Before a test, many students reread their notes. In 2006, psychologists Henry Roediger and Jeffrey Karpicke tested that habit.
Students read passages. Some read them again. Others put the page away and wrote down all they remembered, without looking back to check.
Five minutes later, the rereaders recalled more. A week later, those who wrote from memory recalled much more. Yet the rereaders felt more sure they'd remember.