The use of contextual information in forensic toxicology: An international survey of toxicologists' experiences

Abstract

Cognitive bias is a well-documented automatic process that can have serious negative consequences in a variety of settings. For example, cognitive bias within a forensic science setting can lead to examiners' judgements being swayed by details that they have learned while working on the case, and which go beyond the physical evidence being examined. Although cognitive bias has been studied in many forensic disciplines, such as fingerprints, bullet comparison, and document examination, knowledge of cognitive bias within forensic toxicology is lacking. Here, we address this knowledge gap by assessing the reported use of contextual information by an international group of forensic toxicologists attending the 54th conference of The International Association of Forensic Toxicologists (TIAFT) in Brisbane in 2016. In a first study, participants read a set of simple post-mortem toxicology results (two drug concentrations in blood) and then indicated what information they would normally use when interpreting these results in their day-to-day casework. Using a questionnaire, we then surveyed the familiarity of toxicologists with contextual bias and captured any suggested bias-minimizing procedures for use in forensic toxicology laboratories. Thirty-six participants from 23 different countries and with a range of 1–35 years' forensic toxicology reporting experience volunteered. Analysis of their responses showed that the majority of participants reported using some contextual information in their interpretation of these post-mortem toxicology results (range = 3–15 pieces of information, median ± SD = 11 ± 3), the most common being the deceased's history of prescription or illicit drug use. More than three-quarters of participants reported being familiar with the concept of contextual bias, although few (n = 9) worked in laboratories that had a formal policy covering it. Over half of participants knew of at least one bias-minimizing procedure specifically for forensic toxicology casework, but only a quarter (overall) reported using bias-minimizing procedures in their laboratories. Our results provide substantial evidence that although practising forensic toxicologists are familiar with contextual bias, many report that they still engage in behaviours that could lead to cognitive bias (e.g., through the use of contextual information, through lack of explicit policies or bias-minimizing procedures). We anticipate that our work will form the basis of further research involving a larger sample of participants and examining other potentially relevant factors such as sex/gender, country and accreditation of laboratories.