Manipulation of non-verbal interaction style and demographic embodiment to increase anthropomorphic computer character credibility

For years, people have sought more natural means of communicating with their computers. Many have suggested that interaction with a computer should be as easy as interacting with other people, taking advantage of the multimodal nature of human communication. While users should, in theory, gravitate to such anthropomorphic embodiments, quite the contrary has been experienced; users generally have been dissatisfied and abandoned their use. This suggests a disconnect between factors that make human-human communication engaging and those used by designers to support human-agent interaction. This paper discusses a set of empirical studies that attempted to replicate human-human non-verbal behavior. The focus revolved around behaviors that portray a credible façade, thereby helping embodied conversational agents (ECAs) to form a successful cooperative dyad with users. Based on a review of the non-verbal literature, a framework was created that identified trustworthy and credible non-verbal behaviors across five areas and formed design guidelines for character interaction. The design suggestions for those areas emanating from the facial region were experimentally supported but there was no concordant increase in perceived trust when bodily regions (posture, gesture) were added. In addition, in examining the importance of demographic elements in embodiment, it was found that users prefer to interact with characters that match their ethnicity and are young looking. There was no significant preference for gender. The implications of these results, as well as other interesting consequences are discussed.