Summary Written by Carol-Ann Hamilton
“Maybe instead of giving people a penny for their thoughts, we should get paid a penny for listening.”

- Contagious, page 34

The Big Idea


"Top of mind means tip of tongue"- Contagious, page 79

Let’s start by defining the term contagious. Berger means: likely to spread; to diffuse from person to person and through social transmission; to be talked about, shared, or imitated by consumers, coworkers and constituents.

Together, six principles to crafting contagious content spell the acronym, STEPPS. Its components are as follows:

  1. Social Currency. Does talking about your product or idea make people look good and in-the-know? Can you make people feel like insiders?
  2. Triggers. How do we remind people to talk about our products and ideas? Triggers prompt people to think about related things (e.g., peanut butter/jam).
  3. Emotion. When we care, we share. We need to craft messages and ideas to get people to feel something. Sometimes even negative emotions kindle the fire.
  4. Public. Does your product or idea advertise itself? Can people see when others are using it? This one is akin to the phrase, “monkey see, monkey do”.
  5. Practical Value. How can you highlight incredible value and package your knowledge/expertise into useful information that stands out from the crowd?
  6. Stories. People don’t just share information, they tell stories. Like the Trojan horse, we need to embed our products/ideas into stories people want to recount.

Insight #1

The $100 Cheesesteak

"Word of mouth is the primary factor behind 20 percent to 50 percent of all purchasing decisions."- Contagious, page 7

The concept behind luxury boutique steakhouse, Barclay Prime, was to deliver the best experience imaginable. However with a typical 25% restaurant failure rate inside of twelve months, designer Howard Wein knew he needed to generate buzz. He needed to cut through the clutter, where in Philadelphia a standard cheesesteak is available for four to five dollars at hundreds of sandwich shops, burger joints and pizzerias.

To spare you lots of salivating, let’s just say the chef’s creation is topped with a butter-poached Maine lobster tail and served with a chilled split of premium champagne. People describe the delight as “eating gold.” Splashed across the media, Barclay Prime has not just survived against all odds but has built a following.

Even if people don’t order the “sandwich” they rave about the hundred-dollar cheesesteak because of these principles: Social Currency; Triggers (i.e., high frequency of cheesesteaks in Philadelphia); Emotions (very surprising); Practically Valuable (useful information about a high-quality steakhouse); all wrapped in a Story.

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Insight #2

“Clean Ears Every Time”

"Information travels under the guise of what seems like idle chatter."- Contagious, page 189

Ken Craig is 86 years old. Unlike most viral videos made by adolescents and watched by teens, his YouTube is about shucking corn.

One day, his daughter-in-law was over making dinner. Almost done cooking the main course, he showed her a trick to neatly prevent pesky corn silk strands from sticking to the husk. She was so impressed that the next day, they shot a clip of Ken in his kitchen, talking through his easy process to pop out the ear of corn – clean as a whistle. Along the way, she sent the video to a couple of friends.

Those friends sent it to a couple of friends, who also sent it to a couple of friends. Soon Ken’s “spot” collected more than 5 million views. Why the number?

People share practically valuable information to help others. If Social Currency is about information senders and how sharing makes them look, Practical Value is mostly about the information receiver. It’s about saving people time or money, or helping them have good experiences. It’s kind of like news you can use.

Let’s leave off with a few stunning statistics. People share more than 16,000 words per day and every hour there are more than 100 million conversations about brands. However, only 7% of word of mouth happens online. As well, we need to tap into the “right” emotions. “High arousal” ones such as awe, excitement and humor (even anger and anxiety) incite action while “low arousal” emotions like contentment or sadness are less apt to stir spirits or be passed along.

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Jonah Berger

Jonah Berger is the James G. Campbell Assistant Professor of Marketing at the Wharton School at the University of Pennsylvania. He has published dozens of articles in top-tier academic journals, and popular accounts of his work have appeared in places like The New York Times, the Wall Street Journal, The Washington Post, Science, Harvard Business Review, Wired, BusinessWeek, and Fast Company. His research has also been featured in The New York Times Magazine’s annual “Year in Ideas” issue. Berger has been recognized with awards for both scholarship and teaching, including being named Wharton’s “Iron Prof.” At Wharton, he teaches an elective called Contagious: How Products, Behaviors, and Ideas Catch On. He lives in Philadelphia, Pennsylvania.

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