Short-term storage is a stable predictor of fluid intelligence whereas working memory capacity and executive function are not: A comprehensive study with Iranian schoolchildren

Cultural Influences on the Development of Children's Memory and Cognition

Memory is socially constructed. The types of information that children pay attention to and remember, as well as how children organize and recall their memories can differ as a function of sociocultural background. This chapter presents an overview of cultural variations on children's memory and cognition. We draw attention to the necessity of conducting controlled experiments to examine cultural differences in the specific processes involved in episodic memory (e.g., encoding, retention, discrimination skills). We highlight potential challenges (e.g., language, measurement equivalence) that researchers need to overcome to conduct valid cross-cultural research. In light of cultural transformations in recent decades, we outline promising avenues for future research as well as the applications of this research to important issues for forensics and immigrants and asylum-seekers.

Individual differences in working memory and general intelligence indexed by P200 and P300: A latent variable model

A robust relationship between working memory (WM) and general intelligence (g) has been well established. Nevertheless, explanations for this relationship in terms of underlying neurocognitive processes are still inadequate. This study addresses this issue using an individual differences approach in which Central Executive System (CES) and Short-Term Storage (STS) components of WM are measured comprehensively and examined for their relationship with g via event-related potentials components (P200 and P300) as mediators. Participants (n = 115) completed tests of the WM, CES and STS, as well as g. P200 and P300 components were recorded during 3-back WM task performance. Structural equation modelling showed significant negative associations between the P200 latency for target stimuli and CES shifting processes, and between the P300 amplitude for target stimuli and CES inhibition and updating processes. The relationship between CES processes and g was mediated in a localized fashion by the P300 amplitude. These findings further support the notion that the CES has a multidimensional structure and, importantly, reveal that the inhibition and updating functions of the CES are crucial in explaining the relationship between WM and g. Negative relations between ERP indices (P200 latency and P300 amplitude for target stimuli) and g support a neural efficiency hypothesis related to high intelligence.

Does the structure of working memory in EL children vary across age and two language systems?

This study examined the cross-sectional structure of working memory (WM) among elementary school English learners (ELs). A battery of WM tasks was administered in Spanish (L1) and English (L2) within five age groups (ages 6, 7, 8, 9, & 10). Confirmatory factor analysis showed a three-factor structure of WM emerged in both L1 and L2 administrations for each age group. The important findings, however, were: (1) the separation between the executive component and storage component (phonological loop) structure of WM increased as a function of age within both language systems, (2) the structure of WM supported a domain general phonological storage component and a domain general executive system across both language systems, and (3) the visual-spatial WM system shared minimal variance with the executive system. Taken together, the findings support Baddeley's multicomponent model (e.g., Baddeley & Logie, 1999. The multiple-component model. In A. Miyake & P. Shah (Eds.), Models of working memory: Mechanisms of active maintenance and executive control (pp. 28-61). Cambridge: Cambridge University Press) as a good fit to the structure of WM in EL children's English and Spanish language system.

Working memory components that predict word problem solving: Is it merely a function of reading, calculation, and fluid intelligence?

The purpose of this study was to assess whether the differential effects of working memory (WM) components (the central executive, phonological loop, and visual-spatial sketchpad) on math word problem-solving accuracy in children (N = 413, ages 6-10) are completely mediated by reading, calculation, and fluid intelligence. The results indicated that all three WM components predicted word problem solving in the nonmediated model, but only the storage component of WM yielded a significant direct path to word problem-solving accuracy in the fully mediated model. Fluid intelligence was found to moderate the relationship between WM and word problem solving, whereas reading, calculation, and related skills (naming speed, domain-specific knowledge) completely mediated the influence of the executive system on problem-solving accuracy. Our results are consistent with findings suggesting that storage eliminates the predictive contribution of executive WM to various measures Colom, Rebollo, Abad, & Shih (Memory & Cognition, 34: 158-171, 2006). The findings suggest that the storage component of WM, rather than the executive component, has a direct path to higher-order processing in children.

Cognitive Profile of Individuals With Obsessive-Compulsive Tendencies

The aim of this study is to compare working memory capacity (WMC), short-term memory (STM), and attention mechanisms of executive function (including inhibition, shifting, and updating) between people with obsessive-compulsive tendencies (OCT) and controls without OCT. For this purpose, 164 undergraduate students (90 women and 74 men) were selected using the stratified random method, and they individually responded to the Maudsley Obsessional-Compulsive Inventory to measure OCT and to executive function tests including Forward Digit Span, Backward Digit Span, Stroop, Set Shifting, and Keep Track tasks. These tasks assessed STM, WMC, and inhibition of prepotent responses, mental set shifting, and information updating and monitoring, respectively. In this study, the cutoff point of the Maudsley Obsessional-Compulsive Inventory was considered to be 11. With regard to this cutoff point, 44 people in the group had OCT and 120 did not. The obtained results from the Pearson correlation coefficient and analysis of variance showed that students with OCT had significantly limited STM and WMC compared with those in the control group. Furthermore, their executive function abilities including shifting, updating, and inhibition were significantly weaker than those in the control group.

Short-Term Storage and Executive Working Memory Processing Predict Fluid Intelligence in Primary School Children

Working memory (WM) includes short-term storage and executive processing of information. WM has been suggested to be one of the key concepts to explain individual differences in fluid intelligence (Gf). However, only a few studies have investigated the association of the two different aspects of WM in relation to Gf. Furthermore, even fewer studies have included children. Therefore, we first investigated the inter-relations between the WM aspects (verbal and visual-spatial storage, verbal and visual-spatial executive processing). Second, we explored the relation between a general WM factor and Gf. Third, we analyzed the relations between the different WM aspects and Gf while we controlled for common variance among all WM tasks. Nine- to 11-year olds had to solve simple and complex span tasks. Correlations and structural equation modeling techniques were used to examine these relations. Most inter-relations among simple and complex spans were found to be substantial and positive. The general WM factor was related to Gf. Furthermore, after controlling for common variance among all WM tasks, individual differences in verbal storage, visual-spatial storage and verbal processing still uniquely related to Gf. Visual-spatial processing, however, was not related to Gf. Results are discussed in terms of underlying mechanisms.

The Structure of Working Memory in Young Children and Its Relation to Intelligence

This study investigated the structure of working memory in young school-age children by testing the fit of three competing theoretical models using a wide variety of tasks. The best fitting models were then used to assess the relationship between working memory and nonverbal measures of fluid reasoning (Gf) and visual processing (Gv) intelligence. One hundred sixty-eight English-speaking 7-9 year olds with typical development, from three states, participated. Results showed that Cowan's three-factor embedded processes model fit the data slightly better than Baddeley and Hitch's (1974) three-factor model (specified according to Baddeley, 1986) and decisively better than Baddeley's (2000) four-factor model that included an episodic buffer. The focus of attention factor in Cowan's model was a significant predictor of Gf and Gv. The results suggest that the focus of attention, rather than storage, drives the relationship between working memory, Gf, and Gv in young school-age children. Our results do not rule out the Baddeley and Hitch model, but they place constraints on both it and Cowan's model. A common attentional component is needed for feature binding, running digit span, and visual short-term memory tasks; phonological storage is separate, as is a component of central executive processing involved in task manipulation. The results contribute to a zeitgeist in which working memory models are coming together on common ground (cf. Cowan, Saults, & Blume, 2014; Hu, Allen, Baddeley, & Hitch, 2016).

Does Growth in the Executive System of Working Memory Underlie Growth in Literacy for Bilingual Children With and Without Reading Disabilities?

This cohort-sequential study explored the components of working memory (WM) that underlie second language (L2) reading growth in 450 children at risk and not at risk for reading disabilities (RD) whose first language is Spanish. English language learners designated as balanced and nonbalanced bilinguals with and without risk for RD in Grades 1, 2, and 3 at Wave 1 were administered a battery of cognitive (short-term memory, WM, naming speed, and inhibition), vocabulary, and reading measures in Spanish and English. These same measures were administered 1 and 2 years later. Two important findings occurred: First, growth in the WM executive component was significantly related to growth in English word identification and passage comprehension when competing measures (phonological processing, naming speed, inhibition, and fluid intelligence) were entered into the multilevel growth model. Second, children defined as at risk for RD in Wave 1 had lower intercepts than children not at risk at Wave 3 across several measures of cognition, language, and achievement. However, except on measures of the executive component of WM, no significant group differences in linear growth emerged. These findings suggest that growth in L2 reading was tied to growth in the executive system of WM.

Relations between key executive functions and aggression in childhood

The present study examined relationships between three key executive functions (working memory, inhibition, and mental set-shifting) and multiple types of aggression in a general population sample of 9-year-old children. One hundred and forty-eight children completed a battery of executive function tasks and were rated on aggression by their primary teachers. All executive function (EF) composites were related to a composite measure of aggression. Working memory (WM) was most consistently related to the different types of aggression (overt, relational, reactive, and proactive), whereas inhibition and mental set-shifting only were related to relational and reactive aggression, respectively. Specificity in relations (studied as independent contributions) was generally low with the exception of the relation between WM and relational aggression. Taken together, our results highlight the roles of WM and relational aggression in EF-aggression relations in middle childhood.