Gamma band activity and the P3 reflect post-perceptual processes, not visual awareness.

TitleGamma band activity and the P3 reflect post-perceptual processes, not visual awareness.
Publication TypeJournal Article
Year of Publication2014
AuthorsPitts MA, Padwal J, Fennelly D, Martínez A, Hillyard SA
Date Published2014 Nov 1
KeywordsAdult, Attention, Awareness, Consciousness, Electroencephalography, Event-Related Potentials, P300, Female, Gamma Rhythm, Humans, Male, Psychomotor Performance, Visual Perception, Young Adult

A primary goal in cognitive neuroscience is to identify neural correlates of conscious perception (NCC). By contrasting conditions in which subjects are aware versus unaware of identical visual stimuli, a number of candidate NCCs have emerged; among them are induced gamma band activity in the EEG and the P3 event-related potential. In most previous studies, however, the critical stimuli were always directly relevant to the subjects' task, such that aware versus unaware contrasts may well have included differences in post-perceptual processing in addition to differences in conscious perception per se. Here, in a series of EEG experiments, visual awareness and task relevance were manipulated independently. Induced gamma activity and the P3 were absent for task-irrelevant stimuli regardless of whether subjects were aware of such stimuli. For task-relevant stimuli, gamma and the P3 were robust and dissociable, indicating that each reflects distinct post-perceptual processes necessary for carrying-out the task but not for consciously perceiving the stimuli. Overall, this pattern of results challenges a number of previous proposals linking gamma band activity and the P3 to conscious perception.

Alternate JournalNeuroimage
PubMed ID25063731
PubMed Central IDPMC4169212
Grant List1P50MH86385 / MH / NIMH NIH HHS / United States
P50 MH086385 / MH / NIMH NIH HHS / United States
R01 EY016984 / EY / NEI NIH HHS / United States
R01 EY016984-35 / EY / NEI NIH HHS / United States
IRG Funded