Storage and processing in working memory: Dual-task costs, prioritization, and short-term consolidation across the adult lifespan

The extent to which dual-task performance declines with advancing age remains subject to debate. For example, tasks requiring the simultaneous storage and processing of information yield age differences in some studies but not in others. One possible explanation for this inconsistent pattern of findings is the difficulty in comparing dual-task performance between age groups when they differ in single-task performance. Alternatively, there may be a specific age-related deficit in the ability to coordinate storage and processing, or in controlling priority given to one or other task. We investigated these possible accounts in two experiments designed to modulate the size of the dual-task cost across the adult lifespan. For memory, we observed a large dual-task cost which increased with age, but no general dual-task cost for the processing task. Shifting priority between tasks induced a trade-off that did not differ with age. These findings support the notion that age does not affect the ability to coordinate storage and processing in working memory tasks, as older participants were just as able as younger participants to favour the performance of one task over the other in response to instruction. Rather, the effect of age appears to be a general drop in memory performance when required to perform simultaneous processing that may reflect increased susceptibility to interference or difficulty in task switching.