Chapter one: introduction to the study of stereotyping and prejudice. Some researchers theorize that the tendency to form groups is such a basic part of the nature of animals, including humans, and has conveyed survival benefits so successfully that it had withstood time and evolution. In addition to the tremendous benefits to individuals in groups, however, there are some disadvantages and complications that group life brings, such as mate competition and mate retention. Group members tend to favour their own groups (ingroups) over other groups to which they do not belong (outgroups). Even when group membership is based on the most arbitrary criteria (e. g. , randomly assigning people to group a or to group. B, an example of a minimal group), people tend to show preferences for members of their own group over those of other groups. In other words, stereotypes tell us what social information is important to perceive and to disregard in our environment.