Premium
Timing of the earliest ERP correlate of visual awareness
Author(s) -
Wilenius Maria E.,
Revonsuo Antti T.
Publication year - 2007
Publication title -
psychophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.661
H-Index - 156
eISSN - 1469-8986
pISSN - 0048-5772
DOI - 10.1111/j.1469-8986.2007.00546.x
Subject(s) - psychology , stimulus (psychology) , perception , contrast (vision) , negativity effect , event related potential , visual perception , cognitive psychology , audiology , electrophysiology , electroencephalography , neuroscience , medicine , artificial intelligence , computer science
Abstract The earliest reliably occurring event‐related brain potential (ERP) correlate of visual awareness (visual awareness negativity, VAN) emerges after 100 ms and peaks between 200 and 300 ms from stimulus onset. In a study using low‐contrast stimuli, VAN was significantly delayed, peaking at 460 ms (V. Ojanen, A. Revonsuo, & M. Sams, 2003). In that study physical differences between the conscious and nonconscious stimuli may have confounded the results. Here we explored whether VAN is similarly delayed for physically identical stimuli. We presented low‐contrast stimuli near an individually determined subjective contrast threshold. A delayed VAN peaked at 400 ms at occipito‐temporal sites to subjectively perceived stimuli. Our results support the interpretation that VAN is the earliest ERP correlate of phenomenal visual awareness. The electrophysiological processes eliciting VAN may become delayed as a function of the difficulty of the early perceptual discrimination.