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Rong Zhou, Michael von Grünau; Experience Visual Qualia without Conscious Percept?. Journal of Vision 2012;12(9):1009. doi: 10.1167/12.9.1009.
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© ARVO (1962-2015); The Authors (2016-present)
In the phenomenon of blindsight, people can exhibit above-chance performance in responding to visual stimuli, which indicates there is a possible dissociation between visual awareness and performance. Moreover, it is possible that observers tend to degrade their awareness threshold while they are under-confident due to the inability of perceiving targets clearly. In Experiment 1 (n = 3), we presented observers with drifting plaids composed of two superimposed gratings whose direction differed by 180°, the orientation of which was varied by 10, 20, 30, and 45°. Perceptual responses (i.e., perceived component or pattern motion) and eye movement (EM) patterns were recorded under binocular- and dichoptic-viewing conditions. In Experiment 2 (n = 3), we used only dichoptic viewing and utilized binocular switch suppression technique (i.e., repeatedly switching conflicting images between the eyes) to render drifting gratings temporarily invisible. Furthermore, the contrast level of drift gratings was varied. Perceptual responses and EM patterns were recorded. Observers had to indicate their visual experience categorically (i.e., clear image, almost clear image, weak glimpse, or not seen) at the end of each trial. During binocular viewing, observers’ perceptual responses were consistent with their EMs. Under the dichoptic-viewing condition, observers perceived component motion frequently. There was no clear dissociation between perceptual responses and EMs. However, the optokinetic nystagmus rate (OKN) increased during dichoptic viewing. In Experiment 2, EMs were dissociable from observers’ perceptual responses even when they reported no awareness of moving gratings. Moreover, observers reported visual experience as being graded rather than "all-or-none". Our findings indicate observers’ visual awareness and performance can be dissociated, and they tend to underestimate their visual capacity when conditions are difficult. Understanding how the visual system operates with or without visual awareness by using different psychophysical manipulations will allow us to use measurable techniques to trace the fingerprints of the neuronal correlates of consciousness.
Meeting abstract presented at VSS 2012
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