Influence: The Psychology of Persuasion Book Summary

Influence: The Psychology of Persuasion

By Robert B. Cialdini PH.D.

Influence is a fascinating book. Seems to be a “must read” for anyone that will be purchasing something in their lifetime… so everyone. It takes a purely psychological approach to what influences people, and dives into the “hacks” that marketers and salesmen use to trigger an automated response that we have been conditioned to produce over millions of years of evolution.At the end of the book he talks about how this ‘problem’ is only going to get worse as we need to sort through an ever expanding amount of information.Our brains have developed shortcuts which allow us to automate decisions, but it leaves us vulnerable to people who know how to target what triggers these shortcuts.

The book is broken out into six different “influencers” talks through studies, examples, how to avoid, anecdotes, etc. The six influencers are:

  1. Reciprocation
  2. Commitment and consistency
  3. Social Proof
  4. Liking
  5. Authority
  6. Scarcity

These can be exploited by marketers, and Cialdini writes in the viewpoint as goes at it from a “how can you recognize and defend yourself” to this advantage being used against you? When introducing the topic in the book he talks about “fixed action patterns” where the behaviors that compose them occur in virtually the same vashion and in the same order every time. For example using the word “because” even if the reason isn’t important. People just want a reason, an example given was to ask if you can cut in line to the copier at work. If you say instead “Excuse me, i have five pages, may I use the copier because i need to make copies“. This use of the word ‘because’ triggers a response since all we are really looking for is a reason to comply, even if it is a mediocre one.

When in doubt about the value of an object, people will defer to the price tag. They will naturally assume that a higher priced item is worth more. An example in the book page 5 about a jewelry store that mistakenly said “everything on this shelf 2X price” and it all sold because people perceived its value as being higher.

Perceptual contrast is another principle that impacts judgement. We react to things based on what events precede them. For an example, there is an anecdote from a college coed about how she wrote home to her parents about a fire in the dorms, scull fracture, was in the hospital, is living with a gas station attendant that knocked her up etc. Then at the end she says that none of that was true, but she is getting an F in chemistry and wanted them to see it from the proper perspective.



Reciprocity shows us that we have a certain obligation to the future repayment of favors, gifts, etc. This is illustrated by the Krishnas who had a fundraising tactic where they would employ the rules of reciprocity. A pedestrian at highly trafficked area (airport, train station, etc.) would be given a small “gift” (book, flower, etc.) when they would try to give it back the Krishna would say “no it is our gift to you” after which the pedestrian who wanted nothing to do with this to begin with would donate to the Krishna. After some digging the researchers in the study found that once the Krishna was out of flowers, they would go around to the trash cans and pick up the ones people had already thrown away from earlier. This is also seen in “free samples”, Free sample “BUG” that Amway used with great success. There is an interesting example about how the reciprocity rule can induce a much more favorable return on page 30-31. The idea is they are a benefactor before beggar. Before asking for something/favor, you need to give them a good reason, even if it is just buying them a coke. See pg. 33 for “unfair exchanges”. We do not want to be labeled or even think of ourselves as a moocher, so we comply.

Cialdini also talks about Reciprocal Concessions. An example is of a boy scout that asked him if he wanted to go to the boy scout circus- tickets were $5 each. He said no because it was the last place he wanted to spend his Saturday night. The Boy Scout said “well, if you don’t want to buy any tickets, how about buying some of our big chocolate bars?” He bought the bars despite not wanting them and realized what had happened. As a consequence of the reciprocation rule, we have an obligation to make a concession to someone who has made a concession to us. The boy scout’s concession had been a $1 candy bar vs. $5 circus ticket, the author’s concession was buying the chocolate bars despite not wanting them. As with all rules in this book, he says this will not work always, and on everyone, but it can have the influential effect. This can be used by marketers to increase your chances of a request- similar to the anchoring cognitive bias: Make a larger request first, then after you have refused make the smaller request you were interested in all along. It is a rejection then retreat method. It can also be used on both the buying and selling side. When buying something on craigslist for example listed for $500, first offer $300, then when it is rejected, go $350, then $375… and don’t be afraid to walk. In sales a “larger then smaller” sequence is often followed: show a very expensive model, then show the one you want them to buy. Pool table example on page 47. The rejection-then-retreat tactic also has the ability to prompt its victims to agree to further requests. since it is all about forcing compliance, the victims more likely to feel more satisfied with the arrangements as a result.

How to say no- try to reject the initial concession. See any gifts or favors as a sales device to avoid falling into the reciprocation sale. “After all, the reciprocity rule asserts that if justice is to be done, exploitation attempts should be exploited.”

Commitment and Consistency

This lever of influence is based on the assumption that it is typically in our best interest to be consistent. so we fall into the habit even in situations that it does not help us. It is a big shortcut we use to sift through and make decisions without actually having to think about them. There is an example of commitment and consistency on page 63-64 with Transcendental Meditation sales tactics. After Cialdini’s friend poked logical holes in the things the salespeople were saying people still signed up afterwards. When asked, they said things like “I wasn’t going to sign up today, but when your buddy started talking I knew I had to give them my money now or i would go home and start thinking about what he said and never sign up.” They were searching for an answer to their problems and they were trying to believe it was their answer: “TM? certainly i think it will help me; certainly i expect to continue; certainly i believe in TM. i already put my money down for it didn’t i?” Now these people do not have to keep searching for a different way to solve their problems. People want to be consistent with the decisions they have already made. This power the desire to be consistent has over us can be controlled by forcing that engagement in the first place. This is where the commitment part comes in! Cialdini argues “If I can get you to make a commitment (take a stand, go on record), I will have set the stage for your automatic and ill considered consistency with that earlier commitment.” Telephone solicitors for charity often deploy a strategy that takes advantage of this vulnerability: they ask first ask about your health/well being “how are you feeling this evening/how are you doing today”once you state that you are A-O.K. publicly they will say something like “glad to hear that, because I am calling to ask if you would be willing to make a donation to help the unfortunate victims of…”. They will feel awkward/ do not want to appear stingy in the context of their favorable circumstances. There is an interesting story in the book on pg 70-71 about the Chinese during the Korean war about how they treated POWs and got them to comply with even collaborate with the enemy in some way or another. They used the principles of consistency to slowly shape the dialogue of the prisoners to be pro-communist. They would start with writing letters and then make public acknowledgements, read essays they wrote about “problems with America” etc. Since these announcements were public the POW’s slowly began finding themselves as collaborators that had given aid to the enemy.

There is also a certain committing power of written statements- set a goal, write it down. For people to set goals and hold themselves accountable to them done at Amway. Quote from the book is ” something special happens when people personally put their commitments on paper: they live up to what they have written down.” Public commitments tend to be lasting commitments. Cialdini also talks about Fraternity hazing, or Hell Week as it is called. The reason hazing is done and is so effective is that there is a strong correlation between brutal initiation rites and group solidarity. You see this in Fraternities, African tribes, the Army, etc. So in order to get the most loyal people in the world you put them through the crucible to make what they belong to more important to them. A note for rearing children: “we should never heavily bribe or threaten our children to do things we want them to truly believe in” Instead you want them to believe in the correctness of what they have done. We want them to accept inner responsibility for the the actions we want them to take.

How to say NO- Ralph Waldo Emerson said “A foolish consistency is the hobgoblin of little minds.”- Cialdini writes “While consistency is generally good, even vital, there is a foolish, rigid variety to be shunned.” See the anecdote on pages 105-108. Once you realize you are trapped in their game call them out on it. That you would be a “sucker to comply with their request merely because doing so would be consistent with some prior commitment.”

Social Proof

Nobody likes canned laughter, but TV executives use it anyways despite this. Why is it that they still use them, and they are so effective. When looking at studies, they have found that audiences react more favorably to jokes with canned laughter. It is an internal automatic “tape” that gets cued when we hear laughter. Very similar- Bartenders “salt” their tip jars, church ushers salt collection baskets etc. it tells people what other people are doing as the social norm. Another form of social proof comes in the form of cults, cult believers and leaders. For example doomsday cults over the years have been proven wrong, only to use it to reconfirm their beliefs and double down on a later date. This exact scenario can be seen in the Munster Rebellion (listen to the Hardcore History Podcast for this!). A key to social proof, Cialdini argues, is uncertainty. “when uncertainty reigns, we are most likely to look and accept the actions of others as correct.” The problem is that the people you are following are also looking around to see what the other people are doing as correct. It is called “pluralistic ignorance”. Examples of this can be seen in Catherine Genovese, a woman who was brutally stabbed in front of many witnesses, but nobody stopped the man who did it or even called the police until she was dead. The dialogue goes like this, “nobody else is helping her, everything must be okay” “someone else probably already called the police”. If you are walking down the street and someone appears to be in trouble, but everyone else is just walking by with no concern you will feel like it probably isn’t a big deal since the person in front of you wasn’t concerned. What to do if you are ever in trouble like this? You should talk directly to a person that you single out, give them instructions. This social proof will have the other effect of everyone piling to help. It is because when there are many people, the responsibility is spread across those people. In smaller groups, it is more likely something will be done. It is because the responsibility is spread across the people present.

Social proof does work better in some conditions than it does others. One condition is “similarity”. “The principle of social proof operates most powerfully when we are observing the behavior of people just like us”. That is why advertisers hire actors that their target audience can relate to (middle aged man, busy mother, cool kid). There is an interesting part of the book that looks at suicide rates, car accidents, plane crashes etc. following a highly publicized suicide. They find that it is especially correlated when the publicized suicide is in the demographic of the people that committed suicide in the following months. Another story about The People’s Temple – a cult that killed themselves in Jamestown, Guyana South America on page 152-153 outlines some interesting details about the mass suicide how once people started doing it others followed suit.The question is also raised  “if the community had remained in San Fransisco, would Rev. Jim Jones’s Suicide command have been obeyed?” while speculative, the question stems from the people being completely removed from the rest of the world. Another note here is “herd” mentality, similar to cattle going to the slaughterhouse by following the cow in front of them. The marketer asks “How do i get people moving in the same direction?”

How to say NO! Cialdini says there are two types of scenarios regarding social proof to watch out for. The first is when social evidence has been falsified- such as canned laughter, and other canned responses that are meant to trigger a similar response in the viewer. Beware of commercials with real customer testimonials, even if they are “real customers” the company is only going to cherry pick and advertise the favorable responses to their product. A point is also made that we trust the knowledge of the crowd: “best selling” “fastest growing” etc. make people more confident in their choice. We as people are willing to place a lot of trust in the collective knowledge of the crowd, and an autopilot device like social proof should never be trusted fully. One more example is one I can pull from my own experience in hunting. Deer are wary animals, very cautious about going into new areas and they will often communicate with their tails. Tail up means “watch out” for example. To exploit this, hunters will often use a decoy- if using a doe you could be signaling to other does that “all is clear and safe over here”. The same principle applies to duck decoys- the social proof tells flying ducks that this is a safe place to land.


The liking rule is a brutal one. We are more likely to say yes to the people we know and like than some random stranger. Case in point is the Tupperware party- they have all kinds of these things these days: bags, fake nails, makeup… the idea is that it is a lot more difficult to say no to friends. The Tupperware party has several weapons of influence- reciprocity, commitment, social proof, and most of all liking (the host)- you can see a more detailed breakdown on page 167. Salesmen will also try to imitate you in ways, you should be careful around salesmen who seem to be just like you: posture, mood, verbal style, hobbies, etc. they are using a “mirror and match” technique. The book also looks at a study with African American desegregation, what it reminded me of was the movie Remember the Titans, where they needed mutual cooperation in order to have success. Only after they cooperated and collaborated with each other did they start to create bonds and friendships and see past the color of their skin. Another good illustration of the liking principle is the “good cop, bad cop” interrogation method. A good illustration of how it works is on pages 186-187 and it utilizes the perceptual contrast principle. A general note about “liking” there are several factors like physical attractiveness, familiarity, and association that influence how much we like a person.

You can also see this in sports where we associate ourselves and our identity with our sports team. “We” won the game vs. “they” won the game. As author Isaac Asimov put it: “All things being equal, you root for your own sex, your own culture, your own locality… and 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”. Pg. 200 has an interesting section on how we phrase things based on the performance of our team.

How to say NO! A general approach to neutralizing the “liking” effect is recognizing when has been fabricated. Ask yourself something like “In the 25 minutes i have known this person, have i come to like them more than i expected?” in this case beware. While you shouldn’t react against it, we need to be careful and make sure we separate the person trying to sell you something from the product they are selling.


The power of authority can be seen in the first main example used in the book. It is a widely known study that was done by Stanley Milgram back in the 60s (I believe). Anyone that has taken a psychology class has heard the experiment: there is a teacher and learner. the teacher will test the learner’s memory and administer shocks after every wrong answer to test (as the participant understands it) memory as the shocks intensify. What ended up happening is that as the test progressed, the ‘learner’ who was actually just a researcher in the other room would scream louder and louder. The teacher, taking cues from a researcher in a white lab coat (authority figure) would continue administering the shocks. As the test progressed it was shocking (sorry about the pun) that what the teachers would often complete the whole array of shock levels despite screams of pain from the next room and the learner begging for the study to stop. All it took was a nod from the researcher when the Teacher would question if they should keep going. This book doesn’t go into it, but there are also parallels here with the Stanford Prison Experiment led by Philip Zimbardo where there were guards and prisoners and they took the roles very seriously and with little to no instruction started humiliating and psychologically abusing the prisoners. The prisoners took the abuse with little protest and were submissive and depersonalized. Both experiments show how something like the Holocaust could have possibly happened.

Outside of these studies, we find that when we follow orders of an authority figure it takes the responsibility out of our hands. We do not have to take as much responsibility for our actions if it is coming from a higher up authority. Cialdini says ” we are trained from birth that obedience to proper authority is right and disobedience is wrong.” even in the bible “failure to obey the ultimate authority produced the loss of paradise for Adam, Eve, and the rest of the human race.” We see authority figures in Doctors, and it has been the cause of many medication errors. Con artists will drape themselves with titles, clothes, and trappings of authority. Pg 226 talks about clothing specifically where just by wearing authority attire: guard uniform, people obeyed the requester much more often than when he was not in uniform.

How to say NO! – Always ask “Is this authority truly and expert?” and wonder how an expert stands to benefit from our compliance. It is important to question the legitimacy of the request. There is a good anecdote on page 233-234 about how a waiter was able to get higher tips, receipts during his service. Basically he was able to establish himself as a knowledgeable resource since he would often say something like “that dish isn’t up to par tonight, but may i suggest this one instead?” the one suggested is actually a bit less expensive than what they originally ordered so they trust him as it was not an upsell. The other benefit is that they now trust him as the authority of knowing what is good in the kitchen. So when he suggests wine pairings, appetizers, desserts, etc. they are more compliant AND they will likely give him a better tip!


Scarcity is the principle that if there is a chance the availability might not be there in the future you will be more willing to take the plunge and get in on the deal now. Just think “limited time” “While supplies last” or any kind of “limited number” tactic. It cannot be guaranteed to last long, so you better jump on the opportunity while it lasts. It is also better to talk in terms of what people might lose out on vs what they might gain. The example in the book is ” you can lose several potential health benefits by failing to…” vs. ” you can gain several potential health benefits…” The former is telling you that if you don’t do this it is your loss. One example of the scarcity principle I have been ‘victim’ to is the website WTSO- which is an online wine business that sells wine till sold out- there are a limited number of each bottle for sale and when it is gone its gone for good! Whenever I see something I really want, I order it right away even though I probably wouldn’t have bought it if it weren’t for the scarcity. Another form of the scarcity tactic is the deadline: buy this car today or you may have to buy it at a higher price later or it might not be available for purchase at all. Today I saw an article about the new iPhone that is coming out next week that read something like: “Report: iPhone shortages expected at launch” there is a scarcity principle working here – if you want that new iPhone, you better pre-order that phone as soon as it goes for sale or you might miss out!

Psychological reactance- whenever a freedom is limited or threatened, the need to retain our freedoms makes us desire them significantly more than previously. This principle applies to goods and services as well. People do not like restrictions- especially 2 year olds and teenagers- see pages 246-249. It is the Romeo and Juliet effect of wanting something you are not supposed to have. As we are in the election cycle I would be neglecting the opportunity to talk about Donald Trump in this section. Cialdini says “clever individuals holding a weak or unpopular position can get us to agree with that position by arranging to have their message restricted. The irony is that for such people– members of fringe political groups for example– the most effective strategy may not be to publicize their unpopular views, but publicize the censorship of it.” It seems like Trump has done that a lot in this election which has driven his popularity in certain groups.

Optimal conditions for scarcity influence. The drop from abundance to scarcity has a positive reaction rather than just pure scarcity. It seems like when things become scarce they seem like more sought after. This principle can be seen in the Russians under Gorbachev, where the Russian people got more rights. Then when a coup took place, the Russians who now had a taste of freedom were not going to give it up without a fight. For parents: “research shows that parents who enforce discipline inconsistently produce generally rebellious children. Cialdini also warns that “extreme caution is advised whenever we encounter the devilish construction of scarcity plus rivalry.” see pages 264-266 for story about TV networks bidding on a show against each other.

Final Comment: I think it is important to understand these triggers of influence. What causes our autopilot to trigger? Cialdini’s final argument says “The real treachery, and the thing we cannot tolerate, is any attempt to make their profit in a way that threatens the reliability of our shortcuts.” This summary ended up being a bit more in depth than I hoped but some of these principles had a couple different angles to go after.


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