Influence: The Psychology of Persuasion (THE Book Summary)

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Influence: The Psychology of Persuasion by Robert Cialdini is one of the best psychology books in the world. With over three million copies sold to date and printed in over 30 languages, there’s almost no better book on how to influence people and how not to be tricked. This Influence book summary will cover some key principles from Influence and delve into what I personally liked and disliked about it.

By the end of the summary, you’ll be an expert persuader. You’ll probably also pick up on some tactics that will help you fend manipulation. Let’s dive right in and start exploring the power of persuasion!

Influence Book Summary: Key Takeaways

Here are the main ideas and takeaways from Cialdini’s Influence!


Throughout Influence, readers encounter various persuasion techniques that influencers use to get their way. One of the first ones in the book is reciprocation. Here’s a little personal story that perfectly demonstrates the reciprocity principle:

  • 13-year-old Jeff visits LA, California with his family.
  • One day while walking down the bustling streets of Hollywood, Jeff is intercepted by a DJ dude who hands him a free CD.
  • Jeff tries to give it back to him but the DJ insists that Jeff take it as it’s his gift.
  • Then Jeff happily goes his way, but the DJ stops him and asks if Jeff will give him $5 to fund his musical endeavors.
  • Jeff declines at first, but the DJ dude starts getting upset and tries to get Jeff to agree to the $5 gift: “hey man… I gave you the CD… come on!”
  • A reluctant Jeff reaches into his pocket and fishes out the $5 his parents gave him to spend on food. He hands it over because he feels that the man gave him a concession so he should do the same.
  • Jeff is now $5 poorer, and the DJ dude $5 richer.

If this (or anything similar) has ever happened to you… congratulations, you were the recipient of the reciprocation principle. How it works is that when someone does something for us, we feel obligated to do something in return so we’re much more likely to do what they tell us to do.

This makes sense if it’s just friends and family. BUT the crazy part of it is that the reciprocal principle works EVEN if the gift is forced upon you. Hence all those people in the airports handing out flowers, or the DJs in Hollywood handing out CDs. Turns out that persuading others can happen against their will!

Social Proof

The second technique that an influencer might use to persuade people is social proof. The social proof principle basically states that someone is much more likely to do something or to be persuaded if they see other people doing the desired action.

This is extremely common among lots of marketers. For example:

  • Expert stamps of approval – “This drug is certified by Stanford biomedical doctors.”
  • Celebrity endorsement – *a hair or skin commercial with Jennifer Aniston in it*
  • Wisdom of the crowds – “Over 90% of Americans surveyed say they prefer this brand of shaving cream over its competitors!”

Normally, social proof is a good thing. It gives an idea credibility and is good for when you want to make decisions quick without too much evidence. As with most things though, salesmen and marketers alike have learned how to exploit this to their advantage.

Instead of “everyone else is doing it, so I’ll do it too,” it becomes much more “you THINK everyone else is doing it, so you WANT to do it too.”


This is a super easy one to understand. Likability simply refers to the fact that we are much more likely to say yes if the person making the request is someone we like. There are a few things you can do to make people like you:

  1. Be attractive – ok maybe I lied a little. There isn’t much you can do about your physical attractiveness, but it DOES play a significant factor in whether people do what you say. That being said, make sure to always put your best foot forward when meeting with people. The way you look counts.
  2. Be similar – this one you CAN control to a certain extent. Consumer psychology has found that you’re much more likely to buy from someone (or like someone better) if they have stuff in common with you. A great example of this are the groups and social circles that formed in school: nerds hung around nerds, jocks around jocks, music kids with music kids, etc.

Here are a few tips for being more “likable” and hence upping your persuasive skills:

  • Give people compliments! Everybody loves a compliment.
  • Be close and stay in contact with people you want to build a relationship with.
  • Cooperate with people! Studies have found that working with a colleague or friend towards the same goal helps strengthens bonds of likability.

The more likable you are, the more influential you become. However, you also should be aware that liking someone makes their ability to influence you to increase.


It’s natural social-psychology to believe that scarce things are better. Why do you think so persuasive techniques rely on creating a sense of urgency or limited time?

In Influence, Cialdini describes how the scarcity biases came to be. He describes that in caveman times, it would take a long time for a hunter/gatherer to find some sweet berries (they were scarce). Then, when they found them, they’d get a huge dopamine hit and that wired their brains to believe that scarce and rare things are better.

Human behavior is such that we will always fear loss greater than desiring gain. This could also play a part in our inherent scarcity mindset.

Though it IS normally true that scarce things are better, the modern world has capitalized on this human instinct for profit:

  • A salesman says that the deal is only on for today, and will be gone tomorrow.
  • An advertiser shows that a product is only half off for a limited time (limited time offers).
  • A motivator offers their course to you for ONLY $99, but tomorrow the price shoots back up to $1000.


The principle of consistency and commitment basically states that once we make up our mind or take a stance, we’ll naturally work very hard to justify that stance later on. Even if some part of us knows that we’re wrong. The example Cialdini gives is as follows:

  • A pretty woman asked him to take part in a survey.
  • During this survey, the woman asked about Cialdini’s eating out and recreation habits.
  • To try and impress the lady, Cialdini boasted and exaggerated his routines a bit (saying he was a frequent movie goer and eats ate fancy restaurants all the time).
  • Then the woman proceeded to change topics from the survey and brought up this coupon thing she was selling which would provide tons of discounts to frequent movie-goers and fancy restaurant eaters.
  • Not wanting to appear inconsistent with himself, Cialdini reluctantly bought the coupon thing.

Some more examples of consistency in action are:

  • You tell everyone that you’re going to run a marathon next month, so you work really hard to make it happen because you don’t want to appear inconsistent.
  • You’re beliefs have internally changed from before, but you’ve already made public announcements regarding your politics so you work hard to justify your original views.
  • You maintain your religious faith even as your own belief starts dwindling.

Once you have made up your mind to take a stance, you’ll encounter lots of personal and interpersonal pressures to keep your original position. This is the appeal to consistency when you get it working in your favor.


The final persuading technique that influencers use is employing authority. Put super simply, people like to follow authority figures. Cialdini describes an experiment whereby a random person is brought to a room with a screen and a button. In the room is also a “doctor” (an authority figure) and on the screen is a person strapped up to some device. The doctor then instructs the person to press the button and inflict increasing pain on the person on screen.

With every single person, they went through with the entire experiment, pressing the button over and over, EVEN when the person on screen was yelling for them to stop and screaming in pain. Of course, the person on screen is actually an actor and not experiencing any real pain. But this shows the power of authority: nobody wanted to disobey the “doctor” instructing them.

Examples of other authority figures:

  • Police, firemen, doctors
  • Certain titles like PhD, MBA, etc.
  • Celebrities (hence all the celebrity endorsements and testimonials)

Influence Book Summary: What I Liked and Disliked

When reading Influence, what I loved was that I could clearly see each and every one of Cialdini’s ideas in action. With every principle he mentioned, I could pinpoint a time in my life when it had played out. After reading Influence, I am definitely more aware of all the influencing going around in my life that I was previously ignorant to.

I liked:

  • The informative nature of the book.
  • How Cialdini cites research and studies to back his claims.
  • How the book shows you influence at work all around you.

There really wasn’t anything that I disliked about the book, but something that could have made it better was if Cialdini provides a more “how-to” approach to things. It would have been interesting to see a more “How to Win Friends and Influence People” (Dale Carnegie) approach to the book. There were points in the book when you could pick up some negotiation skills or learn how to motivate others, but these weren’t made explicit. I would have loved it if Cialdini not only wrote his book for the purpose of defending against persuasion but also included the art of persuasion and convincing others.

I wanted more:

  • Ways to influence others and how to persaude others.
  • Methods to increase your persuasive communication.
  • Thoughts on how to be more motivational.
  • Tips on increasing your own influencing skills
  • Tips for negotiating.

Influence Book Summary

Influence is all around us in the world. Every day there are credible people trying to convince other people to do something right. And every day there is also an equal number of manipulative people trying to influence for profit.

In leading psychologist Robert Cialdini’s bestselling book Influence, he describes the various ways that people can be inadvertently influenced against their best wishes. He then goes on to describe what people can do to stop this from happening to them.

Even though at first glance, Influence may appear to be just another psychology book, it’s much more than that. Influence is one of the best business books of all time, and it’s clear to see why. Through reading Influence, you can:

  • Learn how to be more persuasive and get better at influencing others.
  • Become a better communicator.
  • Build rapport with important people in your life.
  • Prevent yourself from being manipulated.
  • Negotiate better and be able to sniff out deception

Some of the key principles mentioned in this Influence book summary are:

  • Reciprocation: humans have a natural give-and-take notion (or empathy) that makes it much more likely for them to do something for you if you give them something first.
  • Social proof: how persuasive you are partly depends on the social influence behind what you’re pushing.
  • Likability: influencing people is easier if you’re likable (charismatic, good looking, have shared similarities).
  • Scarcity: the human brain uses a shortcut that says that rare and scarce things are better.
  • Consistency: humans naturally have a consistent commitment to previous publicly stated beliefs.
  • Authority: we have a tendency to agree with / be swayed by an authority figure.

So… what are you waiting for? Get your hands on a copy of this book and start learning about all the influence and persuasion in your own world!

Thank You!

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Influence book summary

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