Contagious: Why Things Catch On

by Jonah Berger

Wharton marketing professor Jonah Berger has studied why certain ideas and products get talked about and shared more than others. He refers to the “psychology of sharing” and identifies six common attributes: Social Currency, Triggers, Emotion, Public, Practical Value, and Stories.

Berger puts the hype of viral marketing in context. “Word of mouth is the primary factor behind 20 percent to 50 percent of all purchasing decisions.” However, “Research by the Keller Fay Group finds that only 7 percent of word of mouth happens online… So the first issue with all the hype around social media is that people tend to ignore the importance of offline word of mouth, even though offline discussions are more prevalent, and potentially even more impactful, than online ones. The second issue is that Facebook and Twitter are technologies, not strategies.”

Social Currency “People prefer sharing things that make them seem entertaining rather than boring, clever rather than dumb, and hip rather than dull.” Ways to create social currency include inner remarkability, game mechanics, and making people feel like insiders.

The book describes a bar called Please Don’t Tell, where people enter through a secret door in a telephone booth. “Please Don’t Tell has never advertised. Yet since opening in 2007 it has been one of the most sought-after dive reservations in New York City. It takes bookings only the day of, and the reservation line opens at 3:00 p.m. sharp. Spots are first-come, first served… By 3:30 all spots are booked.”

Triggers — “Triggers and cues lead people to talk, choose, and use. Social currency gets people talking, but Triggers keep them talking. Top of mind means tip of tongue.” An example is an advertising campaign promoting Kit Kat as a coffee break snack. Linking Kit Kat to coffee “created a frequent trigger to remind people of the brand.”

Emotion — “Emotions drive people to action. They make us laugh, shout, and cry, and they make us talk, share, and buy. So rather than quoting statistics or providing information, we need to focus on feelings.”

“Some emotions, like anger and anxiety, are high-arousal… Positive emotions also generate arousal. Take excitement… The same is true for awe. When inspired by awe we can’t help wanting to tell people what happened.

“Other emotions, however, have the opposite effect: they stifle action. Take sadness… Contentment also deactivates… On the negative side, make people mad, not sad.”

“These ideas also suggest that one way to generate word of mouth is to find people when they are already fired up.” Advertising on game shows reaches viewers in high-arousal state, compared with a documentary. “Ad timing also matters… In game shows, excitement—and therefore arousal—is highest when contestants are about to find out how much they’ve won. We may end up talking more about ads that show up close to these exciting moments.”

Public —Most people are more attracted to a busy restaurant than an empty one. “People often imitate those around them… Psychologists call this idea social proof.”

Observability has huge impact on whether products and ideas catch on… The easier something is to see, the more people talk about it. Observability also spurs purchase and action.” The author discusses examples of making “making the private public.”

Berger also explains behavioral residue. Livestrong wristbands have a life far beyond the bike ride. Event T-shirts are another example. “People posting their opinions and behavior online also provide behavioral residue. Reviews, blogs, posts, or other sorts of content all leave evidence that others can find later.”

“Communications professor Bob Hornik wanted to see whether anti-drug ads were actually effective.” They weren’t. “In fact, the messages actually seemed to increase drug use… If you want to get people not to do something, don’t tell them that lots of their peers are doing it.”

Practical Value “People like to pass along practical, useful information. News others can use.” This chapter includes discussion of prospect theory, sale prices, scarcity, and limited-time offers. “Retailers sometimes create limits around the number of a given discounted item a given customer can buy. ‘One per household’ or ‘Limit three per customer.’ … Indeed, research finds that quantity limits increase sales by more than 50 percent.”

Stories “People don’t think in terms of information. They think in terms of narratives. But while people focus on the story itself, information comes along for the ride… Virality is most valuable when the brand or product benefit is integral to the story. When it’s woven so deeply into the narrative that people can’t tell the story without mentioning it.” The author notes that Evian’s Roller Babies video “got more than 50 million views… That same year Evian lost market share and sales dropped almost 25 percent. The problem? Roller-skating babies are cute, but they have nothing to do with Evian. So people shared the clip, but that didn’t benefit the brand.”

Berger, Jonah. Contagious: Why Things Catch on. New York: Simon & Schuster, 2013. Buy from

Disclosure: As an Amazon Associate I earn from qualifying purchases.