Effects of different types of forensic information on eyewitness’ memory and confidence accuracy

This study investigated eyewitnesses’ memory and confidence accuracy for action information (what happened at the crime scene), and detail information (descriptions of persons, objects, time and place). In Experiment 1, 89 participants watched a film and participated in one of four conditions: Laboratory discussion, Family discussion, Retell and Control, the first three with five meetings each. Three weeks later all participants open free recalled the events, and confidence judged their answers. The participants showed better free recall and confidence accuracy for action than for detail information. Participants in the two discussion conditions and in the Retell condition recalled more items and those in the Lab-discussion and Retell conditions more correct items for action information, than those in Control group. However, the four conditions did not differ for proportion correct of all action items recalled and confidence accuracy for action items. In brief, Experiment 1 showed that witness discussions and retellings of the experienced event with others improved recall for action information but had had no, or small, effects on confidence accuracy. Experiment 2 investigated recall and confidence accuracy performance for action and detail information using focused questions. Seventy-seven participants watched a film, answered and confidence judged 63 questions about action and detail information about the events. Again, participants showed better memory and confidence accuracy for action information. Overall, the results indicate that, for both free recall and focused questions, witnesses’ recall and confidence accuracy is better for action information than for detail information, thus extra precaution is needed in the forensic system when detail information from witnesses is considered.