Language Development and the Brain: A Phonological Perspective Usha Goswami

1. Language Development and the Brain: A Phonological Perspective Usha Goswami Centre for Neuroscience in Education University of Cambridge

2. How does the Brain encode Speech? • Auditory signal • Visual dynamics • Encoding via • oscillations?

3. The Brain and the Speech Signal Phonetics – ba / da NINE SEVEN TWO THREE TWO Syllable structure Rhythm Prosody

4. Behavioural Science Babies use speech rhythm as an early segmentation cue Can also distinguish e.g. ba / pa, syllable stress

5. What is happening in the Brain? Envelope and Fine Structure

6. Smith, Oxenham & Delgutte, 2002:Auditory Chimera • Method for contrasting envelope (slowly varying) • and fine structure (rapidly varying) components • of speech (or other sounds) experimentally • CHIMERA = • Envelope cues from one sentence • Fine structure cues from another sentence • Which sentence will listeners hear?

7. Auditory Chimera Sentences • Perception mainly from fine structure • Not much from envelope • Perception mainly from envelope • Not much from fine structure

8. Envelope information most important for speech intelligibility Early language acquisition: critical role for envelope?

9. Envelope information most important for speech intelligibility Emphasises importance of speech rhythm and syllable structure

10. Envelope: Importance of Rise Times

11. Spectro-Temporal Profile (STeP) Spectrogram+Waveform Spectro-temporal profile (STeP) Spectrogram + Waveform Greenberg et al. (2003) Combination of Cues Important “SEVEN”

12. Amplitude Envelope and Stressed Syllables • Full-spectrum • perspective • “Seven” • unaccented • syllable • accented • syllable • [s] [eh] [vx] [en] • juncture Rise times • [eh] • [en] • [s] • [vx] • mean • duration • Greenberg 2002

13. How Does the Brain Encode Modulation? Language Representations Neuroscience Simple neural coding mechanisms, like oscillation at different rhythmic rates, appear to be critical. Networks Delta: 0.5 – 4 Hz Theta: 4 – 8 Hz Gamma: 20 – 50 Hz Neurons

14. The Brain Samples Information in Different Frequency Bands (Theta, Gamma ..) Speech signal Rapid modulations Gamma networks 20 – 50 Hz Slow modulations Theta networks 4 – 8 Hz “syllables” “phonemes” Binding for speech perception

15. Rise Times Enable Phase Locking? Speech signal Alignment with “edges” in signal Rapid modulations Gamma networks 20 – 50 Hz Slow modulations Theta networks 4 – 8 Hz Phonetics: ba - pa Rhythm Syllables Meter Speech percept Hickok, Poeppel

16. Hamalainen, Rupp et al. – Phase Locking 2 Hz 10 Hz

17. Early language experiences entrain the oscillators? Speech signal Perceptual magnets Infant-directed speech Rapid modulations Gamma networks 20 – 50 Hz Slow modulations Theta networks 4 – 8 Hz Phonetics ba - pa Rhythm Syllables Meter Speech percept

18. Implications for Language Development Prior to Schooling Entraining the oscillators – activities that emphasise rhythms and metrical structure of speech - nursery rhymes - poetry - music and singing - other rhythmic experience – dancing marching playing instruments

19. Link To Phonology: Word Representations in the Brain semantic representation phonological representation motor programme

20. Contribution of Brain Imaging Brain (mental lexicon) Acoustic signal Phonology

21. How does the phonological system develop? Need to understand how basic auditory processing and learning to talk contribute to the development of well-specified phonological representations Phonological Representation

22. What are the Brain Representations of Language like Prior to Reading? semantic representation phonological representation motor programme

23. The Mental Lexicon Age 1 year produce 50 – 100 words Age 6 years produce 6000 words comprehend 14,000 words Developmentally, requires fine-grained representations of similarities and differences in sound

24. Spoken Language Processing Lexicon Phonetics Phonology Acoustics

25. Spoken Language Processing Bottom-Up Lexicon/ Reading Phonetics Phonology Acoustics

26. Spoken Language Processing Top-down Lexicon Phonetics Phonology Acoustics

27. The Development of Phonological Awareness Children gradually become “aware” of sound units within words as they develop their language skills A universal developmental sequence is found across languages

28. Levels of Phonological Awareness Syllable (butterfly, wigwam, soap) Rhyme (onset-rime: str - eet, fl - eet) Phoneme (smallest units of sound that change meaning: cat-pat, cat-cot, cat-cap but pin … spoon)

29. Basic Unit of Speech Processing – The Syllable syllable onset rime phonemes (develop largely via reading)

30. The Development of Phonological Awareness Oddity Task: Bradley & Bryant, 1983 Alliteration: hill, pig, pin Rhyme 1: cot, hat, pot Rhyme 2: sit, pin, win

31. Oddity Task: English, German, Chinese

32. Oddity Task: Dyslexic Children(Bradley & Bryant, 1978)

33. Gains in Reading and Spelling after 2 yrs,Adjusting for Age and I.Q.

34. Predicting Reading Acquisition Brain Language Language play Nursery rhymes Phonology “Auditory Organization” Phonological & orthographic connections Reading

35. Measuring Syllable and Phoneme Awareness e.g., tapping out sounds using a drumstick counting out sounds using plastic tokens Syllable level popsicle 3 taps butter 2 taps soap 1 tap Phoneme level book 3 taps up 2 taps I 1 tap

36. Counting Tasks: Syllable vs Phoneme

37. Rate of Phonemic Development Languages vary in the degree to which letters have a 1:1 mapping to sound Greek Finnish German Italian Spanish Swedish Dutch Icelandic Norwegian French Portuguese Danish English

38. Phoneme counting at end of Grade 1 % correct Greek (Porpodas) 100 Italian (Cossu et al.) 97 Turkish (Durgunoglu & Oney) 94 German (Wimmer et al.) 92 Norwegian (Hoien et al.) 83 French (Demont & Gombert) 61 English (Perfetti et al.: Grade 2) 65

39. Predicting Reading Acquisition Across Languages Brain Language Phonology Syllables Rhymes Phonemes Reading

40. The Development of Phonological Representations • Infancy • - physical changes in signal where languages place • phonetic boundaries • - statistical learning of prototypes and phonotactics • - use of prosodic cues to segment syllables and words • Within first year have proto-lexical representations that encode stress and segmental information

41. The Development of Phonological Representations • Early Childhood • - enormous increase in vocabulary • - pressure for segmental specificity • - syllable structure varies across languages • phonological “neighbourhood density” varies • across languages

42. How Reading Changes the Brain Speech-reading eg, lip shape PHONOLOGICAL REPRESENTATIONS OF WORDS Vocabulary size and rate of expansion Linguistic factors eg, sonority profile (language specific) Speech processing skills (input and output) Rhythmic cues Word frequency/ familiarity/ age of acquisition Phonological neighbourhood density (language specific) Syllable Structure (language specific)

43. Reading and spelling acquisition (phoneme level) Speech-reading eg, lip shape PHONOLOGICAL REPRESENTATIONS OF WORDS chair tray tip Vocabulary size and rate of expansion Linguistic factors eg, sonority profile (language specific) Speech processing skills (input and output) Rhythmic cues? Word frequency/ familiarity/ age of acquisition Phonological neighbourhood density (language specific) Syllable structure (language Specific)

44. Development of Phonological Awareness: Language Universal? Preschool: large units syllables rhymes With schooling: small units phonemes

45. English Monosyllables: Approx. 4000 CV sea 5% CVC cat 43% CVCC desk 21% CCVC trip 15% CCVCC grasp 6% German: 1400 French: 2500

46. Representing Phonemes Varies Across Languages Greek Finnish German Italian Spanish Swedish Dutch Icelandic Norwegian French Portuguese Danish English Languages vary in the degree to which letters have a 1:1 mapping to sound, and this affects how rapidly phonology gets “re-mapped” in the brain

47. EU Study: Word and Nonword Reading (cvc)

48. Rates of development largely explained by spelling transparency across languages E.g., ‘a’ GermanEnglish Hand hand Ball ball Garten garden

49. Rates of Development across Languages - development of phonemic representation slower in less consistent orthographies - development of grapheme-phoneme recoding skills (“sine qua non” of reading acquisition) also slower in less consistent orthographies

50. Educational Neuroscience Importance of understanding how the brain encodes information Importance of understanding how environment shapes the basic encoding Focus on causal mechanisms of development Deeper understanding of development