries belong only to the figure and not to the background. The figural effect determines grouping and figure-ground segregation more strongly than the well-known Gestalt principles. Under watercolor conditions both the figure and the background assume new properties becoming respectively bulging object and hole both with a 3-D volumetric appearance (object-hole effect). Our purposes were: (i) to demonstrate that the hole induced by the watercolor illusion has unique figural properties comparable to those of the object and not present in the background induced by the known figure-ground principles; (ii) to demonstrate a dissociation of the object-hole effect from the coloration one; (iii) to demonstrate that the object-hole effect depends on a new principle. This was psychophysically tested by weakening (ungrouping) the whole figural organization of the watercolor illusion, i.e. by imparting motion to only some components of a stimulus, while other components remain stationary. The results showed that (i) subjects perceived moving holes more strongly than moving figures or objects enlarging and shrinking. (ii) Paradoxically, moving holes appear more as figures than the bulging surfaces. (iii) When motion was imparted to components that while stationary were perceived as objects, their figurality is further enhanced (summation effect). (iv) When object-hole and coloration effects were dissociated no significant difference compared to illusory colored conditions was reported. Coloration can be considered independent from the object-hole effect of the watercolor illusion. The object-hole effect may depend on the "asymmetric luminance contrast principle" (B. Pinna, 2005).

The watercolor illusion is a color spreading effect at long-range diffusing from a thin colored contour juxtaposed to a chromatic one of higher contrast and a object-hole effect across a large area (Pinna, 1987; Pinna et al., 2001, 2003; Pinna & Reeves, 2006). The watercolored figure appears evenly colored by an opaque light veil of chromatic tint (coloration effect), with a clear surface color property spreading from the lighter contour. At the same time, the watercolored figure manifests a strong figure-ground organization and a solid figural appearance comparable to a bas-relief illuminated from the top (object-hole effect). It appears similar to a rounded surface segregated in depth, which extends out from the flat surface. The complementary region appears as a hole or empty space. The phenomenal properties of coloration and object-hole effects raise some questions. Can the two effects be considered relatively independent? Under what conditions can a possible dissociation occur? How does the dissociation of one effect, say the coloration, influence the object-hole effect and vice versa? To answer these questions two new effects related to the watercolor illusion were psychophysically studied: (1) the "uneven watercolor," based on a modified watercolor figure without volumetric and three-dimensional properties but with a strong coloration effect and (2) the "watercolor surface capture," where oblique lines within a watercolor figure appear bulging, curved in depth and segregated from those that are perceived as placed in the background or perceived through holes. The results of two experiments suggest that the coloration effect can be dissociated from the object-hole one. These results are discussed in the light of a simple summation hypothesis of the underlying effects composing the whole figurality. This hypothesis can suggest further investigation both in the phenomenal and in the neurophysiological domain.