Ralph Hertwig

Max Planck Institute for Human Development | MPIB · Center of Adaptive Rationality

Learning the probabilities of multiple events from the environment is an important core competency of any organism. In our within‐participant experiment, participants experienced samples from two distributions, or prospects, each comprised of two to four events, and were required to provide simultaneous, rather than sequential, judgment of the like...

Large online platforms design online environments that steer user attention, raising concerns about a loss of user agency, autonomy and even manipulation. Yet little is known about who users themselves think should control their online environments, and under what circumstances. In our preregistered study, participants across 26 countries (N = 11,6...

Despite a long history of research on democratic backsliding, the process itself − in which the executive branch amasses power and undermines democratic processes and institutions − remains poorly understood. We seek to shed light on the underlying mechanisms by studying democratic near misses: cases in which a period of autocratic governance is qu...

Research on judgment and decision making typically studies “small worlds”—highly simplified and stylized tasks such as monetary gambles—among homogenous populations rather than big real-life decisions made by people around the globe. These transformative life decisions (e.g., whether or not to emigrate or flee a country, disclose one’s sexual orien...

Nearly five billion people use and receive news through social media and there is widespread concern about the negative consequences of misinformation on social media (e.g., election interference, vaccine hesitancy). Despite a burgeoning body of research on misinformation, it remains largely unclear who is susceptible to misinformation and why. To...

Efficiently allocating individuals to work on complex decision problems is a key challenge for groups, organizations, and societies. It involves a crucial trade- off: Increasing the number of individuals working on a task typically improves accuracy, but also increases costs. Research in collective intelligence has proposed a plethora of mechanisms...

Functional responses in the Nucleus Accumbens (NAcc) to risk- and reward-related cues can predict real-life risk-taking behavior. Since NAcc activity depends on neurotransmission from connected brain regions, projections to the NAcc may also predict risk preference. To quantify risk preference, we employed latent variables previously derived in a c...

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...

Behavioral public policy came to the fore with the introduction of nudging, which aims to steer behavior while maintaining freedom of choice. Responding to critiques of nudging (e.g., that it does not promote agency and relies on benevolent choice architects), other behavioral policy approaches focus on empowering citizens. Here we review boosting,...

Collective intelligence underpins the success of groups, organizations, markets and societies. Through distributed cognition and coordination, collectives can achieve outcomes that exceed the capabilities of individuals-even experts-resulting in improved accuracy and novel capabilities. Often, collective intelligence is supported by information tec...

Vaccine hesitancy was a major challenge during the COVID-19 pandemic. A common but sometimes ineffective intervention to reduce vaccine hesitancy involves providing information on vaccine effectiveness, side effects, and related probabilities. Could biased processing of this information contribute to vaccine refusal? We examined the information ins...

Models of heuristics are often predicated on the desideratum that they should possess no free parameters. As a result, heuristic implementations are usually deterministic and do not allow for any choice errors, as the latter would require a parameter to regulate the magnitude of errors. We discuss the implications of this in light of research that...

What motivates people to share and create content online? In real time, we linked each of N=2,762 individual posts (retweets and newly created content) with the self-reported motives from a sample of N=137 highly active US Twitter users over the course of one week. We also captured their total activity of N=48,419 posts over 10 weeks (March-May 202...

Impulsivity is a personality construct frequently employed to explain and predict important human behaviors. Major inconsistencies in its definition and measurement, however, have led some researchers to call for an outright rejection of impulsivity as a psychological construct. We address this highly unsatisfactory state with a large-scale, prereg...

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...

The spread of misinformation through media and social networks threatens many aspects of society, including public health and the state of democracies. One approach to mitigating the effect of misinformation focuses on individual-level interventions, equipping policymakers and the public with essential tools to curb the spread and influence of fals...

Despite a surge of research into misinformation, it is largely unclear who falls for misinformation and why. We conducted a systematic individual participant data meta-analysis covering 256,337 unique choices made by 11,561 participants across 31 experiments. Our meta-analysis reveals the impact of key demographic and psychological factors on onlin...

Here we examine geographical and historical differences in polygenic associations with educational attainment in East and West Germany around reunification. We test this in n = 1902 25-85-year-olds from the German SOEP-G[ene] cohort. We leverage a DNA-based measure of genetic influence, a polygenic index calculated based on a previous genome-wide a...

Self-control is a personality dimension that is associated with better physical health and a longer lifespan. Here, we examined (1) whether self-control is associated with buccal and saliva DNA-methylation (DNAm) measures of biological aging quantified in children, adolescents, and adults, and (2) whether biological aging measured in buccal DNAm is...

Background Although transparency is crucial for building public trust, public health communication during the COVID-19 pandemic was often nontransparent. Methods In a cross-sectional online study with COVID-19 vaccine-hesitant German residents (N = 763), we explored the impact of COVID-19 public health communication on the attitudes of vaccine-hes...

Like biological species, words in language must compete to survive. Previously, it has been shown that language changes in response to cognitive constraints and over time becomes more learnable. Here, we use two complementary research paradigms to demonstrate how the survival of existing word forms can be predicted by psycholinguistic properties th...

Risk preference is an important construct for understanding individual differences in risk taking throughout the behavioral sciences. An active stream of research has focused on better understanding risk preference through its connection to other psychological constructs, in particular, cognitive abilities. Here, we examine two large-scale multimet...

The German Socio-Economic Panel (SOEP) serves a global research community by providing representative annual longitudinal data of respondents living in private households in Germany. The dataset offers a valuable life course panorama, encompassing living conditions, socioeconomic status, familial connections, personality traits, values, preferences...

Why is the empirical evidence for birth‐order effects on human psychology so inconsistent? In contrast to the influential view that competitive dynamics among siblings permanently shape a person's personality, we find evidence that these effects are limited to the family environment. We tested this context‐specific learning hypothesis in the domain...

Research on online misinformation has evolved rapidly, but organizing its results and identifying open research questions is difficult without a systematic approach. We present the Online Misinformation Engagement Framework, which classifies people’s engagement with online misinformation into four stages: selecting information sources, choosing wha...

Functional responses in the Nucleus Accumbens (NAcc) to risk- and reward-related cues can predict real-life risk-taking behavior. Since NAcc activity depends on neurotransmission from connected brain regions, projections to the NAcc may also predict risk preference. To quantify risk preference, we employed latent variables previously derived in a c...

Inequalities and injustices are thorny issues in liberal societies, manifesting in forms such as the gender-pay gap; sentencing discrepancies among Black, Hispanic, and White defendants; and unequal medical-resource distribution across ethnicities. One cause of these inequalities is implicit social bias-unconsciously formed associations between soc...

Self-control is a personality dimension that is associated with better physical health and a longer lifespan. Here we examined (1) whether self-control is associated with buccal and saliva DNA-methylation (DNAm) measures of biological aging quantified in children, adolescents, and adults, and (2) whether biological aging measured in buccal DNAm is...

The increasing prevalence of image-altering filters on social media and video conferencing technologies has raised concerns about the ethical and psychological implications of using Artificial Intelligence (AI) to manipulate our perception of others. In this study, we specifically investigate the potential impact of blur filters, a type of appearan...

Sampling approaches to judgment and decision making are distinct from traditional accounts in psychology and neuroscience. While these traditional accounts focus on limitations of the human mind as a major source of bounded rationality, the sampling approach originates in a broader cognitive-ecological perspective. It starts from the fundamental as...

How do people infer the Bayesian posterior probability from stated base rate, hit rate, and false alarm rate? This question is not only of theoretical relevance but also of practical relevance in medical and legal settings. We test two competing theoretical views: single-process theories versus toolbox theories. Single-process theories assume that...

Importance: Family meals are a formative learning environment that shapes children's food choices and preferences. As such, they are an ideal setting for efforts to improve children's nutritional health. Objective: To examine the effect of extending the duration of family meals on the fruit and vegetable intake in children. Design, setting, and...

Two concepts shaped and continue to shape the discussion on the limits of a liberal and democratic state. First, Mill's harm principle, according to which the fundamental justification for a state exercising power over individuals is to prevent harm being done to others. Second, the distinction between the public sphere, where liberal democracies c...

In online content moderation, two key values may come into conflict: protecting freedom of expression and preventing harm. Robust rules based in part on how citizens think about these moral dilemmas are necessary to deal with this conflict in a principled way, yet little is known about people's judgments and preferences around content moderation. W...

Importance: Hesitancy toward COVID-19 vaccination is a major factor in stagnating uptake rates and in the risk of health care systems becoming overwhelmed. Objective: To compare an interactive risk ratio simulation (intervention) with a conventional text-based risk information format (control) and analyze change in participants' COVID-19 vaccina...

Risk preference impacts how people make key life decisions related to health, wealth, and well-being. Systematic variations in risk-taking behavior can be the result of differences in fitness expectations, as predicted by life-history theory. Yet the evolutionary roots of human risk-taking behavior remain poorly understood. Here, we studied risk pr...

The spread of misinformation through media and social networks threatens many aspects of society, including public health and the state of democracies. A wide range of individual-focused interventions aimed at reducing harm from online misinformation have been developed in the behavioral and cognitive sciences. We, an international group of 26 expe...

This Comment piece summarises current challenges regarding routine vaccine uptake in the context of the COVID-19 pandemic and provides recommendations on how to increase uptake. To implement these recommendations, the article points to evidence-based resources that can support health-care workers, policy makers and communicators.

When judging the average value of sample stimuli (e.g., numbers) people tend to either over- or underweight extreme sample values, depending on task context. In a context of overweighting, recent work has shown that extreme sample values were overly represented also in neural signals, in terms of an anti-compressed geometry of number samples in mul...

We determined the scope of five decision models of choices across four environmental niches defined by whether outcome probabilities are described (risk) or experienced by sampling (uncertainty) and whether lotteries are simple (one or two outcomes per prospect) or complex (three or four). The majority of participants chose in accordance with cumul...

Persistent inequalities and injustices are a blight on modern liberal societies. Examples abound, from the gender gap in pay to sentencing disparities between Black, Hispanic, and White defendants to allocation disparities in medical resources between Black and White patients. One cause of these and other inequalities is implicit social biases. In...

Low-quality and misleading information online can hijack people’s attention, often by evoking curiosity, outrage, or anger. Resisting certain types of information and actors online requires people to adopt new mental habits that help them avoid being tempted by attention-grabbing and potentially harmful content. We argue that digital information li...

One of today’s most controversial and consequential issues is whether the global uptake of digital media is causally related to a decline in democracy. We conducted a systematic review of causal and correlational evidence (N = 496 articles) on the link between digital media use and different political variables. Some associations, such as increasin...

Background Long-term prescriptions of strong opioids for chronic noncancer pain—which are not supported by scientific evidence—suggest miscalibrated risk perceptions among those who prescribe, dispense, and take opioids. Because risk perceptions and behaviors can differ depending on whether people learn about risks through description or experience...

The use of information technologies for the public interest, such as COVID-19 tracking apps that aim to reduce the spread of COVID-19 during the pandemic, involve a dilemma between public interest benefits and privacy concerns. Critical in resolving this conflict of interest are citizens’ trust in the government and the risks posed by COVID-19. How...

Ecological rationality represents an alternative to classic frameworks of rationality. Extending on Herbert Simon’s concept of bounded rationality, it holds that cognitive processes, including simple heuristics, are not per se rational or irrational, but that their success rests on their degree of fit to relevant environmental structures. The key i...

When moderating content online, two key values may come into conflict: protecting freedom of expression and preventing harm. Robust rules based in part on how citizens think about these moral dilemmas are necessary to deal with the unprecedented scale and urgency of this conflict in a principled way. Yet little is known about people's judgments and...

During the Covid-19 pandemic, people have been exposed to vast amounts of misinformation. This “infodemic” has undermined key behavioural and pharmacological measures to contain the pandemic. In a cross-sectional survey of residents of Germany, we investigated the perceived prevalence of misinformation, the strategies people reported using to disce...

People routinely rely on experts’ advice to guide their decisions. However, experts are known to make inconsistent judgments when judging the same case twice. Previous research on expert inconsistency has largely focused on individual or situational factors; here we focus directly on the cases themselves. First, using a theoretical model, we study...

Background: The pressure on physicians when a patient seeks pain relief and their own desire to be self-effective may lead to the prescription of strong opioids for chronic noncancer pain (CNCP). This study, via physician self-reporting, aims to identify and measure (i) physician adherence to national opioid prescribing guidelines and (ii) physici...

When judging the average value of sample stimuli (e.g., numbers) people tend to either over- or underweight extreme sample values, depending on task context. In a context of overweighting, recent work has shown that extreme sample values were overly represented also in neural signals, in terms of an anti-compressed geometry of number samples in mul...

When acquiring information about choice alternatives, decision makers may have varying levels of control over which and how much information they sample before making a choice. How does control over information acquisition affect the quality of sample-based decisions? Here, combining variants of a numerical sampling task with neural recordings, we...

During pandemics, effective nonpharmaceutical interventions encourage people to adjust their behavior in fast-changing environments in which exponential dynamics aggravate the conflict between the individual benefits of risk-taking and its social costs. Policy-makers need to know which interventions are most likely to promote socially advantageous...

Children eat most of their meals in a family context, making family meals a key environment in which to learn about healthy food. What makes a family meal “healthy”? This diary study examined the practice of seven family mealtime routines (e.g., positive mealtime atmosphere, parental modeling, and longer meal duration) and their predictive value fo...

Controlling the spread of an infectious disease depends critically on the general public’s adoption of preventive measures. Theories of health behavior suggest that risk perceptions motivate preventive behavior. The supporting evidence for this causal link is, however, of questionable validity. The COVID-19 pandemic provides a rare opportunity to e...

The first reference on rationality that integrates accounts from psychology and philosophy, covering descriptive and normative theories from both disciplines. Both analytic philosophy and cognitive psychology have made dramatic advances in understanding rationality, but there has been little interaction between the disciplines. This volume offers t...

The modern world holds countless risks for humanity, both large-scale and intimately personal—from cyberwarfare, pandemics, and climate change to sexually transmitted diseases and drug use and abuse. Many risks have prompted institutional, regulatory, and technological countermeasures, the success of which depends to some extent on how individuals...

Verhaltenswissenschaftliche Erkenntnisse zur Frage nach der "Rationalität" des menschlichen Entscheidens

One of today's most controversial and consequential questions is whether the rapid, worldwide uptake of digital media is causally related to a decline in democracy. We conducted a systematic review of causal and correlational evidence (N=498 articles) on the link between digital media and different political variables, such as trust, polarization o...

The German Socio-Economic Panel (SOEP) serves a global research community by providing representative annual longitudinal data of private households in Germany. The sample provides a detailed life course perspective based on a rich collection of information about living conditions, socio-economic status, family relationships, personality, values, p...

Objectives The impact of the quality of discharge communication between physicians and their patients is critical on patients’ health outcomes. Nevertheless, low recall of information given to patients at discharge from emergency departments (EDs) is a well-documented problem. Therefore, we investigated the outcomes and related benefits of two diff...

Objectives Opioid prescription rates worldwide suggest miscalibrated risk perceptions among those who prescribe, dispense, and take opioids. Findings from cognitive science show that risk perceptions can differ systematically depending on whether people learn about risks by description or experience. We investigated the effects of descriptive and s...

Die Frage nach der Natur menschlicher Rationalität und dem Maß, in dem wir ihr gerecht werden, ist bereits seit Jahrtausenden umstritten. Diverse Denkschulen haben ganz unterschiedliche Antworten darauf gefunden. In diesem kurzen Beitrag beleuchten wir drei unterschiedliche Denkschulen und ihre typischen Ergebnisse. Link: https://mint-zirkel.de/202...

Background Strong opioids can have unintended effects. Clinical studies of strong opioids mainly report physical side effects, psychiatric or opioid use disorders. To date, too little attention has been paid to the psychological effects of opioids to treat patients with chronic noncancer pain (CNCP). This study aims to identify and measure (i) the...

The COVID-19 pandemic has seen one of the first large-scale uses of digital contact tracing to track a chain of infection and contain the spread of a virus. The new technology has posed challenges both for governments aiming at high and effective uptake and for citizens weighing its benefits (e.g., protecting others’ health) against the potential r...

Loss aversion has long been regarded as a fundamental psychological regularity, yet evidence has accumulated to challenge this conclusion. We review three theories of how people make decisions under risk and, as a consequence, value potential losses: expected-utility theory, prospect theory, and risk-sensitivity theory. These theories, which stem f...

Online platforms’ data give advertisers the ability to “microtarget” recipients’ personal vulnerabilities by tailoring different messages for the same thing, such as a product or political candidate. One possible response is to raise awareness for and resilience against such manipulative strategies through psychological inoculation. Two online expe...

Understanding how people of different ages decide in competition is a question of theoretical and practical importance. Using an experimental laboratory approach, this research investigates the ability of younger and older adults to think and act strategically with equal or unequal resources. In zero-sum games of resource allocation, younger adults...

During the COVID-19 pandemic, citizens have been exposed to vast amounts of mis- and disinformation. This “infodemic” has undermined key behavioural and pharmacological measures to contain the pandemic—for instance, by increasing vaccine hesitancy. In a cross-sectional survey of residents of Germany, we investigated citizens’ perceptions of and abi...

Rationale Tracking the trajectory of people's emotional and behavioral reactions to the COVID-19 pandemic sheds light on how people cope with the emerging crisis, evaluates the impact of emotional reactions on preventive behaviors, and provides insights into how preventive behaviors can be encouraged and maintained in the long term. Objective We a...