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Summary: Influence: The Psychology of Persuasion by Robert Cialdini

Why do we sometimes say yes when we really should have said no? “Influence: The Psychology of Persuasion” lays out the six principles of persuasion that have led to many a misguided purchasing decision or deal. In this book review, you’ll learn how master marketers use common (and some uncommon) tactics like sales and free samples to manipulate your purchasing habits. And, most importantly, you’ll learn how to launch a counterattack to protect yourself from these machinations.

Learn the secrets marketers use to make you say “yes” when you should say “no.”


  • Want to become more influential
  • Are too susceptible to advertisements
  • Care about the psychology behind persuasion


You might not be the type of person to buy something based on a cheesy infomercial, but you certainly have been influenced by advertisers, friends, and family throughout your life — whether you’re aware of it or not. Maybe you’re still feeling guilty about buying that treadmill that’s collecting dust in your closet because it was on sale for a great price. Worse, there’s also that year-long gym membership you signed up for and have never actually used. Getting physically fit is a lot harder than it seems on Instagram.

In this increasingly hyperconnected world, we’re all being influenced in ways we don’t even notice. That’s why it’s important to grasp the six principles of influence, which are:

  • Reciprocation: Small gifts can have big, profitable returns.
  • Consistency: You committed to a relationship, and you’re gonna stick with it, no matter how much it makes you unhappy now.
  • Social proof: If everyone jumped off a cliff, would you? You say no, but studies show the answer would actually be yes.
  • Liking: A well-timed compliment may be all it takes for someone to charm you into doing them a favor.
  • Authority: You’re most likely to obey doctor’s orders, even when it’s just a person dressed as a doctor in a drug commercial.
  • Scarcity: You have the overwhelming need to buy things you definitely don’t need before a fantastic sale is over.

Psychology Professor Robert Cialdini identified these principles after he spent time away from his day job to spy on skilled marketers and other compliance professionals to learn their secret techniques. In this summary, all those secrets will be revealed.

Book Summary: Influence - The Psychology of Persuasion

Weapons of Influence

Influence is a weapon that can be deadly to your wallet. And often, it’s triggered automatically so that you don’t even notice its power. Before diving into the specifics of each principle, it’s important to grasp the general pervasiveness of their use.

One day, a friend who owned a jewelry shop called up Cialdini to explain a seemingly strange sales situation. The shop owner had been unable to sell a set of turquoise jewelry for so long, they decided to put it on sale. They left a note to an employee to sell it at a 50% discount. But the employee misread the note, and put the items on display at double the price.

The turquoise pieces sold quickly after that.

The store owner inadvertently exploited many people’s understanding that the more expensive an item is, the better quality it is. This is a stereotype most of us accept and make purchases by. Plenty of sales people use this and other techniques to get customers to agree to prices they might otherwise balk at. It’s why a car salesman doesn’t try to upsell you until after you’ve agreed on the price of the car — what’s another $250 for tinted windows when you’re already spending $16,000?

In contrast to the initial car price, $250 is nothing. The contrast effect — where a large initial ask makes a follow-up favor seem much more reasonable than it normally would — plays a large part in many of our interactions.

Sales techniques and other persuasive appeals exploit fixed-action patterns based on stereotypes we respond to. Stereotypes are shortcuts we rely on to process the overwhelming amount of information we come across each day without getting lost in the minutiae. These shortcuts can be used by, for, and against us and our best interests, depending on the situation.

A greater awareness of common fixed-action patterns and how the six principles of persuasion are used will protect and guide you in future transactions.


Give, and you will receive. It’s a simple statement we all know that defines the power of the rules of reciprocity. If your neighbor jumpstarts your car one day, you’re more likely to do the same for them someday, or perform some other favor. If someone gives you a gift, you feel obligated to give them one in return.

The rules of reciprocity guide every society around the world, and this principle is also one that we all feel on a personal level. Almost everyone dislikes the feeling of being in debt to someone else. We don’t want others to think we’re selfish or a moocher.

That’s why free samples are an effective marketing tactic.

Sure, you probably don’t always buy the cheese you sampled at the supermarket. But a number of psychology experiments (and real-world corporate earnings) show that free samples or small gifts have really big payoffs. Free cheese samples make people feel indebted and buy more cheese.

Another tactic of reciprocation that works extremely well is the rejectionthen-retreat strategy. You’ve probably seen this in action again when you’ve made a larger purchase, like for a television or a computer. A salesperson is more likely to show you the most expensive models first to make less expensive ones seem reasonably priced by comparison. Really, they expected all along that you would buy the $1,000 model over the $3,000 one. You reject their first offer, and they retreat to another option that you’re more likely to buy.

And if they convinced you to buy the $3,000 one? All the better for them!

It’s a common tactic employed in politics and during labor negotiations, as well. The initial policy statement or demands for better wages will be too ambitious and rejected out of hand. But this makes any compromise seem much more reasonable and more likely to pass.

So how can you fight against the worst manipulations of this rule?

Take time to identify situations where others are trying to manipulate you. Do you really care about the cause of the charity that sent you a gift? Should you be trusting the advice of a marketer who just wants to sell you something? Save your gifts and favors for your friends and family.

Commitment and Consistency

Psychologist Thomas Moriarty was having a lovely time at the beach, lounging and listening to his radio. Then, he decided to go for a walk. He left his radio on his beach blanket, with plenty of people around sunbathing and making sandcastles, blissfully unaware that they were about to be participants in an experiment. While he was walking along the shoreline, a hired researcher playing a thief came along and took his radio.

Only four people attempted to stop the theft out of 20 tries.

Then, Moriarty added a twist to the experiment. Before going for a walk on the beach, he asked someone lounging next to his spot to watch his stuff. Everyone asked agreed to do this.

In this scenario, when the wannabe thief came along, 19 out of 20 times, the people who had agreed to watch Moriarty’s stuff stepped in to protect the radio and apprehend the thief.

The full power of consistency and commitment is on display in this experiment. The people who gave their word to watch the radio wanted to live up to those expectations.

To understand why consistency is so important and ingrained in us, think of how much you hate when people are inconsistent. Perhaps you have a particularly flaky friend who always tells you they’ll do one thing, but then they do another. You never know whether to trust their word when they make you a promise. You wish they were consistent.

But automatic consistency can be dangerous, overriding rational thought and reality. And it all starts with getting you to commit to something.

Commitments change your perception of yourself. They also change what others think of you. Once a commitment is made, you want to behave in a way that’s consistent with your public and private image. For instance, if you think of yourself as an environmentally conscious person, then you will be more likely to donate to green organizations when they send you solicitations.

There are several methods that make commitments increasingly binding. A commitment that’s public, requires a decent amount of effort, and that you believe you decided to make all by yourself, results in a strong self-image you feel the need to remain consistent with.

In our consumerist society, marketers try to manipulate your self-image all the time. Think once again of the car salesman. Perhaps he agrees to let you drive the car around for a day to get a feel for how it handles. You agree, seemingly of your own volition.

But now you’re in a situation where you’re more likely to stick with that car, even if you don’t love the way it handles. That’s because now, your neighbors have seen you driving it. Now, you’ve put in a fair amount of effort to negotiate the price and drive it back and forth from the dealership. Backing out of the deal would make you look inconsistent.

Cialdini has two rather poetic techniques to avoid the traps of harmful consistency. First, listen to your gut before you agree to something. If you can’t stomach the thought of going through with the proposed commitment, don’t. And tell anyone trying to dupe you that you know what they’re up to. They’ll be flustered and leave you alone.

Second, if you’ve already made a commitment but it’s not going how you want, you have to follow your heart. When thinking about an exhausting job, a lackluster relationship, or even just a regrettable purchase within the return window, ask yourself: Would you make the same choice if you could go back in time, knowing what you do now? If not, free yourself from these burdens produced by automatic consistency.

Social Proof

Like most people, you probably hate laugh tracks. Still a staple of comedy television, they’re just so phony and distracting. So why do networks still use canned laughter? Simple: They have data that proves it makes people laugh more.

Canned laughter is a mundane but powerful use of the social proof principle. In most social situations, our personal actions are guided by the actions of others. If other people think a joke is funny, we are more likely to laugh along.

The pull of social proof is strongest in situations where we’re uncertain. For instance, if you go to a fancy dinner party, you might not know which of the three forks you’re supposed to use for what course. So you would surreptitiously observe which fork others at the table use to eat the salad.

In most situations, social proof guides us correctly and is innocuous. But its power has also turned deadly time and again.

The bystander effect is a well-studied phenomenon where people witnessing an emergency situation do not intervene. So if someone’s trying to murder you, you’re statistically better off if there are only one or two people around instead of 20. If you ask 20 bystanders for help, most assume someone else is going to help you. And when nobody else does, it sends the message that inaction is acceptable, because everyone else is just standing around, too.

When only one person’s around, though, they’re more likely to react on their own gut instincts and hear your cries for help as a personal directive.

It always seems silly when people ask, “If everyone jumped off a cliff, would you?” Obviously, we’d all say no. But when actually put in that situation, because of the power of social proof, many people would jump with everyone else.

Depressing, right? So how can you make sure social proof doesn’t lead you to some of the worst-case scenarios?

All it really takes is an awareness of when you’re copying others, instead of looking at the situation in front of you and making decisions for yourself. When someone yells for help, act. When a laugh track prompts you to laugh, become more conscious of the joke. If an advertiser says their product is a top seller, do research to see if it’s actually the best.


The next principle of influence — liking — may seem pretty simple and straightforward: You’re more likely to do a favor for or buy something from someone you like.

But why do you like someone, particularly if they’re a virtual stranger, like a waiter or a sales representative? There are five criteria that greatly influence who we like.

That hot new bartender at your favorite bar? You almost certainly like him more because he’s physically attractive. When you see an attractive person, research has found it can cause a halo effect: You’re more likely to think they’re smart, kind, talented, honest, or some other virtuous trait, based on looks alone.

Similarity also plays a large factor in whether you like someone. It’s why sales people often try to establish a connection with you, unrelated to whatever they’re selling. Oh, you love hockey? Your friendly car dealer does, too!

Flattery will worm its way into your heart easily, as well. We’re highly susceptible to compliments. If someone says they like your hair, you’re more likely to like them.

These three components of liking — physical attractiveness, similarity, and compliments — are the easiest to grasp. The next two work in less obvious ways.

Have you ever heard a new song on the radio and disliked it? But then, upon hearing it for a third time some days later, you realize it’s pretty catchy? By the fifth listen, you want to put it on repeat. Research has found that increased contact with something or someone makes it more familiar, and therefore more likeable.

But in some instances, repeated exposure isn’t enough: Cooperation is also required. For example, many work environments are a delicate balance between competition and cooperation. Several people are vying to climb their way up the corporate ladder. But everyone needs to work together to finish projects. In stressful, highly competitive environments, you’d be less inclined to like your coworkers. In a highly collaborative and creative space, you’re more likely to love your teammates. These two prongs make up the “contact and cooperation” component of likeability.

Last but not least comes conditioning and association. When you were a child, your parents likely warned you not to play with the bad kids, because you would be guilty by association. If you hang out with miscreants, you must be a miscreant yourself. Who and what you associate with becomes part of your identity.

Sports are a prime example of this. When the hometown team’s doing well, people often say, “We’re doing amazing this season!” When the hometown team has lost its past five games, those same people would say, “They suck!” Good teams inspire fans to embrace their “12th-man” status, whereas bad ones cause fans to disassociate their identity with the team’s dismal success.

There are a lot of factors at play with likability. How can you possibly combat them all?

Simple. Think back to our infamous car salesman who’s been employing each weapon of influence. Then ask yourself: Do you like him more than you like the deal he’s offered you? Always take a moment to pause and consider the terms you’re agreeing to, divorced from the person you’re making them with.


When a policeman tells you to do something, you more than likely comply with the request. When a doctor gives you a diagnosis for an ongoing health problem, you most likely follow the treatment plan.

Both instances show how much people defer to authority figures. We’re taught from a young age to do so. As children, we follow the advice of parents and teachers; as adults, we seek help from professionals in fields we have little to no expertise in.

The trouble arises when people unthinkingly follow an authority’s directives. For instance, health care staff, like nurses, often also follow doctor’s orders, even when those orders should be obviously wrong to another trained professional. Since health care staff don’t think critically about what doctors tell them to do, it leads to a number of mistakes. A study in the 1980s found that US hospitals had a 12% error rate when dispensing medication to patients.

And this is a trouble that arises when people are appealing to actual authority figures. The other danger lies in how easy it is to don the guise of an authority figure.

Three symbols of authority can trigger automatic compliance, even in the absence of actual credentials. The three symbols are titles, clothes, and other status trappings.

As we’ve already seen, most people will defer to a doctor. But con artists can take advantage by merely wearing a lab coat and pretending to be a doctor. If someone is dressed as a police officer, we assume they are a police officer, even though anyone can buy these uniforms at costume shops. And anyone who presents as highclass — through status symbols like expensive jewelry or a fancy car — also is gifted the status of authority figure.

So how can you avoid getting foiled by false authorities or errant expert knowledge?

First, figure out if who you’re deferring to is truly a relevant expert. Advertisers are likely to hire fake doctors to push vitamins and other products. Don’t let the veneer of authority fool you.

Second, if the person you’re looking to really is an expert, question how truthful you think they’re being given the situation. Are they giving you the whole picture, or is it in their benefit to hold back crucial info? What do they have to gain from your compliance with their directives?


Any collector of cards or coins knows the particular and overwhelming influence of scarcity. But few realize just how persuasive it can actually be when making purchasing and political decisions.

Some common ways to play up an item’s scarcity include the “limited number tactic” and the “deadline tactic.”

For the limited number tactic, a manufacturing company may genuinely do a limited run of an item, or a sales person at a big-box store might just be pulling your leg when they say they don’t know when the next shipment of the item will come in. The deadline tactic encompasses motivators like sales and limited-time offers.

When the supply of an item is low, then the demand for that item often increases. People most desire something when it’s harder to get.

This includes limits on information. It’s why most people react poorly to anything perceived as censorship.

The principle of scarcity, then, relies on what psychologists call “reactance.” People react rebelliously to any perceived limits on freedoms they once had. Banning books or taking away purchasing opportunities elicits a greater desire to seek out or purchase those materials.

What’s so dangerous about making purchases based on perceived scarcity is that often, the scarce items function no better or worse than a non-scarce equivalent.

How can you resist the pressure to make a hasty purchase that scarcity creates?

If you became interested in an item only after hearing of its rarity, pause and consider why you really want the item. Will it be a fantastic addition to your collector’s item stash? Or does it have a specific usefulness that you seek (in other words, is it something to eat or an item to perform a chore)? If it’s the latter, remember that non-scarce items perform just as well functionally as scarce ones.


Now more than ever, it’s crucial to grasp how to protect yourself against the weapons of influence. Every day, we are baraged with more information than ever before, thanks to accelerated technological innovation. This means we increasingly rely on mechanical responses to limited information to make choices, large and small.

If you notice a brand or corporation purposefully tampering with the cues used to make sound purchases by manipulating the principles of influence, Cialdini encourages boycotting. Don’t like laugh tracks? Don’t watch shows with laugh tracks. Only when places realize they can’t profit from dishonesty will they shift to more authentic ways.

Disengage autopilot before making significant decisions in your life.

And never forget the six principles of influence:

  • Reciprocation: Small gifts can have big, profitable returns.
  • Consistency: You committed to a relationship, and you’re gonna stick with it, no matter how much it makes you unhappy now.
  • Social proof: If everyone jumped off a cliff, would you? You say no, but studies show the answer would actually be yes.
  • Liking: A well-timed compliment may be all it takes for someone to charm you into doing them a favor.
  • Authority: You’re most likely to obey doctor’s orders, even when it’s just a person dressed as a doctor in a drug commercial.
  • Scarcity: You have the overwhelming need to buy things you definitely don’t need before a fantastic sale is over.

About Robert B. Cialdini

Robert Cialdini teaches psychology and marketing at Arizona State University, after stints at Stanford University and the University of California at Santa Cruz. His book, Influence: The Psychology of Persuasion, became a business book classic despite warning against the dangers of false advertisements and automatic responses. Cialdini has also written Yes! 50 Scientifically Proven Ways to Be Persuasive and Pre-suasion.


The book is a classic text on the psychology of persuasion, which explains why people say yes to certain requests and how to apply these principles ethically in various situations. The book is based on the author’s extensive research and experience as a professor of psychology and a consultant for various organizations. The book consists of six chapters, each presenting one of the six universal principles of influence, along with examples, applications, and countermeasures. The principles are:

  • Reciprocation: People tend to feel obliged to return favors or concessions that they receive from others, even if they did not ask for them or want them. This principle can be used to elicit compliance by offering something first, such as a gift, a service, or a compromise, and then asking for something in return.
  • Commitment and Consistency: People tend to act in ways that are consistent with their previous commitments or statements, especially if they are made publicly or voluntarily. This principle can be used to elicit compliance by getting people to make small initial commitments, such as signing a petition, filling out a survey, or agreeing to a trial offer, and then asking for larger requests that are in line with those commitments.
  • Social Proof: People tend to look at what others are doing or thinking in order to decide how to behave or what to believe, especially in uncertain or ambiguous situations. This principle can be used to elicit compliance by showing that many others have already complied with the request, such as displaying testimonials, ratings, or endorsements from satisfied customers, peers, or experts.
  • Liking: People tend to say yes to those who they like or who are similar to them in some way, such as appearance, personality, background, or interests. This principle can be used to elicit compliance by increasing one’s likability or similarity with the target person, such as giving compliments, finding common ground, or cooperating on a shared goal.
  • Authority: People tend to obey or respect those who have higher status, expertise, or credibility in some domain, such as education, profession, or experience. This principle can be used to elicit compliance by displaying one’s authority or legitimacy on the subject matter, such as showing credentials, awards, or endorsements from recognized sources.
  • Scarcity: People tend to value or desire things that are rare, limited, or exclusive more than things that are abundant or easily available. This principle can be used to elicit compliance by creating a sense of urgency or exclusivity around the request, such as emphasizing the deadline, the limited supply, or the unique opportunity.

The book is an informative and engaging resource for anyone who wants to learn more about the psychology of persuasion or improve their skills and results in it. The book is written in a clear, concise, and friendly tone that makes it easy to read and understand. The book also uses vivid examples, anecdotes, humor, and emotion to convey its messages and invite its readers to reflect and relate. The book does not impose any judgments or prescriptions on its readers but rather encourages them to explore their own paths and perspectives.

The book is not only a guide but also a source of inspiration and enlightenment. It helps readers understand the essence and spirit of persuasion, and how it can help them achieve their goals and influence others positively. It also helps readers develop their skills, abilities, and potential, and achieve their goals. It motivates readers to pursue excellence, seek challenges, and overcome difficulties. It also urges readers to share their knowledge and experience with others who may benefit from them.

Overall, I think the book is a valuable addition to the literature on persuasion and personal development. It is suitable for anyone who wants to learn more about the psychology of persuasion or improve their skills and results in it. I highly recommend it to anyone who is interested in this topic.

Alex Lim is a certified book reviewer and editor with over 10 years of experience in the publishing industry. He has reviewed hundreds of books for reputable magazines and websites, such as The New York Times, The Guardian, and Goodreads. Alex has a master’s degree in comparative literature from Harvard University and a PhD in literary criticism from Oxford University. He is also the author of several acclaimed books on literary theory and analysis, such as The Art of Reading and How to Write a Book Review. Alex lives in London, England with his wife and two children. You can contact him at [email protected] or follow him on Website | Twitter | Facebook

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