Dual Mechanisms of Control in Cognitive and Motor Aging

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Executive functions (EFs) encompass a variety of cognitive control processes implicated in complex activities such as multitasking and coordinated action. As such, EFs can influence the success or failure of activities of daily living in old age. The Dual Mechanisms of Control (DMC) theory (Braver et al., 2007) postulates two modes of cognitive control. In the Proactive mode, goal-relevant information is actively maintained in working memory, biasing attention to prevent interference. In the Reactive mode, when no task-relevant cues are available, control is recruited on a just-in-time basis. The DMC framework assumes that whereas reactive control is maintained in old age, proactive control declines. Presently, support for these assumptions is largely based upon simple keyboard reaction time tasks (AX-CPT, Stroop, Flanker). Given the ubiquity and importance of cognitive control in complex task performance, a logical next step is to test the DMC model in tasks that better approximate everyday activities. The major objective of the proposed research program is, therefore, to examine the DMC theory and its applications across a range of cognitive, visuo-manual, and gross motor EF paradigms.***Using my currently held NSERC funds, my lab has examined the role of EFs in a broad variety of cognitive and motor paradigms (updating, task switching, motor dual tasking), in young and older adults. To date, we have tested the assumptions of the DMC framework only in a cognitive context. We therefore aim to adapt our existing visual-manual and postural control paradigms to systematically vary the proactive and reactive control demands in these new contexts. We anticipate that young adults will flexibly deploy reactive and proactive control. In contrast, older adults will employ reactive control, and their task performance will suffer when only proactive control can be used. ***Together, the planned research is expected to advance current understanding of DMC theory and map out the limits of its applicability across a broader range of EF contexts. Evaluation of the DMC principles in the domains of fine and gross motor control is entirely novel. Identifying contexts in which declining proactive control puts elders at risk will inform the design of training protocols and assistive devices to improve the everyday functioning of older adults. **