The impact of evidence lineups on fingerprint expert decisions

Abstract

Summary Forensic examiners routinely compare a crime‐relevant mark of unknown origin against a single suspect's sample, which may create an expectation that the two will match. We tested how embedding the suspect's sample among known‐innocent fillers (i.e., an evidence lineup) affects expert decision‐making. Experienced fingerprint examiners (N = 43) compared crime‐relevant marks against either individual suspect fingerprints (i.e., the standard procedure) or arrays of fingerprints (i.e., evidence lineups), with a matching fingerprint either present or absent. Evidence lineups promoted conservative decision‐making, as evidenced by fewer correct IDs and a higher rate of inconclusive judgments. Though errors were rare, evidence lineups also occasionally revealed errors that would have otherwise gone undetected. Our findings thus support arguments that evidence lineups can expose fraud, identify flawed methodologies, and curb overconfidence. The potential benefits and challenges of implementing evidence lineups in forensic laboratories are discussed.

Human Factors in Forensic Science: Psychological Causes of Bias and Error

“…Ribeiro et al (2019) also found that jurors underestimated fingerprint examiners' accuracy (88%) relative to their actual accuracy rates in proficiency studies (97%; Tangen et al, 2011;Ulery et al, 2011). Thus, jurors may sometimes overvalue and sometimes undervalue forensic evidence-but importantly, for any forensic discipline whose error rate is unknown (NAS, 2009; see also Dror, 2020b), it is impossible to know if jurors are giving the evidence too much or too little weight.…”

“…As it stands, many laboratories either create and distribute their own proficiency tests or they contract an external organization to do so. However, scholars have noted that proficiency test results are only informative to the extent that the tests approximate actual casework (e.g., Dror, 2020b;Koehler, 2013;Mejia et al, 2020;Risinger et al, 2002)-and unfortunately, proficiency tests often fall short in two important respects.…”

“…Despite the logistical challenges of designing ecologically valid proficiency tests-such as knowing the ground truth of test samples, identifying samples of appropriate difficulty, and deciding when, if ever, to count inconclusive decisions as correct (see, e.g., Dror, 2020b;Dror & Scurich, 2020;Martire & Kemp, 2018;Mejia et al, 2020)-numerous laboratories have published accounts of their own implementation of blind proficiency testing programs (e.g., Hundl et al, 2020;Moral et al, 2019;Pierce & Cook, 2020; see also Gardner et al, 2021), detailing its costs and benefits and encouraging other labs to follow suit.…”

Impact of Minutiae Errors in Latent Fingerprint Identification: Assessment and Prediction

“…Their results have shown that examiners made a positive identification of 37.8% for displayed images; by contrast, 25.6% images were classified as inconclusive. The main drawback of [29] is that examiners were aware of being part of a monitored study. This may explain why the study output an unusually high rate of inconclusive judgments attributed to suspicion of examiners aware they were under assessment.…”

“…The analysis of these errors is critical to understand the performance of these systems. There are studies analyzing the likelihood of human errors in the stages a to c and showing these errors are habitual [26][27][28][29]. Nevertheless, there are not studies evaluating how these errors affect the identification stage, (d).…”