NORTHEASTERN UNIVERSITY DOCTORAL THESIS Automated Structural Analysis of Interactive Narratives Author: Supervisor: Elin Carstensdottir Dr. Magy Seif El-Nasr Committee: Dr. Stacy Marsella Dr. Timothy W. Bickmore Dr. Casper Harteveld Dr. Bryan Loyall (External) A thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy in the Khoury College of Computer Sciences iii Declaration of Authorship I, Elin Carstensdottir, declare that this thesis titled, “Automated Structural Analysis of Interactive Narratives” and the work presented in it are my own. I confirm that: • This work was done wholly or mainly while in candidature for a research de- gree at this University. • Where any part of this thesis has previously been submitted for a degree or any other qualification at this University or any other institution, this has been clearly stated. • Where I have consulted the published work of others, this is always clearly attributed. • Where I have quoted from the work of others, the source is always given. With the exception of such quotations, this thesis is entirely my own work. • I have acknowledged all main sources of help. • Where the thesis is based on work done by myself jointly with others, I have made clear exactly what was done by others and what I have contributed my- self. v NORTHEASTERN UNIVERSITY Abstract Khoury College of Computer Sciences Doctor of Philosophy Automated Structural Analysis of Interactive Narratives by Elin Carstensdottir Interactive narrative is becoming increasingly popular for entertainment, such as video games and interactive TV, as well as high impact domains such as education, training and health. Designing complex storytelling experiences is a considerable challenge, even for experts. Iterative design is a common design method used across academia and industry that relies on repeatedly building and testing scenarios, us- ing various formative evaluation methods. These testing methods, however, require human playtesters, making the process both time-consuming and resource demand- ing. Further, our community has yet to develop a way to communicate, evaluate, and compare interactive narratives. In this dissertation, I present a new model for describing and communicating in- teractive narrative design called Progression Model, which captures the narratives structure from a users’ experience perspective. Further, I present a novel model capturing progression and moment-to-moment interaction in a graph-based repre- sentation called Progression Maps. Moreover, I present a new automated system, called Design Assistant, that develops a graph-based visualization of progression in interactive narratives. Results from various studies show the success of the use of Progression Maps and the automatically generated Design Assistant graphs. Specif- ically, the results show that the models and graphs are suitable for novice designers to communicate about their designs; they are easy to understand and suitable for qualitative and quantitative analysis of interactive narrative design. vii Acknowledgements Completing a PhD is a massive undertaking and possibly one of the hardest, most rewarding challenges I have ever faced. I have been incredibly fortunate to have the wholehearted support of my amazing mentors, colleagues, friends, and staff at Northeastern, and having had the love and support of my friends and family who were there for all of it. I’d like to start by thanking my advisor and mentor Dr. Magy Seif El-Nasr for all of her support, guidance, inspiration, and encouragement throughout my PhD journey at Northeastern. Thank you for inspiring me to go out of my comfort zone, wholeheartedly supporting my need to be self-directed in my work, and encourag- ing me to follow and trust my instincts as a researcher and educator. A big thank you to Dr. Stacy Marsella for all of the encouragement, support and guidance you have given me through the years, as an intern at USC ICT, at Northeastern and as a part of my thesis committee. Thank you Dr. Casper Harteveld for all of the support and col- laboration in relation to StudyCrafter and feedback during the development of the work presented in this thesis, Dr. Timothy Bickmore for asking the right questions and making my work better, and Dr. Bryan Loyall whose suggestions and questions have inspired and encouraged me to look further and wider. I got the best possible introduction to research through working with Dr. Hannes Högni Vilhjálmsson at Reykjavik University during my undergraduate studies. Thank you for introducing me to the exciting world of computational media and games re- search, and for your encouragement and patient support through the years. I have been very fortunate in having been around many incredible current and former faculty and post-docs at Northeastern who have helped me improve my work and supported me in one way or another during my time there. The list is long but I wanted to especially thank Dr. Truong-Huy D. Nguyen, Dr. Gillian Smith, Dr. Seth Cooper, Dr. Alessandro Canossa, Dr. Celia Pearce, and Susan Gold. A massive thank you to Meg Barry and Sarah Gale, who were invaluable and always helpful, and an equally massive thank you to Jane Kokernak for her help with editing this thesis and helping me become a better writer. Thank you to my colleagues in the Computational Media department at UC Santa Cruz who have been incredibly welcoming and supportive as I wrapped up this thesis. To all of my friends in the Playable Innovative Technologies Lab at Northeastern, past and present, you have been an amazing bunch of people to share this journey with. I have been very fortunate to have gotten to experience this with you all. There are so many of you so I apologize if I forgot to include your name here. First, thank you Britton Horn for your friendship, humor and wit, for teaching me how to be sufficiently polite for Texas, and patiently explaining all things America to me. I cannot imagine a better friend and cubicle partner for this crazy time. Thank you So- phie Spatharioti for helping me keep sane, for encouraging my never ending quest viii for quality puns, displaying proper disappointment in sub-par pun quality, and for being an incredible friend. Thank you Erica Kleinman for being a fantastic collab- orator, for the numerous conversations about the contents of this dissertation, your friendship, and quality entertainment material recommendations. Thank you Dan Feng for all of our collaboration and fun conversations through the years. Thank you Nathan Partlan for all of the thoughtful feedback, collaboration, and support you provided in the last stages of finishing this dissertation. Thank you Anurag Sarkar for being a good friend and never failing to cheer me up and make me laugh. Thank you Chaima Jemmali, Sara Bunian, Abdelraman Madkour, Josh Miller, Sabbir Ahmad and the entirety of the GUII lab for many years of fun, inspiration, support, conference shenanigans, and laughter. I have been blessed with amazing friends who provided many distractions, con- versations, and support, and without whom this work would not have been possi- ble. In particular, thank you Ting Huang for being the world’s greatest roommate and an incredible friend. Thank you Sarah, Leni, and Susan for your unwavering friendship, generosity, kindness, and endlessly inspiring fabulousness in all things. Thank you Nada Nadji for keeping me laughing, for keeping me silly, and for drag- ging me outside into the world to have fun and eat good food. Thank you Eva Sigurbjörg, Birna Rún, and Angela Nazarian for being incredible and true friends despite the distance and the time apart, and for always being there. I want to thank all of my amazing family who have always supported and helped me regardless of what I chose to do, and finally, but most importantly, I want to thank my wonderful parents and sister for all of their love and kindness, for their understanding and humor, for giving me strength, and being unrelentingly support- ive in every conceivable way. This dissertation is for you. ix Contents Declaration of Authorship iii Abstractv Acknowledgements vii 1 Introduction1 1.1 Building Player-Centric Interactive Narrative...............3 1.1.1 Lack of a Common Lexicon.....................4 1.1.2 Interactive Narrative Design Abstraction.............4 Design Example: Papers Please...................5 Design Example: The Wolf Among Us...............6 1.1.3 Narrative Progression........................8 1.1.4 Challenges in Interactive Narrative Design............9 1.1.5 Design Methods and Authoring for Interactive Narrative.... 10 Challenges posed by Formative Evaluation Techniques..... 11 Authoring Challenges........................ 12 1.2 Automating Design Support and Analysis for Interactive Narrative.. 14 1.2.1 Automated Design Support in Digital Games........... 14 1.2.2 Narrative Generation......................... 15 1.2.3 Visualization and Automated Playtesting of Digital Games... 15 1.3 Thesis Statement and Research Questions................. 16 1.3.1 Contribution Statement....................... 18 1.4 Chapter Overview.............................. 20 2 Tools and Models for Interactive Narrative 23 2.1 Models of Interactive Narrative Structure................. 24 2.1.1 Graph Based Models......................... 26 2.2 Interactive Narrative Design......................... 27 2.2.1 Interactive Narrative Design Tools................. 30 2.3 Structural Analysis and Player Experience................. 30 2.3.1 Modeling and Analyzing Game Design.............