Daily diaries reveal influence of pessimism and anxiety on pain prediction patterns.

The match/mismatch model of pain prediction was tested with a group of rheumatoid arthritis patients (N = 227) in a natural setting. Daily diary measures of pain prediction and pain experience were obtained over 30 days. Results revealed a greater number of underpredictors (N = 147) than over predictors (N = 58) in our sample, with a minority (N = 22) overpredicting and underpredicting with equal frequency. Further, people modified their predictions to a greater degree after an over prediction than they did after an under prediction. As expected, anxious participants were less accurate and more prone to over predicting their pain than their less anxious counterparts. In contrast, participants who reported low levels of daily pessimism were more likely than their more pessimistic counterparts to under predict their pain. The findings suggest that people continued to under predict their pain despite repeated disconfirmations and that low levels of pessimism may have accounted for this pattern.