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By Robert B Cialdini, PhD





Robert Cialdini became an “experimental social psychologist” after finding himself to be a “patsy” and an “easy mark” for anyone selling anything. He came to the conclusion that he had been a “sucker” his entire life when he noted the sheer number of unwanted tickets, subscriptions, and such like he had accumulated, leading him to ponder what factors make one person say yes while another may say no under the same conditions. In short, he wanted to uncover the techniques being used to bring about compliance so that he could avoid falling prey to persuasion – arming himself and others with the techniques needed to counteract those of what he calls “compliance professionals.”


My Top 3 Takes from the Summary

  • People make decisions based on very limited snippets of information.

  • Most people are vulnerable to “automatic behaviour patterns.”

  • “There is a group of people who know very well where the weapons of automatic influence lie, and who employ them regularly to get what they want.” The first step in overcoming these weapons is to recognise that they exist.


The Psychology of Persuasion

The author’s “psychology of compliance” research began in an academic environment but soon expanded into a broader scope of investigation when he turned his attention to “compliance professionals.” These are people such as sales operators, recruiters, advertisers, fundraisers, or anyone whose livelihood depends on getting someone to buy into their product or mission. Through studying these professionals, he came to understand the techniques and strategies that get results and the psychology of why people say yes.


A central theme across the strategies is that people tend to make decisions based on very limited snippets of information. The author believes that the fast pace of modern life leaves most of us feeling “rushed, stressed, uncertain, indifferent, distracted, or fatigued” a lot of the time, and this leads to taking the easiest option, or what would appear to be the best option, based on the ready information. However, he makes the point that our tendency to rely on “an isolated piece of information, even though it normally counsels us correctly, can lead us to clearly stupid mistakes – mistakes that, when exploited by clever others, leave us looking silly or worse.”


Making decisions based on quick assumptions is an “automatic behaviour pattern” the author believes most people are vulnerable to. He uses coupons as an example. Many people will automatically assume a coupon represents a good deal, so they’ll buy the apparently discounted item without doing any further research. However, in reality, the coupon may not represent a good deal or a discounted price at all when compared to competitors’ offers. The forces of influence are strong, and we’re bombarded with a constant stream of information, making us increasingly dependent on automatic shortcuts when we’re making decisions, but the problem pointed out by the author is that most of us are unaware of doing it. Not being aware makes us vulnerable to those who know how to exploit automatic behaviour patterns, and “there is a group of people who know very well where the weapons of automatic influence lie and who employ them regularly to get what they want.”

The first step in overcoming these weapons of automatic influence is to recognise that they exist, and the author helps readers to become more aware by sharing his in-depth understanding of six key principles of influence. They are; reciprocation, commitment and consistency, social proof, authority, liking, and scarcity.



The Rule of Reciprocation


The rule of reciprocation is the first principle of persuasion. “We should try to repay, in kind, what another person has provided us,” is such a commonly practised rule that we feel obliged to stick by it. If your child is invited to another child’s birthday party, there’s an automatic obligation to invite the other child to your child’s birthday party. If someone gives you a Christmas or holiday card, there’s an automatic need to give them one in return, or at least add them to your list for next year! Sociologist Alvin Gouldner states that “there is no human society that does not subscribe to the rule” and it’s believed to be an “adaptive mechanism” that made it possible to evolve into an organised society.


It began with the need to share food and skills for survival, and then as people began to specialise in certain types of work, the exchanging of goods also began, and the diversity this brought came to be depended upon. Everyone benefited from these exchanges, so it became an ingrained rule that spread across all members of society. Anyone not conforming to the rule would be held in very low regard, a view that’s still held to this day with non-conformers described as “moochers” – a category most people go to great lengths to avoid being put in.


Those who exploit this rule recognise it as a source of influence. It’s a rule that has significant power, making it hard to avoid. All it takes to feel the power is for someone to give us something – no matter how small – and we instantly feel we owe them something in return. If someone has done something for us, we find it almost impossible to say no when they ask us to do something for them, so exploiters need only do us the tiniest of favours before making their request. A good example of this is a charity sending out a sheet of personalised address labels along with a donation request.


When the rule of reciprocation is used as a tactic, it’s hard not to fall prey to it. The author advises that the only way to resist it is to “defuse its energy” by determining whether you’re entering a situation that’s likely going to lead to giving back much more than was given. It comes down to motivation and learning to recognise when the giver is motivated to exploit the receiver’s automatic need to reciprocate.



Commitment and Consistency


People generally like to appear consistent in their behaviour, and this is something persuasion professionals can exploit. “Foot-in-the-door” and “low-ball” techniques are used to persuade people to make a small, initial commitment before the attractive offer is altered to make it more profitable for themselves.  



Social Proof


To explain this principle, the author suggests looking no further than the litter left behind in a movie theatre. To determine what is acceptable, we often look to see what other people think is acceptable, so seeing a floor littered with empty popcorn boxes can persuade us that this is acceptable behaviour. The same principle can be applied to a motorway on which every driver is exceeding the speed limit – we see social proof of what’s appropriate or acceptable.     


This is something that very often works in society’s favour with people generally behaving in a way that’s right and proper, thereby encouraging others to do the same. However, social proof is a weapon of influence that can leave us “vulnerable to attacks of profiteers” who understand and exploit its power. The author points out that it’s common practice for bartenders to start their shift by placing a few of their own notes and coins into the tip jar, and it’s not unusual for church ushers to do the same before passing the collection basket around the congregation. When people see that other people are putting money in, they see it as the right thing to do – resulting in more tips or a larger collection.


Advertisers employ the same tactic by using the terms “best-selling” or “fastest-growing” to convince people to choose their product, but the pull of social proof is often at its strongest when we’re unsure of ourselves. The author states: “In general, when we are unsure of ourselves when the situation is unclear or ambiguous when uncertainty reigns, we are most likely to look and accept the actions of others as correct.” However, he points out that there’s an inherent problem with this, and it’s known as “pluralistic ignorance.” If we’re uncertain about how to behave in a certain situation, it’s quite likely that others in the social group are also looking for direction on how to behave. An example given is the number of bystanders seen to do nothing when they witness a crime being committed against someone.


Social proof effectively allows us to make decisions on autopilot. We don’t need to delve into the pros and cons of each option, we can simply look to others and choose accordingly. This approach often works well enough, but not always. To protect ourselves from falling victim to social proofing gone wrong, we need to become more sensitive to situations where it’s working with inaccurate information. In so doing, we can switch off the autopilot and make thoughtful, intentional decisions for ourselves.





People buy into people, so they’re much more likely to agree to offers made by people they like. Factors that influence liking include physical appearance, common ground or shared experiences, charisma, cooperation and trust, and a sense of humour.





People often react or respond to commands from the authority in an automated fashion.     



This principle is used liberally in advertising and product promotion. “Opportunities seem more valuable to us when their availability is limited,” so something that might become unavailable soon is grabbed quickly, and the more rare something is, the higher its value. The author explains that humans are incentivised to act when they believe that not acting will result in a potential loss, meaning “people seem to be more motivated by the thought of losing something than by the thought of gaining something of equal value.” This makes the principle of scarcity one that can be exploited by marketers, and he believes salespeople often use it in unethical ways.

To defend ourselves against scarcity tactics, the author suggests we take a logical approach. Scarcity causes an emotional reaction, and emotions get in the way of making logical choices. “By learning to flag the experience of heightening arousal” as a warning sign that we’re being swept up in the emotions triggered by a scarcity tactic, we can take a step back to consider the logic of our decision.





Robert Cialdini not only explains the psychology of why people say yes, but he also details how to apply the insights he shares ethically in business and everyday settings. Everything the reader needs to begin recognising a profiteer’s motivation is set out clearly, and he offers techniques that anyone can learn and practice to protect themselves from falling prey to persuasion.





The principles detailed by the author can be weapons of automatic influence that unscrupulous others might wield over us to get what they want, but the techniques provided to overcome their power give the reader the defence they need to ensure they never again feel they’re an easy mark for anyone selling anything.  This updated version of the original book published in 1984 includes information relating to the progress made in the field of persuasion and influence.    



Bio of the Author


Robert Cialdini is an American psychologist and academic, and expert in the fields of persuasion, compliance, and negotiation. Frequently regarded as the “Godfather of influence,” he is the Regents’ Professor Emeritus of Psychology and Marketing at Arizona State University. He was a visiting professor of marketing, business, and psychology at Stanford University and at the University of California at Santa Cruz. His book has sold over three million copies worldwide and has been translated into over 40 languages.

Influence: The Psychology of Persuasion by Robert Cialdini, New and Expanded edition, 2021, ISBN: 978-0-062-93765-0 is available to buy at Amazon.  


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