magazine issue 6 2015 / Issue 26

To affinity and beyond! How our preference to be among similar people interacts with our social ecology

• written by Joanna Schug & Philip S. Lu
• edited by Laysee Ong

They asked groups of American and Japanese participants to report their preferences for similarity in a potential new friendship partner and also asked them to estimate the similarity between their close friends and themselves for a number of traits. They found that both American and Japanese participants preferred a similar person as a friend. But the extent to which they reported how similar they were to their existing friends depended on how much relational mobility they felt existed in their social environment: the lower the perceived relational mobility, the lower the similarity among their friends. In fact, when they looked at Japanese and American participants who perceived their social network as having the same level of relational mobility, there was no cultural difference in how similar they and their close friends were—participants in both countries who felt there were more chances to form new and leave old relationships felt their friends were more similar. It seems like people in Japan and the US aren’t so different after all-- Americans just seem to have more opportunities to choose new (and discard old) friends.

The size of the pool matters

The ability to choose from a larger number of choices gives people more chances to put their preferences for similarity into practice. This was highlighted by a study conducted by Bahns, Pickett, and Crandall (2012). They approached pairs of students who happened to be hanging out either at a large university or a small college campus, and asked them to fill out a survey. They found that pairs from the small college campus tended to be less similar to each other than pairs from the large university campus, suggesting that the larger pool from which students selected their friends allowed them to choose a more similar friend. This result is even more impressive when you think about the fact that the large university overall had a more diverse group of students.

Another study conducted by sociologist Ishiguro (2011) examined the levels of actual similarity between pairs of close friends in Japan. He found that you could use the number of people an individual had met in the past year, and the number of people they knew overall, to predict how similar the friends were in the pairs. The more acquaintances, the more similar the friends were. Research on homogamy has also shown that people who broaden their search to extend outside of narrow ethnic and religious communities are more likely to find a similar mate in terms of personality than those who do not (Ahern, Cole, Johnson, & Wong, 1981; Guttman, Zohar, Willerman, & Kahneman, 1988). It seems like widening the size of the pool you choose from translates to higher levels of similarity. The important thing to remember is that the effects of similarity are brought about by personal choices—random mobility should not have an impact on the similarity among people. In this sense, our choices about whom we associate with, combined with our preference for similarity, is what causes levels of similarity between friends and couples to increase. Next, we will discuss implications of these choices for society at large.

The dark side of the preference for similarity

So far we’ve established that people tend to prefer similar others, but whether or not you can actually end up in relationships with similar people depends on the social environment, and how easy it is in that environment to choose people to form relationships with. That is, the higher the relational mobility of the environment (the more choices one has to form new and leave old relationships), the more chances there are for people’s preferences to translate into actual choices.

This might sound like a good thing, but a lot of other research suggests that there are unfortunate societal level consequences to people getting what they want in societies high in relational mobility. For example, people who are highly desirable will have no trouble meeting and forming relationships with others who are highly desirable. While this might be good for them, this means that people who are a little less desirable might have a much harder time with relationships in high-mobility societies. Thus relationships have the potential to be much more stratified socially, with those who are more highly desirable winning out.

One example of this social stratification can be seen in educational homogamy. Since the 1960s, the tendency for people to marry others with the same level of education has been increasing in the US (Mare 1991, Schwartz & Mare 2005). Now more than ever, people are marrying and having children with those of similar educational backgrounds.

Now you might be wondering whether this increase in educational homogamy is due to an actual increase in the preference for similarity in educational attainment, or due to some other factor, such as the fact that more women are attending college these days. The answer appears to be a bit of both. One commonly accepted explanation is that because women’s access to education and opportunities in the workforce have improved, the education and economic status of women is now a relevant factor for men to consider in selecting their mates (Oppenheimer 1988, Sweeney 2002), compared to when it was still relatively rare for women to go to college or join the workforce.