Does the phonological deficit in developmental dyslexia extend beyond the segmental level? Catherine Dickie,1 Ann Clark,2 Mits Ota1 1
University of Edinburgh,
2
Queen Margaret University
Speech Prosody in Atypical Populations Monday 2nd April 2007
Phonology in dyslexia
The Phonological Representations Hypothesis
The literacy difficulties seen in dyslexia are caused by underlying poor phonological representations (Snowling 2000, Ramus 2003)
Key evidence comes from phonological awareness tasks
dyslexics are less accurate in phoneme/ syllable counting, phoneme deletion etc (Pennington et al 1990)
Problems with the phonological theory
Phonological awareness tasks measure metaphonological skills, not strictly phonology itself Developmentally, phonological awareness does not appear until the onset of literacy
segmentation skills are enhanced by literacy skills
Everything we know so far about phonology in dyslexia is segmental
there’s more to phonology than segments phonological segments overlap with alphabetic units
Moving beyond the segment 1.
to escape the confound with orthography
2.
is the phoneme manipulation deficit merely a reflection of weak literacy?
to get a fuller understanding of the phonological deficit
is the deficit restricted to segments?
Phonological contrasts
Two kinds of minimal pair Segmental minimal pairs
pat ≠ bat (so /p/ contrasts with /b/) the minimal difference is voicing
Suprasegmental minimal pairs
′toy+factory ≠ toy+′factory ′hot+dog ≠ hot+′dog the minimal difference is stress 1967, Ladd 1984, Vogel & Raimy 2002)
(Jones
Study
Question:
Is there an impairment in the representation of stress in dyslexia?
Tasks Materials Participants Results
Tasks
Compare both phonological domains
ie segmental and suprasegmental
Use four types of task (a)
(b)
Interpretation
Recognition
Pig Latin
Spoonerism
“minimal pairs”
“manipulation”
Materials (a) – Minimal Pairs 1.
Interpretation
Phoneme-based
assigning the correct meaning to a given (auditory) word or phrase, when the choice is between minimal pairs
coat vs goat
Stress-based
′hot+dog vs hot+′dog
Phoneme-based interpretation
Kay et al (1992)
Stress-based interpretation
Pictures © Marion Tallach 2006
2.
Recognition
Phoneme-based
focusing on the phonological form of an auditory word or phrase so as to identify a given contrast
does /s/ occur in fussy or fuzzy?
Stress-based
does “end-stress” occur in ′hot+dog or hot+′dog?
Materials (b) – Manipulations 3.
Pig Latin
Phoneme-based
isolating a phonological unit and moving it around within the word or phrase (Pennington et al 1990)
blanket lanket-bey (not anket-bley, etc)
Stress-based
′ca.len.dar ca.′len.dar-ta (not ′ca.len.dar-ta, etc)
4.
Spoonerisms
Phoneme-based
isolating comparable units in pairs of words and exchanging them
plastic, craggy clastic, praggy
Stress-based
ca.′the.dral, ′bad.min.ton ′ca.the.dral, bad.′min.ton
Participants
Participants were all university students and native speakers of English 21 students with dyslexia
21 students without dyslexia
(7 male, 14 female, mean age 24;2) (7 male, 14 female, mean age 24;1)
matched for gender, age, and regional accent
Results: Minimal Pairs tasks 1.
Interpretation Interpretation task (accuracy)
Interpretation task (response times) 5000
2.00 1.50
dys
1.00
con
0.50 0.00 Phonemic
Stress
Phonological dom ain
Response time (msec)
Accuracy (d')
2.50
4000 3000
dys
2000
con
1000 0 Phonemic
Stress
Phonological dom ain
Main effects for domain; no group effects; interaction in RT
Recognition
2.
Interpretation Recognition task task (response (accuracy) times)
Recognition task (response times)
2.00 4000 1.50 3000
dys dys
1.00 2000
con con
0.50 1000 0.000 Phonemic
Stress Stress
Phonological dom ain
Response time (msec)
Response Accuracy time(d') (msec)
2.50 5000
1800 1600 1400 1200 1000 800 600 400 200 0
dys con
Phonemic
Stress
Phonological dom ain
Main effects for domain; no group effects; no interactions
Results: Manipulation tasks Pig Latin
3.
1800 5000 3.50 1600 3.00 4000 1400 2.50 1200 3000 2.00 1000 800 1.50 2000 600 1.00 400 1000 0.50 200 0.000
2500
dys dys dys con con con
Phonemic
Stress Stress
Phonological dom ain
Pig Latin (response times)
Response time (msec)
Response Accuracy time(d') (msec)
Interpretation Recognition Pig Latin task task task (response (response (accuracy) times) times)
2000 1500
dys
1000
con
500 0 Phonemic
Stress
Phonological dom ain
Main effects for domain; main effects for group; no interactions
Spoonerisms
4.
Spoonerism (response times)
2500 1800 5000 2.50 1600 2000 4000 2.00 1400
2000
1200 1500 3000 1.50 1000 800 1000 2000 1.00 600 400 1000 0.50 500 200 0.000
dys dys con con
Phonemic Phonemic
Stress Stress
Phonological Phonological dom domain ain
Response time (msec)
Response Accuracy time(d') (msec)
Interpretation Recognition Pig Spoonerism Latintask task (response (response (response (accuracy) times) times) times)
1500 dys
1000
con
500 0 Phonemic
Stress
Phonological dom ain
Dys less accurate than Con; no other effects or interactions
Summary of results
Minimal pair tasks:
both groups found the suprasegmental tasks harder no differences between the dyslexics and controls in accuracy or (probably) in response time either
Manipulation tasks:
the controls were more accurate than the dyslexics on all measures suprasegmental version was harder in the pig Latin task (tho not spoonerisms)
How to interpret the results?
The two minimal pairs tasks have a more direct bearing on phonological representations
the dyslexics did not differ from the controls
The two manipulation tasks are much more distant from phonology in the narrow sense
the controls out-performed the dyslexics in both segmental and stress these tasks make heavy metalinguistic and working memory demands
Conclusion
Contribution
direct comparison of segmental and suprasegmental contrasts the dyslexic group shows a deficit in both segments and stress, but only when there are additional manipulation demands
Implications
a reconsideration of the Phonological Representations Hypothesis?
References
Breier, J.I., Gray, L., Fletcher, J.M., Diehl, R.L., Klaas, P., Foorman, B.R., Molis, M.R. (2001) ‘Perception of voice and tone onset time continua in children with dyslexia with and without Attention Deficit/Hyperactivity Disorder.’ Journal of Experimental Child Psychology 80: 345-270 Jones, D. (1967) The Phoneme: Its Nature and Use. Cambridge: Cambridge University Press Kay, J., Lesser, R., Coltheart, M. (1992) PALPA: Psycholinguistic Assessments of Language Processing in Aphasia. Hove: Lawrence Erlbaum Associates Ladd, D.R. (1984), ‘English compound stress.’ In D. Gibbon & H. Richter (eds), Intonation, Accent and Rhythm: Studies in Discourse Phonology. Berlin: W. de Gruyter Mody, M., Studdert-Kennedy, M., Brady, S. (1997), ‘Speech perception deficits in poor readers: auditory processing or phonological coding?’ Journal of Experimental Child Psychology 64: 199-231
Pennington, B.F., van Orden, G.C., Smith, S.D., Green, P.A., Haith, M.M. (1990) ‘Phonological processing skills and deficits in adult dyslexics.’ Child Development 61, 1753-1778 Ramus, F. (2003) ‘Developmental dyslexia: a specific phonological deficit or general sensorimotor dysfunction?’ Current Opinion in Neurobiology 13, 212218 Snowling, M.J. (2000) Dyslexia. Oxford: Blackwell Vogel, I., Raimy, E. (2002) ‘The acquisition of compound vs phrasal stress: the role of prosodic constituents.’ Journal of Child Language 29, 225-250 Wolf, M., O’Rourke, A.G., Gidney, C., Lovett, M., Cirino, P., Morris, R. (2002) ‘The second deficit: an investigation of the independence of phonological and naming-speed deficits in developmental dyslexia.’ Reading and Writing 15, 43-72
