EEG recordings were processed offline using the Edit program in Scan 4.3 (Compumedics Neuroscan, Inc., Charlotte, NC). Artifacts from eye movements were removed using the ocular artifact reduction algorithm (ARTCOR procedure) in Scan 4.3. Data were then band-pass filtered between 0.5 and 30 Hz using a zero-phase lag filter at 48 dB/octave. Stimulus-locked epochs for the target condition were extracted for all instances where there was a correct behavioral response. Trials consisted of 1800 msec of data, including a 500-msec prestimulus baseline. Any epochs with voltages beyond the range of ±75 μV were rejected as artifacts and excluded from further processing.
