Developmental change in working memory strategies: from passive maintenance to active refreshing

Change in strategies is often mentioned as a source of memory development. However, though performance in working memory tasks steadily improves during childhood, theories differ in linking this development to strategy changes. Whereas some theories, such as the time-based resource-sharing model, invoke the age-related increase in use and efficiency of a strategy of active maintenance of memory traces, other theories, such as the task-switching model, do not mention strategy change. According to these models, either the cognitive load of the task or the duration of maintenance would account for recall performance. In the present study, we varied orthogonally these 2 factors. The results revealed that a different and unique factor affected recall performance at different ages: the duration of maintenance at age 6 and the cognitive load at age 7. As described by the task-switching model, younger children would not implement any maintenance activities while performing a concurrent task, their memory traces suffering from a time-based decay. This suggests that an increasing capacity of cognitive monitoring allows children to shift from this passive maintenance of memory traces to the active refreshing thereof at around the age of 7, reunifying the 2 current accounts of working memory development as 2 developmental stages.     

Modeling working memory: a computational implementation of the Time-Based Resource-Sharing theory

Working memory is a core concept in cognition, predicting about 50% of the variance in IQ and reasoning tasks. A popular test of working memory is the complex span task, in which encoding of memoranda alternates with processing of distractors. A recent model of complex span performance, the Time-Based-Resource-Sharing (TBRS) model of Barrouillet and colleagues, has seemingly accounted for several crucial findings, in particular the intricate trade-off between deterioration and restoration of memory in the complex span task. According to the TBRS, memory traces decay during processing of the distractors, and they are restored by attentional refreshing during brief pauses in between processing steps. However, to date, the theory has been formulated only at a verbal level, which renders it difficult to test and to be certain of its intuited predictions. We present a computational instantiation of the TBRS and show that it can handle most of the findings on which the verbal model was based. We also show that there are potential challenges to the model that await future resolution. This instantiated model, TBRS*, is the first comprehensive computational model of performance in the complex span paradigm. The Matlab model code is available as a supplementary material of this article.     

Rôle du contrôle exécutif dans le raisonnement par analogie chez l’enfant et le primate non humain

Analogical reasoning (AR) is a cornerstone of human cognition. Two main theories have historically been proposed to account for the ontogeny of AR. They propose that analogical skills are constrained by children's logical skills or limited knowledge of the relations to be considered. We adopt an alternative perspective in this review paper suggesting that AR abilities depend on the efficiency of executive control. We present convergent data collected in children and monkeys highlighting the role of three main executive functions: inhibitory control, cognitive flexibility and working memory updating. The analysis of children's reasoning suggests that the contribution of relational knowledge and executive control to analogical reasoning cannot be considered independently.     

Developmental fractionation of working memory and response inhibition during childhood

The lateral prefrontal cortex (LPFC) plays a major role in both working memory (WM) and response inhibition (RI), which are fundamental for various cognitive abilities. We explored the relationship between these LPFC functions during childhood development by examining the performance of two groups of children in visuospatial and auditory WM tasks and a go/no-go RI task. In the younger children (59 5- and 6-year-olds), performance on the visuospatial WM task correlated significantly with that in the auditory WM task. Furthermore, accuracy in these tasks correlated significantly with performance on the RI task, particularly in the no-go trials. In contrast, there were no significant correlations among those tasks in older children (92 8- and 9-year-olds). These results suggest that functional neural systems for visuospatial WM, auditory WM, and RI, especially those in the LPFC, become fractionated during childhood, thereby enabling more efficient processing of these critical cognitive functions.     

La représentation du but dans le contrôle exécutif chez l’enfant

Implementation of executive control over thought and action can only be guided by the goals that one desires to reach. Over the last decade, research has pointed out the central role of goal representation in executive control both during childhood and adulthood. The present paper reviews these findings, emphasizing the developmental dynamics observed during childhood. More precisely, it addresses the role of active goal maintenance in working memory, as it has been stressed by developmental and neurocognitive theoretical models. Beyond goal maintenance, the question as to how goal representations are formed in working memory has attracted research efforts lately. With age, children successfully process increasingly subtle environmental cues to infer the current task goal and when task goals need to be updated, as evidenced by the effect of cue transparency on switching and inhibition performance. In addition, the paper addresses how goal representation sheds light on the interplay between executive skills and conceptual knowledge, through the presentation of research in such domains as analogical reasoning, categorical flexibility, and class inclusion quantification. Taken together, these lines of research show that executive control development does not rely exclusively on a growing ability to implement appropriate actions, but it also depends largely on increasingly efficient identification of what such actions should be.     

Developmental change in the relation between executive functions and symptoms of ADHD and co‐occurring behaviour problems

In a sample of 92 children aged 6–13 years this study investigates the normal developmental change in the relation between executive functioning (EF) and the core behavioural symptoms associated with attention deficit hyperactivity disorder (ADHD) (hyperactivity/impulsivity and inattention) as well as symptoms often co‐occurring with childhood hyperactivity (conduct‐ and internalizing problems). EF was assessed by using multiple tests grouped through prior factor analysis, resulting in cognitive measures relating to disinhibition, speed/arousal, verbal working memory, non‐verbal working memory, and fluency. The results showed that although disinhibition was positively related to hyperactivity/impulsivity and inattention mainly for the youngest age group, there were no significant age effects for these relations. Instead, age effects were found for the relations between speed/arousal and inattention as well as for the relations between verbal working memory/fluency and inattention. In the oldest age group poor performance on these cognitive measures was associated with high ratings of inattention. For the total sample a relation was obtained between disinhibition and hyperactivity/impulsivity as well as between both working memory measures and internalizing problems. In conclusion, the results from this study suggest that poor inhibition is most clearly associated with ADHD symptoms for younger children, whereas poor functioning with regard to later developing and more complex executive functions such as working memory and fluency is associated with ADHD symptoms for older children. Copyright © 2006 John Wiley & Sons, Ltd.     

Seven-year-olds allocate attention like adults unless working memory is overloaded

Previous studies have indicated that visual working memory performance increases with age in childhood, but it is not clear why. One main hypothesis has been that younger children are less efficient in their attention; specifically, they are less able to exclude irrelevant items from working memory to make room for relevant items. We examined this hypothesis by measuring visual working memory capacity under a continuum of five attention conditions. A recognition advantage was found for items to be attended as opposed to ignored. The size of this attention-related effect was adult-like in young children with small arrays, suggesting that their attention processes are efficient even though their working memory capacity is smaller than that of older children and adults. With a larger working memory load, this efficiency in young children was compromised. The efficiency of attention cannot be the sole explanation for the capacity difference.     

Developmental differences in working memory: Where do they come from?

Several models assume that working memory development depends on age-related increases in efficiency and speed of processing. However, age-related increases in the efficiency of the mechanisms that counteract forgetting and restore memory traces may also be important. This hypothesis was tested in three experiments by manipulating both the processing duration within a working memory task and the time available to restore memory traces. Third- and sixth-grade children performed a complex span task in which they maintained series of letters while adding numbers to series of digits. When we equated processing and restoration times between ages, the developmental difference in working memory span was reduced but remained significant. However, this residual difference was eliminated when the time available to reactivate memory traces was tailored to the processing speed of each age group. This indicates that children employ active mechanisms for maintenance and restoration of memory traces that develop with age.     

Le rôle de la mémoire de travail dans la production écrite de textes

Integration of capacity (Just and Carpenter, 1992) and componentiel (Baddeley, 1986) conceptions of working memory in models of text composition (Hayes, 1996 ; Kellogg, 1996 ; McCutchen, 1996) has allowed studying several facets of the role of working memory in writing acquisition and in expert management of the writing processes. This article presents these two conceptions and examines their respective contribution in the field of writing research from two perspectives: The demands of the writing processes (in terms of processing and transient storage) and the influence of working memory capacity on the control of production. The conclusion underlines the importance of investigating the on-line management of text production, the role of the visuo-spatial sketchpad, and to link strategies for allocating the working memory resources with text quality.     

Capacité de mémoire de travail et traitement du pronom chez l’enfant

The aim of this study was to explore the relationship between working memory capacity (WMC) and reading comprehension in children by testing the processing of pronouns. Two groups of nine- to ten-year-old children classified as high span and low span were administered a pronoun processing task. In this task, the computation of the antecedent referent for pronouns was varied by manipulating the distance between the pronoun and its antecedent and the availability of a gender cue. The results showed that compared to high-span children, low-span children experienced more difficulties in computing a pronoun's referent. High-span children spent longer reading sentences containing anaphoric pronouns when pronouns could not be resolved on the basis of the gender alone, suggesting that the pronouns were resolved as they were read. Low-span children tended to delay resolution until it was required by the task. In the question-answering times, low-span children were more adversely affected by distance than high-span children. Altogether these findings support the view that working memory capacity constrains resolution of anaphoric pronouns in children.     

The effects of socioeconomic status on working memory in childhood are partially mediated by intersensory processing of audiovisual events in infancy

Socioeconomic status (SES) is a well-established predictor of individual differences in childhood language and cognitive functioning, including executive functions such as working memory. In infancy, intersensory processing—selectively attending to properties of events that are redundantly specified across the senses at the expense of non-redundant, irrelevant properties—also predicts language development. Our recent research demonstrates that individual differences in intersensory processing in infancy predict a variety of language outcomes in childhood, even after controlling for SES. However, relations among intersensory processing and cognitive outcomes such as working memory have not yet been investigated. Thus, the present study examines relations between intersensory processing in infancy and working memory in early childhood, and the role of SES in this relation. Children (N = 101) received the Multisensory Attention Assessment Protocol at 12-months to assess intersensory processing (face-voice and object-sound matching) and received the WPPSI at 36-months to assess working memory. SES was indexed by maternal education, paternal education, and income. A variety of novel findings emerged. 1) Individual differences in intersensory processing at 12-months predicted working memory at 36-months of age even after controlling for SES. 2) Individual differences in SES predicted intersensory processing at 12-months of age. 3) The well-established relation between SES and working memory was partially mediated by intersensory processing. Children from families of higher-SES have better intersensory processing skills at 12-months and this combination of factors predicts greater working memory two years later at 36-months. Together these findings reveal the role of intersensory processing in cognitive functioning.     

Fonctions exécutives,vieillissement cognitif et variations stratégiques

Aging is characterized by a decrease of cognitive performance in most of cognitive domains. One of the most fundamental issues is then to know what are the underlying mechanisms of these age-related changes in human cognition. Recent research suggests that in addition to speed of processing and working memory capacities, age-related impairment in executive functioning plays an important role in the cognitive decline associated to aging. Above and beyond performance, current research shows that the mediating role of executive function in age-related changes in cognitive performance occurs via changes in strategies variations (i.e., repertoire, distribution, execution, and selection of the strategies used to accomplish a cognitive task). In this article, we illustrate both strategic variations and underlying executive control mechanisms in two important cognitive domains : episodic memory and problem solving.     

L'élaboration du contenu du texte : de la mémoire à long terme à l'environnement de la tâche

This paper aims at analysing different theories about text content elaboration. In the literature, the conceptual processing is considered through its relationships with long-term memory and the retrieving process during planning. It has been shown that knowledge availability and organisation influenced the writing progress. The task environment, which contains both the text that is currently written and documentary sources, equally plays an important role during text content elaboration. In this framework, the question concerning the double influence of knowledge from long-term memory and information from environment on the dynamics of writing processing is raised. The working memory, the activation theories and the analysis of the writer's eye movements are studied to answer this crucial question.     

Sensorimotor and working memory systems jointly support development of perceptual rhythm processing

We studied the role of sensorimotor and working memory systems in supporting development of perceptual rhythm processing with 119 participants aged 7–12 years. Children were assessed for their abilities in sensorimotor synchronization (SMS; beat tapping), auditory working memory (AWM; digit span), and rhythm discrimination (RD; same/different judgment on a pair of musical rhythm sequences). Multiple regression analysis revealed that children's RD performance was independently predicted by higher beat tapping consistency and greater digit span score, with all other demographic variables (age, sex, socioeconomic status, music training) controlled. The association between RD and SMS was more robust in the slower tempos (60 and 100 beats-per-minute (BPM)) than faster ones (120 and 180 BPM). Critically, the relation of SMS to RD was moderated by age in that RD performance was predicted by beat tapping consistency in younger children (age: 7–9 years), but not in older children (age: 10–12 years). AWM was the only predictor of RD in older children. Together, the current findings demonstrate that the sensorimotor and working memory systems jointly support RD processing during middle-to-late childhood and that the degree of association between the two systems and perceptual rhythm processing is shifted before entering into early adolescence.     

Working memory training improvements and gains in non-trained cognitive tasks in young and older adults

Previous studies on working memory training have indicated that transfer to non-trained tasks of other cognitive domains may be possible. The aim of this study is to compare working memory training and transfer effects between younger and older adults (n = 60). A novel approach to adaptive n-back training (12 sessions) was implemented by varying the working memory load and the presentation speed. All participants completed a neuropsychological battery of tests before and after the training. On average, younger training participants achieved difficulty level 12 after training, while older training participants only reached difficulty level 5. In younger participants, transfer to Verbal Fluency and Digit Symbol Substitution test was found. In older participants, we observed a transfer to Digit Span Forward, CERAD Delayed Recall, and Digit Symbol Substitution test. Results suggest that working memory training may be a beneficial intervention for maintaining and improving cognitive functioning in old age.     

Neurocognitive ageing of storage and executive processes

Converging behavioural and neuropsychological evidence indicates that age-related changes in working memory contribute substantially to cognitive decline in older adults. Important questions remain about the relationship between working memory storage and executive components and how they are affected by the normal ageing process. In several studies using positron emission tomography (PET), we find age differences in the patterns of frontal activation during working memory tasks. We find that separable age differences can be linked to different cognitive operations underlying short-term information storage, and interference resolution. Some operations are associated with age-related increases in activation, with older adults displaying bilateral activations and recruiting prefrontal areas more than younger adults. Other operations are associated with age-related decreases in activation. We consider the implications of these results for understanding the working memory system and potential compensatory processes in the ageing brain.     

Very long-term memories of a salient preschool event

Children who attended either a younger (mean age = 3frac12;years) or an older (mean age = 4frac12; years)preschool classroom were interviewed twice about an emergency school evacuation in response to a fire alarm. All children were able to answer some memory questions 2 weeks after the evacuation occurred, but the memory narratives produced by older preschool children showed a more refined knowledge of the temporal and causal sequence of events. Seven years later, memory of the fire alarm was reassessed. Only those preadolescents who had been in the older preschool group at the time of the alarm showed convincing evidence of long-term memory. The offset of childhood amnesia appears to be influenced by developmental changes in cognitive processing.     

Binding and strategic selection in working memory: a lifespan dissociation

Working memory (WM) shows a gradual increase during childhood, followed by accelerating decline from adulthood to old age. To examine these lifespan differences more closely, we asked 34 children (10-12 years), 40 younger adults (20-25 years), and 39 older adults (70-75 years) to perform a color change detection task. Load levels and encoding durations were varied for displays including targets only (Experiment 1) or targets plus distracters (Experiment 2, investigating a subsample of Experiment 1). WM performance was lower in older adults and children than in younger adults. Longer presentation times were associated with better performance in all age groups, presumably reflecting increasing effects of strategic selection mechanisms on WM performance. Children outperformed older adults when encoding times were short, and distracter effects were larger in children and older adults than in younger adults. We conclude that strategic selection in WM develops more slowly during childhood than basic binding operations, presumably reflecting the delay in maturation of frontal versus medio-temporal brain networks. In old age, both sets of mechanisms decline, reflecting senescent change in both networks. We discuss similarities to episodic memory development and address open questions for future research.     

Specifying Links Between Executive Functioning and Theory of Mind during Middle Childhood: Cognitive Flexibility Predicts Social Understanding

The purpose of this study was to specify the development of and links between executive functioning and theory of mind during middle childhood. One hundred four 7- to 12-year-old children completed a battery of age-appropriate tasks measuring working memory, inhibition, flexibility, theory of mind, and vocabulary. As expected, spatial working memory and flexibility increased significantly with age, especially after 7 years. Moreover, flexibility predicted social understanding over and above the effects of age, vocabulary, working memory, and inhibition. Together, these findings highlight improvements in and tight relations between complex aspects of executive functioning and theory of mind during middle childhood and suggest that executive functioning and theory of mind are linked beyond their emergence in early childhood.     

Relationships between working memory and intelligence from a developmental perspective: Convergent evidence from a neo-Piagetian and a psychometric approach

The objective of this paper, in line with the other papers of this special issue, is to show the potentialities of combining intelligence research and cognitive psychology. The development of intelligence is here addressed from two usually separate perspectives, a psychometric one, and a neo-Piagetian one. Two studies are presented. In Experiment 1, children aged 6, 7, 9, and 11 years (N = 100) were administered two working memory tasks and three Piagetian tasks. In Experiment 2, children aged 8–12 years (N = 207), young adults aged 20–35 (N = 160), and older adults aged 60–88 years (N = 135) were administered working memory and processing speed tasks, as well as the Raven Standard Matrices task. Regression and commonality analyses were run to analyse the age-related variance in the Piagetian tasks (Study 1), and in the Raven task (Study 2). In both experiments, working memory accounted for a large part of the age differences observed, but more so in Study 1 (Piagetian tasks) than in Study 2 (Raven task). It is concluded that working memory mediates the effect of age on fluid intelligence during childhood and during adulthood.