This is what “forensic linguistics” mean in popular parlance. The comparison of texts and the interpretation of their differences/similarities began with the question of Biblical authorship, was used in legal cases in the 18th century, and is now used to identify the authors of ransom notes, manifestos, and abusive or libelous emails or other electronic communications. Also called “stylometrics.”
Perhaps 25% of the cases I handle involve the authorship of anonymous, disputed, or forged documents. The client wants to know who’s writing those nasty, threatening emails or letters. I typically ask the client for writing samples from the suspected author. Sometimes there’s more than one suspect, and I have to decide which of them may be the author of the anonymous document(s).
I don’t use computers or statistics (what do they give you but numbers and probabilities, which still require interpretation?). I analyze the text in the traditional manner, which involves the tools and techniques of the discipline known as “stylistics.”
The following description is taken from an affidavit by Gerald R. McMenamin, one of the leading scholars in the field; the affidavit – from Case 1:10-cv-00569-RJA -LGF Document 50 Filed 06/02/11
As part of his expert witness statement, McMenamin describes the theoretical and practical foundation of the method by which he examined documents and determined that they were not written by Facebook founder Mark Zuckerman. See http://www.nytimes.com/2011/07/24/opinion/sunday/24gray.html, :
These are the principles I apply to my authorship analyses
Principles of stylistic analysis
A forensic linguist must be exquisitely sensitive to nuances of text. Where a synonym exists, the very choice of each word represents a decision on the part of the author. Superimposed upon that is the way toward is spelled, abbreviated or capitalized. Truly, a text is a tangle of choices.
The following are intended to test your potential as a forensic linguist. There are two exercises from Forensic Linguistics: An Introduction to Language, Crime and the Law, by John Olsson (New York: Continuum, 2004).
(1) From page 193:
Note ALL peculiarities in the following text.
(from Forensic Linguistics: Advances in Forensic Stylistics, by Gerald R. McMenamin, CRC Press, 2002).
Q: What is the role of the analyst’s intuition?
A: Intuition is the analyst’s use of his or her own judgment to discover linguistic variation and suggest initial hypotheses to investigate. As a speaker or writer of the language and as a linguist, the analyst uses introspection to start the process of analysis. Lakoff comments, on the use of introspection and informal observation that, “… any procedure is at some point introspective…” (Lakoff, 19705:5). A good discussion of the methodological role of intuition in linguistic research can be found in B. Johnstone, Qualitative Methods in Sociolinguistics, Oxford University Press, New York, 2000.
FAQ’s about forensic linguistics full post
(405 words, estimated 1:37 mins reading time)
Although it employs the methods and concepts of modern linguistics (and sometimes makes use of statistical analysis and computer databases), forensic linguistics is at least 200 years old.
According to Gerald R. McMenamin (Forensic Linguistics: Advances in Forensic Stylistics), “hundreds of studies — in the form of journal articles and books — have been done on style, stylistics, and questioned authorship. German studies of Old Testament authorship date back at least to the middle of the 19th century. In addition, evidence has been presented in multiple court cases, and numerous judicial opinions have been documented based on evidence of forensic stylistics.
“Epithets, like pepper / Give zest to what you write; / And if you strew them sparely, / They whet the appetite: / But if you lay them on too thick, / You spoil the matter quite!”
Lewis Carroll, “Poeta fit, non Nascitur,” 1869
“A good style should show no signs of effort. What is written should seem a happy accident.”
W. Somerset Maugham, “The Summing Up,” 1938
Leave it to a linguist to obsess over the use of a single word…but, well, that’s what we do. I could write an entire article on the appearance and evolution of interjections like Duh! and meh, or new conversation-stoppers like what-ever (pronounced with falling intonation).