Complex Span Tasks Research Articles

Aiding the search: Examining individual differences in multiply-constrained problem solving

Understanding and resolving complex problems is of vital importance in daily life. Problems can be defined by the limitations they place on the problem solver. Multiply-constrained problems are traditionally examined with the compound remote associates task (CRAT). Performance on the CRAT is partially dependent on an individual's working memory capacity (WMC). These findings suggest that executive processes are critical for problem solving and that there are reliable individual differences in multiply-constrained problem solving abilities. The goals of the current study are to replicate and further elucidate the relation between WMC and CRAT performance. To achieve these goals, we manipulated preexposure to CRAT solutions and measured WMC with complex-span tasks. In Experiment 1, we report evidence that preexposure to CRAT solutions improved problem solving accuracy, WMC was correlated with problem solving accuracy, and that WMC did not moderate the effect of preexposure on problem solving accuracy. In Experiment 2, we preexposed participants to correct and incorrect solutions. We replicated Experiment 1 and found that WMC moderates the effect of exposure to CRAT solutions such that high WMC participants benefit more from preexposure to correct solutions than low WMC (although low WMC participants have preexposure benefits as well). Broadly, these results are consistent with theories of working memory and problem solving that suggest a mediating role of attention control processes.

Neural mechanisms of two different verbal working memory tasks: A VLSM study

Currently, a distributed bilateral network of frontal-parietal areas is regarded as the neural substrate of working memory (WM), with the verbal WM network being more left-lateralized. This conclusion is based primarily on functional magnetic resonance imaging (fMRI) data that provides correlational evidence for brain regions involved in a task. However, fMRI cannot differentiate the areas that are fundamentally required for performing a task. These data can only come from brain-injured individuals who fail the task after the loss of specific brain areas. In addition to the lack of complimentary data, is the issue of the variety in the WM tasks used to assess verbal WM. When different tasks are assumed to measure the same behavior, this may mask the contributions of different brain regions. Here, we investigated the neural substrate of WM by using voxel-based lesion symptom mapping (VLSM) in 49 individuals with stroke-induced left hemisphere brain injuries. These participants completed two different verbal WM tasks: complex listening span and a word 2-back task. Behavioral results indicated that the two tasks were only slightly related, while the VLSM analysis revealed different critical regions associated with each task. Specifically, significant detriments in performance on the complex span task were found with lesions in the inferior frontal gyrus, while for the 2-back task, significant deficits were seen after injury to the superior and middle temporal gyri. Thus, the two tasks depend on the structural integrity of different, non-overlapping frontal and temporal brain regions, suggesting distinct neural and cognitive mechanisms triggered by the two tasks: rehearsal and cue-dependent selection in the complex span task, versus updating/auditory recognition in the 2-back task. These findings call into question the common practice of using these two tasks interchangeably in verbal WM research and undermine the legitimacy of aggregating data from studies with different WM tasks. Thus, the present study points out the importance of lesion studies in complementing functional neuroimaging findings and highlights the need to consider task demands in neuroimaging and neuropsychological investigations of WM.

Working memory cannot regulate overt emotional capture

Individual differences in working memory capacity partly arise from variability in attention control, a process influenced by negative emotional content. Thus, individual differences in working memory capacity should predict differences in the ability to regulate attention in emotional contexts. To address this hypothesis, a complex-span working memory task was modified so that negative arousing images or neutral images subtended the background during the encoding phase. Across three experiments, negative arousing images impaired working memory encoding relative to neutral images, resulting in impoverished symmetry span scores. Contrary to the primary hypothesis, individual differences in working memory capacity derived from three complex span tasks failed to moderate the effect of negative arousing images on working memory encoding across two large scale studies. Additionally, in Experiment 3, both negative and arousing images captured attention and were processed despite their incongruence with task goals which led to increased memory for the images in a subsequent recognition task. Implications for theories of working memory and attention control in emotional contexts will be discussed.

Measuring working memory in the spanish population: Validation of a multiple shortened complex span task.

Working memory plays a key role in cognition as it is a major predictor of a wide range of higher order abilities and behaviors typical to daily life. Shorter versions of the complex span tasks (CSTs) have been recently developed, allowing for the reduction of test administration time without affecting validity and reliability in the measurement of working memory capacity (WMC). However, these short versions have not been validated for the Spanish-speaking population. The present work aimed to validate an English version of the shortened CSTs into Spanish in a sample of 325 university students (40% female; mean age = 21.04; SD = 2.80). Cronbach's coefficient alpha was computed for each complex span task as an index of internal consistency. Validity evidence was evaluated by comparing participants' scores on the three shortened complex span tasks (operation span, symmetry span, and rotation span) with two measures of reasoning ability (Raven's Advanced Progressive Matrices and Number Series) and using confirmatory factor analysis. Results indicated that the short version of the Spanish complex span has satisfying qualities for assessing WMC in a sample of university students, which is an initial step toward providing a valid and standardized method for assessing WMC in the Peninsular Spanish-speaking population. (PsycINFO Database Record

What item response theory can tell us about the complex span tasks.

Working memory capacity is an important construct in psychology because of its relationship with many higher-order cognitive abilities and psychopathologies. Working memory capacity is often measured using a type of paradigm known as complex span. Some recent work has focused on shortening the administration time of the complex span tasks, resulting in different versions of these tasks being used (Foster et al., 2015; Oswald, McAbee, Redick, & Hambrick, 2015). Variations in the complex span tasks, such as the number of set sizes, can lead to varying power to discriminate individuals at different ability levels. Thus, research findings may be inconsistent across populations due to differing appropriateness for the ability levels. The present study uses a combination of item response theory and correlational analyses to better understand the psychometric properties of the operation span, symmetry span, and rotation span. The findings show that the typical administration of these tasks, particularly the operation span, is not suitable for above average ability samples (Study 1; n = 573). When larger set sizes are added to the tasks (Study 2; n = 351), predictive validity and discriminability is improved for all complex span tasks, however the operation span is still inferior to the spatial tasks. The authors make several conclusions about which tasks and set sizes should be used depending on the intended population, and further suggest avoiding the standard-length operation span for average or higher ability populations. (PsycINFO Database Record

On the sources of forgetting in working memory: The test of competing hypotheses.

Whether forgetting from working memory (WM) is only due to interference or is also caused by temporal decay is still a matter of debate. In the present study, this question was examined using complex span tasks in which each memory item was followed by a series of processing episodes, the duration and number of which were varied. It is known that recall performance in these tasks depends on the cognitive load ( CL) of concurrent processing conceived as the ratio between processing time and free time, higher CL resulting in lower spans. The decay-and-refresh hypothesis accounts for this effect by assuming that memory traces decay during processing but are refreshed during free time. This hypothesis predicts lower recall performance with longer processing episodes, but no effect of their number as long as CL remains constant. The interference-only hypothesis supposes that free time is used to alleviate the interference created by processing distractors. This hypothesis is potentially compatible with an effect of the duration of processing episodes through increased interference, but predicts a detrimental effect of their number. In three experiments, the recall pattern fitted the predictions of the decay-and-refresh hypothesis for verbal WM, but that of the interference-only hypothesis for visuospatial WM. Although the entire pattern of data is more easily accommodated by the decay-and-refresh hypothesis than by its interference-only contender, our results suggest that it is unwise to aim at identifying a unique source to a complex phenomenon like WM forgetting.

Training Change Detection Leads to Substantial Task-Specific Improvement

Previous research has demonstrated that adaptive training of working memory can substantially increase performance on the trained task. Such training effects have been reported for performance on simple span tasks, complex span tasks, and n-back tasks. Another task that has become a popular vehicle for studying working memory is the change-detection paradigm. In a typical change-detection trial, one has to determine whether a set of stimuli is identical to a set that was presented just previously. Here, we developed an adaptive training regimen comprised of increasingly difficult change-detection trials to assess the degree to which individuals’ change-detection performance can be improved with practice. In contrast to previous work, our results demonstrate that participants are able to dramatically improve their performance in change detection over the course of 10 training sessions. We attribute this improvement to the current training method that adaptively adjusted the set size of the change-detection task to the proficiency of the trainee. Despite these considerable training effects, an exploratory investigation revealed that these improvements remained highly task specific and may not generalize to untrained tasks.

Auditory and cognitive performance in elderly musicians and nonmusicians.

Musicians represent a model for examining brain and behavioral plasticity in terms of cognitive and auditory profile, but few studies have investigated whether elderly musicians have better auditory and cognitive abilities than nonmusicians. The aim of the present study was to examine whether being a professional musician attenuates the normal age-related changes in hearing and cognition. Elderly musicians still active in their profession were compared with nonmusicians on auditory performance (absolute threshold, frequency intensity, duration and spectral shape discrimination, gap and sinusoidal amplitude-modulation detection), and on simple (short-term memory) and more complex and higher-order (working memory [WM] and visuospatial abilities) cognitive tasks. The sample consisted of adults at least 65 years of age. The results showed that older musicians had similar absolute thresholds but better supra-threshold discrimination abilities than nonmusicians in four of the six auditory tasks administered. They also had a better WM performance, and stronger visuospatial abilities than nonmusicians. No differences were found between the two groups’ short-term memory. Frequency discrimination and gap detection for the auditory measures, and WM complex span tasks and one of the visuospatial tasks for the cognitive ones proved to be very good classifiers of the musicians. These findings suggest that life-long music training may be associated with enhanced auditory and cognitive performance, including complex cognitive skills, in advanced age. However, whether this music training represents a protective factor or not needs further investigation.

Working Memory and Speech Comprehension in Older Adults With Hearing Impairment.

This study examined the relationship between working memory (WM) and speech comprehension in older adults with hearing impairment (HI). It was hypothesized that WM would explain significant variance in speech comprehension measured in multitalker babble (MTB). Twenty-four older (59-73 years) adults with sensorineural HI participated. WM capacity (WMC) was measured using 3 complex span tasks. Speech comprehension was assessed using multiple passages, and speech identification ability was measured using recall of sentence final-word and key words. Speech measures were performed in quiet and in the presence of MTB at + 5 dB signal-to-noise ratio. Results suggested that participants' speech identification was poorer in MTB, but their ability to comprehend discourse in MTB was at least as good as in quiet. WMC did not explain significant variance in speech comprehension before and after controlling for age and audibility. However, WMC explained significant variance in low-context sentence key words identification in MTB. These results suggest that WMC plays an important role in identifying low-context sentences in MTB, but not when comprehending semantically rich discourse passages. In general, data did not support individual variability in WMC as a factor that predicts speech comprehension ability in older adults with HI.

N-back versus Complex Span Working Memory Training.

Working memory (WM) is the ability to maintain and manipulate task-relevant information in the absence of sensory input. While its improvement through training is of great interest, the degree to which WM training transfers to untrained WM tasks (near transfer) and other untrained cognitive skills (far transfer) remains debated and the mechanism(s) underlying transfer are unclear. Here we hypothesized that a critical feature of dual n-back training is its reliance on maintaining relational information in WM. In Experiment 1, using an individual differences approach, we found evidence that performance on an n-back task was predicted by performance on a measure of relational WM (i.e., WM for vertical spatial relationships independent of absolute spatial locations); whereas the same was not true for a complex span WM task. In Experiment 2, we tested the idea that reliance on relational WM is critical to produce transfer from n-back but not complex span task training. Participants completed adaptive training on either a dual n-back task, a symmetry span task, or on a non-WM active control task. We found evidence of near transfer for the dual n-back group; however, far transfer to a measure of fluid intelligence did not emerge. Recording EEG during a separate WM transfer task, we examined group-specific, training-related changes in alpha power, which are proposed to be sensitive to WM demands and top-down modulation of WM. Results indicated that the dual n-back group showed significantly greater frontal alpha power after training compared to before training, more so than both other groups. However, we found no evidence of improvement on measures of relational WM for the dual n-back group, suggesting that near transfer may not be dependent on relational WM. These results suggest that dual n-back and complex span task training may differ in their effectiveness to elicit near transfer as well as in the underlying neural changes they facilitate.

The fate of distractors in working memory: No evidence for their active removal

Not all the information processed in working memory (WM) must be retained. Due to the strict limitations of its capacity, the mechanisms that prevent WM from being cluttered and choked by no longer relevant information are of paramount importance. The present study tested the hypothesis put forward by the SOB-CS model of an active and attention-demanding mechanism that would remove no-longer relevant items from WM. Such a mechanism has been advocated to account for the well-known fact that, in complex span tasks, processing distractors at a slower pace results in better recall of memory items. According to the SOB-CS model, slow pace would free more time for removing distractors, thus alleviating the interference they create on target items. In direct contradiction with this hypothesis, a first experiment demonstrated that distractors are not less, but more accessible at the end of complex span task trials in which they have been processed at a slow rather than a fast pace. Using the repetition priming effect occurring in a lexical decision task inserted as processing component within a complex span task, a second experiment established that distractors processed at a slower pace do not elicit weaker, but stronger repetition priming effects, indicating that they have not been removed. Along with previous findings, the present study not only shows that there is no trace of distractor removal in the long term, in the short term, nor immediately after processing, but demonstrates that memory traces of distractors are stronger in situations assumed to involve a more complete removal by the SOB-CS model. These empirical evidence suggests that distractors are not actively removed from working memory after having been processed.

Dynamic range of frontoparietal functional modulation is associated with working memory capacity limitations in older adults

Older adults tend to over-activate regions throughout frontoparietal cortices and exhibit a reduced range of functional modulation during WM task performance compared to younger adults. While recent evidence suggests that reduced functional modulation is associated with poorer task performance, it remains unclear whether reduced range of modulation is indicative of general WM capacity-limitations. In the current study, we examined whether the range of functional modulation observed over multiple levels of WM task difficulty (N-Back) predicts in-scanner task performance and out-of-scanner psychometric estimates of WM capacity. Within our sample (60–77years of age), age was negatively associated with frontoparietal modulation range. Individuals with greater modulation range exhibited more accurate N-Back performance. In addition, despite a lack of significant relationships between N-Back and complex span task performance, range of frontoparietal modulation during the N-Back significantly predicted domain-general estimates of WM capacity. Consistent with previous cross-sectional findings, older individuals with less modulation range exhibited greater activation at the lowest level of task difficulty but less activation at the highest levels of task difficulty. Our results are largely consistent with existing theories of neurocognitive aging (e.g. CRUNCH) but focus attention on dynamic range of functional modulation asa novel marker of WM capacity-limitations in older adults.

Time to process information in working memory improves episodic memory

Abstract In simple-span tasks, participants encode items sequentially for immediate serial recall. Complex-span tasks are similar, except that items are interleaved with a distraction task. Whereas immediate memory is higher in simple than complex span, in tests of episodic long-term memory, better recall for words studied in complex than simple span has been observed (McCabe, 2008). This McCabe effect has been explained by assuming that distraction displace items from working memory, forcing people to covertly retrieve items after each distraction, thereby generating better episodic retrieval-cues than during simple span. Our experiments support an alternative hypothesis: individual words are attended to and processed longer in working memory in complex-span than in simple-span trials. We reduced the presentation rate of words in simple span, creating a “slow span” condition. Across four experiments, slow span improved episodic memory compared to simple span, and this benefit was larger than the McCabe effect.

The Development of Reading and Operation Span Tasks in Persian as Measures of Working Memory Capacity for Iranian EFL Learners

This paper presented two complex span tasks in Persian as measures of working memory capacity (WMC). Firstly, the construct of working memory (WM) and possible WM measures that could assess this construct efficiently were critically reviewed. Accordingly, as measures of domain-general components of WM, a reading span task and an operation span task which were documented to assess this construct efficiently were chosen and developed. Following this, the developed tasks were conducted on 151 teenage learners in a foreign language institute in West Azerbaijan Province. Then, the administration and scoring of the measures were described step by step. The tasks were validated against each other as well as against a digit span task which assessed the domain-specific aspect of WMC as well. The result showed a strong correlation between the reading span task and the operation span task, and a moderate correlation of either of the functions with the digit span task. Consequently, both of the developed span tasks can be valid indicators of WM capacity for Iranian individuals and can be used in a wide array of research domains in second language acquisition studies.

Measuring working memory capacity in children using adaptive tasks: Example validation of an adaptive complex span.

Working memory tasks designed for children usually present trials in order of ascending difficulty, with testing discontinued when the child fails a particular level. Unfortunately, this procedure comes with a number of issues, such as decreased engagement from high-ability children, vulnerability of the scores to temporary mind-wandering, and large between-subjects variations in number of trials, testing time, and proactive interference. To circumvent these problems, the goal of the present study was to demonstrate the feasibility of assessing working memory using an adaptive testing procedure. The principle of adaptive testing is to dynamically adjust the level of difficulty as the task progresses to match the participant's ability. We used this method to develop an adaptive complex span task (the ACCES) comprising verbal and visuo-spatial subtests. The task presents a fixed number of trials to all participants, allows for partial credit scoring, and can be used with children regardless of ability level. The ACCES demonstrated satisfying psychometric properties in a sample of 268 children aged 8-13 years, confirming the feasibility of using adaptive tasks to measure working memory capacity in children. A free-to-use implementation of the ACCES is provided.

Relating verbal and non-verbal auditory spans to language comprehension performance

Working memory capacity has often been assessed by various forms of the span task (e.g., reading span, digit span, etc.). Simple span tasks involve storage, whereas complex span tasks involve both storage and processing, and can include verbal and/or non-verbal stimuli. Arguably, daily activities, such as engaging in conversation or understanding a news article, require more storage and processing than recalling a list of numbers. The objective of this study was to determine the relationship of verbal and non-verbal auditory spans to language comprehension performance. Twenty-two normal-hearing adults participated in the study consisting of the following four experiments: forward and reverse digit span, Working Memory Span Task, Pitch Pattern Span Task, and the LISN (Lecture, Interview, and Spoken Narratives) listening comprehension task. Results revealed no significant relationship between non-verbal spans and language comprehension. Also, there was no significant relationship between forward and reverse digit spans to language comprehension. There was a significant correlation between the working memory span task and language comprehension. This suggests that complex language-based tasks that require more storage and processing will be better predictors of language comprehension than simple span tasks or tasks that do not involve language.

Short-Term Storage and Executive Working Memory Processing Predict Fluid Intelligence in Primary School Children.

Working memory (WM) includes short-term storage and executive processing of information. WM has been suggested to be one of the key concepts to explain individual differences in fluid intelligence (Gf). However, only a few studies have investigated the association of the two different aspects of WM in relation to Gf. Furthermore, even fewer studies have included children. Therefore, we first investigated the inter-relations between the WM aspects (verbal and visual-spatial storage, verbal and visual-spatial executive processing). Second, we explored the relation between a general WM factor and Gf. Third, we analyzed the relations between the different WM aspects and Gf while we controlled for common variance among all WM tasks. Nine- to 11-year olds had to solve simple and complex span tasks. Correlations and structural equation modeling techniques were used to examine these relations. Most inter-relations among simple and complex spans were found to be substantial and positive. The general WM factor was related to Gf. Furthermore, after controlling for common variance among all WM tasks, individual differences in verbal storage, visual-spatial storage and verbal processing still uniquely related to Gf. Visual-spatial processing, however, was not related to Gf. Results are discussed in terms of underlying mechanisms.

What is the time course of working memory attentional refreshing?

One way of maintaining information in working memory is through attentional refreshing, a process that was recently shown to be independent from verbal rehearsal. In the classical working memory complex span task, the usual assumption is that memoranda are refreshed in a cumulative fashion, starting from the first item, going in a forward order until the latest one, and cycling until there is no time to continue the process. However, there is no evidence that refreshing operates in that way. The present study proposes a computational modelling study, which constitutes a powerful method to investigate alternative hypotheses. Different refreshing schedules are investigated within computational implementation of the time-based resource sharing model. Their ability to fit three sets of behavioral data and to reproduce the major time-based resource sharing predictions were evaluated using standard model selection criteria. Besides an already published schedule in which the attentional focus is expanded, it appeared that one schedule, the least-activated-first, outperforms the classical cumulative one. The memory trace refreshed at a given time is the one that is the least activated in working memory at that time. These findings characterized the time course of attentional refreshing in working memory and specified the contribution of refreshing to primacy and recency effects. Moreover, in the light of various fields of cognitive psychology, we propose that such refreshing schedules can operate without a homunculus within a general framework including cognitive control and strategic considerations.

What is working memory capacity? / ¿Qué es la capacidad de la memoria de trabajo?

The question ‘what is working memory capacity?’ can be approached from the individual-differences and the experimental perspective. The first part of the article reviews individual-differences research that aims to determine the source of common variance among tests of working memory and related complex cognitive activities, such as reasoning and text comprehension. I propose that the ability to build, maintain and update temporary bindings between content and context representations underlies the shared variance of these variables. Multiple bindings must be maintained simultaneously for building new structural representations that underlie reasoning and language comprehension. Interference between these bindings limits the complexity of these structural representations. The second part of the article reviews experimental work, informed by computational modelling of the mechanisms of working memory. I introduce an interference-based model of working memory, SOB-CS, and review experiments with complex-span tasks that test predictions from that model. The experiments support the assumption that the capacity of working memory is limited by two forms of interference: interference by superposition of multiple bindings between distributed representations, and interference by confusion of similar items, and of items bound to similar contexts.

The association of context-specific sitting time and physical activity intensity to working memory capacity and academic achievement in young adults.

To examine combined associations between self-reported context-specific sitting time (ST) and physical activity (PA) with working memory capacity (WMC) and academic achievement in a sample of Spanish adults. Undergraduate students (n = 371; 21 years ± 3 years, 44% female) were recruited from University of Vic-Central University of Catalonia. Participants completed a 54-item survey that assessed socio-demographic variables (e.g. age, gender, academic year), min/week of light (LPA), moderate (MPA) and vigorous (VPA) intensity PA (International Physical Activity Questionnaire), min/day of domain-specific ST (Last 7 days sedentary behavior questionnaire) and academic performance (grade point average). WMC was assessed through a multiple complex span task that included: Operation Span, Symmetry Span and Rotation Span. These tasks interleave a processing task with a short list of to-be-remembered items. General linear models-adjusted by PA, ST and gender-assessed combined associations between ST and PA with WMC and academic achievement. Performing more than 3 h/week of MPA was related to increases in WMC (P < 0.001). However, PA was not associated with academic performance. More than 3 h seated on a weekend day while performing non-screen leisure activities were related to reduced WMC after adjusting for PA (P = 0.012). Similarly, >3 h/weekday spent seated in these sedentary activities or in leisure-forms of screen time were inversely associated with academic performance regardless of PA (P = 0.033; P = 0.048). MPA may benefit working memory; however, specific domains of leisure-time sedentary behavior may have an unfavorable influence on working memory and academic performance regardless of time spent in PA.