Persuasion: Part 1

We all exert pressure on each other in ways small and profound. We recommend movies or books to a friend. We convince a colleague to take a different tactic at work. We lobby a neighbor to vote for our favored political candidate. This week, we launch the first of a two-part mini-series on the science of influence, and talk with psychologist Robert Cialdini about how we can all improve our techniques for persuading others.

Trying to make a big decision or fulfill a personal goal in the year to come? Don’t miss our recent episode about how to figure out what you want in life. 

Additional Resources

Book:

Influence, New and Expanded: The Psychology of Persuasion, by Robert Cialdini, 2021. 

Pre-Suasion: A Revolutionary Way to Influence and Persuade, by Robert Cialdini, 2016.

Research:

Celebrity Opinion Influences Public Acceptance of Human Evolution, by Steve Arnocky et al., Evolutionary Psychology, 2018.

I Am What I Am, by Looking Past the Present: The Influence of Biospheric Values and Past Behavior on Environmental Self-Identity, by Ellen van der Werff, Linda Steg, Kees Keizer, Environment and Behavior, 2014.

Social Norms and Energy Conservation, by Hunt Allcott, Journal of Public Economics 2011. 

Observational Learning: Evidence from a Randomized Natural Field Experiment, by Hongbin Cai, Yuyu Chen, Hanming Fang, American Economic Review, 2009.

Increasing the Attractiveness of College Cafeteria Food: A Reactance Theory Perspective, by Stephen G. West, Journal of Applied Psychology, 1975.

The transcript below may be for an earlier version of this episode. Our transcripts are provided by various partners and may contain errors or deviate slightly from the audio.

Shankar Vedantam:

This is Hidden Brain. I'm Shankar Vedantam. From high school corridors to the corridors of power, human beings are always trying to influence one another. We try to convince others to like the books and music we love. We want colleagues to follow our suggestions on changes at work. We lobby friends and family to support the political parties we endorse. But have you ever noticed some people are more effective at persuasion than others? They convince others to go along with their ideas, to agree with them. These people are better at sales, better at winning elections, maybe even better at scoring dates. What explains this? Charisma? Charm? Good looks? Today, we launched the first of a two-part miniseries that examines the science of influence. Insights from the world of persuasion this week on Hidden Brain.

Robert Cialdini grew up in Milwaukee in the 1950s. From an early age, he was an observer of human nature.

Robert Cialdini:

I grew up in an entirely Italian family, in a predominantly Polish neighborhood, in a historically German city, in an otherwise rural state. And what happened to me in my thinking fairly early on was to recognize the norms associated with each of those subcultures was different enough to make it more likely that somebody would say yes to you if you understood what those norms and factors were that described how people were to behave in each of those situations.

Shankar Vedantam:

What were family dinners like at your dining table and at the dining table of your Polish friends?

Robert Cialdini:

Very different. So that in an Italian home, it was not uncommon at all for us to have arguments at the table, for us to disagree and to speak with our hands about it, and for one person to challenge another. When I went to have dinner with one of my playmates, no, it was much more organized, much more genteel, and people accorded each other, a kind of grace that we didn't in my family. I remember noticing that, "Oh, I have to be different here."

Shankar Vedantam:

Bob noticed that in his own family, he was more likely to get something he wanted when he demanded it. But if he was interacting with strangers or acquaintances, he needed a different approach.

Robert Cialdini:

By the time I was an adolescent, I recognized if I drove out of the city and let's say I wanted to buy some apples by somebody, a farmer at the side of the road with a stand, the interaction that I would have with that farmer had to be preceded by some sort of sociable exchange. We had to be connected in a way. Maybe I would talk about the score of the last baseball game, and then I would get better prices. In this rural communal environment, it was important to establish a commonality and a sense of shared membership in this category.

Shankar Vedantam:

When Bob went off to college, he continued to observe people. He noticed some people had a knack for getting others to go along with them. He didn't have theories that connected all these observations, but he could just see that some ways of talking were simply more effective than others.

Robert Cialdini:

I would say that all my life, I was a patsy. I was an easy mark for the pitches of salespeople, fundraisers who would come to my door and so on. But I don't remember them as frauds, I remember them as individuals who were able to move me to change my choices based on what they were providing in terms of information or enticements.

Shankar Vedantam:

One day in college, Bob was in his dorm room when there was a knock at the door.

Robert Cialdini:

So it was somebody selling subscriptions to magazines. And I was a student, I didn't have a lot of money, but I was a sports fan and he offered me a subscription to Sports Illustrated, and I was going to say no because I didn't have the funds, really. And he said, "It's the most popular subscription here in your dorm, and the experts rate it as the number one sports magazine in the United States." And I found myself buying that subscription. I didn't want it, but he had arranged for me to choose something I didn't want because of what he said to me.

Shankar Vedantam:

And did you ponder afterwards what he had said? Did you ask yourself afterwards, "What exactly happened in that conversation to get him to change my mind"? Did that question go through your head?

Robert Cialdini:

It did, but I don't know I had the terms to explain it, but I knew that they had worked and I knew that he had turned a no to a yes. So there was something powerful there inside what he had said.

Shankar Vedantam:

Bob wanted to discover what that power was. It was clear that lots of things didn't work to persuade others. Some things simply turned people into brick walls. You got a lot of "no"s and you got them fast. But other approaches seem to work like magic, it was like a key turning in a lock. As Bob embarked on his career in psychology, he decided he wanted to understand how those locks and keys really worked.

You're listening to Hidden Brain. I'm Shankar Vedantam.

This is Hidden Brain. I'm Shankar Vedantam. There are different ways to be a psychologist. You can run experiments in a lab or survey people on the street. But as Bob Cialdini set out to discover the keys to influence and persuasion, he decided to follow the instincts of his childhood. He decided the best way to understand how influence worked was to closely observe people who were very successful at influencing others.

Robert Cialdini:

I decided to determine what were the most powerful effects on the influence process by studying the practitioners whose economic livelihood depends on the strength of the strategies they employ and the effects that they produce.

Shankar Vedantam:

Someone telling you about how influence worked didn't have skin in the game, but if you were a salesperson whose effectiveness as an influencer determined how much you got paid, maybe even whether you got paid, you had to quickly learn what worked and what didn't work.

Robert Cialdini:

I answered ads in the newspaper for trainees, so I learned how to sell nutritional supplements door-to-door, I learned how to sell automobiles from a lot. Wherever people were asking for recruits for their organization, I would answer the ad and I would do so incognito -- disguised identity, disguised intent. I worked undercover to learn what they had learned were the most powerful influences on the influence process. And I did so not just in sales, I also looked at fundraising, I looked at recruiting and procurement, these kinds of jobs where your responsibility is to influence the situation for the best possible outcomes. And I tried to look for commonalities across these various professions. Which were the approaches, tactics, principles that were employed in common? Because that would tell me which were the most likely to be features of the human condition. And what shocked me was how small the footprint was of those principles that were in common across all of those settings and professions. I only counted six.

Shankar Vedantam:

I understand that at one point you actually learned how to sell portrait photography. Tell me about that experience. What was that like? What did you learn about what they did?

Robert Cialdini:

So first of all, we would sell on the phone, but we also had certain kinds of experiences in retail establishments. You go to a Walmart or a Target and so on, and there will be a booth of people selling portrait photography for your family. And you could get these photographs and then there were a number of options that you had for how many photographs of what size and so on, and you could get different sets, and of course they varied by price. And what we were told to do when a family would only chose to purchase a small number of these photographs, they told us to say this to the family: "Well, because of stocking constraints, we'll be only able to keep the pictures of your children for one week. After that, we'll be forced to burn the pictures of your children."

You could see the look on the faces of the parents, "Well, you're going to burn the images of my children?" So it was essentially something that appealed to the idea of scarcity. This is going to be gone, it's going to be gone within seven days unless you choose to curtail that loss.

Shankar Vedantam:

After about two and a half years, Bob started analyzing the data he had collected. At his lab at Arizona State University, he used experimental methods to study the practices of the salespeople he had observed. Several patterns emerged, techniques of persuasion that almost every influence professional used. The first technique was the one used by those portrait photography salespeople.

Robert Cialdini:

People want more of what they can have less of. What we mean by scarcity is entities or opportunities that are unique, are uncommon or are dwindling in availability. When that's the case, we want those things more because of the desire to have those things that we are missing, that we will forego unless we seize them. I'm convinced that a major factor that lends itself to the power of scarcity is loss aversion. Loss is the ultimate form of scarcity. If you can't have it, it's gone. So because of loss aversion, which I think is deeply installed in us, things that are scarce, that are dwindling in availability that we will otherwise forego or miss, become very attractive.

Shankar Vedantam:

I was trying to book an airline ticket the other day and I put in my dates and I was just scouting around to try and see if I wanted to make the trip. But when I put in my dates, the website told me that tickets were available and this was the price, but they had a little line in italics at the bottom saying, "Only two seats available at this price." Is that scarcity?

Robert Cialdini:

That is. It says dwindling availability, you are risking the loss of this price. There's a company called Booking.com that does reservations for hotels and flights around it, and they were using my principles and they hit upon this particular tactic where you'll look at a hotel room online, it will be a certain price, and they will say two things. They'll say, "Only two of these left at this price," and "There are five people looking at this room right now." It's competition for scarce resources.

The first time they did that, their marketing people sent a message to the technology people and said, "There's something wrong because we're getting flooded with so many purchases. There's something wrong with our system." And the technology people said, "No, there's nothing wrong with the system, it's what you said that caused people to leap to avoid missing out on this favorable opportunity."

Shankar Vedantam:

One insight Bob had as he studied the science of persuasion and influence was that effective techniques were often effective even when you knew exactly how they worked and why they affected you. Bob eventually became one of the world's foremost experts on the science of influence. But he still found himself susceptible to the techniques he studied, like the time he read an announcement about a local Mormon temple.

Robert Cialdini:

So I live in the Phoenix, Arizona area. There's a suburb called Mesa, and there's a very impressive Mormon temple in the center of Mesa where non-members are not allowed to visit a certain section of the temple that is exclusive to members. Except in the first few weeks after a temple is constructed, then anyone is allowed to see all of it or after a significant enough renovation that the temple is seen to be a new one. And I remember reading an account that the Mormon temple in Mesa was now going to be available for me to visit, even that sacrosanct area that is normally exclusive to members. And I remember calling a colleague of mine and saying, "Gus, it's available. How about if we go over there?" And he said, "Bob, what is it about the Mormon temple? Are you especially interested in church architecture? You're especially interested in the Mormons?" I said, "No, none of those. It's because I can't have it. If I don't go now, I'll never be able to hand it."

And it occurred to me then, what I've just seen is the effect of scarcity on my choices that was independent of the merits of what I was getting. I didn't care about what was in that sector, I only cared that I couldn't get there before and now I can. Crystallized scarcity.

Shankar Vedantam:

We can all think of ways we respond to scarcity in our own lives. There are also ways to experimentally measure this phenomenon. At Florida State University, students were asked to rate the quality of cafeteria food. Some time later, they were asked to do it again. The second evaluations were far more glowing than the first. Why?

Robert Cialdini:

There was no difference in the merits of the food, they didn't buy more high quality food or hire a new chef. It was that because of a fire, they weren't allowed in the cafeteria for the next two weeks. And so, now what they couldn't have became more valuable in terms of its appeal.

Shankar Vedantam:

As we will explore in different ways in this episode and the next, there are ways to use techniques of influence ethically and ways to use these techniques unethically. One domain where influencers regularly use scarcity is in sales and marketing. Bob says there is a way to do this right, and a way to do it wrong.

Robert Cialdini:

Well, I was in an appliance store and I wasn't looking for a television set, but I saw one at a sale price and I knew that this set was highly rated in Consumer Reports. And so I was standing in front of it, there was a brochure on the counter, I was looking through the brochure and the salesperson approached. He said, "I see you're interested in this set at this price. I can see why. This is a great deal, but I have to tell you, it's our last one." And then he said, "I just got a call from a woman who said she might come by this afternoon to buy it." Shankar, I'm supposed to be the guru of influence. Twenty minutes later, I'm wheeling out of the shop with that set in my cart. And it occurred to me that there was something crucial about the ethics of that man's assertion.

If he was right, I wanted him to give me scarcity information. I wanted that information to help me decide what to do. If he hadn't done that and I went home to think it over and then came back the next day and it was gone, I would've said to him, "What? You didn't tell me it was the last one, what's wrong with you, man?" That's information I want to have in order to make a good decision, right? So if however, that was a artifice, that was a device he was using because in fact, there are retail outlets that have been indicted for using that strategy. They train their salespeople to say, "This is the last one." There are plenty in the back room, and then they just go and fill that spot with a new one. So I went back the next morning after I had purchased this, was there an empty spot on the shelf? There was. He was honest.

What I did was to go back to my office and write a very positive review of that store and that salesperson. If there had been another one on that shelf and I had seen that it was a trick, I would've written a very poor review of that shop because I think it's very important for us to penalize the people who use these strategies dishonestly, who reduce their predictive value, their diagnostic value in our choices. We have to penalize those people who deceive us by using one or another of the principles of influence. And we have to commend, we have to praise, those people who do so honestly.

Shankar Vedantam:

All of us have also seen the power of a second form of influence. When someone gives you a gift for your birthday, you feel like giving them a gift when their birthday rolls around. If you get invited to a friend's home for dinner, it's only a matter of time before you invite them over to your place. When we obtain favors, we feel the need to return favors.

Robert Cialdini:

It's the rule in every human society that says, we are obligated to give back to others who have first given to us. We say yes to those we owe. The reason that's the case in every human society is, first of all, that we have very nasty names for people who don't play by that rule, who take without giving in return. In English, we call them moochers or takers or ingrates or teenagers, actually. Nobody wants to be labeled like that. So we go to great lengths to be sure that we are seen as someone who pays our debts, who gives back to those who give to us. It's not what we have received, it's that we have received that spurs us into action.

I mean, I had a similar situation a while ago when I was approached by a Boy Scout on a city street. He wanted me to buy a couple of his tickets to the Boy Scout Circus that Saturday, and I declined. They were $5 a piece in those days. I declined. And he said, "Oh, well, if you can't do that, would you want to buy a couple of our chocolate bars here? They're only $1 a piece." And I bought his chocolate bars and I realized that something important had happened because I don't like chocolate bars, but I like dollars. And he was walking away with two of my dollars and I was standing there with two of his chocolate bars.

So what happened there was a different form of reciprocation. It was a reciprocation of concessions, which also plays a big role in human culture. If I make a concession to you, there's an obligation to meet me and make a concession in return in any kind of an exchange. And so, that's what the Boy Scout did. He made a concession from $5 a piece to $1, and I said yes, and it didn't matter that I didn't want what he was offering for $1. I wanted to be true to the rule.

Shankar Vedantam:

So this technique is sometimes called rejection and then retreat. Unpack that for me, Bob, what's happening here?

Robert Cialdini:

So the strategy is to ask for a large enough favor that people will most likely say no to it, and then the influence agent retreats to a smaller favor, and the subject of this appeal feels the need to say, "Okay, you made a concession, I'll make a concession in return." This happens all the time in labor negotiations, for example, where people start with very large requests and then they make concessions. And what the other side is expected to do is make some sort of concession in return.

Shankar Vedantam:

In one study, Dennis Regan at Stanford University ran an experiment similar to what happened with Bob and the Boy Scouts. He brought volunteers into the lab and asked them to rate various paintings. In reality, the paintings were not the point of the experiment.

Robert Cialdini:

It was a lovely study. And about halfway through he said, "Okay, it's time for a break." In truth, one of the subjects was a confederate of the experiment. This person said, "Do you mind if I leave the room?" Researcher said, "No, that's fine." The confederate left and came back with two bottles of Coca-Cola, one for himself, one for the other subject. He said, "I was thirsty. I got myself a Coke. I thought you might like one as well." Then the experiment begins again, and at the end, the experimenter leaves the room to go get some materials. And the confederate says to the subject, "I wonder if you could do me a favor, I'm selling raffle tickets and the more I sell, the greater I will be able to get in return and you could win whatever the prize was, I don't remember, let's say it was a big screen TV."

And what Regan did was to look at how many raffle tickets people bought. Those who didn't get a Coke, there was a control condition where the confederate left the room [and] just returned with nothing, and the experiment began. Bought half as many tickets as those who got the Coca-Cola. Those who received the favor were now going to return the favor by buying twice as many of the man's raffle tickets in reciprocation.

Shankar Vedantam:

What's also striking is I think, Bob, it's not labeled explicitly as an exchange, and I think that's partly what makes it actually so complicated. So if you are selling a $5 book and I give you $5 and you give me the $5 book, we've made an exchange, it's a transaction. You've given me something that's worth $5, I've given you $5, we come out equal. But I think there's something that's happening here that's not at the level of transaction, because a can of Coke might not be the same as the cost of two raffle tickets. There's something that happens in these interactions that goes beyond, if you will, the world of transaction.

Robert Cialdini:

You're not paying for the item, you're paying for relieving the pain of violating the rule that's been inculcated in you from childhood, how you think of yourself as a citizen of the culture.

Shankar Vedantam:

A third important form of influence is something that we have touched on before, and it's the idea of liking. Tell us about this idea. What is the role of liking in influence?

Robert Cialdini:

This wouldn't come to it as a surprise to anyone that we prefer to say yes to the people we like. What's surprising is, what small techniques can be employed to produce that rapport. And there are two that the research literature highlights. One is similarity, pointing to commonalities. We like people who are like us. If somebody can show us that we're similar, we like that person. There's a greater sense of rapport and we're more willing to interact with and benefit and partner with that person. The other is praise. And once again, the research is clear, not only do we like those who are like us, we like those who do like us and say so.

Shankar Vedantam:

It's so interesting. This is actually something that you learned when you were working with the portrait photographers all those years ago, which is you were taught when people came up, tell them that their children are beautiful, tell them that their children are well-behaved. Praise them, compliment them, show them that you like them. In some ways, it's exactly the same idea.

Robert Cialdini:

It is. That's what the professionals all recognized, not by understanding the literature in behavioral science, but by recognizing what worked. Through trial and error, they found the approaches, the tactics, the practices that lent themselves to good outcomes. And so, they were the ones that they trained into their trainees.

Shankar Vedantam:

One area where it's very useful to be able to offer praise and compliments is when you are the bearer of bad news. We all have a tendency to shoot messengers who bring us bad news unless those messengers show up with an armful of flowers. That's what once happened to Bob. He had written a book that ran into a major printing error.

Robert Cialdini:

The first 5,000 copies had errors in the pagination was off, and some of the pages, the print was lighter than the other pages. And my editor called me and said, "I've got some bad news about this 5,000 copies." These were the ones that went to the key bookstores, to the reviewers that we most wanted to write positive things about the book. And he said, "I'm sorry about this. I hate it when things like that happen to good guys like you." So he gave me a compliment of being a good guy. And here's the addition to that compliment. It was a compliment that provided me with a reputation to live up to.

And what I heard myself say to him was, "Oh, Ben, it's okay. These things happen. We're all human." Instead of pounding my hand on the desk and saying, "Recall those 5,000 books, Reese." No, I became the good guy. I became the good guy that he assigned to me. It's a great strategy for optimizing compliments. If you would like people to perform more of something that you find admirable, let's say you have a colleague who comes to the meetings that you hold on time most of the time or comes very well-prepared most of the time, compliment that person on that and you will see more of it because you've given that person a reputation to live up to.

Shankar Vedantam:

You can use the influence technique of liking to get people to endorse various things. In one experiment, researchers used the technique to get people to support an important scientific idea: Charles Darwin's theory of evolution. The volunteers were told about a book on evolution.

Robert Cialdini:

And they were told that an esteemed biologist at a prestigious university had written a positive comment about the book. That had no effect on these people's belief in the wisdom of evolutionary thought. What if they were told that George Clooney wrote a positive comment? It had a significant impact on their belief in evolutionary. Why did the researchers choose George Clooney? They asked people to rate a whole range of celebrities, and the one who was most likable at the time, the one that was most liked, was Clooney. And they just associated Clooney's favorability to evolutionary thought, and people came along.

I'm blanking on who said this, but the quote was, "You will never reason a man out of a position he wasn't reasoned into in the first place." And that's what we try to do very often as science communicators, we try to reason people into change on dimensions that were not about rationality, they were about belief or affect or something other than cogitation. And we make the mistake too often in the world of scholarship to use what we think is powerful to change people who didn't get there by virtue of facts or reason.

Shankar Vedantam:

It's useful to think of these strategies for persuasion in the context of battles to convince people around the world about the benefits of vaccinations and other public health campaigns. So often, scientists resort to making arguments to convince people. Have you noticed how none of Bob Cialdini's techniques for persuasion involve hammering at your opponents using PowerPoint decks, op-ed articles or peer-reviewed papers?

When we come back, how these techniques of influence can be used for good and for evil. You're listening to Hidden Brain. I'm Shankar Vedantam.

This is Hidden Brain. I'm Shankar Vedantam. Psychologist Bob Cialdini has spent decades studying the science of influence. His book, Influence: The Psychology of Persuasion, lays out several techniques that he learned undercover while attending trainings for salespeople, fundraisers, and recruiters. So far, we've looked at three of them. We are influenced by the people we like, by our desire to reciprocate favors, and by the experience of scarcity. Like all techniques involving psychological influence, these techniques can be used for good, and they can be used for evil. In the hands of a demagogue, they can lead nations astray. But used wisely, they can help us wrestle with some of our most difficult challenges. Take this application of the technique of scarcity.

Robert Cialdini:

Well, let's take the problem of climate change. Not just what do we stand to gain if we move in that direction. What do we stand to lose as a culture, as a species? What do we stand to lose? That's one thing we can emphasize honestly, because what we stand to lose is truly important. Unless we act in a certain way soon, we will have some things that are not retrievable. We just can't get back from them. They will be lost.

Shankar Vedantam:

So I mean, I've seen that the bumper sticker that I'm sure you've seen, which says there is no planet B. And in many ways that's the same idea here, which is if we are saying that if we lose this very valuable and precious thing we have, there is no replacement, there's no substitute.

Robert Cialdini:

Right. Exactly.

Shankar Vedantam:

Using the technique of scarcity might help us push public policy in a positive direction. We need to take care of this one precious earth, so we'll recycle or aim to cut carbon emissions. But just as easily, scarcity can be used for questionable ends. For example, Bob once knew a man who used the principle of scarcity to sell used cars.

Robert Cialdini:

Here's what he would do. He would buy a car from ads in the newspaper one weekend, add nothing but soap and water, advertise it for the following weekend, and sell it at a much larger price. Let's say three people would call to come and see the car that afternoon. Instead of doing what I would've done, schedule the first for 1:00, the second for 2:00 and third for 3:00, he would schedule them all for the same time.

And the first person would come usually a few minutes early and start doing normal car buying behavior, kicking the tires, pointing out rust spots and dents and so on, and maybe even beginning to negotiate on the price, when the second person arrived. And it changed the situation psychologically completely. This car was now a resource that the two of them were competing against one another for. He would say to the second person, "This gentleman was here before you, so would you please stand on the other side of the driveway until he's finished considering this." And so the first person recognizes there's this lurking newcomer over there on the side of them, and he gets anxious.

And now the third person arrives, and the first person does one of two things: buys the car immediately or just can't take all this tension, he just abruptly leaves. At which time the second person pounces, because there's a lurking newcomer waiting for him or her to decide.

Shankar Vedantam:

Is it always wrong to communicate a feeling of scarcity? This is where things get tricky. Think back to the TV that Bob purchased after he was told it was the last one available. If the salesman had not communicated that information and another customer had snapped up the TV, Bob would've been furious with the salesman. This feels very different than a used car salesman who generates an artificial feeling of scarcity in order to manipulate buyers into making a hasty decision.

One rule of thumb Bob uses to decide whether the application of an influence technique is ethical or unethical is to ask whether the influencer is calling attention to something real or making up something false in a given situation. If you told your boss you had a competing job offer in order to secure a raise and you actually had a competing job offer, your inducement of scarcity in the mind of your boss would be entirely ethical. But if you told your boss you had a competing job offer and you were bluffing, that would be unethical. The same goes for personal relationships. If you are unhappy in a relationship and communicate to a partner that you are thinking of leaving, that would be appropriate. But deliberately playing hard to get or threatening to leave just to induce a feeling of scarcity and worry?

Robert Cialdini:

If that's all it is, if it's not genuine, then it is a form of manipulation. So I would agree with you that this is ethically objectionable.

Shankar Vedantam:

Another ethical landmine has to do with the second technique we talked about, the norm of reciprocity. One time in the early 1980s, Bob was traveling through an airport when he noticed members of a religious group greeting passengers.

Robert Cialdini:

They would walk up to people and press a flower into their hands, a passenger in the airport somewhere, and they wouldn't take it back. And they say, "No, no, no. That is our gift to you. However, if you would like to give a gift to us for the good works of our society, that would be greatly appreciated." And I remember watching them operate like this and people, they weren't able to simply walk away with the flower, they felt a need to give back because they had received. The interesting thing was if I followed them, I would see that the first waste container they came to, they would throw the flower with force into the garbage because they didn't want it. They wanted to be released from violation of the rule for reciprocity. That's what they paid for.

Shankar Vedantam:

But when you think about, for example, the use of gifts in lobbying, for example, I live in Washington, D.C. and I'm just not a short distance from K Street, the home of most of the lobbyists in the country, and they give gifts to various people, they take people out to lunch, they take them on trips. And of course, these are often no-strings-attached lunches or no-strings-attached trips. But as you point out, there are always strings attached, even if there are no strings attached.

Robert Cialdini:

And the research supports what you just said, and that is those individuals, for example, physicians who've been given gifts by pharmaceutical representatives, those politicians who've been given gifts by lobbyists act in ways to favor the benefactor.

Shankar Vedantam:

But Bob says the very same rule of reciprocity can also be used in an entirely ethical way to spur people to take action against a real danger. Again, take the example of climate change.

Robert Cialdini:

I've been impressed by how the evangelical community has been moved to protecting the environment by the message that you have been gifted this planet by God. It is your job as stewards of the environment to protect what you have received. Well, that's the only thing I know that has been as so successful in turning people who are evangelical and have not supported climate change to give them the sense that they are indebted. It's their turn now to take care of this gift that they've received.

Shankar Vedantam:

Bob told me there are plenty of opportunities for us to ethically apply the science of influence, but they demand that we become careful observers of the world. Many situations contain elements that can be usefully adapted to leverage the power of influence. In his own life, Bob once got a chance to ethically apply the influence technique of liking to fix a longstanding problem.

Robert Cialdini:

My home newspaper delivery person, Carl, his name is, he drives by my house every morning and throws my newspaper out onto my driveway. And most of the time, I would say 70% of the time, he gets it in the middle of the driveway so it doesn't get wet from my watering systems on each side that will go on early in the morning. Well, 30% of the time I have a wet newspaper. So I thought, "What could I do here?" And every holiday season, in one of my newspapers, there's an envelope addressed to Carl and it's for me to put a tip in, send him a check. So I always do. But this past year, I had a little post-it note on the check and I said, "Thank you, Carl, for your conscientiousness in getting my newspaper in the center of the driveway so it doesn't get wet." It used to be 70%, it's now 90% of the time [that] it's in the center of the driveway. He lived up to the reputation to the compliment I gave him. So it's fairly easy to do.

Shankar Vedantam:

In next week's episode, we return with more ideas about persuasion and more complex dilemmas involving the ethical and unethical users of these techniques. I hope you will join us for that show.

Hidden Brain is produced by Hidden Brain Media. Our audio production team includes Brigid McCarthy, Annie Murphy-Paul, Kristin Wong, Laura Kwerel, Ryan Katz, Autumn Barnes, and Andrew Chadwick. Tara Boyle is our executive producer. I'm Hidden Brain's executive editor.

Our unsung hero today is listener and Hidden Brain supporter Sandro Meucci. Sandro says that one of his favorite episodes of the show is Watch Your Mouth, which is a look at language and how it shapes the way we see the world. Sandro says, "I'm Italian, and since 2015 I live in the Netherlands and still struggle learning Dutch. So it was very inspiring and refreshing hearing that learning a new language is not only taking up a vocabulary, but also a new mindset." Wishing you lots of luck with your Dutch classes, Sandro, and thanks very much for supporting the show.

If you found this episode thought-provoking and you would like to join Sandro in helping us to make more episodes like this, please do your part to keep us thriving. Visit support.hiddenbrain.org. Again, that's support.hiddenbrain.org. I'm Shankar Vedantam. See you soon.


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