in visual recognition memory tasks, with both ERP topography and polarity affected by the choice of EEG recording reference (cf. Kayser et al., 2003), the different scalp distributions of N2, P3 and the overlying old/new effects strongly suggest that separable cognitive processes with distinct neuronal generators are superimposed, though volume-conducted, to produce these scalp-recorded ERPs (cf. Johnson et al., 1998; Friedman, 2000; Kayser et al., 2003).
