Harald Merckelbach

Maastricht University | UM · Forensic Psychology Section

Mental-health patients may report more symptoms than they actually experience. Experts and laypeople often view this overreporting as a sign of malingering. We show that there are multiple pathways to symptom overreporting: carryover effects from previous tests that lower the threshold for answering affirmatively to symptom items, suggestive misinf...

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...

For more than 30 years, the posttraumatic model (PTM) and the sociocognitive model (SCM) of dissociation have vied for attention and empirical support. We contend that neither perspective provides a satisfactory account and that dissociation and dissociative disorders (e.g., depersonalization/derealization disorder, dissociative identity disorder)...

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...

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...

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...

The Self-Report Symptom Inventory (SRSI) was developed to expand the toolbox of self-report instruments available to detect symptom overreporting. Such instruments, today known as symptom validity tests, play a crucial role in both forensic evaluations and in a range of clinical referral questions. The SRSI was originally designed in the German lan...

Feigning (i.e., grossly exaggerating or fabricating) symptoms distorts diagnostic evaluations. Therefore, dedicated tools known as symptom validity tests (SVTs) have been developed to help clinicians differentiate feigned from genuine symptom presentations. While a deviant SVT score is an indicator of a feigned symptom presentation, a non-deviant s...

For more than 30 years, the posttraumatic model (PTM) and the sociocognitive model (SCM) of dissociation have vied for attention and empirical support. We contend that neither perspective provides a satisfactory account and that dissociation and dissociative disorders (e.g., depersonalization/ derealization disorder, dissociative identity disorder)...

When patients fail symptom validity tests (SVTs) and/or performance validity tests (PVTs), their self-reported symptoms and test profiles are unreliable and cannot be taken for granted. There are many well-established causes of poor symptom validity and malingering is only of them. Some authors have proposed that a cry for help may underlie poor sy...

Samenvatting Over nadelige effecten van psychotherapie is weinig bekend. Dit komt omdat negatieve reacties op psychologische interventies niet standaard worden geregistreerd in psychotherapie-trials. Deze studie beoogt meer inzicht krijgen in de potentieel negatieve effecten van psychotherapie, zoals gerapporteerd door patiënten. Deelnemers werden...

In an often-cited study, Murdock et al. (2010) found that therapists are more likely to attribute premature treatment termination to client characteristics than to themselves, a finding that the authors interpreted in terms of a self-serving bias (SSB). We replicated and extended the study of Murdock et al. (2010, study 2). Psychologists and psycho...

Does Eye Movement and Desensitization and Reprocessing (EMDR) therapy affect the accuracy of memories? This recurrent issue in recent memory research bears relevance to expert witness work in the courtroom. In this review, we will argue that several crucial aspects of EMDR may be detrimental to memory. First, research has shown that eye movements u...

Symptoomvaliditeitstests in de rechtszaal 1 Eisers of verdachten van wie wordt vermoed dat ze klachten veinzen, duiken ook in de rechtszaal op en zorgen daar niet zelden voor verwarring. De juridische omgang met het onderwerp zou aan conceptuele helderheid en consistentie winnen, als deskundigen in voorkomende gevallen een speciale klasse van tests...

Some self-report symptom validity tests, such as the Self-Report Symptom Inventory (SRSI), rely on a detection strategy that uses bizarre, extreme, or very rare symptoms. Thus, items are constructed to invite respondents with an invalid response style to affirm pseudosymptoms that are usually not experienced by genuine patients. However, these pseu...

Background and Objectives Anecdotal and research evidence suggests that individuals with dissociative symptoms exhibit hyperassociativity, which might explain several key features of their condition. The aim of our study was to investigate the link between dissociative tendencies and hyperassociativity among college students. Methods The study (n...

Dissociative amnesia, defined as an inability to remember important autobiographical experiences usually of a stressful nature, is a controversial phenomenon. We systematically reviewed 128 case studies of dissociative amnesia reported in 60 papers that appeared in peer-reviewed journals in English over the past 20 years (2000-2020). Our aim was to...

Practitioners always want to exclude the possibility that a patient is feigning symptoms. Some experts have suggested that an inconsistent symptom presentation across time (i.e., intraindividual variability) is indicative of feigning. We investigated how individuals with genuine pain-related symptoms (truth tellers; Study 1 n = 32; Study 2 n = 48)...

Inspired by theories of prosocial behavior, we tested the effect of relationship status and incentives on intended voluntary blame-taking in two experiments (Experiment 2 was pre-registered). Participants (NE1 = 211, NE2 = 232) imagined a close family member, a close friend, or an acquaintance and read a scenario that described this person committi...

Expert witnesses and scholars disagree on whether suggestibility and compliance are related to people’s tendency to falsely confess. Hence, the principal aim of this review was to amass the available evidence on the link between suggestibility and compliance and false confessions. We reviewed experimental data in which false confessions were experi...

Based on converging research, we concluded that the controversial topic of unconscious blockage of psychological trauma –i.e., repressed memory- remains very much alive in clinical, legal, and academic contexts (Otgaar et al., 2019). In his commentary, Brewin (in press) conducted a co-citation analysis and concluded that scholars do not adhere to t...

We reviewed articles that appeared between 2000 and 2018 and that addressed fantasy proneness as measured by the Creative Experiences Questionnaire (CEQ) or the Inventory of Childhood Memories and Imaginings (ICMI). We searched Google Scholar to identify relevant articles and used the Hunter-Schmidt method to meta-analyze the correlates of fantasy...

The recently developed Self-Report Symptom Inventory (SRSI) intends to provide an alternative approach to the detection of symptom over-reporting. Unlike other measures, the SRSI includes both non-existent symptoms (i.e., pseudosymptoms) and genuine symptoms. Previous research using the German SRSI showed that people who exaggerate their complaints...

We asked students, clinicians, and people from the general population attending a public university lecture (n = 401) whether they knew others who (had) feigned symptoms. We also asked about the type of symptoms and the motives involved. A slight majority of proxy respondents (59%) reported that they knew a person who (had) feigned symptoms, and 34...

We explored underreporting of mental health symptoms and its correlates in adults receiving psychological treatment. We administered the Supernormality Scale (SS), the Minnesota Multiple Personality Inventory‐2 (Restructured Form, MMPI‐2‐RF), the Narcissistic Personality Inventory (NPI) and the Beck Depression Inventory‐II (BDI‐2) to 147 patients a...

We show that, in contrast to Brewin, Li, Ntarantana, Unsowrth, and McNeilis (2019), large proportions of laypersons believe in the scientifically controversial phenomenon of unconscious repressed memories. We provide new survey data showing that when participants are asked specific questions about what they mean when they report that traumatic memo...

In two experiments, we tested the hypothesis that guilt feelings would elevate the probability of making a false confession. In Experiment 1 (N = 146), a confederate induced guilt feelings by asking participants to cheat on a task. The experimenter then falsely accused participants of having pressed a forbidden key, causing a computer crash. In Exp...

Clinicians tend to overestimate their ability to recognize feigning behavior in psychiatric patients, especially if it concerns patients who have been admitted for observation. Feigning can be either externally motivated (e.g., for financial compensation, known as malingering) or internally motivated (e.g., to assume the “sick role,” known as facti...

Performing eye movements during memory retrieval is considered to be important for the therapeutic effect of eye movement desensitization and reprocessing (EMDR). We conducted a meta-analysis of laboratory studies that compared the effects of eye movements and/or alternative dual tasks (e.g., counting) on the vividness and emotionality of negative...

Factitious disorder and malingering are two forms of abnormal illness behaviour in which mental or somatic symptoms are deliberately fabricated or grossly exaggerated or otherwise grossly misrepresented. They are forms of other-deceit, with the person in question assumed to be fully aware of this deceit. The central distinguishing feature of both i...

Background: Fantasy proneness has been linked to dissociative symptoms and adverse childhood experiences. AIM: To review and meta-analyze the empirical literature on fantasy proneness (as indexed by the Creative Experiences Questionnaire) that appeared between 2000 and 2018. METHOD: We searched Google Scholar to identify relevant papers and subjec...

Diverse geleerden hebben zich afgevraagd waarom juri-disch taalgebruik nogal eens de indruk wekt moedwillig mistig en nodeloos ingewikkeld te zijn. Willen rechters, officieren en advocaten dan niet begrepen worden door diegenen tot wie zij zich richten? Sprekend over rechters merkte de emeritus hoogleraar rechtspsychologie Hans Crombag ooit op dat...

Psychodiagnostiek behoort tot de kroonjuwelen van ons vak, schrijven Harald Merckelbach en Brechje Dandachi-FitzGerald. Des te meer reden om eens stil te staan bij de valkuilen waarin de psychodiagnosticus kan tuimelen. Zoals de neiging om opdrachtgevers of verwijzers ter wille te zijn. Over deze en andere valkuilen gaat dit artikel. 'Goede diagnos...

What does believing in repressed memory mean? In a recent paper in this journal, Brewin, Li, Ntarantana, Unsworth, and McNeilis (in press; Study 3) argued that when people are asked to indicate their belief in repressed memory, they actually think of deliberate memory suppression rather than unconscious repressed memory. They further argued that in...

Can purely psychological trauma lead to a complete blockage of autobiographical memories? This longstanding question about the existence of repressed memories has been at the heart of one of the most heated debates in modern psychology. These so-called memory wars originated in the 1990s and many scholars have assumed that they are over. We demonst...

To check the credibility of impairments reported by refugees, so-called performance validity tests may be administered. We explored whether a psychotic condition may compromise performance on such test in patients admitted to a referral center for refugee mental health in the Netherlands (n = 231). We selected patients with no clear incentive to ex...

Voluntary false confessions, or blame-taking behavior to protect another person, are likely to occur at a high rate in the general and the criminal population (Sigurdsson & Gudjonsson, 1996; Willard et al., 2015). This can lead to wrongful convictions while actual culprits run free. Surprisingly, this topic has received little attention. For unders...

Previous studies found that misleading feedback may increase self-reported symptoms. Does this reflect social demand or internalized misinformation? We investigated whether suggestive misinformation may escalate symptoms when it is provided in a context that minimizes social demand. Eighty participants completed the Checklist for Symptoms in Daily...

Objective: The Self-Report Symptom Inventory (SRSI) is a new symptom validity test that, unlike other symptom over-reporting measures, contains both genuine symptom and pseudosymptom scales. We tested whether its pseudosymptom scale is sensitive to genuine psychopathology and evaluated its discriminant validity in an instructed feigning experiment...

The Modified Stroop Task (MST) effect refers to a prolonged reaction time (RT) in color-naming words related to an individual's disorder. Some authors argue that its absence in people who claim symptoms might be an indication of feigning. We tested whether the MST effect is robust against feigning attempts and compared its absence as an index of fe...

Brand et al.’s (2018) response—as well as previous works by some of the authors—reveal a recurrent and concerning picture of using lengthy, but flawed, arguments to promote the concept of dissociative amnesia. Our focus here is not so much on the weak-to-moderate correlation between measures of trauma and dissociation—we concentrate more on the wea...

Expert Witnesses, Dissociative Amnesia, and Extraordinary Remembering: Response to Brand et al.

Ethics committees (ECs) regulate research activities to maintain research participants’ autonomy and to protect them from harm and injury. No research to date attempted to establish how much risk is involved in social science research. Using a survey approach, we set out to estimate the risk of being involved in an incident for research participant...

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Children are often viewed as poor eyewitnesses. Fact-finders, lawyers, and researchers assume that children are exceptionally prone to accept external suggestive (leading) questions and to create false memories. Is this assumption justified? This review will show it is not. First, studies on spontaneous false memories— elicited without any suggesti...

Hand preference may be crucial in the forensic domain, notably in cases where the assailant is known to be left‐handed and the defendant claims to be right‐handed (or vice versa). In such cases, forensic psychologists or physicians may be asked to test the hand preference of the defendant. However, hand preference may be faked. The case described h...

In this comment on Patihis and Pendergast (2018), we challenge an assumption that underpins recovered memory therapies: that there exists a close link of traumatic experiences with dissociation. We further suggest that (a) researchers examine how therapists who believe in repressed memories instill this belief in clients and establish expectations...

Suggestibility is regarded as a major issue when children testify in court. Many legal professionals and memory researchers view children as inferior witnesses. Although differences in suggestibility exist between children and adults, they are much more complex than is usually assumed. We show that under certain conditions, adults are more suscepti...

Psychotherapie beoogt patiënten beter te maken, maar kan om diverse redenen in deze opzet falen. Therapeutisch falen is een belangrijk onderwerp, die erkenning was tot voor kort niet vanzelfsprekend, stellen Harald Merckelbach en collega's. 'Dat psycho­ therapeuten mislukkingen nogal eens over het hoofd te zien, komt onder meer omdat ze geen classi...

Psychotherapie beoogt patiënten beter te maken, maar kan om diverse redenen in deze opzet falen. Therapeutisch falen is een belangrijk onderwerp, die erkenning was tot voor kort niet vanzelfsprekend, stellen Harald Merckelbach en collega's. 'Dat psycho­ therapeuten mislukkingen nogal eens over het hoofd te zien, komt onder meer omdat ze geen classi...

We recently made the case that associative activation is a viable mechanism underlying false memory formation and hence, also false memory formation in psychopathology (Otgaar, Muris, Howe, & Merckelbach, 2017). Tryon (in press) argued that our description of associative activation did not meet the criteria of causation and explanatory value in ord...

Forensic psychologists are sometimes faced with the task of educating triers of fact about the evidential weight of dissociative experiences reported by claimants in litigation procedures. In their two-part essay, Brand et al. (Psychological Injury and Law, 10, 283–297, 2017a; Psychological Injury and Law, 10, 298–312, 2017b) provide advice to expe...

We examined whether self-reported symptoms are affected by explicit and implicit misinformation. In Experiment 1, undergraduates ( N = 60) rated how often they experienced somatic and psychological symptoms. During a subsequent interview, they were exposed to misinformation about 2 of their ratings: One was inflated (upgraded misinformation), where...

It is well known that the use of tranylcypromine in combination with amphetamines may induce a potentially lethal hypertensive crisis. That such a complication may also occur when tranylcypromine is combined with khat, however, is less known. We describe the case of a young patient who received a low dose of tranylcypromine combined with a small am...

Some researchers argue that the modified Stroop task (MST) can be employed to rule out feigning. According to these authors, modified Stroop interference effects are beyond conscious control and therefore indicative of genuine psychopathology. We examined this assumption using a within-subject design. In the first session, students (N = 22) respond...

published in: De Psycholoog, 53 (3), 32-40.

Houben_Open_Practices_Disclosure – Supplemental material for Lateral Eye Movements Increase False Memory Rates

Several studies on the verifiability approach found that truth-tellers report more verifiable details than liars. Therefore, we wanted to test whether such a difference would emerge in the context of malingered symptoms. We obtained statements from undergraduates (N = 53) who had been allocated to three different conditions: truth-tellers, coached...

Little is known about the personality characteristics of those who have experienced a “Near-Death Experience” (NDE). One interesting candidate is fantasy proneness. We studied this trait in individuals who developed NDEs in the presence (i.e., classical NDEs) or absence (i.e., NDEs-like) of a life-threatening situation. We surveyed a total of 228 i...

Choice blindness for identification decisions refers to the inability of eyewitnesses to detect that an originally recognized target was swapped for a non-identified lineup member. The robustness of the effect calls for measures that can prevent or reduce the negative consequences of choice blindness manipulations. Here, we investigated whether pre...

Purpose To investigate the predictive value of antisocial personality disorder (ASPD) and features of ASPD (i.e., lack of remorse, blame externalization, and deceitfulness) for symptom exaggeration. Methods A sample of forensic psychiatric patients (N = 57) was asked to complete several self‐report instruments (measuring symptom exaggeration, lack...

Previous studies showed that feigning amnesia for a crime impairs actual memory for the target event. Lack of rehearsal has been proposed as an explanation for this memory-undermining effect of feigning. The aim of the present study was to replicate and extend previous research adopting a mock crime video instead of a narrative story. We showed par...

False memories can result in severe legal consequences including the imprisonment of innocent people. False memory in eyewitnesses is the largest factor contributing to miscarriages of justice in the United States. To date, no study has focused on how false memories might play a role in the Chinese legal system. The purpose of this review is to sum...

The foremost goal of an investigative interview is to obtain information from a suspect, witness, or source. Most of the literature on information disclosure during investigative interviews has focused on communication and the interpersonal dynamics between investigator and interviewee. Little attention has been given to the environment in which th...

We examined the influence of co-witness discussion on the metacognitive regulation of memory reports. Participants (N = 92) watched a crime video. Later, a confederate confidently agreed with (gave confirming feedback), disagreed with (gave disconfirming feedback), or gave no feedback (control) regarding participants’ answers to questions about the...

Behavioural observation programmes are becoming increasingly popular at transportation hubs, sporting events, and other large crowd gatherings. Premise of these programmes is that malicious intention can be accurately deduced from observable behaviour. In a recent article published in this journal, Wijn et al. (2017, Legal and Criminological Psycho...

Posttraumatic stress disorder (PTSD) may affect victims of crime, but may also be reported by offenders. In the postappeal phase, offenders may claim to suffer from chronic PTSD and argue that this indicates diminished criminal responsibility at the time the index crime was committed. As members of a Dutch criminal cases review commission, we recen...