Carolyn Semmler

How Variations in Distance Affect Eyewitness Reports and Identification Accuracy

Witnesses observe crimes at various distances and the courts have to interpret their testimony given the likely quality of witnesses’ views of events. We examined how accurately witnesses judged the distance between themselves and a target person, and how distance affected description accuracy, choosing behavior, and identification test accuracy. Over 1,300 participants were approached during normal daily activities, and asked to observe a target person at one of a number of possible distances. Under a Perception, Immediate Memory, or Delayed Memory condition, witnesses provided a brief description of the target, estimated the distance to the target, and then examined a 6-person target-present or target-absent lineup to see if they could identify the target. Errors in distance judgments were often substantial. Description accuracy was mediocre and did not vary systematically with distance. Identification choosing rates were not affected by distance, but decision accuracy declined with distance. Contrary to previous research, a 15-m viewing distance was not critical for discriminating accurate from inaccurate decisions.

Using a Flow-chart to Improve Comprehension of Jury Instructions

The effectiveness of providing a flow-chart to supplement traditional methods of delivering jury instructions was investigated using an experimental design. Two hundred and thirty-four mock-jurors listened to a case summary and judges instructions (in one of eight formats) regarding the law of self-defence. They were then required to (a) write a description of the main elements of self-defence, (b) render a judgment as to the applicability of self-defence to the case heard, and (c) apply their knowledge to four novel scenarios. Mock-jurors performed relatively poorly when describing self-defence elements and in applying them to the case heard and the novel scenarios. Having a flow-chart for reference while deliberating about the case facilitated descriptions of the criteria for self-defence, particularly for the elements of self-defence law that were most poorly described. Suggestions for structuring presentation of information to further improve juror comprehension were provided.

The Role of Estimator Variables in Eyewitness Identification.

Estimator variables are factors that can affect the accuracy of eyewitness identifications but that are outside of the control of the criminal justice system. Examples include (1) the duration of exposure to the perpetrator, (2) the passage of time between the crime and the identification (retention interval), (3) the distance between the witness and the perpetrator at the time of the crime. Suboptimal estimator variables (e.g., long distance) have long been thought to reduce the reliability of eyewitness identifications (IDs), but recent evidence suggests that this is not true of IDs made with high confidence and may or may not be true of IDs made with lower confidence. The evidence suggests that though suboptimal estimator variables decrease discriminability (i.e., the ability to distinguish innocent from guilty suspects), they do not decrease the reliability of IDs made with high confidence. Such findings are inconsistent with the longstanding “optimality hypothesis” and therefore require a new theoretical framework. Here, we propose that a signal-detection-based likelihood ratio account—which has long been a mainstay of basic theories of recognition memory—naturally accounts for these findings.

The Dynamic Interaction Between Eyewitnesses and Interviewers: The Impact of Differences in Perspective on Memory Reports and Interviewer Behavior

Despite myriad possible differences in perspectives brought to an investigative interview by eyewitnesses and interviewers, little is known about how such differences might affect eyewitness memory reports or interviewer behavior. Two experiments tested the impact of such differences in a dynamic interaction paradigm in which participants served as eyewitnesses and interviewers. In Experiment 1 (N = 38 pairs), reporting goals for eyewitnesses and interviewers were manipulated in a factorial design, with participants instructed to provide or obtain either as much information as possible or only accurate information. Matching interviewer-interviewee instructions promoted accurate reporting, regardless of the actual content of the instructions. In Experiment 2 (N = 45 pairs), access to information about corroborating eyewitness identifications was manipulated in a factorial design. Corroborating information affected interviewers, but not eyewitnesses. When interviewers did not have access to corroborating information, they provided more negative feedback, and there was a trend toward interrupting more and asking more yes/no questions. These experiments indicate that differences in perspective can have effects on both the content of a witnesss report and the behavior of an interviewer. The potential for differences in perspective should be considered in research on protocols intended to maximize eyewitness report accuracy.

The effect of the proportion of mismatching trials and task orientation on the confidence-accuracy relationship in unfamiliar face matching

Unfamiliar, one-to-one face matching has been shown to be error-prone. However, it is unknown whether there is a strong relationship between confidence and accuracy in this task. If there is, then confidence could be used as an indicator of accuracy in real-world face matching settings such as border security, where the objectively correct decision is typically unknown. Two experiments examined the overall confidence–accuracy relationship, as well as the relationship for positive (match) and negative (mismatch) decisions. Furthermore, they tested whether these relationships were affected by factors relevant to applied face matching settings: the proportion of mismatching trials (PMT), and the task orientation of the decision-maker (look for matches, or look for mismatches). Both calibration analyses and signal detection methods were applied to assess performance. The results showed that confidence can have a high correspondence with accuracy overall, regardless of task orientation but with small effects of PMT. Thus, confidence is promising as an indicator of accuracy in face matching. However, PMT systematically produces large detrimental effects on the confidence–accuracy relationships for positive and negative decisions, when considered separately. Signal detection measures help with understanding these effects and proposing future research directions for improving the relationships.

The Impact of State and Trait Anger on Processing of Evidential Inconsistencies

The courtroom can be an emotional place, and these emotions may impact on a jurors ability to process and evaluate evidence. This study investigated the effects of mock-jurors’ state and trait anger on the detection of evidential inconsistencies. Community members eligible for jury duty (N = 123) were randomly assigned to hear one of four audio trials differing in evidence consistency and emotion-inducing content. State anger increased endorsement of guilty verdicts, and angry mock-jurors were more careful processors of evidence, detecting more inconsistencies and recalling significantly more trial details. The results lend support to motivational theories of emotional influence on information processing.