How does the severity of a learning disability affect working memory performance?

Working memory performance was examined in children aged 11-12 years who had borderline, mild, and moderate learning disabilities. Comparisons with children of average abilities were used to determine whether those with more severe learning disabilities had greater impairments in working memory. Seven measures of working memory span were used to assess temporary phonological short-term storage (digit span, word span), temporary visuo-spatial short-term storage (pattern span, spatial span), and temporary short-term storage with additional processing, or central executive, demands (listening span. odd one out span, reverse digit span). Children with mild and moderate learning disabilities were impaired on all measures of working memory compared to children of average abilities. Children with borderline learning disabilities were just as good as children with average abilities on visuo-spatial and complex span tasks, but showed an impairment on phonological span tasks. Children with moderate learning disabilities were indistinguishable from children with mild learning disabilities on simple span tasks, but were significantly poorer than the mild group on the more demanding complex span tasks. For the group as a whole, working memory was strongly related to mental age.     

How does the severity of a learning disability affect working memory performance?

Working memory performance was examined in children aged 11-12 years who had borderline, mild, and moderate learning disabilities. Comparisons with children of average abilities were used to determine whether those with more severe learning disabilities had greater impairments in working memory. Seven measures of working memory span were used to assess temporary phonological short-term storage (digit span, word span), temporary visuo-spatial short-term storage (pattern span, spatial span), and temporary short-term storage with additional processing, or central executive, demands (listening span, odd one out span, reverse digit span). Children with mild and moderate learning disabilities were impaired on all measures of working memory compared to children of average abilities. Children with borderline learning disabilities were just as good as children with average abilities on visuo-spatial and complex span tasks, but showed an impairment on phonological span tasks. Children with moderate learning disabilities were indistinguishable from children with mild learning disabilities on simple span tasks, but were significantly poorer than the mild group on the more demanding complex span tasks. For the group as a whole, working memory was strongly related to mental age.     

Measurements of auditory-verbal STM span in aphasia: effects of item, task, and lexical impairment

In the first part of this study, we investigated effects of item and task type on span performance in a group of aphasic individuals with word processing and STM deficits. Group analyses revealed significant effects of item on span performance with span being greater for digits than for words. We also investigated associations between subjects' lexical-semantic and phonological processing abilities and performance on four measures of verbal span (digit and word span, each varied for type of response, verbal vs. pointing) as well as one measure of nonverbal span. We predicted and found that the patterns of association between verbal span tasks and lexical abilities reflected the integrity of language processes and representations deployed in each paradigm used to assess span. Performance on the pointing span task, which engages both lexical-semantic and phonological processes, correlated with measures of both lexical-semantic and phonological abilities. Performance on repetition span, which engages primarily input and output phonological processes, correlated with measures of phonological abilities but not measures of lexical-semantic abilities. However, when partial correlations were performed for two subject groups based on their relative preservation of lexical-semantic ability (less or more than phonological ability), repetition span correlated with lexical-semantic measures only in the subgroup with relatively impaired lexical-semantics. Additionally, performance on the nonverbal span task correlated with measures of phonological abilities, suggesting either a general cognitive deficit affecting verbal and nonverbal STM or possibly, the use of a verbal strategy to perform this task. Our discussion focuses on the interpretation of span measurements in clinical practice and research, as well as the implications of these data for theories of short-term memory and word processing.     

On the division of short-term and working memory: an examination of simple and complex span and their relation to higher order abilities

Research has suggested that short-term memory and working memory (as measured by simple and complex span tasks, respectively) are separate constructs that are differentially related to higher order cognitive abilities. This claim is critically evaluated by reviewing research that has compared simple and complex span tasks in both experimental and correlational studies. In addition, a meta-analysis and re-analyses of key data sets were conducted. The review and analyses suggest that simple and complex span tasks largely measure the same basic subcomponent processes (e.g., rehearsal, maintenance, updating, controlled search) but differ in the extent to which these processes operate in a particular task. These differences largely depend on the extent to which phonological processes are maximized and variability from long list lengths is present. Potential methodological, psychometric, and assessment implications are discussed and a theoretical account of the data is proposed.     

Temporal–contextual processing in working memory: Evidence from delayed cued recall and delayed free recall tests

Three experiments are reported that addressed the nature of processing in working memory by investigating patterns of delayed cued recall and free recall of items initially studied during complex and simple span tasks. In Experiment 1, items initially studied during a complex span task (i.e., operation span) were more likely to be recalled after a delay in response to temporal–contextual cues, relative to items from subspan and supraspan list lengths in a simple span task (i.e., word span). In Experiment 2, items initially studied during operation span were more likely to be recalled from neighboring serial positions during delayed free recall than were items studied during word span trials. Experiment 3 demonstrated that the number of attentional refreshing opportunities strongly predicts episodic memory performance, regardless of whether the information is presented in a spaced or massed format in a modified operation span task. The results indicate that the content–context bindings created during complex span trials reflect attentional refreshing opportunities that are used to maintain items in working memory.     

Stimulus similarity decrements in children's working memory span

Two experiments investigated the impact of the relationship between processing and storage stimuli on the working memory span task performance of children aged 7 and 9 years of age. In Experiment 1, two types of span task were administered (sentence span and operation span), and participants were required to recall either the products of the processing task (sentence-final word, arithmetic total) or a word or digit unrelated to the processing task. Experiment 2 contrasted sentence span and operation span combined with storage of either words or digits, in tasks in which the item to be remembered was not a direct product of the processing task in either condition. In both experiments, memory span was significantly greater when the items to be recalled belonged to a different stimulus category from the material that was processed, so that in sentence span tasks, number recall was superior to word recall, and in operation span tasks, word recall was superior to number recall. Explanations of these findings in terms of similarity-based interference and response competition in working memory are discussed.     

Articulatory rehearsal in Alzheimer type dementia

This study investigated the relationship between articulation rate and memory span in a sample of 21 patients with early Alzheimer type dementia (AD), comparing their performance with 21 matched controls. Memory span was measured using auditorily and visually presented digits. The AD patients were moderately impaired in both conditions. Articulation rate was measured either by requiring subjects to read lists of random digits or repeatedly count from 1 to 10. The AD patients were able to read the digits as fast as the controls but were slower in the counting task. The measures of memory span and articulation rate correlated significantly for the controls but not for the AD patients, indicating that the normal association between articulation and memory span is disrupted. These results are discussed in relation to previous results and suggest that articulatory rehearsal processes in primary memory are unimpaired at the early stages of AD.     

Children's working memory: investigating performance limitations in complex span tasks

Three experiments investigated the roles of resource-sharing and intrinsic memory demands in complex working memory span performance in 7- and 9-year-olds. In Experiment 1, the processing complexity of arithmetic operations was varied under conditions in which processing times were equivalent. Memory span did not differ as a function of processing complexity. In Experiment 2, complex memory span was assessed under three conditions designed to vary both processing and intrinsic storage demands: mental arithmetic (significant attentional demands-requires storage), odd/even judgments (significant attentional demands-no storage required), and articulatory suppression (minimal attentional demands--no storage required). The highest memory spans were found in the articulatory suppression task. Span was at an intermediate level with arithmetic processing and was lowest for processing involving odd/even judgments. This difference in memory span for processing tasks involving arithmetic processing and odd/even judgments was eliminated in Experiment 3 when the pacing requirements of the arithmetic and odd/even processing tasks were equated. The results are consistent with the view that complex memory span performance is disrupted by processing activities that divert attentional resources from storage.     

认知负荷和控制性注意对工作记忆广度任务成绩的影响

通过stroop干扰实验严格筛选被试,考察了控制性注意能力不同的被试在加工部分认知负荷不同的工作记忆广度任务中的成绩。结果表明：任务复杂性和加工速度对工作记忆广度任务成绩有重要影响,任务越复杂或加工速度越快,被试的工作记忆广度任务成绩越低;在复杂的和加工速度快的工作记忆广度任务中,控制性注意能力高的被试成绩要好于控制性注意能力低的被试,但在简单的和加工速度慢的任务中两者成绩没有显著差异。     

Recall of morphologically complex forms is affected by memory task but not dyslexia

The authors studied the effect of morphological complexity on working memory in list recall tasks with base words (boy), inflected words (boy + 's) and derived words (boy + hood) in a morphologically rich language: Finnish. Simple serial recall was compared to complex working memory tasks, combining word recall with sentence verification in 8-year-old normally reading participants, dyslexic children, and adults. The normally reading children performed better than dyslexic children on both memory tasks and a test of morphology. Base words were better recalled than morphologically complex words. Memory was better for derived than inflected words in simple but not complex span tasks. There was no interaction between word type and reading group and thus no suggestion of dyslexia being associated with specific problems to represent complex morphology in working memory. Morphological processing in working memory appeared to depend on the task.     

The impact of fear words in a secondary task on complex motor performance: a dual-task climbing study

The relationship between emotion and motor action has been previously examined using relatively simple motor tasks. However, there has been limited research using more complex physical tasks. One such complex physical task is high-angle climbing. In this experiment, we examined the performance of climbers in a dual climbing and word memory task, in which they were asked to recall fear-related or neutral words after the climb, as well as single-task performance. Climbing distance, efficiency, and word recall all significantly decreased in the dual-task conditions, relative to the single tasks. Climbing distance and efficiency also decreased in the fear word dual task, relative to the neutral word memory dual task. Subjective measures of performance indicated that climbers were aware of impaired climbing performance in the dual tasks, relative to the climbing-only condition, but that they were not aware of the increased impairment caused by the fear words. These findings have important theoretical and practical implications, particularly in occupational settings requiring climbing-like operations, such as fire-fighting and search and rescue.     

The endurance of children's working memory: a recall time analysis

We analyze the timing of recall as a source of information about children’s performance in complex working memory tasks. A group of 8-year-olds performed a traditional operation span task in which sequence length increased across trials and an operation period task in which processing requirements were extended across trials of constant sequence length. Interword pauses were longer than are commonly found in immediate serial recall tasks yet shorter than for reading span. These pauses increased with the demands of recall, decreased across the output sequence, and were to some extent predictive of scholastic ability. Overall, timing data illustrate that recall in working memory tasks involves subtle processes of item access rather than simple readout of information from an immediate store.     

The influence of levels of processing on recall from working memory and delayed recall tasks

Recent research in working memory has highlighted the similarities involved in retrieval from complex span tasks and episodic memory tasks, suggesting that these tasks are influenced by similar memory processes. In the present article, the authors manipulated the level of processing engaged when studying to-be-remembered words during a reading span task (Experiment 1) and an operation span task (Experiment 2) in order to assess the role of retrieval from secondary memory during complex span tasks. Immediate recall from both span tasks was greater for items studied under deep processing instructions compared with items studied under shallow processing instructions regardless of trial length. Recall was better for deep than for shallow levels of processing on delayed recall tests as well. These data are consistent with the primary-secondary memory framework, which suggests that to-be-remembered items are displaced from primary memory (i.e., the focus of attention) during the processing phases of complex span tasks and therefore must be retrieved from secondary memory.     

Multiple short‐term storage: A task to evaluate the coordination function of the central executive

The present paper explores one of the multiple aspects of working memory, specifically the coordinating function of the central executive with a complex double‐stimuli task. Performance on this task requires coordinating the short‐term maintenance of verbal as well as visuospatial information in preparation for recall. The task involves the single recall of words, the single recall of locations, or the recall of localized words. The study of the double‐stimuli task involves three classical interference tasks (articulatory suppression, Moar box tracking, and standing balance position) and comparing with simple span tasks (word recall and location recall). Word and location recall in this double‐stimuli task involves observing the classical interference effects: articulatory suppression impairs word recall performance without affecting location recall, whereas in visuospatial interference tasks the reverse is true. A second analysis showed that when performance on the double‐stimuli task (implying the simultaneous maintenance of verbal and visuospatial material at the same time) is compared with performances on short‐term memory tasks (classical word span or location span using the same material), a significant decrease in performance is observed. In a third analysis a score specific to the complex task was computed (corrected score). This score takes into account the recall capacity for both words and locations. This score, directly related to the capacities of coordination implied in the task, is sensitive to most attentional requirements of interference tasks. Contrary to what can be observed on location recall, the standing balance position did not significantly decrease performance. These results are consistent with an interpretation of the working memory according to which coordination of the subsystems is a function of the central executive.     

Drunk,but not blind: The effects of alcohol intoxication on change blindness

Alcohol use has long been assumed to alter cognition via attentional processes. To better understand the cognitive consequences of intoxication, the present study tested the effects of moderate intoxication (average BAC between .071 and .082) on attentional processing using complex working memory capacity (WMC) span tasks and a change blindness task. Intoxicated and sober participants were matched on baseline WMC performance, and intoxication significantly decreased performance on the complex span tasks. Surprisingly, intoxication improved performance on the change blindness task. The results are interpreted as evidence that intoxication decreases attentional control, causing either a shift towards more passive processing and/or a more diffuse attentional state. This may result in decreased performance on tasks where attentional control or focus are required, but may actually facilitate performance in some contexts.     

Examining the relationship between free recall and immediate serial recall: the effect of concurrent task performance

In 3 experiments, participants saw lists of 16 words for free recall with or without a 6-digit immediate serial recall (ISR) task after each word. Free recall was performed under standard visual silent and spoken-aloud conditions (Experiment 1), overt rehearsal conditions (Experiment 2), and fixed rehearsal conditions (Experiment 3). The authors found that in each experiment, there was no effect of ISR on the magnitude of the recency effect, but interleaved ISR disrupted free recall of those words that would otherwise be rehearsed. The authors conclude that ISR and recency cannot both be outputs from a unitary limited-capacity short-term memory store and discuss the possibility that the process of rehearsal may be common to both tasks.     

Midazolam amnesia and short-term/working memory processes

We examined whether midazolam impairs short-term/working memory processes. We hypothesize that prior dissociations in midazolam's effects on short-term/working memory tasks and episodic memory tasks arise because midazolam has a larger effect on episodic memory processes than on short-term/working memory processes. To examine these issues, .03 mg/kg of participant's bodyweight of midazolam was administered in a double-blind placebo-controlled within-participant design. Performance on the digit span and category generation/recall tasks was examined. The results of Experiment 1 demonstrated that: (1) midazolam impaired performance on the digit span task; (2) midazolam did not impair performance on the category generation task; (3) midazolam impaired performance on the category recall task; and (4) midazolam's effect on category recall was four times as large as its effect on digit span. The results of Experiment 2 demonstrated that midazolam did not impair digit span performance when the digit span task was administered at a later time. These results suggest that midazolam can impair short-term/working memory processes, but these effects are substantially smaller than midazolam's effect on episodic memory processes. Moreover, they demonstrate that conscious awareness of materials during study is not sufficient to produce episodic memory.     

Phonological similarity effects in simple and complex span tasks

Three experiments were conducted to examine the effect of phonological similarity in simple and complex memory span tasks. In Experiment 1, participants performed either a simple or a complex span task, and the memoranda within lists were either phonologically similar or distinct. Phonologically similar lists consisted of words that rhymed.The simple span task was word span. There were two complex span tasks; one was the original reading span task, and the other was a variant of reading span in which all the sentences within a list were contextually related. The classic phonological similarity decrement was observed in word span. In contrast, phonological similarity facilitation was observed in both versions of reading span. This facilitation effect was further investigated in Experiment 2 using two new versions of reading span. In Experiment 2, the sentences in reading span were either short or long, and the memoranda were presented separately from, and were unrelated to, the sentences. Again, words within phonologically similar lists rhymed, and again, facilitation was observed. In Experiment 3, phonological similarity was operationalized in terms of feature overlap, rather than rhyme. The classic phonological similarity decrement was still observed in word span, but facilitation was not observed in complex span. The results suggest that phonological similarity, when operationalized using words that rhyme, serves as a list retrieval cue and that complex span tasks are more dependent on cue-driven memory retrieval mechanisms than are simple span tasks.     

Impaired discourse gist and working memory in children after brain injury

Emerging evidence suggests that a traumatic brain injury (TBI) in childhood may disrupt the ability to abstract the central meaning or gist-based memory from connected language (discourse). The current study adopts a novel approach to elucidate the role of immediate and working memory processes in producing a cohesive and coherent gist-based text in the form of a summary in children with mild and severe TBI as compared to typically developing children, ages 8-14 years at test. Both TBI groups showed decreased performance on a summary production task as well as retrieval of specific content from a long narrative. Working memory on n-back tasks was also impaired in children with severe TBI, whereas immediate memory performance for recall of a simple word list in both TBI groups was comparable to controls. Interestingly, working memory, but not simple immediate memory for a word list, was significantly correlated with summarization ability and ability to recall discourse content.     

Differential constraints on the working memory and reading abilities of individuals with learning difficulties and typically developing children

This study examined the factors that constrain the working memory span performance and reading ability of individuals with generalized learning difficulties. In the study, 50 individuals with learning difficulties (LD) and 50 typically developing children (TD) matched for reading age completed two working memory span tasks. Participants also completed independent measures of the processing and storage operations involved in each working memory span task and Raven's Coloured Progressive Matrices. The results showed that despite an equivalent level of working memory span, the relative importance of the constraints on working memory differed between the groups. In addition, working memory span was not closely related to word recognition or sentence comprehension performance in the LD group. These results suggest that the working memory span performance of LD and TD individuals may reflect different working memory limitations and that individuals with generalized learning difficulties may approach cognitive tasks in a qualitatively different way from that of typically developing individuals.