Erratum

The main aims of this study were a) to assess the cerebellar deficit hypothesis examining children's performance in cerebellar and cognitive tasks associated with the dyslexic syndrome and b) to investigate if there is a differentiation in articulation speed in children with dyslexia. A battery consisted of five cerebellar tests, five cognitive tests, and an articulation speed test was administered to three age- and sex-matched groups of dyslexics, children with attention deficit/hyperactivity disorder (ADHD) and normal readers aged 8–12 years. The dyslexics showed significant impairment in one cerebellar test compared with the control group and in two cognitive tests compared with both the control and the ADHD group. Additionally, the dyslexic children performed significantly worse than the control group during the articulation speed test; such a difference was not observed between the control and the ADHD group. The present study provides clues to support the cerebellar deficit hypothesis and the possible relationship between reading impairment and speed of articulation. Further research is considered essential to clarify the relationship between cerebellar function, dyslexia, and oral language speed.     

Performance of Dyslexic Children on Cerebellar and Cognitive Tests

In a previous study (A. J. Fawcett, R. I. Nicolson, & P. Dean, 1996), the authors had found strong behavioral evidence for cerebellar deficit in a panel of children with dyslexia. In the present study, the generality of those results was assessed. A battery of clinical tests for cerebellar dysfunction was administered, together with selected cognitive tests, to a further 59 dyslexic and 67 control children. The dyslexic children showed highly significant impairments on the cerebellar tests, with deficits on postural stability and muscle tone comparable in magnitude with their reading and spelling deficits. Furthermore, over 95&percent; of the dyslexic children showed clear evidence of deficit on muscle tone or stability. The findings provide further evidence of the generality of cerebellar impairment in dyslexia. The implications of the cerebellar tests for screening in dyslexia are discussed.     

Performance of Dyslexic Children on Cerebellar and Cognitive Tests

In a previous study (A. J. Fawcett, R. I. Nicolson, & P. Dean, 1996), the authors had found strong behavioral evidence for cerebellar deficit in a panel of children with dyslexia. In the present study, the generality of those results was assessed. A battery of clinical tests for cerebellar dysfunction was administered, together with selected cognitive tests, to a further 59 dyslexic and 67 control children. The dyslexic children showed highly significant impairments on the cerebellar tests, with deficits on postural stability and muscle tone comparable in magnitude with their reading and spelling deficits. Furthermore, over 95% of the dyslexic children showed clear evidence of deficit on muscle tone or stability. The findings provide further evidence of the generality of cerebellar impairment in dyslexia. The implications of the cerebellar tests for screening in dyslexia are discussed.     

Are there different patterns of cerebral asymmetry between dyslexic subtypes?

The purpose of this research has been to analyze the cerebral asymmetry in dyslexic children and, specifically for demonstrating whether there are different patterns of cerebral asymmetry among subtypes of dyslexia. We used a sample of 89 dyslexic children divided into subtypes obtained from the Jimenez and Ramirez (2002) study. The dual-task method was used to assess hemispheric specialization. The data were compared with that obtained from a control group of normal readers of same age (CA; N= 37) and with a younger reading level control group (RL; N= 40). We found that in the dyslexic group, similarly to the younger reading level group, a high percentage of children showed convergence in the left hemisphere of both linguistic and spatial functions. This pattern was also found in the RL control group. On the other hand, we did not find different patterns of cerebral asymmetry between dyslexic subtypes.     

基于PASS模型的汉语阅读障碍认知加工特点的实验研究

研究以智力的PASS认知模型为基础,考察了3-5年级阅读障碍组和正常对照组的PASS认知加工特点,探究汉语阅读障碍儿童的PASS认知缺陷模式,为后期的干预提供理论上的支持和帮助。结果发现,PASS四个认知加工均存在明显的年级差异,低年级儿童的PASS认知加工能力明显不如中高年级儿童。汉语阅读障碍儿童在DN: CAS 12项分任务上的成绩均低于正常对照组儿童。同时,大多数汉语阅读障碍儿童存在不止一种的PASS认知加工缺陷,即汉语发展性阅读障碍内部是一个异质群体;阅读障碍儿童在继时性加工上存在的问题最为严重,存在缺陷的人数也最多。     

Automaticity: a new framework for dyslexia research?

The performance of a group of 23 13-year-old dyslexic children was compared with that of same-age controls on a battery of tests of motor balance. A dual-task paradigm was used--subjects performed each test twice, once as a single task, and once as a dual task concurrently with a secondary task. Two alternative secondary tasks were used, the classic counting-backwards task and an auditory choice reaction task. Both secondary tasks were calibrated for each subject to ensure that their performance on the secondary task alone fell between pre-specified performance criteria. In all single-task conditions there was no difference between the performance of the two groups. By contrast, in 19 out of the 20 tests performed under dual-task conditions, the dyslexic group were significantly impaired, whereas the controls showed no impairment, thus resulting in significantly better performance by the control group than the dyslexic group. The sole exception was that the dyslexic children were not impaired on the easiest balance condition with the choice reaction task. Under the dual-task conditions the dyslexic children also performed worse than the controls on the secondary task. It is very hard to accommodate the findings within the traditional framework of a deficit specific to lexical skills. One plausible explanation of the results is that, unlike the controls, the dyslexic children need to invest significant conscious resources for monitoring balance, and thus their performance is adversely affected by any secondary task which serves to distract attention from the primary task. This need for "conscious compensation" suggests that for dyslexic children the skill of motor balance is poorly automatized. It is possible, therefore, that many of the reading deficits of dyslexic children are merely symptoms of a more general learning deficit--the failure to fully automatize skills.     

The cognitive profile and multiple-deficit hypothesis in Chinese developmental dyslexia

The present study was conducted to examine the cognitive profile and multiple-deficit hypothesis in Chinese developmental dyslexia. Thirty Chinese dyslexic children in Hong Kong were compared with 30 average readers of the same chronological age (CA controls) and 30 average readers of the same reading level (RL controls) in a number of rapid naming, visual, phonological, and orthographic tasks. Chinese dyslexic children performed significantly worse than the CA controls but similarly to the RL controls on most of the cognitive tasks. The rapid naming deficit was found to be the most dominant type of cognitive deficit in Chinese dyslexic children. Over half of the dyslexic children exhibited deficits in 3 or more cognitive areas, and there was a significant association between the number of cognitive deficits and the degree of reading and spelling impairment. The present findings support the multiple-deficit hypothesis in Chinese developmental dyslexia.     

Automatisation deficits in balance for dyslexic children.

Traditional theories of dyslexia have focused on components of the reading process. The Dyslexic Automatisation Deficit hypothesis takes a broader view, attributing deficits to an inability to become completely fluent in cognitive and motor skills. A series of experiments compared the balance of 15-yr.-old and 11-yr.-old groups of dyslexic children and normal children matched for age and IQ under single-task and dual-task conditions. There were no group differences in the single-task conditions. However, introduction of a concurrent secondary task led to a dissociation in that, whereas the balance of normal children was unaffected, the dyslexic children's balance was significantly impaired. It was concluded that the normal children balanced automatically whereas the dyslexic children did not. These results directly support the proposed framework.     

不同阅读水平儿童中央执行系统比较研究

本研究通过两部分实验探讨汉语发展性阅读障碍儿童与正常儿童中央执行系统的容量差异和这种差异的性质。通过比较匹配生理年龄的不同阅读水平儿童在自定步速和固定步速的复杂阅读广度测验中的成绩,发现发展性阅读障碍儿童在两种阅读广度测验中都表现出中央执行系统容量的缺陷,这种缺陷既不能用加工效率理论,也不能用资源分配理论来解释,而符合一般容量假设。因此,本研究支持发展性阅读障碍儿童存在实时加工和存储信息的一般容量缺陷。     

A behavioral experimental analysis of dyslexia

A behavioral analysis of specific dyslexia is contrasted with traditional genetic, neurological and developmental theories which hold that the dyslexic's inability to read is based on impaired intellectual functioning and decreased perceptual and attentional skills caused by a biological limitation. Two groups of six children, aged 9 and 10 years and comprised of dyslexic and non-dyslexic subjects, were given either traditional remedial reading treatment or behavior therapy consisting of the Staats Motivated Action Reading Technique. Both dyslexic and non-dyslexic subjects receiving the behavioral intervention significantly improved in reading achievement to approximately the same degree, and the dyslexic subjects improved in several perceptual and attentional measures as well. These results are taken to support the position that the specific dyslexia syndrome is subject to the laws of learning and can be viewed as a function of a deficient learning history.     

Variation among developmental dyslexics: evidence from a printed-word-learning task

A word-learning task was used to investigate variation among developmental dyslexics classified as phonological and surface dyslexics. Dyslexic children and chronological age (CA)- and reading level (RL)-matched normal readers were taught to pronounce novel nonsense words such as veep. Words were assigned either a regular (e.g., "veep") or an irregular (e.g., "vip") pronunciation. Phonological dyslexics learned both regular and exception words more slowly than the normal readers and, unlike the other groups, did not show a regular-word advantage. Surface dyslexics also learned regular and exception words more slowly than the CA group, consistent with a specific problem in mastering arbitrary item-specific pronunciations, but their performance resembled that of the RL group. The results parallel earlier findings from Manis, Seidenberg, Doi, McBride-Chang, & Petersen [Cognition 58 (1996) 157-195] indicating that surface dyslexics and phonological dyslexics have a different profile of reading deficits, with surface dyslexics resembling younger normal readers and phonological dyslexics showing a specific phonological deficit. Models of reading and reading disability need to account for the heterogeneity in reading processes among dyslexic children.     

Rapid silent response to repeated target symbols by dyslexic and nondyslexic children

A previous study demonstrated that naming of repeated colors, objects, letters, and numbers (RAN test) was performed more slowly by dyslexic than by nondyslexic learning disabled children, whereas both groups were slower than controls. A test eliminating the vocal response and requiring “cancellation” of selected verbal targets distinguished the two learning disabled groups from each other only when the targets were triads of numbers or letters, the dyslexic group performing more slowly. Compared even with triad target selection, however, dyslexic children were relatively more impaired on rapid naming (RAN), suggesting a specific relationship of reading to speech or the greater mobilization of language functions which speech requires.     

Dyslexic and normal readers' eye movements

Dyslexic and normal readers' eye movements were compared while tracking a moving fixation point and in reading. Contrary to previous reports, the dyslexic and normal readers did not differ in their number of saccades, percentage of regressions, or stability of fixations in the tracking task. Thus, defective oculomotor control was not associated with or a causal factor in dyslexia, and the dyslexics' abnormal eye movements in reading must be related to differences in higher cognitive processes. However, individual differences in oculmotor efficiency, independent of reading ability, were found within both the dyslexic and normal groups, and these differences were correlated in reading and tracking tasks.     

Spoken language correlates of reading impairments acquired in childhood

This study reports the reading difficulties of five children following unilateral left hemisphere stroke sustained either before or during the early stages of literacy acquisition. Although each of the children experienced a period of disturbed language processing in the initial stages postonset, at the time of testing none of the children were considered to be clinically aphasic. Yet, on a standardized test of oral reading each of the children achieved a reading age that lagged behind chronological age and marked reading impairments were disclosed in four of the five children. A set of standardized and nonstandardized tests, aimed at measuring aspects of cognitive and spoken language processing that are considered to be important for normal reading acquisition, was administered. Where nonstandardized tests were used, performance of each of the stroke children was compared to that of groups of normally developing control children, closely matched for chronological age. A range of residual deficits in cognitive and spoken language processing was disclosed among the five brain-damaged children that appeared to be associated with their reading impairments. Two children had expectedly poor reading due to a selective impairment in verbal IQ; a specific phonological reading disorder was revealed in two children, each of which had a residual impairment to phonological awareness; and delayed reading acquisition was observed in one child with a general language deficit. It is suggested that when a child suffers damage to the left hemisphere in the early stages of reading acquisition, difficulties with learning to read are likely to ensue and may arise as a consequence of an underlying cognitive or linguistic deficit.     

Abnormalities of visual evoked potentials by checkerboards in children with specific reading disability

Visual evoked potentials by checkerboards of varying check sizes were recorded in the two hemispheres of 16 specific reading disabled and 8 normal children. In most of the disabled subjects a gross hemisphere asymmetry was assessed, while in the control group the usual evoked potential symmetry was observed. In some disabled subjects the evoked potentials had a larger amplitude in the right hemisphere, while in others the amplitude was larger in the left hemisphere. In a small subgroup the evoked potentials were symmetrical, but they had a smaller amplitude than in the control subjects. The results, giving evidence of a dysfunction in basic visual processing, are discussed in the context of current literature on clinical subgroups and the interhemispheric relationship in the dyslexic syndrome.     

空格减少汉语发展性阅读障碍儿童的视觉拥挤效应：来自眼动的证据

使用眼动仪记录汉语发展性阅读障碍儿童、正常年龄匹配和能力匹配儿童阅读插入空格文本时的眼动,考察在字、词以及非词间插入空格呈现文本对汉语发展性阅读障碍儿童阅读加工过程的影响。结果发现,阅读障碍儿童在字间空格条件下平均注视时间减少的程度大于正常儿童,注视次数在字间和词间空格条件下未见显著增加,能力匹配儿童的注视次数在这两种空格条件下却显著增加。结果说明,在字间和词间插入空格能够减少儿童的平均阅读时间,且字间空格文本呈现显著地提高了其阅读效率,说明空格对汉语阅读障碍儿童具有促进作用,这种促进主要是由于空格减少了其视觉拥挤效应所致。     

Neuropsychological evaluation of neurologically asymptomatic HIV-infected children

Forty-two children born to HIV positive mothers (29 infected at different stages of the disease, according to the Disease Control Classification Centers, and 13 noninfected) underwent evaluation using a battery of neuropsychological tests. Executive function impairments were present in all infected children, whereas memory and visuo-prassic deficits were evident only in those with full-blown AIDS. Language abilities and overall intelligence were spared. Performance of seroreverters was in the normal range. These findings suggest that even in neurologically asymptomatic children, neuropsychological evaluation can identify early impairment of specific cognitive functions. The findings are discussed in the light of the prognostic power of neuropsychological assessment for early signs of HIV neurological involvement.     

Visual rapid naming and phonological abilities: different subtypes in dyslexic children

One implication of the double-deficit hypothesis for dyslexia is that there should be subtypes of dyslexic readers that exhibit rapid naming deficits with or without concomitant phonological processing problems. In the current study, we investigated the validity of this hypothesis for Portuguese orthography, which is more consistent than English orthography, by exploring different cognitive profiles in a sample of dyslexic children. In particular, we were interested in identifying readers characterized by a pure rapid automatized naming deficit. We also examined whether rapid naming and phonological awareness independently account for individual differences in reading performance. We characterized the performance of dyslexic readers and a control group of normal readers matched for age on reading, visual rapid naming and phonological processing tasks. Our results suggest that there is a subgroup of dyslexic readers with intact phonological processing capacity (in terms of both accuracy and speed measures) but poor rapid naming skills. We also provide evidence for an independent association between rapid naming and reading competence in the dyslexic sample, when the effect of phonological skills was controlled. Altogether, the results are more consistent with the view that rapid naming problems in dyslexia represent a second core deficit rather than an exclusive phonological explanation for the rapid naming deficits. Furthermore, additional non-phonological processes, which subserve rapid naming performance, contribute independently to reading development.     

Hemispheric specialization for speech perception in language deficient kindergarten children

Twenty right-handed kindergarten children with superior language skills and twenty with deficient language skills (as defined by performance on an elicited sentence repetition task) were tested (1) for hemispheric specialization for speech perception with a dichotic CV syllable task and (2) for relative manual proficiency by means of a battery of hand tasks. Reading readiness and aspects of other cognitive abilities were also assessed. The superior children evidenced a mean right-ear advantage of 14.5%, which is consistent with normal values reported by other investigators using the same stimuli. The language deficient group evidenced essentially no mean ear advantage (0.5) with half of these subjects exhibiting left-ear superiority. The findings suggest relationships among cerébral dominance, language proficiency (including reading readiness), and general cognitive functioning.