“…For more than 60 years, the experience of pain has been reported to be associated with various negative emotional states, including depression, anxiety, fear, and anger (Chapman et al, 1946; Hemphill et al, 1952; Ramzy & Wallerstein, 1958; Schachter, 1957; Webb & Lascelles, 1962). Studies have generally found that higher levels of negative emotions are associated with greater acute and chronic pain intensity (e.g., Bruehl et al, 2002; Janssen, 2002; Linton, 2000; Staud, 2004), and possibly with increased risk of developing chronic pain (Linton, 2005).…”