Revisitation of the luminance conditions for the occurrence of the achromatic neon color spreading illusion

Abstract

This paper develops the idea (Bressan, 1993) that neon spreading derives from the perceptual scissioning of ordinary assimilation color, a process identical to that occurring with nonillusory colors in phenomenal transparency. It is commonly held that the critical elements in achromatic neon spreading patterns must be of luminance intermediate between that of the embedding lines and of the background. The interpretation of neon spreading on the basis of color scissioning, however, predicts that neon spreading should also be observed for different luminance hierarchies, provided that these are compatible with transparency. This prediction found experimental support in the present work. The results suggest that (1) the widespread notion that chromatic and achromatic neon spreading must be mediated by separate mechanisms is unwarranted; (2) the widespread notion that color spreading in ordinary assimilation patterns and color spreading in neon patterns must be mediated by separate mechanisms is unwarranted; and (3) other than pointing to the way in which the overall organization of a scene affects the mode of color appearance, the neon spreading effect may not convey any extra theoretical relevance.The neon color spreading illusion (van Tuijl, 1975;Varin, 1971) occurs when, in a line drawing, sections of the lines are replaced by segments of a different (chromatic or achromatic) color. This color then appears to spread out of the segments, giving rise to the perception of a slightly tinted transparent surface floating above the pattern; alternatively, the observer has the impression of a unitary, uniformly colored lattice of lines, onto which a differently colored light (or shadow) is cast by an independent outside source.It is commonly held that neon color spreading takes place only if certain figural and luminance conditions occur together. The classic figural prerequisites are the presence of subjective contours, connection and collinearity between the segments and the lines in which they are embedded, and similar stroke widths (Redies & Spillmann, 1981). At the same time, the luminance of the segments must be between the luminances of the external (embedding) lines and of the background (van Tuijl & de Weert, 1979). If these conditions are not satisfied, no neon effect can be perceived; instead, ordinary spreading due to Bezold-type assimilation may be observed, lacking the defining features of neon spreading (van Tuijl & de Weert, 1979; van Tuijl & Leeuwenberg, 1979). In this case, the pattern is not perceived as one unitary line structure, and the difference between the illusorily colored area and its surround is not perceived as due to a veil or a light; rather, one has the impression of two coplanar regions of different colors. On the basis of both the different conditions Correspondence should be addressed to P. Bressan, Dipartimento di Psicologia Generale, Universita di Padova, Piazza Capitaniato 3, 35139 Padova, Italy (e-mail: bressan@unipad.unipd.it). 55 for their occurrence and their different phenom...

Perceptual transparency in neon color spreading displays

“…These results are compatible with both Anderson's (1997) model and the present model. They are, however, seemingly at odds with the data of Bressan (1993b), which showed that balanced perceptual transparency may be observed in some stimuli in which the luminance of the inner elements is not intermediate between the other two luminances in the display. We are not able to give a conclusive explanation of this discrepancy, but it may be noted that the experimental procedure adopted in the present investigation differs from that of Bressan in many respects.…”

Color from Motion: Separate Contributions of Chromaticity and Luminance

“…In this case, we expected that the strength of the · subjective contour would be reduced or that it would not be seen at all. Luminance contrast is known to be critical for the formation of static subjective contours (Frisby and Clatworthy 1975;Gregory 1977), the perception of apparent motion (Ramachandran and Gregory 1978;Cavanagh et al 1985), and the perception of achromatic neon spreading (Bressan 1993 2.2.2 Procedure. Ten stimuli, varying in luminance and chromaticity of the test and surround dots as described above, were presented in random order.…”

Phenomenal Qualities and the Development of Perceptual Integration

“…It is known that 4-month-old infants can perceive transparency in chromatic and moving patterns (Johnson and Aslin, 2000). It has also been demonstrated that the perception of transparency is necessary for the emergence of neon colour spreading (Meyer and Dougherty, 1987;Nakayama, Shimajo, and Ramachandran, 1990;Bressan, 1993aBressan, , 1993b. These data suggest that the perception of transparency and that of neon colour spreading develop together.…”