Selected ERP waveforms (colored lines, PO4: thick, T8: thin) for words
(column 1) and faces (column 2) as shown in Fig.
2, and ERP difference waveforms (i.e., faces-minus-words; column 3),
comparing three common EEG references (NR: nose reference; LM: linked-mastoids
reference; AR: average reference; colors as in Fig. 2). The shaded areas and the black dashed lines depict the
differences between the two ERPs shown in each subgraph (i.e., thick-minus-thin
colored lines). Relative ERP differences between any two sites are unaffected by
the EEG reference, as revealed by identical difference waveforms in each column
(dashed lines). It is obvious that any attempt to quantify deflections (i.e.,
peak and troughs) of the colored lines will yield different results for each EEG
reference, notwithstanding their invariance in topography across references.