Double Trouble: Visual and Phonological Impairments in English Dyslexic Readers

Developmental surface dyslexia and dysgraphia in a child with corpus callosum agenesis: an approach to diagnosis and treatment

We present a case study detailing cognitive performance, functional neuroimaging, and effects of a hypothesis-driven treatment in a 10-year-old girl diagnosed with complete, isolated corpus callosum agenesis. Despite having average overall intellectual abilities, the girl exhibited profound surface dyslexia and dysgraphia. Spelling treatment significantly and persistently improved her spelling of trained irregular words, and this improvement generalized to reading accuracy and speed of trained words. Diffusion weighted imaging revealed strengthened intrahemispheric white matter connectivity of the left temporal cortex after treatment and identified interhemispheric connectivity between the occipital lobes, likely facilitated by a pathway crossing the midline via the posterior commissure. This case underlines the corpus callosum's critical role in lexical reading and writing. It demonstrates that spelling treatment may enhance interhemispheric connectivity in corpus callosum agenesis through alternative pathways, boosting the development of a more efficient functional organization of the visual word form area within the left temporo-occipital cortex.

Lived Experiences of Everyday Memory in Adults with Dyslexia: A Thematic Analysis

Dyslexia-related difficulties with memory are well documented under laboratory conditions and via self-report questionnaires. However, the voice of the individual with dyslexia regarding the lived experience of memory across different memory systems and different daily settings is currently lacking. To address this gap in the literature, semi-structured in-depth interviews were conducted with 12 adult female university students with dyslexia. Questions probed different memory systems and experiences across different settings, with interviewees also being asked about their use of technology to support their memory. Two overarching themes were identified in the subsequent thematic analysis. The theme of fallibility of memory had two sub-themes of (i) a lack of trust and confidence in memory and (ii) factors contributing to memory failure. The second theme, facilitators of memory, also consisted of two sub-themes, relating to (i) a preference for traditional tools to support memory and (ii) the use of digital tools to support memory: benefits and limitations. The current study gives insights into the rich and complex extended and distributed cognitive systems of adults with dyslexia. The implications of the findings for dyslexia theory, support in educational and work settings as well as assistive technology development are considered.

Visual attention modulates the transition from fine-grained, serial processing to coarser-grained, more parallel processing: A computational modeling study

During reading acquisition, beginning readers transition from serial to more parallel processing. The acquisition of word specific knowledge through orthographic learning is critical for this transition. However, the processes by which orthographic representations are acquired and fine-tuned as learning progresses are not well understood. Our aim was to explore the role of visual attention in this transition through computational modeling. We used the BRAID-Learn model, a Bayesian model of visual word recognition, to simulate the orthographic learning of 700 4-to 10-letter English known words and novel words, presented 5 times each to the model. The visual attention quantity available for letter identification was manipulated in the simulations to assess its influence on the learning process. We measured the overall processing time and number of attentional fixations simulated by the model across exposures and their impact on two markers of serial processing, the lexicality and length effects, depending on visual attention quantity. Results showed that the two lexicality and length effects were modulated by visual attention quantity. The quantity of visual attention available for processing further modulated novel word orthographic learning and the evolution of the length effect on processing time and number of attentional fixations across repeated exposures to novel words. The simulated patterns are consistent with behavioral data and the developmental trajectories reported during reading acquisition. Overall, the model predicts that the efficacy of orthographic learning depends on visual attention quantity and that visual attention may be critical to explain the transition from serial to more parallel processing.

A New Immersive Rehabilitation Therapy (MoveR) Improves More Than Classical Visual Training Visual Perceptual Skills in Dyslexic Children

In this study, we wonder how to compare the improvement in visual perceptual skills (by using the test of visual perceptual skills, TVPS) in children with dyslexia after two visual training types (a new immersive rehabilitation therapy called MoveR, and the classical vision therapy). Thirty-nine children with dyslexia were enrolled in the study. They were split into two groups (G1 and G2) matched in IQ (intelligence quotient), sex, and age. Children of the group G1 underwent to MoveR training while children of the group G2 underwent to visual training. TVPS scores of four subtests were assessed twice before and 6 months after the two different types of training (MoveR or visual). MoveR training is an immersive therapy to reinforce visual discrimination, visual attention, saccadic/vergence system and spatial orientation. Visual therapy is based by training different types of eyes movements (horizontal, vertical and oblique pursuits and saccades, convergence and divergence movements), reading task and some exercise for improving eyes-head coordination. Each training type lasted 30 min a day, five days a week, for two weeks. Before training, the TVPS scores of the four subtests measured were statistically similar for both groups of children with dyslexia (G1 and G2). After training, both group of children (G1 and G2) improved the TVPS score of the four subtests assessed; however, such improvement reached significance in G1 only. We conclude that MoveR training could be a more useful tool than classical visual training to improve visual perceptual abilities in dyslexic children. Follow up studies on a larger number of dyslexic children will be necessary in order to explore whether such improvement persists over time and its eventual implication in reading or other classroom's activities.

Dyslexia with and without Irlen syndrome: A study of influence on abilities and brain-derived neurotrophic factor level

The presence of comorbid Irlen syndrome (IS) in children with developmental dyslexia (DD) may have an impact on their reading and cognitive abilities. Furthermore, the brain-derived neurotrophic factor (BDNF) was reported to be expressed in brain areas involved in cognitive and visual processing. The aim of this study was to evaluate some cognitive abilities of a group of dyslexic children with IS and to measure and compare the plasma BDNF level to dyslexic children without IS and neurotypical (NT) children. The participants were 60 children with DD (30 in the DD + IS group; 30 in the DD group) and 30 NT children. The Irlen reading perceptual scale, the Stanford Binet intelligence scale, 4th ed, the dyslexia assessment test, and the Illinois test of psycholinguistic abilities were used. The BDNF level was measured using the enzyme-linked immunosorbent assay. One-minute writing and visual closure deficits were more prevalent, while phonemic segmentation deficits were less prevalent in the DD + IS group compared to the DD group. The BDNF level in the DD groups was lower than that in NT children (p < 0.001). Some reading and non-reading tasks were influenced by the presence of a coexisting IS. The reduced BDNF level could play a role in the deficits noticed in the abilities of children with DD.

Self-reported symptoms of developmental dyslexia predict impairments in everyday cognition in adults

BACKGROUND

Research into the impact of dyslexia on everyday cognition in adults with dyslexia is relatively limited and has tended to focus on university students.

AIMS AND METHODS

The present online study aimed to add to this small corpus by investigating the everyday effects of dyslexia on memory and attention in a larger community-based sample. One hundred and seventy-two adult volunteers completed five well-established self-report questionnaires, assessing dyslexia and Attention Deficit Hyperactivity Disorder symptomatology and everyday experiences with memory, attention, and mind-wandering.

RESULTS

After controlling for ADHD symptomatology, hierarchical regression analyses revealed that higher levels of dyslexia-related symptomatology were associated with greater, more frequent everyday memory and attentional problems, but not with a greater propensity to mind-wandering. Increased levels of dyslexia symptomatology were positively associated with the frequency of both everyday attentional lapses (at least when performing a pair of tasks or easy tasks while inhibiting intervening stimuli) and everyday memory failures. No significant associations were found between dyslexia symptomatology and attentional lapses when performing difficult tasks in the presence of concurrent stimuli or between dyslexia symptomatology and the propensity to mind-wandering.

CONCLUSIONS AND IMPLICATIONS

Dyslexia symptomatology was perceived as being associated with more everyday memory and attention problems in adulthood. Adjustments to educational and workplace settings and interventions to compensate for these difficulties are proposed.

Probabilistic Decision-Making in Children With Dyslexia

Background

Neurocognitive mechanisms underlying developmental dyslexia (dD) remain poorly characterized apart from phonological and/or visual processing deficits. Assuming such deficits, the process of learning complex tasks like reading requires the learner to make decisions (i.e., word pronunciation) based on uncertain information (e.g., aberrant phonological percepts)-a cognitive process known as probabilistic decision making, which has been linked to the striatum. We investigate (1) the relationship between dD and probabilistic decision-making and (2) the association between the volume of striatal structures and probabilistic decision-making in dD and typical readers.

Methods

Twenty four children diagnosed with dD underwent a comprehensive evaluation and MRI scanning (3T). Children with dD were compared to age-matched typical readers (n = 11) on a probabilistic, risk/reward fishing task that utilized a Bayesian cognitive model with game parameters of risk propensity (γ+) and behavioral consistency (β), as well as an overall adjusted score (average number of casts, excluding forced-fail trials). Volumes of striatal structures (caudate, putamen, and nucleus accumbens) were analyzed between groups and associated with game parameters.

Results

dD was associated with greater risk propensity and decreased behavioral consistency estimates compared to typical readers. Cognitive model parameters associated with timed pseudoword reading across groups. Risk propensity related to caudate volumes, particularly in the dD group.

Conclusion

Decision-making processes differentiate dD, associate with the caudate, and may impact learning mechanisms. This study suggests the need for further research into domain-general probabilistic decision-making in dD, neurocognitive mechanisms, and targeted interventions in dD.

Shallow or deep? The impact of orthographic depth on visual processing impairments in developmental dyslexia

The extent to which impaired visual and phonological mechanisms may contribute to the manifestation of developmental dyslexia across orthographies of varying depth has yet to be fully established. By adopting a cross-linguistic approach, the current study aimed to explore the nature of visual and phonological processing in developmental dyslexic readers of shallow (Italian) and deep (English) orthographies, and specifically the characterisation of visual processing deficits in relation to orthographic depth. To achieve this aim, we administered a battery of non-reading visual and phonological tasks. Developmental dyslexics performed worse than typically developing readers on all visual and phonological tasks. Critically, readers of the shallow orthography were disproportionately impaired on visual processing tasks. Our results suggest that the impaired reading and associated deficits observed in developmental dyslexia are anchored by dual impairments to visual and phonological mechanisms that underpin reading, with the magnitude of the visual deficit varying according to orthographic depth.

Automaticity and Executive Abilities in Developmental Dyslexia: A Theoretical Review

Cognitive difficulties are well documented in developmental dyslexia but they present a challenge to dyslexia theory. In this paper, the Model of the Control of Action is proposed as a theoretical explanation of how and why deficits in both automaticity and executive abilities are apparent in the cognitive profiles of dyslexia and how these deficits might relate to literacy difficulties. This theoretical perspective is used to consider evidence from different cognitive domains. The neuroanatomical underpinnings of automaticity and executive abilities are then discussed in relation to the understanding of dyslexia. Links between reading, writing, and executive function are considered. The reviewed evidence suggests that dyslexia theory should consider an interaction between procedural learned behaviour (automaticity) and higher-order (executive) abilities. The capacity to handle environmental interference, develop and engage adaptive strategies accordingly, and plan actions all require interactions between the cerebellum and the prefrontal cortex (PFC). Difficulties in these areas might explain both impairments in the cumulative development of literacy skills in childhood and general task management in everyday life in adulthood. It is suggested that improved measures are required to assess this cerebellar–PFC interaction and to allow early identification of future literacy difficulties, allowing implementation of timely interventions and reasonable adjustments.

What Is Going on with Visual Attention in Reading and Dyslexia? A Critical Review of Recent Studies

This critical review examined current issues to do with the role of visual attention in reading. To do this, we searched for and reviewed 18 recent articles, including all that were found after 2019 and used a Latin alphabet. Inspection of these articles showed that the Visual Attention Span task was run a number of times in well-controlled studies and was typically a small but significant predictor of reading ability, even after potential covariation with phonological effects were accounted for. A number of other types of tasks were used to examine different aspects of visual attention, with differences between dyslexic readers and controls typically found. However, most of these studies did not adequately control for phonological effects, and of those that did, only very weak and non-significant results were found. Furthermore, in the smaller studies, separate within-group correlations between the tasks and reading performance were generally not provided, making causal effects of the manipulations difficult to ascertain. Overall, it seems reasonable to suggest that understanding how and why different types of visual tasks affect particular aspects of reading performance is an important area for future research.

Holistic processing of faces and words predicts reading accuracy and speed in dyslexic readers

We compared the performance of dyslexic and typical readers on two perceptual tasks, the Vanderbilt Holistic Face Processing Task and the Holistic Word Processing Task. Both yield a metric of holistic processing that captures the extent to which participants automatically attend to information that is spatially nearby but irrelevant to the task at hand. Our results show, for the first time, that holistic processing of faces is comparable in dyslexic and typical readers but that dyslexic readers show greater holistic processing of words. Remarkably, we show that these metrics predict the performance of dyslexic readers on a standardized reading task, with more holistic processing in both tasks associated with higher accuracy and speed. In contrast, a more holistic style on the words task predicts less accurate reading of both words and pseudowords for typical readers. We discuss how these findings may guide our conceptualization of the visual deficit in dyslexia.

Neuro-Behavioral Correlates of Executive Dysfunctions in Dyslexia Over Development From Childhood to Adulthood

Dyslexia is a neurobiological learning disability in the reading domain that has symptoms in early childhood and persists throughout life. Individuals with dyslexia experience difficulties in academia and cognitive and emotional challenges that can affect wellbeing. Early intervention is critical to minimize the long-term difficulties of these individuals. However, the behavioral and neural correlates which predict dyslexia are challenging to depict before reading is acquired. One of the precursors for language and reading acquisition is executive functions (EF). The present review aims to highlight the current atypicality found in individuals with dyslexia in the domain of EF using behavioral measures, brain mapping, functional connectivity, and diffusion tensor imaging along development. Individuals with dyslexia show EF abnormalities in both behavioral and neurobiological domains, starting in early childhood that persist into adulthood. EF impairment precedes reading disability, therefore adding an EF assessment to the neuropsychological testing is recommended for early intervention. EF training should also be considered for the most comprehensive outcomes.

Overcoming theoretical stagnation through cultural–historical neuropsychology: The case of dyslexia

In this article we argue that cultural–historical neuropsychology manages to escape the theoretical stagnation that characterises the field of dyslexia. To support our argumentation, we first define cultural–historical psychology and neuropsychology and determine their subject matter. Afterwards, we provide an outline of how reading and reading difficulties are perceived through the prism of cultural–historical neuropsychology. We then discuss several mainstream conceptualisations of dyslexia that contribute to the theoretical stagnation in the field. Finally, we explain how cultural–historical neuropsychology avoids each theoretical barrier imposed by mainstream conceptualisations.

Selective visual attention skills differentially predict decoding and reading comprehension performance across reading ability profiles

BACKGROUND

The purpose of this study was to examine the relationship between selective visual attention (SVA), reading decoding, listening comprehension and reading comprehension in children with and without a reading disorder.

METHODS

We used longitudinal data from the Avon Longitudinal Study of Parents and Children. We split children into four groups: Typical Readers, Dyslexics, Poor Comprehenders and Comorbid Reading Disorder. We included measures of single word reading, nonword reading, spelling, phonological processing, vocabulary, receptive language, nonverbal intelligence, selective attention and reading comprehension. We used analysis of variance, correlations and structural equation modelling to examine the relationship between SVA and reading. We fit two possible models: SVA Indirect and SVA Direct. The difference between these models was the inclusion of a direct path from SVA to reading comprehension.

RESULTS

We examined an indirect model, where SVA predicted reading comprehension through word decoding and listening comprehension, and a direct model, which included a pathway from SVA to reading comprehension. Based on our analysis of variance and correlation results, we collapsed the Dyslexic, Poor Comprehenders and Comorbid Reading Disorder groups for the structural equation modelling. We found evidence that for Typical Readers, an indirect model was the best fit, whereas the direct model was the best model for children with a reading disorder.

CONCLUSIONS

Selective visual attention is related to reading comprehension. This relationship differs for children with and without a reading disorder.

Occurrence of reading and writing cognitive processes and perception visual skills in students with Visual Dyslexia

PURPOSE

to evaluate and classify visual dyslexic students, considering that developmental dyslexia subtypes are not differentiated in most diagnoses and that they affect a generalized approach.

METHODS

Cross-sectional, observational, analytical study composed of 80 students, divided into two groups, GA (dyslexics) and GB (without complaints of learning difficulties) using PROLEC (proof of assessment of reading processes), TVPS - 3 (Visual Test of Perceptual Skills) and TPMBO (Bruininks-Oseretsky Motor Proficiency Test) - subtests 7 and 8.

RESULTS

Comparing the groups, the students of GA presented inferior performance in all the PROLEC tests and in the TVPS3 tests. The TPMBO tests of visuomotor coordination and manual dexterity tests were inferior. In a second stage, screening the visual dyslexics, 12 (30%) schoolchildren were found, who presented better performance in reading frequent words, when compared to the performance in reading infrequent words and pseudowords. In the visual perceptual skills (TVPS-3), they obtained values below 50%, except for the subscale constancy of form. The occurrences of exchanges in reading aloud were in confusion of letters, syllables or words with little difference in the way of writing, but different in the direction, the same students did not present exchanges or confusions between letters, which have the same point and manner of articulation, and whose sounds are acoustically close.

CONCLUSION

Thus, characterizing the dyslexia subtype is fundamental, because the application of therapeutic techniques will depend on the correct focus of the observed changes. Therefore, an accurate and multidisciplinary diagnosis is required.

The Clock Counts - Length Effects in English Dyslexic Readers

In reading, length effects (LEs) are defined as an increment in the time taken to read as a function of word length and may indicate whether reading is proceeding in an efficient whole word fashion or by serial letter processing. LEs are generally considered to be a pathognomonic symptom of developmental dyslexia (DD) and predominantly have been investigated in transparent orthographies where reading impairment is characterized as slow and effortful. In the present study a sample of 18 adult participants with DD were compared to a matched sample of typical developing readers to investigate whether the LE is a critical aspect of DD in an opaque orthography, English. We expected that the DD group would present with marked LEs, in both words and non-words, compared to typical developing readers. The presence of LEs in the DD group confirmed our prediction. These effects were particularly strong in low frequency words and in non-words, as observed in reading speed. These preliminary findings may have important theoretical implications for current understanding of DD.