Kirsten Schuchardt

Working Memory Deficits in Children With Specific Learning Disorders

This article examines working memory functioning in children with specific developmental disorders of scholastic skills as defined by ICD-10. Ninety-seven second to fourth graders with a minimum IQ of 80 are compared using a 2 x 2 factorial (dyscalculia vs. no dyscalculia; dyslexia vs. no dyslexia) design. An extensive test battery assesses the three subcomponents of working memory described by Baddeley (1986): phonological loop, visual-spatial sketchpad, and central executive. Children with dyscalculia show deficits in visual-spatial memory; children with dyslexia show deficits in phonological and central executive functioning. When controlling for the influence of the phonological loop on the performance of the central executive, however, the effect is no longer significant. Although children with both reading and arithmetic disorders are consistently outperformed by all other groups, there is no significant interaction between the factors dyscalculia and dyslexia.

Functional deficits in phonological working memory in children with intellectual disabilities.

Recent studies indicate that children with intellectual disabilities have functional limitations primarily in the phonological loop of working memory (Baddeley, 1986). These findings are indicative of a specific structural deficit. Building on this research, the present study examines whether it is possible to identify specific phonological subfunctions as causal factors in these qualitative deviations from typical development found in children with intellectual disabilities. In a three-group design, specific subfunctions of phonological working memory were examined in students of the same mental age (one group of 15-year-olds with mild intellectual disability [IQ 50-69], one group of 10-year-olds with borderline intellectual disability [IQ 70-84], and one group of 7-year-olds of average intelligence [IQ 85-115]). The automatic activation of the subvocal rehearsal process was operationalized by the word-length effect; the size of the phonological store, by a task involving repetition of nonwords of differing syllable length; and accuracy of processing, by both the phonological similarity effect and the quality of acoustic presentation of the nonword repetition task (distorted vs. undistorted item presentation). The results revealed impairment of the phonological store only in terms of reduced storage capacity, and showed that this deficit increased with length of the item sequences to be remembered. However, this deficit was observed only in children with mild intellectual disability; the performance of children with borderline intellectual disability corresponded with that of a control group of 7-year-olds matched for mental age. The findings are discussed in the context of the two-component model of the phonological loop. They indicate that deficits in storage capacity are associated with deficits in language development and thus seem to be one of the causes of cognitive impairment in individuals with mild intellectual disability.

Working Memory in Children with Learning Disabilities: Rethinking the Criterion of Discrepancy.

The criterion of discrepancy is used to distinguish children with learning disorders from children with intellectual disabilities. The justification of the criterion of discrepancy for the diagnosis of learning disorders relies on the conviction of fundamental differences between children with learning difficulties with versus without discrepancy to intelligence. But the open question is whether these two groups are really characterised by different cognitive functioning. This question was examined in three studies in which several functions of working memory according to Baddeley were explored. A working memory battery with tasks for the phonological loop, the visual–spatial sketchpad and central executive skills was presented in individual sessions to children with learning disabilities (dyslexia or dyscalculia or mixed disorders of scholastic skills) and normal IQ, to children with the same problems but lower IQ, and to control groups of children with regular school achievement and normal IQ. Results reveal specific deficits in working memory in the groups with learning disabilities compared with the control groups. However, there were no differences between the disabled groups with normal versus lower intelligence. These findings do not support the notion of discrepant cognitive functioning due to differences in intelligence of the groups, and therefore lead to doubts about the validity of the criterion of discrepancy.

Arbeitsgedächtnisdefizite bei Kindern mit schwachen Rechen- und Schriftsprachleistungen

Zusammenfassung. Vor dem Hintergrund des Arbeitsgedachtnismodells von Baddeley (1986) wurde uberpruft, ob Kinder mit Schulleistungsschwachen Leistungsdefizite in zentralexekutiven, phonologischen und visuell-raumlichen Arbeitsgedachtnisfunktionen aufzeigen. Aus einer Stichprobe von 232 Drittklasslern wurden 69 Kinder identifiziert, die sich auf die vier Felder eines zweifaktoriellen Designs (Rechenleistung: schwach vs. unauffallig; Schriftsprachleistungen: schwach vs. unauffallig) verteilen. Um schwache Leistungen aufgrund von Intelligenzminderleistungen aus den Analysen herauszunehmen, wurden nur Kinder mit einem IQ groser 90 berucksichtigt. Die Kinder bearbeiteten in Einzelversuchen eine umfangreiche Testbatterie zur Erfassung der drei Subkomponenten des Arbeitsgedachtnisses. Es zeigte sich, dass Kinder mit Minderleistungen im Rechnen nur in der phonologischen Schleife Defizite aufweisen. Dagegen wurden bei Kindern mit schwachen Schriftsprachleistungen sowohl phonologische als auch zentralexekutive Defi...

Working Memory in Children With Learning Disabilities in Reading Versus Spelling Searching for Overlapping and Specific Cognitive Factors

In transparent orthographies like German, isolated learning disabilities in either reading or spelling are common and occur as often as a combined reading and spelling disability. However, most issues surrounding the cognitive causes of these isolated or combined literacy difficulties are yet unresolved. Recently, working memory dysfunctions have been demonstrated to be promising in explaining the emergence of literacy difficulties. Thus, we applied a 2 (reading disability: yes vs. no) × 2 (spelling disability: yes vs. no) factorial design to examine distinct and overlapping working memory profiles associated with learning disabilities in reading versus spelling. Working memory was assessed in 204 third graders, and multivariate analyses of variance were conducted for each working memory component. Children with spelling disability suffered from more pronounced phonological loop impairments than those with reading disability. In contrast, domain-general central-executive dysfunctions were solely associated with reading disability, but not with spelling disability. Concerning the visuospatial sketchpad, no impairments were found. In sum, children with reading disability and those with spelling disability seem to be characterized by different working memory profiles. Thus, it is important to take both reading and spelling into account when investigating cognitive factors of literacy difficulties in transparent orthographies.

Unterscheidet sich die Struktur des Arbeitsgedächtnisses bei Schulkindern mit und ohne Lernstörung

Zusammenfassung. 245 Kinder der ersten bis vierten Klassenstufe bearbeiten eine ausfuhrliche Testbatterie zur Erfassung der Funktionstuchtigkeit bei phonologischen, visuell-raumlichen und zentral-exekutiven Arbeitsgedachtnisanforderungen. Etwa die Halfte dieser Kinder leiden unter einer diagnostizierten Lernstorung (ICD-10). Mit Hilfe statistischer Dimensions- und Strukturanalysen konnte gezeigt werden, dass die der verwendeten Arbeitsgedachtnistestbatterie zugrunde liegende Vorstellung der Struktur von drei vergleichsweise unabhangigen Faktoren des Arbeitsgedachtnisses in gleicher Weise Gultigkeit hat fur Kinder mit vs. ohne Lernstorung.

Die Komorbidität von Lernschwierigkeiten mit ADHS-Symptomen im Grundschulalter

Children having difficulties in acquiring early literacy and mathematical skills often show an increased rate of inattention, hyperactivity, and impulsivity. This study provides data on the comorbidity rates of specific learning difficulties and ADHD symptoms. We analyzed the data of 273 children with learning difficulties despite an at least average IQ, 57 children with low IQ, and 270 children without learning difficulties and average IQ (comparison group). We assessed children’s IQ and school achievement using standardized achievement tests. ADHD symptoms were assessed via parents’ ratings. Our results showed that only 5 % of both the control group and the group with solely mathematical difficulties fulfilled the criteria of an ADHD subtype according to the DSM-IV based on parents’ ratings. In contrast, this was the case in even 20 % of the children with difficulties in reading/writing and of those with low IQ. Compared to girls, boys in the control group had a 150% higher risk for matching the criteria of one of the ADHD subtypes in parents’ ratings, whereas boys with learning difficulties and those with low IQ had an even 200% to 600% higher risk for it. The relationship between learning difficulties and ADHD symptoms can be found predominantly in the inattentive type. Possible reasons for the results are discussed.

Exekutive Funktionen bei Kindern mit Lernstörungen

Zusammenfassung Im Grundschulalter treten bei etwa einem Viertel aller Kinder Lernschwierigkeiten in einem oder mehreren Schulleistungsbereichen auf (Lesen, Schreiben, Rechnen). Diese Schwierigkeiten werden als Lernstorungen bezeichnet, wenn sie eine bedeutsame Diskrepanz zur Alterskohorte und zur allgemeinen Intelligenz des jeweiligen Kindes aufweisen. Die Forschung zu moglichen Ursachen fur Lernstorungen hat neben Intelligenz, visueller und auditiverInformationsverarbeitung und bereichsspezifischem Wissen inzwischen auch das Arbeitsgedachtnis und die exekutiven Funktionen in den Blick genommen. Der vorliegende Beitrag gibt nach einer Einfuhrung in das Thema Lernstorungen und einer Darstellung des Konstrukts der exekutiven Funktionen einen Uberblick uber aktuelle Befunde zur Auspragung exekutiver Funktionen bei Kindern mit Lese-Rechtschreibschwierigkeiten und Rechenschwierigkeiten. Dabei wird deutlich, dass die haufig auftretende Komorbiditat mit ADHS berucksichtigt werden muss. Kinder mit Lernstorungen ...Zusammenfassung Im Grundschulalter treten bei etwa einem Viertel aller Kinder Lernschwierigkeiten in einem oder mehreren Schulleistungsbereichen auf (Lesen, Schreiben, Rechnen). Diese Schwierigkeiten werden als Lernstorungen bezeichnet, wenn sie eine bedeutsame Diskrepanz zur Alterskohorte und zur allgemeinen Intelligenz des jeweiligen Kindes aufweisen. Die Forschung zu moglichen Ursachen fur Lernstorungen hat neben Intelligenz, visueller und auditiverInformationsverarbeitung und bereichsspezifischem Wissen inzwischen auch das Arbeitsgedachtnis und die exekutiven Funktionen in den Blick genommen. Der vorliegende Beitrag gibt nach einer Einfuhrung in das Thema Lernstorungen und einer Darstellung des Konstrukts der exekutiven Funktionen einen Uberblick uber aktuelle Befunde zur Auspragung exekutiver Funktionen bei Kindern mit Lese-Rechtschreibschwierigkeiten und Rechenschwierigkeiten. Dabei wird deutlich, dass die haufig auftretende Komorbiditat mit ADHS berucksichtigt werden muss. Kinder mit Lernstorungen ...

Development of Working Memory from Grade 3 to 5: Differences between Children With and Without Mathematical Learning Difficulties

ABSTRACT Based on the finding that children with mathematical learning difficulties (MLD) have deficits in working memory (WM), the question arises as to whether these children differ from typical learners only in the level or also in the developmental trajectories of WM functioning. To this end, the WM of 80 children with MLD and 71 typical learners was assessed longitudinally from third to fifth grade. Typical learners outperformed children with MLD in the phonological, visuospatial and central executive WM functioning in third grade. Latent change analyses indicated that both phonological and central executive WM functioning developed in a parallel pattern in children with MLD and in typical learners. In contrast, visuospatial WM functioning revealed a different development in children with and without MLD since the gap between both groups decreased over time. Overall, despite starting at a lower level, the WM functioning in children with MLD did not develop more slowly.

Phonological Processing in Children With Specific Reading Disorder Versus Typical Learners: Factor Structure and Measurement Invariance in a Transparent Orthography.

Although children with specific reading disorder (RD) have often been compared to typically achieving children on various phonological processing tasks, to our knowledge no study so far has examined whether the structure of phonological processing applies to both groups of children alike. According to Wagner and Torgesen (1987), phonological processing consists of 3 distinct constructs: phonological awareness (PA), rapid automatized naming (RAN), and the phonological loop (PL) of working memory. The present study examined whether this phonological processing model which was originally developed for English orthography is also applicable to a more transparent language such as German. Furthermore, we tested whether the structure of phonological processing is invariant across typically achieving children and children with RD. Therefore, 209 German-speaking 3rd graders (100 typical learners and 109 children with RD) completed a comprehensive test battery assessing PA, RAN, and PL. Using confirmatory factor analyses, we compared the latent structure of these phonological processing skills across both groups. The study yielded 3 important findings: First, Wagner and Torgesen’s (1987) model transfers to the German language and its orthography with transparent grapheme-to-phoneme correspondences. Second, the tripartite structure of phonological processing was evident across both groups (factorial invariance). Third, group invariance was also found for the measurement and structural components of the model (measurement invariance). These findings suggest that the nature of phonological processing is invariant across typically achieving children and children with RD acquiring the transparent orthography of German. Theoretical and practical implications are discussed.