Event Extraction in a Plot Advice Agent

Proceedings of the 21st International Conference on Computational Linguistics and 44th Annual Meeting of the ACL, pages 857–864, Sydney, July 2006. c⃝2006 Association for Computational Linguistics Event Extraction in a Plot Advice Agent Harry Halpin School of Informatics University of Edinburgh 2 Buccleuch Place Edinburgh, EH8 9LW Scotland, UK H.Halpin@ed.ac.uk Johanna D. Moore School of Informatics University of Edinburgh 2 Buccleuch Place Edinburgh, EH8 9LW Scotland, UK J.Moore@ed.ac.uk Abstract In this paper we present how the auto- matic extraction of events from text can be used to both classify narrative texts ac- cording to plot quality and produce advice in an interactive learning environment in- tended to help students with story writing. We focus on the story rewriting task, in which an exemplar story is read to the stu- dents and the students rewrite the story in their own words. The system automati- cally extracts events from the raw text, for- malized as a sequence of temporally or- dered predicate-arguments. These events are given to a machine-learner that pro- duces a coarse-grained rating of the story. The results of the machine-learner and the extracted events are then used to generate fine-grained advice for the students. 1 Introduction In this paper we investigate how features of a text discovered via automatic event extraction can be used in both natural language understanding and advice generation in the domain of narrative in- struction. The background application is a fully automated plot analysis agent to improve the writ- ing of students could be used by current nar- rative tutoring systems (Robertson and Wiemer- Hastings, 2002). As shown by participatory de- sign studies, teachers are interested in a plot anal- ysis agent that can give online natural language advice and many students enjoy feedback from an automated agent (Robertson and Cross, 2003). We use automatic event extraction to create a story- independent automated agent that can both ana- lyze the plot of a story and generate appropriate advice. 1.1 The Story Rewriting Task A task used in schools is the story rewriting task, where a story, the exemplar story, is read to the students, and afterwards the story is rewritten by each student, providing a corpus of rewritten sto- ries. This task tests the students ability to both listen and write, while removing from the student the cognitive load needed to generate a new plot. This task is reminiscent of the well-known “War of the Ghosts” experiment used in psychology for studying memory (Bartlett, 1932) and related to work in fields such as summarization (Lemaire et al., 2005) and narration (Halpin et al., 2004). 1.2 Agent Design The goal of the agent is to classify each of the rewritten stories for overall plot quality. This rating can be used to give “coarse-grained” gen- eral advice. The agent should then provide “fine- grained” specific advice to the student on how their plot could be improved. The agent should be able to detect if the story should be re-read or a human teacher summoned to help the …

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