Learning unacceptability: Repeated exposure to acceptable sentences improves adult learners’ recognition of unacceptable sentences

People who learn a new language as adults tend to judge unconventional utterances more leniently than native speakers do, while both groups’ ratings on acceptable utterances tend to align more closely. Experiment 1 confirms this asymmetry with 61 English-speaking undergraduate students enrolled in Spanish classes. The finding that unconventional utterances are particularly hard for learners to fully appreciate raises the possibility that conventional utterances may not statistically preempt unconventional paraphrases for adult learners. To investigate this, we report a preregistered study that provides the undergraduates learning Spanish with three days of exposure to conventional Spanish sentences involving one of two sets of constructions. They performed self-paced reading initially and after exposure. While native Spanish speakers displayed the expected slow-down when reading the unconventional sentences (Exp 2), but the learners did not, regardless of exposure or proficiency. At the same time, judgment data reveal that even beginning learners at the initial assessment explicitly rate unconventional sentences somewhat lower than conventional sentences, and the recognition of unconventionality increases with proficiency. Moreover, the judgment data reveal an effect of statistical preemption, particularly on intermediate learners, as predicted: repeatedly witnessing conventional sentences significantly impacted subsequent ratings of unconventional paraphrases. Collectively, the current findings indicate that adult learners do take advantage of statistical preemption to identify unacceptable sentences, but their ability to recognize unacceptability in real-time lags far behind.