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Developmental Dyslexia (developmental + dyslexia)

Distribution by Scientific Domains

Psychology	84%
3 Other Domains	16%

Selected Abstracts

Developmental dyslexia and explicit long-term memory

DYSLEXIA, Issue 3 2010
Deny Menghini
Abstract The reduced verbal long-term memory capacities often reported in dyslexics are generally interpreted as a consequence of their deficit in phonological coding. The present study was aimed at evaluating whether the learning deficit exhibited by dyslexics was restricted only to the verbal component of the long-term memory abilities or also involved visual-object and visual-spatial domain. A further goal of the present study was to investigate the predictive value of non-verbal long-term memory abilities with respect to word and non-word reading in dyslexic children. In accordance with these aims, performances of 60 dyslexic children were compared with that of 65 age-matched normal readers on verbal, visual-spatial and visual-object task. Results documented a generalized impairment of episodic long-term memory capacities in dyslexic children and the results did not vary as a function of children's age. Furthermore, in addition to verbal measures, also individual differences in non-verbal long-term memory tasks turn out to be good predictors of reading difficulties in dyslexics. Our findings indicate that the long-term memory deficit in dyslexia is not limited to the dysfunction of phonological components but also involves visual-object and visual-spatial aspect, thus suggesting that dyslexia is associated to multiple cognitive deficits. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Visual deficits in developmental dyslexia: relationships between non-linguistic visual tasks and their contribution to components of reading

DYSLEXIA, Issue 2 2008
Manon W. Jones
Abstract Developmental dyslexia is often characterized by a visual deficit, but the nature of this impairment and how it relates to reading ability is disputed (Brain 2003; 126: 841,865). In order to investigate this issue, we compared groups of adults with and without dyslexia on the Ternus, visual-search and symbols tasks. Dyslexic readers yielded more errors on the visual-search and symbols tasks compared with non-dyslexic readers. A positive correlation between visual-search and symbols task performance suggests a common mechanism shared by these tasks. Performance on the visual-search and symbols tasks also correlated with non-word reading and rapid automatized naming measures, and visual search contributed independent variance to non-word reading. The Ternus task did not discriminate reading groups nor contributed significant variance to reading measures. We consider how visual-attention processes might underlie specific component reading measures. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Balancing and pointing tasks in dyslexic and control adults

DYSLEXIA, Issue 4 2006
Catherine J. Stoodley
Abstract Developmental dyslexia may affect as much as 15% of the population, but the aetiology of the disorder is still being debated. The cerebellar theory of dyslexia proposes that cerebellar dysfunction could lead to the myriad of symptoms seen in dyslexic individuals, both in literacy and non-literacy domains. The cerebellum is crucial to the fluent performance of motor skills. Previous studies have found that dyslexic children are worse than control children on certain motor and balancing tasks. Here the performance of 28 dyslexic compared to 26 control adults on rapid pointing and balancing measures, tasks which are thought to reflect cerebellar function, was investigated. There were no significant differences between the dyslexic and control participants on the balancing tasks or when the speed and accuracy of pointing were analysed separately. However, when the speed and accuracy of pointing were combined, the dyslexic participants showed poorer performance than the controls (p = 0.045). Furthermore, there were significant relationships between performance on the pointing task and literacy skills, and regression analysis showed that the error and speed of pointing contributed significantly to the variance in literacy skill. The implications for the role of the cerebellum and processing speed in dyslexia are discussed. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Developmental dyslexia in Norwegian: evidence from single-case studies

DYSLEXIA, Issue 1 2006
Trude Nergård-Nilssen
Abstract This study provides detailed descriptions of the reading impairments in four 10-year-old Norwegian children with dyslexia. In all four cases reading comprehension was well in advance of the children's slow and inaccurate word-recognition skills. Phonological decoding (as assessed by pseudohomophone and nonword reading) appeared relatively unimpaired in three of the dyslexic cases, both in terms of speed and accuracy. However, reading errors showed that these children had particular difficulties with both phoneme length and phoneme quality awareness in reading. A ,phonemic identification deficit' account for developmental dyslexia in Norwegian children is suggested. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Speech- and sound-segmentation in dyslexia: evidence for a multiple-level cortical impairment

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2006
T. Kujala
Abstract Developmental dyslexia involves deficits in the visual and auditory domains, but is primarily characterized by an inability to translate the written linguistic code to the sound structure. Recent research has shown that auditory dysfunctions in dyslexia might originate from impairments in early pre-attentive processes, which affect behavioral discrimination. Previous studies have shown that whereas dyslexic individuals are deficient in discriminating sound distinctions involving consonants or simple pitch changes, discrimination of other sound aspects, such as tone duration, is intact. We hypothesized that such contrasts that can be discriminated by dyslexic individuals when heard in isolation are difficult to identify when occurring within words or structurally similar complex sound patterns. In the current study, we addressed how segments of pseudo-words and their non-speech counterparts are processed in dyslexia. We assessed the detection of long-duration differences in segments of these stimuli and identified the brain processes that could be associated with the behavioral results. Consistent with previous studies, we found no early cortical sound-duration discrimination deficit in dyslexia. However, differences between impaired and non-impaired readers were found in the brain processes associated with sound-change recognition as well as in the behavioral performance. This suggests that even when the early, automatic, sound discrimination processes are intact in dyslexic individuals, deficits in the later, attention-dependent processes may lead to impaired perception of speech and other complex sounds. [source]

Rapid processing of letters, digits and symbols: what purely visual-attentional deficit in developmental dyslexia?

DEVELOPMENTAL SCIENCE, Issue 4 2010
Johannes C. Ziegler
Visual-attentional theories of dyslexia predict deficits for dyslexic children not only for the perception of letter strings but also for non-alphanumeric symbol strings. This prediction was tested in a two-alternative forced-choice paradigm with letters, digits, and symbols. Children with dyslexia showed significant deficits for letter and digit strings but not for symbol strings. This finding is difficult to explain for visual-attentional theories of dyslexia which postulate identical deficits for letters, digits and symbols. Moreover, dyslexics showed normal W-shaped serial position functions for letter and digit strings, which suggests that their deficit is not due to an abnormally small attentional window. Finally, the size of the deficit was identical for letters and digits, which suggests that poor letter perception is not just a consequence of the lack of reading. Together then, our results show that symbols that map onto phonological codes are impaired (i.e. letters and digits), whereas symbols that do not map onto phonological codes are not impaired. This dissociation suggests that impaired symbol-sound mapping rather than impaired visual-attentional processing is the key to understanding dyslexia. [source]

Visual spatial attention and speech segmentation are both impaired in preschoolers at familial risk for developmental dyslexia

DYSLEXIA, Issue 3 2010
Andrea Facoetti
Abstract Phonological skills are foundational of reading acquisition and impaired phonological processing is widely assumed to characterize dyslexic individuals. However, reading by phonological decoding also requires rapid selection of sublexical orthographic units through serial attentional orienting, and recent studies have shown that visual spatial attention is impaired in dyslexic children. Our study investigated these different neurocognitive dysfunctions, before reading acquisition, in a sample of preschoolers including children with (N=20) and without (N=67) familial risk for developmental dyslexia. Children were tested on phonological skills, rapid automatized naming, and visual spatial attention. At-risk children presented deficits in both visual spatial attention and syllabic segmentation at the group level. Moreover, the combination of visual spatial attention and syllabic segmentation scores was more reliable than either single measure for the identification of at-risk children. These findings suggest that both visuo-attentional and perisylvian-auditory dysfunctions might adversely affect reading acquisition, and may offer a new approach for early identification and remediation of developmental dyslexia. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Do children with developmental dyslexia have impairments in implicit learning?

DYSLEXIA, Issue 2 2010
Elpis V. Pavlidou
Abstract We explored implicit learning in a group of typically developing and developmental dyslexic primary school children (9,12,y) using a modified artificial grammar learning task. Performance was calculated using two measures of performance: a perfect free recall (PFR) score and a grammaticality judgment score. Both groups of children required the same amount of exposure to memorize the items (i.e. PFR performance) (t(30)=1.620, p>0.05; p -value reported two-tailed). However, repeated measures ANOVA (Participant type × Grammaticality × Chunk strength) revealed a Participant type effect for grammaticality judgment scores (F(1,30)=4.521, p<0.05; p -value reported two-tailed). Typically developing children showed above chance performance in terms of both grammaticality and chunk strength of the stimuli. Children with developmental dyslexia on the other hand, failed to show implicit learning irrespective of the substring characteristics (i.e. grammaticality or chunk strength). We propose that children with developmental dyslexia may be impaired in their implicit rule abstraction mechanism, which can partially explain their persistent reading problems. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Visual deficits in developmental dyslexia: relationships between non-linguistic visual tasks and their contribution to components of reading

Sensitivity to visual and auditory stimuli in children with developmental dyslexia

DYSLEXIA, Issue 2 2008
Bernardine King
Abstract This study considered the extent to which 23 children with dyslexia differed from 23 reading age (RA) and 23 chronological age (CA) matched controls in their ability to make temporal judgements about auditory and visual sequences of stimuli, and in the speed of their reactions to the onsets and offsets of visual and auditory stimuli. The children with dyslexia were slower (p,=,0.039) than the CA controls in their reactions to non-verbal auditory onsets (tones), were less able to recognize the first stimulus of a sequence of tones (p,=,0.022), and were less accurate in identifying the initial phoneme of a sequence of three (p,<,0.001). These characteristics may be manifestations of an impaired temporal processing system for rapid auditory stimuli. CA controls responded more quickly to tone onsets than to tone offsets (p,=,0.025), but the dyslexic and RA groups showed no significant difference (p,>,0.05) in their reaction times to onsets and offsets of these non-verbal auditory stimuli. Dyslexic readers showed impairment compared with CA controls in responding to the last of a sequence of three non-verbal visual stimuli (shapes), p,=,0.02. Reaction times in the visual and auditory onset and offset tasks were richly intercorrelated in the control groups, but the dyslexic group did not show as many significant correlations in reaction times between the auditory and visual domains, or between the onset and offset RTs within each modality. These results suggest that there may be a less integrated cross-modal and intra-modal temporal system in children with dyslexia than in controls. In many of the measures in this study, the performance of the dyslexic group resembled that of the RA control group but differed from CA controls, which implies a developmental delay. The possibility that such a cognitive delay may be related to an underlying neurological disorder is discussed. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Dichotic listening deficits in children with dyslexia

DYSLEXIA, Issue 1 2008
Deborah W. Moncrieff
Abstract Several auditory processing deficits have been reported in children with dyslexia. In order to assess for the presence of a binaural integration type of auditory processing deficit, dichotic listening tests with digits, words and consonant,vowel (CV) pairs were administered to two groups of right-handed 11-year-old children, one group diagnosed with developmental dyslexia and an age-matched control group. Dyslexic children performed more poorly than controls from their left ears when listening to digits and words and from their right ears when listening to CVs. Direction of ear advantage varied across individuals in both groups when tested with digits and CVs, but ear advantage was stable with words. Several factors that may have contributed to inconsistencies in direction of ear advantage are discussed. When the children were tested in a directed response mode, degree of ear advantage differed significantly between groups with both words and digits. More dyslexic than control children demonstrated clinically significant reductions in dichotic listening performance, but no uniform pattern of deficit emerged. Only the double correct score and the left ear score with CV pairs were predictive of word recognition performance in dyslexic children. Binaural integration deficits are present in some children with dyslexia. Auditory processing disorder assessment may help delineate factors that underlie or are associated with reading impairment in this population. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Brain responses to subject-verb agreement violations in spoken language in developmental dyslexia: an ERP study

DYSLEXIA, Issue 2 2006
Judith E. Rispens
Abstract This study investigates the presence and latency of the P600 component in response to subject,verb agreement violations in spoken language in people with and without developmental dyslexia. The two groups performed at-ceiling level on judging the sentences on their grammaticality, but the ERP data revealed subtle differences between them. The P600 tended to peak later in the left posterior region in the dyslexic group compared with the control group. In addition, the group of dyslexic subjects did not show a P600 in response to sentences with a plural NP subject. These results suggest that brain activation involved in syntactic repair is more affected by linguistic complexity in developmental dyslexia compared with non-dyslexic individuals. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Developmental dyslexia in Norwegian: evidence from single-case studies

Measurement error: implications for diagnosis and discrepancy models of developmental dyslexia

DYSLEXIA, Issue 3 2005
Sue M. Cotton
Abstract The diagnosis of developmental dyslexia (DD) is reliant on a discrepancy between intellectual functioning and reading achievement. Discrepancy-based formulae have frequently been employed to establish the significance of the difference between ,intelligence' and ,actual' reading achievement. These formulae, however, often fail to take into consideration test reliability and the error associated with a single test score. This paper provides an illustration of the potential effects that test reliability and measurement error can have on the diagnosis of dyslexia, with particular reference to discrepancy models. The roles of reliability and standard error of measurement (SEM) in classic test theory are also briefly reviewed. This is followed by illustrations of how SEM and test reliability can aid with the interpretation of a simple discrepancy-based formula of DD. It is proposed that a lack of consideration of test theory in the use of discrepancy-based models of DD can lead to misdiagnosis (both false positives and false negatives). Further, misdiagnosis in research samples affects reproducibility and generalizability of findings. This in turn, may explain current inconsistencies in research on the perceptual, sensory, and motor correlates of dyslexia. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Visual, auditory and cross-modal processing of linguistic and nonlinguistic temporal patterns among adult dyslexic readers

DYSLEXIA, Issue 2 2005
Ann Meyler
Abstract This study examined visual, auditory, and cross-modal temporal pattern processing at the nonlinguistic and sublexical linguistic levels, and the relationships between these abilities and decoding skill. The central question addressed whether dyslexic readers are impaired in their perception of timing, as assessed by sensitivity to rhythm. Participants were college-level adult dyslexic and normal readers. The dyslexic adults evidenced generalized impairment in temporal processing: they were less accurate and slower than normal readers when required to detect the temporal gap that differentiated pairs of patterns. Impairment was greatest when processing visual syllables. Temporal pattern processing correlated to decoding ability only among normal readers. It is suggested that high-functioning dyslexics may cope with temporal processing problems by adopting a predominantly holistic, orthographic strategy when decoding. It is proposed that there may be cumulative effects of processing demands from different sources including modality, stimulus complexity, and linguistic demands, and that combinations of these may interact to impact temporal processing ability. Moreover, there may be fundamentally distinct and dissociable temporal processing abilities, each of which may be differently linked developmental dyslexia. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Surface and phonological subtypes of adult developmental dyslexia

DYSLEXIA, Issue 3 2002
Claire Zabell
Abstract In order to assess the efficacy of phonological versus surface dyslexia subtyping within an adult dyslexic population, 45 adult dyslexics were assessed on the Castles and Coltheart (1993) irregular word and non-word reading tasks. Based on the performance of a matched group of 28 non-dyslexics, between 62 and 75% of the dyslexics were divided into phonological and surface subtypes. Phonological dyslexics were those individuals who presented evidence of relatively poor or inefficient non-word reading, whereas the surface dyslexics were those who indicated relative difficulties with irregular word reading. The proportions of dyslexics within each subtype varied according to the use of accuracy-based or latency-based procedures, but were consistent with previous findings with children. Subsequent comparisons between the groups on measures of phonological processing, lexical access and word knowledge/recognition indicated few differences between the two subtypes and, in particular, no differences on measures of phonological ability. The lack of observed differences on such measures casts doubt on the efficacy of this procedure for explaining individual differences amongst adult dyslexics and as a practical procedure for diagnosis and intervention. Copyright © 2002 John Wiley & Sons, Ltd. [source]

The magnocellular theory of developmental dyslexia

DYSLEXIA, Issue 1 2001
John Stein
Abstract Low literacy is termed ,developmental dyslexia' when reading is significantly behind that expected from the intelligence quotient (IQ) in the presence of other symptoms,incoordination, left,right confusions, poor sequencing,that characterize it as a neurological syndrome. 5,10% of children, particularly boys, are found to be dyslexic. Reading requires the acquisition of good orthographic skills for recognising the visual form of words which allows one to access their meaning directly. It also requires the development of good phonological skills for sounding out unfamiliar words using knowledge of letter sound conversion rules. In the dyslexic brain, temporoparietal language areas on the two sides are symmetrical without the normal left-sided advantage. Also brain ,warts' (ectopias) are found, particularly clustered round the left temporoparietal language areas. The visual magnocellular system is responsible for timing visual events when reading. It therefore signals any visual motion that occurs if unintended movements lead to images moving off the fovea (,retinal slip'). These signals are then used to bring the eyes back on target. Thus, sensitivity to visual motion seems to help determine how well orthographic skill can develop in both good and bad readers. In dyslexics, the development of the visual magnocellular system is impaired: development of the magnocellular layers of the dyslexic lateral geniculate nucleus (LGN) is abnormal; their motion sensitivity is reduced; many dyslexics show unsteady binocular fixation; hence poor visual localization, particularly on the left side (left neglect). Dyslexics' binocular instability and visual perceptual instability, therefore, can cause the letters they are trying to read to appear to move around and cross over each other. Hence, blanking one eye (monocular occlusion) can improve reading. Thus, good magnocellular function is essential for high motion sensitivity and stable binocular fixation, hence proper development of orthographic skills. Many dyslexics also have auditory/phonological problems. Distinguishing letter sounds depends on picking up the changes in sound frequency and amplitude that characterize them. Thus, high frequency (FM) and amplitude modulation (AM) sensitivity helps the development of good phonological skill, and low sensitivity impedes the acquisition of these skills. Thus dyslexics' sensitivity to FM and AM is significantly lower than that of good readers and this explains their problems with phonology. The cerebellum is the head ganglion of magnocellular systems; it contributes to binocular fixation and to inner speech for sounding out words, and it is clearly defective in dyslexics. Thus, there is evidence that most reading problems have a fundamental sensorimotor cause. But why do magnocellular systems fail to develop properly? There is a clear genetic basis for impaired development of magnocells throughout the brain. The best understood linkage is to the region of the Major Histocompatibility Complex (MHC) Class 1 on the short arm of chromosome 6 which helps to control the production of antibodies. The development of magnocells may be impaired by autoantibodies affecting the developing brain. Magnocells also need high amounts of polyunsaturated fatty acids to preserve the membrane flexibility that permits the rapid conformational changes of channel proteins which underlie their transient sensitivity. But the genes that underlie magnocellular weakness would not be so common unless there were compensating advantages to dyslexia. In developmental dyslexics there may be heightened development of parvocellular systems that underlie their holistic, artistic, ,seeing the whole picture' and entrepreneurial talents. Copyright © 2001 John Wiley & Sons, Ltd. [source]

The use of tinted lenses to alleviate reading difficulties

JOURNAL OF RESEARCH IN READING, Issue 1 2001
Helen Whiteley
An increasing number of optometrists are offering assessments using the Intuitive Colorimeter (Wilkins, Nimmo-Smith and Jansons, 1992) to determine whether children who have reading difficulties might benefit from the use of tinted lenses. Suggestions have been made in the media that tinted lenses may provide a ,cure' for developmental dyslexia, and there have been many anecdotal accounts of improvements in reading following their use (e.g. Brace, 1993). However, such extreme claims are not typical of the scientific literature supporting the use of tinted lenses. This article provides an overview of the research into the use of tinted lenses for the amelioration of reading difficulties. The electronic databases searched for this review were BIDS, MEDLINE, PsychInfo, PsychLit and Science Direct. Key search terms used were coloured (colored) lenses, Irlen lenses, scotopic sensitivity and visual deficits in combination with the term ,reading difficulties'. [source]

Network influences on scholarly communication in developmental dyslexia: A longitudinal follow-up

JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 14 2003
Claudia A. Perry
Author cocitation analysis was used to explore ongoing changes in the intellectual structure of the hybrid problem area of developmental dyslexia for the period 1994,1998, and to address ambiguities in results raised by an earlier study of these researchers for the years 1976,1993. Results suggest that: (1) discrepancies between the structure of the sociometric (personal) and author cocitation networks reflect real differences, not temporal factors; (2) differences between cocitation patterns and reports in the literature, and corresponding delays in the visibility of emerging perspectives, are likely due to the "inertia" of aggregate cocitation data and/or by shifts by neuroscience-vision researchers to publication in more prominent journals; (3) a sharp rise in link density for the neuroscience-vision subgroup indicates increased cohesiveness and growing maturation for this emerging perspective; (4) shifts in subgroup membership, link density, patterns of coauthorship, and multiple factor loadings suggest possible convergence between other subgroups in the network and identify individuals who may play boundary-spanning roles within the network; and (5) changing patterns of cocitation throughout the network suggest the increasing influence of studies relating to neurobiological mechanisms underlying dyslexia. The possible contributions of such boundary spanners in addressing the substantial information and communication challenges posed by the increased interdisciplinary character of scholarship in general, also are discussed. [source]

Annotation: What electrical brain activity tells us about brain function that other techniques cannot tell us , a child psychiatric perspective

THE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 5 2007
Tobias Banaschewski
Background:, Monitoring brain processes in real time requires genuine subsecond resolution to follow the typical timing and frequency of neural events. Non-invasive recordings of electric (EEG/ERP) and magnetic (MEG) fields provide this time resolution. They directly measure neural activations associated with a wide variety of brain states and processes, even during sleep or in infants. Mapping and source estimation can localise these time-varying activation patterns inside the brain. Methods: Recent EEG/ERP research on brain functions in the domains of attention and executive functioning, perception, memory, language, emotion and motor processing in ADHD, autism, childhood-onset schizophrenia, Tourette syndrome, specific language disorder and developmental dyslexia, anxiety, obsessive-compulsive disorder, and depression is reviewed. Results:, Over the past two decades, electrophysiology has substantially contributed to the understanding of brain functions during normal development, and psychiatric conditions of children and adolescents. Its time resolution has been important to measure covert processes, and to distinguish cause and effect. Conclusions:, In the future, EEG/ERP parameters will increasingly characterise the interplay of neural states and information processing. They are particularly promising tools for multilevel investigations of etiological pathways and potential predictors of clinical treatment response. [source]