Amidst the many brain events evoked by a visual stimulus, which are specifically associated with conscious perception, and which merely reflect non-conscious processing? Several recent neuroimaging studies have contrasted conscious and non-conscious visual processing, but their results appear inconsistent. Some support a correlation of conscious perception with early occipital events, others with late parieto-frontal activity. Here we attempt to make sense of those dissenting results. On the basis of a minimal neuro-computational model, the global neuronal workspace hypothesis, we propose a (...) taxonomy which distinguishes between vigilance and access to conscious report, as well as between subliminal, preconscious and conscious processing. We suggest that these distinctions map onto different neural mechanisms, and that conscious perception is systematically associated with a sudden surge of parieto-frontal activity causing top-down amplification. (shrink)

The objectives of this article are twofold. First, by denying the dualism inherent in attempts to load metaphysical significance on the inner/outer distinction, it defends the view that scientific investigation can approach consciousness in itself, and is not somehow restricted in scope to the outward manifestations of a private and hidden realm. Second, it provisionally endorses the central tenets of global workspace theory, and recommends them as a possible basis for the sort of scientific understanding of consciousness thus legitimised. However, (...) the article goes on to argue that global workspace theory alone does not constitute a fully worked-out objective account of the conscious subject. This requires additional attention to be paid to the issue of embodiment, and to the possibility of indexicality that arises when an instantiation of the global workspace architecture inhabits a spatially localised body. (shrink)