Human expert performance in forensic decision making: Seven different sources of bias

Abstract

Forensic science has existed for many decades without due attention being given to the important role of human cognition in forensic work. Without such attention, forensic examiners were believed to be objective and immune to bias. This past decade we have seen an impressive shift in forensic science, now taking human factors into account. One important element in cognitive forensics is to minimize potential bias in forensic work. To accomplish this we must first understand the different sources of bias and then develop and deploy counter measures whenever possible. In this paper, I go through seven sources of bias, some arising from the mere fact that we are humans, other originating from training, motivations and organizational factors (and other general sources of bias), and others arising from the specific case at hand. Bias is then placed within the wider context of human performance, showing the hierarchy of expert performance (HEP) that distinguishes between observations and conclusions in decision-making, between effects that are due to bias and those that do not arise from bias, and when performance varies among examiners and when it varies within the same examiner. A cognitive informed approach can substantially improve and contribute to forensic science.