Identifying the null subject: Evidence from event-related brain potentials

Event-related brain potentials (ERPs) were recorded during spoken language comprehension to study the on-line effects of gender agreement violations i n controlled infinitival complements. Spanish sentences were constructed in which the complement clause contained a predicate adjective marked for syn tactic gender. By manipulating the gender of the antecedent (i.e., the cont roller) of the implicit subject while holding constant the gender of the ad jective, pairs of grammatical and ungrammatical sentences were created The detection of arch a gender agreement violation would indicate that the pars er had established the coreference relation between the null subject and it s antecedent. The results shelved a complex biphasic ERP (ie., an early neg ativity with prominence at anterior and central sites, followed by a centro parietal positivity) in the violating condition as compared to the non-viol ating conditions. The brain reacts to NP-adjective gender agreement violati ons within a few hundred milliseconds of their occurrence. The data imply t hat the parser has properly coindexed the null subject of an infinitive cla use with its antecedent.