By |Published On: March 6th, 2015|Categories: Book Reviews|

Book Overview

Anyone involved in business has observed that certain products, services or ideas seem to catch on and become wildly popular.

Others ideas fall flat.

Why do some ideas fail to achieve widespread acceptance despite being high quality, of good value, and endowed with hefty advertising budgets? What exactly are the shared intangibles that account for the runaway success of, say, a blog post that goes viral, or of Apple’s ubiquitous products?

Jonah Berger, who teaches marketing at Wharton, has thought about this question, and has conducted a lot of of research exploring it, in areas ranging from car purchases to YouTube videos. Based on this analysis, Berger has identified the critical factors that drive the success and popularity of things that tend to catch on in our society. The results of his work can be distilled into a few core ideas, which he explores in a captivating book, “Contagious: Why Things Catch On.”
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In order for something to become popular and spread effectively, especially socially or through word of mouth, people have to want to share it, and as it turns out there are a handful of common attributes that highly popular things have in common that induce people to share them with others. These attributes, to varying degrees, are what make something contagious.

What I like about the book?

In general, I found the book to be well-organized, with clear explanations, and Berger adds a lot of good applied examples to demonstrate the concepts. I also enjoyed how Berger explained the research process at a high level and the evolution of his thinking as the ideas crystallized. Berger lays out his framework using a helpful acronym, “STEPPS,” to assist readers in recalling the basic ideas.

STEPPS stands for: Social Currency, Triggers, Emotion, Public, Practical Value, and Stories. Berger devotes a chapter to each category he has identified.

Social Currency. In financial markets, currencies represents a store of value, and a medium of exchange. Social currency is similar in that it represents knowledge that has value and is shared within social groups. As naturally social animals, we enjoy being perceived as witty, informed and entertaining, and so we often transact in social currency. We forward that quirky news item in an email. We tell our friend about the cool new restaurant that opened up downtown. Sharing like this makes us feel good about ourselves, and contributes to a sense of participation in, and of belonging to a community. Plus, people just inherently love to share their own preferences, opinions, and experiences.

Triggers. What is it that drives people to continue to talk about  certain things more than others? Berger discusses how at first, he thought perhaps people preferred to talk about thing that were just more, well, interesting. And although when people were fascinated by something, it did generate immediate word of mouth, these conversations were not ongoing, but instead petered out. What did generate continued word of mouth was whether an idea was “top of mind,” and easily recalled, especially when it was reinforced via a trigger. A trigger is a kind of environmental cue that drives us to remember thing that are related. For instance, Budweiser’s “Wassup” commercials used this common greeting to drive beer sales. Effective triggers cause things to remain top of mind and drive continued conversations.

Emotion. In an effort to explore the “why” of viral posts, Berger researched the most shared and emailed articles, using New York Times articles as research data. Berger first observed that some of the most heavily distributed articles tended to evoke a particular emotion: awe. A classic example: many will remember Susan Boyle, a rather plain woman who auditioned for Britain’s Got Talent. The audience practically laughed at her, and the judges rolled their eyes, but when she started singing, jaws dropped. Her performance video went viral, with total views now at 165 million. At first, Berger thought this suggested that positive emotions drove sharing, but it turned out specific negative emotions were even more effective. The reason? It was physiological arousal – excitement, amusement, anger, anxiety – that drove the effect. The physiological response drives people to become more emotionally involved and act. What this suggests this is that if we want our communications to be more likely to spread or go viral, we need to provoke an emotional, preferably physiological reaction.

Public. Another factor that drives sharing and use is public visibility. A product or idea gets picked up by more people to the extent that it can be seen or viewed by others. A related concept is that of “social proof,” a psychological concept, in which people form judgments when they observe the actions of others. When we see something in the public sphere, we reason since others have adopted it, it may be a good idea, and we are more likely to use or adopt it ourselves. For example, in Denver, when people had purchased a specific type of car, more of that car type tended to be sold subsequently. This is also a variation on herding, when animals group together for safety.

Practical Value. Another reason we are likely to share things is when they have practical value, and are applicable to our daily lives. We naturally want to help others, and when we see an idea that can make life easier for others, for instance by saving time or money for them, we tend to share it. Berger highlights Vanguard’s monthly email, which includes personal finance tips. Many of these tips are useful, and so people tend to send them to others, and Vanguard’s name gets spread in the process.

Stories. Humans crave stories, since stories provide us with a deeper understanding of our world. And stories can contain embedded meaning and messages. Berger suggests that, in order to create an effective communication that will spread, we build a story that has the elements of a Trojan horse. That is, a story should have features which are part of the telling that convey our intended message. He provides the example of Subway’s Jared Fogle, who lost 245 pounds eating Subway sandwiches. Losing the weight is a news item itself, but the fact that he did so while eating only Subway products is extraordinary.

Constructive Criticism

I thought the book was a little short considering the broad range of issues Berger tried to tackle. You could probably write a book on each chapter, yet some chapters were a mere 20 pages long. I thought this led to him glossing over some concepts. Berger could have shared more from his deep experience acquired from exploring these topics.

Additionally, while there is undoubtedly a lot of good research underlying the ideas, Berger didn’t devote a lot of space to sharing this, which was puzzling to me. Perhaps this is a result of trying to market relatively technical and wonkish academic material to a mass market paperbook crowd. Or perhaps he was rushing to generate text in order to get the book finished and into the publisher’s hands. Regardless, I had hoped for more analysis and content similar to the insights he publishes in the Journal of Marketing Research and other top-tier marketing science journals. It felt like the book was an academic “lite” treatment of some subjects. But perhaps the book publisher was targeting a crowd more interested in good stories and less interested in the nuance details of the data. Who knows.


Overall, “Contagious” is a great overview of the primary features that drive things to spread in a viral way. Reading over some uncharitable reviews on Amazon, I saw that some felt Berger’s observations were “obvious,” and “common sense.”

I disagree.

Deep truths can seem obvious when someone smart simplifies them for us, but the process of actually identifying them is not a trivial one. For example, the observation that physiological arousal causes sharing might seem obvious in retrospect, but no one had previously been able to demonstrate this empirically via experimentation. It might have turned out not to be true. So these are valuable insights. While it reads easily, has a light tone, and is highly accessible, there is solid research behind a lot of this book.

Plus, the book has good practical value which, as a key feature of things we tend to share, perhaps contributed to its success. The book can be viewed as a good road-map for anyone seeking to increase the chances that their political idea, consumer product, or blog content will catch on, spread, and be shared by people. The concepts are immediately applicable for anyone trying to generate buzz, and are especially relevant in today’s highly connected world. Also, the book was a New York Times Bestseller, which is pretty good social proof.

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About the Author: David Foulke

David Foulke
David Foulke is an operations manager at Tradingfront, Inc., a provider of automated digital wealth management solutions. Previously, he was at Alpha Architect, where he focused on business development, firm operations, and blogging on quantitative investing and finance topics. Prior to Alpha Architect, he was involved in investing and strategy at Pardee Resources Company, a manager of natural resource and renewable assets. Prior to Pardee, he worked in investment banking and capital markets roles at several firms in the financial services industry, including Houlihan Lokey, GE Capital and Burnham Financial. He also founded two internet companies, E-lingo, and Stonelocator. Mr. Foulke received an M.B.A. from The Wharton School of the University of Pennsylvania, and an A.B. from Dartmouth College.

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For informational and educational purposes only and should not be construed as specific investment, accounting, legal, or tax advice. Certain information is deemed to be reliable, but its accuracy and completeness cannot be guaranteed. Third party information may become outdated or otherwise superseded without notice.  Neither the Securities and Exchange Commission (SEC) nor any other federal or state agency has approved, determined the accuracy, or confirmed the adequacy of this article.

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