EEG recording procedures are detailed in Kayser et al. (2013). Briefly, using NeuroScan software (NeuroScan, 1993), continuous EEGs were acquired at 200 samples/s with a 48-channel Grass Neurodata recording system for an expanded 10–20 system scalp montage (Pivik et al., 1993; Jurcak et al., 2007), using a nose tip reference and analogue hardware settings of 10k gain and .01–30 Hz (-6dB/octave) band pass. Volume-conducted blink artifacts were removed from the raw EEG by spatial singular value decomposition (NeuroScan, 2003). Recording epochs of 1,200 ms (200 ms prestimulus baseline) were extracted off-line, tagged for A/D saturation, and digitally low-pass filtered at 50 Hz (-24 dB/octave) to remove any residual high frequency activity from the EEG that is not relevant to ERPs, including digitizer noise. Using a reference-free approach to identify residual artifacts on a channel-by-channel and trial-by-trial basis (Kayser & Tenke, 2006d), artifactual surface potentials were either replaced by spherical spline interpolation (Perrin et al., 1989) using the data from artifact-free channels (i.e., when less than 25% of all EEG channels contained an artifact) or the affected trial was rejected.
