For publications written at CPB, please see my LinkedIn profile.

Social Identity and Group Contests   (with Arno Riedl)

Social identity has been shown to successfully enhance cooperation and effort in cooperation and coordination games. Little is known about the causal effect of social identity on the propensity to engage in group contests. In this paper we explore theoretically and experimentally whether social identity increases investments in group contests. We show theoretically that increased social identity with the own group implies higher investments in Tullock contests. Empirically we find that induced social identity does increase group closeness but does not increase conflict investments. 

Social Identity in the Lab: A Horse Race between Different Methods to Induce Social Identity  (with Tony Williams and Arno Riedl)

Social identity affects the economic behavior of individuals and groups. However, studying the effect of social identity remains difficult. It is often not possible to directly observe and manipulate social identity in natural settings which makes causal inference challenging.  An alternative approach is to create new social identities experimentally in the lab. In this paper we compare several methods to induce social identity in the lab and ways to measure the strength of the induced social identity with social preferences tests. We find that choice of method does not matter for the success of inducing a social identity but that the choice of measure does. While we find that  the social identity inductions have little to no effect on between-subject social preference measures, they have a significant effect on social preferences measured within-subject. We find that salience effects can greatly affect the within-subject measures and suggest that social identity findings produced by within-subject designs could be an artifact of the measure used instead of an effect of the induced identity.

Conflict and Migration: Mobility in Group Contests (with Arno Riedl and Florian Heine).

Group contests have been used to study conflict between countries, R\&D competitions, sports competition and lobbying. Usually, it is assumed that individuals belong to one group and that this group membership will remain unchanged. However, in practice, soldiers can defect, employees switch employers and athletes switch teams. We introduce intergroup mobility to a group contest and test how this affects contest contributions in a lab experiment. We find that endogenous (voluntary) migration increases contest contributions, whereas exogenous migration (displacement) has a negative but insignificant effect relative to a baseline without intergroup mobility. Ingroup bias as measured by modified dictator games persists throughout the experiment in the control treatment and does not decrease in the migration treatments. In the endogenous migration treatment, the decision to leave the own group is mainly driven by bad prospects of winning.

Decreasing Incomes Increase Selfishness (with Nickolas Gagnon and Riccardo Domenico Saulle ).

We use a controlled laboratory experiment to study the causal impact of income decreases within a time period on redistribution decisions at the end of that period, in an environment where we keep fixed the sum of incomes over the period. First, we investigate the effect of a negative income trend (intra-personal decrease), which means a decreasing income compared to one's recent past. Second, we investigate the effect of a negative income trend relative to the income trend of another person (inter-personal decrease). If intra-personal or inter-personal decreases create dissatisfaction for an individual, that person may become more selfish to obtain compensation. We formalize both effects in a multi-period model augmenting a standard model of inequality aversion. Overall, conditional on exhibiting  sufficiently-strong social preferences, we find that individuals indeed behave more selfishly when they experience decreasing incomes. While many studies examine the effect of income inequality on redistribution decisions, we delve into the history behind one's income to isolate the effect of income changes.