Academic journal article Canadian Journal of Experimental Psychology

Differential Involvement of Knowledge Representation and Executive Control in Episodic Memory Performance in Young and Older Adults

Academic journal article Canadian Journal of Experimental Psychology

Differential Involvement of Knowledge Representation and Executive Control in Episodic Memory Performance in Young and Older Adults

Article excerpt

Craik and Bialystok (2006, 2008) postulated that examining the evolution of knowledge representation and control processes across the life span could help in understanding age-related cognitive changes. The present study explored the hypothesis that knowledge representation and control processes are differentially involved in the episodic memory performance of young and older adults. Young and older adults were administered a cued-recall task and tests of crystallized knowledge and executive functioning to measure representation and control processes, respectively. Results replicate the classic finding that executive and cued-recall performance decline with age, but crystallized-knowledge performance does not. Factor analysis confirmed the independence of representation and control. Correlation analyses showed that the memory performance of younger adults was correlated with representation but not with control measures, whereas the memory performance of older adults was correlated with both representation and control measures. Regression analyses indicated that the control factor was the main predictor of episodic-memory performance for older adults, with the representation factor adding an independent contribution, but the representation factor was the sole predictor for young adults. This finding supports the view that factors sustaining episodic memory vary from young adulthood to old age; representation was shown to be important throughout adulthood, and control was also important for older adults. The results also indicated that control and representation modulate age-group-related variance in episodic memory.

Keywords: episodic memory, aging, knowledge representation, executive control

Research has shown that episodic memory involves both age-related losses and compensation mechanisms. Episodic memory is defined as the kind of memory that enables conscious recollection of personal happenings and events from the past (Wheeler, Stuss, & Tulving, 1997). It is classically assessed by free-recall, cued- recall, and recognition tasks.

In a seminal article, Craik and Bialystok (2006) proposed a framework comprising two components, cognitive representation and control, to account for these cognitive changes across the life span, and particularly during adulthood. This framework builds on Cattell's model (1971), distinguishing between crystallized and fluid processes by specifying key factors explaining not only cognitive performance at a given period of life, but also cognitive changes across the life span. Representations are defined as the set

of crystallized schémas that are the basis for memory and knowl- edge of the world. Control is the set of fluid operations that enable executive adaptive processes. According to Craik and Bialystok (2006), representations are crystallized schémas and can therefore be measured with classic tests of knowledge ability, such as the vocabulary and information subtests of the Wechsler Adult Intel- ligence Scale (WAIS; Wechsler, 1981). By contrast, control in- volves executive processes and can thus be measured using stan- dard executive-function tasks, whose main goal is to overcome the prepotent "default mode" of automatic behaviour.

These two factors are also assumed to have different life-span trajectories. Representational knowledge increases during child- hood, continues to accumulate at a slower pace throughout adult- hood, and remains relatively stable in old age. This is the pattern classically depicted for crystallized abilities (Cattell, 1971; Horn, 1982). By contrast, cognitive control increases in power, speed, and complexity from infancy to young adulthood, and declines thereafter, as shown for fluid abilities (Cattell, 1971; Horn, 1982). Craik and Bialystok (2006) suggest that the relative growth and decline of these two factors may help explain the role played by these two components in sustaining cognitive abilities (e.g., intel- ligence, language, and memory) at different periods of life. …

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