Participants sat in a dimly lit room and were instructed to sit still with their eyes closed for 3 minutes (Clementz et al. 1994; Sponheim et al. 1994, 2000). 32 channels of EEG were recorded using Ag/AgCl electrodes with a nose reference (Falk-Minow Services, Munich, Germany) and Neuroscan SYNAMPS recording system (Neuroscan, Inc., El Paso, TX, USA). EEG signals were digitized at the rate of 1000 Hz with a 0.10 Hz high-pass filter and a 200 Hz low-pass filter. Electrode impedances were kept below 10 kΩ Vertical and horizontal electrooculograms (EOGs) were monitored by an electrode located inferior to the right eye, and two electrodes on the right and left outer canthus, respectively.
