Hooked vs Contagious: Which to Read First?
Nir Eyal on building products people return to, and Jonah Berger on why ideas spread: two marketing and product classics, compared, with a launch-plan comparison, an ethics check and a suggested reading order.
Anyone who builds, markets or launches something eventually meets two questions. How do we get people to notice and talk about it? And once they have tried it, how do we give them a reason to come back? Two popular books each take one of those questions seriously. Jonah Berger’s Contagious (2013) looks at why some ideas, products and messages get passed from person to person. Nir Eyal’s Hooked (2014) looks at how some products become part of people’s routines. They are often mentioned in the same breath, and they sit comfortably side by side on a shelf.
This guide looks at what each book offers, how they compare and which might suit you best. Because the ideas are easiest to appreciate when applied, we have added a short launch-plan comparison, a short note on ethics and a reading order. We will also point to a few of our other CROWNLEIGH Book Club guides that connect with the same themes.
Hooked is about retention: it describes a four-step loop of Trigger, Action, Variable Reward and Investment that helps explain why people return to some products without being reminded. Contagious is about word of mouth: it describes six principles, summarised as STEPPS, that help explain why people share some things and not others. Many readers find Hooked the more useful guide if they are shaping a product people will use again and again, and Contagious the more useful guide if their challenge is being noticed and talked about. Each is best read alongside your own experience, and with a clear sense of how you would like to treat the people you hope to reach.
The two books side by side
| Hooked | Contagious | |
|---|---|---|
| Author | Nir Eyal, with Ryan Hoover | Jonah Berger |
| First published | 2014 | 2013 |
| Subtitle | How to Build Habit-Forming Products | Why Things Catch On |
| Core idea | Products become habits when a trigger leads to an easy action, a rewarding and somewhat unpredictable outcome, and a small investment that sets up the next visit | Things spread when they are built around six principles: Social Currency, Triggers, Emotion, Public, Practical Value and Stories |
| Signature ideas | The Hook Model; internal and external triggers; the three types of variable reward; investment and stored value | STEPPS; behavioural residue; high-arousal emotions; ‘news you can use’; stories as vehicles for information |
| Focus | What happens after someone has tried a product | What happens before and around the first try: talking and sharing |
| Best for | Product designers, founders and managers working on apps and services people use regularly | Marketers, founders and communicators thinking about awareness and recommendation |
| Things to bear in mind | Sits close to questions of persuasion; works best when the product genuinely helps its users | Examples are memorable but are drawn from particular campaigns; they are a starting point, not a guarantee |
| Reading experience | Compact, framework-led and practical, with a clear model to apply | Story-led and lively, with many short case studies |
What they share
- Psychology first. Both books start from how people actually behave, rather than from technology or advertising techniques.
- Memorable frameworks. Each gives you a short, easy-to-recall model: a four-step loop on one hand, six principles on the other.
- Case studies. Both lean on real products and campaigns to bring their ideas to life.
- Work done before launch. Each suggests that growth is shaped by design decisions, rather than by luck or a large advertising budget alone.
Hooked: the four-step loop
Nir Eyal wrote Hooked for people who design products, and its central idea is the Hook Model: a cycle of four steps that, repeated often enough, can turn an occasional behaviour into a habit. The book draws on psychology and on Eyal’s work in and around the technology industry.
Some of the key ideas:
- Trigger. Something prompts the behaviour. External triggers, such as a notification or a message from a friend, come from outside. Internal triggers come from within, often an emotion such as boredom, curiosity or a wish to stay in touch.
- Action. The simplest behaviour done in anticipation of a reward. Eyal builds on the work of the researcher BJ Fogg, who describes behaviour as a combination of motivation, ability and a prompt, and the book encourages makers to make the action as easy as possible.
- Variable reward. Outcomes that are satisfying and slightly unpredictable tend to hold attention. Eyal groups them into rewards of the tribe (social), the hunt (information or resources) and the self (mastery or completion).
- Investment. The user puts something in, such as data, effort, content or a skill, which makes the product more valuable to them next time and sets up the next trigger.
- The Manipulation Matrix. A short ethics tool that asks whether the maker would use the product themselves and whether it materially improves people’s lives.
Many readers enjoy the book for how quickly it turns a big topic into something they can sketch on a whiteboard. It is a good companion for a product team’s planning session.
Pick one product you use regularly and sketch its loop on a page: what triggers you, what you do, what you get and what you leave behind for next time. Then pick a product you are building, or one you admire, and try to sketch its loop in the same way. Notice which of the four steps is strongest and which is missing.
Contagious: six principles of sharing
Jonah Berger is a professor at the Wharton School, and Contagious summarises his research into why some things are talked about and shared. Rather than trying to predict the next viral hit, the book asks what the things people talk about tend to have in common, and arrives at six principles that spell STEPPS.
Some of the key ideas:
- Social Currency. People share things that make them look good, so remarkable, inside-knowledge or exclusive-feeling ideas travel well.
- Triggers. Things that are connected to frequent cues in everyday life stay at the front of people’s minds, and so are talked about more.
- Emotion. When we care, we share. The book suggests that emotions which raise our energy, such as awe or excitement, tend to encourage sharing more than those that lower it.
- Public. Things that are visible are easier to copy, so products and behaviours that leave a visible trace help themselves spread.
- Practical Value. People enjoy passing on useful information, from tips to savings to advice.
- Stories. Information travels inside narratives, and a good story carries the message along with it.
Many readers enjoy the book for its lively examples, and for the way its checklist can be used to review a message, a name or a campaign.
Choose one idea, product or message you would like people to talk about, and score it against the six STEPPS principles, noting which are strongest. Then change one thing to strengthen the weakest one, share the new version with a handful of people, and notice what they pass on, and what they pass on first.
A launch-plan comparison
To see the difference in flavour, imagine a small team preparing to launch a language-learning app. The two columns below are short illustrations, not a plan to follow word for word.
| Question | In the style of Contagious | In the style of Hooked |
|---|---|---|
| First goal | Get people talking about the app and recommending it to friends | Help people who have downloaded the app come back tomorrow, and the day after |
| Starting point | What is remarkable enough about the app that someone would mention it? (Social Currency) | What feeling or moment in a learner’s day might prompt them to open the app? (Trigger) |
| Making it easy | Give learners a shareable moment, such as a certificate or a streak that others can see (Public) | Make the first lesson a single tap away, so the action takes almost no effort (Action) |
| Keeping interest | Share useful phrases people can pass on to travelling friends (Practical Value) | Vary the rewards: a surprise bonus lesson, a friendly leaderboard, a sense of progress (Variable reward) |
| Looking ahead | Tell the story of a learner who ordered dinner in a new language (Stories) | Let learners choose their goals and build a personal deck of words (Investment) |
Notice how the first column is about the conversation around the product, and the second is about the experience of using it. In practice, the two can work together: a product people want to return to gives them something to talk about, and a product people talk about brings in new users to learn from.
Where the two books feel different
The clearest difference is where each places the spotlight. Contagious looks outward, at the conversations between people. Its question is: why would one person tell another? Hooked looks inward, at a single person’s relationship with a product. Its question is: why would they come back?
They also differ in how much they ask the reader to design. Hooked is a design manual in miniature: it expects you to apply its loop to a product you can change. Contagious is closer to a checklist for communicators: it works as well for a message, a name or an event as for a product. Many readers find that Contagious suits marketing and communications roles, while Hooked suits product and design roles, and that reading both helps teams from each side to speak the same language.
A gentle note on ethics
Because Hooked is about forming habits, it is worth reading with a thoughtful eye. A habit that helps someone, such as learning a language, saving regularly or keeping in touch with family, is very different from one that quietly takes up their time. Eyal addresses the question directly, and the Manipulation Matrix is his way of asking makers to consider it. The same spirit applies to word of mouth: a useful question is whether people would be glad to have shared what you made.
Before you apply either book to a product or campaign, ask yourself three questions. They are this guide’s own test, loosely inspired by the spirit of Eyal’s Manipulation Matrix, rather than questions taken from either book:
- Would I use this myself, and would I be glad if someone I care about used it?
- Does it materially improve people’s lives, in a way they would recognise and agree with?
- If the people we are designing for could see exactly what we are doing and why, would they be comfortable with it?
If the answer to any of these is uncertain, that is a useful prompt to adjust the design before launch. Many readers find that the products and messages that pass this test are also the ones that earn long-term trust.
Which one suits which situation?
Here is a rough guide, based on what each book emphasises. Treat it as a starting point rather than a rulebook:
| Your situation | Where to start | Why |
|---|---|---|
| You are designing an app or service people will use regularly | Hooked | Its loop is built around repeat use |
| You have a good product and need people to hear about it | Contagious | Its six principles are built around word of mouth |
| You work in marketing, communications or events | Contagious | It works well as a checklist for messages and campaigns |
| You lead a product team and want a shared model | Hooked | The Hook Model is easy to sketch and discuss together |
| You are launching something new | Both | One helps people find it, the other helps them return |
If you enjoyed these ideas
A handful of our other CROWNLEIGH Book Club guides connect closely with the ideas in these two books:
- Habits. The mechanics of cues, routines and rewards are explored in our guide to Atomic Habits and The Power of Habit.
- Persuasion. How the way a message is framed shapes the response appears in our guide to Influence and Pre-Suasion.
- How we decide. The quirks of human judgement behind many of these ideas are explored in our guide to Thinking, Fast and Slow and Noise.
- How products catch on. The journey from early adopters to the mainstream is explored in our guide to Crossing the Chasm and The Innovator’s Dilemma.
- Understanding customers. Thoughtful questions and fresh insight in conversations with customers feature in our guide to The Challenger Sale and SPIN Selling.
You can find all of these, and more as we add them, on our CROWNLEIGH Book Club page.
Our suggested reading order
If you are launching something new, we would suggest starting with Contagious. People need to find a product before they can come back to it, and its six principles give you a quick way to review your message and your name. Then read Hooked to think about what happens once someone has arrived: how they are prompted, how easy the first step is and what makes the second visit worthwhile. If you already have users and your challenge is keeping them, it works nicely the other way round: begin with Hooked, and follow with Contagious to help your existing users pass the word on.
Frequently asked questions
Should I read Hooked or Contagious first?
If you are working on something people will use regularly, Hooked is a natural place to begin. If you are working on awareness and recommendation, Contagious is a good first read. For a new launch, many readers enjoy starting with Contagious and following it with Hooked.
Is Hooked ethical to use in product design?
It depends on how it is used, and the book itself encourages makers to think about this. Habits that help people do things they want to do, such as learn, exercise or stay in touch, are very different from habits that work against their interests. The simple test in this guide, and the Manipulation Matrix in the book, are good ways to check your own plans before you build.
Is Contagious only about viral marketing?
No. Its ideas apply to anything that people might talk about, from a charity campaign to a team announcement to a new café. The six principles also work well as a way of reviewing an ordinary message in a more memorable way.
Do I need to read both?
Not necessarily. Each book stands well on its own. Reading both gives you a way of thinking about how a product is discovered and how it is kept.
Can I read Hooked and Contagious together, and is it worth it?
Yes, and many people enjoy it. A pleasant approach is to read a chapter of one, then a chapter of the other, and try one idea from each over the same month. The 30-day tests above are an easy way to do just that.
A closing thought
Read together, the two books suggest a simple idea: that many of the things which grow are those people genuinely find worth coming back to and worth talking about. Whichever you open first, you may finish with a clearer picture of how people discover, use and share the things you make, and a few good questions to ask before your next launch.
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