Whichever way you choose to categorize,working memory helps you learn

There has been growing interest in the relationship between the capacity of a person's working memory and their ability to learn to categorize stimuli. While there is evidence that working memory capacity (WMC) is related to the speed of category learning, it is unknown whether WMC predicts which strategies people use when there are multiple possible solutions to a categorization problem. To explore the relationship between WMC, category learning, and categorization strategy use, 173 participants completed two categorization tasks and a battery of WMC tasks. WMC predicted the speed of category learning, but it did not predict which strategies participants chose to perform categorization. Thus, WMC does not predict which categorization strategies people use but it predicts how well they will use the strategy they select.     

Depressive thoughts limit working memory capacity in dysphoria

Dysphoria is associated with persistence of attention on mood-congruent information. Longer time attending to mood-congruent information for dysphoric individuals (DIs) detracts from goal-relevant information processing and should reduce working memory (WM) capacity. Study 1 showed that DIs and non-DIs have similar WM capacities. Study 2 embedded depressive information into a WM task. Compared to non-DIs, DIs showed significantly reduced WM capacity for goal-relevant information in this task. Study 3 replicated results from Studies 1 and 2, and further showed that DIs had a significantly greater association between processing speed and recall on the depressively modified WM task compared to non-DIs. The presence of inter-task depressive information leads to DI-related decreased WM capacity. Results suggest dysphoria-related WM capacity deficits when depressive thoughts are present. WM capacity deficits in the presence of depressive thoughts are a plausible mechanism to explain day-to-day memory and concentration difficulties associated with depressed mood.     

Happiness increases verbal and spatial working memory capacity where sadness does not: Emotion,working memory and executive control

The effects of emotion on working memory and executive control are often studied in isolation. Positive mood enhances verbal and impairs spatial working memory, whereas negative mood enhances spatial and impairs verbal working memory. Moreover, positive mood enhances executive control, whereas negative mood has little influence. We examined how emotion influences verbal and spatial working memory capacity, which requires executive control to coordinate between holding information in working memory and completing a secondary task. We predicted that positive mood would improve both verbal and spatial working memory capacity because of its influence on executive control. Positive, negative and neutral moods were induced followed by completing a verbal (Experiment 1) or spatial (Experiment 2) working memory operation span task to assess working memory capacity. Positive mood enhanced working memory capacity irrespective of the working memory domain, whereas negative mood had no influence on performance. Thus, positive mood was more successful holding information in working memory while processing task-irrelevant information, suggesting that the influence mood has on executive control supersedes the independent effects mood has on domain-specific working memory.     

A model of working memory capacity in the radial-arm maze task

The radial arm maze is one of the most commonly used tests for assessing working memory in laboratory animals. However, to date, there exists no quantitative method of estimating working memory capacity from performance on this task. Here, we present a mathematical model of performance on the radial arm maze from which we can derive estimates of capacity. We derive explicit results for the two most commonly used measures of performance as functions of number of arms in the maze and memory capacity, assuming a uniform random search. We simulate random non-uniform search strategies. Comparing our model to previous experiments, we show that our model predicts a working memory capacity in the range of 3-9 at the level of performance observed in these experiments. This estimate is within the typical estimate of human working memory capacity. Performance of rats on large mazes (e.g. 48 arms) has been used as evidence that the working memory capacity of rats may be significantly larger than that of humans. We report that memory capacity in the range 3-9 is sufficient to explain the performance of rats in very large radial mazes. Furthermore, when we simulate non-uniform random search strategies observed in the experiments, the resulting estimates do not differ significantly from those assuming a uniform random search. We conclude that a list-based model of working memory with modest capacity is more powerful than previously expected.     

Capacity,strategies, and metamemory: tests of a three-factor model of memory development

Multiple measures of three of the factors (capacity, strategies, and metamemory) hypothesized to cause improvements in memory with age were obtained from 179 children in kindergarten to second grade (younger: ages 5-8) or third and fourth grade (older: ages 8-11) during nine sessions of testing. Confirmatory factor analysis was computed separately for each age group. Results suggested that the fit of the three-factor model was statistically significantly better than a one-factor, general memory model for both age groups. However, the fit indices were borderline, and there was not sufficient evidence for a metamemory factor for younger children. The factors that influence memory performance may differ with age.     

Children's working memory: Its structure and relationship to fluid intelligence

Working memory (WM) has been predominantly studied in adults. The insights provided by these studies have led to the development of competing theories on the structure of WM and conflicting conclusions on how strongly WM components are related to higher order thinking skills such as fluid intelligence. However, it remains unclear whether and to what extent the theories and findings derived from adult data generalize to children. The purpose of the present study is therefore to investigate children's WM (N = 161), who attended classes at the end of kindergarten in Luxembourg. Specifically, we examine different structural models of WM and how its components, as defined in these models, are related to fluid intelligence. Our results indicate that short-term storage capacity primarily explains the relationship between WM and fluid intelligence. Based on these observations we discuss the theoretical and methodological issues that arise when children's WM is investigated.     

Time and resource limits on working memory: cross-age consistency in counting span performance

This longitudinal study separated resource demand effects from those of retention interval in a counting span task among 100 children tested in grade 2 and again in grades 3 and 4. A last card large counting span condition had an equivalent memory load to a last card small, but the last card large required holding the count over a longer retention interval. In all three waves of assessment, the last card large condition was found to be less accurate than the last card small. A model predicting reading comprehension showed that age was a significant predictor when entered first accounting for 26% of the variance, but counting span accounted for a further 22% of the variance. Span at Wave 1 accounted for significant unique variance at Wave 2 and at Wave 3. Results were similar for math calculation with age accounting for 31% of the variance and counting span accounting for a further 34% of the variance. Span at Wave 1 explained unique variance in math at Wave 2 and at Wave 3.     

Dissociation between appearance and location within visuo-spatial working memory

Previous research has demonstrated separation between systems supporting memory for appearance and memory for location. However, the interpretation of these results is complicated by a confound occurring because of the simultaneous presentation of objects in multiple-item arrays when assessing memory for appearance and the sequential presentation of items when assessing memory for location. This paper reports an experiment in which sequential or simultaneous modes of presentation were factorially manipulated with memory for visual appearance or memory for location. Spatial interference (tapping) or visual interference (dynamic visual noise) were presented during retention. Appearance versus location interacted with the type of interference task, but mode of presentation did not. These results are consistent with the view that different subsystems within visuo-spatial working memory support memory for appearance and memory for location.     

A Bayesian hierarchical model for the measurement of working memory capacity

Working memory is the memory system that allows for conscious storage and manipulation of information. The capacity of working memory is extremely limited. Measurements of this limit, and what affects it, are critical to understanding working memory. Cowan (2001) and Pashler (1988) suggested applying multinomial tree models to data from change detection paradigms in order to estimate working memory capacity. Both Pashler and Cowan suggested simple formulas for estimating capacity with these models. However, in many cases, these simple formulas are inadequate, and may lead to inefficient or biased estimation of working memory capacity. I propose a Bayesian hierarchical alternative to the Pashler and Cowan formulas, and show that the hierarchical model outperforms the traditional formulas. The models are easy to use and appropriate for a wide range of experimental designs. An easy-to-use graphical user interface for fitting the hierarchical model to data is available.     

Relationship between working memory capacity and contingent involuntary orienting

Individual differences in working memory capacity are related to the ability to control attention; where less working memory capacity is associated with less attentional control. A well-known demonstration of attentional control is contingent involuntary orienting (Folk, Remington, & Johnston, 1992), which is the finding that visuospatial attention is captured by a salient peripheral cue, but only if the cue is featurally similar to the target of search and not if the cue is featurally dissimilar. This control of attention and ability to resist shifting attention towards an irrelevant visual cue is believed to be moderated by attentional settings for target-specific features. This study establishes that working memory capacity is related to contingent involuntary orienting of attention. Lower working memory capacity was associated with larger stimulus-driven cueing effects at short cue-to-target onset asynchronies, than at longer asynchronies, suggesting working memory capacity was associated with the ability to control covert orienting of attention at early processing stages.     

Visual working memory is enhanced by mixed strategy use and semantic coding

Visual working memory is enhanced by processes related to verbalisation. However, the mechanism underlying this enhancement is unclear. Experiment 1 investigated the potential contribution of the phonological loop of working memory, by assessing the effects of articulatory suppression on two versions of the Visual Patterns Test—one low and one high in availability of verbal coding. The lack of interaction suggested that the phonological loop is not responsible; however, active use of combined verbal and visual strategies, as well as activated semantic knowledge, both appear to be related to increased capacity. Experiment 2 assessed the role of central executive resources. Because central executive suppression removed the benefit of the high verbal coding task version, central executive resources, assumed to relate to the temporary maintenance of multimodal codes in the episodic buffer, appear to underlie the benefit associated with verbalisation.     

Reconsidering the two-second decay hypothesis in verbal working memory

A common belief in the study of short-term memory is that the verbal trace decays around two seconds after it is encoded. This belief is typically assumed to follow from the finding that in immediate serial recall, the time required to rapidly articulate a span-length list is around two seconds. Empirically, this belief is in opposition to a broad set of findings across a number of domains that establish mean decay times to be longer than two seconds. Theoretically, the available computational and mathematical models of immediate serial recall do not address this issue directly, because they typically rely on other mechanisms in addition to decay to account for forgetting. As such, they may show that decay times can be longer than two seconds, but they fail to show that they cannot be as short as two seconds. We address the issue directly and set a lower bound on mean trace decay times, even under the limiting assumption that all forgetting is due to trace decay. We do this by presenting a simple item-based model of trace decay that allows us to estimate values of mean trace duration. For a set of words whose span-length lists can be rapidly articulated in about two seconds, the model offers a conservative estimate for their mean decay times of around four seconds. Both the experimental and theoretical evidence show that items in verbal working memory decay considerably slower than the two-second decay hypothesis claims.     

Effects of emotional content on working memory capacity

Emotional events tend to be remembered better than neutral events, but emotional states and stimuli may also interfere with cognitive processes that underlie memory performance. The current study investigated the effects of emotional content on working memory capacity (WMC), which involves both short term storage and executive attention control. We tested competing hypotheses in a preregistered experiment (N?=?297). The emotional enhancement hypothesis predicts that emotional stimuli attract attention and additional processing resources relative to neutral stimuli, thereby making it easier to encode and store emotional information in WMC. The emotional impairment hypothesis, by contrast, predicts that emotional stimuli interfere with attention control and the active maintenance of information in working memory. Participants completed a common measure of WMC (the operation span task; Turner, M. L., &; Engle, R. W. [1989]. Is working memory capacity task dependent? Journal of Memory and Language, 28, 127–154) that included either emotional or neutral words. Results revealed that WMC was reduced for emotional words relative to neutral words, consistent with the emotional impairment hypothesis.     

Misleading cues improve developmental assessment of working memory capacity: The color matching tasks

The theory of constructive operators was used as a framework to design two versions of a paradigm (color matching task, CMT) in which items are parametrically ordered in difficulty, and differ only contextually. Items in CMT-Balloon are facilitating, whereas items in CMT-Clown contain misleading cues. Participants of ages 7–14 years and adults (N = 149) were studied. We found significant model-predicted graded differences in performance between the facilitating and misleading tasks, across and within age groups, expressing age versus items’ demand interactions. Younger children were differentially affected by contextual cues. Even though both task versions were highly correlated with a well-established developmental measure of attentional capacity, CMT-Clown, which contained misleading cues, was a better measure of working memory capacity. These results show a need to estimate degree of misleadingness whenever performance levels in working memory or mental attention tasks are compared and interpreted. Developmental profiles of both tasks are discussed in terms of contextual differences and neoPiagetian stages of development.     

On the capacity of attention: its estimation and its role in working memory and cognitive aptitudes

Working memory (WM) is the set of mental processes holding limited information in a temporarily accessible state in service of cognition. We provide a theoretical framework to understand the relation between WM and aptitude measures. The WM measures that have yielded high correlations with aptitudes include separate storage-and-processing task components, on the assumption that WM involves both storage and processing. We argue that the critical aspect of successful WM measures is that rehearsal and grouping processes are prevented, allowing a clearer estimate of how many separate chunks of information the focus of attention circumscribes at once. Storage-and-processing tasks correlate with aptitudes, according to this view, largely because the processing task prevents rehearsal and grouping of items to be recalled. In a developmental study, we document that several scope-of-attention measures that do not include a separate processing component, but nevertheless prevent efficient rehearsal or grouping, also correlate well with aptitudes and with storage-and-processing measures. So does digit span in children too young to rehearse.     

The influence of temporal resolution power and working memory capacity on psychometric intelligence

According to the temporal resolution power (TRP) hypothesis, higher TRP as reflected by better performance on psychophysical timing tasks accounts for faster speed of information processing and increased efficiency of information processing leading to better performance on tests of psychometric intelligence. An alternative explanation of individual differences in psychometric intelligence highlights individual differences in working memory (WM) capacity which has been found to be closely associated with psychometric intelligence. A latent variable approach was applied on the data of 200 participants ranging in age from 18 to 30 years and spanning a large range of levels of psychometric intelligence. Functional relationships were examined among TRP, WM capacity, as well as reasoning and speed of processing as two important aspects of psychometric intelligence. As predicted by the TRP hypothesis, the relation between TRP and psychometric intelligence was mediated by WM capacity supporting the view that higher TRP leads to better coordinated mental operations which, in turn, result in higher psychometric intelligence. The results are discussed against the background that WM capacity and psychometric reasoning are hardly dissociable from each other and that the specific factors limiting WM capacity and accounting for the mediation effect need to be identified in future research.     

A working memory span task for toddlers

This study presents a new working memory measure for toddlers, inspired by the Spin-the-Pots (Hughes & Ensor, 2005), which we modified structuring it as a memory span task. As in the original task, we required toddlers to retrieve objects hidden in little boxes; however, in our Memory Span Spin-the-Pots (MSSP) we used smaller numbers of targets, and we systematically manipulated memory load, covering or not the display, and rotating it or not. Two experiments involved participants between 18 months and three years. In Experiment 1 we examined the effects of covering and rotation on toddlers’ memory. Either covering or rotating the stimuli hindered their performance, and combining both transformations yielded an under-additive interaction. Moreover, the effect of covering decreased in the second half of the procedure. In Experiment 2 we validated the MSSP as a working memory measure by comparing it with the Imitation Sorting Task (IST; Alp, 1994). We found that the MSSP correlated with the IST, also with age partialled out, although the IST was easier. In both experiments, the scores increased with age. Overall, this research sheds light on some variables that affect toddlers’ performance on the MSSP, and shows that it can be used as a valid working memory measure for toddlers. The results are discussed considering the attentional processes presumably involved.     

A cognitive approach to dogmatism: An investigation into the relationship of verbal working memory and dogmatism

This study investigated the relationship of working memory to open and closed belief systems. Two hundred college students completed a working memory span test to measure verbal working memory, and Rokeach’s Dogmatism Scale (1956). Regression analysis was undertaken to determine the contribution of verbal working memory to dogmatism. A negative correlation was found between dogmatism scores and working memory scores (p = .002) confirming the hypothesis that those participants who display a larger working memory capacity would show lower levels of dogmatic beliefs than participants displaying a smaller working memory capacity. Error analysis was employed to determine the significance of inhibition processes; indicating that capacity limits in verbal working memory, and not processing deficits, were primarily responsible for poor working memory scores. Dogmatism was not found to be related to gender, age, ethnicity, religious affiliation, academic major, or level of education.     

The phenotypic and genotypic relation between working memory speed and capacity

This study examined the phenotypic and genotypic relationship between working memory speed (WMS) and working memory capacity (WMC) in 12-year-old twins and their siblings (N = 409). To asses WMS all children performed a reaction time task with three memory loads from which a basic mental speed measure and the derived slope were used. WMC was measured with two subtests of the WISC-R, namely Arithmetic and Digit Span. The phenotypic correlations among the WMS and WMC indices were around − 0.30. Heritabilities for all variables ranged from 43% to 56%. Structural equating modelling revealed that a model with two genetic factors, representing WMS and WMC, which were correlated (− 0.54) fitted the data best, indicating that WMS and WMC are partly mediated by the same set of genes and partly by separate sets of genes. When general IQ was simultaneously analysed with the data the correlation between the genetic factors for WMS and WMC decreased (− 0.25), but was still significant. This means that  50% of the genetic correlation between WMS and WMC is explained by IQ.     

A sub-process view of working memory capacity: Evidence from effects of speech on prose memory

In this article we outline a “sub-process view” of working memory capacity (WMC). This view suggests that any relationship between WMC and another construct (e.g., reading comprehension) is actually a relationship with a specific part of the WMC construct. The parts, called sub-processes, are functionally distinct and can be measured by intrusion errors in WMC tasks. Since the sub-processes are functionally distinct, some sub-process may be related to a certain phenomenon, whereas another sub-process is related to other phenomena. In two experiments we show that a sub-process (measured by immediate/current-list intrusions) is related to the effects of speech on prose memory (semantic auditory distraction), whereas another sub-process (measured by delayed/prior-list intrusions), known for its contribution to reading comprehension, is not. In Experiment 2 we developed a new WMC task called “size-comparison span” and found that the relationship between WMC and semantic auditory distraction is actually a relationship with a sub-process measured by current-list intrusions in our new task.