Short-term Memory Capacity Research Articles

Semantic and Syntactic Interference in Sentence Comprehension: A Comparison of Working Memory Models.

This study investigated the nature of the underlying working memory system supporting sentence processing through examining individual differences in sensitivity to retrieval interference effects during sentence comprehension. Interference effects occur when readers incorrectly retrieve sentence constituents which are similar to those required during integrative processes. We examined interference arising from a partial match between distracting constituents and syntactic and semantic cues, and related these interference effects to performance on working memory, short-term memory (STM), vocabulary, and executive function tasks. For online sentence comprehension, as measured by self-paced reading, the magnitude of individuals' syntactic interference effects was predicted by general WM capacity and the relation remained significant when partialling out vocabulary, indicating that the effects were not due to verbal knowledge. For offline sentence comprehension, as measured by responses to comprehension questions, both general WM capacity and vocabulary knowledge interacted with semantic interference for comprehension accuracy, suggesting that both general WM capacity and the quality of semantic representations played a role in determining how well interference was resolved offline. For comprehension question reaction times, a measure of semantic STM capacity interacted with semantic but not syntactic interference. However, a measure of phonological capacity (digit span) and a general measure of resistance to response interference (Stroop effect) did not predict individuals' interference resolution abilities in either online or offline sentence comprehension. The results are discussed in relation to the multiple capacities account of working memory (e.g., Martin and Romani, 1994; Martin and He, 2004), and the cue-based retrieval parsing approach (e.g., Lewis et al., 2006; Van Dyke et al., 2014). While neither approach was fully supported, a possible means of reconciling the two approaches and directions for future research are proposed.

Cognitive Effects of Androgen Deprivation Therapy in Men With Advanced Prostate Cancer

To evaluate the prostate cancer effects of androgen deprivation therapy (ADT) by using a systematic set of methods to calculate specific cognitive functions in men with locally advanced or metastatic prostate cancer. From April 2014 to February 2016, a prospective, comparative study was done to evaluate the cognitive effects of hormone therapy. Group 1 consisted of 78 patients with locally advanced or metastatic prostate cancer who received complete ADT treatment continuously for 12 months and group 2 (control group) consisted of 78 patients who underwent radical prostatectomy without any additional treatment. The Montreal Cognitive Assessment (MoCA) test and the Frontal Assessment Battery (FAB) test with Turkish language version were used to evaluate multiple domains of cognitive function. Post-treatment results of both tests revealed that patients in group 1 achieved lower mean total scores than group 2. In MoCA test, the deficits were especially prominent in the areas of language ability and short-term memory capacity (P < .05 and P < .05). No significant differences could be identified between groups in respect to attention, executive functions, visuospatial abilities, abstract thinking, calculating abilities, and orientation. In FAB test, the deficits were especially prominent in the areas of mental flexibility and inhibitory control (P < .05 and P < .05). No significant differences could be identified between groups in conceptualization, motor series, conflicting instructions, and environmental autonomy. ADT affects cognitive functions such as language ability, short-term memory capacity, mental flexibility, and inhibitory control. Urologists should keep in mind these side effects and inform the patients and their families for the early symptoms of cognitive dysfunction.

Impaired visual short-term memory capacity is distinctively associated with structural connectivity of the posterior thalamic radiation and the splenium of the corpus callosum in preterm-born adults

Preterm birth is associated with an increased risk for lasting changes in both the cortico-thalamic system and attention; however, the link between cortico-thalamic and attention changes is as yet little understood. In preterm newborns, cortico-cortical and cortico-thalamic structural connectivity are distinctively altered, with increased local clustering for cortico-cortical and decreased integrity for cortico-thalamic connectivity. In preterm-born adults, among the various attention functions, visual short-term memory (vSTM) capacity is selectively impaired. We hypothesized distinct associations between vSTM capacity and the structural integrity of cortico-thalamic and cortico-cortical connections, respectively, in preterm-born adults.A whole-report paradigm of briefly presented letter arrays based on the computationally formalized Theory of Visual Attention (TVA) was used to quantify parameter vSTM capacity in 26 preterm- and 21 full-term-born adults. Fractional anisotropy (FA) of posterior thalamic radiations and the splenium of the corpus callosum obtained by diffusion tensor imaging were analyzed by tract-based spatial statistics and used as proxies for cortico-thalamic and cortico-cortical structural connectivity.The relationship between vSTM capacity and cortico-thalamic and cortico-cortical connectivity, respectively, was significantly modified by prematurity. In full-term-born adults, the higher FA in the right posterior thalamic radiation the higher vSTM capacity; in preterm-born adults this FA-vSTM-relationship was inversed. In the splenium, higher FA was correlated with higher vSTM capacity in preterm-born adults, whereas no significant relationship was evident in full-term-born adults.These results indicate distinct associations between cortico-thalamic and cortico-cortical integrity and vSTM capacity in preterm-and full-term-born adults. Data suggest compensatory cortico-cortical fiber re-organization for attention deficits after preterm delivery.

Comparative Study of Visual &amp; Auditory Memory between Psychology &amp; Non-Psychology Students: Testing a Stream Hypothesis

Background and Objectives: The process of retention and storage of any kind of information is known as Memory. Present study was conducted to compare the Visual &amp; Auditory Short term memory (STM) in Psychology &amp; Non psychology Students. Materials and Methods: After appropriate consent from students and department. The study comprised of 60 students (30 Psychology, 30 non-psychology/other stream students ) aged 16-20 years of Amity University Gwalior, M.P included ,students having infirmities (Visual or Auditory) were excluded. Reaction time for audiovisual exposures to recalling is noted in all ten subtests. Results: There is a strong difference between the retention and storing capacity of visual STM and auditory STM among both groups. Results: There is a strong difference between the retention and storing capacity of visual STM and auditory STM (p&lt;0.001) between both groups. The mean reaction time is more for long words/sentences than short words. Short words are remembered more accurately than long words by both groups. Interpretation and Conclusion: The visual STM has a short mean reaction time and more accuracy than auditory STM. STM and working memory plays an important role in the learning processes of both groups of undergraduate students.

Determination of the Edge of Criticality in Echo State Networks Through Fisher Information Maximization.

It is a widely accepted fact that the computational capability of recurrent neural networks (RNNs) is maximized on the so-called "edge of criticality." Once the network operates in this configuration, it performs efficiently on a specific application both in terms of: 1) low prediction error and 2) high short-term memory capacity. Since the behavior of recurrent networks is strongly influenced by the particular input signal driving the dynamics, a universal, application-independent method for determining the edge of criticality is still missing. In this paper, we aim at addressing this issue by proposing a theoretically motivated, unsupervised method based on Fisher information for determining the edge of criticality in RNNs. It is proved that Fisher information is maximized for (finite-size) systems operating in such critical regions. However, Fisher information is notoriously difficult to compute and requires the analytic form of the probability density function ruling the system behavior. This paper takes advantage of a recently developed nonparametric estimator of the Fisher information matrix and provides a method to determine the critical region of echo state networks (ESNs), a particular class of recurrent networks. The considered control parameters, which indirectly affect the ESN performance, are explored to identify those configurations lying on the edge of criticality and, as such, maximizing Fisher information and computational performance. Experimental results on benchmarks and real-world data demonstrate the effectiveness of the proposed method.

Estimating group size from human speech: Three's a conversation, but four's a crowd.

Much previous research has examined various aspects of auditory processing, including the localization of sounds, and the influence of lexical and indexical information on language processing. In the present set of experiments we explored the ability of listeners to estimate the number of speakers in a group solely from the information in an auditory signal. The bound on accurately estimating the number of simultaneous speakers is 3. We suggest that subitization-the ability to estimate numerosity of visual and auditory elements without explicitly counting these elements-rather than the capacity of short-term memory, may underlie this limitation. The cognitive constraint on estimating the number of simultaneous speakers may have implications for a wide variety of seemingly unrelated psychological phenomena.

КЛИНИЧЕСКИЕ ДОКАЗАТЕЛЬСТВА ЭФФЕКТИВНОСТИ БАД «ОЛЕОПРЕН НЕЙРО» В ПРОФИЛАКТИКЕ И КОМПЛЕКСНОМ ЛЕЧЕНИИ ДИСЦИРКУЛЯТОРНОЙ ЭНЦЕФАЛОПАТИИ СОСУДИСТОГО ГЕНЕЗА

Clinical trials of effectiveness and functional orientation of a special product – Oleopren Neyro dietary supplement – on a representative group of patients with dyscirculatory encephalopathy of vascular genesis of stages I – II are carried out. The product has been included in the patients’ diet along with basic therapy in a dose of one capsule twice a day during 10 days. Indexes of clinical symptoms and signs such as: general physical and mental state of the patients, headache, process of memorizing and recalling reads, initiative, attentiveness and concentration, emotional-volitional sphere, muscular tone, hypertensive syndrome, electroencephalogram (EEG), rheoencephalogram are studied along with the indexes of life quality: energy level, sensation of pain, emotional condition, sleep, social isolation, physical activity. As a result of the therapy, distinct positive dynamics of clinical disease is registered: general condition of 95 % of patients has improved. After treatment with the use of nutrition factor, short-term memory capacity has increased, the majority of patients can correctly repeat 10 words; average time for completing a task for attention concentration has decreased from 61,1 seconds before the beginning of the treatment to 43,5 seconds in the control group and 40,6 in the group of patients with dyscirculatory encephalopathy who have been taking Oleopren Neyro, on completing the therapy (Р < 0,05). The obtained research results give grounds for recommending the dietary supplement as an effective agent for enhancing body resistance to adverse effect of the environment, stressful situations, psychoemotional and physical exertions. Test product can be used in comprehensive treatment, and in order to prevent encephalopathy of different nature (residual, vascular, post-traumatic, toxical). Possible influence of nutrition factor on metabolism correction, connected with functional disorder of dolichol phosphate cycle at the cell membrane level, increased removal of dolichols from the body and promotion of their deficiency, is studied. Polypropenols as a part of dietary supplement composition hold key positions in the dolichol phosphate cycle and provide biosynthesis of glycoproteins and glucoaminoglukans, glycosylation of membrane proteins, preventing their proteolysis.

Distributed sequence memory of multidimensional inputs in recurrent networks

Recurrent neural networks (RNNs) have drawn interest from machine learning researchers because of their effectiveness at preserving past inputs for time-varying data processing tasks. To understand the success and limitations of RNNs, it is critical that we advance our analysis of their fundamental memory properties. We focus on echo state networks (ESNs), which are RNNs with simple memoryless nodes and random connectivity. In most existing analyses, the short-term memory (STM) capacity results conclude that the ESN network size must scale linearly with the input size for unstructured inputs. The main contribution of this paper is to provide general results characterizing the STM capacity for linear ESNs with multidimensional input streams when the inputs have common low-dimensional structure: sparsity in a basis or significant statistical dependence between inputs. In both cases, we show that the number of nodes in the network must scale linearly with the information rate and poly-logarithmically with the input dimension. The analysis relies on advanced applications of random matrix theory and results in explicit non-asymptotic bounds on the recovery error. Taken together, this analysis provides a significant step forward in our understanding of the STM properties in RNNs.

概率学习的两种认知过程研究

目的：在重复预测任务中，决策者倾向于根据事件发生的概率匹配他们的预测频率，该行为违背了理性决策理论的最优化假设。以往的研究结论支持了匹配概率行为的两种假说：其一是基于简单的联结学习过程，即重复成功/回避失败的策略；其二是来自于更老练的模式搜索策略，比如赌徒谬误信念。本研究尝试利用记忆辅助操纵实现对认知过程的分离。方法：招募50名大学生，在重复预测任务中增加动态窗口反馈，更新近期出现的事件，窗口容量设置为3和9两个条件(各25人)。结果：1) 对连续事件敏感的行为模式表现出正近因效应(倾向于重复最近一次事件)和负近因(倾向于预测相反事件)的共存；2) 与低容量条件相比，高容量条件下负近因效应持续的时间(试次数)更长；3) 随着实验的进行，负近因效应逐渐被正近因所取代。结论：本研究采用新的实验操纵手段，为分离概率学习的认知过程提供了方法上的改良，为匹配概率行为的两种假说提供了直接的证据。 Probability matching is a classical behavioral anomaly observed in lab and field studies. When asked to make predictions of two mutually exclusive random events from Bernoulli process re-peatedly, people tend to match their predictive frequencies to observed event frequencies, which violate maximization assumption in rational decision theory. Previous studies suggest there are two independent psychological processes that lead to this behavior: Associative learning, pattern searching. Previous researchers’ attempts to distinguishing these two processes are failed because of the confounding of latent variables. Our study tried to use a cognitive auxiliary procedure, a dynamic feedback window, to extend short-term memory capacity of recent events. By manipulating the length of this window (at the level of 3 and 9), we can separate cognitive process of probability learning. The results showed that: First, by checking how responses are sensitive to streaks/runs of events, we find that the recency curve showed a complex wavy form: A mixture of the positive and negative recency effect. Secondly, as subjects gained experiences, negative part of the curve is gradually replaced by the positive effect, suggesting that the process of pattern searching is overturned a process of associative learning process. Third, the pattern of recency curve also changed when window length is increased (from 3 to 9): at the high-probability-event end of the curve, the shifting from decreasing to increasing occurred early in the condition of 3, but latter in the condition of 9; but at the low-probability-event end, the opposite is true. This result implies that the process of searching patterns may embed in the strategies of encoding and inferencing of streaks of events, which are sensitive to task situations. In conclusion, by using a dynamic feedback design to manipulate short-term memory, our studies separated cognitive process during probability learning, provided new evidence to associative learning and pattern searching hypothesis of probability learning. These are both meaningful from theoretical and methodological views.

Separate Serial Order Short-term Memory Systems: A Case Series Approach

Separate Serial Order Short-term Memory Systems: A Case Series Approach

Arithmetic Training Does Not Improve Approximate Number System Acuity.

The approximate number system (ANS) is thought to support non-symbolic representations of numerical magnitudes in humans. Recently much debate has focused on the causal direction for an observed relation between ANS acuity and arithmetic fluency. Here we investigate if arithmetic training can improve ANS acuity. We show with an experimental training study consisting of six 45-min training sessions that although feedback during arithmetic training improves arithmetic performance substantially, it does not influence ANS acuity. Hence, we find no support for a causal link where symbolic arithmetic training influences ANS acuity. Further, although short-term number memory is likely involved in arithmetic tasks we did not find that short-term memory capacity for numbers, measured by a digit-span test, was effected by arithmetic training. This suggests that the improvement in arithmetic fluency may have occurred independent of short-term memory efficiency, but rather due to long-term memory processes and/or mental calculation strategy development. The theoretical implications of these findings are discussed.

Neuro-cognitive mechanisms of simultanagnosia in patients with posterior cortical atrophy.

Posterior cortical atrophy is dominated by progressive degradation of parieto-occipital grey and white matter, and represents in most cases a variant of Alzheimer's disease. Patients with posterior cortical atrophy are characterized by increasing higher visual and visuo-spatial impairments. In particular, a key symptom of posterior cortical atrophy is simultanagnosia i.e. the inability to perceive multiple visual objects at the same time. Two neuro-cognitive mechanisms have been suggested to underlie simultanagnosia, either reduced visual short-term memory capacity or decreased visual processing speed possibly resulting from white matter impairments over and above damage to cortical brain areas. To test these distinct hypotheses, we investigated a group of 12 patients suffering from posterior cortical atrophy with homogenous lesion sides in parieto-occipital cortices and varying severity of grey and white matter loss. More specifically, we (i) tested whether impaired short-term memory capacity or processing speed underlie symptoms of simultanagnosia; (ii) assessed the link to grey and white matter damage; and (iii) integrated those findings into a neuro-cognitive model of simultanagnosia in patients with posterior cortical atrophy. To this end, simultaneous perception of multiple visual objects was tested in patients with posterior cortical atrophy mostly with positive Alzheimer's disease biomarkers and healthy age-matched controls. Critical outcome measures were identification of overlapping relative to non-overlapping figures and visuo-spatial performance in tests sensitive to simultanagnosia. Using whole report of briefly presented letter arrays based on the mathematically formulated 'Theory of Visual Attention', we furthermore quantified parameters of visual short-term memory capacity and visual processing speed. Grey and white matter atrophy was assessed by voxel-based morphometry analyses of structural magnetic resonance data. All patients showed severe deficits of simultaneous perception. Compared to controls, we observed a specific slowing of visual processing speed, while visual short-term memory capacity was preserved. In a regression analysis, processing speed was identified as the only significant predictor of simultaneous perception deficits that explained a high degree of variance (70-82%) across simultanagnosia tasks. More severe slowing was also indicative for more severe impairments in reading and scene comprehension. Voxel-based morphometry yielded extensive reductions of grey and white matter in parieto-occipital and thalamic brain areas. Importantly, the degree of individual atrophy of white matter in left superior parietal lobe, but not of any grey matter region, was associated with processing speed. Based on these findings, we propose that atrophy of white matter commonly observed in posterior cortical atrophy leads to slowing of visual processing speed, which underlies the overt clinical symptoms of simultanagnosia.

Training echo state networks for rotation-invariant bone marrow cell classification

The main principle of diagnostic pathology is the reliable interpretation of individual cells in context of the tissue architecture. Especially a confident examination of bone marrow specimen is dependent on a valid classification of myeloid cells. In this work, we propose a novel rotation-invariant learning scheme for multi-class echo state networks (ESNs), which achieves very high performance in automated bone marrow cell classification. Based on representing static images as temporal sequence of rotations, we show how ESNs robustly recognize cells of arbitrary rotations by taking advantage of their short-term memory capacity. The performance of our approach is compared to a classification random forest that learns rotation-invariance in a conventional way by exhaustively training on multiple rotations of individual samples. The methods were evaluated on a human bone marrow image database consisting of granulopoietic and erythropoietic cells in different maturation stages. Our ESN approach to cell classification does not rely on segmentation of cells or manual feature extraction and can therefore directly be applied to image data.

Benefits of simultaneous bilateral cochlear implantation on verbal reasoning skills in prelingually deaf children

BackgroundImpaired auditory speech perception abilities in deaf children with hearing aids compromised their verbal intelligence enormously. The availability of unilateral cochlear implantation (CI) auditory speech perception and spoken vocabulary enabled them to reach near ageappropriate levels. This holds especially for children in spoken language environments. However, speech perception in complex listening situations and the acquisition of complex verbal skills remains difficult. Bilateral CI was expected to enhance the acquisition of verbal intelligence by improved understanding of speech in noise. MethodsThis study examined the effect of bilateral CI on verbal intelligence of 49 deaf children (3;5–8;0 years). Relations between speech perception in noise, auditory short-term memory and verbal intelligence were analysed with multiple linear regressions. In addition, the interaction of educational setting, mainstream or special, on these relations was analysed. ResultsChildren with bilateral CI obtained higher scores on verbal intelligence. Significant associations were present between speech perception in noise, auditory short-term memory and verbal intelligence. ConclusionChildren with simultaneous bilateral CIs showed better speech perception in noise than children with unilateral CIs, which mediated by the auditory short-term memory capacity, enhanced the ability to acquire more complex verbal skills for BICI children in mainstream education.

The capacity and fidelity of visual short-term memory for objects and ensembles

The capacity and fidelity of visual short-term memory for objects and ensembles

The contribution of short-term memory capacity to reading ability in adolescents with cochlear implants

ObjectiveThis study aimed to establish the relationship between short-term memory capacity and reading skills in adolescents with cochlear implants. Methods and materialsA between-groups design compared a group of young people with cochlear implants with a group of hearing peers on measures of reading, and auditory and visual short-term memory capacity. The groups were matched for non-verbal IQ and age. The adolescents with cochlear implants were recruited from the Cochlear Implant Programme at a specialist children's hospital. The hearing participants were recruited from the same schools as those attended by the implanted adolescents. Participants were 18 cochlear implant users and 14 hearing controls, aged between 12 and 18 years. All used English as their main language and had no significant learning disability or neuro-developmental disorder.Short-term memory capacity was assessed in the auditory modality using Forward and Reverse Digit Span from the WISC IV UK, and visually using Forward and Reverse Memory from the Leiter-R. Individual word reading, reading comprehension and pseudoword decoding were assessed using the WIAT II UK. ResultsA series of ANOVAs revealed that the adolescents with cochlear implants had significantly poorer auditory short-term memory capacity and reading skills (on all measures) compared with their hearing peers. However, when Forward Digit Span was entered into the analyses as a covariate, none of the differences remained statistically significant. ConclusionsDeficits in immediate auditory memory persist into adolescence in deaf children with cochlear implants. Short-term auditory memory capacity is an important neurocognitive process in the development of reading skills after cochlear implantation in childhood that remains evident in later adolescence.

Computational analysis of memory capacity in echo state networks

Reservoir computing became very popular due to its potential for efficient design of recurrent neural networks, exploiting the computational properties of the reservoir structure. Various approaches, ranging from appropriate reservoir initialization to its optimization by training have been proposed. In this paper, we extend our previous work and focus on short-term memory capacity, introduced by Jaeger in case of echo state networks. Memory capacity has been previously shown to peak at criticality, when the network switches from a stable regime to an unstable dynamic regime. Using computational experiments with nonlinear ESNs, we systematically analyze the memory capacity from the perspective of several parameters and their relationship, namely the input and reservoir weights scaling, reservoir size and its sparsity. We also derive and test two gradient descent based orthogonalization procedures for recurrent weights matrix, which considerably increase the memory capacity, approaching the upper bound, which is equal to the reservoir size, as proved for linear reservoirs. Orthogonalization procedures are discussed in the context of existing methods and their benefit is assessed.

The attention-weighted sample-size model of visual short-term memory: Attention capture predicts resource allocation and memory load

We investigated the capacity of visual short-term memory (VSTM) in a phase discrimination task that required judgments about the configural relations between pairs of black and white features. Sewell et al. (2014) previously showed that VSTM capacity in an orientation discrimination task was well described by a sample-size model, which views VSTM as a resource comprised of a finite number of noisy stimulus samples. The model predicts the invariance of ∑i(di′)2, the sum of squared sensitivities across items, for displays of different sizes. For phase discrimination, the set-size effect significantly exceeded that predicted by the sample-size model for both simultaneously and sequentially presented stimuli. Instead, the set-size effect and the serial position curves with sequential presentation were predicted by an attention-weighted version of the sample-size model, which assumes that one of the items in the display captures attention and receives a disproportionate share of resources. The choice probabilities and response time distributions from the task were well described by a diffusion decision model in which the drift rates embodied the assumptions of the attention-weighted sample-size model.

Psycholinguistic mechanisms supporting school-age children's comprehension of spoken directions: A preliminary study

The contribution of two working memory mechanisms to school-age children's comprehension of spoken directions was examined. Sixty typically developing school-age children completed the CELF-4 (Clinical Evaluation of Language Fundamentals-4, Semel, Wiig, & Secord, 2003) concepts and following oral directions subtest and four predictor measures. Predictors included global measures of lexical and syntactic knowledge, verbal short-term memory (STM) capacity, and the updating mechanism in WM. Correlation and regression analyses were conducted. Regression analysis indicated that lexical knowledge, STM capacity, and updating accuracy jointly accounted for 27% variance in the comprehension of spoken directions as measured by the CELF-4, with receptive vocabulary contributing the most. STM capacity and updating accuracy were comparably robust in their contribution and shared mechanisms that accounted for significant variance in the criterion. The importance of understanding the relation between cognitive and language processes is highlighted. The limitations of the study and methodological considerations for research in children with developmental language impairment are discussed.

Something to talk about: are conversation sizes constrained by mental modeling abilities?

Conversations are ubiquitous and central elements of daily life. Yet a fundamental feature of conversation remains a mystery: It is genuinely difficult to maintain an everyday conversation with more than four speakers. Why? We introduce a “mentalizing explanation” for the conversation size constraint, which suggests that humans have a natural limit on their ability to model the minds of others, and that this limit, in turn, shapes the sizes of everyday conversations. Using established methodologies for investigating conversation size, we pit this mentalizing hypothesis against two competing explanations—that the size of a conversation is limited by a short-term memory capacity (limiting the factual information we process) or by an auditory constraint (speakers need to be able to hear what each other are saying)—in conversations drawn from a real-world college campus and from Shakespearean plays. Our results provide support for the mentalizing hypothesis and also render alternative accounts less plausible.