[1] Lincoln Univ, Sch Psychol, Coll Social Sci, Lincoln LN6 7TS, Lincs, England
[2] East London NHS Fdn Trust, Wolfson Inst Prevent Med, Violence Prevent Res Unit, London, England
[3] Queen Mary Univ London, St Bartholomews Hosp, London, England
[4] Univ Coll Cork, Sch Appl Psychol, Cork, Ireland
[5] Univ East London, Sch Psychol, London, England
[6] Imperial Coll, Dept Med, London, England
[7] Auckland Univ Technol, Fac Hlth & Environm Sci, Gambling & Addict Res Ctr, Auckland, New Zealand
[8] Auckland Univ Technol, Fac Hlth & Environm Sci, Gambling & Addict Res Ctr, Dept Psychol, Auckland, New Zealand