why kids include or exclude other kids from their group of friends

New research at the University of Maryland looks at why kids decide to include - and exclude - other kids from their group of friends. It turns out the decision making process is much more complex than previously believed, and could even provide insights into how to intervene when children are rejected by their peers.

Human Development Professor Melanie Killen (College of Education) led the 4-year project, which was recently published in the February, 2007 edition of Current Directions in Psychological Science (Association for Psychological Science).

Killen, who is the associate director of the Center for Children, Relationships, and Culture at Maryland says the decision making process includes a number of factors. "They take into account group information, ranging from cliques and networks, when deciding what makes a group work well. Sometimes kids are excluded because they lack social skills, but a lot of time it has nothing to do with that. Instead it has to do with what we refer to as 'group membership' such as gender, race, ethnicity, and culture."

Whatever the reason, earlier research has shown that individuals who experience pervasive long-term exclusion suffer from depression, anxiety and loneliness.

Killen's research looked at two models when trying to define how children make decisions about including - or excluding - other children from their group. One model - called the "individual social deficit model" says that rejection occurs due to a child's social deficits - including being shy, wary or fearful. In contrast, the "intergroup social cognition model" says that rejection happens due to things like group dynamics, bias, prejudice and inclusion/exclusion.

The age of the children, it turns out, is also a factor. "With age, kids become more aware of group dynamics, conventions, customs, rituals. With this sophistication comes a greater concern about group functioning, which can lead to exclusion which can be negative from a social justice viewpoint," says the University of Maryland researcher.

Most significantly, the research shows the thought process that can go into bringing new recruits into cliques and clubs. "We refer to it as 'social cognition' - cognition about the social world, including inclusion/exclusion," says Killen, who also directs Maryland's Social and Moral Development Laboratory.

This kind of research has many benefits. "Understanding how children and adolescents evaluate decisions about exclusion helps us to know why it happens, what to do about it, and how to intervene," Killen says. "Evaluations of exclusion are due to children's understandings of justice, fairness, and equality as well as the extent to which they hold stereotypes and biases about others."

The University of Maryland researcher says she wants to learn more about the decision-making process, and will be looking next at how implicit biases influence explicit judgments. "Understanding what changes from childhood to adolescence to adulthood and how different forms of group membership enter into this type of decision making (including gender, race, ethnicity, culture and religion)." -Association for Psychological Science