The acquisition of prosodic constraints on derivational morphology in typically developing children and children with...

Aim of this study was to investigate at what age German children master prosodic and morphological constraints in the acquisition of the word formation paradigm -heit/-keit, which is comparable to English -ness, and whether children with Specific Language Impairment (SLI) have difficulties identifying the prosodic cues from the input. Derived words with -heit contain simple bases with final stress and those with -keit have complex bases with a weak final syllable. Three groups of typically developing children (four, six and eight years old) and 18 children with SLI (from 8 to 10 years) had to produce either -heit or -keit derivations in a sentence completion task. The results show that typically developing children mastered these derivations by the age of six only when both prosodic and morphological cues were present, while eight-year-old children performed almost adult-like. In contrast, most children with SLI did not produce systematic responses that follow prosodic and/or morphological constraints. The findings support the assumption that children with SLI are less sensitive to prosodic properties of grammatical forms than typically developing peers.