COMBINING EXPERIENCES OVER TIME - THE EFFECTS OF DURATION, INTENSITY CHANGES AND ONLINE MEASUREMENTS ON RETROSPECTIVE PAIN EVALUATIONS

Two experiments were conducted to examine the effects of various facto rs on retrospective pain evaluation. The factors examined in Experimen t 1 were the rate and pattern of change, the intensity (particularly t he final intensity), and the duration of the painful experience. Exper iment 2 manipulated these factors and, in addition, examined the effec t of continuous (on-line) ratings on the overall retrospective evaluat ion. The two experiments utilized different pain modalities, heat in t he first and mechanical pressure in the second. In addition, all subje cts in Experiment 1 experienced stimuli with the same physical magnitu de, while in Experiment 2 stimuli were individually tailored to make t hem subjectively equivalent. In both experiments, subjects were presen ted with a series of painful stimuli and evaluated the intensity of ea ch stimulus immediately upon its termination. The stimuli themselves w ere composed of multiple intensity levels that differentially changed over time (Intensity-Patterns). Subjects' on-line ratings in Experimen t 2 closely mirrored the physical patterns of the intensities. The mai n conclusion from both experiments is that the retrospective evaluatio ns of painful experiences are influenced primarily by a combination of the final pain intensity and the intensity trend during the latter ha lf of the experience. In addition, results indicated that duration has little impact on retrospective evaluations for stimuli of relatively constant intensity. However, when the stimulus intensity changes over time, duration does play a role. Finally, the task of continuously rep orting the stimulus intensity had a moderating impact on the retrospec tive evaluations. (C) 1998 John Wiley & Sons, Ltd.