“These two words increased sales by 18%.” Robert Cialdini

16 years ago, the managers of a chain of restaurants in Beijing wanted to do something that most people thought impossible. The managers at May Jo Dong Po, a popular restaurant with 13 locations across Beijing, wanted to increase the amount each customer spent. The restaurant was mostly full of customers, but spend per customer wasn't as high as some comparable chains. Now, if you were advising this chain, you might tell them to increase the price. That's the obvious way to increase revenue per customer. Perhaps you'd tell them to use more expensive ingredients as well, or to hire better chef or redesign the interior. But May Jo Dong Po's managers didn't want to do that. In fact, they didn't want to spend any money at all. So, they teamed up with three researchers from Peaking University, who helped set up an experiment. They randomized tables into three conditions. The first was the control. Nothing about these tables was changed. The second was called the ranking treatment. On these tables, there was a small placard that displayed the names of five of the most popular dishes from the previous week. The third group of tables was called the salient treatment. On these tables, they also had a placard displaying the five most popular dishes, but didn't name them as most popular. They said these are five dishes you should try. The outcome was pretty remarkable for the ranking treatment, where the placard displayed the five most popular dishes, and titled it as so, sales of each dish jumped by 13 to 18%. Robert Chaldeini in his book Influence writes how, quite simply, the dishes became more popular because of their popularity. Notably, the increase occurred for a persuasive practice that was costless, completely ethical, because the items were indeed the most popular, and easy to implement, and yet never before employed by the managers. I read the full paper that cited in Chaldeini's book, and I found that the researchers surveyed the customers after their meal, and they found that those who were told they'd eaten the most popular dish, and ordered it in eight. Well, they rated those dishes, and their overall experience, 8 to 9% higher than those who ate the same dishes, but didn't learn that they were the most popular. And in restaurants, where the most popular dishes were also the most expensive, the total revenue per customer went up as well. Today's guest on Nudge explains why this happens. When people are uncertain of what to do in a situation, they don't look inside themselves for the answer, because all they see is that uncertainty, that ambiguity. What should I do here? They don't go there. They go outside themselves. And one place they look is the behavior of peers. That's the Godfather of Influence Robert Chaldeini, and today we're covering Social Proof. Many of you in marketing will know that moment when the strategy is sorted, the brief is done, everyone's nodding along, and then you realise someone actually has to make all of the content you've agreed on. And usually that someone is you, and usually it is needed by tomorrow. Now, fortunately, there is software to help. Breez Assistant lives inside HubSpot. It drafts campaign copy, blog post emails all in your brand's tone of voice, and it's all grounded in actual customer data. With Breez Assistant, you don't just create content, you create content that converts. Check out HubSpot.com, the agentic customer platform for growing businesses. Robert Chaldeini wrote the best-selling book, Influence, which I should mention at this point has sold over 5 million copies, and by the end of today's episode you'll know exactly why he makes that very clear and why I make that clear in the start of this episode. Anyway, in Influence, Chaldeini writes that the principle of Social Proof states that we determine what is correct by finding out what other people think is correct. Importantly, the principle applies to the way we decide what constitutes correct behavior. We view an action as correct in a given situation to de-degree that we see others performing it. What are those around me like me choosing to do in this situation? And if I follow that, I'll usually be right. Like Chaldeini's other principles of persuasion, Social Proof is an evolution retreat. We have evolved to follow the actions of others. As hunter-gatherers, we'd eat the berries that those around us ate. As cavemen, we'd avoid setting up cave in a cave that a bunch of other cavemen have just run out of. And as modern-day consumers, we listen to chart-topping songs, read best-selling books, and seek out the most-bought stocks. As you say, if everybody's running out of the cave in a particular direction, that probably means there's something bad in that cave. Or it's time to move because there are circumstances that require it. So you see examples of it all around in the way that organizations give you evidence. On the original McDonald Shop signs, they'd proudly declare how 50 million burgers had been sold. Netflix today will highlight their trending TV shows and movies. And Slack on their website proudly declare that 80% of the Fortune 100 use their app every day. Amazon is a good example. They have on their site. After you've made a purchase or you're looking to make a purchase, they'll have a section that says, "Consumers like you have purchased this." Consumers like you. There's a very specific reason. Amazon uses that exact phrase. We'll cover wine a bit, but it's not the only tactic they use. Or they have a list of products that are trending near you. So it's a combination of what a lot of people are doing and people like you who are in the same region and so on. Social proof works for Amazon, Slack, Netflix and McDonald's because it is a deeply embedded part of human psychology. Chaldeenie writes, "How studies have shown," for example, "students worried about their academic performance or about their ability to fit in in school improved significantly when informed that many students like them had the same concerns and overcame them. Consumers became more likely to follow the consensus of other consumers about purchasing a brand of sunglasses when told others similar to them were doing the same. In classrooms where adolescent aggression is frequent, it spreads contagiously but almost entirely within a peer group. For example, frequent aggression of boys in a class has little effect on the aggressiveness of girls and vice versa. Employees are more likely to engage in information sharing if they see it modeled by fellow co-workers rather than by managers. Physicians who overprescribe certain drugs such as antibiotics are unlikely to change this behavior in a lasting fashion unless informed that their prescription rates exceeds the norm of their peers. And after an extensive review of environmental behavior changed the economist Robert Frank stated, "By far the strongest predictor of whether we install solar panels, bi-electric cars, eat more responsibly and support climate-friendly policies is the percentage of peers who take those." You'll notice a common theme with each of these examples. People are generally persuaded by learning what the masses do but they are far more likely to be persuaded if they hear what people like them do. Let's take another UK example. Her Majesty's Tax Office sent a letter to people who were delinquent taxpayers that provided the usual admonitions and penalties for failing to pay a $1,000,000. They got about 67% of the people who complied. My colleague there in the UK, Steven J. Martin, did this study and he showed that if you send them a letter that adds one sentence which is the majority of UK residents do pay their taxes on time. The rate goes from 67% to 71%. If the letter says the majority of people in your region, it goes to 73%. If you say the majority of people in your town, it goes to 79%. Once again, we're looking at what multiple others are doing and what comparable others are doing and you win as a consequence. How can all of us supply this principle? I asked Chaldeini for the easiest way to apply social proof, something all of us can try. Here's a strategy that I really like. If you have a product or service, let's say some product and for the demand for it has been so good that you're out of it. What do you say on your website to alert people that you're out of this thing? Sometimes you see not available at this point or not presently available for purchase. Some kind of language like that. If instead you say sold out, you engage the principle of social proof that the others don't. If it's not available, that could be because of a manufacturing problem or a supply chain problem. But if it's sold out, it means it's because a lot of other people have decided to do this. You change that one sentence and you get more people lined up on a list to purchase the product when it is available by using the social proof. Honestly, the problem is not that you don't have this available to you. You do. just don't recognise how to harness it very often. Nudge Vault subscribers will recognise this insight. It is one of the 452 within the Nudge Vaults, and it's a study by Peterson back in 2019. His research conducted at the University of Texas found that the sold out label led to 8% less disappointment and fewer negative product reviews than an out of stock label and 15% less than an unavailable label. Social proof makes complete sense to me. I can understand why we follow the actions of others. We are overwhelmed by choice every day, and following what the majority do makes sense. It's an easy heuristic that will lead to pretty decent results. I notice myself following the crowd all the time. I book hotels, the lovers of books, I wear clothes that I see other people wearing. However, there is an aspect of Chaldini's research that I've never quite understood. See in his original studies on social proof, studies that I've cited on the show dozens of times. He proved that social proof becomes more effective if it's hyper-focused on people like you. Specifically, I'm referring to his famous 2008 study with Goldstein. I'll repeat the study for those who haven't heard it before, but sorry if you have, you can skip ahead 30 seconds if you like. So in a mid-sized hotel in Arizona, Chaldini ran an experiment with 1,058 guests in 190 rooms over 80 days. The goal was to get people to reuse their towels. Sometimes, the researchers put an environmental plea in the room. They would put a little placard, which said, "Help save the environment, reuse your towel." When guests saw this message, 35.1% of them reuse their towels. The rest didn't bother. The next group received a similar-sized placard, but it said, "Rather than help save the environment," it said, "the majority of guests in this hotel reuse their towel." This triggers social proof, and suddenly 44.1% of the guests reuse their towels, up considerably from the 35% in the control group. But Chaldini and Goldstein tested one final message. A message I've never quite understood. They wrote, "Most hotel guests who stayed in this room reuse their towels." This message, I think, is irrelevant. Who cares how people in that room acted? Surely we'd be more persuaded by hearing how most other people in the whole hotel were impacted. But that wasn't the case. The final message increased reuse of the hotel towel to 49.3% so that's up from 44.1% in the previous variant. I've never quite got my head around why this happens. Why does the specific reference to the group guests in this room work so well? Well, I asked Chaldini. Well, some of it is not entirely rational, but if you step back, it is rational. Who are the people around me? They have the best match of circumstances to me. The people in my home, the people in my neighborhood, the people in my community are most like me, and they're the ones I should most find diagnostic of what I should do in this situation, because their situation, their circumstances are similar to mine, and that's the best type of person to follow. Chaldini writes that there is compelling evidence for the importance of similarity in a study of a fundraising effort conducted on a college campus. In the study, donations to charity more than doubled when the requester first claimed to be similar to donation targets. When they just said, "Can you donate?" Not many people did, but when they first said, "Oh, I'm a student here too, can you donate?" People were far more likely to donate. The closer you get to people around you, like you, the more likely you are to say, "Oh, this is a good cue for what I should be doing." And this, I think, links very nicely with Chaldini's seventh principle of influence. The principle he introduced in the latest edition of his book, It's Unity. He'll say yes to those who share an identity with them. And those identities can be relatively different. They can be the same religion. If a loan officer and a solicitor for a loan have the same religion, the officer is more likely to give them the loan. This person is one of us. He's of me. He's not just like me. He's of me in this category, this identity role of a category. Now, here's the thing that I don't even usually talk about, but I think it's so revealing. Not only do you get this loan officer to give that loan at higher than normal rates. The recipient pays it back at higher than normal rates. You're in it together. You're going to favor those people who are of you. And it can be identities of various kinds, sports fans of a particular team, right? It can be political parties. It can be neighborhoods. It can be work environments. I got a colleague to do me a favor, a big favor that he first said no to when I said to him, come on, Tim. We've been members of the same psychology department now for 12 years. And I had it like that. We said no before. But now I reminded him of our unity, our unified identity. And the answer then became yes. Social proof and unity is slightly different. Unity is more about the way individuals can influence and persuade if they're similar to us. But the two combine. If we hear that the majority of people and social proof like us, that's unity, take us out of action, then we're more likely to do it. However, what do you do if you have no social proof to share? What do you do if your product or service isn't that popular? Can you even use social proof? Well, I asked Robert Childini that exact question after this quick break. And I should point out that most listeners do stay tuned until after the outbreak. Hello and welcome back. You and the majority of listeners are listening to Nudge with me Phil Agnib with the fantastic Dr. Robert Childini. Now I wanted to know what we should do if our product isn't the most popular. If it's not sold out, is there a way we can use social proof if we don't have the corresponding popularity? It turns out there is and my research team has done some of the research. And that is suppose you have some, it's a startup, you have something, or maybe it's a new upgrade to your product lists. And it really is a valuable thing. But most people haven't done it yet. And so you can't say the majority of our customers are choosing this new upgrade. Here's what you can say. We have a trend in that direction. You can say two months ago, only 15% of the people did it. Last month, it was 20%. This month, it's 30%. If you were to just say, well, 30% of our customers choose that. That's a mistake. That means 70% have not. But if you show them a trend in that direction that gets to 30, you get a significant increase in uptake because people project trends into the future. So what I always recommend is don't just give them the percentage at this one point. If you've got something that's truly valuable, you're going to see an upward trend. Track that and present that. And what we find in our data and other studies have done the same thing, that trend outperforms the percentage all by itself. Chaldeen he writes about the study he helped run in his book Influence. He writes how he invited university students to participate in the experiment in which some subjects read information indicating that only a minority of their fellow students conserved water at home. That's what they were trying to change, water conservation. For another sample of students, the information indicated that although a minority of other students conserved water, the percentage doing so had increased over the past two years. Finally, there was a third sample of students. This was the control condition who didn't get any information about how other people were conserving water. They were just told to do so. Chaldeen he and his colleagues then sneakily measured how effective this water conservation message was. To do this, all the students were asked to participate in a consumer preference test on a new brand of toothpaste, which they were to rate after brushing their teeth in a sink at the laboratory. You can see what Chaldeen is going with this. They didn't know it, but the researchers had equipped the sink with a meter that recorded exactly how much water they used when testing the toothpaste. So which of these water conservation messages was most effective? While the results were clear. Those who had heard that only a minority of students conserved water at home, they conserved when they were brushing their teeth, even less than those in the control condition. So hearing that few people do something actually had a worse impact. That's worse than hearing nothing at all. They used more water than if they hadn't been told how others acted. However, those who learnt that that minority of people who were conserving water was increasing that more and more people are doing so, well they use the least amount of water. They use less than both the control and the other variant. Sharing that behavior is changing is a good way to persuade. What we found is that you need three data points where you say it was this, at this point, it was this at the next point and then now it's this. So you have a true trend. Otherwise all you have is a change and changes go up and down and you can't and level up, but a trend has a trajectory that people see as going forward in the future. So when you have that third data point, you get to say something very valuable. You get to say more than just and more of our customers are adopting it. You get to say more and more of our customers are adopting it. That's the trend. And if that's true, we'd be fools of the influence process if we didn't make that available to people honestly. Which of course leads me to tell you that more people than ever before are signing up to their nudge vaults. In the past 24 hours, at the time I'm recording this, five of you signed up to unlock the 452 evidence backed insights. That's more than any other day since I've launched it. I created the nudge vaults for all marketers out there who struggle to apply the behavioral science to their work. The nudge vaults will help you source, apply and test marketing psychology insights with evidence backed reliable principles. And of course, you shouldn't take my word from it. You should be influenced by people like you. So here is Laura Scarf, director at the Business Academy online, sharing what she thinks about the vaults. In terms of nudge vaults, this was really the kicker for me. Having access to the vaults, having access to all of these studies, and what I really loved about the database was Phil gave examples of how you could apply it. And so that I found incredibly useful and in fact was one of the main sellers for me. If you're interested in this increasingly popular database, then head to nudgepodcast.com/volts. That's nudgepodcast.com/volts to learn more. Massive, massive thank you to Robert Chaldeini for joining me again on Nudge. I feel incredibly privileged to have interviewed Chaldeini. I think he is the best behavioral science practitioner of all time. His books are fantastic. I recommend all of them to you, including influence, which I think is his best, but also some of his overlooked books like Pre-Swashing and Yes. You'll find links to all of these books in the show notes. I suggest you read them all. Thank you so much for listening. I've had great fun working on this episode. I'll be back next Monday for another episode of Nudge, which I should remind you after an episode like today is the UK's number one marketing podcast. Cheers.