Gavrilova, S.I.

Background. Aging is associated with decline in various cognitive functions, including task switching – the ability to shift quickly between tasks and mindsets. Previous research has shown that older adults exhibit less efficient task switching. Mathematical modeling of cognitive processes involved in switching between tasks may shed light on the sources of switching inefficiency in normal and pathological cognitive aging.

Objective. To investigate possible sources of task-switching decline in normal and pathological (mild cognitive impairment, MCI) cognitive aging using the Diffusion Model (DM). 

Design. 57 young adults, 34 healthy older participants, and 5 MCI-diagnosed older participants performed the commonly used Number-Letter switching task. Reaction times (RT) and accuracy were measured and Diffusion Models were fitted to individual reaction time distribution to obtain parameters characterizing processes involved in task switching: active, controlled task-set reconfiguration; passive, automatic task-set inertia; and response caution. 

Results. Older age and MCI-pathology-related effects on switching efficiency were found for RT and, partly, for accuracy. After controlling for possible age differences between the two older groups, active processes of task-set reconfiguration had a clear MCI-related deficit, while passive, automatic task-set inertia components only exhibited a general effect of aging (pathological or not). Response caution was only related to older age, with no MCI effect.

Conclusion. Effortful task-set reconfiguration is sensitive to both age and MCI pathology, while passive processes of task-set inertia dissipation is only subject to age changes. The results support the idea of different dynamics of controlled and automatic cognitive processes in normal and pathological (MCI) aging.