Why do we fall for particular people?

Even the shortest ties can sometimes lead to the deepest bonds in life. Like when you attend a party and run into someone wearing the T-shirt of your favourite band, or who laughs at the same jokes as you, or who picks up the oddball food you alone (or so you thought) enjoy.

My favourite is when a conversation is started by a tiny, common interest that develops into an enduring love.

We tend to prefer people who are similar to us; this phenomenon is known as the similarity-attraction effect. New research from Boston University has now uncovered one of the causes.

Charles Chu, an assistant professor of management and organisations at the BU Questrom School of Business, studied the factors that influence how attracted or turned off we are by one another in a number of studies.

He discovered that self-essentialist thinking, where people believe they have a deep inner core or essence that shapes who they are, was a key determinant.

Chu found that when someone believes an essence drives their interests, likes, and dislikes, they presume the same is true for others as well. If they locate someone with a single similar interest, they anticipate that person will share their larger worldview.

The Journal of Personality and Social Psychology of the American Psychological Association published the findings.

"If we had to come up with an image of our sense of self, it would be this nugget, an almost magical core inside that emanates out and causes what we can see and observe about people and ourselves," says Chu, who published the paper with Brian S Lowery of Stanford Graduate School of Business.

"We argue that believing people have an underlying essence allows us to assume or infer that when we see someone who shares a single characteristic, they must share my entire deeply rooted essence, as well."

But Chu's research suggests this rush to embrace an indefinable, fundamental similarity with someone because of one or two shared interests may be based on flawed thinking--and that it could restrict who we find a connection with.

Working alongside the pull of the similarity-attraction effect is a countering push: we dislike those who we don't think are like us, often because of one small thing--they like that politician, band, book, or TV show we loathe.

"We are all so complex," says Chu. "But we only have full insight into our own thoughts and feelings, and the minds of others are often a mystery to us. What this work suggests is that we often fill in the blanks of others' minds with our own sense of self and that can sometimes lead us into some unwarranted assumptions."

To examine why we're attracted to some people and not to others, Chu set up four studies, each designed to tease out different aspects of how we make friends--or foes.

In the first study, participants were told about a fictional person, Jamie, who held either complementary or contradictory attitudes toward them.

After asking participants their views on one of five topics--abortion, capital punishment, gun ownership, animal testing, and physician-assisted suicide--Chu asked how they felt about Jamie, who either agreed or disagreed with them on the target issue.

They were also quizzed about the roots of their identity to measure their affinity with self-essentialist reasoning.

Chu found the more a participant believed their view of the world was shaped by an essential core, the more they felt connected to Jamie who shared their views on one issue.

In a second study, he looked at whether that effect persisted when the target topics were less substantive.

Rather than digging into whether people agreed with Jamie on something as divisive as abortion, Chu asked participants to estimate the number of blue dots on a page, then categorized them--and the fictional Jamie--as over- or under-estimators.

Even with this slim connection, the findings held: the more someone believed in an essential core, the closer they felt to Jamie as a fellow over- or under-estimator.

"I found that both with pretty meaningful dimensions of similarity as well as with arbitrary, minimal similarities, people who are higher in their belief that they have an essence are more likely to be attracted to these similar others as opposed to dissimilar others," says Chu.

In two companion studies, Chu began disrupting this process of attraction, stripping out the influence of self-essentialist reasoning. In one experiment, he labelled attributes (such as liking a certain painting) as either essential or nonessential; in another, he told participants that using their essence to judge someone else could lead to an inaccurate assessment of others.

"It breaks this essentialist reasoning process, it cuts off people's ability to assume that what they're seeing is reflective of a deeper similarity," says Chu.

"One way I did that was to remind people that this dimension of similarity is actually not connected or related to your essence at all; the other way was by telling people that using their essence as a way to understand other people is not very effective."

Chu says there's a key tension in his findings that shape their application in the real world.

On the one hand, we're all searching for our community--it's fun to hang out with people who share our hobbies and interests, love the same music and books as us, and don't disagree with us on politics.

"This type of thinking is a really useful, heuristic psychological strategy," says Chu. "It allows people to see more of themselves in new people and strangers." But it also excludes people, and sets up divisions and boundaries--sometimes on the flimsiest of grounds.

"When you hear a single fact or opinion being expressed that you either agree or disagree with, it really warrants taking an additional breath and just slowing down," he says.

“Not necessarily taking that single piece of information and extrapolating on it, using this type of thinking to go to the very end, that this person is fundamentally good and like me or fundamentally bad and not like me.”

Chu, whose background mixes the study of organisational behaviour and psychology, teaches classes on negotiation at Questrom and says his research has plenty of implications in the business world, particularly when it comes to making deals.

"I define negotiations as conversations, and agreements and disagreements, about how power and resources should be distributed between people," he says.

"What inferences do we make about the other people we're having these conversations with? How do we experience and think about agreement versus disagreement? How do we interpret when someone gets more and someone else gets less? These are all really central questions to the process of negotiation."

But in a time when the political division has invaded just about every sphere of our lives, including workplaces, the applications of Chu's findings go way beyond corporate horse-trading.

Managing staff, collaborating on projects, and team bonding--all are shaped by the judgments we make about each other.

Self-essentialist reasoning may even influence society's distribution of resources, says Chu: who we consider worthy of support, who gets funds and who doesn't, could be driven by "this belief that people's outcomes are caused by something deep inside of them."

That's why he advocates pushing pause before judging someone who, at first blush, doesn't seem like you.

"There are ways for us to go through life and meet other people, and form impressions of other people, without constantly referencing ourselves," he says.

"If we're constantly going around trying to figure out, who's like me, who's not like me? that's not always the most productive way of trying to form impressions of other people. People are a lot more complex than we give them credit for."