University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Court Review: The Journal of the American Judges Association American Judges Association 2012 Memory Conformity Between Eyewitnesses Fiona Gabbert University of Abertay Dundee, [email protected] Daniel B. Wright Florida International University, [email protected] Amina Memon Royal Holloway University of London, [email protected] Elin M. Skagerberg Tavistock Centre, [email protected] Kat Jamieson University of Abertay Dundee, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/ajacourtreview Gabbert, Fiona; Wright, Daniel B.; Memon, Amina; Skagerberg, Elin M.; and Jamieson, Kat, "Memory Conformity Between Eyewitnesses" (2012). Court Review: The Journal of the American Judges Association. 382. https://digitalcommons.unl.edu/ajacourtreview/382 This Article is brought to you for free and open access by the American Judges Association at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Court Review: The Journal of the American Judges Association by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Memory Conformity Between Eyewitnesses Fiona Gabbert, Daniel B. Wright, Amina Memon, Elin M. Skagerberg, & Kat Jamieson ore than a century of psychology research has shown a description of an accomplice when McVeigh had actually that memory is fallible. People’s memory can be entered the shop alone? It is likely that the confident witness Minfluenced by information encountered after an inci- unintentionally influenced the others, leading them to report dent has been witnessed—so-called postevent information, or that they also recalled a second man.3 Indeed, the witnesses PEI.1 In everyday life, one of the most common ways to admitted in testimony that they had discussed their memories encounter PEI is when individuals who have shared the same before being questioned by investigators.4 experience discuss this with one another. In the case of wit- The more recent high-profile murder investigation of the nessing a crime, individuals might be particularly motivated Swedish foreign minister, Anna Lindh, in September 2003, to discuss what happened, and who was involved, because of provides a second example. Witnesses were all placed together the significance of the event. The PEI encountered during this in a small room to prevent them leaving the scene of the crime discussion with a co-witness might be largely consistent with before being interviewed. The witnesses later admitted to dis- one’s own memories of the event. However, some details may cussing the event with one another while in the room.5 During differ either because one witness has remembered something these discussions, one witness mentioned to the others present differently, has paid attention to different details, or has sim- that the perpetrator wore a camouflage-patterned military ply made an honest mistake in his or her own account. A com- jacket. As a result, a number of these witnesses subsequently mon finding within eyewitness-memory literature is that reported this clothing detail to the investigating officers. This exposure to PEI that is inconsistent with a person’s own mem- description was used in an immediate search for the perpetra- ory can affect the ability to subsequently report details of the tor in the surrounding area, and also featured in the release of originally encoded event.2 a national police alert. This detail, however, was incorrect, The following two examples show how the memory report resulting in wasted police time and resources. Footage from of one witness may influence that of another witness during a surveillance cameras showed that the killer, Mijailo Mijailovic, discussion. Witness evidence in the Oklahoma bombing inci- was in fact wearing a grey hooded sweatshirt. Given that wit- dent of 1995 came from employees working at Elliot’s Body nesses were free to discuss the incident with each other at Shop where the perpetrator, Timothy McVeigh, rented the some length, it is reasonable to assume that co-witness influ- truck used in the bombing. McVeigh was arrested for the mass ence was the main source of error in the immediate stages of murder but there was a question as to who, if anyone, was his this investigation.6 accomplice when he rented the truck. One of the three These examples highlight that when witnesses discuss their employees working in the shop that day claimed, with some memories, their accounts of the witnessed event can become confidence, that McVeigh was accompanied by a second man. similar, and hence, seemingly corroborative. This phenome- Initially, the other witnesses gave no description of this alleged non is referred to as “memory conformity.”7 When memory accomplice. However, later they too claimed to remember conformity occurs in a formal investigation, whether criminal details of a second person. This led to a costly police hunt for or civil, there can be serious and costly implications for any a person the FBI now believes does not exist. Several months subsequent investigations. Of course, not all PEI shared later, the witness who had confidently indicated the presence between witnesses will be misleading. There is the potential for of an accomplice acknowledged that he may have been recall- witnesses to share accurate PEI, which can have positive ing another customer. So, why did all three witnesses provide effects on memory.8 Furthermore, collaborative remembering Footnotes AND REMEMBERS) (2001). 1. E.g., Fiona Gabbert et al., Memory Conformity: Can Eyewitnesses 4. Memon & Wright, supra note 3. Influence Each Other’s Memories for an Event?, 17 APPLIED 5. PärAnders Granhag, Karl Ask & Anna Rebelius, “I Saw the Man COGNITIVE PSYCHOL. 533 (2003). Who Killed Anna Lindh,” A Case Study of Eyewitness Descriptions, 2. See Michael. S. Ayers & Lynne. M. Reder, A Theoretical Review of 15TH EUROPEAN CONFERENCE ON PSYCHOLOGY & LAW, Vilnuis, the Misinformation Effect: Predictions from an Activation-Based Lituania (June 2005). Memory Model, 5 PSYCHONOMIC BULL. & REV. 1-21 (1998); 6. Id. Jacqueline E. Pickrell et al., The Misinformation Effect, COGNITIVE 7. E.g., Daniel B. Wright et al., Memory Conformity: Exploring ILLUSIONS: A HANDBOOK ON FALLACIES AND BIASES IN THINKING, Misinformation Effects When Presented by Another Person, 91 BRIT. JUDGMENT AND MEMORY 345 (Rütiger F. Pohl ed., 2004). J. PSYCHOL. 189 (2000). 3. Amina Memon & Daniel B. Wright, Eyewitness Testimony and the 8. See Helen M. Paterson & Richard I. Kemp, Comparing Methods of Oklahoma Bombing, 12 THE PSYCHOLOGIST 292 (1999); D.L. Encountering Post-Event Information: The Power of Co-Witness SCHACTER, THE SEVEN SINS OF MEMORY (HOW THE MIND FORGETS Suggestion, 20 APPLIED COGNITIVE PSYCHOL. 1083 (2006). 36 Court Review - Volume 48 can help people remember details that would otherwise have group of people (often just a “[A] large amount been forgotten. However, the notion that group members can pair) some set of stimuli or an “cross-cue” one another to produce new memories that would event, have the people interact of research has not have been generated if remembering alone is not supported with each other, and then indi- shown that people by research,9 even when attempts are made to increase the vidually test each person about are easily opportunity for cross-cuing.10 In contrast, a large amount of what he or she remembers. One research has shown that people are easily influenced by mis- critical decision memory-con- influenced by leading PEI encountered from another person.11 formity researchers have to misleading Criminal events are often witnessed by more than one per- make is whether to have the [postevent] son,12 and discussion between witnesses is common.13 For PEI delivered from one partici- example, an Australian survey of students who had witnessed pant to another, or to have a information a crime found that where multiple witnesses had been present, confederate (a person working encountered from 86% of respondents admitted to discussing the event with a co- for the researcher but pretend- another person.” witness.14 More recently, a U.K. survey of eyewitnesses who ing to be a participant) deliver were interviewed after viewing a lineup revealed that the the PEI. When participants are majority had witnessed the crime with other people present, presenting PEI to each other, it is common to show them and more than half of these people had discussed the event slightly different materials so that disagreements are likely. with a co-witness.15 Although it is best practice for the police Consider one study that used this approach:17 Two versions of to encourage witnesses to the same event not to discuss their a crime event were made, each containing the same sequence of memories for fear of evidence contamination, it is likely that events but filmed from different angles to simulate different wit- many witnesses do enter into discussions about the event both ness vantage points. The different viewing angles allowed the before the police arrive and afterward, even if police warned participants to see two different critical features of the event. them not to do so. In such circumstances investigators and After viewing, participants had an opportunity to remember the jurors may subsequently attach a false corroborative value to event together, where the critical features were often discussed. any consistencies between witness statements obtained or any An individual memory test followed and 71% of witnesses who evidence given in court thereafter, when the evidence may be had discussed the event reported at least one of the two erro- contaminated if the witnesses had discussed their memories neous critical details acquired from their co-witness. before being interviewed by the police. Using a confederate has some advantages over other meth- ods because well-trained confederates can impart the same EXPERIMENTAL RESEARCH ON MEMORY CONFORMITY PEI, in the same manner, to all participants during the course There are different approaches to studying memory.16 As of a discussion.