1. a Department of Psychology , St. George's Hospital Medical School , Cranmer Terrace, London , SW17 ORE , UK
2. b Imperial Cancer Research Fund Health Behaviour Unit , Institute of Psychiatry , De Crespigny Park, London , SE5 8AF , UK
3. c Limburgs Universitair Centrum , 8–3590 , Diepenbeek , Belgium
4. d Department of Clinical Science , University of Tampere , PO Box 607, SF-33101 , Tampere , Finland
5. e Department of Behavioural Sciences in Medicine , University of Oslo , PO Box 1111 Blindern, N-0317 , Oslo , Norway