ERP and MEG Correlates of Visual Consciousness : An Update

Two decades of event-related potential (ERP) research have established that the most consistent correlates of the onset of visual consciousness are the early visual awareness negativity (VAN), a negative component in the N2 time range over posterior electrode sites, and the late positivity (LP), a positive component in the P3 time range over fronto-parietal electrode sites. A review by Koivisto & Revonsuo (2010) had looked at 39 studies and concluded that the VAN is the earliest and most reliable correlate of visual phenomenal consciousness, whereas the LP probably reflects later processes associated with reflective/access consciousness. However, an “early” vs. “late” debate still persists. This thesis provides an update to that earlier review. All ERP and MEG studies that have appeared since 2010 and directly compared ERPs of aware and unaware conditions are considered. The result corroborates the view that VAN is the earliest and most consistent signature of visual phenomenal consciousness, and casts further doubt on the LP as an ERP correlate of consciousness. Important new methodological, empirical, and theoretical developments in the field are described, and the empirical results are related to the theoretical background debates