Book Precis: “Influence: The Psychology Of Persuasion” by Robert Cialdini

by Ben Richardson
12th May 2021    4 Minutes

In this summary of “Influence: The Psychology Of Persuasion” by Robert Cialdini, you will learn the six principles of influencing people, how to use them and how to defend yourself against them.

Influence is a fantastic book and the defining study of this subject in our view.

We would strongly encourage you to read it in full if you are looking to improve your influencing skills.

We would also encourage to take a quick look at our previous review of ‘How To Win Friends And Influence People” by Dale Carnegie.

The main idea behind “Influence: The Psychology Of Persuasion” is that humans react predictably to certain triggers. Understanding what they are and how they work will make you less easily manipulated against your will.


Six Principles Of Persuasion

Six principles make people more likely to comply with a request. 

Of course, they won’t all work all of the time. Understanding your audience is the key to knowing which technique will work best.

1. Reciprocation

This principle states that “Humans have the natural urge to repay gifts and favours, which they have received.”

When someone does something for us, we feel an obligation to repay them in some way. We feel obliged to them until we have repaid them in some way.  

Businesses use this principle in giving free samples and small gifts both before and after purchases.

To defend yourself against this principle, learn to identify the true intention of the requester. 

If someone starts to make demands after giving you a gift or doing you a favour, recognize that it was probably not a real favour. 

2- Commitment and Consistency

We tend to remain consistent with our commitments once we have made them.

For example, if you agree to a small request, you are much more likely to agree to a larger request in future. 

One study compared the response rate when asking people to put a large sign encouraging safe driving on their front lawn with people who had previously agreed to put a small three-inch “Drive carefully” sticker in their home window. 

Those who had previously agreed to the small sticker were four times more likely to agree to the large sign on their front lawn.

People wanted to remain consistent with their prior commitments and so were much more likely to agree. 

This rule is the basis of writing down your goals. Writing them down acts as a form of commitment and so increases your chances of sticking with them.

3- Social Proof

People are influenced by what others do. This principle means we tend to follow what others are doing.

When we are unsure how to behave or react in a certain situation, we look to others for answers. We assume that if lots of people are doing something, it must be correct. This is why we tend to buy popular products with lots of customer reviews.

This principle is widely used. 

TV shows add laughter. Hearing others enjoying themselves makes us more likely to enjoy a program. 

Bartenders ‘seed’ their tip jars at the start of the night with some money. Thinking that others have previously tipped a bartender will encourage others to tip them. 

4- Liking

This principle means that we prefer to say YES to the requests of people we know and like.

Friendship and personal relationships have a strong influence on our choices. Hence salespeople trying to strike up a conversation and make small talk before they try to make a sale. 

We tend to like physically attractive people, people who are similar to us, and those that we associate with success, praise, or co-operation. 

5- Authority

This principle states that people are more willing to follow the directions of someone in a position of authority in a hierarchy.  

We obviously are heavily influenced by people senior to us in our work hierarchy. See this article for full details of workplace power.

In addition, we generally trust people with authority whether we are part of their hierarchy or not. Think of the way you respond to doctors, lawyers, business people, police officers, etc. This tends to 

The fact that they have expertise and authority in one area seems to have a ‘halo effect’ on all their decisions. 

This means that it is always wise to ask yourself if someone has real expertise in this specific area. 

6- Scarcity

This principle states that we value and desire things more when they appear less available. 

For example, in an experiment by Stephen Worschel, people rated chocolate chip cookies better when they came from a jar having two cookies rather than a jar having ten cookies.

This principle is used in limited-quantity products, limited-time offers, and auctions.


Is This Ethical? 

The answer is that it depends on your intentions. 

If you apply the above principles in someone’s best interest, then they are ethical. 

For example, the current drive to encourage people to get vaccinated against coronavirus uses some of these techniques, but they are being used in the audience’s best interests. 

However, if you apply them to try to persuade someone to do something that isn’t in their interests (buy a car that isn’t a good fit for them), it is unethical. It is then manipulation not influencing.

Ultimately if someone knew what you were doing, and why you were doing it, would it make them trust you more or less?

That is the acid test for your behaviour.


Learning to influence people ethically is a fundamental career skill for all of us. 

You can use the principles from this book to positively influence others while protecting yourself from deception.

Whenever you meet someone next time, pick one or two principles and give them a try (ethically, of course!). You might well be surprised by the results. 


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