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Evaluating the ‘suggestiveness’ of showups: Evidence for an implicit feedback effect on witness confidence

(Completed – Under review) 

Currently, there is a fairly large body of research that has examined the efficacy of showups (presentation of a single suspect to eyewitnesses for the purpose of identification).  Contrary to the intuitive beliefs of researchers and other legal scholars, this research has suggested that showups are not more suggestive than lineups and, in fact, lead to more accurate eyewitness identifications than lineups (for a review see Steblay, N., Dysart, J., Fulero, S., & Lindsay, R. C. L. (2003). Eyewitness accuracy rates in police showup and lineup presentations: A meta-analytic comparison. Law and Human Behavior, 27(5), 523-540.).  This research, however, only looked at one aspect of showups that was believed to be suggestive by the courts; lack of protection.  In comparison to lineups, showups offer no protection to an innocent suspect when he/she is presented to an eyewitness that feels compelled to choose anyone.  In a properly constructed lineup, the likelihood of misidentifying an innocent suspect will be equal to 1/k (where k equals the number of individuals presented in the lineup).  In a showup, the likelihood of misidentification by an eyewitness that feels compelled to identify anyone is also 1/k, however k always equals 1 and therefore the likelihood of misidentification is equal to 100% in a situation where the eyewitness feels compelled to pick anyone.  According to the previous research, this "lack of protection" does not appear to increase the likelihood of misidentification.  However, drawing ultimate conclusions that showups are more accurate than lineups is troublesome since the research only focused on one specific aspect of showups that was believed to be suggestive by the Courts.  The Courts have also proposed that "custodial influence" (the presentation of an individual in the custody of police officers) may be unduly suggestive and therefore bias the eyewitness' identification.  The present research was designed to assess whether custodial influence increases the likelihood of identification of a suspect in a showup, regardless of whether the suspect is the perpetrator of the crime.  Results of this research suggest that custodial influence increases both the likelihood of identification of a suspect, regardless of guilt or innocence, as well as the confidence the eyewitness has in his/her identification.  A manuscript of this research is currently under review. 

Research Team:    Dr. Stephen J. Ross

 

Examining field/archival research on eyewitness identification procedures

(Completed – Manuscript revision) 

The recent publications of lineup evaluations from Hennepin County, Minnesota and Illinois have sparked much controversy over the relative effectiveness of sequential and simultaneous lineup procedures.  At the base of this controversy is the contention that field evaluations are highly sensitive to aspects of the study environment and, therefore, researchers must be diligent to ensure that proper field evaluation techniques are being utilized when conducting this research.  However, commentators have overlooked that we now have 10 published reports evaluating eyewitness identification practices in actual police investigations.  These reports provide us with an opportunity to evaluate the influence of various system and estimator variables across time and jurisdiction.  The present examination was conducted to compare, and combine where possible, the results from these studies to determine the influence of specific system and estimator variables on eyewitness identification rates.  Results from this project were presented at the “Off the witness stand” conference at John Jay College in March, 2007 and at annual meeting of the American Psychology-Law Society in Jacksonville, FL in March 2008.  We are currently revising a manuscript and will be resubmitting it for review.

Research Team:    Dr. Stephen J. Ross

                                Dr. Roy S. Malpass (University of Texas at El Paso)

                               

Understanding the processes behind the Appearance Change Instruction: Criterion shift or mental mutation?

(Completed - Manuscript preparation)

Prior to viewing a lineup, eyewitnesses are often instructed that the perpetrator’s appearance may not be the same in the lineup as it was during commission of the crime.  Only one published study (Charman & Wells, 2007) has evaluated the efficacy of this “appearance change instruction” (ACI).  Charman and Wells (2007) found that the ACI was actually detrimental to eyewitnesses as it increased the likelihood of a false identification without increasing correct identifications and proposed two theories that may explain the effects the ACI has on eyewitness recognition. First, they proposed that by giving eyewitnesses the ACI prior to the identification task, the witness may be engaging in a form of “mental mutation” in which they are imagining alternatives to the lineup members that are more similar to their memory of the perpetrator and then evaluating whether that “new” stimulus is the perpetrator.  This mutation increases the extent to which the eyewitness’ new stimuli are similar to their original memory of the perpetrator resulting in an increase in “general ecphoric similarity” leading to an increase in choosing rates across both perpetrator-present and perpetrator-absent lineups. The second theory proposed by Charman and Wells (2007), is that the ACI influences eyewitness decisions through a downward criterion shift.  According to this theory, the implication that the perpetrator may not look the same now as he/she did during commission of the crime leads to a lowered decision criterion causing eyewitnesses to be willing to accept less similarity between the lineup member and their memory of the perpetrator as a positive identification. 

In this research we are interested in evaluating the cognitive mechanisms through which the ACI influences eyewitness decisions.  We will directly contrast two theories of how the ACI may influence eyewitness decisions as proposed by Charman and Wells (2007).  Specifically, through a series of three studies we will evaluate whether the influence of the ACI on eyewitness decisions appears to be a product of a general increase in ecphoric similarity (due to mental mutation of the original memory with the presented lineup members) or a downward criterion shift.  In Study 1, a process-tracing approach (Ericsson & Simon, 1993) will be used to evaluate the decision processes used by eyewitnesses when given the ACI and compare that with other eyewitnesses not given this instruction.  Study 2 will use a dual-process paradigm (Meissner, Tredoux, Parker, & Maclin, 2005) to evaluate whether the ACI influences criterion placement and familiarity-based responding. Finally, Study 3 will involve a secondary recognition task in which eyewitnesses will be asked to identify previously seen lineup members from a photoarray containing images of those lineup members and various “morphs” of those lineup members with the original perpetrator’s image. Studies 1 and 2 have been completed with results presented at the last two meetings of the American Psychology-Law Society. Data collection on Study 3 is currently underway. 

Research Team:    Dr. Stephen J. Ross
                                Brian Cahill (Graduate Assistant - Florida International University)
                                Jenna Kieckhaefer (Graduate Assistant - Florida International University)

 

Evaluating lineup construction techniques: Similarity structure, lineup fairness, and diagnosticity

(Data collection)

Research indicates that suspect-filler similarity is associated with lineup fairness such that lineups in which the fillers are more similar to the  suspect are fairer than those that consist of fillers that are dissimilar to the suspect (Malpass & Devine, 1983; Malpass, Tredoux & McQuiston-Surrett, 2005).  In this research we are interested in determining the extent to which the similarity structure of lineups is influenced by the construction technique (match-to-description, match-to-suspect, Wogalter, & Iterative).  In addition, we are evaluating the efficiency of various construction techniques and the fairness & diagnostic value of the lineups developed using these techniques.  In contrast to previous research evaluating similarity structure of lineups, we are using an objective measure of facial similarity derived from a geometric model constructed through principal-components analysis (PCA).  Using this approach, the similarity between any two faces can be estimated by calculating the Euclidian distance between those two faces in the geometric model.  Participants are trained in one of the four construction techniques and are required to construct lineups for four different suspects.  Data for this project is currently being collected.  Analyses will be performed to evaluate whether the similarity structure of the lineup (suspect-filler similarity & inter-filler similarity) varies across the four construction techniques.  In addition, the efficiency of the construction techniques in relation to amount of training required, ease of understanding, and amount of time required for constructing the lineups will be evaluated.  Future data collection will be conducted to evaluate the fairness and diagnostic value of the lineups generated using these techniques.

Research Team:    Dr. Stephen J. Ross

                                Petru Fernandez (Research Assistant - Florida International University)