1. Neurosciences Research Institute, School of Life and Health Sciences, Aston University, Birmingham B4 7ET, UK
2. ATR Human Information Science Laboratories, 2–2–2 Hikaridai, Seika–cho, Soraku–gun, Kyoto 619–0288, Japan
3. Department of Psychology, Royal Holloway, University of London, Egham TW20 0EX, UK