Culprit Present-Absent Criteria Discrepancy

I examined why mistaken identifications increase when either witnessing or testing conditions get worse. In Experiment 1 (N=633), participants watched either a clear or degraded version of a simulated crime. In Experiment 2 (N=1266), all participants watched the same version of the crime, but were then randomly assigned to either a clear or noise-degraded lineup. After indicating which lineup member best matched their memory for the culprit, participants indicated how well that lineup member matched their memory for the culprit. Degraded conditions led to fewer culprit identifications from present lineups and more mistaken identifications from absent lineups. Degrading witnessing/testing conditions resulted in lower memory ratings for the culprit, but, memory ratings for the best-matching innocent person were statistically equivalent under clear and degraded conditions. These results suggest that the reason mistaken identifications increase when witnessing/testing conditions get worse is because witnesses lower their criterion for making an affirmative identification.

Objective: When a witness is presented with an identification procedure, she may not be aware that among the valid response options is the option to say “I’m not sure” or “I don’t know”. This is problematic, at least in theory, because it suggests that witnesses might be forced into making definitive identification decisions when they do not have the requisite memory strength to reliably do so. In fact, past research suggests that providing witnesses with an explicit option to opt-out reduces innocent-suspect identifications without reducing culprit identifications (Weber & Perfect, 2012). This finding suggests that improving identification procedures in the real world might be as simple as providing witnesses with an explicit “opt-out” option. We sought to replicate this pattern of results across two experiments. Method: We randomly assigned Amazon Mechanical Turk Workers (Experiment 1A: N = 2003) and university students (Experiment 1B: N = 721) to a 2 (culprit: present, absent) x 2 (memory strength: strong, weak) x 2 (not-sure option: yes, no) between-participants design. We manipulated memory strength by giving witnesses either a clear or degraded view of the initial encoding video. After watching the encoding video, participants completed a 10-minute filler task and were then presented with a one-person showup procedure. Results: Consistent with our predictions, participants who were given an initial poor view were more likely to respond “I’m not sure” than were participants who were given an initial clear view. More importantly, contrary to both our predictions and to past research, the not-sure option neither improved classification performance nor the reliability of suspect identifications. Conclusion: We found no evidence that a not-sure option improves performance. If anything, the not-sure option did more harm than good.

We examined how giving eyewitnesses a weak recognition experience impacts their identification decisions. In 2 experiments we forced a weak recognition experience for lineups by impairing either encoding or retrieval conditions. In Experiment 1 (n = 245), undergraduate participants were randomly assigned to watch either a clear or a degraded culprit video and then viewed either a culprit-present or culprit-removed lineup identification procedure. In Experiment 2 (n = 227), all participants watched the same clear culprit video but were then randomly assigned to either view a clear or noise-degraded lineup procedure. Half of the participants viewed a culprit-present lineup procedure and the remaining participants viewed a culprit-removed lineup procedure. Not surprisingly, degrading either encoding or retrieval conditions led to a sharp drop in culprit identifications. Critically, and as predicted, degrading either encoding or retrieval conditions also led to a sharp increase in the identification of innocent persons. These results suggest that when a lineup procedure gives a witness a weak match-to-memory experience, the witness will lower her criterion for making an affirmative identification decision. This pattern of results is troubling because it suggests that witnesses who encounter lineups that do not include the culprit might have a tendency to use a lower criterion for identification than do witnesses who encounter lineups that actually include the culprit. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

While there is a growing body of research examining the relatively “cold,” cognitive decision-making components of showups, few attempts have been made to capture the “hot” affective components of showups that are thought to exacerbate the suggestiveness of the procedure. In 3 simulated-field experiments, we partnered with law enforcement to examine how participants who were led to believe they were involved in an actual criminal investigation (Field-simulation condition) differed from participants who knew they were not part of an actual investigation (Lab-simulation condition). We staged crimes for both conditions, but in the field-simulation condition, law enforcement personnel carried out mock investigations that culminated with a live showup. In Experiment 1 (N = 321), which did not include a culprit-present condition, the field-simulation condition increased innocent suspect identifications. The standard showup admonition decreased innocent suspect identifications, but only for dissimilar innocent suspects. Experiment 2 (N = 196) added a culprit-present condition and found that the field-simulation condition increased innocent suspect and culprit identifications to a similar extent. Experiment 3 (N = 367) replicated the findings of Experiment 2 and examined the impact of admonishing eyewitnesses that if they did not believe the suspect was the culprit, they might have additional opportunities to make an identification. Confidence-accuracy calibration analyses revealed that confidence discriminated accurate from inaccurate identifications in the field, but not in the lab; however, eyewitnesses who made identifications in the field were overconfident and across all levels of confidence were less likely to be correct than eyewitnesses who made identifications in the lab.

We tested the proposition that when eyewitnesses find it difficult to recognize a suspect (as in a culprit-absent showup), eyewitnesses accept a weaker match to memory for making an identification. We tie this proposition to the basic recognition memory literature, which shows people use lower decision criteria when recognition is made difficult so as to not miss their chance of getting a hit on the target. We randomly assigned participant–witnesses (N = 610) to a condition in which they were told that if they did not believe the suspect was the culprit, they would have additional opportunities to make an identification later (additional-opportunities instruction). We fully crossed this instruction with the standard admonition (i.e., the culprit may or may not be present) and with the presence or absence of the culprit in a showup identification procedure. The standard admonition had no impact on eyewitness decision-making; however, the additional-opportunities instruction reduced innocent-suspect identifications (from 33% to 15%) to a greater extent than culprit identifications (57% to 51%). The additional-opportunities instruction yielded a better tradeoff between culprit and innocent-suspect identifications as indicated by binary logistic regression and receiver operator characteristic (ROC) analyses.