Memory for pain: relation between past and present pain intensity.

Memory for the intensity of past physical pain depends critically on the intensity of present pain. When their present pain intensity was high, patients with chronic headaches of myofascial origin rated their maximum, usual, and minimum levels of prior pain as being more severe than their hourly pain diaries indicated. When their present pain intensity was low, the same patients remembered all 3 levels of prior pain as being less severe than they actually had been. The results show that pain produces systematic distortions of memory similar to those associated with alterations of affect or mood, and suggest a resolution to a conspicuous conflict in the current pain literature.