How expectancy violations facilitate learning to cope with pain - An experimental approach

Background: Expectations of painful sensations constitute a core feature of chronic pain. An important clinical question is whether such expectations are revised when disconfirming experiences are made (e.g., less pain than expected). This study examined how people adjust their pain expectations when the experience of decreasing pain is expected vs. unexpected. Methods: In a novel randomized between-subjects design, a subclinical sample of people who frequently experience pain was provided with painful thermal stimulations. Unbeknownst to participants, the temperature applied was decreased from trial to trial. Based on the experimental instructions provided, this experience of decreasing pain was expected in one condition (expectation-confirmation; n = 34), whereas it was unexpected in another (expectation-disconfirmation; n = 39). Results: Perceived pain intensity was lower in the expectation-confirmation condition than in the expectationdisconfirmation condition (p = .014, eta(2)(p) = 0.083). The expectation-confirmation condition also showed a greater adjustment of their pain expectations than the expectation-disconfirmation condition (p = .046, eta(2)(p) = 0.047). Across groups, large expectation violations (i.e., less pain than expected) were associated with increases in pain tolerance and the ability to cope with pain at a one-week follow-up. Conclusions: In terms of assimilation, perceived pain intensity was shaped in the direction of pain expectations. The greater adjustment of expectations in the expectation-confirming condition is consistent with a confirmation bias in pain perception. Though participants who experienced large discrepancies between expected and experienced pain were hesitant to adjust their pain expectations immediately, expectation violations increased their ability to cope with pain one week later, suggesting some beneficial longer-term effects of expectation violations.