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)

We often feel that our perceptual experience is richer than what we can express. For instance, when flashed with a large set of letters, we feel that we can see them all, while we can report only a few. However, the nature of this subjective impression remains highly debated: while many favour a dissociation between two forms of consciousness , others contend that the richness of phenomenal experience is a mere illusion. Here we addressed this question with a classical partial-report (...) paradigm now modified to include unexpected items in the unreported parts of the stimuli. We show that even in the presence of unexpected pseudo-letters, participants still felt that there were only letters. Additionally, we show that this feeling reflects an illusion whereby participants reconstruct letters using partial letter-like information. We propose that the feeling of seeing emerges from the interplay between partially accessible information and expectations. (shrink)

On identifie deux modèles du concept de règle présents dans l’œuvre de Wittgenstein, dès le Tractatus : les règles de projection (ou de traduction) et les règles opératoires (ou de calcul). Dans le cadre conceptuel de ce texte, gouverné par l’indépendance des propositions élémentaires, ces deux modèles sont équivalents. On interprète ensuite les difficultés de Wittengstein avec le concept de phénoménologie, au début des années trente, comme liées à la restriction du concept de règle aux règles de projection. Le dépassement (...) de ces difficultés se fait par la découverte de la possibilité d’un nouvel équilibre entre les deux modèles, équilibre dans lequel les règles opératoires jouent un rôle directeur. (shrink)