Neural correlates of consciousness in an attentional blink paradigm with uncertain target relevance.

Several event-related potentials (ERPs) have been proposed as neural correlates of consciousness (NCC), most prominently the early visual awareness negativity (VAN) and the late P3b component. Highly influential support for the P3b comes from studies utilizing the attentional blink (AB), where conscious perception of a first visual target (T1) impairs reporting a second target (T2) presented shortly afterwards. Recent no-report studies using other paradigms suggest that the P3b component may reflect post-perceptual processes associated with decision-making rather than awareness. However, no-report studies are limited in their awareness assessment, and their conclusions have not been tested in an AB paradigm. The present study (N = 38) addressed these issues using a novel AB paradigm, which reduced decision-making processes by omitting a discrimination task on T2 stimuli and rendering their relevance uncertain. Nevertheless, awareness was assessed trial by trial. Comparing ERPs in response to seen versus unseen T2 stimuli revealed a VAN but no enhanced P3b regardless of whether they were marked as distinct from distractor stimuli or not. Our results corroborate the VAN and challenge the P3b as NCC despite rigorous trial-by-trial assessment of conscious perception. Thus, they support the idea that awareness emerges during early sensory processing.