So a social identity invokes a number of different areas of psychological competence: knowledge, motivation, perception, memory, personality, and emotion, to name a few. And yet one's social identity seems to stand a bit apart from any of these psychological concepts singly. Cognitive psychology focuses on some aspects of this mix; social psychology and personality psychology focuses on other aspects; but there is no area of psychology that attempts to capture all of "social identity" as a psychological real process or structure.
Moreover, a social identity is embodied in an individual; and yet it is produced by the experiences we have in relations to other individuals and groups. A social identity can be said to be a feature of a group or a community as much as it is a feature of particular individuals within a given community. And this fact is causally important: we can't explain the individual's identity without reference to the sustained and fairly consistent features of the group with respect to its social identity. So a social identity has an aspect of "social-ness" that cautions us against a narrowly psychological interpretation of the concept.
We might single out a number of aspects of a social identity as a psychologically real construct, embodied in a particular person through a particular body of experience and a specific location within a community:
- an epistemic frame in terms of which I understand the social world
- an element of my psycho-cognitive-emotional apparatus
- a model of how to behave in certain common social settings
- a self-ascription defining the features of action and comportment that are most defining of "me" in the world
- a self-valorization of the things that are most worthwhile to me
- an account of who I'm related to and similar to; who my affinity groups are
- a map expressing my location within a particular extended community
In addition, it is important to recognize the feature of "intersectionality" that characterizes social identities: the ways in which one's identity involves a crossing of different grounds of identity and affinity. (University of Michigan social psychologist Elizabeth Cole has published a useful recent article called "Coalitions as a Model for Intersectionality: From Practice to Theory" in Sex Roles; here is a link. I also found the Wikipedia article on intersectionality to be valuable.)
Identities aren't "pure" expressions of one particular feature of one's location in the social world; instead, features of sexual identity, geographical identity, class identity, racial and ethnic identity, professional identity, and cohort identity all play a role in constituting one's overall identity. This means that it is important to give concrete attention to the multiple forms of social influence and immersion through which a given individual comes to embody a complex social identity; we need to look to the microfoundations of identity formation. (See more on this approach here.)
And this point about intersectionality also raises the likelihood of internal conflict. One's identity as an Asian American may be in some conflict with features of identity derived from one's location within the hip-hop generation or one's professional status as a junior member of an accounting firm. And the modes of behavior implicated by one strand may be at odds with those created by the other strands.
Innovative efforts to provide fresh approaches to the study of social identities are emerging in several fields. Paula Moya and Michael Hames-Garcia's Reclaiming Identity: Realist Theory and the Predicament of Postmodernism is an introduction to a genuinely innovative approach to the study of identities that attempts to bring literary criticism, race and gender studies, and social theory into one extended discussion.