The effects of interleaving and rest on L2 vocabulary learning

Studies of learning indicate that presenting materials from multiple categories together (interleaving them) tends to yield better learning vs. presenting categories separately (blocking them). However, the impact of interleaving on language learning is mixed and has not been tested in the context of dual language learning. Here, we taught monolingual English-speaking adults vocabulary in German or Polish across two experiments, interleaving or blocking the languages. In Experiment 1, we observed a benefit of interleaving. Experiment 2 included a break midway through the task, and participants across conditions performed similarly. Our findings indicate that the interleaving advantage observed in other domains extends to dual language learning and may stem from a spacing effect. These findings have implications not only for theories of second language acquisition and dual language learning, but also for developing pedagogical approaches that optimize learning of multiple languages.