Visual attentional blink in dyslexic children: Parameterizing the deficit

Retained Primitive Reflexes and Potential for Intervention in Autistic Spectrum Disorders

We provide evidence to support the contention that many aspects of Autistic Spectrum Disorder (ASD) are related to interregional brain functional disconnectivity associated with maturational delays in the development of brain networks. We think a delay in brain maturation in some networks may result in an increase in cortical maturation and development in other networks, leading to a developmental asynchrony and an unevenness of functional skills and symptoms. The paper supports the close relationship between retained primitive reflexes and cognitive and motor function in general and in ASD in particular provided to indicate that the inhibition of RPRs can effect positive change in ASD.

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.

Factors Explaining Deficits in Reading Acquisition: The Case of Williams Syndrome

Purpose Multiple factors impact reading acquisition in individuals with reading disability, including genetic disorders such as Williams syndrome (WS). Despite a relative strength in oral language, individuals with WS usually have an intellectual disability and tend to display deficits in areas associated with reading. There is substantial variability in their reading skills. While some authors have postulated that phonological deficits are at the source of their reading deficits, others have suggested that they can be attributed to visuospatial deficits. This study was the first to undertake an in-depth exploration of reading skills among French-speaking children and adults with WS. We tested the assumption that some factors influence performance on single-word identification among individuals with WS, with a focus on the roles of phonological awareness and visuospatial skills. Method Participants were 29 French-speaking adults with WS and 192 controls matched for nonverbal mental age and reading level. We administered tests assessing reading (decoding and word recognition), vocabulary (expressive and receptive), and phonological and visuospatial skills. We also controlled for chronological age and nonverbal reasoning. Results Phonemic awareness was the most predictive factor of single-word identification in the WS group. Visuospatial skills also contributed, but not more or beyond other factors. More broadly, reasoning skills may also have accounted for the variability in single-word identification in WS, but this was not the case for either chronological age or vocabulary. Conclusions There is considerable heterogeneity among adults with WS, who may be either readers or prereaders. Similar profiles identified among individuals with other specific learning disabilities suggest that high reading variability is not specific to the neuropsychological profile of WS. We discuss a multidimensional approach to the factors involved in reading deficits in WS.

What bilateral damage of the superior parietal lobes tells us about visual attention disorders in developmental dyslexia

Neuroimaging studies have identified the superior parietal lobules bilaterally as the neural substrates of reduced visual attention (VA) span in developmental dyslexia. It remains however unclear whether the VA span deficit and the deficits in temporal and spatial attention shifting also reported in dyslexic children reflect a unitary spatio-temporal deficit of attention - probably linked to general posterior parietal dysfunction- or the dysfunction of distinct attentional systems that relate to different neural substrates. We explored this issue by testing an adult patient, IG, with a specific damage of the bilateral superior parietal lobules after stroke, on tasks assessing the VA span as well as temporal and spatial attention shifting. IG demonstrated a very severe VA span deficit, but preserved temporal attention shifting. Exogenous spatial orientation shifting was spared but her performance was impaired in endogenous attention. The overall findings show that distinct sub-systems of visual attention can be dissociated within the parietal lobe, suggesting that different attentional systems associated with specific neural networks can be selectively impaired in developmental dyslexia.

Multiple Causal Links Between Magnocellular-Dorsal Pathway Deficit and Developmental Dyslexia

Although impaired auditory-phonological processing is the most popular explanation of developmental dyslexia (DD), the literature shows that the combination of several causes rather than a single factor contributes to DD. Functioning of the visual magnocellular-dorsal (MD) pathway, which plays a key role in motion perception, is a much debated, but heavily suspected factor contributing to DD. Here, we employ a comprehensive approach that incorporates all the accepted methods required to test the relationship between the MD pathway dysfunction and DD. The results of 4 experiments show that (1) Motion perception is impaired in children with dyslexia in comparison both with age-match and with reading-level controls; (2) pre-reading visual motion perception-independently from auditory-phonological skill-predicts future reading development, and (3) targeted MD trainings-not involving any auditory-phonological stimulation-leads to improved reading skill in children and adults with DD. Our findings demonstrate, for the first time, a causal relationship between MD deficits and DD, virtually closing a 30-year long debate. Since MD dysfunction can be diagnosed much earlier than reading and language disorders, our findings pave the way for low resource-intensive, early prevention programs that could drastically reduce the incidence of DD.

The attentional blink in typically developing and reading-disabled children

This study's research question was whether selective visual attention, and specifically the attentional blink (AB) as operationalized by a dual target rapid serial visual presentation (RSVP) task, can explain individual differences in word reading (WR) and reading-related phonological performances in typically developing children and reading-disabled subgroups. A total of 407 Dutch school children (Grades 3-6) were classified either as typically developing (n = 302) or as belonging to one of three reading-disabled subgroups: reading disabilities only (RD-only, n = 69), both RD and attention problems (RD+ADHD, n = 16), or both RD and a specific language impairment (RD+SLI, n = 20). The RSVP task employed alphanumeric stimuli that were presented in two blocks. Standardized Dutch tests were used to measure WR, phonemic awareness (PA), and alphanumeric rapid naming (RAN). Results indicate that, controlling for PA and RAN performance, general RSVP task performance contributes significant unique variance to the prediction of WR. Specifically, consistent group main effects for the parameter of AB(minimum) were found, whereas there were no AB-specific effects (i.e., AB(width) and AB(amplitude)) except for the RD+SLI group. Finally, there was a group by measurement interaction, indicating that the RD-only and comorbid groups are differentially sensitive for prolonged testing sessions. These results suggest that more general factors involved in RSVP processing may explain the group differences found.

Temporal variability predicts the magnitude of between-group attentional blink differences in developmental dyslexia: a meta-analysis

Background. Here we report on a meta-analysis of the between-group main effect (Group Difference) noted in the attentional blink (AB) research focused on specific reading impairment, commonly referred to as developmental dyslexia. The AB effect relates to a limitation in the allocation of attention over time and is examined in a dual-target rapid serial visual presentation (RSVP) paradigm. When the second target appears in close temporal proximity to the first target, the second target is reported less accurately. Method. A Web of Science search with terms "attentional blink" & dyslexia returned 13 AB experiments (11 papers) conducted with developmental dyslexia. After exclusions, 12 experiments were included in the meta-analysis. The main pattern of performance from those experiments was lower overall accuracy in groups of individuals with dyslexia relative to typically reading peers; that is, a between-group main effect. This meta-analysis examined the size of the Group Difference in relation to temporal and task-set related features, which differed between and within experiments. Results. Random effects modelling indicated a significant Group Difference of -0.74 standard deviation units, 95% CI [-.96, -.52], p < .001 (excluding one anomalous result): implicating significantly poorer overall dual-target performance in dyslexic readers. Meta-regression analyses indicated two variables related to the Group Difference; pre-RSVP time and temporal variability of the second target relative to the first target within the RSVP. Discussion. It is suggested that the endogenous engagement of the temporal features of task-set is slower or disrupted in developmental dyslexia.

Is the impairment in temporal allocation of visual attention in children with ADHD related to a developmental delay or a structural cognitive deficit?

We investigated the temporal allocation of visual attention in 11-year-old children with attention-deficit/hyperactivity disorder (ADHD) by comparing their attentional blink (AB) parameters (duration, amplitude and minimum performance) with those observed in three groups of healthy control participants (8-year-olds, 11-year-olds and adults). The AB is a marker of impaired ability to detect a second target following the identification of a first target when both appear randomly within a rapid sequence of distractor items. Our results showed developmental effects; with age, the AB duration decreased and the AB minimum moved to shorter lag times. Importantly, 11-year old children with ADHD presented much the same similar AB patterns (in terms of duration and minimum position) as the healthy 8-year-old controls. Our results support the hypothesis whereby impaired allocation of temporal selective attention in children with ADHD is due to a developmental delay and not a specific cognitive deficit.

Temporal sampling in vision and the implications for dyslexia

It has recently been suggested that dyslexia may manifest as a deficit in the neural synchrony underlying language-based codes (Goswami, 2011), such that the phonological deficits apparent in dyslexia occur as a consequence of poor synchronisation of oscillatory brain signals to the sounds of language. There is compelling evidence to support this suggestion, and it provides an intriguing new development in understanding the aetiology of dyslexia. It is undeniable that dyslexia is associated with poor phonological coding, however, reading is also a visual task, and dyslexia has also been associated with poor visual coding, particularly visuo-spatial sensitivity. It has been hypothesized for some time that specific frequency oscillations underlie visual perception. Although little research has been done looking specifically at dyslexia and cortical frequency oscillations, it is possible to draw on converging evidence from visual tasks to speculate that similar deficits could occur in temporal frequency oscillations in the visual domain in dyslexia. Thus, here the plausibility of a visual correlate of the Temporal Sampling Framework is considered, leading to specific hypotheses and predictions for future research. A common underlying neural mechanism in dyslexia, may subsume qualitatively different manifestations of reading difficulty, which is consistent with the heterogeneity of the disorder, and may open the door for a new generation of exciting research.

Investigating the role of visual and auditory search in reading and developmental dyslexia

It has been suggested that auditory and visual sequential processing deficits contribute to phonological disorders in developmental dyslexia. As an alternative explanation to a phonological deficit as the proximal cause for reading disorders, the visual attention span hypothesis (VA Span) suggests that difficulties in processing visual elements simultaneously lead to dyslexia, regardless of the presence of a phonological disorder. In this study, we assessed whether deficits in processing simultaneously displayed visual or auditory elements is linked to dyslexia associated with a VA Span impairment. Sixteen children with developmental dyslexia and 16 age-matched skilled readers were assessed on visual and auditory search tasks. Participants were asked to detect a target presented simultaneously with 3, 9, or 15 distracters. In the visual modality, target detection was slower in the dyslexic children than in the control group on a “serial” search condition only: the intercepts (but not the slopes) of the search functions were higher in the dyslexic group than in the control group. In the auditory modality, although no group difference was observed, search performance was influenced by the number of distracters in the control group only. Within the dyslexic group, not only poor visual search (high reaction times and intercepts) but also low auditory search performance (d′) strongly correlated with poor irregular word reading accuracy. Moreover, both visual and auditory search performance was associated with the VA Span abilities of dyslexic participants but not with their phonological skills. The present data suggests that some visual mechanisms engaged in “serial” search contribute to reading and orthographic knowledge via VA Span skills regardless of phonological skills. The present results further open the question of the role of auditory simultaneous processing in reading as well as its link with VA Span skills.

Developmental dyslexia: exploring how much phonological and visual attention span disorders are linked to simultaneous auditory processing deficits

The simultaneous auditory processing skills of 17 dyslexic children and 17 skilled readers were measured using a dichotic listening task. Results showed that the dyslexic children exhibited difficulties reporting syllabic material when presented simultaneously. As a measure of simultaneous visual processing, visual attention span skills were assessed in the dyslexic children. We presented the dyslexic children with a phonological short-term memory task and a phonemic awareness task to quantify their phonological skills. Visual attention spans correlated positively with individual scores obtained on the dichotic listening task while phonological skills did not correlate with either dichotic scores or visual attention span measures. Moreover, all the dyslexic children with a dichotic listening deficit showed a simultaneous visual processing deficit, and a substantial number of dyslexic children exhibited phonological processing deficits whether or not they exhibited low dichotic listening scores. These findings suggest that processing simultaneous auditory stimuli may be impaired in dyslexic children regardless of phonological processing difficulties and be linked to similar problems in the visual modality.