EEG recordings were processed offline using the Edit program in Scan 4.3 (Compumedics Neuroscan, Inc., El Paso, TX). 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 0.5Hz and 30Hz using a zero phase lag filter at 48dB/octave. Stimulus-locked epochs were created from all instances of each experimental conditions and were baseline corrected using the 100 ms pre-stimulus interval. Any epochs with out of range voltages (+/−75microV) were rejected as artifacts and excluded from further processing. To extract the P160, epochs were averaged using the AVERAGE procedure, producing one average waveform per condition per subject. The time windows for the P160 and P300 components were determined by visual inspection of grand averaged waveforms and the maximal positive amplitude between 120–180ms and 250–550ms post-stimulus was scored as the P160 and P300.
