If self-examination is more effective than straight studying (once we’re familiar with the material), there must be reasons for it. One follows directly from the Bjorks’ desirable difficulty principle. When the brain is retrieving studied text, names, formulas, skills, or anything else, it’s doing something different, and harder, than when it sees the information again, or restudies. That extra effort deepens the resulting storage and retrieval strength. We know the facts or skills better because we retrieved them ourselves, we didn’t merely review them.
