The Impact of Auditory Distraction on Visual Memory Encoding in Middle-aged and Older Adults: A High-density Electroencephalography Study

Multitasking is essential for facing the complexity of everyday life environments, where the simultaneous processing of multiple information streams is ubiquitous, and it often requires an increased deployment of attentional resources to manage concurrent tasks. The physiological cognitive decline associated with aging further depletes cognitive resources, making it important to investigate the impact of aging on multitasking abilities, particularly in relation to the mnestic domain. To this aim, we investigated the impact of auditory distraction on visual memory encoding in older adults using high-density electroencephalography. Fifty healthy adults aged 48-72 yearscompleted a dual-task paradigm, combining visual memory encoding with an auditory sustained attention task. Behavioral performance was analyzed alongside neural correlates measured through ERPs and theta synchronization during high-density electroencephalography recordings. Participants demonstrated a decline in visual memory recognition performance under the more demanding dual-task condition, but with a stable cost across age. Increasing age negatively impacted overall performance but also subjective confidence. Neurophysiological data showed larger subsequent memory effect amplitudes and increased theta synchronization during dual-tasking, suggesting greater item-specific encoding. Source localization identified the left orbitofrontal and superior temporal gyri as well as the right opercular gyrus as key regions involved in memory encoding under distraction. Increased theta power at rest correlated with worse task performance in older adults, suggesting that neural processing efficiency declines with age. These findings highlight how multitasking interferes with memory encoding in adults, with significant neural recruitment to compensate for dual-task demands.