Analyzing Film Adaptation through Narrative Alignment (2023)

Abstract: Novels are often adapted into feature films, but the differences between the two media usually require dropping sections of the source text from the movie script. Here we study this screen adaptation process by constructing narrative alignments using the Smith-Waterman local alignment algorithm coupled with SBERT embedding distance to quantify text similarity between scenes and book units. We use these alignments to perform an automated analysis of 40 adaptations, revealing insights into the screenwriting process concerning (i) faithfulness of adaptation, (ii) importance of dialog, (iii) preservation of narrative order, and (iv) gender representation issues reflective of the Bechdel test.

## introduction book-to-film adaptation plays an important role in film-making. from an artistic point of view, there are many possible ways to craft a movie from any given book, all of which entail changes (addition, deletion, and modification) to the structure of the text. books and films are different forms of media, with different characteristics and goals. novels are generally much longer texts than screenplays, written without the strict time-limits of film. further, film adaptations present the screenplay writers' interpretation of the book, whose intentions are often different from the author of the original text. in this paper, we study which parts of books get excised from the script in their movie adaptations. our technical focus is on methods to identify alignments between each unit (e.g., dialog, set-up of a scene) of a movie script with the paragraphs of the book. however, certain book paragraphs must be left unmatched when appropriate, reflecting sections of the book deleted in the movie adaptation for simplifying or focusing the action. we primarily focus on understanding screenwriter behavior and discovering patterns in the book-to-film adap-tation process. the importance of book-to-film adaptation is evidenced by its economic and cultural impact. @xcite found that books were the basis of more than 50% of the top 20 uk-produced films between 2007-2016. these films grossed £22.5bn globally, accounting for 65% of the global box office gross of the top uk films. recent availability of large-scale book and screenplay data empowers the nlp community to study the screenwriting process. our work opens new lines of research in this domain, providing insight into the thought processes of screenwriters and film producers. the relationship between book source and film script has repeatedly been the subject of research within the nlp community. the degree to which movie adaptations are faithful to the original books was raised by @xcite , who considers two questions: how it can be decided if a movie is faithful to its book, and whether being faithful to its source is a merit for a movie adaptation. there have been many works focusing on analyzing movie adaptations of specific books, such as @xcite and @xcite . with the advent of gpt-3 @xcite and more advanced models, artificial intelligence (ai) systems are increasingly being proposed to automate creative tasks in the entertainment industry. the writers guild of america's historic strike highlighted concerns about ai's use in covered projects -specifically, there was a contention that ai should not be involved in the direct writing or rewriting of literary material, nor should it be utilized as source material @xcite . a book to film script alignment and analysis tool has potential application for both sides of the debate, e.g., by creating training dataset for generative models for rewriting creative materials into different formats and analyzing the differences between materials created by humans the green edges denote alignment with the correct portion of the book, as opposed to the magenta edges. our local alignment methods recognize the split structure of the book much better than global alignment methods like book2movie @xcite , who align only 41.4% of part 2 with the second part of the book, compared to 81.6% with our alignment. we frame the book-to-script problem as a sequence alignment problem, where a book and its movie script are two text sequences. sequence alignment techniques are critically important in bioinformatics, specifically for efficiently aligning genome and protein sequences. in the field of computer vision, some of these algorithms have been adapted for image matching @xcite . pial and skiena (2023) posit that these algorithms have a role to play in the analysis of long texts in nlp too. we adapt their proposed text alignment methods for the book-to-film adaptation domain. the primary mechanism of most sequence alignment algorithms does not change based on the components of the sequence. provided with a definition for similarity (or distance) between individual components, they can be adapted to any domain. our primary contributions 1 include: our alignments identify which portions of the book are excised in the adaptation, providing novel insights into the screenwriting process. the outline of this paper is as follows. we survey work on script analysis and alignment methods in section 2. our alignment methods based on smith-waterman and sbert embeddings are presented in section 3, and the datasets we develop in section 4. the accuracy of our alignment algorithms is established in section 5, before we apply these methods to four aspects of film adaptation in section 6. ## related work the task of aligning the video of a movie with a book has been explored in prior research. @xcite proposed a graph-based approach to align book chapters with corresponding movie scenes, treating the alignment as a shortest path finding problem. @xcite utilized neural sentence embeddings and video-text neural embeddings to compute similarities between movie clips and book sentences. in contrast, our work primarily analyzes the removed and retained parts of the book to gain insights into screenwriter behavior while also performing book-to-film alignment. core to our proposed method is the dynamic programming (dp) algorithm for alignment. dp and the associated dynamic time warping algorithms have been widely applied in various film alignment tasks, including aligning script dialogs with transcript dialogs @xcite , aligning scripts with video for person identification @xcite , action recognition @xcite , and identifying scene order changes in post-production @xcite , aligning plot synopses with video @xcite , and annotating movie videos with script descriptions @xcite . @xcite uses dp to segment novels into parts corresponding to a particular time-of-day. neural machine translation @xcite models create soft alignments between target words and segments of the source text relevant for predicting the target word. the size of the book and film scripts restrict us to directly employ neural models like this. other than translations involving two languages, @xcite proposes using method hp2 hp4 complexity baseline (length) 22.6 3.0 o(c + s) book2movie 59.5 52.5 o(c 2 s log(cs)) greedy + sbert 61.2 51.5 o(mn log(mn)) sw + sbert 85.3 66.2 o(mn log(mn)) doc2vec (le and mikolov, 2014) embeddings for creating monolingual parallel corpus composed of the works of english early modern philosophers and their corresponding simplified versions. additionally, several previous works have addressed different aspects of film scripts, such as genre classification @xcite , estimating content ratings based on the language use @xcite , script summarization @xcite , sentiment analysis @xcite , automated audio description generation @xcite , creating dialog corpora @xcite , creating multimodal treebanks @xcite . @xcite performs subtitle to movie script alignment for creating training dataset for automatic turn segmentation classifier. however, to the best of our knowledge, ours is the first-ever work on automated analysis of book-to-film adaptations on a moderately large scale (40 books). in bioinformatics, sequence alignment has been studied in depth for many decades. accurate but comparatively slower classes of algorithms include the dp algorithms like local alignments by @xcite , global alignments by @xcite , etc. global alignments align the whole sequence using dp, while local alignments try to align locally similar regions. in this work, we use smith-waterman (sw) to produce local alignments, which are subsequently used to construct the final global alignment. heuristic but faster algorithms include @xcite . ## aligning books with film scripts here we describe the smith-waterman algorithm for local sequence alignment, including the similarity metrics we use to compare books and scripts. ## evaluation we evaluate the performance of our alignment algorithm against several baselines and previous work. there are two distinct aspects to be considered in our evaluation: (i) the performance of different text similarity metrics, and (ii) local vs. global alignment approaches such as book2movie @xcite . additionally, we provide qualitative evaluation of our alignments in appendix c. ## analysis of the film adaptation process the economics of the movie industry imposes stronger constraints on the length of scripts than the publishing industry forces on books. our alignments illustrate the relationship between book and script lengths, and running times. the book-script alignment methods we have developed so far enable us to analyze the film adaptation process in several interesting ways. the subsections below will consider four particular tasks, namely: (i) measuring the faithfulness of a film adaptation to its original source, (ii) the influence of dialog on script retention, (iii) the preservation of temporal sequencing in adaptation, and (iv) gender representation decisions in film adaptation. ## conclusion in this paper, we have adapted a local dynamic programming alignment algorithm to efficiently align books and scripts and conducted a proof-of-concept analysis of 40 film adaptations, revealing insights into screenwriters' decision-making from various perspectives. our work demonstrates that alignment methods can be used to identify which parts of books appear in movies, and opens up new research directions regarding how films are adapted from books. future research directions include exploring patterns in screenwriting process that reflect the prevailing zeitgeist and cultural dynamics. by leveraging automated methods, it is possible to investigate how these patterns vary across different time periods, cultures as well as for characters of different genders and ethnicities. one future study would be to create a model that can embed video frames and book text in the same embedding space essentially converting two different media to the same space that can create better metrics to quantify similarity, yielding better alignments using the smith-waterman algorithm. this study can shed light onto how much the auditory and visual analysis strengthens the adaptation analysis process.