Authorship Analysis

Stylometry is the application of the study of linguistic style, usually to written language. It has also been applied successfully to music and to fine-art paintings as well. Argamon, Shlomo, Kevin Burns, and Shlomo Dubnov, eds. The structure of style: algorithmic approaches to understanding manner and meaning. Springer Science & Business Media, 2010. Another conceptualization defines it as the linguistic discipline that evaluates an author's style through the application of statistical analysis to a body of their work.

Stylometry is often used to attribute authorship to anonymous or disputed documents. It has legal as well as academic and literary applications, ranging from the question of the authorship of Shakespeare's works to forensic linguistics and has methodological similarities with the analysis of text readability.

History

Stylometry grew out of earlier techniques of analyzing texts for evidence of authenticity, author identity, and other questions.

The modern practice of the discipline received publicity from the study of authorship problems in English Renaissance drama. Researchers and readers observed that some playwrights of the era had distinctive patterns of language preferences, and attempted to use those patterns to identify authors of uncertain or collaborative works. Early efforts were not always successful: in 1901, one researcher attempted to use John Fletcher's preference for "⁠ ⁠’em", the contractional form of "them", as a marker to distinguish between Fletcher and Philip Massinger in their collaborations—- but he mistakenly employed an edition of Massinger's works in which the editor had expanded all instances of "⁠ ⁠’em" to "them".

The basics of stylometry were established by Polish philosopher Wincenty Lutosławski in ''Principes de stylométrie'' (1890). Lutosławski used this method to develop a chronology of Plato's Dialogues.

The development of computers and their capacities for analyzing large quantities of data enhanced this type of effort by orders of magnitude. The great capacity of computers for data analysis, however, did not guarantee good quality output. During the early 1960s, Rev. A. Q. Morton produced a computer analysis of the fourteen Epistles of the New Testament attributed to St. Paul, which indicated that six different authors had written that body of work. A check of his method, applied to the works of James Joyce, gave the result that '' Ulysses'', Joyce's multi-perspective, multi-style novel, was composed by five separate individuals, none of whom apparently had any part in the crafting of Joyce's first novel, ''A Portrait of the Artist as a Young Man.''

In time, however, and with practice, researchers and scholars have refined their methods, to yield better results. One notable early success was the resolution of disputed authorship of twelve of ''The Federalist Papers'' by Frederick Mosteller and David Wallace.
While there are still questions concerning initial assumptions and methods (and, perhaps, always will be), few now dispute the basic premise that linguistic analysis of written texts can produce valuable information and insight. (Indeed, this was apparent even before the advent of computers: the successful application of a textual/linguistic analysis to the Fletcher canon by Cyrus Hoy and others yielded clear results during the late 1950s and early 1960s.)

Applications

Applications of stylometry include literary studies, historical studies, social studies, information retrieval, and many forensic cases and studies. It can also be applied to computer code and intrinsic plagiarism detection, which is to detect plagiarism based on the writing style changes within the document. Stylometry can also be used to predict whether someone is a native or non native English speaker by their typing speed.

Stylometry as a method is vulnerable to the distortion of text during revision. There is also the case of the author adopting different styles in the course of his career as was demonstrated in the case of Plato, who chose different stylistic policies such as the those adopted for the early and middle dialogues addressing the Socratic problem.

Features

Textual features of interest for authorship attribution are on the one hand computing occurrences of idiosyncratic expressions or constructions (e.g. checking for how the author uses interpunction or how often the author uses agentless passive constructions) and on the other hand similar to those used for readability analysis such as measures of lexical variation and syntactic variation.

Since authors often have preferences for certain topics, research experiments in authorship attribution mostly remove content words such as nouns, adjectives, and verbs from the feature set, only retaining structural elements of the text to avoid overfitting their models to topic rather than author characteristics.

Stylistic features are often computed as averages over a text or over the entire collected works of an author, yielding measures such as average word length or average sentence length. This enables a model to identify authors who have a clear preference for wordy or terse sentences but hides variation: an author with a mix of long and short sentences will have the same average as an author with consistent mid-length sentences. To capture such variation, some experiments use sequences or patterns over observations rather than average observed frequencies, noting e.g. that an author shows a preference for a certain stress or emphasis pattern,

or that an author tends to follow a sequence of long sentences with a short one.

One of the very first approaches to authorship identification, by Mendenhall, can be said to aggregate its observations without averaging them.

More recent authorship attribution models use vector space models to automatically capture what is specific to an author's style, but they also rely on judicious feature engineering for the same reasons as more traditional models.

Current research

Modern stylometry uses computers for statistical analysis, and artificial intelligence and access to the growing corpus of texts available via the Internet. Argamon, Shlomo, Jussi Karlgren, and James G. Shanahan. Stylistic analysis of text for information access. Papers from the workshop held in conjunction with the
28th Annual International ACM Conference on Research and
Development in Information Retrieval, August 13–19, 2005,
Salvador, Bahia, Brazil. Swedish institute of computer science, 2005. Software systems such as Signature (freeware produced by Dr Peter Millican of Oxford University), JGAAP (the Java Graphical Authorship Attribution Program—freeware produced by Dr Patrick Juola of Duquesne University), stylo (an open-source R package for a variety of stylometric analyses, including authorship attribution, developed by Maciej Eder, Jan Rybicki and Mike Kestemont) and Stylene for Dutch (online freeware by Prof Walter Daelemans of University of Antwerp and Dr Véronique Hoste of University of Ghent) make its use increasingly practicable, even for the non-expert.

Academic venues and events

Stylometric methods are used for several academic topics, as an application of linguistics, lexicography, or literary study, in conjunction with natural language processing and machine learning, and applied to plagiarism detection, authorship analysis, or information retrieval.

Forensic linguistics

The International Association of Forensic Linguists (IAFL) organises the Biennial Conference of the International Association of Forensic Linguists (13th edition in 2016 in Porto) and publishes ''The International Journal of Speech, Language and the Law'' with forensic stylistics as one of its central topics.

AAAI

The Association for the Advancement of Artificial Intelligence (AAAI) has hosted several events on subjective and stylistic analysis of text.

PAN

PAN workshops (originally, plagiarism analysis, authorship identification, and near-duplicate detection, later more generally workshop on uncovering plagiarism, authorship, and social software misuse) organised since 2007 mainly in conjunction with information access conferences such as ACM SIGIR, FIRE, and CLEF. PAN formulates shared challenge tasks for plagiarism detection, authorship identification, author gender identification, author profiling, vandalism detection,Potthast, Martin, Benno Stein, and Teresa Holfeld. "Overview of the 1st International Competition on Wikipedia Vandalism Detection." In CLEF (Notebook Papers/LABs/Workshops). 2010. and other related text analysis tasks, many of which hinge on stylometry.

Case studies of interest

* In 1439, Lorenzo Valla showed that the Donation of Constantine was a forgery, an argument based partly on a comparison of the Latin with that used in authentic 4th-century documents.
* In 1952, the Swedish priest Dick Helander was elected bishop of Strängnäs. The campaign was competitive and Helander was accused of writing a series of a hundred-some anonymous libelous letters about other candidates to the electorate of the bishopric of Strängnäs. Helander was first convicted of writing the letters and lost his position as bishop but later partially exonerated. The letters were studied using a number of stylometric measures (and also typewriter characteristics) and the various court cases and further examinations, many contracted by Helander himself during the years until his death in 1978, discussed stylometric method and its value as evidence in some detail.Text processing text analysis and generation – text typology and attribution. Proceedings of Nobel symposium 51 / ed. by Sture Allén Stockholm : Almqvist & Wiksell international 1982 653 pp. Data linguistica; 16 Nobel symposium; 51
* In 1975, after Ronald Reagan had served as governor of California, he began giving weekly radio commentaries syndicated to hundreds of stations. After his personal notes were made public on his 90th birthday in 2001, a study used stylostatistical methods to determine which of those talks were written by him and which were written by various aides.
* In 1996, the stylometric analysis of the controversial, pseudonymously authored book ''Primary Colors,'' performed by Vassar College professor Donald Foster brought the topic to the attention of a wider audience after correctly identifying the author as Joe Klein. (This case was resolved only after a handwriting analysis confirmed the authorship.)
* In 1996, stylometric methods were used to compare the Unabomber manifesto with letters written by one of the suspects, Theodore Kaczynski, which resulted in Theodore's apprehension and later conviction.
* In April 2015, researchers using stylometry techniques identified a play, ''Double Falsehood'', as being the work of William Shakespeare. Researchers analyzed 54 plays by Shakespeare and John Fletcher, and compared average sentence length, studied the use of unusual words and quantified the complexity and psychological valence of their language.
* In 2016, MacDonald P. Jackson, Emeritus Professor of English at the University of Auckland, New Zealand and a Fellow of the Royal Society of New Zealand, who had spent his entire academic career analyzing authorship attribution, wrote a book titled ''Who Wrote "The Night Before Christmas"?: Analyzing the Clement Clarke Moore Vs. Henry Livingston Question'', in which he evaluates the opposing arguments and, for the first time, uses the author-attribution techniques of modern computational stylistics to examine the long-standing controversy. Jackson employs a range of tests and introduces a new one, statistical analysis of phonemes; he concludes that Livingston is the true author of the classic work.
*In 2017, Simon Fuller and James O'Sullivan published a study claiming that bestselling author James Patterson does not do any writing in his apparently co-authored novels. According to O'Sullivan, his collaboration with former U.S. president Bill Clinton, '' The President is Missing'', is an exception to this rule.
* In 2017, a group of linguists, computer scientists, and scholars analysed the authorship of Elena Ferrante. Based on a corpus created at University of Padua containing 150 novels written by 40 authors, they analyzed Ferrante's style based on seven of her novels. They were able to compare her writing style with 39 other novelists using, for example, stylo. The conclusion was the same for all of them: Domenico Starnone is the secret author of Elena Ferrante.
* In 2018, Mark Glickman, a senior lecturer in statistics at Harvard University, worked with Ryan Song, a former statistics student at Harvard, and Jason Brown, a professor at Dalhousie University in Nova Scotia, applying stylometry to find that, most likely, The Beatles' song "In My Life" was composed by John Lennon, but with a 50% chance that Paul McCartney wrote the middle eight.
*In 2019, th
ETSO project: Stylometry applied to the Spanish Golden Age Theater
directed by Álvaro Cuéllar González and Germán Vega García-Luengos (University of Valladolid) managed to gather more than 1200 plays of the Spanish Golden Age. After applying stylometrical analysis, the attribution of ''Mujeres y criados'' to Lope de Vega was ratified, and an authorship problem was detected in ''La monja alférez'', a play attributed to Pérez de Montalbán which, thanks to these analyzes and through historical and philology research, was eventually attributed to Juan Ruiz de Alarcón.
*In 2020, Rachel McCarthy and James O'Sullivan argued that Emily Brontë is the true author of ''Wuthering Heights'', ending speculation by some critics that the novel might have been written by one of her siblings, specifically either