Minimal Group Paradigm
Minimal group paradigm is a social psychology research methodology that proposes that the minimal condition for group biases (like favoritism towards your own group and prejudice towards other groups) is simply being a member of a group.
This research area was first introduced by Henri Tajfel and previously it was believed that group biases occurred because of personal factors. Tajfel proposed that the minimal requirement for group biases and discrimination to occur was simply to be part of a group even if it was for a trivial and random reason. Minimal groups research has shown that irrelevant and arbitrary distribution into groups can cause individuals to favor their group over others and show prejudice towards members of other groups.
For example, in an experiment participants are divided into groups A and B for an arbitrary reason such as shirt type or color preference. After being distributed into arbitrary groups individuals will begin to show favoritism to members of their group and prejudice towards members of other groups. This shows that there doesn't need to be idealogical justification, benefits, or personal factors in group biases- simply being a member of a group was enough for biases to occur.