Bob Schwartz

I say, “Please don’t talk to strangers, baby”
But she always do
She say, “I’ll talk to strangers if I want to
‘Cause I’m a stranger, too”
Randy Newman, Have You Seen My Baby?

Elizabeth Bernstein writes in the Wall Street Journal:

The Surprising Boost You Get From Strangers
Sometimes a stranger—not a friend or a loved one—can significantly improve our day, providing comfort or helping to broaden our perspective

Sometimes a stranger—not a friend or a loved one—can significantly improve our day. A pleasant encounter with someone we don’t know, even a nonverbal one, can soothe us when no one else is around. It may get us out of our own head—a proven mood booster—and help broaden our perspective.

“People feel more connected when they talk to strangers, like they are part of something bigger,” says Gillian Sandstrom, a psychologist and senior lecturer in the Department of Psychology at the University of Essex, in Colchester, England, who studies interactions between strangers.

In research studies, Dr. Sandstrom has shown that people’s moods improve after they have a conversation with a Starbucks barista or a volunteer at the Tate Modern art museum in London. She’s also found that people are happier on days when they have more interactions with acquaintances they don’t know well and that students enjoy class more when they interact with their classmates.

And yet most people resist talking to strangers, she says. They fret about the mechanics of the conversation—how to start, maintain or stop it. They think they will blather on and disclose too much—or not talk enough. They worry they will bore the other person.

They’re typically wrong. Dr. Sandstrom’s research shows people underestimate how much another person will like them when they talk for the first time. And in a study in which she asked participants to talk to at least one stranger a day for five days, 99% said they found at least one of the conversations pleasantly surprising, 82% said they learned something from one of the strangers, 43% exchanged contact information, and 40% had communicated with one of the strangers again, an indication they might be making friends.

Scientists believe there may be an ancient reason why humans enjoy interacting with strangers. To survive as a species, we need to mate outside our own gene pool, so we may have evolved to have both the social skills and the motivation to interact with people who are not in our tribe.

You don’t even have to talk to complete strangers to reap the benefits. Multiple studies show that people who interact regularly with passing acquaintances, or who engage with others through community groups, religious gatherings or volunteer opportunities, have better emotional and physical health and live longer than people who do not. The researchers believe that engaging with someone we don’t know well is more cognitively challenging than interacting with loved ones: Rather than use the verbal shorthand that develops in close relationships, we have to speak in full sentences, engaging more of our brain.

Why do we enjoy talking to people we don’t know? An encounter with a stranger, when pleasant, fulfills four basic human needs, according to Rachel Kazez, a licensed clinical social worker in Chicago, who advises her patients to talk to strangers when they are feeling low. It gives us a sense of control, because we can choose whether to talk or not, and how much information we disclose.

We feel connected—it can sometimes be easier to open up and have an intimate conversation with a stranger because we know we won’t see that person again. We get to feel capable, because they don’t know our insecurities or setbacks. And the encounter may give us a sense of meaning or purpose, especially because a stranger doesn’t have to be nice to us.

“If you are feeling lonely and have a nice interaction with a stranger on a bus, you can suddenly feel like: ‘Oh, I fit in. I’m part of this city,’ ” Ms. Kazez says.