Enhancing tonic arousal improves voluntary but not involuntary attention in humans

Arousal and attention are fundamental brain functions that play a critical role in optimizing performance. Kahnemans attention model (1973) theorizes a key interplay between attention and arousal, yet this relationship remains poorly understood. Using a multimodal approach, we investigated this interaction in healthy young adults performing an auditory attention task designed to simultaneously assess phasic arousal, voluntary attention, and involuntary attention. Furthermore, tonic arousal was experimentally modulated with low or high arousing music, as confirmed by changes in pupil size and heart rate. Behavioral data confirmed that informative cues enhanced voluntary attention, while unexpected salient task-irrelevant sounds (so-called distractors) produced either shortened or lengthened reaction times depending on their timing relative to target onset. Physiological data indicated that the facilitation effect of distractors on reaction times was driven by increases in phasic arousal. This benefit was further modulated by a dynamic interplay between phasic arousal and voluntary attention over time. Supporting Aston-Jones and Cohens theory, a fronto-central cortical response to distractors revealed that tonic and phasic arousal interact in line with an inverted U-shaped relationship. This study provides empirical evidence, in humans, that tonic arousal can optimize performance by tuning phasic arousal and attentional control.