Proceedings of the Annual Meeting of the Cognitive Science Society

We model the causal links between child language (CL) andchild-directed language (CDL). We take pairs of sequences oflinguistic measurements from a longitudinal study. Each child-mother pair of sequences is considered as an instance of thetrajectory of a high-dimensional dynamical system. We thenuse Multispatial Convergent Cross Mapping to ascertain thedirections of causality between the pairs of sequences, that is,whether the complexity of CL drives that of CDL, the com-plexity of CDL drives that of CL, both, or neither. We find thatchildren are responsive to the amount of speech and the diver-sity of words produced by their mothers, but not vice-versa.However, the syntactic diversities of the children’s utterancesdrive the syntactic diversity of the mothers’ utterances. This isevidence for fine-grained fine-tuning of CDL in response onlyto the syntax of CL.