Ingroup favoritism is not time-stable

Humans are a group-living species. Our evolutionary past could thus have shaped the ways in which we think and behave in group contexts. One such candidate feature of human social cognition and behavior is ingroup favoritism. Indeed, recent work revealed that at least some people are ingroup favoring and ‘strongly groupy’. Such individuals readily discriminate negatively against outgroup members across all group contexts they are put into, even if these contexts are minimal and even if discriminating does not entail any benefits. However, so far, it has not been tested whether ingroup favoring behavior in general or ’groupy’ social preferences in particular are stable within persons over longer periods of time. Here, we present the results of a longitudinal lab-in-the-field study of ingroup favoritism and ’groupiness’ over one year. We find that neither ingroup favoritism nor ‘groupiness’ are particularly time-stable. Thus, our findings are hard to reconcile with notions of ingroup favoritism or ‘groupiness’ as individual traits. Instead, our observations underscore that group-based discrimination is malleable—for better or for worse. Our results reemphasize the need to understand which situational factors trigger ‘groupy’ behavior and how these interact with individual characteristics.