Laura Smalarz

Eyewitness Identification: Bayesian Information Gain, Base-Rate Effect-Equivalency Curves, and Reasonable Suspicion

We provide a novel Bayesian treatment of the eyewitness identification problem as it relates to various system variables, such as instruction effects, lineup presentation format, lineup-filler similarity, lineup administrator influence, and show-ups versus lineups. We describe why eyewitness identification is a natural Bayesian problem and how numerous important observations require careful consideration of base rates. Moreover, we argue that the base rate in eyewitness identification should be construed as a system variable (under the control of the justice system). We then use prior-by-posterior curves and information-gain curves to examine data obtained from a large number of published experiments. Next, we show how information-gain curves are moderated by system variables and by witness confidence and we note how information-gain curves reveal that lineups are consistently more proficient at incriminating the guilty than they are at exonerating the innocent. We then introduce a new type of analysis that we developed called base rate effect-equivalency (BREE) curves. BREE curves display how much change in the base rate is required to match the impact of any given system variable. The results indicate that even relatively modest changes to the base rate can have more impact on the reliability of eyewitness identification evidence than do the traditional system variables that have received so much attention in the literature. We note how this Bayesian analysis of eyewitness identification has implications for the question of whether there ought to be a reasonable-suspicion criterion for placing a person into the jeopardy of an identification procedure.

Contamination of Eyewitness Self-Reports and the Mistaken-Identification Problem

Mistaken identification testimony by highly confident eyewitnesses has been involved in approximately 72% of the cases in which innocent people have been convicted and later exonerated by DNA testing. Lab studies of eyewitness identification, however, show that mistaken eyewitnesses are usually not highly confident and that there is a useful confidence-accuracy relation that can help distinguish accurate from mistaken eyewitnesses. We describe research on important variables that can cause mistaken eyewitnesses to give inflated self-reports about their confidence and other testimony-relevant judgments. These testimony-bolstering variables tend to be controlled in pristine experiments, thereby permitting good confidence-accuracy relations. In the real world, however, methods of obtaining identifications and supporting testimony permit testimony-bolstering variables to contaminate witness self-reports in ways that make it difficult to distinguish between accurate and mistaken eyewitness identification testimony. We describe how the justice system can dramatically reduce the chances of such contamination.

The perfect match: Do criminal stereotypes bias forensic evidence analysis?

This research provided the first empirical test of the hypothesis that stereotypes bias evaluations of forensic evidence. A pilot study (N = 107) assessed the content and consensus of 20 criminal stereotypes by identifying perpetrator characteristics (e.g., sex, race, age, religion) that are stereotypically associated with specific crimes. In the main experiment (N = 225), participants read a mock police incident report involving either a stereotyped crime (child molestation) or a nonstereotyped crime (identity theft) and judged whether a suspects fingerprint matched a fingerprint recovered at the crime scene. Accompanying the suspects fingerprint was personal information about the suspect of the type that is routinely available to fingerprint analysts (e.g., race, sex) and which could activate a stereotype. Participants most often perceived the fingerprints to match when the suspect fit the criminal stereotype, even though the prints did not actually match. Moreover, participants appeared to be unaware of the extent to which a criminal stereotype had biased their evaluations. These findings demonstrate that criminal stereotypes are a potential source of bias in forensic evidence analysis and suggest that suspects who fit criminal stereotypes may be disadvantaged over the course of the criminal justice process. (PsycINFO Database Record

Miranda at 50: A Psychological Analysis

In 1966, the U.S. Supreme Court handed down a controversial ruling in Miranda v. Arizona, which required police to inform suspects, prior to custodial interrogation, of their constitutional rights to silence and to counsel. In commemoration of the 50th anniversary of Miranda, we present a psychological analysis of the Court’s ruling. We show how the Court’s assumption that the provisions of the Miranda ruling would enable suspects to make knowing, intelligent, and voluntary decisions regarding whether to invoke or waive their constitutional rights has not been borne out by scientific research. Hence, we argue that even well-adjusted, intelligent adults are at risk of succumbing to police pressure during custodial interrogation. We conclude with policy implications and directions for future Miranda research.

Increasing the Similarity of Lineup Fillers to the Suspect Improves the Applied Value of Lineups Without Improving Memory Performance: Commentary on Colloff, Wade, and Strange (2016)

Among the most robust findings in the basic recognitionmemory literature is that increasing the similarity of lures to the target item decreases memory performance. This truism lies at the very heart of signal detection theory (SDT). Colloff, Wade, and Strange (2016), however, reported that lineups using high-similarity fillers (lineup lures) produced better memory performance than did lineups using low-similarity fillers. Specifically, they claimed that high-similarity fillers improved memory performance by helping witnesses determine which features were relevant for making an identification (i.e., diagnostic-feature detection), thereby making witnesses less likely to “confuse innocent and guilty suspects.” Using their data, we show that high-similarity fillers do not improve memory performance and that Colloff et al. used the wrong SDT model to estimate memory per for mance. We agree with Colloff et al. that their high-similarity lineups produced better applied outcomes for the legal system than did their low-similarity lineups, a finding that is consistent with the extant literature (e.g., Clark, 2012; Lindsay & Wells, 1980). However, as we show in this Commentary, high-similarity fillers did not make witnesses less likely to confuse the innocent with the guilty; high-similarity fillers simply influenced which innocent individual the witnesses confused with the guilty. Moreover, consistent with the long-established finding that high-similarity lures reduce rather than improve memory performance, our results show that memory performance is actually worse for high-similarity than for low-similarity lineups. The superior applied value of high-similarity lineups was not due to improved memory performance but instead to a process in which high-similarity lineups spread false-positive responses across lineup members. A six-person lineup is composed of either all innocent people (the innocent suspect plus five other innocents called fillers) or the culprit along with these same five innocent fillers. Any identification of an innocent person (whether an innocent filler or the innocent suspect) is a false positive (false alarm). Consider the data from Colloff et al. reproduced here in Table 1. In culpritpresent lineups, high-similarity fillers yielded a 31% true-positive rate, whereas low-similarity fillers yielded a 57% true-positive rate. In culprit-absent lineups, highsimilarity fillers yielded a 55% false-positive rate (innocent suspect: 9% + fillers: 46%), and low-similarity fillers yielded a 58% false-positive rate (innocent suspect: 36% + fillers: 22%). Hence, high-similarity lineups produced a lower rate of true positives and a functionally identical rate of false positives when compared with low-similarity lineups. Colloff et al., however, used an analysis that ignored all of the false positives on fillers and instead counted only the false-positive responses on the innocent 698528 PSSXXX10.1177/0956797617698528Smith et al.Measuring Memory Performance in Eyewitness Lineups other2018

Defendant stereotypicality moderates the effect of confession evidence on judgments of guilt.

This research examined whether criminal stereotypes—i.e., beliefs about the typical characteristics of crime perpetrators—influence mock jurors’ judgments of guilt in cases involving confession evidence. Mock jurors (N = 450) read a trial transcript that manipulated whether a defendant’s ethnicity was stereotypic or counterstereotypic of a crime, and whether the defendant had confessed to the crime or not. When a confession was present, the transcript varied whether the confession had been obtained using high-pressure or low-pressure interrogation tactics. Consistent with the hypothesis, the presence of a confession (relative to no confession) increased perceptions of the defendant’s guilt when the defendant was stereotypic of the crime, regardless of the interrogation tactics that had been used to obtain it. When the defendant was counterstereotypic of the crime, however, the presence of a confession did not significantly increase perceptions of guilt, even when the confession was obtained using low-pressure interrogation tactics. These findings demonstrate the potentially powerful effects of criminal stereotypes on legal judgments and suggest that individuals who fit a criminal stereotype may be disadvantaged over the course of the criminal justice process.

A Biphasic Process of Resistance Among Suspects: The Mobilization and Decline of Self-Regulatory Resources.

We conducted two experiments to test whether police interrogation elicits a biphasic process of resistance from suspects. According to this process, the initial threat of police interrogation mobilizes suspects to resist interrogative influence in a manner akin to a fight or flight response, but suspects’ protracted self-regulation of their behavior during subsequent questioning increases their susceptibility to interrogative influence in the long-run. In Experiment 1 (N = 316), participants who were threatened by an accusation of misconduct exhibited responses indicative of mobilization and more strongly resisted social pressure to acquiesce to suggestive questioning than did participants who were not accused. In Experiment 2 (N = 160), self-regulatory decline that was induced during questioning about misconduct undermined participants’ ability to resist suggestive questioning. These findings support a theoretical account of the dynamic and temporal nature of suspects’ responses to police interrogation over the course of questioning.

Psychological Science on Eyewitness Identification and the U.S. Supreme Court: Reconsiderations in Light of DNA-Exonerations and the Science of Eyewitness Identification

The U.S. Supreme Court has not reexamined the test for admission of eyewitness identifications that are the product of suggestive procedures in over 35 years (Manson v. Brathwaite, 432 U.S. 98, 1977). Since then, there have been over 218 DNA-based exonerations of individuals who were mistakenly identified, and an extensive and rich scientific literature on eyewitness identification has emerged. This chapter reviews the original Manson ruling, using as an analytic framework the Court’s own justifications for implementing a Manson test for determining the admissibility of suggestively obtained identification evidence. The Court’s 1977 ruling was meant to be a safeguard against wrongful conviction, and we note how the DNA-based exonerations can only be a small fraction of the total cases of wrongful convictions based on mistaken identification. The flaws inherent in Manson, in light of the last 30 years of scientific research on eyewitness identification, are reviewed, and it is argued that Manson fails to provide an adequate safeguard against wrongful conviction based on mistaken identification. The two objectives of the Manson ruling, namely suppressing unreliable identifications and providing a disincentive for suggestive procedures, cannot be met with the basic approach inherent in Manson and paradoxically may incentivize police to use suggestive procedures.