The effect of mood on shaping belief and recollection following false feedback.

The current study examined how mood affects the impact of false feedback on belief and recollection. In a three-session experiment, participants first watched 40 neutral mini videos, which were accompanied by music to induce either a positive or negative mood, or no music. Following a recognition test, they received false feedback to reduce belief in the occurrence of the events displayed in some of the videos (Session 2). This was followed by an immediate memory test and a delayed memory assessment one week later (Session 3). The results revealed that participants in negative mood reported higher belief scores compared to those in positive moods, despite an overall decline in belief scores for all groups following the false feedback. Notably, individuals in negative moods exhibited less reduction in their belief scores after encountering challenges, thereby maintaining a higher accuracy in their testimonies. Over time, a reduction in the clarity of participants' memory recall was observed, which correspondingly reduced their testimony accuracy. This study thus indicates that mood states play a role in shaping belief and memory recall under the influence of false feedback.

Inducing emotionally negative nonbelieved memories using negative pictures.

Memories that can be recalled but are no longer believed are termed nonbelieved memories. The current studies examined the creation of emotionally negative nonbelieved memories after viewing negatively valenced pictures. In both experiments, participants took part in two sessions. In Session 1, after being presented with a set of neutral and negative pictures, participants had to rate their emotional state. One week later, in Session 2, participants had to complete a recognition task to identify pictures that had appeared during the previous session. During this task, participants' memories for some pictures were challenged by telling them that their answers were incorrect in order to evoke nonbelieved memories. The experimental procedure was successful in creating nonbelieved memories in the participants. Specifically, in Experiment 1 (N = 35), we induced nonbelieved true memories for both negative and neutral pictures. We found a significant decrease in both belief and recollection after the challenge, with the change in belief being twice as large as the change in recollection. In Experiment 2 (N = 43), we successfully induced both nonbelieved true and false memories for negative pictures. Again, the reduction of belief was significantly greater than that of recollection. In general, participants evinced better memory for negative pictures, but following challenges people were just as likely to accept false social feedback and change their memories regarding other types of pictures. In both experiments, our challenges did not lead to notable changes in emotional state. In general, our findings show that emotionally negative nonbelieved memories can be successfully evoked in an experimental setting.

Retracted memories in the general population: are there differences between eastern and western countries?

The main purpose of the current studies was to examine retracted experiences in the general population from various cultural backgrounds. More specifically, in two studies, we examined the details of memory retraction experiences, the reasons for retraction, and the outcomes of retraction in participants from China and other countries, mainly the United States of America. It was found that memory retraction experiences appeared to be quite common. In the sample of Chinese participants (Study 1: N = 1380), 50.58% reported at least one such an experience, whereas in respondents from other countries (Study 2; N = 425), a significantly lower but still substantial prevalence rate of 35% was found. In general, the retracted memories predominantly involved positive events and some respondents experienced pressure during the withdrawal. Social feedback and event plausibility were the two main reasons for the withdrawal. Compared to recollection scores, belief scores decreased significantly after withdrawal, and some respondents even formed nonbelieved memories. After retracting the memories, most respondents felt they gained benefits (e.g., they had resolved a psychological problem that had bothered them for years). These studies give us a more general understanding of retracted memory experiences in the general population.

Time and memory distrust shape the dynamics of recollection and belief-in-occurrence.

The current study examined how people's metamemory judgments of recollection and belief-in-occurrence change over time. Furthermore, we examined to what extent these judgments are affected by memory distrust - the subjective appraisal of one's memory functioning - as measured by the Memory Distrust Scale (MDS) and the Squire Subjective Memory Scale (SSMQ). Participants (N = 234) studied pictorial stimuli and were tested on some of these stimuli later in the same session, but were tested on other stimuli 1, 2, 4, 8, and 17 days later. Recollection and belief ratings were correlated highly and followed similar declining patterns over time. However, belief decreased relatively more slowly than recollection, such that the discrepancy between recollection and belief increased over time. Memory distrust moderated the association between recollection and belief, with this association being weaker among people who reported greater (versus lower) memory distrust. Memory distrust also interacted with retention period to predict memory judgments. Two measures of memory distrust diverged in their predictive power. In particular, only the MDS predicted the spontaneous reporting of nonbelieved memories. Our results provide support to the theoretical perspective that belief-in-occurrence is a summative judgment informed not only by recollective phenomenology but also by metamemorial beliefs.

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.

Can false denials turn fact into fiction? The effect of false denials on memory for self-performed actions.

We examined the mnemonic effects of falsely denying a self-performed action. Specifically, participants (N = 30) performed, imagined, or received no instruction about 24 action statements (e.g., "cross your arms"). Next, their memory for whether they had performed, imagined, or did nothing (i.e., received no instructions) with these actions was tested. Subsequently, participants were instructed to repeatedly deny an action they had performed (false denial) and to repeatedly claim to have performed an action they had only imagined (false admission). In a final sorting memory task, 54% (n = 16) of participants erroneously indicated, after false admissions, that they had performed the imagined action. None of the participants indicated that they had only imagined an action after false denials, showing that it might be difficult to forget a performed action, even after repeatedly denying it. The current experiment sets the stage for future research to investigate why it seems to be difficult to forget performed actions.

Factors affecting the forced confabulation effect: a meta-analysis of laboratory studies.

During police investigations, interviewees are sometimes forced to confabulate a response to questions for which they don't know the answer. In this registered report, we conducted a three-level meta-analysis to examine whether forcing people to confabulate an answer to these questions can lead to false memories for the confabulated details and/or events (i.e., forced confabulation effect). Results showed that forced confabulation indeed led to the production of false memories. Qualitative reviews of studies suggested that the forced confabulation effect is enhanced after receiving confirmatory feedback. Moreover, we found evidence that longer delays between the forced confabulation phase and the final memory task are necessary to observe the forced confabulation effect for entire events. However, caution is needed when interpreting the forced confabulation effect. Specifically, our moderator analyses revealed that voluntarily produced confabulation led to more false memories than forced confabulation. Also, our exploratory analysis indicated that the forced confabulation effect was mainly observed in within-subject designs. Taken together, our meta-analysis supports the notion that forcing participants to confabulate can lead them to later report such confabulations as part of the truth. Nonetheless, caution is warranted because this effect might be due to the introduction of misinformation through asking unanswerable questions.

Preference for cheap-and-easy memory verification strategies is strongest among people with high memory distrust.

When choosing strategies for verifying one's memory, people are more influenced by the perceived cost of using a strategy than by its likelihood of yielding reliable information (i.e., cheap-strategy bias). The current preregistered study investigated whether people with high memory distrust are less likely to exhibit this bias than their low memory distrust counterparts. Participants (N = 535) imagined a scenario in which they witnessed an accident and were then led by friends to question their memories about the accident. Participants had to propose five strategies for verifying that particular memory. Following this, they rated each strategy's cost, reliability, and their likelihood of using it, as well as completing two validated measures of trait memory distrust. Contrary to our prediction, compared with participants with low memory distrust, participants with higher memory distrust exhibited a larger cheap-strategy bias. Follow-up analyses suggested that compared with memory-trusters, memory distrusters' strategy choices were more influenced by a strategy's perceived cost, and less influenced by its perceived reliability. Our results suggest that people who are more skeptical about their memories may be more cynical about the worthwhileness of verifying their memory, which could make them especially susceptible to misinformation acceptance and false memory creation.

Challenging memories reduces intrusive memories and the memory amplification effect.

This study scrutinizes the influence of attenuating beliefs about the veracity of traumatic experiences on the manifestation of intrusive recollections and the memory amplification effect. Participants were exposed to distress-inducing visual stimuli, subsequently rating their emotional status pre and post exposure. They engaged in a recognition task, identifying scenarios within the stimuli. Participants' recall was contested, casting doubt about the occurrence of certain scenes. Subsequently, they maintained a daily log of intrusive memories over a week. A second session reiterated the same process. This method effectively diminished the certainty in the participants' traumatic memories. Scenes whose occurrence was contested demonstrated a significant decline in both intrusive memories and memory amplification when juxtaposed with uncontested ones. Interestingly, no significant correlation emerged between the diminished belief in traumatic incidents and reductions in intrusive memory or memory amplification. Thus, this study advocates that interrogating the veracity of traumatic recollections can mitigate the prevalence of intrusive memories and the memory amplification effect, suggesting a novel potential therapeutic approach for trauma-related disorders.

Cannabis increases susceptibility to false memory.

With the growing global acceptance of cannabis and its widespread use by eyewitnesses and suspects in legal cases, understanding the popular drug's ramifications for memory is a pressing need. In a double-blind, randomized, placebo-controlled trial, we examined the acute and delayed effects of Δ9-tetrahydrocannabinol (THC) intoxication on susceptibility to false memory in 64 healthy volunteers. Memory was tested immediately (encoding and retrieval under drug influence) and 1 wk later (retrieval sober). We used three different methods (associative word lists and two misinformation tasks using virtual reality). Across all methods, we found evidence for enhanced false-memory effects in intoxicated participants. Specifically, intoxicated participants showed higher false recognition in the associative word-list task both at immediate and delayed test than controls. This yes bias became increasingly strong with decreasing levels of association between studied and test items. In a misinformation task, intoxicated participants were more susceptible to false-memory creation using a virtual-reality eyewitness scenario and virtual-reality perpetrator scenario. False-memory effects were mostly restricted to the acute-intoxication phase. Cannabis seems to increase false-memory proneness, with decreasing strength of association between an event and a test item, as assessed by different false-memory paradigms. Our findings have implications for how and when the police should interview suspects and eyewitnesses.

Oversimplifications and Misrepresentations in the Repressed Memory Debate: A Reply to Ross.

Ross argued that false memory researchers misunderstand the concepts of repression and dissociation, as well as the writings of Freud. In this commentary, we show that Ross is wrong. He oversimplifies and misrepresents the literature on repressed and false memory. We rebut Ross by showing the fallacies underlying his arguments. For example, we adduce evidence showing that the notions of dissociation or repression are unnecessary to explain how people may forget and then remember childhood sexual abuse, stressing that abuse survivors may reinterpret childhood events later in life. Also, Ross overlooks previous critiques concerning dissociation. Finally, we will demonstrate that Ross misrepresents work by Freud and Loftus in the area of repressed and false memory. His article confuses, not clarifies, an already heated debate on the existence of repressed memory.

Teaching psychology students to change (or correct) controversial beliefs about memory works.

Therapists, judges, law enforcement, and students often believe in the existence of automatic and unconscious repression. Such a belief can be perilous as it might lead therapists to suggestively search for repressed memories leading to false memories. Recovering therapy-induced false memories of criminal acts can have serious consequences. Here, we tested whether erroneous beliefs in repressed memories can be corrected. Surveying two cohorts of Forensic and Legal Psychology Master's students, we examined whether education about the science of (eyewitness) memory can correct erroneous beliefs in repressed memories. Students assessed memory statements before taking a course on eyewitness memory, six weeks after the course exam, and 18 or 6 months later, respectively (Ns = 33-74 per cohort and measurement). As expected, students in both cohorts on average initially strongly agreed with the statement that memories of traumatic events can be unconsciously blocked, but strongly disagreed with the statement after the course. Belief-corrections also persisted after the longer delay. These findings show that educating people about the science of (eyewitness) memory can be effective in correcting false and controversial memory beliefs in general and the existence of repressed memories in specific.

What science tells us about false and repressed memories.

What does science tell us about memory phenomena such as false and repressed memories? This issue is highly pressing as incorrect knowledge about these memory phenomena might contribute to egregious effects in the courtroom such as false accusations of abuse. In the current article, we provide a succinct review of the scientific nature of false and repressed memories. We demonstrate that research has shown that about 30% of tested subjects formed false memories of autobiographical experiences. Furthermore, this empirical work has also revealed that such false memories can even be implanted for negative events and events that allegedly occurred repeatedly. Concerning the controversial topic of repressed memories, we show that plausible alternative explanations exist for why people claim to have forgotten traumatic experiences; explanations that do not require special memory mechanisms such as the unconscious blockage of traumatic memories. Finally, we demonstrate that people continue to believe that unconscious repression of traumatic incidents can exist. Disseminating scientifically articulated knowledge on the functioning of memory to contexts such as the courtroom is necessary as to prevent the occurrence of false accusations and miscarriages of justice.

False remembering in real life: James Ost's contributions to memory psychology.

This special issue honours James Ost's (1973-2019) contributions to our understanding of false and distorted remembering. In our editorial, we introduce some of James' distinctive research themes including the experiences of people who retract "recovered" memories, social (e.g., co-witness and interviewer influence) and personality influences on false remembering, the nature of false remembering itself (e.g., different types of false memories; false memories vs. false beliefs), public understanding of (false) memory, and a historical link to the work of Frederic Bartlett. We illustrate these themes through a number of key publications. The unifying thread behind James' work is his core interest in false/distorted remembering in real-life (typically high-stake) situations, in line with his engagement with the British False Memory Society and his role as an expert witness in court trials. The articles included in this special issue elaborate on the research themes to which James devoted his career and his curiosity.

False denials increase false memories for trauma-related discussions.

False denials are sometimes used to cope with traumatic experiences. We examined whether false denials can affect true and false memory production for a traumatic event and conversations surrounding the trauma. One hundred and twenty-six participants watched a trauma analogue video of a car crash before being randomly asked in a discussion with the experimenter to (1) respond honestly or (2) falsely deny that certain details happened in the video. After one week, all participants received misinformation about the discussion with the experimenter and the car crash. Finally, all participants were instructed to respond truthfully in a source memory task. Participants who falsely denied information during the first session were statistically significantly more prone than honest participants to omit details they denied and to report misinformation about what was discussed in the first session. Our work suggests that false denials of a traumatic experience might lead to both forgetting and increased false memory levels for earlier conversations about the event.

Simulating denial increases false memory rates for abuse unrelated information.

Victims of abuse might deny their traumatic experiences. We studied mnemonic effects of simulating false denial of a child sexual abuse narrative. Participants (N = 127) read and empathized with the main character of this narrative. Next, half were instructed to falsely deny abuse-related information while others responded honestly in an interview. One week later, participants received misinformation for the narrative and interview. In a final source memory task, participants' memory for the narrative and interview was tested. Participants who falsely denied abuse-related information endorsed more abuse-unrelated misinformation about the event than honest participants. Abuse-related false memory rates did not statistically differ between the groups, and false denials were not related to omission errors about (1) the interview and (2) narrative. Hence, victim's memory for abuse-related information related to their experience might not be affected by a false denial, and inconsistencies surrounding the abuse-unrelated information are more likely to take place.

The effects of stress on eyewitness memory: A survey of memory experts and laypeople.

This survey examined lay and expert beliefs about statements concerning stress effects on (eyewitness) memory. Thirty-seven eyewitness memory experts, 36 fundamental memory experts, and 109 laypeople endorsed, opposed, or selected don't know responses for a range of statements relating to the effects of stress at encoding and retrieval. We examined proportions in each group and differences between groups (eyewitness memory experts vs. fundamental memory experts; experts vs. laypeople) for endorsements (agree vs. disagree) and selections (don't know vs. agree/disagree). High proportions of experts from both research fields agreed that very high levels of stress impair the accuracy of eyewitness testimony. A majority of fundamental experts, but not eyewitness experts, endorsed the idea that stress experienced during encoding can enhance memory. Responses to statements regarding moderating factors such as stressor severity and detail type provided further insight into this discrepancy. Eyewitness memory experts more frequently selected the don't know option for neuroscientific statements regarding stress effects on memory than fundamental memory experts, although don't know selections were substantial among both expert groups. Laypeople's responses to eight of the statements differed statistically from expert answers on topics such as memory in children, in professionals such as police officers, for faces and short crimes, and the existence of repression, providing insight into possible 'commonsense' beliefs on stress effects on memory. Our findings capture the current state of knowledge about stress effects on memory as reflected by sample of experts and laypeople, and highlight areas where further research and consensus would be valuable.

Believing in dissociative amnesia relates to claiming it: a survey of people's experiences and beliefs about dissociative amnesia.

Dissociative amnesia is one of the most controversial categories in the field of psychiatry and clinical psychology. Self-reports of dissociative amnesia in the general population, and beliefs about this topic, have so far not been subjected to empirical scrutiny. Here, we surveyed a sample from the general population (N = 1017), revealing that about a tenth (n = 102) claimed to have experienced dissociative amnesia. Some claims pertained to amnesia for traumatic autobiographical experiences (e.g., sexual assault), while other claims reflected memory loss for experiences that can be regarded as non-traumatic or non-stressful (e.g., dissociative amnesia for an anniversary). Importantly, many participants believed in the existence of dissociative amnesia, and those who claimed dissociative amnesia indicated even more belief in this phenomenon than the rest of the sample. Finally, many participants indicated to have at least once claimed to have feigned memory loss in their life, and that they experienced some form of forgetting when trying to retrieve events for which they lied upon. Overall, our findings suggest that claiming dissociative amnesia goes hand in hand with believing in dissociative amnesia.

Implanting false autobiographical memories for repeated events.

Research to date has exclusively focused on the implantation of false memories for single events. The current experiment is the first proof of concept that false memories can be implanted for repeated autobiographical experiences using an adapted false memory implantation paradigm. We predicted that false memory implantation approaches for repeated events would generate fewer false memories compared to the classic implantation method for single events. We assigned students to one of three implantation conditions in our study: Standard, Repeated, and Gradual. Participants underwent three interview sessions with a 1-week interval between sessions. In the Standard condition, we exposed participants to a single-event implantation method in all three interviews. In the Repeated condition, participants underwent a repeated-event implantation method in the three interviews. The Gradual condition also consisted of a repeated-event implantation method, however, in the first interview alone, we suggested to participants that they had experienced the false narrative once. Surprisingly, within our sample, false memories rates in the Standard condition were not higher compared to the Repeated and Gradual conditions. Although sometimes debated, our results imply that false memories for repeated events can be implanted in lab conditions, likely with the same ease as false memories for single events.

Do liars really remember what they lied upon? The impact of fabrication on memory.

The present experiment aimed to examine how fabrication can affect memory. In particular, we examined whether different types of fabrication can lead to different mnemonic effects. A sample of 159 participants watched a video of a robbery and subsequently answered some questions about it. Participants were divided into three conditions: one group was instructed to tell the truth (i.e., truth-telling group), while the other two groups were instructed to lie either by partially distorting details (i.e., distortion group) or by completely making up wrong details of the event seen in the video (i.e., fabrication group). Two days later, participants completed a final memory test where they honestly answered recognition and recall questions concerning: (i) memory for the video and (ii) memory for having discussed details during the interview. Results showed that different types of fabrication affect liars' memory differently. Fabricators reported an undermining of memory for the event, whereas those who partially distorted details reported a higher impairment for the interview. Our findings showed that the effects of lying on liars' memory might be determined by the cognitive resources required to lie.