Effects of motion and configural complexity on color transparency perception

Abstract

We tested whether motion and configural complexity affect perceived transparency. A series of five coherent chromatic transformations in color space was applied across a figure: translation, convergence, shear, divergence and rotation. The stimuli consisted of a bipartite or a checkerboard configuration (10 x 10 degrees), with a central static or moving overlay (5 x 5 degrees). Three different luminance conditions (the plane of chromatic transformation oriented toward higher, lower, or equal luminances) were also tested for each of three modulation depths. For each stimulus, the observer judged whether the overlay appeared transparent or not. The main results indicated an interaction between the type of chromatic transformation and stimulus motion and complexity. For example, convergences are judged to appear transparent significantly more often when motion is added for bipartite configurations, or when they are generated in a checkerboard configuration. Surprisingly, shears that have been reported to appear opaque, are more frequently reported to appear transparent with short vector lengths and when combined with motion. Other transformations are also affected by motion, although the effectiveness of figural complexity on transparency seems to depend on both the type of color shifts and the presence of motion. The results indicate that adding motion and stimulus complexity are not necessarily neutral with respect to the chromatic shifts evoking transparency. Thus, studies that have used motion to enhance transparency may yield different results about the color shifts supporting transparency perception from those that did not. The same might be supposed for stimulus complexity under some conditions.

Perceptual scale for transparency: Common fate overrides geometrical and color cues

“…In pointing out the role of certain shape changes in promoting impressions of transparency, particularly for shadows, Metzger (1936) mentions in a footnote that the law of common fate would add a contribution to transparency perception in a movie, but without presenting details of the conditions or evidence, and it is highly unlikely that he was imagining a condition where common fate conflicts with other cues that are voting against transparency. The role we demonstrate for motion defined common fate explains motion enhancing effects in previous studies ( D'Zmura et al, 2000 ; Falkenberg & Faul, 2019 ; Gerardin et al, 2006 ; Khang & Zaidi, 2002a ), but goes beyond them in showing that common fate can override the information provided by junctions, which are otherwise quite powerful factors ( Anderson, 1997 ). In fact, by replacing ellipses with rectangles in the overlaid surface ( Figure 9 ), we demonstrate that, because of common fate, transparency can still be seen despite junction, color, and pattern information all being otherwise incompatible with transparency.…”

Transparent layer constancy is improved by motion, stereo disparity, highly regular background pattern, and successive presentation

“…Gerardin , Roud, Süsstrunk, and Knoblauch (2006) found that the configural complexity of the background figure 1 in Gerbino, 2015, as well as those in panels (c) and (d), are identical with regard to their luminance relations and also fulfill the topological requirements according to Kanizsa (1979), and yet the impression of transparency is clearly weakened in (b) and (d). In panel (a), the impression of a transparent dark bar in front of a white cross is evoked.…”

“…Moving filters were often used with the intention to support the decomposition (D'Zmura, Khang & Zaidi, 2002b;Khang & Zaidi, 2004;Faul & Falkenberg, 2015) but the effectiveness of this manipulation was not tested. Gerardin et al (2006) observed almost 100% correct transparency classification in a condition with moving filters. Apart from an effect due to a boosted decomposition, motion could also improve constancy for other reasons: As noted by Khang and Zaidi (2002b), a moving filter generates a larger sample of overlaid background colors than a static filter, which makes it less probable that single surfaces cause a color bias.…”

“…Motion is assumed to facilitate the decomposition by increasing the effectiveness of figural cues for transparency: By continuously covering and uncovering background regions, new X-junctions are created while good continuation of the background pattern and figural unity of the transparent region are preserved in existing X-junctions (Metelli, 1974;Gerardin et al, 2006;Gerbino, 2015). Moving filters were often used with the intention to support the decomposition (D'Zmura, Khang & Zaidi, 2002b;Khang & Zaidi, 2004;Faul & Falkenberg, 2015) but the effectiveness of this manipulation was not tested.…”

The role of scission in the perception of color and opacity

“…Finally, it should be noted that all of the experiments described herein utilized moving images to assess the perception of chromatic transparency. Gerardin, Roud, Süsstrunk, and Knoblauch (2006) recently showed that motion can cause otherwise non-transparent surfaces to appear transparent, which suggests that the use of motion in our displays could have introduced a confound in assessing the conditions of perceiving transparency in static displays. However, as can be seen directly by viewing both the static and moving versions of our displays, motion never caused a non-transparent display to appear transparent in our stimuli; it merely facilitated the judgment of the color of the target disk.…”