Using Anticipation to Create Believable Behaviour

Abstract

Although anticipation is an important part of creating believ-able behaviour, it has had but a secondary role in the field of life-like characters. In this paper, we show how a simple an-ticipatory mechanism can be used to control the behaviour of a synthetic character implemented as a software agent, with-out disrupting the user’s suspension of disbelief. We describe the emotivector, an anticipatory mechanism coupled with a sensor, that: (1) uses the history of the sensor to anticipate the next sensor state; (2) interprets the mismatch between the prediction and the sensed value, by computing its attention grabbing potential and associating a basic qualitative sensa-tion with the signal; (3) sends its interpretation along with the signal. When a signal from the sensor reaches the process-ing module of the agent, it carries recommendations such as: “you should seriously take this signal into consideration, as it is much better than we had expected ” or “just forget about this one, it is as bad as we predicted”. We delineate several strategies to manage several emotivectors at once and show how one of these strategies (meta-anticipation) transparently introduces the concept of uncertainty. Finally, we describe an experiment in which an emotivector-controlled synthetic character interacts with the user in the context of a word-puzzle game and present the evaluation supporting the ade-quacy of our approach.