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Min-Suk Kang, Randolph Blake, Geoffrey Woodman; Semantic analysis does not occur during interocular suppression in the absence of awareness. Journal of Vision 2011;11(11):321. doi: https://doi.org/10.1167/11.11.321.
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© ARVO (1962-2015); The Authors (2016-present)
It has been intensely debated whether visual stimuli are processed to the point of semantic analysis in the absence of awareness. In the present study, we used two related interocular suppression paradigms to measure the extent to which the meaning of a stimulus was registered across multiple levels of visibility. To infer whether a stimulus was semantically analyzed we measured the N400 component of observers' event-related potentials (ERPs), a highly sensitive index of the semantic mismatch between a stimulus and the context in which it is presented. Observers judged the semantic relatedness of a prime and target word while ERPs were recorded under continuous flash suppression (Experiment 1) and binocular rivalry (Experiment 2). Also, we parametrically manipulated the visibility of the target word by increasing the contrast between the target word and the suppressive stimulus presented to the other eye (Experiment 3). We found that the amplitude of the N400 was attenuated with increasing suppression depth and absent whenever the observers could not discriminate the meaning of the words. We interpret these findings in the context of single-process models of consciousness which can account for a large body of empirical evidence obtained from visual masking, attention and, now, interocular suppression paradigms.
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