The impact of vocabulary, grammar and decoding on reading comprehension among children with SLI: a longitudinal study

Predictors of reading comprehension among children with SLI have been rarely studied in Spanish. Even more sparse are longitudinal studies inspecting the evolution of their reading abilities. The aim of the present study is to inspect how decoding, production of grammatical/ungrammatical sentences, production of simple/complex sentences, and vocabulary (measured with two instruments) predict reading comprehension among Spanish-speaking monolingual school-age children with SLI in two grades: 2nd grade and 4th grade. Forty-eight children were recruited for this study, evenly grouped in two conditions: SLI and Typical. Groups were balanced by gender with no differences in months of age. All children were assessed twice: when in 2nd grade and when in 4^th grade. Several multiple regression analyses were conducted. Findings revealed differences in terms of which particular predictors significantly impacted reading comprehension in each group. Vocabulary and syntax complexity are the most consistent predictors of reading performance. Decoding predicted reading comprehension performance only in the observed early stage (2nd grade), becoming non-significant over time. Grammaticality was found to have no impact on reading comprehension in both groups. Reported results suggest that vocabulary and complex syntax solidly predict reading comprehension, while decoding and grammaticality play a minor or even negligible role. Thus, interventions designed to improve reading comprehension among children with SLI might benefit from targeting these two particular dimensions of language.