The gentle science of persuasion, part three: Social proof

Social psychologists have long known that human beings often make choices about what to think, and what to do, based on the thoughts and actions of others. Simply stated: We like to follow the crowd. As a psychological phenomenon, it's called "social proof." And according to Robert Cialdini, the Regents' Professor of Psychology and Marketing at Arizona State University and Distinguished Professor of Marketing in the W. P. Carey School, "social proof" is one of the six key principles underlying the powerful science of persuasion.

More than a few Americans fancy themselves individualists, immune to the tides of popular opinion. Robert Cialdini knows better. A renowned social psychologist, Cialdini has seen up close what researchers in his field have long known — that human beings often make choices about what to think, and what to do, based on the thoughts and actions of others. Simply stated: We like to follow the crowd.

As a psychological phenomenon, it's called "social proof." And according to Cialdini, the Regents' Professor of Psychology and Marketing at Arizona State University and Distinguished Professor of Marketing in the W. P. Carey School, "social proof" is one of the six key principles underlying the powerful science of persuasion.

"Multiple others and similar others — those are the key amplifiers of the social proof effect," says Cialdini, one of the world's leading experts on persuasion. "If you can get people who are similar to the person you're trying to persuade to speak on your behalf, it's a lot easier for you than if you have to try to hammer your message one more time into a reticent mind." Savvy businessmen and so-called "influence professionals" have long used the power of persuasion to their advantage, and recently, Cialdini set out to better understand how these master persuaders practice their science in the real world.

He interviewed professional persuaders in marketing and advertising, infiltrated training sessions for sales jobs and studied the tactics of military and corporate recruiters and of fundraisers. The experience confirmed what Cialdini has been preaching for years: That influence professionals make persuasion work not through luck, but rather by leveraging six specific psychological principles.

"We have looked directly at the way people act in a particular situation, recognizing that sometimes they'll act for reasons that have nothing to do with their attitudes, or beliefs, or perceptions but that have everything to do with one or another of these six principles," Cialdini says.

Each of these six principles, if used correctly, can provoke a strong psychological response among subjects of persuasion. In a six part series, Knowledge@WPCarey is offering readers an in-depth look at each of these principles — as well as a peek into the fascinating world of professional persuasion. In previous stories, we examined the principles of "liking" and "reciprocity." Today, we turn to the third, the principle of "social proof."

Use the crowd

Social proof uses "the many" to influence the few. It's a simple but powerful idea. And when social proof has been put to the test in the real world, it's proven its worth. Take, as an example, Cialdini's recent investigation into those hotel signs, posted so often in guest rooms, asking that guests recycle their towels and linens.

Given the amount of water and energy that can be saved if linens were recycled, it seems to be a reasonable request. But it hasn't necessarily been an easy thing to get people to do: Just ask hotel chains, which for years have seen these requests go unheeded. "The question occurred to me when I first saw these signs: What's the best thing that hotels could say on the sign to get people to do that?" says Cialdini.

"When you see these signs, they generally say something like, 'Do it for the environment,' or 'Do it out of social responsibility' or 'Do it for your children's sake,' all of those kinds of things." Cialdini suspected that hotels might get a much better response if they simply changed their message, using the leverage of social proof to get people to re-use those old towels.

What if, Cialdini wondered, the signs said, simply: "The majority of the guests who have stayed in this room recycled their linens." A quick study revealed exactly what Cialdini predicted. Signs that used the social proof message — informing guests that other guests re-used their towels — proved to be much more effective than other signs. "That's the principal of social proof," Cialdini says.

"All those marketing minds at Sheraton and the Four Seasons and the Ritz Carlton, why didn't they come up with this? It's because you need to look at social science evidence for what might be available to you there." There are other examples, too, that illustrate how social proof can be especially powerful when the "many" appear to be similar to individuals that need to be influenced. That "similarity," says Cialdini, is an important aspect of the principle, as the following research attests.

A famous 1960s study in New York found city residents were highly likely to return a lost wallet when they were told another New Yorker — somebody like them — had already attempted to do so. When they were told a foreigner — somebody unlike them — had previously attempted to return the wallet, however, that influence disappeared.

A 1982 study published in the Journal of Applied Psychology by Peter Reingen of ASU's W. P. Carey School of Business, meanwhile, tested social proof and similarity in the realm of charity. For the study, a group of researchers requesting donations door-to-door used a unique ploy to influence potential donors' decisions: After explaining the charity and what it did, the researchers then showed residents a list of other residents from the neighborhood who had already donated.

The result? The longer the donor list, the team found, the more likely residents were to give money themselves. "That's evidence that if many others have done this, then I'm likely to do it, too," Cialdini explains. "But if those many others are similar to me, too, I'm even more likely to follow."

Social proof in the office

More than a few managers have probably encountered this real-world problem: They craft an exciting new initiative, convinced it can solve an internal organizational flaw, boost sales or give the company a competitive edge. Then they pitch it to their staff — and meet resistance from a few key staffers, who are often old-timers who've grown comfortable with the way things are. It's a problem that social proof can solve, Cialdini says.

"As a manager, if you've got a new initiative that you're trying to get people on board with, but you've still got some people hanging back who aren't convinced, you have to realize that you're not the best communicator," Cialdini says. "The best communicators know when they're not the best communicators. And then they offload that job to the people who are the best communicators."

When managers meet staff resistance, the best communicators, says Cialdini, are the staffers who are supportive of the plan. Managers in these situations, then, would be wise to seek out those staffers and use them to their advantage. The reason? Reluctant workers are much more inclined to listen to the reasoning of a colleague they know and trust — and can relate to — rather than a manager or executive that may not understand their daily challenges.

"In those situations, the manager in a team meeting should simply give voice to the individuals who have already gotten on board with the plan — including maybe one of the real old-timers," Cialdini says. "Managers should actually ask them, 'Hey Jim, what's your thinking on this?' Then, when Jim says yes, that will persuade Harry a lot more than you ever could."

Bottom line

• According to the social proof principle, humans are heavily influenced by the actions of others.
• When attempting to influence others, social proof can be a highly effective tool. The opinion of "the many" can help change the mind of an individual, especially if the many are similar in some way to the individual.
• In the business world, managers can use the leverage of social proof by letting peers speak, rather than attempting to force their opinion from above.

The series:

• Part One: Liking
• Part Two: Reciprocity
• Part Three: Social Proof
• Part Four: Consistency
• Part Five: Authority
• Part Six: Scarcity