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Mental Model: The Contrast Principle

Posted on:December 10, 2017 at 12:00 AM (5 min read)

A quick letter:

“Dear Mother and Dad

Since I left for college I have been remiss in writing and I am sorry for my thoughtlessness in not having written before. I will bring you up to date now but before you read on, please sit down. You are not to read any further unless you are sitting down, okay?

Well, then, I am getting along pretty well now. The skull fracture and the concussion I got when I jumped out of the window of my dormitory when it caught on fire shortly after my arrival here is pretty well healed now. I only spent two weeks in the hospital and now I can see almost normally and only get those sick headaches once a day. Fortunately, the fire in the dormitory, and my jump, was witnessed by an attendant at the gas station near the dorm, and he was the one who called the Fire Department and the ambulance. He also visited me in the hospital and since I had nowhere to live because of the burnout dormitory, he was kind enough to invite me to share his apartment with him. It’s really a basement room, but it’s kind of cute. He is a very fine boy and we have fallen deeply in love and are planning to get married. We haven’t got the exact date yet, but will be before my pregnancy begins to show.

Yes, Mother and Dad, I am pregnant. I know how much you are looking forward to being grandparents and I know you will welcome the baby and give it the same love and devotion and tender care you gave me when I was a child. The reason for the delay in our marriage is that my boyfriend has a minor infection which prevents us from passing our pre-marital blood tests and I carelessly caught it from him.

Now that I have brought you up to date, I want to tell you that there was no dormitory 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 am not infected, and there is no boyfriend. However, I am getting a “D” in American History, and an “F” in chemistry and I want you to see those marks in their proper perspective.

Your loving daughter, Sharon”

Example taken from the book mentioned below, pages 15-16.

The Book

Let’s dive into the book that will give some clarity on the story taken from it above. Two weeks ago, I began, then finished a recommended book from Charlie Munger, Influence by Robert Cialdini. The book breaks down the psychological tendencies and shortcuts our brain uses when making decisions, specifically complying with requests, and how those tendencies are taken advantage of by what Dr. Cialdini calls “compliance practitioners.”

It shows the potential misuse and good reasons the shortcuts exist, meaning we should be wary when they are being used to take advantage of us. These could be sales employees or fundraising gurus. Anyone looking to influence you into an action you may not have considered before the interaction with that person. He gives definitions, examples, and recommendations on how to combat them (when appropriate) as your guide to decision making from this knowledge.

The book fits right in with my project for defining Mental Model Dictionary entries.


The contrast principle affects how we see the difference between two things presented one after the other.

Human’s don’t have an absolute scale for judging the differences between these two items. Sharon, the loving daughter above, used this principle to show her parents that yes she did fail, but it wasn’t even close to being as detrimental as the other potential mistakes she listed. If Sharon would have presented her “D” and “F” without first stating the extreme cases of other potential mistakes, her parents would have definitely read the results in a much harsher light.

She put their perspective into reality by using the contrast principle, and I found the example not only hilarious but also a fabulous demonstration of the principle

The second example I’ll leave you with has nothing to do with parents but focuses on water and our senses.

You fill up three buckets with water, room temperature, hot (not scolding), and cold. You place the room temperature water in the middle of the three and place your hands for 1 minute in the hot and cold buckets on each side. After the minute passes, you take both hands and place them in the room temperature bucket.

The hand from the hot water tells your brain the water is cold, while the hand from the cold water tells you it’s hot! This again proves how your brain uses the relative scale when making comparisons.

Defend Against the Shortcut

When making a decision between two items or if you are buying a 10K+ car and the salesman ask if you want to throw in only a $100 radio, take a breath and ask a couple of questions: “Am I buying this or making this decision in comparison to another option?” “Would I make this decision without an option to compare it with?” “What are the big things I’m comparing to each other?”

Concluding Thoughts

I have added this to my mental model dictionary entries. I hope this helps you recognize and defend against the shortcut when necessary!