Abstract: The authors investigated the distinctiveness and interrelationships among visuospatial and verbal memory processes in short-term, working, and long-term memories in 345 adults. Beginning in the 20s, a continuous, regular decline occurs for processing-intensive tasks (e.g., speed of processing, working memory, and long-term memory), whereas verbal knowledge increases across the life span. There is little differentiation in the cognitive architecture of memory across the life span. Visuospatial and verbal working memory are distinct but highly interrelated systems with domain-specific short-term memory subsystems. In contrast to recent neuroimaging data, there is little evidence for dedifferentiation of function at the behavioral level in old compared with young adults. The authors conclude that efforts to connect behavioral and brain data yield a more complete understanding of the aging mind.

Abstract: Recent theoretical work has suggested that brain oscillations in the theta band are involved in active maintenance and recall of working memory representations. To test this theoretical framework we recorded neuromagnetic responses from 10 subjects performing the Sternberg task. Subjects were required to retain a list of 1, 3, 5 or 7 visually presented digits during a 3-s retention period. During the retention period we observed ongoing frontal theta activity in the 7-8.5-Hz band recorded by sensors over frontal brain areas. The activity in the theta band increased parametrically with the number of items retained in working memory. A time-frequency analysis revealed that the task-dependent theta was present during the retention period and during memory scanning. Following the memory task the theta activity was reduced. These results suggest that theta oscillations generated in frontal brain regions play an active role in memory maintenance.

Abstract: Working memory (WM) capacity is the ability to retain and manipulate information during a short period of time. This ability underlies complex reasoning and has generally been regarded as a fixed trait of the individual. Children with attention deficit hyperactivity disorder (ADHD) represent one group of subjects with a WM deficit, attributed to an impairment of the frontal lobe. In the present study, we used a new training paradigm with intensive and adaptive training of WM tasks and evaluated the effect of training with a double blind, placebo controlled design. Training significantly enhanced performance on the trained WM tasks. More importantly, the training significantly improved performance on a nontrained visuo-spatial WM task and on Raven’s Progressive Matrices, which is a nonverbal complex reasoning task. In addition, motor activity ‐ as measured by the number of head movements during a computerized test ‐ was significantly reduced in the treatment group. A second experiment showed that similar training-induced improvements on cognitive tasks are also possible in young adults without ADHD. These results demonstrate that performance on WM tasks can be significantly improved by training, and that the training effect also generalizes to nontrained tasks requiring WM. Training improved performance on tasks related to prefrontal functioning and had also a significant effect on motor activity in children with ADHD. The results thus suggest that WM training potentially could be of clinical use for ameliorating the symptoms in ADHD.

Abstract: To study the role of brain oscillations in working memory, we recorded the scalp electroencephalogram (EEG) during the retention interval of a modified Sternberg task. A power spectral analysis of the EEG during the retention interval revealed a clear peak at 9−12 Hz, a frequency in the alpha band (8−13 Hz). In apparent conflict with previous ideas according to which alpha band oscillations represent brain ‘idling’, we found that the alpha peak systematically increased with the number of items held in working memory. The enhancement was prominent over the posterior and bilateral central regions. The enhancement over posterior regions is most likely explained by the well known alpha rhythm produced close to the parietal-occipital fissure, whereas the lateral enhancement could be explained by sources in somato-motor cortex. A time-frequency analysis revealed that the enhancement was present throughout the last 2.5 s of the 2.8 s retention interval and that alpha power rapidly diminished following the probe. The load dependence and the tight temporal regulation of alpha provide strong evidence that the alpha generating system is directly or indirectly linked to the circuits responsible for working memory. Although a clear peak in the theta band (5−8 Hz) was only detectable in one subject, other lines of evidence indicate that theta occurs and also has a role in working memory. Hypotheses concerning the role of alpha band activity in working memory are discussed.

Abstract: Participants memorized briefly presented sets of digits, a subset of which had to be accessed as input for arithmetic tasks (the active set), whereas another subset had to be remembered independently of the concurrent task (the passive set). Latencies for arithmetic operations were a function of the setsize of active but not passive sets. Object-switch costs were observed when successive operations were applied to different digits within an active set. Participants took 2 s to encode a passive set so that it did not affect processing latencies (Experiment 2). The results support a model distinguishing 3 states of representations in working memory: the activated part of long-term memory, a capacity limited region of direct access, and a focus of attention.

Abstract: Background: Cognitive abilities of older persons range from normal, to mild cognitive impairment, to dementia. Few large longitudinal studies have compared the natural history of mild cognitive impairment with similar persons without cognitive impairment. Methods: Participants were older Catholic clergy without dementia, 211 with mild cognitive impairment and 587 without cognitive impairment, who underwent annual clinical evaluation for AD and an assessment of different cognitive abilities. Cognitive performance tests were summarized to yield a composite measure of global cognitive function and separate summary measures of episodic memory, semantic memory, working memory, perceptual speed, and visuospatial ability. The authors compared the risk of death, risk of incident AD, and rates of change in global cognition and different cognitive domains among persons with mild cognitive impairment to those without cognitive impairment. All models controlled for age, sex, and education. Results: On average, persons with mild cognitive impairment had significantly lower scores at baseline in all cognitive domains. Over an average of 4.5 years of follow-up, 30% of persons with mild cognitive impairment died, a rate 1.7 times higher than those without cognitive impairment (95% CI, 1.2 to 2.5). In addition, 64 (34%) persons with mild cognitive impairment developed AD, a rate 3.1 times higher than those without cognitive impairment (95% CI, 2.1 to 4.5). Finally, persons with mild cognitive impairment declined significantly faster on measures of episodic memory, semantic memory, and perceptual speed, but not on measures of working memory or visuospatial ability, as compared with persons without cognitive impairment. Conclusions: Mild cognitive impairment is associated with an increased risk of death and incident AD, and a greater rate of decline in selected cognitive abilities.

Abstract: The relation between executive function (EF) and theory of mind (ToM) may involve specific processes of inhibition and/or working memory capacity contributing to ToM, or it might be a reflection of general intellectual ability. To differentiate these alternatives, we administered task batteries measuring inhibitory control (IC), working memory, and ToM, as well as measures of verbal and performance intelligence, to 47 typically developing preschool children. Inhibitory control tasks in which a dominant response needed to be suppressed while a subdominant response was activated (Conflict IC) significantly predicted performance on false belief tasks over and above working memory, the intelligence measures, a simple delay task (Delay IC), and age. In contrast, working memory, Delay IC, and intelligence were not significant in this analysis. Conflict IC, but not Delay IC, was related to working memory. Together, these findings suggest that the combination of inhibition and working memory (as reflected in Conflict IC tasks) may be central to the relation between EF and false belief understanding. Copyright © 2002 John Wiley & Sons, Ltd.

Abstract: Working memory represents the ability of the brain to hold externally or internally driven information for relatively short periods of time1,2. Persistent neuronal activity is the elementary process underlying working memory but its cellular basis remains unknown. The most widely accepted hypothesis is that persistent activity is based on synaptic reverberations in recurrent circuits. The entorhinal cortex in the parahippocampal region is crucially involved in the acquisition, consolidation and retrieval of long-term memory traces for which working memory operations are essential2. Here we show that individual neurons from layer V of the entorhinal cortex—which link the hippocampus to extensive cortical regions3—respond to consecutive stimuli with graded changes in firing frequency that remain stable after each stimulus presentation. In addition, the sustained levels of firing frequency can be either increased or decreased in an input-specific manner. This firing behaviour displays robustness to distractors; it is linked to cholinergic muscarinic receptor activation, and relies on activity-dependent changes of a Ca2+-sensitive cationic current. Such an intrinsic neuronal ability to generate graded persistent activity constitutes an elementary mechanism for working memory.

Abstract: M. A. Just and P. A. Carpenter’s (1992) capacity theory of comprehension posits a linguistic working memory functionally separated from the representation of linguistic knowledge. G. S. Waters and D. Caplan’s (1996) critique of this approach retained the notion of a separate working memory. In this article, the authors present an alternative account motivated by a connectionist approach to language comprehension. In their view, processing capacity emerges from network architecture and experience and is not a primitive that can vary independently. Individual differences in comprehension do not stem from variations in a separate working memory capacity; instead they emerge from an interaction of biological factors and language experience. This alternative is argued to provide a superior account of comprehension results previously attributed to a separate working memory capacity. The concept of a working memory resource or capacity for temporary storage and manipulation of information has played an important role in many theories of cognition, particularly theories of language processing (e.g., Baddeley, 1986; Engle, Cantor, & Carullo, 1992; Just & Carpenter, 1992). The particular approach advocated by Just and Carpenter (1992) is one in which linguistic working memory capacity directly constrains the operation of language comprehension processes, and that variation in the capacity of linguistic working memory within the normal population is a primary source of individual differences in language comprehension. Just and Carpenter further suggest that reductions in working memory capacity in aging can explain reduced language comprehension and production abilities among normal elderly adults and that aphasic patients’ language comprehension deficits following brain injury may be explained by a deficit in working memory capacity rather than by a loss of linguistic knowledge (Miyake, Carpenter, & Just, 1994). Just and Carpenter’s work has been extremely successful in emphasizing the importance of individual differences in language research, but their approach is not without controversy. Criticisms of their claims have taken several forms. Waters and Caplan (1996) suggested that there are at least two different working memory capacities that subserve language use, and they have sharply criticized the data that Just and Carpenter interpreted in support of a single working memory capacity (see also Caplan & Waters, 1999b; cf. Just, Carpenter, & Keller, 1996). Similarly, several aphasia researchers have suggested that a reduction of working memory capacity is not an adequate description of these

Abstract: The current state of A.D. Baddeley and G.J. Hitch's (1974) multicomponent working memory model is reviewed. The phonological and visuospatial subsystems have been extensively investigated, leading both to challenges over interpretation of individual phenomena and to more detailed attempts to model the processes underlying the subsystems. Analysis of the controlling central executive has proved more challenging, leading to a proposed clarification in which the executive is assumed to be a limited capacity attentional system, aided by a newly postulated fourth system, the episodic buffer. Current interest focuses most strongly on the link between working memory and long-term memory and on the processes allowing the integration of information from the component subsystems. The model has proved valuable in accounting for data from a wide range of participant groups under a rich array of task conditions. Working memory does still appear to be working.

Abstract: Participants remembered a short set of words while read- ing syntactically complex sentences (object-extracted clefts) and syn- tactically simpler sentences (subject-extracted clefts) in a memory-load study. The study also manipulated whether the words in the set and the words in the sentence were of matched or unmatched types (common nouns vs. proper names). Performance in sentence comprehension was worse for complex sentences than for simpler sentences, and this effect was greater when the type of words in the memory load matched the type of words in the sentence. These results indicate that syntactic processing is not modular, instead suggesting that it relies on working memory resources that are used for other nonsyntactic processes. Fur- ther, the results indicate that similarity-based interference is an im- portant constraint on information processing that can be overcome to some degree during language comprehension by using the coherence of language to construct integrated representations of meaning.

Abstract: It has become fashionable to equate constructs of working memory (WM) and general intelligence (g). Few investigations have provided direct evidence that WM and g measures yield similar ordering of individuals. Correlational investigations have yielded mixed results. The authors assess the construct space for WM and g and demonstrate that WM shares substantial variance with perceptual speed (PS) constructs. Thirty-six ability tests representing verbal, numerical, spatial, and PS abilities; the Raven Advanced Progressive Matrices; and 7 WM tests were administered to 135 adults. A nomological representation for WM is provided through a series of cognitive and PS ability models. Construct overlap between PS and WM is further investigated with attention to complexity, processing differences, and practice effects.

Abstract: Working memory is hypothesized to comprise a collection of distinct components or processes, each of which may have a unique neural substrate. Recent neuroimaging studies have isolated a region of the left inferior frontal gyrus that appears to be related specifically to one such component: resolving interference from previous items in working memory. In the present study, we examined working memory in patients with unilateral frontal lobe lesions by using a modified version of an item recognition task in which interference from previous trials was manipulated. In particular, we focused on patient R.C., whose lesion uniquely impinged on the region identified in the neuroimaging studies of interference effects. We measured baseline working memory performance and interference effects in R.C. and other frontal patients and in age-matched control subjects and young control subjects. Comparisons of each of these groups supported the following conclusions. Normal aging is associated with changes to both working memory and interference effects. Patients with frontal damage exhibited further declines in working memory but normal interference effects, with the exception of R.C., who exhibited a pronounced interference effect on both response time and accuracy. We propose that the left inferior frontal gyrus subserves a general, nonmnemonic function of selecting relevant information in the face of competing alternatives and that this function may be required by some working memory tasks.

Abstract: 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.

Abstract: Previous studies of attention-directing cues have focused largely on the effects of cuing on perceptual processes, but cuing may also influence the transfer of perceptual representations into visual working memory. In the present study, we examined this potential role of cues, using both predictive and nonpredictive cues in the context of a visual working memory task. Each trial began with a cue, followed by an array of six colored squares, a delay interval, and then a probe square presented at the location of one of the squares in the previous array. The subjects were required to indicate whether the color of the probe square was the same as the color of the square that had previously been presented at the same location. Performance on this working memory task was more accurate when the cued location was probed than when an uncued location was probed, even when the cued location was no more likely to be probed than any of the uncued locations. An additional experiment using the abrupt-onset paradigm of Yantis and Jonides (1984) yielded similar results. Thus, visual transients may automatically influence the transfer of perceptual representations into visual working memory.

Abstract: The association between executive function (EF; planning, working memory, and inhibition) and individual differences in symptoms of attention deficit hyperactivity disorder (ADHD) was explored in a sample of preschool children. One hundred sixty children (between the ages of 3 years, 0 months and 5 years, 6 months), selected so as to oversample high ADHD scorers, performed 3 tasks previously shown to measure planning (Tower of London), working memory (Noisy Book) and inhibition ("Puppet Says..."). EF measures were reliable (k > .77) and were correlated with IQ (rs > .38) and age (rs > .59). Once IQ and age were controlled, planning and working memory (r = .41) were correlated. Planning and working memory were not correlated with inhibition (rs < .20). There was no association between ADHD and working memory or planning (rs < .12). There was a significant negative association between ADHD and conduct problems and inhibition (r = -.30 and r = -.25, respectively). Only the link with ADHD persisted after the ...

Abstract: This study assessed the reading, language, and memory skills of 56 bilingual Arab-Canadian children age's 9-14. English was their main instructional language, and Arabic was the language spoken at home. All children attended a Heritage Language Program in Toronto where they were taught to read and write Arabic. The children were administered word and pseudo-word reading, language, and working memory tests in English and Arabic. The majority of the children showed at least adequate proficiency in both languages. There was a significant relationship between the acquisition of word and pseudo-word reading working memory, and syntactic awareness skills in the two languages. The poor readers in Arabic had lower scores on all linguistic tasks, except the visual task. There were no significant differences between bilingual English Arabic children and monolingual English-speaking children on the reading, language, and memory tasks. However, bilingual English Arabic children who had reading problems in English had higher scores on English pseudo-word reading and spelling tasks than monolingual English-speaking children with reading disabilities, probably because of positive transfer from the regular nature of Arabic orthography. In this case, bilingualism does not appear to have negative consequences for the development of language reading skills in both languages—Arabic and English—despite the different nature of the two orthographies.

Abstract: Summary Recent research on prospective memory suggests the involvement of executive functions in explaining performance in complex task environments. However, few theoretical concepts specify which executive functions contribute to prospective memory performance. Moreover, it is unclear which executive functions are required in the course of the prospective memory process. Therefore, we argue that prospective memory should be conceptualized as a multi-phasic process and propose a theoretical model that disentangles four different phases: (a) forming an intention, (b) maintaining the intention, (c) initiating the intended action, and (d) executing the intention. Empirical tests of the model with eighty adults reveal that more than 50 percent of the variance in the complex prospective memory task is predicted by the executive measures. Of those, planning and cognitive flexibility are particularly important predictors. The discussion focuses on the role of particular executive functions in predicting performance in specific phases of prospective remembering. Key words: prospective memory, executive functions, planning, cognitive flexibility, inhibition, working memory According to Neisser (1982), "to remember" stands for two different everyday cognitive processes: "remembering what we must do" and "remembering what we have done." The current literature refers to the first type of remembering as prospective memory and to the second as retrospective memory (Einstein & McDaniel, 1990, 1996). Although its proper labeling is still under discussion (Burgess, 2000; Crowder, 1996; Ellis, 1996; Goschke & Kuhl, 1996), the field of prospective memory research "is booming" (Roediger, 1996, p. 149; cf also Ellis & Kvavilashvili, 2000). Interest in prospective memory is largely based on its relevance in everyday life, for example having to remember to attend a meeting, to buy a certain item in the grocery store, or to manage the various daily tasks at home and at work. The cognitive mechanisms underlying prospective memory performance have become an issue of major interest. In searching for processes explaining differences in prospective remembering, some researchers have focused on processes related to retrospective memory (e.g., recency and proximity effects; Hitch & Ferguson, 1991). The general hypothesis of many studies was that, in principle, prospective memory performance can be explained by the same mechanisms underlying performance in well-known retrospective memory tasks such as delayed recall (Crowder, 1996). In more recent work, the impact of another memory process, i.e., working memory, has been investigated. Consistently, and with different prospective tasks, these studies report that working memory capacity predicts significant amounts of the variance in prospective memory performance (e.g., Cherry & LeCompte, 1999; Kliegel, McDaniel & Einstein, 2000; Martin & Park, 1999). In sum, some parts of the existing literature suggest that processes related to retrospective memory performance explain differences in prospective memory performance. However, this conclusion might be premature for two reasons. First, most empirical studies report only weak relations between retrospective memory processes and prospective memory performance (Cockburn, 1995; Einstein, Holland, McDaniel & Guynn, 1992; Einstein & McDaniel, 1990; Kliegel et al., 2000; Kvavilashvili, 1987). Second, task analyses of everyday prospective memory suggest that prospective remembering requires more than just retrospective memory. In fact, it seems obvious that in everyday life one typically works on several "subtasks" in order to perform well on an everyday prospective memory task: One has to form an intention, one has to keep the intention in mind while working on ongoing activities, one has to monitor the environment to initiate the action at the appropriate time, and one has to perform the intended action according to the previously planned intention (Ellis, 1996). …

Abstract: This Monograph aims to contribute to the information processing, the differential, and the developmental modeling of the mind, and to work these into an integrated theory. Toward this aim, a longitudinal study is presented that investigates the relations between processing efficiency, working memory, and problem solving from the age of 8 years to to the age of 16 years. The study involved 113 participants, about equally drawn among 8-, 10-, 12-, and 14-year-olds at the first testing; these participants were tested two more times spaced one year apart. Participants were tested with a large array of tasks addressed to processing efficiency (i.e., speed of processing and inhibition), working memory (in terms of Baddeley's model, phonological storage, visual storage, and the central executive of working memory), and problem solving (quantitative, spatial, and verbal reasoning). Confirmatory factor analysis validated the presence of each of the above dimensions and indicated that they are organized in a three-stratum hierarchy. The first stratum includes all of the individual dimensions mentioned above. These dimensions are organized, at the second stratum, in three constructs: processing efficiency, working memory, and problem solving. Finally, all second-order constructs are strongly related to a third-order general factor. This structure was stable in time. Structural equation modeling indicated that the various dimensions are interrelated in a cascade fashion so that more fundamental dimensions are part of more complex dimensions. That is, speed of processing is the most important aspect of processing efficiency, and it perfectly relates to the condition of inhibition, indicating that the more efficient one is in stimulus encoding and identification, the more efficient one is in inhibition. In turn, processing efficiency is strongly related to the condition of executive processes in working memory, which, in turn, is related to the condition of the two modality-specific stores (phonological and visual). Finally, problem solving is related to processing efficiency and working memory, the central executive in particular. All dimensions appear to change systematically with time. Growth modeling suggested that there are significant individual differences in attainment in each of the three aspects of the mind investigated. Moreover, each of the three aspects of the mind as well as their interrelations change differently during development. Mixture growth modeling suggested that there are four types of developing persons, each defined by a different combination of performance in these aspects of the mind. Some types are more efficient and stable developers than others. These analyses indicated that processing efficiency is a factor closely associated with developmental differences in problem solving, whereas working memory is associated with individual differences. Modeling by logistic equations uncovered the rates and form of change in the various dimensions and their reciprocal interactions during development. These findings are discussed from the point of view of information processing, differential, and developmental models of thinking, and an integrative model is proposed.

Abstract: Several studies have reported beneficial effects of treatments for attentional deficits following traumatic brain injury Improvements in speed of processing appear to be less robust than improvements on non-speeded tasks, while several studies suggest greater benefits of training more complex forms of attention The present study presents preliminary results concerning the effectiveness of an intervention for attentional deficits after mild traumatic brain injury The treatment was based upon the conceptualization of deficits and interventions as a function of the central executive component of working memory, or "working attention" A prospective, case-comparison design was employed comparing four treatment participants with an untreated comparison sample Treatment tasks were derived from experimental procedures which have been demonstrated to elicit working memory demands, consisting of "n-back", random generation, and dual-task procedures The intervention emphasized the conscious and deliberate use of strategies to effectively allocate attentional resources and manage the rate of information during task performance Treatment participants were more likely to exhibit clinically significant improvement on measures of attention and reduction of self-reported attentional difficulties in their daily functioning Further analysis suggested that the principal effect of the intervention was on working memory, ie the ability to temporarily maintain and manipulate information during task performance, with no direct effect on processing speed The results are consistent with a strategy training model of remediation, in which the benefits of treatment are due to participants' improved ability to compensate for residual deficits and adopt strategies for the more effective allocation of their remaining attentional resources

Abstract: Background Impairments in working memory have been proposed to underlie a broad range of cognitive deficits seen in schizophrenia. Visual working memory impairments are frequently reported in schizophrenia. Investigations of visual working memory generally assume intact visual information processing, despite evidence of visual perceptual impairments in schizophrenia. In this study, we evaluated the integrity of the perceptual system for object and spatial visual information and the relevant working memory system, after adjusting for individual perceptual performance differences. Methods Thirty patients with schizophrenia and 20 healthy control subjects underwent testing using a task of perceptual discrimination of spatial and object visual stimuli. For testing visual working memory, a delay was introduced to the perceptual discrimination task. A thresholding procedure was used so that each subject adequately perceived the information during the working memory test. Results Subjects with schizophrenia exhibited impaired performance relative to controls for object and spatial visual perceptual discrimination. The extent of impairment was greater for the object than for the spatial test. After controlling for perceptual impairments, the subjects with schizophrenia exhibited impaired performance relative to controls for the spatial working memory test but not the object working memory test. Conclusions Findings implicate dysfunction of posterior brain areas that mediate visual perceptual processing and the prefrontal areas involved in the active maintenance of information during delay intervals. However, the systems that govern object and spatial visual perception and working memory appear to be affected differentially by schizophrenia.