Henry Otgaar

Maastricht University | UM · LINC (Faculty of Law KU Leuven); Section Forensic Psychology, Department of Clinical Psychological Science

Professionals who evaluate witness testimony must understand the developmental factors that can affect statements credibility. This online vignette study investigated in how far 102 legal professionals (e.g., judges, attorneys, and police officers) were aware of age-related differences in false memory formation (e.g., the developmental reversal eff...

Background Ayahuasca is an Amazonian brew with 5-HT 2A -dependent psychedelic effects taken by religious groups globally. Recently, psychedelics have been shown to impair the formation of recollections (hippocampal-dependent episodic memory for specific details) and potentially distort memory while remembering. However, psychedelics spare or enhanc...

While it is well-established that authentic emotional autobiographical memories elicit physiological responses, research suggests that this elicitation can also occur for fabricated autobiographical memories. Yet challenges arise from awareness discrepancies when considering two research fields: Participants in memory studies may be unaware of prod...

Purpose: Eyewitness memory research has reformed police practices and policy and is sometimes relied upon in legal proceedings. Due to the practical implications derived from this research, it is imperative to evaluate how practical recommendations are postulated. To assess the practical relevance of research, effect sizes and their interpretation...

Posttraumatic stress disorder (PTSD) is one of the most serious and incapacitating mental diseases that can result from trauma exposure. The exact prevalence of this disorder is not known as the literature provides very different results, ranging from 2.5% to 74%. The aim of this umbrella review is to provide an estimation of PTSD prevalence and to...

Debates surrounding the origin of recovered memories of child abuse have traditionally focused on two conflicting arguments, namely that these memories are either false memories or instances of repressed memories (i.e., reflecting the idea that people can unconsciously block traumatic autobiographical experiences and eventually regained access). Wh...

Fake news can affect people in negative ways. A recent line of research has demonstrated that when people are exposed to fake news they can form false memories for the events depicted in the news stories. We conducted a meta-analysis to obtain an estimate of the average rate of false memories elicited by fake news. Thirteen articles were included i...

Although human memory is generally reliable, it is susceptible to distortions like false memories. This study investigated the relationship between the emotional valence of events, mood states, and the formation of false autobiographical memories using the blind implantation method. Specifically, we examined the impact of positive and negative mood...

Purpose: Before psychological research is used for policy reforms and recommendations, it is important to evaluate its replicability, generalizability, and practical relevance. In the present article, we examined these three criteria for published articles in the Journal of Criminal Psychology. Methodology: Through a literature search for published...

Child interviews should be conducted according to best practice standards, acknowledging developmental, social, and cultural aspects, and using evidence-based interviewing protocols that rely on open-ended questions (e.g., “Tell me what happened”), including when interviews take place with the help of interpreters. Interviewers need to engage in hy...

We conducted a qualitative study investigating traumatic daydreaming themes among individuals with mal-adaptive daydreaming (MD). Forty-one participants were interviewed regarding connections between their traumatic daydreams and real-life adversity. Specifically, we asked participants about 1) childhood trauma experiences , 2) trauma-related daydr...

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...

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 (SS...

Campus sexual assault constitutes a frequent crime witnessed by many. Among co-witnesses such assault is oftentimes denied. We examined how false denials during an informal co-witness conversation impacted memory for the conversation and witnessed assault. Ninety Participants watched a trauma-analogue video with a co-witness. The next day, honest c...

Eyewitness memory research has reformed police practices and policy and is sometimes relied upon in legal proceedings. Due to the practical implications derived from this research, it is imperative to evaluate how practical recommendations are postulated. To assess the practical relevance of research, effect sizes and its interpretation play a pivo...

Purpose In the current study, we investigated whether denial and avoidance rates differed statistically significantly based on the interview protocol used. Method We examined 38 National Institute of Child Health and Human Development (NICHD) interview transcripts, and 30 control transcripts from interviews from an earlier study ( Applied Cognitiv...

Rechtspsychologen treden regelmatig op als deskundige in de rechtszaal. In hun deskundigenrapportages wordt dikwijls gebruikt maakt van de wetenschappelijk literatuur. Het gebruik hiervan wekt de indruk dat die literatuur praktisch relevant is. Maar is dat ook zo? In dit artikel betogen wij dat bij een groot deel van rechtspsychologisch onderzoek h...

Self-compassion is assumed to have a protective role in the etiology of emotional problems in adolescents. This assumption is primarily based on correlational data revealing negative correlations between the total score on the Self-Compassion Scale (SCS) and symptom measures of anxiety and depression. Recently, however, the SCS has been criticized...

Because of the inherent reconstructive nature of memory, both recollection and belief concerning experienced events can change dynamically because of external information. We argue that economic games that include rich social information and a controlled environment can offer unique opportunities to study memory-related phenomena in relation to ext...

In the current set of experiments, we examined the effectiveness of the Cognitive Interview (CI) on memory for traffic accidents. Three online experiments were conducted among Indonesian young motorcyclists who had an accident experience. Participants were interviewed about their most memorable accident experience, either with a CI or a Standard In...

How child victims of sexual abuse disclose their experiences is contested among experts. We surveyed international researchers (N = 199) and child protection service workers (N = 267) on their beliefs regarding how victims of child sexual abuse cope with and disclose their experiences, and how these disclosure patterns affect the validity of statem...

Research on misleading post-event information has demonstrated that being exposed to such information can undermine people’s memory for the original event. Similarly, studies on lying and memory have shown that lying upon an event can negatively impact memory. By combining these two lines of work, we asked participants to read a case vignette about...

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 relat...

One of the most heated debates in psychological science concerns the concept of repressed memory. We discuss how the debate on repressed memories continues to surface in legal settings, sometimes even to suggest avenues of legal reform. In the past years, several European countries have extended or abolished the statute of limitations for the prose...

Legal practitioners sometimes ask psychologists to evaluate the validity of statements of victims, witnesses, and suspects. For their assessment, psychologists often have access to different pieces of evidence (e.g., a video recording of the interview, the suspect’s statements). Research has demonstrated that the order of reviewing the evidence can...

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...

Different court cases from the 1980s known as the 'daycare abuse cases' are reviewed. In these cases, the alleged victims were interviewed with suggestive questioning, resulting in likely false memories and wrongful convictions. In addition, an Italian case in which a therapist has recently been convicted related to false memory controversy is disc...

The recommendations of this white paper are jointly drafted by researchers in childinterviewing active within the European Association of Psychology and Law and are focusedon cases in which children are interviewed in forensic settings, in particular withininvestigations of child sexual and/or physical abuse.

Purpose This study aimed to examine beliefs in repressed memory and dissociative amnesia from a cross-cultural perspective. Design/methodology/approach Chinese ( n = 123) and Belgian student participants ( n = 270) received several statements tapping into various dimensions of repressed memory and dissociative amnesia. Participants provided belief...

General Audience Summary The experience of sometimes finding it difficult to trust one’s own memory is widely shared. Moreover, some people are more skeptical about their memories, while others are less. This individual difference is referred to as trait memory distrust. Memory distrust has been measured with two scales, the Squire Subjective Memor...

When memories of past rewarding experiences are distorted, are relevant decision-making preferences impacted? Although recent research has demonstrated the important role of episodic memory in value-based decision making, very few have examined the role of false memory in guiding novel decision making. The current study combined the pictorial Deese...

In legal cases, testimonies can become contaminated because of an amalgam of external and internal influences on memory. It is well-established that external influences (e.g., suggestive interviews) can hurt memory. However, less focus has been placed on the impact of internal influences (e.g., lying) on memory. In the current review, we show that...

Purpose The purpose of this study was to investigate cognitive behavior therapists and trainees’s beliefs about various aspects of traumatic memory and to investigate cognitive behavior therapists’ practices in relation to alleged traumatic experiences and whether they are linked with their beliefs about various aspects of traumatic memory. Design...

The present review addressed the relationship between two self-related concepts that are assumed to play a role in human resilience and well-being: self-esteem and self-compassion. Besides a theoretical exploration of both concepts, a meta-analysis (k = 76, N = 35,537 participants) was conducted to examine the magnitude of the relation between self...

The use of alternative scenarios has been advocated as a method to mitigate bias when evaluating the reliability of testimonies. In two experiments, undergraduate students acted as expert witnesses when reading an alleged child sexual abuse case file and evaluated the reliability of the statements. In the first experiment, a subgroup of participant...

Studies have shown that lying can detrimentally affect memory. For example, when people fabricate a false account, this fabrication can turn into a false memory. The current experiment aimed to examine whether the typical effects on memory due to fabrication depend on psychopathy traits. 232 participants completed the Personality Psychopathy Invent...

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 negati...

In this commentary, we argue that besides focusing on generalization, sufficient attention must be invested in the practical relevance of psychological and applied memory research. That is, memory research is frequently used to address real-life questions. In the area of psychology and law, memory scientists are sometimes asked by court to provide...

Recent work suggests that the debate surrounding repressed memory and traumatic forgetting continues today. To further investigate this debate, we performed preregistered scientometric analyses on publications on the debate about repressed memory to provide information about its bibliometric evolution. Furthermore, we reviewed these publications to...

The current study examined the effect of reducing beliefs in the occurrence of traumatic experiences on the production of intrusive memories and the memory amplification effect. Participants took part in two sessions. In the first session, participants rated their emotional state before and after viewing trauma-inducing videos. Then, participants c...

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 memor...

Posttraumatic stress disorder (PTSD) is one of the most serious and incapacitating mental diseases that can result from trauma exposure. However, despite its relevance, there is still considerable confusion and debate surrounding its diagnosis. The aim of this umbrella review is to clarify the overall prevalence of PTSD. Furthermore, the study exam...

Background: Legal cases and research have shown that due to suggestive therapeutic interventions, people can start to remember abuse that they never experienced. Some of these people eventually retract their claims of abuse. This study examined the memory reports of self-defined retractors of abuse and the prevalence of nonbelieved memories. Method...

Purpose: A heated debate exists on whether traumatic memories can be dissociated or repressed. One way in which researchers have attempted to prove the existence of dissociative amnesia or repressed memory is to examine whether claims of amnesia for traumatic events are associated with specific neural markers. Methods: Here, we will argue that suc...

When experiencing mental health challenges, we all deserve treatments that actually work. Whether you are a healthcare consumer, student, or mental health professional, this book will help you recognize implausible, ineffective, and even harmful therapy practices while also considering recent controversies. Research-supported interventions are iden...

When experiencing mental health challenges, we all deserve treatments that actually work. Whether you are a healthcare consumer, student, or mental health professional, this book will help you recognize implausible, ineffective, and even harmful therapy practices while also considering recent controversies. Research-supported interventions are iden...

In this commentary, we argue that besides focusing on generalization, sufficient attention must be invested in the practical relevance of psychological and applied memory research. That is, memory research is frequently used to address real life questions. In the area of psychology and law, memory scientists are sometimes asked by court to provide...

Objective Previous research has indicated high rates of sexual assault (SA) among US students (> 25%). Yet this type of investigation has been less frequent at European universities. Methods We conducted an investigation at three universities, two Dutch universities (N = 95 and N = 305) and one university in Belgium (N = 307). Students were asked...

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 memor...

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...

Scott O. Lilienfeld was among the most influential clinical psychological scientists, avid promoters of psychological science, and stalwart and effective critics of pseudoscience in our time. We describe the role that Lilienfeld and other skeptical scientists played in the so-called “memory wars” that spanned more than three decades and continue to...

Psychotherapy aims to make patients better. As is true for any type of treatment, psychotherapy regularly fails to achieve this goal. Therapeutic failures may take many forms, and the list of possible reasons for failure is similarly extensive. As we will explain in this chapter, there is no conclusive definition of psychotherapeutic failure. Also,...

Background and purpose: Self-compassion is considered as a protective psychological construct that would shield against the development of emotional problems. The aim of the present study was to compare the 'protective nature' of two measures of self-compassion: the Self-Compassion Scale for Youth (SCS-Y) and the Sussex-Oxford Compassion for the S...

Memory experts are sometimes asked to evaluate the validity of accounts of witnesses, victims, or suspects. In some of these cases, they are asked what effect alcohol has on the validity of such accounts. In this article, we offer a guide on what expert witnesses can reliably say about how alcohol affects memory. We do so by resorting to effect siz...

When beliefs in autobiographical memories are reduced while recollections remain relatively intact, a phenomenon termed nonbelieved memories (NBMs) unfolds. The current preregistered study (N = 104) used a 3-week longitudinal design to investigate the relationships between the frequency of recalled NBMs, memory distrust, rumination over autobiograp...

People who are confronted with criminal situations sometimes lie by using different deceptive strategies. If they eventually come forward with the truth, it is important to understand whether their memory-based testimonies might be affected by their initial lies. To examine and compare the effects of various deceptive strategies (i.e., fabrication,...

Individuals scoring high on psychopathic personality traits process emotional material to a different extent than individuals with few psychopathic traits. Evidence exists that these individuals have impaired emotional memory. The question arises whether this emotional memory impairment has ramifications for the production of emotional false memori...

People are often exposed to fake news. Such an exposure to misleading information might lead to false memory creation. We examined whether people can form false memories for COVID-19-related fake news. Furthermore, we investigated which individual factors might predict false memory formation for fake news. In two experiments, we provided participan...

Psychologists are sometimes asked to provide their expert opinion in court on whether memories of victims, witnesses, or suspects are reliable or not. In this article, we will discuss what expert witnesses can reliably say about memory in the legal arena. We argue that before research on memory can be discussed in legal cases, this research should...

In three studies, we examined whether beliefs in repressed memory and dissociative amnesia could be changed. Participants provided agreement ratings to statements related to repressed memory and dissociative amnesia. Then, they received a university course which included education on the science of memory. Following this, participants had to re-rat...

In menig misdaadserie komt het voorbij: de forensisch expert in een witte jas die een vingerspoor in de computer invoert. Al snel komt de computer met de verlossende boodschap: er is een match. Het vingerspoor van de plaats delict komt overeen met de vingerafdruk van de verdachte. Hoera, de zaak is opgelost. Toch? Werkt het inderdaad zo in de prakt...

People lie on a frequent basis. However, when a victim of maltreatment lies by denying the abuse, lies can become forensically relevant. We have reviewed the relevant literature on the prevalence and memory consequences of such false denials. The way forensic interviewers proceed in the face of denying children will be shaped by their beliefs about...

General Audience Summary Studies have recently shown that lack of sufficient sleep as well as drug influence can heighten the proneness to go along with suggestions (susceptibility to suggestion) or to form memories of events that never happened (false memories). People who use drugs often combine multiple substances, such as alcohol, cannabis, and...

Legal psychologists’ assessments can have a major impact on the fact finder’s evaluation of evidence and, consequently, perceptions of guilt. Yet, in the few studies about legal psychologists’ assessments and reports, great variability was found. As is the case with other forensic expert domains, legal psychologists are prone to cognitive biases, s...

In various countries, forensic scientists have begun to express their expert opinion in terms of the likelihood of observing the evidence under the primary and under an alternative hypothesis (i.e., the likelihood-ratio approach). This development is often confined to technical domains such as fingerprint analyses. In forensic psychological experti...

In the current experiment, we examined the effects of self‐generated deceptive behavior on memory. Participants (n = 230) were randomly assigned to a “strong‐incentive to cheat” or “weak‐incentive to cheat” condition and played the adapted Sequential Dyadic Die‐Rolling paradigm. Participants in the “strong‐incentive to cheat” condition were incenti...

Ross (in press) 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 examp...

In the current experiment, we examined the effects of self-generated deceptive behavior on memory. Participants (n = 230) were randomly assigned to a “strong-incentive to cheat” or “weak-incentive to cheat” condition and played the adapted Sequential Dyadic Die-Rolling paradigm. Participants in the “strong-incentive to cheat” condition were incenti...

We examined whether fabrication affects memory using a new paradigm combining the Deese/Roediger-McDermott paradigm (DRM) and the Amsterdam Short Term Memory task (ASTM). Participants were assigned to either a forced fabrication or honest condition, and encoded emotionally-negative and neutral wordlists by reading words out loud. The wordlists cont...

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 fa...

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 tes...

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-twenty-six participants watched a trauma analogue video of a car crash before being randomly asked in a discussion with the exp...

A suspect of a crime can avoid legal repercussions by creating a false alibi. We examined whether creating such a false alibi can have adverse effects on memory. To do so, participants watched a mock crime video and were either instructed to create a false alibi or to provide an honest account for what they actually saw in the video. After a two-da...

Pretending to suffer from amnesia for a mock crime has been shown to lead to memory impairments. Specifically, when people are asked to give up their role of simulators, they typically recall fewer crime-relevant details than those who initially confess to a crime. In the current review, we amassed all experimental work on this subject and assessed...

Are personality traits related to symptom overreporting and/or symptom underreporting? With this question in mind, we evaluated studies from 1979 to 2020 ( k = 55), in which personality traits were linked to scores on stand-alone validity tests, including symptom validity tests (SVTs) and measures of socially desirable responding (SDR) and/or super...

In a new commentary in Mindfulness , Neff once again tried to defend the use of the Self-Compassion Scale (SCS) total score by arguing that compassionate and uncompassionate self-responding (CS and UCS) are part of a bipolar continuum. In this brief reaction, we refute this notion and also clarify how the continued use of the SCS total score muddie...