Understanding User Perceptions of Robot's Delay, Voice Quality-Speed Trade-off and GUI during Conversation.

Conversational robots face the practical challenge of providing timely responses to ensure smooth interactions with users. Thus, those who design and implement robots will need to understand how different levels of delay in response may affect users' satisfaction with the conversation, how to balance the trade-off between a robot's quality of voice and response time, and how to design strategies to mitigate possible negative effects of a long delay. Via an online video-prototype study on a service robot with 94 Chinese participants, we find that users could tolerate up to 4s delay but their satisfaction drops at the 8s delay during both information-retrieval conversations and chitchats. We gain an in-depth understanding of users' preference for the trade-off between the voice quality and the response speed, as well as their opinions on possible robot graphic user interface (GUI) design to alleviate negative user experience with response latency.