Dyslexia In Children

Angela Fawcett, Rod Nicolson

• Editorial: Routledge
• Año: 2017
• ISBN:
  9781315504759
• Edición: 1
• Categoría: Littérature
• Categoría: Critique littéraire

This text links general skills difficulties to dyslexia. It examines the research which has found that dyslexic children have problems not just with their reading but in a range of skills including several (such as balance) unrelated to reading.

Part 1
Phonological skills, reading and dyslexia

Difficulties in learning to read are, of course, the litmus test for dyslexia, and it is therefore appropriate to begin this volume with two chapters which together provide a detailed overview of the skills involved in reading in normal and dyslexic children. One of the major achievements of international research on dyslexia in the 1980s was the emergence and refinement of the ‘phonological deficit’ hypothesis as a near-complete explanation of the problems dyslexic children face when learning to read. In brief, the hypothesis states that dyslexic children have an impairment in the ability to detect and process speech sounds (phonology), and that this impairment critically limits the skills which are a prerequisite for reading, such as the ability to detect rhymes, and, later, the ability to ‘sound out’ words and ‘blend’ sounds when trying to decipher the written word.

John Rack has worked with groups in London, York and Colorado investigating the phonological deficit hypothesis, and has provided an authoritative overview of its current status. Rack makes it his task to assess the adequacy of the phonological deficit hypothesis in terms of the four criteria of specificity (why is the problem specific to reading-related skills rather than more general cognitive abilities?), causality (are phonological deficits the cause, a consequence or a correlate of the reading problems?), process (can one specify the process by which phonological deficits result in reading problems) and variation (are differences in severity of phonological deficit sufficient to account for individual variations in reading difficulty?). Considering first the issue of specificity, Rack presents a range of studies of phonological deficits, including short-term memory, verbal repetition, long-term memory and naming, thereby explaining and establishing the case for the phonological deficit hypothesis. In an investigation of causality, he then goes on to consider more direct assessments of phonological skills, including rhyming and phonological awareness, and their role in learning to read. Next he links these deficits to evidence from the specific difficulties identified in dyslexics, emphasising nonword reading deficits and error analysis. In an important theoretical analysis of the processes involved, Rack links these findings to a model of reading development, considering in particular the role of phonetic cues in early reading. He argues that dyslexic children are able to make use of limited phonetic cues in reading, but that they would have continuing difficulties with the more complex processes of grapheme-phoneme mapping. Rack concludes that the phonological deficit hypothesis fulfils the criteria for a difficulty in processing outside the realm of reading, which impacts upon the development of literacy skills.

In the second chapter, John Beech focuses on Rack’s third issue, the processes by which dyslexic children acquire reading abnormally, and presents a thorough and detailed overview of current theories and data on children learning to read, considering the development of reading skills in normal readers. He draws on ‘dual-route’ theories of reading, which assume that a word may be read either as a whole via visual features (the lexical or logographic route) or assembled from the series of word segments such as the individual graphemes (the sublexical route). The logographic route is typically found in the early stages of reading, whereas the sublexical route is dependent on word segmentation and blending using phonological cues. A major issue considered is whether or not dyslexic children who rely predominantly on logographic (whole word) reading are able to become fluent readers without acquiring sublexical skills. First, he considers the evidence for the development of reading in a population of deaf children, who are limited to the logographic skills in their route to reading. He goes on to discuss connectionist simulations of reading; case studies of acquired dyslexia in mature readers with minimal sublexical skill; and the development of automaticity in normal children. Then he considers the evidence for the development of fluency in dyslexia, first in adults, and then in a longitudinal case-study of reading with minimal sublexical involvement.

Beech next discusses the development of sublexical skills (that is, skills in processing the components of words), in particular the development of reading and phonology in normally achieving readers, and presents a meta-analysis of the effects of training on segmentation and blending. He considers the unit of analysis in the sublexical route, whether simply grapheme to phoneme or onset and rime. Beech explores the issue of resistance to developing lexical skills in a small subgroup of dyslexics, who are unable or unwilling to use this route. He discusses the lack of interaction between lexical and sublexical processes in training studies, suggesting that these might represent either the impact of cumulative deficits, or an intractable resistance to training in sublexical skills. He concludes that a subset of dyslexic children may be limited to reading by analogy, missing out the sublexical route, and outlines a remediation strategy which could be used.

The third chapter in this part, by Regina Yap and Aryan Van der Leij, examines an issue highlighted by both Rack and Beech, namely the question of whether, given extensive training, dyslexic children are able to acquire normal fluency of reading, or whether there is indeed some intractable problem within the processes involved. Rather than phonological skill, however, they focus directly on the time taken to perceive a written word. Of particular interest is their finding that, even when dyslexic Dutch children were matched with (younger) normal children on reading ability, the dyslexic children required more time to perceive a word when the words were presented for very brief periods. Furthermore, a second, longitudinal study suggested that this ability to detect words under speeded conditions improved more slowly with time for the dyslexic children. The authors conclude that dyslexic children have greater than normal difficulties in acquiring fluency in reading-related skills, a conclusion consonant with the positions taken by Rack and by Beech. Their account, in terms of difficulties of automatisation of skill, is somewhat different from that provided by the phonological deficit hypothesis, and provides a valuable link to the material reviewed in Part 2 of this volume.

Chapter 1
Dyslexia: The Phonological Deficit Hypothesis

John P. Rack

Introduction

The present chapter is concerned with the relationship between phonological skills and specific reading difficulties or dyslexia. In particular, it is concerned with the hypothesis that a deficit in the processing of phonological information – information about the sounds of words – is at the root of most dyslexics’ reading and spelling problems. This is the theory that is here called the Phonological Deficit Hypothesis. Many variants of the theory exist (e.g., Bradley and Bryant, 1983; 1985; Brady, 1986; Frith, 1981; 1985; Goswami and Bryant, 1990; Liberman and Shankweiler, 1979; Mann, 1984; Olson et al., 1990; Shankweiler et al., 1979; Snowling, 1987; Stanovich, 1988; Vellutino and Scanlon, 1987), some of which are more concerned with normal development and some more with reading difficulties. Before reviewing some of the recent evidence that supports the phonological deficit hypothesis, it is useful to discuss the general problems for all deficit accounts of dyslexia and to show how these have been addressed, with some success, in the literature on phonological skills. As we shall see later, some people have argued that it is now the right time to redefine dyslexia to reflect the central role of phonological processes in its aetiology (Catts, 1989; Siegel, 1988). A major theme of the present chapter is to identify the type of evidence which would be necessary for such a redefinition and to see how well the evidence supporting phonological deficit theory goes towards meeting these requirements.

Dyslexia has typically been defined, negatively, by applying a set of exclusionary criteria. Thus a dyslexic person must have average or above average intelligence; adequate opportunities to learn to read; no sensory or neurological damage and no psychiatric or emotional problems (Critchley, 1970; Stanovich, 1986; Vellutino, 1979). Dyslexic children are therefore something of a puzzle: they are poor readers and spellers, but there is no obvious reason why this should be so. Indeed, the lack of any obvious explanation leads some to deny the existence of the condition itself.

Most people, however, now accept that dyslexia is a specific and sometimes subtle difficulty with aspects of learning or information processing. The highly specific processing difficulties shown by dyslexic children are of great interest to psychologists who wish to understand the components (or modules) of cognitive abilities. The existence of specific deficits, along with evidence for specific abilities, is powerful evidence for a ‘componential’ theory of intellectual functioning (see Sternberg, 1982, for further discussion). It would be very informative if it could be shown that there is a particular cognitive deficit which affects reading and spelling skills but has a relatively minor influence on other intellectual abilities. In this spirit, a large amount of research has been directed at identifying the specific cognitive deficits that ‘go along’ with dyslexia, and which may be at the root of the problem.

Understanding the unexpected or unusual problems that cause dyslexia is an important goal for practical as well as theoretical purposes. It has considerable significance for dyslexic people themselves and for their parents and teachers who may feel responsible for their children’s difficulties. An understanding of the underlying cause of dyslexia is also an important first stage in devising appropriate remedial programmes. Remedial programmes need both to target the areas of weakness and to seek ways around severe difficulties which may be resistant to teaching.

An understanding of the causes of dyslexia should lead to a more satisfactory (positive) definition of dyslexia. Such a definition would allow identification of people who have behavioural or emotional problems at school because they have specific reading and spelling problems. Their behaviour may be the result of the unsympathetic treatment that they have received from parents or teachers, or it may be their way of avoiding confronting their reading and spelling problems. Either way, such people would not meet the exclusionary criteria for dyslexia although they may have reading and spelling difficulties for the same reasons as dyslexics. Rather than relying on the exclusionary criteria, it would therefore be preferable to identify dyslexia using a set of positive symptoms (Catts, 1989; Fletcher and Morris, 1986; Miles, 1983).

A final, important practical consequence of a proper understanding of the causes of dyslexia is that it should facilitate early detection of potential difficulties. If we know which cognitive difficulties are at the root of dyslexia, it may be possible to screen for those difficulties at an early stage and possibly prevent reading and spelling problems from arising.

Thus, deficit accounts of dyslexia are very attractive since the theoretical and practical consequences are extensive. Early research focused on the role of visual-processing difficulties, but a comprehensive review by Vellutino (1979) showed that much of the evidence could be interpreted in terms of verbal difficulties. Attention then shifted to verbal, and specifically phonological, skills and this is the area receiving the greatest research attention today. Interest in visual and other skills remains, as the other chapters of this book testify, and, as will become apparent, the present hypothesis does not deny the importance of some of these factors. Before going on to consider the evidence relating to the phonological deficit theory, we turn to the general problems for all deficit accounts of dyslexia. These we may term specificity, causality, process, and variation.

The nature of the current exclusionary definition of dyslexia dictates that the relevant underlying deficit must be highly specific. A general explanation, in terms of gross differences in visual or phonological differences, or in terms of general rule acquisition skill (Morrison and Manis, 1983), is hard to reconcile with the definition of dyslexia as a specific learning difficulty. Such global deficits would be expected to influence abilities more generally and therefore lead to learning problems across a wide range of cognitive domains. (See Stanovich, 1986, for an elaboration of this argument.) A slightly different possibility is that an underlying deficit is very mild. It may therefore go undetected except in particularly demanding circumstances. In either case, deficit accounts need to explain why some tasks (notably reading and spelling) pose more problems for dyslexic individuals than are posed by other tasks.

The second challenge for deficit accounts is to determine whether poor reading is a cause or a consequence of the as...