Before Marie-Hélène left the hospital, she had Tobie vaccinated. A key turning point, she recalls, was when Arnaud “told me that whether I chose to vaccinate or not, he respected my decision as someone who wanted the best for my kids. Just that sentence—to me, it was worth all the gold in the world.”

Marie-Hélène didn’t just allow Tobie to be vaccinated—she had his older siblings vaccinated at home by a public health nurse. She even asked if Arnaud would speak with her sister-in-law about vaccinating her children. She said her decision was unusual enough in her antivaccination community that “it was like setting off a bomb.”

Marie-Hélène étienne-Rousseau is one of many parents who have undergone a conversion like this. Vaccine whisperers don’t just help people change their beliefs; they help them change their behaviors, too. In Arnaud’s first study, with mothers in the maternity ward after birth, 72 percent said they planned to vaccinate their children; after a motivational interviewing session with a vaccine counselor, 87 percent were onboard. In Arnaud’s next experiment, if mothers attended a motivational interviewing session, children were 9 percent more likely to be fully vaccinated two years later. If this sounds like a small effect, remember that it was the result of only a single conversation in the maternity ward—and it was sufficient to change behavior as far out as twenty-four months later. Soon the government health ministry was investing millions of dollars in Arnaud’s motivational interviewing program, with a plan to send vaccine whisperers into the maternity wards of every hospital in Quebec.

Today, motivational interviewing is used around the world by tens of thousands of practitioners—there are registered trainers throughout America and in many parts of Europe, and courses to build the necessary skills are offered as widely as Argentina, Malaysia, and South Africa. Motivational interviewing has been the subject of more than a thousand controlled trials; a bibliography that simply lists them runs sixty-seven pages. It’s been used effectively by health professionals to help people stop smoking, abusing drugs and alcohol, gambling, and having unsafe sex, as well as to improve their diets and exercise habits, overcome eating disorders, and lose weight. It’s also been applied successfully by coaches to build grit in professional soccer players, teachers to nudge students to get a full night’s sleep, consultants to prepare teams for organizational change, public health workers to encourage people to disinfect water in Zambia, and environmental activists to help people do something about climate change. Similar techniques have opened the minds of prejudiced voters, and when conflict mediators help separated parents resolve disputes about their children, motivational interviewing is twice as likely to result in a full agreement as standard mediation.

Overall, motivational interviewing has a statistically and clinically meaningful effect on behavior change in roughly three out of four studies, and psychologists and physicians using it have a success rate of four in five. There aren’t many practical theories in the behavioral sciences with a body of evidence this robust.

Motivational interviewing isn’t limited to professional settings—it’s relevant to everyday decisions and interactions. One day a friend called me for advice on whether she should get back together with her ex. I was a fan of the idea, but I didn’t think it was my place to tell her what to do. Instead of offering my opinion, I asked her to walk through the pros and cons and tell me how they stacked up against what she wanted in a partner. She ended up talking herself into rekindling the relationship. The conversation felt like magic, because I hadn’t tried to persuade her or even given any advice.*

When people ignore advice, it isn’t always because they disagree with it. Sometimes they’re resisting the sense of pressure and the feeling that someone else is controlling their decision. To protect their freedom, instead of giving commands or offering recommendations, a motivational interviewer might say something along the lines of “Here are a few things that have helped me—do you think any of them might work for you?”

You’ve seen how asking questions can help with self-persuasion. Motivational interviewing goes a step further, guiding others to self-discovery. You got a glimpse of it in action when Daryl Davis asked KKK members how they could hate him when they didn’t even know him, and now I want to unpack the relevant techniques in depth. When we try to convince people to think again, our first instinct is usually to start talking. Yet the most effective way to help others open their minds is often to listen.

BEYOND THE CLINIC

Years ago I got a call asking for help from a biotechnology startup. The CEO, Jeff, was a scientist by training; he liked to have all the necessary data before making a decision. After more than a year and a half at the helm, he still hadn’t rolled out a vision for the company, and it was in danger of failing. A trio of consultants tried to convince him to offer some direction, and he fired them all. Before the head of HR threw in the towel, she threw a Hail Mary pass and contacted an academic. It was the perfect time for a motivational interview: Jeff seemed reluctant to change, and I had no idea why. When we met, I decided to see if I could help him find his motivation to change. Here are the pivotal moments from our conversation:

Me: I really enjoy being the guy who gets hired after three consultants get fired. I’d love to hear how they screwed up.

Jeff: The first consultant gave me answers instead of asking questions. That was arrogant: how could he solve a problem before he’d even taken the time to understand it? The next two did a better job learning from me, but they still ended up trying to tell me how to do my job.

Me: So why did you bother to bring in another outsider?

Jeff: I’m looking for some fresh ideas on leadership.

Me: It’s not my place to tell you how to lead. What does leadership mean to you?

Jeff: Making systemic decisions, having a well-thought-out strategy.

Me: Are there any leaders you admire for those qualities?

Jeff: Abraham Lincoln, Martin Luther King Jr., Steve Jobs.

That was a turning point. In motivational interviewing, there’s a distinction between sustain talk and change talk. Sustain talk is commentary about maintaining the status quo. Change talk is referencing a desire, ability, need, or commitment to make adjustments. When contemplating a change, many people are ambivalent—they have some reasons to consider it but also some reasons to stay the course. Miller and Rollnick suggest asking about and listening for change talk, and then posing some questions about why and how they might change.

Say you have a friend who mentions a desire to stop smoking. You might respond by asking why she’s considering quitting. If she says a doctor recommended it, you might follow up by inquiring about her own motivations: what does she think of the idea? If she offers a reason why she’s determined to stop, you might ask what her first step toward quitting could be. “Change talk is a golden thread,” clinical psychologist Theresa Moyers says. “What you need to do is you need to pick that thread up and pull it.” So that’s what I did with Jeff.

Me: What do you appreciate most about the leaders you named?

Jeff: They all had vivid visions. They inspired people to achieve extraordinary things.

Me: Interesting. If Steve Jobs were in your shoes right now, what do you think he’d do?

Jeff: He’d probably get his leadership team fired up about a bold idea and create a reality distortion field to make it seem possible. Maybe I should do that, too.

A few weeks later, Jeff stood up at an executive off-site to deliver his first-ever vision speech. When I heard about it, I was beaming with pride: I had conquered my inner logic bully and led him to find his own motivation.

Unfortunately, the board ended up shutting down the company anyway.

Jeff’s speech had fallen flat. He stumbled through notes on a napkin and didn’t stir up enthusiasm about the company’s direction. I had overlooked a key step—helping him think about how to execute the change effectively.

There’s a fourth technique of motivational interviewing, which is often recommended for the end of a conversation and for transition points: summarizing. The idea is to explain your understanding of other people’s reasons for change, to check on whether you’ve missed or misrepresented anything, and to inquire about their plans and possible next steps.