The testing effect as a function of explicit testing instructions and judgments of learning.

During study, people monitor their learning; the output of this monitoring is captured in so-called judgments of learning (JOLs). JOLs predict later recall better if they are made after a slight delay, instead of immediately after study (the delayed JOL effect). According to the self-fulfilling prophecy (SFP) hypothesis delayed JOLs are based on covert retrieval attempts from long-term memory, and successful retrieval attempts in themselves enhance learning (the testing effect). We compared memory for 40 Swahili-Swedish paired associates after a week as a function of three different learning conditions, namely study plus (i) explicitly instructed self-testing, (ii) delayed JOLs, or (iii) less self-testing. We showed that repeated delayed JOLs lead to a memory improvement that does not differ significantly from a comparable condition where the participants are explicitly testing memory, and both the latter groups performed reliably better than a group that self-tested less. The results suggest that delayed JOLs improve long-term retention as efficiently as explicit memory testing and lend support to the SFP hypothesis.