Dyslexia lecture 2006
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Lecture given at University of London's Institute of Education on dyslexia research
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Dyslexia lecture 2006
- 1. The First Nata Goulandris Memorial Lecture
- 2. First Nata Goulandris Memorial Lecture The effect of orthography on reading and reading problems Uta Frith UCL - Institute of Cognitive Neuroscience 5th June 2006
- 3. A tribute to Nata Goulandris This Memorial lecture takes its key themes from Nata’s main research interests • • • • Her interest and research on reading and spelling Her interest in different orthographies Her interest in cross-language comparisons Her interest in dyslexia
- 4. Nata’s passionate interest in reading and spelling research The Greek origin of the alphabet Alpha Beta Gamma Delta Αα Ββ Γγ Δδ
- 5. Orthography and the origins of the alphabet • Orthos = right, correct • Graphy = writing ορτοσ γραφειν • Different ways of writing down the sounds of speech • The alphabet provides a unique key for mapping speech sounds at sub-segmental level – Below sentence level, below word level, below syllable level • Vowels - the great Greek invention • The shapes of letters, the names of letters, the set of letters used in European writing systems are all based on their original Greek forms.
- 6. European Project A comparison of Italian, French and English readers • Eraldo Paulesu, F. Fazio, D. Perani, S. Cappa, G. Cossu, G. Silani and others • Milan, Brescia, Parma • Jean-Francois Démonet, V. Chanoine, M. Habib and others • Toulouse, Marseille, Grenoble • Cathy Price, E. McCrory, N. Brunswick, C. Frith, U. Frith and others • UCL - FIL and ICN
- 7. Aims of the Project Does depth of orthography affect reading strategy and efficiency? Does it affect dyslexia? Is dyslexia a different disorder in different languages?
- 8. Depth of orthography Shallow orthography what you see is what you hear Speech sound is encoded Each letter maps to one sound You can pronounce previously unseen words Deep orthography what you see is what you know Each letter maps to many sounds You cannot pronounce previously unseen words Sound, origin, meaning of words is encoded
- 9. Shallow orthography The relationship of print-to-sound is transparent As in Italian Roma - Milano N.B. There is ambiguity at the supra-segmental level Word stress is not marked: fémore vs rumòre
- 10. Deep orthography Ambiguous print - sound mappings at both segmental and supra-segmental levels As in English Leicester - Norwich As in French Rhône - Saône
- 11. The ambigous print-to-sound mappings of English rough though you journal would out ourselves thought
- 12. Differences in reading strategy in shallow and deep orthographies Behavioural study reading words, non-words and control tasks Neuroimaging study brain activation pattern during reading explicit reading (reading aloud) implicit reading (exposure to print)
- 13. Behavioural study Participants 72 ordinary university students • 36 from London • (mean age 20.6 sd 3.3) • 36 from Milan • (mean age 20.8, sd=3.0), • Students were matched on course of study arts, science, engineering
- 14. Latencies for words and nonwords 55 0 English RED Italian GREEN * 50 0 * msec 45 0 * En gl i sh I t al i an 40 0 35 0 30 0 words cabin market cottage marmo ponte moto nonwords margo ponda moco nonwords cagin marnet connage * p <.001
- 15. Latencies for ‘International’ words 550 msec 500 English RED Italian GREEN * 450 Engl i s h I t al i an 400 350 300 Italian root taxi bravo pasta panda villa coma English root tennis boiler basket corner partner bitter * p <.001
- 16. Summary - Italian readers • Italian readers read faster • They are even faster reading non-words Taking advantage of unambiguous print-sound relationships at segmental level Strategy of letter-sound translation in segments ‘From small to big’
- 17. Summary - English readers • English readers read more slowly • Even more so when reading non-words - need to disambiguate print-sound mappings Strategy of looking up whole word/segment first more effortful and labour-intensive? ‘From big to small’
- 18. Reading strategy shaped by orthography shaped by language shaped by culture Are the different reading strategies visible in the brain?
- 19. Neuroimaging studies What happens in the brain when we see print? Explicit reading (words vs nothing) “read aloud” Implicit reading (words vs graphic patterns) “yes or no” to ascenders (b,t,l,h) cat: yes yes car: no no 12 Italian normal readers - university students 12 English normal readers - university students
- 21. Greater activation in English readers in ‘word naming area’
- 22. Greater activation in Italian readers in ‘Letter-sound decoding area’
- 23. The brain is affected by differences in orthography Extensive common activation of the same left hemisphere language network In addition In English skilled readers areas associated with word naming more activated In Italian skilled readers areas associated with letter sound decoding more activated
- 24. How do differences in orthography affect dyslexia? Different manifestations in different cultures What is stable? what is variable?
- 25. Dyslexia - the behavioural signs in English WORK BY MAGGIE SNOWLING A developmental disorder Pre-school children difficulties in learning spoken language repeating speech School children difficulties in learning written language phoneme awareness difficult Adults slow reading, poor speling, difficulties in speech processing tasks + difficulties in learning second language
- 26. Is dyslexia a different disorder in different cultures? Estimates of prevalence of dyslexia are often lower than in English speaking countries
- 27. European Project Part II Is dyslexia a different disorder in different languages? A comparison of Italian - French - English dyslexic readers
- 28. Problems of subject selection In Uk and France Adult volunteers previously diagnosed known difficulties in reading and writing acquisition slow reading and poor spelling impaired on phonological tasks In Italy No previous diagnosis Wide screening of students was necessary to select slowest readers and worst on phonological tasks
- 29. Similar participants Full WAIS - standardised in three countries all highly able students
- 30. WAIS subtests where English dyslexics show impaired performance Digit Span Arithmetic Digit Symbol All involve short term memory Excellent performance on all other subtests Also true for French and Italian dyslexics
- 31. Tests where English dyslexics are impaired Reaction time to name words, digits Word Span: Short Term Memory Spoonerisms [Hear] Basket Lemon [Say] Lasket Bemon Also true for French and Italian dyslexics
- 32. Similar stimuli across the three languages Words (frequent regular nouns) UK carrot river banana IT grano terra banana FR melon canard banane Nonwords (very wordlike) UK bonnel rixer barata IT bansio terba barata FR mebon carand barafe
- 37. Italian dyslexics just as different from normally reading controls - as others even though not diagnosed Slow reading and impaired phonological tests are robust indicators For English, French and Italian dyslexics
- 38. Neuroimaging PET scans of explicit and implicit reading 12 dyslexics in each country 12 controls in each country Total = 72
- 39. normal Reduced activation in dyslexia dyslexic
- 40. What are the differences? comparing exposure to print vs baseline in normal and dyslexic readers In English, French, Italian All dyslexics showed reduced activation Italian, English and French
- 41. Are there subtle anatomical differences in the brains of dyslexics? (Giorgia Silani et al., 2005) Investigate whole brain voxel by voxel Look for relative decreases and increases in grey matter
- 42. Function Brain areas that are more active in normal readers than dyslexic readers Structure Yellow/red: decrease in grey matter Blue: increase in grey matter in dyslexics
- 43. Differences in white matter density The arcuate fasciculus connecting regions of the speech system Less dense white matter In dyslexics for all 3 language groups
- 44. Dyslexic FR high grey matter density French low fast reading speed slow Dyslexic IT grey matter density Dyslexic UK Italian grey matter density English reading speed reading speed Fig. 3 Relationship between grey matter increase and reading performance in dyslexic readers
- 45. What does this brain region do? • Part of the speech processing system • Active when things are named – Words, pictures, letters, colours, sounds… – Associated with rapid access to NAMES of things • Names? phonological representations – Heard sounds and programs for articulation
- 46. Nikolopoulos, Goulandris, Hulme and Snowling, 2006 • • • • Rare longitudinal study of Greek readers, age 7 -9 Speech rate best predictor of later reading Phoneme awareness predictor of later spelling Efficiency of speech output system (naming) is critical for dyslexia – In terms of behaviour – Fits with findings on brain anatomy
- 47. Taking dyslexia seriously • The underlying neurological problem persists as shown in brain imaging studies • Compensation has a cost • Is naming speed the final barrier? • Raising awareness of dyslexia
- 48. Dyslexia Biological Unity • universal neuro-cognitive basis – for reading (explicit and implicit) Cultural diversity • diverse behavioural effects – for reading accuracy and speed
- 49. Dyslexia less of a handicap when acquiring a shallow orthography But hidden cases Slow reading and speech processing difficulties Dyslexia’s problems are magnified when acquiring a deep orthography