Intra‐individual variability in task performance after cognitive training is associated with long‐term outcomes in children

Abstract

The potential benefits and mechanistic effects of working memory training (WMT) in children are the subject of much research and debate. We show that after five weeks of school‐based, adaptive WMT 6–9 year‐old primary school children had greater activity in prefrontal and striatal brain regions, higher task accuracy, and reduced intra‐individual variability in response times compared to controls. Using a sequential sampling decision model, we demonstrate that this reduction in intra‐individual variability can be explained by changes to the evidence accumulation rates and thresholds. Critically, intra‐individual variability is useful in quantifying the immediate impact of cognitive training interventions, being a better predictor of academic skills and well‐being 6–12 months after the end of training than task accuracy. Taken together, our results suggest that attention control is the initial mechanism that leads to the long‐run benefits from adaptive WMT. Selective and sustained attention abilities may serve as a scaffold for subsequent changes in higher cognitive processes, academic skills, and general well‐being. Furthermore, these results highlight that the selection of outcome measures and the timing of the assessments play a crucial role in detecting training efficacy. Thus, evaluating intra‐individual variability, during or directly after training could allow for the early tailoring of training interventions in terms of duration or content to maximise their impact.

Adaptiveness of fluctuations in intra-individual variability of performance is process-dependent in middle childhood

“…Importantly, Going IIV showed a gradual reduction over the training weeks, as well as marked reductions after training: sigma was reduced immediately after training (although note these effects did not show long-term maintenance), and tau showed a long-term reduction. Thus, consistent with the correlations at T0 and previous studies (Cubillo et al 2022;Ram et al 2005) the response speed training led to improvements in Going efficiency (i.e. more consistent (reduction in sigma) and less degree and variability in occasional extremely slow responses (reduction in tau)), supporting the notion that reductions in Going IIV are adaptive (Unsworth 2015;MacDonald, Li, and Bäckman 2009;West et al 2002).…”

“…This notion is supported by studies showing that IIV follows a U-shaped function over the lifespan, where IIV decreases from childhood into young adulthood (reflecting optimisation of cognitive processing) and increases again in the elderly (reflecting a decline in cognitive function) (Williams et al 2005;MacDonald, Nyberg, and Bäckman 2006). A recent cognitive training study also shows that, after a working memory training, children show better accuracy and reduced IIV in working memory and selective attention tasks (Cubillo et al 2022), consistent with the idea that training improves efficiency and stability in cognitive processing (von Bastian and Oberauer 2014). Similar findings have been reported in older adults, where repeated practice of memory speed tasks results in IIV reductions (Ram et al 2005).…”

“…Fluctuations in performance are a hallmark of cognitive processing over the lifespan (Shalev, Bauer, and Nobre 2019), and previous research shows that intra-individual variability (IIV) measures of performance are more sensitive to developmental differences than conventional mean measures (Tamnes et al 2012). This has resulted in a wealth of investigations using IIV measures of cognitive performance as markers of development-, ageing-and training-related changes (Tamnes et al 2012;MacDonald, Hultsch, and Dixon 2003;Cherbuin, Sachdev, and Anstey 2010;Cubillo et al 2022;Ram et al 2005). The prevailing assumption is that reductions in IIV are adaptive because cognitive performance becomes more consistent and optimised (MacDonald, Nyberg, and Bäckman 2006;Williams et al 2005;Cubillo et al 2022;Ram et al 2005).…”

“…This has resulted in a wealth of investigations using IIV measures of cognitive performance as markers of development-, ageing-and training-related changes (Tamnes et al 2012;MacDonald, Hultsch, and Dixon 2003;Cherbuin, Sachdev, and Anstey 2010;Cubillo et al 2022;Ram et al 2005). The prevailing assumption is that reductions in IIV are adaptive because cognitive performance becomes more consistent and optimised (MacDonald, Nyberg, and Bäckman 2006;Williams et al 2005;Cubillo et al 2022;Ram et al 2005). However, some studies also report an adaptive role of IIV increases, suggesting that IIV may not consistently reflect the same phenomenon across cognitive domains or even within the same individual (Allaire and Marsiske 2005).…”

“…However, they also point out the complexity of defining the functional role of IIV at different lifespan stages and within different cognitive domains. In this sense, training studies hold the potential to provide rich insight into how IIV of different cognitive processes is modulated when performance is causally manipulated to become more efficient and stable (von Bastian and Oberauer 2014;Cubillo et al 2022). Here, we aimed to address this question in the context of response speed and inhibitory control during middle childhood.…”