Abstract
Down syndrome (DS) is the leading cause of intellectual disability and, among other things, it affects cognition,
learning, and adaptive skills. In spite of many significant challenges, most people with DS wish to learn the
skills that will enable the greatest independence possible in their adult lives (Wehmeyer & Metzler, 1995). One
of the greatest barriers to independence for youth with DS is limited reading skills. Although children with DS
can learn to read words, their progress typically stalls at the early grade level when the emphasis on reading
comprehension increases. Their reading skills may never transition from “learning to read to reading to learn”
(Chall, 1967). It is well known that DS is associated with a cognitive-linguistic phenotype of strengths and
weaknesses. Several aspects of this phenotype are directly relevant to reading development, and thus reading
development might be atypical in this population (e.g., strengths in visual memory and vocabulary; weakness
in syntax). The proposed study has two aims – Aim 1 is to determine the key components of reading
comprehension in DS, following the Simple View of Reading model. Based on a sample of 70 children with DS
ages 10-15, the proposed study will determine whether the two major components of reading comprehension –
word identification and language comprehension – both contribute independently to reading comprehension.
The proposed study will go on to test an Extended Simple View which adds three cognitive measures as
potential additional components – verbal working memory, attentional control, and processing speed. Finally,
the proposed study will examine components of word identification (phonological decoding and orthographic
processing) and language comprehension (vocabulary and syntax). Aim 2 is to test the hypothesis that poor
syntax is a key limiting factor in the difficult transition to reading comprehension for children with DS. For this,
40 of the 70 children with DS from Aim 1 (ages 10-15) will be matched with 40 children with non-DS intellectual
disability (ID, ages 10-15; oversampling n = 50 to achieve n = 40 of matched participants) and 40 typically
developing children (ages 6-10; oversampling n = 50 to achieve n = 40 of matched participants) on word
identification ability. It is hypothesized that reading comprehension, along with language comprehension and
syntax, will be especially low in the group with DS and that, among several candidates, syntax will be the
strongest mediator of the relation between group and reading comprehension. Thus, the proposed study will
provide a descriptive breakdown of component (and subcomponent) skills of reading comprehension in DS and
identify the skills (e.g., syntax) that most limit the growth of reading comprehension in DS. Findings from the
study will be helpful in identifying targets for reading intervention for students with DS.