Age of acquisition and neurodynamics in French Sign Language (LSF): insights from event-related potentials

Understanding how language modality and psycholinguistic factors such as age of acquisition (AoA) shape language processing is central to the neurobiology of language. This study provides the first event-related potential (ERP) data on semantic and morphosyntactic processing in French Sign Language (LSF) using an online sentence comprehension task. Deaf native and non-native signers were presented with sentences containing semantic or morphosyntactic anomalies. As in spoken and other signed languages, semantic violations elicited a biphasic N400-P600 response. In contrast, morphosyntactic anomalies did not yield a clear Left Anterior Negativity (LAN) effect. No significant impact of AoA was observed on either semantic or morphosyntactic processing. These findings are discussed with respect to visuospatial modality specificity and the relevance of AoA thresholds in assessing language processing in deaf signers.