Postdeviance Distraction in Younger and Older Adults: Neuro-Behavioral Evidence From Speech Perception

摘要

Older adults are usually more easily distracted by task-irrelevant stimuli than younger ones. In addition, there is evidence that it takes them more time to overcome a distracting event. Here, the distracting effect of irregular switches in speaker location was studied in 22 younger and 22 older adults in a speech perception task. The participants responded to target words that were presented either from a frequent location (standard trials) or a rare location (deviant trials). Behavioral performance measures, event-related brain potentials (ERPs), and EEG synchronization (intertrial coherence [ITC]) were analyzed. Behavioral performance was not only decreased in deviant trials, but also in subsequent standard trials, indicating an effect of so-called postdeviance distraction. The negative impact of the distracting event (i.e., the switch in speaker location) on the processing of subsequent (standard) trials was more pronounced in the older versus younger group. The EEG analyses revealed a decreased N2 amplitude and increased latencies in P2 and P3a in the older group, suggesting a reduced and delayed attentional control. Moreover, there were age-related changes in late (200-450 ms) theta ITCs: While the ITC of the young remained constant in trials following a deviant, the ITC of the old decreased, suggesting a decline in processing of stimuli following (task-irrelevant) switches in speaker location. This could contribute to age-related deficits in speech comprehension in spatially variable listening situations.