Proceedings of the Annual Meeting of the Cognitive Science Society

This study used a picture–word verification task to examine EEG correlates of lexical and morphological error detection in adult learners (N=36) and fluent bilingual speakers of Turkish (N=18). Prior to EEG, we trained learners on a miniature version of Turkish featuring 36 nouns inflected for case (dative, ablative) and number (singular, plural) presented in pre-recorded spoken dialogues with corresponding pictures. During EEG, participants judged whether the picture matched the inflected Turkish noun. Both groups showed increased negativity to lexical violations (wrong noun) in the 300–500 ms window, consistent with an N400, with a smaller, more prolonged effect in learners. Fluent bilinguals showed an early negativity (100–300 ms) followed by a P600 (500–700 ms) to case and number violations (wrong inflection). Learners failed to show a P600 and exhibited a weak, sustained negativity. Findings suggest that adult second language learners may initially process morphological errors similarly to lexical errors.