We investigate the role of awareness in learning non-salient grammar features in a second language during oral interaction. We conducted a learning experiment during which forty-eight adult Dutch-speaking advanced learners of German and a native German-speaking experimenter engaged in a scripted oral dialogue game. The experimenter and learner in turn produced sentences based on pictures eliciting German strong verbs with stem-vowel alternations, a morphosyntactic feature that represents a persistent learning difficulty. While learners in the implicit condition were merely instructed to focus on sentence meaning, learners in the explicit condition were encouraged to also pay attention to and learn from the target structure in the experimenter's input. Although the explicit group achieved higher accuracy scores overall, both groups had similar (absolute) learning gains, showing that oral input provided during interactive exchanges can lead to substantial learning not only under explicit, learning-targeted conditions, but also without an explicit directive to learn.
