 "Reproductive thinking" is solving a problem deliberately based on previous experience and knowledge.Reproductive thinking proceeds algorithmically—a problem solver reproduces a series of steps from memory, knowing that they will lead to a solution—or by trial and error.Karl Duncker, another Gestalt psychologist who studied problem solving, coined the term functional fixedness for describing the difficulties in both visual perception and problem solving that arise from the fact that one element of a whole situation already has a (fixed) function that has to be changed in order to perceive something or find the solution to a problem.