ERP and MEG correlates of visual consciousness: The second decade.

The earliest and most reliable brain signal linked to visual phenomenal consciousness is the visual awareness negativity (VAN), a negative voltage deflection occurring around 200-300 milliseconds after a stimulus appears over posterior scalp regions. A later positive component, the late positivity (LP), which appears over frontal areas around 300-500 milliseconds, likely reflects later cognitive processes such as reflective or access consciousness rather than phenomenal awareness itself. This conclusion is supported by a review of event-related potential and magnetoencephalography studies published since 2010 that directly compared brain responses to consciously perceived versus unseen stimuli. The evidence strengthens VAN's role as the primary neural correlate of phenomenal consciousness and further undermines LP as a marker of phenomenal awareness.

Study at a glance

Abstract

The first decade of event-related potential (ERP) research had established that the most consistent correlates of the onset of visual consciousness are the early visual awareness negativity (VAN), a posterior negative component in the N2 time range, and the late positivity (LP), an anterior positive component in the P3 time range. Two earlier extensive reviews ten years ago had concluded that VAN is the earliest and most reliable correlate of visual phenomenal consciousness, whereas LP probably reflects later processes associated with reflective/access consciousness. This article provides an update to those earlier reviews. ERP and MEG studies that have appeared since 2010 and directly compared ERPs between aware and unaware conditions are reviewed, and important new developments in the field are discussed. The result corroborates VAN as the earliest and most consistent signature of visual phenomenal consciousness, and casts further doubt on LP as an ERP correlate of phenomenal consciousness.