Structural adaptation in gesture and speech

Interlocutors are known to repeat the structure of each other's speech and to repeat each other's gestures. Yet would they also repeat the information structure of each other's gestures? And which are we more prone to adapt to: gesture, or speech? This study presented participants with gesture and speech in which manner and path information were either conflated into one gesture/clause, or separated into two gestures/clauses. We found that both the information structure perceived in speech and in gesture influenced the information structure participants produced in their gesturing. However, the information structure perceived in gesture only influenced the structure participants produced in their speech if a less preferred structure was perceived in speech. When the preferred structure was perceived in speech, this structure was (re)produced in speech irrespective of perceived gestures. These results pose a challenge to the development of models of gesture and speech production.