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Some conscious experiences are more vivid than others. Although perceptual visibility is a familiar component of human consciousness, how variation in visibility is registered by the human brain is unknown. In particular, it is unknown whether the vividness of experience is encoded in a “rich” manner, via the strengthening or broadcast of content-specific perceptual representations, or a “sparse” manner, in which content-invariant signals track the reliability or precision of perceptual contents. Here we reanalysed existing MEG and fMRI data from two distinct studies, operationalising perceptual visibility as subjective ratings of awareness and visibility. Using representational similarity and decoding analyses, we find evidence supporting a proposal that perceptual visibility is associated with content-invariant neural signatures distributed across visual, parietal, and frontal cortices. Our findings are consistent with content-invariant neural substrates supporting the strength of perceptual experience and offer a novel methodology for examining the neural correlates of perceptual awareness.Significance StatementThe vividness of experience varies across different stimuli and contexts. Despite being a fundamental feature of human conscious awareness, it remains debated as to how perceptual vividness is encoded in the brain. Here we investigate whether the neural correlates of perceptual visibility are specific to the content of an experience and/or whether they generalize over different stimuli. By reanalysing data from two different neuroimaging studies, we describe evidence in support of a content-invariant neural code for perceptual visibility. We find temporally dynamic content-invariant neural signatures of visibility localised to visual, parietal, and frontal cortices. Our approach to dissociating content-specific and content-invariant neural signatures of awareness offers a new framework within which to distinguish between rich vs. sparse models of consciousness. |
