Figure 2. Left and Center Panels: Grand-average event-related potentials elicited by task-irrelevant flashes on a Target disc (Left) or on a Distractor disc (Center).

In each panel, ERPs obtained while subjects tracked 2 discs are shown in red; ERPs obtained while subjects tracked 3 discs are shown in green; and ERPs obtained while 4 discs were being tracked are shown in blue. The vertical line in each panel marks the onset of the flash. Right Panel: log ERP amplitude (maximum–minimum) for tracking loads of 2, 3 and 4 discs. ERPs to flashes on Target discs are represented by black circles; ERPs evoked by flashes on Distractor discs are shown with white squares. Error bars represent within-subject SEM.