Generating Non-Linear Narratives
Vinay Chilukuri · 2011
Stories play a crucial role in our day-to-day lives. Apart from the entertainment sector, they are also being utilized in different areas of games, education and training. The ability to generate rich stories similar to human authored ones is of significance in story generation research. Along with the content of the story the manner in which it is presented is an important factor in effective storytelling. Though a lot of development happened in automatic story generation, most of it ignored the way in which the story could be presented. This thesis deals with a presentation aspect of the story, the order in which the events could be narrated, in order to make it more engaging than that of the chronological versions generated by many story generation systems. We hypothesize that cognitive engagement is manifested when a narrative is deviated from its chronological order without affecting the ease of comprehension. Narratives with events presented in out of chronology are termed non-linear. From a computational perspective, given n events of a story, the total orderings possible are n!. Generating an order in random would affect the comprehension of the material. We have studied how the comprehension of the viewers was affected upon changing the presentation order of the events, by employing a commercial feature film. Using these experimental results along with previous theory from narrative comprehension, we arrive at an algorithm that generates different presentation orders of a story by assessing the amount of processing load required for processing an order of events. Using the principles of the event-indexing model, a cognitive model of narrative comprehension, a function was devised that calculates the processing load, by taking input, the desired amount of non-linearity that could be imparted into the story. An experimental evaluation is undertaken in order to test the generated narratives by our system, corresponding to the different input levels of non-linearity, in terms of engagement. We have obtained results that, for the story employed, increasing the non-linearity up to a medium level did not produce any change in the difficulty in comprehension and thus contributing to engagement. However, it was observed that higher levels of non-linearity led to a decrease in engagement and that, character inconsistencies present in the story had a negative affect on the engagement of the material.