Dictionary meaning of Contrast is “To compare in order to show differences or unlikeness“. We judge stimuli by differences and changes and not by absolute magnitudes. In the excellent book ‘The Psychology of Persuasion – Cialdini’ writes
Each student takes a turn sitting in front of three pails of water – one cold, one at room temperature and one hot. After placing one hand in the cold water and one in the hot water, the student is told to place both in the lukewarm water simultaneously. The look of amused bewilderment that immediately registers tells the story: Even though both hands are in the same bucket, the hand that has been in the cold water feels as if it is now in hot water, while the hand that was in hot water feels as if is is now in cold water.
Ok this is genetically encoded in our system and Why should I care about this? Using this contrast effect we are manipulated subconsciously all the time. Really?
The order in which something is presented matters. I had been to an Electronics store and purchased a Laptop for $400 and an iPod for $275. The total amount came to $675. After the purchase a sales person requested me to buy a printer for just $30. I was about to make the purchase as $30 seemed cheaper than $675. I remembered contrast effect and decided against the purchase.
This happens a lot in real estate. Excerpt From “Seeking Wisdom From Darwin To Munger“
Mary is looking at houses. The real estate broker knows that the house he is trying to sell Mary is in poor shape and a bad area. He starts by showing Mary bad properties in an ugly neighborhood. Afterwards, he takes her to the house he wanted to sell all along. Suddenly this house and the area seem great in comparison to the other house she saw.
Contrast may blind us to change if it happens very slowly. Imagine you are having a cake everyday and it has 350 calories in it. For you to gain 1 pound you need to take in extra 3500 calories. This translates to eating 1 cake every day for the next 10 days. For gaining 10 pounds you need to eat 100 cakes for 100 days. If we had the ability to detect the incremental changes then nobody will be fat.
What should I do
Evaluate people and objects my themselves and not by their contrast.