Affective storytelling based on characters' feelings

Most Interactive Storytelling systems developed to date have followed a task-based approach to story representation, using planning techniques to drive the story by generating a sequence of actions, which essentially "solve" the task to which the story is equated. One major limitation of this approach has been that it fails to incorporate characters' psychology, and as a consequence important aesthetic aspects of the narrative cannot be easily captured by Interactive Storytelling. In this paper, we introduce a new approach to Interactive Storytelling which aims at reconciling narrative actions with the characters' attributed psychology as stated in the narrative. Our long-term goal is to be able to explore Interactive Storytelling for those narrative genres which are based on the characters' psychology rather than solely on their actions. We used as a starting point the formalisation by Flaubert himself of his novel Madame Bovary, which includes a detailed account of character's desires and feelings. We describe a prototype in which characters' behaviour is driven by a real-time search-based planning system applying operators whose content is based on a specific inventory of feelings. Furthermore, the actual pattern of evolution of the character's plan, as measured through the variation of the search heuristic, is used to confer a sense of awareness to the characters, which can be used to generate feelings about its overall situation, from feelings of boredom to hope, despair and helplessness.