Word-of-mouth referral is one of the most important marketing channels today. And yet it’s not always clear what we can do to drive results. Contagious reveals the science behind social transmission. And it covers six principles for increasing word-of-mouth referral.

This book is for entrepreneurs, marketers, social media managers, or anyone else interested in increasing word-of-mouth referral. It’s not about using paid ads or brand campaigns to spread a message. Rather it’s about making products, ideas, and content more contagious so they spread naturally.

Introduction: Why Things Catch On

People love to share news, stories, and information with those around them. As a result, worth of mouth is the primary factor behind 20-50% of all purchase decisions. It’s more effective than traditional advertising because it’s both more persuasive and more targeted.

This book explains what makes stories, information, products, ideas, messages, or videos become contagious. In other words, the factors that make them more likely to spread via word of mouth and social influence.  The principles are relatively independent, so you can mix and match them as you see fit.

Principle 1: Social Currency

Word of mouth is a tool that people use to make a good impression among others. Think of it as a way to generate a kind of social currency. Just as people use money to buy products or services, they use social currency to achieve desired positive impressions among their families, friends, and colleagues.

A common belief is that some people are simply more influential than others. However in most cases that does not make them any more effective in making things go viral. Just as some jokes are so funny that it doesn’t matter who tells them, contagious content spreads regardless of who is doing the talking.

People share things that make themselves look good to others. Things that make them seem entertaining rather than boring, clever rather than dumb, and hip rather than dull. So to get people talking, give them a way to make themselves look good while promoting your products or ideas.

There are three ways to do this: (1) find inner remarkability, (2) leverage game mechanics, and (3) make people feel like insiders.  Is there something novel, surprising, extreme, or just plain interesting about your product or idea? Can you use game mechanics to measure user progress or enable social comparison? Can you make people feel like insiders by giving them exclusive access or social status?

Principle 2: Triggers

There are two types of word of mouth: immediate and ongoing. Immediate word of mouth occurs when you pass on the details of a product, service, or message soon after first experiencing it. Ongoing worth of mouth covers the conversations that take place in the weeks and months that follow.

Interesting experiences tend to receive more immediate word of mouth, but they don’t necessarily sustain high levels over time. Most conversations are less about finding interesting things to say than they are about filling conversational space. So we often talk about whatever is top of mind in the moment.

This is where triggers become so valuable. Triggers are stimuli that prompt people to think about related things in any given moment. They boost word of mouth by making a product, topic, or idea top of mind. Triggered products or ideas tend to benefit from both immediate and ongoing word of mouth.

So rather than just going for a catchy message, consider the context. Think about whether the message will be triggered by the everyday environments of the target audience. Most products or ideas have a number of natural triggers, but it’s also possible to create new links or associations to environmental stimuli.

Note that it’s important to balance the frequency of the trigger with the strength of the link.  The more things a given trigger is associated with, the weaker any one association will be. It’s also important to pick triggers that happen near where a desired behavior is expected to take place. That way the target audience has a convenient way to act after being triggered to think about a specific message or idea.

Principle 3: Emotional

When we care, we share. Naturally contagious content usually evokes some sort of emotion.  So rather than harping on features or facts, we need to focus on feelings. Not just any feelings, but those that are most likely to motivate people to take action and share our message.

Emotions can be categorized based on the positive or negative feelings they create. But what matters most is the level of physiological arousal that they cause. Arousal is a state of readiness for action. Other emotions have the opposite effect, they stifle action and cause people to feel content and relaxed.

Positive high-arousal emotions include feelings of awe, excitement, and amusement. Negative high-arousal emotions include feelings of anger and anxiety. All of these examples are emotions that can lead people to share, because they kindle the fire within people and drive them to take action.

Does talking about your product or idea generate emotion? How can you kindle the fire?  Use the “three whys” method to find the emotional core of any idea. Write down why you think people are interested in your message and then ask “Why is this important?” three times. Each time you do this, note your answer and drill down further and further until you uncover the core emotion behind it.

Principle 4: Public Observability

Seeing others do something makes it more likely that we will do it ourselves.  We imitate, in part, because their choices provide information. We assume that if other people are doing something, it must be a good idea. They may know something that we don’t. Psychologists call this idea “social proof”.

Unfortunately most products, services, and ideas are used or adopted privately. What websites do your coworkers like? What initiatives do your neighbors support? Unless they tell you, you may never know. And while that may not matter to you, it matters a lot for the success of related businesses and organizations.

Public observability has a huge impact on whether products or ideas catch on. The easier it is to see other people using or supporting something, the more likely it is that we will notice it, spread the word, and consider imitating their behavior.

Look for ways to generate public signals for private choices, actions, and opinions that relate to your products or ideas. Can your product advertise itself by being used in public? Do customers have any way to demonstrate their support even when not using the product? Is it easy for people to see how much support exists for a behavior, message, or idea that you want to spread?

Principle 5: Practical Value

People like to share practical or useful information. It lets their friends see that they care, makes them feel helpful, and causes everyone to feel more connected. Where Social Currency is primarily about making the sender look good, Practical Value is more about helping recipients.

Promotional deals are one example of practical value. They are more likely to be shared when they highlight incredible value, seem surprising or surpass expectations, and are restricted or limited in availability. It’s best to frame discounts using the Rule of 100: if the product is less than $100, frame the discount based on the percentage of savings. If more than $100, use the cash value of the discount instead.

Useful information is another form of practical value. Articles about health and education are some of the most shared. And, while broad content might be shared more often, content that is relevant to a narrow audience may actually be more viral. That’s because it reminds people of a specific friend or family member.

Of the six principles of contagiousness, Practical Value may be the easiest to apply. That’s because almost every product or idea has something useful about it. The harder part is cutting through the clutter.

Principle 6: Stories

People don’t think in terms of facts. They think in terms of stories, because narratives are more engrossing than facts alone. They have a beginning, middle, and end.  If people get sucked in early, they’ll stay for the conclusion. And, while people focus on the story, information comes along for the ride.

One powerful aspect of stories is that they make it easy for people to talk about products or ideas without sounding like advertisements.  Plus, it’s harder for listeners to argue against a specific customer’s story than against advertising claims. They’re so engaged in the narrative that they’re less likely to question what is being said.

For businesses, the goal is not only to make a story go viral, but to also make it valuable to the company or brand.  Therefore, stories are most valuable when the brand or product is integral to the narrative. When it’s woven so deeply that people can’t spread the story without mentioning it.

After The Contagious Book Summary

Contagious Book Cover
Contagious by Jonah Berger

This book summary of Contagious briefly covered each of the six principles. However, it’s not meant to be a substitute for reading the book. That’s because the original text provides a much richer and more detailed learning experience.

So if you’re an entrepreneur, marketer, social media manager, or anyone else interested in increasing word-of-mouth referral, consider picking up a copy of the book. Contagious is available from Amazon, Audible, and Apple Books.

Are you looking for another great book? Consider checking out the best digital marketing books or the best social media marketing books to find your next great read.

Rick Kettner

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