Traditional stimulus-locked event-related potentials (ERPs) displayed a strong visual P2 peak over frontal and posterior sites and a prominent P3 over central sites (Figure 2, left), consistent with previous literature (Hopfinger and West, 2006; Makeig et al., 1999). N1 and N2 responses were also visible. The response-locked ERPs showed a double peak that was most pronounced at central and posterior sites (Figure 2, right), and which was highly replicable across subjects. This matches the post-motor thetaband synchronization described byMakeig et al. (2004).
