A Dual Mechanisms of Control Account of Age Differences in Working Memory

Age deficits in working memory (WM) can be large, but the exact sources are unclear. We hypothesized that young adults outperform older adults on WM tasks because they use controlled attention processes to prioritize the maintenance of relevant information in WM in a proactive-mode, whereas older adults tend to rely on the strength of familiarity signals to make memory decisions in a reactive mode. We used a WM task that cued participants to prioritize one item over others, and presented repeated lure probes that cause errors when one is engaging a reactive mode. Results showed that, relative to young adults with full attention available to use proactive-control during the delays, older adults with full attention (and young adults with divided attention) during the delays had exaggerated error rates to repeated lure probes compared to control probes. When the amount of proactive interference was increased (by repeating stimuli across trials), older adults were able to engage proactive control and this eliminated their exaggerated error rate (while young adults with divided attention could not). These results provide evidence for a dual-mechanisms of control account of age differences in WM.