Dyslexia and Language Impairment: Risk and Protective Factors Maggie Snowling University of York

1. Dyslexia and Language Impairment: Risk and Protective FactorsMaggie SnowlingUniversity of York http://www.york.ac.uk/res/crl/

2. Phonology Semantics Grammar Pragmatics Language skills and learning to read • Phonology • How speech sounds convey meaning • Language skills beyond phonology • Vocabulary • Grammar • Pragmatics

3. Spectrum of Reading Disorders (Bishop & Snowling, 2004) + Poor comprehender Normal Reader phonology + L- Oral Language Dyslexia Language Impairment P-

4. Talk will contrast language and phonology • How reading depends on language and phonological skills • Model highlighting risk factors for literacy problems • Intervention programmes to promote language and phonological skills

5. Two Distinct Forms of RDDyslexia vs Poor Comprehender phonology beyond phonology

6. Use of context in reading depends on grammatical skills Predicts: Dyslexia = normal sentence context effect Poor comprehender = reduced context effect

7. Contextual Facilitation: Dyslexia vs Poor Comprehender • Low constraining contexts • I went shopping with my mother and my.. • We end assembly at school with a ... Nation & Snowling, 1998 Child Dev

8. Text comprehension requires inferencing skills Predicts: Dyslexia = automatic inferencing Poor comprehender = fewer inferences

9. Holly was on a school trip. Her class were going to the zoo as part of ‘wild week’. They saw elephants, monkeys, zebras and tigers. Holly wanted to see the lions most of all. She could see them, but they were all asleep. “Wake up!” shouted Holly. Suddenly, one of the lions jumped up and ran towards her. The lion ran up to the fence where Holly stood and made a huge roar! Holly had never been so scared.She ran away fast. “He didn’t want to be woken up!” said her teacher.

10. Holly was on a school trip. Her class were going to the zoo as part of ‘wild week’. They saw elephants, monkeys, zebras and tigers. Holly wanted to see the lions most of all. She could see them, but they were all asleep. “Wake up!” shouted Holly. Suddenly, one of the lions jumped up and ran towards her. The lion ran up to the fence where Holly stood and made a huge roar! Holly had never been so happy.She ran away fast. “He didn’t want to be woken up!” said her teacher.

11. Effects of Text-level Context on Reading Time: Dyslexia vs PC L. Clarke & Snowling

12. Modular view of Disorders: Summary Contrasting profiles of dyslexia (RD) and reading comprehension impairment (PC) Double dissociation of phonological and semantic reading skills

13. Questioning Modularity • The extent to which developmental disorders are selective is over-stated (Thomas & Karmiloff-Smith, 2002) • Genes are generalists (Plomin & Kovas, 2005) • Single-deficit accounts are inadequate to explain developmental disorders (Pennington, 2006; Bishop, 2006; Pennington & Bishop, 2009)

14. Family-Risk Study • Children with a parent with dyslexia • seen at 4, 6 and 8 years (Snowling, Gallagher & Frith, 2003) • follow up at 12-13 years (Snowling, Muter & Carroll, 2007) • Controls from families with no history of dyslexia, similar SES • >40% persistent literacy difficulties • (dyslexia); compare with at-risk normal readers and controls

15. Oral Language Age 4 Expressive language Nonword repetition

16. Phonological Awareness Age 6 rhyme 12.00 10.00 8.00 6.00 4.00 2.00 0.00 phoneme

17. Characteristics of family-risk sample • Two ‘sorts’ of phonological deficit in pre-school • Poor phonology + delayed language (P-/L-) • Poor phonology + normal language (P-/L+) • Developmental consequences vary: • P-/L- fulfil criteria for dyslexia at 8 years • P-/L+ do not fulfil criteria for dyslexia because of compensation Two risk factors One risk factor

18. Literacy Skills in Adolescence Fluency (TOWRE) Spelling 2 1 2 1 At-risk ‘normal’ readers show weak exception word reading, spelling and reading fluency, relative to controls Exception 1 Broader phenotype of dyslexia

19. Summary: Family Risk Study • Two risk factors for reading impairment (P; L) • Affected and unaffected individuals display some of the same risk factors: • Poor phonology (P-) • Putative endophenotype • Children differ in their ability to compensate • Good language is a protective factor (L+) • Children who have poor literacy through adolescence: • More likely to experience multiple deficits (P- / L- / A-)

20. Dimensions, Risk, and Dyslexia Phenotypes 1 P L Broader Phenotype Dyslexia P L Dyslexia P L SLI-dyslexia Risk 1 Risk 2

21. Dimensions, Risk, and Dyslexia Phenotypes 2 P L Phonological dyslexia P L Dyslexia P L SLI-dyslexia Risk 1 Risk 2

22. Dimensions, Risk, and Dyslexia Phenotypes 3 P L Phonological dyslexia P L Poor comprehender P L SLI-dyslexia

23. Dimensions, Risk, and Dyslexia Phenotypes 4 P L Phonological dyslexia P L L Hyperlexia P L SLI-dyslexia

24. Dyslexia is not as ‘specific’ or selective as once thought Two ‘routes’ to dyslexia: Specific phonological deficits (PD) Downstream effect of poor language mediated by PD Need to think of causes of disorders in a different way Dimensional view emphasizes continuous risk factors that may accumulate to lead to a ‘diagnosis’

25. Causal Model of Dyslexia

26. Implications for Intervention • Dimensions represent important domains for development • Children with poor phonological skills require intervention that includes training in phoneme awareness • Children with wider language difficulties require intervention to foster reading comprehension

27. Intervention Programmes Phonology + Reading Language Speaking and listening Vocabulary training Narrative work (oral) • Letter-sound work • Segmenting and blending • Reading together and reading independently Bowyer-Crane, Snowling, Duff, Fieldsend, Carroll, Miles, Götz, & Hulme (2008)

28. P+R Session Outline

29. OL Session Outline

30. Design of Study • Evaluation of two 20-week programmes (P+R or OL) delivered by teaching assistants • Randomised Controlled Trial (following the CONSORT guidelines) • 4 test phases: pre-intervention (t1), mid-intervention (t2), post-intervention (t3), maintenance test (t4)

31. Relative Advantage of P+R Group in z-score units (95% CIs) Segment/ Blend SPELL raw LK NWR Prose EWR Read comp

32. What causes reading gains? Intervention Group (0,1) Literacy Outcome t4 Early Word Reading IQ (block design)

33. What causes reading gains? Time 1 Time 4 Intervention Group (0,1) Literacy Outcome t4 0.265 .329 0.104 Early Word Reading .472 .267 Segmentation Blending t3 IQ (block design) .265 .224 .273 .225 .164 Letter Knowledge t3 .287

34. What causes reading gains? Time 1 Time 4 Intervention Group (0,1) Literacy Outcome t4 0.265 .329 0.104 Early Word Reading .472 .267 Segmentation Blending t3 IQ (block design) .265 .224 .273 .225 .164 Letter Knowledge t3 .287 Chi sq = .86, df. 1 NS; CFI 1.0; RMSEA 0.00 (0-.208) Literacy outcome is entirely mediated by these two variables . Dropping direct effect of group has no effect on fit indices of model R2 for Literacy 67% ; Total indirect effects on Literacy 4.0%; Indirect effect Grp->Seg/Bl3-> Lit 2.4%; Indirect effect Grp->LK3-> Lit 0.2%. Both indirect effects are reliable

35. Effects of P+R Intervention • P+R intervention program was effective in promoting basic reading skills • Effects maintained 5 months after intervention ceased. • Gains in phoneme awareness and LK generalized to nonword reading at t4 • The beneficial effects of the P+R program on reading are fully mediated by gains in phoneme awareness and letter knowledge (in line with theoretical predictions)

36. Relative Advantage of OL group in z-score units (95% CIs) No transfer to reading comprehension

37. Intervention to Promote Reading Comprehension Clarke, Hulme, Truelove & Snowling, 2010

38. Protocol for ‘ReadMe’ • RCT with 4 groups • Poor comprehenders selected by screening around 1000 children in 20 classes (20 different schools) • In each class the 8 children with the weakest reading comprehension skills (in the presence of adequate decoding) were selected • Selected children allocated randomly to 4 groups: OL, TC, OL+TC, Waiting list • Teaching alternates between individual and dyadic teaching session for 20 weeks

39. Randomised Controlled Trial Design t1 t2 t3 t4 TC block 2 TC block 1 TC OL block 2 OL block 1 OL Maintenance test Mid test Post test Screening Pre test COM block 1 COM block 2 COM Control Control Control Control block 1 Control block 2 Oct - April 2006 8-9 years July 2007 9 years Dec-Jan 2007 9-10 years Dec 2008 10-11 years July 2009

40. Programme contents and features Text Comprehension Written Language Context Reading Comprehension Metacognitive Strategies Inferencing from Text Narrative - written Oral Language Spoken Language Context Listening Comprehension Vocabulary Figurative Language Narrative - spoken • Combined • All eight components • Sessions contained both reading and listening comprehension • Opportunities for children to encounter new vocabulary/idioms/inferences in both written and spoken language.

41. Gains in Text Comprehension Clarke, Hulme, Truelove & Snowling

42. Conclusions 1 • Language and phonological skills – foundation of literacy development • When one set of skills selectively impaired (depending on severity), ‘compensation’ is possible • Intervention programmes targeted to improve phonological skills and LK in ‘at risk’ children are effective (depending on severity) • Intervention programmes targeted to improve reading comprehension are effective (and oral language intervention particularly beneficial) • Response to intervention moderated by co-morbid factors (Duff et al., 2008)

43. Conclusions 2 • Dimensional impairments interact during development to produce heterogeneity within and between disorders • Dyslexia is not a diagnostic ‘entity’ with clear-cut boundaries • Categories of developmental disorder are underpinned by dimensions and associated ‘risk factors’ • Targeted interventions need to focus on dimensions underpinning disorders

44. Acknowledgements • Funders: Wellcome Trust, Nuffield Foundation, MRC, ESRC, British Academy • CRL Research Group • Schools: Pupils, TAs and teachers • All who provided assistance at various times