Evaluation of Multimodal Behaviour of Embodied Agents

Individuality of Embodied Conversational Agents (ECAs) may depend on both the look of the agent and the way it combines different modalities such as speech and gesture. In this chapter, we describe a study in which male and female users had to listen to three short technical presentations made by ECAs. Three multimodal strategies of ECAs for using arm gestures with speech were compared: redundancy, complementarity, and speech-specialization. These strategies were randomly attributed to different-looking 2D ECAs, in order to test independently the effects of multimodal strategy and ECA’s appearance. The variables we examined were subjective impressions and recall performance. Multimodal strategies proved to influence subjective ratings of quality of explanation, in particular for male users. On the other hand, appearance affected likeability, but also recall performance. These results stress the importance of both multimodal strategy and appearance to ensure pleasantness and effectiveness of presentation ECAs.