Steve Sharman1, Mike Aitken2,3, Luke Clark2,4. 1. Department of Psychology, University of Cambridge, Downing Street, Cambridge, CB2 3EB, UK. sps48@cam.ac.uk. 2. Department of Psychology, University of Cambridge, Downing Street, Cambridge, CB2 3EB, UK. 3. Institute of Psychiatry, Psychology and Neuroscience, Kings College London, De Crespigny Park, London, SE5 8AF, UK. 4. Department of Psychology, Centre for Gambling Research at UBC, University of British Columbia, 2136 West Mall, Vancouver, BC, V6T 1Z4, Canada.