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Working memory (WM), the temporary maintenance of a limited amount of information in an accessible state, is required for the performance of many tasks. Studies have shown that WM demands are related to the neural processing of tasks requiring attention: Age affects the ERP components associated with WM context updating processes in the visual oddball task (P3) and semantic processing in the word-pair judgment task (N400). This study investigated whether WM capacity measured by complex span tasks mediates the effects of age on these ERPs. Younger adults (YA, n = 44, ages 18–23 yr) and older adults (OA, n = 41, ages 69–89 yr) completed operation, reading, and symmetry complex span tasks and two ERP tasks (P3/visual oddball; N400/word-pair judgment). Results showed age-related differences for all complex span tests. Principal components analysis of these tests showed a single factor for both groups, so a combined WM capacity factor score was created. Regressions of age group and WM factor score on P3 and N400 amplitudes and latencies showed that OAs had relatively lower amplitudes and longer latencies. However complex span was not related to P3 or N400 amplitudes or latencies and that result was the same for younger and older adults; that is, complex span did not mediate the age effects. WM processes indexed by the P3 and N400 components appear to be different from those elicited by complex span tasks. Attentional control processes of WM influence oddball and semantic judgement tasks more than storage components. 

We explored neural processing differences associated with aging across four cognitive functions. In addition to ERP analysis, we included task-related microstate analyses, which identified stable states of neural activity across the scalp over time, to explore whole-head neural activation differences. Younger and older adults (YA, OA) completed face perception (N170), word-pair judgment (N400), visual oddball (P3), and flanker (ERN) tasks. Age-related effects differed across tasks. Despite age-related delayed latencies, N170 ERP and microstate analyses indicated no age-related differences in amplitudes or microstates. However, age-related condition differences were found for P3 and N00 amplitudes and scalp topographies: smaller condition differences were found for in OAs as well as broader centroparietal scalp distributions. Age group comparisons for the ERN revealed similar focal frontocentral activation loci, but differential activation patterns. Our findings of differential age effects across tasks are most consistent with the STAC-r framework which proposes that age-related effects differ depending on the resources available and the kinds of processing and cognitive load required of various tasks.