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Abstract

Autonomous, graphically embodied agents are a versatile platform for information presentation and user interaction. This thesis presents ERIC, a homogeneous agent framework that can be configured to provide real-time running commentary on a dynamic environment of many and frequent events. We have focused on knowledge reasoning with a world model, generating and expressing affect, and generating coherent natural language, synchronised with nonverbal modalities. The graphical and TTS output of the agent is provided by commercial systems. ERIC is currently implemented to commentate a simulated horse race and a multiplayer tank combat game. With minimal modification the system is configurable to provide commentary in any continuous dynamically changing environment; for example, it could commentate sports matches and computer games, or play the role of "tourist guide" during a self-guided tour of a city. An elaborate world model is deduced from limited input by an expert system implemented as rules in Jess. Natural language is generated using template-based NLG. Discourse coherence is maintained by requiring semantic relations between the forwardlooking and backward-looking centers of successive utterances. The agent uses a set of causal and belief relations to assign appraisals of emotion-eliciting conditions to facts in the world model based on goals and desires. These appraisals are used to generate an affective state according to the OCC cognitive model of emotions; the agent�s affect is expressed via his lexical choice, gestures and facial expressions. ERIC was designed to be domain-independent, homogeneous, behaviourally complex, reactive and affective. Domain-indepence was evaluated by comparing the effort required to implement the ERIC system with the effort required to re-implement the framework for another domain. Complexity, reactivity and affectivity were assessed by independent experts, whose reviews are presented.