Semantic and Syntactic Processing in American Sign Language: Electrophysiological Evidence

Abstract:
Studies of written and spoken language suggest that non-identical neural subsystems mediate semantic and syntactic processing. Event-related brain potential (ERP) studies show that semantic anomalies elicit a posterior bilateral N400, whereas syntactic anomalies elicit a left anterior negativity, followed by a broadly distributed late positivity. While these effects have been found for a variety of semantic and syntactic permutations in spoken languages, there is a paucity of research investigating semantic and syntactic processing in sign languages. Recent evidence suggests that American Sign Language (ASL) depends upon many of the same neural systems as spoken language, but also recruits additional brain regions, primarily in the right hemisphere. In this study, we recorded ERPs from congenitally deaf native signers of ASL as they viewed semantically or syntactically appropriate and anomalous ASL sentences. As with written/spoken sentence processing, semantic violations elicited a central posterior N400 while syntactic violations elicited an early negativity followed by a broadly distributed posterior late positive shift. In contrast to spoken/written language, the distribution of the early negativity varied as a function of the type of syntactic agreement violation, suggesting that both biological constraints and experience shape the development of neural systems important for language.