The interaction between pain and cognition: on the roles of task complexity and pain intensity.

OBJECTIVES The interaction between pain and cognition includes a concurrent negative effect of pain on cognitive performance and an analgesic effect of cognitive distraction on pain experience. The purpose of this exploratory study was to investigate the role of pain intensity and task complexity on this interaction. METHODS Two experiments were conducted in healthy volunteers. In both experiments, participants completed 3 conditions: a pain only condition (consisting of the cold pressor test), a cognition only condition (consisting of the cognitive task) and a combined condition (concurrent administration of the cold pressor and cognitive task). In experiment I, participants performed one out of three possible tasks that differed in cognitive load (low, medium, high). In experiment II the parameters of the pain stimulus, induced by a cold pressor test, were adapted and only the high load cognitive task was employed. Pain scores, reaction times, and accuracy rates were recorded. RESULTS In experiment I, cognitive distraction significantly decreased pain scores, irrespective of the cognitive load of the task. Pain did not affect cognitive performance. In experiment II, pain diminished accuracy rates. No effect of cognitive distraction on pain was observed. Individual characteristics did not noticeably influence the interaction between pain and cognition. CONCLUSIONS The results of this study suggest a two-way interaction, however no evidence for a simultaneous bidirectional relationship was found. Cognitive distraction successfully reduces pain, up until a certain point where this relationship is reversed, and pain starts to interfere with cognitive performance. This may imply that priorities shift at a certain pain-threshold, however further research should confirm this hypothesis. This study could contribute to further understanding of cognitive mechanisms related to pain perception.