Theoretical vs. empirical discriminability: The application of ROC methods to eyewitness identification.

Pairs (N=234) of witnesses and lineup administrators completed an identification task in which administrator knowledge, lineup presentation, instruction bias, and target presence were manipulated. Administrator knowledge had the greatest effect on identifications of the suspect for simultaneous photospreads paired with biased instructions, with single-blind administrations increasing identifications of the suspect. When biased instructions were given, single-blind administrations produced fewer foil identifications than double-blind administrations. Administrators exhibited a greater proportion of biasing behaviors during single-blind administrations than during double-blind administrations. The diagnosticity of identifications of the suspect in double-blind administrations was double their diagnosticity in single-blind administrations. These results suggest that when biasing factors are present to increase a witness's propensity to guess, single-blind administrator behavior influences witnesses to identify the suspect.

This experiment examined whether a photoarray administrator's knowledge of a suspect's identity increased false identification rates. Fifty participant-administrators (PAs) presented 50 participant-witnesses (PWs) two perpetrator-absent photoarrays following a live staged crime involving two perpetrators. For one photoarray per trial, the experimenter revealed the suspect's identity to the PA. Each PA presented the photoarrays sequentially or simultaneously in the presence or absence of an observer. When the observer was present, PA knowledge of the suspect's identity had a biasing effect in sequential photoarrays only. This pattern did not emerge when the observer was absent. The experimental manipulations did not affect PAs' and PWs' ratings of photoarray fairness or PWs' ratings of pressure to make an identification. These data suggest that only administrators who are blind to the suspect's identity should present sequential photoarrays.The vagaries of eyewitness identification are well-known... . A major factor contributing to the high incidence of miscarriage of justice from mistaken identification has been the degree of suggestion inherent in the manner in which the prosecution presents the suspect to witnesses for pretrial identification. . . . Suggestion can be created intentionally or unintentionally in many subtle ways.-Supreme Court Justice William Brennan, writing for the majority in United States v. Wade (1967) 940This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.

Scientifically trained and untrained judges read descriptions of an expert's research in which the peer review status and internal validity were manipulated. Seventeen percent of the judges said they would admit the expert evidence, irrespective of its internal validity. Publication in a peer-reviewed journal also had no effect on judges' decisions. Training interacted with the internal validity manipulation. Scientifically trained judges rated valid evidence more positively than did untrained judges. Untrained judges rated a study with a confound more positively than did trained judges. Training did not affect judge evaluations of studies with a missing control group or potential experimenter bias. Admissibility decisions were correlated with judges' perceptions of the study's validity, jurors' ability to evaluate scientific evidence, and the effectiveness of cross-examination and opposing experts to highlight flaws in scientific methodology.

We tested whether an opposing expert is an effective method of educating jurors about scientific validity by manipulating the methodological quality of defense expert testimony and the type of opposing prosecution expert testimony (none, standard, addresses the other expert's methodology) within the context of a written trial transcript. The presence of opposing expert testimony caused jurors to be skeptical of all expert testimony rather than sensitizing them to flaws in the other expert's testimony. Jurors rendered more guilty verdicts when they heard opposing expert testimony than when opposing expert testimony was absent, regardless of whether the opposing testimony addressed the methodology of the original expert or the validity of the original expert's testimony. Thus, contrary to the assumptions in the Supreme Court's decision in Daubert, opposing expert testimony may not be an effective safeguard against junk science in the courtroom.

The authors examined whether expert testimony serves an educational or a persuasive function. Participants watched a simulated sexual abuse trial in which the child witness had been prepared for her testimony (i.e., she was calm, composed, and confident) or unprepared (i.e., emotional, confused, and uncertain). The trial contained different levels of expert testimony: none, standard (i.e., a summary of the research), repetitive (i.e., standard testimony plus a 2nd summary of the research), or concrete (i.e., standard testimony plus a hypothetical scenario linking the research to the case facts) testimony. Repetitive testimony bolstered the child's testimony, whereas concrete and standard testimony did not. Concrete testimony sensitized jurors to behavioral correlates of sexual victimization; standard and repetitive testimony desensitized jurors to these correlates. Implications for the use of procedural innovations in sexual abuse trials are discussed.

Two studies examined the effectiveness of the Mac-a-Mug Pro, a computerized facial composite production system. In the first study, college freshmen prepared from memory composites of other students and faculty from their former high schools. Other students who had attended the same high schools could not recognize the composites of either students or faculty members when the composites of individuals known to them (n = 10) were mixed with composites of a large number (n = 40) of strangers. Neither preparer familiarity with the target, preparer-assessed composite quality, nor viewer familiarity predicted composite recognition. Study 2 indicated that naive witnesses who viewed the composites could not select the people depicted in the composites from photo lineups (1 target and 4 foils). The results raise questions about the efficacy of composite systems as tools to promote recognition of suspects in criminal contexts.

This study examined whether need for cognition (NC) moderated jurors' sensitivity to methodological flaws in expert evidence. Jurors read a sexual harassment trial summary in which the plaintiff's expert presented a study that varied in ecological validity, general acceptance, and internal validity. High NC jurors found the defendant liable more often and evaluated expert evidence quality more favorably when the expert's study was internally valid vs. missing a control group; low NC jurors did not. Ecological validity and general acceptance did not affect jurors' judgments. Ratings of expert and plaintiff credibility, plaintiff trustworthiness, and expert evidence quality were positively correlated with verdict. Theoretical implications for the scientific reasoning literature and practical implications for trials containing psychological science are discussed. Mitchel) for granting us access to the jury pool. We also thank dissertation committee members Brian Cutler and Ronald Fisher for their helpful suggestions.