Mfost of social psychology's theories of the self fail to take into account the significance of social identification in the definition of self. Social identities are self-definitions that are more inclusive than the individuated self-concept of most American psychology. A model of optimal distinctiveness is proposed in which social identity is viewed as a reconciliation of opposing needs for assimilation and differentiation from others. According to this model, individuals avoid self-construals that are either too personalized or too inclusive and instead define themselves in terms of distinctive category memberships. Social identity and group loyalty are hypothesized to be strongest for those self-categorizations that simultaneously provide for a sense of belonging and a sense of distinctiveness. Results from an initial laboratory experiment support the prediction that depersonalization and group size interact as determinants of the strength of social identification.

Cross-cultural perspectives have brought renewed interest in the social aspects of the self and the extent to which individuals define themselves in terms of their relationships to others and to social groups. This article provides a conceptual review of research and theory of the social self, arguing that the personal, relational, and collective levels of self-definition represent distinct forms of selfrepresentation with different origins, sources of self-worth, and social motivations. A set of 3 experiments illustrates haw priming of the interpersonal or collective "we" can alter spontaneous judgments of similarity and self-descriptions.

1954) recognized that attachment to one's ingroups does not necessarily require hostility toward outgroups. Yet the prevailing approach to the study of ethnocentrism, ingroup bias, and prejudice presumes that ingroup love and outgroup hate are reciprocally related. Findings from both cross-cultural research and laboratory experiments support the alternative view that ingroup identification is independent of negative attitudes toward outgoups and that much ingroup bias and intergroup discrimination is motivated by preferential treatment of ingroup members rather than direct hostility toward outgroup members. Thus to understand the roots of prejudice and discrimination requires first of all a better understanding of the functions that ingroup formation and identification serve for human beings. This article reviews research and theory on the motivations for maintenance of ingroup boundaries and the implications of ingroup boundary protection for intergroup relations, conflict, and conflict prevention.

Experimental research on intergroup discrimination in favor of one's own group is reviewed in terms of the basis of differentiation between in-group and outgroup and in terms of the response measure on which in-group bias is assessed. Results of the research reviewed suggest that (a) factors such as intergroup competition, similarity, and status differentials affect in-group bias indirectly by influencing the salience of distinctions between in-group and out-group, (b) the degree of intergroup differentiation on a particular response dimension is a joint function of the relevance of intergroup distinctions and the favorableness of the in-group's position on that dimension, and (c) the enhancement of in-group bias is more related to increased favoritism toward in-group members than to increased hostility toward out-group members. The implications of these results for positive applications of group identification are discussed.

In this article, we introduce the concept of social identity complexity—a new theoretical construct that refers to an individual's subjective representation of the interrelationships among his or her multiple group identities. Social identity complexity reflects the degree of overlap perceived to exist between groups of which a person is simultaneously a member When the overlap of multiple ingroups is perceived to be high, the individual maintains a relatively simplified identity structure whereby memberships in different groups converge to form a single ingroup identification. When a person acknowledges, and accepts, that memberships in multiple ingroups are not fully convergent or overlapping, the associated identity structure is both more inclusive and more complex. In this article, we define the concept of social identity complexity and discuss its possible antecedents and consequences. Results from initial studies support the prediction that social identity complexity is affected by stress and is related to personal value priorities and to tolerance of outgroup members.

We examine the relationship between the intellectual capital of scientists making frontier discoveries, the presence of great university bioscience programs, the presence of venture capital firms, other economic variables, and the founding of U.S. biotechnology enterprises during 1976-1989. Using a linked cross-section/time-series panel data set, we find that the timing and location of the birth of biotech enterprises is determined primarily by intellectual capital measures, particularly the local number of highly productive "star" scientists actively publishing genetic sequence discoveries. Great universities are likely to grow and recruit star scientists, but their effect is separable from the universities. When the intellectual capital measures are included in our poisson regressions, the number of venture capital finns in an area reduces the probability of foundings. At least early in the process, star scientists appear to be the scaice, immobile factors of production. Our focus on intellectual capital is related to knowledge spillovers, but in this case "natural excludability" permits capture of supranonnal returns by scientists. Given this reward structure technology transfer was vigorous without any special intermediating structures. We believe biotechnology may be prototypical of the birth patterns in other innovative industries.

In psychological research on cultural differences, the distinction between individualism and collectivism has received the lion's share of attention as a fundamental dimension of cultural variation. In recent years, however, these constructs have been criticized as being ill-defined and "a catchall" to represent all forms of cultural differences. The authors argue that there is a conceptual confusion about the meaning of ingroups that constitute the target of collectivism. Collectives are rarely referred to in existing measures to assess collectivism. Instead, networks of interpersonal relationships dominate the operational definition of "ingroups" in these measures. Results from a content analysis of existing scales support this observation. To clarify and expand the individualism-collectivism distinction, a theoretical framework is proposed that draws on M. B. Brewer and G. Gardner's (1996) conceptualization of individual, relational, and collective selves and their manifestation in self-representations, beliefs, and values. Analyses of data from past studies provide preliminary support for this conceptual model. The authors propose that this new theoretical framework will contribute conceptual clarity to interpretation of past research on individualism and collectivism and guide future research on these important constructs.

Social dilemmas appear in two basic forms: the public goods problem (in which the individual must decide whether to contribute to a common resource) and the commons dilemma (in which the individual must decide whether to take from a common resource). The two forms of choice dilemma are equivalent in terms of outcomes, but because they involve different decision frames, they are not psychologically equivalent In this research, framing effects on decisions involving use of a common resource pool were explored in a 2 X 2 X 2 (Public Goods vs. Commons Dilemma Task Structure X Small vs.Large Group Size X Individualistic vs. Collective Social Identity) experiment. That the two versions of the decision task were not psychologically equivalent was evidenced both by a main effect of task structure and by interactions involving task structure, group size, and social identity. Overall, subjects kept more of the common resource for themselves under the public goods version of the task than under the commons dilemma frame. Furthermore, under the commons dilemma structure, group size had no effect on choice behavior, but in the public goods version individuals in large groups kept more than did individuals in small groups. Lastly, as the resource pool was depleted, the social identity manipulation had opposite effects for large groups under commons dilemma and public goods frames.Social dilemmas exist whenever the cumulative result of reasonable individual choices is collective disaster. There are, for example, many situations in which each member of a collective has a greater incentive to act in a self-interested way, in disregard of the social consequences, even though if everyone else does the same, all will be worse off . Contemporary examples are commonplace. In a heat wave, each individual is most comfortable using his or her air conditioner at full power; yet, if all do so, an electrical overload may result, leaving everyone hotter. If enough people use moderate restraint, on the other hand, all may be reasonably comfortable, and a supply of the common resource remains available for future use. Similarly, many of us might prefer not to contribute any of our own money toward medical research, but if everyone fails to contribute, all will be worst off in the long run.These two examples illustrate the most extensively studied forms of social dilemma: the commons dilemma, in which individuals must decide how much of a shared resource to take for themselves, and the problem of the provision of public goods, in which individuals must decide whether to contribute in order to establish or sustain a common resource. Both types of dilemma are characterized by free access to the resource and by the fact that cooperative or prosocial outcomes are dependent on voluntary actions by individuals (viz., that individuals exercise appropriate self-restraint on consumption in a commons, and that Preparation of this article was supported by National Science Foundation Grant BNS83-02674 to the first author. We thank Matt Futterman for his as...