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When does phonological impairment cause literacy problems?

Dorothy BishopExperimental Psychology

University of Oxford

Powerpoint and referenceswill be on my website

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What we have learned today

Phonology is not a single skillPhonology is not a single skill• Segmental vs. higher-level structureSegmental vs. higher-level structure• Input vs. outputInput vs. output• Perception vs. memoryPerception vs. memory

• Hard to disentangle, but people are Hard to disentangle, but people are devising wonderfully ingenious tasksdevising wonderfully ingenious tasks

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Why is phonology important in reading?

Two ways to learn to read a wordTwo ways to learn to read a wordA.A. If word is totally unfamiliar: decode letters If word is totally unfamiliar: decode letters

into sounds to achieve pronunciationinto sounds to achieve pronunciation

/k/+/a/+/m/+//+/l/

CAMEL

/kaml/ /'kaml/

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Phonological skills involved in decoding

Knowledge of mappings from letters to soundsKnowledge of mappings from letters to sounds Distinct representations of phonemesDistinct representations of phonemes Ability to segment syllables into phonemesAbility to segment syllables into phonemes Combine sequence of sounds into syllablesCombine sequence of sounds into syllables Match assembled string to a similar lexical entryMatch assembled string to a similar lexical entry

Learn to do Learn to do this rapidly this rapidly with larger with larger orthographic orthographic unitsunits

/k/+/a/+/m/+//+/l/

CAMEL

/kaml//'kaml/

/k/+/a/+/m/+//+/l/

CAMEL

/kaml//'kaml/

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Why is phonology important in reading?

Another way to learn to read a wordAnother way to learn to read a wordB.B. Incorporate orthographic information in Incorporate orthographic information in

lexical representation of a known wordlexical representation of a known word

/kaml/

lexical representation

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Why is phonology important in reading?

Another way to learn to read a wordAnother way to learn to read a wordB.B. Incorporate orthographic information in Incorporate orthographic information in

lexical representation of a known wordlexical representation of a known word

/'kaml/

CAMELlexical representation

Does not require phonological analysis

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Reading without decoding

Patient PS, L hem. infarct aged late 40s– Phonemic errors on reading aloud and

spontaneous speech– Excellent comprehension of written words; can

judge synonyms, define words, match to pictures– Homophones: can only relate to correct meaning,

i.e. cannot respond “inherits” to word “air”– Nonwords: very poor at reading

Hanley, J. R., & Mcdonnell, V. (1997). Are reading and spelling phonologically mediated? Evidence from a patient with a speech production impairment. Cognitive Neuropsychology, 14, 3-33.

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Today’s talk raise questions about causation

Phonological skill

Literacy Syntax

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What has not been discussed

Phonological skill

Literacy

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Phonological deficits in dyslexia: a symptom rather than a cause?

Evidence from:Evidence from:

1.1. Orthographic influences on phonological tasksOrthographic influences on phonological tasks

2.2. Phonological processing in non-literate peoplePhonological processing in non-literate people

3.3. Phonological skills as Phonological skills as predictorspredictors of literacy of literacy

4.4. Literacy in children with sensory or motor conditions affecting Literacy in children with sensory or motor conditions affecting phonologyphonology

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1. Orthographic influences on 1. Orthographic influences on phonological tasksphonological tasks

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Orthographic influences on phonological judgement

Judging whether pictures have rhyming names;Children more accurate if can use orthography

Bishop et al, 1989

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Orthographic influences on phonological judgement

Phoneme awareness: task performance affected by orthography Castles et al, 2003

•Tasks where orthography no help (or may hinder) e.g., take the 'w' from squabble

•cf. transparent conditione.g., take the 'r' from struggle

•Also phoneme reversal: gnat vs mood.

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2. Phonological processing in2. Phonological processing in non-literate people non-literate people

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Phonological processing inPhonological processing in non-literate people non-literate people

• “Illiterates, who lack the linguistic construct ‘phoneme’, cannot perform oral tasks that require the awareness of that construct”

Tarone & Bigelow, 2005, p 82

• Seminal study by Morais et al (1979): Non-literate Portuguese worse than Belgian first-graders at tasks of phoneme deletion/addition; those with some literacy attainments did better

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Comparison of literate vs. nonliterate adults: summary

Do not differ on– Rhyme judgement– Phoneme discrimination– Word repetition– Nonword repetition (short)– Categorical perception*

Do differ on– Phoneme deletion– Phonological fluency– Nonword repetition (long)

* but less precise categorical boundary; Serniclaes et al, 2005See also Kosmidis et al, 2004; Castro-Caldas et al, 1998; de Santos Loureiro et al, 2004

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3. Early phonology measures as predictors of later reading

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Early phonology measures as predictors of later reading

– Bradley and Bryant (1985); famous demonstration that preschool phonological awareness accounted for significant variation in reading outcome after allowing for IQ, vocabulary.

BUT!– “...the sound categorization tests that we gave to the 4-year-old

children were really rather good at picking up those children who would eventually become good readers. The percentage success .. ranged from 40 to 53%. On the other hand, these same tests were very weak indeed at predicting reading failure. The successful rate of prediction of poor readers ranged from as low as 14% to 28%.”

– Bradley & Bryant, p. 105

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Wimmer et al, 1991

At start of grade 1 (children non-readers), good PA predicted good reading 7 mo later, but many with poor PA also did well. Children differ in the ease with which they pick up PA when introduced to literacy.

Positive correlation between preschool phonology and later reading could be consequence of some preschoolers reading (see also Castles and Coltheart, 2004)

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Bishop et al (in press) comparison of pure LI and LI + reading disability (RD)

– Retrospective analysis of measures taken at 4 years. Did not differ on:

Nonverbal ability Vocabulary Oral comprehension Sentence memory Phonological awareness Nonword repetition

NB significantly impaired at 4 yr on all these when compared to control group

LI do not differ from LI+RD at any time

Phonological awareness

0

20

40

60

80

100

1 2

time

% c

orr

ect

TD: N = 84 LI: N = 17 RD+LI: N = 21

time 1 = 4 yrtime 2 = 6 yr

Significant interaction: time x groupLI do not differ from LI+RD at time 1, but do differ at times 2 and 3

4 yr: CNRep 20 items6 yr: CNRep 40 items9 yr: NEPSY

Nonword repetition

60

70

80

90

100

1 2 3

time

scal

ed s

core

TD: N = 84 LI: N = 17 RD+LI: N = 21

time 1 = 4 yrtime 2 = 6 yrtime 3 = 9 yr

LI worse than LI+RD at time 1, but do worse still at time 3

Oromotor

60

70

80

90

100

110

1 3

time

scal

ed s

core

TD: N = 84 LI: N = 17 RD+LI: N = 21

time 1 = 4 yr

time 3 = 9 yr

4 yr: Goldman Fristoearticulation9 yr: NEPSY oromotor

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Differences in phonological processing emerge over time

Nonword repetition and oromotor (articulation): groups diverge with age

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4. Children with sensory or motor problems affecting phonology

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Children with impaired speech production

In general, these do not seem to impair decoding unless accompanied In general, these do not seem to impair decoding unless accompanied by broader language difficulties:by broader language difficulties:

Structural problems – e.g., cleft palate (Stackhouse, 1982)Structural problems – e.g., cleft palate (Stackhouse, 1982) Neurological problems, e.g. cerebral palsy (Bishop & Robson, 1989)Neurological problems, e.g. cerebral palsy (Bishop & Robson, 1989) Problems of unknown (?genetic) origin, - speech sound disorder Problems of unknown (?genetic) origin, - speech sound disorder

(see review by Pennington & Bishop, in press)(see review by Pennington & Bishop, in press)

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Children with impaired phoneme discrimination

Study comparing children with mild-moderate Study comparing children with mild-moderate hearing loss and those with SLIhearing loss and those with SLI

Briscoe et al, 2001Briscoe et al, 2001

Hearing impaired had sensorineural hearing loss Hearing impaired had sensorineural hearing loss from 25 to 65 dB across speech frequenciesfrom 25 to 65 dB across speech frequencies

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Phonological discrimination

Bridgeman & Snowling test

Same/Different judgements re real and nonwords with final s, t, st, or ts

‘Different’ differ either in single segment (e.g. ‘tot’ vs. ‘toss’) or in sequence (e.g. ‘gets’ vs. ‘guest’)

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Phonological discrimination

* *

* significant difference from group CA

Phonological awareness task

(Introducing monster): This is ‘Wug’. He likes things that sound like his name. Which do you think he will choose?The cake, the jug, the leaf or the boat?

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Phonological awareness * *

* significant difference from group CA

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WORD single word reading

131961418N =

CBCASLI-OSLI-YHI

WO

RD

WR

160

140

120

100

80

60

40

54

34

35

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Nonword reading

132061419N =

CBCASLI-OSLI-YHI

NO

NW

DR

D

140

130

120

110

100

90

80

70

60

41

35

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Conclusion re hearing loss

Mild-moderate hearing loss affects phonological discrimination and awareness, and nonword repetition (Briscoe et al)

Yet children with mild-moderate hearing loss do much better than those with SLI on literacy

see also Halliday & Bishop, 2005

Wake et al., 2006

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Questions for discussion

Is phonological deficit a causal deficit in SLI or dyslexia?

Is profile of phonological deficits in SLI/dyslexia the same as that in illiterates?

What are implications for intervention? Do we really understand how a phonological deficit

could cause literacy problems? How important is nonsegmental level for

understanding SLI? Why so little funding for research on these disorders

compared with autism?