Cognitive Bias and Blindness: A Global Survey of Forensic Science Examiners

Exposure to irrelevant contextual information prompts confirmation-biased judgments of forensic science evidence (Kassin, Dror, & Kukucka, 2013). Nevertheless, some forensic examiners appear to believe that blind testing is unnecessary. To assess forensic examiners' beliefs about the scope and nature of cognitive bias, we surveyed 403 experienced examiners from 21 countries. Overall, examiners regarded their judgments as nearly infallible and showed only a limited understanding and appreciation of cognitive bias. Most examiners believed they are immune to bias or can reduce bias through mere willpower, and fewer than half supported blind testing. Furthermore, many examiners showed a bias blind spot (Pronin, Lin, & Ross, 2002), acknowledging bias in other domains but not their own, and in other examiners but not themselves. These findings underscore the necessity of procedural reforms that blind forensic examiners to potentially biasing information, as is commonplace in other branches of science.