Published papers

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

Anti-Social Behavior in Groups. NEW!
Working Paper of the Max Planck Institute for Tax Law and Public Finance No. 2018-14, 2018.
with Michal Bauer, Dagmara Celik Katreniak, Julie Chytilová, Lubomír Cingl, and Tomáš Želinský
This paper provides strong evidence supporting the long-standing speculation that decision-making in groups has a dark side, by magnifying the prevalence of anti-social behavior towards outsiders. A large-scale experiment implemented in Slovakia and Uganda (N=2,309) reveals that deciding in a group with randomly assigned peers increases the prevalence of anti-social behavior that reduces everyone’s payoff but which improves the relative position of own group. The effects are driven by the influence of a group context on individual behavior, rather than by group deliberation. The observed patterns are strikingly similar on both continents.

How Stress Affects Performance and Competitiveness across Gender
Minor revision requested at Management Science
with Lubomir Cingl and Ian Levely
We study how psycho-social stress affects willingness to compete and performance under tournament incentives across gender. The work has implications for gender gaps on the labor market, since many key career events involve competition in stressful settings (e.g. entrance exams or job interviews). We use a laboratory economic experiment in which a task is compensated under both tournament and piece-rate schemes and elicit subjects’ willingness to compete. Stress is exogenously introduced through a modified version of the Trier Social Stress Test, and stress response is measured by salivary cortisol levels. We find that stress reduces willingness to compete. For female subjects, this can be explained by performance: while tournament incentives increase output in the control group, women in the stress treatment actually perform worse when competition is introduced. For males, output is not affected by the stress treatment and lower competitiveness seems to be preference-based. These results may explain previous findings that men and women react differently to tournament incentives.

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

Improving the efficiency of TV-fee collection (with L. Cingl, K. Chadimová, M. Zajíček).