Working memory and educational achievement in children with intellectual disabilities

Effects of a physical education intervention on attention and inhibitory control in Ecuadorian children with intellectual disabilities

Background: Studies on physical activity interventions indicated a facilitative effect on cognitive performance in persons with intellectual disabilities; however, research is scarce, especially in low/middle-income countries. Aim: We explored the effects of a 6-week enriched physical education program on inhibitory control and attention functions in Ecuadorian children with intellectual disabilities. Methods: Thirty children with mild intellectual disabilities (10-14 years old) were randomly assigned to an intervention or control group. Before and after the intervention, attention and inhibitory control were measured using computer-based nonverbal tasks. Results: The findings showed significantly more accurate and faster responses in the vigilance task in the intervention group than in the controls. There were no significant intervention-related changes in inhibitory control; however, there were more prominent accuracy tendencies toward improvement in the intervention group. Conclusions: Results provide evidence of the potential of physical activity programs to enhance attention in this population, which could serve as a mediator for inhibitory control.

Early numeracy profiles in young children with intellectual disabilities: The role of cognitive functions

Exploring individual differences and looking beyond averaged parameters of early numeracy in young children with mild intellectual disabilities has become an area of interest to many researchers worldwide. This study aimed to identify the different profiles of early numeracy skills in young children with mild intellectual disabilities. For this purpose, we assessed early numeracy through Utrecht early numeracy test and learning aptitude through Detroit Test, in a sample of 135 children diagnosed with intellectual disabilities. The mean of their mental age was 5:09 (years:months). Two-step cluster analysis identified four homogenous groups of children with distinct early numeracy profiles as follows:C1 were fluent in relational and numerical skills up to 20, C2 were fluent in relational skills and numerical skills up to 10, C3 had basic knowledge of relational skills and inconsistent numerical skills up to 10 and C4 had inconsistent relational skills and numerical skills. Results are discussed with reference to their educational implications.

The Perfect Match! A Review and Tutorial on Issues Related to Matching Groups in Investigations of Children with Neurodevelopmental Conditions

Research concerned with children and young people who have neurodevelopmental disabilities (ND) in relation to early language acquisition usually involves comparisons with matched group(s) of typically developing individuals. In these studies, several important and complex issues need to be addressed. Three major issues are related to: (1) the choice of a variables on which to carry out group matching; (2) recruiting children into the study; and (3) the statistical analysis of the data. To assist future research on this topic, we discuss each of these three issues and provide recommendations about what we believe to be the best course of action. To provide a comprehensive review of the methodological issues, we draw on research beyond the topic of early language acquisition. Our overall aim is to contribute to research that considers questions about delay or differences in development patterns of development and about identifying potentially causal variables.

Cognitive factors and educational placement affecting mathematical attainment in middle school students with mild intellectual disability

The study investigated the relationship between mathematics achievement, cognitive and motor skills, and general intellectual ability among seventy 10-12 years old students with mild intellectual disability (MID) attending regular school (n = 30) and special school (n = 40). The purpose of the study was to identify the critical deficits teachers need to consider when teaching mathematics at the secondary school level. The students attending regular schools had significantly higher fluid intelligence scores (p = 0.036), but we found no difference in the total score of the math achievement test. Special school students were more eager to use assistance and aids when solving math problems (p = 0.040). The study indicated significant associations between basic mathematical skills, verbal and visuospatial processing, and motor skills. Thus, it is essential to compensate for the delay of students' cognitive development to improve their basic mathematical skills and, in general, mathematical performance. The educational placement affects the willingness or ability to seek academic help when solving mathematical problems.

Gamification as technology enabler in SEN and DHH education

Yearly in Mauritius, only a few Special Educational Needs (SEN) and especially Deaf and Hard of Hearing (DHH) students manage to get a passing mark in French language at elementary level. As at date, literature suggests that there is hardly any French language learning tools connected with pedagogical knowledge and technological tools suitable for those children. The rationale behind this paper is to show how gamification of French learning resources can positively affect SEN and especially DHH students' understanding and level of achievement in the language. Research questions were posed about the difficulties faced when students of that specific group learn to read and write in French, about how the gamification of textual resources can be used to improve the students' learning, and the impact the games have on the students. The aim of this research is to embed gamification in the teaching and learning process of French language. Advocating for both qualitative and quantitative methods, the project based itself on the pragmatic paradigm while the theoretical framework is based on action research. Using my methodological inventiveness, data was gathered using techniques such as surveys, interviews, observations and focus group discussions through the lenses of narrative inquiry. On average, most students already did quite well when subjected to their teachers' teaching methods only and showed a slight improvement for some students when games were added as learning aid.

Spelling abilities of school-aged children with Williams syndrome

AIMS

We examined the relation between spelling ability and word-reading ability in children with Williams syndrome (WS).

METHODS

Eighty 9-17-year-olds with genetically-confirmed WS completed standardized tests of spelling, word reading, and intellectual ability; 45 also completed tests of phonological awareness and vocabulary. Reading instruction method was classified as Phonics or Other.

RESULTS

Spelling ability varied widely. Although at the group level, spelling standard scores (SSs) were significantly lower than word-reading SSs, at the individual level, this difference was significant for fewer than half the participants. Spelling and reading SSs were highly correlated, even after controlling for intellectual ability. Students taught to read using systematic phonics instruction had significantly higher spelling SSs than those taught to read using other approaches, even after controlling for intellectual ability. Spelling ability contributed significant unique variance to word-reading ability, beyond the effects of phonological awareness, vocabulary, and reading instruction method.

CONCLUSIONS

Our findings are consistent with Ehri's Word Identity Amalgamation Theory. In combination with previous meta-analytic findings for typically developing children (Graham & Santangelo, 2014) our results suggest that children with WS are likely to benefit from the inclusion of systematic spelling instruction as part of a systematic phonics approach to teaching word reading.

Decoding Abilities in Adolescents with Intellectual Disabilities: The Contribution of Cognition, Language, and Home Literacy

Decoding abilities in individuals with intellectual disabilities (ID) are substantially lower than for typical readers. The underlying mechanisms of their poor reading remain uncertain. The aim of this study was to investigate the concurrent predictors of decoding ability in 136 adolescents with non-specific ID, and to evaluate the results in relation to previous findings on typical readers. The study included a broad range of cognitive and language measures as predictors of decoding ability. A LASSO regression analysis identified phonological awareness and rapid automatized naming (RAN) as the most important predictors. The predictors explained 57.73% of the variance in decoding abilities. These variables are similar to the ones found in earlier research on typically developing children, hence supporting our hypothesis of a delayed rather than a different reading profile. These results lend some support to the use of interventions and reading instructions, originally developed for typically developing children, for children and adolescents with non-specific ID.

Investigating Reading Comprehension in Adolescents with Intellectual Disabilities: Evaluating the Simple View of Reading

Reading comprehension difficulties are common in individuals with intellectual disabilities (ID), but the influences of underlying abilities related to reading comprehension in this group have rarely been investigated. One aim of this study was to investigate the Simple View of Reading as a theoretical framework to describe cognitive and linguistic abilities predicting individual differences in reading comprehension in adolescents with non-specific ID. A second aim was to investigate whether predictors of listening comprehension and reading comprehension suggest that individuals with ID have a delayed pattern of development (copying early grade variance in reading comprehension) or a different pattern of development involving a new or an unusual pattern of cognitive and linguistic predictors. A sample of 136 adolescents with non-specific ID was assessed on reading comprehension, decoding, linguistic, and cognitive measures. The hypotheses were evaluated using structural equation models. The results showed that the Simple View of Reading was not applicable in explaining reading comprehension in this group, however, the concurrent predictors of comprehension (vocabulary and phonological executive-loaded working memory) followed a delayed profile.

Parent perceptions regarding literacy instruction for students with intellectual disability

BACKGROUND

Parents offer a unique perspective as they may view literacy instruction through the lens of its direct impact on their child's daily life. Further, they are likely to provide insight into the interactions between the perceived effectiveness of instruction and their expectations for their child's success. The purposes of the current investigation were to explore perceptions of parents of children with intellectual disability (ID) related to their child's literacy instruction in schools and understand parental expectations for their child's literacy performance.

METHODS

In the current investigation, we surveyed 211 parents of children with ID in one state within the USA to identify their perceptions related to their child's literacy outcomes and instruction. The survey instrument contained 25 items including 9 multiple-choice, 12 multiple-selection, 2 open-response and 2 rank order items.

RESULTS

Data indicated significant differences across grade bands related to the type of skills students engage in learning, the importance of specific literacy skills and the challenges or barriers for students to engage in literacy instruction. The overwhelming majority of parents reported their child learning to read as very important and believe there is a difference in life outcomes between children who can read written words and those who cannot. Parents of elementary school children report barriers of disruptive behaviour, the inability of children to remain seated and distractibility more so than parents of secondary students. Parents of high school students reported a lack of instructional time more often than parents of middle and elementary school.

CONCLUSIONS

While parents across grade bands reported the importance of literacy skills for students with ID and instruction in reading comprehension, listening comprehension and vocabulary, some differences were noted. Only half the parents reported an increased focus on literacy instruction, including on essential skills (e.g. decoding), in the earlier grades. Problem behaviour and motivation served as barriers to literacy for elementary students, and a lack of instructional time served as a barrier to writing for high school students.

An open randomized controlled trial of the effects of linguistic simplification and mediation on the comprehension of "easy read" text by people with intellectual disabilities

BACKGROUND

This trial aimed to measure the effects of extrinsic and intrinsic factors on users' comprehension of health information provided in adapted written "easy read" material.

METHOD

Sixty adults with intellectual disabilities undertook The Easy Read Task, randomly allocated with stratification by reading ability to one of four conditions (with and without simplified language/with and without mediation).

RESULTS

Neither linguistic complexity of the text nor mediation independently or combined made a significant difference to the understanding of information. Post hoc testing revealed that the group who received simplified language with mediation performed significantly better than the group that had complex text with mediation. None of the other differences between the remaining groups were significant.

CONCLUSIONS

Constructing meaning needs to extend beyond a consideration of form as found in "easy read" documents to recognize the role of individual capacity for language processing.

A Serious Game-Derived Index for Detecting Children With Heterogeneous Developmental Disabilities: Randomized Controlled Trial

BACKGROUND

Developmental disabilities are a set of heterogeneous delays or difficulties in one or more areas of neuropsychological development. Considering that childhood is an essential stage of brain development and developmental delays lead to personal or social burdens, the early detection of childhood developmental disabilities is important. However, early screening for developmental disabilities has been a challenge because of the fear of positive results, expensive tests, differences in diagnosis depending on examiners' abilities, and difficulty in diagnosis arising from the need for long-term follow-up observation.

OBJECTIVE

This study aimed to assess the feasibility of using a serious game-derived index to identify heterogeneous developmental disabilities. This study also examines the correlation between the game-derived index and existing neuropsychological test results.

METHODS

The randomized controlled trial involved 48 children with either normal development or developmental disabilities. In this clinical trial, we used 19 features (6 from the Korean-Wechsler Preschool and Primary Scale of Intelligence, 8 from the Psychoeducational Profile Revised, 2 from the Bruininks-Oseretsky Test of Motor Proficiency, Second Edition, and 3 from the Pediatric Evaluation of Disability Inventory) from neuropsychological tests and 9 (7 game scores, path accuracy, and completion rate) from the serious game, DoBrain. The following analysis was conducted based on participants' baseline information and neuropsychological test and game-derived index data for one week: (1) we compared the baseline information between the normal development and developmental disabilities groups; (2) then we measured the correlation between the game-derived index and the neuropsychological test scores for each group; and (3) we built a classifier based on the game-derived index with a Gaussian process method and then compared the area under the curve (AUC) with a model based on neuropsychological test results.

RESULTS

A total of 16 children (normal development=9; developmental disabilities=7) were analyzed after selection. Their developmental abilities were assessed before they started to play the serious games, and statistically significant differences were found in both groups. Specifically, the normal development group was more developed than the developmental disabilities group in terms of social function, gross motor function, full-scale IQ, and visual motor imitation, in that order. Similarly, the normal development group obtained a higher score on the game-derived index than the developmental disabilities group. In the correlation analysis between the game-derived index and the neuropsychological tests, the normal development group showed greater correlation with more variables than the developmental disabilities group. The game-derived index-based model had an AUC=0.9, a similar detection value as the neuropsychological test-based model's AUC=0.86.

CONCLUSIONS

A game-derived index based on serious games can detect children with heterogenous developmental disabilities. This suggests that serious games can be used as a potential screening tool for developmental disabilities.

TRIAL REGISTRATION

Clinical Research Information Service KCT0003247; https://cris.nih.go.kr/cris/en/search/search_result_st01 .jsp?seq=12365.

Acquisition of Reading and Intellectual Development Disorder

We propose a review of the literature of the studies investigating reading acquisition in intellectual deficiency (ID), with particular focus on the explanatory factors for reading difficulties. Indeed, we explore the role of intellectual efficiency, perceptual abilities, oral language development, phonological processing and memory. The study of reading acquisition in ID is a challenge because of a high degree of heterogeneity in the results which, together with other variables influencing learning and development. This review has allowed us to understand that there are multiple reasons why individuals with ID have difficulty learning to read. More specifically, there is a link between reading skills and certain cognitive skills, such as perception, oral language, phonological processing and working memory.

Modeling individual variation in early literacy skills in kindergarten children with intellectual disabilities

In the present study, we investigated (i) to what extent the early literacy skills (phonological awareness, letter knowledge, and word decoding) along with cognitive (nonverbal reasoning, attention, phonological short-term memory, sequential memory, executive functioning) and linguistic (auditory discrimination, rapid naming, articulation, vocabulary) precursor measures of 53 six-year old children with intellectual disabilities (ID) differ from a group of 74 peers with normal language acquisition (NLA) and (ii) whether the individual variation of early literacy skills in the two groups to the same extent can be explained from the precursor measures. Results showed that children with ID scored below the NLA group on all literacy and precursor measures. Structural equation modeling evidenced that in the children with NLA early literacy was directly predicted by phonological awareness, PSTM and vocabulary, with nonverbal reasoning and auditory discrimination also predicting phonological awareness. In children with ID however, the variation in word decoding was predicted by letter knowledge and nonverbal reasoning, whereas letter knowledge was predicted by rapid naming, which on its turn was predicted by attentional skills. It can be concluded phonological awareness plays a differential role in the early literacy skills of children with and without ID. As a consequence, the arrears in phonological awareness in children with ID might put them on hold in gaining proper access to literacy acquisition.

WHAT THIS PAPER ADDS

This paper adds to the theoretical knowledge base on literacy acquisition in a special population, namely children with intellectual disabilities (ID). It addresses factors that influence early literacy learning, which have not been investigated thoroughly in this special and specific group. Furthermore, the children are not tested solely on literacy, but also on cognitive measures that may influence literacy acquisition. Whereas most research in ID focuses on groups with specific syndromes/etiologies, this paper takes a varied group of children with ID into account. The paper also adds to educational insights, since the findings imply that children with ID are able to use phonological pathways in learning to read. Educators could teach these children phonics-based literacy skills tailored to their individual learning needs.

Relation between working memory and self-regulation capacities and the level of social skills acquisition in people with moderate intellectual disability

BACKGROUND

Social competence deficit is one of the main characteristics of intellectual disability. The aim of this paper is to determine the influence of working memory (WM) and self-regulation (SR) on social skills in persons with moderate intellectual disability (MID).

METHOD

The sample included 41 participants with MID, aged 14-21. Memorizing animals and maze tasks were used for WM assessment. SR skills were assessed by the Behavioral Multitask Batteries. Social skills were rated by the Socialization subscale from the Adaptive Behavior Assessment System II, which consists of two parts.

RESULTS

Social skills part could mainly be predicted from SR scores (β = -.441), followed by WM (β = .390) and IQ score (β = .382). Only WM score (β = .494) had a predictive value for Leisure time part.

CONCLUSION

As WM had a greater influence on social skills, incorporating WM training into programmes for improving social skills in persons with MID should be considered.

The Contributions of Memory and Vocabulary to Non-Verbal Ability Scores in Adolescents with Intellectual Disability

It is usually assumed that performance on non-verbal intelligence tests reflects visual cognitive processing and that aspects of working memory (WM) will be involved. However, the unique contribution of memory to non-verbal scores is not clear, nor is the unique contribution of vocabulary. Thus, we aimed to investigate these contributions. Non-verbal test scores for 17 individuals with intellectual disability (ID) and 39 children with typical development (TD) of similar mental age were compared to determine the unique contribution of visual and verbal short-term memory (STM) and WM and the additional variance contributed by vocabulary scores. No significant group differences were found in the non-verbal test scores or receptive vocabulary scores, but there was a significant difference in expressive vocabulary. Regression analyses indicate that for the TD group STM and WM (both visual and verbal) contributed similar variance to the non-verbal scores. For the ID group, visual STM and verbal WM contributed most of the variance to the non-verbal test scores. The addition of vocabulary scores to the model contributed greater variance for both groups. More unique variance was contributed by vocabulary than memory for the TD group, whereas for the ID group memory contributed more than vocabulary. Visual and auditory memory and vocabulary contributed significantly to solving visual non-verbal problems for both the TD group and the ID group. However, for each group, there were different weightings of these variables. Our findings indicate that for individuals with TD, vocabulary is the major factor in solving non-verbal problems, not memory, whereas for adolescents with ID, visual STM, and verbal WM are more influential than vocabulary, suggesting different pathways to achieve solutions to non-verbal problems.

Working memory studies among individuals with intellectual disability: An integrative research review

BACKGROUND

Integrative research review infers generalizations about a substantive subject, summarizes the accumulated knowledge that research has left unresolved and generates a new framework on these issues. Due to methodological issues emerging from working memory (WM) studies in the population with non-specific intellectual disability (NSID) (N=64) between 1990-2014, it is difficult to conclude on WM performance in this population.

AIM

This integrative research review aimed to resolve literature conflicts on WM performance among individuals with NSID and to identify the conditions/moderators that govern their WM performance compared to controls with Typical development.

METHOD/PROCEDURE

We used the six stages of integrative research review: problem formulation, data collection, evaluation, data analysis, results, interpretation and discussion.

OUTCOMES AND RESULTS

The findings indicate two types of moderators that determine WM performance in the population with NSID: Participants' moderators (criteria for matching the ID and TD groups, CA and MA), and task moderators [the three WM components of Baddeley and Hitch's (1974) model and task load]. Only an interaction between the two moderators determines WM performance in this population. The findings indicate a hierarchy (from more to less preserved) in WM performance of individuals with NSID: The visuospatial tasks, then some of the executive functions tasks, and the phonological loop tasks being less preserved. Furthermore, at a low level of control, the performance of participants with NSID was preserved beyond the modality and vice versa.

CONCLUSIONS AND IMPLICATIONS

Modality and MA/intelligence determine WM performance of individuals with ID. Educators should prepare intervention programs take the impact of the two moderators into account.

The importance of working memory for school achievement in primary school children with intellectual or learning disabilities

BACKGROUND

Given the well-known relation between intelligence and school achievement we expect children with normal intelligence to perform well at school and those with intelligence deficits to meet learning problems. But, contrary to these expectations, some children do not perform according to these predictions: children with normal intelligence but sub-average school achievement and children with lower intelligence but average success at school. Yet, it is an open question how the unexpected failure or success can be explained.

AIMS

This study examined the role of working memory sensu Baddeley (1986) for school achievement, especially for unexpected failure or success.

METHOD AND PROCEDURES

An extensive working memory battery with a total of 14 tasks for the phonological loop, the visual-spatial sketchpad and central executive skills was presented in individual sessions to four groups of children differing in IQ (normal vs. low) and school success (good vs. poor).

OUTCOMES AND RESULTS

Results reveal that children with sub-average school achievement showed deficits in working memory functioning, irrespective of intelligence. By contrast, children with regular school achievement did not show deficits in working memory, again irrespective of intelligence.

CONCLUSIONS AND IMPLICATIONS

Therefore working memory should be considered an important predictor of academic success that can lead both to unexpected overachievement and failure at school. Individual working memory competencies should be taken into account with regard to diagnosis and intervention for children with learning problems.

Strategic verbal rehearsal in adolescents with mild intellectual disabilities: A multi-centre European study

BACKGROUND

There is a long-held view that verbal short-term memory problems of individuals with intellectual disabilities (ID) might be due to a deficit in verbal rehearsal. However, the evidence is inconclusive and word length effects as indicator of rehearsal have been criticised.

AIM & METHOD

The aim of this multi-site European study was to investigate verbal rehearsal in adolescents with mild ID (n=90) and a comparison group of typically developing children matched individually for mental age (MA, n=90). The investigation involved: (1) a word length experiment with non-verbal recall using pointing and (2) 'self-paced' inspection times to infer whether verbal strategies were utilised when memorising a set of pictorial items.

RESULTS

The word length effect on recall did not interact with group, suggesting that adolescents with ID and MA comparisons used similar verbal strategies, possibly phonological recoding of picture names. The inspection time data suggested that high span individuals in both groups used verbal labelling or single item rehearsal on more demanding lists, as long named items had longer inspection times.

CONCLUSIONS

The findings suggest that verbal strategy use is not specifically impaired in adolescents with mild ID and is mental age appropriate, supporting a developmental perspective.

The impact of behavioural executive functioning and intelligence on math abilities in children with intellectual disabilities

BACKGROUND

Little is known about the role of behavioural executive functioning (EF) skills and level of intelligence (IQ) on math abilities in children with mild to borderline intellectual disabilities.

METHOD

Teachers of 63 children attending a school for special education (age: 10 to 13 years; IQ: 50 to 85) filled out a Behaviour Rating Inventory for Executive Function for each student. Furthermore, students took a standardised national composite math test and a specific math test on measurement and time problems. Information on level of intelligence was gathered through school records. Multiple regression analyses were performed to test direct, moderating and mediating effects of EF and IQ on math performance.

RESULTS

Behavioural problems with working memory and flexibility had a direct negative effect on math outcome, while concurrently, level of intelligence had a positive effect. The effect of IQ on math skills was moderated by problems with inhibition: in children with a clinical level of inhibition problems, there was no effect of level of intelligence on math performance.

CONCLUSIONS

Findings suggest that in students with mild to borderline intellectual disabilities and math difficulties, it is important to address their strengths and weaknesses with respect to EF and adjust instruction and remedial intervention accordingly.

Social Competence in Children with Borderline Intellectual Functioning: Delayed Development of Theory of Mind Across All Complexity Levels

Borderline intellectual functioning (BIF) is characterized by heterogeneous cognitive difficulties, with an intelligence quotient (IQ) between 70 and 85 points, and a failure to meet the developmental and sociocultural standards for personal independence and social responsibility required in daily life. The fact that this population still remain a marginal clinical category, with no ad hoc diagnostic and therapeutic approaches, has stimulated the present research. Our goal was to study children with BIF investigating the development of Theory of Mind (ToM) as a pillar of social competence. Children with BIF (N = 28, 16 male/12 female, and mean age 9.46 ± 1.26 years) and children with typical development (TD; N = 31, 17 male/14 female; mean age 8.94 years ± 0.99) underwent a neurocognitive assessment and a ToM assessment. Children with BIF showed a significant lower performance across all the levels of ToM development investigated compared to the control group, and a correlation between executive functions and the advanced levels of ToM reasoning. These results constitute a first step in the direction of defining the clinical profile of children with BIF concerning ToM development, opening the way to future interventions in order to support the developmental evolution of this population in an adaptive direction.

HPA axis function predicts development of working memory in boys with FXS

The present study examines verbal working memory over time in boys with fragile X syndrome (FXS) compared to nonverbal mental-age (NVMA) matched, typically developing (TD) boys. Concomitantly, the relationship between cortisol-a physiological marker for stress-and verbal working memory performance over time is examined to understand the role of physiological mechanisms in cognitive development in FXS. Participants were assessed between one and three times over a 2-year time frame using two verbal working memory tests that differ in complexity: memory for words and auditory working memory with salivary cortisol collected at the beginning and end of each assessment. Multilevel modeling results indicate specific deficits over time on the memory for words task in boys with FXS compared to TD controls that is exacerbated by elevated baseline cortisol. Similar increasing rates of growth over time were observed for boys with FXS and TD controls on the more complex auditory working memory task, but only boys with FXS displayed an association of increased baseline cortisol and lower performance. This study highlights the benefit of investigations of how dynamic biological and cognitive factors interact and influence cognitive development over time.

The effectiveness of working memory training with individuals with intellectual disabilities - a meta-analytic review

Working memory (WM) training has been increasingly popular in the last years. Previous studies have shown that individuals with intellectual disabilities (ID) have low WM capacity and therefore would benefit by this type of intervention. The aim of this study was to investigate the effect of WM and cognitive training for individuals with ID. The effects reported in previous studies have varied and therefore a meta-analysis of articles in the major databases was conducted. Inclusion criteria included to have a pretest-posttest design with a training group and a control group and to have measures of WM or short-term memory. Ten studies with 28 comparisons were included. The results reveal a significant, but small, overall pretest-posttest effect size (ES) for WM training for individuals with ID compared to controls. A mixed WM approach, including both verbal and visuo-spatial components working mainly on strategies, was the only significant training type with a medium ES. The most commonly reported training type, visuo-spatial WM training, was performed in 60 percent of the included comparisons and had a non-significant ES close to zero. We conclude that even if there is an overall effect of WM training, a mixed WM approach appears to cause this effect. Given the few studies included and the different characteristics of the included studies, interpretations should be done with caution. However, different types of interventions appear to have different effects. Even if the results were promising, more studies are needed to better understand how to design an effective WM intervention for this group and to understand if, and how, these short-term effects remain over time and transfer to everyday activities.

Treating verbal working memory in a boy with intellectual disability

The present case study investigates the effects of a cognitive training of verbal working memory that was proposed for Davide, a 14-year-old boy diagnosed with mild intellectual disability. The program stimulated attention, inhibition, switching, and the ability to engage either in verbal dual tasks or in producing inferences after the content of a short passage had been encoded in episodic memory. Key elements in our program included (1) core training of target cognitive mechanisms; (2) guided practice emphasizing concrete strategies to engage in exercises; and (3) a variable amount of adult support. The study explored whether such a complex program produced "near transfer" effects on an untrained dual task assessing verbal working memory and whether effects on this and other target cognitive mechanisms (i.e., attention, inhibition, and switching) were long-lasting and produced "far transfer" effects on cognitive flexibility. The effects of the intervention program were investigated with a research design consisting of four subsequent phases lasting 8 or 10 weeks, each preceded and followed by testing. There was a control condition (phase 1) in which the boy received, at home, a stimulation focused on the visuospatial domain. Subsequently, there were three experimental training phases, in which stimulation in the verbal domain was first focused on attention and inhibition (phase 2a), then on switching and simple working memory tasks (phase 2b), then on complex working memory tasks (phase 3). A battery of neuropsychological tests was administered before and after each training phase and 7 months after the conclusion of the intervention. The main finding was that Davide changed from being incapable of addressing the dual task request of the listening span test in the initial assessment to performing close to the normal limits of a 13-year-old boy in the follow-up assessment with this test, when he was 15 years old.

Working memory development in children with mild to borderline intellectual disabilities

BACKGROUND

The purpose of the current cross-sectional study was to examine the developmental progression in working memory (WM) between the ages of 9 and 16 years in a large sample of children with mild to borderline intellectual disabilities (MBID). Baddeley's influential WM model was used as a theoretical framework. Furthermore, the relations between WM on the one hand, and scholastic skills (arithmetic and reading) on the other were examined.

METHOD

One hundred and ninety-seven children with MBID between 9 and 16 years old participated in this study. All children completed several tests measuring short-term memory, WM, inhibition, arithmetic and single word reading.

RESULTS

WM, visuospatial short-term memory and inhibition continued to develop until around age 15 years. However verbal short-term memory showed no further developmental increases after the age of 10 years. Verbal short-term memory was associated with single word reading, whereas inhibition was associated with arithmetic.

DISCUSSION

The finding that verbal short-term memory ceases to develop beyond the age of 10 years in children with MBID contrasts with results of studies involving typically developing children, where verbal short-term memory develops until around age 15 years. This relative early developmental plateau might explain why verbal short-term memory is consistently considered weak in children with MBID.

Phonological short-term memory impairment and the word length effect in children with intellectual disabilities

There is mounting evidence that children and adolescents with intellectual disabilities (ID) of nonspecific aetiology perform poorer on phonological short-term memory tasks than children matched for mental age indicating a structural deficit in a process contributing to short-term recall of verbal material. One explanation is that children with ID of nonspecific aetiology do not activate subvocal rehearsal to refresh degrading memory traces. However, existing research concerning this explanation is inconclusive since studies focussing on the word length effect (WLE) as indicator of rehearsal have revealed inconsistent results for samples with ID and because in several existing studies, it is unclear whether the WLE was caused by rehearsal or merely appeared during output of the responses. We assumed that in children with ID only output delays produce a small WLE while in typically developing 6- to 8-year-olds rehearsal and output contribute to the WLE. From this assumption we derived several predictions that were tested in an experiment including 34 children with mild or borderline ID and 34 typically developing children matched for mental age (MA). As predicted, results revealed a small but significant WLE for children with ID that was significantly smaller than the WLE in the control group. Additionally, for children with ID, a WLE was not found for the first word of each trial but the effect emerged only in later serial positions. The findings corroborate the notion that in children with ID subvocal rehearsal does not develop in line with their mental age and provide a potential explanation for the inconsistent results on the WLE in children with ID.

Conceptual abilities of children with mild intellectual disability: analysis of wisconsin card sorting test performance

BACKGROUND

The ability to generate and flexibly change concepts is of great importance for the development of academic and adaptive skills. This paper analyses the conceptual reasoning ability of children with mild intellectual disability (MID) by their achievements on the Wisconsin Card Sorting Test (WCST).

METHOD

The sample consisted of 95 children with MID aged between 10 years and 13 years 11 months. The following variables from the WCST were analysed: number of categories completed, initial conceptualisation, total number of errors, non-perseverative errors, perseverative errors, number of perseverative responses, and failures to maintain set.

RESULTS

The observed WCST predictive variables account for 79% of the variability in the number of categories completed (p < .000). The total number of errors was the most significant predictor of performance on the WCST.

CONCLUSION

We can conclude that there is a significant progress of conceptual abilities between the age of 13 years to 13 years 11 months, compared to other assessed age groups. The results of our research suggests that the development of mental set flexibility is the basis of progress in conceptual abilities, thus intervention programs should offer specially designed activities that vary in their attentional demands, content, conceptual patterns, and actions required.

Math practice and its influence on math skills and executive functions in adolescents with mild to borderline intellectual disability

Adolescents with mild to borderline intellectual disability (MBID) often complete schooling without mastering basic math skills, even though basic math is essential for math-related challenges in everyday life. Limited attention to cognitive skills and low executive functioning (EF) may cause this delay. We aimed to improve math skills in an MBID-sample using computerized math training. Also, it was investigated whether EF and math performance were related and whether computerized math training had beneficial effects on EF. The sample consisted of a total of 58 adolescents (12-15 years) from special education. Participants were randomly assigned to either the experimental group or a treatment as usual (TAU) group. In the experimental condition, participants received 5 weeks of training. Math performance and EF were assessed before and after the training period. Math performance improved equally in both groups. However, frequently practicing participants improved more than participants in the control group. Visuo-spatial memory skills were positively related to addition and subtraction skills. Transfer effects from math training to EF were absent. It is concluded that math skills may increase if a reasonable effort in practicing math skills is made. The relation between visuo-spatial memory skills provides opportunities for improving math performance.

Contributions of phonological awareness, phonological short-term memory, and rapid automated naming, toward decoding ability in students with mild intellectual disability

Reading decoding ability is a fundamental skill to acquire word-specific orthographic information necessary for skilled reading. Decoding ability and its underlying phonological processing skills have been heavily investigated typically among developing students. However, the issue has rarely been noticed among students with intellectual disability who commonly suffer from reading decoding problems. This study is aimed at determining the contributions of phonological awareness, phonological short-term memory, and rapid automated naming, as three well known phonological processing skills, to decoding ability among 60 participants with mild intellectual disability of unspecified origin ranging from 15 to 23 years old. The results of the correlation analysis revealed that all three aspects of phonological processing are significantly correlated with decoding ability. Furthermore, a series of hierarchical regression analysis indicated that after controlling the effect of IQ, phonological awareness, and rapid automated naming are two distinct sources of decoding ability, but phonological short-term memory significantly contributes to decoding ability under the realm of phonological awareness.

Individuals with intellectual disability can self-teach in reading

Previous research has suggested that individuals with intellectual disability (ID) underperform in several areas of reading compared to mental age-matched peers. However, it is unclear how they compare on orthographic aspects of reading, which have to do with learning and matching the specific letter patterns in words. The leading approach to understanding orthographic learning is the self-teaching hypothesis, which suggests that orthographic learning is acquired through the experience of phonologically recoding words. The present study was a first test of the self-teaching hypothesis for individuals with ID in comparison to a group of typically developing children matched on verbal mental age. Results indicated that both groups were able to self-teach.

Strengths and weaknesses in reading skills of youth with intellectual disabilities

Reading-related skills of youth with intellectual disability (ID) were compared with those of typically developing (TD) children of similar verbal ability level. The group with ID scored lower than the TD group on word recognition and phonological decoding, but similarly on orthographic processing and rapid automatized naming (RAN). Further, phonological decoding significantly mediated the relation between group membership and word recognition, whereas neither orthographic processing nor RAN did so. The group with ID also underperformed the TD group on phonological awareness and phonological memory, both of which significantly mediated the relation between group membership and phonological decoding. These data suggest that poor word recognition in youth with ID may be due largely to poor phonological decoding, which in turn may be due largely to poor phonological awareness and poor phonological memory. More focus on phonological skills in the classroom may help students with ID to develop better word recognition skills.

Strengths and weaknesses in executive functioning in children with intellectual disability

Children with intellectual disability (ID) were given a comprehensive range of executive functioning measures, which systematically varied in terms of verbal and non-verbal demands. Their performance was compared to the performance of groups matched on mental age (MA) and chronological age (CA), respectively. Twenty-two children were included in each group. Children with ID performed on par with the MA group on switching, verbal executive-loaded working memory and most fluency tasks, but below the MA group on inhibition, planning, and non-verbal executive-loaded working memory. Children with ID performed below CA comparisons on all the executive tasks. We suggest that children with ID have a specific profile of executive functioning, with MA appropriate abilities to generate new exemplars (fluency) and to switch attention between tasks, but difficulties with respect to inhibiting pre-potent responses, planning, and non-verbal executive-loaded working memory The development of different types of executive functioning skills may, to different degrees, be related to mental age and experience.

Phonological and Visuospatial Short-Term Memory in Children With Specific Language Impairment

An investigation was carried out into the phonological short-term memory (PSTM) and visuospatial short-term memory (VSSTM) skills of children with specific language impairment (SLI; n = 41) using memory span tasks. Individuals with SLI were compared with children who had milder degrees of language difficulty (“low language functioning” [LLF]; n = 31) and children with typical development (n = 88). Regression analyses examined the effects of group after controlling for age and nonverbal IQ; further regressions included an additional control for verbal IQ. Even after controlling for all of these variables, children with SLI and LLF showed significantly weaker PSTM than children with typical development. For VSSTM, there were no overall group differences in performance. The findings imply that the PSTM difficulties that have been reported in children with SLI are substantial, whereas VSSTM appears to be an area of relative strength for most children with SLI.

Relationships Between Working Memory and Academic Skills: Are There Differences Between Children With Intellectual Disabilities and Typically Developing Children?

In typically developing children, working memory is linked to academic skills. However, little is known about the role working memory plays for learning in children with intellectual disabilities (ID). Therefore, the aims of this study were to examine whether different working memory functions are related to reading, spelling, and calculating in children with ID of nonspecific etiology and whether these relationships are different from the ones found in typically developing children. Forty-seven children with mild-to-borderline ID and 47 children matched for mental age were tested. Although in typically developing children, only phonological short-term memory tasks were predictive for literacy, for children with ID, visuospatial working memory tasks also accounted for variance. In typically developing children, calculation skills were predicted by phonological working memory tasks, whereas visuospatial working memory resources were crucial for children with ID. Several possible explanations are discussed for discrepancies in prediction patterns.

The more you remember the more you decide: collaborative memory in adolescents with intellectual disability and their assistants

The aim of the present study was to investigate collaborative memory in adolescents with intellectual disabilities when collaborating with an assistant, and also the extent to which decisiveness is related to individual memory performance. Nineteen students with intellectual disabilities (mean age=18.5, SD=0.9) each collaborated with a teaching assistant (mean age 40.3, SD=12.1) familiar from everyday work in school. Pictures were presented individually. Recognition was performed in two parts, first individually and thereafter collaboratively. The design involved 2 settings, one natural (with equal encoding time) and another with equal individual memory performance (assistants had shorter encoding time than the students). Results showed collaborative inhibition in this previously uninvestigated collaboration setting with adolescents with intellectual disabilities and their assistants. The assistants both performed higher and decided more than the students with intellectual disabilities in the natural setting, but not in the equated performance setting. Inhibition was larger in the equated setting. The assistants' decisiveness was moderately correlated with individual memory performance. Implications for everyday life are discussed.

Working memory subsystems and task complexity in young boys with Fragile X syndrome

BACKGROUND

Working memory problems have been targeted as core deficits in individuals with Fragile X syndrome (FXS); however, there have been few studies that have examined working memory in young boys with FXS, and even fewer studies that have studied the working memory performance of young boys with FXS across different degrees of complexity. The purpose of this study was to investigate the phonological loop and visual-spatial working memory in young boys with FXS, in comparison to mental age-matched typical boys, and to examine the impact of complexity of the working memory tasks on performance.

METHODS

The performance of young boys (7 to 13-years-old) with FXS (n = 40) was compared with that of mental age and race matched typically developing boys (n = 40) on measures designed to test the phonological loop and the visuospatial sketchpad across low, moderate and high degrees of complexity. Multivariate analyses were used to examine group differences across the specific working memory systems and degrees of complexity.

RESULTS

Results suggested that boys with FXS showed deficits in phonological loop and visual-spatial working memory tasks when compared with typically developing mental age-matched boys. For the boys with FXS, the phonological loop was significantly lower than the visual-spatial sketchpad; however, there was no significant difference in performance across the low, moderate and high degrees of complexity in the working memory tasks. Reverse tasks from both the phonological loop and visual-spatial sketchpad appeared to be the most challenging for both groups, but particularly for the boys with FXS.

CONCLUSIONS

These findings implicate a generalised deficit in working memory in young boys with FXS, with a specific disproportionate impairment in the phonological loop. Given the lack of differentiation on the low versus high complexity tasks, simple span tasks may provide an adequate estimate of working memory until greater involvement of the central executive is achieved.

Executive functions in individuals with intellectual disability

The aim of the present study was to investigate executive functions in adults with intellectual disability, and compare them to a closely matched control group longitudinally for 5 years. In the Betula database, a group of adults with intellectual disability (ID, n=46) was defined from measures of verbal and non-verbal IQ. A control group, with two people for every person with intellectual disability (n=92), was chosen by matching on the following criterion in order of priority: IQ higher than 85, age, sex, sample, level of education, and years of education. Three types of tasks of executive functions were included on two occasions, with 5 years between testing sessions: The Tower of Hanoi, executively loaded dual task versions of word recall, and verbal fluency. Adults with ID showed significant impairments on verbal fluency and on the executively loaded dual task word recall task (at encoding but not at recall). There were no group differences on the Tower of Hanoi. No significant differences between the two test occasions were found. The results are interpreted in terms of individuals with ID having problems with speed of accessing lexical items and difficulties with working memory-related executive control at encoding, which includes shifting between tasks. There are, however, not necessarily problems with inhibition. The dual task results additionally imply that the adults with intellectual disability were more sensitive to strategy interruptions at encoding, but that dividing attention at recall did not have such detrimental effects.

The episodic buffer in children with intellectual disabilities: an exploratory study

Performance on three verbal measures (story recall, paired associated learning, category fluency) designed to assess the integration of long-term semantic and linguistic knowledge, phonological working memory and executive resources within the proposed 'episodic buffer' of working memory (Baddeley, 2007) was assessed in children with intellectual disabilities (ID). It was hypothesised that children with ID would show equivalent performance to typically developing children of the same mental age. This prediction was based on the hypothesis that, despite poorer phonological short-term memory than mental age matched peers, those with ID may benefit from more elaborate long-term memory representations, because of greater life experience. Children with ID were as able as mental age matched peers to remember stories, associate pairs of words together and generate appropriate items in a category fluency task. Performance did not, however, reach chronological age level on any of the tasks. The results suggest children with ID perform at mental age level on verbal 'episodic buffer' tasks, which require integration of information from difference sources, supporting a 'delayed' rather than 'different' view of their development.