[1] Univ Guelph, Psychol Dept, 50 Stone Rd E, Guelph, ON N1G 2W1, Canada
[2] Univ Minnesota, Dept Educ Psychol, 56 East River Rd, Minneapolis, MN 55455 USA
[3] McMaster Univ, McMaster Childrens Hosp, Pediat Chron Pain Program, Hamilton, ON L8N 3Z5, Canada
[4] McMaster Univ, Dept Anesthesia, Hamilton, ON L8N 3Z5, Canada
[5] Western Univ, Schulich Sch Med & Dent, Dept Pediat, London, ON N6A 3K7, Canada