Embodied conversational agents (ECAs) are autonomous software entities with human-like appearance and communication skills. These agents can take on a number of different roles, for example, as an assistant, tutor, information provider, or customer service agent. They may also simply represent or entertain a user.The precise nature and benefits of different characteristics of ECAs requires careful investigation. Questions range from the function of an eyebrow raise to mechanisms for assessing and improving ECA trustworthiness.This book will help experts and designers in the specification and development of applications incorporating ECAs. Part 1 provides guidelines for evaluation methodologies and the identification of design and evaluation parameters. Part 2 demonstrates the importance of considering the user's perspective and interaction experience. Part 3 addresses issues in fine-tuning design parameters of ECAs and verifying the perceived effect. Finally, in Part 4 lessons learned from a number of application case studies are presented.The book is intended for both ECA researchers in academia and industry, and developers and designers interested in applying the technology.

The Blind Men and the Elephant Revisited.- Embodied Conversational Agents on a Common Ground.- Empirical Evaluation Methodology for Embodied Conversational Agents.- Evaluating Users¿ Reactions to Human-Like Interfaces.- User-Centred Design and Evaluation of Affective Interfaces.- `User as Assessor¿ Approach to Embodied Conversational Agents.- More About Brows.- Evaluation of Multimodal Behaviour of Embodied Agents.- ECA as User Interface Paradigm.- Talking to Digital Fish.- Experimental Evaluation of the Use of ECAs in ecommerce Applications.- What We Can Learn from Avatar-Driven Internet Communities.