PDF Summary:Contagious, by

Book Summary: Learn the key points in minutes.

Below is a preview of the Shortform book summary of Contagious by Jonah Berger. Read the full comprehensive summary at Shortform.

1-Page PDF Summary of Contagious

Why is it that some new products and ideas gain widespread popularity while others fail to “catch on”? According to marketing expert Jonah Berger, the driving force behind products and ideas catching on and becoming “contagious” is word of mouth: Things catch on when people talk about them. You might think you have to spend large amounts on advertising to trigger this effect—but Berger explains that generating word of mouth only requires a compelling product or compelling marketing.

In our guide, we’ll explain Berger’s strategies for generating word of mouth, why they work, and how you can implement them. Through our commentary, we’ll also bring in psychological research and alternative perspectives that add nuance and contrast to Berger’s strategies. In addition, we’ll provide real-world examples of Berger’s principles and practical advice on how to adapt them to your product or idea.

(continued)...

Step #2: Engage Your Audience

Berger explains that attracting an audience for your product isn’t enough—you then have to keep them interested in it. Someone who sees your product but quickly forgets about it won’t generate word of mouth, while someone who’s interested will think and talk about it much more.

(Shortform note: Some experts argue that engaging an existing audience is more important than finding a new one. Studies show that gaining new customers can cost more than five times as much as keeping customers you already have—and that increasing customer retention (how many customers you consistently keep) by 5% can increase profits by anywhere from 25% to 95%. From this perspective, engaging an existing audience is a cheaper and more profitable way to generate word of mouth than attracting new customers.)

In this section of our guide, we’ll explain Berger’s two methods for keeping an audience engaged: inspiring an emotional response and telling a story.

Method #1: Inspire an Emotional Response

When people get emotional, they like to talk about how they’re feeling and what made them feel that way. Therefore, when your product inspires an emotional response, it’ll also generate word of mouth. Berger suggests using marketing that focuses less on delivering lots of information and more on inspiring an emotional response.

(Shortform note: Experts suggest that emotional marketing doesn’t just get people talking about your product—it can also make them feel an emotional connection to your company or brand. If your marketing makes an audience feel proud to buy your products or somehow “close” to your company, then they’ll want to be loyal customers that talk about and buy your products long-term. For example: Coca-Cola’s “Share a Coke'' campaign put common names on Coke products that customers could share with friends and family. This campaign associated Coke with emotional relationships, and it made customers feel involved or personally attached to the company.)

However, not every emotion has this effect. Berger says to aim for emotions that generate “physiological arousal”: a state of physical readiness for action. People respond to physiological arousal in various ways: running around, jumping for joy, or—most importantly—telling others about what caused their emotional response. The five main high-arousal emotions are anger, anxiety, awe, amusement, and excitement. Meanwhile, low-arousal emotions include sadness and contentment. Inspire high-arousal emotions with your marketing—for example, you could amuse people by adding humor, or awe them with breathtaking nature photos.

Is Focusing on High-Arousal Emotions Enough to Generate Virality?

Further research on the link between emotions and popular, “viral” content suggests that physiological arousal alone can’t explain audience engagement. Instead, studies show that emotional “virality” depends on three different standards:

  • Physiological arousal

  • Valence: positivity or negativity

  • Dominance: how much people feel in control (for example, inspiration is a high dominance emotion while fear is low dominance)

Psychologists argue that different combinations of emotions can create different kinds of “virality”: Divisive and controversial viral stories inspire a mix of high arousal and low dominance emotions, while uplifting “feel-good” viral stories inspire a mix of positive valence and high dominance emotions. Therefore, following Berger’s advice and solely focusing on high-arousal emotions may not be sufficient to emotionally engage your audience—instead, consider how you can use all three factors above to your benefit.

Method #2: Tell a Story

To engage your audience, Berger recommends telling a gripping narrative with your marketing and making your product crucial to this narrative. People love to share interesting stories. When your product is crucial to the story, they’ll have to mention it—generating word of mouth.

For example: In 2019, PepsiCo created a Superbowl commercial that told a story about people proud of drinking Pepsi. They based their story on the phrase: “Is Pepsi okay?” This phrase is essential to the story, and it centrally features the product—so people can’t explain the narrative without talking about Pepsi.

Add Context to Your Stories

Some experts recommend that to engage an audience, you shouldn’t just tell a story that features your product—you should also tell a story about when and why people use it. This way, you engage the audience by showing them why they might need your product or what benefits it might provide.

For example: An ad for a smartphone tells the story of kids pranking their dad by hiding his phone charger. This ad tells a story about the product, but it doesn’t show an audience why they should want it. Consider how the same ad with context shows the benefits of the product: Kids prank their dad by hiding his phone charger. But their dad’s new smartphone has such good battery life that a week goes by without him looking for the charger—so the kids get bored and give up on their prank.

Step #3: Benefit Your Audience

Once you’ve attracted and engaged an audience, Berger says to focus on the third method of generating word of mouth: making sure your audience gets something out of talking about your product. If they get something out of it, then your audience will want to generate word of mouth.

(Shortform note: While Berger offers benefits as one of many ways to create word of mouth, some experts claim that you should build your marketing entirely around these benefits. People focus on their own personal lives and problems—so if your marketing doesn’t provide a personal benefit, people will ignore it. But if you focus entirely on benefitting your customer and providing them with a positive experience, then you’ll get people interested and talking about your product.)

In this section of the guide, we’ll explore the two benefits Berger says to offer your customers: social currency and practical value.

Benefit #1: Social Currency

Berger says your product should provide “social currency” to your customers—in other words, talking about it should give them social influence and make them look interesting. If talking about your product makes someone look good in this way, then they’ll generate much more word of mouth. On the other hand, if talking about your product makes someone seem dull, they’re probably not going to choose it as a topic of conversation.

(Shortform note: For a further explanation of what “looking good” means in a social context, researchers studied why people share viral videos and found three main reasons that relate to social currency: 1) They want to be the first to show their friends something interesting, 2) they want to demonstrate their knowledge of something, and 3) they want to show that they’re up to date on current trends.)

To make your product or idea a source of social currency, Berger suggests:

  • Making your product or idea remarkable
  • Applying game mechanics
  • Using scarcity and exclusivity
Making Your Product or Idea Remarkable

Berger notes that people love talking about remarkable things because doing so makes them seem remarkable, thus increasing their social currency. Make your product or service seem remarkable by identifying and emphasizing the thing that makes it interesting. If your product does something previously thought to be impossible, or if it improves upon a traditional formula, make sure to mention this in your marketing. For example: In 2006, Gillette launched the world’s first five-blade razor. This “world first” made the product remarkable and featured prominently in its marketing.

(Shortform note: For advice on how to make your product remarkable, Seth Godin (Purple Cow) argues that you must take risks—playing things safe and going for broad appeal means you won’t stand out. To take risks, Godin suggests consistently trying new ideas and taking on large and ambitious projects—even if you fail spectacularly, you’ll still get people talking about you and your product.)

Applying Game Mechanics

Berger suggests adding “game mechanics”—the components of a game that measure accomplishment—to your product. Game mechanics might include systems like reward points or bonuses for frequent customers. When people interact with these mechanics and “win” the game, they’ll feel a sense of achievement—and they’ll brag about this achievement to gain social currency and impress others. When they brag, they also generate word of mouth about the product or service that gave them a sense of achievement.

(Shortform note: Game mechanics don’t just generate social currency—they can also psychologically motivate people to buy or use your product. Research suggests that game mechanics can increase motivation and make tasks feel more meaningful. This means customers might engage with your product’s game mechanics just to enjoy them for their own sake. And if they enjoy them enough, they might recommend the game to others, which generates word of mouth about your product. For example, the US Army created and ran their own video game for over two decades—a multiplayer game that people could play with (and recommend to) their friends.)

Using Scarcity and Exclusivity

According to Berger, making a product or service scarce gives social currency to the people who do manage to get hold of it. These customers seem “special” because they’ve accessed something that’s out of reach to a lot of people. When bragging about their “special” status, these customers will spread word of mouth about the scarce thing they’ve bought. To add the perception of scarcity to your product, give the impression that it’ll be difficult to get hold of. For example, tell customers that you expect the product to sell out quickly.

(Shortform note: In addition to providing social currency, scarcity can also generate word of mouth through stories of how hard it is to obtain your product—and how far people go to get it. This was a crucial part of toy company Ty’s billions made from their plush toys, Beanie Babies. Ty tightly controlled limited runs of certain Beanie Babies, creating scarcity. This scarcity led people to incredible lengths to get certain Beanie Babies, even reselling the toys for thousands of dollars. Stories of these devoted customers generated word of mouth not just about the products, but about the Beanie Baby “craze” as a whole.)

Berger argues that exclusivity works on a similar principle—if customers feel like they’re part of a group that not just anyone can join, they’ll brag about it to gain social currency. And if your product made them feel that way, then they’ll mention it and generate word of mouth. To add the perception of exclusivity to your product, create the impression that only a select few people can access it. First-class seats on an airplane are a great example: Airlines separate first class passengers into their own section and provide them extra benefits so they feel like they’re part of a special group. These customers then brag about these benefits or how comfortable their trip was—generating word of mouth.

(Shortform note: While Berger suggests exclusivity as one possible method of generating word of mouth, some marketing relies entirely on exclusivity. These strategies are often known as “anti-marketing”: Marketing strategies that actively avoid advertising or intentionally defy normal marketing principles to create an image of exclusivity. For example: In 2011, Patagonia ran a Black Friday ad that said, “Don’t Buy This Jacket.” Anti-marketing campaigns give the impression that your product or company doesn’t need to attract new customers—which makes it look exclusive. However, anti-marketing is risky. Customers might never notice a product or take its ironic approach at face value, like with Coca-Cola’s failed “OK Soda” product.)

Benefit #2: Provide Practical Value

The easiest way to benefit your audience is to make your product or service a source of “practical value”: useful things that make life easier. Examples of practical value include money-saving or advice on “life hacks.” Practical value generates word of mouth because people want to share it to benefit their friends and family—and in the process, they’ll talk about your product.

(Shortform note: You might wonder why Berger emphasizes practical value when earlier on he noted that things like price and quality can’t make something popular on their own. To clear up this confusion, think of it this way: What matters isn’t how much value you provide to your customers, but rather how much they talk about the value you provide.)

Berger suggests two sources of practical value that get people talking:

Discounts

The first way to add practical value to your product or service is to give it a significant discount. Berger notes that if your product or service is a real money-saver, people will want to tell other people about it.

(Shortform note: While Berger recommends discounts—a type of temporary value-adding promotion—Ryan Holiday (Perennial Seller) suggests always making your customers feel like they’re saving money with payment models that require little to no upfront cost. This could include free trials, offering portions of your product for free, or even monetizing your product entirely through ads and sponsorships. Requiring little to no cash upfront means your product will provide more value to potential customers that want to try it. As a result, more people will try your product—and then more people will talk about it.)

Useful Information

The second way to add practical value to your product or service is to provide useful information to your customers, sending them advice or practical tips to make life easier. When your customers receive this information, they’ll create word of mouth by passing it on to friends or family members they think would benefit from it. In the process, they’ll also inform others about your company as the source of that information. Berger suggests you limit information to three or four simple and engaging points at a time: If it’s short, people will be more likely to actually read it. If it’s interesting, they’ll be more likely to tell others about it.

Share Useful Information About Problems Your Product Solves

Berger mostly talks about useful information as small tips for solutions to everyday challenges. While Chet Holmes (The Ultimate Sales Machine) also suggests providing useful information, he argues that it should instead educate your audience on the problem your product solves. The more your audience understands this problem, the more they’ll understand the benefits of your product—and the more they’ll share this information.

An example of problem-focused information marketing is Listerine’s popularization of “halitosis.” In the 1920s, halitosis wasn’t a medical term—it was just Latin for “bad breath.” But Listerine’s marketing reframed bad breath as a serious medical problem with a formal-sounding name. The marketing created buzz (and fear) around halitosis, and their products, which they positioned as the solution to this problem, became massively successful because of it.

Want to learn the rest of Contagious in 21 minutes?

Unlock the full book summary of Contagious by signing up for Shortform.

Shortform summaries help you learn 10x faster by:

  • Being 100% comprehensive: you learn the most important points in the book
  • Cutting out the fluff: you don't spend your time wondering what the author's point is.
  • Interactive exercises: apply the book's ideas to your own life with our educators' guidance.

Here's a preview of the rest of Shortform's Contagious PDF summary:

PDF Summary Introduction

...

Word of mouth is a powerful marketing tool. Research has shown that 20% to 50% of all purchasing decisions have word of mouth as their driving force. It’s at least ten times more effective than traditional advertising, for two reasons.

First, our friends and family are more trustworthy than ads. They’re objective sources of information about a product or idea because they have no stake in whether we accept their recommendation or not. They’re likely to tell the truth about a product’s effectiveness. Meanwhile, ads aren’t credible sources of information. Because their main purpose is to sell things, they focus on the good things about a product or idea and hide its flaws.

Second, word of mouth is more targeted than advertising. Of all the people who see ads each day on TV and on billboards, very few are actually going to be interested in buying the product being promoted. Meanwhile, word of mouth is naturally targeted because people only tell you about products that they know you will be interested in. For example, your friend isn’t going to tell you about some really cool skis she’s bought if she knows you don’t like skiing. Capitalizing on this targeted form of...

PDF Summary Chapter 1: Give People Social Currency

...

How Can You Make Your Product Seem Remarkable?

You can make a product or idea seem remarkable by using your marketing materials to emphasize the thing that makes it interesting or notable. Clearly tell the consumer what makes your product so special. For instance, can your product do something that was previously thought to be impossible? Does it break and improve upon an expected or accepted pattern? If so, make this a key element of your marketing strategy.

Take the example of Blendtec blenders. These products seem ordinary enough. They’re just blenders, right? Well, not quite. Blendtec products became remarkable when it emerged they were strong enough to blend items as tough as golf balls. No other blender had done that before.

Another example of this principle is JetBlue, a popular budget airline. Most low-cost airlines have small seats, very few snacks, and no in-flight entertainment. JetBlue flights are remarkable because they break all of these conventions—so people talk about and recommend them.

A more unusual way to make your product remarkable is to add an element of mystery or controversy to its marketing. Give it a mysterious provenance, or make it...

PDF Summary Chapter 2: Create Effective Triggers

...

For a trigger to be effective, it needs to be designed very carefully. It must have the following five features:

  1. The capacity for frequent activation. People need to come across the trigger a lot.
  2. Long-term relevance. The trigger can’t disappear from public view in the future.
  3. Activation close to the site of the behavior you want to encourage in people: for instance, near to the shop where people can buy your product.
  4. Uniqueness. It must be clearly distinct from other companies’ triggers.
  5. Relevance to your target audience’s environment. It must be something that this audience is likely to encounter in their geographic area.

The trigger also needs to be consistently and strongly linked to your product in your marketing campaign.

Feature #1: Frequent Activation

If you want people to consistently think and talk about your product, you need to remind them of its existence regularly. Therefore, you need to pick a trigger that activates frequently.

The easiest way to make your trigger activate frequently is to make it a common stimulus that people will encounter a lot in their everyday lives. Make the trigger something people might come across on their...

What Our Readers Say

This is the best summary of Contagious I've ever read. I learned all the main points in just 20 minutes.

Learn more about our summaries →

PDF Summary Chapter 3: Generate an Emotional Response

...

So, which emotions generate high physiological arousal, and which don’t? According to Jonah Berger, the five main high-arousal emotions are anger, anxiety, awe, amusement, and excitement. These are the emotions to incorporate into your marketing plan.

Meanwhile, low-arousal emotions include sadness and contentment. These emotions discourage action rather than drive it. For instance, sadness tends to de-energize the body. It makes people want to stay put on the couch and wallow, not rush about telling people about the source of their sadness. Likewise, contentment has a relaxing effect on the body. It makes people’s blood pressure go down and their heart rate decrease. People often want to relish this feeling of relaxation, not cut it short by snapping into action again.

Example: Denise Grady’s Viral New York Times Article

Over ten years, Denise Grady had written numerous articles about science for the New York Times. Her articles had always been popular but had never become truly “contagious”—until October 27, 2008, when one of her pieces went viral.

The viral piece appeared to be quite dry. It was about fluid dynamics: specifically, how you can use a certain type of...

PDF Summary Chapter 4: Create Public Visibility

...

Making Your Product Advertise Itself

Making your product advertise itself means visibly including your branding on your product so that people can immediately see who’s made it. For example, make your logo or tagline visible on the product. That way, when people see others using your product, they’ll learn about the existence of your brand.

If people start to see your branded products a lot, this may become a talking point. For instance, people might start to comment on the fact that the brand seems popular, or ask their friends if they’ve heard of this newly visible brand. This will generate word of mouth about your product and company.

Example: How Apple Products Advertise Themselves

Apple has found various ways to make its products advertise themselves. One example of this is the “Sent from my iPhone” email signature. Whenever anyone receives an email sent by an iPhone user, they’re greeted by this signature—unless the iPhone user decides to turn the signature off, and very few people can be bothered to do so. This signature works as an indirect iPhone ad. It tells people, “Your colleagues and friends have iPhones—why don’t you?”

Another example of...

PDF Summary Chapter 5: Provide Practical Value

...

  1. They follow the Rule of 100.
  2. They’re obvious: they’re well-advertised and easy to find out about.

Make Your Discount Big

For a discount to be amazing, it has to be big. For instance, a 5% discount will be perceived as an okay deal, not an amazing one. It doesn’t knock that much off the original price, so it’s not that attractive. A 50% discount, however, is a pretty big saving and is therefore more likely to impress customers.

Customers are more likely to share information about a big discount for two reasons. First, a big discount is more helpful than a small one. To many people, sharing information about a 5% discount doesn’t seem worth it. It’s not going to save their loved ones much money, so what’s the point in telling them about it? However, sharing information about a 50% discount is incredibly helpful—it’ll help the person’s loved ones make a huge saving. Therefore, this larger discount is more likely to be shared.

Second, big discounts are remarkable. They’re surprising, impressive, and exciting—and therefore worthy of remark. As you learned in Chapter 1, people love to talk about remarkable things because they’re a source of social currency....

PDF Summary Chapter 6: Tell People a Story

...

Conversely, if you embedded these facts and figures into the story of Jared Fogle, a man who lost nearly 250 pounds by eating nothing but healthy Subway sandwiches, people are going to be interested. This is a compelling story about a man who did something remarkable. The story may well include dry nutritional information about the low fat content of the sandwiches Jared ate. However, because this data is woven into a narrative, discussing it is more socially acceptable.

By including this information about Subway sandwiches in a story, you’ve made it much more shareable. People are more likely to pass on the information now that it’s part of a narrative. In many ways, you’ve inadvertently done Subway a favor. You’ve helped them generate word of mouth about their low-fat sandwiches. You wouldn’t have done so if you’d stuck to the “spouting facts” approach.

Telling the Right Kind of Story

It’s important to note that you can’t just incorporate information about your product or idea into any story and expect that story to automatically generate word of mouth. You need to tell the right kind of story: one that’s actually effective at getting people talking about your...

Why are Shortform Summaries the Best?

We're the most efficient way to learn the most useful ideas from a book.

Cuts Out the Fluff

Ever feel a book rambles on, giving anecdotes that aren't useful? Often get frustrated by an author who doesn't get to the point?

We cut out the fluff, keeping only the most useful examples and ideas. We also re-organize books for clarity, putting the most important principles first, so you can learn faster.

Always Comprehensive

Other summaries give you just a highlight of some of the ideas in a book. We find these too vague to be satisfying.

At Shortform, we want to cover every point worth knowing in the book. Learn nuances, key examples, and critical details on how to apply the ideas.

3 Different Levels of Detail

You want different levels of detail at different times. That's why every book is summarized in three lengths:

1) Paragraph to get the gist
2) 1-page summary, to get the main takeaways
3) Full comprehensive summary and analysis, containing every useful point and example