Experimental Analyses of Pain: Understanding Processes and Developing Interventions
Kehoe, Anne (2008) Experimental Analyses of Pain: Understanding Processes and Developing Interventions. PhD thesis, National University of Ireland Maynooth.
The current thesis compared the relative utility of acceptance and distraction-based interventions on the tolerance and distress of experimentally induced radiant heat pain. The research program comprised five automated experimental studies, including componential analyses to investigate the processes underpinning the use of acceptance and distraction as strategies for coping with pain. Chapter 1 provides a review of the available literature on clinical pain, including empirical evidence on its understanding and treatment. Chapter 2 incorporates two studies -- Experiments 1 and 1A. In Experiment 1 (n=128), acceptance- and distraction-based interventions were compared with a placebo intervention. Only the Acceptance group showed a significant increase in heat tolerance, Distraction participants did not and Placebo showed a significant decrease. In spite of the significant changes in heat tolerance, reported adherence to strategy was lower than expected. Experiment 1A (n=27) incorporated a modified version of the Distraction Intervention (referred to as Distraction 2). This modification was based on the hypothesis that the original distraction protocol had perhaps provided participants with an opportunity to defuse from the pain-related thoughts that may have exerted an unexpected but positive influence on the outcomes associated with the distraction protocol. As a result, the outcomes for Distraction 2 were then systematically compared with the original Acceptance and Distraction data (Distraction 1) from Experiment 1. Both Acceptance and Distraction 1 participants showed a near significant increase in tolerance, but Distraction 2 did not. Once again, reported adherence to strategy was low. Overall, the data from Experiment 1A suggested that the modest outcomes associated with Distraction in Experiment 1 may indeed have spuriously resulted from participants defusing, rather than distracting, from the pain-related thoughts Experiment 2 (n=39) reported in Chapter 3 attempted to match the Acceptance and Distraction protocols more closely, by encouraging all participants to engage in positive imagery, to determine key features of the interventions that had facilitated the differential outcomes. At its simplest, the different outcomes may have resulted from the fact that participants in the two key intervention groups were engaging in different experimental activities. This study also modified the adherence measures, which had not yielded strong outcomes thus far. One procedural modification employed to enhance adherence involved the introduction of a Values Clip that advised participants that their involvement in the research would be of indirect assistance to real sufferers of chronic pain. The results from Experiment 2 indicated strong adherence to intervention by all participants, which suggested the potential role played by the Values Clip. Furthermore, the data were supportive of the two previous studies when the Acceptance group showed a significant increase in heat tolerance, while Distraction showed a significant decrease. Experiment 3 (n=36) reported in Chapter 4 removed the Swamp Metaphor from the existing protocols in an attempt to determine the impact this may have had on the outcomes. The results indicated that once again, Acceptance was associated with a significant increase in pain tolerance, while Distraction was not. Unfortunately however, the strong adherence effects recorded previously were not maintained. Although these results initially suggested that the Swamp Metaphor had relatively little impact on outcomes, the low adherence data raised the possibility that the metaphor had been useful in facilitating greater understanding of, and adherence to, the experimental protocols. In Experiment 4 (n=42) reported in Chapter 5, the Swamp Metaphor was re-incorporated into both interventions because of its likely relationship with adherence. However, the Values Clip was now removed in order to determine what role this may have played in the outcomes from Experiments 2 and 3. The data here were consistent with the four previous studies, with significant pain tolerance increases for Acceptance, but not Distraction. However, adherence to intervention remained problematic. The current research extends existing evidence of the relative utility of acceptance and distraction as coping strategies for dealing with experimentally induced pain. In all five studies, Acceptance was associated with considerable increases in pain tolerance, Distraction was not. The work also represents the first attempt to employ clinical interventions with radiant heat pain as an analogue of clinical pain. The strong concordance of evidence across all five studies, as well as consistency with existing published findings, highlight the utility of the apparatus in this regard.
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