Grand averages of stimulus-locked ERPs at Cz in the four groups. Grand averages of stimulus-locked ERPs at Cz in the four groups. Depicted are compatible (solid thick line) and incompatible trials (dashed thick line) and the difference waveform (solid thin line). For illustration the data were low-pass filtered (low-pass filter, 12 Hz). Shown is the isovoltage map of the difference waveform for the time window 250–350 ms (N2) in the complete sample (maximum and minimum values in microvolts are −1.0 and 0.5). Ulrike M. Krämer et al. J. Neurosci. 2007;27:14190-14198 ©2007 by Society for Neuroscience