Severe developmental language disorder — Reading and spelling

Linguistic awareness i.e. the ability to identify phonemes, to segment words into syllables and to rhyme is highly correlated with reading/spelling proficiency. Children with severe developmental language disorders DLD (syntagmatic type) have been shown to specifically lack linguistic awareness. Two non-identical twin boys with severe, specific DLD were studied longitudinally with respect to their linguistic, neurolinguistic and pragmatic development. In spite of poor linguistic awareness, the boys acquired normal reading/spelling skills. This might be due to the early and massive language training they were given. However, the boys differ considerably in some aspects of reading and spelling performance. These findings are discussed with reference to their different neurolinguistic and pragmatic profiles.     

A developmental framework for developmental dyslexia

There are surprisingly few theories of the normal development of literacy that take into account the different cognitive processes underlying reading and spelling skills. The present framework suggests three phases, corresponding to the acquisition of logographic, alphabetic, and, finally, orthographic skills. At each phase, a new skill is introduced with either reading (input processes) or writing (output processes) acting as pacemaker. This stepwise progress is driven by a certain opposition between reading and writing processes. At any of the critical points where a new step has to be taken, breakdown can occur. This will result in different types of literacy disorder. However, the disorder will not only be characterized by the deficiency in a particular skill, but also by compensatory skills which will inevitably develop. Only by using models of this type will we be able to achieve a properly developmental perspective for developmental dyslexia.     

Clock drawing in developmental dyslexia

Although developmental dyslexia is often defined as a language-based reading impairment not attributable to low intelligence or educational or socioeconomic limitations, the behavioral manifestations of dyslexia are not restricted to the realm of language. Functional brain imaging studies have shed light on physiological differences associated with poor reading both inside and outside the classical language areas of the brain. Concurrently, clinically useful tests that elicit these nonlinguistic deficits are few. Specifically, the integrity of the dorsal visual pathway, which predominantly projects to the parietal cortex, remains underinvestigated, lacking easily administered tests. Here we present the Clock Drawing Test (CDT), used to test the visuoconstructive ability of children with and without dyslexia and garden-variety poor readers. Compared to typically reading children, many children with dyslexia and some garden-variety poor readers showed significant left neglect, as measured by the distribution of figures drawn on the left clock face. In the poor readers with dyslexia, we observed spatial construction deficits like those of patients with acquired right-hemisphere lesions. The results suggest that in some children with dyslexia, right-hemisphere dysfunction may compound the phonological processing deficits attributed to the left hemisphere. The CDT provides an easy opportunity to assess skills known to be associated with right-hemisphere parietal function. This test can be easily administered to children for both clinical and research purposes.     

Object-naming deficits in developmental dyslexia

This paper reports two experiments which focus on the object naming deficits of dyslexic readers. In Experiment 1, dyslexic and normal readers were asked to name objects depicted by pictures or following their spoken definition. Ten-year-old dyslexics named fewer objects correctly than other children of a similar age, performing only as well as a younger group of 8-year-old normal readers. This was true irrespective of the modality through which they were tested. In terms of naming latency, however, they were similar to comparison groups. In Experiment 2, nine-year-old dyslexic and normal readers performed as well as each other in a receptive vocabulary test in which pictures had to be matched to spoken words. However, once again, on a picture naming test, the dyslexics did less well than controls. We argue that dyslexic children are subject to verbal naming difficulties which cannot be accounted for by generally low levels of vocabulary knowledge. Their problems are attributable not to difficulties in semantic representation but to difficulties with the lexical-phonological representation of spoken words they know. We propose that, in turn, these difficulties are related to their memory and reading problems.     

Morphological awareness in developmental dyslexia

This study examines morphological awareness in developmental dyslexia. While the poor phonological awareness of dyslexic children has been related to their difficulty in handling the alphabetical principle, less is known about their morphological awareness, which also plays an important part in reading development. The aim of this study was to analyze in more detail the implications of the phonological impairments of dyslexics in dealing with larger units of language such as morphemes. First, the performance of dyslexic children in a series of morphological tasks was compared with the performance of children matched on reading-level and chronological age. In all the tasks, the dyslexic group performed below the chronological age control group, suggesting that morphological awareness cannot be developed entirely independently of reading experience and/or phonological skills. Comparisons with the reading-age control group indicated that, while the dyslexic children were poorer in the morphemic segmentation tasks, they performed normally for their reading level in the sentence completion tasks. Furthermore, they produced more derived words in the production task. This suggests that phonological impairments prevent the explicit segmentation of affixes while allowing the development of productive morphological knowledge. A second study compared dyslexic subgroups defined by their degree of phonological impairment. Our results suggest that dyslexics develop a certain type of morphological knowledge, which they use as a compensatory reading strategy.     

The neural basis of developmental dyslexia

Until recently, many thought developmental dyslexia was a behavioral disorder that primarily affected reading. In fact, it is a partly heritable condition, the clinical manifestations of which are extremely complex including deficits in reading, working memory, sensorimotor coordination, and early sensory processing. Even though extensive research has characterized these behavioral abnormalities carefully, the biological mechanisms of the clinical manifestations still are poorly understood. Recent research into both the nature of the structural and functional abnormalities in developmental dyslexia and the functional neuroanatomy of reading have rapidly advanced our understanding of the localization of the processes responsible for the signs and symptoms of dyslexia. This paper reviews recent evidence supporting a biological basis for developmental dyslexia. This article was made possible by grant NICHD HD36461 from The Charles A. Dana Foundation and The International Dyslexia Association.     

Self-concept and self-esteem in developmental dyslexia

Self-concept and self-esteem in two groups of dyslexic children (mainstream placement and SpLD unit placement, total N=63) were examined. Interviews and a questionnaire (the SDQ-1) were utilised, giving a mix of qualitative and quantitative data. Where appropriate, a control group of 57 children without learning difficulties was assimilated into the research design. The main findings were that the presence of dyslexia produced marked effects on the self-concept and self-esteem of children, although this was more apparent in the participants attending mainstream schools than those in SpLD units. The qualitative data revealed that children with dyslexia felt isolated and excluded in their schools, and that, typically, up to half were regularly teased or bullied. The findings were related to self-concept and self-esteem theory, and current educational practice. The limitations in terms of research design and analysis were also noted.     

快速命名与汉语发展性阅读障碍的研究综述

近年来快速命名与发展性阅读障碍的研究,主要讨论了快速命名对发展性阅读障碍产生预测性作用的主要原因:语音能力、正字法能力和任意性的形音联结.虽然鲜有研究涉及任意性的形音联结,但这个因素在形音关系不透明的汉语中,可能与阅读过程和快速命名都存在很大的相关性.今后应设立一个有效的统一的鉴别发展性阅读障碍儿童的标准,逐渐形成中文阅读发展的体系.     

Lexical stress assignment in Italian developmental dyslexia

Stress assignment to Italian polysyllabic words is unpredictable, because stress is neither marked nor predicted by rule. Stress assignment, especially to low frequency words, has been reported to be a function of stress dominance and stress neighbourhood. Two experiments investigate stress assignment in sixth-grade, skilled and dyslexic, readers. In Experiment 1, skilled readers were not affected by stress dominance. Dyslexic children, although affected by word frequency, made more stress regularisation errors on low frequency words. In Experiment 2, stress neighbourhood affected low frequency word reading irrespective of stress dominance for both skilled and dyslexic readers. Words with many stress friends were read more accurately than words with many stress enemies. It is concluded that, in assigning stress, typically developing and developmental dyslexic Italian readers are sensitive to the distributional properties of the language.     

Timing precision and rhythm in developmental dyslexia

Current research on the etiology ofdevelopmental dyslexia is generally informed byeither of two major hypotheses. One of theseassumes that the phonological processing ofconsonants and vowels at a segmental levelidentifies the core deficit in developmentaldyslexia and that it cannot be reduced todomain-general deficits of temporal informationprocessing. The other hypothesis holds thatphonological processing deficits aresymptomatic of an underlying, domain-generaldysfunction; and that at least some dyslexiasubtypes are causally related to domain generaldeficits of temporal information processing forauditory and visual stimuli. This report startsfrom the assumption that the terms temporal information processing andphonological processing as applied in currentdyslexia research, are frequently conflated. Further, it assumes that the conflated termsmust be decomposed into their concretebehavioral referents before the causalsignificance of either can be investigatedsystematically.The studies to be summarized in thisreport represents one step toward suchdecomposition. The findings indicated thatduring a motor sequencing task, dyslexicstudents anticipated the signal of anisochronic pacing metronome by intervals thatwere two or three times as long as those ofage matched normal readers or normal adults.These group differences were significant whenparticipants tapped with the preferred indexfinger alone or with both fingers in unison.Dyslexic students also took significantlylonger than normal readers did to recalibratetheir tapping responses when the metronome ratewas experimentally changed in the middle of atrial.In addition, dyslexic students, bycontrast to normal readers, had inordinatedifficulty reproducing simple motor rhythms byfinger tapping, and similar difficultyreproducing the appropriate speech rhythm oflinguistically neutral nonsense syllables.These difficulties were exaggerated whenparticipants had to synchronize theirperformance to an external pacing metronome.The implications of the findings for temporalinformation processing deficits on one hand,and impaired phonological processing on theother, are discussed.     

Cerebral dominance and subtypes of developmental dyslexia

Conclusions Evidence of different syndromes of developmental dyslexia raises the question of the interaction between dyslexic types and patterns of cerebral dominance. Some of the proposed classifications of dyslexia, and most notably the one proposed by Boder (1971), strongly suggest that dyslexic subtypes, that can be identified clinically by reading-spelling patterns, may possess different or opposite cerebral dominance patterns. Thus, research of cerebral dominance in dyslexia (i.e., Orton’s hypothesis) should involve careful selection and classification of subjects. When this is done it can be shown that electrophysiological measures can identify cerebral-dominance abnormalities in at least one subtype of developmental dyslexia. This paper was presented in part at the 29th Annual Conference of The Orton Society, November 1978, in Minneapolis, Minnesota.     

Continuities between speech and spelling in a case of developmental dyslexia

This paper explores the relationship between speech and spelling in a single-case study of developmental dyslexia. JM, a developmental dyslexic with a well-documented history of speech, reading and spelling difficulties, was examined when he was 13–14 years old. He still had subtle articulation difficulties causing some disfluency and his use of phonetic voicing was atypical. We argue that these difficulties were recapitulated in his spelling where he was more sensitive to the prosodic aspects of words than normal spellers, exhibiting a strong tendency to spell accurately words which are stressed on the first, rather than the second syllable. He also had more difficulty with phonetic voicing and spelling errors reflected this uncertainty. Thus, when word-specific (orthographic) spelling information is unavailable, JM, like all spellers, must make use of phonological spelling strategies. In his case, these are compromised because of underlying phonological speech problems. It is argued that, while young children make use of a phonological frame on which to organize orthographic information, dyslexics, like JM, who have inadequate phonological representations, are unable to do so. This has a detrimental effect on their acquisition of spelling.     

The question of linguistic anomaly in developmental dyslexia

Recent research findings pointing to an anatomical anomaly in the left hemisphere of dyslexics supports the conjecture that dyslexia involves a central anomaly in structural linguistic capacity. Two preliminary studies were carried out to test this conjecture. One study employed the techniques of grammatical research and the other was a reaction time study. Each study provided distinct evidence of a linguistic anomaly. The grammatical study suggested an anomaly when the assignment of referential relations among nominal elements is restricted on the basis of sentence structure, and the reaction time study provided evidence of an anomaly in the exploitation of grammatical markers. Based on a presentation at the 33rd Annual Conference of The Orton Dyslexia Society, San Diego, California, November 1983. I wish to thank Albert Galaburda for many stimulating discussions which led to the preliminary research reported here and the elaboration of that work in continuing studies, he cannot, however, be held accountable for either.     

Sentence comprehension in young adults with developmental dyslexia

This study investigated the effects of syntactic complexity on written sentence comprehension in compensated adults with dyslexia. Because working memory (WM) plays a key role in processing complex sentences, and individuals with dyslexia often demonstrate persistent deficits in WM, we hypothesized that individuals with dyslexia would perform more poorly on tasks designed to assess the comprehension of syntactic structures that are especially taxing on WM (e.g., passives, sentences with relative clauses). Compared to their nondyslexic peers, individuals with dyslexia were significantly less accurate and marginally slower on passive sentences. For sentences containing relative clauses, the dyslexic group was also less accurate but did not differ in response times. Covarying WM and word reading in both analyses eliminated group differences showing that syntactic deficits in adults with dyslexia are constrained by both WM and word-reading ability. These findings support previous research showing that syntactic processing deficits are characteristic of dyslexia, even among high-achieving students.