[1] Univ Bristol, Sch Expt Psychol, 12a Priory Rd, Bristol BS8 1TU, Avon, England
[2] Univ Bristol, MRC Integrat Epidemiol Unit, Bristol, Avon, England
[3] Univ Bristol, UK Ctr Tobacco & Alcohol Studies, Bristol, Avon, England
[4] Cambridge Cognit Ltd, Cambridge, England