Consistently keeping your brand promise employs three concepts of cognitive psychology: consistency principle, confirmatory bias and contrast principle.
Consistency is a primary motivator of human behavior. We crave consistency. By contrast, inconsistency is considered to be undesirable. How would you like to be described as erratic, unpredictable, or unstable? As Dr. Robert Cialdini wrote in his book Influence, Science and Practice, “Like most other forms of automatic responding, (consistency) offers a shortcut through the complexities of modern life. Once we have made up our minds about issues, stubborn consistency allows us a very appealing luxury: We don’t have to think hard about the issues anymore. We don’t really have to sift through the blizzard of information we encounter every day to identify relevant facts.”
We are rationalizers, not rational thinkers. We look for evidence that confirms our beliefs. This is how confirmatory bias works. So, behaving consistently in support of your brand position helps to reinforce your place in the market and in the minds of your customers.
Consistent behavior leverages the contrast principle. We love to compare things: people, products, places, etc. It’s how we think. Consistent behavior helps your customers compare you with alternatives. Bonus: When your competitors appear to be inconsistent, unpredictable, or erratic, you will compare favorably by default.
It's not enough to declare your brand promise. Remember, you are the sum of your actions.