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San-Yuan Lin, Su-Ling Yeh; Amodal completion without awareness. Journal of Vision 2014;14(10):1057. doi: 10.1167/14.10.1057.
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The extent of unconscious processing is under extensive investigation. Yet, it remains unknown whether amodal completion—a fundamental process that completes spatially discontinuous objects by illusory contours and surfaces—also occurs without awareness. We examined this by adopting the double-rectangle cueing paradigm (Egly, Driver, & Rafal, 1994) with a temporal-order judgment (TOJ) task. Specifically, an occluder and four squares (served as the parts of the two to-be-completed rectangles) were presented in separate eyes in a continuous flash suppression paradigm so that the stimulus in one eye is suppressed from consciousness. The cue and the subsequently presented two concurrent targets for the TOJ task were shown within the four squares. If amodal completion did occur to form two rectangles from the four squares and the occluder, the proportion of prior entry for the two targets would differ in the TOJ task. Furthermore, to ensure unconscious processing, trials with reports of seeing the suppressed stimuli were excluded. In Experiment 1, a reversed same-object advantage—target on the uncued rectangle was judged to appear earlier more often than target on the cued rectangle—was found in such arrangement. This is also true when the stimuli swapped—the occluder became visible and the squares invisible (Experiment 2). The reversed same-object advantage suggests that amodal completion occurs but may be weak to constrain object-based attention to prioritize within-object information in the tug-of-war of "within-object or between-object selection" when the display is only partly seen. To test this, in Experiment 3, we increased the strength of the object representation by inducing amodal completion at conscious level and found the same-object advantage. These results altogether suggest that amodal completion occurs unconsciously and that the depth of unconscious processing can be extended beyond contours and surfaces that are spatially continuous.
Meeting abstract presented at VSS 2014
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