Peter J. van Koppen

• JD
• Professor (Full) at Vrije Universiteit Amsterdam

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The culture in which individuals are socialised can play a role in shaping their eyewitness memory reports. Drawing on self‐construal theory, we examined cultural differences in the misinformation effect. In a mock witness paradigm, participants sampled from collectivistic (Ghana; n = 65) and individualistic (United Kingdom; n = 62) cultures were e...

The questions to be answered in forensic mental health reports are challenging. Experts have the task to assess a defendant’s past as well as their current and future mental state. To support forensic mental health experts in that complex task, best practices have been developed nationally and internationally. In the Netherlands, there are guidelin...

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.

Child abuse is a dangerous situation for an infant. Professionals need to weigh the risk of failing to act when children are seriously harmed against the serious harm done by carrying out safeguarding interventions. In severe cases, foster care might be advisable. The negative effects for the child’s psychosocial development requires that such plac...

A newborn girl had, from two weeks on, small bruises on varying body locations, but not on her chest. Her Armenian grandmother easily bruised, too. Her mother was diagnosed with hypermobility-type Ehlers-Danlos-Syndrome (hEDS), an autosomal dominant connective tissue disorder, with a 50% inheritance probability. Referral to a University Medical Cen...

Until now, supportive evidence for alibis has been conceptualised into two distinct types: witness and physical evidence. The present study examined whether knowledge, as a third type of supportive evidence, can contribute to the understanding of evidence for alibis. Three experiments were conducted in which police detectives, laypersons and underg...

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...

Research has repeatedly shown that accusatory questions posed during an investigative interview are indicative of biased beliefs about suspect guilt. Linguistic research has shown that the verbs used in utterances can be indicative of biased beliefs about another person. In the present study we examined question type and the verbs used in question...

In this chapter the Dutch scenario theory is presented, which was developed in the 1990s by Peter van Koppen and Anne Ruth Mackor in collaboration with Willem Wagenaar and Hans Crombag. The scenario theory builds on the descriptive psychological account featuring factfinders who think in terms of a story when they are reasoning about evidence to de...

De vraag hoe traumatische ervaringen, zoals seksueel misbruik, worden herinnerd behoort tot een van de meeste verhitte debatten in de psychologie. Het gaat dan met name om de kwestie van verdringing en of traumatische ervaringen onbewust kunnen worden opgeslagen. Otgaar en collega’s laten zien dat het debat hierover aan een stevige opmars bezig is....

Are the cognitive sciences relevant for law? How do they influence legal theory and practice? Should lawyers become part-time cognitive scientists? The recent advances in the cognitive sciences have reshaped our conceptions of human decision-making and behavior. Many claim, for instance, that we can no longer view ourselves as purely rational agent...

Having to explain a decision has often been found to have a positive effect on the quality of a decision. We aimed to determine whether different accountability requirements for judges (i.e., having to justify their decision or having to explicate their decision) affect evidence use. Those requirements were compared to instructions based on the fal...

In Linkebeek bij Brussel overleed in augustus 2003 Chantal Beaudelet door een schot dat was afgevuurd met het dienstwapen van haar vriend Jack Darne. Chantal en Jack lagen op dat moment samen in bed. Drie jaar later werd Jack veroordeeld voor haar moord. Jack zegt dat Chantal zelfmoord pleegde en dat hij ten onrechte al veertien jaar vastzit voor d...

Order of evidence presentation affects the evaluation and the integration of evidence in mock criminal cases. In this study, we aimed to determine whether the order in which incriminating and exonerating evidence is presented influences cognitive dissonance and subsequent display of confirmation bias. Law students (N = 407) were presented with a mu...

In this case study it was investigated whether foreign DNA may get encapsulated in a cosmetic gel nail. It was inspired by a murder case in which the main suspect claims that he was wrongly convicted. Most of the evidence in the case was circumstantial. The most direct piece of evidence was DNA of the suspect found beneath the victim’s fingernails....

The analysis of competing hypotheses (ACH) has been suggested to be a method that can protect against confirmation bias in the context of intelligence analysis. In the current study, we aimed to determine whether ACH could counter confirmation bias in the reasoning with evidence in the context of criminal law proceedings. Law students (N = 191) rec...

Purpose When people migrate to new cultures, they adapt to their new culture while at the same time retaining the norms of their original culture. The phenomenon whereby migrants adapt to the cultural norms of a host culture has been referred to as acculturation. Using a mock witness paradigm, we examined the acculturation effect in the eyewitness...

Denault, V., Plusquellec, P., Jupe, L. M., St-Yves, M., Dunbar, N. E., Hartwig, M., … van Koppen, P. J. (2020). L’analyse de la communication non verbale: Les dangers de la pseudoscience en contextes de sécurité et de justice [The analysis of nonverbal communication: The dangers of pseudoscience in security and justice contexts]. Revue internationa...

Purpose Forensic interviewers often face witnesses who are unwilling to cooperate with the investigation. In this experimental study, we examined the extent to which cooperativeness instructions affect information disclosure in a witness investigative interview. Methods One hundred and thirty‐six participants watched a recorded mock‐crime and were...

Purpose Distinguishing accurate from inaccurate identifications is a challenging issue in the criminal justice system, especially for biased police line‐ups. That is because biased line‐ups undermine the diagnostic value of accuracy post‐dictors such as confidence and decision time. Here, we aimed to test general and eyewitness‐specific self‐rating...

For security and justice professionals (e.g., police officers, lawyers, judges), the thousands of peer-reviewed articles on nonverbal communication represent important sources of knowledge. However, despite the scope of the scientific work carried out on this subject, professionals can turn to programs, methods, and approaches that fail to reflect...

Increasingly, investigators conduct interviews with eyewitnesses from different cultures. The culture in which people have been socialised can impact the way they encode, remember, and report information about their experiences. We examined whether eyewitness memory reports of mock witnesses from collectivistic (sub‐Saharan Africa) and individualis...

Para los profesionales de la seguridad y la justicia (policías, abogados, jueces), los miles de artículos revisados por pares sobre comunicación no verbal representan fuentes importantes de conocimiento. Sin embargo, a pesar del alcance del trabajo científico realizado sobre este tema, los profesionales pueden recurrir a programas, métodos y enfoqu...

Using a mock witness methodology, we investigated the predictive value of metamemory measures and objective memory tests as indicators of eyewitness free recall performance. Participants (n = 208) first completed a metamemory assessment that included assessments of self-rated memory capacity, memory development and use of strategies. In a separate...

Using a mock witness methodology, we investigated the predictive value of metamemory measures and objective memory tests as indicators of eyewitness free recall performance. Participants (n = 208) first completed a metamemory assessment that included assessments of self-rated memory capacity, memory development and use of strategies. In a separate...

Previous findings show that collaborative interviews with pairs of eyewitnesses can result in more accurate testimony than individual interviews, and that partners remember more together if they acknowledge, repeat, rephrase and elaborate upon each other's contributions. In the present study, we investigated whether these findings differ for pairs...

Controlled studies have demonstrated that guilt-presumptive questions usually accompany interviewer guilt bias and accusatory behaviours towards a suspect. When evaluating police-suspect interviews, however, conventional methods primarily focus on the appropriateness of questions, and guilt-presumption is not featured as a questioning strategy. Ins...

Metamemory can be defined as the knowledge about one's memory capabilities and about strategies that can aid memory. In this paper, we describe the development and validation of the Eyewitness Metamemory Scale (EMS), tailored specifically for use in face memory and eyewitness identification settings. Participants (N = 800) completed the EMS and oth...

Distinguishing accurate from inaccurate identifications is a challenging issue in the criminal justice system, especially for biased police lineups. That is because biased lineups undermine the diagnostic value of accuracy postdictors such as confidence and decision time. Here, we aimed to test general and eyewitness-specific self-ratings of memory...

Identifications made by eyewitnesses are compelling evidence for prosecuting a suspect, but inaccurate identifications can have severe consequences including the conviction of innocent persons. Based on metacognitive frameworks, we aimed to distinguish accurate from inaccurate identification decisions by using metamemory assessments. Participants (...

In this paper, we present a scenario approach and apply it to the Simonshaven case. We offer an outline in which we spell out the core notions of the scenario approach. Next, we give a summing up of criteria to assess and compare scenarios. We use examples of the Simonshaven case to illustrate how the scenario‐approach works. The last section conta...

Expertise en Recht

Metamemory can be defined as the knowledge about one’s memory capabilities and about strategies that can aid memory. In this paper, we describe the development and validation of the Eyewitness Metamemory Scale (EMS), tailored specifically for use in face memory and eyewitness identification settings. Participants (N = 800) completed the EMS and oth...

Expectancy effects are known to influence behaviour so that what is expected appears to be true. In this study, expectancy was induced using (fabricated) information about honesty and specific group membership. Targets were tested in a non-accusatory interview environment using neutral and information-gathering questions. It was hypothesized that t...

The aim of the current study was to obtain a snapshot of police officer’s beliefs about factors that may influence the outcome of the investigative interview with suspects. We created a 26-item survey that contained statements around three specific themes: best interview practices, confessions and interviewee vulnerabilities. Police officers (N = 1...

The present study was designed to determine whether differences exist between true and false alibis and how accurate police detectives and lay people are in determining the veracity of alibis. This article provides a replication of the research by Culhane et al. (2013 Culhane, S. E., Kehn, A., Horgan, A. J., Meissner, C. A., Hosch, H. M., & Wodahl,...

A large body of research has described the influence of context information on forensic decision‐making. In this study, we examined the effect of context information on the search for and selection of traces by students (N = 36) and crime scene investigators (N = 58). Participants investigated an ambiguous mock crime scene and received prior inform...

After witnessing an incident, police officers may write their report collaboratively. We examined how collaboration influences the amount and accuracy of information in police reports. Eighty-six police officers participated, in pairs, in a live training scenario. Officers wrote a report about the incident, either with their partner or individually...

Expectancy effects are known to influence behaviour so that what is expected appears to be true. In the present study, expectancy was induced using (fabricated) information about honesty and specific group membership. We tested Targets in a non-accusatory interview environment using neutral and information-gathering type questions. We hypothesized...

Pairs of eyewitnesses with a content-focused interaction style remember significantly more about witnessed incidents. We examined whether content-focused retrieval strategies can be taught. Seventy-five pairs of witnesses were interviewed thrice about an event. The first and third interview were conducted individually for all witnesses. The second...

Expectancy effects are known to influence behaviour so that what is expected appears to be true. In the present study, expectancy was induced using (fabricated) information about honesty and specific group membership. We tested Targets in a non-accusatory interview environment using neutral and information-gathering type questions. We hypothesized...

The list of motives by Kanin (1994) is the most cited list of motives to file a false allegation of rape. Kanin posited that complainants file a false allegation out of revenge, to produce an alibi or to get sympathy. A new list of motives is proposed in which gain is the predominant factor. In the proposed list, complainants file a false allegatio...

In this study, we examined how the provision of contextual information and the ability to ask questions and obtain feedback affected mock investigators' interpretation of a crime scene. Participants were randomly assigned to 1 of 4 conditions in a 2 × 2 design and assessed two photographs of the same crime scene. Participants were instructed to wri...

In the present study, how crime scene investigators are informed before going to a crime scene was investigated. In order to gain more insight in the flow of information from emergency call to crime scene, semi-structured interviews were conducted in three different police regions with six crime scene investigators, six forensic team leaders, and s...

In the absence of evidence, asylum seekers are interviewed to assess the credibility of their stories. Few studies have examined whether or not the questions asked in such interviews stimulate the applicant to give lengthy, detailed, and accurate answers. The style, type, and content of the questions asked in order to assess a claim about origin we...

Nowadays, more and more people report about their memories in cross‐cultural contexts. In international criminal settings and asylum procedures, object recognition tests can provide valuable information, for example, about weapons used during a crime or landmarks from the claimed region of origin. This study was the first to compare object recognit...

Pitch presentation accepted to EAPL 2017 (European Association of Psychology and Law) in Mechelen, Belgium. Research examining the mnemonic consequences of witnesses’ cooperation style during investigative interviews.

Symposium accepted to EAPL 2017 (European Association of Psychology and Law) presented in Mechelen, Belgium. These accepted abstracts cover various studies that are diectly applicable to the area of deception detection.

Police detectives, who have to evaluate the believability of an alibi, put high demands on an alibi to be believable because they appear to be unaware of how difficult it can be to present a believable alibi. As a result, erroneously disbelieved alibis are one of the causes contributing to wrongful convictions worldwide. Asking these evaluators to...

False allegations constitute a public problem since they result in a waste of time spent by the police and justice departments, and may cause public and individual harm. A prevalence study was conducted to obtain recent and valid figures of the prevalence of unfounded allegations of rape and unfounded allegations of other crimes. The most recent pu...

Abstract This paper contains a case study, in which we study the criminal file to address the validity of a rape allegation. In this case, a woman accuses her former male partner of raping her repeatedly. The criminal file contains exclusive material that helps to answer the question of validity of the allegations in an objective manner. The allege...

Establishing the origin of those seeking asylum is essential but difficult as asylum seekers often cannot corroborate their origin claim with documents. The aim of the present study was to assess whether asking knowledge questions, sketch questions and impossible questions are valid methods to determine the veracity of an origin claim. Participants...

The aim of the current vignette study is to map the style, type, and themes of questions that are asked when assessing the credibility of asylum seekers’ claims. Sixty-five officials from the Swedish Migration Agency (Migrationsverket), were asked to respond to one out of four different vignettes that contained fictitious asylum narratives. Each vi...

The present study was designed to establish the base rate of alibis and supportive evidence for alibis of non‐offenders. That is impor- tant because the presence and lack of an alibi are often seen as a clear indicator of innocence and guilt, respectively, of a suspect. A large sample of laypersons (N = 841) was randomly assigned to one of 32 condi...

Police officers are often believed to provide more reliable testimony than civilian eyewitnesses. We reviewed the available empirical evidence for this belief. There is some evidence to suggest that police officers do indeed report more accurate details about witnessed events than civilians do, particularly concerning crime-relevant details. That r...

In a large body of research the influence of contextual information on decisions made in a broad range of disciplines has been studied. To date, the influence of these expectancy effects on the crime scene investigation has not been studied. In the present study we explored the effect of prior information given to crime scene investigators on their...

A study was conducted to test whether it is possible to build a model to distinguish true and false allegations of rape based on the theory of fabricated rape. The theory is based on the principle that a false complainant of rape has not been raped and has to fabricate a story while the story ofa true victim is based on recollections of the event....

Purpose Police interviewers are typically instructed to prevent eyewitnesses from talking to each other, because witnesses can contaminate each other's memory. Previous research has not fully examined, however, how discussion between witnesses affects correct and incorrect recall of witnessed events. We conducted quantitative and qualitative analys...

False allegations constitute a problem since they may cause harm. To study the difference between true and false allegations we used a quasi-experimental approach. In the control condition likely true allegations were retrieved from criminal files. The victims, all female, were between the ages of 17 and 53 (M=28.0, SD=10.6). In the experimental co...

The present study was designed to assess whether or not the presentation method and the salaciousness of an alibi affect its evaluation. Community participants (n = 150) were asked to evaluate the salacious or non-salacious alibi of a crime suspect. The alibi was either presented immediately after arrest by the suspect or was changed after the init...

Crimes are often observed by multiple witnesses. Research shows that witnesses can contaminate each other's memory, but potential benefits of co-witness discussion have not yet been investigated. We examined whether witnesses can help each other remember, or prune each other's errors. In a research design with high ecological validity, attendees of...

PurposePolice officers often write reports about witnessed incidents, which may serve as evidence in court. We examined whether incident reports and identifications by police officers, and in particular specialized detectives on surveillance teams, are more complete or more accurate than reports and identifications by civilian observers.Methods Our...

Many people believe that inconsistency is a sign of lying, and that consistency is a sign of truth telling. The present chapter assesses the validity of these popular beliefs. We review the literature on the relationship between consistency and deception, and present an overview of effect sizes obtained in studies on this topic. Four different type...

In a recent case in the Netherlands, a pimp was accused of molesting two of his prostitutes and also of raping one of them.1 Although the police knew of the violent character of the pimp, the case confronted them with a problem: the prostitutes had also accused the pimp of forcing them to sell their bodies, but after the pimp was arrested both cont...

Both the legal system of the Netherlands and that of Germany are inquisitorial systems, at least for criminal cases. One could naively suppose that the differences in legal procedure between the two countries would be negligible compared to differences with accusatorial systems. And, indeed if one spends a day in court in The Netherlands and in Ger...

This paper presents a theory of reasoning with evidence in order to determine the facts in a criminal case. The focus is on the process of proof, in which the facts of the case are determined, rather than on related legal issues, such as the admissibility of evidence. In the literature, two approaches to reasoning with evidence can be distinguished...

Confession made under torturePsychological characteristicsSituational characteristicsCeci n'est pas une confessionThe content of the confession: on forms of knowledgeConclusions AcknowledgementReferences

In this case study, 14 witnesses of an armed robbery were interviewed after 3 months. Security camera recordings were used to assess memory accuracy. Of all information that could be remembered about 84% was correct. Although accurately recalled information had a higher confidence level on average than inaccurately recalled information, the mean ac...

In oktober 1985 werd Marijke Medens met messteken om het leven gebracht bij het benzinestation in Warnsveld. Destijds liep het onderzoek dood, maar in 2001 kwam er nieuwe informatie binnen bij de geheime politie. Daaruit moest blijken dat Mick van Bezemer de moord pleegde, samen met een aantal anderen. Hun namen zouden vermeld staan in een mysterie...

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The murder of a young girl in 2000 in a park in the Dutch town Schiedam and the attempted murder of her friend resulted in a miscarriage of justice that shook Dutch society. After a description of the case, an attempt is made to analyze the factors that caused this miscarriage of justice and other dubious convictions in The Netherlands. Many factor...

Purpose . This study focuses on two psychological mechanisms that may inadvertently affect judges' decisions on proof of guilt and on punishment. It involves mechanisms that are clearly in conflict with formal judicial doctrine. One hypothesis, the conviction paradox , asserts that, faced with very serious offences, a judge's standard of proof will...