The development of working memory: exploring the complementarity of two models

The aim of the paper was to further explore the complementarity of the working memory models postulated by Pascual-Leone and Baddeley. Five-, six-, eight-, and nine-year-old children were assessed on two working memory tasks that have frequently been used within the respective streams of research: the Mr. Peanut task and the Corsi blocks task. Results indicated a developmental increase in spatial short-term memory for both tasks. Concurrent spatial suppression reduced performance on the two tasks in all four age groups. By contrast, articulatory suppression interfered with recall only on the Mr. Peanut task, and in only the older children. The two models were shown to make their own specific contribution to the interpretation of the data, attesting to their complementarity. Pascual-Leone's theory offered a clear explanation of the results concerning the central aspects of working memory, that is, the stepwise age-related increase in performance, whereas Baddeley's model provided a convincing account of the findings regarding the peripheral phonological and visuo-spatial components, that is, the effects of articulatory and spatial suppression.     

The development of visuo-spatial working memory

Children's performance on tests of visuo-spatial working memory improves with age, although relatively little is known about why this happens. One explanation concerns the development of the ability to recode visually presented information into phonological form. This process appears to be used from around 8 years of age and is a major contributor to tasks in which stimuli can be verbally labelled. However, evidence suggests that phonological recoding cannot account for all of the age-related change in performance on visuo-spatial working memory tasks. In this review, four other mechanisms (knowledge, processing strategies, processing speed, and attentional capacity) are considered in terms of their contribution to children's visuo-spatial working memory development.     

Computational models of working memory: putting long-term memory into context

Detailed computational modeling of human memory has typically been aimed at either short-term (working) memory or long-term memory in isolation. However, recent research highlights the importance of interactions between these systems for both item and order information. At the same time, computational models of both systems are beginning to converge onto a common framework in which items are associated with an evolving "context" signal and subsequently compete with one another at recall. We review some of these models, and discuss a common mechanism capable of modelling working memory and its interaction with long-term memory, focussing on memory for verbal sequences.     

The phonological-similarity effect differentiates between two working memory tasks

Working memory is a set of interactive cognitive processes that maintain information on–line and available for analysis. Part of the system is specialized for maintaining verbal information, a core component of which is thought to be a phonological store. On the basis of the study of patients with acquired brain lesions, this store has been localized to the supramarginal and angular gyri of the speech–dominant hemisphere, and some functional neuroimaging studies support this localization. However, other imaging studies localize the phonological store in a more dorsal region of the parietal lobe. To reconcile these findings, we examined the phonological–similarity effect in two different tasks. A phonological–similarity effect was observed only in the task that involved sequential presentation and explicit verbal rehearsal. We conclude that at least one possible source of the differences in brain activation between different working memory tasks may be differences in phonological processing.     

The role of working memory in the development of emotion comprehension

This study investigated the relationship between emotion comprehension, grammar comprehension, and working memory capacity in children between 5 and 11 years (n= 130), testing the hypothesis that working memory has a role in the development of emotion comprehension. We replicated the correlation between emotion comprehension and grammar comprehension, and found that working memory capacity correlates with both of these variables (also with age statistically controlled). The significant effect of age on emotion comprehension was eliminated when working memory capacity was co‐varied. In a regression analysis of emotion comprehension scores, when working memory capacity was entered as a predictor, no additional variance was significantly accounted for by grammar comprehension, gender, or age. A structural relations model, in which the paths from working memory capacity to emotion comprehension and from working memory capacity to grammar comprehension account fully for the correlation between grammar and emotion comprehension, fit the data well. However, working memory capacity was not equally related to all components of the Test of Emotion Comprehension (TEC) ( Pons & Harris, 2000 ), the relationship being significant only for some of them. In particular, working memory capacity has a decisive role in the transition from understanding external to mental aspects of emotions. It is concluded that the development of working memory has a considerable impact on the development of emotion comprehension.     

The reaction-time task-rule congruency effect is not affected by working memory load: further support for the activated long-term memory hypothesis

Previous studies claimed that task representation is carried out by the activated long-term memory portion of working memory (WM; Meiran and Kessler in J Exp Psychol Human Percept Perform 34:137–157, 2008). The present study provides a more direct support for this hypothesis. We used the reaction-time task-rule congruency effect (RT-TRCE) in a task-switching setup, and tested the effects of loading WM with irrelevant task rules on RT-TRCE. Experiment 1 manipulated WM load in a between-subject design. WM participants performed a color/shape task switching, while having 0, 1 or 3 numerical task rules as WM load. Experiment 2 used a similar load manipulation (1 or 3 rules to load WM) in a within-subject design. Experiment 3 extended these results by loading WM with perceptual tasks that were more similar to the shape/color tasks. The results show that RT-TRCE was not affected by WM load supporting the activated long-term memory hypothesis.     

Concurrent performance of two memory tasks: evidence for domain-specific working memory systems

Previous studies of dual-task coordination in working memory have shown a lack of dual-task interference when a verbal memory task is combined with concurrent perceptuomotor tracking. Two experiments are reported in which participants were required to perform pairwise combinations of (1) a verbal memory task, a visual memory task, and perceptuomotor tracking (Experiment 1), and (2) pairwise combinations of the two memory tasks and articulatory suppression (Experiment 2). Tracking resulted in no disruption of the verbal memory preload over and above the impact of a delay in recall and showed only minimal disruption of the retention of the visual memory load. Performing an ongoing verbal memory task had virtually no impact on retention of a visual memory preload or vice versa, indicating that performing two demanding memory tasks results in little mutual interference. Experiment 2 also showed minimal disruption when the two memory tasks were combined, although verbal memory (but not visual memory) was clearly disrupted by articulatory suppression interpolated between presentation and recall. These data suggest that a multiple-component working memory model provides a better account for performance in concurrent immediate memory tasks than do theories that assume a single processing and storage system or a limited-capacity attentional system coupled with activated memory traces.     

The development of visual working memory capacity during early childhood

The change detection task has been used in dozens of studies with adults to measure visual working memory capacity. Two studies have recently tested children in this task, suggesting a gradual increase in capacity from 5 years to adulthood. These results contrast with findings from an infant looking paradigm suggesting that capacity reaches adult-like levels within the first year. The current study adapted the change detection task for use with children younger than 5 years to test whether the standard version of the task was too difficult and may have underestimated children's capacity. Results showed that 3- and 4-year-olds could successfully complete this modified task and that capacity increased roughly linearly, from 2 or 3 items during this period to 3 or 4 items between 5 and 7 years. Furthermore, performance did not differ significantly between the modified version and a replication of the standard version with 5- and 7-year-olds. Thus, there is no evidence that previous research with the change detection task underestimated children's capacity. Further research is needed to understand how performance relates across the infant looking task and change detection to provide a more complete picture of visual working memory capacity over development.     

On the independence of short-term memory and working memory in cognitive development

We report some experiments that were concerned with the now familiar hypothesis that short-term memory and information processing draw upon a common pool of scarce resources. The results of two series of experiments were more consistent with the hypothesis that the resources that support short-term memory and information processing do not overlap and develop independently of each other. In Experiments 1–4, children's performance on four reasoning problems (class inclusion, conservation, probability judgment, and transitive inference) was found to be stochastically independent of their short-term memory for the critical background facts on these problems. Age changes in reasoning and short-term memory also proved to be independent. It was found in the second series of experiments that certain manipulations which affect the accuracy of children's reasoning do not affect short-term memory, and conversely. In Experiments 5–7, manipulations that affected the difficulty of information processing on class-inclusion and transitivity tasks did not affect short-term memory on these same tasks. In Experiments 8 and 9, manipulations that affected short-term retention of the background facts on conservation and probability-judgment tasks did not affect reasoning on these same tasks.     

Effect of articulatory suppression on task-switching performance: implications for models of working memory

In a series of experiments, we examine some effects of articulatory suppression in task switching. The results from Experiments 1a and 2a showed that switch costs in the articulatory suppression condition were larger than those in the control and tapping conditions when the switching cues were not provided. On the other hand, articulatory suppression did not have any effect on switch costs in Experiments 1b and 2b, where the switching cues were provided. In Experiment 3, using a computer-assisted experimentation, this pattern of data was replicated in a two-factor design with articulatory suppression and switching cues factors. The results indicate that a specific component in working memory, the phonological loop, might contribute to the performance in task switching, at least in situations where the external task cues were not available. The data reported here suggest that the phonological loop plays an important role in one of the executive control processes, and challenge the traditional idea that the slave systems are simply governed by the central executive in the working memory.     

The development of verbal and visual working memory processes: a latent variable approach

Working memory (WM) processing in children has been studied with different approaches, focusing on either the organizational structure of WM processing during development (factor analytic) or the influence of different task conditions on WM processing (experimental). The current study combined both approaches, aiming to distinguish verbal and visual processing in order to investigate WM development. We investigated recall performance under different task conditions in a sample of 5- to 13-year-olds, applying latent class regression analysis. In this analysis, we examined latent classes (subgroups) within the sample that differed in terms of processing type. The interpretations of the latent classes were validated internally using characteristics of the latent classes and externally using recall performance of words and figures. The results showed that children of different developmental stages used the same type of processing under the same conditions. However, due to developmental differences, their overall performances differed, showing groups of children who were successful in verbal or visual processing and groups of children who were not. This study shows and discusses the importance of disentangling the influence of task conditions from the influence of WM development when interpreting recall performance in children.     

Focused attention improves working memory: implications for flexible-resource and discrete-capacity models

Performance in working memory (WM) tasks depends on the capacity for storing objects and on the allocation of attention to these objects. Here, we explored how capacity models need to be augmented to account for the benefit of focusing attention on the target of recall. Participants encoded six colored disks (Experiment 1) or a set of one to eight colored disks (Experiment 2) and were cued to recall the color of a target on a color wheel. In the no-delay condition, the recall-cue was presented after a 1,000-ms retention interval, and participants could report the retrieved color immediately. In the delay condition, the recall-cue was presented at the same time as in the no-delay condition, but the opportunity to report the color was delayed. During this delay, participants could focus attention exclusively on the target. Responses deviated less from the target’s color in the delay than in the no-delay condition. Mixture modeling assigned this benefit to a reduction in guessing (Experiments 1 and 2) and transposition errors (Experiment 2). We tested several computational models implementing flexible or discrete capacity allocation, aiming to explain both the effect of set size, reflecting the limited capacity of WM, and the effect of delay, reflecting the role of attention to WM representations. Both models fit the data better when a spatially graded source of transposition error is added to its assumptions. The benefits of focusing attention could be explained by allocating to this object a higher proportion of the capacity to represent color.     

The personalisation method applied to a working memory task: Evidence of long-term working memory effects

Ericsson and Kintsch (1995) proposed that, in situations of expertise, individuals can overcome working memory limitations by using long-term working memory. It allows a greater capacity than working memory thanks to long-term memory encoding and retrieving. To test this characteristic, an adaptation of Daneman and Carpenter's (1980) reading span was used. To operationalise expertise, the personalisation method (Guida & Tardieu, 2005) was employed. In Experiment 1, a personalised group, which read reading span sentences that mentioned familiar locations, was compared to a nonpersonalised group, which read sentences with unfamiliar locations. In Experiment 2, a personalised group, which read reading span sentences with neutral locations, was encouraged to mentally personalise these locations by thinking about known locations. This group was compared to a nonpersonalised group, which was encouraged to think about unknown locations. The personalised groups were expected to store and retrieve information in long-term memory via long-term working memory more easily than the nonpersonalised groups, which had to count massively on working memory. The results showed that personalisation enhanced reading span and confirmed one implication of the long-term working memory theory: high- and low-reading-span differences could also be due to long-term memory retrieval. Finally, these results are interpreted in terms of interaction between working memory size and long-term memory knowledge, showing that participants with a lower reading span benefited more from high domain knowledge than participants with a higher reading span.     

Doxastic divergence and the problem of comparability. Pragmatism defended further

Situations where it is not obvious which of two incompatible actions we ought to perform are commonplace. As has frequently been noted in the contemporary literature, a similar issue seems to arise in the field of beliefs. Cases of doxastic divergence are cases in which the subject seems subject to two divergent oughts to believe: an epistemic and a practical ought to believe. This article supports the moderate pragmatist view according to which subjects ought, all things considered, to hold the practically right belief in, at least, some cases of doxastic divergence. Unlike many defences of pragmatism, this paper does not aim to overcome exclusivism (briefly, the view that only epistemic, but not practical, considerations have an influence on what a subject ought to believe). Another major challenge that pragmatism faces is to show that the epistemic and the practical ought to believe are comparable. This article makes a case for their comparability.     

The two sides of adversity: the effect of distant versus recent adversity on updating emotional content in working memory

Previous research suggests that adversity can have both adaptive and maladaptive effects, yet the emotional and working memory processes that contribute to more or less adaptive outcomes are unclear. The present study sought to investigate how updating emotional content differs in adolescents who have experienced past, recent, or no adversity. Participants who had experienced distant adversity (N?=?53), no adversity (N?=?58), or recent adversity only (N?=?20) performed an emotion n-back task with emotional facial expressions. Results revealed that the distant adversity group exhibited significantly faster reaction times (RTs) than the no adversity and recent adversity only groups. In contrast, the recent adversity only group exhibited significantly slower RTs and more errors than the distant adversity and no adversity groups. These results suggest an emotion and executive control pathway by which both the benefits and negative effects of adversity may be conferred. Results also highlight the importance of time in assessing the impact of adversity.     

The development of strategy use in elementary school children: working memory and individual differences

The current study tested the development of working memory involvement in children's arithmetic strategy selection and strategy efficiency. To this end, an experiment in which the dual-task method and the choice/no-choice method were combined was administered to 10- to 12-year-olds. Working memory was needed in retrieval, transformation, and counting strategies, but the ratio between available working memory resources and arithmetic task demands changed across development. More frequent retrieval use, more efficient memory retrieval, and more efficient counting processes reduced the working memory requirements. Strategy efficiency and strategy selection were also modified by individual differences such as processing speed, arithmetic skill, gender, and math anxiety. Short-term memory capacity, in contrast, was not related to children's strategy selection or strategy efficiency.     

The development of reflection-impulsivity: further data

The MFF20 was administered to 617 children aged 7–12yr. The resulting development trends for latency and errors suggest errors decrease to about age 10 yr then level off while a corresponding, though less dramatic, increase in latency was observed. These results were obtained without evidence of ceiling or floor effects or any evidence of a decrease in the relationship between latency and errors after age 10 yr, in contrast to those obtained by Salkind and Nelson (1980).