Channel selection was based on an optimized electrode approach (e.g., Foxe and Simpson, 2002), whereby the channel that showed the highest P1 amplitude, from the CSD interpolated data, was selected for analysis. The CSD scalp maps at the latency at which the P1 peak was maximal, with the selected electrode marked by a black dot are presented in Figure 1 (left column); scalp maps from the IC selected for each participant are presented in Figure 1 (right column). Despite not being used in the IC selection criteria, the similarity between the weight with which the ICs project to the scalp electrodes and the topography of the CSD maps at the time-point when P1 was maximal, confirms that the selected component represent activity associated with the P1 deflection.
