There is one book that everyone needs to know on why people do what they do.  It’s called Influence:  The Psychology of Persuasion, by Robert B. Cialdini, and it is a classic.  Cialdini is professor emeritus of psychology and marketing at Arizona State University.  He doesn’t speak often about persuasion, but he has people approved to speak on the subject for him, so if you get a chance to hear a Cialdini clone, do so. 

Cialdini makes persuasion so simple that anyone can understand it.  He posits that there are 6 triggers that influence us to act, to believe, to be persuaded:  reciprocity, commitment, social proof, liking, authority, and scarcity.   Let’s take each one in turn.

Reciprocity.  This idea is baked so deeply in us that it may be innate.  Some studies show babies at a very early stage demonstrating basic forms of reciprocity.  The concept is very simple:  if you do something for me, I feel obligated to do something of similar value in return. 

Commitment.   We humans love to make commitments.  If we make a small commitment, we’re more likely to make a big one to that same idea, person, or cause.  It’s why fundraising people ask you for any amount, no matter how small, because once you start giving, you’re more likely to keep on doing so. 

Social Proof.  We’re a social species.  If we see lots of other people doing something, we’re more likely to do it too. 

Liking.  If you tell me you like me, I’m more likely to be persuaded by something you say.  I find people I like more persuasive than others.  And I tend to like people who are similar to me. 

Authority.  People who are able to invoke authority, any kind of authority, are more likely to persuade me than people who don’t.  We still look up to our leaders, our teachers, our presidents, in spite of the bad press that so many institutions have had of late. 

Scarcity.  If something is scarce, I’m more likely to find it appealing, or persuasive, or attractive.  When there only a few of something, I want them!   

The power of Cialdini’s work lies in its simplicity and clarity.  These 6 impulses are very powerful motivators for us humans.  If you can invoke one or more of them, you will find the persuasive power of your argument, your speech, or your pitch going up.  Way up.  I’m grateful to Dr. Cialdini for making persuasion so clear and easy to understand. 


  1. Nick, I read this last year and it’s one of the most insightful, accessible and plain useful books I’ve ever read. Full of ‘a-ha’ moments and study results you can’t help wanting to tell someone else!

  2. Dave —
    Thanks for your comment. And yes, they do contradict one another. If you read the book, you’ll see how Cialdini explains that humans are persuaded in contradictory ways.

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