To further understand how novelty works to enhance creativity, consider what happens when it is removed.
In 1942, Abraham Luchins was curious about what could cause a person to overlook a simple solution to a problem. He designed an experiment that consisted of a series of nine relatively simple puzzles. He set up the experiment such that many of the early problems could be solved using the same approach. This caused participants to develop a mechanized mindset, applying the same solution each time. When they reached the last problem, which required a creative solution, they were unable to see the simple answer in front of them. A control group that was not exposed to the repeated experiences did not experience this blindness.
In other words, the lack of novelty caused the participants to enter into a mechanical state of mind that led them to miss simple and creative solutions they would have otherwise identified. The tendency to become mentally stagnant in the absence of novelty is called the Einstellung effect.
— The Joy of Craft (Claes Zane), Loc. 1896–904