Confidence in accuracy moderates the benefits of retrieval practice.

The effect of Retrieval Practice refers to the phenomenon that taking a practice test is more effective for learning than re-study, probably due to the benefit from processes underlying successful retrievals during practice. However, it is rarely studied whether other processes (e.g., metacognitive monitoring) during retrieval practice may also play an important role. In two experiments, we examined whether the effectiveness of retrieval was affected by subjects' confidence in their retrieval success. Subjects studied word-pairs and rated their confidence after each practice test trial (cued-recall in Exp.1, multiple choice in Exp.2), or re-study trial. In both experiments, we observed the classic retrieval practice effect. Moreover, in Exp.2, the benefits differed as a function of subjects' confidence in their retrieval performance: the effect of retrieval practice only emerged for high-confidence trials with higher than 56% confidence. In summary, the retrieval practice only facilitates the retention of correct answers with high confidence.