Salience or value: what drives priority in pain-cognition interactions?

The evolutionary function of pain is to protect against injury by capturing attention and motivating nocifensive behavior. This makes pain inherently salient and capable of disrupting the pursuit of competing goals. However, this interference can sometimes be overridden by concurrent demands. We have yet to discover how priority is assigned when pursuing competing goals while experiencing pain: through attentional resource competition (salience-based) or motivational conflict (value-based), or both. We investigated these different mechanisms in a study in which 40 healthy adults completed the cognitive branching paradigm, which comprises 2 nested backward letter-matching tasks, 1 with a low-value reward ($0.05) and the other with a high-value reward ($1). Participants performed the tasks first without stimulation and then under 2 conditions: tonic painful heat and tonic nonpainful electric stimuli that were matched for salience. We analyzed performance using linear mixed models and conducted post-hoc Bayesian tests for significant interactions. We found that pain selectively disrupted the low-value task, but not the high-value task, indicating that priority assignment was value-based, whereas the electric stimulus had no impact on task performance. In addition, sex-disaggregated analyses showed that this effect was exclusively seen in males, whereas females exhibited no significant impact of pain on task performance. Our findings suggest that motivational conflict, rather than resource competition, determines priority assignment when pain is concurrent to competing demands. In addition, we show for the first time, sexually dimorphic mechanisms in pain-cognition interactions, which contributes to an emerging literature of sex differences in pain mechanisms and behaviours.