Confidence and accuracy of lineup selections and rejections: Postdicting rejection accuracy with confidence

Correlation and calibration approaches show meaningful, positive confidence-accuracy relations for witnesses making selections from lineups, but rarely for rejections (Brewer & Wells, 2006; Sauerland & Sporer, 2009). This disparity may reflect the difference between selecting a single photo versus rejecting a set of photos. Participants (N = 101) in two experiments made selections from and rejections of lineups in situations requiring either a single confidence rating about a single face (typical of "choosers") or a single confidence rating about multiple faces (typical of "nonchoosers"). Mean confidence ratings were significantly higher for accurate versus inaccurate decisions for both selections and rejections when decisions were based on single faces. Single decisions about multiple faces produced no significant difference in confidence between correct and incorrect rejections but a significant difference for selections

A Bayesian Analysis on the (Dis) utility of iterative-showup procedures: The moderating impact of prior probabilities

A showup is an identification procedure in which a lone suspect is presented to the eyewitness for an identification attempt. Showups are commonly used when law enforcement personnel locate a suspect near the scene of a crime in both time and space but lack probable cause to make an arrest. If an eyewitness rejects a suspect from a showup, law enforcement personnel might find another suspect and run another showup. Indeed, law enforcement personnel might go through several iterations of finding suspects and running showups with the same eyewitness. We label this phenomenon the iterative-showup procedure. The consequence of this procedure is that innocent suspect identifications increase disproportionately to culprit identifications. This happens because there is only one culprit, but a seemingly endless supply of innocent suspects. We apply Bayesian modeling to single-and iterative-showup procedures to demonstrate that iterative showups are almost always associated with lower probative value. We demonstrate that the prior probabilities that later suspects are the culprit are greatly constrained by the posterior probabilities that earlier suspects were the culprit. Identifications from iterative-showup procedures are of questionable reliability. We review alternative investigative strategies that police might consider in order to limit the use of iterative-showup procedures

Fair lineups are better than biased lineups and showups, but not because they increase underlying discriminability

Receiver Operating Characteristic (ROC) analysis has recently come in vogue for assessing the underlying discriminability and the applied utility of lineup procedures. Two primary assumptions underlie recommendations that ROC analysis be used to assess the applied utility of lineup procedures: (a) ROC analysis of lineups measures underlying discriminability, and (b) the procedure that produces superior underlying discriminability produces superior applied utility. These same assumptions underlie a recently derived diagnostic-feature detection theory, a theory of discriminability, intended to explain recent patterns observed in ROC comparisons of lineups. We demonstrate, however, that these assumptions are incorrect when ROC analysis is applied to lineups. We also demonstrate that a structural phenomenon of lineups, differential filler siphoning, and not the psychological phenomenon of diagnostic-feature detection, explains why lineups are superior to showups and why fair lineups are superior to biased lineups. In the process of our proofs, we show that computational simulations have assumed, unrealistically, that all witnesses share exactly the same decision criteria. When criterial variance is included in computational models, differential filler siphoning emerges. The result proves dissociation between ROC curves and underlying discriminability: Higher ROC curves for lineups than for showups and for fair than for biased lineups despite no increase in underlying discriminability

The impact of multiple show-ups on eyewitness decision-making and innocence risk

If an eyewitness rejects a show-up, police may respond by finding a new suspect and conducting a second show-up with the same eyewitness. Police may continue finding suspects and conducting show-ups until the eyewitness makes an identification (Study 1). Relatively low criterion-setting eyewitnesses filter themselves out of the multiple show-ups procedure by choosing the first suspect with whom they are presented (Studies 2 and 3). Accordingly, response bias was more stringent on the second show-up when compared with the first, but became no more stringent with additional show-ups. Despite this stringent shift in response bias, innocence risk increased with additional show-ups,