Language disorders in children: What can they tell us about genes and brains?. Dorothy Bishop University of Oxford. Specific language impairment (SLI). Diagnosed in children when language does not follow normal developmental course
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University of Oxford
Thursday, 9 January, 2003, 11:15 GMT
Daily grunt parents hold children back
Not enough talking going on
Parents who do little more than grunt at their children every day are damaging their language development, a literacy expert has said.
Alan Wells, director of the Basic Skills Agency, says parents no longer talk to their children and instead just let them sit in front of the television or computer for hours.
hemorrhage : a
Rates of language/learning difficulties higher in relatives of those with SLI, compared with controls
MZ twins: genetically identical
DZ twins: share 50% of polymorphic genes
Is concordance for disorder higher in MZ than in DZ twins?
Lewis & Thompson, 1992 .86 .48
Bishop et al, 1995 .70 .46
Tomblin & Buckwalter, 1998 .96 .69
Hayiou-Thomas et al, 2005 .36 .33
Bishop & Hayiou-Thomas, 2008 .88 .35
(same sample, criteria of SALT contact)
Evidence for substantial genetic influence on SLI
But lots of questions remain, e.g.:
Hurst et al, 1990; Gopnik, 1990;
Vargha-Khadem et al, 1995
A forkhead-domain gene is mutated
in a severe speech and language disorder
Lai, C. S., Fisher, S. E., Hurst, J. A.,
Vargha-Khadem,F., & Monaco, A.
Molecular evolution of FOXP2, a gene
involved in speech and language
Enard, W., Przeworski, M., Fisher, S. E., Lai, C. S. L.
Wiebe, V., Kitano, T., Monaco, A. P., Paabo, S.
(Watkins et al, 2002)
when no speech is required, e.g.
The elephant pushing the boy is big
e.g. heart disease, diabetes
Gathercole and Baddeley, 1990
Child listens to spoken nonwords and repeats, e.g.
2 syllables: hampent
3 syllables: dopelate
4 syllables: confrantually
5 syllables: pristoractional
near ceiling on
2 syllable nonwords
data from Bishop et al, 1996
quantitative rather than categorical approach
shared environment only
co-twinDeFries-Fulker (DF) analysis
h2g = 1.17
(SE = .319)
To get beyond correlational evidence, can use twin method to test for common origins in different deficits
Bishop et al., 2006
NB test not given to 19 children with unintelligible speech
Residual score: total correct on 3-, 4- and 5-syllable nonsense words predicted from the total of 2-syllable words: gives purer measure of memory
h2g = .84
(95%CI = .58)
test of grammatical morphology
“Here the boy is raking; now he is done.
Tell me what he did”.
Tell me what a
Mann Whitney; z = 5.75, p < .001
Bishop et al., 2006
h2g = .68
(95%CI = .59)
h2g.xy = .32
(95%CI = .71)
Genetic risk 2 inflected)
Genetic risk 1
Conclusions from twin study
MZ twins more similar to each other than DZ, but only within-trait
MZ twins more similar to each other than DZ
phi = .29, p < .001
children with co-occurring deficits
deficits are most likely
to be identified with SLI
phonological STM deficit
Suggests language is a strongly canalised function:
will develop despite variation in underlying cognitive bases
Neither seems true!
Barry, J. G., Yasin, I., & Bishop, D. V. M. (2007). Heritable risk factors associated with language impairments. Genes, Brain and Behavior, 6, 66-76.
NB significant differences maintained when self-report LI excluded
Very different from FOXP2
Two genes on chromosome 16
figures from Dianne Newbury
Caroline Adams & Courtenay Norbury
6 yr old twin testing project
Twins Early Development Study
making prepublication test materials available
Dianne Newbury, Tony Monaco, Simon Fisher
making prepublication genetic results available