Are the anterior negativities to grammatical violations indexing working memory?

Anterior negativities obtained when a grammatical rule is violated may reflect highly automatic first-pass parsing processes, the detection of a morphosyntactic mismatch, and/or the inability to assign the incoming word to the current phrase structure. However, for some theorists these negativities rather reflect some aspect of working memory processes. Event-related brain potentials (ERPs) obtained for word category and morphosyntactic violations were directly compared with effects obtained when working memory is particularly demanded (embedding subject- or object-relative clauses), yielding a significant dissociation in terms of topography. Even though, the anterior negativities for grammatical violations vanished when relative clauses were embedded, suggesting that the processes reflected by anterior negativities related to grammatical violations and those related to working memory manipulations, even if different, are placing demands on a common pool of limited resources.