Contagious: Why Things Catch On

by Jonah Berger

Awe is a complex emotion and frequently involves a sense of surprise, unexpectedness, or mystery.

Sharing emotions also helps us connect.

And the fact that we both feel the same way helps deepen our social connection. It highlights our similarities and reminds us how much we have in common. Emotion sharing is thus a bit like social glue, maintaining and strengthening relationships.

Arousal is a state of activation and readiness for action.

Physiological arousal motivates a fight-or-flight response

“The best results don’t show up in a search engine, they show up in people’s lives.”

Figure out how to make them care.

On the positive side, excite people or inspire them by showing them how they can make a difference. On the negative side, make people mad, not sad. Make sure the polar bear story gets them fired up. Simply adding more arousal to a story or ad can have a big impact on people’s willingness to share it.

Emotions drive people to action. They make us laugh, shout, and cry, and they make us talk, share, and buy.

sneakers, you should make something that will move people. People don’t want to feel like they’re being told something—they want to be entertained, they want to be moved.

Jobs realized that seeing others do something makes people more likely to do it themselves.

Thus a key factor in driving products to catch on is public visibility. If something is built to show, it’s built to grow.

People often imitate those around them.

People imitate, in part, because others’ choices provide information.

behavior is public and thoughts are private.

People can imitate only when they can see what others are doing.

Observability has a huge impact on whether products and ideas catch on.

Social influence was stronger when behavior was more observable. Observable things are also more likely to be discussed.

The more public a product or service is, the more it triggers people to take action.

The Movember Foundation succeeded because they figured out how to make the private public. They figured out how to take support for an abstract cause—something not typically observable—and make it something that everyone can see.

Making the cause public helped it catch on more quickly than it ever could have otherwise.

If people can’t see what others are choosing and doing, they can’t imitate them.

Solving this problem requires making the private public. Generating public signals for private choices, actions, and opinions. Taking what was once an unobservable thought or behavior and transforming it into a more observable one.

Every time people use the product or service they also transmit social proof or passive approval because usage is observable.

Shapes, sounds, and a host of other distinctive characteristics can also help products advertise themselves.

Designing products that advertise themselves is a particularly powerful strategy for small companies or organizations that don’t have a lot of resources. Even when there is no money to buy television ads or a spot in the local paper, existing customers can act as advertisements if the product advertises itself. It’s like advertising without an advertising budget.

Behavioral residue is the physical traces or remnants that most actions or behaviors leave in their wake.

when publicly visible, these remnants facilitate imitation and provide chances for people to talk about related products or ideas.

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.

If you want to get people not to do something, don’t tell them that lots of their peers are doing

It’s been said that when people are free to do as they please, they usually imitate one another.

We need to make the private public. If something is built to show, it’s built to grow.

People like to pass along practical, useful information. News others can use.

people don’t just value practical information, they share it. Offering practical value helps make things contagious.

Passing along useful things also strengthens social bonds.

Sharing is caring.

Setting a higher reference point made the first deal seem better even though the price was higher overall.

They want consumers to use those prices as the reference price, making the sale price look even better.

Reference points also work with quantities.

Deals seem more appealing when they highlight incredible value.

But offers that are available for only a limited time seem more appealing because of the restriction. Just like making a product scarce, the fact that a deal won’t be around forever makes people feel that it must be a really good one.

Quantity limits work the same way.

Researchers find that whether a discount seems larger as money or percentage off depends on the original price. For low-priced products, like books or groceries, price reductions seem more significant when they are framed in percentage terms.

Useful information, then, is another form of practical value. Helping people do things they want to do, or encouraging them to do things they should do. Faster, better, and easier.

So while broadly relevant content could be shared more, content that is obviously relevant to a narrow audience may actually be more viral.

finding Practical Value isn’t hard. Almost every product or idea imaginable has something useful about it. Whether it saves people money, makes them happier, improves health, or saves them time, all of these things are news you can use. So thinking about why people gravitate to our product or idea in the first place will give us a good sense of the underlying practical value.

By encasing the lesson in a story, these early writers ensured that it would be passed along—and perhaps even be believed more wholeheartedly than if the lesson’s words were spoken simply and plainly.

They think in terms of narratives. But while people focus on the story itself, information comes along for the ride.

Narratives are inherently more engrossing than basic facts. They have a beginning, middle, and end. If people get sucked in early, they’ll stay for the conclusion. When you hear people tell a good story you hang on every word.

Stories carry things. A lesson or moral. Information or a take-home message.