Abstract: Representation of the visual and spatial properties of our environment is a pivotal requirement of everyday cognition. We can mentally represent the visual form of objects. We can extract information from several of the senses as to the location of objects in relation to ourselves and to other objects nearby. For some of those objects we can reach out and manipulate them. We can also imagine ourselves manipulating objects in advance of doing so, or even when it would be impossible to do so physically. The problem posed to science is how these cognitive operations are accomplished, and proffered accounts lie in two essentially parallel research endeavours, working memory and imagery. Working memory is thought to pervade everyday cognition, to provide on-line processing and temporary storage, and to update, moment to moment, our representation of the current state of our environment and our interactions with that environment. There is now a strong case for the claims of working memory in the area of phonological and articulatory functions, all of which appear to contribute to everyday activities such as counting, arithmetic, vocabulary acquisition, and some aspects of reading and language comprehension. The claims for visual and spatial working memory functions are less convincing. Most notable has been the assumption that visual and spatial working memory are intimately involved in the generation, retention and manipulations of visual images. There has until recently been little hard evidence to justify that assumption, and the research on visual and spatial working memory has focused on a relatively restricted range of imagery tasks and phenomena. In a more or less independent development, the literature on visual imagery has now amassed a voluminous corpus of data and theory about a wide range of imagery phenomena. Despite this, few books on imagery refer to the concept of working memory in any detail, or specify the nature of the working memory system that might be involved in mental imagery. This essay follows a line of reconciliation and positive critiquing in exploring the possible overlap between mental imagery and working memory. Theoretical development in the book draws on data from both cognitive psychology and cognitive neuropsychology. The aim is to stimulate debate, to address directly a number of assumptions that hitherto have been implicit, and to assess the contribution of the concept of working memory to our understanding of these intriguing core aspects of human cognition.

Abstract: Working memory is the retention of a small amount of information in a readily accessible form. It facilitates planning, comprehension, reasoning, and problem-solving. I examine the historical roots and conceptual development of the concept and the theoretical and practical implications of current debates about working memory mechanisms. Then I explore the nature of cognitive developmental improvements in working memory, the role of working memory in learning, and some potential implications of working memory and its development for the education of children and adults. The use of working memory is quite ubiquitous in human thought, but the best way to improve education using what we know about working memory is still controversial. I hope to provide some directions for research and educational practice.

Abstract: This meta-analysis examined the effects of process-based executive-function and working memory training (49 articles, 61 independent samples) in older adults (> 60 years). The interventions resulted in significant effects on performance on the trained task and near-transfer tasks; significant results were obtained for the net pretest-to-posttest gain relative to active and passive control groups and for the net effect at posttest relative to active and passive control groups. Far-transfer effects were smaller than near-transfer effects but were significant for the net pretest-to-posttest gain relative to passive control groups and for the net gain at posttest relative to both active and passive control groups. We detected marginally significant differences in training-induced improvements between working memory and executive-function training, but no differences between the training-induced improvements observed in older adults and younger adults, between the benefits associated with adaptive and nonadaptive training, or between the effects in active and passive control conditions. Gains did not vary with total training time.

Abstract: Children’s behavioral self-regulation and executive function (EF; including attentional or cognitive flexibility, working memory, and inhibitory control) are strong predictors of academic achievement. The present study examined the psychometric properties of a measure of behavioral self-regulation called the Head-Toes-Knees-Shoulders (HTKS) by assessing construct validity, including relations to EF measures, and predictive validity to academic achievement growth between prekindergarten and kindergarten. In the fall and spring of prekindergarten and kindergarten, 208 children (51% enrolled in Head Start) were assessed on the HTKS, measures of cognitive flexibility, working memory (WM), and inhibitory control, and measures of emergent literacy, mathematics, and vocabulary. For construct validity, the HTKS was significantly related to cognitive flexibility, working memory, and inhibitory control in prekindergarten and kindergarten. For predictive validity in prekindergarten, a random effects model indicated that the HTKS significantly predicted growth in mathematics, whereas a cognitive flexibility task significantly predicted growth in mathematics and vocabulary. In kindergarten, the HTKS was the only measure to significantly predict growth in all academic outcomes. An alternative conservative analytical approach, a fixed effects analysis (FEA) model, also indicated that growth in both the HTKS and measures of EF significantly predicted growth in mathematics over four time points between prekindergarten and kindergarten. Results demonstrate that the HTKS involves cognitive flexibility, working memory, and inhibitory control, and is substantively implicated in early achievement, with the strongest relations found for growth in achievement during kindergarten and associations with emergent mathematics.

Abstract: Children’s behavioral self-regulation and executive function (EF; including attentional or cognitive flexibility, working memory, and inhibitory control) are strong predictors of academic achievement. The present study examined the psychometric properties of a measure of behavioral self-regulation called the Head-Toes-Knees-Shoulders (HTKS) by assessing construct validity, including relations to EF measures, and predictive validity to academic achievement growth between prekindergarten and kindergarten. In the fall and spring of prekindergarten and kindergarten, 208 children (51% enrolled in Head Start) were assessed on the HTKS, measures of cognitive flexibility, working memory (WM), and inhibitory control, and measures of emergent literacy, mathematics, and vocabulary. For construct validity, the HTKS was significantly related to cognitive flexibility, working memory, and inhibitory control in prekindergarten and kindergarten. For predictive validity in prekindergarten, a random effects model indicated that the HTKS significantly predicted growth in mathematics, whereas a cognitive flexibility task significantly predicted growth in mathematics and vocabulary. In kindergarten, the HTKS was the only measure to significantly predict growth in all academic outcomes. An alternative conservative analytical approach, a fixed effects analysis (FEA) model, also indicated that growth in both the HTKS and measures of EF significantly predicted growth in mathematics over four time points between prekindergarten and kindergarten. Results demonstrate that the HTKS involves cognitive flexibility, working memory, and inhibitory control, and is substantively implicated in early achievement, with the strongest relations found for growth in achievement during kindergarten and associations with emergent mathematics.

Abstract: The aim of this review is to illustrate the role of working memory and executive functions for scholastic achievement as an introduction to the question of whether and how working memory and executive control training may improve academic abilities. The review of current research showed limited but converging evidence for positive effects of process-based complex working-memory training on academic abilities, particularly in the domain of reading. These benefits occurred in children suffering from cognitive and academic deficits as well as in healthy students. Transfer of training to mathematical abilities seemed to be very limited and to depend on the training regime and the characteristics of the study sample. A core issue in training research is whether high- or low-achieving children benefit more from cognitive training. Individual differences in terms of training-related benefits suggested that process-based working memory and executive control training often induced compensation effects with larger benefits in low performing individuals. Finally, we discuss the effects of process-based training in relation to other types of interventions aimed at improving academic achievement.

Abstract: In the research reported here, we tested the hypothesis that sustained engagement in learning new skills that activated working memory, episodic memory, and reasoning over a period of 3 months would enhance cognitive function in older adults. In three conditions with high cognitive demands, participants learned to quilt, learned digital photography, or engaged in both activities for an average of 16.51 hr a week for 3 months. Results at posttest indicated that episodic memory was enhanced in these productive-engagement conditions relative to receptive-engagement conditions, in which participants either engaged in nonintellectual activities with a social group or performed low-demand cognitive tasks with no social contact. The findings suggest that sustained engagement in cognitively demanding, novel activities enhances memory function in older adulthood, but, somewhat surprisingly, we found limited cognitive benefits of sustained engagement in social activities.

Abstract: 1 Introduction 1.1 Historical Background 1.2 Association, Context, and Episodic Memory 1.3 Methods Used in Studying Memory 1.4 The Laws of Repetition and Recency 1.5 Cognitivism 1.6 Organization of the Book 2 Item Recognition 2.1 Strength Theory 2.2 Multiple Sources of Strength? 2.3 Major Findings Concerning Item Recognition 2.4 Sternberg's Procedure 2.5 Summary and Current Directions 2.6 Study Questions 3 Attribute Models 3.1 Attributes 3.2 A Multi-trace Distributed Memory Model 3.3 Similarity Effects 3.4 The Diffusion Model of Reaction Time 3.5 Context Revisited 3.6 Summary and Current Directions 3.7 List-strength Effect 3.8 A Unitrace Attribute Model 3.9 Study Questions 4 Associations and Cued Recall 4.1 Major Associative Tasks 4.2 Encoding and Repetition 4.3 Recency and List Length 4.4 Retrieval Errors 4.5 Retroactive Interference and Recovery 4.6 Proactive Interference 4.7 Context and Interference Theory 4.8 Similarity and Interference 4.9 Unlearning as Inhibition 4.10 Interference Theory: Concluding Remarks 4.11 Item and Associative Information 4.12 Summary and Current Directions 4.13 Study Questions 5 Models of Association 5.1 The Attribute-Similarity Framework 5.2 Neural Network Models 5.3 Summary and Current Directions 5.4 More on Linear Associators 5.5 Project: Cued Recall in a Hopfield Net 5.6 Study Questions 6 Free Recall and Memory Search 6.1 Serial-position Effects 6.2 Retrieval Dynamics 6.3 Semantic Clustering 6.4 Intrusions 6.5 Repetition Effects 6.6 Summary and Current Directions 6.7 Study Questions 7 Models of Free Recall 7.1 Dual-store Memory Search Models 7.2 Testing Dual-Store Models 7.3 Problems for Dual-store Models 7.4 Single-store retrieved-context models 7.5 Testing Retrieved Context Theory 7.6 Summary and Current Directions 7.7 Study Questions 8 Sequence Memory 8.1 Serial Recall and Memory Span 8.2 Serial-Position Effects 8.3 Modality and Suffix Effects: Evidence for a phonological STS? 8.4 Recall Errors 8.5 Associative Asymmetry 8.6 Grouping Effects 8.7 Summary and Current Directions 8.8 Study Questions 9 Theories of Sequence Memory 9.1 Associative Chaining 9.2 Positional Coding 9.3 Eight Critical Findings 9.4 Chaining vs. Positional Coding 9.5 Hierarchical Associative Theory 9.6 Summary and Current Directions 9.7 Study Questions References Author Index Index

Abstract: From vocabulary learning to imitating sequences of motor actions, the ability to plan, represent, and recall a novel sequence of items in the correct order is fundamental for many verbal and nonverbal higher level cognitive activities. Here we review phenomena of serial order documented across the verbal, visual, and spatial short-term memory domains and interpret them with reference to the principles of serial order and ancillary assumptions instantiated in contemporary computational theories of memory for serial order. We propose that functional similarities across domains buttress the notion that verbal, visual, and spatial sequences are planned and controlled by a competitive queuing (CQ) mechanism in which items are simultaneously active in parallel and the strongest item is chosen for output. Within the verbal short-term memory CQ system, evidence suggests that serial order is represented via a primacy gradient, position marking, response suppression, and cumulative matching. Evidence further indicates that output interference operates during recall and that item similarity effects manifest during both serial order encoding and retrieval. By contrast, the principles underlying the representation of serial order in the visual and spatial CQ systems are unclear, largely because the relevant studies have yet to be performed. In the spatial domain, there is some evidence for a primacy gradient and position marking, whereas in the visual domain there is no direct evidence for either of the principles of serial order. We conclude by proposing some directions for future research designed to bridge this and other theoretical gaps in the literature.

Abstract: Errors in short-term memory increase with the quantity of information stored, limiting the complexity of cognition and behavior. In visual memory, attempts to account for errors in terms of allocation of a limited pool of working memory resources have met with some success, but the biological basis for this cognitive architecture is unclear. An alternative perspective attributes recall errors to noise in tuned populations of neurons that encode stimulus features in spiking activity. I show that errors associated with decreasing signal strength in probabilistically spiking neurons reproduce the pattern of failures in human recall under increasing memory load. In particular, deviations from the normal distribution that are characteristic of working memory errors and have been attributed previously to guesses or variability in precision are shown to arise as a natural consequence of decoding populations of tuned neurons. Observers possess fine control over memory representations and prioritize accurate storage of behaviorally relevant information, at a cost to lower priority stimuli. I show that changing the input drive to neurons encoding a prioritized stimulus biases population activity in a manner that reproduces this empirical tradeoff in memory precision. In a task in which predictive cues indicate stimuli most probable for test, human observers use the cues in an optimal manner to maximize performance, within the constraints imposed by neural noise.

Abstract: Recent studies suggest that working memory training may benefit older adults; however, findings regarding training and transfer effects are mixed. The current study aimed to investigate the effects of a process-based training intervention in a diverse sample of older adults and explored possible moderators of training and transfer effects. For that purpose, 80 older adults (65-95 years) were assigned either to a training group that worked on visuospatial, verbal, and executive working memory tasks for 9 sessions over 3 weeks or to a control group. Performance on trained and transfer tasks was assessed in all participants before and after the training period, as well as at a 9-month follow-up. Analyses revealed significant training effects in all 3 training tasks in trained participants relative to controls, as well as near transfer to a verbal working memory task and far transfer to a fluid intelligence task. Encouragingly, all training effects and the transfer effect to verbal working memory were stable at the 9-month follow-up session. Further analyses revealed that training gains were predicted by baseline performance in training tasks and (to a lesser degree) by age. Gains in transfer tasks were predicted by age and by the amount of improvement in the trained tasks. These findings suggest that cognitive plasticity is preserved over a large range of old age and that even a rather short training regime can lead to (partly specific) training and transfer effects. However, baseline performance, age, and training gains moderate the amount of plasticity.

Abstract: Cognitive processes require working memory (WM) that involves a brief period of memory retention known as the delay period. Elevated delay-period activity in the medial prefrontal cortex (mPFC) has been observed, but its functional role in WM tasks remains unclear. We optogenetically suppressed or enhanced activity of pyramidal neurons in mouse mPFC during the delay period. Behavioral performance was impaired during the learning phase but not after the mice were well trained. Delay-period mPFC activity appeared to be more important in memory retention than in inhibitory control, decision-making, or motor selection. Furthermore, endogenous delay-period mPFC activity showed more prominent modulation that correlated with memory retention and behavioral performance. Thus, properly regulated mPFC delay-period activity is critical for information retention during learning of a WM task.

Abstract: Working memory skills have been shown to be enhanced by adaptive training in several randomised controlled trials. Here, two field trials were conducted in which teachers administered working memory training to their own pupils in school. Twenty-two children aged 8-9 years participated in Trial 1. In Trial 2, 50 children aged 9-11 years with the lowest academic performance completed training. They were matched with a group of 50 children who were not trained. Following training, children in Trial 1 improved significantly in both trained and untrained working memory tasks, with effect sizes comparable to those reported in research studies. Improvements on the trained tasks in Trial 2 were comparable, and training was associated with significantly greater progress at school across the academic year in maths and English. These findings indicate that teacher-administered training leads to generalised and robust gains in working memory and educationally significant gains in academic performance.

Abstract: Little is known about how specific components of working memory, namely, attentional processes including response inhibition, sustained attention, and cognitive inhibition, are related to reading decoding and comprehension. The current study evaluated the relations of reading comprehension, decoding, working memory, and attentional control in 1,134 adolescent students. Path analyses were used to assess the direct and indirect effects of working memory and aspects of attentional control on reading comprehension and decoding. There were significant direct effects of working memory, sustained attention, and cognitive inhibition on reading comprehension, but not decoding. There was a significant direct effect of working memory and response inhibition on decoding, but not comprehension. These results suggest that different aspects of attentional control are important for decoding versus comprehension.

Abstract: Two studies are reported in which younger and older monolingual and bilingual adults performed executive function tasks. In Study 1, 130 participants performed a Stroop task and bilinguals in both age groups showed less interference than monolinguals with a greater benefit for older adults. In Study 2, 108 participants performed a complex working memory task based on verbal or nonverbal stimuli. Bilinguals showed less interference than monolinguals, with a larger bilingual advantage in the older adult group and in the nonverbal task. Together, these results show that bilingual advantages in executive function depend on characteristics of the participants and features of the tasks, with larger effects found for older than younger adults and for complex tasks using nonverbal material.

Abstract: Working memory is the cognitive system in charge of the temporary maintenance of information in view of its on-going processing. Lying at the centre of cognition, it has become a key concept in psychological science. The book presents a critical review and synthesis of the working memory literature, and also presents an innovative new theory - the Time-Based Resource-Sharing (TBRS) model. Tracing back the evolution of the concept of working memory, from its introduction by Baddeley and Hitch in 1974 and the development of their modal model, Barrouillet and Camos explain how an alternative conception could have been developed from the very beginning, and why it is needed today. This alternative model takes into account the temporal dynamics of mental functioning. The book describes a new architecture for working memory, and provides a description of its functioning, its development, the sources of individual differences, and hints about neural substrates. The authors address central and debated questions about working memory, and also more general issues about cognitive architecture and functioning. Working Memory: Loss and Reconstruction will be essential reading for advanced students and researchers of the psychology of memory.

Abstract: Recent studies have revealed that the deployment of attention can be biased by the content of visual working memory (VWM), but that stored memories do not always interact with attention. This has led to a model which proposes a division within VWM between a single active template that interacts with perception and multiple accessory representations that do not. The present study was designed to study whether multiple memory representations are able to bias attention. Participants performed a visual search task while maintaining a variable number of colors in VWM. Consistent with earlier findings, we observed increased attentional capture by memory related distractors when VWM was filled with a single item. However, memory related capture was no longer present for memory loads beyond a single item. The absence of memory related capture at higher VWM loads was independent of individual VWM capacity, nor was it attributable to weaker encoding, forgetting, or reduced precision of memory representations. When analyses were limited to those trials in which participants had a relatively precise memory, there was still no sign of attentional guidance at higher loads. However, when observers were cued toward a specific memory item after encoding, interference with search returned. These results are consistent with a distinction within VWM between representations that interact with perception and those that do not, and show that only a single VWM representation at a time can interact with visual attention.

Abstract: Instrumental music training has been shown to enhance cognitive processing beyond general intelligence. We examined this assumption with regard to working memory performance in primary school-aged children (N = 50; 7–8 years of age) within a longitudinal study design. Half of the children participated in an extended music education program with 45 minutes of weekly instrumental music training, while the other half received extended natural science training. Each child completed a computerized test battery three times over a period of 18 months. The battery included seven subtests, which address the central executive, the phonological loop and the visuospatial sketchpad components of Baddeley’s working memory model. Socio-economic background and basic cognitive functions were assessed for each participant and used as covariates in subsequent analyses of variance (ANOVAs). Significant group by time interactions were found for phonological loop and central executive subtests, indicating a superior developmen...

Abstract: Based on a meta-analysis, Redick and Lindsey (2013) found that complex span and n-back tasks show an average correlation of r = 0.20, and concluded that “complex span and n-back tasks cannot be used interchangeably as working memory measures in research applications” (p. 1102). Here, we comment on this conclusion from a psychometric perspective. In addition to construct variance, performance on a test contains measurement error, task-specific variance, and paradigm-specific variance. Hence, low correlations among dissimilar indicators do not provide strong evidence for the existence, or absence, of a construct common to both indicators. One way to arrive at such evidence is to fit hierarchical latent factors that model task-specific, paradigm-specific, and construct variance. We report analyses for 101 younger and 103 older adults who worked on nine different working memory tasks. The data are consistent with a hierarchical model of working memory, according to which both complex span and n-back tasks are valid indicators of working memory. The working memory factor predicts 71% of the variance in a factor of reasoning among younger adults (83% for among older adults). When the working memory factor was restricted to any possible triplet of working memory tasks, the correlation between working memory and reasoning was inversely related to the average magnitude of the correlations among the indicators, indicating that more highly intercorrelated indicators may provide poorer coverage of the construct space. We stress the need to go beyond specific tasks and paradigms when studying higher-order cognitive constructs, such as working memory.

Abstract: According to cognitive load theory (CLT), the limitations of working memory (WM) in the learning of new tasks together with its ability to cooperate with an unlimited long-term memory (LTM) for familiar tasks enable human beings to deal effectively with complex problems and acquire highly complex knowledge and skills. With regard to WM, CLT has focused to a large extent on learning task characteristics, and to a lesser extent on learner characteristics to manage WM load and optimize learning through instructional design. With regard to LTM, explanations of human learning and cognition have mainly focused on domain-general skills, instead of domain-specific knowledge held in LTM. The contributions to this special issue provide a broader cognitive load view on the role of memory in learning and education by presenting the historical roots and conceptual development of the concept of WM, as well as the theoretical and practical implications of current debates about WM mechanisms (Cowan 2014), by presenting an updated model of cognitive load in which the physical learning environment is considered a distinct causal factor for WM load (Choi et al. 2014), by an experimental demonstration of the effects of persistent pain on the available WM resources for learning (Smith and Ayres 2014), and by using aspects of evolutionary educational psychology to argue for the primacy of domain-specific knowledge in human cognition (Tricot and Sweller 2014).

Abstract: We determined how various cognitive abilities, including several measures of a proposed domain-specific number sense, relate to mathematical competence in nearly 100 9-year-old children with normal reading skill. Results are consistent with an extended number processing network and suggest that important processing nodes of this network are phonological processing, verbal knowledge, visuo-spatial short-term and working memory, spatial ability and general executive functioning. The model was highly specific to predicting arithmetic performance. There were no strong relations between mathematical achievement and verbal short-term and working memory, sustained attention, response inhibition, finger knowledge and symbolic number comparison performance. Non-verbal intelligence measures were also non-significant predictors when added to our model. Number sense variables were non-significant predictors in the model and they were also non-significant predictors when entered into regression analysis with only a single visuo-spatial WM measure. Number sense variables were predicted by sustained attention. Results support a network theory of mathematical competence in primary school children and falsify the importance of a proposed modular ‘number sense’. We suggest an ‘executive memory function centric’ model of mathematical processing. Mapping a complex processing network requires that studies consider the complex predictor space of mathematics rather than just focusing on a single or a few explanatory factors.

Abstract: Recent studies have revealed that preschoolers' story comprehension is influenced by several basic as well as complex cognitive and linguistic processes. Among the abilities known to be relevant for young children's understanding of stories are the size of their vocabulary, their inference-making ability, and their working memory. In this study, we examine the role of other processes in explaining preschool children's story comprehension, in a sample of 257 Chilean kindergarten children from middle-income families. The processes we examine are comprehension monitoring, theory of mind, inhibition, and attention control. Mediation relations suggested by theory and previous research are examined between working memory and comprehension, through integrative processes, and between vocabulary breadth and comprehension, through vocabulary depth. We use two different measures of story comprehension to clarify the role that each predictor plays in different aspects of this complex skill. Results suggest that when the story comprehension measure requires construction of a coherent representation, vocabulary, monitoring, inferences, working memory, inhibitory skill, and attention, but not theory of mind, make a significant contribution. Effects of vocabulary breadth are mediated by vocabulary depth, and effects of working memory are partially mediated by monitoring and inferences. When story comprehension is measured through recall of isolated story elements, only working memory and vocabulary explain significant variance. Theoretical as well as practical implications are discussed.

Abstract: BACKGROUND: Until now, working memory training has not reached sufficient evidence as effective treatment for ADHD core symptoms in children with ADHD; for young children with ADHD, no studies are available. To this end, a triple-blind, randomized, placebo-controlled study was designed to assess the efficacy of Cogmed Working Memory Training (CWMT) in young children with ADHD. METHODS: Fifty-one children (5-7 years) with a DSM-IV-TR diagnosis of ADHD (without current psychotropic medication) were randomly assigned to the active (adaptive) or placebo (nonadaptive) training condition for 25 sessions during 5 weeks. The compliance criterion (>20 sessions) was met for 47 children. The primary outcome measure concerned the core behavioural symptoms of ADHD, measured with the ADHD Rating Scale IV (ADHD-RS). Secondary outcome measures were neurocognitive functioning, daily executive functioning, and global clinical functioning. The influence of the increase in difficulty level (Index-Improvement) for the treatment group was also analysed. Clinical trial registration information - 'Working Memory Training in Young ADHD Children'; www.clinicaltrials.gov; NCT00819611. RESULTS: A significant improvement in favour of the active condition was found on a verbal working memory task (p = .041; adapted Digit Span WISC-III, backward condition). However, it did not survive correction for multiple testing. No significant treatment effect on any of the primary or other secondary outcome measurements was found. The Index-Improvement significantly contributed to ADHD-RS and the Behavior Rating Inventory of Executive Function, both rated by the teacher, but revealed no significant group difference. CONCLUSIONS: This study failed to find robust evidence for benefits of CMWT over the placebo training on behavioural symptoms, neurocognitive, daily executive, and global clinical functioning in young children with ADHD.

Abstract: Working memory is typically defined as a system devoted to the simultaneous maintenance and processing of information. However, the interplay between these 2 functions is still a matter of debate in the literature, with views ranging from complete independence to complete dependence. The time-based resource-sharing model assumes that a central bottleneck constrains the 2 functions to alternate in such a way that maintenance activities postpone concurrent processing, with each additional piece of information to be maintained resulting in an additional postponement. Using different kinds of memoranda, we examined in a series of 7 experiments the effect of increasing memory load on different processing tasks. The results reveal that, insofar as attention is needed for maintenance, processing times linearly increase at a rate of about 50 ms per verbal or visuospatial memory item, suggesting a very fast refresh rate in working memory. Our results also show an asymmetry between verbal and spatial information, in that spatial information can solely rely on attention for its maintenance while verbal information can also rely on a domain-specific maintenance mechanism independent from attention. The implications for the functioning of working memory are discussed, with a specific focus on how information is maintained in working memory.

Abstract: Adaptive computerized training has been associated with significant enhancements in untrained working memory tasks, but the nature of the cognitive changes that underpin these improvements are not yet fully understood. Here, we investigate the possibility that training stimulates the use of memory-related strategies. In a randomized controlled trial, participants completed four tests of working memory before receiving adaptive working memory training, nonadaptive working memory training with low memory loads, or no training. Open-ended interviews about strategy use were conducted after the administration of untrained working memory tasks at two time points. Those in the adaptive and nonadaptive groups completed the assessments before (T1) and after (T2) 10 training sessions. The no-training group completed the same set of tasks at T1 and T2, without any training between assessment points. Adaptive training was associated with selective improvements in untrained tests of working memory, accompanied by a significant increase in the use of a grouping strategy for visuospatial short-term memory and verbal working memory tasks. These results indicate that training-related improvements in working memory may be mediated by implicit and spontaneous changes in the use of strategies to subsegment sequences of information into groups for recall when the tasks used at test overlap with those used during training.

Abstract: A key issue in cognitive psychology is the nature of limitations in working memory, the small amount of information temporarily held and used in various cognitive tasks. An important question is to what extent working memory storage depends on a mental faculty that is general across domains as opposed to domain-specific (e.g., Kane et al., 2004). A long tradition of dual-task methods lends itself to the examination of this question, and has been used for many years (e.g., Allen, Baddeley, & Hitch, 2006; Baddeley, 1986; Baddeley & Hitch, 1974; Cocchini, Logie, Della Sala, MacPherson, & Baddeley, 2002; Cowan & Morey, 2007; Fougnie & Marois, 2011; Morey & Cowan, 2004, 2005; Morey, Cowan, Morey, & Rouder, 2011; Saults & Cowan, 2007; Stevanovski & Jolicoeur, 2007). With this method, it has been fairly well established that there is some dual-task interference between very different tasks. To some degree, for example, the need to retain visual items interferes with concurrent storage of verbal items, and vice versa. Yet, this methodology has never lived up to its promise because, we contend, a thorough analysis of the problem has not been available. We examine the consequences of what we believe to be an improved methodology to ask how much of the working memory storage capacity is central, or capable of being allocated to different materials to be remembered according to task demands. This concept is separate from peripheral storage, which has different varieties, each of which can only be allocated to a single type of stimulus regardless of task instructions. In our case, storage capacity could be allocated to colored objects (sometimes differing also in shape) and/or words (spoken or, in one experiment, written). Assuming that there is a limited amount of central storage to be allocated freely, the number of colored objects remembered should be reduced when the participant must also remember words at the same time, and vice versa. A dual-task design, with memory for one or two different stimulus sets of different types required on a given trial, is required in order to estimate central and peripheral components of working memory. The reason is that memory for a single stimulus set theoretically can be based on multiple storage mechanisms, only some of which are shareable resources. With a single type of stimulus, multiple storage mechanisms cannot be separated. Here we apply a model in which memory for items in each modality is assumed to come from the sum of the contributions of central and peripheral components. The central component can be estimated as the portion of memory for stimuli of a certain type (e.g., colors) that have to be shared with stimuli of a second type (e.g., words) if that second type also is to be remembered. The peripheral component can be estimated as the portion of memory for stimuli of a certain type that does not have to be shared. Before the analysis of results into central and peripheral components can be accomplished, the number of items of each type retained in working memory must be estimated, as in past work (Cowan, 2001; Cowan, Blume, & Saults, 2013), separately for single- and dual-task conditions (cf. Saults & Cowan, 2007). Then certain subtractions between conditions can be carried out to estimate the central and peripheral components, as we explain below. Before explaining that, though, we discuss in more detail the theoretical implications of central and peripheral storage.