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Memory Capacity (memory + capacity)

Distribution by Scientific Domains

Psychology	57%
Life Sciences	10%
Engineering	10%
4 Other Domains	23%

Selected Abstracts

Exploring the Relationship Between Modified Output and Working Memory Capacity

LANGUAGE LEARNING, Issue 3 2010
Alison Mackey
This study examines the relationship between learners' production of modified output and their working memory (WM) capacity. The task-based interactions of 42 college-level, native English-speaking learners of Spanish as a foreign language were examined. A relationship was found between learners' WM test scores and their tendency to modify output. Specifically, greater processing capacity was related to greater production of modified output during interaction. [source]

The Development of Visual Short-Term Memory Capacity in Infants

CHILD DEVELOPMENT, Issue 6 2003
Shannon Ross-sheehy
Four experiments assessed visual short-term memory capacity in 4- to 13-month-old infants by comparing their looking to changing and nonchanging stimulus streams presented side by side. In each stream, 1 to 6 colored squares repeatedly appeared and disappeared. In changing streams, the color of a different randomly chosen square changed each time the display reappeared; the colors remained the same in nonchanging streams. Infants should look longer at changing streams, but only if they can remember the colors of the squares. The youngest infants preferred changing streams only when the displays contained one object, whereas older infants preferred changing streams when the displays contained up to 4 objects. Thus, visual short-term memory capacity increases significantly across the first year of life. [source]

Developmental dyslexia and explicit long-term memory

DYSLEXIA, Issue 3 2010
Deny Menghini
Abstract The reduced verbal long-term memory capacities often reported in dyslexics are generally interpreted as a consequence of their deficit in phonological coding. The present study was aimed at evaluating whether the learning deficit exhibited by dyslexics was restricted only to the verbal component of the long-term memory abilities or also involved visual-object and visual-spatial domain. A further goal of the present study was to investigate the predictive value of non-verbal long-term memory abilities with respect to word and non-word reading in dyslexic children. In accordance with these aims, performances of 60 dyslexic children were compared with that of 65 age-matched normal readers on verbal, visual-spatial and visual-object task. Results documented a generalized impairment of episodic long-term memory capacities in dyslexic children and the results did not vary as a function of children's age. Furthermore, in addition to verbal measures, also individual differences in non-verbal long-term memory tasks turn out to be good predictors of reading difficulties in dyslexics. Our findings indicate that the long-term memory deficit in dyslexia is not limited to the dysfunction of phonological components but also involves visual-object and visual-spatial aspect, thus suggesting that dyslexia is associated to multiple cognitive deficits. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Age-dependent cognitive decline in the APP23 model precedes amyloid deposition

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2003
Debby Van Dam
Abstract Heterozygous APP23 mice, expressing human amyloid-precursor protein with the Swedish double mutation and control littermates, were subjected to behavioral and neuromotor tasks at the age of 6,8 weeks, 3 and 6 months. A hidden-platform Morris-type water maze showed an age-dependent decline of spatial memory capacities in the APP23 model. From the age of 3 months onwards, the APP23 mice displayed major learning and memory deficits as demonstrated by severely impaired learning curves during acquisition and impaired probe trial performance. In addition to the cognitive deficit, APP23 mice displayed disturbed activity patterns. Overnight cage-activity recording showed hyperactivity in the transgenics for the three age groups tested. However, a short 2-h recording during dusk phase demonstrated lower activity levels in 6-month-old APP23 mice as compared to controls. Moreover, at this age, APP23 mice differed from control littermates in exploration and activity levels in the open-field paradigm. These findings are reminiscent of disturbances in circadian rhythms and activity observed in Alzheimer patients. Determination of plaque-associated human amyloid-,1,42 peptides in brain revealed a fivefold increase in heterozygous APP23 mice at 6 months as compared to younger transgenics. This increase coincided with the first appearance of plaques in hippocampus and neocortex. Spatial memory deficits preceded plaque formation and increase in plaque-associated amyloid-,1,42 peptides, but probe trial performance did correlate negatively with soluble amyloid-, brain concentration in 3-month-old APP23 mutants. Detectable plaque formation is not the (only) causal factor contributing to memory defects in the APP23 model. [source]

Classical reward conditioning in Drosophila melanogaster

GENES, BRAIN AND BEHAVIOR, Issue 2 2007
Y-C. Kim
Negatively reinforced olfactory conditioning has been widely employed to identify learning and memory genes, signal transduction pathways and neural circuitry in Drosophila. To delineate the molecular and cellular processes underlying reward-mediated learning and memory, we developed a novel assay system for positively reinforced olfactory conditioning. In this assay, flies were involuntarily exposed to the appetitive unconditioned stimulus sucrose along with a conditioned stimulus odour during training and their preference for the odour previously associated with sucrose was measured to assess learning and memory capacities. After one training session, wild-type Canton S flies displayed reliable performance, which was enhanced after two training cycles with 1-min or 15-min inter-training intervals. Higher performance scores were also obtained with increasing sucrose concentration. Memory in Canton S flies decayed slowly when measured at 30 min, 1 h and 3 h after training; whereas, it had declined significantly at 6 h and 12 h post-training. When learning mutant t,,h flies, which are deficient in octopamine, were challenged, they exhibited poor performance, validating the utility of this assay. As the Drosophila model offers vast genetic and transgenic resources, the new appetitive conditioning described here provides a useful tool with which to elucidate the molecular and cellular underpinnings of reward learning and memory. Similar to negatively reinforced conditioning, this reward conditioning represents classical olfactory conditioning. Thus, comparative analyses of learning and memory mutants in two assays may help identify the molecular and cellular components that are specific to the unconditioned stimulus information used in conditioning. [source]

The learning credit card: A tool for managing personal development,

BRITISH JOURNAL OF EDUCATIONAL TECHNOLOGY, Issue 2 2008
Nick Rushby
This is the report of a five month study, undertaken by Sundridge Park Training Technologies in association with Guildford Educational Services to assess the potential of smart card technology to support learning and the management of learning. The study had two strands,the state of the art of the technology and its potential for supporting, delivering and managing learning. In addition to a study of the literature and extensive discussions with people using smart cards, potential users of smart card and visionaries, the project team developed two illustrative systems using cards to store personal data relating to education and training. The term ,smart card' is often used loosely to describe three different types of card, each of which is similar in general shape and size to a traditional credit card. These are: memory cards, laser cards,and true smart cards incorporating a processor and memory. This study has been concerned with memory cards and smart cards. The focus for smart card applications has been predominantly financial: there are relatively few applications in education or training. A notable exception is the large scale project at the University of Bologna which uses smart cards to manage the progress and achievements of a large number of students in the Department of Electronics. The two illustrative systems provided valuable experience of using memory cards and smart cards in quasi-real education and training applications. They highlighted the problems of limited memory capacities and confirmed the high level of user acceptance reported by other trials. We can expect considerable advances in the technology of both memory cards and smart cards over the next months and years. The memory capacities of both types of cards will increase many-fold and the unit costs will fall as large quantities of cards are produced for financial applications. Education and training applications will benefit from this expanding market. The major surprise from the study was the level of interest in the work and the enthusiasm expressed by almost all of those who came to hear of it. The general level of awareness of smart card technology was found to be low. However, the requirement for a system which will enable individuals to manage and own their learning on an extended timescale was generally recognised. Some of the possible applications for smart cards and memory cards in education and training had emerged before the official start of the study and it is clear that the technology is potentially pervasive. The project team and those consulted identified a wide range of possible applications both in education and in training. These focussed on assessment, personal course planning and management, identification of relevant learning opportunities, and the ownership of learning. It was felt that, over the next few years, smart cards are very likely to be in common use as credit cards for financial applications. Therefore, their use for education and training should be planned now. The recommendations from the study are that: More detailed studies are needed to find out how smart cards and memory cards could be used by different organisations in a fully operational system; Standards should be established for smart card applications in education and training, similar to those governing financial applications; Applications should be developed after the standards have been established. To be convincing, these should take a case study approach with small pilot studies in a variety of contexts and must follow real needs rather than attempt to drive them; The case studies would then form the basis for a campaign to increase awareness of smart cards and their potential for education and training, together with a programme for building an infrastructure to support the proposed systems. The public sector should fund the task of developing standards and providing interfaces with existing educational systems and projects to demonstrate the feasibility of various applications. Since educational standards have a European dimension, the European Community may be a source of support for work in the area of standards. At the same time, private sector funding should be sought for skill development and career development systems in industry and in education. The Training Agency itself should consider the application of smart card technology to the control and management of the Youth Training Scheme (YTS). [source]

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

DEVELOPMENTAL SCIENCE, Issue 1 2010
Nelson Cowan
Previous studies have indicated that visual working memory performance increases with age in childhood, but it is not clear why. One main hypothesis has been that younger children are less efficient in their attention; specifically, they are less able to exclude irrelevant items from working memory to make room for relevant items. We examined this hypothesis by measuring visual working memory capacity under a continuum of five attention conditions. A recognition advantage was found for items to be attended as opposed to ignored. The size of this attention-related effect was adult-like in young children with small arrays, suggesting that their attention processes are efficient even though their working memory capacity is smaller than that of older children and adults. With a larger working memory load, this efficiency in young children was compromised. The efficiency of attention cannot be the sole explanation for the capacity difference. [source]

Dispersion analysis of the meshfree radial point interpolation method for the Helmholtz equation

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 12 2009
Christina Wenterodt
Abstract When numerical methods such as the finite element method (FEM) are used to solve the Helmholtz equation, the solutions suffer from the so-called pollution effect which leads to inaccurate results, especially for high wave numbers. The main reason for this is that the wave number of the numerical solution disagrees with the wave number of the exact solution, which is known as dispersion. In order to obtain admissible results a very high element resolution is necessary and increased computational time and memory capacity are the consequences. In this paper a meshfree method, namely the radial point interpolation method (RPIM), is investigated with respect to the pollution effect in the 2D-case. It is shown that this methodology is able to reduce the dispersion significantly. Two modifications of the RPIM, namely one with polynomial reproduction and another one with a problem-dependent sine/cosine basis, are also described and tested. Numerical experiments are carried out to demonstrate the advantages of the method compared with the FEM. For identical discretizations, the RPIM yields considerably better results than the FEM. Copyright © 2008 John Wiley & Sons, Ltd. [source]

The winnerless competition paradigm in cellular nonlinear networks: Models and applications

INTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 4 2009
Paolo Arena
Abstract Starting from the biological background on the olfactory architecture of both insects and mammalians, different nonlinear systems able to respond to spatial-distributed external stimuli with spatial,temporal dynamics have been investigated in the last decade. Among these, there is a class of neural networks that produces quasi-periodic trajectories that pass near heteroclinic contours and prove to be global attractors for the system. For this reason, these networks are called winnerless competition (WLC) networks. The sequence of saddle points crossed by each trajectory depends on the spatial input presented to the network and can be used as a ,code' representing a specific class of stimuli. Thanks to the intrinsic discrimination, WLC networks are often used for classification. In this paper, this capability is exploited within a framework for action-oriented perception. WLC networks are here used as bio-inspired architectures for the association between stimuli and ,percepts'. After presenting the theoretical basis of the WLC network in the classic Lotka,Volterra system, we investigate how WLC networks can be formalized in terms of cellular nonlinear networks (CNNs) hosting different kinds of cells: the FitzHugh,Nagumo neuron, the Izhikevich neuron and the single layer CNN standard cell. In order to find efficient ways to code environmental stimuli for action generation, we analyze and compare these WLC-based CNNs in terms of number of generated classes and robustness against the initial conditions. Based on the simulation results, we apply the best-performing system to solve a perceptual task involving navigation and obstacle avoidance. We demonstrate how the large memory capacity shown by the WLC,CNN is able to contribute to the new perceptual framework for autonomous artificial agents, where the association between stimuli and sequences is learned through the experience. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Neural correlates of verbal episodic memory in patients with MCI and Alzheimer's disease,,a VBM study

INTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 11 2008
Dirk T. Leube
Abstract Objective The hippocampus is a key area for episodic memory processes. Hippocampal atrophy is a hallmark feature of Alzheimer's disease (AD). We used a new and automatized morphometric technique to better characterize brain atrophy in subjects with different levels of cognitive deficit. Methods In this study 21 participants with Mild Cognitive Impairment (MCI), 12 patients with early AD and 29 elderly control subjects were subjected to high resolution MRI and a neuropsychological test battery. Brain volume across participants, measured by voxel-based morphometry (VBM), was correlated with verbal memory capacity, measured with a verbal memory test (VLMT). Results Atrophy in the anterior hippocampus, the ento- and perirhinal cortex as well as the parahippocampal gyrus, middle temporal gyrus and anterior cingulate cortex correlated closely with episodic memory performance. Conclusions These brain areas are known to subserve episodic encoding of verbal material. The data contribute to a better understanding of atrophic brain processes in subjects at risk for AD. A combination of neuropsychological testing and voxel-based morphometry may serve as a diagnostic tool in the future. Copyright © 2008 John Wiley & Sons, Ltd. [source]

A Self-Regulatory Model of Behavioral Disinhibition in Late Adolescence: Integrating Personality Traits, Externalizing Psychopathology, and Cognitive Capacity

JOURNAL OF PERSONALITY, Issue 2 2010
Tim Bogg
ABSTRACT Two samples with heterogeneous prevalence of externalizing psychopathology were used to investigate the structure of self-regulatory models of behavioral disinhibition and cognitive capacity. Consistent with expectations, structural equation modeling in the first sample (N=541) showed a hierarchical model with 3 lower order factors of impulsive sensation seeking, antisociality/unconventionality, and lifetime externalizing problem counts, with a behavioral disinhibition superfactor best accounted for the pattern of covariation among 6 disinhibited personality trait indicators and 4 externalizing problem indicators. The structure was replicated in a second sample (N=463) and showed that the behavioral disinhibition superfactor, and not the lower order impulsive sensation seeking, antisociality/unconventionality, and externalizing problem factors, was associated with lower IQ, reduced short-term memory capacity, and reduced working memory capacity. The results provide a systemic and meaningful integration of major self-regulatory influences during a developmentally important stage of life. [source]

Effects of incentive on working memory capacity: Behavioral and pupillometric data

PSYCHOPHYSIOLOGY, Issue 1 2008
Richard P. Heitz
Abstract We evaluated the hypothesis that individual differences in working memory capacity are explained by variation in mental effort, persons with low capacity exerting less effort than persons with high capacity. Groups previously rated high and low in working memory capacity performed the reading span task under three levels of incentive. The effort hypothesis holds that low span subjects exert less effort during task performance than do high spans. Subjects' pupil sizes were recorded online during task performance as a measure of mental effort. Both recall performance and pupil diameter were found to be increased under incentives, but were additive with span (incentives increased performance and pupil diameter equivalently for both span groups). Contrary to the effort hypothesis, task-evoked pupillary responses indicated that if anything, low span subjects exert more effort than do high spans. [source]

Shooting behaviour: How working memory and negative emotionality influence police officer shoot decisions

APPLIED COGNITIVE PSYCHOLOGY, Issue 5 2010
Heather M. Kleider
Previous research on police officer shoot decisions has focussed on the influence of situational factors that lead to the shooting error. Focussing instead on the ,shooter', the present study examined whether working memory capacity and threat-related increases in negative emotionality influenced participant shoot decisions in a simulated shooting task. Following a working memory test, 24 police officers viewed a police-relevant threatening video while physiological indices of arousal and negative affect were obtained and then completed a computerized shoot-don't shoot task. Results indicated that lower working memory capacity was associated with a greater likelihood of shooting unarmed targets and a failure to shoot armed targets. Moreover, an interaction effect indicated that these associations were only significant for officers who experienced heightened negative emotionality in response to the video. Results suggest that when negatively aroused via threat, limited working memory capacity increases the risk of shooting error. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Individual differences in susceptibility to the effects of speech on reading comprehension

APPLIED COGNITIVE PSYCHOLOGY, Issue 1 2010
Patrik Sörqvist
Individuals with high working memory capacity (WMC) are less distracted by task-irrelevant speech than others. The mechanism behind this relationship, however, is not well understood, and it has only been found in a few paradigms. We used a Number updating task to measure WMC and two suppression mechanisms (immediate and delayed), and tested how they were associated with individual differences in susceptibility to the effects of speech on reading comprehension. The results revealed a negative relationship between WMC and susceptibility to speech distraction. Of the two suppression mechanisms, only immediate suppression was associated with speech distraction, suggesting that susceptibility to distraction is determined by the ability to immediately suppress the irrelevant speech. Furthermore, the relationship between WMC and speech distraction was mediated by the immediate suppression mechanism. The implications of these results and possible explanations of similar results found in other paradigms are discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Protein Kinase C Activators as Synaptogenic and Memory Therapeutics

ARCHIV DER PHARMAZIE, Issue 12 2009
Miao-Kun Sun
Abstract The last decade has witnessed a rapid progress in understanding of the molecular cascades that may underlie memory and memory disorders. Among the critical players, activity of protein kinase C (PKC) isoforms is essential for many types of learning and memory and their dysfunction, and is critical in memory disorders. PKC inhibition and functional deficits lead to an impairment of various types of learning and memory, consistent with the observations that neurotoxic amyloid inhibits PKC activity and that transgenic animal models with PKC, deficit exhibit impaired capacity in cognition. In addition, PKC isozymes play a regulatory role in amyloid production and accumulation. Restoration of the impaired PKC signal pathway pharmacologically results in an enhanced memory capacity and synaptic remodeling / repair and synaptogenesis, and, therefore, represents a potentially important strategy for the treatment of memory disorders, including Alzheimer's dementia. The PKC activators, especially those that are isozyme-specific, are a new class of drug candidates that may be developed as future memory therapeutics. [source]

Variable Memory Strategy Use in Children's Adaptive Intratask Learning Behavior: Developmental Changes and Working Memory Influences in Free Recall

CHILD DEVELOPMENT, Issue 4 2007
Martin Lehmann
Variability in strategy use within single trials in free recall was analyzed longitudinally from second to fourth grades (ages 8,10 years). To control for practice effects another sample of fourth graders was included (age 10 years). Video analyses revealed that children employed different strategies when preparing for free recall. A gradual shift from labeling to cumulative rehearsal was present both with increasing age and across different list positions. Whereas cumulative rehearsal was frequent at early list positions, labeling was dominant at later list portions. Working memory capacity predicted the extent of cumulative rehearsal usage, which became more efficient with increasing age. Results are discussed in the context of the adaptive strategy choice model. [source]