If you ask a random sample of friends how they became friends, they will probably tell you that they like a lot of the same things and, perhaps more important, that they like the same people. So they may. But one of the surest routes to friendship is disliking the same things about other people, according to Jennifer Bosson and three colleagues, who published “Interpersonal Chemistry Through Negativity: Bonding by Sharing Negative Attitudes About Others” this past June in the journal Personal Relationships.

“It’s not that we enjoy disliking people,” Bosson, a social psychologist at the University of South Florida, says. “It’s that we enjoy meeting people who dislike the same people.” To prove their case, Bosson and her colleagues conducted three separate studies. In the first, they asked college students to recall the formation of their closest friendships; in the second, they asked students about the attitudes toward others that they currently shared with their three closest friends. “We found a very robust tendency for people to mention more negative than positive attitudes about other people,” Bosson says, and the closer the friends were, the more negative attitudes toward others that they shared.

Gossipers might shrug at this, but in the third study, Bosson asked whether you could take two strangers and get the same effect. The researchers told a group of 97 students that they were going to meet someone, then they played them a tape of a conversation between two supposed undergrads, Brad and Melissa. “He’s obviously hitting on Melissa but he’s also nice to her,” Bosson explains. “We wanted it to be a typical interaction between undergraduates.” After listening to the tape, the students were asked to list one thing that they liked about Brad and one thing that they didn’t.

The researchers then told the students that they were going to meet another student who either shared their positive idea about Brad or their negative idea about Brad. Next they were asked to rate the likelihood of their liking that person. “Overall,” Bosson says, “people expressed stronger beliefs that they could be friends if they thought they shared their negative evaluation.” As for people who like the same things about other people, they “aren’t doomed,” Bosson says. “They’ll just have to keep talking until they find something about someone that they both dislike.”