[1] MRC, Cognit & Brain Sci Unit, Cambridge, England
[2] Univ E Anglia, Norwich NR4 7TJ, Norfolk, England
[3] Oliver Zangwill Ctr, Ely, Cambs, England
[4] Queens Med Ctr, Univ Hosp, Nottingham NG7 2UH, England
[5] Julian Hosp, Norwich, Norfolk, England
[6] Univ York, Dept Psychol, York YO10 5DD, N Yorkshire, England