Contagious: Why Things Catch On, by Jonah Berger (Simon & Schuster, 256 pp., $26)

If you’ve got an e-mail address, chances are you’ve been the recipient of a “you-have-got-to-read-this” message in the past few weeks. A link takes you to an article that your friend or colleague felt compelled to share. You wander over to Facebook and find the same article clogging your feed. Clearly, you’ve got a hot topic on your hands. But what makes some material buzz-worthy, and other material not?

That’s the question behind Jonah Berger’s new book, Contagious. Berger, a star marketing professor at the University of Pennsylvania’s Wharton School, has spent years studying why some content spreads from person to person across social networks and other media. In his research, he writes, “we kept finding the same ingredients in ads that went viral, news articles that were shared, or products that received lots of word of mouth.” The factors include, among other things, social currency (making the sharer look good), emotion (we share things that inspire awe or anger), practical value, and a good story. Add several of those ingredients, and you’ve got a good chance of making something catch on.

Berger is a serious student of the biggest business books of the past 15 years—he cites Malcolm Gladwell’s The Tipping Point and Chip and Dan Heath’s Made to Stick as influences—and he liberally employs the genre’s conventions. He gives us tales of cool businesses, like New York’s massively oversubscribed hipster bar, Please Don’t Tell, where you enter through a phone booth. He makes surprising (if in retrospect, obvious) connections: people are more likely to support initiatives involving public education when they do their voting in schools; kids shown ads about how to say no when cool kids ask them to do drugs will come to believe that cool kids do drugs—and be more likely to do drugs themselves. Showing his with-it credentials, he analyzes YouTube videos that have logged millions of downloads—like “Clean Ears Everytime,” the video of 86-year-old Ken Craig shucking corn, and the “Will it blend?” series from Blendtec, in which a powerful blender vaporizes marbles, an iPhone, and other objects.

Berger is best when citing studies—many of them his own—on subjects from the Most E-Mailed articles list at the New York Times to a fascinating public health campaign designed to get students to eat more produce. Students exposed to the slogan “Live the healthy way, eat five fruits and veggies a day” liked the message, but didn’t change their eating habits. They found another slogan, “Each and every dining-hall tray needs five fruits and veggies a day” corny and unattractive—but the image of a dining-hall tray provided what Berger calls a “trigger” to conjure the message every time students walked into the cafeteria. “The trays reminded them of the slogan and they ate 25 percent more fruits and vegetables as a result,” he writes. Using objects that people see every day can give any marketing campaign a powerful boost.

Berger is a serious academic, but his sometimes cloying use of anecdotes and PowerPoint-worthy acronyms (like STEPPS, for the components of a viral message), along with his almost self-conscious attempts to make the book fast-paced (with one-line paragraphs), wear thin eventually. He could have found ways to write for ordinary readers without sounding, occasionally, as though his book were the first draft of the keynote he’d be giving at sales conferences in Florida for the next ten years.

Nonetheless, Contagious is an intriguing look at why marketing works and, just as importantly, why it fails. When Ron Bensimhon crashed the 2004 Olympics and belly-flopped off the diving board with the name of an Internet casino,, on his chest, people talked about the event, but not about the company he appeared to be promoting. “When trying to generate word of mouth, many people . . . focus so much on getting people to talk that they ignore the part that really matters: what people are talking about,” writes Berger. In the end, messages still matter, no matter how slickly they’re packaged.


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