Presidential Column

Robert B. Cialdini and Jennifer L. Eberhardt on The 7 Principles of Influence

Jennifer L. Eberhardt and Robert B. Cialdini explore the power of influence and the importance of “shipping” psychological science to address real-world challenges.

Eberhardt and Cialdini spoke on February 4, 2022. Edited excerpts of their conversation follow.

See all columns by Jennifer L. Eberhardt

Jennifer L. Eberhardt

EBERHARDT: So many of us conduct research in the laboratory or, more recently, online. Talk about the importance of adding participant observation and field research to the suite of methodological approaches we use in the discipline. 

CIALDINI: When I was a relatively young researcher, I thought I saw myself moving away from examining the true sources of human behavior and relying instead on studies that my colleagues and I had done to refine the understandings of that behavior. We were passing information back and forth about how we had studied the behavior and increasingly moving away from the source of the behavior itself. I thought it was important to get back to what I call the “streets,” where the behavior occurs. To maintain the metaphor, I felt that I needed to step away from the “avenues” where I was working and get into the streets more often. We work in a very ordered and structured environment that doesn’t always keep us in touch with the raw goods of human behavior.  

So I did two things. One was to engage in a participant-observation project where I became integrated into a setting where the behavior of interest was unrolling naturally. Because I study social influence, I began to enroll, incognito, in the training programs of as many influence professions as I could get access to. I learned how to sell insurance, portrait photography, automobiles, and nutritional supplements. I joined these training programs to learn what worked well in each of these jobs to get people to comply with requests. I did the same within training programs for marketers, fundraisers, and recruiters. 

The plan was to take this information from the streets back to the traditional research avenues where I could unpack it in an ordered and logical way. That way, I could use the evidence of the streets to decide which influence practices were reliable and robust enough to warrant studying them, and to understand why they worked so well. 

EBERHARDT: Yes, I know you immersed yourself in these training programs for 3 years. How did you choose the different programs, and were there commonalities across them? 

CIALDINI: I just answered ads for trainees. Merchandisers were looking for salespeople, marketers, advertisers, recruiters, and so on. All I had to do was to enter their training programs to see what they said worked best and to look for the commonalities among the various professions. I expected that this was going to send me back to the laboratory to understand why those particular practices worked as effectively as they did. 

But something else arose. Midstream, I said to myself, “Wait a minute, there’s a book here. Surely people other than my fellow academics would be interested in knowing the principles of influence that work across the widest range of influence professions, practitioners, audiences, and settings.” That recognition is how my first book, Influence, emerged. It was an accurate recognition, as the book remains popular.  

EBERHARDT: It was 1984 when you published Influence: The Psychology of Persuasion. It’s sold over 5 million copies. Did you imagine the book would be that wildly popular? And you followed this up with a new and expanded version just last year. Why? 

CIALDINI: First of all, I wrote it for a nonacademic audience because it seemed to me that we researchers are partners in a contract with the citizenry who pay for the research we do. People pay for our research with their taxes and their donations to our universities, and they’re entitled to know what we‘ve found with their money. But, at the time, no social scientists were writing for nonacademic audiences. There’s a quote by the legal scholar James Boyle that I think explains why that was the case: “You have never heard true condescension until you have heard academics pronounce the word ‘popularizer.’” Fortunately, that has changed now. 

The reason I wrote a new version of Influence last year is that we’ve learned a lot more about the influence process. That new information deserved a place in the book, so I’ve added 120 pages. 

EBERHARDT: Wow! What are some of the takeaways? What principles, if you will, did you find across all these different settings and influencers that people really need to know about? 

CIALDINI: I now count seven universal principles. One is reciprocation: People give back to those who have first given to them. The second is liking, no surprise. People want to say yes to those they like, and there are two very simple things that professional influencers are trained to do to generate liking: (1) to identify genuine similarities, because we like those who are like us, and (2) to give genuine praise, because we like those who do like us and say so. This brings us to the third principle, social proof: People want to follow the lead of those around them, who are like them. Doing so reduces their uncertainty of what they should do in the situation.  

A fourth principle is authority. To reduce uncomfortable uncertainty, we don’t only look at what our peers are doing and recommending, we also look at what the authorities, the experts, are doing and recommending. Fifth is scarcity: We want more of the things we can have less of. Sixth is commitment and consistency: We want to be consistent with what we have already said or done.  

Finally, there’s a new principle that I call unity. We prefer to say yes to people who we consider one of us, who share a membership in a category that is related to our personal or social identity.  

EBERHARDT: Do you think the importance of those principles varies across time? In certain eras, are there certain principles that seem more important than others? 

CIALDINI: I would say certain principles are employed more than others at different times. Right now, the big one is social proof—the tendency to follow what your peers are doing. Because of the internet, we have access to information about all kinds of other people who have tried certain products or engaged in certain services or exposed themselves to certain ideas. We can see what they have said about those things, how they’ve rated them, and so on. I saw an article that said 97% of people who regularly buy products and services online first consult reviews. 97%? We can’t get 97% of the people in the world to believe the earth is round. But 97% will seek out social-proof-based information because it is so available. I would say social proof is now the dominant way that people are moved to change in a particular direction. 

EBERHARDT: You are fond of saying that influence professionals know what practices work in their own world, but they don’t always know why they work. And you see the job of discovering “why” as the job of behavioral scientists. But it seems to me that some professionals may not really care about discovering why. So I’m wondering, why should they care about the “why”? 

CIALDINI: I think it’s the difference between a cook and a chef. The cook only wants the recipe: Just tell me what to do here, and I’ll get it right. The chef thinks about combinations of ingredients, textures, and flavors that allow them to create new recipes, to develop new dishes. This is why the “why” is so important. It allows people to understand the building blocks that lead to good choices and to bring that understanding to novel situations. I think that a consideration of the whys of human behavior is one aspect of the book that has led to its popularity. People want that information—at least those who aspire to be chefs of influence. 

[Among influence professionals], unethical operators do sometimes win in the moment; but they undermine the quality of the relationship with the recipients of their requests. In the long term, that’s a
wrongheaded approach. The ethical person maintains the quality of the relationship so that the recipient of the appeal wants to continue to interact with that source of information.

— Robert B. Cialdini

EBERHARDT: Your work is not just about the power of influence but also the routes to ethical influence. What do you mean by ethical influence, and why has that been a central concern in your work? 

Robert B. Cialdini

CIALDINI: I think it’s very important that if we are going to reveal the secrets of influence professionals, we should talk about the consequences of being influential as ethical operators versus unethical operators. Unethical operators do sometimes win in the moment; but they undermine the quality of the relationship with the recipients of their requests. In the long term, that’s a wrongheaded approach. The ethical person maintains the quality of the relationship so that the recipient of the appeal wants to continue to interact with that source of information. The way that I define an ethical approach is in terms of the universal principles of influence. That is, is the principle we plan to use an inherent and common part of the influence situation? If so, as an influence agent, you are allowed to point to it. That way, you are informing your audience into assent, rather than fabricating or counterfeiting the presence of the principle. 

Let’s take, for example, the principle of authority. Providing evidence of true and representative authority recommendations on a choice strikes me as ethically commendable. Not only isn’t it objectionable to use the authority principle in this fashion, I think it’s admirable. We don’t simply move people in the right direction; in addition, we do so as educators. We’re not manipulating them, we’re enlightening them. And that seems to me to be the ethical route. 

EBERHARDT: Right. And it gives them more control and power to a certain extent.  

CIALDINI: That’s a bull’s-eye insight. 

EBERHARDT: You also have said you believe we’re living in a golden age of behavioral science. What do you feel brought us to this point? 

CIALDINI: Well, it’s interesting that Influence had very poor sales for the first 3 or 4 years, and then it moved into the best-seller list, where it’s stayed ever since. I think what changed was the times. That is, in the 1980s, the idea of evidence-based decision-making was gaining traction in all the major institutions of our society: government, business, fundraising, sports. Evidence-based decision-making became something that everybody who was an important decision-maker was expected to engage in. And scientifically derived findings were widely considered one trusted source of such evidence. The book Influence benefited because there was a lot of scientific evidence on the topic available in it.  

Jennifer, I am concerned that science’s validity is being eroded these days. A toxic fog of anti-science is rolling across the earth. People are choosing to decide based on what they prefer to believe, rather than what the evidence—as manifested in scientific research—has demonstrated to be true. I’m more than a little worried about this. Therefore, I think it is healthy that behavioral scientists are now speaking to the nonacademic community about their valuable science-based findings in all kinds of formats that didn’t always exist then, including blogs, podcasts, and popular-press behavioral science books. 

EBERHARDT: For sure. A longtime colleague, Lee Ross, was famous for saying that we need to get more of our science into the world and more of the world into our science. Throughout your career, you’ve managed to do both across many different areas of inquiry. Let’s talk about your long-standing interest in the environment. One of your most memorable series of studies for me in this area was where you encouraged people to reuse their towels in hotels. I wonder if you could walk us through the logic of that classic work. 

CIALDINI: Sure. I should take a step back and say that at about the midpoint in my career as a persuasion and influence researcher, I recognized that perhaps the biggest question for us to answer was how to influence people to take environmentally protective and promotive action. So I turned my research to that question. One of the things we looked at was the option in hotels to either reuse one’s towel or get a fresh one. I remember being in a hotel and seeing one of these cards asking me to reuse my towels. You’ve probably seen signs reading, “This space available for rent” or “This space available for lease”—well, I looked at that card and said to myself, “This space available for test.” What could we put on the card that would spur people into greater conformity with the pro-environmental choice?  

So my team, featuring Noah Goldstein and Vlad Griskevicius, started working on that question in hotel guestrooms. With the cooperation of the hotel’s manager, we were able to vary what such a card said and then to see how many people actually did reuse their towels, depending on the message. By far, the most powerful message used social proof. It conveyed that the majority of hotel visitors recycle their towels during their stay. We then did a follow-up study that elaborated on that and generated even more recycling by saying, “The majority of guests who’ve stayed in this room have recycled their towels.” So it wasn’t just most people, it was comparable others who were the most likely to spur conformity in their direction. 

EBERHARDT: And now it seems that reusing hotel towels is part of the culture. It’s become common. 

CIALDINI: What I liked about that research opportunity was that it was in a real-world situation—a field-research setting where naturally occurring human behavior takes place and where there was a behavioral measure of persuasive success that we could register.  

EBERHARDT: It’s classic and cool research for sure. You’ve also looked at the same kind of issue in households—how to reduce household energy consumption. Talk about how you managed that work, including partnering with the private sector in an effort to scale up your effects. 

The door hanger that said that your neighbors are conserving was clearly most effective. It reduced 350% more than the others. This showed the motivating power of social proof: what the people around me, like me, are doing.

— Robert B. Cialdini

CIALDINI: Yes, this was research conducted in the San Diego area and was led by my colleague Wes Schultz. We went to homes and attached door hangers with different messages as to why residents should reduce their consumption of energy. Of course, we had control groups, too. Some people didn’t get any message at all. Some people got a message that implored them to reduce energy but didn’t provide a reason. And others got one of four reasons for conserving energy. The first was the common theme of doing something for the environment. A second message was about social responsibility: Do it to benefit the society. A third message asked residents to conserve energy for their own economic benefit, to reduce their power bill. And the fourth one was a social proof message—essentially, that the majority of your neighbors do take daily steps to reduce their energy consumption. Participants got one or another of those door hangers every week for a month. 

We then looked at their power usage for that month. The door hanger that said that your neighbors are conserving was clearly most effective. It reduced energy consumption 350% more than the others. This showed the motivating power of social proof: what the people around me, like me, are doing. 

I was then approached by a pair of young entrepreneurs with a start-up company called Opower that planned to send energy-conservation messages to the customers of various utility companies. I worked with them for 3 years. We designed messages as well as a report that informed householders where they stood relative to their neighbors in energy conservation. Cumulatively, the results have been astounding. In the 10 years that Opower operated (they were later bought by Oracle), the reports saved 36 billion pounds of carbon dioxide from entering our environment. That’s a lot of consequence.  

I have to say that because I’m a social scientist, I never expected I’d get involved with the private sector. But I needed the private sector to escalate our findings to the societal level. My university couldn’t have scaled up our results to anything like what Opower did. The government wouldn’t succeed at that kind of escalation, either, because it’s hindered by political and administrative constraints. But Opower did it. There are now over 100 utility companies that send these reports to their customers, who are saving something like $750 million a year on their utility bills. 

As a discipline, we don’t always keep track of the impact our work has. And oftentimes we don’t even have the metrics for doing so. The metrics we typically use to gauge impact really have to more to do with impact on the discipline rather than the world. But your work reminds us that both are important.

— Jennifer L. Eberhardt

EBERHARDT: Wow. As a discipline, we don’t always keep track of the impact our work has. And oftentimes we don’t even have the metrics for doing so, like you did in this particular case. The metrics we typically use to gauge impact really have more to do with impact on the discipline rather than the world. But your work reminds us that both are important. As a discipline, I wonder if there are ways that we can start to think about metrics that help us to understand the effect our science is having on the world. 

CIALDINI: I think it’s incumbent on us, whenever possible, to choose to measure an activity that nonacademic individuals would have experience with in a naturally occurring situation. Such as whether to conserve household energy or to hang up towels or recycle trash. If those activities are in our studies from the outset, and we use true behavioral measures, then the results become perceived as much more valuable by the people we need to convince about the value of science in their lives. 

EBERHARDT: Let’s talk about COVID for a minute. I think many people were surprised at the degree of resistance to COVID vaccines once they were made available to the public. Were you surprised, and should we as behavioral scientists have anticipated this? 

CIALDINI: We should have anticipated it based on the influence principle of unity. What has happened is the politicization of what constitutes correct behavior. If you are in a particular political party or have a particular political stand, correct behavior is heavily influenced by what the leaders of that party are saying and what other party members are doing. So in terms of mitigating the problem of people not choosing to be vaccinated, I think we first have to segment the resisters. There are some who are resistant just because they’re uncertain of whether it is the right thing to do. In their case, we can show them evidence that fits with the latest research in persuasion. And that is the impact of trends. For example, showing resisters the increasing trend of those like them who are receiving the vaccination is much more effective than just giving them a number, like 67%. That’s a statistic. Showing people a trend leads them to think it will continue—in other words, to expect even greater social proof. So for resisters who are just uncertain, we can reduce their uncertainty by showing them that more and more people are moving in that direction.  

As for people who are strong resisters, you can’t give them any facts that they will incorporate into their decision-making. Here’s where I would use something called the convert communicator strategy. You give them examples in multiple testimonials from people who used to believe exactly what the strong resisters believe but have changed their minds because of something that happened inside their family or friendship network, or perhaps to them. It’s very hard to dismiss such people. They are not different from you; they are of you, and they have a piece of information that you don’t have. The convert communicator can puncture resistance through social comparison rather than facts. 

EBERHARDT: I wonder also about people in both groups who feel that they have the facts and are following the science. They are staunchly against vaccination, but they also claim that they have this scientific information that other people don’t know about. It seems like there’s almost a battle between mainstream science and messages that are masquerading as science. 

CIALDINI: I think we have to move to a playing field based on social comparison, where influence comes from whom you follow, not from the facts. So we have to move to the playing field where the facts aren’t relevant, but social comparison is—namely, “What are the people around me, like me, doing?” It’s not logical proof; it’s not empirical proof; it’s social proof, which is the only proof we can offer to persuade people who are not susceptible to facts.  

EBERHARDT: Yeah. Even with social proof, though, there are people in different pockets of the country who are saying that this doesn’t matter, this isn’t going to affect them, they don’t need to be vaccinated.  

CIALDINI: Right. So we can intervene with the message, “But look at the increasing trend of people who weren’t vaccinated who are now becoming vaccinated.” And with convert communicators, we can bring together the testimonials of people who used to believe what they believe and who provide a new, contrary point of view based on their own experiences. You’re right that there will continue to be pockets of resistance, but what we can do is talk about true trends and converts within those pockets. 

EBERHARDT: That makes sense. So, given that we’re living through this golden age of behavioral science, were you surprised that the government didn’t turn more to behavioral scientists to involve us in their COVID mitigation strategies? Were you consulted by officials on what could and should be done around this? 

CIALDINI: There were some opportunities that I engaged in and offered ideas. As well, a lot of other prominent behavioral scientists sent messages to the government about what research indicates is likely to be effective. But politicians listen to political voices, including advisors and campaign personnel who aren’t trained in behavioral science. They’re trained in a different kind of discipline, in politics and public administration.  

EBERHARDT: Do you feel there’s more understanding now of the importance of behavioral science as a critical part of health policy and strategy? 

CIALDINI: Yes. I’ve seen that recognition grow over the last decade or decade and a half. But again, I’m worried that there is this counterforce now toward anti-science that is undercutting those gains. 

EBERHARDT: And how do you deal with that counterforce? 

CIALDINI:  I think we have to go back to the issue of how we, as researchers, gain the confidence and trust of the people who might not be compelled by science. We should do our research in settings and with measures that show them the value of science in the places where they live—in the experiences that they have on a daily basis. If we can honestly say to them, “Look what we’ve found that you can use to enhance your life,” we’d increase the odds of bringing them onto the side of science. 

EBERHARDT: What’s next for you? Do you have any new, exciting major projects on the horizon? 

CIALDINI: Well, I’m retired, so I don’t have the same ability to do research. But I think I want to write another book that comes from the stories that people have shared with me about everyday occurrences in which they witnessed the influence process operating to a remarkable degree. I will try to analyze each story in terms of the psychological dynamics that would produce these notable effects. The working title, in fact, is Incidents of Influence. Evidence from Life

EBERHARDT: I like that. Thanks so much for taking the time to speak to the APS membership. We really appreciate all that you do, including taking our field in new directions and addressing some of the world’s biggest challenges. I know you’re famous for saying “if psychological science were a business, we’d be known for having great research and development units, but no shipping department.” But I feel like because of the trail you’ve blazed, that’s all changing. We’re developing a shipping department to get the wares and the goods out to the people who really need it.  

CIALDINI: I enjoyed this.

 This article was initially published in the print edition of the March/April 2022 Observer under the title, “The 7 Universal Principles of Influence.”

See all columns by Jennifer L. Eberhardt


The idea of prospecting for evidence, arguments, tactics, and anything else that moved an antivaccination person to get their shots seems like a great idea. We need to search where their is new knowledge to be found. Find people who have recently gotten their first shot and ask them what made them change their minds. They are all around us. The answers will be vary be different depending on a host of factors. We need to discover what those factors are. We need to get away from theories and our labs and gather information, as the authors tell us to do.

Thanks to both of you for this fascinating interview.

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