Case marking in German-speaking children with specific language impairment and with phonological impairment.

Identification of children with specific language impairment (SLI, now known as Developmental Language Disorder) remains challenging. Morphosyntax difficulties have been proposed as potential linguistic 'markers' for SLI across a number of languages. This study investigates the existence of such a clinical marker in German-speaking children with SLI, looking in particular at German case marking, and makes comparisons with matched typically developing groups and a group with isolated phonological impairment (PI). A case-control study was completed with 66 pre-school children in four groups (1) SLI, (2) PI, (3) age-matched typically developing children (TD-A) (4) language-matched typically developing children (TD-L). Errors in nominative, accusative and dative marking were analysed from the production of articles in elicitation tasks and spontaneous language samples. The performance of the SLI group was poorer than the TD-A group across all three grammatical cases investigated, but there was little supportive evidence for this being a diagnostic marker. It is, however, suggested that poor case marking may alert clinicians to the need for further linguistic assessment. No significant differences were found between the SLI and PI groups; rather scores for the PI group suggested they fell on a gradient between the SLI TD-A groups. Findings are discussed in relation to the proposed new diagnostic category of developmental language disorder.