Enhancing tonic arousal improves voluntary but not involuntary attention in humans

Arousal and attention are pivotal brain functions for optimizing performance. Kahneman’s attention model (1973) theorizes a key interplay between attention and arousal, yet this relationship remains poorly understood. We investigated this interaction in 16 healthy young adults performing an auditory attention task that simultaneously assessed phasic arousal, voluntary attention and involuntary attention. Tonic arousal was modulated by low or high arousing music, as measured using skin conductance, pupil size, and heart rate. Pupil dilation responses to distracting sounds highlight an intricate interplay between tonic and phasic arousal. Importantly, increasing tonic arousal does not influence involuntary attention, whereas it does improve voluntary attention, as shown by shorter and less variable reaction times and larger electroencephalographic brain responses to task-relevant targets. This study provides experimental evidence in humans that tonic arousal can influence the attentional balance by improving voluntary attention in a transient and sustained manner, rather than by impacting involuntary attention.