How signature complexity affects expert and lay ability to distinguish genuine, disguised and simulated signatures
Date
2024-11
Authors
Scurich, Nicholas
Angel, Miriam
Stern, Hal
Thompson, William
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Wiley Periodicals LLC on behalf of American Academy of Forensic Sciences
Abstract
This study examined how variations in signature complexity affected the ability of forensic document examiners (FDEs) and laypeople to determine whether signatures are authentic or simulated (forged), as well as whether they are disguised. Forty-five FDEs from nine countries evaluated nine different signature comparisons in this online study. Receiver Operating Characteristic (ROC) analyses revealed that FDEs performed in excess of chance levels, but performance varied as a function of signature complexity: Sensitivity (the true-positive rate) did not differ much between complexity levels (i.e., 65% vs. 79% vs. 79% for low vs medium vs high complexity), but specificity (the true-negative rate) was the highest (95%) for the medium complexity signatures and lowest (73%) for low complexity signatures. The specificity of high-complexity signatures (83%) was between these values. The sensitivity for disguised comparisons was only 11% and did not vary across complexity levels. One hundred-one novices also completed the study. A comparison of the area under the ROC curve (AUCs) revealed that FDEs outperformed novices in medium and high-complexity signatures but not low-complexity signatures. Novices also struggled to detect disguised signatures. While these findings elucidate the role of signature complexity in lay and expert evaluations, the error rates observed here may differ from those in forensic practice due to differences in the experimental stimuli and circumstances under which they were evaluated. This investigation of the role of signature complexity in the evaluation process was not intended to estimate error rates in forensic practice.
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This article is published as Scurich, Nicholas, Miriam Angel, Hal Stern, and William C. Thompson. "How signature complexity affects expert and lay ability to distinguish genuine, disguised and simulated signatures." Journal of Forensic Sciences 69, no. 6 (2024): 2159-2170. https://doi.org/10.1111/1556-4029.15605. Posted with permission of CSAFE.
Rights Statement
© 2024 The Author(s). This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
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Funding
Center for Statistics and Applications in Forensic Evidence (CSAFE), Grant/Award Number: 70NANB15H176 and 70NANB20H019