Johanna Gereke

research fellow at MZES

Mannheim Centre for European Social Research

About me

I am a postdoctoral research fellow at the Mannheim Centre for European Social Research (MZES). My current research focuses on intergroup relations, migration, discrimination and cooperative behavior in modern societies. Other research projects examine biased beliefs and superstitions in migration decision-making, the link between physical attractiveness and immigrants’ integration outcomes and the relationship between unemployment, poverty and prosociality, political engagement and trust.

My research draws on a range of experimental and quasi-experimental methods, including original lab-in-the-field, survey and field experiments. Prior to joining the MZES, I held a postdoctoral position at the Carlo F. Dondena Centre for Research on Social Dynamics and Public Policy at Bocconi University in Milan, Italy. I hold a Ph.D. in Social and Political Sciences from the European University Institute in Florence, Italy.


  • intergroup relations
  • migration
  • discrimination
  • trust and cooperation
  • poverty and inequality


  • Postdoctoral researcher at the Carlo F. Dondena Centre for Research on Social Dynamics and Public Policy, 2018

    Bocconi University in Milan, Italy

  • Ph.D. in Social and Political Sciences, 2016

    European University Institute in Florence, Italy


Strangers in Hostile Lands: Exposure to Refugees and Right-wing Support

Does local exposure to refugees affect right-wing support and anti-immigrant sentiments? This paper studies the allocation of refugees to the rural hinterlands of Eastern Germany during the refugee crisis of 2015. Similar to non-urban regions elsewhere, the area has seen a major shift towards the political right, despite minimal previous exposure to foreigners. We draw on electoral records and original data collected among 1,320 German citizens from 236 municipalities, half of which received refugees. Two conditions allow for causal identification: a policy allocating refugees following strict administrative rules, and a matching procedure rendering treated and control municipalities statistically indistinguishable. Our survey and behavioral measures confirm the presence of widespread anti-immigrant sentiments, but these are entirely unaffected by the presence of refugees in respondents’ hometowns. If anything, local exposure to refugees served as a ‘reality check’, pulling both right- and left-leaning individuals more towards the center.

Discrimination is unaffected by immigrants’ socioeconomic status.

Experimental economics has moved beyond the traditional focus on market mechanisms and the ‘invisible hand’ by applying sociological and socio-psychological knowledge in the study of rationality, markets, and efficiency. This knowledge includes social preferences, social norms and cross-cultural variation in motivations. In turn, the renewed interest in causation, social mechanisms and middle-range theories in sociology has led to a renaissance of research employing experimental methods. This includes laboratory experiments, but also a wide range of field experiments with diverse samples and settings. By focusing on a set of research topics that have proven to be of substantive interest to both disciplines - cooperation in social dilemmas, trust and trustworthiness, and social norms - this review aims to highlight innovative interdisciplinary research that connects experimental economics with experimental sociology. We conclude that experimental economics and experimental sociology can still learn much from each other, thus providing economists and sociologists with an opportunity to collaborate and advance our knowledge on a range of underexplored topics of interest to both disciplines.

Migration, Magic, and the Risk of Dying: Evidence from real-time migration decisions in The Gambia (data collection ongoing)

Beliefs in magic and superstitions have been observed to influence a range of outcomes, including warfare, business and electoral choice. In the context of migration, previous studies have documented the ubiquity of superstitious beliefs in influencing when, where and how aspiring migrants decide to undertake their journeys abroad. Building on these findings, this study empirically investigates whether magical and superstitious beliefs influence the decision to migrate using an original longitudinal data set. We do so in the context of The Gambia, which has seen some of the highest migration rates in the world in recent years. We hypothesize that magical beliefs make individuals likely to underestimate the risk of the migratory journey, and make them more trusting of smugglers, who often betray this trust. In order to test these hypotheses, we ask 10,000 potential migrants who will be re-interviewed several times during a 6-months period. This allows us to observe actual migration decisions, and to link these to beliefs in magic, risk attitudes and trust perceptions.

Book chapter on ‘Public Goods and Collective Action’ for ‘Rational Choice’ Theory Handbook


Schaub, M., Gereke, J., & Baldassarri, D. (n.d.). Does Poverty Undermine Cooperation in Multiethnic Settings? Evidence from a Cooperative Investment Experiment.

What undermines cooperation in ethnically diverse communities? Scholars have focused on factors that explain the lack of inter-ethnic cooperation, such as prejudice or the difficulty to communicate and sanction across group boundaries. We direct attention to the fact that diverse communities are also often poor and ask whether poverty, rather than diversity, reduces cooperation. We developed a strategic cooperation game where we vary the income and racial identity of the interaction partner. We find that beliefs about how poor people behave have clear detrimental effects on cooperation: cooperation is lower when people are paired with low-income partners, and the effect is particularly strong when low-income people interact among themselves. We observe additional discrimination along racial lines when the interaction partner is poor. These findings imply that poverty and rising inequality may be a serious threat to social cohesion, especially under conditions of high socioeconomic segregation.

Gereke J, Schaub M, Baldassarri D (2018) Ethnic diversity, poverty and social trust in Germany: Evidence from a behavioral measure of trust.

Several scholars have concluded that ethnic diversity has negative consequences for social trust. However, recent research has called into question whether ethnic diversity per se has detrimental effects, or whether lower levels of trust in diverse communities simply reflect a higher concentration of less trusting groups, such as poor people, minorities, or immigrants. Drawing upon a nationally representative sample of the German population (GSOEP), we make two contributions to this debate. First, we examine how ethnic diversity at the neighborhood level–specifically the proportion of immigrants in the neighborhood–is linked to social trust focusing on the compositional effect of poverty. Second, in contrast to the majority of current research on ethnic diversity, we use a behavioral measure of trust in combination with fine-grained (zip-code level) contextual measures of ethnic composition and poverty. Furthermore, we are also able to compare the behavioral measure to a standard attitudinal trust question. We find that household poverty partially accounts for lower levels of trust, and that after controlling for income, German and non-German respondents are equally trusting. However, being surrounded by neighbors with immigrant background is also associated with lower levels of social trust.



Experimental Methods for the Social Sciences (Workshop)

GIGA Hamburg

Oct 2019 – Oct 2019 Hamburg, Germany

Experimental Methods; Datenerhebung/Data collection

Mannheim Centre for European Social Research

Feb 2019 – Present Mannheim, Germany

Instructor Global Study Program

University of Cologne

Mar 2018 – Jul 2018 Cologne, Germany


Heinrich-Heine University

Jun 2016 – Jul 2016 Düsseldorf, Germany

Teaching Assistant

European University Institute

Jan 2015 – Mar 2016 Milan, Italy