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Combining Achromatic and Chromatic Cues to Transparency
Jacqueline M. Fulvio
Monday, October 17, 2005, 02:00pm - 03:00pm
New York University, Department of Psychology
Perceptual transparency is a unique phenomenon of visual object segmentation in which a single retinal intensity is interpreted as arising from two (or more) material layers separated in depth. Although the perception of transparency has been studied in both achromatic and color displays, the way in which the chromatic and achromatic components of a color display combine to determine percepts of transparency has not been investigated. A series of experiments will be reported that investigated this question using stimulus displays created by taking the superposition of chromatic and achromatic displays. Observers stereoscopically viewed 6-region transparency displays, in which the three inner regions were perceived as a transparent filter floating in front of tripartite background. They adjusted the luminance and color of one of the filter regions in order to maximize the percept of transparency. Observers� setting variability was examined in various conditions, including Luminance only (L), Color only (C), Luminance + transparency-consistent Color (L+C) and Luminance + transparency-inconsistent Color (L+iC). When observers adjusted luminance and color together, the results revealed superior setting reliability in the L+C condition, indicating effective cue combination. However, when observers made separate and iterative settings of the color and luminance attributes of the filter regions, an asymmetry was obtained: color settings were more reliable when the display contained variations in both color and luminance, however, luminance settings were more reliable when the stimulus was purely achromatic (in the absence of color). An investigation of the mean settings revealed that this asymmetry arises from the poorer accuracy in observers� setting of color, which in turn hinders their ability to make precise luminance adjustments. Further tests showed that this asymmetry cannot be attributed to differences in filter-to-background contrast in the chromatic and chromatic components.
Jacqueline M. Fulvio