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Story Representation in Experience Management

In Chapter nine we suggested that the Experience Manager needs a metadataencoded script that represents the story so that it will know when the simulation is deviating from the path that is planned. Without such a script, the system will allow the participants to have an experience that does not provide all the dramatic moments intended by the writer. In addition, in a simulation based on delivery of media elements, not having such a script would also mean that the participants could very well take actions that called for media elements that do not exist, and so the participants would find themselves facing a blank screen abandoned at the edge of the virtual world.

ELEMENTS OF THE ENCODED SCRIPT

In creating the encoded script for ALTSIM we chose to represent the story as expectations in the minds of the simulation participants, so that each element of action was written as though the participant was thinking about it and deciding whether or not to do it. In our High Noon example in the previous chapter a small series of actions might be as follows:

For an experience-managed simulation, as the actual script is being written, the author of the story must also author this detailed list of perceptions that will form the metadata of the encoded script. One way to understand this is to realize that the author is describing media that he or she believes will have a predictable effect on the participants and their perceptions and actions within the world. If that is the case, then the outcome of the employment of each piece of media can be predicted and described before it occurs, at least as the author intends it to happen.

Matching Events and Predicting Outcomes

The Experience Manager begins with a list of anticipated perceptions and actions as described by the author. As the story progresses this list can be split into two different lists: the list of actions that have already occurred (previous story), and the list of actions that are needed to occur (future story). Because each action within the simulation is somehow being carried out through an interaction with the computer, the Experience Manager knows what participant actions are being taken. So it can create a third list (Evidence of Player Action). It can then match evidence of actual actions taken by the participant to the past actions and the expected actions that the story requires. It can determine which new player actions will make it impossible to tell the future story. When this is the case, the Experience Manager can then employ adaptation responses in order to adjust the story or to move the participant back to the point where he or she must take the action that will allow the story to continue on track.

Employing Adaptation Strategies

If the information in the three lists (Previous Story, Future Story, Player Evidence) is rich enough, it is possible to identify the conditions under which each specific adaptation strategy will work, and, just as it was essential for the writer to create the actual description of the story that the Experience Manager uses, so too it is essential that the writer identify these situations that call for adaptation strategies and the conditions that will work in those situations. Then the writer must define the story adaptation strategies that will be triggered by unexpected user actions.

One thought is that the strategies developed for one simulation story will very often apply to another so that—like stock footage scenes in the movies— the library of story adaptation strategies will grow and grow. That does not mean that such elements may not have to be remade to suit the style of the individual simulations, but as such elements are accumulated they at least will not have to be redefined and reinvented, which is the most difficult part of the task.

Experience Manager Formalisms

According to Dr. Andrew Gordon of University of Southern California, who conceived of this approach to Experience Management and did the primary research on the topic, “The basis of our formal representations of the expectations of player experiences consists of logical formalizations of commonsense psychology.” Dr. Gordon used “first order predicate calculus statements that allowed [him] to refer to the mental states and actions of the participants in a highly structured manner.” And he adds, “Given this formalization of the triggering conditions for a story adaptation strategy, a simple pattern-matching algorithm can be used to determine whether any available strategies are applicable given the current state of the player experience as encoded in the Previous Storyline, Future Storyline and Player Evidence Lists.”

SUMMARY

The Experience Manager needs an encoded script to keep the story on track. Such a script is based on a detailed list of perceptions that the writer creates while writing the narrative of the simulation. The list of perceptions is based on expectations of what will happen and what the player will do at each event in the simulation, and it is written in the first person, as perceived by the player. The Experience Manager uses the list as a predictor of future events and notes evidence of what the player is doing whenever he or she takes action through the simulation computer. When an action will take the story off track the system uses the information in the encoded script and the story adaptation strategies to select and implement a strategy that will get the story back on track.

A detailed technical review of the concepts presented in this chapter, including sample code from the Story Representation System, was created by Dr. Andrew Gordon of the Institute of Creative Technologies at USC and was originally part of a larger paper which was published in the Proceedings of the 2003 Conference on Technologies for Interactive Storytelling and Entertainment at the Zentrum fur Graphische Datenverarbeitung in Darmsdadt, Germany.