The EEG was recorded from 19 scalp locations based on the International 10/20 system of electrode placement, using linked ears as a reference. Eye movement electrodes were applied to the inner and outer canthus to monitor artifact and all EEG records were visually inspected and manually edited to remove any visible artifact. Two 5 min of EEG was recorded in the eyes closed and in the eyes open condition. The order of recording for the eyes open followed by closed conditions and vice versa was counter-balanced across subjects. Each EEG record was plotted and visually examined and split-half reliability and test–retest reliability measures of the artifacted data were computed using the Neuroguide software program (NeuroGuide, v2.6.9). The amplifier bandwidths were nominally 1.0–30 Hz, the outputs being 3 db down at these frequencies and the EEG was digitized at 100 Hz. Analyses were performed on 58 s to 2 min 17 s segments of EEG. Split-half reliability tests were conducted on the edited EEG segments and only records with >90% reliability were entered into the spectral analyses. Phase shift and lock duration were computed only on contiguous EEG segments.
