Academic journal article Memory & Cognition

Working Memory and Intraindividual Variability in Processing Speed: A Lifespan Developmental and Individual-Differences Study

Academic journal article Memory & Cognition

Working Memory and Intraindividual Variability in Processing Speed: A Lifespan Developmental and Individual-Differences Study

Article excerpt

Published online: 24 December 2014

© Psychonomic Society, Inc. 2014

Abstract Working memory (WM) and intraindividual variability (IIV) in processing speed are both hypothesized to reflect general attentional processes. In the present study, we aimed at exploring the relationship between WM capacity and IIV in reaction times (RTs) and its possible variation with development across the lifespan. Two WM tasks and six RT tasks of varying complexity were analyzed in a sample of 539 participants, consisting of five age groups: two groups of children (9-10 and 11-12 years of age), one group of young adults, and two groups of older adults (59-69 and 70-89 years of age). Two approaches were adopted. First, low-span and high-span individuals were identified, and analyses of variance were conducted comparing these two groups within each age group and for each RT task. The results consistently showed a span effect in the youngest children and oldest adults: High-span individuals were significantly faster and less variable than low-span individuals. In contrast, in young adults no difference was observed between high- and low-span individuals, whether in terms of their means or IIV. Second, multivariate analyses were conducted on the entire set of tasks, to determine whether IIV in RTs brought different information than the mean RT. The results showed that, although very strongly correlated, the mean and IIV in speed should be kept separate in terms of how they account for individual differences in WM. Overall, our results support the assumption of a link between WM capacity and IIV in RT, more strongly so in childhood and older adulthood.

Keywords Aging . Development . Individual differences . Reaction time analyses/methods . Working memory . Intraindividual variability

The objective of the present article is to address the issue of the relationship between working memory (WM) capacity and within-task intraindividual variability (IIV) in reaction time (RT) tasks, investigating whether this relationship might vary across the lifespan. In this introduction, we will briefly present our approach to WM-in conformity with the demand of the editor of this special issue-and then discuss why a potential relationship can be hypothesized between WM and IIV and whether individual differences in WM could be related to IIV.

As a number of researchers interested in developmental and/ or individual differences in WM, we consider the performance in WM tasks to be determined by a set of underlying attentional processes. These processes, such as the activation and inhibition of relevant informational units, are considered to become more efficient with age, accounting for part of cognitive development in children, and to vary in efficacy across individuals. We consider WM to be an index of what has frequently, and rather loosely, been labeled general resources.WMcapacity,while remaining severely limited, increases with age both because of an increase in neurobiological mechanisms and because the use of resources becomes more efficient with experience. There is here a major point of departure between cognitive experimentalists, on the one hand, and developmentalists and differentialists, on the other hand. The first group is interested in the functioning and underlying processes of WM and suggests the existence of a WM system; the latter researchers are primarily interested in the capacity of WM, its changes with age and across individuals, and its predictive character with respect to other, more complex aspects of cognition. According to that second perspective, the processes and mechanisms underlying WM are not necessarily specific to a WM system. Baddeley and Hitch's(1974) initial WM model, which proved so fruitful in yielding an enormous amount of experimental studies, is the leading model of the first type of approach, whereas PascualLeone's(e.g.,1987) approach and, more generally, neoPiagetian models are representatives of the latter perspective. …

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