Combining Experiences Over Time: The Effects of Duration, Intensity Changes & On-Line Measurements on Retrospective Pain Evaluations

Two experiments were conducted to examine the effects of various factors on retrospective pain evaluation. The factors examined in Experiment 1 were the rate and pattern of change, the intensity (particularly the final intensity), and the duration of the painful experience. Experiment 2 manipulated these factors and, in addition, examined the effect of continuous (on-line) ratings on the overall retrospective evaluation. The two experiments utilized different pain modalities, heat in the first and mechanical pressure in the second. In addition, all subjects in Experiment 1 experienced stimuli with the same physical magnitude, while in Experiment 2 stimuli were individually tailored to make them subjectively equivalent. In both experiments, subjects were presented with a series of painful stimuli and evaluated the intensity of each stimulus immediately upon its termination. The stimuli themselves were composed of multiple intensity levels that differentially changed over time (Intensity-Patterns). Subjects' on-line ratings in Experiment 2 closely mirrored the physical patterns of the intensities. The main conclusion from both experiments is that the retrospective evaluations of painful experiences are influenced primarily by a combination of the final pain intensity and the intensity trend during the latter half 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 reporting the stimulus intensity had a moderating impact on the retrospective evaluations.