Subjective salience ratings are a reliable proxy for physiological measures of arousal

Pain is an inherently salient multidimensional experience that warns us of bodily threat and promotes escape behaviours. Stimuli of any sensory modalities can be salient depending on stimulus features and context. This poses a challenge in delineating pain-specific processes in the brain, rather than salience-driven activity. It is thus essential to salience match control (innocuous) stimuli and noxious stimuli, in order to remove salience effects, and identify pain-specific activity. Previous studies have salience-matched either through subjective salience ratings or the skin conductance response (SCR), the latter of which serves as a physiological measure of arousal. Though an objective measure that overcomes the nebulous construct of salience, SCR cannot be used to salience-match in real-time (i.e., during an experiment) and assumes an association between salience and physiological arousal elicited by painful and non-painful stimuli, but this has not been explicitly tested. To determine whether salience and physiological arousal are associated, sixteen healthy adults experienced 30 heat pain and 30 non-painful electric stimuli of varying intensities. Stimuli were subjectively matched for salience and physiologically matched for arousal using SCR. A linear mixed model found no differences in SCR between salience-matched heat and electric stimuli. A mediation analysis showed that salience fully mediated the relationship between stimulus intensity and SCR ( proportion mediated=84% ). In conclusion, salience and physiological arousal are associated, and subjective salience ratings are a suitable for salience-matching pain with non-painful stimuli. Future work can thus use subjective salience ratings to delineate pain-specific processes.