It was Jonah Berger’s grandmother who first introduced him to Malcolm Gladwell. While he was a student at Stanford, Berger’s grandmother sent him a review of Gladwell’s book, "The Tipping Point.” Berger was intrigued, read the book, and loved it, but says he was nagged by questions about human behavior that drove outcomes. Were there really just a few select “connectors” or “mavens” who made products popular or ideas catch on—or were things actually more predictable, more scientific than that?

After spending years researching everything from the most emailed New York Times articles to the most popular baby names, Berger, the James G. Campbell Assistant Professor of Marketing at the Wharton School, thinks he may have hit upon an answer. “What we found in our work is a lot of what drives success—popularity, and a host of different domains—is really social influence, is word-of-mouth, one person telling another person or one person imitating another’s person’s behavior. That’s driving things to catch on,” Berger, 32, says.

This is different than a few select people leading the masses to wear a particular brand of sneakers, or read a certain book. Messages still matter most of all. And Gladwell’s idea that a handful of influential people—“those six hipsters in the East Village,” as Berger calls them—will determine the brand of shoe on your feet in a year’s time just isn’t the case. “Influence exists,” says Berger, “[but] it’s just not about certain people having much more influence than everyone else.”

In his new book, “Contagious,” Berger says it’s word-of-mouth that makes a product or idea catch on. But, why? What’s the secret to one pop tune catching fire on YouTube while another languishes in obscurity? Why does one restaurant with a gimmicky sandwich (a $100 cheesesteak, anyone?) succeed while another fails? What compels millions of people to share a video about a blender, a somewhat mundane household product?

Berger says there are actually “six principles of contagiousness” that make products, ideas, and messages more likely to spread: social currency, triggers, emotion, public, practical value, and stories. Berger has developed the acronym STEPPS as a handy way of remembering the six principles. He notes that not all six things are needed to make the story about the $100 cheesesteak or indestructible blender catch on, but the more elements that are present, the better.

“Contagious” is that rare departure for an academic—a book written for a general audience. But it is one that draws upon Berger’s years of research. “The reason I wrote this book is to help people. As an academic, it’s great to do rigorous academic research—that’s why we’re here, that’s why I’m at an academic institution, but if no one uses those ideas, at the end of the day, there’s sort of a question, ‘Well, was it worth it?’” he says. “This book is a way of saying, ‘OK, we and others have found lots of interesting things, let’s try to boil it down into some key learnings, some ways that people can apply so they can get their own things to catch on.’”

The Current sat down with Berger to talk about how what catches on isn’t random, how our behavior is predictable, and how far less sharing happens on social media than we may think.

Q: In ‘Contagious,’ you write, ‘although quality, price, and advertising contribute to products and ideas being successful, they don’t explain the whole story.’ What does?
A: What we found in our research is word-of-mouth and social influence complete that picture. You might have thought the company with the biggest budget wins or the best product wins, but I think we see lots of examples where worse products actually win out or lots of cases where somebody advertises a whole bunch and it doesn’t go anywhere. What we found in our work is a lot of what drives success—popularity, and a host of different domains—is really social influence, is word-of-mouth, one person telling another person or one person imitating another’s person’s behavior, and that’s driving things to catch on.

Q: Conventional wisdom says it’s totally random what catches on and what doesn’t. But you’re saying that it’s not random at all.
A: I think that is the biggest misconception people ask: ‘Is there a silver bullet from the book, one thing I need to be doing?’ There aren’t, there are six, but I think if there is one thing you take away from the book, it’s not random, it’s not luck, it’s not chance, it’s not magic. It’s not even cats. Some people say, ‘Well, why do things go viral? Well, it must be cats.’ It’s not. There’s a science behind this, just like we can understand how people make choices, just like we can understand a host of behaviors in consumer behavior and in organizations, we can understand why people talk about and share things. There’s a science of conversation, the psychology of talk. We’ve spent over a decade studying these issues. Lots of other people have done great work, as well, and building on these insights, we’ve noticed that there are six key principles at work.

Q: You have configured these six principles into an acronym, STEPPS. Can you talk about what they are?
A: They are: social currency, triggers, emotion, practical value, public, and stories, and each of them is really a psychological driver of what people share. It’s not that people share sports more than they share politics. It’s really about understanding the psychology of sharing. So, social currency, for example, is all about how we share things that make us look good, smart, and in-the-know. A lot of times, what people talk about and say is a signal. Others use it to make inferences about people—what they like, who they are, and so we talk about things that make us look good rather than bad.

Q: The example in the book that I particularly like is the incredibly popular bar with no sign that’s located behind a hot dog store. Can you talk about that?
A: There are lots of great bars in New York, so one question you might ask is, ‘How does one bar stand out?’ But you go into this bar through a hot dog restaurant. They have amazing hot dogs, anything you can think of. There’s a phone booth hidden inside the wall and a rotary dial phone. You put your finger in, you dial a number, and the back of the phone booth opens up and they let you in this bar—but you can only get in if you have a reservation. There’s no sign on the street, there’s no sign inside the restaurant. They’ve really done everything they can to make themselves a secret. But that’s why they’ve become popular—because it seems like something that not everyone knows about. It makes people feel special to get inside. They share it with others because it makes them look in-the-know.

Q: Is it more about feeling special and being part of a club, rather than being ‘cool’?
A: People use the word ‘cool’ very broadly. It means a host of different things to different people. I think the idea here is something that makes you look good rather than bad. I’m not a golfer. I don’t own golf clubs but if I was, the type of golf clubs I used would make me look good to my friends. Would it make me look cool? Maybe, maybe not. You could say the same thing if you’re into cooking—knowing the next kale recipe or a way to make lobster mac and cheese is insider stuff for people who are into cooking. It’s really domain-specific. It can be education, the best child care, dog care. The point is, you know things not everyone knows. If everyone knows it, it doesn’t make you look special.

Q: Talk about triggers. That’s the second principle you write about.
A: Triggers actually play a huge role in what people talk about and share. The idea there is if something is top of mind, it’s going to be tip of tongue. Why do we talk so much about the weather or what we had for lunch? It’s not the most interesting thing going on, but we’re thinking about it so we’re more likely to share it. My favorite example here is Rebecca Black. Everyone hates the song, ‘Friday,’ but why did it do so well? If you look at the data, you see there [are few searches] and then there’s a spike in the searches and then it goes down and then another spike. The searches are seven days apart, on Friday. That song is equally bad every day of the week … but Friday is a trigger, a reminder in the environment to make people think about it and talk about it. It’s just like peanut butter and jelly. Peanut butter is like a little advertisement for jelly. The two are connected in our mind, so thinking about one triggers you to think about the other.

Q: We are predictable in a lot of ways, aren’t we?
A: We’re not mindless automatons, but we are predictable. It’s not like behavior is random. That’s been the most interesting thing for me to study this. We’ve done so much in other areas of behavior science to understand and quantify behavior. Can we predict every behavior? No. But we can get some sense of what’s going on, some traction, by understanding the drivers of social influence.

Q: The ‘E’ stands for ‘emotion.’ It makes sense that something is shared if it strikes an emotional chord with people.
A: In general, the more you care about something, you’re more likely to share. Some emotions increase sharing rather than others. If you watch YouTube, for example, you think it’s all about humor, and then if you looked at political rants, angry stuff is shared—but those are two totally different things. What our research has found—and this is joint work with [Wharton assistant professor] Katherine Milkman—is these emotions actually have a lot in common. Anger and humor seem really different, but they’re both activating or arousing emotions. If you’re angry, you’re fired up. If you’re laughing, if you think something’s funny, you’re also fired up. This activation causes you to share things. Activating emotions, whether they’re positive or negative, drive us to share. Sure, we share positive things more than we share negative things, but it is more complicated than that.

Q: You write about ideas being public, as well. What do you mean by that?
A: The idea of public is if something is built to show, it’s built to grow. Think about how you pick a restaurant. If you don’t know where to go, you look around for one that’s full. You assume if it’s full, it must be pretty good. We tend to use others as information, we tend to imitate others’ behavior. We can only imitate what others are doing if we can see it, if we can observe it. If you can’t see in that restaurant window, then you’re not going to see how many people
are inside and you’re going to be less likely to go in and check it out. The idea of public is all about making the private public, making things [that are] less observable more observable. You can think about Apple, for example, and the logo on their laptop. The logo actually used to face the user when it was down on the table. You want to know which side has a clip on it, it faces you, but then it’s upside down for everybody else. It seems like such a small thing, but if you think about it, it makes it much more visible, much more observable for everyone else. This can have negative effects as well. You think anti-drug ads would decrease drug use, but a researcher over in [the Annenberg School for Communication] actually found that anti-drug ads, in some cases, increase drug use because it makes behavior more public. If you’re a kid sitting at home, [who was] never going to try drugs, and suddenly someone gets on the TV and says, ‘Hey, someone’s going to ask you to use drugs, and it’s the cool kids in school, but don’t do it,’—it’s simultaneously telling you not to do it, and telling you other people are doing it. The more we know that other people are doing something, the more we’re going to imitate it, even if it’s not something we should be doing. …The idea about planting it in our heads is very right, particularly if we’re not thinking about something. The more that thing is top of mind, the more we think others are doing it, the more likely we’re going to be to do it ourselves.

Q: You also write about practical value, which seems straightforward.
A: Practical value is news you can use. A guy named Ken Craig, he’s 86 years old, made a viral video about corn. You may ask, ‘How does someone who’s 86 make a viral video and why would anyone share a video about corn?’ He has a trick for getting rid of those annoying silks on the sides of corn. That’s just useful information, so people share it. I still get emails from my mom about [what to eat] and the right sunscreen to use [according to] Consumer Reports. We
share that because we want to help others to make their lives better.

Q: Finally, the ‘S,’ which stands for ‘stories.’ We’re just a bunch of storytellers at our core, aren’t we?
A: People love to share stories. The one thing I have to add there is this idea of Trojan horse stories. It’s not just the stories are engaging—they are. What’s neat about stories is they carry something inside. They’re Trojan horses for information, for brands. In the book, I talk about this example of Blendtec. It’s a company that makes blenders. They have a video where they drop an iPhone into the blender. You watch it get torn to shreds, it turns into glass and dust,
it’s been shared millions of times. Sales [of the blender] went up 700 percent afterwards. You think about why—it’s not just engaging content. At the end of the day you can’t share that video without learning that Blendtec makes really tough blenders. No one wants to share an advertisement. They do want to share remarkable content that has social currency. They do want to share emotional things, they want to share useful information, but if that has inside it a brand or a benefit, that brand or benefit comes for the ride.

Q: The blender video translated into higher sales. But does it always? Do people sometimes share a wacky video of a blender chewing up an iPhone just because it’s a wacky video of a blender?
A: I think this book does talk about viral content, it helps us understand why things go viral. But if you look at the viral, only about 7 percent of word-of-mouth is online. Much more is offline. And so, for me, this book is about understanding why things go viral, but it’s also about, ‘Hey, I’m a newspaper reporter, how can I make more people share my content?’ ‘I’m a local yoga studio, how can I make more customers come in?’ ‘I’m an NPR radio station, how can I get more listeners, more donations?’ It’s about understanding why people share anything online or off and how companies, and individuals, and organizations can harness these concepts to help their own ideas catch on. If you’re an accountant and you can get 10 million views, fantastic. But you don’t need 10 million views, right? All you need are a couple more customers. If you’re a coffee shop, all you want is enough business to stay in business. I think it’s really about turning customers into advocates—getting people to find out about your service or idea, even if it’s political ideas or nonprofits.

Q: So, these are also things that nonprofits could do, or do the principles you write about work better for companies that are trying to promote a specific product?
A: I think it works better for people who are trying to promote something, whatever that thing is. We like talking about products because they’re easy to talk about, but the same thing happens with ideas. … It’s about crafting narratives to figure out how to get people who know the information to spread it. It doesn’t have to be a physical product; it doesn’t have to be anything that’s being sold. But there does have to be some sort of idea unit. How do you find out about a new dog trainer or a new real estate agent or what college you should send your kids to? I think this idea of word-of-mouth is important across industries and across areas of life.

Q: Consumers can be paralyzed by so many choices. Does word-of-mouth help to get rid of some of that anxiety by telling us what products and ideas we can trust?
A: Oh, so much. We’re getting a dog walker. I love this dog. We want this dog to be trained, [the dog walker will] take this dog into their house—but how do I know if they’re a good person? Same thing with a real estate agent—I’m trusting this person to find me a good place—how do I know? The more important the decision, the more risky the decision, the more we rely on others for information, whether picking a college, a car, which house to buy, what city to live in, what job to take, for all these things we turn to friends, coworkers, and family members because we trust them. We know they have our best interest at heart. If you think about it, there’s no way that we could collect all that information ourselves. We’re not only paralyzed by choice, we’re paralyzed by information. I do a little bit [of research] on too much choice and decision quicksand—how we get stuck in choice. There’s so much information out there, how do we know what to pay attention to, read, and listen to, and friends and colleagues and word-of-mouth generally is a way to short-circuit that process.

Q: In your book, you write that yes, the messenger is important, but not as important as the message itself. Here, it sounds like you’re saying that the messenger still plays an important role.
A: What I mean by ‘It’s not the messenger,’ is, it’s not about special people. It’s not about 1 percent of everybody that decides what the rest of us do. It’s not about finding an influential blog or celebrity to get your idea to catch on. The messenger is important, but they’re your friends. We trust our friends more than we trust celebrities anyway. Yes the audience matters, yes, the messenger matters some, but not in the way that I think ‘The Tipping Point’ would make
us think. It’s not about those six hipsters in the East Village and if they get the product, then it’s going to be a hit. It’s not about finding Kim Kardashian and getting her to blog about us and then we’re going to be a success. That stuff doesn’t hurt, but often, it doesn’t pay off. It’s much more important to think about everyday Joes and Janes and get them to share, whether they have 10 friends or 10,000, whether they’re the most persuasive person in the world or a shy wallflower. Shy wallflowers still have friends who rely on them for what to do and they’re going to be really influential among that community.

Q: One thing in your book that really surprised me was the social media piece. We may think that the bulk of sharing information is happening on Facebook or Twitter, and this is how ideas spread, but the percentage of information shared this way is actually way lower than we may think.
A: It’s like that old anecdote—you look for your keys under the streetlamp because that’s where the streetlamp is. Sure, we can see things being shared online, but that doesn’t mean most things are shared online, or that online has a bigger impact on our behavior than offline. I think it’s really more about understanding when people share and why people share. Every school is trying to figure out how to get on social media. Is that worth everyone’s time? I’m not clear. I’m not saying it’s not, but it’s just not clear to me. I actually have students in my class do an exercise—they have to get on Twitter, build a following, share content, and track how many people are looking at their content by using short links. You can see that on a good day, best case, 5 percent of people may click on what you’re sharing. Is that worth it? Maybe. But are all those people then buying something or changing their behavior because of it? Not even clear. And so because we can see the followers going up, we feel like we’re doing something good. It can be very useful to be out in social media but I think it’s more important to think about what benefits you’re getting from it and be sure that those benefits are paying off for the investment that you’re putting in. To me, it’s much more important to think about how you can get offline consumers talking and sharing because there are just as many, if not more offline conversations.

Q: Does it boil down to it simply being easier for companies to set up a Facebook page and a Twitter account, and more difficult to engage in face-to-face contact with potential customers?
A: I think that everyone tries to sell things whenever they do it, whether it’s a university, whether it’s local shops. My message needs to say. ‘Here’s my product, here are the benefits.’ That’s not how word-of-mouth works. People don’t share sales attempts. We’re doing some work that shows that the more branded something is, the less likely that people are to want to share it because it seems like a deliberate sell attempt, and they don’t want to pass that off to their
friends. It’s not about necessarily having people talk about you; it’s about setting up the conversations so at the end of the day you’re part of that conversation. Maybe they’re not talking about your coffee shop every single day, but they’re talking about great coffee and you’ve got them to talk about that more, and every so often, your coffee shop gets to go along for the ride. I talk about Vanguard in the book [and] the MoneyWhys [newsletter]. No one’s sharing those because they want to advertise for Vanguard; they want to help others be more financially responsible. At the end of the day, that’s shaping the conversation, and increasing the number of people who are talking about financial issues, which makes Vanguard more of a solution. It’s almost like the old public relations idea—you link your article to something that’s going on currently, because that’s the conversation. That’s the same idea here.

Q: What’s next for you?
A: I’m working on a lot of projects with students and faculty here and folks at other universities, about why people talk and share. One project is how online versus offline changes what we share, how does when we share a written versus oral medium shape communication? We find that written communication makes us talk about more interesting things because it gives us more time to construct and refine what to say, whereas in an oral conversation, we don’t want to sit there in silence, which means that we talk top-of-mind, but not necessarily what’s the most interesting. We have another project looking at how audience size shapes what people talk about, because it changes the focus from us to others. When we’re talking to one person, we’re thinking about that one other person. When we’re talking to a broad audience, we’re thinking more about ourselves, so we share content that makes us look better rather than worse. I’m doing a project on how controversy shapes what people talk about. Is more controversy better or worse? Another project on when do people talk about the present, the past, or the future, and how much do they talk about each of those points in time and why. We’re working on a dozen or so projects in this area, but really we’re trying to understand why people talk and share, what the drivers are, and how contextual factors shape how those processes work.