17Cognitive bias is a well-documented automatic process that can have serious negative consequences in a 18 variety of settings. For example, cognitive bias within a forensic science setting can lead to examiners' 19 judgements being swayed by details that they have learned while working on the case, and which go beyond 20 the physical evidence being examined. Although cognitive bias has been studied in many forensic disciplines, 21 such as fingerprints, bullet comparison, and document examination, knowledge of cognitive bias within 22 forensic toxicology is lacking. Here, we address this knowledge gap by assessing use of contextual information 23 by an international group of forensic toxicologists attending the 54th conference of The International 24 Association of Forensic Toxicologists (TIAFT) in Brisbane in 2016. In a first study, participants read a set of 25 simple post-mortem toxicology results (two drug concentrations in blood) and then indicated what 26 information they would normally use when interpreting these results in their day-to-day casework. Using a 27 questionnaire, we then surveyed the familiarity of toxicologists with contextual bias and captured any 28 suggested bias-minimizing procedures for use in forensic toxicology laboratories. Thirty-six participants from 29 23 different countries and with a range of 1-35 years' forensic toxicology reporting experience volunteered. 30 Analysis of their responses showed that the majority of participants used some contextual information in their 31 interpretation of post-mortem toxicology results (range = 3-15 pieces of information, median SD = 11 3), 32 the most common being the deceased's history of prescription or illicit drug use. More than three-quarters of 33 participants reported being familiar with the concept of contextual bias, although few (n = 9) worked in 34 laboratories that had a formal policy covering it. Over half of participants knew of at least one bias-minimizing 35 procedure specifically for forensic toxicology casework, but only a quarter (overall) reported using bias-36 minimizing procedures in their laboratories. Our results provide substantial evidence that although practising 37 forensic toxicologists are familiar with contextual bias, many report that they still engage in behaviours that 38 could lead to cognitive bias (e.g., through the use of contextual information, through lack of explicit policies 39 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 1 and accreditation of laboratories. 2 3 4 Keywords: cognitive bias; forensic toxicology; bias-minimizing procedure; contextual bias 5 6
