Belonging Community: Being at home in an urban neighbourhood

How do friendships form? gives some insight into why mixed neighbourhoods are important. The study, from Marmaros and Sacerdote, researchers from Google and Dartmouth College, tracked the 4.2 million e-mail exchanges between university students for more than a year to identify the social networks they established.

As Dartmouth students are assigned randomly to student residences, the researchers were able to track how factors like geographic proximity, family background, racial identity and shared student activities affected the formation of friendships between students.

The literature explains we are most likely to become close friends with people with whom we have frequent contact.  Fostering friendship with a random stranger further away requires an additional investment of time with no guarantee of a positive pay-off of a close friendship. Marmoros and Sacerdote wanted to test the theory that we are more likely to become close friends with someone with whom we have “lots of local, low cost social interactions.”

In essence, when we see a neighbour regularly, we get a short-term and a long-term benefit: in the immediate interaction, we are provided with the opportunity to exchange information and then, over the course of time, trust is built through reciprocity. Both these benefits can emerge at a fairly low cost to ourselves without a large investment of time or other resources. Random interactions expose us to the possibility of bigger pay-offs.

Marmaros and Sacerdote found such a “neighbourly effect” among the students whom they mapped. Students were more likely to form friendships with those who lived close to them or who shared an activity or class. The effect was lessened if students did not share the same racial or family background, however, the effect was still positive.

A caution from the study:

• The positive effects on social interaction were only found at fairly close distances, such as among those living on the same floor in a school dorm.

Otherwise shared activities were required to demonstrate significant cross-cultural friendship formation. Even while seen as a broad societal benefit, the authors explained, an individual may be less likely to form a cr0ss-cultural friendship if it is seen as more “costly” in terms of time or additional risk factors. Happily, proximity to each other seems to help overcome the racial barrier.

Two additional noteworthy upsides:

• Close friendships continued even when students moved further distances from each other. The opportunity to form friendships across a variety of identities, provided by living close to each other, provides a lasting effect. Once friendships are formed, most students found it worth continuing to invest in them.
• Citing other research and expanding on their own, the authors describe the positive equity effects on the attitudes of white students who live with a Black roommate. While the white students were not more likely to have a larger circle of Black friends (as a result of having one Black friend), they are “more likely to support affirmative action in admissions and societal income redistribution.”