Metacognitive control over the distribution of retrieval practice with and without feedback and the efficacy of learners' spacing choices.

In two experiments on self-regulated learning, participants studied word pairs, made judgments of learning (JOLs), and decided whether to continue practicing after a long or short spacing interval prior to a final cued-recall test. When practice involved restudying, learners preferred a long spacing interval. However, when retrieval practice was involved, learners preferred a short spacing interval for items with low and medium JOLs and a long interval for high-JOL items, regardless of whether retrieval practice was followed by feedback or not. Taking retrieval practice after a short rather than a long spacing interval was efficacious when no feedback followed practice tests, leading to superior recall. Given that retrieval practice was successful, a long spacing interval led to better recall than a short one, but learners were insufficiently accurate in determining which items should be given a long spacing interval for this strategy to be effective. Presenting feedback after retrieval practice did not alter learners' spacing strategy, and the frequent selection of short spacing intervals impaired subsequent recall.