Recent years have witnessed the birth of a new paradigm for learning environments: animated pedagogical agents. These lifelike autonomous characters cohabit learning environments with students to create rich, face-to-face learning interactions. This opens up exciting new possibilities; for example, agents can demonstrate complex tasks, employ locomotion and gesture to focus students'attention on the most salient aspect of the task at hand, and convey emotional responses to the tutorial situation. Animated pedagogical agents offer great promise for broadening the bandwidth of tutorial communication and increasing learning environments' ability to engage and motivate students. This article sets forth the motivations behind animated pedagogical agents, describes the key capabilities they offer, and discusses the technical issues they raise. The discussion is illustrated with descriptions of a number of animated agents that represent the current state of the art.

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We present a model of dialogue for embodied virtual agents that can communicate with multiple (human and virtual) agents in a multi-modal setting, including face-to-face spoken and nonverbal, as well as radio interaction, spanning multiple conversations in support of an extended complex task.

Only humans communicate using language and carry on conversations with one another. And the skills of conversation have developed in humans in such a way as to exploit all of the unique affordances of the human body. We make complex representational gestures with our prehensile hands, gaze away and towards one another out of the corners of our centrally set eyes, and use the pitch and melody of our voices to emphasize and clarify what we are saying. Perhaps because conversation is so defining of humanness and human interaction, the metaphor of face-to-face conversation has been applied to human-computer interface design for quite some time. One of the early arguments for the utility of this metaphor gave a list of features of face-to-face conversation that could be applied fruitfully to human-computer interaction, including mixed initiative, nonverbal communication, sense of presence, rules for transfer of control (Nickerson 1976). However, although these feature

We are working toward animated agents that can collaborate with human students in virtual worlds. The agent's objective is to help students learn to perform physical, procedural tasks, such as operating and maintaining equipment. Like most of the previous research on task-oriented dialogues, the agent (computer) serves as an expert that can provide guidance to a human novice. Research on such dialogues dates back more than twenty years (Deutsch 1974), and the subject remains an active research area (Allen et al. 1996; Lochbaum 1994; Walker 1996). However, most of that research has focused solely on verbal dialogues, even though the earliest studies clearly showed the ubiquity of nonverbal communication in human task-oriented dialogues (Deutsch 1974). To allow a wider variety of interactions among agents and human students, we use virtual reality (Durlach and Mavor 1995); agents and students cohabit a threedimensional, interactive, simulated mock-up of the student'

: Although avatars may resemble communicative interface agents, they have for the most part not profited from recent research into autonomous embodied conversational systems. In particular, even though avatars function within conversational environments (for example, chat or games), and even though they often resemble humans (with a head, hands, and a body) they are incapable of representing the kinds of knowledge that humans have about how to use the body during communication. Humans, however, do make extensive use of the visual channel for interaction management where many subtle and even involuntary cues are read from stance, gaze and gesture. We argue that the modeling and animation of such fundamental behavior is crucial for the credibility and effectiveness of the virtual interaction in chat. By treating the avatar as a communicative agent, we propose a method to automate the animation of important communicative behavior, deriving from work in conversation and discourse theory. B...

We describe the generation of communicative actions in an implemented embodied conversational agent. Our agent plans each utterance so that mul- tiple communicative goals may be realized opportunistically by a composite action including not only speech but also coverbat gesture that fits the con- text and the ongoing speech in ways representative of natural human conversation. We accomplish this by reasoning from a grammar which describes ges- ture declaratively in terms of its discourse function, semantics and synchrony with speech.

We describe an initial prototype of a holodeck-like environment that we have created for the Mission Rehearsal Exercise Project. The goal of the project is to create an experience learning system where the participants are immersed in an environment where they can encounter the sights, sounds, and circumstances of realworld scenarios. Virtual humans act as characters and coaches in an interactive story with pedagogical goals.

This paper promotes social role awareness as a desirable capability of animated agents, that are by now strong affective reasoners, but otherwise often lack the social competence observed with humans. In particular, humans may easily adjust their behavior depending on their respective role in a socio-organizational setting, whereas their synthetic pendants tend to be driven mostly by attitudes, emotions, and personality. Our main contribution is the incorporation of `social filter programs' to mental models of animated agents. Those programs may qualify an agent's expression of its emotional state by the social context, thereby enhancing the agent's believability as a conversational partner or virtual teammate. Our implemented system is entirely webbased and demonstrates socially aware animated agents in an environment similar to Hayes-Roth's Cybercaf'e. Keywords believability, social agents, human-like qualities of synthetic agents, social dimension in communication, affective reaso...

Prior research into embodied interface agents has found that users like them and find them engaging. In this paper, we argue that embodiment can serve an even stronger function if system designers use actual human conversational protocols in the design of the interface. Communicative behaviors such as salutations and farewells, conversational turn-taking with interruptions, and referring to objects using pointing gestures are examples of protocols that all native speakers of a language already know how to perform and that can thus be leveraged in an intelligent interface. We discuss how these protocols are integrated into Rea, an embodied, multi-modal conversational interface agent who acts as a real-estate salesperson, and we show why embodiment is required for their successful implementation.