Depression in multiple sclerosis: Relationship to working memory capacity.

Recent research has shown that depression in multiple sclerosis (MS) is associated with deficits on cognitively demanding tasks. One explanation for this relationship is that depressed NIS patients may have reduced working memory capacity. The present study was designed to test this hypothesis. Depressed NIS patients were compared with nondepressed MS patients and nondepressed healthy controls on a task of working memory capacity (reading span) and a short-term memory task not taxing working memory capacity (word span). In support of the capacity-reduction model, compared with the nondepressed groups, depressed MS patients performed significantly worse on reading span but not on word span. Additionally, reading span was significantly correlated with capacity-demanding tasks shown to be impaired in depressed NIS patients in previous reports. Results suggest that depressed MS patients are characterized by limited working memory capacity and that the central executive component of the working memory system may be most affected. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is "working memory capacity" just another name for word knowledge?

This study is concerned with whether the correlation between complex working memory spans and reading comprehension occurs because the complex spans reflect the capacity of a structural working memory that plays a causal role in comprehension or because a 3rd factor, word knowledge, plays a causal role in both the span tasks and comprehension. If the latter hypothesis is correct, the correlation between word span and reading comprehension should be large when span is tested with low-frequency words but should not occur when span is tested with very familiar words. 90 college students were tested on a simple and a complex version of the word span task with high- and low-frequency words. The Verbal Scholastic Aptitude Test (VSAT) was used as a measure of reading comprehension. The correlation between span and VSAT was somewhat higher when span was tested with low-frequency words, but was significant with both low- and high-frequency words. This suggests that both word knowledge and a content-free working memory play a causal role in the relationship between word span and higher level cognitive tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Task experience and children's working memory performance: A perspective from recall timing.

Working memory is an important theoretical construct among children, and measures of its capacity predict a range of cognitive skills and abilities. Data from 9- and 11-year-old children illustrate how a chronometric analysis of recall can complement and elaborate recall accuracy in advancing our understanding of working memory. A reading span task was completed by 130 children, 75 of whom were tested on 2 occasions, with sequence length either increasing or decreasing during test administration. Substantial pauses occur during participants' recall sequences, and they represent consistent performance traits over time, while also varying with recall circumstances and task history. Recall pauses help to predict reading and number skills, alongside as well as separate from levels of recall accuracy. The task demands of working memory change as a function of task experience, with a combination of accuracy and response timing in novel task situations being the strongest predictor of cognitive attainment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Generality and modifiability of working memory among skilled and less skilled readers.

Investigated whether individual differences in working memory are related to a general system and whether the predictability of working memory to academic achievement is enhanced under dynamic testing conditions. Exp 1 correlated 11 working memory tasks with short-term memory and achievement measures. Convergent and discriminant validity for the working memory measures was established. Although a confirmatory factor analysis supported the notion that the working memory tasks reflect 2 operations, these operations produced similar correlational patterns to achievement. Exp 2 supported a 2-factor model under dynamic testing procedures, and those procedures contribute significant variance to reading performance. Overall, the results suggest that (1) working memory operates as a general system independent of reading skill and (2) dynamic testing procedures enhance the prediction of reading performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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 1st 2 experiments, a moving window procedure was used to present the operation–word and reading span tasks. High- and low-span Ss 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. Exp 3 compared a traditional experimenter-paced simple word-span and an S-paced span in their relationship with comprehension. The experimenter-paced word-span correlated with comprehension, but the S-paced span did not. The results of all 3 experiments support a general capacity explanation for the relationship between working memory and comprehension. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in the efficiency of word recognition.

Examined the hypothesis that the attentional demands of word recognition covary with other measures of reading efficiency. Individual differences in efficiency were indexed by (1) speed and accuracy of lexical access, (2) obligatory activation of phonological codes, and (3) working memory capacity. The attentional demands of word recognition were measured with a dual-task technique. Ss performed naming and probe-detection tasks separately (single task) and in combination (dual task). The results showed that single-task to dual-task decrements in performance on the naming and probe tasks were predicted by measures of the speed and accuracy of lexical access, obligatory activation of phonological codes, and efficiency of working memory. These findings provide support for the widespread assumption that the attentional demands of basic reading processes are a source of individual differences in reading skill. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term longitudinal change in cognitive performance in later life.

Changes in mean performance on memory, information processing, and intellectual ability tasks over a 3-yr period were examined. The sample consisted of 328 community-dwelling men and women (from an original sample of 484 individuals) aged 55–86 yrs. Ss completed tasks yielding measures of verbal processing time, working memory, implicit memory, vocabulary, verbal fluency, world knowledge, reading comprehension, word recall, and text recall. The results showed significant average decline on working memory, verbal fluency, and world knowledge. There were also interactions for 2 processing time measures and working memory, showing greater decline in the earlier-born cohort group than in the later-born cohort group. A step-down analysis revealed that covarying declines in other variables, including processing time, did not eliminate significant declines in working memory, verbal fluency, and world knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The separability of working memory resources for spatial thinking and language processing: An individual differences approach.

The current study demonstrates the separability of spatial and verbal working memory resources among college students, In Experiment 1, we developed a spatial span task that taxes both the processing and storage components of spatial working memory. This measure correlated with spatial ability (spatial visualization) measures, but not with verbal ability measures. In contrast, the reading span test, a common test of verbal working memory, correlates with verbal ability measures, but not with spatial ability measures. Experiment 2, which uses an interference paradigm to cross the processing and storage demands of span tasks, replicates this dissociation and further demonstrates that both the processing and storage components of working memory tasks are important for predicting performance on spatial thinking and language processing tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Word knowledge and working memory as predictors of reading skill.

Three measures of working memory capacity and three measures of word knowledge were used as predictors of three different measures of reading skill. The results demonstrated that the size of a reader's vocabulary and the speed of accessing it are independent of a "depth" measure of word knowledge and that reading comprehension, reading speed, and text inferencing ability are all independent measures of reading skill. A series of regression analyses were conducted to derive a causal model of the three reading performance measures. The results indicated that working memory efficiency during reading was related to comprehension, whereas a more passive working memory capacity measure was related to reading speed. Moreover, text inferencing ability was related only to word knowledge. We conclude that concepts such as "reading skill," "working memory," and "word knowledge" are multidimensional constructs that cannot be captured by a single variable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The sandwich effect: The role of attentional factors in serial recall.

Five experiments tested the prediction, from a simple chaining model, that interleaving irrelevant material will substantially disrupt immediate serial recall. Exp 1 interpolated long or short words between items in an auditory digit span test. These 2 "sandwich" conditions disrupted recall to an equal but moderate extent. Exp 2 presented mixed lists of digits and words, cuing one or the other before or after presentation. Precuing led to substantially better recall. Exp 3 used articulatory suppression to rule out the hypothesis that recall was protected from the sandwich effect by subvocal rehearsal. Exp 4 combined the sandwich effect with a concurrent task, finding clear effects of both but no interaction. Exp 5 showed that the predictability of interpolated material did not influence recall. These results can be explained by adding an attentional preprocessor to standard chaining models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention and retrieval from long-term memory.

Conducted 9 experiments with 152 female volunteers (mean age 44.4 yrs) to investigate the disrupting effect of a secondary task on retrieval from long-term memory. Exps I–V studied the influence of concurrent card sorting or digit span on free recall or paired-associate learning of word lists. Exp VI explored recall probability using a recognition paradigm in which accuracy and latency could be measured simultaneously. Exp VII explored the latency effect with a semantic memory paradigm, and Exp VIII required Ss to make semantic category judgments while retaining sequences of 6 digits. Exp IX examined the effect of concurrent digital load on the rate of generating items from semantic categories. Overall findings reveal that a demanding concurrent task did not reduce the probability of retrieving an item from semantic or episodic memory. However, concurrent load during learning substantially effected recall performance. A concurrent task during retrieval did not have a clear effect on latency. The contrast between the pattern shown by errors and by that shown by latencies suggests that attempts to estimate the attentional demands of any task should be interpreted with considerable caution when based on a single measure, such as performance errors, performance latency, or a response to a probe RT signal. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A new tool for measuring and understanding individual differences in the component processes of reading comprehension.

We propose a new measure of individual differences in reading comprehension ability that is theoretically motivated, is easy to administer, and that has high predictive power. Participants read 3-sentence paragraphs that describe the relations among a set of real and artificial terms, and then they respond to true–false statements that assess their ability to access and integrate long-term memory knowledge with text information, to make text-based inferences, and to recall text. The components of our task predict performance on a test of global reading comprehension and on a range of specific comprehension tests, each of which draws more heavily on one particular component. Our task is better at predicting reading comprehension than is a typical working memory span task and has the potential for advancing researchers' understanding and measurement of a range of linguistic and cognitive tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concreteness of relational effects on recall of adjective–noun pairs.

Studied the effects of concreteness and relatedness of adjective–noun pairs on free recall, cued recall, and memory integration. The authors report on 2 experiments in which Ss read phrases or sentences containing adjective–noun pairs that vary in rated concreteness and intrapair relatedness. In Exp 1 normative ratings on imagery and relatedness were provided by 23 graduate and 20 undergraduate students. 64 undergraduates participated in the memory experiment. Exp 2 extended Exp 1 by using complete sentences rather than adjective–noun word pairs. 72 undergraduates volunteered to participate in the memory experiment and a separate group of 14 volunteered to participate in a sentence rating task. Consistent with predictions from dual coding theory and prior results with noun–noun pairs, both experiments showed that the effects of concreteness were strong and independent of relatedness in free recall and cued recall. The 2 attributes also had independent (additive) effects on integrative memory as measured by conditionalized free recall of pairs. Integration as measured by the increment from free to cued recall occurred consistently only when pairs were high in both concreteness and relatedness. Relatedness, adjective imagery, and noun imagery ratings, along with word frequencies for adjectives and nouns, and sentences with relatedness ratings are appended. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Children's working-memory processes: A response-timing analysis.

Recall response durations were used to clarify processing in working-memory tasks. Experiment 1 examined children's performance in reading span, a task in which sentences were processed and the final word of each sentence was retained for subsequent recall. Experiment 2 examined the development of listening-, counting-, and digit-span task performance. Responses were much longer in the reading- and listening-span tasks than in the other span tasks, suggesting that participants in sentence-based span tasks take time to retrieve the semantic or linguistic structure as cues to recall of the sentence-final words. Response durations in working-memory tasks helped to predict academic skills and achievement, largely separate from the contributions of the memory spans themselves. Response durations thus are important in the interpretation of span task performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Effect of attentional demands on context utilization.

Three experiments studied the prediction that utilization of contextual information will be reduced by the presentation of secondary tasks requiring attention. Ss in all experiments were primarily undergraduates. Context utilization was measured using a word boundary task that compared performance on passages with and without contextual information. Exp I (n = 64) used unclear materials to increase attentional demands, and significantly reduced context utilization. However, Exp II (n = 64) suggests that these results could be explained by changes in performance rate. Exp III (n = 96) used a digit recall task to produce attentional demands and significantly reduced context utilization. Results are discussed in terms of the importance of a limited-capacity operational memory for reading performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The use of nonword repetition as a test of phonological memory in children with Down syndrome

Recent research suggests a significant relationship between verbal short-term memory and normal language development. Although poor short-term memory and impaired language are features of Down syndrome there has been little investigation of the relationship between these functions in this population, and no studies have included the nonword repetition test devised by Gathercole and Baddeley on which much of the evidence from normal development is based. This study reports the use of nonword repetition with 33 children and teenagers with Down syndrome aged from 5 to 18 years, and investigates the relationship between this test and other memory and language measures. Word repetition was included as an indirect control for the perceptual and speech impairments often associated with this group. Words were repeated significantly more successfully than nonwords and both these tasks were sensitive to word length. Nonword repetition was significantly correlated with age, and when age and nonverbal cognitive ability were controlled, nonword repetition was significantly correlated with all other language-based memory measures, i.e. auditory digit span, word span, sentence repetition, and fluency, and also with memory for a sequence of hand movements, but not with memory for faces or a visual digit span task. There was also a significant relationship between nonword repetition and receptive vocabulary, language comprehension, and reading. When performance on the word repetition task was controlled in addition to age and nonverbal ability, significant correlations between nonword repetition and word span, sentence memory, hand movements, language comprehension, and reading remained. Fewer relationships between auditory digit span and these other measures were established; in particular, there was no association between digit span and the language and reading measures. Results suggest that nonword repetition is a reliable measure of phonological memory in Down syndrome and can predict language comprehension and reading ability.     

A common basis for recency effects in immediate and delayed recall.

Examined the effects of word frequency and list length on the long-term serial position curve in 2 experiments, using a total of 68 undergraduates. In Exp I, the object was to find a distractor activity that would be sufficient to eliminate the recency effect in conventional free recall. In Exp II, whether list length would show a similar pattern of effects in a continuous-distractor paradigm was examined. Results demonstrate that word frequency and list length had the same effects on the serial-position curve in the continuous-distractor paradigm of delayed recall that they had previously been shown to have in immediate recall. High word frequency and shorter lists led to improved recall of preterminal items but did not influence recall of terminal items. Results suggest that the same processes underlie recency effects in the 2 paradigms and that accounts that attribute recency effects to primary (or short-term) memory are inadequate. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simple and complex word spans as measures of working memory capacity.

Five experiments investigated the effects of word length in simple word span tasks and complex operation and reading span tasks and the relationship between these tasks and reading comprehension. The 1st 2 experiments showed word length effects using both simple and complex memory span tasks and that both simple and complex span tasks correlated with reading comprehension. In the 3rd experiment, articulatory suppression did not eliminate word length effects. The final experiments showed that articulatory suppression eliminated the effect of word length when words were sampled with replacement from small fixed pools but not when sampled without replacement from a large pool. The word pool effects were not a result of concreteness of the words. It is concluded that the reading span does not measure a working memory specific to reading. Further, in immediate memory experiments, repeating words from trial to trial may lead to a more limited coding than is used with nonrepeated words. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

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.