Exposure to misleading post-event information can result in impaired memory for the original event. Two theoretical mechanisms (i.e., retrieval blocking and source misattribution) have been proposed as explanantions for the occurrence of the misinformation effect. The impact of context on the occurrence of these errors has been examined to determine if changing the context between events reduces the misinformation effect. Previous findings indicate that context plays a different role in each of these mechanisms; however, experimental differences in the paradgms used to examine retrieval blocking and source misattribution have made comparisons between these mechanisms difficult. The present study examined the role of context in eyewitness memory using the same materials, manipulations, and procedures to determine if context does, in fact, have a different impact on these mechanisms. Results indicate that changing the context between events reduces the occurrence of source misattribution but does not ameliorate the impact of retrieval blocking.

According to the misinformation effect, exposure to misleading post-event information typically impairs memory for the original event. Such findings are generally obtained in the laboratory using the misinformation paradigm. One component of the typical misinformation paradigm is that most of the post-event information corresponds with the event information, implying that the context surrounding the misinformation is the same as that of the original event. The present experiments investigated the role of such implication by presenting the experimental conditions with misleading items in a narrative that differed from the original event (a slide show) to varying degrees; both the location of the event and the persons described were varied. A significant misinformation effect was obtained regardless of implication condition. Even when a relationship between the witnessed event and post-event narrative was not implied, memory was impaired by the presence of misleading information. The findings are discussed in terms of retrieval blocking.

Erroneous suggestions can add to or contradict people’s memories for previously witnessed event details. Researchers have also investigated a different kind of erroneous suggestion in which details from a target event that had actually been witnessed are erroneously suggested to not have transpired in the event. This phenomenon is referred to as the suggested invisibility effect. Previous research examining suggested invisibility has not thoroughly examined the mechanisms underlying the effect. That is, does not reporting previously witnessed event details reflect demand characteristics or genuine memory impairments? The current dissertation research was motivated by such questions. In a newly developed paradigm, 5 experiments examined suggested invisibility and its accompanying subjective memory. Subjects watched a crime video and 2 days later read three hand-written simulated witness testimonies. Each testimony (a) stated that two event details were not visible in the video (though they in fact were clearly displayed) and (b) mentioned two other details in broad generic terms. Subjects then completed a final memory test to assess their memory for the original crime video. Experiment 1 produced the basic effect, showing that subjects were significantly less likely to report witnessed details when they had been erroneously suggested to not have been visible compared to control details. Experiment 2A was conducted to further examine the basis of suggested invisibility, however, many subjects expressed disbelief in the testimonies and this resulted in null effects. Subsequent experiments enhanced the plausibility of the testimonies. Experiment 2B amended the rationale to subjects for reading the lengthy testimonies and replicated the suggested invisibility effect; Experiment 3 embedded suggestions of invisibility in response to cued-recall questions rather than in lengthy narratives; and, Experiment 4 presented subjects with a transcript of an interview between a witness and an experimenter. In both Experiments 3 and 4, robust effects of suggested invisibility were only attained with naïve subjects who claimed to not have been suspicious of the experimental manipulation. When suggested invisibility was observed subjects’ confidence levels were similar to that of control details, suggesting that sometimes subjects were genuinely confident in not having witnessed previously seen details. Collectively, these findings support the idea that memories can be swayed in the direction of erroneous suggestions that render false reports of not having seen previously witnessed details. / Graduate

In a large body of research, Elizabeth Loftus (1975) first illuminated major concerns about the inaccuracy of eyewitness accounts. The primary goal of the present research was to test whether training regarding common eyewitness mistakes and witness suggestibility could improve eyewitness accuracy. The experimental group watched a presentation on research conducted by Elizabeth Loftus (1975) on eyewitness testimony and suggestibility during a Psychology course. Afterwards, an actor interrupted the classroom and had a discussion with the teacher. Students were asked a series of questions about the disruption. Some of the questions were leading and suggested certain things about the disruption that were inaccurate. After the misleading questions were asked, students were instructed to write a brief summary of what they saw. One week later, the students were asked direct questions about the disruption. A control group did not receive the presentation on eyewitness testimony, but witnessed the exact same event as the experimental group and followed the same procedure. The results suggest that participants who were trained were not as influenced as participants in the control group. Additionally, students in the control group reported the actor's behavior as more threatening than did the experimental group. This research not only adds to the existing literature, but has the potential to improve current eyewitness identification procedures in order to strengthen our justice system.

This paper explores research on the misinformation effect and hypothesizes a new explanation for the occurrence misinformation effect. Current psychological theories states the misinformation effect occurs when memories are skewed by the presentation of new information after an initial event. This effect has been tested in a multitude of ways, including testing words lists, pictures, colors, and change blindness. Socially, the misinformation effect has been used to explain the inaccuracies of eyewitness testimony. The current judicial system relies on the fallible memory of people and has wrongfully imprisoned numerous innocents. The purpose of this research is to show the misinformation effect is not a problem with memory storage and retrieval, but rather a product of selective stimulus control.

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Memory conformity effects occur when witnesses report misleading suggestions they learned about from another witness. Using a new paradigm the present thesis investigated whether what subject-witnesses report about an event also implies what they personally remember or know about that event. Subjects were tested in pairs, with each member of a pair shown a different version of a video using the MORI technique. There were critical details (e.g., theft of an iPod) in each of the following conditions: visible to only one member of each subject spair, visible to both members of the pair, and not visible to either member of the pair. Pairs subsequently completed a questionnaire together to remember details from the video. Subjects then individually completed a similar questionnaire. A source monitoring and subjective experiences test revealed that co-witness discussion does not necessarily lead people to experience illusory recollections for details they did not witness themselves.

Syftet med denna studie var att undersöka hur studenters minnesprestation påverkas av missvisande information, om polisstudenters minnesprestation skiljer sig signifikant från psykologstudenters samt om säkerheten är högre på de betydande objekten, det vill säga de frågor som blivit manipulerade med missvisande information, än övriga frågor. Ett experiment genomfördes där urvalet bestod av polisstudenter (n = 45) och psykologstudenter (n = 19) på Umeå universitet. Samtliga 64 deltagare, med en medelålder på 24.4 år, fick se en video där ett fiktivt brott begicks för att sedan läsa ett narrativ av videon, som antingen innehöll missvisande eller korrekt information, och slutligen fylla i en enkät med flervalsfrågor relaterat till videon. En variansanalys (ANOVA) användes för att analysera deltagarnas svar som visade på att det förelåg en missinformationseffekt, det vill säga att deltagarna som fått missvisande information blev påverkade av det, samt att deltagarna som blivit tilldelade det missvisande narrativet rapporterade lägre säkerhet i sina svar än de som blivit tilldelade det korrekta narrativet, båda dessa oberoende av deltagarnas utbildning. Slutsatsen som kan dras utifrån detta är att minnesprestation och säkerhet påverkas av missvisande information, däremot verkar utbildning inte vara en prediktor för detta. Framtida forskning bör genomföra liknande studier med större urval då detta ansågs vara en brist i denna studie. / The purpose of this study was to investigate how students' memory performance is affected by misleading information, if police students' memory performance differs significantly from psychology students and if confidence is higher on the critical items, meaning the questions which have been manipulated with misinformation, than other questions. An experiment was conducted where the sample consisted of police students (n = 45) and psychology students (n = 19) at Umeå University. All 64 participants, with a mean age of 24.4 years, watched a video of a fictional crime, then read a narrative of the video, which contained either misleading or accurate information, and finally completed a multiple-choice survey related to the video. Ananalysis of variance (ANOVA) was used to analyze participants' responses which showed that there was a misinformation effect, meaning that the participants who received misleading information were affected by it, and that participants assigned to the misleading narrative reported lower confidence in their responses than those assigned to the correct narrative, both of these independent of the participants' education. The conclusion that can be drawn from this is that memory performance and confidence are affected by misleading information, however, education does not seem to be a predictor of this. Future research should conduct similar studies with a bigger sample as this was considered a shortcoming in this study.