Best Principles of Persuasion You Need to Know

Best Principles of Persuasion You Need to Know

In his excellent book, Influence: The Psychology of Persuasion, Robert Cialdini explains six principles of persuasion.

Sid and Harry owned a small men’s clothing store in the 1930s. They leveraged one of Cialdini’s six principles of persuasion to sell more suits. Their “routine” went like this.  

One of the best principles of persuasion explained

When Sid had a customer for a suit, he’d have him try it on in front of the store’s three-sided mirror. Kneeling down next to the customer’s legs, Sid would feign being hard of hearing, repeatedly asking the customer to speak more loudly. 

When the customer asked the price, Sid would yell to his brother in the back of the store, “Hey Harry, how much is this suit?” 

Harry would look up from his work, squint, peer at the customer and reply with an exaggerated price, perhaps $42 on a $22 suit. Sid would then cup his hand to his ear and yell back, “How much?” In an irritated tone, Harry would respond louder, $42. 

Sid would then turn to the customer and say, “It’s $22.” Many customers would buy the suit and quickly get out the door before Sid discovered what they thought was his mistake. 

What is the best principle of persuasion you need to know?

Putting the ethics issue aside, Harry and Sid knew how to leverage the “contrast principle.” This is how we perceive different things to be more different than they actually are when they are presented one after another.

For example, when you lift a light object followed by a heavy object, the heavy object appears heavier than it otherwise would. When you meet someone with a bubbly personality, followed by someone with a quiet personality, the subdued person appears even more subdued. 

The contrast principle takes advantage of what’s known as a psycho physiological response. It is used by expert marketers and salespeople to increase their closing ratio.

In the history of sales, I don’t believe anyone has used the contrast principle more creatively than the following highly publicized (all over the Internet) letter from a college co-ed to her parents.  

The Contrast Principle of Persuasion Story

Dear Mom and Dad,

It has now been three months since I left for college. I am sorry for my thoughtlessness in not having written before. I will bring you up to date but before you read on you had better sit down. Okay?

I am getting along pretty well now. The skull fracture and concussion I got when I jumped out of my apartment window when it caught fire after my arrival here is pretty well healed. I only spent two weeks in the hospital and now I can see almost normally, and only get these sick headaches once a day. 

Fortunately the fire and my jump were witnessed by Roger, an attendant at the gas station, and he was the one who called the fire department. He also visited me in the hospital, and since I had nowhere to live he was kind enough to invite me to share his apartment with him. He is a very fine man, and we are planning to get married. 

We haven’t set the date yet, but it will be before my pregnancy begins to show. His divorce is final now, and he shares custody of his 3 children.

The reason for the delay in our marriage is that Roger has a minor infection which prevents us from passing our premarital blood tests, and I carelessly caught it from him. This will soon clear up with the penicillin injections I am taking daily.

Now that I have brought you up to date I want to tell you that there was no fire, I did not have a concussion or skull fracture, I was not in the hospital, I am not pregnant, I am not engaged, I do not have syphilis, and there is no divorced man in my life. However, I am getting a “D” in Art and an “F” in Biology and I wanted you to see these marks in the proper perspective.

Your loving daughter,

Jane