Contagious

Chapter 1: Introduction: Why Things Catch On

Overview

Howard Wein’s hundred-dollar cheesesteak wasn’t just a gimmick—it was a lifeline. Opening a luxury steakhouse in Philadelphia, he knew that even the best food and atmosphere wouldn’t guarantee success. Most restaurants fail, and they can’t afford heavy advertising. They depend on word of mouth. So Wein engineered a conversation piece: a Kobe beef and lobster cheesesteak served with champagne, something so absurdly extravagant that people had to tell others about it. The media covered it, celebrities ordered it, and the buzz turned a risky venture into a lasting hit.

That story captures the central puzzle of why some things catch on while others don’t. Common explanations—quality, price, advertising—fall short. Baby names like Olivia and Rosalie are equally lovely, yet one dominates. Blurry home videos go viral while polished productions flop. The real driver is social transmission: word of mouth influences 20 to 50 percent of all purchasing decisions, and it’s far more persuasive than traditional ads because we trust friends and share with people who care. But there’s a surprising catch—only 7 percent of word of mouth happens online. Offline conversations dominate, and the visible frenzy of social media can be misleading. Posting content doesn’t guarantee sharing; most YouTube videos get fewer than 500 views. To harness word of mouth, we have to understand why people talk and what makes certain messages contagious.

Conventional wisdom focuses on finding the right influencers—mavens, connectors, salesmen. But that misses the bigger factor: the message itself. Some content is inherently viral, spreading regardless of who shares it. The question is whether anything can be made contagious. That’s where Tom Dickson and Blendtec come in. An engineer with a homemade flour grinder, Dickson and his marketing director George Wright created the “Will It Blend?” video series, blending marbles, iPods, and a rake handle. The series was so share-worthy that sales skyrocketed 700 percent. The lesson is clear: virality isn’t born, it’s made. Even a mundane blender can become a global sensation with the right approach.

Over a decade of research—studying baby names, New York Times articles, and face-to-face conversations—yielded a systematic framework: six principles called STEPPS. These are the ingredients that make content more likely to be shared and imitated. Social Currency means people share things that make them look good—remarkable products give the sharer status. Triggers are frequent environmental reminders that keep an idea top of mind and tip of tongue. Emotion fuels sharing; content that sparks high-arousal feelings like awe, anger, or amusement gets passed along. Public ensures that observable behavior is imitable—making products visible spreads them through social proof. Practical Value turns useful information into a gift people want to share. And Stories carry information inside narratives, so embedding a message deep in a story makes it impossible to tell without it. These principles aren’t a rigid recipe—they’re flexible tools to pick and choose. By applying them, even a boring old blender can become the talk of the internet.

Key Takeaways

• Virality is engineered, not accidental. Even mundane products can become contagious with the right strategy.
• Six principles (STEPPS) drive sharing: Social Currency, Triggers, Emotion, Public, Practical Value, and Stories.
• The principles are flexible. Use any combination that fits your context; you don’t need all six.
• Understanding the why behind sharing (not just the what) gives you actionable levers to make your ideas spread.

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Chapter 2: Chapter 1. Social Currency

Overview

The secret behind a bar hidden behind a vintage phone booth isn’t the cocktails—it’s the thrill of discovery. That bar, Please Don’t Tell, never advertises, yet every reservation vanishes by mid-afternoon simply because people have to share something exclusive. This is social currency: the value people gain from sharing something that makes them look good. The brain is wired to crave this. Harvard neuroscientists discovered that talking about ourselves lights up the same reward circuits as food or money—participants even took a 25 percent pay cut just to share their opinions. Stories get amplified in the telling, exaggerated to make the teller seem more remarkable.

Not everything starts out remarkable, but almost anything can be made so by breaking expectations. Snapple bottle caps become conversation starters, a $100 cheesesteak shatters assumptions, and a blender that pulverizes golf balls turns a mundane appliance into a talking point. The trick is to find the gap between expectation and reality and exploit it.

Game mechanics tap into people’s love of progress and status. Airlines turn purchases into levels and tiers, and passengers go out of their way for arbitrary thresholds because it feels like leveling up. Internal markers of achievement (punch cards, badges) combine with external social comparison—Harvard students preferred earning less money if it meant having more relative status. Making these achievements visible, like sharing airline upgrades or Foursquare badges, turns customers into free marketers. The best status systems are intuitive, like Olympic medals or traffic-light labels, so everyone instantly knows who’s winning.

Exclusivity is a powerful form of social currency. Rue La La sold the same products as a competitor but became a $350 million success by making shopping invitation-only and time-limited. Members felt like insiders and evangelized the site. The McRib became a cult phenomenon not because it was delicious but because it was elusive. Scarcity creates desire, but it works best when access feels earned—not impossible. Please Don’t Tell gives customers a discreet business card, making it easy to share the secret selectively, while the staff use a “no, but” strategy to maintain scarcity without turning people away.

Monetary incentives can actually backfire, crowding out the intrinsic joy of sharing. People will do a lot for status, recognition, and bragging rights—as fantasy football players prove by obsessing over rosters for no cash prize. Social incentives are far more sustainable and cost nothing. The entire chapter underscores that the most valuable currency isn’t money; it’s the feeling of looking good in front of others, earned through a well-designed secret, a clever badge, or a tastefully shared piece of insider knowledge.

Key Takeaways

• Monetary incentives can kill intrinsic motivation; social incentives (like looking good or feeling like an insider) are more durable and cost nothing.
• The perfect secret isn’t one that’s impossible to share—it’s one you give people the tools to share selectively (e.g., a discreet business card).
• Scarcity and exclusivity work best when coupled with a “no, but” strategy: maintain the difficulty but always offer an alternative or a path forward.

Chapter 3: Chapter 2. Triggers

Overview

Most people would bet on Disney World generating more word of mouth than a box of cereal. But the data tells a different story: Honey Nut Cheerios actually gets talked about more, and the reason isn’t that it’s more interesting—it’s that triggers keep it top of mind. Environmental cues—sights, sounds, smells, routines—shape what people discuss, buy, and even vote for, often without them realizing it.

The key insight comes from a study of BzzAgent campaigns, which found that interesting products generate a burst of immediate buzz but quickly fade, while products triggered by daily habits—like moisturizer or Ziploc bags—sustain ongoing conversation week after week. That’s because most everyday chatter isn’t about being clever; it’s about whatever happens to be top of mind. A brief mention of a product can even boost sales, as with a wine described as smelling like stinky socks. Triggers work by linking an idea to something people already encounter frequently, like coffee for Kit Kat or weekends for Michelob beer.

The power of triggers extends far beyond groceries. In one study, a corny slogan on cafeteria trays increased fruit and vegetable consumption by 25%, while a generic health message did nothing. More dramatically, people who voted in a school were significantly more likely to support a school-funding tax increase—the building itself triggered thoughts of education. Even negative attention can act as a trigger, as when an anti-smoking campaign spoofed Marlboro ads so that every sighting of the cowboy reminded people of emphysema.

To create an effective trigger, two factors matter most: frequency and link strength. The cue must appear often in the target audience’s environment—coffee works better than hot chocolate because people drink it year-round. But the link must also be unique; a cue associated with too many things (like the color red) loses its power. Timing is equally critical: a bath mat ad that only reminds you of the product while you’re in the shower—far from any store—misses the mark. The best triggers fire at the right place and moment, like a shopping list that goes with you out the door.

The chapter also examines what happens when triggers fail. The tip-of-the-tongue state—knowing you know something but not being able to retrieve it—reveals that triggers are not the information itself but the associative pathway leading to it. Changing your environment or waiting for a new cue often unlocks the memory, demonstrating that triggers are fragile, context-dependent, and require precise alignment of place, emotion, and attention.

Ultimately, triggers are the steady workhorse behind ongoing word of mouth. While social currency might get people talking initially, triggers keep them talking—by linking an idea to the everyday rhythms of life, from breakfast routines to the sight of a coffee cup to the simple act of opening a cabinet.

Key Takeaways

• Frequent triggers in the environment drive more word of mouth than clever or interesting messages.
• Expand an idea’s habitat by pairing it with common stimuli (e.g., Kit Kat and coffee).
• Effective triggers balance frequency with a strong, unique link—avoid overused cues.
• Timing matters: trigger the behavior at the right place and moment (e.g., shopping list for reusable bags).
• Even negative attention can boost awareness if it triggers a reminder.
• Context is everything—tailor triggers to the audience’s daily environments.

Chapter 4: Chapter 3. Emotion

Overview

The chapter opens with a puzzle: why did an article about cough photography become one of the most e-mailed stories of the day? The answer lies not in the topic’s utility but in the emotion it stirred—awe. That same awe drove millions to share Susan Boyle’s audition, and research tracking thousands of New York Times articles found that awe-inspiring pieces were 30 percent more likely to be shared. But not all emotions work the same way. Sadness actually decreased sharing by 16 percent, while anger and anxiety boosted it. The key difference is physiological arousal—the racing heart and sweaty palms that accompany anger, anxiety, and awe, but not sadness or contentment. High-arousal emotions create a fire that compels action; low-arousal ones power things down.

The “United Breaks Guitars” saga illustrates anger’s viral force, and Google’s “Parisian Love” ad shows how a romantic narrative can make search features emotionally compelling. The takeaway is to focus on feelings, not features—drill down to the emotional core by asking “Why is this important?” three times. When choosing emotions to drive sharing, pick those that kindle rather than smother: excitement and inspiration on the positive side, anger and disgust on the negative. Motrin’s babywearing ad backfired because it triggered mothers’ anger, a high-arousal negative emotion that spread like wildfire. Even physical activity matters: participants who jogged for sixty seconds were twice as likely to share an article, meaning that placing ads near exciting content or in gyms can boost word of mouth simply because people are already fired up.

Timing also plays a crucial role—crime shows peak in tension mid-episode, while game shows save the biggest arousal for the end, so advertisers need to align with those spikes. Ultimately, people share feelings, not facts. Abstract topics like fluid dynamics or online search become contagious when wrapped in an emotion that connects to people’s own lives. The goal isn’t to inform; it’s to ignite.

Denise Grady had been writing science for The New York Times for over a decade, but nothing prepared her for what happened on October 27, 2008. Her article about schlieren photography—a technique used to visualize disturbances in air—shot to the top of the paper’s Most E-Mailed list. On the surface, it made no sense. The piece lacked social currency, practical value, and seasonal relevance. Yet thousands of people hit forward.

Grady’s own origin story offers a clue. As a high school student, she struggled through Robert Millikan’s oil-drop experiment until it clicked—and that flash of understanding, that thrill of grasping something profound, hooked her for life. She became a journalist with a mission: to give readers even a sliver of that excitement. The cough article grew out of a photograph in The New England Journal of Medicine—a stunning image of a cough captured through schlieren photography. That image, and the awe it inspired, turned a technical topic into a viral phenomenon.

That finding didn’t come from guesswork. As a Stanford grad student, I started clipping the Wall Street Journal’s Most E-Mailed lists by hand, then automated the process with a web crawler that tracked The New York Times every fifteen minutes for six months. The resulting dataset—nearly 7,000 articles—let my colleagues and me test what really drives sharing beyond obvious factors like interest and usefulness. Science articles stood out: they lacked social currency and practical value, yet outperformed politics, fashion, and business. Why? Because they evoked awe.

We had research assistants score each article on how much awe it inspired. The result: awe-inspiring articles were 30 percent more likely to make the Most E-Mailed list. Think Susan Boyle’s Britain’s Got Talent debut—a frumpy woman with a voice that stopped time, racking up over 100 million views in nine days. Awe made people share.

But does any emotion boost sharing? We tested sadness and found the opposite: sad articles were 16 percent less likely to be shared. Positive articles fared better than negative ones overall—13 percent more shares. Then came the twist: anger and anxiety both increased sharing. So it wasn’t simply about positivity or negativity. Something else was at play.

That something is physiological arousal—the racing heart, sweaty palms, the feeling of being on edge. Awe, anger, and anxiety all activate the body; sadness deactivates it. And that activation, not the emotion’s pleasantness, may be the real key to getting people to click “send.”

Arousal: The Engine Behind Sharing

Physiological arousal—that state of heightened activation when your heart races and muscles tense—turns out to be the missing link that explains why some emotions drive sharing while others don’t. Whether it’s the adrenaline of anger, the flutter of excitement, or the chill of awe, high-arousal emotions kindle a fire that compels action. We want to do something: yell, run, tell someone. On the flip side, low-arousal emotions like sadness or contentment power things down. A sad person curls up on the couch; a content one relaxes. Neither feels much like passing along a story.

The "United Breaks Guitars" saga is a textbook case. Musician Dave Carroll’s $3,500 guitar was smashed by baggage handlers, and after nine months of runaround from the airline, he channeled his fury into a song. The video went viral—3 million views in ten days, a 10% stock price drop for United. The fuel wasn’t the facts of the case; it was the anger, a high-arousal emotion that made people want to share and vent.

Focusing on Feelings, Not Features

Facts alone rarely move people. Teens know smoking is bad; fast-food eaters know the health risks. What works is emotion. That’s why Google’s "Parisian Love" ad succeeded. Instead of a dry tutorial on search features, it told a love story through search queries—from "study abroad Paris France" to "how to assemble a crib." No people, no voiceover, just a series of searches that built a narrative. It was romantic and inspiring, and it made viewers want to pass it on. The lesson: find the emotional core of your idea by asking "Why is this important?" three times, drilling down to what people truly care about.

Kindling the Fire with High-Arousal Emotions

When using emotion to drive sharing, choose those that ignite action. On the positive side, excite or inspire. On the negative side, make people mad, not sad. BMW’s 2001 film series The Hire leaned into fear and anxiety with kidnappings and near-death experiences—and racked up 11 million views in four months. Public health messages work better when they evoke disgust (high arousal) rather than sadness (low arousal). The key is to stoke the fire, not smother it.

Babywearing and the Danger of Aroused Anger

Motrin learned this the hard way. A well-intentioned ad about the aches of babywearing offended mothers, who saw it as trivializing their parenting choices. Their anger—high arousal—spread like wildfire through blogs and Twitter, sparking a boycott and media coverage. The company had to pull the ad and apologize. The takeaway: negative high-arousal emotions are powerful. Monitor for words like "angry" or "pissed off" to catch a fire before it becomes a blaze.

Exercise Makes People Share

The arousal effect goes beyond emotion itself. In a simple experiment, participants who jogged in place for sixty seconds were more than twice as likely to share an article afterward as those who sat still. Physical arousal—even from running—spills over, making us more talkative. This explains why we sometimes overshare after a turbulent flight or a close call on the road. It also suggests that placing ads near exciting content (game shows, crime dramas) or at the gym can boost word of mouth, simply because people are already fired up.

Key Takeaways

• High-arousal emotions (anger, awe, excitement, anxiety) drive sharing; low-arousal ones (sadness, contentment) suppress it.
• Focus on feelings, not features—drill down to the emotional core of your idea.
• Physical arousal from exercise or intense experiences also boosts transmission.
• Monitor for high-arousal negative sentiment (anger, disgust) to prevent bad buzz from snowballing.

The precise moment of an ad’s appearance can make or break its impact. In crime shows, anxiety peaks mid-episode, with tension dissolving once the mystery is solved. Game shows, conversely, save the most arousing moment—the big reveal—for the end. If advertisers or content creators want people to talk about their message, they need to align with those spikes of activation.

Ultimately, emotion is what drives action. It’s what makes us laugh, shout, cry, and—crucially—share. Facts and statistics rarely light that fire. As Google designer Anthony Cafaro observed, people don’t want to be told something; they want to be entertained and moved. Even abstract topics like fluid dynamics or online search can become contagious when they’re wrapped in an emotion that connects to people’s own lives. Activating emotions—excitement, anger, even anxiety—fuel transmission far more than passive states like sadness. The goal isn’t to inform. It’s to ignite.

Key Takeaways

• Timing is everything: Place content or ads at the peak of emotional tension, not during moments of resolution or boredom.
• People share feelings, not facts: Emotional activation (arousal) drives transmission more than information alone.
• Make it personal: Abstract topics become shareworthy when tied to a viewer’s own life or underlying emotion.