Electrophysiological evidence of infants' understanding of verbs

When do infants first begin grasping the meaning of verbs? To learn verbs - words that describe actions and events - theorists suggest that infants must employ word segmentation, event processing, and verb-to-action mapping skills. Prior research suggests that many of these skills emerge by approximately 10 months. In the current study, we examined whether 10-month-old infants understand several early verbs. In a novel action-verb pairing paradigm, infants saw videos of everyday actions while hearing matching or mismatching verbs. We tested adults on the same paradigm to verify that action-verb pairs reliably evoked an N400 mismatch effect. Adults showed an N400-like effect over frontal and centroparietal regions. Infants also showed ERP differences between mismatched and matched action-verb pairs, although the pattern differed from adults, with variation in topography and directionality. Infants' ERP response was not related to their receptive or productive vocabulary size. These findings indicate that infants were sensitive to co-occurrences between actions and verbs, reflecting emerging verb understanding and suggesting nascent semantic knowledge. We further consider alternative explanations, including the possibility that the observed ERP differences reflect early action-verb associations that may serve as building blocks for later semantic verb knowledge. These results expand our understanding of infant language acquisition by demonstrating that, by 10 months, infants are sensitive to mismatches between everyday actions and verbs.