When persons disagree: an ERP study of Unagreement in Spanish.

Agreement is one of the main devices used by languages to signal grammatical relations. In this study, we investigated the neurophysiological processing correlates of subject-verb agreement in Spanish using Unagreement, a phenomenon characterized by a person mismatch between subject and verb that nonetheless produces a grammatical pattern. Unagreement was compared to well-formed sentences with full agreement, and ill-formed sentences with a person mismatch. Compared to control sentences, Unagreement produced a left posterior negativity followed by a more central negativity; no P600 effect was observed. In contrast, person violations generated a negativity that was widely distributed over the scalp, followed by a P600 effect. These data suggest that the comprehension of qualitatively different agreement patterns, which could reflect the performance of different processing routines, recruits different neural generators.