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Given the complexity of human behavior, it can be difficult to identify factors that affect it so consistently that they can con-fidently be labeled as laws or principles. A notable exception is the testing effect in human memory: Taking a test on learned information, compared with simply restudying it, renders the information more likely to be remembered in the future. The testing effect has been demonstrated in numerous studies over the last century (e.g., Roediger & Butler, 2011; Roediger & Karpicke, 2006a), and it was recently featured in a practice guide for educators as a technique for enhancing student learn-ing that is backed by strong evidence (Pashler et al., 2007). Studies of the testing effect typically involve an encoding phase (e.g., a phase in which participants learn French-English word pairs, such as le chien–dog), followed by an attempt to retrieve the encoded information (le chien–?) or restudy i