Figure 2. Grand-average ERP waveforms obtained in Experiment 1 in the 600 ms post-stimulus interval at posterior electrodes PO7/PO8 contralateral (solid lines) and ipsilateral (dashed lines) to the target hemifield, as a function of target numerosity (left column: one-target condition; middle column: two-target condition; right column: three-target condition).

Topographical ERP scalp distribution maps of the N2pc (180–270 ms) are shown for each condition, obtained by computing the contralateral minus ipsilateral difference activity, and mirrored across the midline. The scale was optimized for each experiment (Experiment 1: ±4 µV). Both the N2pc and CDA increased as a function of target numerosity.