Topographic images that depict the scalp localizations for the auditory oddball task for the wet- (top panels) and the dry-EEG approaches (bottom panels) - note that the peaks at the Cz sensor for the P3a (left panel) and the P3b (right panel) components. Critically, the P3a component (left bottom panel) for the dry approach is relatively more frontal-situated (toward the nose) as compared to the wet EEG approach which instead situated at the very top or apex of the brain (right top panel). The P3b occurs over the Cz electrode at the top / apex and mid-line of the brain (top and bottom right panels) for both the dry- and the we-EEG approaches.