"Eyewitnesses' Retrospective Reports on External Influences" Gary L. Wells, PI
The legal system relies heavily on eyewitnesses to help convict perpetrators and to free innocents from suspicion. A primary method for doing this is to use a photographic lineup in which a suspect's photo is placed among filler photos and the eyewitness is asked to identify which of the photos, if any, is of the perpetrator. Scientific experiments as well as studies of actual cases of convictions of innocent people, however, reveal that eyewitnesses are prone to error under certain conditions. In particular, eyewitnesses are easily influenced by external factors, such as suggestive pre-lineup instructions, unintentional cues from the lineup administrator as to which person to select, and comments that bolster the confidence of the eyewitness after the selection. Courts have long assumed that any such influences are readily discoverable by merely questioning the eyewitness as to whether these suggestive influence events occurred and, if so, whether they were influenced by the suggestive event. The experiments that will be conducted are designed to test whether eyewitnesses can recall such suggestive events and whether they can accurately report on whether the suggestive events influenced their responses. Participants will view simulated crimes and then be subjected to various suggestive events that lead them to make mistaken identifications from photo lineups. The actual impact of the suggestive events will be measured by comparing their identification decisions (and their confidence) to participants who were not subjected to the suggestive events. Either immediately or seven days later the participant-witnesses will be asked to recall any suggestive events. They will then be told about the suggestive event and asked what their identification decision and confidence would have been had the suggestive event not occurred. It is expected that participant-witnesses will have difficulty recalling the suggestive event, especially after seven days. In addition, it is expected that participant-witnesses will greatly underestimate the impact that the suggestive event had on their identification decisions and confidence. The results are expected to have strong implications for the legal system's reliance on eyewitnesses to report suggestive influences and provide a new incentive for the legal system to take measures to eliminate the suggestive events from occurring in the first place. In addition, these experiments will shed new light on our understanding of the limits to people's abilities to self-report on the factors that affect their judgments and decisions.
