Influence: The Psychology of Persuasion by Robert B. Cialdini: Summary and Notes

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One sentence summary: In this book, Influence: The Psychology of Persuasion Robert B. Cialdini distills 30 years of studies, research, and observations into six principles that if applied can increase your level of influence.

One paragraph summary: In this book, Influence: The Psychology of Persuasion by Robert B. Cialdini is a book on how to influence people. Cialdini spent over 30 years studying the art of persuasion and observed that there are six principles or ways to influence people. These are reciprocity, commitment, social proof, sympathy, authority, and scarcity. These principles are used by marketers, psychologists, politicians, and pretty much everyone else looking to influence the decisions we make. By applying these principles, you too can start to make others do the things you want.

Have you ever tried to influence another person's decision only to make them do the opposite? You are not alone. Getting other people to do what you want is such a tough act that many folks think there is no use trying

You will often hear: “Joe is stubborn that way,” ‘Susan will never change,’ 'We've tried everything…”

But what if I told you that there is a science behind influencing people? In this book, Influence: The Psychology of Persuasion Robert Cialdini shares some of the most powerful tricks of persuading people. Cialdini is an expert in the art of persuasion and has studied the subject for over 30 years. He is currently a Professor Emeritus of Psychology and Marketing at Arizona State University and a visiting professor at Stanford.

But what if I told you that there is a science behind influencing people? In this book, His book has sold over 5 million copies and has been translated into 41 languages! Marketers, politicians, businessmen, and psychologists have long relied on its tips and tricks to get people to do what they want.

What's Caldinis' big idea? He says despite having bigger brains, you and I are no different from a mother turkey. Mother turkeys are excellent caretakers who protect their young from any dangers and smother them with love but only if the chicks make the ‘cheep cheep’ sound. Failure to do so can get it killed. Scientists have also demonstrated that the mother turkey will show the same kind of devotion to anything, including robots, as long as it makes the same sound.

Humans compare with the mother turkey because we also have mental blindspots — mechanical patterns of behavior — that make us vulnerable to influence. For instance, do you know that when you ask people to do you a favor, you are more likely to be successful if you give a reason, no matter how outrageous? Now you know.

When I read Caldini’s book, it reminded me of Predictably Irrational by Dan Ariely. The two books excellently demonstrate the many quirks of the human mind. To get the whole picture, I recommend that you read one after the other.

Main Takeaway Lessons Influence: The Psychology of Persuasion

Cialdini identifies six principles that make it easier for a person to say yes.


Commitment and consistency





Lesson 1: The principle of reciprocity

The principle of reciprocity is the idea that you are sure to get something in return when you do a favor for someone. Humans are wired that way, and it makes a lot of sense because it means greater survivability for everyone.

If you want to hear of an extreme case of the principle of reciprocity at work, look no further than the case of Ethiopia in 1985. Despite millions of its citizens facing starvation, Ethiopia sent a $5000 aid package to earthquake victims in Mexico. All because in 1935, Mexico had sent help to Ethiopia as they fought off an invading force of Italians. The decision to send aid had many people scratching their heads because Ethiopia was in a much more dire situation. But they sent it anyway

This story shows that the urge to return favors is so strong that we are likely to do it even at the risk of our health, social standing, and welfare. Caldini says that human societies gain a lot of competitive advantage from the reciprocity rule. We are even ready to put labels on others and punish them if they don't adhere to the principle

Marketers, charities, supermarket chains, and even the likes of Netflix with their free one-month subscription know that if you get something for ‘free,’ you will feel obligated to return the favor. The lesson here is, do something for others before asking for a favor. It always works.

Lesson 2: Commitment and consistency

If you can get someone to commit to something, they are likely to escalate their commitment and even assume an identity based on the commitment they make.

Have you ever wondered why some companies are willing to spend millions of dollars running testimonial campaigns? It is because they also get thousands of people to write something favorable about them. The same customers — assuming they are customers in the first place — are likely to escalate their commitment and become even more loyal. It is an ingenious marketing ploy

One of the tricks behind the principle of commitment is to start small.Studies show that even a minor commitment is enough to trigger a chain of actions that tend to escalate. Cialdini notes that commitments are most effective in changing a person's behavior when they are active, public, and effortful. Writing something down is especially powerful because it serves as a reminder and can be publicly displayed.

Commitment goes hand in hand with consistency. People who demonstrate consistency in their actions and words are seen as being more trustworthy and reliable. Cialdini notes that good consistency is highly valued in our society. He adds that without consistency, our lives would be difficult, erratic, and disjointed

Lesson 3: Consensus (Social proof)

Look, here is a guy that agrees with me, Yah!

The principle of consensus is much like trusting the wisdom of the crowd. It says our opinions of whether things are right or wrong depend largely on what other people think. If our friends agree, we are also likely to agree. Behaving this way saves us from second-guessing many of the choices we make. In other words, it keeps us making too many decisions that could tire us

Marketers exploit the principle of consensus by running testimonials and customer feedback ads because they know how powerful the opinions of others are, especially when there is little else to go on.

While conforming to general expectations is an excellent way of reserving our decision-making, it also has drawbacks. Think of Nazism, for instance. Part of the reason most Germans were drawn to the ideology was because their neighbors were Nazis, as were their friends. What I’m trying to say? While it is good to follow the wisdom of the crowd, reserve some thinking for yourself.

Lesson 4: Sympathy

Being likable, and beautiful can make you more influential as people associate beauty with intelligence, charm, and honesty. It’s outrageous when you think about it, but it is what it is.

Also, if you share similarities with someone or even claim to like them, it is an effective way to gain their trust. This idea finally made me understand why some of my colleagues dare me to do all kinds of dumb stuff – they think we are the same!

Jokes aside, we also tend to be sympathetic to the people we rub shoulders with the most. These include family members, workmates, friends, and so on.

Finally, Cialdini explains why everyone hates the weatherman. We tend to hate the people who deliver bad news even if they are not to blame. The same holds for people who provide good news – we like them more

Cialdini advises that when faced with a situation that tries to appeal to our sympathies, we should separate the dealer from the deal, especially in a commercial setting. The key is to focus on the qualities of the product and nothing more

Lesson 5: Authority

According to Cialdini, we have a deep-seated sense of duty to authority. We do what we are told because having a value system and a singular reference point is best for everyone. Without authority figures and symbols, the result would be anarchy

Humans respect different types of authority figures and symbols. They include:

Lesson 5: Scarcity

If you want to make something attractive, make it rare. Cialdini observes that whenever our decision-making power is threatened — by scarcity — we fight like hell to keep our options available. In other words, we hate losing, even if it’s in our best interests. Not only that, but we also make easy targets for limited edition marketing schemes because of the fear of losing out on things that we may not even end up using

Cialdini makes an interesting observation on the relationship between scarcity and abundance. He says that if we are exposed to an abundance of something and then denied that very thing, the reactions can be adverse. The race riots of the 60s illustrate this point perfectly. African Americans had steadily gained civil rights and liberties, leading to the landmark Civil Rights Act of 1965. Following these gains, whites started a campaign of violence and intimidation that threatened to undo everything. African Americans reacted to the threat of loss by staging unprecedented riots because they had come to know freedom, and now everything was at risk

The lesson here is once you give something, don’t think about taking it away because humans really hate losing

Wrap Up

Influence: The Psychology of Persuasion has sold millions of copies because it is one the most concise books on human behavior ever written. Cialdini offers convincing arguments and lots of examples on how to influence people. He also references tens of studies that demonstrate how anyone can do this. You should read it if you are looking to increase your level of impact. Other good books in the same category include Predictably Irrational, The Power of Habit, and Switch

Who would I recommend the Book To?

Anyone interested in the business process and startups in general, the book is a necessary tool for any entrepreneur. You should read it.


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