The effects of target discriminability and criterion placement on accuracy rates in sequential and simultaneous target-present lineups

Abstract

Participants attempted to select previously studied faces from lineups that were administered either sequentially (test faces presented one at a time) or simultaneously (test faces presented altogether). Target discriminability was manipulated by varying the number of facial features that could be used to distinguish the study face from the other test faces (foils) or by varying study face exposure duration. In addition, decision criterion level was manipulated via an instruction manipulation. Results indicated that sequential participants adopted a stricter decision standard under high criterion instructions compared to simultaneous participants. Under liberal criterion setting instructions, the rate at which the target was selected was comparable across lineup procedures. Target discriminability affected target selections to a greater extent in simultaneous compared to sequential lineups. We discuss the applied implications that these findings have regarding correct identifications from lineups.     

Mugshot Exposure Effects: Retroactive Interference, Mugshot Commitment, Source Confusion, and Unconscious Transference

More than 25 years of research has accumulated concerning the possible biasing effects of mugshot exposure to eyewitnesses. Two separate metaanalyses were conducted on 32 independent tests of the hypothesis that prior mugshot exposure decreases witness accuracy at a subsequent lineup. Mugshot exposure both significantly decreased proportion correct and increased the false alarm rate, the effect being greater on false alarms. A mugshot commitment effect, arising from the identification of someone in a mugshot, was a substantial moderator of both these effects. Simple retroactive interference, where the target person is not included among mugshots and no one in a mugshot is present in the subsequent lineup, did not significantly impair target identification. A third metaanalysis was conducted on 19 independent tests of the hypothesis that failure of memory for facial source or context results in transference errors. The effect size was more than twice as large for "transference" studies involving mugshot exposure in proximate temporal context with the target than for "bystander" studies with no subsequent mugshot exposure.     

“To develop and test:” The inventive difference between evaluation and experimentation

The National Research Council (NRC) Report on Improving Evaluation of Anticrime Programs raises a fundamental question about the mission of evaluation research. The implicit premise of the report is that the mission of evaluation is to answer questions about programs developed by others; in short, to test anti-crime programs. In contrast, the mission of experimental criminology has, historically, been to develop anti-crime programs as well as to test them. There are times when an arm’s-length relationship between program and evaluation may be appropriate. Yet, such a separation necessarily produces a courtroom-like adjudication role for evaluators, rather than the laboratory-like, participant–inventor role that has characterized the best of experimental criminology. The recent case of the Chicago police’s “evaluating” the use of sequential suspect identification methods developed by academic psychologists shows the many flaws of the “testing-only” model. This suggests that providing “effective guidance of criminal justice policy and practice,” as the NRC report defines its focus [Lipsey, M. ed (2005). http://newton.nap.edu/pdf/0309097061/pdf_image/R1.pdf] will not only require evaluation research (defined as arm’s-length testing) but the full toolbox of experimental criminology to develop and test anti-crime programs.

Do Trained Dogs Discriminate Individual Body Odors of Women Better than Those of Men?*

Scent identification lineups using dogs are a potentially valuable forensic tool, but have been dismissed by some critics because of cases where a false identification was shown to have occurred. It is not known, however, why dogs appear to make more false indications to the odors of some persons than of others. In this study, human genders were compared as to the degree their individual odors are distinguishable or "attractive" to dogs. Six dogs were trained to smell an individual's hand odor sample and then find the matching hand odor sample in a lineup of five odors. Using one-gender lineups and two-gender lineups with different gender ratios, it was found that dogs trained for the study identified individual women's hand odors more accurately than those of men. It is hypothesized that this is either because of differences in chemical compounds making discrimination of women's odors easier, or because of greater "odor attractiveness" of women's scents to dogs.     

Prior knowledge influences interpretations of eyewitness confidence statements: ‘The witness picked the suspect,they must be 100% sure%

When an eyewitness identifies a suspect from a lineup, it is important to know how certain they are about the decision. Even though eyewitnesses are likely to express certainty with words, past research shows that verbal confidence statements (e.g. ‘I’m pretty sure’) are prone to systematic misinterpretation. Until now, no one has examined how an evaluator's prior knowledge, such as which lineup member is the police suspect, influences their interpretation of eyewitness confidence about a lineup identification. Experiments 1 and 3 show that participants perceived the identical statement of confidence as meaning a higher and lower level of certainty, respectively, when the eyewitness's selection either matched or mismatched the police's suspect. Experiment 2 shows that these effects generally persist when the bias manipulation is manipulated between-subjects. Finally, Experiment 3 finds that clarifying the witness's statement with numeric information (e.g. I’m 80% sure) does not eliminate the influence of biasing information.     

Age Differences in Lineup Identification Accuracy: People Are Better with Their Own Age

Previous research has reported that young adults are better at eyewitness face recognition than are older adults. However, these studies have used young adults as culprits and fillers. We explore how the relative ages of the witness and the culprit influence eyewitness accuracy in 2 experiments. In the first experiment, young (18–25 years old) and older (35–55 years old) adults each saw 4 crime videos. In 2 the culprit was a young adult and in 2 the culprit was an older adult. Participants were more accurate at identifying the culprit when viewing culprit present lineups comprising people of their own age: an own age bias analogous to the own race bias. In the 2nd experiment, using a similar procedure, young (18–33 years old) and older (40–55 years old) adults viewed both culprit present and culprit absent lineups. The results of the first experiment were replicated for the culprit present lineups. However, no own age bias was found for the culprit absent lineups. Implications for police procedures dealing with cross-generation identifications are discussed.     

The application of multiple lineups in a field study

Abstract

The usefulness of multiple lineups was tested in a field experiment with nine different targets. Six hundred and forty-eight passers-by were asked for directions in the pedestrian zone of a university town. Subsequently, they were approached by a different person and asked to identify the target from portrait, body, and profile lineups. Additionally, participants were asked to identify a shopping bag that the target had carried. Two of the lineups were target-present, and two target-absent. Diagnosticity ratios (DRs) were computed for target/suspect choices, lineup rejections and foil choices. Compared to foil choices and rejections, target/suspect choices were most diagnostic of guilt. Here, the combination of lineups was superior over individual lineups. Lineup rejections showed some capability of establishing innocence, but with lower DRs than target/suspect choices. Here, combinations did not increase diagnosticity. The diagnosticity of multiple foil choices was acceptable for portrait face lineups but limited for all other lineups or combinations.