We investigated whether adult German native speakers and Dutch-speaking secondlanguage learners of German exploit German regular verb morphology for predictive sentence processing and whether such predictive processing is moderated by working memory capacity and awareness of the predictive cue. In a picture-matching task with visual-world eye-tracking, the participants (first-language group: n = 31; secondlanguage group: n = 30) saw two pictures of action scenes, varying in the number of referents depicted (singular versus plural). Simultaneously, they heard sentences in German in which the verb suffix represented the first reliable cue for grammatical number of the upcoming subject noun phrase. Successful exploitation of this number cue was measured as anticipatory button-press reaction times and eye-movements toward the correct picture, before subject onset. We found significant prediction effects in both the first-language and the second-language group, with anticipatory processing being somewhat faster in the native speakers than in the learners. Faster reaction times on prediction trials were associated with higher working memory scores. Debriefing interviews revealed that all participants had become aware that they could use the verb form predictively, adding further evidence that prediction can be a conscious process.

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.

We investigated the predictive processing of grammatical number information through stem-vowel alternations in German strong verbs by adult first language (L1) speakers and Dutch-speaking advanced second language (L2) learners of German, and the influence of working memory and awareness (i.e., whether participants consciously registered the predictive cue) thereon. While changed stem vowels indicate a singular referent (e.g., /ε/ in fällt3SG, “falls”), unchanged vowels indicate plural (e.g., /a/ in fallt2PL, “fall”). This target structure presents a challenge for L2 learners of German due to its subregularity and low salience. With their eye movements being tracked, participants matched German auditory sentences (VSO order) with one of two pictures, displaying identical action scenes but varying in agent number. The number cue provided by the strong verbs allowed participants to predict whether the upcoming subject would be singular or plural. The analyses revealed significant prediction, measured as predictive eye movements toward the target picture and faster button-press responses. Prediction in the L2 group was weaker than in the L1 group and present in the eye movement data only. Higher working memory scores were linked to faster predictive presses. Approximately half of the participants had become aware of the predictive cue, and being aware facilitated prediction to a limited extent.

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