04/22/2013 06:03 pm ET Updated Dec 06, 2017

School Size and Interracial Friendship

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School brochure pictures notwithstanding, by and large, students hang around kids of their same race. But it turns out that the type of school they go to might encourage or subvert this tendency.

A new study by Siwei Chang and Yu Xie of the University of Michigan analyzed simulated data from a model of how we form friends as well as the real friendships of 4,745 American high school students and concluded that the smaller the school (i.e., the context for making friends), the more likely students were to form interracial friendships.

In a press release, Xie is quoted as saying, "We found that total school size had a major effect on the likelihood that students would form interracial friendships. Large schools promote racial segregation and discourage interracial friendships."

Friendship formation is governed by a similarity drive: We like people like us. In addition to a general preference for friends of our same race, Xie and Chang looked at other typical preferences for friends similar to us in terms of age, education, hobbies, personality, religious affiliation and political beliefs. They found that when the pool of potential friends is small, it's unlikely that students will find a same-race friend who embodies their other preferences. The bigger the student population, though, the more likely they will find same-race friends who share these other traits listed above.

These new results neatly line up with research by Angela Bahns at Wellesley College, whom I interviewed for Friendfluence. Bahns looked at college students and their friends and found that pairs of friends on large campuses were significantly more similar in terms of their attitudes, beliefs and health behaviors than pairs of friends at smaller, more homogeneous schools. As I wrote in my book:

Bahns reasons that people from the bigger schools were able to satisfy their similarity drive more thoroughly than those from the smaller schools. "They took a more fine-grained approach in finding a closer match," she says, "whereas in smaller environments, people might have that same fundamental drive but are constrained by the environment, meaning their criteria have to be relaxed." It's not simply that in the smaller environments students befriended others with different hobbies or interests. It's that they had friends with different outlooks and lifestyles, which presumably opened their minds in the fashion that college is supposed to.

Secondly, and more surprisingly, the friendships on the smaller campuses, among people who were less similar to each other, were closer. "My guess is that the higher quality of these friendships stems from the fact that the students are aware that they are kind of stuck with who they've got, and if a friendship doesn't go well, they can't just trade that friend up for a better one." (This is the inverse of what many have said of online dating: It creates a sense of endless possibility and therefore less of an urge to commit to just one.) "A lot of research implies that because it's an attraction, similarity is a good thing that leads to longer, more satisfying relationships. Here we have a little bit of data that questions that," Bahns says.

James Vela-McConnell, a professor of sociology at Augsburg College, conducted interviews with people who had friends of other races, sexual orientations and genders for his book Unlikely Friends: Bridging Ties and Diverse Friendships. Echoing what Bahns found, his subjects described unlikely friendships as eye-opening and horizon-broadening. Differences became a source of bonding rather than an impediment to it.

Together, these studies provide important, maybe even crucial, information about the environmental contexts that best encourage "unlikely" friends. They also indicate that these friendships might be more satisfying than our mirror-image default pals. Hey, these friendships could even change the world: As Rodolfo Mendoza-Denton puts it, cross-race friendship is "the single best antidote to prejudice and racism."