Gradual development of constructional complexity in German spatial language

In this paper, we assess the developmental trajectories by which children approach adult levels of complexity and informativeness in the linguistically and conceptually challenging domain of spatial language. To this end, we look at three types of spatial relations (localization, spontaneous and caused motion) in spontaneous German child speech (age 2;6 to 2;11 and 4;6 to 4;11), and in elicited Frog Story narratives from German child and adult speakers (3-, 5-, 9-year-olds, and adults. Children are generally sensitive to typological preferences. From early on, their productions reflect target-language-
specific lexicalization patterns. Our analyses show that they still approach adult-like levels of information complexity and density only gradually. This concerns the local complexity (structural repertoire for the conceptual slots figure, verb, path/ground), as also established in previous research, but in particular the global complexity, as investigated in this study. Global complexity measures the structural integration of information, or the combinatorial complexity that surfaces at the utterance level. As predicted by usage-based theories, adult-like degrees of informativeness and information density are
only reached gradually, although the component parts at the local level are available earlier in development.