EEG recordings were obtained from 21 channels at the Fz, FCz, Cz, CPz, and Pz central recording sites, the Fp1/Fp2, F3/F4, C3/C4, P3/P4, O1/O2 medial hemispheric sites, as well as F7/F8, T7/T8, P7/P8 lateral hemispheric sites of the modified 10–20 system [37]. An Electro-cap system was used, with additional tin electrodes affixed with paste and tape. Cephalic electrodes were referenced to linked mastoids balanced for resistance, with a forehead ground. These methods permit a direct comparison to previous studies and do not compromise hemispheric difference measures. Impedance for all recording sites was 10 kΩ or less. Electro-ocular (EOG) activity was monitored with electrodes placed at the outer canthus and infra-orbitally about the left eye. EEG was recorded for 3 minutes with eyes open as is typically done to avoid a preponderance of alpha activity, and the subject sitting in a sound-attenuated booth. The bandpass was 0.02–45 Hz, with a digitization rate of 256 Hz employed. Trials where the amplitude exceeded 100 μV were excluded from analysis.
