Implicit learning in problem solving: The role of working memory capacity

Participants solving the Balls and Boxes puzzle for the first time were slowed in proportion to the level of working memory (WM) reduction resulting from a concurrent secondary task. On a second and still challenging solution of the same puzzle, performance was greatly improved, and the same WM load did not impair problem-solving efficiency. Thus, the effect of WM capacity reduction was selective for the first solution of the puzzle, indicating that learning to solve the puzzle, a vital part of the first solution, is slowed by the secondary WM-loading task. Retrospective verbal reports, tests of specific puzzle knowledge, and a recognition test of potential strategies all indicated that participants were unaware of their knowledge of the puzzle, suggesting that it had been learned implicitly. Concurrent protocols collected from participants supported this conclusion and further suggested that participants were not aware of learning to solve the puzzle as this learning occurred. These results provide evidence that implicit learning depends on WM capacity and that implicit memory can play an important role in problem solving. Starting with the original conception of problem solving as search through a problem space presented by Newell an