Next time you enter an elevator, walk in and keep facing the back wall. If you stay that way, in my experience, people will laugh or ask if you’re okay. (That’s an opportunity, if you want, to say you would love for someone to define “okay.”)

Standing this way breaks unstated rules of how we’re supposed to behave in elevators. Detaching from expectations gives people an excuse to talk, to acknowledge one another’s humanity. Absent a break in the order, the expectation is silence.

(Of course, you can make a quick joke—my favorite is, if the elevator is stopping frequently, “What is this, the local train?”—and expect a modicum of laughter. But even if the joke goes over well, the rule seems to be that you can’t say it more than once in the same ride.)

The celebrated Canadian sociologist Erving Goffman saw elevators as microcosms of society. Described by the Times Literary Supplement as “a public private eye,” Goffman covertly studied people as they rode in elevators in 1963. He noted that the rule upon entering seemed to be to give some brief visual notice of other passengers, and then to withdraw attention, not making eye contact again at any point. (Though 35 percent of people added one or two glances to the initial look.)

Goffman called this civil inattention. That is, we act civilized toward one another—not harming anyone or blocking their paths or shouting in an enclosed space—but also not attentive. This goes on today, wherever people might be described as alone together.

“That’s the principle that’s operational when people aren’t talking to each other on the subway,” Kio Stark, the author of the forthcoming book When Strangers Meet, explained to me. “You can pretend you’re there by yourself.”

And this is good and necessary at times, especially in a city as bereft of solitude as New York. But it can be overdone. As Stark argues from the top of the book, “This if nothing else: Talking to strangers is good for you.”

Her work appealed to me because I’ve suggested as much in a mediocre piece called “Always Talk to Strangers.” That was based on a study that found that people who considered their neighbors to be friendly and trustworthy were less likely to have heart attacks. Other public-health research has shown improved moods among commuters who chat on the subway, and happiness and creativity among people who talk to strangers.

Kio Stark always has and does. She was born in a New York family and doesn’t think it’s rare. Her reasons are many, but among the most compelling is essentially boredom. She writes that a stranger-encounter is “an exquisite interruption” to whatever expectations you had about your day. Go to work, and you know who you’ll see. Hang out with friends, and you know what to expect. But engage with a stranger, and at least something interesting might happen.

“It’s not only about novelty,” she added when we spoke. “It’s about feeling connected to my block, my neighborhood.”

At a grander scale, in an increasingly polarized society, it can require concerted effort to break out of sociocultural strata and online algorithms that are constantly pairing us with like-minded people. (Don’t know anyone who’s voting for Trump? That’s on you.)

Beyond the promise of a unique and enlightening experience, there is also the little jolt of breaking a rule. Of course, not a rule rule, like harassment or assault, but an unstated social rule. It’s up to us to know when and how to break those rules in ways that don’t unduly offend or put other people out. That’s the hard part. So she suggests exercises to start. Figure out what makes you uncomfortable, and target ways to get over those. A good one for most people is just to do an exercise where you walk around your neighborhood and just say “hi” to everyone you see.

Once you’ve mastered that, try having an actual interaction (not necessarily a conversation). That usually works well by doing what Stark calls “triangulation.” That’s sociology-speak for remarking on something external to both you and the stranger—something you’re both experiencing or observing. Like the weather, but less boring. Commenting on a shared experience tends to be less confrontational than making a remark about the other person directly, however flattering (read: creepy).

Willing listeners and your correspondent in Prospect Park, Brooklyn (Nicolas Pollock / The Atlantic)

Once you’ve mastered saying hi and triangulating, Stark suggests advanced strategies like asking people profound existential questions, or getting lost in a neighborhood where you have to genuinely ask people for directions. And, before doing that, embrace the sensation of being “the stranger” who doesn’t belong. She describes that as “emotionally risky.”

So I didn’t try that one. But I did attempt some others, and you can watch them here in today’s captivating episode of If Our Bodies Could Talk.

If Our Bodies Could Talk

One fun behind-the-scenes fact is that I met a guy named Enrique in the park, and he was there practicing on his brand new, red guitar-kelele. (It’s barely larger than a ukelele, and has six strings like a guitar.) We chatted for a while, and I asked if I could play it. He kindly agreed. I played for a long time. I played all of “Stairway to Heaven.” I was sort of testing the waters of his politeness, which were apparently boundless. Anyway, we had to cut this footage because our legal team told us that someone already owns the performance rights to “Stairway to Heaven.”

Stark’s book is a 101 introduction to stranger engagement. It serves primarily to call attention to the profound implications of the art, at times uneasily high-minded for a 100-page primer, as with the opening line “How do you divide the world into known and unknown?”

That is, though, the question at the heart of this practice. Once we consider a person known, our behavior toward them changes entirely. We can emote and commiserate and learn and be ourselves.

When it comes to knowing people, that line is still often drawn at whether you’ve spoken to a person before. If you have, you know them. A significant threshold to be crossed with a simple act.