A critical examination of assumptions underlying the cusum technique of forensic linguistics

Authors

  • Anthony J. Sandford University of Glasgow
  • Joy P. Aked University of Glasgow
  • Linda M. Moxey University of Glasgow
  • James Mullin University of Glasgow

DOI:

https://doi.org/10.1558/ijsll.v1i2.151

Keywords:

Forensic linguistics, cusum technique, language habits, authorship

Abstract

Morton (1991) has suggested that simple language habits may be used to discriminate against cases where writing and transcribed speech has multiple rather than single authorship. Using a variety of materials, the article shows that these claims receive no support, and that his claim that habits within an individual may be the same for writing and for speech is wrong; rather the data conform to well-documented linguistic observations concerning lexical density in speaking and writing. Five of Morton's habit measures are used, and it is found that within-subject variation is as great as between subject variation. Furthermore, ratios indicating habits which underlie the logic of the cusum predict goodness of fit of habit cusums to sentence cusums, and nor whether the author is the same or different. The authors claim Morton's method is nor well-founded, and until proven otherwise should not be entertained any longer as a forensic technique.

Author Biographies

  • Anthony J. Sandford, University of Glasgow
    Anthony Sandford (BSc, Leeds; PhD, Cantab; Chart. Psycho!., FBPsS) is Professor of Psychology at the University of Glasgow, and a principal investigator with the Human Communication Research Centre, which he helped to found. His research includes experimental studies of language comprehension and production, and psychological aspects of meaning, as well as forensic linguistics and writing style. He has written five books.
  • Joy P. Aked, University of Glasgow
    Joy Aked (BSc, PhD, Glasgow) is a Research Assistant at the University of Glasgow in the Human Communication Research Centre, working on language comprehension and latterly on models of writing style.
  • Linda M. Moxey, University of Glasgow
    Linda Moxey (MA, PhD, Glasgow, MSc, Edinburgh) is a Lecturer in Psychology at the University of Glasgow, and was formerly a British Academy Research Fellow. Her interests are in language use both in practical contexts and from a theoretical perspective. She has written several papers on Psychological Semantics, and, with A. ]. Sanford, the book Communicating Quantities (1993, Lawrence Erlbaum).
  • James Mullin, University of Glasgow
    James Mullin (BSc, Glasgow) is a Computer Manager in the Department of Psychology at the University of Glasgow. He has provided computational support for much of the research in the Department of Human Communication. He has written several papers, and has developed computer-based psychology laboratories and associated manuals.

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Published

1994-12-01

Issue

Vol. 1 No. 2 (1994)

Section

Articles

License

© Equinox Publishing Ltd.

For information regarding our Open Access policy, click here.

How to Cite

Sandford, A. J., Aked, J. P., Moxey, L. M., & Mullin, J. (1994). A critical examination of assumptions underlying the cusum technique of forensic linguistics. International Journal of Speech, Language and the Law, 1(2), 151-167. https://doi.org/10.1558/ijsll.v1i2.151