Electrophysiological correlates of auditory semantic priming in 24-month-olds

While the N400 component in adults is sensitive to both semantic incongruity and semantic relatedness between stimulus items, the N400 in toddlers has only been shown as an incongruity effect so far. The present event-related potential (ERP) study aimed to investigate whether the N400 in toddlers also indexes semantic relatedness between single words. To address this issue, we developed a unimodal auditory experiment with semantically related and unrelated word pairs, comparable to behavioral semantic priming tasks used with adults. In 24-month-old children, target words which were preceded by a semantically unrelated word elicited a broadly distributed N400-like effect compared to target words which were primed by a semantically related word. For related words, toddlers displayed a negativity in the 200–400 ms interval, indicating facilitated lexical-phonological processing. Results of the present study suggest that the N400 in toddlers is functionally equivalent to the adult component in indexing relatedness as well as semantic incongruity between stimulus items. Moreover, the study demonstrates an instrument for investigating semantic relatedness priming in young children, for whom behavioral tasks are often inappropriate.