Specific impairment in developmental reading disabilities: a working memory approach

The Role of Working Memory in Early Literacy and Numeracy Skills in Kindergarten and First Grade

The working memory system supports learning processes such as acquiring new information and the development of new skills. Working memory has been found to be related to both early literacy and early numeracy in kindergarten and to linguistic and mathematical academic skills at older ages, but the contribution of each of the memory components at these ages is not yet clear. The purpose of this study is to examine the unique connections among the various systems of WM, early literacy, and early numeracy using various assessment tests of simple WM and complex WM, as well as a variety of tasks in math and language skills administered to the same 250 children in kindergarten and 150 children in first grade. Consistent with the predictions, significant relations among all components of memory and mathematics and language knowledge at both ages were found, although these connections were differential for the different types of tasks and memory systems. The connection of complex WM was stronger in its contribution and more significant in first grade in both mathematics and language domains. Complex WM resources were more important in early literacy at kindergarten age, while simple WM seems to be important in early numeracy. The theoretical and educational implications of these results are discussed accordingly.

Revisiting Multifactor Models of Dyslexia: Do They Fit Empirical Data and What Are Their Implications for Intervention?

Developmental dyslexia can be viewed as the result of the effects of single deficits or multiple deficits. This study presents a test of the applicability of a multifactor-interactive model (MFi-M) with a preliminary set of five variables corresponding to different neuropsychological functions involved in the reading process. The model has been tested on a sample of 55 school-age children with developmental dyslexia. The results show that the data fit a model in which each variable contributes to the reading ability in a non-additive but rather interactive way. These findings constitute a preliminary validation of the plausibility of the MFi-M, and encourage further research to add relevant factors and specify their relative weights. It is further discussed how subtype-based intervention approaches can be a suitable and advantageous framework for clinical intervention in a MFi-M perspective.

The Cognitive Ability of Chinese Students with Dyslexia and Mathematical Learning Disabilities

This study aims to investigate the core cognitive factors that affect reading and math performance of children of the grades 1-6 in Xi'an, Shaanxi Province, China, as well as the differences between children with dyslexia and mathematical disabilities (MD). Therefore, this study mainly evaluated the Cattell Horn Carroll (CHC) cognitive factors for 427 Chinese children and explored the core cognitive factors that affect Chinese children's reading and math performance. Students with dyslexia (n = 34), students with mathematics learning disabilities (n = 34), and 34 normal children were randomly selected as the control group. In order to explore the differences in cognitive development, we analyzed the differences among the three groups (Dyslexia, mathematical learning disabilities (MD), and normal children). The results revealed the following: (1) almost all cognitive ability factors in this study are significantly related to students' reading and mathematical achievements. (2) the core cognitive factors for predicting Chinese dyslexia students are crystallized intelligence, auditory processing and working memory. Executive function, spatial relationship and working memory are the core cognitive factors to predict Chinese children's mathematical achievements. (3) in addition, there are differences in cognitive deficits between disabled Chinese children in reading and math, among which those with reading deficits have extensive auditory processing deficits; while children with mathematic deficits have worse executive function. Recommendations were made based on these findings.

WISC-IV and Rey Auditory Verbal Learning Test Indicators of Specific Learning Disorder and Discrepant Academic Achievement

Though several studies have been undertaken to explore the correlates of academic achievement, there is a dearth of studies relating to the cognitive profiles of children who show marked discrepancies between their cognitive potential and actual academic achievement. The present study was undertaken in this context. The study was conducted on a sample of 308 students in the age range of 12–16 years, drawn from different schools in Kerala, India. The participants belonged to four groups, that is, Underachievers, Normal achievers, Overachievers, and those with Specific Learning Disorders (SLD). WISC-IV India and Rey Auditory Verbal Learning Test (RAVLT) were used for assessing cognitive functions. Results indicated that the SLD group could be discriminated from the other three groups in terms of Digit span, Letter-Number sequencing, Working Memory Index, and Processing Speed Index. Further, a retention score obtained from RAVLT could discriminate between the SLD and UA groups. Discriminant analysis of the variables resulted in the extraction of two significant functions composed of three variables of WISC and two variables of RAVLT. The results indicated that the different groups of scholastically backward children, though similar in their overall IQ, had distinct and characteristic cognitive profiles.

Specific Cues Can Improve Procedural Learning and Retention in Developmental Coordination Disorder and/or Developmental Dyslexia

The present study investigates procedural learning of motor sequences in children with developmental coordination disorder (DCD) and/or developmental dyslexia (DD), typically-developing children (TD) and healthy adults with a special emphasis on (1) the role of the nature of stimuli and (2) the neuropsychological functions associated to final performance of the sequence. Seventy children and ten adults participated in this study and were separated in five experimental groups: TD, DCD, DD, and DCD + DD children and adults. Procedural learning was assessed with a serial reaction time task (SRTT) that required to tap on a specific key as accurately and quickly as possible when stimuli appeared on the screen. Three types of stimuli were proposed as cues: the classical version of the SRTT with 4 squares aligned horizontally on the screen, giving visuospatial cues (VS cues), and two modified versions, with 4 letters aligned horizontally on the screen (VS + L cues) and letters at the center of the screen (L cues). Reaction times (RT) during the repeated and random blocks allowed assessing three phases of learning: global learning, specific learning and retention of the sequence. Learning was considered as completed when RT evolved significantly in the three phases. Neuropsychological assessment involved, among other functions, memory and attentional functions. Our main result was that learning and retention were not influenced by the available cues in adults whereas learning improved with specific cues in children with or without neurodevelopmental disorders. More precisely, learning was not completed with L cues in children with neurodevelopmental disorders. For children with DD, learning was completed with the VS and VS + L cues whereas for children with DCD (with or without DD), learning was completed with combined VS + L cues. Comorbidity between DD and DCD had no more impact on procedural learning than DCD alone. These results suggest that learning depends on the nature of cues available during practice and that cues allowing learning and retention depend on the type of disorder. Moreover, selective attention was correlated with RT during retention, suggesting that this neuropsychological function is important for procedural learning whatever the available cues.

The Influence of Articulatory Suppression on Reading Among Chinese Children With Developmental Dyslexia: An Eye-Movement Study

Objective: The study aimed to examine how the phonological loop influences reading ability and processing in Chinese children with developmental dyslexia (DD). Methods: This study included 30 children with DD and 37 children without DD. Two types of articles (i.e., scenery prose and narrative story) and two conditions (under the conditions of articulatory-suppression and silent reading) were applied. An eye-link II High-Speed Eye Tracker was used to track a series of eye-movement parameters. The data were analyzed by the linear Mixed-Effects model. Results: Compared with children without DD, Children with DD had lower reading achievement (RA), frequency of saccades (FS) and frequency of fixations (FF), longer reading time (RT) and average fixation duration (AFD), slower reading speed (RS), shorter average saccade amplitude (ASA) and fixation distance (FD), more number of fixations (NF), and number of saccades (NS). There were significant interactions between participant group and articulatory suppression on RT and FD. We also observed interaction effects between article types and articulatory suppression on RA, AFD, ASA, and FS. Conclusion: Children DD exhibit abnormal phonological loop and eye movements while reading. The role of articulatory suppression on reading varies with the presentation of DD and the article type.

Working memory profiles of children with reading difficulties who are learning to read in Greek

This study investigated working memory skills in a small group of 13 nine-year-old Greek children facing reading difficulties and a group of 14 age matched typical Greek readers. The children were assessed on working memory tasks measuring separately the four components of the working memory model of Baddeley and Hitch (1974) as revised by Baddeley (2000): the phonological loop, visuo-spatial sketchpad, episodic buffer and central executive. Both groups completed tests of accuracy of reading, speed of reading and text understanding. The children with reading difficulties performed significantly more poorly than typical readers on all aspects of working memory apart from visual-spatial short-term memory. These results indicate a similar verbal working memory impairment in Greek children with reading difficulties as in their English peers, despite the fact that they are learning to read a language with a transparent rather than an opaque orthography.

Comprehension and Eye Movements in the Processing of Subject- and Object-Relative Clauses: Evidence from Dyslexia and Individual Differences

In this study, we examined eye movements and comprehension in sentences containing a relative clause. To date, few studies have focused on syntactic processing in dyslexia and so one goal of the study is to contribute to this gap in the experimental literature. A second goal is to contribute to theoretical psycholinguistic debate concerning the cause and the location of the processing difficulty associated with object-relative clauses. We compared dyslexic readers (n = 50) to a group of non-dyslexic controls (n = 50). We also assessed two key individual differences variables (working memory and verbal intelligence), which have been theorised to impact reading times and comprehension of subject- and object-relative clauses. The results showed that dyslexics and controls had similar comprehension accuracy. However, reading times showed participants with dyslexia spent significantly longer reading the sentences compared to controls (i.e., a main effect of dyslexia). In general, sentence type did not interact with dyslexia status. With respect to individual differences and the theoretical debate, we found that processing difficulty between the subject and object relatives was no longer significant when individual differences in working memory were controlled. Thus, our findings support theories, which assume that working memory demands are responsible for the processing difficulty incurred by (1) individuals with dyslexia and (2) object-relative clauses as compared to subject relative clauses.

Is executive dysfunction a potential contributor to the comorbidity between basic reading disability and attention-deficit/hyperactivity disorder?

Our study is one of the few to analyze executive functioning (EF) in a comprehensive, multi-modal fashion as a potential contributor to the comorbidity between attention-deficit/hyperactivity disorder (ADHD) and basic reading disability (RD). We included multiple, traditional, neuropsychological measures of EF, along with the Behavior Rating Inventory of Executive Function (BRIEF) questionnaire, to assess inhibit, shift, working memory (WM), planning, generation fluency, and problem-solving. Participants included 263 children, ages 8-12 years, with RD, ADHD, RD/ADHD, and typically developing controls. When using the traditional measures in a 2 × 2 MANCOVA, we found both RD and ADHD had poor cognitive EF in most areas at the group level, with phonological loop deficits being more specific to RD and behavioral regulation deficits being more specific to ADHD. Children with RD/ADHD performed comparably to those with RD and ADHD alone. Results were similar on the BRIEF. In contrast, only WM predicted both basic reading and inattention when the data were assessed in a continuous fashion. It also explained the correlations between basic reading and inattention, being worthy of longitudinal research to determine if it is a shared contributor to RD/ADHD. When comparing hypotheses as to the nature of RD/ADHD, we found the multiple deficit hypothesis was better supported by our EF data than the phenocopy hypothesis or the cognitive subtype hypothesis.

The Moderation Effect of Processing Efficiency on the Relationship Between Visual Working Memory and Chinese Character Recognition

To investigate the underlying mechanism of the relationship between visual working memory (VWM) and Chinese character recognition, and the moderation effect of processing efficiency on this relationship, 154 first-grade students were administered a battery of tasks for VWM, rapid temporal processing, and Chinese character reading. In the VWM task, the children were asked to remember the jumping routes of a frog and report these routes in reverse sequence. The longest span for which each participant could respond correctly at least four times out of six was the VWM index. In the task of temporal order judgement, the participants were asked to select which of two balls was presented first, with stimulus onset asynchronies varying from 8 to 492 ms according to an adaptive psychophysical procedure. Visual temporal order threshold (VTOT) was utilized as an indicator of processing efficiency. The participants were asked to read 100 characters aloud to measure their word-level reading abilities in Chinese character recognition. After controlling age, non-verbal intelligence, visual short-term memory, morphological awareness, and orthographic awareness, the results of a moderation effect analysis showed that (1) both VWM and visual VTOT predicted Chinese character reading, and (2) the moderation effect of VTOT on the VWM-reading link was significant (p = 0.001). The correlation between VWM and Chinese character reading was positive and significant when VTOTs were above average (i.e., smaller than 87.14 ms); however, the correlation was negative at relatively poor levels of VTOTs (i.e., larger than 231.44 ms).

Reading-related abilities underlying phonological awareness: a cross-sectional study in children with and without dyslexia

PURPOSE

The present cross-sectional study examined the individual role of rapid automatized naming (RAN), verbal short-term memory (VSTM), and phonological verbal fluency (PVF) along with word reading performance in predicting phonological awareness (PA).

MATERIALS AND METHODS

A total of 225 Arabic speaking children from grades 2, 3, 4 and 5 took part in this study, divided into two groups of readers: typical developing readers and dyslexic readers. The participants were tested on word and pseudoword reading, phonological awareness, rapid naming, verbal short-term memory and phonological verbal fluency.

RESULTS

There are different predictive patterns between the two groups. Whereas Raven and Grade contributed directly in predicting PA in typical readers, VSTM and PVF directly predicted PA in children with dyslexia. However, word reading played a dual role in the both groups as direct predictors of PA, mediating the predictive relationships between PA and the other variables.

CONCLUSION

The results suggest the potential existence of an underlying phonological representation processing ability shared between PA, phonological access (RAN and PVF), VSTM, and word reading ability.

Frontal volume as a potential source of the comorbidity between attention-deficit/hyperactivity disorder and reading disorders

Prefrontal volume reductions commonly are demonstrated in ADHD, but the literature examining prefrontal volume in reading disorders (RD) is scant despite their also having executive functioning (EF) deficits. Furthermore, only a few anatomical studies have examined the frontal lobes in comorbid RD/ADHD, though they have EF deficits similar to RD and ADHD. Hence, we examined frontal gyri volume in children with RD, ADHD, RD/ADHD and controls, as well as their relationship to EF for gyri found to differ between groups. We found right inferior frontal (RIF) volume was smaller in ADHD, and smaller volume was related to worse behavioral regulation. Left superior frontal (LSF) volume was larger in RD than ADHD, and its size was negatively related to basic reading ability. Left middle frontal (LMF) volume was largest in RD/ADHD overall. Further, its volume was not related to basic reading nor behavioral regulation but was related to worse attentional control, suggesting some specificity in its EF relationship. When examining hypotheses on the etiology of RD/ADHD, RD/ADHD was commensurate with ADHD in RIF volume and both RD and ADHD in LSF volume (being midway between the groups), consistent with the common etiology hypothesis. Nevertheless, they also had an additional gyrus affected: LMF, consistent with the cognitive subtype hypothesis in its specificity to RD/ADHD. The few other frontal aMRI studies on RD/ADHD supported both hypotheses as well. Given this, future research should continue to focus on frontal morphology in its endeavors to find neurobiological contributors to the comorbidity between RD and ADHD.

Parental perspectives on inclusive education for children with intellectual disabilities in Greece

The current study explores the parental perspectives of children with intellectual disabilities (ID) on the effectiveness of inclusive education in Greek mainstream schools. The participants were 83 parents, whose children had different degrees of ID and all of them were attending mainstream schools at the time of the study. They completed a questionnaire examining their perspectives with regard to (a) the most effective educational placement in mainstream schools (special class, mainstream class or co-teaching), (b) their satisfaction with the inclusive mainstream education, (c) their cooperation with the teachers, (d) the perceived benefits of their children's educational placement and (e) their suggestions regarding the improvement of the inclusive educational model. Results indicated that most parents of children with ID would like their child to attend a mainstream class with a co-teaching arrangement. The perceived benefits are mostly related to the development of their children's social skills. Significant considerations regarding cooperation with the teachers, lack of individualized information and guidance, administrative and organizational issues were expressed.

Phonological and Semantic Contributions to Verbal Short-Term Memory in Young Children With Developmental Stuttering

Purpose The purpose of this study was to examine the verbal short-term memory skills of children who stutter (CWS) and children who do not stutter (CWNS) in 2 experiments, focusing on the influence of phonological and semantic similarity. Method Participants were 42 CWS and 42 CWNS between the ages of 3;0 and 5;11 (years;months). In Experiment 1, children completed the phonological similarity task, in which they listened to lists of phonologically similar and dissimilar words and then repeated them when signaled to do so. In Experiment 2, children completed another forward span task, the semantic category task, which is similar to the phonological similarity task, except that it consisted of lists of semantically homogeneous and heterogeneous words. Main dependent variables were cumulative memory span, proportion of errors by type, and speech reaction time (SRT) for correct responses. Results The CWS exhibited significantly shorter memory spans for phonologically dissimilar words and were less affected by the phonological qualities of the words than the CWNS in Experiment 1, based on the findings of both between-groups and within-group analyses. In Experiment 2, although the groups did not differ in their performance in either condition, within-group analyses revealed that the CWNS benefitted from semantic similarity, whereas the CWS did not. The between-groups difference in absolute difference scores, however, did not reach significance. The CWS produced more omissions and false alarms than the CWNS in both experiments, but the 2 groups of children were otherwise comparable in SRT, although the CWS exhibited overall faster SRT than the CWNS in Experiment 2. Conclusions Verbal short-term memory is one domain-general cognitive process in which CWS display weakness relative to typically fluent peers. These weaknesses are likely due, in part, to differences in phonological and, perhaps, semantic processing of words to aid memory.

Training Working Memory of Children with and without Dyslexia

For the future school performance of a child in the fields of literacy and numeracy, the operational efficiency of working memory is a central predictor. Children affected by dyslexia exhibit specific deficits in the functions of working memory. A software application for elementary school-age children has been specifically developed for this study, attempting to improve the working memory's operational efficiency. Based on Baddeley's model of working memory (1986), the phonological loop, the visuo-spatial sketchpad, and the central executive were trained in 18 sessions over a period of six weeks. The group of test subjects undergoing this training was composed of third-graders, of which 43 were and 27 were not affected by dyslexia. The untrained control group was made up of 41 third-graders with dyslexia and 28 without dyslexia. While the short-term effects of the program could not be proven, the present analyses focus on long-term effects. The results obtained from a pre-test/follow-up design reveal that no long-term increases in performance regarding phonological and central executive working memory could be confirmed. Only the visuo-spatial Corsi block span exhibited a training effect over a period of three months. Additionally, training did not show any long-term effect of performance improvement, not even for a subgroup of children with dyslexia and an especially low working memory performance. Thus, even after this study, the question whether working memory can be trained or not remains partly unanswered but leaves us predominantly pessimistic.

[Verbal and visual-spatial memory in Chinese children with developmental dyslexia]

OBJECTIVE

To explore the abilities of verbal and visual-spatial memory in Chinese children with developmental dyslexia.

METHODS

Thirty-two children with developmental dyslexia (aged 8-12 years) and thirty-nine age- and gender-matched normal children were involved in the study. Their verbal short-term and verbal working memories were measured using the digit ordering and the digit span tests, respectively. Their visual-spatial short-term and visual-spatial working memories were examined using the forward and backward block-tapping tests, respectively.

RESULTS

The DD children scored lower in the digit ordering and the digit span tests than the control children (P<0.05). The scores for the forward and backward block-tapping tests did not vary between the two groups (P>0.05).

CONCLUSIONS

The children with DD have the deficits in both verbal short-term memory and verbal working memory.

Spoken sentence production in college students with dyslexia: working memory and vocabulary effects

BACKGROUND

Individuals with dyslexia demonstrate syntactic difficulties on tasks of language comprehension, yet little is known about spoken language production in this population.

AIMS

To investigate whether spoken sentence production in college students with dyslexia is less proficient than in typical readers, and to determine whether group differences can be attributable to cognitive differences between groups.

METHODS & PROCEDURES

Fifty-one college students with and without dyslexia were asked to produce sentences from stimuli comprising a verb and two nouns. Verb types varied in argument structure and morphological form and nouns varied in animacy. Outcome measures were precision (measured by fluency, grammaticality and completeness) and efficiency (measured by response times). Vocabulary and working memory tests were also administered and used as predictors of sentence production performance.

OUTCOMES & RESULTS

Relative to non-dyslexic peers, students with dyslexia responded significantly slower and produced sentences that were significantly less precise in terms of fluency, grammaticality and completeness. The primary predictors of precision and efficiency were working memory, which differed between groups, and vocabulary, which did not.

CONCLUSIONS & IMPLICATIONS

College students with dyslexia were significantly less facile and flexible on this spoken sentence-production task than typical readers, which is consistent with previous studies of school-age children with dyslexia. Group differences in performance were traced primarily to limited working memory, and were somewhat mitigated by strong vocabulary.

Cognitive and familial risk evidence converged: A data-driven identification of distinct and homogeneous subtypes within the heterogeneous sample of reading disabled children

The evident degree of heterogeneity observed in reading disabled children has puzzled reading researchers for decades. Recent advances in the genetic underpinnings of reading disability have indicated that the heritable, familial risk for dyslexia is a major risk factor. The present data-driven, classification attempt aims to revisit the possibility of identifying distinct cognitive deficit profiles in a large sample of second to fourth grade reading disabled children. In this sample, we investigated whether genetic and environmental risk factors are able to distinguish between poor reader subtypes. In this profile, we included reading-related measures of phonemic awareness, letter-speech sound processing and rapid naming, known as candidate vulnerability markers associated with dyslexia and familial risk for dyslexia, as well as general cognitive abilities (non-verbal IQ and vocabulary). Clustering was based on a 200 multi-start K-means approach. Results revealed four emerging subtypes of which the first subtype showed no cognitive deficits underlying their poor reading skills (Reading-only impaired poor readers). The other three subtypes shared a core phonological deficit (PA) with a variable and discriminative expression across the other underlying vulnerability markers. More specific, type 2 showed low to poor performance across all reading-related and general cognitive abilities (general poor readers), type 3 showed a specific letter-speech sound mapping deficit next to a PA deficit (PA-LS specific poor readers) and type 4 showed a specific rapid naming deficit complementing their phonological weakness (PA-RAN specific poor readers). The first three poor reader profiles were more characterized by variable environmental risk factor, while the fourth, PA-RAN poor reader subtype showed a significantly strong familial risk for dyslexia. Overall, when we zoom in on the heterogeneous phenomenon of reading disability, unique and distinct cognitive subtypes can be identified, distinguishing between those poor readers more influences by the role of genes and those more influenced by environmental risk factors. Taking into account this diversity of distinct cognitive subtypes, instead of looking at the reading disabled sample as a whole, will help tailor future diagnostic and intervention efforts more specifically to the needs of children with such a specific deficit and risk pattern, as well as providing a more promising way forward for genetic studies of dyslexia.

Executive functions in adults with developmental dyslexia

BACKGROUND

Executive functioning (EF) deficits are well recognized in developmental dyslexia, yet the majority of studies have concerned children rather than adults, ignored the subjective experience of the individual with dyslexia (with regard to their own EFs), and have not followed current theoretical perspectives on EFs.

AIMS AND METHODS

The current study addressed these shortfalls by administering a self-report measure of EF (BRIEF-A; Roth, Isquith, & Gioia, 2005) and experimental tasks to IQ-matched groups of adults with and without dyslexia. The laboratory-based tasks tested the three factors constituting the framework of EF proposed by Miyake et al. (2000).

RESULTS

In comparison to the group without dyslexia, the participants with dyslexia self-reported more frequent EF problems in day-to-day life, with these difficulties centering on metacognitive processes (working memory, planning, task monitoring, and organization) rather than on the regulation of emotion and behaviour. The participants with dyslexia showed significant deficits in EF (inhibition, set shifting, and working memory).

CONCLUSIONS AND IMPLICATIONS

The findings indicated that dyslexia-related problems have an impact on the daily experience of adults with the condition. Further, EF difficulties are present in adulthood across a range of laboratory-based measures, and, given the nature of the experimental tasks presented, extend beyond difficulties related solely to phonological processing.

Visual processing in reading disorders and attention-deficit/hyperactivity disorder and its contribution to basic reading ability

Whether visual processing deficits are common in reading disorders (RD), and related to reading ability in general, has been debated for decades. The type of visual processing affected also is debated, although visual discrimination and short-term memory (STM) may be more commonly related to reading ability. Reading disorders are frequently comorbid with ADHD, and children with ADHD often have subclinical reading problems. Hence, children with ADHD were used as a comparison group in this study. ADHD and RD may be dissociated in terms of visual processing. Whereas RD may be associated with deficits in visual discrimination and STM for order, ADHD is associated with deficits in visual-spatial processing. Thus, we hypothesized that children with RD would perform worse than controls and children with ADHD only on a measure of visual discrimination and a measure of visual STM that requires memory for order. We expected all groups would perform comparably on the measure of visual STM that does not require sequential processing. We found children with RD or ADHD were commensurate to controls on measures of visual discrimination and visual STM that do not require sequential processing. In contrast, both RD groups (RD, RD/ADHD) performed worse than controls on the measure of visual STM that requires memory for order, and children with comorbid RD/ADHD performed worse than those with ADHD. In addition, of the three visual measures, only sequential visual STM predicted reading ability. Hence, our findings suggest there is a deficit in visual sequential STM that is specific to RD and is related to basic reading ability. The source of this deficit is worthy of further research, but it may include both reduced memory for order and poorer verbal mediation.

Reasoning and dyslexia: is visual memory a compensatory resource?

Effective reasoning is fundamental to problem solving and achievement in education and employment. Protocol studies have previously suggested that people with dyslexia use reasoning strategies based on visual mental representations, whereas non-dyslexics use abstract verbal strategies. This research presents converging evidence from experimental and individual differences perspectives. In Experiment 1, dyslexic and non-dyslexic participants were similarly accurate on reasoning problems, but scores on a measure of visual memory ability only predicted reasoning accuracy for dyslexics. In Experiment 2, a secondary task loaded visual memory resources during concurrent reasoning. Dyslexics were significantly less accurate when reasoning under conditions of high memory load and showed reduced ability to subsequently recall the visual stimuli, suggesting that the memory and reasoning tasks were competing for the same visual cognitive resource. The results are consistent with an explanation based on limitations in the verbal and executive components of working memory in dyslexia and the use of compensatory visual strategies for reasoning. There are implications for cognitive activities that do not readily support visual thinking, whether in education, employment or less formal everyday settings.

Development of reading and phonological skills of children at family risk for dyslexia: a longitudinal analysis from kindergarten to sixth grade

The main focus of this article is to develop a better understanding of the developmental trajectories of literacy and phonological skills within Dutch-speaking children. Children at high and low risk for dyslexia were followed and compared at four different moments: kindergarten and first, third and sixth grades. Three groups were then compared: (1) dyslexic readers; (2) normal readers at high risk for dyslexia; and (3) normal readers at low risk for dyslexia. Children diagnosed with dyslexia scored lower than high-risk normal readers on phonological awareness (PA), rapid automatized naming (RAN), verbal short-term memory and literacy skills. Normal readers at high risk scored between both groups, confirming that dyslexia is to be considered as a continuum rather than an all-or-none condition. Growth analyses showed that the three groups evolved similarly on all measures except for phoneme deletion and literacy measures. Finally, solely PA and RAN explained a significant amount of variance in the evolution of reading skills.

Short-term memory for order but not for item information is impaired in developmental dyslexia

Recent findings suggest that people with dyslexia experience difficulties with the learning of serial order information during the transition from short- to long-term memory (Szmalec et al. Journal of Experimental Psychology: Learning, Memory, & Cognition 37(5): 1270-1279, 2011). At the same time, models of short-term memory increasingly incorporate a distinction of order and item processing (Majerus et al. Cognition 107: 395-419, 2008). The current study is aimed to investigate whether serial order processing deficiencies in dyslexia can be traced back to a selective impairment of short-term memory for serial order and whether this impairment also affects processing beyond the verbal domain. A sample of 26 adults with dyslexia and a group of age and IQ-matched controls participated in a 2 × 2 × 2 experiment in which we assessed short-term recognition performance for order and item information, using both verbal and nonverbal material. Our findings indicate that, irrespective of the type of material, participants with dyslexia recalled the individual items with the same accuracy as the matched control group, whereas the ability to recognize the serial order in which those items were presented appeared to be affected in the dyslexia group. We conclude that dyslexia is characterized by a selective impairment of short-term memory for serial order, but not for item information, and discuss the integration of these findings into current theoretical views on dyslexia and its associated dysfunctions.

Age, dyslexia subtype and comorbidity modulate rapid auditory processing in developmental dyslexia

The nature of Rapid Auditory Processing (RAP) deficits in dyslexia remains debated, together with the specificity of the problem to certain types of stimuli and/or restricted subgroups of individuals. Following the hypothesis that the heterogeneity of the dyslexic population may have led to contrasting results, the aim of the study was to define the effect of age, dyslexia subtype and comorbidity on the discrimination and reproduction of non-verbal tone sequences. Participants were 46 children aged 8–14 (26 with dyslexia, subdivided according to age, presence of a previous language delay, and type of dyslexia). Experimental tasks were a Temporal Order Judgment (TOJ) (manipulating tone length, ISI and sequence length), and a Pattern Discrimination Task. Dyslexic children showed general RAP deficits. Tone length and ISI influenced dyslexic and control children's performance in a similar way, but dyslexic children were more affected by an increase from 2 to 5 sounds. As to age, older dyslexic children's difficulty in reproducing sequences of 4 and 5 tones was similar to that of normally reading younger (but not older) children. In the analysis of subgroup profiles, the crucial variable appears to be the advantage, or lack thereof, in processing long vs. short sounds. Dyslexic children with a previous language delay obtained the lowest scores in RAP measures, but they performed worse with shorter stimuli, similar to control children, while dyslexic-only children showed no advantage for longer stimuli. As to dyslexia subtype, only surface dyslexics improved their performance with longer stimuli, while phonological dyslexics did not. Differential scores for short vs. long tones and for long vs. short ISIs predict non-word and word reading, respectively, and the former correlate with phonemic awareness. In conclusion, the relationship between non-verbal RAP, phonemic skills and reading abilities appears to be characterized by complex interactions with subgroup characteristics.

Naming abilities in low-proficiency second language learners

Difficulties in second language (L2) learning are often associated with recognizable learning difficulties in native language (L1), such as in dyslexia. However, some individuals have low L2 proficiency but intact L1 reading skills. These L2 learners experience frequent tip-of-the-tongue states while naming in L1, which indicates that they have a weakness in retrieval of phonological codes of words. The authors hypothesized that if naming ability is shared across languages, this difficulty would reemerge in L2 naming, which was tested using the tip-of-the-tongue experimental paradigm. Consistent with this hypothesis, low-proficiency L2 learners (n = 15) reported more tip-of-the-tongue states, more frequently mispronounced correctly retrieved words, and benefited less from phonological cuing compared to high-proficiency L2 learners (n = 23). It is notable that low-proficiency L2 learners performed worse than individuals with dyslexia (n = 16) on some of these measures, despite the same level of L2 proficiency. These results indicate that L2 naming difficulties of low-proficiency L2 learners are a manifestation not merely of their low L2 proficiency but rather of a general weakness in phonological word form retrieval, which is shared across languages. More broadly, the study provides further evidence for the existence of a distinct profile of cognitive weaknesses characteristic of the behavioral phenotype of low-proficiency L2 learners.

Working memory abilities among children treated for medulloblastoma: parent report and child performance

OBJECTIVE

We investigated the 5-year postsurgical developmental trajectory of working memory (WM) in children with medulloblastoma using parent and performance-based measures.

METHOD

This study included 167 patients treated for medulloblastoma. Serial assessments of WM occurred at predetermined time points for 5 years.

RESULTS

There was a subtle, statistically significant increase in parental concern about WM, coupled with a statistically significant decrease in age-standardized scores on performance-based measures. However, whole-group mean scores on both parent and performance-based measures remained in the age-expected range. Posterior fossa syndrome was consistently associated with poorer WM. Younger age at treatment and higher treatment intensity were associated with greater negative change in WM performance only.

CONCLUSIONS

Most children treated for medulloblastoma display WM within the age-appropriate range according to parent report and performance. However, the subtle negative changes over time and identified subgroups at increased risk highlight the need for ongoing monitoring of this population.

Executive functions in developmental dyslexia

The present study was aimed at investigating different aspects of Executive Functions (EF) in children with Developmental Dyslexia (DD). A neuropsychological battery tapping verbal fluency, spoonerism, attention, verbal shifting, short-term and working memory was used to assess 60 children with DD and 65 with typical reading (TR) abilities. Compared to their controls, children with DD showed deficits in several EF domains such as verbal categorical and phonological fluency, visual-spatial and auditory attention, spoonerism, verbal and visual short-term memory, and verbal working memory. Moreover, exploring predictive relationships between EF measures and reading, we found that spoonerism abilities better explained word and non-word reading deficits. Although to a lesser extent, auditory and visual-spatial attention also explained the increased percentage of variance related to reading deficit. EF deficits found in DD are interpreted as an expression of a deficient functioning of the Central Executive System and are discussed in the context of the recent temporal sampling theory.

A comparison of the language skills of ELLs and monolinguals who are poor decoders, poor comprehenders, or normal readers

The overall objective of this article is to examine how oral language abilities relate to reading profiles in English language learners (ELLs) and English as a first language (EL1) learners, and the extent of similarities and differences between ELLs and EL1s in three reading subgroups: normal readers, poor decoders, and poor comprehenders. The study included 100 ELLs and 50 EL1s in Grade 5. The effect of language group (ELL/EL1) and reading group on cognitive and linguistic skills was examined. Except for vocabulary, there was no language group effect on any measure. However, within ELL and EL1 alike, significant differences were found between reading groups: Normal readers outperformed the two other groups on all the oral language measures. Distinct cognitive and linguistic profiles were associated with poor decoders and poor comprehenders, regardless of language group. The ELL and EL1 poor decoders outperformed the poor comprehenders on listening comprehension and inferencing. The poor decoders displayed phonological-based weaknesses, whereas the poor comprehenders displayed a more generalized language processing weakness that is nonphonological in nature. Regardless of language status, students with poor decoding or comprehension problems display difficulties with various aspects of language.

Impaired short-term memory for order in adults with dyslexia

Verbal short-term memory (STM) deficits are consistently associated with dyslexia, but the nature of these deficits remains poorly understood. This study used the distinction between item and order retention processes to achieve a better understanding of STM deficits in adults with dyslexia. STM for item information has been shown to depend on the quality of underlying phonological representations, and hence should be impaired in dyslexia, which is characterized by poorly developed phonological representations. On the other hand, STM for order information is considered to reflect core STM processes, which are independent from language processing. Thirty adults with dyslexia and thirty control participants matched for age, education, vocabulary, and IQ were presented STM tasks, which distinguished item and order STM capacities. We observed not only impaired order STM in adults with dyslexia, but this impairment was independent of item STM impairment. This study shows that adults with dyslexia present a deficit in core verbal STM processes, a deficit which cannot be accounted for by the language processing difficulties that characterize dyslexia. Moreover, these results support recent theoretical accounts considering independent order STM and item STM processes, with a potentially causal involvement of order STM processes in reading acquisition.

Free recall behaviour in children with and without spelling impairment: the impact of working memory subcapacities

This study examined supraspan free recall in children with and without spelling impairment. A repeated free recall task involving overt rehearsal and three computer-based adaptive working memory tasks were administered to 54 eight-year-old children. Children without spelling impairments tended to recall more items than did those children with spelling deficits. Video analyses revealed that recall behaviour was similar in impaired and unimpaired children, indicating that both groups applied similar learning activities. Group differences in number of recalled items were attributed to differences in working memory subcapacities between children with and without spelling impairment, especially with regard to central executive and phonological loop functioning.

Auditory frequency discrimination in adults with dyslexia: a test of the anchoring hypothesis

PURPOSE

A recent hypothesis ascribes dyslexia to a perceptual anchoring deficit. Supporting results have so far been obtained only in children with dyslexia and additional learning difficulties, but the hypothesis has been argued to apply to all individuals with dyslexia.

METHOD

The authors measured auditory frequency discrimination thresholds in 54 young adults (native speakers of Dutch; 25 individuals with dyslexia; 29 age- and education-matched controls), with a 2-alternative forced-choice staircase paradigm. There were 2 conditions: 1 in which 1 tone in each pair had a fixed frequency across trials (standard), and 1 in which both tones varied in frequency (no standard). Presence of a standard stimulus allows the creation of a stimulus-specific representation in short-term-memory (perceptual anchor).

RESULTS

The standard condition yielded significantly lower discrimination thresholds in both controls and individuals with dyslexia; both groups benefited equally from the presence of an invariant stimulus.

CONCLUSION

There is no difference between this group of adults with dyslexia and controls in their capacity to form a perceptual anchor. The implication is that an anchoring deficit cannot be generalized to all cases of dyslexia.

Easier Said Than Done

A Canadian context for the diagnosis of students with specific learning disabilities (LD) was investigated in the present literature review. A systematic review of the literature was undertaken to determine the current and best practices in this field. Overall, no agreed upon definition of LD was identified, although core similarities in definitions were noted. Furthermore, recent research shows that many psychological assessments fail to adhere to any one definition when making this diagnosis, and as a result the diagnosis may or may not reflect the presence of a permanent disability that impairs academic functioning at the postsecondary level. There is, therefore, a need to adopt a consistent, evidence-based approach to diagnosis of LD in Canada. Recommendations regarding best practices and appropriate criteria for diagnosis of LD are discussed.

There are multiple contributors to the verbal short-term memory deficit in children with developmental reading disabilities

Prior research has put forth at least four possible contributors to the verbal short-term memory (VSTM) deficit in children with developmental reading disabilities (RD): poor phonological awareness that affects phonological coding into VSTM, a less effective phonological store, slow articulation rate, and fewer/poorer quality long-term memory (LTM) representations. This project is among the first to test the four suppositions in one study. Participants included 18 children with RD and 18 controls. VSTM was assessed using Baddeley's model of the phonological loop. Findings suggest all four suppositions are correct, depending upon the type of material utilized. Children with RD performed comparably to controls in VSTM for common words but worse for less frequent words and nonwords. Furthermore, only articulation rate predicted VSTM for common words, whereas Verbal IQ and articulation rate predicted VSTM for less frequent words, and phonological awareness and articulation rate predicted VSTM for nonwords. Overall, findings suggest that the mechanism(s) used to code and store items by their meaning is intact in RD, and the deficit in VSTM for less frequent words may be a result of fewer/poorer quality LTM representations for these words. In contrast, phonological awareness and the phonological store are impaired, affecting VSTM for items that are coded phonetically. Slow articulation rate likely affects VSTM for most material when present. When assessing reading performance, VSTM predicted decoding skill but not word identification after controlling Verbal IQ and phonological awareness. Thus, VSTM likely contributes to reading ability when words are novel and must be decoded.

Neuropsychological treatment of dyslexia: does type of treatment matter?

In this study, 123 children with a diagnosis of developmental dyslexia were assigned to different treatment groups, either variations of Bakker's intervention program based on the balance model or a control, a specific reading training group. Thorough cognitive and neuropsychological assessment allowed determination of the subtype of dyslexia according to the balance model and the neuropsychological profile with respect to reading and spelling abilities, verbal memory, and phonemic awareness. Characteristics of hemisphere-specific stimulation were systematically manipulated in an effort to shed light on the bases and mechanisms of reading improvement. It was shown that the effects of treatment vary according to type of dyslexia and that the different intervention programs have differential effects on reading-related neuropsychological functions. Since opposite effects can be produced by the same type of treatment in different dyslexia subtypes, the results of the study suggest that accurate classification of subtype on the base of reading and reading-related variables is advantageous for an optimal planning of the therapy.

Perception of non-verbal auditory stimuli in Italian dyslexic children

Auditory temporal processing deficits have been proposed as the underlying cause of phonological difficulties in Developmental Dyslexia. The hypothesis was tested in a sample of 20 Italian dyslexic children aged 8-14, and 20 matched control children. Three tasks of auditory processing of non-verbal stimuli, involving discrimination and reproduction of sequences of rapidly presented short sounds were expressly created. Dyslexic subjects performed more poorly than control children, suggesting the presence of a deficit only partially influenced by the duration of the stimuli and of inter-stimulus intervals (ISIs).

Using Nonword Repetition Tasks for the Identification of Language Impairment in Spanish-English Speaking Children: Does the Language of Assessment Matter?

The purpose of this study was twofold: (a) to evaluate the clinical utility of a verbal working memory measure, specifically, a nonword repetition task, with a sample of Spanish-English bilingual children and (b) to determine the extent to which individual differences in relative language skills and language use had an effect on the clinical differentiation of these children by the measures. A total of 144 Latino children (95 children with typical language development and 49 children with language impairment) were tested using nonword lists developed for each language. The results show that the clinical accuracy of nonword repetition tasks varies depending on the language(s) tested. Test performance appeared related to individual differences in language use and exposure. The findings do not support a monolingual approach to the assessment of bilingual children with nonword repetition tasks, even if children appear fluent speakers in the language of testing. Nonword repetition may assist in the screening of Latino children if used bilingually and in combination with other clinical measures.

Sentence comprehension in young adults with developmental dyslexia

This study investigated the effects of syntactic complexity on written sentence comprehension in compensated adults with dyslexia. Because working memory (WM) plays a key role in processing complex sentences, and individuals with dyslexia often demonstrate persistent deficits in WM, we hypothesized that individuals with dyslexia would perform more poorly on tasks designed to assess the comprehension of syntactic structures that are especially taxing on WM (e.g., passives, sentences with relative clauses). Compared to their nondyslexic peers, individuals with dyslexia were significantly less accurate and marginally slower on passive sentences. For sentences containing relative clauses, the dyslexic group was also less accurate but did not differ in response times. Covarying WM and word reading in both analyses eliminated group differences showing that syntactic deficits in adults with dyslexia are constrained by both WM and word-reading ability. These findings support previous research showing that syntactic processing deficits are characteristic of dyslexia, even among high-achieving students.