Legal psychologists as experts: guidelines for minimizing bias

Abstract

Legal psychologists’ assessments can have a major impact on the fact finder’s evaluation of evidence and, consequently, perceptions of guilt. Yet, in the few studies about legal psychologists’ assessments and reports, great variability was found. As is the case with other forensic expert domains, legal psychologists are prone to cognitive biases, such as being adversely affected by irrelevant contextual information, confirmation bias, and allegiance bias. Based on the scientific literature, we propose several ways in which legal psychologists can minimize cognitive biases in their assessments, most notably the alternative scenario method. Furthermore, we propose guidelines for expert witnesses in the legal psychological domain, designed to make reports as scientifically grounded, applicable, readable, transparent, and bias-free as possible. We hope that the guidelines will enhance the quality of expert witness testimony provided by legal psychologists around the world.