You’re meeting someone for the first time — a friend of a friend. She seems pleasant. She mentions her love of burrito bowls and HGTV. You like burrito bowls. You like HGTV. This seems like a person you can get along with. But then she leans forward and, lowering her voice, confides that your mutual pal has been driving her nuts lately. Five minutes of shit-talking later, and you feel like you have a new best friend.

Since at least the 1940s, social psychologists have recognized that shared opinions — negative, as well as positive — can facilitate bonding between two strangers. But it was always assumed that if two people don’t know each other well, sharing positive attitudes is the best way to form a relationship. Negativity is a turnoff as well as a faux pas — or so the thinking went.

But a handful of recent studies have turned some of this conventional wisdom on its head. Sharing negative attitudes with someone — and, in particular, sharing negative opinions about other people — seems to be among the quickest and most effective ways for two strangers to form a bond. If you want to cozy up to someone, there may be no better way to do it than to gossip about the people you both hate.

“Similarity is a big attractor in general, so I don’t want to downplay the effectiveness of sharing likes,” says Jennifer Bosson, a professor of psychology at the University of South Florida. “But learning that you share a negative attitude has a stronger effect and facilitates liking more.”

Beginning in the early 2000s, several of Bosson’s experiments helped shift the thinking on the power negative opinions have in facilitating interpersonal bonding.

In a small 2006 study, she and colleagues asked participants to listen to a recorded conversation between a man and a woman — “Brad” and “Melissa” — and to write down one thing they liked and one thing they disliked about Brad. The participants then learned they would meet someone else taking part in the study who had completed the same listening exercise. Some participants were told this other person (who wasn’t real) had disliked the exact same thing that they disliked about Brad. Others were told the stranger liked the same thing they had liked. The researchers then polled the participants about how much they expected to bond with the stranger. Surprise surprise, the shared dislikes fostered a greater expectation of closeness and bonding than did the shared likes.

Bosson verified and refined her conclusions in several follow-up experiments. Regardless of gender or race, disliking the same thing about a person can help strangers bond more effectively than if they share the same positive opinions. The stronger the shared dislike, the closer the resulting bond is likely to be.

What explains this? “When someone expresses a negative attitude about a third party, that’s a counter-normative behavior,” Bosson says. By “counter-normative,” she means a social action that people view as unconventional and not desirable. When a stranger displays a counter-normative behavior, “we feel like we just learned something about that person — like we know them better,” she says.

One example: Imagine watching someone cross a street in front of a car. The normative behavior would be for that person to wave to the driver. “But if you saw the person give the driver the middle finger, as opposed to waving, you’d feel like you knew something more about that person,” Bosson says. If you also happen to share that person’s counter-normative view — maybe the way the driver stopped suddenly made your own middle finger itch — that combination of feeling like you know the stranger and also sharing his or her counter-normative opinion is “a powerful attractor,” she says. “This gives you the instantaneous sense of bonding with somebody.”

“It confirms our view of the world and it validates our thinking, and we like people who validate us.”

There are other, more deeply seated explanations for why shared negative opinions may be an especially strong social glue. Experts say the last million or so years of human evolution may have programmed us to bond over the people we dislike.

“Psychologically, I think there are a lot of buttons that get pushed when someone hates the same person we do,” says Frank McAndrew, a professor of psychology at Knox College in Illinois. “It confirms our view of the world and it validates our thinking, and we like people who validate us.”

McAndrew’s specialties are social and evolutionary psychology. “I work on the assumption that we’re walking around with these caveman brains that evolved in a world of small groups and face-to-face interactions,” he says. In that sort of world, any stranger could be member of a competing group or tribe and pose a mortal threat to you or your loved ones. But if it turned out that the stranger dislikes the same groups or tribes you dislike, that gives you a solid basis for cooperation and trust.

Forming this kind of alliance scratches another fundamental itch. “Being accepted fosters a feeling of belonging, which is a basic human need,” adds William Swann, one of Bosson’s collaborators and a professor of social and personality psychology at the University of Texas. But to feel like you’ve been accepted into something requires that others be excluded. (After all, the more members a club has, the less people want to join.)

Even within groups or tribes, shared negative opinions are often more appealing to us than shared positive ones. McAndrew says that human social structures are nearly always hierarchical — and also in flux. The people at the lower rungs of the ladder are trying to climb up, and to do that they usually have to pull others down. In this context, gossip comes in handy. “We like negative information because it’s more exploitable if we’re trying to gain ground on somebody,” he says. “Finding out good things about someone you’re competing against doesn’t really help you, but finding out negative things is useful.” (This may help explain that shameful tingle of satisfaction you feel when a friend loses his job or gets dumped by his partner; when someone else’s situation worsens, it feels like your own has improved by comparison.)

While this built-in propensity to bond over poor opinions can help people form close friendships or allegiances, the obvious dark side is that it can strengthen feelings of dislike or hatred toward others. “Discussing beliefs about the negative qualities of outgroup members will make those beliefs more vivid and easy to recall, which could bolster the strength and certainty of those beliefs,” Swann explains. This can “tip the balance” from simply disliking someone or a group of someones to truly hating them, he says.

In some cases, this hatred can go so far as to make the outgroup members seem inhuman, says Dr. Richard Murrow, a distinguished professor of neurology at the University of North Carolina who has studied the neurobiological underpinnings of hate speech. Murrow says this dehumanization of the “other” probably served an important purpose in early human societies. “It allows members of one tribe or nation to kill outsiders who may threaten the collective, and to do so without remorse,” he says. “Early attempts at civilization would not have survived competition from other groups without this adaptation.”

But this predisposition is proving to be less helpful in contemporary life.

The advent of the internet, in particular, may be hijacking and exaggerating many of our worst inclinations. The long-standing “if you can’t say anything nice” ethics of polite society — long on the wane — have been incinerated, and replaced by an online ethos that seems to reward brutal criticism above all else.

“The internet is taking our primitive thirst for gossip and reputation-seeking and bonding with like-minded people and amplifying it a thousand times,” McAndrew says. Sharing hatred online may be a great way for disparate communities of strangers to form bonds and to feel more connected with one another, but it can also delude us into thinking our poor opinions about certain people or groups are normal and justified, he says.

Bosson agrees. “Sharing negative opinions of others may increase group cohesiveness and also fuel intergroup prejudice,” she says. She points out that a lot of social media today seems to revolve around reinforcing shared dislikes — whether it’s of another political party, another sports team, or some other reviled outgroup. “These behaviors are validating and enforcing, and so they meet a psychological need for us,” she says, “but the consequences in the grand scheme of things can be disastrous.”

When things get so heated that one group stops seeing the other as human, she adds, “the ultimate outcome is often war.”