Eyewitness testimonies : The memory and meta-memory effects of retellings and discussions with non-witnesses

Sammanfattning: This thesis investigated the effects of eyewitnesses retellings and discussions with non-witnesses on the eyewitness memory and meta-memory judgments. In Study I, the effect of eyewitness discussions with non-witnesses (persons who had not experienced the event) on eyewitness memory and meta-memory realism for the overall information about an event was investigated. The results suggest that discussions of an experienced event may reduce some of the beneficial memory and meta-memory effects caused by mere retellings, but may not have great negative effects compared to a control condition. Analysis of the type of questions asked suggests listeners ask more about the peripheral details as compared with the central details. In a follow-up study to study I conducted a year later participants in the Retell condition no longer showed evidence of the memory and meta-memory benefits evident at the original final test after about 24 days. However, participants in the Retell condition recalled a higher number of correct items than participants in the Control condition. In Study II, the effect of eyewitness discussions with non-witnesses on eyewitness memory and meta-memory realism for different types of information was investigated. The different types of information were Forensically central, Forensically peripheral, and Non-forensic information. These are types of information that the police may ask at the beginning of a crime investigation. The results from the two experiments showed that participants had better memory and meta-memory realism for Forensically central and Non-forensic information than for Forensically peripheral information. Moreover, participants in the four conditions were equally capable of distinguishing between correct and incorrect items. Further, in Experiment 1 participants in conditions involving retelling and discussing the event reported more total number and number of correct Forensically central items as compared to the Control condition. Study III investigated if retellings and discussions would cause more reminiscence and hypermnesia than mere retellings. The results showed that discussions indeed cause more reminiscence and hypermnesia over the five sessions as compared to mere retellings. The results also showed that the number of times a piece of in- formation was repeated over the sessions was associated with a higher probability for that piece of information being retrieved at the final recall. Interestingly, if the information was retold or discussed in an earlier or later session did not predict if this information would be reported in the testing session or not. Last, the results showed that the forensically peripheral information, but not forensically central information was affected by the reiteration effect (i.e., the effect that confidence tends to increase when a person asserts the same statement many times). This may be due to the fact that the peripheral information was less integrated than the central information.