Influence: The Psychology of Persuasion by Robert Cialdini

Influence: The Psychology of Persuasion by Robert Cialdini

The Book in a Few Sentences

"You couldn’t start with a better book than Cialdini’s 'Influence,'" says Charlie Munger. If you like Malcolm Gladwell's books, you'll love this.

Influence: The Psychology of Persuasion summary

This is my book summary of Influence by Robert Cialdini. My summary and notes include the key lessons and most important insights from the book.


  • Just what are the factors that cause one person to say yes to another person? And which techniques most effectively use these factors to bring about such compliance?
  • Those who don’t know how to get people to say yes soon fall away; those who do, stay and flourish.
  • Although there are thousands of different tactics that compliance practitioners employ to produce yes, the majority fall within six basic categories. 
  • Each of these categories is covered by a fundamental psychological principle that directs human behavior, and, in so doing, gives the tactics their power.
  • Finally, each principle is examined as to its ability to produce a distinct kind of automatic, mindless compliance from people, that is, a willingness to say yes without thinking first.
  • The evidence suggests that the ever-accelerating pace and informational crush of modern life will make this particular form of unthinking compliance more and more prevalent in the future.

Chapter 1: Weapons of Influence

  • …we, too, have our preprogrammed tapes; and, although they usually work to our advantage, the trigger features that activate them can be used to dupe us into playing them at the wrong times. 
  • A well-known principle of human behavior says that when we ask someone to do us a favor we will be more successful if we provide a reason. People simply like to have reasons for what they do.
  • Excuse me, I have five pages. May I use the Xerox machine because I’m in a rush? 
  • The effectiveness of this request-plus-reason was nearly total: Ninety-four percent of those asked let her skip ahead of them in line.
  • It seems that it was not the whole series of words, but the first one, “because,” that made the difference.
  • In fact, automatic, stereotyped behavior is prevalent in much of human action, because in many cases it is the most efficient form of behaving, and in other cases it is simply necessary. 
  • You and I exist in an extraordinarily complicated stimulus environment…To deal with it, we need shortcuts.
  • Unlike the mostly instinctive response sequences of nonhumans, our automatic tapes usually develop from psychological principles or stereotypes we have learned to accept.
  • There is a principle in human perception, the contrast principle, that affects the way we see the difference between two things that are represented one after another. 
  • Simply put, if the second item is fairly different from the first, we will tend to see it as more different than it actually is.
  • The great advantage of this principle is not only that it works but also that it is virtually undetectable.

Chapter 2: Reciprocation

  • The rule says that we should try to repay, in kind, what another person has provided us.
  • …there is no human society that does not subscribe to the rule. And within each society it seems pervasive also: it permeates exchanged of every kind.
  • A widely shared and strongly held feeling of future obligation made an enormous difference in human social evolution, because it meant that one person could give something (for example, food, energy, care) to another with confidence that it was not being lost.

The Rule Enforces Uninvited Debts

  • Although the obligation to repay constitutes the essence of the reciprocity rule, it is the obligation to receive that makes the rule so easy to exploit. The obligation to receive reduces our ability to choose whom we wish to be indebted to and puts that power in the hands of others.

The Rule Can Trigger Unfair Exchanges

  • Most of us find it highly disagreeable to be in a state of obligation.
  • In combination, the reality of internal discomfort and the possibility of external shame can produce a heavy psychological cost.

Reciprocal Concessions

  • Another consequence of the rule, however, is an obligation to make a concession to someone who has made a concession to us.
  • Suppose you want me to agree to a certain request. One way to increase your chances would be first to make a larger request of me, one that I will most likely turn down. Then, after I have refused, you would make the smaller request that you were really interested in all along.

Chapter 3: Commitment and Consistency

  • Once we have made a choice or take a stand, we will encounter personal and interpersonal pressures to behave consistently with that commitment. Those pressures will cause us to respond in ways that justify our earlier decision.
  • We all fool ourselves from time to time in order to keep our thoughts and beliefs consistent with what we have already done or decided.
  • Inconsistency is commonly thought to be an undesirable personality trait.
  • Once we have made up our minds about an issue, stubborn consistency allows us a very appealing luxury: We really don’t have to think hard about the issue anymore.

Commitment Is the Key

  • Once a stand is taken, there is a natural tendency to behave in ways that are stubbornly consistent with the stand.
  • The tactic of starting with a little request in order to gain eventual compliance with related larger requests has a name: the foot-in-the door technique.
  • What the Freedman and Fraser findings tell us, then, is to be very careful about agreeing to trivial requests. Such an agreement can not only increase our compliance with similar, much larger requests, it can also make us more willing to perform a variety of larger favors that are only remotely connected to the little one we did earlier.
  • …once you’ve got a man’s self-image where you want it, he should comply naturally with a whole range of your requests that are consistent with this view of himself. 

The Magic Act

  • Our best evidence of what people true feel and believe coms less from their words than from their deeds.
  • …a written declaration has some advantages. First, it provides physical evidence that the act occurred. 
  • A second advantage of a written testament is that it can be shown to other people. Of course, that means it can be used to persuade those people. It can persuade them to change their own attitudes in the direction of the statement. 
  • People have a natural tendency to think that a statement reflects their true attitude of the person who made it. 
  • What is surprising is that they continue to think so even when they know that the person did not freely choose to make the statement.
  • Unless there is strong evidence to the contrary, observers automatically assume that someone who makes such a statement means it.
  • And, as we will see in Chapter 4, what those around us think is true of us is enormously important in determining what we ourselves think is true.
  • Once an active commitment is made, then, self-image is squeezed from both sides by consistency pressures. 
  • From the inside, there is a pressure to bring self-image into line with action. From the outside, there is sneakier pressure—a tendency to adjust this image according to the way others perceive us.

The Public Eye

  • One reason the written testaments are effective in bringing about genuine personal change is that they can so easily be made public.
  • Whenever one takes a stand that is visible to others, there arises a drive to maintain that stand in order to look like a consistent person.

The Effort Extra

  • And the evidence is clear that the more effort that goes into a commitment, the greater is its ability to influence the attitudes of the person who made it.
  • …”persons who go through a great deal of trouble or pain to attain something tend to value it more highly than persons who attain the same thing with a minimum of effort.
  • Given Aronson and Mills’s demonstration that the severity of an invitation ceremony significantly heightens the newcomer’s commitment to the group, it is hardly surprising that groups will oppose all attempts to eliminate this crucial link to their future strength.

The Inner Choice

  • Social scientists have determined that we accept inner responsibility for behavior when we think we have chosen to perform it in the absence of strong outside pressures.
  • A large reward is one such external pressure. It may get us to perform a certain action, but it won’t get us to accept inner responsibility for the act. 
  • Consequently, we won’t feel committed to it. 
  • The same is true of a strong threat; it may motivate immediate compliance, but it is unlikely to produce long-term commitment.
  • No matter which variety of lowballing is used, the sequence is the same: An advantage is offered that induces a favorable purchase decision; then, sometime after the decision has been made but before the bargain is sales, the original purchase advantage is deftly removed.

How to Say No

  • “Knowing what I know now, if I could go back in time, would I make the same choice now?”
  • Accumulating psychological evidence indicates that we experience our feelings toward something a split second before we can intellectualize about it. 
  • Therefore, if we train ourselves to be attentive, we should register it ever so slightly before our cognitive apparatus engages.

Chapter 4: Social Proof

  • It states that one means we use to determine what is correct is to find out what other people think is correct.
  • The principle applies especially to the way we decide what constitutes correct behavior. 
  • We view a behavior as more correct in a given situation to the degree that we see others performing it.

Cause of Death: Uncertain(ty)

  • In general, when we are unsure of ourselves, when the situation is unclear or ambiguous, when uncertainty reigns, we are most likely to look to and accept the actions of others as correct.
  • Especially in an ambiguous situation, the tendency for everyone to be looking to see what everyone else is doing can lead to a fascinating phenomenon called “pluralistic ignorance.”

Monkey Me, Monkey Do

  • The principle of social proof operates most powerfully when we are observing the behavior of people just like us.

How to Say No

  • First, we seem to assume that if a lot of people are doing the same thing, they must know something we don’t. 
  • Especially when we are uncertain, we are willing to place an enormous amount of trust in the collective knowledge of the crowd. 
  • Second, quite frequently the crowd is mistaken because they are not acting on the basis of any superior information but are reacting, themselves, to the principle of social proof.

Chapter 5: Liking

  • …the professionals’ compliance strategy is quite direct: They first get us to like them.
  • What are the factors that cause one person to like another person?

Physical Attractiveness

  • Research has shown that we automatically assign to good-looking individuals such favorable traits as talent, kindness, honesty, and intelligence.
  • For example, a study of the Canadian federal elections found that attractive candidates received more than two and a half times as many votes as unattractive candidates.
  • They [attractive people] are better liked, more persuasive, more frequently helped, and seen as possessing better personality traits and intellectual capacities. 


  • We like people who are similar to us. This fact seems to hold true whether the similarity is in the area of opinions, personality traits, background, or life-style.


  • We are phenomenal suckers for flattery. 
  • …we tend, as a rule, to believe praise and to like those who provide it, oftentimes when it is clearly false.

Contact and Cooperation

  • For the most part, we like things that are familiar to us.
  • It appears that in an election booth voters often choose a candidate merely because the name seems familiar.

Conditioning and Association

  • There is a natural human tendency to dislike a person who brings us unpleasant information, even when that person did not cause the bad news.
  • An innocent association with either bad things or good things will influence how people feel about us.
  • As distinguished author Isaac Asimov put it in describing our reactions to the contests we view, “All things being equal, you root for your own sex, your own culture, your own locality…and what you want to prove is that you are better than the other person. Whomever you root for represents you; and when he wins, you win.”
  • According to the association principle, if we can surround ourselves with success that we are connected with in even a superficial way (for example, place of residence), our public prestige will rise.

Chapter 6: Authority

  • It has to do, he [Stanley Milgram] says, with a deep-seated sense of duty to authority within us all.
  • “It is the extreme willingness of adults to go to almost any lengths on the command of an authority that constitutes the chief finding of the study.”

Connotation, Not Content

  • When in a click, whirr mode, we are often as vulnerable to the symbols of authority as to the substance.


  • Studies investigating the way in which authority status affects perceptions of size have found that prestigious titles lead to height distortions.


  • A second kind of authority symbol that can trigger our mechanical compliance is clothing.


  • Finely styled and expensive clothes carry an aura of status and position, as do trappings such as jewelry and cars.
  • The experimenters discovered that motorists would wait significantly longer before honking their horns at a new, luxury car stopped in front of a green traffic light than at an older, economy model.

How to Say No

  • By wondering how an expert stands to benefit from our compliance, we give ourselves another safety net against undue and automatic influence.

Chapter 7: Scarcity

  • The idea of potential loss plays a large role in human decision making. In fact, people seem to be more motivated by the thought of losing something than by the thought of gaining something of equal value.
  • For instance, homeowners told how much money they could lose from inadequate insulation are more likely to insulate their homes than those told how much money they could save.
  • Probably the most straightforward use of the scarcity principle occurs in the “limited number” tactic, when the customer is informed that a certain product is in short supply that cannot be guaranteed to last long.
  • Related to the limited-number technique is the “deadline” tactic, in which some official time limit is placed on the customer’s opportunity to get what the compliance professional is offering.

Psychological Reactance

  • Like the other weapons of influence, the scarcity principle trades on our weakness for shortcuts.
  • In addition, there is a unique, secondary source of power within the scarcity principle: As opportunities become less available, we lose freedoms; and we hate to lose the freedoms we already have.
  • When our freedom to have something is limited, the item becomes less available, and we experience an increased desire for it.
  • Freedoms once granted will not be relinquished without a fight.
  • …research shows that parents who enforce discipline inconsistently produce generally rebellious children.
  • Not only do we want the same item more when it is scarce, we want it most when we are in competition for it.
  • Here’s our predicament, then: Knowing the causes and workings of scarcity pressures may not be sufficient to protect us from them because knowing is a cognitive thing, and cognitive processes are suppressed by our emotional reaction to scarcity.
  • Perhaps, in fine jujitsu style, we can use the arousal itself as our prime cue. 
  • Rather than relying on a considered, cognitive analysis of the entire situation, we might simply tune ourselves to the internal, visceral sweep for our warning.
  • Therein lies an important insight. The joy is not in experiencing a scarce commodity but in possessing it. 
  • As soon as we feel the tide of emotional arousal that flows from scarcity influences, we should use that rise in arousal as a signal to stop short. 
  • Panicky, feverish reactions have no place in wise compliance decisions. 
  • We need to calm ourselves and regain rational perspective.
  • Once this is done, we can move to the second stage by asking ourselves why we want the item under consideration.Quite simply, we need to recall that the scarce cookies didn’t taste any better.

Epilogue: Instant Influence

  • All this leads to a jarring insight: With the sophisticated mental apparatus we have used to build world eminence as a species, we have created an environment so complex, fast-paced, and information-laden that we must increasingly deal with it in the fashion of the animals we long ago transcended.
  • Unlike the animals, whose cognitive powers have always been relatively deficient, we have created our own deficiency by constructing a radically more complex world.