Older adults are impaired by distractors presented during working memory encoding.

Working memory (WM) performance declines across the lifespan, partly due to greater vulnerability to distractors in the environment. Successful working memory relies on resistance to distractors, which may enter memory due to ineffective filtering during simultaneous presentation with targets (i.e., during encoding), or due to insufficient ability to ignore them during maintenance. Prior research offers mixed conclusions regarding whether impaired distractor suppression contributes to older adults' (OA) WM deficits. Across three behavioral experiments, we found consistent evidence that OA were more vulnerable to distractors presented during encoding than during maintenance. Unexpectedly, the familiarity of the distractor items had limited impact on performance, whereas low-salience distractors presented during encoding produced robust decrements in accuracy and increases in reaction time. These results demonstrate that distraction during encoding is a driver of WM disruption in older adults, even when the distractors are subtle.