Interpersonal coordination in communication: effects of alignment in multiple modalities on objective and subjective task outcomes.

Introduction: Previous research has shown that during interactions, partners adapt to (imitate, synchronize, complement) each other's behavior: a phenomenon often termed interpersonal coordination (IC). Approaches focusing on shared conceptual space suggested that the presence of synchronous or coordinated behaviors indicates the extent of conceptual alignment and thus, predicts communication success, while dynamical systems theory regards IC emerging from general coupling principles assuming no mechanistic role in the outcome of the interaction. Contrasting these two approaches, we tested whether IC appears in a wide variety of behaviors and how well various forms of IC predict the outcome of the interaction. Methods: Pairs of participants solved a computer-mediated communicative task involving verbal negotiation, while data of head motion, pupil size, and gaze direction were collected, and measures of prosody and structural speech characteristics were extracted from the recorded verbal interactions. Communication success was assessed using objective task performance measures and subjective evaluations from the participants. Results: (1) Interlocutors coordinated multiple aspects of their behavior, (2) some of the objective measures of task performance were predicted by gaze pattern coordination, and (3) some forms of IC were positively, while other forms of IC were negatively associated with the participants' subjective experience of their partner and the interaction. Discussion: The results indicating that interpersonal coordination between interlocutors appears across multiple modalities are fully compatible with dynamical systems theory. On the other hand, the presence of both positive and negative associations between IC and subjective outcomes of the interaction suggests that while a strict form of a theory suggesting that stronger alignment leads to better communication outcome is not supported by the data, it is compatible with an extended version of such a theory that acknowledges the potentially different roles of partners in a joint task situation.