Components of Working Memory Updating

Components of Working Memory Updating Ullrich K. H. Ecker (ullrich.ecker@uwa.edu.au) School of Psychology, University of Western Australia 35 Stirling Hwy, Crawley, WA 6009, Australia Stephan Lewandowsky (lewan@psy.uwa.edu.au) School of Psychology, University of Western Australia 35 Stirling Hwy, Crawley, WA 6009, Australia Klaus Oberauer (K.Oberauer@bristol.ac.uk) Department of Experimental Psychology, University of Bristol 12a Priory Rd, Bristol, BS8 1TU, UK WM Updating and Individual Differences Abstract The pattern of correlations between tasks can address issues relating to the number and nature of processes or components involved in WM. For instance, Oberauer and colleagues (e.g., Oberauer, S¨us, Schulze, Wilhelm, & Wittmann, 2000) have used such an individual differences approach to decompose the WMC construct into functional components, which were then related to higher cognitive functions. We already noted that WMU has also been found to pre- dict such higher functions; however, most studies have mea- sured WMU by the accuracy on WM tasks that require up- dating, such as a running memory task. This does not sup- ply a pure measure of WMU, and therefore we do not know whether the correlation between the “updating” factor and intelligence reflects a relationship between intelligence and WMU, or intelligence and WMC. Indeed, some researchers have claimed that there is only a weak link between WMU and WMC (e.g., Radvansky & Copeland, 2001), so on the one hand, WMU and WMC may be dissociable dimensions. On the other hand, prominent theories of WM that assume a tight link between WMC and executive functions (e.g., Kane et al., 2004) should predict that WMU and WMC are closely related because WMU is regarded as one executive function. Working memory updating (WMU)—the ability to maintain accurate representations of information changing over time— has been successfully used in individual differences research to predict higher cognitive abilities. For instance, WMU has been found to predict fluid intelligence and reading com- prehension. However, little is known about the underlying component processes of WMU or the relationship between WMU and working memory capacity (WMC). A decomposi- tion of WMU into three distinct components—retrieval, trans- formation, and substitution—was implemented into a standard WMU paradigm. Experimental conditions featured every pos- sible combination of these components. The decomposition was used to analyze the relationship between WMU subcom- ponents and WMC. We utilized structural equation modeling in a novel way, in that both interindividual variability and ex- perimental effects on mean performance measures (RT and ac- curacy) were accounted for concurrently. Results suggest that the proposed components make distinct and additive contribu- tions to WMU. We found that WMC reliably predicts WMU in general, but also that some components of WMU are inde- pendent of WMC. Hence, WMU and WMC may make inde- pendent contributions in predicting higher mental abilities. Keywords: working memory updating; working memory ca- pacity; individual differences; structural equation modeling Working memory (WM) can be characterized as a col- lection of mechanisms for holding selected representations available for further cognitive processing. One implication of the involvement of WM in many cognitive tasks is that the content of WM must be continuously updated. For instance, a task like keeping score in a tabletennis match involves up- dating one of two numbers in WM after each rally. WM updating (WMU from here on) has been identified as one of three factors reflecting individual differences in ex- ecutive functions, and the only one to reliably predict fluid intelligence (Friedman et al., 2006; Miyake et al., 2000). Ac- cordingly, WMU has been linked to reading comprehension skills (Palladino, Cornoldi, De Beni, & Pazzaglia, 2001). The acknowledged importance of WMU stands in contrast to the lack of understanding of the underlying component pro- cesses (for similar arguments, see Kessler & Meiran, in press; Oberauer & Kliegl, 2001). Our study seeks to fill this void by (a) experimentally manipulating components involved in up- dating and (b) considering how those components relate to individual differences in WM capacity (WMC). The Present Study We began our examination by conducting a task analysis of previously-used WMU paradigms. We identified 3 pu- tative sub-processes of WMU; retrieval (R), transformation (T), and substitution (S). Our experiment orthogonally ma- nipulated these three components, thus permitting their em- pirical identification and assessment of their interrelationship. Further, our study included 4 independent working memory tasks, thus permitting a reliable estimate of each participant’s WMC. These WMC estimates were then statistically related to the individual components of WMU isolated by our exper- imental manipulations. Method Participants Ninety-seven psychology students from the University of Western Australia participated in the two experimental ses-