COMMUNICATION DISABILITIES
Developmental Language Impairment1
Session 1
Course Tutor: James Law
______________________________________________________________
Learning objectives of the session:
 To recognise the form/content and use framework and be able to apply
it to developmental language impairment (DLI)
 To be familiar with the terminology related to developmental language
impairment.
 To be aware of the range of different sub-classifications of DLI –
particularly the issue of specific language impairment (SLI).
 To be familiar with the main questions which have yet to be answered
in the field of DLI – most notably in the fields of early identification,
prevalence and intervention.
Introduction
The vast majority of children acquire language without any difficulty and this
makes it possible to make generalisations about the course and nature of
language development. However, for a sizeable number of children the
process is not straightforward. It is this group which is the subject of these
four lectures. There are a number of terms used for this group of children. On
the one hand we find ostensibly medical terminology “congenital auditory
aphasia” (Vaisse 1866), “congenital auditory imperception” (Worster Drought
1943) or “developmental aphasia” (Ingram and Reid 1956). On the other
hand we find less value laden terminology such as “language delay” or
“language difference” or even “language needs”. In the middle we have terms
such as language disorder and language impairment. Developmental
language impairment serves as an umbrella term for the other categories
which may be differentiated both in terms of degree of difficulty and in terms
of presenting symptoms.
What is developmental language impairment?
A developmental language impairment represents a marked discrepancy
between a child’s language skills and what would be expected for his or her
age. In some cases the impairment is mirrored in that of other skills, such a
motor skills, cognitive skills etc. Such cases are sometimes described as
“general language impairments”. However it is also possible to identify
children who have “specific language impairments”, that is they do not
experience difficulties in areas other than language. The term “primary”
language impairment is used for difficulties with no readily identifiable cause
and the term “secondary” language impairment is used for difficulties where
the child experiences a condition which accounts for the associated language
The emphasis in these sessions with be on “language” rather than “speech” , the latter being covered
in greater detail elsewhere in the course.
1
Developmental Language Impairment – James Law – Course Notes 2001
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difficulty such as general learning difficulties, hearing impairment, cerebral
palsy.
In defining the terminology it is important to recognise that we have to deal
with two central issues.
 The first is how delayed do you have to be to be considered language
impaired – i.e. how do you identify cases in the first place? This is
particularly important when you are trying to identify the right children
in the population as a whole.
 The second is that once you have identified a case how do you
describe the child’s difficulties effectively such that it makes a
difference as to what you do about it? This is particularly important
because language impairments are “heterogeneous” in nature.
Note that this approach presupposes a highly functional approach. It does not
follow that just because you can identify discrepancies between skills that
children necessarily have problems. We are looking for the children who need
support beyond that which is available under the status quo in existing
provision. This can be a particularly problematic area especially for children
who all receive educational services as a matter of course.
The ways that we can describe or assess these children in terms of their
impairment and in terms of the context in which they develop are covered in
more detail in the intervention course running parallel to this course. A most
useful starting point is the Form/Content and Use Framework advocated by
Bloom and Lahey and spelled out clearly by Lahey in Language Disorders and
language Development (1988).
The SLI debate
It has long been recognised that a group of these children appear to have
primary language impairment – ie impairment which occurs separate from
any other difficulties. This is distinct from secondary language impairment
which as the name suggests can be explained because of some other
condition – eg cerebral palsy or general learning difficulty. A primary or
“specific” language impairment is normally defined by exclusion. This means
that:


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Hearing should be within normal limits (at least 25dB between 250 and
6,000hz)
Intelligence should be within normal limits
There should be no obvious neurological symptoms (eg cerebral palsy)
No primary emotional problems
No significant environmental component
See Stark and Tallal (1981) for an application of these criteria which has
remained in the literature.
In essence the term SLI is applied in three different ways.
Developmental Language Impairment – James Law – Course Notes 2001
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1. Language is specifically delayed relative to non-verbal skills (so called
cognitive referencing). This a child who is developmentally delayed but
has verbal skills significantly below other aspects of his or her
development could be said to have specific problems (eg Down Syndrome)
2. Language is specifically delayed relative to “normal” non verbal skills. The
latter are measured on IQ measures. Normal is defined by convention to
be at least one standard deviation below the population mean although
some authors use two standard deviations. In essence it is this group that
commonly is directly towards language units/resource bases.
3. One aspect of language is impaired relative to others. For example a child
with phonological or syntactic impairment may be said to have a specific
delay (relative to other language skills).
Be careful when you encounter the term SLI that you know how it is being
used.
There has been considerable discussion in recent years about whether it is
possible to identify impairment which are truly specific – Does specific
language impairment (SLI) truly exist? See Conti-Ramsden, Donlan and Grove
(1992) for an empirical report on the differing skills of children in a language
unit. There are a great many issues well captured by Leonard (1987) and in
his recent seminal work on SLI (Leonard 1998) and in a recent review by
Plante (1998). See also the recent discussion of the relationship between SLI
and motor impairments (Hill 2001).
What are the arguments for and against a specific deficit?
..
..
..
..
..
What are the common features of SLI?
See Leonard 1997 for an over view and also Chiat 2000.
o Slow rate of lexical acquisition
o Poor verb processing (Conti-Ramsden and Jones 1997)
o Poor grammatical development (especially in the use of inflectional
morphology) (Marchman, Wulfeck and Ellis Weismer (1999),
o Poor performance on non-word repetition tasks (Bishop, North and
Donlan 1996)
o Poor narrative skills
o Poor verbal comprehension skills
o Poor negotiation skills (Brinton, Fujiki and McKee 1998)
Developmental Language Impairment – James Law – Course Notes 2001
3
Classification Systems
Even if we are prepared to accept the concept of SLI clinical experience
indicates that the children with SLI present in all sorts of different ways. This
has led to attempts to “classify” SLI.
The most basic classification systems concern the distinction between
expressive and receptive language skills. It is common to hear children
described as having expressive language impairment or expressive/receptive
language impairment (why no receptive language impairment?). It is also
relatively common to hear a distinction being drawn between language delays
and language disorders. The term “delay” suggests that the child is behind in
their language development but the pattern is consistent with normal
development and there is often an assumption that these children with “catch
up” at a later date. The term delay tends to be used for preschool children.
By contrast the term “language disorder” or “language deviance “has
suggested a more serious condition in which the sequence of language
learning does not follow the normal pattern. The child’s language learning is
effectively abnormal resulting in unusual linguistic forms and an increasingly
distorted pattern of usage. Although this distinction is remains popular in
some circles there is increasing evidence to suggest that they may not be
discrete forms at all (Curtiss et al.1992).
Look at the literature to identify the key syntactic features of language delay
and language disorder.
Once you have got beyond the identification process it is necessary to
establish what type of language impairment the child is experiencing. A
number of classification systems have been described. The most commonly
recognised system is that described by Bishop and Rosenbloom (1987) and
Rapin and Allen (1987) and shown in Bishop’s video film on the same subject.
What are the main characteristics of the following categories of language
impairment?
Developmental Language Impairment – James Law – Course Notes 2001
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RAPIN and ALLEN (1987) Classification system for SLI
Verbal auditory agnosia
Verbal dyspraxia
Phonological-processing deficit syndrome
Phonological-syntactic deficit syndrome
Lexical-syntactic deficit syndrome
Semantic-pragmatic deficit syndrome
The classification system has found support in recent years (Conti-Ramsden
et al 1997).
There are a number of issues around the adoption of classification systems
which must not be ignored. It is likely that the classification systems overlap.
Children probably don’t fit into one category or the other. More importantly
we tend to see what we are most familiar with and many of these
classification system have arisen from studies of quite a narrow range of
children. It is clear that the nature of the impairment is likely to change
across time, probably with the classification systems increasing in specificity
as the child ages. For this reason some people are beginning to see
developmental language impairment in terms of a model of risk and
resilience. There are factors which predispose the child to difficulties such as
a genetic predisposition and others which may optimise their chances of
coping effectively with it. The way in which the impairment manifests itself is
not constant over time. Different cognitive skills come into play at different
Developmental Language Impairment – James Law – Course Notes 2001
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times and these obviously affect the way the child copes with incoming
information and the way in which they communicate with peers.
At the end of this session are you:
o Clear how you can distinguish primary and secondary language
disorder?
o Familiar with the concept of discrepancy criteria?
o Familiar with arguments against discrepancy criteria?
o Aware of the ways in which DLI has been subclassified?
Developmental Language Impairment – James Law – Course Notes 2001
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Reading for session 1:
Bishop D, Rosenbloom L,(1987) Classification of childhood language disorders
in Yule W, Rutter M, (eds) Language Development and Disorders Oxford;
Mackeith Press
Conti-Ramsden G, Donlan C, (1992) Characteristics of children with specific
language impairment attending language units European Journal of Disorders
of Communication 27, 325-343
Conti-Ramsden G, Crutchley A, Botting N, (1997) The extent to which
psychometric tests differentiate subgroups of children with SLI Journal of
Speech Hearing and Language Research 40, 765-367
Curtiss S, Katz W, Tallal P, (1992) Delay versus deviance in the language
acquisition of language impaired children Journal of Speech and Hearing
Research 35, 373-383
Hill EJ, (2001) Non-specific nature of specific language impairment: a review
of the literature with regard to concomitant motor impairments International
Journal of Language and Communication Disorders 36,2,149-171
Leonard L, (1987) Is specific language impairment a useful construct? In
Rosenberg S, Advances in Applied Psycholinguistics vol.1 Cambridge:
Cambridge University Press
Mosciki, e. (1984) The prevalence of `incidence’ is too high. Journal of the
American Speech and Hearing Association 26, 39-40
Plante E, (1998) Criteria for SLI: the Stark and Tallal legacy and beyond
Journal of Speech Language and Hearing Research 41, 951-957
Rapin I, Allen D, (1987) Developmental dysphasia and autism in pre-school
children: Characetristics and subtypes in Proceedings of the First International
Symposium on Specific Speech and Language Disorders London: AFASIC
Stark R, Tallal P, (1981) Selection of children with specific language deficits
Journal of Speech and Hearing Disorders 46, 114-122
Tomblin JB. Records, N. Buckwalter, P. Zhang, X. Smith, E. O’Brien, M. (1997)
Prevalence of Specific Language Impairment in Kindergarten children Journal
of Speech Language and Hearing Research 40, 6 1245
Developmental Language Impairment – James Law – Course Notes 2001
7
COMMUNICATION DISABILITIES
Developmental Language Impairment
Session 2
Course Tutor: James Law
______________________________________________________________
Learning objectives of the session:
 To be familiar with the issue of causation, what procedures we use to
establish causation and how much we know about the causes of
developmental language impairment.
 To be aware of the differences between causes of language
impairment and associated phenomenon (correlations).
 To be familiar with the idea of non linear multi-factorial causation.
Introduction
In the previous session we saw
developmental language impairment
skills. It is now necessary to look at
what is known about them from the
range of phenomenon which have
impairments.
how the population of children with
is described in terms of their language
them more closely and try to tease out
point of view of aetiology and from the
found to be associated with language
Aetiology
There is now some considerable evidence about the inherently constitutional
nature of language impairments. There are various ways of establishing this.
The first is the physical examination of the brains of DLI children. In general
this has relied on procedures for scanning the children’s brains such as
Positron Emission Tomography (PET scans) or Magnetic Resonance Imaging
(MRI) or more recently “functional MRI”. There is some evidence for
symmetries in brain development where asymmetries would be anticipated
(Locke 1994).
One area, which has attracted considerable interest in recent years, is that of
specific molecular genetic markers for DLI or more specifically motor speech
disorders. The most prominent evidence here comes from a single family –
known as the KE family - in West London (Hurst et al. 1990, Tomblin and
Buckwalter 1995, Vargha-Khadem et al. 1998). A particular site has been
identified on the long arm of chromosome 7 (7q31). The search is now on to
replicate this evidence. There are various levels of evidence. They usually
start with co-occurrence within families, go on to twin studies and proceed to
specific chromosome analysis. The co-occurrence evidence has now been
accepted. In recent years there has come considerable supporting evidence
from behaviour genetics, most notably the large scale TEDS study which has
3000 twin pairs (Plomin and Dale 2000). The evidence suggest that MZ
Developmental Language Impairment – James Law – Course Notes 2001
8
(monozygote) twins have much migher level of “concordance” in term of their
language abilities than DZ (dizygote) twins.
What are the implications for clinical practice of the recent
genetic findings?
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The relative high heritability of language indicates that
language is not just a matter of input.
It seems very unlikely that we are looking for a single
gene.In most cases we are talking about “polygenetic
inheritance”.
This may help parents concerned that they have caused
the problems that their child is experiencing.
The environment is clearly important but only within certain
parameters. Are their limits to the impact of intervention?
It looks as if there may be genetic support for early
intervention.
There may be discussion of genetic screens for language
impairment/autism etc. It is not clear at this stage how
these could be implemented.
We also need to be aware of what might be called medical aetiology. A
number of authors have picked out the adverse medical histories of these
children both in terms of constitutional disorders such as epilepsy and what
might be termed environmental factors such as otitis media with effusion. In
the case of certain presentations of epileptic disorders specific speech and
language disorders can follow (eg. Landau Kleffner Syndrome). We also know
that low birth weight may be a contributory factor (Rocissano and Yatchmink
1983). Of particular interest here are “small for dates” babies (Largo and
Howard 1986, Grunau 1990).
There is also evidence that these children have neuro-developmental lags –
that is many aspects of their motor development and co-ordination are also
moderately delayed and that language should be taken within this context
(Bishop and Edmundson 1987 and the peg moving task).
An alternative explanation for language disorders relates to the work of Paula
Tallal in the field of speech perception. In essence the argument runs that
some children have a specific deficit (of constitutional origin) which prevents
them from perceiving the speech input correctly. They process speech more
slowly than other children and this has a dramatic effect on their processing
of continuous speech. This, in turn, has a knock on effect on their ability to
tune into the auditory signal, to pick up the meaning of new words, to extract
saliency out of the speech signal and ultimately to a delayed use of language
which has a cumulative effect on the child’s language development. Tallal and
colleagues argue that this is true of all language impaired children and most
importantly that it is effectively a learned strategy which is reversible.
Developmental Language Impairment – James Law – Course Notes 2001
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Finally there is a distinct difference in the prevalence of speech and language
difficulties in boys relative to girls. This is of the order of 3:1. A propensity for
marked speech and language delays to be more common in males than females
is generally confirmed by the studies reviewed in Law et al. 1998. Gender ratios
derived are 1.25:1 (Randall et al. 1974), 2.26:1 (Stevenson and Richman 1976),
2.30:1 (Burden et al. 1996), 1.25:1 for both speech and language at four years
(Stewart et al. 1986) and 2.3:1 (speech), with 1.2-1.6:1 (language) (Tuomi and
Ivanoff 1977). There are two exceptions to this pattern. One of these is
Beitchman et al. 1986 who found the reverse pattern for Speech only (0.98:1),
Language only (0.98:1) and Speech or language (0.82:1) and a most
unexpected 0.46:1 for the Speech and Language diagnosis. The other is
Tomblin et al. (1997) who suggest that while boys are more likely to present
with specific language impairment, the ratio is nearer equivalence. There are a
number of possible explanations for these figures. The first is suggested by the
design of the Beitchman study which sought to sample and then project the
false negatives back into the original population sample. Of the false negatives,
the majority were girls and in projecting back up to the main sample the
authors projected the gender balance as well as the number of cases. A second
explanation is that the relatively liberal cut-off effectively misses the commonly
observed discrepancy between the genders because those cases found may be
less likely to be true clinical cases and as such may tend to reflect the normal
gender balance in the population. A third explanation and one favoured by
Tomblin and colleagues is that existing data are the result of underreporting of
difficulties in girls, a phenomenon which has also been reported in the literature
related to reading disabilities (Shaywitz, Shaywitz, Fletcher, and Escobar
1990). The fact that the other major cohort study in this area did detect the
predicted imbalance (2:1) adopting the fifth percentile as a cut off suggests that
it may be the cut off which is the determining factor here rather than a high
level of undetected difficulties in girls (Silva 1980). (For the full list of references
consult Law et al. 1998)
What possible explanations might there be for the gender difference?
Factors associated with developmental language impairment
Socio-economic status
Over the class the role played by SES has been the source of considerable
discussion much of it politically motivated. The most recent evidence (Hart
and Risley 1995 Meaningful differences Baltmore: Paul Brookes) presents us
with convincing evidence of the different role of verbal input in different social
groups and the potential impact this may have on very young children’s
language development. This evidence builds on a considerable amount of
evidence derived from the Head Start Programmes in the US in the 1960s and
1970s suggesting that there are all sorts of aspects of the environment which
need to be taken into consideration. Do these difficulties iron themselves out
over the period that the children are in school or do differences in input
translate into impairments? It is important that this issue takes us back to
that of prevalence. Why?
Developmental Language Impairment – James Law – Course Notes 2001
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Alongside the evidence concerning differences in parental input is that of
environmental differences. Mayfield (1983) for example suggested that there
are specific linguistic sequelae attributable to lead pollution. Diet has also be
identified as a possible contributary factor. These factors are clearly SES
related.
Currently in the UK no data is collected about the prevalence of language
delay in different populations. It is not clear that more SLT services are
available where greater disadvantage exists.
Parent/child interaction
Although this area is clearly related to SES (as far as Hart and Risley are
concerned) it has tended to be treated discretely in the literature. Chomsky in
his very early contributions to the debate about language acquisition has
repeatedly argued that the role of input was essentially trivial. Children do not
start speaking in the manner that their parents spoke to them but quickly
generate their own syntactic forms because they were pre-programmed to do
so. At one level they had to receive enough input but the threshold for this
was probably very low. This position lead to decades of discussion about the
precise role of parental (usually maternal) input.
What are the characteristics of that input?
Child directed speech:
 Adult speaks to the here and now
 Limited vocabulary use
 Unnecessary words and unstressed words are omitted
 There are fewer word endings
 Utterances are grammatically simple
 Adult uses utterances which are slightly more grammatically complex
than those with the repertoire of the child
 Utterances are slowly and carefully enunciated
 Utterances are repetitive
Given that language acquisition is universal how universal are these
behaviours? And what does it mean if you do not exhibit them? Is it possible
to inhibit a child’s develop by not using these features?
The linguistic evidence tended to suggest that while there was some evidence
for very specific relationship between what the parent says and the child’s
subsequent output (eg use of auxiliaries) there is little direct relationship
between input and output. Rather child directed speech appears to help to
focus the child on the verbal input in a general way.
Developmental Language Impairment – James Law – Course Notes 2001
11
What happens when children do not receive input at all or where is is actively
negative? You need to be familiar with the cases of Genie and the Kulochova
twins (see Skuse 1988 in Bishop and Mogford and for the story of Genie try
Rymer 1993). For a review of the literature of the relationship between child
abuse and neglect and language development see Law and Conway 1991.
Evidence from the population of language impaired children initially suggested
that parental input for language impaired children was sparse and that the
problem was therefore one of parental input. Wulbert et al. for example
described parents and children “living together in parallel”. This is a powerful
image but does it mean that the parent is ignoring the child or vice versa.
Conti-Ramsden and colleagues have suggested that we should look at the
issue from the other side. Parents follow the level of output of the child. They
respond but they do not initiate if the child is not themselves responsive. This
can lead to a downward spiral where the environment effectively is not
supporting the limited output that the child brings to the interaction.
Hearing
As we saw last session children with severe hearing losses do not tend to be
classified as having developmental language impairment in the same sense as
children with primary language impairments. However even if we exclude
children with identified sensori-neural hearing losses it is still important to be
aware that mild and intermittent conductive hearing losses are in the histories
of many children with language delay. These are usually associated with
coughs, colds and more specifically ear infections in the early years
Does this mean that all children with mild hearing losses are going to have
language delay? Or are we more sensitised to this issue purely because
children with identified hearing losses also have delayed language
development?
Cognitive skills
There is a temptation to assume that if a child has a specific language
impairment he or she will not have any associated non-linguistic cognitive
difficulties. This is a complex issue which was touched on in the last session.
There is a good review of the evidence here in Leonard 1997 (chapter 7).
An area which has attracted particular attention is the role of symbolic play.
This can be seen as a non linguistic activity. Yet there is fairly convincing
evidence that children with language impairments also exhibit immature
symbolic play skills. If so what is the relationship between play and language?
Some have argued that play like language is an essentially symbolic skill and
that the language impairments and poor play skills are both attributable to a
difficulty in symbolic processing.
Another interesting area is that of visual processing. Do children with
language impairments also have difficulties with visual representations? The
evidence seems rather more equivocal but there is some evidence that while
Developmental Language Impairment – James Law – Course Notes 2001
12
language impaired children do not have difficulties with simple visual tasks
they do have difficulties with what are known as complex hierarchical visual
tasks. Are such tasks corollaries of the syntactic tasks that language impaired
children find so difficult? It is also worth noting a line of argument deriving
from the development of language skills in blind children. This evidence has
been very recently reviewed in Perez-Pereira and Conti-Ramsden 1999.
Behaviour
It is commonly reported that children with language impairment also have
behavioural problems. Why might this be?
Three mechanisms are suggested. Speech and language impairments lead to
frustration on the part of the child in turn leading to behavioural difficulties.
Alternatively the behaviour may lead to poor communication skills. Thirdly
they may have a common neuro-developmental delay which affects both
language and behaviour. In general the first and the third of these
explanations are seen as the most likely. With the exception of selective
mutism there is rarely a direct link from behaviour to language, but clearly
this is likely to be a complex interactive process. For example poor interaction
in the first months of life leads to poor attention skills in turn leading to poor
early language skills, each effect having a knock on effect on the way that
others communicate with the child.
Reading
One of the most salient associations is between early language delay and
literacy difficulties. In the most recent large scale study to address this issue
Tomblin and colleagues found that reading and spokne language were
strongly correlated (r=.68). 58% of a group of 164 DLI children were found
to have such difficulties compared with 9% of 417 language normal controls.
Clearly this sort of association has considerable ramifications for those
working with children with reading difficulties in school.
English as an additional language
This will be dealt with in greater detail later in the year. But given the
proportion of people who have English as an additional language in the UK
this is of considerable importance. There is no evidence which suggests that
growing up in an environment with two or more languages commonly being
used by those around you will lead to a clinical level of language difficulty.
Indeed there has been some suggestion that it increases your awareness of
language, your metalinguistic skills, and that this may have a positive knock
on effect on language skills. However it is true that the learning of one
language may affect the learning of another (eg. the cross over of vocabulary
(see Genesee in Mogford and Bishop 1988) and there is often extensive
discussion at a clinical level trying to unpick cause and effect when children
when bilingual children are identified as language impaired.
Developmental Language Impairment – James Law – Course Notes 2001
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Multidimensional models
In the majority of cases aetiology is not likely to be linear – ie. With a simple
one to one correspondence between cause and effect. Instead it is more
appropriate to see the model as multi-factorial with a basic propensity for
language being increased or diminished according to factors in the individual’s
environment. The critical issue here is to build a model of risk and protective
factors. To do this it is essential that the widest range of domains of
information is covered for each individual and that outcomes are tailored to
the needs of the individual.
At the end of this session are you:
 Able to distinguish between causes and correlations?
 Familiar with the concept of aetiology and co-morbidity?
 Familiar with the most important factors common to children with DLI?
Reading for session 2:
Hammer CS, Tomblin JB, Zhang X, Weiss AL, (2001) Relationship between
parenting behaviours and specific language impairment in children
International Journal of Language and Communication Disorders 36, 2, 185207
Hurst JA, Baraitser M, Auger E, Graham F, Norell S, (1990) An extended
family with a dominantly inherited speech disorder Developmental Medicine
and Child Neurology 32, 347-355
Law J, (ed) (1993) The early identification of language impairment London:
Chapman and Hall
Leonard L, (1998) Children with specific language impairment Cambs, Mass:
MIT Press
Locke J, (1994) The gradual emergence of language disorders Journal of
Speech and hearing Research 37, 608-616
Nelson NW, (1993) Childhood language disorders in context: Infancy through
adolescence London: Allyn and Bacon
Perez-Pereira M, Conti-Ramsden G, (1999) Language development and social
interaction in blind children Hove: Psychology Press
Plomin R, Dale P, (2000) Genetics and early language development: A UK
twin study of twins DVM Bishop and L.Leonard (Eds) Speech and Language
impairments in children: Causes, characteristics, Intervention and Outcome
Chichester: Psychological Press
Developmental Language Impairment – James Law – Course Notes 2001
14
Rocissano L, and Yatchmink Y, (1983) Language skills and interactive patterns
in prematurely born toddlers Child Development 54, 1229-1241
Rymer R, (1993) Genie: Escape from a silent childhood London: Michael
Joseph
Tomblin JB, Buckwalter PR, (1994) Studies of genetics of specific language
impairment in Watkins RV Rice ML, Specific Language Impairments in
Children Baltimore: Paul Brookes
Tomblin JB, Zhang X, Buckwalter P, Catts H, (2000) The association of
reading disability, behavioral disorders, and language impairment among
second grade children Journal of Child Psychology and Psychiatry 41, 4 473482
Vargha-Khadem F, Watkins KE, Price CJ, Ashburner J, Alcock K, Connelly A,
Francowiack RSJ, Friston KJ, Pembrey ME, Mishkin M, Gadian DG, Passingham
RE, (1998) Neural basis of an inherited speech and language disorder
Proceedings of the National Academy of Science 95, 12695-12700
Developmental Language Impairment – James Law – Course Notes 2001
15
COMMUNICATION DISABILITIES
Developmental Language Impairment
Session 3
Course Tutor: James Law
______________________________________________________________
Learning objectives of the session:
 To understand about the concept of prevalence
 To understand about the concept of natural history and why it is
important.
 To understand about the known sequence of language impairment
 To understand about the range of interventions used in treating
language impairment.
 To understand about the known impact of language impairment.
 To understand the relationship between the intervention and the
identification process.
Prevalence
How many children have development language impairments? While this may
not seem a very interesting question from the point of view of the individual
speech and language therapist it is a central issue when it comes to
determining who needs intervention. Prevalence refers to the number of
cases in a given population at a given time. It is contrasted with incidence
which corresponds to the number of new cases in a given population. It is
very difficult to establish the incidence of developmental conditions without a
universal method of establishing onset and a criterion for what is considered a
case. Prevalence is conventionally expressed as the proportion or percentage
of cases in a given population at a specified time. Normal rather than clinical
populations are the focus in the present review. Prevalence differs from, but
is often confused with, incidence which refers to the number of new cases
(Moscicki 1984). Cases may move out of the pool from which prevalence is
taken because of a number of mediating factors (such as spontaneous
recovery, intervention or death) but prevalence also depends upon incidence.
Prevalence will rise if incidence exceeds the decrease brought about by these
mediating factors. Prevalence is an important concept for three reasons. It
allows planning of service delivery. It should also allow calculation at an
epidemiological level of the impact of intervention, with a successful
intervention being one that results in a decline in prevalence. It should reflect
current knowledge about a disorder, the parameters being determined but
where the boundaries lies between normality and abnormality and which
cases respond to intervention.
It is possible to establish prevalence in a number of ways – by asking
clinicians, by asking parents, by assessing a whole population. To date this
Developmental Language Impairment – James Law – Course Notes 2001
16
has proved problematic because we do not have a clear idea of which
children will not improve if they are not identified as cases. We still tend to
operate with rules of thumb which are recognised to have clinical validity. The
most comprehensive summary of this literature comes in Law et al. 1998 and
Law et al.2000). In this case the median figure reported was 5.95%. This is in
line with most authorities which tend to agree that somewhere between 5
and 10% of children have low language scores which make them vulnerable
to persistent speech/language and other difficulties. But note that some
authors refer to much higher figures and some much lower figures. The figure
currently most commonly reported in the US comes from Tomblin, Records,
Buckwalter, Zhang, Smith and O’Brien (1997).
What is the impact of developmental language impairment?
For a long time it was assumed that DLI was essentially a transitory
phenomenon. Parents were told that children would simply “grow out of it”.
In the last few years it has become apparent that this is not the case.
What sort of evidence would you need to address this issue?
Look at the following list and indicate where the bias might lie in interpreting
this evidence.







The reports of parents.
The reports of children (provided retrospectively).
The reports of speech and language therapists
The reports of classroom teachers
Studies following children who have attended specialist language
provision.
Studies following complete clinic caseloads
Studies of whole populations.
At one level it is useful to ask parents. They might be said to provide the
most valid judgement of their child’s abilities. The AFASIC Parent’s survey
entitled Alone and Anxious (1993) gives you a clear idea of how frustrated
parents feel both in communicating with the child and in fighting for services.
They are clearly very acutely aware of the identification and labelling process.
But does this tell us more about the parents than it does the children?
What we need is a clear indication of what happens to a group of children
who are identified as being language impaired at say 2 or 3 years when they
are followed up into adulthood. These studies are now beginning to fill the
gaps in our knowledge.
Developmental Language Impairment – James Law – Course Notes 2001
17
Following up children in specialist language provision and other
clinical provision.
There are many examples of this. The difficulties which they experience are
associated with a number of antecedents in the health sphere and are linked
to a range of educational outcomes most notably in socialisation and in the
development of literacy (Beitchman et al. 1996, Bishop and Adams 1989,
Fundudis, Kolvin and Garside 1979). For many the prognosis appears to be
relatively good (King et al. 1982) especially for those with expressive
language delays (McRae and Vickar 1991, Whitehurst et al. 1991). But
outcomes appear to be more problematic for the group with more severe
specific language delays. Stothard, Snowling, Bishop, Chipchase and Kaplan
(1998) have suggested that a substantial proportion of children (80%)
originally identified as having specific language impairment which persisted
until 5;6 years were likely to go on to have persistent difficulties to 15 years
and remained at risk of having more general learning difficulties at follow-up.
The focus for a number of the follow-up studies has been children identified
as being in need of intensive intervention in the pre-school period in what are
known in the UK as “language units”. In measuring outcomes two techniques
are commonly used, standardised speech and language tests and educational
placement. Evidence from children identified at primary school age suggests
that the figure for those that are reintegrated into mainstream provision may
be high - of the order of 80% (Bruges 1988, Stone 1992) and this is likely to
reflect the severity of the initial difficulties and the age of the children. For
example only 52% of children from a residential provision for children with
severe specific language impairment returned to mainstream once they left
junior school (Haynes and Naidoo 1991). The increased emphasis on
integration has meant that there is a need to investigate this issue further, to
move towards identifying what are the real strengths of the specialised
language unit environment for these children and what the differences may
be between those children who cope well in one environment relative to
another. For example there is some evidence that those who stay in language
units differ from those that moved to mainstream school in achieving
significantly lower intelligence and literacy scores (Davison and Howlin 1997).
Davison and Howlin (1997) raise the interesting question of the extent to
which associated difficulties, most notably behaviour problems, also
discriminate in terms of educational placement, the suggestion being that the
lack of support in mainstream is likely to lead to behaviour problems. The
suggestion is, therefore, that placement in mainstream may represent
improvement but does not necessarily reflect normalisation or even an ability
to cope with the educational, social and emotional demands of mainstream
class
Law et al. 1999 followed up a group of language impaired children and found
a proportion to have resolved by the time they were going into secondary
school.
Developmental Language Impairment – James Law – Course Notes 2001
18
But what does it mean to have a developmental language impairment that
has resolved?
There is some suggestion that even children who have apparently improved
have not truly resolved (Joffe, Doyle, and Penn 1996). In particular there is
evidence that children whose difficulties have apparently resolved continue to
have poor phonological processing skills (Stothard et al. 1998).
Natural History
“Natural history” is a specific term used to describe the prognosis of a condition
in the absence of intervention (Gordis 1996). It can be a difficult concept
when it comes to children’s development because, in most cases, children
receive some form of intervention by virtue of entering the education system.
Nonetheless there probably is a distinction to be drawn between intervention
of a generic nature and intervention which is targeted at the child’s specific
difficulties. Natural history is important because the anticipated status of a
putative case allows determination of current status. Thus if two cases are
identified as having comparable levels of skill at time one but it is known that
there is a much greater risk of persistent problems for case one than for case
two, then the relative weighting attributed to case one will be higher. Again
the issue of natural history is dealt with in detail in Law et al. 1998.
At the end of this sessions are you:
o Familiar with the difference between prospective and natural history
studies?
o Aware of the difference between studies looking at population cohorts
and those following up confirmed “cases”?
o Aware of the potential long term impact of DLI?
Developmental Language Impairment – James Law – Course Notes 2001
19
Reading for Session 3:
Aram DH, Nation JE, (1980) Pre-school language disorders and subsequent
language and academic difficulties Journal of Communication Disorders 13,
159-170
Beitchman JH. Wilson B. Brownlie EB, Walters H, Lancee W, (1996) Long
term consistency in speech/language profiles 1: Developmental and Academic
outcomes Journal of American Academy of Child Psychiatry 35:6 804-825.
Bishop DVM, Adams C, (1990) A prospective study of the relationship
between specific language impairment, phonological disorders and reading
retardation Journal of Child Psychology and Psychiatry 31 1027-1050
Bralley R, Stoudt R. (1977) A Five Year Longitudinal Study Of Development
Of Articulation. Language, Speech And Hearing Services In Schools 8(3): 176180.
Bruges A, The outcome of language unit placement: A survey in Avon 1987
Educational Psychology in Practice 4 85-90
Catts H, Kamhi AG, (1999) Language and reading disabilities London: Allyn
and Bacon
Conti-Ramsden G, Botting N, Simkin Z, Knox E, (2001) Follow-up of children
attending infant language units: outcomes at 11 years of age International
Journal of Language and Communication Disorders 36,2,207-211
Davison FM, Howlin P, (1997) A follow-up study of children attending a
primary-age language unit European Journal of Disorders of Communication
32, 19-36
Felsenfeld S, Broen P, McGue M. (1992) A 28-Year Follow-Up Of Adults With A
History Of Moderate Phonological Disorder: Linguistic And Personality Results.
Journal Of Speech And Hearing Research 35: 1114-1125.
Fey M, (1986) Language intervention with young children London: Taylor and
Francis Nye et al. 1987, McClean and Woods Cripe 1997), Law 1997.
Fiedler M, Lenneberg E, Rolfe U, Drorbaugh J. (1971)A Speech Screening
Procedure With Three-Year-Old Children. Pediatrics 48(2):268-276.
Gordis L, (1996) Epidemiology London: WB Saunders
Hall N. (1996) Language And Fluency In Child Language Disorders: Changes
Over Time. Journal Of Fluency Disorders 21:1-32.
Developmental Language Impairment – James Law – Course Notes 2001
20
Haynes C, Naidoo S, (1991) Children with Specific Speech and Language
Impairment. Clinics in Developmental Medicine 119 Oxford: Blackwell
Scientific
Huntley RMC, Holt K, Butterfill A, Latham C, (1988) A follow-up study of a
language intervention programme British Journal of Disorders of
Communication 23 127-140
Hall N, Yamashita T, Aram D. (1993) Relationship Between Language And
Fluency In Children With Developmental Language Disorders. Journal Of
Speech And Hearing Research; 36: 568-579.
Joffe BS, Doyle J, Penn C, (1996) The persisting communication difficulties of
`remediated’ language-impaired children European Journal of Disorders of
Communication 31, 369-386
King RR, Jones C, Lasky E, (1982) In retrospect: A fifteen year follow-up
report of speech-language-disordered children Language, Speech and Hearing
Services in Schools 13, 24-32
Law J, Boyle J, Harris F, Harkness A, Nye C, (1998) Screening for speech and
language delay: a systematic review of the literature Health Technology
Assessment 2, (9)
Law J, Boyle J, Harris F, Harkness A, Nye C, (2000) Prevalence and natural
history of primary speech and language delay: fidnings from a systematic
review of the literature International Journal of Language and Communication
Disorders 35, 2 165-189
Law J, Durkin C, Sargent J, Hanrahan D, (1999) Beyond Early Language Unit
Provision:Linguistic, Developmental And Behavioural Outcomes
Child
Language Teaching and Therapy 15, 2 93-111
McRae KM, Vickar E, (1991) Simple developmental speech delay: a follow-up
study Developmental Medicine and Child Neurology 33, 868-874
Paul R, Cohen D, Caparulo BK, (1983) A longitudinal study of patients with
severe developmental disorders of language learning Journal of American
Academy of Child Psychiatry 22 525-534
Renfrew C, Geary L. (1973) Prediction Of Persisting Speech Deficit. British
Journal Of Disorders Of Communication 8(1): 37-41.
Rescorla L, Schwartz E. (1990) Outcome Of Toddlers With Specific Expressive
Language Delay. Applied Psycholinguistics 11(4):393-407.
Richman N, Stevenson J, Graham P. (1982) Preschool To School: A
Behavioural Study: London: Academic Press,
Developmental Language Impairment – James Law – Course Notes 2001
21
Scarborough H, Dobrich W. (1990) Development Of Children With Early
Language Delay. Journal Of Speech And Hearing Research 33(1):70-83.
Silva P. (1980)The Prevalence, Stability And Significance Of Developmental
Language Delay In Preschool Children. Developmental Medicine And Child
Neurology 22:768-777.
Silva P, Mcgee R, Williams S. (1983) Developmental Language Delay From
Three To Seven Years And Its Significance For Low Intelligence And Reading
Difficulties At Age Seven. Developmental Medicine And Child Neurology
25:783-793.
Silva P, Williams S, Mcgee R. (1987) A Longitudinal Study Of Children With
Developmental Language Delay At Age Three: Later Intelligence, Reading And
Behaviour Problems. Developmental Medicine And Child Neurology 29: 630640.
Stern LM, Connell TM, Lee M, Greenwood G, (1995) The Adelaide pre-school
language unit: results of follow-up Journal of Paediatric Child Health 31 207212
Stevenson J, Richman N. (1976) The Prevalence Of Language Delay In A
Population Of Three-Year-Old Children And Its Association With General
Retardation. Developmental Medicine And Child Neurology 18(4):431-441.
Snowling MJ, Adams JW, Bishop DVM, Stothard SE, (2001) Educational
attainments of school leavers with a preschool history of speech-language
impairment International Journal of Language and Communication Disorders
36 2, 173-185
Stothard SE, Snowling MJ, Bishop DVM, Chipchase BB, Kaplan CA, (1998)
Language impaired pre-schoolers: A follow-up into adolescence Journal of
Speech, Language and Hearing Disorders 41, 407-418
Stone E, (1992) A follow-up study of ex-pupils from a speech and language
unit Child, Language Teaching and Therapy 8, 3, 285-313
Thal D, Bates E. (1988) Language And Gesture In Late Talkers. Journal Of
Speech And Hearing Research 31:115-123.
Thal D, Tobias S. (1992) Communicative Gestures In Children With Delayed
Onset Of Oral Expressive Vocabulary. Journal Of Speech And Hearing
Research 35: 1281-1289.
Thal D, Tobias S, Morrison D. (1991) Language And Gesture In Late Talkers:
A One Year Follow-Up. Journal Of Speech And Hearing Research 34: 604-612.
Developmental Language Impairment – James Law – Course Notes 2001
22
Ward S. (1992) The Predictive Validity And Accuracy Of A Screening Test For
Language Delay And Auditory Perceptual Disorder. British Journal Of
Disorders Of Communication 27: 55-72.
Whitehurst GJ, Fischel JE, Lonigan CJ, Valdez-Menchuria MC, Arnold DS,
Smith M, Treatment of early expressive language delay: If, when and how
Topics in Language Disorders 11, 55-68
Developmental Language Impairment – James Law – Course Notes 2001
23
COMMUNICATION DISABILITIES
Developmental Language Impairment
Session 4
Course Tutor: James Law
______________________________________________________________
Intervention
The details of how intervention is provided in your intervention course.
However an important component of our understanding of communication
disabilities is what is known about effective intervention.
There are a number of questions which we need to address about
intervention:
Does it work and if so how ?

Which children will be affected by it and in what way?.

What is the impact of the individual therapist contributions to the
process?
Some therapists maintain it is something of an unknowable art and that
scientific enquiry has nothing to contribute to the discussion. This is almost
certainly wrong. As the number of good quality studies in the field increases
so does our knowledge of what does or does not work. At the level of the
individual the purpose of intervention is to eliminate the condition or to
reduce its impact. At the level of the population the purpose of intervention is
to reduce the prevalence of developmental language impairment (or whatever
the condition).
What sort of interventions are available? There are a number of different
ways of dividing them up. For example, it is possible to look at those aimed at
younger or older children, those which do or do not involve the parents, those
which are direct (in the sense that they work through the speech and
language therapist) and those which might be termed indirect (in that they
work through a third party – teacher or parent). The different interventions
will be described in further detail in your clinical tutorials and you will develop
a clear understanding once you have honed your clinical experience. The
interesting issue from the point of view of the argument here is “do we know
that intervention can be shown to make a difference”? Effectively can it alter
the course of the natural history?
Developmental Language Impairment – James Law – Course Notes 2001
24
What evidence would we need to address this issue? What would we accept?
In many ways this then becomes an issue of research design. Law et al. 1998
cover it in detail in the most recent summary of the complete world literature
in this field but see also Fey (1986) Nye et al. 1987, McClean and Woods
Cripe 1997), Law 1997.
In summary there is some pretty good evidence that intervention works
better than nothing for some children – most notably children with expressive
language delays. It is clear that intervention needs to be administered by an
SLT when a child has a speech difficulty. When it comes to language difficulty
working with parents appears to be just as useful. We do not yet have
enough evidence to say whether early intervention is better that later
intervention. Of particular interest here is work on a programme called the
WILSTAAR (Ward 1999 International Journal of Language and Communication
Disorders 34, 243-264 and correspondence in the same journal pp 441-447).
Likewise we could not be sure whether there are some groups that we know
SLTs are better at working with that others. We do not know enough about
the role of SLT in groups that are known to be more persistent (i.e. children
with expressive/receptive difficulties, children with autism or children from
low SES backgrounds. Particular important we do not know whether it is more
effective to have SLT providing intervention to school children or whether it
really is more effective to have them integrated in mainstream schools.
In other words there are more unanswered than answered questions but a
start has been made. You will be hearing much more detail about the
procedures used in the Intervention course.
Remember lack of evidence is not the same as negative evidence!
Intervention in education
The interventions referred to above tend to be “clinically” focussed – that is
they tend to be carried out by a specialist speech and language therapist with
individuals or groups of children. The target of the intervention is customarily
the removal of the problem. However once children go into the educational
system this type of intervention may not be recommended because there is
insufficient time or because such interventions do not match up to the aims of
the National Curriculum. Accordingly it is critically important to consider the
role of what might be termed “ecological” interventions set within larger
systems – ie. the classroom. These will be covered in more detail elsewhere
but just as it is important to think of assessment relating to a number of
different levels in the child’s experience so too we must consider more broad
based interventions.
This a major issue for teachers and therapists working together today and it
has thrown up a number of issues which have recently been addressed by the
Speech and Language Therapy Working group set up by the DfEE and the DH
and which will be publishing its report during the current term. This group
also commissioned a research study on the way in which health and
Developmental Language Impairment – James Law – Course Notes 2001
25
education services relate to one another in the provision of services to
children with speech and language needs.
Summary
 Evidence to date suggests that there is a lot of developmental noise in
early language development.
 In part the intervention may serve primarily to reduce that noise.
 Intervention probably results in measurable effects when it is possible
to isolate FORM, CONTENT or USE. The more enmeshed the difficulties
in the three areas are the less likely it will be that focused intervention
will remove a child’s difficulties. In such cases a more systemic model
may be more appropriate but the effects of such models are by
definition more difficult to capture.
 We know least about how to affect the development the most
persistent cases.
 Although we can be sure that intervention can impact on the
individual, it is not clear the extent to which intervention can alter the
course of natural history or effective result in a decline in prevalence.
For many the real benefits are likely to be in the field of tertiary
prevention – preventing the impact of the impairment rather than
removing the impairment altogether.
At the end of this session are you:
o Familiar with the concept of intervention and its objectives?
o Broadly aware of the potential effects of intervention?
o Aware of the problems associated with the design of some studies?
o Aware of the apparent contradiction between good intervention results
and poor prognosis?
o Familiar with some of the differences between clinical and educational
interventions for children with DLI?
Developmental Language Impairment – James Law – Course Notes 2001
26
Reading for Session 4:There are a great many papers around the issue of intervention. Many are
descriptive and while interesting do not give compelling proof of the value of
intervention. The following are chapters/papers that have attempted to
summarise the current position.
Enderby P Emerson J (eds) (1995) Does speech and language therapy work?
Whurr Publishers: London
Glogowska M, Roulstone S, Enderby P, Peters TJ, (2000) Randomised
controlled trial of community based speech and language therapy in preschool
children British Medical Journal 321 923-926 together with Law J, ContiRamsden G, (2000) treating children with speech and impairments: six hours
hours of therapy is not enough British Medical Journal 321 908-909
Law J, (1997) Evaluating intervention for language impaired children: a
review of the literature European Journal of Disorders of Communication 32:
404-412
Law J, Intervention for children with communication difficulties in Law, J,
Parkinson A, Tamnhe R, Communication Difficulties in Childhood Oxford:
Radcliffe Press
Law J, Boyle J, Harris F, Harkness A, Nye C, (1998) Screening for speech and
language delay: a systematic review of the literature Health Technology
Assessment 2, (9)
McLean LK, Woods Cripe JW, (1997) The effectiveness of early intervention
for children with communication disorders. In: Guralnick MJ (ed) The
effectiveness of early intervention Baltmore, Maryland: Paul Brookes
Nye C, Foster SH, Seaman D, (1987) Effectiveness of language intervention
with language/learning disabled children Journal of Speech and Hearing
Research 52, 348-357
Ward S, (1999) An investigation into the effectiveness of an early intervention
method for delayed language development in young children International
Journal of Language and Communication Disorders 34 3 243-265
Developmental Language Impairment – James Law – Course Notes 2001
27