D e v e l o p m e n t a l d y s l e x Research Review i a i n a d u l t s : a r e s e a r c h r e v i e w Developmental dyslexia in adults: a research review This report is funded by the Department for Education and Skills as part of Skills for Life: the national strategy for improving adult literacy and Michael Rice with Greg Brooks numeracy skills. The views expressed are those of the author(s) and do not necessarily reflect those of the Department. May 2004 www.nrdc.org.uk NRDC NRDC is a consortium of partners •Basic Skills Agency Funded by the Institute of Education led by the Institute of Education •Learning and Skills Department for University of London with: Development Agency Education and Skills as 20 Bedford Way •Lancaster University •LLU+, London South part of Skills for Life: London WC1H 0AL •The University of Nottingham Bank University the national strategy for Telephone: +44 (0)20 7612 6476 •The University of Sheffield •National Institute of improving adult Fax: +44 (0)20 7612 6671 •East London Pathfinder Adult Continuing literacy and numeracy email: [email protected] •Liverpool Lifelong Learning Education skills. website: www.nrdc.org.uk Partnership •King’s College London Published by the National Research and Development Centre for Adult Literacy and Numeracy This report may be downloaded as a PDF document from the NRDC website at www.nrdc.org.uk We welcome feedback on the content and accessibility of this publication. This should be sent to: Publications NRDC Institute of Education 20 Bedford Way London WC1H 0AL. Telephone: +44 (0)20 7612 6476 Fax: +44 (0)20 7612 6671 email: [email protected] ISBN 0 954649281 © Crown Copyright 2004 Extracts from this publication may be used or reproduced for non-commercial, research, teaching or training purposes on condition that the source is acknowledged. NRDC is a consortium of partners led by the Institute of Education, based in the Bedford Group for Lifecourse and Statistical Studies at the IoE. www.ioe.ac.uk/bedfordgroup Design: Chapman Design Limited Photography: Phillip Meech Print: Bradell Developmental dyslexia in adults: a research review Michael Rice with Greg Brooks CONTENTS PREFACE 7 FOREWORD 9 SUMMARY 11 Part one KEY ISSUES IN DYSLEXIA RESEARCH 13 Introduction 13 Conceptual issues 16 The context 16 How can dyslexia be defined? 17 Who do we describe as ‘dyslexic’? 17 What kind of causal process might result in dyslexia? 19 What is the prevalence rate of dyslexia? 19 Research issues 21 Choosing the concept 21 Making the concept a reality 21 Choosing the comparison group 23 Choosing the strategy 24 Interpretational issues 25 Do ‘dyslexic’ brains differ from ‘normal’ brains? 25 Introduction 25 Evidence from post-mortem studies 25 Evidence from in vivo studies: structural differences 27 Evidence from in vivo studies: functional differences 28 What do the brain studies tell us? 30 Is there a gene for dyslexia? 31 Introduction 31 Modes of inheritance and their implications 31 Do ‘dyslexics’ and ‘non-dyslexics’ differ in kind or in degree? 33 The statistical evidence 33 The psychometric evidence 34 Are diagnoses of dyslexia stable across methods of ascertainment? 34 Are diagnoses of dyslexia stable over time? 36 Are there phonological and surface subtypes of dyslexia? 37 Is there any bias in our perception of dyslexia? 39 Can the research findings be applied to adults in literacy and numeracy classes? 40 The crux of the problem 40 Part two EXPLANATORY THEORIES OF DYSLEXIA 42 Introduction 42 Phonological awareness 44 Background 44 What is phonological awareness? 44 Individual differences in phonological awareness 46 The reciprocal relationship between phonological awareness and readingability 47 Are there any impediments to the acquisition of phonemic awareness? 48 Summary 49 Dyslexia and alphabetic skills: the phonological deficit theory 49 The phonological deficit theory 49 What does the phonological deficit theory explain? 50 What does the phonological deficit theory not explain? 50 Do phonological deficits differentiate ‘dyslexics’ from other poor readers? 51 Limitations of the phonological deficit theory: the phonological-core variable-difference model of reading disability 52 What does the phonological-core variable-difference model predict? 53 Is there an alternative to the phonological-core variable-difference model? 54 Dyslexia and lexical access: the double-deficit hypothesis 55 Introduction 55 Is fluency distinct from phonological processing? 55 Cognitive components of rapid naming 56 What causes the naming-speed deficit? 56 The diagnostic significance of naming speed tasks 57 Naming-speed deficits in other languages 58 The relation of naming-speed to psychometric and demographic variables 58 The prognostic significance of naming-speed deficits in dyslexia 58 Limitations of the double-deficit hypothesis 59 Dyslexia and automaticity: the cerebellar deficit hypothesis 59 Introduction 59 The dyslexia automatisation deficit hypothesis 60 The cerebellar deficit hypothesis 60 Limitations of the cerebellar deficit hypothesis 61 Dyslexia and processing speed: the temporal processing deficit theory 62 Introduction 62 Do dyslexics have a temporal deficit in visual processing? 63 Do dyslexics have a temporal deficit in auditory processing? 64 The magnocellular deficit hypothesis 65 Limitations of the magnocellular deficit hypothesis 65 Part three THE NEXT GENERATION OF THEORIES 67 Introduction 67 A cognitive process model of reading disability 67 A self-organising systems model of reading disability 68 An atypical brain development framework for developmental learning disabilities 70 Part four TOWARDS GOOD PRACTICE FOR DYSLEXIC STUDENT IN ADULT LITERACY AND NUMERACY EDUCATION 72 Introduction 73 What is to be done and why? 73 How successful is intervention likely to be? 73 Limitations in the intervention research 74 Intervention 75 Introduction 75 Curriculum 76 Methods 77 Agents 78 Evaluation studies 79 Introduction 79 How can we know what really works? 80 Intervention studies with adult dyslexics 82 A multisensory alphabetic phonetic approach with college students 82 Dyslexia and psychodynamics: a case study of a dyslexic adult 83 Task-determined strategies of visual process 83 Simultaneous multisensory instructional procedure 84 Spelling improvement for college students who are dyslexic 84 Assistive technology for post-secondary students with learning disabilities: from research to practice 85 Computer-based compensation of adult reading difficulties 85 Summary 86 General Conclusions 87 REFERENCES 89 APPENDICES 133 1 Some definitions of dyslexia 133 2 An analysis of dyslexia definitions 147 3 Some research criteria used in studies of dyslexia 148 4 A general model of reading and influences on reading development 153 5 Referral items in ‘screening’ checklists 154 6 An analysis of referral items in ‘screening’ checklists 157 7 A ‘road map’ for understanding reading disability 162 8 Screening for dyslexic adults 163 9 Some recommended reading for literacy teachers 167 10 Anatomy and functions of the brain 170 TABLES 1 Four theories of dyslexia and their explanatory compass 66 2 Selected intervention studies with adult dyslexics 82 3 Locations and functions of Brodmann’s areas 171 FIGURES A Brodmann’s areas 173 B Lateral surface of the left cerebral hemisphere, cerebellum (C), brain stem and rostral spinal cord (S), indicating the frontal (F), parietal (P), temporal (T), and occipital (O) lobes 174 C Lateral view of the left cerebral hemisphere and rostral view of the cerebralcortex, with main features 175 D Cortical surface of the left cerebral hemisphere and mid-sagittal section,showing the main features 176 This report is funded by the Department for Education and Skills as part of Skills for Life: the national strategy for improving adult literacy and numeracy skills. The views expressed are those of the authors and do not necessarily reflect those of the Department. Developmental dyslexia in adults: a research review 7 Preface A rigorous review of research on dyslexia is long overdue. ‘Developmental Dyslexia in Adults: a research review’ aims to generate and share new knowledge, based on evidence from sound research, to add to all that is already known about dyslexia from practice, informed advocacy and research and development work by organisations which have been active in the field over several decades. So NRDC is pleased to publish this report from a rigorous, peer-reviewed research project. The report can inform policy development and teaching and learning practice by enhancing the evidence base on which decisions are taken and new directions pursued. We believe it will deepen and enrich our knowledge of dyslexia and in addition inform literacy provision for other groups ofSkills for Lifelearners. It is important to emphasise that this is a review of research, not a review of practice or policy. However, we believe that a strong partnership based on the combined approaches of researchers, practitioners, dyslexia organisations and policy makers can make a real difference for the learners whose needs this report highlights – people with dyslexia. The major project: ‘A Framework for Understanding Dyslexia’ conducted recently by LSDA and NIACE has identified existing approaches to the teaching and learning of adults with dyslexia. Wherever good approaches could be found, they have been bought together to illuminate possible strategies for people whose learning needs, as with most learners of literacy, numeracy and language, can be better identified and met by carefully designed and focused teaching and learning strategies. NRDC’s recent report ‘Adult Numeracy: review of research and related literature’ analysed research on dyscalculia. These new pieces of work, adding to the large body of work already carried out by dyslexia organisations, LLU+ at South Bank University and others, have the potential to raise significantly the quality of educational opportunities for people with dyslexia, whose learning needs can be better identified and met by carefully designed and focused teaching and learning strategies. We hope the report will interest organisations and teachers working with dyslexic adult learners. We strongly believe the messages here can also speak to many practitioners engaged in wider literacy provision for young people and adults. It is critical to improve learning opportunities and focus sharply on the best methods of teaching to help learners overcome the obstacles they face, achieve more and progress in life and work. The report indicates that the work done in the field of dyslexia to help dyslexic people learn has much to offer literacy practitioners working with learners who are not dyslexic. This is because dyslexia practice has developed structured, explicit approaches to teaching, which are geared to the assessed needs of individual learners and which are successful in helping many learners. There is evidence that the approaches to teaching developed for the field of dyslexia might well be appropriate for other groups of people learning to improve their literacy. The findings of this study connect interestingly with other NRDC research into effective teaching and learning. We are finding out from research projects on reading, that much literacy teaching does not systematically use explicit teaching strategies in the blend of teaching and learning activities in the classroom. We also know that, for many adult literacy learners, significant progress is elusive. We are now carrying out five extensive linked studies of Effective Teaching and Learning Practice: in reading, writing, ESOL, numeracy and ICT. These studies, based on assessments and detailed observation of classrooms and other settings, are investigating 8 Research Report which strategies do make a difference to learners’ progress and achievement. ‘Developmental Dyslexia in Adults: a research review’ also finds that there are many reasons why people find it difficult to learn to read and write and suggests that we should find out much more about why different groups of people find reading and writing, language and number difficult to learn, for a range of different reasons. It seems likely that we are not looking at a simple straightforward divide between people with dyslexia and people whose education has been unfulfilling and unrewarding, whether because of lack of support at school or home, poverty or other external factors. This is why we have placed phrases such as‘ordinary poor readers’, which are used commonly in the scientific literature in speech marks: this review questions such a divide. The reasons adults have difficulty with literacy and numeracy are multiple and complex and we should begin to explore them thoroughly so that we can help people to overcome them, and achieve. At NRDC we would very much like to work with partner organisations in the field of dyslexia and related areas to discuss the findings of this review and to look at priorities for further research and development so that we can better match the needs and difficulties learners have with teaching strategies which will enable them to achieve. Please contact us if you would like to work with us. Ursula Howard Director, NRDC Developmental dyslexia in adults: a research review 9 Foreword This is a critical review of the extensive and complex researchliterature on developmental dyslexia as it might apply to adults participating in courses which offer literacy, numeracy, and English for speakers of other languages (ESOL). By using electronic databases, including the Science Citation and Social Science Citation Indexes, ERIC and Medline, by making visual inspections of library holdings at the Institute of Education, University of London and elsewhere and by searching the Internet, we identified a large number of potentially relevant book chapters or papers published in peer-reviewed journals. Although we set our watershed at 1987, we included earlier items when continuing citation underlined their importance. From more than three thousand items initially identified, we selected 1,800 items for inspection. We obtained reprints or made photocopies of 1,220 items, which we then read and annotated. Because very few of the items deal specifically and exclusively with adults and even fewer dealt with adults in basic education, we have needed to make cautious inferences from the literature on childhood dyslexia. In our review, we consider the major explanatory theories of dyslexia and their implications for practice. We also consider some recent alternative perspectives on developmental reading difficulties. A draft version was reviewed by a panel of academic experts and this version incorporates nearly all of their suggested amendments and additions. We conclude that there is no evidence from research to support a policy of differentiating dyslexic from non-dyslexic students in adult literacy, numeracy and ESOL. We offer five main reasons for our conclusion. First, both dyslexic and non-dyslexic students need to acquire the same knowledge and skills in literacy and numeracy. Second, structured and explicit tuition is appropriate for both groups. Third, individual differences between students occur along many dimensions, while all classification schemes entail overlapping categories. Fourth, diagnostic protocols for dyslexia in adults cannot be used with any confidence either to ascertain the causes (as opposed to the symptoms) of literacy or numeracy difficulties or to predict the outcomes of interventions. Fifth, the construct of developmental dyslexia is insufficient for a systematic and thorough appraisal of learners’ difficulties in adult education. With respect to adult literacy, we also conclude that successful teaching is informed by the tutor’s understanding of ‘normal’ language and literacy acquisition. Our conclusions are not to be taken to mean that ‘nothing works’; practitioners know many things that have ‘worked’ for particular learners. However, that is professional wisdom based on experience and an analysis of that knowledge was not part of our remit. Nevertheless, there is a clear need for research which draws on practitioner knowledge and wisdom and investigates whether there are grounds for categorising learners as either ‘dyslexic’ or as ‘ordinary’ adult learners with literacy, numeracy and language needs. As our research shows that there are multiple reasons why adults find learning literacy, numeracy and ESOL difficult, we should extend our knowledge of the diversity of causes and the strategies needed to help adults improve their skills. Michael Rice Dr Michael Rice (University of Cambridge, formerly Senior Research Officer, NRDC Institute of Education) with Greg Brooks Research Director, NRDC Sheffield, and Professor of Education, University of Sheffield 10 Research Report Acknowledgements We are grateful to: (cid:2) the seven academic experts who responded to our invitation to comment on either the complete draft or specific sections of it. Two of the seven are themselves the parents of young dyslexic adults; (cid:2) library staff at the Institute of Education, University of London, the University of Cambridge Institute of Education, Cambridge University Library and the Department of Experimental Psychology at the University of Cambridge; and (cid:2) Felicity Rees, who edited an earlier draft and provided a first draft of an executive summary. Project team and authorship Greg Brooks was the project director, gave advice and edited the final draft. Michael Rice was the Senior Research Officer. The rest of the project and this report, was his work, including authorship of the entire text.