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Characterizing visual asymmetries in contrast perception using shaded stimuli.

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Chacón Gómez, José and Castellanos López, Miguel Ángel and Serrano Pedraza, Ignacio (2015) Characterizing visual asymmetries in contrast perception using shaded stimuli. Journal of vision, 15 (11). pp. 1-14. ISSN 1534-7362

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Official URL: http://dx.doi.org/doi:10.1167/15.16.11



Abstract

Previous research has shown a visual asymmetry in shaded stimuli where the perceived contrast depended on the polarity of their dark and light areas (Chacón, 2004). In particular, circles filled out with a top-dark luminance ramp were perceived with higher contrast than top-light ones although both types of stimuli had the same physical contrast. Here, using shaded stimuli, we conducted four experiments in order to find out if the perceived contrast depends on: (a) the contrast level, (b) the type of shading (continuous vs. discrete) and its degree of perceived three-dimensionality, (c) the orientation of the shading, and (d) the sign of the perceived contrast alterations. In all experiments the observers' tasks were to equate the perceived contrast of two sets of elements (usually shaded with opposite luminance polarity), in order to determine the subjective equality point. Results showed that (a) there is a strong difference in perceived contrast between circles filled out with luminance ramp top-dark and top-light that is similar for different contrast levels; (b) we also found asymmetries in contrast perception with different shaded stimuli, and this asymmetry was not related with the perceived three-dimensionality but with the type of shading, being greater for continuous-shading stimuli;


Item Type:Article
Uncontrolled Keywords:Shaded stimuli, Perceived contrast, Contrast asymmetries, Shape from shading
Subjects:Medical sciences > Psychology > Experimental psychology
Medical sciences > Psychology > Perception
Medical sciences > Optics > Visual perception
ID Code:36264
Deposited On:08 Apr 2016 11:48
Last Modified:20 Apr 2016 14:35

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