It is well-known that native English speakers sometimes erroneously accept subject-verb agreement violations when there is a number-matching attractor (e.g., *The key to the cabinets were…). Whether bilinguals whose L1 lacks number agreement are prone to such interference is unclear, given previous studies that report conflicting findings using different structures, participant groups, and experimental designs. To resolve the conflict, we examined highly proficient Korean–English bilinguals’ susceptibility to agreement attraction, comparing prepositional phrase (PP) and relative clause (RC) modifiers in a speeded acceptability judgment task and a speeded forced-choice comprehension task. The bilinguals’ judgments revealed attraction with RCs but not with PPs, while reaction times indicated attraction with both structures. The results therefore showed L2 attraction in all measures, with the consistent exception of judgments for PPs. We argue that this supports an overall native-like agreement processing mechanism, augmented by an additional monitoring mechanism that filters explicit judgments in simple structures.

The present study examined whether early immersive L2 exposure in a foreign language learning context can yield long-term advantages in L2 morpho-syntactic sensitivity. Participants were 40 Korean university students with high English proficiency, who had either attended an English kindergarten or begun learning English in a classroom, and a control group of native English speakers. All participants performed a speeded aural grammaticality judgment task that included the following features: articles, subcategorization, plural -s, third-person -s. Results showed that the English-kindergarten group outperformed the late-classroom group in terms of accuracy for ungrammatical sentences, while the two groups did not differ significantly on grammatical sentences and in reaction time measures. The learners altogether scored higher in plural -s and third-person -s compared to articles. While the native speakers showed near-perfect accuracy and fast reaction times, the highly proficient learners were at near-chance level in detecting morpho-syntactic errors during online L2 aural processing.