‘‘Agent’’ has different meanings and definitions in different domains and communities (Les, Cumming, & Finch, 1999). In this study, agent refers to a computer-simulated character, which presents users with human-like characteristics, such as domain competence, emotions, and other personal characteristics. The characteristics can be expressed or displayed in text, graph, icons, voice, animation, multimedia, or virtual reality.

Les, J., Cumming, G., & Finch, S. (1999). Agent systems for diversity in human learning. In Proceedings ofAI-ED 99 World Conference on Artificial Intelligence in Education, Le Mans, France, 13–20.