Does perceptual load influence auditory distraction processing in older adults?

• ¹ The HEARing CRC, Australia
• ² Western Sydney University, The MARCS Institute for Brain Behaviour and Development, Australia

Aim: To efficiently process target sounds in an environment of targets and non-targets requires that the irrelevant non-target sounds be ignored. Irrelevant sounds can however interfere with task performance because they capture attention (auditory distraction). Our previous work using a cross-modal distraction task showed that older adults can off-set the effects of distraction when the task requires involved top-down executive control, i.e., working memory (WM). The current experiment aimed to determine whether older adults could counter-act distraction effects by increased bottom-up attention in a unimodal distraction task. The degree of bottom-up attention was varied by manipulating the perceptual difficulty of the task, and distraction was measured electrophysiologically by examining ERPs. Method: We recorded ERPs from 24 older (62-76years) and 24 younger adults (21-35years) while they completed a tone duration classification task in an auditory oddball paradigm with novel auditory distractors. Listeners performed a duration classification task that required an easy or difficult discrimination (with the degree of difficulty individual tailored based on a pre-test). Results: ANOVA results revealed a main effect of task difficulty (more errors on the harder discrimination) and a main effect of age (older adults were slower and made more errors). There was a task difficulty effect on P3a (a neural indicator of attention switch to distractor) and RON (an index of switching back to task after distraction) with both older and younger adults exhibiting larger P3a and attenuated RON for difficult discrimination trials. There was no age effect or interaction (between task and age) for these ERPs. Conclusions: Increasing perceptual task load in a unimodal distraction paradigm had a similar effect on auditory distractor processing for younger and older adults. This contrasts with the effect of increasing WM load on crossmodal distraction where older adults showed a larger effect, and points to the importance of modality and type of load in understanding distraction processing in older adults.