Phenomenal Transparency at X-Junctions

Abstract

Phenomenal transparency was studied in a stimulus geometry that differs markedly from the conventional Metelli configuration, namely four squares that abut at a common vertex. In case of subjective transparency one perceives either a bipartite square ground overlaid with a uniform transparent rectangle, or a uniform square background overlaid with a pair of mutually orthogonal, uniform, transparent rectangular regions. Thus, the generic interpretations are limited to “left”, “right”, “lower”, or “upper” transparent rectangles or (when no subjective transparency occurs) “mosaic”. All transparent cases are congruent, whereas the Metelli configuration allows distinct Gestalt interpretations. This avoids interactions between Gestalt factors and subjective transparency per se. Formal analysis reveals that—as in Metelli's case—a number of ambiguous cases (eg “left” or “lower”) are to be expected. In the experiment we included these ambiguous cases as additional response categories. Observers who differ markedly on the Metelli configuration are virtually indistinguishable under the quad-square configuration. Moreover, observers reliably categorise the ambiguous instances as such; thus, “multiple transparency” has to be reckoned with as a bona fide percept.

The Art of Transparency

“…The regions where the back and front surfaces cross create X-junctions (one of the two X-junctions is indicated in red in Figure 2a). The luminance relations between the four parts making up the X-junction are closely linked to the perception of transparency and the corresponding depth order (eg, Metelli 1974; Beck et al 1984; Brill 1984; Adelson and Anandan 1990; Gerbino et al 1990; Kersten 1991; Nakayama et al 1990; Plummer and Ramachandran 1993; Anderson 1997; Masin 2006; Singh and Anderson 2002; Koenderink et al 2008; Delogu et al 2010; Koenderink et al 2010). In Figure 2a there is no ambiguity in regard to the depth order of the two squares—ie, the lighter square appears in front of the darker square.…”

There or not there? A multidisciplinary review and research agenda on the impact of transparent barriers on human perception, action, and social behavior

“…Unfortunately, this segregation process does not always succeed. For example, only specific combinations of luminance relations create the perception of transparency in a unique depth order ( Kitaoka, 2005 ; Koenderink et al, 2010 ). Alternatively (see Figure 2B ), perceptions of transparency with an ambiguous depth order due to non-diagnostic luminance relations are possible (creating the impression of so-called bistable transparency; Adelson and Anandan, 1990 ; Anderson, 1997 ; Delogu et al, 2010 ; Fukiage et al, 2014 ).…”

The color appearance of three-dimensional, curved, transparent objects

“…In fact, for the episcotister stimulus, whether a surface will appear transparent or not can be predicted by the relative luminance relationships between adjacent patches, without regard to their absolute luminance [7,9]. In the episcotister model, these relationships must occur at the well-known X-junctions, where they determine perceived depth order [56,11,13,7,33,42,59,67,9,53,77,49,50,15]. However, the episcotister model is not predictive of changes in transparency perception as other factors of the stimulus are varied, such as the mean luminance.…”