Sheina Orbell1, Caroline J Henderson2, Martin S Hagger3. 1. Department of Psychology, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK. sorbell@essex.ac.uk. 2. Department of Psychology, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK. 3. Health Psychology and Behavioural Medicine Research Group, School of Psychology and Speech Pathology, Curtin University, Perth, Australia.