Handwriting: Cognitive Bias

Abstract

AbstractAlthough the forensic science community has long been cognizant of the need to avoid physical contamination of evidence, it has been reluctant to acknowledge the possibility of mental contamination of evidence in the form of cognitively biased forensic evaluations. As highlighted in the 2009 National Academies of Science report,Strengthening Forensic Science in the U.S: a Path Forward, empirical research in the fields of behavioral science and information obtained from reviews of forensic practitioner errors in several high‐profile cases have clearly established the adverse impact that contextual and motivational biases can have on human judgment and the accuracy of forensic evaluations of evidence. Nevertheless, far too many forensic handwriting experts still steadfastly believe that proper training and experience somehow shield them from the biasing influences that have been proven to impact the accuracy of visual observations and decision making on the part of human beings in all other walks of life. Understanding the various sources of bias and learning how to limit or minimize their influence is essential for improving the accuracy of decisions made by forensic handwriting experts and the reliability of their expert testimony.In this article, Andrew Sulner, a third‐generation board certified forensic document examiner and former state prosecutor, explains and illustrates how the opinions and expert testimony of individuals performing comparative analyses of signatures and handwriting are susceptible to biasing influences that can improperly taint and sway their decision‐making process and the manner in which they testify as experts. Actual case histories are used to demonstrate how cognitive or motivational bias can contribute to erroneous findings and/or disingenuous testimony on the part of experienced and presumptively well‐trained forensic document examiners. Individual debiasing techniques and institutional context management and evidence testing protocols for minimizing examiner bias in forensic handwriting investigations are also discussed.