The communicative import of gestures: evidence from a comparative analysis of human-human and human-machine interactions

Is communication the primary functional role of gesticulation? We conducted a study in which participants narrated to a presumed computer system, a presumed addressee in another room (via web cam), or an addressee in the same room, who could either see them or not. Participants produced significantly fewer gestures when they thought to be talking to a computer system. Our results show that people narrate differently to a computer system than to a human addressee. Considering the difference in gesticulation, it seems plausible that, in a narrative task, most gestures are produced with a communicative intent.