beginning 187 ms prior to and continuing for 1413 ms after the stimulus onset. Artifact rejection thresholds were set at 73.3 μV. Waveforms were computed using epochs filtered with 32 Hz low pass digital filter. The epochs were 1000 milliseconds long and included 200 milliseconds prior to the stimulus and 800 ms post-stimulus. Only subjects with good, artifact-free visually inspected waveforms were included. The trials in which the response time exceeded 1000 ms were coded as missed responses and excluded from all analyses. Further, only the correct response trials and with 15 minimum numbers of good trials in each conditions were included for the statistical analysis.
