Contagious: Why Things Catch On by Jonah Berger

The Science of Virality: Key Lessons from Contagious: Why Things Catch On by Jonah Berger

Jonah Berger’s Contagious: Why Things Catch On, published in 2013, is a compelling exploration of why certain ideas, products, or behaviors spread like wildfire while others fade into obscurity. Drawing on behavioral science and real-world examples from viral YouTube videos to word-of-mouth marketing Berger unveils the six principles (STEPPS) that drive contagiousness: Social Currency, Triggers, Emotion, Public, Practical Value, and Stories. With clarity and wit, he demystifies the mechanics of virality, offering practical insights for marketers, entrepreneurs, and anyone curious about influence. This article distills 10 key lessons from the book, each accompanied by a quote from Berger, to reveal how to craft ideas that catch on. Whether you’re launching a product or sharing a story, these lessons will help you make your message stick.

1. Social Currency: Make People Feel Like Insiders

Berger’s first principle, Social Currency, suggests that people share things that make them look good smart, cool, or in-the-know. Ideas or products that give people status or a sense of exclusivity are more likely to be shared. For example, a speakeasy-style bar with a hidden entrance becomes shareable because it makes patrons feel like insiders. By designing experiences that boost social cachet, you encourage word-of-mouth. This lesson teaches us to craft messages that enhance the sharer’s reputation.  
“We share things that make us look good.”
This quote captures the core of social currency: people spread ideas that elevate their social standing.

2. Triggers: Link Ideas to Everyday Cues

Triggers are environmental cues that remind people of an idea or product, prompting them to talk about it. Berger explains how frequent, contextual triggers like the song “Sweet Caroline” playing at baseball games keep ideas top-of-mind. A product like Kit Kat became more shareable when tied to the trigger of coffee breaks with the slogan “Give me a break.” This lesson highlights the power of connecting your message to recurring cues in people’s lives.  
“Top of mind means tip of tongue.”
Berger’s phrase emphasizes how triggers keep ideas alive in conversations.

3. Emotion: High-Arousal Feelings Drive Sharing

Emotion is a key driver of virality, but not all emotions are equal. Berger notes that high-arousal emotions like awe, excitement, or anger spur action, while low-arousal emotions like sadness dampen it. For instance, Susan Boyle’s viral Britain’s Got Talent performance sparked awe, driving millions to share it. Crafting messages that evoke intense emotions increases their shareability. This lesson reminds us to tap into feelings that energize people to act.  
“When we care, we share.”
This quote underscores how emotional intensity fuels word-of-mouth.

4. Public: Make Behavior Visible to Others

Ideas spread when they’re observable, as public visibility encourages imitation. Berger uses the example of Movember, where men grow mustaches to raise awareness for men’s health visible facial hair sparks curiosity and conversation. Similarly, Apple’s white earbuds made iPod use conspicuous, signaling popularity. This lesson teaches us to design products or campaigns that are inherently visible to amplify their spread.  
“Making things more observable makes them easier to imitate, which makes them more likely to become popular.”
Berger highlights how visibility drives social influence and adoption.

5. Practical Value: Useful Content Gets Shared

People love sharing information that’s useful to others, as it boosts their social currency and helps their network. Berger explains why articles like “10 Ways to Save Money” or recipes go viral because they offer practical value. For example, a video demonstrating a clever kitchen hack is shared because it solves a problem. This lesson emphasizes creating content that is actionable and relevant to people’s lives.  
“People share things that are useful because it makes them seem helpful and caring.”
This quote reflects the social benefit of sharing practical information.

6. Stories: Wrap Ideas in Compelling Narratives

Stories are powerful vehicles for spreading ideas because they engage people emotionally and make messages memorable. Berger notes that effective stories carry a “Trojan Horse” effect, embedding a brand or idea within a narrative. For instance, Subway’s campaign about Jared Fogle’s weight loss journey spread because it was a compelling story, not just an ad. This lesson urges us to craft narratives that naturally carry our message.  
“Stories are like Trojan horses: they carry messages in a way that makes them stick.”
Berger’s metaphor illustrates how stories smuggle ideas into people’s minds.

7. Word-of-Mouth Trumps Traditional Advertising

Berger argues that word-of-mouth is far more effective than traditional advertising because it’s trusted and targeted. Only about 7% of word-of-mouth happens online; most occurs face-to-face, where personal recommendations carry weight. For example, a friend’s restaurant tip influences us more than a billboard. This lesson encourages businesses to focus on creating shareable experiences rather than relying solely on ads.  
“Word of mouth is the primary factor behind 20 to 50 percent of all purchasing decisions.”
This statistic from Berger underscores the unmatched power of personal recommendations.

8. The Power of Scarcity and Exclusivity

Scarcity makes things more desirable and shareable. Berger describes how limited-edition products, like a rare sneaker drop, create buzz because people want to talk about what’s exclusive. Similarly, “secret” menus at restaurants like In-N-Out Burger spark curiosity and conversation. This lesson teaches us to leverage scarcity to make ideas or products feel special, driving their spread.  
“When something is rare, people talk about it.”
Berger’s insight reveals how scarcity fuels social currency and virality.

9. Social Influence Shapes Behavior

People are heavily influenced by what others do, a concept Berger ties to social proof. When we see others adopting a behavior like wearing a Livestrong bracelet it signals acceptability, encouraging us to follow. Public campaigns, like anti-smoking initiatives, gain traction when they highlight widespread participation. This lesson emphasizes designing campaigns that showcase collective behavior to drive adoption.  
“Behavior is contagious because it provides information about what is normal or desirable.”
This quote highlights how social proof guides our actions and spreads ideas.

10. Simplicity Enhances Spreadability

Complex ideas struggle to spread, while simple, clear messages catch on easily. Berger explains that viral content often boils down to a single, memorable idea like Google’s minimalist homepage or a catchy slogan. Simplicity makes it easier for people to understand and share. This lesson urges us to distill our messages to their essence, ensuring they resonate and stick.  
“The simpler an idea, the easier it is to share.”
Berger’s principle underscores the power of clarity in making ideas contagious.

Conclusion

Contagious: Why Things Catch On offers a roadmap for understanding and harnessing the forces that make ideas spread. Jonah Berger’s six STEPPS principles: Social Currency, Triggers, Emotion, Public, Practical Value, and Stories, provide a practical framework for crafting messages that resonate and endure. From evoking awe to leveraging social proof, these 10 lessons reveal how to make products, ideas, or behaviors catch on in a crowded world. As Berger reminds us, “Virality isn’t random; it’s engineered.” Let this book inspire you to create content that sparks conversations and drives impact.