Identity, language, and conflict: An experiment on ethno-linguistic diversity and group discrimination in two bilingual societies

Ethno-linguistic diversity has been empirically linked to low provision of public goods. We contribute to this literature analyzing diversity in a lab-in-the-field experiment in which we carefully control for ethno-linguistic diversity in two different bilingual societies, one with a much stronger identity conflict (the Basque Country) than the other (Valencia Country). In both locations, our participants come from different ethno- linguistic cultures (Catalan or Spanish, Basque or Spanish), and interact with other participants from their same background or a different one. We recruit participants using their mother tongue language, and study the effect of homogeneous (with no diversity) or mixed (with ethno-linguistic diversity) natural cultural identities in a nested public goods game with a local and a global public good. The game is constructed to eliminate any tension between efficiency and diversity; so, not contributing to the global (and efficient) public good can be interpreted as willingness to exclude the other group from the benefits of your contribution. Our results strongly support that diversity is strongly context dependent. While diversity in the Basque Country significantly reduces contributions to the global public good, and efficiency, it has no effect in the Valencia Country (if any, the effect is positive, but insignificant). We show that diversity destroys (reinforces) conditional cooperation in the Basque (Valencia) Country. While diversity is associated with overoptimistic empirical beliefs in Valencia, it significantly increases normative group discrimination in Basque Country.