Answer to Question 1
Answer: According to Henri Tajfel (1982a), group membership, even in minimal groups, often serves to help us enhance our self-esteem when we identify with other group members. An in-group bias often develops, even in minimal groups. We develop positive feelings for in-group members and are motivated to treat them well; we develop negative feelings toward out-group members, simply because they are not members of our group. Further, a cognitive bias known as out-group homogeneity often develops as function of group membership; we tend to view members of out -groups as more similar to one another than they really are, contributing to stereotypes. Thus, the in-group bias (positive evaluations of members of our own group, and negative evaluations of members of the other group) in combination with cognitive biases (perceptions of out-group homogeneity) set the stage for prejudice and discrimination.
Answer to Question 2
Answer: Normative conformity is the desire to be accepted and to fit in with the group. Because stereotypes exist in culture, often people will not challenge them because they do not want to stand out and go against the common beliefs of a culture.