The visual attention (VA) span is defined as the amount of distinct visual elements which can be processed in parallel in a multi-element array. Both recent empirical data and theoretical accounts suggest that a VA span deficit might contribute to developmental dyslexia, independently of a phonological disorder. In this study, this hypothesis was assessed in two large samples of French and British dyslexic children whose performance was compared to that of chronological-age matched control children. Results of the French study (...) show that the VA span capacities account for a substantial amount of unique variance in reading, as do phonological skills. The British study replicates this finding and further reveals that the contribution of the VA span to reading performance remains even after controlling IQ, verbal fluency, vocabulary and single letter identification skills, in addition to phoneme awareness. In both studies, most dyslexic children exhibit a selective phonological or VA span disorder. Overall, these findings support a multi-factorial view of developmental dyslexia. In many cases, developmental reading disorders do not seem to be due to phonological disorders. We propose that a VA span deficit is a likely alternative underlying cognitive deficit in dyslexia. (shrink)

Dehaene (in Reading in the Brain) reviews and finds support for the phonological deficit hypothesis of developmental dyslexia, which proposes that dyslexics have a basic deficit in processing the constituents of spoken words. This hypothesis can be seen as reflecting three associated claims: a) there is only one basic kind of dyslexia; b) all (or most) dyslexic children have phonological impairments, and c) these phonological impairments cause their dyslexia. We consider each of these claims, and the evidence (...) presented by Dehaene, and conclude that questions remain about all three. Phonological deficits alone seem unlikely to be able to account for the complexity and heterogeneity of developmental dyslexia. (shrink)

In this paper we argue that attempts to distinguish between categories of 'dyslexia' and 'poor reader' or 'reading disabled' are scientifically unsupportable, arbitrary and thus potentially discriminatory. We do not seek to veto scientific curiosity in examining underlying factors in reading disability, for seeking greater understanding of the relationship between visual symbols and spoken language is crucial. However, while stressing the potential of genetics and neuroscience for guiding assessment and educational practice at some stage in the future, we argue (...) that there is a mistaken belief that current knowledge in these fields is sufficient to justify a category of dyslexia as a subset of those who encounter reading difficulties. The implications of this debate for large-scale intervention are outlined. (shrink)

We raise the new possibility that people diagnosed with developmental dyslexia (DD) are specialized in explorative cognitive search, and rather than having a neurocognitive disorder, play an essential role in human adaptation. Most DD research has studied educational difficulties, with theories framing differences in neurocognitive processes as deficits. However, people with DD are also often proposed to have certain strengths – particularly in realms like discovery, invention, and creativity – that deficit-centered theories cannot explain. We investigate whether these strengths (...) reflect an underlying explorative specialization. We re-examine experimental studies in psychology and neuroscience using the framework ofcognitive search, whereby many psychological processes involve a trade-off between exploration and exploitation. We report evidence of an explorative bias in DD-associated cognitive strategies. High DD prevalence and an attendant explorative bias across multiple areas of cognition suggest the existence of explorative specialization. An evolutionary perspective explains the combination of findings and challenges the view that individuals with DD have a disorder. In cooperating groups, individual specialization is favored when features that confer fitness benefits are functionally incompatible. Evidence for search specialization suggests that, as with some other social organisms, humans mediate the exploration–exploitation trade-off by specializing in complementary strategies. The existence of a system of collective cognitive search that emerges through collaboration would help to explain our species’ exceptional adaptiveness. It also aligns with evidence for substantial variability during our evolutionary history and the notion that humans are adapted not to a particular habitat but to variability itself. Specialization creates interdependence and necessitates balancing complementary strategies. Reframing DD therefore underscores the urgency of changing certain cultural practices to ensure we do not inhibit adaptation. Key improvements would remove cultural barriers to exploration and nurture explorative learning in education, academia, and the workplace, as well as emphasize collaboration over competition. Specialization in complementary search abilities represents a meta-adaptation; through collaboration, this likely enables human groups (as a species and as cultural systems) to successfully adapt. Cultural change to support this system of collaborative search may therefore be essential in confronting the challenges humanity now faces. (shrink)

Recent findings in autopsy studies, neuroimaging, and neurophysiology indicate that dyslexia is accompanied by fundamental changes in brain anatomy and physiology, involving several anatomical and physiological stages in the processing stream, which can be attributed to anomalous prenatal and immediately postnatal brain development. Epidemiological evidence in dyslexic families led to the discovery of animal models with immune disease, comparable anatomical changes and learning disorders, which have added needed detail about mechanisms of injury and plasticity to indicate that substantial changes (...) in neural networks concerned with perception and cognition are present. It is suggested that the disorder of language, which is the cardinal finding in dyslexic subjects, results from early perceptual anomalies that interfere with the establishment of normal cognitive-linguistic structures, coupled with primarily disordered cognitive processing associated with developmental anomalies of cortical structure and brain asymmetry. This notion is supported by electrophysiological data and by findings of anatomical involvement in subcortical structures close to the input as well as cortical structures involved in language and other cognitive functions. It is not possible at present to determine where the initial insult lies, whether near the input or in high-order cortex, or at both sites simultaneously. (shrink)

: If a child’s development is made possible by interaction with his environment, involving an integration of affective and intellectual processes, dyslexia implies multiple cognitive deficits that cause learning difficulties and over time can affect a child’s sense of self. Inattentive behavior due to incomprehension of classroom tasks can cause compounding of gaps in learning that will lead to a lack of foundational skills. Vygotskij underlines how the zone of proximal development determines the difference between the child’s actual level (...) of development and the level of performance that he achieves under the guidance of a teacher, through imitation; the teacher must focus his efforts on identifying what the child is only able to do in collaboration today but will be able to do independently tomorrow. The main means of interaction between the teacher and the dyslexic child is the language that, materialized and objectified in external speech, then distilled into thought as internal speech can arm dyslexic children with foundational skills. Keywords: L.S. Vygotskij; Dyslexia; Language; Learning; Zone of Proximal Development Un approccio alla dislessia evolutiva da una prospettiva Vygotskijana Riassunto: Se lo sviluppo del bambino è reso possibile dall’interazione con il suo ambiente, attraverso l’integrazione di processi affettivi e intellettuali, la dislessia implica molteplici deficit cognitivi con conseguenti difficoltà di apprendimento, che col tempo possono condizionare la percezione che il bambino ha di sé. Il comportamento disattento in classe, dovuto all’incomprensione dei compiti assegnati, può generare un accumulo tale di lacune nell’apprendimento da condurre al mancato sviluppo di abilità fondamentali. Vygotskij sottolinea come la zona di sviluppo prossimale denoti la differenza tra il livello di sviluppo effettivamente raggiunto dal bambino e le prestazioni ottenute sotto la guida di un insegnante, per mezzo dell’imitazione del maestro. Compito dell’insegnante è concentrare gli sforzi al fine di individuare quanto il bambino è in grado di realizzare oggi in collaborazione, che domani sarà in grado di effettuare autonomamente. Il principale mezzo di interazione tra l’insegnante e il bambino dislessico è il linguaggio che, materializzato e oggettivato nel linguaggio esterno, successivamente condensato nel pensiero come linguaggio interno, può consentire ai bambini dislessici lo sviluppo di abilità fondamentali. Parole chiave: L.S. Vygotskij; Dislessia; Linguaggio; Apprendimento; Zona di sviluppo prossimale. (shrink)

Dehaene (in Reading in the Brain) reviews and finds support for the phonological deficit hypothesis of developmental dyslexia, which proposes that dyslexics have a basic deficit in processing the constituents of spoken words. This hypothesis can be seen as reflecting three associated claims: a) there is only one basic kind of dyslexia; b) all (or most) dyslexic children have phonological impairments, and c) these phonological impairments cause their dyslexia. We consider each of these claims, and the evidence (...) presented by Dehaene, and conclude that questions remain about all three. Phonological deficits alone seem unlikely to be able to account for the complexity and heterogeneity of developmental dyslexia. (shrink)

In this article, we analyse similarities and differences in and between two very topical issues in today’s learning disabilities, namely dyscalculia and dyslexia. More precisely, we introduce the nature of mathematics as science,\,\) which—of course—is the essence of the matter. From this, we deduce that —using both theoretical results, inquiries performed and previous observations on that the brain of a person with dyscalculia and the brain of a person with dyslexia appear to work in essentially the same way—that (...) dyscalculia is not a concept by itself, but merely yet another one of the sad guises of dyslexia. (shrink)

Evolution fuels interindividual variability in neuroplasticity, reflected in brain anatomy and functional connectivity of the expanding neocortical regions subserving reading ability. Such variability is orchestrated by an evolutionarily conserved, competitive balance between epigenetic, stress-induced, and cognitive-growth gene expression programs. An evolutionary developmental model of dyslexia, suggests that prenatal and childhood subclinical stress becomes a risk factor for dyslexia when physiological adaptations to stress promoting adaptive fitness, may attenuate neuroplasticity in the brain regions recruited for reading. Stress has the (...) potential to blunt the cognitive-growth functions of the predominantly right hemisphere Ventral and Dorsal attention networks, which are primed with high entropic levels of synaptic plasticity, and are critical for acquiring beginning reading skills. The attentional networks, in collaboration with the stress-responsive Default Mode network, modulate the entrainment and processing of the low frequency auditory oscillations and visuospatial orienting linked etiologically to dyslexia. Thus, dyslexia may result from positive, but costly adaptations to stress system dysregulation: protective measures that reset the stress/growth balance of processing to favor the Default Mode network, compromising development of the attentional networks. Such a normal-variability conceptualization of dyslexia is at odds with the frequent assumption that dyslexia results from a neurological abnormality. To put the normal-variability model in the broader perspective of the state of the field, a traditional evolutionary account of dyslexia is presented to stimulate discussion of the scientific merits of the two approaches. (shrink)

This paper presents an experimental study investigating artificial grammar learning (AGL) in monolingual and bilingual children, with and without dyslexia, using an original methodology. We administered a serial reaction time (SRT) task, in the form of a modified Simon task, in which the sequence of the stimuli was manipulated according to the rules of a simple Lindenmayer grammar (more specifically, a Fibonacci grammar). By ensuring that the subjects focused on the correct response execution at the motor stage in presence (...) of congruent or incongruent visual stimuli, we could meet the two fundamental criteria for implicit learning: the absence of an intention to learn and the lack of awareness at the level of resulting knowledge. The participants of our studies were four groups of 10-year-old children: 30 Italian monolingual typically developing children, 30 bilingual typically developing children with Italian L2, 24 Italian monolingual dyslexic children and 24 bilingual dyslexic children with Italian L2. Participants were administered the modified Simon task developed according to the rules of the Fibonacci grammar and tested with respect to the implicit learning of three regularities: (i) a red is followed by a blue; (ii) a sequence of two blues is followed by a red and (iii) a blue can be followed either by a red or by a blue. Results clearly support the hypothesis that implicit learning took place, since participants of all groups became increasingly sensitive to the structure of the input, implicitly learning the sequence of the trials and thus appropriately predicting the occurrence of the relevant items, as manifested by faster reaction times in predictable trials. Moreover, group differences were found, with bilinguals being overall faster than monolinguals and dyslexics less accurate than controls. Finally, an advantage of bilingualism in dyslexia was found, with bilingual dyslexics performing consistently better than monolingual dyslexics and, in some conditions, at the level of the two control groups. These results are taken to suggest that bilingualism should be supported also among linguistically impaired individuals. (shrink)

The noisy computation hypothesis of developmental dyslexia (DD) is particularly appealing because it can explain deficits across a variety of domains, such as temporal, auditory, phonological, visual and attentional processes. A key prediction is that noisy computations lead to more variable and less stable word representations. A way to test this hypothesis is through repetition of words, that is, when there is noise in the system, the neural signature of repeated stimuli should be more variable. The hypothesis was tested (...) in an functional magnetic resonance imaging experiment with dyslexic and typical readers by repeating words twelve times. Variability measures were computed both at the behavioral and neural levels. At the behavioral level, we compared the standard deviation of reaction time distributions of repeated words. At the neural level, in addition to standard univariate analyses and measures of intra-item variability, we also used multivariate pattern analyses (representational similarity and classification) to find out whether there was evidence for noisier representations in dyslexic readers compared to typical readers. Results showed that there were no significant differences between the two groups in any of the analyses despite robust results within each group (i.e., high representational similarity between repeated words, good classification of words vs. non-words). In summary, there was no evidence in favor of the idea that dyslexic readers would have noisier neural representations than typical readers. (shrink)

BackgroundResearch during 2020 has been rapidly attending to the impact of COVID-19 on various dimensions of wellbeing on adults and children around the world. However, less attention has focused on the psychoeducational impact on children and their families. To our knowledge, no currently available studies have looked specifically at the impact of COVID-19 on students with dyslexia and their families. Research on this topic is needed to offer greater support for this population of students and their families.ObjectiveThe main objective (...) of this paper is to examine the psychoeducational impact of the required COVID-19 quarantine in Spain among children with dyslexia and their families.MethodA sample of 32 children with dyslexia and their mothers participated in this study.MeasuresChildren and adolescents with dyslexia and their mother completed several measures before the required national quarantine in Spain and again during the quarantine. Children completed measures of depression, state anxiety, reading activity, and reading motivation. Mothers provided demographic information and completed measures related to students’ emotional and behavioral difficulties as well as parenting stress, parental distress, and a questionnaire about educational problems during quarantine.ResultsMajor findings showed that during quarantine, children with dyslexia had increased levels of depression and anxiety symptoms, and parents perceived their children as having more emotional symptoms, hyperactivity-inattention, and conduct problems. During quarantine, children and adolescents with dyslexia also showed less reading activity and less reading motivation. Parents also reported significantly more stress, during quarantine compared to pre-quarantine conditions. Some demographic and psychological variables predicted children’s state anxiety as well parental stress. The questionnaire related to impacts of quarantine also revealed several important findings. For example, nearly all parents of children with dyslexia reported difficulties in establishing study routines, that the quarantine negatively affected their child’s learning, and that they did not receive sufficient help from teachers on how to support their child’s learning. Additionally, the vast majority of the parents were very worried about the child’s learning and school success, the child’s motivation and interest in reading, the child’s peer relations, and the professional skills of the child’s teacher.ConclusionThis study offers a preliminary investigation into this topic and elucidates several psychoeducational challenges that children with dyslexia and their families have experienced during the quarantine in Spain. Study findings highlight the need to provide immediate support for children with dyslexia and emphasizes the importance of developing prevention programs to mitigate any future negative impacts of COVID-19 on children with dyslexia and their parents. (shrink)