Learning Through Retrieval Variability: Benefits and Metacognitive Judgments in Foreign-Language Vocabulary Learning.

Variable practice often enhances long-term learning despite increasing difficulty during acquisition. The present study examined whether variable retrieval practice improves foreign-language vocabulary learning and, if so, whether learners' metacognitive judgments reflect its benefits. Participants studied Lithuanian-English word pairs across four study-test cycles under either constant or variable retrieval practice conditions. In the constant conditions, learners consistently retrieved words in either an easy or difficult direction, whereas in the variable conditions, they retrieved in both directions. Following practice, participants predicted their performance on a final test, which was administered after either 10 min (Experiment 1a) or 24 h (Experiment 1b). Results showed that variable retrieval practice improved retention, with the clearest benefits observed when items were later tested in the more difficult retrieval direction after a substantial delay. Although learners' predictions failed to anticipate these benefits, participants appeared to recognize the effectiveness of variable retrieval practice, and many reported using similar study strategies independently. The findings extend the literature on desirable difficulties and variable practice by demonstrating the benefits of variable retrieval practice in foreign-language learning while highlighting a disconnect between learning outcomes and prospective metacognitive judgments. Practically, the results suggest that incorporating variable retrieval practice into vocabulary instruction may enhance retention and promote more effective self-regulated study strategies.