Are forensic scientists too risk averse?

Willa M. Mannering, Macgregor D. Vogelsang, Thomas A. Busey, Fred L. Mannering

Abstract

Fingerprint examiners maintain decision thresholds that represent the amount of evidence required for an identification or exclusion conclusion. As measured by error rate studies (Proc Natl Acad Sci USA. 2011;108(19):7733–8), these decision thresholds currently exhibit a preference for preventing erroneous identification errors at the expense of preventing erroneous exclusion errors. The goal of this study is to measure the decision thresholds for both fingerprint examiners and members of the general public, to determine whether examiners are more risk averse than potential jury members. To externally measure these decision thresholds, subjects manipulated decision criteria in a web‐based visualization that reflects the trade‐offs between erroneous identification decisions and erroneous exclusion decisions. Data from fingerprint examiners and the general public were compared to determine whether both groups have similar values as expressed by the placement of the decision criteria. The results of this study show that fingerprint examiners are more risk averse than members of the general public, although they align with error rate studies of fingerprint examiners. Demographic data demonstrate those factors that may contribute to differences in decision criterion placement, both between the two groups and between individuals within a group. The experimental methods provide a rich framework for measuring, interpreting, and responding to the values of society as applied to forensic decision‐making.