Fig. 2

A schematic illustration of event-related potentials (ERP). The EEG epochs obtained in single trials 1–16 were averaged. After averaging the random activity was reduced and event related activity increased (e.g. to the stimulus). As a result, a sequence of peaks occurred. The early peaks are related to physical features of the stimulus, whereas the later peaks are associated with particular cognitive processes like selective attention (P1 and N1), stimulus evaluation (P2), response selection and conflict processing (N2c) and allocation of cognitive resources and working memory (P3b). The dotted waves indicate the variability of the amplitude depending on the intensity of the involved cognitive process. The distribution of the electric potentials can be visualized in form of topographical maps that illustrate the highest current densities on the scalp at a particular point in time. The time axis is logarithmic scaled