Agreement or no agreement. ERP correlates of verb agreement violation in German Sign Language

Previous studies on agreement violation in sign languages report neurophysiological responses similar to those observed for spoken languages. In contrast, the two current event-related potential studies (ERP) on agreement violations in German Sign Language sentences present results that allow for an alternative explanation. In experiment A, we investigated the processing of agreement verbs ending in an unspecified location different to the location associated with the referent. Incorrect agreement verbs engendered a posterior positivity effect (220–570 ms post nonmanual cues) and a left anterior effect (300–600 ms post the subsequent sign onset). In experiment B, we investigated a violation of morphologically modified plain verbs. Incorrect plain verbs, articulated to express third person object agreement, engendered a broadly distributed positivity effect (420–730 ms post mismatch onset). We discuss the results under the perspective of enhanced costs for context updating, and argue that sign language agreement is based on phonological and pragmatic principles.