On the role of figural organization perceptual transparency

Abstract

. In Metelli (1974)made an important contribution by identifying order and magnitude restrictions for a pattern of intensities and showing that when they are satisfied the perception of transparency readily occurs. These restrictions were derived from a physical model of transparency. We argue that the visual system does not use intensity information to compute indices of transmittance and reflectance analogous to what an optical engineer might do in describing a physical instance of transparency. Rather, a lightness pattern affects perceptual transparency, just as geometric properties do, through processes that impose an organization on sensory information rather than through processes that recover quantitative descriptions. In the absence of depth cues, such as stereopsis and motion parallax, the perception of transparency occurs when the lightness relations in a pattern favor the perception of a continuous boundary across x-junctions. We present evidence for two kinds of violations of the order and magnitude restrictions: simple and strong. Transparency judgments, although reduced in number, still occur for simple violations of the order and the magnitude restrictions. Transparency judgments occur relatively infrequently for strong violations. A physical model of transparency fails to capture the difference between simple and strong violations of the order and magnitude restrictions. We discuss (1) the basis for differentiating between simple and strong violations of the order and magnitude restrictions, (2) the effect simple and strong violations have on the perception of transparency, and (3)the occurrence of transparency with and without color constancy (i.e., the color seen through the transparent surface looks or fails to look the same as the color seen directly).where a is the proportion of light reflected from surface A (corresponding to the areal fraction occupied by the open sector of the episcotister), I-a is the proportion of light reflected from the blades of the episcotister (corresponding to the areal fraction occupied by the blades of the episcotister), a is the reflectance of surface A, b is the reflectance of surface B, and e is the reflectance of the episcotister blades. Solving Equations 1 and 2 for a and e yields Metelli (1974) proposed a model for the perception of transparency based on a physical model of transparency. Beck, Prazdny, and Ivry (1984) reported findings that challenge the adequacy of the Metelli model. The implications of these findings were not made fully clear in the earlier paper; thus, in this paper, we present the Metelli model, the difficulties we see with the Metelli model, an alternative model based on processes of figural organization, and an experiment that further clarifies the conditions for the perception of transparency.This research was supported by National Science Foundation Grant INT-8418187 andby Air Force of Scientific Research Grant AFOSR-85-0359. Requests for reprints should be sent to Iacob Beck, Department of Psychology, University of Oregon, Eugene,...

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

“…Although physical transparency is impossible if either condition is infringed, Beck and Ivry (1988) found that, for a certain class of violations, perceived transparency was still reported. In general, the frequency of transparency judgments tended to vary inversely with the magnitude of the violation.…”

Perceptual transparency in neon color spreading displays

“…In the achromatic case, this means that ,(A) < ,(P) < ,(B) or ,(B) < ,(P) < ,(A). Since these relations are invariant with respect to monotonic transformations of ,, the same predictions follow if one assumes that perceived lightness, as opposed to luminance, is the relevant variable, which has been proposed by Beck and co-workers (Beck & Ivry, 1988;Beck, Prazdny, & Ivry, 1984). It is also apparent that this model makes exactly the same predictions as Anderson's (1997) model for achromatic (and isochromatic) stimuli-namely, that the region P <Q should look transparent whenever the luminance of P is between the luminances of A and B.…”

Reply to Beck and Ivry

“…Metelli (1985) and Metelli, Da Pos, and Cavedon (1985) replied to Beck et al (1984). Beck and Ivry (1988) reported further findings that challenged again the adequacy of the Metelli model.…”

“…I shall not defend his model in general, because I hold a different point of view on phenomenal transparency (Masin, 1984a(Masin, , 1984bMasin & Gardonio, 1985). Here I comment only on a phenomenon mentioned as Point 3 in the last sentence of the abstract of Beck and Ivry's (1988) paper: "(3) the occurrence of transparency with and without color constancy (i.e., the color seen through the transparent surface looks or fails to look the same as the color seen directly)." Beck and Ivry (1988) give the reader the clear impression, particularly in Table 1, that failure of "color constancy" in transparency is a serious problem for the Metelli model.…”

“…Here I comment only on a phenomenon mentioned as Point 3 in the last sentence of the abstract of Beck and Ivry's (1988) paper: "(3) the occurrence of transparency with and without color constancy (i.e., the color seen through the transparent surface looks or fails to look the same as the color seen directly)." Beck and Ivry (1988) give the reader the clear impression, particularly in Table 1, that failure of "color constancy" in transparency is a serious problem for the Metelli model. The idea is also conveyed that failure of "color constancy" is a phenomenon first noted by them: " Beck et al (1984) suggested that the perception of transparency with a stationary pattern can also occur without color constancy" (Beck & Ivry, 1988, p. 588).…”