Lisa Henderson

Accessing and selecting word meaning in autism spectrum disorder.

BACKGROUND Comprehension difficulties are commonly reported in autism spectrum disorder (ASD) but the causes of these difficulties are poorly understood. This study investigates how children with ASD access and select meanings of ambiguous words to test four hypotheses regarding the nature of their comprehension difficulties: semantic deficit, weak central coherence, reduced top-down control and inhibition deficit. METHODS The cross-modal semantic priming paradigm was used. Children heard homonym primes in isolation or as final words in sentences biased towards the subordinate meaning and then named picture targets depicting dominant or subordinate associates of homonyms. RESULTS When homonyms were presented in isolation, children with ASD and controls showed priming for dominant and subordinate pictures at 250ms ISI. At 1,000ms ISI, the controls showed dominant (but not subordinate) priming whilst the ASD group did not show any priming. When homonyms were presented in subordinate sentence contexts, both groups only showed priming for context-appropriate (subordinate) meanings at 250ms ISI, suggesting that context has an early influence on meaning selection. At 1,000ms ISI the controls showed context-appropriate (but not inappropriate) priming whereas the ASD group showed both appropriate and inappropriate priming. CONCLUSIONS Children with ASD showed intact access to semantic information early in the time course of processing; however, they showed impairments in the selection of semantic representations later in processing. These findings suggest that a difficulty with initiating top-down strategies to modulate online semantic processing may compromise language comprehension in ASD. Implications for intervention are discussed.

Learning new vocabulary during childhood: Effects of semantic training on lexical consolidation and integration

Research suggests that word learning is an extended process, with offline consolidation crucial for the strengthening of new lexical representations and their integration with existing lexical knowledge (as measured by engagement in lexical competition). This supports a dual memory systems account, in which new information is initially sparsely encoded separately from existing knowledge and integrated with long-term memory over time. However, previous studies of this type exploited unnatural learning contexts, involving fictitious words in the absence of word meaning. In this study, 5- to 9-year-old children learned real science words (e.g., hippocampus) with or without semantic information. Children in both groups were slower to detect pauses in familiar competitor words (e.g., hippopotamus) relative to control words 24h after training but not immediately, confirming that offline consolidation is required before new words are integrated with the lexicon and engage in lexical competition. Children recalled more new words 24h after training than immediately (with similar improvements shown for the recall and recognition of new word meanings); however, children who were exposed to the meanings during training showed further improvements in recall after 1 week and outperformed children who were not exposed to meanings. These findings support the dual memory systems account of vocabulary acquisition and suggest that the association of a new phonological form with semantic information is critical for the development of stable lexical representations.

Accessing, Integrating, and Inhibiting Word Meaning in Poor Comprehenders

This study examined three processes crucial to reading comprehension (semantic access, integration, and inhibition) to identify causes of comprehension impairment. Poor comprehenders were compared to chronological-age controls and vocabulary-age (VA) controls. When listening to homonym primes (“bank”) versus unrelated primes, controls were faster to name pictures related to dominant (money) and subordinate (river) meanings at 250 ms interstimulus interval (ISI) but only showed dominant priming at 1,000 ms ISI, whereas poor comprehenders only showed dominant priming. When listening to subordinately biased sentences ending in homonyms (“John fished from the bank”) versus control sentences, all groups showed priming when naming subordinate (appropriate) pictures at 250 ms ISI: VA controls and poor comprehenders also showed priming when naming dominant (inappropriate) pictures. At 1,000 ms ISI, controls showed appropriate priming, whereas poor comprehenders only showed inappropriate priming. These findings suggest that poor comprehenders have difficulties accessing subordinate word meanings, which can manifest as a failure to inhibit irrelevant information.

The effect of coloured overlays and lenses on reading: a systematic review of the literature

There are many anecdotal claims and research reports that coloured lenses and overlays improve reading performance. Here we present the results of a systematic review of this literature and examine the quality of the evidence.

Treating reading difficulties with colour

UK dyslexia charities should present a more balanced view

Reading comprehension impairments in Autism Spectrum Disorders

Les enfants porteurs d’un Trouble du spectre autistique (TSA) presentent, pour la plupart, des difficultes de comprehension avec un niveau de lecture relativement correct. Ces etudes sont peu nombreuses et rares sont celles qui ont examine les competences de base necessaires a l’apprentissage de la lecture (e.g. le decodage phonologique) chez ces enfants. Dans cette etude, 49 enfants porteurs d’un TSA et 49 enfants tout-venant de meme âge sont evalues en lecture (mots, textes, comprehension), en decodage phonologique (lecture de pseudomots) et en vocabulaire. La lecture de mots et celle de textes (exactitude) sont de niveau similaire dans les deux groupes. En revanche, la comprehension en lecture et les connaissances du vocabulaire sont plus faibles chez les TSA. Environ 31% des TSA presentent un ecart entre la comprehension et la lecture de mots (compares a 10% chez les enfants tout-venant). Lorsque les deux groupes sont apparies en lecture de mots, les enfants porteurs d’un TSA presentent malgre tout un faible niveau de decodage phonologique. Alors que le decodage phonologique represente un predicteur significatif du niveau de comprehension en lecture chez les TSA, ce n’est pas le cas pour le groupe d’enfants tout-venant. L’ensemble de ces donnees suggere que le niveau de lecture ‘apparent’ des enfants porteurs d’un TSA masque des difficultes basiques dans le decodage phonologique. Ces difficultes associees a celles observees en comprehension orale limite le developpement de la comprehension en lecture chez les enfants porteurs d’un TSA.

Consolidation of vocabulary during sleep: The rich get richer?

HighlightsDifferent neural mechanisms may support word learning in children and adults.Children show larger proportions of slow‐wave sleep that supports consolidation.Consolidation in adults can benefit from richer existing knowledge.Meta‐analysis suggests extant vocabulary is associated with new word consolidation.Directions for uncovering prior knowledge influences on consolidation are proposed. ABSTRACT Sleep plays a role in strengthening new words and integrating them with existing vocabulary knowledge, consistent with neural models of learning in which sleep supports hippocampal transfer to neocortical memory. Such models are based on adult research, yet neural maturation may mean that the mechanisms supporting word learning vary across development. Here, we propose a model in which children may capitalise on larger amounts of slow‐wave sleep to support a greater demand on learning and neural reorganisation, whereas adults may benefit from a richer knowledge base to support consolidation. Such an argument is reinforced by the well‐reported “Matthew effect”, whereby rich vocabulary knowledge is associated with better acquisition of new vocabulary. We present a meta‐analysis that supports this association between childrens existing vocabulary knowledge and their integration of new words overnight. Whilst multiple mechanisms likely contribute to vocabulary consolidation and neural reorganisation across the lifespan, we propose that contributions of existing knowledge should be rigorously examined in developmental studies. Such research has potential to greatly enhance neural models of learning.

The poor comprehender profile: Understanding and supporting individuals who have difficulties extracting meaning from text

Publisher Summary This chapter illustrates the components of reading comprehension and how they can fractionate in reading disorders. The focus has been on providing a picture of current understanding of the poor comprehender profile, as well as introducing the issues and key questions pertinent to this field. It is recognized that the simple view is useful in distinguishing the dyslexic and poor comprehender profiles and capturing the basic skills fundamental to successful reading. The simple view, however, fails to explain the complexities in reading comprehension, and to do this, alternative models, such as the construction-integration model need to be considered.

Sleep problems in children with dyslexia: understanding the role of sleep in neurocognitive development through the lens of developmental disorders

It has long been recognised that sleep is more than a passive recovery state or mere inconvenience. Sleep plays an active role in maintaining a healthy body, brain and mind, and numerous studies suggest that sleep is integral to learning and memory. The importance of sleep for cognition is clear in studies of those experiencing sleep deprivation, who show consistent deficits across cognitive domains in relation to nonsleep-deprived controls, particularly in tasks that tax attention or executive functions (1). Poor sleep has been associated with poor grades, and academic performance suffers when sleep is sacrificed for extra study (2). Thus, it is perhaps unsurprising that children with developmental disorders of learning and cognition often suffer from sleep disturbances. These have been well documented in children with autism and attention-deficit/hyperactivity disorder (ADHD), where sleep problems can be particularly severe. However, a growing body of evidence suggests that sleep can be atypical across a spectrum of learning disorders. Understanding the ways in which sleep is affected in different developmental disorders can not only support the design and implementation of effective assessment and remediation programs, but can also inform theories of how sleep supports cognition in typical development. The study by Carotenuto et al. (3) in this issue makes a valuable contribution to this literature by looking at sleep disturbances in children with developmental dyslexia. Dyslexia is the most common specific learning disorder, affecting around one in 10 children in our classrooms. It is characterised by difficulties with reading and spelling and is primarily caused by a deficit in phonological processing. However, dyslexia often co-occurs with other developmental disorders, such as ADHD and specific language impairment, and there can be striking heterogeneity between children. This has led to the suggestion that dyslexia can result from complex combinations of multiple risk factors and impairments (4). Consequently, research attention is turning towards the wider constellation of subclinical difficulties often experienced by children with dyslexia, including potential sleep problems. Two preliminary studies have found differences in the sleep architecture of children with dyslexia in comparison with typical peers, using overnight sleep EEG recordings (polysomnography) (5,6). Notably, children with dyslexia showed unusually long periods of slow wave sleep and an increased number of sleep spindles. Slow wave sleep and spindles are related to language learning, most notably through promoting the consolidation of new vocabulary (7). Children with dyslexia have pronounced deficits in learning new oral vocabulary, providing a plausible theoretical link between sleep disturbances and language difficulties. If sleep problems do in fact exacerbate the learning difficulties associated with dyslexia, as well as impacting on daily cognitive function, this could have important implications for intervention and support programs. However, an important first step is to establish the nature and extent of sleep disturbances in dyslexia. Previous studies (5,6) have used small samples (N = <30) and examined a large array of sleep parameters on a small number of unusual nights (where children were wearing sleep recording equipment), as opposed to looking at global patterns over time. As such, how representative these findings are is questionable, and consequently these studies should be viewed as hypothesis-generating rather than hypothesis-testing. Carotenuto et al. (3) address some of these concerns, administering questionnaire measures of sleep habits to the parents of 147 children with dyslexia and 766 children without dyslexia, aged 8–12 years. A sample of this size allows for a robust analysis of sleep characteristics. Therefore, their findings that children with dyslexia showed higher rates of several markers of sleep disorders lend significant weight to suggestions that dyslexia might be associated with an increased risk for sleep problems. Importantly, the sleep questionnaire used by Carotenuto et al. (3) allows for a breakdown of sleep disturbances. It is interesting to note that they found the greatest difficulties in initiating and maintaining sleep, sleep breathing disorders and disorders of arousal. This closely mirrors the types of sleep problem documented in children with ADHD (8). While Carotenuto et al. (3) took care to exclude children with comorbid diagnoses, many children with dyslexia show subtle features of attention disorders that do not reach clinical thresholds. Future studies that can establish whether sleep disturbances are associated with subclinical attention problems or dyslexia per se will be particularly informative for understanding which cognitive skills most critically relate to sleep. This is also vital information for

Letter to the Editor concerning “A systematic review of controlled trials on visual stress using intuitive overlays or colorimeter”

We read with interest the review written by Evans and Allen, and published in the Journal of Optometry, in July, 2016. Systematic reviews are considered the ‘gold-standard’ form of evidence for assessing the effectiveness of therapeutic interventions. A systematic review comprises a focussed question, a comprehensive search strategy to identify all potentially relevant studies, predefined selection criteria to minimise bias from ‘cherry-picking’ studies and an assessment of the risk of bias (RoB) of individual studies in a way that can be evaluated and reproduced. Because studies at high RoB often overestimate treatment effects, the aim is to either exclude studies at high RoB, or at least prioritise those studies at the lowest RoB. For this reason the RoB table is the key feature of any systematic review because it needs to inform the subsequent discussion. The authors state that they used the Critical Appraisal Skills Programme (CASP) checklist for assessing bias. However, the domains of bias outlined in Tables 2 and 3 do not correspond to the domains of bias of the CASP checklist. For example, in section-C of the CASP checklist for Randomised Controlled Trials (RCTs), three questions are posed. These are: (i) Can the results be applied in your context? (ii) Were all clinically important outcomes considered? (iii) Are the benefits worth the harms and costs? Users of the CASP tool are asked to provide Yes, No or Can’t Tell responses to each of these questions. In dealing with these three questions for the studies they reviewed, however, Evans and Allen chose to have only one column titled ‘‘Interpretation’’ in their tables, which mostly did not provide direct responses to the above section-C CASP questions. Thus the authors have developed their own, hybrid RoB rating scale which has unknown validity. Furthermore, the authors appear to have ‘cherry-picked’ the domains of bias used for each system;