The Dynamic Character of Disguise Behavior for Text-based, Mixed, and Stylized Signatures

Authors

  • Linton A. Mohammed M.F.S.,

    1. San Diego Sheriff’s Regional Crime Laboratory, 5255 Mt. Etna Drive, San Diego, CA 92117.
    2. Handwriting Analysis and Research Laboratory, School of Human Biosciences, La Trobe University, Bundoora, Vic. 3086, Australia.
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  • Bryan Found Ph.D.,

    1. Handwriting Analysis and Research Laboratory, School of Human Biosciences, La Trobe University, Bundoora, Vic. 3086, Australia.
    2. Document Examination Unit, Digital and Documents Evidence Branch, Victoria Police Forensic Services Department, Macleod, Vic. 3085, Australia.
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  • Michael Caligiuri Ph.D.,

    1. Department of Psychiatry, School of Medicine, University of California, San Diego, San Diego, CA 92037.
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  • Doug Rogers Ph.D.

    1. Handwriting Analysis and Research Laboratory, School of Human Biosciences, La Trobe University, Bundoora, Vic. 3086, Australia.
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Additional information and reprint requests:
Linton A. Mohammed, M.F.S.
Forensic Document Examiner
923 Merlo Court
Carlsbad, CA 92011
E-mail: lamqde@gmail.com

Abstract

Abstract:  The aims of this study were to determine if dynamic parameters (duration, size, velocity, jerk, and pen pressure) differed for signing style (text-based, stylized, and mixed) and if signing style influences handwriting dynamics equally across three signature conditions (genuine, disguised, and auto-simulation). Ninety writers provided 10 genuine signatures, five disguised signatures, and five auto-simulated signatures. All 1800 signatures were collected using a digitizing tablet resulting in a database of each signature’s dynamic characteristics. With genuine signatures, there were significant differences between styles for size, velocity, and pen pressure, and there were significant differences between genuine signatures and at least one of the un-natural signature conditions for all parameters. For velocity and size, these changes with condition were dependent on style. Changes with condition for the other parameters were similar for the three styles. This study shows that there are differences among natural signature styles and disguise behaviors that may be relevant in forensic signature examinations.

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