[1] Univ Cambridge, Dept Psychiat, Cambridge, England
[2] Cambridge Cognit Ltd, Cambridge, England
[3] Univ Cambridge, Behav & Clin Neurosci Inst, Cambridge, England
[4] Univ Cambridge, Dept Expt Psychol, Cambridge CB2 3EB, England
[5] Natl Hosp Neurol & Neurosurg, UCL Inst Neurol, London WC1N 3BG, England