Tuned to explore: Increased phasic responses to auditory targets and novelty in children regardless of induced tonic arousal

The ability to focus on relevant information while ignoring distractions is critical during childhood, as it supports learning, social interaction, and adaptation to changing environments. This attentional balance is thought to depend in part on arousal regulation, mediated by the activity of the locus coeruleus norepinephrine (LC-NE) system. Moderate levels of arousal are typically associated with optimal cognitive performance. However, the interaction between arousal and attention remains poorly understood in humans, especially during development. In this study, we investigated whether experimentally modulating tonic arousal, the baseline level of physiological alertness, affects attentional processing in children (N = 44, aged 6-8) and adults (N = 46, aged 18-35). Participants performed an active auditory three-stimulus (standard, novel, target) oddball task, designed to assess selective attention to target tones and distraction by novel sounds. Prior to each task block, tonic arousal was manipulated using music or videos varying in arousing content. Physiological responses were recorded continuously (skin conductance, pupil dilation, heart rate) to index both tonic arousal and transient, phasic changes in arousal triggered by task events. While tonic arousal modulation was successful, as confirmed by skin conductance levels, Bayesian analyses provided evidence for no effect of this modulation on subsequent attentional processing. Importantly, children generally exhibited stronger phasic arousal responses, particularly to task-irrelevant novel sounds, reflecting less mature regulation of attention and arousal. These findings show developmental differences in physiological responses to unexpected environmental stimuli and provide physiological evidence of increased distractibility during childhood.