[1] Univ Stirling, Div Psychol, Fac Nat Sci, Stirling FK9 4LA, Scotland
[2] Univ Alberta, Fac Med & Dent, Dept Anesthesiol & Pain Med, Edmonton, AB, Canada
[3] West Virginia Univ, Dept Psychol, Morgantown, WV 26506 USA
[4] Univ Aberdeen, Inst Appl Hlth Sci, Hlth Psychol, Aberdeen, Scotland