Non-Canonical ERP Patterns in Second-language Sentence Processing: Evidence from Syntactic, Semantic, and Phonological Violations in Japanese Learners of English

Background/ObjectivesDespite notable advances in the neural mechanisms of second-language (L2) processing, few studies have systematically compared syntactic, semantic, and phonological processing of L2 within a single experimental design. We investigate the neurocognitive mechanisms underlying L2 sentence processing in native Japanese speakers with intermediate English proficiency. By integrating behavioral measures and event-related potentials (ERPs), we examined how syntactic, semantic, and phonological information influenced sentence comprehension. MethodsTwenty-seven participants completed an auditory sentence judgment task involving English sentences with a syntactic, semantic, or phonological error. ResultsBehavioral results revealed the highest accuracy in the control and semantic conditions, while syntactic and phonological violations led to significantly lower performance, indicating greater processing difficulty in these domains. Among the three linguistic violation types, phonological violations elicited the robust ERP negativities across both time 300-500 ms and 500-800 ms time windows, while syntactic and semantic violations evoked less consistent neural responses in this L2 auditory sentence judgment task. These results suggest that mismatches in expected phonological forms hinder lexical activation, triggering a negativity that resembles an N400 but reflects different underlying processes. ConclusionWe found non-canonical neural response patterns in L2 learners, characterized by sensitivity to phonological anomalies but minimal neural disruption for semantic or syntactic anomalies. The current study contributes to our understanding of L2 sentence processing in native Japanese speakers, particularly by aligning real-time neural responses with behavioral performance. This work offers implications for pedagogical practices and assessment strategies tailored to neurodiverse bilingual populations.