Speaking, fast or slow: how conversational agents’ rate of speech influences user experience

With the development of artificial intelligence technology, users are increasingly inclined to use conversational agents (CAs) as personal assistants. Communication speed has received much attention as a key medium for content, emotion and attitude expression in interpersonal communication. This study investigates the effect of the rate of speech on users’ subjective evaluation of using a CA, as well as users’ rate of speech preferences and their scenario difference. We used a 3 (CAs’ speed: slow, medium, and fast) × 2 (participants' gender: male and female) mixed design with three types of users’ rate of speech and collected data on subjective evaluations, forced choice, and interviews from 25 participants. The results of this study showed that with increasing user rate of speech, users preferred the feedback speed of CAs to increase. Also, the majority of users preferred CAs to respond using medium speed. Gender differences were also found in feedback speed preference. The results of this study can be used to propose a new paradigm in the field of mobile interaction by introducing the theory of communication adaptation to the problem of feedback speed adjustment in conversational agents and exploring the role of speed in mobile interaction.