Developmental dyslexia: The difficulties of interpreting poor performance, and the importance of normal performance

Reduced benefit from long-term item frequency contributes to short-term memory deficits in dyslexia

Dyslexia, a specific difficulty in acquiring proficient reading, is also characterized by reduced short-term memory (STM) capacity. Extensive research indicates that individuals with developmental dyslexia (IDDs) benefit less from exposure, and this hampers their long-term knowledge accumulation. It is well established that long-term knowledge has a great effect on performance in STM tasks, and thus IDDs' reduced benefit of exposure could potentially reduce their relative performance in such tasks, especially when frequent items, such as digit-words, are used. In this study we used a standard, widely used, STM assessment: the Digit Span subtest from the Wechsler Adult Intelligence Scale. The task was conducted twice: in native language and in second language. As exposure to native language is greater than exposure to second language, we predicted that IDDs' performance in the task administered in native language will reveal a larger group difference as compared to second language, due to IDDs' reduced benefit of item frequency. The prediction was confirmed, in line with the hypothesis that reduced STM in dyslexia to a large extent reflects reduced benefits from long-term item frequency and not a reduced STM per se.

Screening for Dyslexia in University Students: a Standardized Procedure Based on Conditional Inference Trees

OBJECTIVE

The focus of this study is on providing tools to enable researchers and practitioners to screen for dyslexia in adults entering university. The first aim is to validate and provide diagnostic properties for a set of seven tests including a 1-min word reading test, a 2-min pseudoword reading test, a phonemic awareness test, a spelling test, the Alouette reading fluency test, a connected-text reading fluency test, and the self-report Adult Reading History Questionnaire (ARHQ). The second, more general, aim of this study was to devise a standardized and confirmatory procedure for dyslexia screening from a subset of the initial seven tests. We used conditional inference tree analysis, a supervised machine learning approach to identify the most relevant tests, cut-off scores, and optimal order of test administration.

METHOD

A combined sample of 60 university students with dyslexia (clinical validation group) and 65 university students without dyslexia (normative group) provided data to determine the diagnostic properties of these tests including sensitivity, specificity, and cut-off scores.

RESULTS

Results showed that combinations of four tests (ARHQ, text reading fluency, phonemic awareness, pseudoword reading) and their relative conditional cut-off scores optimize powerful discriminatory screening procedures for dyslexia, with an overall classification accuracy of approximately 90%.

CONCLUSIONS

The novel use of the conditional inference tree methodology explored in the present study offered a way of moving toward a more efficient screening battery using only a subset of the seven tests examined. Both clinical and theoretical implications of these findings are discussed.

Predicting language outcome at birth

Even though most children acquire language effortlessly, not all do. Nowadays, language disorders are difficult to diagnose before 3-4 years of age, because diagnosis relies on behavioral criteria difficult to obtain early in life. Using electroencephalography, I investigated whether differences in newborns' neural activity when listening to sentences in their native language (French) and a rhythmically different unfamiliar language (English) relate to measures of later language development at 12 and 18 months. Here I show that activation differences in the theta band at birth predict language comprehension abilities at 12 and 18 months. These findings suggest that a neural measure of language discrimination at birth could be used in the early identification of infants at risk of developmental language disorders.

Phonological syllables allow children with developmental dyslexia to access words

Learning to read is a middle-distance race for children worldwide. Most of them succeed in this acquisition with "normal" difficulties that ensue from the progressive (re)structuring of the phonological and orthographic systems. Evidence accumulated on reading difficulties in children with developmental dyslexia (DYS children, henceforth) shows a pervasive phonological deficit. However, the phonological deficit may not be due to degraded phonological representations but rather due to impaired access to them. This study focused on how and to what extent phonological syllables, which are essential reading units in French, were accessible to DYS children to segment and access words. We tested the assumption that DYS children did not strictly have pervasive degraded phonological representations but also have impaired access to phonological and orthographic representations. We administered a visually adapted word-spotting paradigm, engaging both sublexical processing and lexical access, with French native-speaking DYS children (N = 25; Mage in months = 121.6, SD = 3.0) compared with chronological age-matched peers (N = 25; Mage in months = 121.8, SD = 2.7; CA peers henceforth) and reading level-matched peers (N = 25; Mage in months = 94.0, SD = 4.6; RL peers henceforth). Although DYS children were slower and less accurate than CA and RL peers, we found that they used phonological syllables to access and segment words. However, they exhibit neither the classical inhibitory syllable frequency effect nor the lexical frequency effect, which is generally observed in typically developing children. Surprisingly, DYS children did not show strictly degraded phonological representations because they demonstrated phonological syllable-based segmentation abilities, particularly with high-frequency syllables. Their difficulties are rather interpreted in terms of impaired access to orthographic and phonological representations, which could be a direct effect of difficulties in generalizing and consolidating low-frequency syllables. We discuss these results regarding reading acquisition and the specificities of the French linguistic system.

Academic skills in children with cerebral palsy and specific learning disorders

AIM

To investigate the prevalence and clinical manifestations of reading, writing, and mathematics disorders in children with cerebral palsy (CP). We explored how the clinical profile of these children differed from those with specific learning disorders (SLDs), taking into account several factors, particularly IQ scores, neuropsychological aspects, and the presence of a visual impairment.

METHOD

A prospective cross-sectional study was conducted in 42 children with CP (mean age 9 years 8 months; SD = 2 years 2 months) and 60 children with SLDs (mean age 10 years; SD = 1 year 7 months). Clinical characteristics, neuromotor and cognitive profiles, neuropsychological aspects (speech performance, academic skills, visual attention, phonological awareness, working memory), and signs of visual impairment (visual acuity, contrast sensitivity, visual field, oculomotor functions) were assessed. A machine learning approach consisting of a random forest algorithm, where the outcome was the diagnosis and the covariates were the clinical variables collected in the sample, was used for the analyses.

RESULTS

About 59% of the children with CP had reading, writing, or mathematics disorders. Children with CP with learning disorders had a low performance IQ, normal phonological awareness, and working memory difficulties, whereas children with SLDs had normal performance IQ, impaired phonological awareness, and mild working memory difficulties. There were no differences in verbal IQ between the two groups.

INTERPRETATION

Learning disorders are frequently associated with CP, with different clinical characteristics, compared with SLDs. Assessment of academic skills is mandatory in these children, even if the IQ is normal. At school age, specific interventions to promote academic skills in children with CP could be a major rehabilitative goal.

WHAT THIS PAPER ADDS

Reading, writing, and mathematics disorders in cerebral palsy have specific clinical characteristics. Their underlying mechanisms differ from those described in specific learning disorders. Working memory impairment can be considered a hallmark of learning disorders in children with cerebral palsy.

Do developmental dyslexia and congenital amusia share underlying impairments?

Developmental dyslexia and congenital amusia have common characteristics. Yet, their possible association in some individuals has been addressed only scarcely. Recently, two converging studies reported a sizable comorbidity rate between these two neurodevelopmental disorders (Couvignou et al., Cognitive Neuropsychology 2019; Couvignou & Kolinsky, Neuropsychologia 2021). However, the reason for their association remains unclear. Here, we investigate the hypothesis of shared underlying impairments between dyslexia and amusia. Fifteen dyslexic children with amusia (DYS+A), 15 dyslexic children without amusia (DYS-A), and two groups of 25 typically developing children matched on either chronological age (CA) or reading level (RL) were assessed with a behavioral battery aiming to investigate phonological and pitch processing capacities at auditory memory, perceptual awareness, and attentional levels. Overall, our results suggest that poor auditory serial-order memory increases susceptibility to comorbidity between dyslexia and amusia and may play a role in the development of the comorbid phenotype. In contrast, the impairments observed in the DYS+A children for auditory item memory, perceptual awareness, and attention might be a consequence of their reduced reading experience combined with weaker musical skills. Comparing DYS+A and DYS-A children suggests that the latter are more resourceful and/or have more effective compensatory strategies, or that their phenotype results from a different developmental trajectory. We will discuss the relevance of these findings for delving into the etiology of these two developmental disorders and address their implications for future research and practice.

Speech therapy to overcome dyslexia in primary schoolers

This research was aimed to investigate changes in the reading technique and in terms of its semantic charge in primary schoolers diagnosed with dyslexia, which occur as a result of the integrated use of speech therapy techniques. The study was performed between 2016 and 2019 in 6 schools of Moscow and Almaty. It enrolled 194 and 200 children, respectively, who were examined with form I to III inclusive. The study revealed that 13% of children had reading speed disorders; they were constituted group 1. Another 11% had reading comprehension disorders; they constituted group 2. In group 1, by form III, the number of reading repetitions increased twofold. In group 2, the number of children, who read in words and phrases, increased by half; in group 1, it doubled. This research showed clear progress in children with technical dyslexia vs. those with semantic dyslexia. Based on the results, it is possible to develop a methodology for speech therapy techniques that can be suitable not only for speech therapists, but also for primary school teachers, as well as for parents of dyslectic children.

Can adults with developmental dyslexia apply statistical knowledge to a new context?

We investigated transfer of artificial grammar learning in adults with and without dyslexia in 3 experiments. In Experiment 1, participants implicitly learned an artificial grammar system and were tested on new items that included the same symbols. In Experiment 2, participants were given practice with letter strings and then tested on strings created with a different letter set. In Experiment 3, participants were given practice with shapes and then tested on strings created with different shapes. Results show that in Experiment 1, both groups demonstrated utilization of pre-trained instances in the subsequent grammaticality judgement task, while in Experiments 2 (orthographic) and 3 (nonorthographic), only typically developed participants demonstrated application of knowledge from training to test. A post hoc analysis comparing between the experiments suggests that being trained and tested on an orthographic task leads to better performance than a nonorthographic task among typically developed adults but not among adults with dyslexia. Taken together, it appears that following extensive training, individuals with dyslexia are able to form stable representations from sequential stimuli and use them in a subsequent task that utilizes strings of similar symbols. However, the manipulation of the symbols challenges this ability.

Phoneme Representation and Articulatory Impairment: Insights from Adults with Comorbid Motor Coordination Disorder and Dyslexia

Phonemic processing skills are impaired both in children and adults with dyslexia. Since phoneme representation development is based on articulatory gestures, it is likely that these gestures influence oral reading-related skills as assessed through phonemic awareness tasks. In our study, fifty-two young dyslexic adults, with and without motor impairment, and fifty-nine skilled readers performed reading, phonemic awareness, and articulatory tasks. The two dyslexic groups exhibited slower articulatory rates than skilled readers and the comorbid dyslexic group presenting with an additional difficulty in respiratory control (reduced speech proportion and increased pause duration). Two versions of the phoneme awareness task (PAT) with pseudoword strings were administered: a classical version under time pressure and a delayed version in which access to phonemic representations and articulatory programs was facilitated. The two groups with dyslexia were outperformed by the control group in both versions. Although the two groups with dyslexia performed equally well on the classical PAT, the comorbid group performed significantly less efficiently on the delayed PAT, suggesting an additional contribution of articulatory impairment in the task for this group. Overall, our results suggest that impaired phoneme representations in dyslexia may be explained, at least partially, by articulatory deficits affecting access to them.

Discriminatory Brain Processes of Native and Foreign Language in Children with and without Reading Difficulties

The association between impaired speech perception and reading difficulty has been well established in native language processing, as can be observed from brain activity. However, there has been scarce investigation of whether this association extends to brain activity during foreign language processing. The relationship between reading skills and neuronal speech representation of foreign language remains unclear. In the present study, we used event-related potentials (ERPs) with high-density EEG to investigate this question. Eleven- to 13-year-old children typically developed (CTR) or with reading difficulties (RD) were tested via a passive auditory oddball paradigm containing native (Finnish) and foreign (English) speech items. The change-detection-related ERP responses, the mismatch response (MMR), and the late discriminative negativity (LDN) were studied. The cluster-based permutation tests within and between groups were performed. The results showed an apparent language effect. In the CTR group, we found an atypical MMR in the foreign language processing and a larger LDN response for speech items containing a diphthong in both languages. In the RD group, we found unstable MMR with lower amplitude and a nonsignificant LDN response. A deficit in the LDN response in both languages was found within the RD group analysis. Moreover, we observed larger brain responses in the RD group and a hemispheric polarity reversal compared to the CTR group responses. Our results provide new evidence that language processing differed between the CTR and RD groups in early and late discriminatory responses and that language processing is linked to reading skills in both native and foreign language contexts.

Multimodal intervention in 8- to 13-year-old French dyslexic readers: Study protocol for a randomized multicenter controlled crossover trial

BACKGROUND

Developmental dyslexia, a specific and long-lasting learning disorder that prevents children from becoming efficient and fluent readers, has a severe impact on academic learning and behavior and may compromise professional and social development. Most remediation studies are based on the explicit or implicit assumption that dyslexia results from a single cause related to either impaired phonological or visual-attentional processing or impaired cross-modal integration. Yet, recent studies show that dyslexia is multifactorial and that many dyslexics have underlying deficits in several domains. The originality of the current study is to test a remediation approach that trains skills in all three domains using different training methods that are tailored to an individual's cognitive profile as part of a longitudinal intervention study.

METHODS

This multicenter randomized crossover study will be conducted in three phases and will involve 120 dyslexic children between the ages of 8 and 13 years. The first phase serves as within-subject baseline period that lasts for 2 months. In this phase, all children undergo weekly speech-language therapy sessions without additional training at home (business-as-usual). During the second phase, all dyslexics receive three types of intensive interventions that last 2 month each: Phonological, visual-attentional, and cross-modal. The order of the first two interventions (phonological and visual-attentional) is swapped in two randomly assigned groups of 60 dyslexics each. This allows one to test the efficacy and additivity of each intervention (against baseline) and find out whether the order of delivery matters. During the third phase, the follow-up period, the intensive interventions are stopped, and all dyslexics will be tested after 2 months. Implementation fidelity will be assessed from the user data of the computerized intervention program and an "intention-to-treat" analysis will be performed on the children who quit the trial before the end.

DISCUSSION

The main objective of this study is to assess whether the three types of intensive intervention (phase 2) improve reading skills compared to baseline (i.e., non-intensive intervention, phase 1). The secondary objectives are to evaluate the effectiveness of each intervention and to test the effects of order of delivery on reading intervention outcomes. Reading comprehension, spelling performance and reading disorder impact of dyslexic readers are assessed immediately before and after the multimodal intervention and 2 months post-intervention.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT04028310. Registered on July 18, 2019.

Repeated series learning revisited with a novel prediction on the reduced effect of item frequency in dyslexia

Developmental dyslexia, a difficulty with acquiring fluent reading, has also been characterized by reduced short-term memory (STM) capacity, which is often operationalized with span tasks. The low performance of individuals with dyslexia (IDDs) in such tasks is commonly attributed to poor phonological memory. However, we suggest an alternative explanation based on the observation that many times the items that are used in spans tasks are high-frequency items (e.g., digit words). We suggest that IDDs do not enjoy the benefit of item frequency to the same extent as controls, and thus their performance in span tasks is especially hampered. On the contrary, learning of repeated sequences was shown to be largely independent of item frequency, and therefore this type of learning may be unimpaired in dyslexia. To test both predictions, we used the Hebb-learning paradigm. We found that IDDs’ performance is especially poor compared to controls’ when high-frequency items are used, and that their repeated series learning does not differ from that of controls. Taken together with existing literature, our findings suggest that impaired learning of repeated series is not a core characteristic of dyslexia, and that the reports on reduced STM in dyslexia may to a large extent be explained by reduced benefit of item frequency.

Phonological awareness in children with developmental language disorder

Children with developmetal language disorder have impaired developmental pattern of language structure. Literature data speak in favor of delay and/or difficulties in development of phonological, lexical, morphological and syntactic structure, but the nature of developmental language disorder (DLD) has still not been elucidated. The aim of this paper was to present and analyze data about phonological awareness in children with DLD based on a systematic literature review. Also, we wanted to point out some methods of assessment and stimuli/encouragement in development of phonological abilities. The research presented in the analyzed literature have shown that current knowledge regarding phonological awareness in children with DLD is mainly obtained from comparative stuides of children with developmental language disorder and children with normal language development. A large number of results has revealed that different components of phonological awareness in children with DLD are less developed compared to their peers with typical development. Studies have also presented current assessment techniques and importance of phonological awareness preventive stimulation progams, which are an important indicator/parameter for the development of reading and writing as well as for onset of impairments in learning these skills.

Poor visuo-spatial orientation and path memorization in children with dyslexia

PURPOSE

Given the importance of spatial representation and navigation in the natural environment and the presence of sensory motor integration impairment in dyslexic children the aim of this study was to explore the capability in spatial orientation task in dyslexic children.

MATERIALS AND METHODS

We included forty children: 26 dyslexic children (mean age: 10.1 ± 0.3 years old) and 14 typically developing (TD) children (mean age: 10.1 ± 0.4 years old). Children have to walk on an unguided isosceles rectangle triangle of 3 meters that was marked on the ground of a room, during two visual conditions: eyes open and eyes closed. Their paths were recorded using the HTC Vive system (Base + Trackers) with a refresh rate of 90 Hz with accuracy < 0.05 mm.

RESULTS

Results underlined that both groups of children reported poor performance during eyes closed condition. Moreover, dyslexic children, reported poor spatial orientation capabilities in the most difficult conditions, that is during reproduction of hypotenuse and angle of 45 deg.

CONCLUSIONS

We suggested that visual information is important during walking; the poor body orientation observed in dyslexic children could be due to a deficient integration of the sensorial inputs (visual, vestibular and proprioceptive). Further studies testing vestibular/cerebellar rehabilitation could be useful for these kinds of children.HighlightsChildren with dyslexia showed poor spatial orientation capabilities compared to typically developing children, particularly when visual inputs are not available and in the most difficult conditions (like rotation of the body).Poor motor abilities reported by children with dyslexia could be due to cerebrocerebellar pathways impairments.

Cross-Sectional Investigation of Brain Volume in Dyslexia

The goal of the study was to determine whether dyslexia is associated with differences in local brain volume, and whether these local brain volume differences show cross-sectional age-effects. We investigated the local volume of gray and white brain matter with voxel-based morphometry (VBM) as well as reading performance in three age groups of dyslexic and neurotypical normal reading subjects (children, teenagers and adults). Performance data demonstrate a steady improvement of reading skills in both neurotypical as well as dyslexic readers. However, the pattern of gray matter volumes tell a different story: the children are the only group with significant differences between neurotypical and dyslexic readers in local gray matter brain volume. These differences are localized in brain areas associated with the reading network (angular, middle temporal and inferior temporal gyrus as well as the cerebellum). Yet the comparison of neurotypical and normal readers over the age groups shows that the steady increase in performance in neurotypical readers is accompanied by a steady decrease of gray matter volume, whereas the brain volumes of dyslexic readers do not show this linear correlation between brain volume and performance. This is further evidence that dyslexia is a disorder with a neuroanatomical basis in the form of a lower volume of gray matter in parts of the reading network in early dyslexic readers. The present data point out that network shaping processes in gray matter volume in the reading network does take place over age in dyslexia. Yet this neural foundation does not seem to be sufficient to allow normal reading performances even in adults with dyslexia. Thus dyslexia is a disorder with lifelong consequences, which is why consistent support for affected individuals in their educational and professional careers is of great importance. Longitudinal studies are needed to verify whether this holds as a valid pattern or whether there is evidence of greater interindividual variance in the neuroanatomy of dyslexia.

Success Is Not the Entire Story for a Scientific Theory: The Case of the Phonological Deficit Theory of Dyslexia

In a recent paper, Share discussed four different “Common Misconceptions about the Phonological Deficit Theory of Dyslexia” and described this theory as “a model of true scientific progress” and a clear “success story”. In this note, I argue that at least part of the success of this theory is due to the lack of explicit predictions which make it very difficult (if possible) to test its predictions, and, possibly, falsify the theory. Some areas of pertinent research, including categorical phoneme perception, picture naming, and phonological awareness are summarized. Furthermore, two lines of research in which groups of researchers have attempted to formulate more explicit predictions are briefly outlined. It is concluded that, although much research has variously referred to the phonological deficit theory of dyslexia, the resulting large body of evidence presents a complex pattern of results which, in the absence of an explicit formulation of the theory, is extremely difficult to frame within a unitary interpretation. Overall, what seems needed is a theoretical formulation that, on the one hand, can account for the complex pattern of available evidence and, on the other hand, provide testable predictions for future research.

Visual attention and reading: A test of their relation across paradigms

Relations of visual attention to reading have long been hypothesized; however, findings in this literature are quite mixed. These relations have been investigated using several different visual attention paradigms and with variable controls for other competing reading-related processes. We extended current knowledge by evaluating four of the key visual attention paradigms used in this research-visual attention span, attention blink, visual search, and visuospatial attention-in a single study. We tested the relations of these to reading in 90 middle schoolers at high risk for reading difficulties while considering their effect in the context of known language predictors. Performance on visual-spatial, visual search, and attentional blink paradigms showed weak nonsignificant relations to reading. Visual attention span tasks showed robust relations to reading even when controlling for language, but only when stimuli were alphanumeric. Although further exploration of visual attention in relation to reading may be warranted, the robustness of this relationship appears to be questionable, particularly beyond methodological factors associated with the measurement of visual attention. Findings extend and refine our understanding of the contribution of attention to reading skill and raise questions about the mechanism by which visual attention is purported to affect reading.

Is there such a thing as a 'good statistical learner'?

A growing body of research investigates individual differences in the learning of statistical structure, tying them to variability in cognitive (dis)abilities. This approach views statistical learning (SL) as a general individual ability that underlies performance across a range of cognitive domains. But is there a general SL capacity that can sort individuals from 'bad' to 'good' statistical learners? Explicating the suppositions underlying this approach, we suggest that current evidence supporting it is meager. We outline an alternative perspective that considers the variability of statistical environments within different cognitive domains. Once we focus on learning that is tuned to the statistics of real-world sensory inputs, an alternative view of SL computations emerges with a radically different outlook for SL research.

Towards a Comprehensive Account of Rhythm Processing Issues in Developmental Dyslexia

Developmental dyslexia is typically defined as a difficulty with an individual's command of written language, arising from deficits in phonological awareness. However, motor entrainment difficulties in non-linguistic synchronization and time-keeping tasks have also been reported. Such findings gave rise to proposals of an underlying rhythm processing deficit in dyslexia, even though to date, evidence for impaired motor entrainment with the rhythm of natural speech is rather scarce, and the role of speech rhythm in phonological awareness is unclear. The present study aimed to fill these gaps. Dyslexic adults and age-matched control participants with variable levels of previous music training completed a series of experimental tasks assessing phoneme processing, rhythm perception, and motor entrainment abilities. In a rhythm entrainment task, participants tapped along to the perceived beat of natural spoken sentences. In a phoneme processing task, participants monitored for sonorant and obstruent phonemes embedded in nonsense strings. Individual sensorimotor skills were assessed using a number of screening tests. The results lacked evidence for a motor impairment or a general motor entrainment difficulty in dyslexia, at least among adult participants of the study. Instead, the results showed that the participants' performance in the phonemic task was predictive of their performance in the rhythmic task, but not vice versa, suggesting that atypical rhythm processing in dyslexia may be the consequence, but not the cause, of dyslexic difficulties with phoneme-level encoding. No evidence for a deficit in the entrainment to the syllable rate in dyslexic adults was found. Rather, metrically weak syllables were significantly less often at the center of rhythmic attention in dyslexic adults as compared to neurotypical controls, with an increased tendency in musically trained participants. This finding could not be explained by an auditory deficit in the processing of acoustic-prosodic cues to the rhythm structure, but it is likely to be related to the well-documented auditory short-term memory issue in dyslexia.

Chasing the Anchor: A Systematic Review and Meta-Analysis of Perceptual Anchoring Deficits in Developmental Dyslexia

Purpose We report the results of a systematic review and meta-analysis investigating the relationship between perceptual anchoring and dyslexia. Our goal was to assess the direction and degree of the effect between perceptual anchoring and reading ability in typical and atypical (i.e., dyslexic) readers. Method We performed a literature search of experiments explicitly assessing perceptual anchoring and reading ability using PsycInfo (Ovid, 1860-2020), MEDLINE (Ovid, 1860-2019), EMBASE (Ovid, 1883-2019), and PubMed for all available years up to June (2020). Our eligibility criteria consisted of English language articles, and, at minimum, one experimental group identified as dyslexic-either by reading assessment at the time or by previous diagnosis. We assessed for risk of bias using an adapted version of the Newcastle-Ottawa Scale. Eight studies were included in this review and meta-analysis (n = 422 participants). Results The overall effect was negative, moderate, and statistically significant; g = -0.70, 95% confidence interval [-1.10, -0.29]: a negative effect size indicating less perceptual anchoring in dyslexic versus nondyslexic groups. Visual assessment of funnel plot and Egger's test suggest minimal bias but with significant heterogeneity; Q (7) = 17.03, prediction interval [-1.79, 0.40]. Conclusions Of the included studies, we find evidence for a moderate perceptual anchoring deficit in individuals with dyslexia. The primary limitation of the current review is the small number of included studies. The variability of effect sizes appears consistent with the inherent variability within subtypes of dyslexia.

The Correlation between Chinese Written Vocabulary Size and Cognitive, Emotional and Behavioral Factors in Primary School Students

Written vocabulary size plays a key role in children’s reading development. We aim to study the relationship between Chinese written vocabulary size and cognitive, emotional, and behavioral factors in primary school students. Using stratified cluster sampling, 1162 pupils from Grade 2~5 in Guangzhou were investigated. Chinese written vocabulary size, cognitive, emotional, and behavioral factors were assessed by the Chinese written vocabulary size assessment scale, the dyslexia checklist for Chinese children (DCCC) and the Strengths and Difficulties Questionnaire (SDQ), respectively. The scores of visual word recognition deficit (β = −3.32, 95% CI: −5.98, −0.66) and meaning comprehension deficit (β = −6.52, 95% CI: −9.39, −3.64) were negatively associated with Chinese written vocabulary size; the score of visual word recognition deficit (odds ratio (OR) = 1.04, 95% CI: 1.02, 1.07) was the related factor of a delay in written vocabulary size. The score of meaning comprehension deficit was negatively associated with boys’ Chinese written vocabulary size, while the score of auditory word recognition deficit was negatively associated with girls’ Chinese written vocabulary size. The related factor of a delay in written vocabulary size was spelling deficit in boys and visual word recognition deficit in girls. There is a significant correlation between Chinese written vocabulary size and cognitive factors, but not emotional and behavioral factors in primary school students and these correlations are different when considering gender.

The influence of the multimedia and modality principles on the learning outcomes, satisfaction, and mental effort of college students with and without dyslexia

The purpose of this study was to examine the application of the multimedia and modality principles on cued-recall, recognition, and mental effort of college students with and without dyslexia. The study used a Multimedia (Image Present vs. Image Absent) × Modality (Narration vs. Onscreen Text) × Dyslexia (Dyslexia vs. Non-Dyslexia) 3-way factorial design with each independent variable serving as a between-subject condition. A total of N = 148 participants (73 with dyslexia and 75 without dyslexia) were recruited from five different institutions of higher education in the Southeastern United States and systematically assigned to one of four multimedia learning conditions. After assessing our data for statistical assumptions, we employed factorial Analysis of Variance (ANOVA) models on each dependent measure. Our findings show a reverse modality effect for students with dyslexia who performed better than their peers without dyslexia in Onscreen Text conditions. Although performance was better across groups and conditions when images were present, there were no significant interactions related to the multimedia condition. Similarly, there were no significant interactions related to mental effort even though learners with dyslexia exhibited high instructional efficiency in the Onscreen Text-Image Present condition while learners without dyslexia exhibited low task involvement in the Onscreen Text-Image Absent condition. Our results provide theoretical implications and important avenues for future research and practice as related to how multimedia learning influences students with dyslexia. We also suggest studies that could inform the eventual design of adaptive and personalized multimedia learning solutions for learners with dyslexia.

Improving reading skills in children with dyslexia: efficacy studies on a newly proposed remedial intervention-repeated reading with vocal music masking (RVM)

In this work, two different studies are examined to evaluate the effectiveness of a novel intervention program for the improvement of reading ability in children with dyslexia, known as repeated reading with vocal music masking (RVM). The proposed remedial approach is inspired by Breznitz's original work. The studies assess a 5-week program of intensive RVM training in a pre-post-test clinical paradigm, as well as a longitudinal paradigm where it is compared to 8 months of the standard remediation program (SRP). The results of both studies support the efficacy of the newly proposed RVM method. Notably in the longitudinal study, the reading speed of children, as well as related phonological, visuo-attentional, and cognitive skills, and attitudes toward reading, were measured regularly. Significant improvements in reading efficiency and related skills were observed, as well as greater motivation to read after RVM training. A modeling of the data specifically linked executive and processing speed skills to be involved in RVM training, suggesting that RVM may help rebalance the phonological and orthographic coding procedures necessary for efficient reading. The short, intensive, and focused nature of RVM training makes it a viable and attractive intervention for clinical practice. As preliminary results are promising, RVM training may prove to be a valuable tool that clinicians can call upon to effectively treat reading fluency disorders, especially when standard programs do not provide results.

Comorbidity and cognitive overlap between developmental dyslexia and congenital amusia in children

Developmental dyslexia and congenital amusia are two specific neurodevelopmental disorders that affect reading and music perception, respectively. Similarities at perceptual, cognitive, and anatomical levels raise the possibility that a common factor is at play in their emergence, albeit in different domains. However, little consideration has been given to what extent they can co-occur. A first adult study suggested a 30% amusia rate in dyslexia and a 25% dyslexia rate in amusia (Couvignou et al., Cognitive Neuropsychology 2019). We present newly acquired data from 38 dyslexic and 38 typically developing children. These were assessed with literacy and phonological tests, as well as with three musical tests: the Montreal Battery of Evaluation of Musical Abilities, a pitch and time change detection task, and a singing task. Overall, about 34% of the dyslexic children were musically impaired, a proportion that is significantly higher than both the estimated 1.5-4% prevalence of congenital amusia in the general population and the rate of 5% observed within the control group. They were mostly affected in the pitch dimension, both in terms of perception and production. Correlations and prediction links were found between pitch processing skills and language measures after partialing out confounding factors. These findings are discussed with regard to cognitive and neural explanatory hypotheses of a comorbidity between dyslexia and amusia.

Investigating the role of temporal processing in developmental dyslexia: Evidence for a specific deficit in rapid visual segmentation

The current study investigates the role of temporal processing in the visual domain in participants with developmental dyslexia (DD), the most common neurodevelopmental disorder, which is characterized by severe and specific difficulties in learning to read despite normal intelligence and adequate education. Specifically, our aim was to test whether DD is associated with a general impairment of temporal sensory processing or a specific deficit in temporal integration (which ensures stability of object identity and location) or segregation (which ensures sensitivity to changes in visual input). Participants with DD performed a task that measured both temporal integration and segregation using an identical sequence of two displays separated by a varying interstimulus interval (ISI) under two different task instructions. Results showed that participants with DD performed worse in the segregation task, with a shallower slope of the psychometric curve of percentage correct as a function of the ISI between the two target displays. Moreover, we found also a relationship between temporal segregation performance and text, words, and pseudowords reading speeds at the individual level. In contrast, no significant association between reading (dis)ability and temporal integration emerged. The current findings provide evidence for a difference in the fine temporal resolution of visual processing in DD and, considering the growing evidence about a link between visual temporal segregation and neural oscillations at specific frequencies, they support the idea that DD is characterized by an altered oscillatory sampling within the visual system.

Statistical Learning and Language Impairments: Toward More Precise Theoretical Accounts

Statistical-learning (SL) theory offers an experience-based account of typical and atypical spoken and written language acquisition. Recent work has provided initial support for this view, tying individual differences in SL abilities to linguistic skills, including language impairments. In the current article, we provide a critical review of studies testing SL abilities in participants with and without developmental dyslexia and specific language impairment and discuss the directions that this field of research has taken so far. We identify substantial vagueness in the demarcation lines between different theoretical constructs (e.g., “statistical learning,” “implicit learning,” and “procedural learning”) as well as in the mappings between experimental tasks and these theoretical constructs. Moreover, we argue that current studies are not designed to contrast different theoretical approaches but rather test singular confirmatory predictions without including control tasks showing normal performance. We end by providing concrete suggestions for how to advance research on SL deficits in language impairments.

Exploring the phonological profiles of children with reading difficulties: A multiple case study

Studies of group differences have established that the phonological profiles of people with reading difficulties contain both strengths and weaknesses. The current study extends this work by exploring individual differences in phonological ability using a multiple case study approach. A heterogeneous sample of 56 children (M age = 9 years) with reading difficulties completed a battery of tasks measuring literacy, phonological processing, expressive vocabulary and general ability. The phonological tasks included measures of phonological awareness (PA), phonological memory (PM), and rapid naming (RAN). A majority-although not all-of the children had phonological processing impairments. However, there was also substantial variability in the nature of children's phonological difficulties. While multiple impairments encompassing two or more phonological domains were most common, impairments that were specific to PA, PM or RAN also occurred frequently. Even within the domain of PA, where children completed three well-matched tasks, individual children were rarely impaired across all three measures and a number of different profiles were observed. Additional, group-level analyses indicated that PA was a significant predictor of decoding while RAN was a significant predictor of automatic word recognition and comprehension. Findings are discussed with reference to conceptual models of phonological processing and implications for assessment.

Bridging sensory and language theories of dyslexia: Toward a multifactorial model

Competing theories of dyslexia posit that reading difficulties arise from impaired visual, auditory, phonological, or statistical learning mechanisms. Importantly, many theories posit that dyslexia reflects a cascade of impairments emanating from a single “core deficit”. Here we report two studies evaluating core deficit and multifactorial models. In Study 1, we use publicly available data from the Healthy Brain Network to test the accuracy of phonological processing measures for predicting dyslexia diagnosis and find that over 30% of cases are misclassified (sensitivity = 66.7%; specificity = 68.2%). In Study 2, we collect a battery of psychophysical measures of visual motion processing and standardized measures of phonological processing in 106 school‐aged children to investigate whether dyslexia is best conceptualized under a core‐deficit model, or as a disorder with heterogenous origins. Specifically, by capitalizing on the drift diffusion model to analyze performance on a visual motion discrimination experiment, we show that deficits in visual motion processing, perceptual decision‐making, and phonological processing manifest largely independently. Based on statistical models of how variance in reading skill is parceled across measures of visual processing, phonological processing, and decision‐making, our results challenge the notion that a unifying deficit characterizes dyslexia. Instead, these findings indicate a model where reading skill is explained by several distinct, additive predictors, or risk factors, of reading (dis)ability.

Context effects on phoneme categorization in children with dyslexia

Research shows that, on average, children with dyslexia behave less categorically in phoneme categorization tasks. This study investigates three subtle ways that struggling readers may perform differently than their typically developing peers in this experimental context: sensitivity to the frequency distribution from which speech tokens are drawn, bias induced by previous stimulus presentations, and fatigue during the course of the task. We replicate findings that reading skill is related to categorical labeling, but we do not find evidence that sensitivity to the stimulus frequency distribution, the influence of previous stimulus presentations, and a measure of task engagement differs in children with dyslexia. It is, therefore, unlikely that the reliable relationship between reading skill and categorical labeling is attributable to artifacts of the task design, abnormal neural encoding, or executive function. Rather, categorical labeling may index a general feature of linguistic development whose causal relationship to literacy remains to be ascertained.

Project DyAdd: Non-linguistic Theories of Dyslexia Predict Intelligence

Two themes have puzzled the research on developmental and learning disorders for decades. First, some of the risk and protective factors behind developmental challenges are suggested to be shared and some are suggested to be specific for a given condition. Second, language-based learning difficulties like dyslexia are suggested to result from or correlate with non-linguistic aspects of information processing as well. In the current study, we investigated how adults with developmental dyslexia or ADHD as well as healthy controls cluster across various dimensions designed to tap the prominent non-linguistic theories of dyslexia. Participants were 18–55-year-old adults with dyslexia (n = 36), ADHD (n = 22), and controls (n = 35). Non-linguistic theories investigated with experimental designs included temporal processing impairment, abnormal cerebellar functioning, procedural learning difficulties, as well as visual processing and attention deficits. Latent profile analysis (LPA) was used to investigate the emerging groups and patterns of results across these experimental designs. LPA suggested three groups: (1) a large group with average performance in the experimental designs, (2) participants predominantly from the clinical groups but with enhanced conditioning learning, and (3) participants predominantly from the dyslexia group with temporal processing as well as visual processing and attention deficits. Despite the presence of these distinct patterns, participants did not cluster very well based on their original status, nor did the LPA groups differ in their dyslexia or ADHD-related neuropsychological profiles. Remarkably, the LPA groups did differ in their intelligence. These results highlight the continuous and overlapping nature of the observed difficulties and support the multiple deficit model of developmental disorders, which suggests shared risk factors for developmental challenges. It also appears that some of the risk factors suggested by the prominent non-linguistic theories of dyslexia relate to the general level of functioning in tests of intelligence.

The role of phonology in lexical access in teenagers with a history of dyslexia

We examined phonological recoding during silent sentence reading in teenagers with a history of dyslexia and their typically developing peers. Two experiments are reported in which participants' eye movements were recorded as they read sentences containing correctly spelled words (e.g., church), pseudohomophones (e.g., cherch), and spelling controls (e.g., charch). In Experiment 1 we examined foveal processing of the target word/nonword stimuli, and in Experiment 2 we examined parafoveal pre-processing. There were four participant groups-older teenagers with a history of dyslexia, older typically developing teenagers who were matched for age, younger typically developing teenagers who were matched for reading level, and younger teenagers with a history of dyslexia. All four participant groups showed a pseudohomophone advantage, both from foveal processing and parafoveal pre-processing, indicating that teenagers with a history of dyslexia engage in phonological recoding for lexical identification during silent sentence reading in a comparable manner to their typically developing peers.

Evolving Concepts of Dyslexia and Their Implications for Research and Remediation

Aspects of dyslexia definitions are framed as a contrast between the past and the future, focusing on implications for research and remedial education, highlighting assumptions that bias or limit research or clinical practice. A crucial development is evident in understanding dyslexia, moving from its conceptualization as a discrete identifiable condition toward the realization of continuity with the general population with no clear boundaries and no qualitative differences. This conceptual evolution amounts to a transition from considering dyslexia to be some entity that causes poor reading toward considering the term dyslexia to simply label poor reading performance. This renders obsolete any searches for abnormalities and directs efforts toward understanding reading skill as a multifaceted domain following a complex multifactorial developmental course.

Developmental dyslexia in Hindi readers: Is consistent sound-symbol mapping an asset in reading? Evidence from phonological and visuospatial working memory

Phonological processing deficit is a hallmark of developmental dyslexia indicating a core cognitive dysfunction. Importance of working memory in reading and its association with the tasks measuring phonological processing is also debated in research. The present study investigates the role of working memory, phonological, and orthographic processing in Hindi-speaking dyslexic children (22 dyslexic and 23 control, of Grade 4). Hindi has a consistent symbol-sound mapping with an extensive list of visually complex graphemes. Although consistent symbol-sound mapping facilitates reading, graphemic complexity has its cost on memory. A range of tasks measuring phonological processing, working memory, and orthographic knowledge was designed and administered. Dyslexic children scored significantly lower than controls not only on working memory tasks but also on the tasks of phonological processing and orthographic knowledge. Moreover, the difference in working memory between dyslexic and normal children was more pronounced with increased task complexity. These results highlight complex relationships between working memory, phonological and orthographic processing together with visual attentional processing in Hindi, that contribute to the reading deficits encountered by children with dyslexia. Their respective contributions are considered in the discussion with some of the visual and phonological features of Hindi orthography and their associated effects in reading.

Categorical phoneme labeling in children with dyslexia does not depend on stimulus duration

It is established that individuals with dyslexia are less consistent at auditory phoneme categorization than typical readers. One hypothesis attributes these differences in phoneme labeling to differences in auditory cue integration over time, suggesting that the performance of individuals with dyslexia would improve with longer exposure to informative phonetic cues. Here, the relationship between phoneme labeling and reading ability was investigated while manipulating the duration of steady-state auditory information available in a consonant-vowel syllable. Children with dyslexia obtained no more benefit from longer cues than did children with typical reading skills, suggesting that poor task performance is not explained by deficits in temporal integration or temporal sampling.

Distinct effects of visual and auditory temporal processing training on reading and reading-related abilities in Chinese children with dyslexia

This study aimed to examine the effects of temporal processing training on the reading abilities of Chinese children with dyslexia. In total, 69 Chinese children with dyslexia in grades three through six were recruited in Taiwan. The children were divided into the following three equal groups: (1) auditory temporal processing training group, (2) visual temporal processing training group, and (3) control group with no specific training. The participants in both training groups received instruction with identical durations (30-40 min), intensities (12 times in total), and frequencies (three to four times per week). The participants in the control group were asked to independently surf some specified websites using devices similar to those used by the two experimental groups for an identical duration, intensity, and frequency. Our results indicated that the two groups who received temporal processing training exhibited significant correlations among Chinese character reading, rapid naming, and corresponding reading-related abilities, while visual temporal processing served as a significant predictor of Chinese character reading ability even if all background data, reading-related abilities, and auditory temporal processing were introduced first. Additionally, significant interactions were found between the Groups and Tested sessions in all the measures, except for phonological awareness, confirming the distinct effects of different temporal processing on most measures involved in this study. Further simple main effects revealed that only those who received the visual temporal processing training gained benefits in the corresponding reading-related ability (i.e., orthographic knowledge) and far-transfer to Chinese character reading.

The dyslexia susceptibility KIAA0319 gene shows a specific expression pattern during zebrafish development supporting a role beyond neuronal migration

Dyslexia is a common neurodevelopmental disorder caused by a significant genetic component. The KIAA0319 gene is one of the most robust dyslexia susceptibility factors but its function remains poorly understood. Initial RNA-interference studies in rats suggested a role in neuronal migration whereas subsequent work with double knock-out mouse models for both Kiaa0319 and its paralogue Kiaa0319-like reported effects in the auditory system but not in neuronal migration. To further understand the role of KIAA0319 during neurodevelopment, we carried out an expression study of its zebrafish orthologue at different embryonic stages. We used different approaches including RNAscope in situ hybridization combined with light-sheet microscopy. The results show particularly high expression during the first few hours of development. Later, expression becomes localized in well-defined structures. In addition to high expression in the brain, we report for the first time expression in the eyes and the notochord. Surprisingly, kiaa0319-like, which generally shows a similar expression pattern to kiaa0319, was not expressed in the notochord suggesting a distinct role for kiaa0319 in this structure. This observation was supported by the identification of notochord enhancers enriched upstream of the KIAA0319 transcription start site, in both zebrafish and humans. This study supports a developmental role for KIAA0319 in the brain as well as in other developing structures, particularly in the notochord which, is key for establishing body patterning in vertebrates.

Beyond the global motion deficit hypothesis of developmental dyslexia: A cross-sectional study of visual, cognitive, and socio-economic factors influencing reading ability in children

Although primarily conceptualized as a disorder of phonological awareness, developmental dyslexia is often associated with broader problems perceiving and attending to transient or rapidly-moving visual stimuli. However, the extent to which such visual deficits represent the cause or the consequence of dyslexia remains contentious, and very little research has examined the relative contributions of phonological, visual, and other variables to reading performance more broadly. We measured visual sensitivity to global motion (GM) and global form (GF), performance on various language and other cognitive tasks believed to be compromised in dyslexia (phonological awareness, processing speed, and working memory), together with a range of social and demographic variables often omitted in previous research, such as age, gender, non-verbal intelligence, and socio-economic status in an unselected sample (n = 132) of children aged 6-11.5 yrs from two different primary schools in Edinburgh, UK. We found that: (i) Mean GM sensitivity (but not GF) was significantly lower in poor readers (medium effect size); (ii) GM sensitivity accounted for only 3% of the variance in reading scores; (iii) GM sensitivity deficits were observed in only 16% of poor readers; (iv) the best predictors of reading performance were phonological awareness, non-verbal intelligence, and socio-economic status, suggesting the importance of controlling for these in future studies of vision and reading. These findings suggest that developmental dyslexia is unlikely to represent a single category of neurodevelopmental disorder underpinned by lower-level deficits in visual motion processing.

Dyslexia and age related effects in the neurometabolites concentration in the visual and temporo-parietal cortex

Several etiological theories, in particular neuronal noise and impaired auditory sampling, predicted neurotransmission deficits in dyslexia. Neurometabolites also affect white matter microstructure, where abnormalities were previously reported in dyslexia. However findings from only few magnetic resonance spectroscopy studies using diverse age groups, different brain regions, data processing and reference scaling are inconsistent. We used MEGA-PRESS single-voxel spectroscopy in two ROIs: left temporo-parietal and occipital cortex in 36 adults and 52 children, where half in each group had dyslexia. Dyslexics, on average, had significantly lower total N-acetylaspartate (tNAA) than controls in the occipital cortex. Adults compared to children were characterized by higher choline and creatine in both areas, higher tNAA in left temporo-parietal and lower glutamate in the visual cortex, reflecting maturational changes in cortical microstructure and metabolism. Although the current findings do not support the proposed etiological theories of dyslexia, they show, for the first time, that tNAA, considered to be a neurochemical correlate of white matter integrity, is deficient in the visual cortex in both children and adults with dyslexia. They also point that several neurotransmitters, including ones previously used as reference, change with age.

The neuronal migration hypothesis of dyslexia: A critical evaluation 30 years on

The capacity for language is one of the key features underlying the complexity of human cognition and its evolution. However, little is known about the neurobiological mechanisms that mediate normal or impaired linguistic ability. For developmental dyslexia, early postmortem studies conducted in the 1980s linked the disorder to subtle defects in the migration of neurons in the developing neocortex. These early studies were reinforced by human genetic analyses that identified dyslexia susceptibility genes and subsequent evidence of their involvement in neuronal migration. In this review, we examine recent experimental evidence that does not support the link between dyslexia and neuronal migration. We critically evaluate gene function studies conducted in rodent models and draw attention to the lack of robust evidence from histopathological and imaging studies in humans. Our review suggests that the neuronal migration hypothesis of dyslexia should be reconsidered, and the neurobiological basis of dyslexia should be approached with a fresh start.

Neural Correlates of Oral Word Reading, Silent Reading Comprehension, and Cognitive Subcomponents

The ability to read is essential for cognitive development. To deepen our understanding of reading acquisition, we explored the neuroanatomical correlates (cortical thickness (CT)) of word reading fluency and sentence comprehension efficiency in Chinese with a group of typically developing children (N = 21; 12 females and 9 males; age range 10.7-12.3 years). Then, we investigated the relationship between the CT of reading-defined regions and the cognitive subcomponents of reading to determine whether our study lends support to the multi-component model. The results demonstrated that children's performance on oral word reading was positively correlated with CT in the left superior temporal gyrus (LSTG), inferior temporal gyrus (LITG), supramarginal gyrus (LSMG) and right superior temporal gyrus (RSTG). Moreover, CT in the LSTG, LSMG and LITG uniquely predicted children's phonetic representation, phonological awareness, and orthography-phonology mapping skills, respectively. By contrast, children's performance on sentence reading comprehension was positively correlated with CT in the left parahippocampus (LPHP) and right calcarine fissure (RV1). As for the subcomponents of reading, CT in the LPHP was exclusively correlated with morphological awareness, whereas CT in the RV1 was correlated with orthography-semantic mapping. Taken together, these findings indicate that the reading network of typically developing children consists of multiple subdivisions, thus providing neuroanatomical evidence in support of the multi-componential view of reading.

Structural and functional abnormality of the putamen in children with developmental dyslexia

There is currently debate with regards to the role of phonological deficit in Chinese reading difficulty, even though some researchers have suggested that the deficit of phonological processing is also a signature of developmental dyslexia in Chinese, as has been found in alphabetic languages. In this study, we examined the brain mechanisms of phonological deficit in Chinese children with developmental dyslexia (DD) during an auditory rhyming judgment task. First, we examined structural differences in Chinese dyslexia by comparing gray and white matter volume in Chinese children with DD, age-matched controls (AC), and reading-matched controls (RC). Next, we examined whether the regions with an abnormal volume in DD showed deficient functional connectivity with the rest of the brain during a phonological task (i.e. auditory rhyming judgment). We found that both AC and RC had greater gray matter volume (GMV) at the left putamen and right dorsal lateral frontal cortex than DD, suggesting possible neural signatures of developmental dyslexia. Functional connectivity analysis revealed that the left putamen was more connected with the right inferior occipital gyrus (IOG) in AC and RC than in DD, suggesting that automatic orthographic involvement during spoken language processing is more salient in controls, while the left putamen was more connected with the left transverse temporal gyrus (TTG) and left insula in DD than in AC and RC, suggesting the phonological articulation -auditory feedback loop is more involved in DD. These findings suggest that the reduced left putamen might contribute to phonological deficits experienced in DD, since it showed deficient connectivity with the rest of the brain during phonological processing.

Is Dyslexia a Brain Disorder?

Specific word reading difficulty, commonly termed ‘developmental dyslexia’, refers to the low end of the word reading skill distribution but is frequently considered to be a neurodevelopmental disorder. This term implies that brain development is thought to be disrupted, resulting in an abnormal and dysfunctional brain. We take issue with this view, pointing out that there is no evidence of any obvious neurological abnormality in the vast majority of cases of word reading difficulty cases. The available relevant evidence from neuroimaging studies consists almost entirely of correlational and group-differences studies. However, differences in brains are certain to exist whenever differences in behavior exist, including differences in ability and performance. Therefore, findings of brain differences do not constitute evidence for abnormality; rather, they simply document the neural substrate of the behavioral differences. We suggest that dyslexia is best viewed as one of many expressions of ordinary ubiquitous individual differences in normal developmental outcomes. Thus, terms such as “dysfunctional” or “abnormal” are not justified when referring to the brains of persons with dyslexia.

Paired associate learning deficits in poor readers: The contribution of phonological input and output processes

It is well-established that poor readers exhibit deficits in paired associate learning (PAL), and there is increasing evidence for a phonological locus of these deficits. However, it remains unclear whether poor performance stems from difficulties specific to the phonological output system or difficulties that affect both phonological input and output processes. Understanding these deficits is important not only in the context of PAL but also for informing broader theories of typical and atypical reading development. We developed a novel paradigm that allowed us to assess PAL in the presence and absence of phonological output demands. In total, 14 poor readers and 14 age-matched controls were first trained to criterion in verbal-visual PAL before being tested in the visual-verbal direction. The results showed that poor readers learned at the same rate as controls in verbal-visual PAL, even when the nonword stimuli were phonologically confusable. Yet, despite having reached the same criterion as controls in verbal-visual PAL, poor readers exhibited robust impairments for those same paired associates in visual-verbal PAL. The overall pattern of results is most consistent with the conclusion that PAL deficits reflect impairments to the phonological output system; however, results that may challenge this interpretation are also discussed.

Knockout Mice for Dyslexia Susceptibility Gene Homologs KIAA0319 and KIAA0319L have Unaffected Neuronal Migration but Display Abnormal Auditory Processing

Developmental dyslexia is a neurodevelopmental disorder that affects reading ability caused by genetic and non-genetic factors. Amongst the susceptibility genes identified to date, KIAA0319 is a prime candidate. RNA-interference experiments in rats suggested its involvement in cortical migration but we could not confirm these findings in Kiaa0319-mutant mice. Given its homologous gene Kiaa0319L (AU040320) has also been proposed to play a role in neuronal migration, we interrogated whether absence of AU040320 alone or together with KIAA0319 affects migration in the developing brain. Analyses of AU040320 and double Kiaa0319;AU040320 knockouts (dKO) revealed no evidence for impaired cortical lamination, neuronal migration, neurogenesis or other anatomical abnormalities. However, dKO mice displayed an auditory deficit in a behavioral gap-in-noise detection task. In addition, recordings of click-evoked auditory brainstem responses revealed suprathreshold deficits in wave III amplitude in AU040320-KO mice, and more general deficits in dKOs. These findings suggest that absence of AU040320 disrupts firing and/or synchrony of activity in the auditory brainstem, while loss of both proteins might affect both peripheral and central auditory function. Overall, these results stand against the proposed role of KIAA0319 and AU040320 in neuronal migration and outline their relationship with deficits in the auditory system.

Screening Protocol for Early Identification of Brazilian Children at Risk for Dyslexia

Early identification of students at risk of dyslexia has been an educational challenge in the past years. This research had two main goals. First, we aimed to develop a screening protocol for early identification of Brazilian children at risk for dyslexia; second, we aimed to identify the predictive variables of this protocol using Principal Component Analysis. The major step involved in developing this protocol was the selection of variables, which were chosen based on the literature review and linguistic criteria. The screening protocol was composed of seven cognitive-linguistic skills: Letter naming; Phonological Awareness (which comprises the following subtests: Rhyme production, Rhyme identification, Syllabic segmentation, Production of words from a given phoneme, Phonemic Synthesis, and Phonemic analysis); Phonological Working memory, Rapid naming Speed; Silent reading; Reading of words and non-words; and Auditory Comprehension of sentences from pictures. A total of 149 children, aged from 6 years to 6 and 11, of both genders who were enrolled in the 1st grade of elementary public schools were submitted to the screening protocol. Principal Component Analysis revealed four factors, accounting for 64.45% of the variance of the Protocol variables: first factor ("pre-reading"), second factor ("decoding"), third factor ("Reading"), and fourth factor "Auditory processing." The factors found corroborate those reported in the National and International literature and have been described as early signs of dyslexia and reading problems.

The role of feedback in implicit and explicit artificial grammar learning: a comparison between dyslexic and non-dyslexic adults

The importance of feedback for learning has been firmly established over the past few decades. The question of whether feedback plays a significant role in the statistical learning abilities of adults with dyslexia, however, is currently unresolved. Here, we examined the role of feedback in grammaticality judgment, type of structural knowledge, and confidence rating in both typically developed and dyslexic adults. We implemented two artificial grammar learning experiments: implicit and explicit. The second experiment was directly analogous to the first experiment in all respects except training format: the standard memorization instruction was replaced with an explicit rule-search instruction. Each experiment was conducted with and without performance feedback. While both groups showed significantly improved learning in the feedback-based explicit artificial grammar learning task, only the typically developed adults demonstrated higher levels of conscious structural knowledge. The present study demonstrates that the basis for the grammaticality judgment of adults with dyslexia differs from that of typically developed adults, regardless of increase in the level of explicitness.