Effects of speech perception, vocabulary, and articulation skills on morphology and syntax in children with Speech Sound Disorders

Although it has been shown that some children with Speech Sound Disorders (SSD) have difficulties in the area of productive morphosyntax, there has been little investigation into the possible source of these problems. Such research may nevertheless shed some light on theoretical questions of morphosyntactic abilities in children with atypical speech and/or language development, as well as suggest avenues for remediation of language weaknesses. The current study examined possible effects of speech perception, vocabulary, and articulation skills on concurrent syntax and longitudinal morphology in a group of seventy-nine children with SSD. Structural Equation Modelling techniques were used to model the relationships among the variables. The rationales for the models were drawn from the literature on children with SSD and also from studies of children with Specific Language Impairment (SLI). The latter were paid particular attention, as some children with SSD may also have SLI, and as morphosyntactic skills in individuals with SLI have been rigorously investigated. It was found that, of the three models examined, an articulation model, in which links were posited from articulation to syntax and from articulation to morphology, demonstrated good fit. Although some of the limitations in morphology and syntax seen in these children could be accounted for in terms of frank articulation errors, other explanations for the association between articulation and morphosyntax were also considered. One possibility was that speech motor skills and morphosyntax were dependent on similar neural substrates that may have been impaired in some of the participants investigated. A second possibility was that, given a finite set of resources devoted to language production, laboured articulation in the children with SSD bled resources from other areas of speech/language processing, and from expressive morphosyntax in particular. Further research, especially studies examining possible relationships among articulation and receptive and expressive grammar, is needed.