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Influence by Robert B. Cialdini.
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Influence: The Psychology of Persuasion explores the art of compliance. It sets out to answer the question, “How do we become convinced to do the things that we do?”

A lot of persuasion rests on the manipulation of human fixed-action patterns. Fixed-action patterns are the mental shortcuts and assumptions that we use to fill in the blanks of our everyday experience. For example, we assume that when other drivers on the road are braking, we should brake too. Or that a long line of people means that there must be some desirable attraction at the end. Or that a high price for an item at the store indicates that it’s rarer or of higher quality (or both). A fixed-action pattern causes us to respond in the same, predictable way to certain stimuli, over and over again.

These fixed-action patterns are useful because it’s impossible for us to individually assess every single situation on its own merits: we would just get overwhelmed with information and be unable to make any decisions at all. These shortcuts let us make decisions without being burdened by endless analysis and weighing of pros and cons. And usually, our fixed-action patterns lead us to the right conclusions and help us make correct decisions.

Compliance Practitioners

While our fixed-action patterns are usually an asset for us in everyday life, they are easily manipulated and exploited by compliance practitioners. These are professional persuaders, people whose job it is to get you to say “yes” to whatever it is they’re offering. They’re usually salespeople, but they can also be fundraisers asking you to contribute to a charitable cause or sign a petition, or they can be politicians asking for your vote. If they’re trying to get you to do something that you wouldn’t do on your own, they’re a compliance practitioner.

These individuals are very skilled at using our fixed-action patterns against us: that is, they manipulate us into behaving the right way in response to the wrong stimuli. A store owner might, for example, mark up the price of a low-quality item to make it more desirable to you: knowing full-well that your mental shortcut would usually lead you to believe that a high-priced item is of high quality. They’re turning your fixed-action advantage into a powerful disadvantage that clouds your judgement and leads you to make faulty decisions.

Most compliance practitioners use six psychological principles of persuasion:

  1. Reciprocity
  2. Commitment/Consistency
  3. Social proof
  4. Liking
  5. Authority
  6. Scarcity

Reciprocity

The Reciprocity Principle tells us to repay others when they do something for us. Most of the time, it just feels like common decency: when a friend treats you to lunch, you pay for their meal the next time; when your neighbors invite you over, you return the courtesy.

The principle is an evolutionary inheritance: early human communities with strong social cohesion and an ability to work together had a better chance of survival. By knowing that a favor would be returned, reciprocity helped to lower the “costs” of helping one’s neighbors and kin.

Thus, compliance practitioners know that you’re more likely to feel obliged to them if they present you some small gift or token gesture of kindness before they make their request. This is why sellers are so fond of promotional offers, free samples, and small gifts: they know you’ll respond with a “gift” of your own by buying whatever it is they’re trying to promote. Or they’ll ask for an initially ludicrous request that you’ll reject, only to present you with a second, smaller request. This rejection-then-retreat tactic is designed to lull you into making a reciprocal concession by giving in to their second ask.

To say “no” to this kind of reciprocity, you have to distinguish between people who are engaging in genuine acts of kindness and those who are simply trying to trick you into doing something for them. You are socially obligated to return a genuine favor with another favor: you’re not obligated to return a trick with a favor.

Commitment/Consistency

The Consistency Principle says that humans have an obsession with sticking to their guns. Once we’ve committed to something, we pressure ourselves to conform to that commitment. In fact, we’ll convince ourselves that our current behavior and beliefs align with our past behavior and beliefs, even when they clearly don’t.

For example, gamblers who are unsure about their bets before they place them have been shown to be far more confident after they’ve put their money on the table. They convince themselves that they were always confident in the horse they picked or the color on the roulette wheel they chose.

Consistency is generally useful for day-to-day human experience and it’s usually a good attribute for someone to have. It frees us from potential mental overload by giving us an easy, one-size-fits-all guide for how to react to a multitude of situations and people that we encounter each day.

Unfortunately, consistency and commitment can also be exploited. Our desire for internal consistency can turn even a small commitment into larger and larger ones. In one California study, homeowners were shown to be far more willing to have an unsightly billboard installed on their property after they had agreed to have a much smaller one erected a few weeks earlier. Thus, compliance practitioners who are “only” asking you to sign a petition or answer a few seemingly innocuous questions are usually trying to build you...

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Influence Summary Influence Guide Chapter 1: Fixed-Action Patterns

Have you ever been persuaded to purchase something that you later regretted? Or been manipulated into contributing money to a charitable cause that you didn’t actually support? If your answer is “yes,” then don’t worry: you’re hardly alone.

Every day, we are bombarded with advertisements and appeals that ask us to buy something, join some organization, or get involved in some cause. Clearly, there is great advantage in persuading people to do things.

But who are these persuaders and how are they so effective at manipulating us into doing what they want?

Compliance Practitioners

A compliance practitioner is anyone whose job is to get you to say “yes” to what they’re offering. They can be:

  • A salesperson who wants you to buy her product.
  • An activist who wants you to volunteer for her cause.
  • A fundraiser who wants you to donate to her charity.
  • A politician who wants you to vote for her.

Their specific agendas may be different, but they’re all after the same thing. They’re all in the persuasion business and they all want to persuade you. How do they do this? By manipulating the decision-making instincts that get you to say “yes” before you even...

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Influence Summary Influence Guide Chapter 2: The Reciprocity Principle

The Reciprocity Principle tells us to repay others when they do something for us. This fixed-action pattern of behavior is so deeply ingrained that we hardly think about it, yet we practice it all the time. When a friend treats you to lunch, you make sure you pick up the check the next time you go out; when your neighbors invite you to a party, you invite them the next time you’re hosting an event.

That the phrase “much obliged” is a synonym for “thank you” is a powerful encapsulation of the Reciprocity Principle: we naturally feel obliged, indebted to those who have done something for us.

The Reciprocity Principle can even extend beyond these small day-to-day courtesies to the world of international diplomacy. When Mexico City was devastated by an earthquake in 1985, Ethiopia dutifully made a foreign aid contribution to help the rebuilding and recovery effort. But why would a country like Ethiopia, poverty-stricken and suffering through a devastating famine, spend its scarce resources to help people all the way on the other side of the world? Simple: the Reciprocity Principle. In 1935, when Ethiopia was invaded and occupied by the Italians, Mexico was one of the few...

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Shortform Exercise: Return the Favor, Not the Trick

Avoid getting sucked into the reciprocity trap.


Have you ever agreed to do something you didn’t want to do because someone gave you an initial concession or performed a small favor for you? If so, describe why you felt compelled to comply with this person’s request.

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Influence Summary Influence Guide Chapter 3: The Consistency Principle

The Consistency Principle says that humans have an obsession with sticking to their guns. Consistency is closely related to commitment. Once we’ve committed to a course of action or to a belief, we pressure ourselves to conform to that commitment. We go through great mental gymnastics to convince ourselves that our current behavior and beliefs align with our past behavior and beliefs, even when they clearly don’t.

In one Canadian study, experimenters looked at the beliefs and behavior of bettors at a racetrack. Thirty seconds before they placed their bets, they were uncertain about their horse. Just thirty seconds after, however they were far more optimistic and confident in their choices. Nothing had objectively changed in this short span of time. The Consistency Principle just forced the bettors to bring their beliefs into line with the action they had already committed to.

The principle creates a valuable opening for those ever-present compliance practitioners. By getting you to make just a small commitment, a skilled compliance practitioner can get you to make larger and larger ones.

Freedom From Thought: Why We’re So Consistent

Like the other instincts,...

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Shortform Exercise: Questioning Your Beliefs

Fight the urge to be stubbornly consistent.


Think of something that you now believe in strongly that you didn’t used to believe in. In a few sentences, describe the differences between your past belief and your current belief, and why you’ve come to see things differently.

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Influence Summary Influence Guide Chapter 4: The Social Proof Principle

The Social Proof Principle states that we decide what’s correct based on what other people think is correct. If lots of other people are doing something or thinking something, then it must be good and worthy of imitation.

We see this all the time in everyday life. When we see a crowd of people forming on a street, we instinctively want to join. “If all those people are gawking at something, it must be something interesting that’s worth checking out,” our brains tell us.

As you can probably guess by now, however, compliance practitioners of all stripes are very good at manipulating social proof to get us to behave in ways that we otherwise wouldn’t.

For example, look at canned laughter on TV sitcoms. Although it’s not as prevalent as it was a generation ago, TV producers still overlay recordings of human laughter following “funny” lines on the show. Experiments show that the audience watching at home finds the show funnier if they hear other people laughing.

The Social Proof Principle is strong enough to override our basic intuition and knowledge. **We laugh along with the laugh track even when the underlying content isn’t funny, and even when we know that it’s a...

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Shortform Exercise: Be An Individual

See how you can resist the pull of social proof.


Have you ever gone along with group behavior, despite your own private reservations about what the group was doing? Describe how you felt and why you decided to do as others were doing.

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Influence Summary Influence Guide Chapter 5: The Liking Principle

The Liking Principle stipulates that we’re more likely to comply with requests from people that we know and like. Thus, we are more amenable to the compliance efforts of neighbors, friends, and family, or from people who claim to know them. We are also more willing to acquiesce to people who we see as being good-looking, affable, or who profess to like us.

As you’ve probably guessed, however, this principle of human behavior creates a wide opening for compliance practitioners who wish to exploit it for personal gain. If they can get us to like them, we’re much more likely to be putty in their hands. If you like the seller, you’ll like what she’s selling.

(Shortform note: It makes sense, from an evolutionary and group cohesion perspective, why we would be more willing to comply with the wishes of people we know. Early human communities were extended kinship groups, where the survival of the individual was closely tied to the larger familial group. In this world of localized, tight-knit communities, helping people in your in-group was a valuable survival trait: you relied on them to help with the necessities of life, like food-gathering and child-rearing. The...

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Shortform Exercise: Principles, Not Personality

Make rational decisions based on their own merits, not because you like the person asking you to make them.


Have you ever been in a situation where you found yourself liking a person more than you otherwise would, given the circumstances? In a few sentences, explain what happened.

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Influence Summary Influence Guide Chapter 6: The Authority Principle

The Authority Principle states that people are hard-wired to comply with requests that come from an acknowledged and accepted source of authority. Thus, we are strongly inclined to be deferential to people who we consider to be in a position of power or expertise. Examples would include teachers, members of the armed forces, police officers, doctors, and judges, to name just a few.

The instinct is so powerful that humans are responsive even to the mere vestiges or symbols of authority—titles, uniforms, and insignia can exert a strong influence. Given this strong fixed-action pattern of compliance, it is no wonder that compliance professionals know how to use the appearance or suggestion of authority to force us to accede to their requests.

Origins of Authority

Like the other fixed-action instincts, there are good and legitimate reasons why we’re strongly conditioned to obey authority. Leadership, hierarchy, and authority are obviously necessary ingredients in any functioning society.

Unless we want a state of complete anarchy and lawlessness, there’s always going to be somebody making decisions and giving orders. Authority of some people over others was a great...

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Shortform Exercise: Questioning Authority

Discover when you should and shouldn’t listen to authority.


Have you ever complied with a request from an authority figure who turned out to be illegitimate or self-serving? Describe what happened.

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Influence Summary Influence Guide Chapter 7: The Scarcity Principle

The Scarcity Principle tells us that we find more appealing those things with limited availability. On a basic level, we encounter this all the time: rare goods are expensive, while abundant items are cheap.

Scarcity is closely related to the idea of loss aversion. As humans, we are powerfully guided by our desire to avert losing what we already have. We are inherently conservative and cautious. Loss aversion is a strong framing effect: we are more afraid of losing something than we are enticed by the hope of gaining something of equal value.

As you know by now, compliance practitioners know how to frame their proposals to make them seem like rare, fleeting opportunities that we’ll miss if we don’t capitalize on them immediately. “Limited-time only” or “first come, first serve” sales offers are the most common use of the Scarcity Principle. Compliance practitioners can greatly enhance the appeal of their product if they can convince you that what they’re selling is in short supply, will be taken off the market imminently, or is only available to an exclusive set of customers.

The Scarcity Principle is powerful because it manipulates our desire to be in control and...

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Shortform Exercise: Wanting Things For The Right Reasons

Figure out whether you really want what you think you want.


Have you ever wanted something, solely because it was rare or difficult to obtain? Describe your emotions and thought process.

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Influence Summary Influence Guide Conclusion

By reading this summary, you’ve hopefully gleaned some important insight into how the compliance practitioners of the world are looking to pull the wool over your eyes by manipulating your fixed-action patterns.

Whether through reciprocity, consistency/commitment, social proof, liking, authority, or scarcity, the goal is always...

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Shortform Exercise: Checking Your Blind Spots

Examine your own mental blind spots.


Of the six principles of persuasion described in this summary, which one do you feel you’re the most vulnerable to? Explain why.

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Table of Contents

  • 1-Page Summary
  • Chapter 1: Fixed-Action Patterns
  • Chapter 2: The Reciprocity Principle
  • Exercise: Return the Favor, Not the Trick
  • Chapter 3: The Consistency Principle
  • Exercise: Questioning Your Beliefs
  • Chapter 4: The Social Proof Principle
  • Exercise: Be An Individual
  • Chapter 5: The Liking Principle
  • Exercise: Principles, Not Personality
  • Chapter 6: The Authority Principle
  • Exercise: Questioning Authority
  • Chapter 7: The Scarcity Principle
  • Exercise: Wanting Things For The Right Reasons
  • Conclusion
  • Exercise: Checking Your Blind Spots