Michael A. Hogg
Social identity theory is a social psychological analysis of the role of self-conception in group membership, group processes, and intergroup relations. It embraces a number of interrelated concepts and subtheories that focus on social-cognitive, motivational, socialinteractive and macrosocial facets of group life. The approach is explicitly framed by a conviction that collective phenomena cannot be adequately explained in terms of isolated individual processes or interpersonal interaction alone and that social psychology should place large-scale social phenomena near the top of its scientific agenda.
Social identity theory defines group cognitively—in terms of people's self-conception as group members. A group exists psychologically if three or more people construe and evaluate themselves in terms of shared attributes that distinguish them collectively from other people. Social identity theory addresses phenomena such as prejudice, discrimination, ethnocentrism, stereotyping, intergroup conflict, conformity, normative behavior, group polarization, crowd behavior, organizational behavior, leadership, deviance, and group cohesiveness.
Social identity theory was first developed at the start of the 1970s in Britain by Henri Tajfel, out of his scientific and personal interests in social perception, social categorization, and social comparison and prejudice, discrimination, and intergroup conflict. Over the past 30 years social identity theory has attracted many collaborators and followers. It has developed and matured conceptually and has motivated, and continues to motivate, a prodigious quantity of research. Although initially a European analysis of intergroup relations, since the early 1990s it has become accepted around the world as one of mainstream social psychology's most significant general theories of the relationship between self and group. However, this popularity has sometimes brought with it a disjunction between some readings of social identity concepts and the concepts themselves.
This chapter describes the concepts that form the social identity approach. I use the term approach because social identity theory is sometimes too narrowly equated with only one aspect—the analysis of intergroup relations and social change as a function of positive distinctiveness (e.g., Tajfel and Turner 1979). In reality the intergroup-relations analysis
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