I've been sitting in on Robert Kraut's online communities course. He's a visiting lecturer from CMU with a background in social psychology, and consequently the course is heavy on theory and empirical studies. In it, he discusses how theories of social psychology can help us understand and build online communities.

So far, we've covered community structures, motivations for contribution and ways of encouraging it, the ways in which newcomers assimilate into the community, and the ways in which relationships can form within a community. We've also talked a little about groups within communities, for example as sources of motivation and social loafing, shared identity and discrimination.

Recently, while talking about the last of these, discrimination, someone mentioned 'Blue Eyes / Brown Eyes', a lesson taught by a teacher, Jane Elliot, to classes of 3rd graders in Iowa during the years following Martin Luther King's assassination. In it, she teaches them about discrimination by dividing them into brown and blue eyed groups, then praising one group and criticizing the other.