The Interplay of Bottom-Up Arousal and Attentional Capture during Auditory Scene Analysis: Evidence from Ocular Dynamics

Abstract

The auditory system plays a crucial role as the brains early warning system. Previous work has shown that the brain automatically monitors unfolding auditory scenes and rapidly detects new events. Here, we focus on understanding how automatic change detection interfaces with the networks that regulate arousal and attention, measuring pupil diameter (PD) as an indicator of listener arousal and microsaccades (MS) as an index of attentional sampling. Naive participants (N=36; both sexes) were exposed to artificial scenes comprised of multiple concurrent streams of pure tones while their ocular activity was monitored. The scenes were categorized as REG or RND, featuring isochronous (regular) or random temporal structures in the tone streams, respectively. Previous work showed that listeners are sensitive to predictable scene structure and use this information to facilitate change processing. Scene changes were introduced by either adding or removing a single tone stream. Results revealed distinct patterns in the recruitment of arousal and attention during auditory scene analysis. PD was greater in REG scenes compared to RND, indicating heightened arousal in unpredictable contexts. However, no differences in overall MS activity were observed between scene types, suggesting no differences in attentional engagement. Scene changes--though unattended-- elicited both PD and MS suppression, consistent with automatic attentional capture and increased arousal. Notably, only MS responses were modulated by scene regularity. This suggests that changes within predictable environments more effectively recruit attentional resources. Together, these findings offer novel insights into how automatic auditory scene analysis interacts with neural systems governing arousal and attention. Significance StatementEven without active listening, our brains automatically respond to changes in complex sound environments--like noticing a new sound on a busy street. These responses involve shifts in arousal and attention, helping us decide how to react, often without conscious awareness. Understanding this process is key to studying how we perceive sound scenes and how it may be disrupted in individuals with attention or arousal difficulties. In this study, participants passively listened to artificial soundscapes while we tracked eye activity: pupil dilation (a sign of arousal) and microsaccades (tiny eye movements linked to attention). We found that sudden scene changes triggered both responses, but they were differently influenced by scene predictability--suggesting they reflect separate aspects of automatic auditory processing.