Creating written text is a major challenge for children who
experience difficulties with the cognitive processes that underpin
writing (Dockrell, 2009); their texts are shorter, more error prone, and
poorly organized compared to those of typically developing peers of the
same age (Hooper, Swarm, Wakely, de Kruif, & Montgomery, 2002;
McArthur & Graham, 1987). These difficulties often continue to
challenge young people through their school career and beyond (Connelly,
Campbell, MacLean, & Barnes, 2006; Riddick, Farmer, & Sterling,
1997). Establishing the ways in which barriers and mediators interact
over time to influence the production of written text for specific
profiles of learning difficulties is a prerequisite to the development
of theory and evidence-based interventions. Using a longitudinal data
set, we examined the relationships of language, literacy, and nonverbal
ability with the written text production of a cohort of young people
with a history of specific language impairment (SLI) at the end of
compulsory education in the United Kingdom (age 16). Practitioners,
policy makers, and researchers use a range of different terms to
describe this population (see Dockrell, Lindsay, Letchford, & Mackie
2006; see also Tomblin et al., 2003, for primary language disorder).
Moreover, different terms are used in Europe (dysphagia) and North
America (SLI in the United States, dysphagia in parts of Canada). The
population is heterogeneous, with the specific nature of their problems
residing with one or more subcomponents of the language system. We use
the term specific language impairment to reflect the most common usage
in the literature.
Children with SLI experience problems with the acquisition and
processing of oral language skills. The most commonly used core
criterion to identify children with SLI is that their language problems
cannot be explained in terms of other cognitive, neurological, or
perceptual deficits (Leonard, 1998). Language problems are evident by a
protracted rate of language development as well as difficulties with
subcomponents of the language system (Leonard). Measurements that tap
into children's proficiencies with phonological processing,
sentence recall, nonword repetition, and tense marking have all
demonstrated high levels of specificity and sensitivity in
differentiating children with SLI from their typically developing peers
(Conti-Ramsden, Botting, & Faragher, 2001; Ellis Weismer et al.,
2000). Although conventionally identified by discrepancy criteria,
children with SLI are heterogeneous in their profile of language
impairments and in terms of nonverbal ability (Botting, Faragher,
Simkin, Knox, & Conti-Ramsden, 2001). Patterns of performance also
vary over time (Botting, 2005; Conti-Ramsden & Botting, 1999). For
many young people with SLI, difficulties with spoken communication
skills persist into adolescence (Beitchman, Wilson, Brownlie, Waiters,
& Lancee, 1996; Botting et al.; Stothard, Snowling, Bishop,
Chipchase, & Kaplan, 1998) and adulthood (Clegg, Hollis, Mawhood,
& Rutter, 2005; Johnson et al., 1999). Older students continue to
experience difficulties with reduced vocabulary levels (Johnson et al.);
accurate use of verb morphology (Clahsen, Bartke, & Gollner, 1997);
and some syntactic structures (Norbury, Bishop, & Briscoe, 2001).
These linguistic deficits have marked effects on the processing of
written text (Bishop & Snowling, 2004), resulting in difficulties in
both word reading and comprehension (Catts, Fey, Tomblin, & Zhang,
2002; Stothard et al., 1998). As with linguistic performance there is
considerable variability within the population on these measures, only
some of which is explained by language competence and cognitive skills
(Young et al., 2002). Variations in phonological and nonphonological
language skills relate to different patterns of reading behavior (Bishop
& Snowling). Phonological processing skills are closely related to
reading decoding (Castles & Coltheart, 2004) and spelling
(Caravolas, Hulme, & Snowling, 2001), whereas measures of receptive
language have been 