Artifacts were removed using the Gratton and Coles method implemented in BVA (Gratton et al., 1983). Data were then bandpass filtered between 0.5 Hz and 30Hz3 using a zero phase lag filter with a 48 dB/octave roll-off. Stimulus-locked trials were extracted for all instances where there was a correct behavioral response, for each of the three experimental conditions (target, rare non-target and standard non-target), with each trial comprising 450ms of data pre-stimulus and 1300ms post-stimulus4. The response window for correct responses on target trials was 800 ms. Data for the ERP analysis were baseline corrected using the 100ms pre-stimulus interval5. Any trials containing out of range voltages (± 75 μV) were rejected as artifacts and excluded from further processing. All further processing was applied to the data from the target condition only.
