Signature authentication by forensic document examiners

We report on the first controlled study comparing the abilities of forensic document examiners (FDEs) and laypersons in the area of signature examinat ion. Laypersons and professional FDEs were given the same signature-authent ication/simulation-detection task. They compared six known signatures gener ated by the same person with six unknown signatures. No a priori knowledge of the distribution of genuine and nongenuine signatures in the unknown sig nature set was available to test-takers. Three different monetary incentive schemes were implemented to motivate the laypersons. We provide two major findings. (i) the data provided by FDEs and by laypers ons in our tests were significantly different (namely, the hypothesis that there is no difference between the assessments provided by FDEs and laypers ons about genuineness and nongenuineness of signatures was rejected); and ( ii) the error rates exhibited by the FDEs were much smaller than those of t he laypersons. In addition, we found no statistically significant differenc es between the data sets obtained from laypersons who received different mo netary incentives. The most pronounced differences in error rates appeared when nongenuine sig natures were declared authentic (Type I error) and when authentic signature s were declared nongenuine (Type II error). Type I error was made by FDEs i n 0.49% of the cases, bur laypersons made it in 6.47% of the cases. Type II error was made by FDEs in 7.05% of the cases, but laypersons made it in 26 .1% of the cases.