Abstract
An eyewitness’s memory of an event is a persuasive tool in the criminal justice system. However, when eyewitnesses are exposed to incorrect post-event information, or misinformation, it can alter the accuracy of their reports. Two of the most common sources of misinformation are co-witness discussions and investigative interviews. Our goals in conducting the present study were threefold: first, to explore whether misinformation from a co-witness is particularly strong relative to misinformation from an interviewer; second, to investigate whether there is a cumulative effect when misinformation is received from both of these sources; and third, to assess whether the answer to these two questions differs as a function of witness age. To investigate these questions, pairs of children (n = 44), adolescents (n = 50), and adults (n = 44) who knew each other before participating were shown two different versions of a movie using the MORI (Manipulation of Overlapping Rivalrous Images) technique. After watching the movie, participants were led through a discussion with their co-witness before being interviewed individually by the experimenter. For each critical detail in the movie, participants were either misled by their co-witness, the interviewer, both of these sources, or neither of these sources. Finally, individual participants completed a 20-item multi-choice Film Memory Questionnaire. Exposure to interviewer misinformation alone significantly reduced the memory report accuracy of all three age groups. In contrast, exposure to co-witness misinformation alone significantly reduced the memory report accuracy of those in the adolescent group only. We did not find evidence for an additive effect when participants were exposed to misinformation from both their co-witness and the interviewer. It is possible that at least some of the social cues that have been purported as reasons for the potency of the co-witness misinformation effect are also present during an investigative interview.