In-group bias in natural groups of soldiers

This study examines both whether soldiers are identified as soldiers rather than civilians and whether soldiers' ingroup bias is a function of military rank (vertical level), military unit (horizontal level), and the interaction of both levels. Our unique data-set consists of German soldiers categorized by military unit (air force, navy, and army) and status (officer candidates and officers). Our results, based on a series of modified dictator games and a comprehensive questionnaire, reveal intriguing patterns. We find a strong in-group bias among soldiers, indicating a robust identification as members of the military in contrast to civilians. In addition, the identification between different military units is consistently high across units. Moreover, we observe an interaction between identification across units and status. Low-status groups of officer candidates show a significantly higher in-group bias at the horizontal level.