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Marjan Persuh, Tatiana Aloi Emmanouil, Tony Ro; Emergence of illusory shapes from invisible inducers. Journal of Vision 2013;13(9):1105. doi: 10.1167/13.9.1105.
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© ARVO (1962-2015); The Authors (2016-present)
Several studies have claimed that unconscious vision is fast, automatic, and involves simpler forms of information processing compared to conscious perception. However, to render stimuli unconscious, experimenters often use brief stimulus presentation times and other manipulations that impair visual processing, which confounds awareness with differences in physical stimulus attributes and neural processing. In the current study, we developed a novel method to render visual stimuli invisible, while allowing for their extended processing. We demonstrate the validity of the method by showing that illusory contours are consciously perceived even when all inducing elements are rendered invisible, contrary to previous reports. In the first experiment we presented inducers, either alone or followed by a pattern mask. We varied the number of inducer-mask repetitions (1-8) and showed that with repeated exposure, participants started to perceive illusory contours even though they were completely unaware of the inducing elements in the masked condition. In the second experiment we used only the highest number of repetitions (8) and showed that the perception of illusory contours was similar regardless of whether the inducers were masked or not, even though forced-choice discrimination of the inducers was at chance. These results demonstrate that with repeated presentations, the processing of stimuli presented below the threshold for awareness may be cumulative and more extensive than previously considered. Our study thus suggests that consciousness research should fundamentally shift to using methods that effectively block stimuli from awareness while minimally interfering with their processing.
Meeting abstract presented at VSS 2013
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