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Specific Language Impairment and Dyslexia

Chloë Marshall

Department of Language and Communication Science, City University London

Keynote talk at the Dyslexia Action Summer Conference, 30th June 2011

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Significant difficulties in learning to read and spell, despite:

Significant difficulties in acquiring expressive language and language comprehension, despite:

Adequate exposure to literacy Adequate exposure to language

Normal sensory abilities Normal sensory abilities

Average or above average non-verbal IQ

Average or above average non-verbal IQ

No additional developmental disorder that could explain literacy difficulties

No additional developmental disorder that could explain language difficulties

DyslexiaSpecific Language Impairment (SLI)

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Characteristics of SLI(example from boy aged 8)

SLT: What does your brother Ryan like to eat?CHILD: Pot noodle and chips SLT: And what about you? CHILD: And he’s like crispsSLT: He likes crisps, what about you? CHILD: I just like icecream, not pot noodle. SLT: You don’t like pot noodle? CHILD: I think it’s disgusting. SLT: I agree with you! CHILD: Make me sick. Started to hurting.

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Characteristics of SLI(same child as before)

CHILD: And the girl was thinking to eat the chocolate,making a mess. Suddenly the girl was filled with a mess! And the lady was bit surprise!

SLT: And who is that lady? CHILD: The mum! The lady clean him on his face. SLT: On her face. It’s a girl, isn’t it? CHILD: The girl. SLT: So she cleaned her on her face, that’s

right. What will she do with the clothes? CHILD: Make him dirty. SLT: Well, the girl’s made them dirty so what will

mummy do with the clothes? CHILD: Take them to the wash!

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Some characteristics of SLI

• Errors in:– Syntax– Morphology– Vocabulary– Phonology

• Also found in signed languages

• Affects around 7% of preschool children

• Can persist into adolescence/ adulthood

• Has a genetic component

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Overlap between dyslexia and SLI

McArthur et al (2000): 102 children: SLI (aged 6-9) 110 children: dyslexia (aged 7-14)

50 113 49SLI Dyslexia

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Understanding the overlap

• Challenges:– identified at different ages, by different professionals

• Perhaps SLI turns into dyslexia?

• Many preschool children diagnosed with SLI go on to have dyslexia.

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Bishop and Snowling’s additional deficit model (2004)

dyslexia normal

SLIpoor

comprehenders

phonology-

-

language

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Bishop & Snowling’s model in a different format

Phon. processing deficit Dyslexia Word reading problems

Oral language difficultiesLanguage deficits SLI

Problems: • Not all children with SLI have dyslexia.• Not all children with SLI have phonological deficits

of the type found in dyslexia

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Profile of a child with SLI, but not dyslexia

Boy, aged 12;11 Standard score

Literacy: WORD

single word reading 103

spelling 100

comprehension 72 (-1.87)

Phonology:

PhAB

rhyme 95

spoonerisms 98

rapid naming - digits 94

non-word reading 100

Language

sentence comprehension 88

word comprehension 75 (-1.67)

sentence repetition 65 (-2.33)

test of word-finding 83 (-1.15)

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Additional difficulties:Passive sentences

The man is eaten by the fish

(scored 7/12; actives, 12/12)

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Additional difficulties:Verb inflection

Buzz is stirring his tea. Everyday Buzz stirs his tea. Yesterday Buzz stirred his tea.

Agreement: 16/20Past tense: 12/20

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Study to investigate language, literacy and phonology in SLI and dyslexia

• Funded by ESRC, 2004-2008, at UCL.• Groups of children 8-12 years-old:

– SLI+dyslexia– SLI-only– Dyslexia-only

• Investigating phonological deficits and links to language deficits.

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Comparing children with SLI+dyslexia, SLI-only and dyslexia-only

-2.5

-2

-1.5

-1

-0.5

0

0.5

z-sc

ore SLI + dyslexia

SLI only

Dyslexia only

TROG BPVS CELF-rs TWF

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Comparing children with SLI+dyslexia, SLI-only and dyslexia-only

-3

-2.5

-2

-1.5

-1

-0.5

0

z-sc

ore SLI + dyslexia

SLI only

Dyslexia only

WORDread

WORDspell

WORDcomprehension

PhABnw read

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Phonological impairments in SLI and dyslexia

SLI+Dyslexia SLI-only Dyslexia-only

Age-matched controls

Speech perception

(log)

0.17 0.20 0.30 0.57

Non-worddiscrimination

(%)

73 80 78 90

Non-wordrepetition

(%)

51 68 78 96

Digit span(raw)

9 10 11 16

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How do phonological impairments contribute to language impairments?

Verb morphology: phonological variables account for:

49.7% variance, highly significant

Passive sentence comprehension: phonological variables account for:

11.3%, significantly less than for verb morphology

Contribution of phonology depends on particular grammatical construction. Not all phonology!

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Summary

• Many children with dyslexia have SLI, but not all.

• Many preschool children diagnosed with SLI go on to have dyslexia.

• Children with SLI may, however, have adequate single word reading skills, BUT have difficulties with reading comprehension.

• Children with both SLI+dyslexia often score particularly poorly on language and literacy assessments.

• Poor phonology underlies some of the language impairment in SLI, but is not the whole story.

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Find out more about SLI (SLCN)

• I CAN:

http://www.ican.org.uk/

• Afasic:

http://www.afasicengland.org.uk/

• National year of communication –

Hello campaignhttp://www.thecommunicationtrust.org.uk/hello.aspx