Eureka effect
There seems to be a two phase process. In the first phase, the problem solver gets stuck. Even though they may have explored all the possibilities, they still cannot see the solution. The second phase occurs suddenly and unexpectedly. After a break in mental fixation or re-evaluating the problem, the answer is seen. Insight problems may be difficult to solve because of our mental fixation on the inappropriate aspects of the problem. People have a good memory for Aha! moments. Insight may occur after a break in mental fixation, allowing the solution to appear transparent and obvious.