Abstract

Studies on human-robot interaction as well as on embodied conversational agents have revealed that the use of laughter by agents increases their perceived naturalness and their social presence. However, laughter plays a variety of functions in human interaction, and its effects on communication go beyond those previously investigated in the aforementioned fields. Taking into account that laughter has been shown to improve task performance in human-human interaction, we investigated here whether laughter use by a virtual agent increases task success also in human-machine interaction. A real-estate scenario was considered, in which an agent presented an apartment to an interested client. Both the presence of laughter and the nature of the agent (virtual or human) were varied in the experiment. We operationalized the task success as being the likelihood of participants recommending the apartment, while also examining the perceived rating of the agent. The results of an observer study showed that the use of laughter by a virtual agent results in increased task success, while also confirming previous findings regarding improvements in the social perception of the agent. Our results concerning the task success in the human agent condition were not in line with those of previous studies, most likely due to a reduced naturalness of the used laughter. This makes the findings pertaining to the virtual agent, where benefits were observed by the use of laughter in interaction, even more salient, suggesting that humans are less sensitive to reduced laughter naturalness in that case. We further discuss the need for better laughter integration with speech, as well as its automatic synthesis in order to better take advantage of these findings.