Brief Exposure to Misinformation Can Lead to Long‐Term False Memories

Do false memories last? And do they last as long as true ones? This study investigated whether experimentally created false memories would persist for an extended period (one and a half years). A large number of subjects (N = 342) participated in a standard three‐stage misinformation procedure (saw the event slides, read the narrations with misinformation, and then took the memory tests). The initial tests showed that misinformation led to a significant amount of false memory. One and a half years later, the participants were tested again. About half of the misinformation false memory persisted, which was the same rate as for true memory. These results strongly suggest that brief exposure to misinformation can lead to long‐term false memory and that the strength of memory trace was similar for true and false memories. Copyright © 2011 John Wiley & Sons, Ltd.     

Comparison of neural activity that leads to true memories,false memories,and forgetting: An fMRI study of the misinformation effect

False memories can occur when people are exposed to misinformation about a past event. Of interest here are the neural mechanisms of this type of memory failure. In the present study, participants viewed photographic vignettes of common activities during an original event phase (OEP), while we monitored their brain activity using fMRI. Later, in a misinformation phase, participants viewed sentences describing the studied photographs, some of which contained information conflicting with that depicted in the photographs. One day later, participants returned for a surprise item memory recognition test for the content of the photographs. Results showed reliable creation of false memories, in that participants reported information that had been presented in the verbal misinformation but not in the photographs. Several regions were more active during the OEP for later accurate memory than for forgetting, but they were also more active for later false memories, indicating that false memories in this paradigm are not simply caused by failure to encode the original event. There was greater activation in the ventral visual stream for subsequent true memories than for subsequent false memories, however, suggesting that differences in encoding may contribute to later susceptibility to misinformation.     

Trace‐strength and source‐monitoring accounts of accuracy and metacognitive resolution in the misinformation paradigm

Two experiments are reported that investigate the impact of misinformation on memory accuracy and metacognitive resolution. In Experiment 1, participants viewed a series of photographs depicting a crime scene, were exposed to misinformation that contradicted details in the slides, and later took a recognition memory test. For each answer, participants were required to indicate whether they were willing to testify (report) their answer to the Court and to rate confidence. Misinformation impaired memory accuracy but it had no effect on resolution, regardless of whether resolution was indexed with confidence‐rating measures (γ correlation and mean confidence) or a report‐option measure (type‐2 discrimination: d′). In Experiment 2, a similar accuracy‐confidence dissociation was found, and the misinformation effect occurred mostly with fine‐grained responses, suggesting that responding was based on recollected details. We argue that the results support source‐monitoring (SM) accounts of accuracy and resolution rather than accounts based on trace strength. Copyright © 2010 John Wiley & Sons, Ltd.     

Treat and trick: A new way to increase false memory

This paper reports a new experimental manipulation that increased false memories 1 month after the manipulation. Mirroring the standard three‐stage misinformation paradigm (original event, misinformation, and test), subjects in the experimental group were first given a colour‐slide presentation of two stories (events), then given an accurate account (instead of misinformation) of the events in narrations, and finally tested for their memory of the original events. One month later, they underwent the standard misinformation paradigm with two new events. The comparison group was given the standard misinformation tasks at both time points. Results showed that the experimental group produced more false memories in the subsequent misinformation paradigm than did the comparison group. We focus on trust and credibility as possible mechanisms underlying this effect. Copyright © 2009 John Wiley & Sons, Ltd.     

Cortisol response and psychological distress predict susceptibility to false memories for a trauma film

For eyewitness testimony to be considered reliable, it is important to ensure memory remains accurate following the event. As many testimonies involve traumatic, as opposed to neutral, events, it is important to consider the role of distress in susceptibility to false memories. The aim of this study was to investigate whether cortisol response following a stressor would be associated with susceptibility to false memories. Psychological distress responses were also investigated, specifically, dissociation, intrusions, and avoidance. Participants were allocated to one of three conditions: those who viewed a neutral film (N?=?35), those who viewed a real trauma film (N?=?35), and a trauma “reappraisal” group where participants were told the film was not real (N?=?35). All received misinformation about the film in the form of a narrative. Participants provided saliva samples (to assess cortisol) and completed distress and memory questionnaires. Cortisol response was a significant predictor of the misinformation effect. Dissociation and avoidance were related to confabulations. In conclusion, following a stressor an individual may differ with regard to their psychological response to the event, and also whether they experience a cortisol increase. This may affect whether they are more distressed later on, and also whether they remember the event accurately.     

Misled subjects may know more than their performance implies

Many studies have demonstrated that subjects exposed to misleading postevent information are likely to report the misinformation with confidence on subsequent tests of memory for the event. The purpose of the present studies was to determine whether subjects exposed to misleading postevent information come to believe they remember seeing the misinformation at the original event. A second question addressed by the present studies is whether exposure to misinformation reduces subjects' ability to remember the source of items they witnessed at the original event. In two experiments, subjects viewed a slide sequence depicting an event, were subsequently exposed to misleading information or neutral information about selected aspects of the event, and were later tested on their memory for the source of original and misleading details. The results showed that exposure to misinformation did not lead subjects to believe they remembered seeing the misinformation, nor did it reduce subjects' ability to accurately identify the source of originally seen details. The same pattern of results was obtained whether subjects were tested immediately (Experiment 1) or after a 1-day delay (Experiment 2). Collectively, the results suggest that subjects may report misinformation even if they know they do not remember seeing it.     

Why misinformation is more likely to be recognised over time: A source monitoring account

Although memory for actual events tends to be forgotten over time, memory for misinformation tends to be retrieved at a stable rate over long delays or at a rate greater than that found immediately after encoding. To examine whether source monitoring errors contribute to this phenomenon, two experiments investigated subjects' memory for the source of misinformation at different retention intervals. Subjects viewed a slide presentation, read a narrative containing misinformation, and, either 10 minutes or 1 week later, completed a recognition test about details seen in the slides and about the source of these details. After the longer retention interval in both experiments, participants were more likely to agree that they had seen misleading information and were also more likely to incorrectly associate the misinformation with the slide event. Theoretical implications of these findings are considered.     

An individual differences approach to the suggestibility of memory over time

We examined how certain personality traits might relate to the formation of suggestive memory over time. We hypothesised that compliance and trust relate to initial acceptance of misinformation as memory, whereas fantasy proneness might relate to integration of misinformation into memory after later intervals (relative to the time of exposure to misinformation). Participants watched an excerpt from a movie—the simulated eyewitness event. They next answered a recall test that included embedded misinformation about the movie. Participants then answered a yes/no recognition test. A week later, participants answered a second yes/no recognition test about the movie (each yes/no recognition test included different questions). Before both recognition tests, participants were warned about the misinformation shown during recall and were asked to base their answer on the movie excerpt only. After completing the second recognition test, participants answered questions from the Neuroticism Extroversion Openness Personality Inventory-3 (McCrae, Costa, & Martin, 2005) and Creative Experiences Questionnaire (Merckelbach, Horselenberg, & Muris, 2001). While compliance correlated with misinformation effects immediately after exposure to misinformation, fantasy-prone personality accounted for more of the variability in false recognition rates than compliance after a 1-week interval.     

False memories in music listening: exploring the misinformation effect and individual difference factors in auditory memory

ABSTRACT

The study of false memory has had a profound impact on our understanding of how and what we remember, as shown by the misinformation paradigm [Loftus, E. F. (2005). Planting misinformation in the human mind: A 30-year investigation of the malleability of memory. Learning & Memory, 12(4), 361–366. doi:10.1101/lm.94705]. Though misinformation effects have been demonstrated extensively within visual tasks, they have not yet been explored in the realm of non-visual auditory stimuli. Thus, the present study aimed to investigate whether post-event information can create false memories of music listening episodes. In addition, we explored individual difference factors potentially associated with false memory susceptibility in music, including age, suggestibility, personality, and musical training. In two music recognition tasks, participants (N?=?151) listened to an initial music track, which unbeknownst to them was missing an instrument. They were then presented with post-event information which either suggested the presence of the missing instrument or did not. The presence of misinformation resulted in significantly poorer performance on the music recognition tasks (d?=?.43), suggesting the existence of false musical memories. A random forest analysis indicated that none of the individual difference factors assessed were significantly associated with misinformation susceptibility. These findings support previous research on the fallibility of human memory and demonstrate, to some extent, the generality of the misinformation effect to a non-visual auditory domain.     

Examining the effects of memory specificity and perceptual load on susceptibility to misleading information

Our study aimed to examine the role of perceptual load in eyewitness memory and susceptibility to misinformation and establish whether trait-based memory specificity protects against misinformation. Participants (n = 264) viewed a video depicting a crime and completed a memory questionnaire immediately afterwards and 1 week later. Memory specificity was measured using the Autobiographical Memory Test (AMT). Higher AMT scores were associated with better memory accuracy. Performance was worse in the high load compared to the low load condition at immediate recall. However, this effect was not seen for every question and load did not influence eyewitness identifications. To test the possibility that load effects were not fully captured by the questionnaire in experiment 1, we conducted a second experiment (n = 120) where we systematically manipulated misinformation about central and peripheral details. We found no effects. Our findings suggest that high perceptual load enhances eyewitness suggestibility, while specific autobiographical memory protects against misinformation.     

Reactions to blatantly contradictory information

In two experiments, subjects were shown a complex event and were later exposed to misinformation about that event. In addition, some subjects received a piece of blatantly contradictory misinformation. Blatant misinformation both was rejected by subjects and caused them to be more resistant to other misinformation that they would ordinarily have been inclined to accept the “spillover” effect. However, delaying the blatant misinformation until the other pieces of false information had already been processed destroyed its ability to make subjects immune to such “ordinary” misinformation. These results are consistent with the idea that subjects incorporate new information into memory at the time it is initially introduced and use this information to update an existing memorial representation.     

Self-relevance enhances susceptibility to false memory

Eyewitness testimony serves as important evidence in the legal system. Eyewitnesses of a crime can be either the victims themselves—for whom the experience is highly self-referential—or can be bystanders who witness and thus encode the crime in relation to others. There is a gap in past research investigating whether processing information in relation to oneself versus others would later impact people's suggestibility to misleading information. In two experiments (Ns = 68 and 122) with Dutch and Chinese samples, we assessed whether self-reference of a crime event (i.e., victim vs. bystander) affected their susceptibility to false memory creation. Using a misinformation procedure, we photoshopped half of the participants' photographs into a crime slideshow so that they saw themselves as victims of a nonviolent crime, while others watched the slideshow as mock bystander witnesses. In both experiments, participants displayed a self-enhanced suggestibility effect: Participants who viewed themselves as victims created more false memories after receiving misinformation than those who witnessed the same crime as bystanders. These findings suggest that self-reference might constitute a hitherto new risk factor in the formation of false memories when evaluating eyewitness memory reports.     

Sleep Increases Susceptibility to the Misinformation Effect

When individuals witness an event and are exposed to misleading postevent information, they often incorporate the misleading information into their memory for the original event, a phenomenon known as the misinformation effect. The present study examined the role of sleep in the misinformation effect. Participants (N = 177) witnessed two events; were exposed to misleading postevent information immediately, 12 hours later the same day, 12 hours later the next day, or 24 hours later; and then took a recognition test. All groups demonstrated the misinformation effect, and this effect was larger in groups with an overnight retention interval. Signal detection analyses revealed that sleep decreased sensitivity. These results suggest that sleep increases susceptibility to the misinformation effect, which may occur because sleep results in gist‐based representations of original events or because sleep improves learning of postevent information. Implications for interviewing eyewitnesses are discussed. Copyright © 2016 John Wiley & Sons, Ltd.     

Recalling a Witnessed Event Increases Eyewitness Suggestibility: The Reversed Testing Effect

ABSTRACT— People's later memory of an event can be altered by exposure to misinformation about that event. The typical misinformation paradigm, however, does not include a recall test prior to the introduction of misinformation, contrary to what real-life eyewitnesses encounter when they report to a 911 operator or crime-scene officer. Because retrieval is a powerful memory enhancer (the testing effect), recalling a witnessed event prior to receiving misinformation about it should reduce eyewitness suggestibility. We show, however, that immediate cued recall actually exacerbates the later misinformation effect for both younger and older adults. The reversed testing effect we observed was based on two mechanisms: First, immediate cued recall enhanced learning of the misinformation; second, the initially recalled details became particularly susceptible to interference from later misinformation, a finding suggesting that even human episodic memory may undergo a reconsolidation process. These results show that real-life eyewitness memory may be even more susceptible to misinformation than is currently envisioned.     

A temporal discriminability account of children's eyewitness suggestibility

Children's suggestibility is typically measured using a three‐stage ‘event–misinformation–test’ procedure. We examined whether suggestibility is influenced by the time delays imposed between these stages, and in particular whether the temporal discriminability of sources (event and misinformation) predicts performance. In a novel approach, the degree of source discriminability was calculated as the relative magnitude of two intervals (the ratio of event–misinformation and misinformation–test intervals), based on an adaptation of existing ‘ratio‐rule’ accounts of memory. Five‐year‐olds (n =150) watched an event, and were exposed to misinformation, before memory for source was tested. The absolute event–test delay (12 versus 24 days) and the ‘ratio’ of event–misinformation/misinformation–test intervals (11:1, 3:1, 1:1, 1:3 and 1:11) were manipulated across participants. The temporal discriminability of sources, measured by the ratio, was indeed a strong predictor of suggestibility. Most importantly, if the ratio was constant (e.g. 18/6 versus 9/3 days), performance was remarkably similar despite variations in absolute delay (e.g. 24 versus 12 days). This intriguing finding not only extends the ratio‐rule of distinctiveness to misinformation paradigms, but also serves to illustrate a new empirical means of differentiating between explanations of suggestibility based on interference between sources and disintegration of source information over time.     

I still think it was a banana: memorable 'lies' and forgettable 'truths'

Interpersonal influences on cognition can distort memory judgements. Two experiments examined the nature of these 'social' influences, and whether their persistence is independent of their accuracy. Experiment 1 found that a confederate's social proximity, as well as the content and the confidence of their utterances, interactively modulates participants' immediate conformity. Notably, errant confederate statements that 'lied' about encoded material had a particularly strong immediate distorting influence on memory judgements. Experiment 2 revealed that these 'lies' were also memorable, continuing a day later to impair memory accuracy, while accurate confederate statements failed to produce a corresponding and lasting beneficial effect on memory. These findings suggest that an individual's 'informational' social influence can be selectively heightened when they express misinformation to someone who suspects no deceptive intent. The methods newly introduced here thus allow multiple social and cognitive factors impinging on memory accuracy to be manipulated and examined during realistic, precisely controlled dyadic social interactions.     

Combating Co‐witness contamination: Attempting to decrease the negative effects of discussion on eyewitness memory

Witnesses who discuss an event with others often incorporate misinformation encountered during the discussion into their memory of the event. Two experiments were conducted to establish whether this memory conformity also occurs in the context of an interview and whether it is possible to reduce the effect. Participants viewed a crime‐video which they then discussed with a co‐witness. Some participants were warned they may have been exposed to misinformation during the discussion before all were interviewed individually. In Experiment 1, participants made remember/know judgments about each component of their free recall, and in Experiment 2 they were asked to indicate the source of their memories. Co‐witness information was incorporated into participants' testimony, and this effect could not be significantly reduced using warnings and source‐monitoring instructions. Remember/know judgments may be useful in distinguishing ‘real’ memories from false memories. We make some recommendations regarding the interviewing of witnesses. Copyright © 2009 John Wiley & Sons, Ltd.     

The Influence of Social (Mis)Information on Memory for Behavior in an Employment Interview

We examined the impact of misinformation on memory for behavioral information in a social decision making context. In the initial study, 70 subjects viewed an 18-minute simulated employment interview, evaluated the interviewee, and then provided group ratings using their own evaluations and two other evaluations containing misinformation (misled group) or no misinformation (control group). The results of this study revealed that misled subjects were quite accepting of the misinformation, and were highly confident that the misinformation was true. In a supplemental experimental condition, a separate group of 23 subjects was given the same misinformation as the misled group. However, this group was alerted to the fact that they had received some misinformation, prior to completing a recognition memory test. This misled-informed group exhibited the same degree of accuracy as the control group, suggesting that the misinformation effects observed for the original misled group were due to social influence, rather than memory interference or source-attribution errors.     

Correcting the misinformation effect

Decades of memory research have demonstrated a dire need for effective methods of correcting misinformation, particularly once it has been encoded. However, much of this research has exposed participants to misinformation first then provided a correction, and used indirect memory questions. Using a misinformation effect (ME) paradigm, in which participants' memory is distorted by misleading postevent information, we examine whether corrections can combat memory distortion on direct memory tests. Experiment 1 showed corrections greatly reduced the ME. Experiment 2 replicated this finding with a longer lag time (3 min) between exposure to misinformation and its correction, except for participants that read only the misinformation and its correction. Experiment 3 ruled out the possibility that participants reported the most recent information they read, suggesting participants evaluate the correction's veracity. Finally, a meta‐analysis of the three experiments reiterates that corrections may be effective in combating misinformation.     

Why misinformation is reported: evidence from a warning and a source-monitoring task

People report suggested misinformation about a previously witnessed event for manifold reasons, such as social pressure, lack of memory of the original aspect, or a firm belief to remember the misinformation from the witnessed event. In our experiments (N?=?429), which follow Loftus's paradigm, we tried to disentangle the reasons for reporting a central and a peripheral piece of misinformation in a recognition task by examining (a) the impact a warning about possible misinformation has on the error rate, and (b) whether once reported misinformation was actually attributed to the witnessed event in a later source-monitoring (SM) task. Overall, a misinformation effect was found for both items. The warning strongly reduced the misinformation effect, but only for the central item. In contrast, reports of the peripheral misinformation were correctly attributed to the misinformation source or, at least, ascribed to guesswork much more often than the central ones. As a consequence, after the SM task, the initially higher error rate for the peripheral item was even lower than that of the central item. Results convincingly show that the reasons for reporting misinformation, and correspondingly also the potential to avoid them in legal settings, depend on the centrality of the misinformation.