Abstract: The study's goal was to identify the beginning of 1st grade quantitative competencies that predict mathematics achievement start point and growth through 5th grade. Measures of number, counting, and arithmetic competencies were administered in early 1st grade and used to predict mathematics achievement through 5th (n = 177), while controlling for intelligence, working memory, and processing speed. Multilevel models revealed intelligence and processing speed, and the central executive component of working memory predicted achievement or achievement growth in mathematics and, as a contrast domain, word reading. The phonological loop was uniquely predictive of word reading and the visuospatial sketch pad of mathematics. Early fluency in processing and manipulating numerical set size and Arabic numerals, accurate use of sophisticated counting procedures for solving addition problems, and accuracy in making placements on a mathematical number line were uniquely predictive of mathematics achievement. Use of memory-based processes to solve addition problems predicted mathematics and reading achievement but in different ways. The results identify the early quantitative competencies that uniquely contribute to mathematics learning.

Abstract: Tulving (2000) provided a concise, general definition of memory as the “neurocognitive capacity to encode, store, and retrieve information,” and suggested the possibility that there are many separate memory systems that fit this definition. Indeed, one of the primary aims of modern memory research has been to identify these different memory systems (Schacter & Tulving, 1994). This approach has lead to an extensive taxonomy of memory systems which are characterized by differences in timing, storage capacity, conscious access, active maintenance, and mechanisms of operation. Early on, William James (1890) proposed the distinction between primary memory – the information held in the ‘conscious present’ – and secondary memory, which consists of information that is acquired, stored outside of conscious awareness, and then later remembered. This distinction maps directly onto the modern distinction between short-term memory (henceforth working memory) and long-term memory (Atkinson & Shiffrin, 1968; Scoville & Milner, 1957; Waugh & Norman, 1965). The most salient difference between these systems is their capacity: the active, working memory system has an extremely limited capacity of only a few items (Cowan, 2001; Cowan, 2005; Miller, 1956), whereas the passive, long-term memory system can store thousands of items (Brady et al. 2008; Standing, 1973; Voss, 2009) with remarkable fidelity (Brady et al., 2008; Konkle et al., 2010a). The emphasis on memory systems and memory processes has been quite valuable in shaping cognitive and neural models of memory. In general, this approach aims to characterize memory systems in a way that generalizes over representational content (Schacter & Tulving, 1994). For example, working memory is characterized by a severely limited capacity regardless of whether items are remembered visually or verbally (e.g., Baddeley, 1986), and long-term memory has a very high capacity whether the items remembered are pictures (e.g., Standing, 1973), words (e.g., Shepard, 1967), or associations (e.g., Voss, 2009). However, generalization across content leaves many basic questions unanswered regarding the nature of stored representations: What is the structure and format of those representations? Research on visual perception takes the opposite approach, attempting to determine what is being represented, and to generalize across processes. For example, early stages of visual representation consist of orientation and spatial frequency features. Vision research has measured the properties of these features, such as their tuning curves and sensitivity (e.g., Blakemore & Campbell, 1969), and shown that these tuning properties are constant across several domains of processing (e.g., from simple detection to visual search). Thus, the intersection between memory and vision is a particularly interesting domain of research because it concerns both the processes of memory and the nature of the stored representations (Luck & Hollingworth, 2008). Recent research within the vision science community at this intersection between memory and vision has been quite fruitful. For example, working memory research has shown an important item/resolution tradeoff: as the number of items remembered increases, the precision with which each one is remembered decreases, possibly with an upper bound on the number of items that may be stored (Alvarez & Cavanagh, 2004; Zhang & Luck, 2008), or possibly without an upper bound (Bays, Catalao & Husain, 2009; Wilken & Ma, 2004). In long-term memory, it is possible to store thousands of detailed object representations (Brady et al. 2008; Konkle et al., 2010b) but only for meaningful items that connect with stored knowledge (Konkle et al., 2010b; Wiseman and Neisser, 1974). Here we review recent research in the domains of visual working memory and visual long-term memory, focusing on how models of these memory systems are altered and refined by taking the contents of memory into account.

Abstract: Influential models of visual working memory treat each item to be stored as an independent unit and assume that there are no interactions between items. However, real-world displays have structure that provides higher-order constraints on the items to be remembered. Even in the case of a display of simple colored circles, observers can compute statistics, such as mean circle size, to obtain an overall summary of the display. We examined the influence of such an ensemble statistic on visual working memory. We report evidence that the remembered size of each individual item in a display is biased toward the mean size of the set of items in the same color and the mean size of all items in the display. This suggests that visual working memory is constructive, encoding displays at multiple levels of abstraction and integrating across these levels, rather than maintaining a veridical representation of each item independently.

Abstract: The present study examined the effects of a 9-month randomized control physical activity intervention aimed at improving cardiorespiratory fitness on changes in working memory performance in preadolescent children relative to a waitlist control group. Participants performed a modified Sternberg task, which manipulated working memory demands based on encoding set sizes, while task performance and the contingent negative variation (CNV) event-related brain potential were measured. Analyses revealed that the physical activity intervention led to increases in cardiorespiratory fitness and improved Sternberg task performance. Further, the beneficial effects of the physical activity intervention were greater for a task condition requiring greater working memory demands. In addition, the intervention group exhibited larger initial CNV at the frontal electrode site, relative to the waitlist group at post-test; an effect not observed during the pre-test. These results indicate that increases in cardiorespiratory fitness are associated with improvements in the cognitive control of working memory in preadolescent children.

Abstract: This article reviews research on working memory (WM) and its use in second language (L2) acquisition research. Recent developments in the model and issues surrounding the operationalization of the construct itself are presented, followed by a discussion of various methods of measuring WM. These methods include word and digit span tasks, reading, listening and speaking span tasks. We next outline the role proposed for WM in explaining individual differences in L2 learning processes and outcomes, including sentence processing, reading, speaking, lexical development and general proficiency. Key findings are that WM is not a unitary construct and that its role varies depending on the age of the L2 learners, the task and the linguistic domain. Some tests of WM may in fact be tests of differences in ability to attend to aspects of the L2. Future research will focus on matching tests of WM more closely with linguistic tasks and using more standardized, replicable measures of WM in new areas including writing in non-alphabetic scripts, instructional interventions and cognitive neuropsychology.

Abstract: Working memory refers to keeping track of ongoing mental processes and temporary memory. One hypothesis is that this form of memory consists of multiple domain-specific components. Over four decades, experiments testing this hypothesis have yielded insight into cognitive changes from childhood to old age, selective cognitive impairments following brain damage, and on-line cognition in healthy adults. Advances in the understanding of working memory also have arisen from the discovery of associations between individual differences in working-memory capacity and a broad range of cognitive measures. These latter advances have often been interpreted as supporting the alternative hypothesis that working memory consists of a single, limited-capacity domain-general system for control of attention. Here I outline recent developments in the multiple-component perspective that address challenges derived from the attention-based hypothesis and from multivariate studies of individual differences. I argue that the mult...

Abstract: Although the measurement of working memory capacity is crucial to understanding working memory and its interaction with other cognitive faculties, there are inconsistencies in the literature on how to measure capacity. We address the measurement in the change detection paradigm, popularized by Luck and Vogel (Nature, 390, 279–281, 1997). Two measures for this task—from Pashler (Perception & Psychophysics, 44, 369–378, 1988) and Cowan (The Behavioral and Brain Sciences, 24, 87–114, 2001), respectively—have been used interchangeably, even though they may yield qualitatively different conclusions. We show that the choice between these two measures is not arbitrary. Although they are motivated by the same underlying discrete-slots working memory model, each is applicable only to a specific task; the two are never interchangeable. In the course of deriving these measures, we discuss subtle but consequential flaws in the underlying discrete-slots model. These flaws motivate revision in the modal model and capacity measures.

Abstract: We measured digit span (DS) in two experiments that used computerized presentation of randomized auditory digits with performance-adapted list length adjustment. A new mean span (MS) metric of DS was developed that showed reduced variance, improved test-retest reliability, and higher correlations with the results of other neuropsychological test results when compared to traditional DS measures. The MS metric also enhanced the sensitivity of forward versus backward span comparisons, enabled the development of normative performance criteria with subdigit precision, and elucidated changes in DS performance with age and education level. Computerized stimulus delivery and improved scoring metrics significantly enhance the precision of DS assessments of short-term verbal memory.

Abstract: Recent neurophysiological and imaging studies have investigated how neural representations underlying working memory (WM) are dynamically updated for objects presented sequentially. Although such studies implicate information encoded in oscillatory activity across distributed brain networks, interpretation of findings depends crucially on the underlying conceptual model of how memory resources are distributed. Here, we quantify the fidelity of human memory for sequences of colored stimuli of different orientation. The precision with which each orientation was recalled declined with increases in total memory load, but also depended on when in the sequence it appeared. When one item was prioritized, its recall was enhanced, but with corresponding decrements in precision for other objects. Comparison with the same number of items presented simultaneously revealed an additional performance cost for sequential display that could not be explained by temporal decay. Memory precision was lower for sequential compared with simultaneous presentation, even when each item in the sequence was presented at a different location. Importantly, stochastic modeling established this cost for sequential display was due to misbinding object features (color and orientation). These results support the view that WM resources can be dynamically and flexibly updated as new items have to be stored, but redistribution of resources with the addition of new items is associated with misbinding object features, providing important constraints and a framework for interpreting neural data.

Abstract: Fluid intelligence (Gf) predicts performance on a wide range of cognitive activities, and children with impaired Gf often experience academic difficulties. Previous attempts to improve Gf have been hampered by poor control conditions and single outcome measures. It is thus still an open question whether Gf can be improved by training. This study included 4-year-old children (N = 101) who performed computerized training (15 min/day for 25 days) of either non-verbal reasoning, working memory, a combination of both, or a placebo version of the combined training. Compared to the placebo group, the non-verbal reasoning training group improved significantly on Gf when analysed as a latent variable of several reasoning tasks. Smaller gains on problem solving tests were seen in the combination training group. The group training working memory improved on measures of working memory, but not on problem solving tests. This study shows that it is possible to improve Gf with training, which could have implications for early interventions in children.

Abstract: In the past years, an increasing number of studies have investigated executive functions as predictors of individual differences in mathematical abilities. The present longitudinal study was designed to investigate whether the executive functions shifting, inhibition, and working memory differ between low achieving and typically achieving children and whether these executive functions can be seen as precursors to math learning disabilities in children. Furthermore, the predictive value of working memory ability compared to preparatory mathematical abilities was examined. Two classifications were made based on (persistent) mathematical ability in first and second grade. Repeated measures analyses and discriminant analyses were used to investigate which functions predicted group membership best. Group differences in performance were found on one inhibition and three working memory tasks. The working memory tasks predicted math learning disabilities, even over and above the predictive value of preparatory mathematical abilities.

Abstract: Working memory is usually defined in cognitive psychology as a system devoted to the simultaneous processing and maintenance of information. However, although many models of working memory have been put forward during the last decades, they often leave underspecified the dynamic interplay between processing and storage. Moreover, the account of their interaction proposed by the most popular A. D. Baddeley and G. Hitch's (1974) multiple-component model is contradicted by facts, leaving unresolved one of the main issues of cognitive functioning. In this article, the author derive from the time-based resource-sharing model of working memory a mathematical function relating the cognitive load involved by concurrent processing to the amount of information that can be simultaneously maintained active in working memory. A meta-analysis from several experiments testing the effects of processing on storage corroborates the parameters of the predicted function, suggesting that it properly reflects the law relating the 2 functions of working memory.

Abstract: This study examines the relationship between working memory and reading achievement in 57 Swedish primary-school children with special needs. First, it was examined whether children’s working memory could be enhanced by a cognitive training program, and how the training outcomes would relate to their reading development. Next, it was explored how differential aspects of working memory are related to children’s reading outcomes. The working memory training yielded effects, and these effects appeared beneficial to children’s reading comprehension development. Working memory measures were found to be related with children’s word reading and reading comprehension. The results show that working memory can be seen as a crucial factor in the reading development of literacy among children with special needs, and that interventions to improve working memory may help children becoming more proficient in reading comprehension.

Abstract: There has been a great deal of interest, both privately and commercially, in using working memory training exercises to improve general cognitive function. However, many of the laboratory findings for older adults, a group in which this training is of utmost interest, are discouraging due to the lack of transfer to other tasks and skills. Importantly, improvements in everyday functioning remain largely unexamined in relation to WM training. We trained working memory in older adults using a task that encourages transfer in young adults (Chein & Morrison, 2010). We tested transfer to measures of working memory (e.g., Reading Span), everyday cognitive functioning [the Test of Everyday Attention (TEA) and the California Verbal Learning Test (CVLT)], and other tasks of interest. Relative to controls, trained participants showed transfer improvements in Reading Span and the number of repetitions on the CVLT. Training group participants were also significantly more likely to self-report improvements in everyday attention. Our findings support the use of ecological tasks as a measure of transfer in an older adult population.

Abstract: Social problems are a prevalent feature of ADHD and reflect a major source of functional impairment for these children. The current study examined the impact of working memory deficits on parent- and teacher-reported social problems in a sample of children with ADHD and typically developing boys (N = 39). Bootstrapped, bias-corrected mediation analyses revealed that the impact of working memory deficits on social problems is primarily indirect. That is, impaired social interactions in children with ADHD reflect, to a significant extent, the behavioral outcome of being unable to maintain a focus of attention on information within working memory while simultaneously dividing attention among multiple, on-going events and social cues occurring within the environment. Central executive deficits impacted social problems through both inattentive and impulsive-hyperactive symptoms, whereas the subsidiary phonological and visuospatial storage/rehearsal systems demonstrated a more limited yet distinct relationship with children’s social problems.

Abstract: Obsessive compulsive disorder (OCD) and depressive rumination are both characterized by cognitive rigidity. We examined the performance of 17 patients (9 suffering from unipolar depression [UD] without OCD, and 8 suffering from OCD without UD), and 17 control participants matched on age, gender, language and education, on a battery covering the four main executive functions. Results indicated that, across both disorders, patients required more trials to adjust to single-task conditions after experiencing task switching, reflecting slow disengagement from switching mode, and showed abnormal post-conflict adaptation of processing mode following high conflict Stroop trials in comparison to controls. Rumination, which was elevated in UD and not in OCD, was associated with poor working memory updating and less task preparation. The results show that OCD and UD are associated with similar cognitive rigidity in the presently tested paradigms.

Abstract: Kirschner, F., Paas, F., & Kirschner, P. A. (2011). Task complexity as a driver for collaborative learning efficiency: The collective working-memory effect. Applied Cognitive Psychology, 25, 615–624. doi: 10.1002/acp.1730.

Abstract: Objective: Mild cognitive impairment (MCI) has emerged as a classification for a prodromal phase of cognitive decline that may precede the emergence of Alzheimer’s disease (AD). Recent research suggests that attention, executive, and working memory deficits may appear much earlier in the progression of AD than traditionally conceptualized, and may be more consistently associated with the later development of AD than memory processing deficits. The present study longitudinally tracked attention, executive and working memory functions in subtypes of MCI. Method: In a longitudinal study, 52 amnestic MCI (a-MCI), 29 nonamnestic MCI (na-MCI), and 25 age- and education-matched controls undertook neuropsychological assessment of visual and verbal memory, attentional processing, executive functioning, working memory capacity, and semantic language at 10 month intervals. Results: Analysis by repeated measures ANOVA indicate that the a-MCI and na-MCI groups displayed a decline in simple sustained attention (з 2 p = .054) with a significant decline on a task of divided attention (з 2 p = .053) being evident in the a-MCI group. Stable deficits were found on other measures of attention, working memory and executive function in the a-MCI and na-MCI groups. The a-MCI group displayed stable impairments to visual and verbal memory. Conclusions: The results indicate that a-MCI and na-MCI display a stable pattern of deficits to attention, working memory, and executive function. The decline in simple sustained attention in a-MCI and n-MCI groups and to divided attention in a-MCI may be early indicators of possible transition to dementia from MCI. However, further research is required to determine this.

Abstract: Flexible-resource theories characterize working memory as a flexible resource that can store either a large number of low-quality representations or a small number of high-quality representations. In contrast, limited-item theories propose that the number of items that can be stored in working memory is strictly limited and cannot be increased by decreasing the quality of the representations. We tested these fundamentally different conceptualizations of working memory capacity by determining whether observers could trade quality for quantity in working memory when given incentives to do so. We found no evidence that observers could increase the number of representations by decreasing their quality in working memory, but observers could make such a trade-off at earlier processing stages. Our results show that the capacity limit of working memory is best characterized as a limit on the number of items that can be stored and not as a limit on a finely divisible resource that simultaneously determines the number and quality of the representations.