Contagious: Why Things Catch On

by Jonah Berger

By focusing on feelings, Google turned a normal ad into a viral hit.

When trying to use emotions to drive sharing, remember to pick ones that kindle the fire: select high-arousal emotions that drive people to action. 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.

More anger or more humor led to more sharing. Adding these emotions boosted transmission by boosting the amount of arousal the story or ad evoked.

Designing messages that make people anxious or disgusted (high arousal) rather than sad (low arousal) will boost transmission. Negative emotions, when used correctly, can be a powerful driver of discussion.

Among students who had been instructed to jog, 75 percent shared the article—more than twice as many as the students who had been in the “relaxed” group. Thus any sort of arousal, whether from emotional or physical sources, and even arousal due to the situation itself (rather than content), can boost transmission.

So be careful the next time you step off the treadmill, barely avoid a car accident, or experience a turbulent plane ride. Because you’ve been aroused by these experiences, you may overshare information with others in the aftermath.

Physiological arousal or activation drives people to talk and share. We need to get people excited or make them laugh. We need to make them angry rather than sad. Even situations where people are active can make them more likely to pass things on to others.

People often imitate those around them.

They dress in the same styles as their friends, pick entrées preferred by other diners, and reuse hotel

towels more when they think others are d...

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

Psychologists call this idea “social proof.

If so many others have refused this kidney, people assume it must not be very good. They infer it is low quality and are more likely to turn it down.

Sure, people may learn about different opportunities during the MBA program, but part of this herding is driven by social influence. People aren’t sure what career to choose, so they look to others.

Social interaction led students who originally preferred different paths to go in the same direction.

Why were students drinking so much if they don’t actually like it? Because behavior is public and thoughts are private.

You’d witness your peers drinking and seeming happy about it, so you’d assume that you are the outlier and that everyone else likes drinking more than you do. So you’d have another drink.

And the cycle continues because people can’t read one another’s thoughts. If they could, they’d realize that everyone felt the same way. And they wouldn’t feel all this social proof compelling them to drink as much.

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.

Public visibility boosts word of mouth. The easier something is to see, the more people talk about it.

They figured out how to take support for an abstract cause—something not typically observable—and make it something that everyone can see.

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.

So early adopters liked talking about it because it gave them Social Currency.

All these examples involve products that advertise themselves. Every time people use the product or service they also transmit social proof or passive approval because usage is observable.

Tickets usually sit in people’s pockets, but if theater companies and minor league teams could use buttons or stickers as the “ticket” instead, “tickets” would be much more publicly observable.

Is there something that generates social proof that sticks around even when the product is not being used or the idea is not top of mind? Yes. And it’s called behavioral residue.

But regardless, one thing is clear: the wristband creates more behavioral residue than the cross-country ride ever could have. As MacEachern keenly noted: The nice thing about a wristband is that it lives on. The bike ride doesn’t. There’ll be pictures of the bike ride and people will talk about the bike ride, but unless it goes on every year—even if it does go on every year, it doesn’t live on as a reminder every day of this sort of stuff. But the wristband does.

In fact, the messages actually seemed to increase drug use. Kids aged twelve and a half to eighteen who saw the ads were actually more likely to smoke marijuana. Why? Because it made drug use more public. Think about observability and social proof.

But anti-drug ads often say two things simultaneously. They say that drugs are bad, but they also say that other people are doing them. And as we’ve discussed throughout this chapter, the more others seem to be doing something, the more likely people are to think that thing is right or normal and what they should be doing as well.

You never see public service announcements for avoiding cutting off your hand with a saw or not getting hit by a bus, so if the government spent the time and money to tell you about drugs, a lot of your peers must be doing them, right? Some of them are apparently the coolest kids in school. And you had no idea!

As with many powerful tools, making things more public can have unintended consequences when not applied carefully. If you want to get people not to do something, don’t tell them that lots of their peers are doing it.

One asked people not to take the wood because “many past visitors have removed petrified wood from the Park, changing the natural state of the Petrified Forest.” But by providing social proof that others were stealing, the message had a perverse effect, almost doubling the number of people taking wood!

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

If people can’t see what others are doing, they can’t imitate them. So to get our products and ideas to become popular we need to make them more publicly observable.

Finally, while a clever campaign could figure out how to make vacuum cleaners more Emotional, the hikers were just having a basic conversation about features different vacuums offered. So what was driving them to talk? The answer is simple. People like to pass along practical, useful information. News others can use.

Further, as the stories of Ken’s corn and the vacuum-discussing hikers illustrate, people don’t just value practical information, they share it. Offering practical value helps make things contagious.

Today, these direct opportunities to help others are fewer and farther between.

If Social Currency is about information senders and how sharing makes them look, Practical Value is mostly about the information receiver. It’s about saving people time or money, or helping them have good experiences.

But at its core, sharing practical value is about helping others. The Emotions chapter noted that when we care, we share. But the opposite is also true. Sharing is caring.

bounded rationality, a new perspective on intuitive judgment and choice.

The theory is amazingly rich, but at its core, it’s based on a very basic idea. The way people actually make decisions often violates standard economic assumptions about how they should make decisions. Judgments and decisions are not always rational or optimal. Instead, they are based on psychological principles of how people perceive and process information.

Kahneman and Tversky’s research is some of the earliest studying what we now think of as “behavioral economics.”

It might seem that old people are stingier than the rest of us. But there is a more fundamental reason that they think the prices are unfair. They have different reference points.

Reference points help explain the barbecue grill scenarios we discussed a few pages ago. People use the price they expect to pay for something as their reference point.

Most infomercials use this technique to make whatever they are offering seem like a great deal. By mentioning $100 or $200 as the price you might expect to pay, the infomercial sets a high reference point, making the final price of $39.99 seem like a steal.

This is also why retailers often list a “regular” or manufacturer’s standard retail price even when something is on sale. They want consumers to use those prices as the reference price, making the sale price look even better.