Mean amplitudes were derived for time-windows averaged across electrodes within a region of interest (ROI). Time windows and ROIs of components were defined by ERP waveforms and topographic maps collapsed across conditions. Thus, the channel and time-window selection was orthogonal to the conditions of interest. Based on this approach, the cue-related P1 was quantified at posterior electrodes PO7, PO8, PO3, PO4, O1 and O2 between 70 and 130 ms. This component was followed by a negative wave (N1) over the same posterior brain area from 130 to 180 ms. A P2 with a central positive deflection at electrode sites C1, C2, Cz and CPz from 200 to 250 ms was detected, followed from 250 to 300 ms by a negative anterior (electrodes FC1, FC2, F1, F2, FCz and Fz) deflection in the N2 range. A clear P3 component was observed at occipito-parietal electrode sites (P1, P2, PO3, PO4, Pz and POz) and quantified between 300 and 500 ms. The CNV, a late negative-going wave for active-attention cues, was detected within a central ROI (C1, C2 and Cz) between 700 and
