John W. Turtle

From the Lab to the Police Station A Successful Application of Eyewitness Research

The U.S. Department of Justice released the first national guide for collecting and preserving eyewitness evidence in October 1999. Scientific psychology played a large role in making a case for these procedural guidelines as well as in setting a scientific foundation for the guidelines, and eyewitness researchers directly participated in writing them. The authors describe how eyewitness researchers shaped understanding of eyewitness evidence issues over a long period of time through research and theory on system variables. Additional pressure for guidelines was applied by psychologists through expert testimony that focused on deficiencies in the procedures used to collect the eyewitness evidence. DNA exoneration cases were particularly important in leading U.S. Attorney General Janet Reno to notice the eyewitness literature in psychology and to order the National Institute of Justice to coordinate the development of national guidelines. The authors describe their experience as members of the working group, which included prosecutors, defense lawyers, and law enforcement officers from across the country.

The Undoing of Scenarios

Scenarios with dramatic outcomes often evoke counterfactual thinking, mentally undoing that outcome by mutating events in the causal scenario and thereby allowing for the mental simulation of new outcomes. Is Experiment 1, we manipulated the order of four events in a scenario. Each of these events could be mutated to alter the outcome, and each event was described as having caused the eveni that followed it People preferred to change the first event and showed no preference for changes to the subsequent events. We proposed that perceived mutability of an event is constrained by the existence of prior events that are believed to have caused the event. Experiment 2 examined characteristics of the events themselves, rather than their order, that affect their mutability. When these were framed as a norm, people were relatively unlikely to mutate the event in order to undo the outcome, instead preferring to mutate the exceptions. The norm or exception status of other events in the scenario did not affect the mutability of a focal event. Discussion includes the conditions that naturally trigger counterfactual thinking and the role of counterfactual thinking in affective reactions.

Eyewitness Identification: The Importance of Lineup Models

A detailed analysis is made of lineup models for eyewitness identification. Previous treatments of eyewitness identification have nol distinguished between the all-suspecl model and the single-suspect model. The single-suspect model allows for the occurrence of foil identifications, a know n-error category, whereas the all-suspect model does not. A Bayesian analysis of posterior probabilities of the guilt of a given suspect under various prior probabilities shows that the all-suspect model maj be more or less diagnostic than the single-suspect model depending on the extent to which the use of suspects rather than foils increases the prior likelihood that the actual target is in I he lineup. On the other hand, the lineup-wise error rate (which is the likelihood that any suspect will be falsely identified) is considerably higher with the all-suspecl lineup. Field data show that the all-suspect lineup is sometimes used by police departments, and some data suggest that police do not appreciate the distinction between the two models with regard to lineup-wise error rates. It is recommended that either a mixed model or a preceding blank lineup be used to replace all-suspecl models in actual cases.

Adult Eyewitness Testimony: Actual victims and witnesses to robbery and fraud: An archival analysis

Although there are some exceptions (for example, Cutshall & Yuille, 1989; Fisher, Geiselman, & Amador, 1989; Read, Tollestrup, Hammersley, McFadzen, & Christensen, 1990; Sporer, 1992; Yuille & Cutshall, 1986) most of the research in the field of eyewitness memory has been laboratory based. This overreliance on laboratory research has left the field open to challenges of the external validity of the research (for example, McCloskey & Egeth, 1983; McKenna, Treadway, & McCloskey, 1992; Yuille & Wells, 1991) and has led to the recognition of a need for more diverse methods of learning about eyewitness memory (for example, Davies, 1990; Yuille & Wells, 1991). In response to this deficit of diversity, this chapter reports the results of an inquiry into actual police case files. We realize that file research lacks the experimental control of laboratory studies. Our data from police case files, however, represent a degree of realism and a range of variables impossible to simulate in a laboratory setting. We are able to provide information on a number of important topics such as the characteristics of actual eyewitnesses, the amount of detail in eyewitnesses’ descriptions of suspects, the accuracy of these descriptions, types of identification tasks employed, the prevalence and accuracy of eyewitness identification, and the weapon focus effect. We believe that the discrepancies and similarities between our results and laboratory research will be informative and serve to point out instances when research conducted in one context can apply in another. The laboratory context has customarily cast eyewitnesses into a uniform role (Yuille & Tollestrup, in press).

The Perceived Credibility of Child Eyewitnesses: What Happens When They Use Their Own Words?

How do triers-of-fact judge the credibility of children versus that of adults as eyewitnesses? We argue that there are two processes to consider in answering this question and that previous research has examined only one of these processes, namely, biases and stereotypes possessed by triers-of-fact. The first process, and the one that separates our’s from previous research, involves the inferences about accuracy or believability that triers-of-fact discern from the qualities of the testimony itself. If a child appears to have little confidence and pauses at inappropriate points in response to questions, for example, that child might be judged to be less credible than an adult who is more confident or pauses less frequently. On the other hand, a child who appears more confident than an adult might be judged to be more credible than the adult. In other words, we propose that the factors that seem to drive the credibility of adult eyewitness testimony (such as confidence; see Wells, Ferguson & Lindsay, 1981) also drive the credibility of child eyewitness testimony. If children and adults differ systematically on these quality-of-testimony variables, their testimony should be differentially credible as well.

Setting the Stage for Psychological Research on the Child Eyewitness

Although it is true that psychologists have shown an interest in the eyewitnessing capabilities of children throughout this century (e.g., Binet, 1900, 1911; Dauber, 1912; Marbe, 1913; Mehl, 1912; Stern, 1910, 1939), we argue that psychological research on the child eyewitness is nascent. With the exception of Binet’s studies on suggestibility, which were somewhat narrow and restricted in focus, research on the child eyewitness did not receive systematic treatment until quite recently. The birth of systematic approaches to the study of child eyewitnesses in the 1980s probably is due to two primary factors: the rapid development of a psychological literature on eyewitness testimony in general (marked by books by Clifford & Bull, 1978; Loftus, 1979; Wells & Loftus, 1984; Yarmey, 1979) and the contemporary salience of children as victims of crime. The development of an eyewitness testimony literature within psychology has facilitated the study of child eyewitnesses by enhancing awareness of the fallibility of eyewitnesses, refining paradigms for experimentally investigating eyewitness variables, and opening the door to applying the research results (e.g., via expert testimony). The salience of the child eyewitness as a special concern has been motivated in part by the dramatic increase in awareness that children are vulnerable and frequent victims of crime—especially in the area of sexual assault. In light of the pressing need to further our understanding of children’s testimony, this chapter outlines a number of psycholegal variables that require further investigation so that more information can be made available to those responsible for constructing a policy to handle the child-witness’ testimony.

Logic and Research Versus Intuition and Past Practice as Guides to Gathering and Evaluating Eyewitness Evidence

Psychologists have conducted extensive research and devoted substantial thought to the memory, cognition, decision-making, logic, and human interaction components of eyewitness evidence. It is fortunate that much of that work has been formally recognized by law enforcement and the legal community and used as the basis for procedure and policy changes with regard to how eyewitness evidence is collected and evaluated. The authors discuss reasons that some segments of law enforcement, the legal community, and the public resist these research findings (e.g., by seeing psychologys role as a way to discredit eyewitness evidence or being committed to established procedures that have no empirical support). The authors also address gaps between these common misconceptions and what the psychology research perspective has to offer, in an effort to gain even more support for research- and logic-based recommendations concerning eyewitness evidence.