The structure of working memory abilities across the adult life span

The present study addresses three questions regarding age differences in working memory: (1) whether performance on complex span tasks decreases as a function of age at a faster rate than performance on simple span tasks; (2) whether spatial working memory decreases at a faster rate than verbal working memory; and (3) whether the structure of working memory abilities is different for different age groups. Adults, ages 20-89 (n = 388), performed three simple and three complex verbal span tasks and three simple and three complex spatial memory tasks. Performance on the spatial tasks decreased at faster rates as a function of age than performance on the verbal tasks, but within each domain, performance on complex and simple span tasks decreased at the same rates. Confirmatory factor analyses revealed that domain-differentiated models yielded better fits than models involving domain-general constructs, providing further evidence of the need to distinguish verbal and spatial working memory abilities. Regardless of which domain-differentiated model was examined, and despite the faster rates of decrease in the spatial domain, age group comparisons revealed that the factor structure of working memory abilities was highly similar in younger and older adults and showed no evidence of age-related dedifferentiation.     

Working memory and interference: A comment on Jenkins, Myerson, Hale, and Fry (1999)

Jenkins, Myerson, Hale, and Fry (1999) showed that slopes relating complex spans to simple spans were considerably smaller than one, indicating that persons with higher simple spans suffered more interference when the span task was combined with a processing demand. They argued that this finding ruled out accounts of working memory based on interference and/or inhibition of interfering information. We demonstrate that the effect is mainly an artifact from regression to the mean, owing to the low reliability of span scores as used by Jenkins et al. Data from 133 young adults for two verbal and two spatial span tasks show that the slopes relating complex to simple performance are considerably higher for sum scores than for span scores. Furthermore, an adequate test for an interference or an inhibition account of working memory is to predict interference from complex span tasks, not from simple span tasks. Interference effects in the verbal span tasks were negatively correlated with an independent measure of working memory capacity, consistent with the interference/inhibition account.     

Complex span tasks, simple span tasks, and cognitive abilities: A reanalysis of key studies

There is great interest in the relationships between memory span tasks and cognitive abilities. However, the causes underlying their correlation remain unknown. In the present article, five key data sets were reanalyzed according to two criteria: They must consider complex span tasks (so-called working memory [WM] tasks) and simple span tasks (so-called short-term memory [STM] tasks), and they must comprise cognitive ability measures. The obtained results offer several points of interest. First, memory span tasks should be conceived from a hierarchical perspective: They comprise both general and specific components. Second, the general component explains about four times the variance explained by the specific components. Third, STM and WM measures are closely related. Fourth, STM and WM measures share the same common variance with cognitive abilities. Finally, the strong relationship usually found between memory span tasks and cognitive abilities could be tentatively interpreted by the component shared by STM and WM--namely, the capacity for temporarily preserving a reliable memory representation of any given information.     

The reliability and stability of verbal working memory measures

The psychometric properties of several commonly used verbal working memory measures were assessed. One hundred thirty-nine individuals in five age groups (18–30, 50–59, 60–69, 70–79, and 80+ years) were tested twice (Time I and Time II) on seven working memory span measures (alphabet span, backward digit span, missing digit span, subtract 2 span, running item span, and sentence span for syntactically simple and complex sentences), with an interval of approximately 6 weeks between testing. There were significant effects of age on all but two of the tasks. All the measures had adequate internal consistency. Correlations between performances at Time I and Time II were significant for all the tasks, other than the missing digit span task. The magnitude of the correlations was similar across the age groups and ranged from .52 to .81. Classification of subjects into discrete memory span groups on the basis of a single measure was highly inconsistent across testing sessions and tasks. Classification into upper and lower quartiles was more stable than using a cutoff score for group membership or than classification into high-, medium-, and low-span groups. Correlational analyses showed that there was a moderate relationship between performances on many of the span tasks. Confirmatory factor analysis suggested that six of the seven tasks reflected a common factor. Both test—retest reliability and stability of classification improved when a composite measure reflecting performance on several tasks was used.     

A Dissociation Between Simple and Complex Span Impairment in Alcoholics

We investigated whether the surprisingly good memory performance of alcoholics may result from simple memory performance being spared while performance in complex memory tasks is impaired. Simple word span was contrasted with a complex word span task involving concurrent monitoring and re-organisation of items for recall. To control for disruption of rehearsal in the complex word span task, performance on two additional tasks with disrupted rehearsal but no additional processing components was studied. As hypothesised, the alcoholics showed a deficit in the complex but not the simple word span task. They were also impaired, compared to controls, on both tasks with disrupted rehearsal. The difference between groups remained in the complex span task when scores in simple span and either of the two other tasks were used as covariates. Thus, both executive processes necessary for coping with disrupted rehearsal and additional processes scheduling processing and storage in a complex task may play a role in accounting for working memory deficits found in alcoholics.     

Working memory functioning in developmental dyslexia

Working memory impairments in dyslexia are well documented. However, research has mostly been limited to the phonological domain, a modality in which people with dyslexia have a range of problems. In this paper, 22 adult students with dyslexia and 22 age- and IQ-matched controls were presented with both verbal and visuospatial working memory tasks. Performance was compared on measures of simple span, complex span (requiring both storage and processing), and dynamic memory updating in the two domains. The dyslexic group had significantly lower spans than the controls on all the verbal tasks, both simple and complex, and also on the spatial complex span measure. Impairments remained on the complex span measures after controlling statistically for simple span performance, suggesting a central executive impairment in dyslexia. The novelty of task demands on the initial trials of the spatial updating task also proved more problematic for the dyslexic than control participants. The results are interpreted in terms of extant theories of dyslexia. The possibility of a supervisory attentional system deficit in dyslexia is also raised. It seems clear that working memory difficulties in dyslexia extend into adulthood, can affect performance in both the phonological and visuospatial modalities, and implicate central executive dysfunction, in addition to problems with storage.     

Working memory functioning in developmental dyslexia

Working memory impairments in dyslexia are well documented. However, research has mostly been limited to the phonological domain, a modality in which people with dyslexia have a range of problems. In this paper, 22 adult students with dyslexia and 22 age- and IQ-matched controls were presented with both verbal and visuospatial working memory tasks. Performance was compared on measures of simple span, complex span (requiring both storage and processing), and dynamic memory updating in the two domains. The dyslexic group had significantly lower spans than the controls on all the verbal tasks, both simple and complex, and also on the spatial complex span measure. Impairments remained on the complex span measures after controlling statistically for simple span performance, suggesting a central executive impairment in dyslexia. The novelty of task demands on the initial trials of the spatial updating task also proved more problematic for the dyslexic than control participants. The results are interpreted in terms of extant theories of dyslexia. The possibility of a supervisory attentional system deficit in dyslexia is also raised. It seems clear that working memory difficulties in dyslexia extend into adulthood, can affect performance in both the phonological and visuospatial modalities, and implicate central executive dysfunction, in addition to problems with storage.     

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.     

Contribution of strategy use to performance on complex and simple span tasks

Simple and complex span tasks are widely thought to measure related but separable memory constructs. Recently, however, research has demonstrated that simple and complex span tasks may tap, in part, the same construct because both similarly predict performance on measures of fluid intelligence (Gf) when the number of items retrieved from secondary memory (SM) is equated (Unsworth & Engle, Journal of Memory and Language 54:68–80 2006). Two studies (n = 105 and n = 152) evaluated whether retrieval from SM is influenced by individual differences in the use of encoding strategies during span tasks. Results demonstrated that, after equating the number of items retrieved from SM, simple and complex span performance similarly predicted Gf performance, but rates of effective strategy use did not mediate the span-Gf relationships. Moreover, at the level of individual differences, effective strategy use was more highly related to complex span performance than to simple span performance. Thus, even though individual differences in effective strategy use influenced span performance on trials that required retrieval from SM, strategic behavior at encoding cannot account for the similarities between simple and complex span tasks.     

Complex span and n-back measures of working memory: A meta-analysis

Working memory is a construct of primary relevance to many areas of psychology. Two types of tasks have been used to measure working memory, primarily in different research areas: Complex span tasks are commonly used in behavioral studies in the cognitive and individual-differences literature, whereas n-back tasks have been used more frequently in cognitive neuroscience studies investigating the neural underpinnings of working memory. Despite both categories of tasks being labeled as “working memory” measures, previous empirical studies have provided mixed evidence regarding the shared amount of overlapping processes between complex span and n-back tasks. The present meta-analysis showed that the complex span and n-back tasks are weakly correlated, although significant heterogeneity across studies was observed. A follow-up analysis of unpublished data indicated that the sample composition affects the relationship between the complex span and n-back tasks, following the law of diminishing returns. Finally, a separate meta-analysis indicated that the simple span and n-back tasks are correlated to the same extent as are the complex span and n-back tasks. The present findings indicate that the complex span and n-back tasks cannot be used interchangeably as working memory measures in research applications.     

6-9岁儿童工作记忆的发展研究

以Baddeley工作记忆模型为基础考察儿童语音环路、视觉空间模板、中央执行的发展及其与复杂广度的关系。225名6-9岁被试完成9个任务,分别测量听力广度及工作记忆三个子系统的功能。发现工作记忆各个子成分的功能在6-9岁期间发展速度不同;中央执行与语音环路和视觉空间模板的联系随年龄增长加强;结构方程模型分析发现中央执行和语音环路功能对儿童听力广度都有显著的直接影响,表明言语复杂广度任务既涉及中央执行功能也涉及语音环路的存贮功能。     

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.     

Effects of impoverished environmental conditions on working memory performance

This cross-cultural study investigates the impact of background experience on four verbal and visuo-spatial working memory (WM) tasks. A total of 84 children from low-income families were recruited from the following groups: (1) Portuguese immigrant children from Luxembourg impoverished in terms of language experience; (2) Brazilian children deprived in terms of scholastic background; (3) Portuguese children from Portugal with no disadvantage in either scholastic or language background. Children were matched on age, gender, fluid intelligence, and socioeconomic status and completed four simple and complex span tasks of WM and a vocabulary measure. Results indicate that, despite large differences in their backgrounds and language abilities, the groups exhibited comparable performance on the visuo-spatial tasks dot matrix and odd-one-out and on the verbal simple span task digit recall. Group differences emerged on the verbal complex span task counting recall with children from Luxembourg and Portugal outperforming children from disadvantaged schools in Brazil. The study suggests that whereas contributions of prior knowledge to digit span, dot matrix, and odd-one-out are likely to be minimal, background experience can affect performance on counting recall. Implications for testing WM capacity in children growing up in poverty are discussed.     

Age differences in reaction time and attention in a national telephone sample of adults: education, sex, and task complexity matter

This study demonstrated effects of age, education, and sex on complex reaction time in a large national sample (N = 3,616) with a wide range in age (32-85) and education. Participants completed speeded auditory tasks (from the MIDUS [Midlife in the U.S.] Stop and Go Switch Task) by telephone. Complexity ranged from a simple repeated task to an alternating task that involved central executive processes including attention switching and inhibitory control. Increased complexity was associated with slower responses in older adults, those with lower education, and women, even after controlling for differences in health status. Higher levels of education were associated with greater central executive efficiency across adulthood: Overall, adults with college degrees performed on complex tasks like less educated individuals who were 10 years younger, up to age 75. These findings suggest that advanced education can moderate age differences on complex speeded tasks that require central executive processes, at least up to the point in old age at which biological declines predominate. The approach demonstrates the utility of combining laboratory paradigms with survey methods to enable the study of larger, more diverse and representative samples across the lifespan.     

Motor and perceptual determinants of performance on the Bender-Gestalt and the Beery Developmental Scale by retarded males.

The Bender Visual-motor Gestalt Test and Beery's Developmental Test of Visual-motor Integration were administered to 51 educable mentally retarded boys ranging in age from 72 to 161 mo. These scores were compared with scores boys received on three gross motor tasks by computing simple correlation coefficients and multiple regression coefficients with Bender and Beery's tests as dependent variables. The simple rs were similar but order of inclusion of independent variables in the regression analysis suggests differences.     

Individual differences in working memory and comprehension: a test of four hypotheses.

A relationship has consistently been found between measures of working memory and reading comprehension. Four hypotheses for this relationship were tested in 3 experiments. In the first 2 experiments, a moving window procedure was used to present the operation-word and reading span tasks. High- and low-span subjects did not differentially trade off time on the elements of the tasks and the to-be-remembered word. Furthermore, the correlation between span and comprehension was undiminished when the viewing times were partialed out. Experiment 3 compared a traditional experimenter-paced simple word-span and a subject-paced span in their relationship with comprehension. The experimenter-paced word-span correlated with comprehension but the subject-paced span did not. The results of all 3 experiments support a general capacity explanation for the relationship between working memory and comprehension.     

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。     

Processing efficiency in preschoolers’ memory span: Individual differences related to age and anxiety

In self-paced auditory memory span tasks, the microanalysis of response timing measures represents a developmentally sensitive measure, providing insights into the development of distinct processing rates during recall performance. The current study first examined the effects of age and trait anxiety on span accuracy (effectiveness) and response timing (efficiency) measures from word and digit span performance in a preschool sample (N = 76, mean age = 57 months, SD = 11). Children were reassessed 8 months later using the same two tasks plus a test of nonword memory span and a measure of articulation rate. The results at the second time point (T2) confirmed the effects of age on both processing effectiveness and efficiency. Trait anxiety was an additional negative predictor of span effectiveness (especially for digit span) and efficiency (in the case of word and nonword span). The findings are discussed in the context of factors contributing to early short-term memory development and attentional control theory.     

Internalising symptoms and verbal working memory in school‐age children: A processing efficiency analysis

The current study investigated differential contributions of internalising symptoms (state anxiety, trait anxiety, depression) to school‐age children's verbal short‐term (STM) and working memory (WM) span accuracy and efficiency (microanalysis of response times). Children's (N = 125, M_age = 11.44 years) STM/WM was assessed with simple/complex span tasks. Our analyses revealed that: (a) children with high levels of state anxiety displayed reduced simple span accuracy (on Word span) and poorer efficiency on both simple (preparatory intervals, interword pauses) and complex span (preparatory intervals) response time segments; (b) trait anxiety was a negative predictor of children's complex span accuracy, as well as their efficiency on both simple (word durations) and complex span (interword pauses) response time measures; (3) depressive symptoms predicted longer simple span interword pauses. Findings indicate that while all internalising symptoms were predictive of children's poorer memory search efficiency, especially during the “silent”, executive intervals (interword pauses), anxiety symptoms were specifically predictive of children's impaired span accuracy and other efficiency indicators (preparatory intervals, word durations). The study highlights the differential contributions of state, trait anxiety, and depressive symptoms to STM/WM in children, emphasising the need to measure both accuracy and efficiency to assess the role that such symptoms play in children's performance.