Distinct mechanisms for the impact of distraction and interruption on working memory in aging

Abstract

Interference is known to negatively impact the ability to maintain information in working memory (WM), an effect that is exacerbated with aging. Here, we explore how distinct sources of interference, i.e., distraction (stimuli to-be-ignored) and interruption (stimuli requiring attention), differentially influence WM in younger and older adults. EEG was recorded while participants engaged in three versions of a delayed-recognition task: no interference, a distracting stimulus, and an interrupting stimulus presented during WM maintenance. Behaviorally, both types of interference negatively impacted WM accuracy in older adults significantly more than younger adults (with a larger deficit for interruptions). N170 latency measures revealed that the degree of processing both distractors and interruptors predicted WM accuracy in both populations. However, while WM impairments could be explained by excessive attention to distractors by older adults (a suppression deficit), impairment induced by interruption were not clearly mediated by age-related increases in attention to interruptors. These results suggest that distinct underlying mechanisms mediate the impact of different types of external interference on WM in normal aging.

Figure 1

Interference conceptual framework.

Figure 2

Experimental Paradigm. All participants performed 4 tasks, which were blocked and counterbalanced.

Figure 3

Working Memory Accuracy and Impact of Interference. A) Participants performed best in the No Interference task (NI), followed by the Distractor task (DS), and then the Interruptor task (IS) (all comparisons are significantly different, p<.05). The older participants performed with a lower WM accuracy on all tasks. B) Older participants has a greater impact on WM performance by both the distractor (DS) and the interruptor (IS), when corrected by their performance without interference (p<.05). Note: asterisks represent significant differences between age groups.

Figure 4

Incidental Long Term Memory Recognition. Older participants recognized interfering stimuli presented in the experiment more than younger adults and remembered them as well as the cues stimuli. Note: single asterisks represent significant differences from 0, and double asterisks represent significant differences between ages/conditions.

Figure 5

Grand-Averaged Event Related Potentials to Intervening Stimuli. A) GAV ERPs from younger participants for Distractor stimuli (DS), Interruptor stimuli (IS) and passively viewed intervening stimuli (PV). B) ERPs from older participants. C) N170 latency measures to Intervening Stimuli. Both younger and older participants significantly enhanced the interruptors (earlier peaks compared to passively viewed intervening stimuli). Unlike younger adults, older participants also showed enhancement for the distracting stimuli. D) Comparisons of N170 latency attentional modulation indices between age groups. Older participants allocated more attention towards distractors than younger participants (suppression index), but did not differ in attention allocated towards interruptors (enhancement index).

Figure 6

Neurobehavioral correlations of the N170 latency attentional modulation indices. In both (A) younger and (B) older age groups, participants that enhance the interruptor more (upper panels) perform worse on the WM task. Likewise, participants that suppress the distractor more (upper panels) perform better on the WM task. Note: More positive value on the x-axis indicate greater enhancement above baseline or greater suppression below baseline.