Information packaging in speech shapes information packaging in gesture: The role of speech planning units in the coordination of speech-gesture production.

Linguistic encoding influences the gestural manner and path depiction of motion events. Gestures depict manner and path of motion events differently across languages, either conflating or separating manner and path, depending on whether manner and path are linguistically encoded within one clause (e.g., “rolling down”) or multiple clauses (e.g., “descends as it rolls”) respectively. However, it is unclear whether such gestural differences are affected by how speech packages information into planning units or by the way information is lexicalised (as verb plus particle or as two verbs). In two experiments, we manipulated the linguistic encoding of motion events in either one or two planning units while lexicalisation patterns were kept constant (i.e., verb plus particle). It was found that separating manner (verb) and path (particle) into different planning units also increased gestural manner and path separation. Thus, lexicalisation patterns do not drive gestural depiction of motion events. Rather gestures are shaped online by how speakers package information into planning units in speech production.