Our motivation was to further explore infant's ability to perceptually integrate fragmented image features based on purely static pictorial cue. In the present study we use new Kanizsa-type configurations that do not contain confounding influences identified with the previous studies. The main stimulus configuration, illustrated in
Figure 2a, is a novel mixed-polarity modification of the configuration that was first devised by Kanizsa (see
Figures 2b and
2c). In these configurations, a missing quarter segment of each circular inducer (as in a standard illusory contour configuration) has been replaced by a uniformly colored quarter segment. While the standard Kanizsa configurations generate a vivid percept of an occlusion by an opaque surface, the same configurations with embedded colored sectors can result in a vivid perception of a transparent, faintly colored, “misty” surface that is bounded by illusory contours (Kanizsa,
1955; Varin,
1971; Ware,
1980). These types of stimuli have also been known as the neon color spreading configurations or neon-Kanizsa configurations, directly linking the phenomena of illusory contours, neon spreading and perceptual transparency (Nakayama, Shimojo, & Ramachandran,
1990). While the original demonstrations of neon spreading consist of inducing segments that are all of the same color/luminance and contrast polarity, we use mixed polarity inducers to ensure that perception of illusory transparent surface is not confounded with perception of induced brightness. The induced brightness in neon-Kanizsa configurations is evident by comparing the central gray regions in
Figures 2b and
2c which appear darker and lighter respectively. In fact, according to the influential models both illusory brightness (in illusory contours) and color spreading (in neon color spreading displays) hinge on the very same neurophysiological structure, i.e., the feature contour system: they are both thought to depend upon the like-contrast polarity relationships between the inducers (Grossberg & Mingolla,
1985; Grossberg & Yazdanbakhsh,
2005; Nakayama et al.,
1990). The most important feature of the novel mixed polarity Kanizsa configuration lies in its ability to dissociate a vivid perception of an illusory transparent surface from that of a uniform color spreading These configurations have also been used to probe the mechanisms underlying different forms of perceptual completion that are closely matched in the structure of local features (Spehar,
2003; Spehar & Halim,
2008).