When Novel Rituals Lead to Intergroup Bias: Evidence From Economic Games and Neurophysiology

Long-established rituals in preexisting cultural groups have been linked to the cultural evolution of group cooperation. We tested the prediction that novel ritualsarbitrary hand and body gestures enacted in a stereotypical and repeated fashioncan inculcate intergroup bias in newly formed groups. In four experiments, participants practiced novel rituals at home for 1 week (Experiments 1, 2, and 4) or once in the lab (Experiment 3) and were divided into minimal in-groups and out-groups. Our results offer mixed support for the hypothesis that novel rituals promote intergroup bias. Specifically, we found a modest effect for daily repeated rituals but a null effect for rituals enacted only once. These results suggest that novel rituals can inculcate bias, but only when certain features are present: Rituals must be sufficiently elaborate and repeated to lead to bias. Taken together, our results offer modest support that novel rituals can promote intergroup bias.