In this paper we describe the design of a relational agent interface for handheld computers and the results of a study exploring the effectiveness of different useragent interaction modalities. Four different agent output modalities--text only, static image plus text, animated, and animated plus nonverbal speech--are compared and their impact on the ability of the agent to establish a social bond with the user, the perceived credibility of information delivered, and user acceptance is evaluated. Subjects ranked the two animated versions of the system higher on all measures. Keywords Relational agent; embodied conversational agent; affective computing; social interface; mobile computing; handheld computer, PDA. ACM Classification Keywords H5.2 [Information Interfaces and Presentation]: User Interfaces--Evaluation/methodology, Graphical user interfaces, Interaction styles, Natural language, Theory and methods, Voice I/O.
Timothy W. Bickmore, Daniel Mauer