VIEILCOG

In cognitive domains as varied as attention, memory, language, problem solving, reasoning, decision making, skill learning, psychologists found negative effects of age on human cognition. Research in cognitive aging enables to understand issues as crucial as: which cognitive skills decline with age and which remain stable (or even improve), why some people age better than others, what are the underlying mechanisms of deleterious effects of age on cognitive performance, and how to help older adults to compensate for cognitive aging. The present project will further our understanding of these important issues. The present project is based on two sets of facts in cognitive aging (see Lemaire & Bherer, 2005, for a recent review). First, age-related declines in cognitive performance are correlated with age-related changes in strategic variations. Young and older adults differ in the type of strategies they use to accomplish cognitive tasks, as well as in how they select and execute available strategies. Moreover, age-related declines in cognitive performance seem to depend on age-related changes in executive functions. Executive functions are higher order mental operations concerned with the maintenance, manipulation, planning, monitoring, and regulation of other cognitive processes that are responsible for perception, memory, reasoning, problem solving, language, and action. Executive functions involve a variety of abilities such as self-regulation, planning, organization, and the ability to initiate, maintain, switch, and stop sequences of complex behaviour. Cognitive declines interact with executive functions, such that older people with poor executive functions decline more than older adults with good executive functions. However, we do not know the boundary conditions for such interaction (or in which cognitive domains it is observed and in which it is not present) and, most importantly, how it occurs (i.e., by which mechanisms). This project has two general goals and specific objectives. First, the data collected will further our understanding of age-related changes and similarities in strategic aspects of cognitive performance in arithmetic, episodic memory, and skill acquisition. Second, we shall investigate age-related declines in executive functions, and examine how these declines modulate changes in strategic variations and performance during aging. Moreover, at more specific levels, we shall (a) investigate the costs of strategy switching in young and older adults and effects of varying domain, task, or problem parameters on these costs, (b) examine the mediating role of executive functions on age-related differences in strategy switch costs, and which of the three main executive functions (inhibition, flexibility, updating) is the most crucial in strategic behaviours and age-related differences in these behaviours, and (c) reveal neural bases of strategic behaviours in general, and of strategy switch costs in particular, in young and older adults. Specific domains will be arithmetic, memory, and skill acquisition, three key domains to further understand cognitive aging. In each domain, young and older adults will be compared. Both groups (each including between 25 and 50 / experiment) will be matched on a variety of factors (e.g., education), and older adults will be screened for potential Alzheimer's disease. Participants will be tested under a variety of experimental conditions, and the role of participants' executive functions will receive empirical scrutiny. We shall collect behavioural data (performance, verbal protocols, eye movements) and brain-imaging (fMRI and ERP) data to understand mechanisms underlying cognitive aging and factors of successful aging. The present findings will (a) enable us to describe how conditions and individual characteristics modulate neural and cognitive mechanisms underlying age-related declines in performance, (b) provide a complete and detailed description of variations in behavioural and neural variations in the three specific cognitive domains investigated here, (c) yield the basic findings necessary to elaborate a mechanistic model of non-protective and protective effects associated to several variables, with such a model being also useful to understand cognitive impairment during early stages of Alzheimer's disease, and (4) determine the nature of neural (e.g., reduced hemispheric asymmetry, hypo-/hyper-neural activations) changes that accompany aging. All in all, our findings will further our understanding of mechanisms underlying cognitive declines during aging, how participants adjust to these cognitive declines, and compensate negative impacts of aging on human cognition. Implications of the findings of this project will be important for both theoretical reasons (they will improve our understanding of cognitive aging) and practical reasons (they will contribute in helping older adults to age successfully).