Investigation of the impact of pedagogical agents ’ conversational formality on learning and engagement in a trialog-based intelligent tutoring system showed that the agents ’ informal discourse yielded higher performance, but elicited higher report of text dif fi culty and mind wandering.
. This study investigated the impact of pedagogical agents ’ conversational formality on learning and engagement in a trialog-based intelligent tutoring system (ITS). Participants ( N = 167) were randomly assigned into one of three conditions to learn summarization strategies with the conversational agents: (1) a formal condition in which both the teacher agent and the student agent spoke with a formal language style, (2) an informal condition in which both agents spoke informally, and (3) a mixed condition in which the teacher agent spoke formally, whereas the student agent spoke informally. Result showed that the agents ’ informal discourse yielded higher performance, but elicited higher report of text dif fi culty and mind wandering. This discourse also caused longer response time and lower arousal. The implications are discussed.