Neural Signatures of Word Learning: How Individual Differences Shape ERPs and Oscillations in The Early Stages of Learning a New Language

A critical component of the language learning process is language control i.e., the management of lexical competition and interference from the existing language. However, how these mechanisms are engaged in early-stage learning remains unclear, particularly regarding individual differences in executive function––more specifically inhibitory control (IC), working memory (WM)––and prior bilingual experience. This study employed a pre/post short-term longitudinal design, where participants completed 10 days of Dutch language learning. Using Event-Related Potentials (ERPs) and Time-Frequency Representations (TFRs), we examined neurophysiological signatures of novel word learning and the role of IC, WM, and bilingual experience. ERP results revealed N400 reductions at post-test, marking successful lexical integration. Greater Bilingual experience predicted greater N400 reductions for noncognates, suggesting more efficient integration. In contrast, stronger IC was linked to smaller N400 reductions for noncognates, indicating greater cognitive effort in managing lexical competition. TFR analyses showed increased theta power for cognates, suggesting enhanced memory encoding, while noncognates elicited greater alpha suppression, suggesting heightened inhibitory control demands. However, individual differences did not significantly modulate these effects, as neither bilingual experience nor IC predicted alpha or theta power at post-test, suggesting that the oscillatory dynamics supporting lexical learning were driven by task demands rather than individual variability. Together, these findings indicate that bilingual experience may facilitate lexical integration, whereas IC may play a critical role in managing interference during word retrieval. The results support models of adaptive language control and highlight the dynamic interplay between linguistic experience, executive function, and lexical competition in word learning.