Isabel Thielmann

Max Planck Institute for the Study of Crime Security and Law

A recurrent observation in personality judgments is that individuals’ ratings of others’ personalities are positively linked to their self-description, and that such “assumed similarity” effects appear to be trait-specific. However, the extent of and explanations for assumed similarity have been addressed only insufficiently. To close this gap, we...

Based on lexical studies, the HEXACO Model of Personality has been proposed as a model of basic personality structure, summarizing individual differences in six broad trait dimensions. Although research across various fields relies on the HEXACO model increasingly, a comprehensive investigation of the nomological net of the HEXACO dimensions is mis...

Decades of research document individual differences in prosocial behavior using controlled experiments that model social interactions in situations of interdependence. However, theoretical and empirical integration of the vast literature on the predictive validity of personality traits to account for these individual differences is missing. Here, w...

Some individuals resort to crime; others refrain. Why is that? Different answers to this question have been proposed within criminology while paying surprisingly little attention to the concept of personality. On closer inspection though, concepts akin to personality (e.g., criminal character, criminal propensity, self-control) run like a unifying...

For decades, a recurring question in person perception research has been whether people’s perceptions of others’ personality traits are related to how they see themselves on these traits. Indeed, evidence for such “assumed similarity” effects has been found repeatedly, at least for certain characteristics. However, recent research suggests that the...

Unethical acts are often witnessed by bystanders who may lie to cover up for the transgressor, thereby helping them avoid sanctions. Here, we investigate the dispositional basis of such unethical loyalty, including the psychological processes involved. Interestingly, as unethical loyalty helps the transgressor, it sets prosociality against honesty—...

We propose a framework in which interventions are described as situations affording the expression of certain personality traits to provide a systematic understanding of differential intervention response by personality traits. The goal of the present paper is twofold: 1) elaborate on the proposed framework, and 2) provide an initial test of this f...

Honesty, defined as freedom from fraud or deception, is widely valued in many aspects of life, from personal relationships to professional settings. Yet acts of dishonesty remain widespread, including political and corporate scandals, misinformation, personal betrayal, and so on. Understanding honesty and the factors that influence it provides insi...

The notion that political orientation is linked to prosociality has been voiced by many, suggesting that supporters of left-wing parties and ideologies may favor prosociality more than supporters of right-wing parties and ideologies. However, evidence for this proposition is inconclusive. We conducted a large-scale, preregistered analysis of the re...

A fundamental assumption about human behavior forming the backbone of trait theories is that, to some extent, individuals behave consistently across structurally comparable situations. However, especially for unethical behavior, the consistency assumption has been severely questioned, at least from the early 19th century onwards. We provide a stric...

Despite notable progress in the study of dishonest behavior and in particular the identification of personality traits (most notably, Honesty-Humility) that are robust predictors of individual differences in dishonesty, prior research has also left several traits untested or yielded inconsistent or inconclusive findings for other traits. We herein...

Dishonest behaviours such as tax evasion impose significant societal costs. Ex ante honesty oaths—commitments to honesty before action—have been proposed as interventions to counteract dishonest behaviour, but the heterogeneity in findings across operationalizations calls their effectiveness into question. We tested 21 honesty oaths (including a ba...

The idea that strong situations restrict variance in behaviors has been treated as a maxim in psychology. Prior work has, however, offered inconclusive support for this proposition. We aimed to overcome the limitations of prior research to conclusively test the restricted variance hypothesis derived from the situational strength framework. Specific...

Scholars from various fields have suggested that criminal victimization can shatter generalized trust. Whereas small average effects in longitudinal studies provide only weak support for this claim, victimization effects may be stronger for specific crime types and multiple victimization. To test this assumption, we estimated various victimization...

Prosocial behavior often entails the possibility to be exploited by other people. Correspondingly, situations affording prosocial behavior are often characterized by one’s dependence on others’ unknown behavior. In such situations, actors will arguably assess the risk of being taken advantage of by others before making a decision. Thus, prosocial b...

Objective and Background According to a recently proposed theoretical framework, different personality traits should explain pro‐social behavior in different situations. We empirically tested the key proposition of this framework that each of four “core tendencies” (i.e., the shared variance of related traits) specifically predicts pro‐social behav...

Prosocial behavior often entails the possibility to be exploited by other people. Correspondingly, situations affording prosocial behavior are often characterized by one’s dependence on others’ unknown behavior. In such situations, actors will arguably assess the risk of being taken advantage of by others before making a decision. Thus, prosocial b...

Dishonest behaviors such as tax evasion impose significant societal costs. Ex-ante honesty oaths—commitments to honesty before action—have been proposed as useful interventions to counteract dishonest behavior, but the heterogeneity in findings across operationalizations calls their effectiveness into question. We tested 21 honesty oaths (including...

Motivated by theoretical accounts positing that participation in intergroup conflict is driven by a desire to promote the in-group, past studies have explored the link between prosocial personality dimensions and out-group harm. However, while dimensions such as Honesty-Humility predict in-group cooperation, they do not explain out-group harm. Acro...

Explaining prosocial behavior is a central goal in classic and contemporary behavioral science. Here, for the first time, we apply modern machine learning techniques to uncover the full predictive potential that personality traits have for prosocial behavior. We utilize a large-scale dataset ( N = 2707; 81 personality traits) and state-of-the-art s...

The current registered report investigated whether individuals high in narcissistic rivalry are more likely to attain status when they have the opportunity to punish uncooperative group members than when they have the opportunity to share their resources with others. We conducted a lab-based behavioral experiment (N = 644) in which groups of seven...

The current registered report investigated whether individuals high in narcissistic rivalry are more likely to attain status when they have the opportunity to punish uncooperative group members than when they have the opportunity to share their resources with others. We conducted a lab-based behavioral experiment (N = 644) in which groups of seven...

Explaining prosocial behavior is a central goal in classic and contemporary behavioral science. Here, for the first time, we apply modern machine learning techniques to uncover the full predictive potential that personality traits have for prosocial behavior. We utilize a large-scale dataset (N = 2,707; 81 personality traits) and state-of-the-art s...

Objective: Among basic personality traits, Honesty-Humility yields the most consistent, negative link with dishonest behavior. The theoretical conceptualization of Honesty-Humility, however, suggests a potential boundary condition of this relation, namely, when lying is prosocial. We therefore tested the hypothesis that the association between Hone...

Populism and beliefs in conspiracy theories fuel societal division as both rely on a Manichean us-versus-them, good-versus-evil narrative. However, whether both constructs have the same dispositional roots is essentially unknown. Across three studies conducted in two different countries and using diverse samples (total N = 1,888), we show that popu...

Objective: Meat consumption has a host of serious negative consequences for nonhuman animals, underprivileged humans, and the natural environment. Several interventions have been developed to encourage meat reduction but to relatively limited effect. There is also a range of established predictors of meat consumption, but much less is known about...

Two participants completing a psychometric scale may leave wildly different responses yet attain the same mean score. Moreover, the mean score often does not represent the bulk of participants’ responses, which may be skewed, kurtotic, or bimodal. Even so, researchers in psychological science often aggregate item scores using an unweighted mean or...

Researchers and practitioners have long been interested in the relations of basic personality domains with health. Whereas previous meta-analyses have focused on the Big Five traits, we provide the first meta-analysis of the relations between the HEXACO domains, as assessed by HEXACO Personality Inventories, and various health outcomes ( k = 276, N...

Typically, up to four dark traits, i.e., the dark tetrad, are investigated to explain the dispositional side of aversive relationship behaviors (ARBs). However, the picture across studies is scattered and inconclusive: All dark tetrad traits show similar zero-order relations with ARBs and multiple regressions analyses produced different results reg...

Objective: There is an ongoing debate in personality research whether the common core of aversive ("dark") traits can be approximated by or even considered equivalent to one of the constructs that have been labeled "Agreeableness". In particular, it has been suggested that the low pole of (what we term) AG+, a broad blend of Big Five Agreeableness...

Parochial altruism suggests that humans are intrinsically motivated to harm out-groups, and that this is tightly connected to a preference for benefitting their in-group. Yet, there is little evidence for the kind of unconditional out-group harm suggested by this account, nor for the assertion that it would be associated with in-group cooperation....

Zusammenfassung In der Wissensgrundlage der kriminologischen Forschung bestehen gegenwärtig beachtliche Lücken: Es mangelt an wirklich interdisziplinärer Forschung; das Verständnis, wie Persönlichkeitseigenschaften mit kriminellem Verhalten zusammenhängen, ist begrenzt; dem Potenzial neuer Technologien, die helfen können, ein besseres Verständnis f...

Personality and social relationships influence each other in multiple and consequential ways. To understand how people differ from each other in their personality and social behavior, how these differences develop, and how this affects further life outcomes, we need to better understand the interplay of personality and social relationships. Here, w...

Situational strength is a key characteristic of situations that has been proposed as a main determinant of when personality may (and may not) affect individuals’ behavior. However, to date, a measure assessing situational strength in various situations and thus, across contexts, is lacking. We followed a 10-step procedure in three phases (item deve...

Individuals differ in how they weigh their own utility versus others'. This tendency codefines the dark factor of personality (D), which is conceptualized as the underlying disposition from which all socially and ethically aversive (dark) traits arise as specific, flavored manifestations. We scrutinize this unique theoretical notion by testing, for...

Whereas research focusing on stable dispositions has long attributed ethically and socially aversive behavior to an array of aversive (or ‘dark’) traits, other approaches from social-cognitive psychology and behavioral economics have emphasized the crucial role of social norms and situational justifications that allow individuals to uphold a positi...

Evolutionary Psychology has considered a Fast Life History Strategy (FLHS), denoting an individual’s tendency to invest more resources in proliferation than in child-rearing, to be responsible for the emergence of aversive traits. Empirical evidence for this notion has been inconsistent, however. Herein, we tested whether FLHS is an adequate repres...

We respond to the comments (https://doi.org/10.5964/ps.9227) on our “Ten Steps” paper (https://doi.org/10.5964/ps.6029), focusing on the most prominent themes: (1) What motivates scientists?, (2) Consensus-building (Is our field ready? May there be adverse side-effects? How shall we do it?), (3) How may institutional change be facilitated?, (4) Div...

This target article is part of a theme bundle including open peer commentaries (https://doi.org/10.5964/ps.9227) and a rejoinder by the authors (https://doi.org/10.5964/ps.7961). We point out ten steps that we think will go a long way in improving personality science. The first five steps focus on fostering consensus regarding (1) research goals, (...

Prosocial behavior is crucial for the flourishing of human societies and it comes along in a beautiful variety of expressions. Humans help strangers they will never meet again, they volunteer and donate for a good cause, and they care intensively about their friends and family. The richness of theories, perspectives, and methodological approaches d...

For decades, a recurring question in person perception research has been whether people’s perceptions of others’ personality traits are related to how they see themselves on these traits. Indeed, evidence for such “assumed similarity” effects has been found repeatedly, at least for certain characteristics. However, recent research suggests that the...

Individual differences in prosocial behavior have been consistently observed in a variety of contexts. Here, we summarize and critically discuss recent developments in two research agendas on the dispositional basis of human prosociality: a personality approach, proposing a variety of trait concepts and corresponding measures to predict prosocial b...

In clinical psychopathology research, up to seven traits have been suggested as instances of antagonistic psychopathology. Those antagonistic traits, in turn, are commonly viewed as reflections of low Agreeableness as per the Big Five (BF‐AG). However, specific theoretical differences between antagonistic traits suggest that other broad and basic d...

Despite the widespread use of the HEXACO model as a descriptive taxonomy of personality traits, there remains limited information on the test-retest reliability of its commonly-used inventories. Studies typically report internal consistency estimates, such as alpha or omega, but there are good reasons to believe that these do not accurately assess...

Im Leitartikel „Replikationskrise, p-hacking und Open Science – Eine Umfrage zu fragwürdigen Forschungspraktiken in studentischen Projekten und Impulse für die Lehre“ werden wichtige empirische Befunde präsentiert, die aufzeigen, inwieweit sich die Weiterentwicklung der psychologischen Wissenschaft aufgrund der Replikationskrise in der deutschsprac...

Does giving behavior in economic games reflect true prosocial preferences or is it due to confusion? Research showing that trait Honesty-Humility accounts for giving behavior suggests the former, whereas research showing that participants give money to a computer might suggest the latter. In three preregistered, well-powered studies, we examined th...

Samenvatting De COVID-19 pandemie kan opgevat worden als een situatie waarin een specifieke vorm van trekactivatie plaatsvindt waarbij persoonlijkheid de kans op besmetting met het COVID-19 virus kan beïnvloeden. In dit onderzoek wordt gekeken naar de relatie tussen HEXACO persoonlijkheid en COVID-19 vermijdingsgedrag, dat wil zeggen het omgaan met...

Does giving behavior in economic games reflect true prosocial preferences or is it due to confusion? Research showing that trait Honesty-Humility accounts for giving behavior suggests the former, whereas research showing that participants give money to a computer might suggest the latter. In three preregistered, well-powered studies, we examined th...

Gossip—a sender communicating to a receiver about an absent third party—is hypothesized to impact reputation formation, partner selection, and cooperation. Laboratory experiments have found that people gossip about others' cooperativeness and that they use gossip to condition their cooperation. Here, we move beyond the laboratory and test several p...

Models of basic personality structure are among the most widely used frameworks in psychology and beyond, and they have considerably advanced the understanding of individual differences in a plethora of consequential outcomes. Over the past decades, two such models have become most widely used: the Five Factor Model (FFM) or Big Five, respectively,...

[Invited commentary]. I see great potential in the approach proposed by Rouder and Haaf. First, using an example from unethical decision making, I demonstrate that considering quantitative individual differences alone can make us overlook important psychological phenomena that are only visible at the individual level. Thus, we should by default com...

The field of prosociality is flourishing, yet researchers disagree about how to define prosocial behavior and often neglect defining it altogether. In this review, we provide an overview about the breadth of definitions of prosocial behavior and the related concept of altruism. Common to almost all definitions is an emphasis on the promotion of wel...

The field of prosociality is flourishing, yet researchers disagree about how to define prosocial behavior and often neglect defining it altogether. In this review, we provide an overview about the breadth of definitions of prosocial behavior and the related concept of altruism. Common to almost all definitions is an emphasis on the promotion of wel...

Participation in intergroup conflict is often framed as a matter of ‘in-group love’ or ‘out-group hate’. Indeed, theoretical accounts including social identity theory and parochial altruism suggest that such group-based preferences are inextricably linked. According to this view, individuals engage in intergroup conflict, including harmful behaviou...

Social desirability (SD) scales have been used for decades in psychology and beyond. These scales are sought to measure individuals’ tendencies to present themselves overly positive in self‐reports, thus allowing to control for SD biases. However, research increasingly questions the validity of SD scales, proposing that SD scales measure substantiv...

Deception of research participants has long been and remains a hot-button issue in the behavioral sciences. At the same time, the field of psychology is fortunate to have an ethics code to rely on in determining whether and how to use and report on deception of participants. Despite ongoing normative controversies, the smallest common denominator a...

The outbreak of a global pandemic such as COVID-19 poses a challenge for societies across the world. Lacking both vaccination and medical treatment, the only way to combat the spread of a virus in its early stages are behavioral measures, particularly physical distancing behavior. The present work proposes three pillars of individuals’ engagement i...

Prosocial behaviors constitute vital ingredients for all types of social interactions and relationships as well as for society at large. Corresponding to this significance, the study of prosocial behaviors has received considerable attention across scientific disciplines. A striking feature of this research is that most disciplines rely on economic...

Prior research using economic games has shown that personality drives cooperation in social dilemmas. In this study, we tested the generalizability of these findings in a real-life social dilemma during the COVID-19 pandemic, namely stockpiling in the presence of low versus high resource scarcity. Honesty-Humility was negatively related to stockpil...

The HEXACO model of personality is currently one of the most widely-used in its field. While numerous studies report HEXACO facet and domain alpha reliabilities (), few have examined its test-retest reliability (rTT)—a fundamental property of psychological tests. We thus report 12-day rTT of the 100-item HEXACO-PI-R domains, facets, and items and c...

Prior research using economic games has shown that personality drives cooperation in social dilemmas. In this study, we tested the generalizability of these findings in a real-life social di-lemma during the COVID-19 pandemic, namely stockpiling in the presence of low versus high resource scarcity. Honesty-Humility was negatively related to stockpi...

The study of volitional personality change has received increasing attention in recent years, suggesting that individuals want to change for the better particularly on those socially desirable characteristics that they lack. However, individuals do not want to change for the better on all (even socially desirable) traits alike. In a meta-analytic s...

The deception of research participants remains a controversial issue in the behavioral sciences. Current ethics codes consistently limit the use of deception to cases in which non-deceptive alternatives are unfeasible and, crucially, require that participants subjected to deception be debriefed correspondingly along with an option to withdraw their...

In light of the recent rise of right-wing populist parties across Europe, it is an intriguing question under which conditions people agree with right-wing political statements. The present study investigates whether mere labelling of political statements as endorsed by a right-wing populist party influences people’s agreement with such statements....

Unethical behavior is often accompanied by others covering up a transgressor’s actions. We devised a novel behavioral paradigm, the Unethical Loyalty Game, to specifically study individuals’ willingness to lie to cover up others’ dishonesty. Specifically, we examined (i) whether and to what extent individuals are willing to lie to cover up others’...

Objective: Although dark traits as studied in mainstream personality research and socially aversive psychopathology as studied in abnormal psychology intend to account for the same classes of behavior, their degree of conceptual and, consequently, empirical correspondence has remained limited at best. We aim to overcome this divide by demonstrating...

In February 2020, the Personality and Diagnostics Chapter (DPPD) of the German Psychological Society (DGPs) tasked this group of authors with outlining what should be considered “good personality science”, as a positive vision of how to improve the credibility of research in the field. We argue in favor of working toward greater consensus about (1)...

In February 2020, the Personality and Diagnostics Chapter (DPPD) of the German Psychological Society (DGPs) tasked this group of authors with outlining what should be considered “good personality science”, as a positive vision of how to improve the credibility of research in the field. We argue in favor of working toward greater consensus about (1)...

We reflect on Ashton and Lee’s reasoning concerning one of the major criticisms that have been voiced against the HEXACO model, namely, that it merely splits Big Five Agreeableness into two related sub-factors. Although the distinction between Honesty-Humility and Agreeableness is reasonable from a theoretical viewpoint, more evidence on the double...

The HEXACO Personality Inventory-Revised (HEXACO-PI-R) has evolved into one of the most heavily applied measurement tools for the assessment of basic personality traits. Correspondingly, the inventory has been translated to several languages for use in cross-cultural research. However, formal tests examining whether the different language versions...

Previous research consistently showed a negative link between Honesty-Humility (HH) and dishonest behavior. However, most prior research neglected the influence of situational factors and their potential interaction with HH. In two incentivized experiments (N = 322, N = 552), we thus tested whether the (subjective) utility of incentives moderates t...

The Standardized Assessment of Severity of Personality Disorder (SASPD) is a 9-item self-report screening instrument and was developed to assess personality disorder (PD) severity according to the initial proposal of ICD-11. Our aim was to investigate the psychometric properties of the German version of the SASPD in nonclinical and clinical samples...

The outbreak of a global pandemic such as COVID-19 poses a challenge for societies across the world. Lacking both vaccination and medical treatment, the only way to combat the spread of a virus in its early stages are behavioral measures, particularly physical distancing behavior. The present work proposes three pillars of individuals’ engagement i...

People’s general tendencies to view others as cold-hearted and manipulative (rather than affectionate and trustworthy) may explain defection in social dilemma situations. To capture idiosyncratic tendencies in other-perceptions, we collected mutual judgments in groups of unacquainted individuals in two studies (N1 = 83, N2 = 413) and extracted perc...

Gossip—a sender communicating to a receiver about an absent third party—is hypothesized to impact reputation formation, partner selection, and cooperation. Lab experiments have found that people gossip about others’ cooperativeness and that they use gossip to condition their cooperation. Here, we move beyond the lab and test several predictions fro...

This chapter outlines how the objective and subjective interdependence structure of social situations can, together with personality, influence behavior. We first review the premises of Interdependence Theory which suggests that six dimensions describe objective characteristics of interdependent situations: mutual dependence, power, conflict, coord...