and sentence production and grammar is an extended developmental
Despite the apparent coordination of the two dimensions,
difficulties in relation to form (spelling and handwriting), and content
generation still posed major difficulties for the students in our study.
Texts produced were short with frequent spelling errors. Previous
research has failed to consider writing fluency for students with SLI,
and current data indicate that shorter texts are associated with reduced
levels of handwriting fluency. Indeed, the cohort's handwriting
fluency was equivalent to the average obtained for students some 7 years
younger (Graham et al., 1998). This is consistent with slow production
of text, as evidenced by words produced per minute. The less fluent
students were also more likely to show decreases in their writing
standard scores over time.
Regression analyses revealed that at age 16 the significant
concurrent predictors of text production were spelling and vocabulary.
The importance of vocabulary as a key predictor of text production at
this age extends work with younger students which has identified
limitations in text generation and reduced levels of word use and
lexical diversity (Fey et al., 2004; Scott & Windsor, 2000) and
semantic content (Bishop & Clarkson, 2003) as critical limiting
factors for children with SLI. The continuity of the importance of
vocabulary as a determinant of text quality for this cohort of children
(Dockrell, Lindsay, Palikara, et al., 2007) adds further weight to the
view that vocabulary provides a building block for written language.
The poor spelling skills of the participants were evident both in
their written text productions and when assessing their single word
spellings. At age 11, the participants' writing levels were
mediated by their reading levels. The point of fracture has moved, and
on the surface appears similar to difficulties exhibited by young adults
with dyslexia (Connelly et al., 2006), where writing was constrained by
transcription skills (in the form of poor spelling and slow
handwriting). However, the Connelly et al. population was different from
the current cohort in that they could produce compositions that were age
appropriate in terms of ideas and development, sentence structure and
organization, unity, and coherence scales of the WOLD (Wechsler,
1996)--all areas of weakness for the students described here. As shown
by Puranik et al. (2007, with a younger cohort), problems with spelling
and transcription combined with wider problems with language led to very
poor performance in writing.
Given the relationships between the different variables and the
predictions derived from previous studies, we used path analysis to
provide estimates of the magnitude and significance of hypothesized
causal connections between sets of variables. Our first model explored
the potential interactions between concurrent measures. The best-fit
model included direct effects of vocabulary, spelling, and writing
fluency, with reading fluency (a timed measure of reading decoding)
having an indirect effect through spelling and writing fluency. The
concurrent model confirms both the effects of semantic factors (as
measured by vocabulary) and phonological factors (as measured by
spelling), and suggests an independent contribution of writing fluency.
There has been a longstanding concern about the information
processing constraints experienced by children with SLI (Ellis Weismer
& Hesketh, 1996; Montgomery, 2000), and their reduced performance on
tasks requiring quick and accurate performance (Leonard et al., 2007).
Measures of speed of writing and reading fluency are both significantly
related--either directly or indirectly--to text production. These
deficits may reflect reduced performance in both verbal working memory
(reading fluency) and processing speed (speed of writing; see Leonard et
al.). Yet the highly significant relationship in the current study
between the two (.57) suggests that the underlying factor may be the
ability to coordinate and efficiently manage different information, and
this l