Contagious – Complete Book Summary & All Key Ideas

Quick Orientation

“Contagious: Why Things Catch On” by Jonah Berger explores the science behind why certain products, ideas, and behaviors become popular and spread. Contrary to common belief that virality is random or solely driven by expensive advertising or influential people, Berger argues that there are underlying principles that make things contagious. Drawing on over a decade of research, the book distills these principles into a practical framework called STEPPS, explaining how anyone can use these insights to make their own offerings catch on, whether it’s a product, a social cause, or an idea. This summary will cover every major idea presented, ensuring a complete understanding of the STEPPS framework and the psychological drivers of social transmission.

Introduction: Why Things Catch On

This introduction sets the stage by highlighting the surprising success of things like a $100 cheesesteak or specific YouTube videos, questioning why some things catch on while others fail, even with significant marketing budgets. It challenges conventional wisdom about quality, price, and advertising being the sole drivers of popularity and introduces the critical role of social transmission.

The Power of Social Transmission

People’s natural inclination to share information with others is a significant factor in driving popularity. This social influence is often more effective than traditional advertising due to its persuasiveness and targeted nature.

Frequency and Importance: People share information constantly throughout their day, discussing brands, news, and personal experiences, with word of mouth influencing a large percentage of purchasing decisions.
Word of Mouth Effectiveness: Word of mouth is more persuasive than advertising because friends are seen as more credible and objective than company claims.
Targeted Reach: People tend to share information with those they believe would find it relevant, making word of mouth naturally targeted to interested audiences.
Economic Impact: Word of mouth directly translates to increased sales and customer value; referred customers spend more and are more profitable.
Accessibility: Generating word of mouth doesn’t require a massive advertising budget; it relies on understanding why people talk and share.

Challenging Conventional Wisdom

The idea that popularity is driven by a few influential people or that virality is random is questioned. The focus shifts from the messenger to the message itself.

Influence of the Messenger: The book argues that while influential individuals exist, the inherent contagiousness of the message is often more important than the messenger’s popularity or persuasiveness.
Randomness of Virality: The success of viral content is not simply random; specific characteristics and principles make some things more likely to be shared than others.
Limitations of Humor and Cuteness: While funny or cute videos can go viral, these qualities alone are not sufficient, as many such videos never gain traction.
Necessity of Looking at Failures: To understand what causes sharing, it’s crucial to study both successful and unsuccessful content, not just the outliers.

Can Anything Become Contagious?

The question is posed whether some things are inherently more likely to catch on or if contagiousness can be engineered into any product or idea.

Inherent Versus Engineered Contagiousness: While some products (like smartphones) seem more exciting than others (like blenders), any product or idea can be made more contagious by applying the right principles.
The Viral Blender: The case of Blendtec’s “Will It Blend?” series demonstrates that a seemingly boring product can achieve massive virality and sales growth with a low budget by highlighting its unique qualities.

The Six Principles of Contagiousness (STEPPS)

The introduction concludes by introducing the core framework of the book: six principles that make products, ideas, and behaviors more likely to spread.

Social Currency: We share things that make us look good.
Triggers: Environmental cues remind people to think and talk about things.
Emotion: When we care, we share; high-arousal emotions drive transmission.
Public: Observable things are easier to imitate and spread.
Practical Value: Useful information gets shared to help others.
Stories: Narratives carry information and messages along with them.

The introduction establishes that understanding the science of social transmission is key to making anything catch on, whether for commercial success, social change, or personal goals.

1. Social Currency

This chapter explores the first principle of contagiousness, explaining that people share things that make them look good to others. Sharing serves as a form of social currency, allowing individuals to achieve desired positive impressions among their peers.

Minting a New Type of Currency

The desire to share personal experiences and opinions is deeply ingrained, offering intrinsic rewards. What we choose to share influences how others perceive us.

Intrinsic Reward of Sharing: Studies show that disclosing information about oneself activates the same brain areas as rewards like food and money.
Willingness to Pay to Share: People are even willing to forgo monetary compensation for the opportunity to share their opinions.
Choices Signal Identity: The products we buy, the clothes we wear, and the places we go are interpreted by others as signals about our identity and who we are.
Sharing Shapes Impression: What we talk about influences whether others see us as witty, cool, or in the know.
Avoiding Negative Impressions: We tend to avoid sharing things that would make us or others look bad.
Word of Mouth as Social Currency: Talking about certain things is a prime tool for making a good impression on family, friends, and colleagues.
Minting Social Currency: Companies and organizations need to craft messages and design products that give people a way to make themselves look good while also promoting the offering.

Inner Remarkability

One way to create social currency is to make products, ideas, or information remarkable – unusual, extraordinary, or worthy of notice.

Remarkable Defined: Remarkable things are novel, surprising, extreme, or simply interesting.
Worthy of Remark: The most important aspect is that they are worth mentioning or talking about.
Snapple Facts Example: Putting surprising and entertaining facts under Snapple bottle caps made the brand remarkable and prompted sharing.
Making Sharers Seem Remarkable: Talking about remarkable things makes the person sharing the information seem more interesting, engaging, and in the know.
Correlation with Word of Mouth: Studies show that more remarkable products and articles get talked about more often and are more likely to be shared.
Shaping Story Evolution: Stories often become more remarkable as they are transmitted from person to person, with details exaggerated for entertainment.
Breaking Patterns: Generating surprise and remarkability can be achieved by breaking expected patterns or norms.
Applying Remarkability: Remarkability isn’t limited to inherently exciting things; it can be found or created in any product or idea.

Leverage Game Mechanics

Using game mechanics, such as points, levels, and leaderboards, can encourage sharing by providing visible symbols of status and achievement.

Game Mechanics Defined: Elements of a game, application, or program that make them fun and compelling through rules and feedback loops.
Internal Motivation: Game mechanics motivate by providing tangible evidence of progress and achievement, which makes people feel good.
Social Comparison Motivation: People care about how they are doing relative to others, and game mechanics facilitate this comparison.
Status and Hierarchy: People like feeling high status, and game mechanics can help them achieve and display this.
Doing Well Looks Good: Achieving success within a game or system provides social currency because people like boasting about accomplishments.
Boosting Word of Mouth: People talk about their achievements (e.g., airline status, game badges), and in doing so, they talk about the brands or domains where these achievements occurred.
Gamifying Products/Ideas: Leveraging game mechanics requires quantifying performance and creating systems that allow people to see and publicize their achievements.
Tangible Symbols: Visible symbols of status, like Foursquare badges or frequent flier tiers, make achievements more public and shareable.

Make People Feel Like Insiders

Creating a sense of scarcity and exclusivity can make people feel special and increase the social currency associated with accessing or knowing about something.

Scarcity Defined: Less available due to high demand, limited production, or time/place restrictions.
Exclusivity Defined: Accessible only to those who meet particular criteria, often involving knowledge or connections rather than just money.
Rue La La Example: This online flash sale site for high-end goods used invitation-only access and limited-time deals to create a sense of exclusivity and urgency, driving demand and word of mouth.
Please Don’t Tell Example: A hidden bar accessed through a phone booth created a sense of secrecy and exclusivity, making visitors feel like insiders.
Increasing Desirability: Scarcity and exclusivity make products seem more desirable because people assume that if something is hard to get, it must be worth the effort.
Inferring Popularity: Limited availability can lead people to infer that something is popular and thus good.
Boosting Word of Mouth via Insider Status: Getting access to something not everyone else has makes people feel unique and special, motivating them to share it and capitalize on the social currency of having insider knowledge.
Applying to Any Product: Even seemingly mundane products, like McDonald’s McRib, can leverage scarcity to generate excitement and word of mouth.

A Brief Note on Motivation

Monetary incentives can motivate action, but social incentives, like social currency, are often more effective in the long term because they tap into intrinsic human desires.

Intrinsic vs. Extrinsic Motivation: People are motivated by both internal rewards (like feeling good about an achievement) and external rewards (like money).
Crowding Out Intrinsic Motivation: Paying people to do something they might otherwise do for free can reduce their intrinsic motivation for that activity.
Social Incentives’ Long-Term Power: Social incentives, like the desire to look good or achieve status, can drive ongoing engagement and word of mouth without direct monetary cost.

This chapter demonstrates that by focusing on how products and ideas can make people look good (Social Currency), marketers and communicators can increase the likelihood of them being talked about and shared.

2. Triggers

This chapter explores the second principle, Triggers, which explains how environmental cues remind people to think about and talk about products, ideas, and behaviors. Being top of mind increases the likelihood of being tip of tongue.

Buzzing for BzzAgent

The chapter begins by highlighting the unexpected finding that products like Cheerios receive more word of mouth than exciting experiences like Disney World, suggesting that interest isn’t the only driver of talk.

The BzzAgent Model: This company mobilizes everyday consumers to try new products and share their honest opinions, demonstrating that ordinary people naturally talk about brands.
Frequency of Brand Mentions: Americans engage in numerous daily conversations about products, brands, and services without prompting.
Challenging the “Interest is King” Idea: Initial research on BzzAgent data showed no direct correlation between product interest levels and overall word of mouth generated.

The Difference Between Immediate and Ongoing Word of Mouth

The timing of word of mouth matters, and what drives immediate sharing isn’t necessarily what drives ongoing conversation.

Immediate Word of Mouth: Sharing information or experiences soon after they occur.
Ongoing Word of Mouth: Conversations that continue in the weeks and months after the initial experience.
Interest Drives Immediate Talk: Interesting products tend to get more immediate word of mouth.
Lack of Sustained Talk from Interest: Interesting things do not necessarily sustain high levels of word-of-mouth activity over time.

From Mars Bars to Voting: How Triggers Affect Behavior

Triggers, or stimuli in the environment, make related thoughts and ideas more accessible, influencing behavior.

Top of Mind Accessibility: At any given moment, some thoughts are more readily accessible than others.
Environmental Triggers: Sights, smells, sounds, and other cues can bring related concepts to mind.
Triggers Lead to Action: Accessible thoughts and ideas are more likely to translate into behavior.
The Mars Bar Example: NASA’s Pathfinder mission to Mars triggered thoughts of Mars candy bars, leading to an unexpected sales increase.
Music and Wine Choice: Background music in a supermarket can trigger associations with specific countries and influence the type of wine people purchase.
Healthy Eating Study: A slogan linking healthy eating to cafeteria trays successfully triggered students to eat more fruits and vegetables, even though they disliked the slogan itself.
Polling Location and Voting: The type of building used as a polling place (e.g., a school) can trigger related thoughts and influence how people vote on ballot initiatives (e.g., supporting school funding).
Triggers Drive Talking: Triggers make products and ideas more top of mind, increasing the likelihood that people will talk about them.

Triggered to Talk

Triggers are particularly important for driving ongoing word of mouth, as they provide regular reminders to think about and discuss a topic.

Beyond Social Currency: While social currency motivates some talk, much conversation is simply filling conversational space with whatever is top of mind.
Triggers and Ongoing Talk: More frequently triggered products receive more word of mouth, including ongoing buzz.
Ziploc Bags vs. Pirate Outfits: Mundane but frequently used products like Ziploc bags get more ongoing word of mouth than remarkable but infrequent events.
Top of Mind, Tip of Tongue: Triggers act as reminders that keep products and ideas top of mind, leading to them being talked about more often.
Considering Context: Instead of just focusing on a catchy message, think about how the message will be triggered by the target audience’s environment.
Triggers vs. Catchy Slogans: A strong trigger can be more effective at changing behavior than a memorable but untriggered slogan.
Importance for Delayed Behavior: Triggers are especially important when the desired action happens after a delay from when the message is received.
Negative Publicity as a Trigger: Even negative reviews or publicity can increase sales for unknown authors or products by simply making them top of mind.

Kit Kat and Coffee: Growing the Habitat

Ideas and products have “habitats” of triggers, and these habitats can be expanded by linking the product to prevalent environmental cues.

Idea Habitats: The set of triggers that cause people to think about a product or idea.
Natural Triggers: Some products have existing, natural associations with environmental cues (e.g., Mars bars and the planet Mars).
Growing the Habitat: Creating new links between a product or idea and frequently occurring stimuli in the environment.
Kit Kat and Coffee Example: Linking Kit Kat to coffee created a frequent trigger that revived sales, as coffee is consumed frequently throughout the day.
Pairing Ideas: Repeatedly pairing a product or idea with a specific trigger can forge a new association.
Competitors as Triggers: Adversaries’ messages or cues can be used as triggers for one’s own message, a strategy known as the poison parasite.

What Makes for an Effective Trigger?

Not all triggers are equally effective; their frequency and the strength of their association with the product or idea matter.

Frequency of Stimulus: More frequent triggers lead to more reminders and thus more word of mouth.
Strength of Link: The more distinct or unusual the association between a trigger and a product, the stronger the link and the more effective the trigger.
Contextual Relevance: Effective triggers occur near where the desired behavior is taking place, making it easier to remember the product or idea at the right time.
Timing is Crucial: Triggers need to bring the product or idea to mind at the moment when the relevant action is being considered or performed.

Why Cheerios Gets More Word of Mouth Than Disney World

Triggers explain why mundane products like Cheerios can generate more word of mouth than exciting ones like Disney World.

Cheerios’ Frequent Trigger: Eating breakfast every day provides a constant trigger for Cheerios.
Disney World’s Infrequent Trigger: Trips to Disney World are rare, leading to fewer triggers and less ongoing conversation.
Observable Patterns in Talk: Social media data shows that mentions of frequently triggered brands like Cheerios spike around the time of their typical consumption.

This chapter emphasizes that understanding and leveraging environmental triggers is crucial for keeping products and ideas top of mind and thus tip of tongue.

3. Emotion

This chapter explores the third principle of contagiousness: Emotion. It highlights that when people care, they share, and different types of emotions have different effects on transmission.

Most E-Mailed Lists and the Importance of Sharing

The chapter begins by examining why certain articles, even on seemingly dry topics like fluid dynamics, become highly shared online.

Online Sharing as Social Glue: The internet makes it easy to share content, allowing people to connect with others and maintain relationships.
Most-Shared Lists as Filters: These lists help people navigate the vast amount of online content by highlighting what others have found interesting or valuable.
Impact on Public Discourse: What makes these lists can influence what topics gain attention and shape public opinion.
Beyond Randomness: There are consistent patterns underlying which online content becomes widely shared.

Systematically Analyzing the Most E-Mailed List

Research systematically analyzed New York Times articles to identify characteristics linked to high sharing rates.

Initial Characteristics Examined: Article topic, interest level, and practical value were analyzed for their correlation with being on the Most E-Mailed list.
Interest and Usefulness Matter: Both interesting and useful articles were more likely to be highly shared, supporting intuitive ideas about what gets passed on.
The Science Anomaly: Science articles, despite sometimes lacking obvious social currency or practical value for a broad audience, were frequently among the most e-mailed.

The Power of Awe

The analysis revealed that a specific emotion, awe, was a key driver of sharing for science articles and other content.

Awe Defined: A sense of wonder and amazement inspired by confronting something greater than oneself.
Elicitors of Awe: Great knowledge, beauty, sublimity, or might can evoke awe.
Psychological Effects of Awe: Awe expands one’s frame of reference, drives self-transcendence, and often involves surprise or mystery.
Science Articles and Awe: Science articles often evoke awe by revealing surprising discoveries or explaining complex phenomena.
Awe Boosts Sharing: Statistically, awe-inspiring articles were significantly more likely to make the Most E-Mailed list.
Susan Boyle Example: The viral video of Susan Boyle’s performance on Britain’s Got Talent evoked awe through the unexpected contrast between her appearance and her incredible voice.

Does Any Emotion Boost Sharing?

The question is raised whether all emotions encourage sharing or if some have different effects.

Sharing Emotions Connects People: Telling others about emotional experiences helps us process those feelings and strengthens social bonds by highlighting shared reactions.
Positivity vs. Negativity: Conventional wisdom suggests negative news is more attention-grabbing, but people may prefer sharing positive things to make a good impression.
Positive Content Shared More: Analysis showed that positive articles were more likely to be highly shared than negative ones.
Conflicting Negative Emotion Results: While sadness decreased sharing, other negative emotions like anger and anxiety surprisingly increased sharing.

Kindling the Fire: The Science of Physiological Arousal

The key to understanding the different effects of emotions on sharing lies in physiological arousal – a state of activation and readiness for action.

Physiological Arousal Defined: A state of heightened activation characterized by increased heart rate, blood pressure, and alertness.
Arousal Drives Action: Arousal motivates behavior and prepares the body for action.
High-Arousal Emotions: Anger, anxiety, and excitement are high-arousal emotions that activate people.
Low-Arousal Emotions: Sadness and contentment are low-arousal emotions that tend to stifle action.
Arousal Boosts Sharing: Understanding arousal explains why anger and anxiety, like awe and excitement, increase sharing – they kindle the fire and motivate transmission.
Amusement is High-Arousal: Funny content is shared because amusement is a high-arousal emotion.
Sadness Decreases Sharing: Sadness stifles action and reduces the likelihood of sharing.
United Breaks Guitars Example: The video created by a musician about his negative experience with United Airlines evoked anger, a high-arousal emotion that drove virality and negative consequences for the company.

Focus on Feelings

Instead of just presenting information or facts, focus on evoking the underlying emotions that motivate people to act and share.

Information Is Not Always Enough: Simply providing facts about health risks or product features may not be sufficient to change behavior.
Emotion Motivates Action: Focusing on feelings can connect with people on a deeper level and drive them to talk, share, and buy.
Finding the Emotional Hook: Even for seemingly unexciting products or topics, it’s possible to find an emotional hook.
Google’s “Parisian Love” Example: This ad for Google Search humanized the product and built an emotional connection by telling a love story using evolving search queries, demonstrating that even a technical product can evoke emotion.
Using the “Three Whys”: Asking “Why is this important?” multiple times can help uncover the core emotional drivers behind an idea.

Kindling the Fire With High-Arousal Emotions

When designing content for sharing, choose emotions that are high in arousal to motivate transmission.

High-Arousal Emotions for Sharing: Excite or inspire on the positive side; make people angry or anxious on the negative side.
Adding Arousal Increases Sharing: Even simply increasing the level of arousal in a story or ad can significantly boost the willingness to share.
Negative Emotions Can Boost Word of Mouth: Used correctly, negative emotions like anger, anxiety, or disgust can drive discussion and transmission.
BMW’s “The Hire” Example: This series of short films for BMW evoked fear and anxiety, high-arousal emotions that drove millions of views and increased sales.
Disgust as a Driver: Disgust, a highly arousing negative emotion, can also encourage talking and sharing.

Babywearing, Boycotts, and Blunting Bad Buzz

Understanding how arousal fuels transmission can help predict which negative events or rumors will spread and how to manage them.

Social Media Amplifies Emotion: Technology makes it easier for emotional content to spread and organize people around shared feelings.
Predicting Negative Spread: Negative content that evokes high-arousal emotions (like anger or anxiety) is more likely to escalate and go viral than low-arousal negativity (like sadness).
Motrin Boycott Example: A Motrin ad that offended mothers sparked a widespread boycott fueled by anger, a high-arousal emotion amplified by social media.
Monitoring Arousing Negative Emotions: Companies can mitigate negative buzz by monitoring online chatter for high-arousal negative words and addressing issues before they escalate.

Exercise Makes People Share

Physiological arousal from any source, not just emotion, can increase the likelihood of sharing information.

Arousal from Physical Sources: Activities like exercise or stressful situations can induce physiological arousal.
Arousal Boosts Transmission: Studies show that physiological arousal, even when not tied to specific emotions, increases people’s willingness to share information.
Oversharing and Arousal: Arousing situations can lead people to share more than they intended.
Timing and Context for Ads: Running ads during arousing moments in television shows or in physically activating environments (like a gym) can increase word of mouth for those ads due to elevated arousal levels.

This chapter concludes that by focusing on evoking emotions, particularly those high in arousal, marketers and communicators can significantly increase the contagiousness of their products and ideas.

4. Public

This chapter delves into the principle of Public, explaining that observable things are easier to imitate and therefore more likely to become popular. If something is built to show, it’s built to grow.

The Psychology of Imitation

People frequently imitate the behavior of those around them, often using others’ choices as information to guide their own decisions.

Imitation is Common: People conform to others’ styles, choices, and behaviors in various aspects of life.
Social Proof: We assume that if many people are doing something, it must be a good idea or the correct thing to do.
Reducing Uncertainty: In situations where we are unsure, we look to others’ behavior to help us decide.
Tip Jar Example: Baristas seed tip jars to create the impression that others are tipping, encouraging more tipping through social proof.
Herd Mentality: Social influence can lead people to follow the crowd, even in important decisions like choosing a restaurant or selecting a career path.
Initial Advantage Magnified: Even a small initial preference for something can be amplified through social influence as people observe others’ choices and follow suit.
Kidney Donation Example: Patients on a kidney waitlist are influenced by the number of people who have previously refused an offered kidney, sometimes turning down viable organs based on social proof.

The Power of Observability

Imitation can only happen when behavior is observable. Making products, ideas, or behaviors more visible is crucial for increasing social transmission.

“Monkey See, Monkey Do”: People can only imitate actions they can see others performing.
Public vs. Private Behavior: Many behaviors and choices are private (e.g., toothpaste choice, voting), making them less susceptible to social influence compared to public behaviors (e.g., car driven, clothes worn).
Observability and Influence: Studies show that social influence on purchases is stronger in environments where others’ choices are more easily observed.
Public Visibility Boosts Talk: Observable things are more likely to be noticed and discussed, increasing word of mouth.
Observability Spurs Action: Visible cues in the environment can trigger reminders and prompt people to take action they may have intended to do.

Making the Private Public… With Moustaches

A key strategy for leveraging the Public principle is to transform private choices, actions, or opinions into publicly observable signals.

Private Support: Support for causes or organizations is often private and unobservable, limiting social influence.
Movember Example: The Movember Foundation made support for men’s cancer research public by encouraging men to grow moustaches during November, turning participants into visible advocates.
Visible Signals Generate Discussion: A sudden change in appearance, like growing a moustache, attracts attention and prompts conversations about the cause.
Making the Private Public: Creating public signals for previously unobservable behaviors or preferences.
College Drinking Example: Making the actual, less frequent drinking norms public (through ads stating that most students drink moderately) reduced binge drinking by correcting the misperception that everyone else was bingeing.
Behavior is Public, Thoughts are Private: People may behave a certain way because they observe others doing it, even if their private thoughts or preferences differ; making private thoughts public can correct these misperceptions.
Addressing Pluralistic Ignorance: When a group privately rejects a norm but incorrectly believes others accept it, making the private rejection public can shift the perceived norm and reduce the behavior.

Advertising Itself: Sharing Hotmail With the World

Designing products or ideas that inherently advertise themselves through their usage makes them more public and facilitates social proof.

Products as Billboards: When people use a product, that usage becomes a public display of the product.
Hotmail Signature: Including a link and message promoting Hotmail at the bottom of every outgoing email turned users into passive advertisers.
Passive Endorsement: Using a product publicly provides social proof and an implicit endorsement to potential new users.
Prominent Branding: Large logos or distinctive patterns on products make the brand more visible and recognizable.
Distinctive Features: Unique shapes, sounds, or colors (like Apple’s white headphones) can make products stand out and be instantly recognizable, facilitating social proof.
Behavioral Residue: Creating physical traces or remnants that stick around even after the product is used makes the behavior more observable over time.
Benefits for Limited Budgets: Designing products that advertise themselves is a powerful strategy for smaller companies or organizations without large advertising budgets.

Livestrong Wristbands as Behavioral Residue

Behavioral residue makes private actions, like donating to a cause, publicly visible, providing social proof and reminders.

Making Private Public: Behavioral residue allows others to see evidence of behaviors or preferences that would otherwise be hidden.
Livestrong Wristband Example: The yellow wristband made support for cancer research and Lance Armstrong visible, turning wearers into walking billboards for the cause and generating social proof.
Durability of Residue: Some forms of behavioral residue, like wristbands or reusable shopping bags, persist longer than the action itself.
Facilitating Imitation and Talk: Publicly visible remnants prompt discussion and make it easier for others to imitate the behavior or purchase.
“I Voted” Stickers: These stickers turned the private act of voting into a public signal, reminding others to vote and providing social proof that people were participating.
Reusable Shopping Bags: Reusing branded shopping bags provides ongoing public visibility for the retailers.
Giveaways as Residue: Promotional items that are used publicly serve as behavioral residue, increasing awareness and discussion of the brand or organization.
Online Behavioral Residue: Online actions like Liking something on Facebook or sharing activity on platforms like Spotify leave a digital trail that others can see, providing social proof and promoting the content or brand.

Anti-Drug Commercials?

Making something public can have unintended negative consequences if it inadvertently promotes the undesirable behavior by making it seem common or normal.

Highlighting Negative Norms: Campaigns that focus on how many people engage in an undesirable behavior can inadvertently increase that behavior by providing social proof that it is common.
“Just Say No” Example: Anti-drug ads intended to discourage drug use may have increased it by making teens aware that many of their peers were using drugs.
Illegal Downloads Example: Music industry warnings about the prevalence of illegal downloading may normalize the behavior and reduce the perceived need to pay for music.
Making the Public Private: To discourage a behavior, focus on reducing its observability or highlighting the positive alternative rather than the negative norm.
Petrified Wood Example: Signs in a national park stating that many visitors steal wood increased theft, while signs focusing on preservation decreased it.

This chapter demonstrates the critical role of public visibility in driving the spread of products, ideas, and behaviors. By making things observable and creating behavioral residue, we facilitate imitation and increase word of mouth.

5. Practical Value

This chapter focuses on the principle of Practical Value, explaining that people share information that is useful and helpful to others. News that others can use is highly contagious.

Saving a Couple of Bucks

Saving money is a key form of practical value that motivates sharing. Understanding the psychology of deals is crucial for making offers seem valuable enough to pass along.

Saving Money as Practical Value: Getting a discount or a better deal is a common and appreciated form of helpful information.
Sharing Good Deals: People are motivated to share promotional offers that seem particularly good or surprising.
Size of Discount Matters: Larger discounts tend to be more appealing and shareable.
Psychology of Deals: How people perceive the value of a deal is not always based on absolute terms but influenced by psychological principles.

The Psychology of Deals

Prospect theory explains how people evaluate potential gains and losses relative to a reference point, influencing their perception of deals.

Evaluation Relative to Reference Point: People assess the value of something based on their expectations or a comparison standard rather than its absolute worth.
Reference Points Influence Perception: A price or discount seems good or bad depending on what people expected to pay or receive.
Infomercial Example: Infomercials set a high initial “expected” price to make the final discounted price seem like a much better deal.
Listing Original Price: Retailers often list the “regular” price alongside the sale price to create a high reference point and make the discount seem larger.
“On Sale” Label Effect: Simply labeling something as “on sale” can increase demand, even if the price hasn’t changed, because it triggers the perception of a good deal.
Diminishing Sensitivity: The impact of a change (like a discount) is smaller the farther it is from the reference point; saving $10 on a $35 item feels more significant than saving $10 on a $650 item.

Highlighting Incredible Value

Making a deal seem remarkable or surpass expectations increases its perceived practical value and shareability.

Cutting Through the Clutter: With constant promotional offers, deals need to stand out to be shared.
Surpassing Expectations: Offers that are surprising or better than what people anticipated are more likely to be passed along.
Availability Restrictions: Limiting the time or quantity of an offer can make it seem more valuable by implying high demand or special status.
Limited-Time Offers: Deals available for only a short period create urgency and suggest that the offer is exceptionally good.
Quantity Limits: Restricting the number of discounted items a customer can buy can increase sales by making the promotion seem more valuable and in demand.
Exclusivity and Perceived Value: Deals available only to a certain group of people (e.g., loyalty members) can seem more valuable due to their exclusivity.

The Rule of 100

This rule provides a simple guideline for determining whether to frame a discount as a percentage off or a dollar amount off to make it seem larger.

Framing Discounts: Offers can be expressed in absolute dollar amounts or relative percentages.
Price Point Matters: Whether a percentage or dollar discount seems larger depends on the original price of the product.
Rule of 100 Application: For products priced under $100, percentage discounts seem larger. For products priced over $100, dollar discounts seem larger.

More Than Money

Practical value isn’t just about saving money; it also includes providing useful information that helps people improve their lives in other ways.

Useful Information is Shareable: Advice that saves time, improves health, or enhances experiences is valuable to others.
Sharing as Helping: Passing along useful information is a way to assist friends, family, and colleagues.
Strengthening Social Bonds: Sharing helpful information demonstrates care and strengthens relationships.
Practical Advice as Advice: People seek and share information and advice to navigate decisions and improve outcomes.
Packaging Information: How useful information is presented can affect its shareability; short lists, tailored advice, and clear summaries are often more effective.
Targeting the Audience: Content that is highly relevant to a narrow audience can be more viral than broadly relevant content because it strongly calls to mind specific individuals who would benefit from it.

A Note on Truth

The desire to share helpful information is so strong that it can lead to the spread of false information if it is perceived as practically valuable.

False Information Spreads: Even inaccurate information can go viral if people believe it is useful and want to help others.
Vaccine-Autism Example: The false link between vaccines and autism spread rapidly because parents perceived the information as useful for protecting their children.
Verifying Information: It’s important to verify the accuracy of information before sharing it, as false information can have negative consequences.

This chapter concludes that highlighting the practical value of products and ideas, whether through monetary savings or useful information, is a powerful driver of word of mouth and contagiousness.

6. Stories

This chapter explores the final principle of contagiousness: Stories. It explains that people don’t just share information; they tell stories, and these narratives act as vessels that carry products, ideas, and messages along with them.

Stories as Vessels

Stories are inherently engaging and memorable, serving as a powerful way to transmit information, lessons, and morals.

Original Entertainment: Stories were historically a primary form of entertainment and cultural transmission.
Engrossing Narratives: Stories have a beginning, middle, and end that capture attention and keep listeners engaged.
Embedding Information: Stories carry underlying messages, lessons, or information along with the narrative.
The Trojan Horse Example: The story of the Trojan Horse, while entertaining, carries the important lesson “Beware of Greeks bearing gifts.”
Fairy Tales and Fables: Many classic stories embed morals and practical lessons within their narratives.
Everyday Stories: The stories people tell in daily conversation also carry information, often practical advice or experiences.
Hidden Nuggets of Knowledge: Seemingly simple stories can contain a wealth of useful information woven into the narrative.
Stories as Carriers: Narratives serve as vehicles that make information easier to remember and transmit to others.

Learning Through Stories

Stories are an effective way to learn, providing vivid and engaging insights into how the world works and what is important.

Efficient Knowledge Acquisition: Stories offer a quick and easy way to gain knowledge compared to trial and error, direct observation, or advertisements.
Proof by Analogy: Stories about others’ experiences provide a form of social proof, suggesting that similar outcomes are possible.
Less Argument Against Stories: People are less likely to argue against personal stories than against direct claims or advertisements.
Overcoming Skepticism: The engaging nature of stories can bypass people’s natural skepticism toward persuasive attempts.
Psychological Cover: Stories provide a way for people to talk about products or ideas without feeling like they are simply advertising.
The Jared Story: The narrative of Jared Fogle losing weight by eating Subway sandwiches was highly contagious because it was a remarkable story, and it embedded key information about Subway’s healthy options within the narrative.
Information Under the Guise of Idle Chatter: The magic of stories is that important information is transmitted while people are focused on the entertaining narrative itself.

Build a Trojan Horse

To leverage the power of stories, marketers and communicators need to craft compelling narratives that people want to share, ensuring that the product or idea is an integral part of the story.

Crafting a Carrier Narrative: Create a story that captures attention and is likely to be retold.
Embedding the Message: Weave the product, idea, or desired message directly into the fabric of the narrative.
Dove’s “Evolution” Example: This video, part of Dove’s “Campaign for Real Beauty,” told a powerful story about unrealistic beauty standards, and by addressing an emotional issue, it created a compelling narrative that people wanted to share, benefiting the Dove brand which was embedded in the discussion.
Tapping into Existing Conversations: Connect the product or idea to topics or issues that people are already thinking or talking about.
Viral Because of the Story, Not Just the Product: The story itself needs to be interesting enough to be shared independently of the product it promotes.

Making Virality Valuable

It’s not enough for a story to go viral; it must also be valuable to the sponsoring company or organization by ensuring the brand is linked to the narrative.

Beyond Mere Attention: Viral content needs to benefit the brand or idea it is intended to promote.
Unrelated Content Failure: Viral content that has no intrinsic link to the product or idea (e.g., the “fool in the pool” stunt for a casino, Evian’s “Roller Babies”) may generate attention but not benefit the brand.
Brand as Integral to the Story: Virality is most valuable when the brand or product benefit is essential to telling the story.
Panda Cheese Example: The “Never Say No to Panda” commercials were highly viral because they were funny, but the brand was inseparable from the humor and the core message (“Never say no to Panda”), making the virality valuable.
Blendtec’s Valuable Virality: The “Will It Blend?” videos demonstrated the blender’s power in a remarkable way, and this benefit was central to the stories, making the virality valuable for Blendtec.

What Makes Story Details Stick?

Certain details within a story are more likely to be remembered and transmitted than others. Critical details relevant to the main point tend to persist.

Story Transmission and Change: As stories are passed along, some details are lost, while others are exaggerated or retained.
Sharpening Around the Main Point: Stories tend to become shorter and more focused on the core message or key details during transmission.
Critical vs. Extraneous Details: Details that are essential to the narrative’s plot or underlying message are more likely to stick than irrelevant details.

This chapter concludes that by building compelling narratives (Trojan Horses) that embed products, ideas, or messages as integral to the plot, communicators can leverage the power of stories to make their offerings contagious and ensure the virality is valuable.

Epilogue

The epilogue revisits the principles of contagiousness through the lens of how certain immigrant groups came to dominate specific niche businesses, illustrating how the STEPPS framework applies beyond typical marketing examples.

The Story of Vietnamese Nail Salons

The story of Vietnamese refugees entering and eventually dominating the nail salon industry in the United States provides a compelling real-world example of social transmission.

Unexpected Origin: The trend started with a small group of Vietnamese women refugees learning manicuring skills from actress Tippi Hedren.
Spread Through Social Ties: Success stories spread through the Vietnamese community, influencing others to enter the business.
Dominance in the Industry: Over time, Vietnamese Americans came to make up a vast majority of nail technicians in California and a significant portion nationwide.

Applying the STEPPS to Immigrant Businesses

The success of niche immigrant businesses, like Vietnamese nail salons, Cambodian doughnut shops, and Korean dry cleaners, can be explained by applying the STEPPS framework.

Triggers: The frequent topic of finding employment among new immigrants served as a trigger to think about available job opportunities, including those pursued by others in their community.
Public: The visible success of friends and acquaintances in specific trades provided public proof that these businesses were viable and offered a path to economic stability.
Social Currency: Entering a successful business niche pursued by others in the community likely provided a sense of belonging and success, acting as social currency.
Practical Value: Sharing information about job opportunities, training, and business practices offered practical value to fellow immigrants seeking work.
Emotion: Stories of successful immigrants overcoming challenges and building new lives likely evoked positive emotions like hope and inspiration.
Stories: Narratives about individuals who found success in these businesses were shared within the community, carrying information about the opportunities and how to pursue them.

Any Product, Idea, or Behavior Can Be Contagious

The examples throughout the book demonstrate the broad applicability of the STEPPS framework.

Diverse Examples: The principles apply to a wide range of offerings, from physical products and services to social causes and behaviors.
Beyond Inherently Exciting Things: Even seemingly mundane things can be made contagious by applying the STEPPS.

Social Epidemics Driven by Products and Ideas, Not Just Influentials

The book challenges the notion that social epidemics are solely driven by a few highly influential individuals.

The Role of Everyday People: Contagious phenomena require the participation of many ordinary individuals who pass along the product or message.
Focus on the Message: The inherent characteristics of the product or idea (the message) are more important drivers of social transmission than the individual messenger’s influence.

Consistent Principles Drive Contagiousness

The epilogue reinforces that the same six principles consistently appear in contagious content across different domains.

The Recipe for Success: The STEPPS framework provides a set of ingredients that make products and ideas more likely to be talked about and shared.
Designing for Contagiousness: The STEPPS can be incorporated into the design of the product or idea itself, or into the messaging and marketing around it.

Applying the STEPPS

The epilogue provides a checklist for applying the STEPPS framework to any product or idea, encouraging readers to consider how each principle can be leveraged.

Social Currency: Does it make people look good to talk about it?
Triggers: What cues in the environment make people think about it?
Emotion: Does it evoke emotion, particularly high-arousal emotions?
Public: Is it easily observable, and can you make it more public?
Practical Value: Does it offer useful information or savings?
Stories: Is it embedded in a narrative people want to share?

The epilogue concludes that by understanding and applying these principles, anyone can harness social influence and word of mouth to make their products and ideas catch on, regardless of their budget or inherent “excitement” level.

Big-Picture Wrap-Up

“Contagious: Why Things Catch On” offers a comprehensive and practical framework for understanding and influencing social transmission. By moving beyond the intuitive but often insufficient explanations of price, quality, advertising, and influence, Jonah Berger reveals the psychological drivers that make people talk and share.

Core Lesson: Virality is not random; it is driven by six predictable principles (STEPPS) that can be applied to any product, idea, or behavior to increase its contagiousness.
Next Action: To make something catch on, analyze how it incorporates the STEPPS and actively work to build in more Social Currency, Triggers, Emotion, Public visibility, Practical Value, and embed it in Stories.
Reflective Question: Consider the last time you shared something with someone – which of the STEPPS most motivated you to pass it along?