The double deficit hypothesis in the transparent Finnish orthography: a longitudinal study from kindergarten to Grade 2

We examined the double deficit hypothesis (Wolf & Bowers, 1999) and literacy development in a longitudinal dataset of 1,006 Finnish children who were nonreaders at school entry. A single phonological awareness (PA) deficit was a predictor of pseudoword spelling accuracy and reading fluency, and a single rapid automatized naming (RAN) deficit was a predictor of reading fluency. The group with both PA and RAN deficits experienced the most extensive reading and spelling difficulties. However, all groups included both poor and average Grade 2 readers and spellers. Poor letter knowledge and vocabulary, task avoidance, attention difficulties, hyperactivity, and lack of teaching at home were additional risk factors for reading and spelling problems, but their impact varied depending on the presence of PA and RAN deficits.     

Comparing the phonological and double deficit hypotheses for developmental dyslexia

This study tested the predictions of thephonological and double deficit hypotheses byexperimentally examining speech perception,phoneme awareness, lexical retrieval (serialand discrete), articulatory speed, and verbalSTM in school age child (N = 35) and adolescent(N = 36) dyslexics, and both chronological age(CA) and reading age (RA) controls. Theresults confirmed the findings of previousstudies of a deficit in phoneme awareness indevelopmental dyslexia. At both age levels,dyslexics performed significantly more poorlythan both their CA and RA controls. Althoughdeficits in the other processes investigated,particularly in rapid serial naming, were alsoapparent, they were not as clear-cut as thedeficit in phoneme awareness. In general,definite evidence of a deficit in rapid serialnaming was limited to the more severelyimpaired dyslexics. Furthermore, although rapidserial naming contributed independent variationto various literacy skills, its contributionwas modest relative to the contribution ofphoneme awareness, regardless of whether theliteracy skill relied more or less heavily onphonological or orthographic coding skills. Further analyses suggested that variation inrapid serial skill is particularly importantfor fluent reading of text, whereas phonemeawareness is particularly important for thedevelopment of the ability to read byphonologically recoding letters or groups ofletters in words into their phonological codes.This explains the relatively strongcontribution of phoneme awareness to readingand spelling ability in general. In sum, thephonological hypothesis offers a moreparsimonious account of the present resultsthan the double deficit hypothesis.     

Why the timing deficit hypothesis does not explain reading disability in adults

It has been proposed that the phonological coredeficit that is linked to reading failure hasas its underlying cause a deficit in temporalprocessing. In a multivariate investigationdesigned to examine the temporal processingdeficit hypothesis, thirty reading-disabled(RD) adults, thirty-two normally achievingadults and thirty-one normally achievingchildren (reading-level controls) wereadministered a comprehensive battery thatincluded a wide range of timing tasks, inaddition to reading and phonological measures. Although adults with RD displayed overallperformance that was below that of normallyachieving adults on most of the timing tasks,their performance was not differentiallyinfluenced by rate of stimulus presentation. Although the RD adults displayed the typicalpattern of impaired phonological awareness andpseudoword reading relative to reading-levelmatched children, the reading-disabled adultsoutperformed the children on the timing tasks. Finally, with the exception of continuousnaming, the timing tasks shared little variancewith phonological sensitivity and contributedlittle unique variance to word reading. Although these findings undermine the timingdeficit hypothesis, they do provide evidencefor the involvement of naming deficits inreading disability.     

Structural invariance in the associations of naming speed,phonological awareness,and verbal reasoning in good and poor readers: A test of the double deficit hypothesis

The associations of multiple measures of speeded naming, phonological awareness, and verbal intelligence with word reading were examined in 51 poor readers and 74 good readers in third and fourth grade. Structural equation modeling was used to determine the extent to which these two groups exhibited structurally invariant patterns of associations among the constructs. Results revealed that for poor readers, both speeded naming and phonological awarencess were significantly associated with word reading, but verbal intelligence had no association with it. In contrast, for good readers, phonological awareness and verbal intelligence were significantly associated with word reading, but naming speed was not. Findings are discussed in light of the double deficit hypothesis.     

Phonological skills and comprehension failure: A test of the phonological processing deficit hypothesis

Shankweiler and colleagues argue that text comprehensionproblems in young children arise from phonological processingdifficulties. Their work has focused on children with poor wordreading ability. We investigated this hypothesis for children whoexperience comprehension difficulties in the presence of age-appropriate word reading skills. We found that good and poorcomprehenders performed comparably on various measures ofphonological processing and differed on a task that made greaterdemands on working memory, Bradley and Bryant's odd-word-outtask. In a final study, hierarchical regression analyses supportedthis distinction: the odd-word-out task was a strong predictor ofreading comprehension performance even after IQ, vocabulary and single word reading had been controlled for, but a lessmemory-dependent phonological task was not. These studiessupport previous work which indicates that poor comprehenders'problems arise from higher-level processing difficulties.     

Dyslexia and the life course

The life stories of adults diagnosed with dyslexia as children were examined, with emphasis on the related emotional experiences. The life story method of narrative analysis was used to compare and analyze the accounts of 12 participants who were interviewed extensively. The findings indicated that self-esteem problems may emerge by early childhood as individuals contend with aspects of their learning disabilities that interfere with typical development. By school age, all participants noted self-esteem problems when they experienced struggles or failures in school, which could feel traumatic. Testing and diagnosis improved self-esteem when conducted in a relevant manner that led to adaptation. The central plots of the participants' lives were characterized by the interplay between the functional challenges of their learning disabilities and the related self-esteem issues. Compensation involved the individual's areas of competence and the resources within the environment. Niches in late adolescence and young adulthood held potential to dramatically improve compensation. Participants generally exhibited four ways of life in adulthood and an added sense of emotional insecurity. Each attempted to integrate lifelong emotional experiences related to living with diagnosed dyslexia.     

Dyslexia and musical notation

The authors examine the difficulties experienced by dyslexic musicians in the formalized study of music, in particular, musical notation. They describe case studies from the literature and from personal interviews they conducted with musicians about their educational histories, musical weaknesses and strengths, and successful compensatory strategies. The authors make instructional suggestions for educators and musicians with dyslexia on how to use multisensory approaches to teach musical notation.     

Dyslexia and spatial thinking

Impairment in spatial thinking has figured prominently as an assumed cause of developmental reading disability. The empirical findings relevant to the idea, with special reference to right-left orientation, visuomotor and visuoconstructive performances, and finger recognition are examined. It is concluded that, although some dyslexic children do show spatial disabilities, there is little evidence to support the existence of a visuospatial type of developmental dyslexia. Presented at the 33rd Annual Conference of The Orton Dyslexia Society, San Diego, California, November 1983.     

Dyslexia and hormone deficiences

From a group of 75 children, originally selected as dyslectic on the basis of their reading and/or spelling problems relative to a total group of 1000 4.th grade children in the city of Trondheim, blood tests were obtained on 35 children. A control group of 45 children was drawn among the 1000 children. Among the 12 different hormones measured, significant differences came out on cortisol, triiodothyronine (T. 3), prolactin, and human growth hormone (HGH, somatotrophin) in boys and girls separately. A follow-up study of 22 dyslectic children from the same cohort gave results consistent with those obtained in the original study. The higher values of the dyslectic group on cortisol and prolactin may suggest the dyslectics to be in a stressful situation, possibly due to their language problems in school. The most striking difference, however, was the very low levels of HGH in the dyslectic group—to the extent that there was little overlap in the two distributions. This result was totally unexpected and is, in fact, opposite of what to be expected on the basis of at least short — time stress events. The results holds up when age and pubery development are controlled for.     

Dyslexia laws in the USA

Throughout the various states of the USA, the appropriate identification of dyslexia and the timely provision of interventions are characterized by variability and inconsistency. Several states have recognized the existence of this disorder and the well-established need for services. These states have taken proactive steps to implement laws and regulations for both identification and treatment, and the provision of equal access to students who are diagnosed with dyslexia. The majority of states, however, have not developed such laws and guidelines. The purposes of this article are to review the present status and content of these dyslexia laws, highlight some differences among the laws and regulations across states, and suggest strategies for initiating such laws.     

Dyslexia and oral reading errors

Thomson was the first of very few researchers to have studied oral reading errors as a means of addressing the question: Are dyslexic readers different to other readers? Using the Neale Analysis of Reading Ability and Goodman's taxonomy of oral reading errors, Thomson concluded that dyslexic readers are different, but he found that they do not resemble beginning readers. Thomson's study and his use of miscue analysis is re‐evaluated, both in relation to the educational and political climate of the time – which was hostile to the concept of dyslexia – and in the light of research and social developments since then. The study of oral reading still has value today, both for the teacher and the researcher, provided its limitations as a technique are fully appreciated.     

Dyslexia and education in the 21st century

This paper both reviews the other papers in this special issue and puts them in the context of the current agenda of research in dyslexia education. The pluralistic nature of the field is explored with reference to this special issue. The paper suggests a way forward for the field in terms of a developing research agenda for dyslexia education as we progress further into the 21st century.