Interaction of color and geometric cues in depth perception: When does ?red? mean ?near??

Abstract

Luminance and color are strong and self-sufficient cues to pictorial depth in visual scenes and images. The present study investigates the conditions under which luminance or color either strengthens or overrides geometric depth cues. We investigated how luminance contrast associated with the color red and color contrast interact with relative height in the visual field, partial occlusion, and interposition to determine the probability that a given figure presented in a pair is perceived as ''nearer'' than the other. Latencies of ''near'' responses were analyzed to test for effects of attentional selection. Figures in a pair were supported by luminance contrast (Experiment 1) or isoluminant color contrast (Experiment 2) and combined with one of the three geometric cues. The results of Experiment 1 show that the luminance contrast of a color (here red), when it does not interact with other colors, produces the same effects as achromatic luminance contrasts. The probability of ''near'' increases with the luminance contrast of the color stimulus, the latencies for ''near'' responses decrease with increasing luminance contrast. Partial occlusion is found to be a strong enough pictorial cue to support a weaker red luminance contrast. Interposition cues lose out against cues of spatial position and partial occlusion. The results of Experiment 2, with isoluminant displays of varying color contrast, reveal that red color contrast on a light background supported by any of the three geometric cues wins over green or white supported by any of the three geometric cues. On a dark background, red color contrast supported by the interposition cue loses out against green or white color contrast supported by partial occlusion. These findings reveal that color is not an independent depth cue, but is strongly influenced by luminance contrast and stimulus geometry. Systematically shorter response latencies for stronger ''near'' percepts demonstrate that selective visual attention reliably detects the most likely depth cue combination in a given configuration.

Simultaneous Brightness and Apparent Depth from True Colors on Grey: Chevreul Revisited

“…Significant variations in either assimilation or contrast as a function of the luminance contrast of a given color were not found. We are confident that individual differences in equiluminance, although we did not measure them, had little or no effect on our results as the average psychophysical equiluminance for ten or more subjects, selected from the same population as in this study, approaches physical equiluminance (Dresp and Fischer, 2001;Guibal and Dresp, 2004), and differences at the threshold level are unlikely to be relevant here. Configurations with spatially separated background fields, where the inducers are seen as belonging to two different visual objects separated by a gap in the middle, produced significantly higher probabilities of apparent contrast compared with the regrouped configurations, where inducers and background form a single object.…”

“…For a color to be seen as standing out in depth against the background, or to be seen as figure rather than as ground, the difference in luminance or brightness between the color and its background must be strong, as stated in Chevreul's law of contrast. This intuition that differences in luminance would act as a cue to relative depth in the visual field has been confirmed since by psychophysical studies showing that surfaces with the stronger luminance contrast in the two-dimensional plane tend to be perceived as figure rather than as ground, or as nearer to the human observer than surfaces with the weaker luminance contrast (Bugelski, 1967;Dresp et al, 2002;Guibal and Dresp, 2004;O'Shea et al, 1994;Oyama and Yamamura, 1960;Rohaly and Wilson, 1999;Schwartz and Sperling, 1983). Mutual interactions between colors in terms of assimilation and contrast may be linked to their capacity for generating effects of relative depth or, in other words, to the likelihoods that they will be perceived as belonging to the same or as belonging to different surfaces in the visual field (Long and Purves, 2003), a possibility that was not made explicit by Chevreul at the time.…”

Amodal Completion of Boundaries in Coloured Surfaces

“…It would be interesting to evaluate the role of different backgrounds; there are studies which have found an interaction between the effect of colour and the effect of background brightness (Chen & Lin, 2005;Egusa, 1983;Guibal & Dresp, 2004). As already mentioned, Guibal and Dresp (2004), for instance, have observed that the background may change the perception of depth.…”

“…It would be interesting to evaluate the role of different backgrounds; there are studies which have found an interaction between the effect of colour and the effect of background brightness (Chen & Lin, 2005;Egusa, 1983;Guibal & Dresp, 2004). As already mentioned, Guibal and Dresp (2004), for instance, have observed that the background may change the perception of depth. In one of their experiments, studying colour contrast of isoluminant red, green and white, they found that red figures were perceived as 'nearer' when presented on a light background, while white and green figures were seen as 'nearer' with a dark background.…”

Influence of Binocular Disparity in Depth Perception Mechanisms in Virtual Environments

“…Many works [6,[9][10][11] suggested the study of depth perception taking into account both pictorial and stereoscopic (binocular and oculomotor) depth cues.…”