UNIVERSITY PARK, Pa. — Friendship bonds that may seem superficial at first glance could be just deep enough to produce attitude changes that help spark social transformations, according to a Penn State sociologist.

In a study, people who met and became acquainted with at least one gay person were more likely to later change their minds about same-sex marriage and become more accepting of gay and lesbian people in general, said Daniel DellaPosta, assistant professor of sociology and an affiliate of the Institute for CyberScience.

According to DellaPosta, sociologists have long proposed that when people establish certain relationships, they may change their attitudes about issues, often referred to as the contact effect. In one example of the contact effect, sociologists have debated whether knowing a person with a different sexual orientation can influence attitudes on larger issues, such as the acceptance of gay rights and same-sex marriage. However, prior to this study, the theory had yet to be rigorously tested.

"What I thought we needed in this area was a test of the contact hypothesis that was conservative — perhaps overly conservative — using the most stringent test we could possibly devise,” said DellaPosta.

DellaPosta examined data from the 2006, 2008 and 2010 editions of General Social Survey, or GSS, a sociological survey of opinions that Americans hold on a range of issues.

In 2006, about 45 percent of the people who had a gay or lesbian acquaintance expressed support for same-sex marriage. By 2010, that figure had increased to 61 percent. In 2006, only 22 percent people who did not have a gay or lesbian acquaintance said they approved of same-sex marriage. That number fell to 18 percent in 2010.

DellaPosta said that the survey data does not reveal exactly when these relationships were established, which makes the test more rigorous.

"By taking people in that 2006 baseline who were acquainted with gay and lesbian people and comparing them with other people who were similar in all visible regards, including their measured attitude toward same-sex marriage and gay and lesbian people at that 2006 baseline, who were not acquainted with gay and lesbian people, you can get a really conservative test of the contact hypothesis," said DellaPosta, who reported his findings in a recent issue of the journal Socius.

The findings could shed light on how "coming out" among gay and lesbian people impacts the general acceptance of gay and lesbian people. In the 1973 GSS, just 11 percent of Americans felt “homosexuality is not wrong at all." By 2016, that number had grown to 52 percent.

DellaPosta suggests that coming out may facilitate more contact with gay and lesbian people that then accelerates an attitude change about issues that affect the gay community.

Further, DellaPosta suggested that the contact with a gay person does not even need to be especially deep for the contact effect to appear.

"If you have very superficial contact, like just seeing someone from an outgroup in the grocery store or on the subway, you may focus more on selective behaviors that reinforce your prejudices — like someone dressing, talking or acting in a way that reinforces some negative stereotype of that group," said DellaPosta. "But, if you take the next level to mere acquaintanceship — someone whose name you know, someone who, if you saw them on the street, you might stop and chat with them for a moment — the contact effect sets in because when you suddenly have to interact with someone from an outgroup as an individual, it forces you to reconsider your biases."

According to DellaPosta, having a closer, deeper bond with a gay or lesbian acquaintance did not result in an even larger shift of attitude toward same-sex marriage. He added that the contact effect actually is larger for people who have a low probability of having a gay or lesbian acquaintance.

The GSS, created in 1972, is a sociological survey collected by the National Opinion Research Center at the University of Chicago. About 2,000 people responded to the GSS 2006 survey, but only a smaller portion were asked about their acquaintances and re-surveyed in 2008 and 2010. Just over half — about 53 percent — of those surveyed said they had at least one gay acquaintance.

Other research has looked at whether the contact theory works for other intergroup relationships, such as how people feel about immigrants and their attitudes toward immigration.

Computations for this research were performed on Penn State’s Institute for CyberScience Advanced CyberInfrastructure (ICS-ACI).