that benefit in-group members. Self-identity and social identity As noted in two recent theoretical reviews, the theoretical basis for the inclusion of self-identity in the theories of reasoned action and planned behavior has many similarities to social identity theory and its extension, self-categorization theory. According to social identity theory, an important component of the self-concept is derived from memberships in social groups and categories. When people define and evaluate themselves in terms of a self-inclusive social category (e.g., sex, class, team) two processes come into play: (1) categorization, which perceptually accentuates differences between the in-group and out-group, and similarities among in-group members (including the self) on stereotypical dimensions; and (2) self-enhancement which, because the self-concept is defined in terms of group membership, seeks behaviorally and perceptually to favor the in-group over the out-group. Social identities are cognitively represented as group prototypes that describe and prescribe beliefs, attitudes, feelings and behaviors that optimize a balance between minimization of in-group differences and maximization of intergroup differences. More specifically, according to social identity theory, there is a continuum between personal and social identity shifts along this continuum that determine the extent to which group-related or personal characteristics influence a person's feelings and actions. If a particular social identity is a salient basis for self-conception, then the self is assimilated to the perceived in-group prototype which can be thought of as a set of perceived in-group norms such that self-perception, beliefs, attitudes, feelings and behaviors are defined in terms of the group prototype. Thus, social identities should influence behavior through the mediating role of group norms. People will be more likely to engage in a particular behavior if it is in accord with the norms of a behaviorally relevant group membership, particularly if the identity is a salient basis for self-definition. If the group membership is not salient, then people's behavior and feelings should be in accord with their own personal and idiosyncratic characteristics rather than group norms. On the other hand, the self-identity theory poses that the self is often a reflection of expected norms and practices in a person's social role. At the center of it is the proposition that the self is made up of multi-faceted and differentiated components that exist in an organized manner for the sake of filling in roles in society. People are able to create an identity for themselves only through talking to others, and often what