Thesis Submitted for the Degree of Doctor of Philosophy University of Bath Department of Psychology
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University of Bath PHD Defining the early indicators of dyslexia: providing the signposts to intervention Pneuman, Susan Award date: 2009 Awarding institution: University of Bath Link to publication Alternative formats If you require this document in an alternative format, please contact: [email protected] General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Download date: 30. Sep. 2021 Defining the early indicators of dyslexia: providing the signposts to intervention Volume 1 of 1 Susan M. Pneuman A thesis submitted for the degree of Doctor of Philosophy University of Bath Department of Psychology March 2009 Copyright Attention is drawn to the fact that copyright of this thesis rests with its author. A copy of this thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with the author and they must not copy it or use material from it except as permitted by law or with the consent of the author. This thesis may be made available for consultation within the University Library and may be photocopied or lent to other libraries for the purposes of consultation. 1 Contents Chapter 1 Introduction to Developmental Dyslexia 8 1.1 Varying Definitions 9 1.2 Prevalence Rates 12 1.3 Intelligence and Dyslexia 13 1.4 Impact of Intelligence on Dyslexia 18 1.5 Development of Reading Skills; Theories of Cognitive, Oral and Written Language Development 23 1.5.1 Relationship between Spoken and Written Language 27 1.5.2 Adams Model of Reading Systems 29 1.5.3 Uta Frith’s Theory of Reading Development 32 1.5.4 Jeanne Chall’s Stages of Reading Development 33 1.6 Cultural Influences on Reading Ability 36 1.7 Summary 42 Chapter 2 Theories of Developmental Dyslexia 44 2.1 Neurological/Sensory 48 2.1.1 The Visual Theory 2.1.2 Rapid Auditory Processing Theory 52 2.1.3 The Magnocellular Theory 55 2.2 Neurological and Brain Structure Theories 60 2.2.1 Cerebral Lateralization 60 2.2.2 Study of the Neuro-anatomy of the Brain 61 2.3 Cognitive Theories 62 2.3.1 Memory Deficits 62 2.3.2 Phonological Theory 63 2.3.3 Small and Large Unit Theories of Reading Acquisition 65 2.4 Summary 66 Chapter 3 Phonological Theory of Language Development 68 3.1 What is Phonological Knowledge and How Does it Develop? 68 3.2 Rhyme and Onset-Rime 73 3.3 Phonological Processing 75 3.4 Deficits in Phonological Processing Lead to Reading Disability 78 3.5 Pseudo-word Reading 81 3.6 Working Memory 83 Chapter 4 Genetic and Environmental Factors 92 2 4.1 Introduction 92 4.2 Genetic Factors 92 4.3 Environmental Factors 95 4.4 Sex 100 4.5 Digit Ratio 101 4.5.1 Cerebral Lateralization and Digit Ratio 102 4.5.2 Cognitive Abilities and Digit Ratio 104 4.6 Summary 108 Chapter 5 Brain Plasticity 110 5.1 Neurological Imaging and Reading Disability 113 5.2 Plasticity 116 5.3 Strategic Learning 118 5.3.1 Development of Strategic Learning 119 5.4 Dynamic Skill Theory 120 5.5 Interventions 123 Chapter 6 Identification of Factors Related to Literacy in Pre-reading Children 125 6.1 Introduction 125 6.2 The Alphabetic Principle 134 6.3 Dyslexia and the Development of Reading 137 6.4 Intervention Methods 140 6.6 Summary 148 Chapter 7 Study 1 151 7.1 Introduction 151 7.2 Method 151 7.2.1 Participants 151 7.3 Design 153 7.3.1 Measures 153 7.4 Observations 161 7.5 Results 162 7.6 Interactions with Sex 170 7.7 Digit Ratio 171 7.8 Wide Range Achievement Test (WRAT) Reading 173 7.9 Wide Range Achievement Test (WRAT) Spelling 174 7.10 Identification of Rhyme 175 7.11 Phonemic Segmentation 176 7.12 Phoneme Related Tasks 177 7.13 Controlled Associations 181 7.14 Reading of Multi-Syllabic Words 183 7.15 Correlations 185 7.16 Discussion 186 3 Chapter 8 Study 2 195 8.1 Method 195 8.1.1 Participants 195 8.1.2 Design 196 8.2 Measures 200 8.3 Identification of Language and Phonological Assessments 203 8.4 Results 206 8.5 Discussion 213 8.6 Summary 217 Chapter 9 Study 3 219 9.1 Method 220 9.1.1 Design 222 9.2 Preschool Intervention Plan 225 9.3 Results 228 9.4 Discussion 238 Chapter 10 Implications and Conclusions 245 10.1 Study 1 250 10.2 Study 2 256 10.3 Study 3 258 10.4 Conclusions 262 10.5 Limitations and suggested further research 270 10.6 Summary 272 References 273 4 List of Tables Chapter 7 Table 7.1 Group statistics 152 Table 7.2 Results of performance on study 1 – reading/spelling/segmentation 162 Table 7.3 Results of performance on study 1- CORE phoneme deletion tasks 164 Table 7.4 Results of performance on study 1 – PALPA rhyme 164 Table 7.5 Results of performance on study 1 – controlled associations/BPVS 164 Table 7.6 Results of performance on study 1 – CORE phonological survey 165 Table 7.7 Results of performance on study 1 – digit ratio 167 Table 7.8 Results of measures sorted by effect size (small) 168 Table 7.9 Results of measures sorted by effect size (medium) 169 Table 7.10 Results of measures sorted by effect size (large) 169 Table 7.11 Comparison of digit ratio between genders for both groups 172 Table 7.12 Results for dyslexic group and control group in WRAT reading 174 Table 7.13 Results for study group and control group for phoneme segmentation 176 Table 7.14 Results between groups and gender for controlled associations 182 Table 7.15 Significant difference in performance between dyslexic and non-dyslexic groups 184 Chapter 8 Table 8.1 Study 2 demographic information 196 Table 8.2 Correlation between intelligence and reading scores 208 Table 8.3 Digit ratio males versus females 211 Table 8.4 Digit ratio and pre-literacy skills 212 Chapter 9 Table 9.1 Age range of participants for study 3 230 Table 9.2 Comparison of performance on pre and post intervention measures 231 Table 9.3 Mean performance on measures pre and post intervention 232 5 List of Figures Chapter 1 Figure 1.4 Two alternative models of the relationship between intelligence and reading disorder 21 Figure 1.5 Adam’s Model of Reading Systems 30 Chapter 3 Figure 3.1 Mapping phonological knowledge 71 Figure 3.6 Model of working memory 85 Chapter 5 Figure 5.1 Left side view of brain and areas of activation 110 Chapter 7 Figure 7.1 Interaction between group and gender for WRAT reading 167 Figure 7.2 Interaction between group and gender for British Picture Vocabulary Scale (BPVS) 170 Figure 7.3 Interaction between group and gender for average digit ratio 173 Figure 7.4 Interaction between group and gender for WRAT spelling 175 Figure 7.5 Interaction between group and gender for rhyme 176 Figure 7.6 Interaction between group and gender for phoneme deletion – first sound of blend 178 Figure 7.7 Interaction between group and gender for consonant sounds 179 Figure 7.8 Interaction between group and gender for “r” and “l” controlled 180 Vowels Figure 7.9 Interaction between group and gender for variant vowels and diphthongs 181 Figure 7.10 Interaction between group and gender for multi-syllabic words 184 Figure 9.1 Age range of participants for Study 3 221 6 Abstract The general aim of this thesis was to identify the indicators of reading disability and to analyze the effect of these factors in preschool age children in order to determine which factors play a principal role in the development of dyslexia. Various theories of developmental dyslexia have been investigated and the key components of major theories are presented in this paper. It is a generally held view that dyslexia is caused by a deficit in phonological processing which is an inability to understand the sound structure of language. This thesis aims to unite current research findings in order to better classify dyslexia as well as to determine approaches to intervention which are critical to a preschool child’s development of literacy. Three studies were conducted. The goal of study 1 was to determine the discrepancies in performance between non-dyslexic readers and dyslexic readers. Study 2 investigated phonological awareness abilities in preschool age children and their relationship with intelligence. An intervention study was then carried out on the preschool participants to determine the effects of instruction in the alphabetic principle on elements related to intelligence and phonological awareness. The results of this thesis and the studies conducted herein found a wide range of domains that were causal to reading disability. These include visuo-spatial discrimination skills, phonological knowledge and working memory.