The Interactive Impact of Pain and Task Difficulty on Effort-Related Cardiovascular Reactivity

Abstract Objective Multiple evidence suggests that pain impairs cognitive task performance. However, much less is known about the impact of pain on cognitive effort, i.e., the mobilization of resources during cognitive task performance. The present experiment investigated how pain interacts with task difficulty to influence the allocation of effort. Methods Healthy volunteers were administered individually adjusted painful or nonpainful thermal stimulations during an easy or difficult cognitive task. Effort was assessed as cardiovascular reactivity during task performance, in particular the cardiac pre-ejection period (PEP). Based on pain research showing that pain adds supplementary demand on cognitive functioning, we expected pain to influence effort because it should increase subjective task difficulty. Consequently, drawing on motivational intensity theory, we predicted and found a crossover interaction between pain and task difficulty on PEP reactivity. Results Pain led to stronger effort than nonpainful stimulations in the easy task, which was expected due to additional pain-related demand. However, nonpainful stimulations led to stronger reactivity than painful stimulations in the difficult task, which was predicted due to too high required effort and disengagement in the pain condition. Moreover, our results showed that pain increased perceived task difficulty. Conclusions These findings provide first evidence that objective task difficulty moderates physical pain’s impact on effort assessed as cardiovascular response. Clinical implications in the context of chronic pain are discussed.