Working Memory Factors Research Articles

Factor Structure of the Norwegian Version of the WAIS-III in a Clinical Sample

Confirmatory Factor Analyses (CFA) of the Wechsler Adult Intelligence Scale-III (WAIS-III) lend partial support to the four-factor model proposed in the test manual. However, the Arithmetic subtest has been especially difficult to allocate to one factor. Using the new Norwegian WAIS-III version, we tested factor models differing in the number of factors and in the placement of the Arithmetic subtest in a mixed clinical sample (n = 272). Only the four-factor solutions had adequate goodness-of-fit values. Allowing Arithmetic to load on both the Verbal Comprehension and Working Memory factors provided a more parsimonious solution compared to considering the subtest only as a measure of Working Memory. Effects of education were particularly high for both the Verbal Comprehension tests and Arithmetic.

Advances in endophenotyping schizophrenia

The search for the genetic architecture of schizophrenia has employed multiple, often converging strategies. One such strategy entails the use of tracing the heritability and neurobiology of endophenotypes. Endophenotypes are quantifiable traits not visible to the eye, which are thought to reflect an intermediate place on the path from genes to disorder. Endophenotype abnormalities in domains such as neurophysiology or neurocognition occur in schizophrenia patients as well as their clinically "unaffected" relatives, and reflect polymorphisms in the DNA of schizophrenia spectrum subjects which create vulnerability to developing schizophrenia. By identifying the single nucleotide polymorphisms (SNPs) associated with endophenotypes in schizophrenia, psychiatric neuroscientists can select new strong inference based molecular targets for the treatment of schizophrenia.

Factor analytic support for social cognition as a separable cognitive domain in schizophrenia

Social cognition has received increasing attention in schizophrenia due to its theoretical relevance to core features of the disorder as well as the marked deficits in social functioning exhibited by these patients. However, there remains a need to develop and validate measures of social cognitive abilities and to demonstrate that they are constructs that are separable from non-social neurocognitive processes. In the current study, the Wechsler Adult Intelligence Scale-Revised (WAIS-R) was administered to 169 males with schizophrenia, and test results were subjected to confirmatory factor analysis (CFA) to determine if those WAIS-R subtests containing social content would form a distinct Social Cognition (SC) factor. CFA was used to evaluate various models that hypothesized an SC factor, and for comparison purposes the same models were evaluated in the WAIS-R standardization sample. Results confirmed the presence of a four-factor model that included an SC factor, as well as the more commonly reported Verbal Comprehension, Perceptual Organization, and Working Memory factors. The SC factor consisted of the Picture Arrangement and Picture Completion subtests, and demonstrated small but significant correlations with disorganization and negative symptoms, as well as with an index of social functioning. Results provide support for the validity of the SC factor as a measure of social cognition in schizophrenia, and demonstrate that at least some aspects of social cognition represent separable cognitive domains in schizophrenia.

Working memory limitations in children with severe language impairment

In the present study, the relations of various aspects of working memory to various aspects of language problems in a clinical sample of 97 Dutch speaking 5-year-old children with severe language problems were studied. The working memory and language abilities of the children were examined using an extensive battery of tests. Working memory was operationalized according to the model of Baddeley. Confirmative factor analyses revealed three memory factors: phonological, visual and central executive. Language was construed as a multifactorial construct, and confirmative factor analyses revealed four factors: lexical-semantic abilities, phonological abilities, syntactic abilities and speech production abilities. Moderate to high correlations were found between the memory and language factors. Structural equation modelling was used to further explore the relations between the different factors. Phonological memory was found to predict phonological abilities; central-executive memory predicted lexical-semantic abilities; and visual memory predicted speech production abilities. Phonological abilities also predicted syntactic abilities. Both the theoretical and clinical implications of the findings are discussed. Learning outcomes: The reader will be introduced to the concepts of multifactorial components of working memory as well as language impairment. Secondly the reader will recognize that working memory and language impairment factors can be related. Particular emphasis will be placed on phonological memory, central-executive memory and visual memory and their possible prediction of specific components of language impairment.

The role of working memory in syntactic ambiguity resolution: A psychometric approach.

In 2 studies, the authors used a combination of psychometric and experimental techniques to investigate the effects of domain-general and domain-specific working memory factors on offline decisions concerning attachment of an ambiguous relative clause. Both studies used English and Dutch stimuli presented to English- and Dutch-speaking participants, respectively. In Study 1, readers with low working memory spans were less likely to use recency strategies for disambiguation than were readers with high spans. This finding is inconsistent with predictions of locality- and resource-based accounts of attachment. Psychometric analyses showed that both domain-specific (verbal) and domain-general working memory accounted for the effect. Study 2 found support for the hypothesis that segmentation strategies imposed during silent reading can account for the counterintuitive relationship. Results suggest that readers with low spans have a greater tendency to break up large segments of text because of their limited working memory, leading to high attachment of the ambiguous relative clause.

Exploratory factor analysis of neuropsychological tests and their relationship to the Brown–Peterson task

The interference condition of the Brown–Peterson task and the auditory consonant trigrams test was designed to evaluate working memory in that it required a division of attentional processes to complete two cognitive tasks. However, the specific cognitive functions contributing to the performance of this interference task have yet to be determined. The objective of this study was to determine what other tasks are comparable to the Brown–Peterson task and conduct an exploratory factor analysis that included the measures from the Brown–Peterson task and other neuropsychological measures. A neuropsychological battery was administered to younger participants ( n = 107, mean age = 20.83) and older participants ( n = 93, mean age = 70.14). Factor analysis yielded a two-factor solution. Performance after the intervening serial subtraction task loaded on an auditory/visual working memory and complex attention factor and had common loadings with working memory subtests of the WAIS-III and the spatial span subtest of the WMS-III. Results suggest that the performance after the intervening serial subtraction task evaluates dual information processing, complex attention, and working memory.

Assessing the Working Memory Abilities of ADHD Children Using the Stanford-Binet Intelligence Scales, Fifth Edition

The present study investigated the working memory abilities of children with attention deficit/hyperactivity disorder (ADHD) as measured by the Stanford-Binet Intelligence Scales, Fifth Edition (SBV). In a retrospective causal-comparative design, the archival data of 46 ADHD children were compared to 59 nondiagnosed children. The ADHD children scored significantly lower in measures of working memory compared to the control group. Within the ADHD group, working memory was the lowest factor score, significantly lower than three of the four other factors. Significant differences were also revealed within the working memory factor, with ADHD children displaying significantly lower nonverbal working memory scores than verbal working memory. No such differences were evident in the control group. The results are interpreted within Baddeley’s working memory model.

#52 Relationships between serum proinflammatory and proimmune cytokines and stress in breastfeeding and formula feeding mothers

Melissa officinalis (lemon balm) is a traditional herbal medicine, which enjoys contemporary usage as a mild sedative, spasmolytic and antibacterial agent. It has been suggested, in light of in vitro cholinergic binding properties, that Melissa extracts may effectively ameliorate the cognitive deficits associated with Alzheimer's disease. To date, no study has investigated the effects on cognition and mood of administration of Melissa to healthy humans. The present randomised, placebo-controlled, double-blind, balanced-crossover study investigated the acute effects on cognition and mood of a standardised extract of M. officinalis. Twenty healthy, young participants received single doses of 300, 600 and 900 mg of M. officinalis (Pharmaton) or a matching placebo at 7-day intervals. Cognitive performance was assessed using the Cognitive Drug Research (CDR) computerised test battery and two serial subtraction tasks immediately prior to dosing and at 1, 2.5, 4 and 6 h thereafter. In vitro IC50 concentrations for the displacement of [3H]-(N)-nicotine and [3H]-(N)-scopolamine from nicotinic and muscarinic receptors in human occipital cortex tissue were also calculated. Results, utilising the cognitive factors previously derived from the CDR battery, included a sustained improvement in Accuracy of Attention following 600 mg of Melissa and time- and dose-specific reductions in both Secondary Memory and Working Memory factors. Self-rated “calmness,” as assessed by Bond–Lader mood scales, was elevated at the earliest time points by the lowest dose, whilst “alertness” was significantly reduced at all time points following the highest dose. Both nicotinic and muscarinic binding were found to be low in comparison to the levels found in previous studies.

Are Working Memory and Attention Related Constructs?

Abstract. The purpose of this study was to replicate the working memory model proposed by Oberauer, Suess, Wilhelm, and Wittmann (2000) and to clarify its relationship to selective attention. Eleven working memory and attention tests were administered to 125 students. Using structural equation models, we were able to confirm a facet model of working memory with three functional and two content factors. Thus, the present study provides further evidence for a facet model of working memory. Additionally, the factor selective attention was added to this model. We found only low to moderate correlations between selective attention and functional working memory factors. Therefore, this study provides further evidence that selective attention, as measured by the Testbattery for Attentional Performance (TAP), and working memory are distinct concepts.

A longitudinal study of sentence comprehension difficulty in primary progressive aphasia

Context: Patients with primary progressive aphasia have sentence comprehension difficulty, but the longitudinal course of this deficit has not been investigated. Objective: To determine how grammatical, single word meaning, and...

Factor Structure of the French Version of the Wechsler Adult Intelligence Scale–III

The standardization of the French version of the Wechsler Adult Intelligence Scale (WAIS-III) was conducted after carefully adapting the French version fromthe U.S. version and extensive field testing. The standardization sample was composed of 1,104 participants from 16 to 89 years. To assess the construct validity of the French version, exploratory and confirmatory factor analyses were performed. Two-factor, three-factor, and four-factor models were compared. The four-factor solution fitted the data much better than did the two-and three-factor solutions. The only problem observed was with the Arithmetic subtest, which did not show clear alignment with the Working Memory factor. Otherwise, the factor structure of the U.S. WAIS-IIIwas replicated with its French adaptation. Despite important changes in five verbal subtests, very similar factor structure was observed between the U.S. and the French standardization samples. This is an important indication of the universality of the factor structure underlying the WAIS-III.

Normal and pathological development of subject–verb agreement in speech production: a study on French children

We report a study on the spoken production of subject–verb agreement in number by four age groups of normally developing children (between 5 and 8;5) and a group of 8 children with Specific Language Impairment (SLI; between 5;4 and 9;4), all French speaking. The production of verb agreement was experimentally elicited by asking children to complete sentence preambles containing a head noun and a potentially attracting ‘local noun’. In contrast to previous studies that focused on attraction with local nouns within the subject constituent (postmodifiers), we also studied attraction with local nouns in structures that are not part of the subject constituent (interpolated adjuncts). In normally developing children, we report that (1) attraction effects appear from early on; (2) singular is produced as the default number until age 7 included; (3) more errors are produced with adjunct structures than with postmodifiers, but only from age 8;5 on. In contrast, even the older SLI children showed no attraction effect, a predominance of the singular as default, no effect of syntactic structure and, more generally, persistent high error rates. The turning point observed between 7 and 8;5 in normal children, characterized by a reduced error rate and a significant effect of syntactic structure, is interpreted as an index of the automatization of agreement. The syntactic structure effect is discussed in terms of the interplay of structural and working memory factors in the computation of long-distance relationships.

Verbal and non-verbal working memory and achievements on National Curriculum tests at 11 and 14 years of age

AbstractRecent research has found links between working memory and performance on National Curriculum tests. However, these studies have employed only verbal complex span tasks as measures of the central executive component of working memory. In the present study, children at Key Stages 2 and 3 of the National Curriculum (aged 11 and 14 years) were tested on measures of the phonological loop and visuospatial sketchpad as well as both verbal and nonverbal central executive tasks. Confirmatory factor analysis identified two factors: one verbal working memory factor associated with both the phonological loop and verbal central executive tasks, and one non-verbal working memory factor associated with both the visuospatial sketchpad and non-verbal central executive tasks. Further analyses were then used to explore the relationship between working memory and National Curriculum test scores in English, mathematics and science. The results suggested that both verbal and non-verbal working memory are important predictors of National Curriculum test scores.

Visuo-spatial and verbal working memory in the five-disc Tower of London task: An individual differences approach

This paper reports a study of the roles of visuo-spatial and verbal working memory capacities in solving a planning task—the five-disc Tower of London (TOL) task. An individual differences approach was taken. Sixty adult participants were tested on 20 TOL tasks of varying difficulty. Total moves over the 20 TOL tasks was taken as a measure of performance. Participants were also assessed on measures of fluid intelligence (Raven's matrices), verbal short-term storage (Digit span), verbal working memory span (Silly Sentence span), visuo-spatial short-term storage (Visual Pattern span and Corsi Block span), visuo-spatial working memory (Corsi Distance Estimation), visuo-spatial processing speed (Manikin test), and verbal speed (Rehearsal speed). Exploratory factor analysis using an oblique rotation method revealed three factors which were interpreted as (1) a visuo-spatial working memory factor, (2) an age-speed factor, and (3) a verbal working memory factor. The visuo-spatial and verbal factors were only moderately correlated. Performance on the TOL task loaded on the visuo-spatial factor but did not load on the other factors. It is concluded that the predominant goal-selection strategy adopted in solving the TOL relies on visuo-spatial working memory capacity and particularly involves the active “inner scribe” spatial rehearsal mechanism. These correlational analyses confirm and extend results previously obtained by use of dual task methods, (Phillips, Wynn, Gilhooly, Della Sala, & Logie, 1999).

Redefining the Factor Structure of the Wechsler Memory Scale-III: Confirmatory Factor Analysis With Cross-Validation

The purpose of this study was to revisit the underlying factor structure of the Wechsler Memory Scale-III. The WMS-III Technical Manual (Wechsler, 1997) presented findings from confirmatory factor analyses that support a three- and five-factor solution with separate immediate and delayed memory factors. A rigorous structural equation modeling approach was used to examine the factor structure of the test. The results verify that a three-factor model composed of verbal (immediate and delayed), visual (immediate and delayed), and working memory factors accurately represents the factor structure of the WMS-III. Results were crossvalidated on an independent sample.

Modulation of mood and cognitive performance following acute administration of Melissa officinalis (lemon balm)

Melissa officinalis (lemon balm) is a traditional herbal medicine, which enjoys contemporary usage as a mild sedative, spasmolytic and antibacterial agent. It has been suggested, in light of in vitro cholinergic binding properties, that Melissa extracts may effectively ameliorate the cognitive deficits associated with Alzheimer's disease. To date, no study has investigated the effects on cognition and mood of administration of Melissa to healthy humans. The present randomised, placebo-controlled, double-blind, balanced-crossover study investigated the acute effects on cognition and mood of a standardised extract of M. officinalis. Twenty healthy, young participants received single doses of 300, 600 and 900 mg of M. officinalis (Pharmaton) or a matching placebo at 7-day intervals. Cognitive performance was assessed using the Cognitive Drug Research (CDR) computerised test battery and two serial subtraction tasks immediately prior to dosing and at 1, 2.5, 4 and 6 h thereafter. In vitro IC 50 concentrations for the displacement of [ 3H]-( N)-nicotine and [ 3H]-( N)-scopolamine from nicotinic and muscarinic receptors in human occipital cortex tissue were also calculated. Results, utilising the cognitive factors previously derived from the CDR battery, included a sustained improvement in Accuracy of Attention following 600 mg of Melissa and time- and dose-specific reductions in both Secondary Memory and Working Memory factors. Self-rated “calmness,” as assessed by Bond–Lader mood scales, was elevated at the earliest time points by the lowest dose, whilst “alertness” was significantly reduced at all time points following the highest dose. Both nicotinic and muscarinic binding were found to be low in comparison to the levels found in previous studies.

Exploratory factor analysis of the WAIS-III in a mixed patient sample

The Wechsler Adult Intelligence Scale-III (WAIS-III) was administered to 152 patients at a VA Medical Center. Means for age, education, and Full Scale IQ were 51.49 years (SD = 13.00), 12.43 years (SD = 2.00), and 92.61 (SD = 14.06), respectively. Of the 152 patients, 69 had substance abuse disorders, 39 had medical/neurological conditions, 27 had both substance abuse and psychiatric disorders, and 17 had psychiatric conditions. The 13 WAIS-III subtests were subjected to a principal-axis factor analysis with oblimin rotation. Four factors were specified to be retained. The Verbal Comprehension, Perceptual Organization, and Processing Speed factors were identical to those in the standardization sample. However, Arithmetic could not be allocated to any factor within the patient sample. The Working Memory factor consisted only of the Digit Span and Letter-Number Sequencing subtests. &copy 2000 National Academy of Neuropsychology. Published by Elsevier Science Ltd

Mediators of behavioral problems in 7-year-old children born after 24 to 28 weeks of gestation.

We tested the hypothesis that prematurity acts through its association with neuromotor and intellectual functioning to explain behavior problems at school age. Sixty-one extremely preterm (EP) very low birth weight (VLBW) children (< 29 wk and < 1,500 g) born in 1987-1990 and 44 normal birth weight children (NBW) (> 37 wk and > 2,500 g) were matched for age, sex, and socioeconomic status (SES). Mediator variables were evaluated at a hospital at 5 years and 9 months. Behaviors were evaluated at school at 7 years by peers, teachers, and parents. When compared with NBW children, EP/VLBW children had poorer IQ and neuromotor development. At school, EP/VLBW children were evaluated by peers as more sensitive/ isolated, and by teachers and parents as more inattentive and hyperactive than NBW. When mediators were introduced, the previously significant relation between prematurity and behavior problems disappeared. Hyperactive and inattentive behaviors were explained by a specific working memory factor for the latter, and by a general intellectual delay for the former, whereas sensitive/isolated behaviors were best explained by neuromotor delays. Inattentive behaviors were also related to family adversity. At school age, extreme prematurity had thus an indirect effect on behaviors via specific and nonspecific intellectual and neuromotor delays.

Expertise and age-related changes in components of intelligence.

In a sample of 263 male GO players at 48 levels of expertise and ranging from 18 to 78 years of age, it was found that factors of expertise deductive reasoning (EDR) and expertise working memory (EWM) were independent of factors of fluid reasoning (Gf) and short-term working memory (STWM) that, along with cognitive speed (Gs), have been found to characterize decline of intelligence in adulthood. The main effects of analyses of cross-sectional age differences indicated age-related decline in EDR and EWM as well as in Gf, STWM, and Gs. However, interaction and partialing analyses indicated that decline in EDR and EWM decreased to no decline with increase in level of expertise. The results thus suggest that with increase in factors known to raise the level of expertise--particularly, intensive, well-designed practice--there may be no age-related decline in the intelligence that is measured in the abilities of expertise.

Executive functioning, temporal discounting, and sense of time in adolescents with attention deficit hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD).

Clinic-referred teens (ages 12-19) with ADHD and ODD (N = 101) were compared to community control (CC) teens, equated for age and sex, (N = 39) on a variety of psychological tasks assessing executive functioning (EF), temporal reward discounting, and time estimation and reproduction. A factor analysis reduced the EF measures to three dimensions, representing CPF Inattention, Working Memory, and CPT Inhibition. Results indicated that the ADHD group had significantly more CPT Inattention than the CC group. No differences were found for Working Memory or CPT Inhibition. The ADHD group displayed significantly greater temporal discounting of delayed hypothetical monetary rewards relative to immediate ones and manifested more impaired time reproduction, but not time estimation, than did the CC group. Main effects for level of IQ were found only on the Working Memory factor and largely did not interact with the group factor otherwise. The group differences in CPT Inattention, temporal discounting, and time reproduction were not a function of level of comorbid oppositional defiant disorder, delinquency, or anxiety-depression. Results are reasonably consistent with past research on EF and sense of time in children with ADHD and extend these findings to the adolescent age group. Problems with working memory and CPT inhibition found in prior studies of children with ADHD, however, were not evident here, perhaps owing to age-related improvements or insufficient task difficulty.