Published and forthcoming papers

Covid-19 and Hostility against Foreigners
European Economic Review, 2021, 137, 103818.
with Vojtěch Bartoš, Michal Bauer, and Julie Chytilová
Harmful behavior against out-group members often rises during periods of economic hardship and health pandemics. Here, we test the widespread concern that the Covid-19 crisis may fuel hostility against people from other nations. Using a controlled money-burning task, we elicited hostile behavior among a nationally representative sample (n=2,186) in the Czech Republic during the first wave of the pandemic. We provide evidence that exogenously elevating salience of the Covid-19 crisis increases hostility against foreigners from the EU, USA and Asia. This behavioral response is similar across various demographic sub-groups. Further, we do not find support for the optimistic view that the Covid-19 crisis may create stronger social bonds within a country. The results underscore the importance of not inflaming anti-foreigner sentiments and suggest the need to monitor impacts of the crisis on behavior in the social domain.

How Stress Affects Performance and Competitiveness across Gender
Management Science, 2020, 66(8): 3295-3310.
with Lubomir Cingl and Ian Levely
Since many key career events, such as exams and interviews, involve competition and stress, gender differences in response to these factors could help to explain the labor market gender gap. In a laboratory experiment, we manipulate psychosocial stress using the Trier Social Stress Test, and confi rm that this is e ffective by measuring salivary cortisol and heart rate. Subjects perform in a real-e ffort task under both tournament and piece-rate incentives and we elicit willingness to compete. We find that women under heightened stress perform worse than women in the control group when compensated with tournament incentives, while there is no treatment difference under piece-rate incentives. For men, stress does not a ffect output under competition, nor under piece-rate. The gender gap in willingness to compete is not a ffected by stress, but stress decreases competitiveness overall, which for women is related to performance. Our results could explain gender diff erences in performance under competition, with implications for hiring practices and incentive structures in firms.

Social Contagion of Ethnic Hostility.
with Michal Bauer, Julie Chytilová, and Tomáš Želinský
Interethnic conflicts often escalate rapidly. Why does the behavior of masses easily change from cooperation to aggression? This paper provides an experimental test of whether ethnic hostility is contagious. Using incentivized tasks, we measured willingness to sacrifice one’s own resources to harm others among adolescents from a region with a history of animosities toward the Roma people, the largest ethnic minority in Europe. To identify the influence of peers, subjects made choices after observing either destructive or peaceful behavior of peers in the same task. We found that susceptibility to follow destructive behavior more than doubled when harm was targeted against Roma rather than against coethnics. When peers were peaceful, subjects did not discriminate. We observed very similar patterns in a norms-elicitation experiment: destructive behavior toward Roma was not generally rated as more socially appropriate than when directed at coethnics, but the ratings were more sensitive to social contexts. The findings may illuminate why ethnic hostilities can spread quickly, even in societies with few visible signs of interethnic hatred.

Risk Preferences under Acute Stress
Experimental Economics 2017,  20(1): 209-236.

with Lubomír Cingl
Many important decisions are made under stress and they often involve risky alternatives. There has been ample evidence that stress influences decision making in cognitive as well as in affective domains, but still very little is known about whether individual attitudes to risk change with exposure to acute stress. To directly evaluate the causal effect of stress on risk attitudes, we adopt an experimental approach in which we randomly expose participants to a psychosocial stressor in the form of a standard laboratory stress-induction procedure: the Trier Social Stress Test for Groups. Risk preferences are elicited using an incentive compatible task, which has been previously shown to predict risk-oriented behavior out of the laboratory. Using three different measures (salivary cortisol levels, heart rate and multidimensional mood questionnaire scores), we show that stress was successfully induced on the treatment group. Our main result is that acute psychosocial stress significantly increases risk aversion. The effect is mainly driven by males; men in our control group are less risk-averse than women, which is a standard result in the literature, but this difference almost disappears when under psychosocial stress.

Working papers

Shifting Punishment on Minorities: Experimental Evidence of Scapegoating  (new version available!)
Revise and Resubmit – Economic Journal; with Michal Bauer, Julie Chytilová, Gérard Roland, and Tomáš Želinský
This paper provides experimental evidence showing that members of a majority group systematically shift punishment on innocent members of an ethnic minority. We develop a new incentivized task, the Punishing the Scapegoat Game, to measure how injustice affecting a member of one’s own group shapes punishment of an unrelated party (“a scapegoat”). We study interactions between the majority group and the Roma minority in Slovakia. By experimentally manipulating the ethnic identity of the scapegoats, we show that the punishment “passed” on innocent individuals more than doubles when they are from the minority, as compared to when they are from the dominant group. These results illuminate a mechanism how individualized tensions can be transformed into a group conflict, dragging minorities into conflicts that are completely unrelated to their behavior.

Media coverage:

Nastiness in Groups (new version available!)
with Michal Bauer, Dagmara Celik Katreniak, Julie Chytilová, Lubomír Cingl, and Tomáš Želinský
This paper provides evidence showing that people are more prone to engage in nasty behavior, malevolently causing financial harm to other people at own costs, when they make decisions on behalf of a group rather than when making choices individually on their own. We establish this behavioral regularity in four large-scale experiments among adolescents, university students and a nationally representative sample of adults (N = 7,426). We test several potential mechanisms, and the results suggest that the “destructiveness shift” in groups is driven by lower perception of individual responsibility, in line with self-signaling models.

Carrots, Sticks, or Simplicity: Field Evidence on What Makes People Pay TV Fees (NEW!)
with Kateřina Chadimová, Lubomír Cingl, and Miroslav Zajíček
We provide evidence on both innovative as well as known behavioral strategies aimed at improving tax compliance, using a unified environment of two large correspondence experiments (N=82,599 and N=51,142) with potential TV-fees evaders in the Czech Republic. We (i) simplify the original letter and add a QR code for easier registration; use two innovative text strategies aimed at (ii) the elicitation of preference for fee designation, and (iii) the explanation of fee purpose. We also employ strategies known in the literature but providing mixed results: highlighting (iv) legal consequences of non-compliance, (v) value of services for the fee, and (vi) social norms. Apart from the text treatments, we modify the envelopes by placing there (vii) a picture of a cartoon character (supported by a sticker inside), or (viii) a red inscription “Important”, with the aim to stimulate recipients’ reciprocity and attention. Our results show that the text simplification and highlighting legal consequences substantially improve effectiveness of the letter, which we self-replicate on a new sample two years later, while the remaining treatments do not improve over the baseline. The QR code brings only a modest improvement.

Foretelling What Makes People Pay: Predicting the Results of Field Experiments on TV Fee Enforcement
with Kateřina Chadimová and Lubomír Cingl
One of the current challenges in field experimentation is creating an efficient design including individual treatments. Ideally, a pilot should be run in advance, but when a pilot is not feasible, any information about the effectiveness of potential treatments’ to researchers is highly valuable. We run a laboratory experiment in which we forecast results of two large-scale field experiments focused on TV license fee collection to evaluate the extent to which it is possible to predict field experiment results using a non-expert subject pool. Our main result is that forecasters were relatively conservative regarding the absolute effectiveness of the treatments, but in most cases they correctly predicted the relative effectiveness. Our results suggest that, despite the artificiality of laboratory environments, forecasts generated there may provide valuable estimates of the effectiveness of treatments.

Study Abroad Experience and Attitudes Towards Other Nationalities
CERGE-EI Working Paper Series, No. 556, 2015.

Every year, millions of people move to a foreign country for school or work. This research provides evidence of how such international experience shifts preferences and stereotypes towards other nationalities. I use the largest study abroad program in the world—the Erasmus program—as a source of variation in international experience. Students about to participate in the Erasmus program are taken as a control group for students who have just returned. Individuals make decisions in a Trust Game and in a Triple Dictator Game to decompose changes to statistical discrimination from changes to taste-based discrimination. Results show that while students prior to an Erasmus stay do not differentiate between partners from Northern and Southern Europe in the Trust Game, students with Erasmus experience start to exhibit lower trust towards partners from the South. Behavior towards other nationalities in the Triple Dictator Game is not affected by Erasmus. Overall, the results suggest that participants learn about cross-country variation in cooperative behavior while abroad and therefore statistical discrimination becomes more relevant with increased international experience.

Work in progress

Spreading consensus: Correcting misperceptions about the views of the medical community has lasting impacts on Covid-19 vaccine take-up (with Vojtěch Bartoš, Michal Bauer, and Julie Chytilová)

Life during the Pandemic (with Vojtěch Bartoš, Michal Bauer, and Julie Chytilová) – some aggregate data are published at (in Czech). Cite data as: Daniel Prokop, Vojtěch Bartoš, Michal Bauer, Jana Cahlíková, Julie Chytilová, Michaela Kudrnáčová, Lucie Marková, Eliška Dvořáková, Tomáš Hovorka (2021): Life during the pandemic: Longitudinal data set from the Czech Republic. URL:

Scam identification ability, confidence, and the use of digital financial services (with Lisa Spantig, Lucy Kaaria, Elif Kubilay, and Eva Raiber) – grant awarded from the Innovations for Poverty Action (IPA) under the Consumer Protection Research Initiative.

Other writings

The impacts of the COVID-19 pandemic on mental health (A study for the Institute for Democracy and Economic Analysis IDEA; in Czech, with Vojtěch Bartoš, Michal Bauer, and Julie Chytilová; in Czech with an English summary; 2020)