On Manipulating Nonverbal Interaction Style to Increase Anthropomorphic Computer Character Credibility

This study examined the effectiveness of enhancing humanagent interaction through the use of nonverbal behaviors. A taxonomy is described, which organizes nonverbal behaviors into functional categories and the manner in which they can be embodied (i.e. through gesture, posture, paralanguage, eye contact and facial expression). Prototype computer characters were created according to guidelines extracted from the taxonomy and their efficacy was empirical evaluated. The results indicate that by including trusting nonverbal behaviors, the perceived credibility of a computer character was enhanced, although addition of trusting bodily nonverbal behavior provided little in addition to trusting facial nonverbal behavior. Perhaps more importantly, a character expressing non-trusting nonverbal behaviors was perceived to be the least credible of all characters examined (including a character that expressed no nonverbal behavior). Participants that interacted with this persona perceived the task to be more demanding, made significantly more errors, and rated their interaction less positively and more monotonous than those using trusting personas. They also rated this character to be less likable, accurate, and intelligent. Taken together, the results from this study suggest that there may indeed be benefit to endowing computer characters with nonverbal trusting behaviors, as long as those behaviors are accurately and appropriately portrayed. Such behaviors may lead to a more trusting environment and positive experience for users. Negative character behavior, however, such as non-trusting behavior, may squander the advantages that embodiment brings.